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Tang, Baoyao. "Rockburst control using destress blasting." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0029/NQ64678.pdf.
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Tang, Baoyao 1963. "Rockburst control using destress blasting." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36717.
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One of the main problems facing mining engineers when dealing with deep, hard rock mines is to prevent and/or reduce rockburst hazard around mine openings. Rockburst is a phenomenon which is characterised by violent rock failure. The current research focuses on the assessment and control of rockbursts in deep, hard rock mines.Strainbursts, or strain-type rockbursts, occur in the vicinity of mine openings and are generally provoked by high stress conditions in a brittle rock mass. A new theory has been developed for the assessment of the potential of violent rock failure by strainburst, in underground hard rock mines. In this theory, the mining-induced energy parameters are used to calculate the so-called burst potential index (BPI). When the BPI reaches or exceeds 100%, the method predicts a burst prone situation. One of the most commonly used methods to control strainbursts in hard rock mines is destress blasting.
Motivated by the lack of a dedicated analysis tool to help assess destress blasting, a new, geomechanical model was developed. The technique employs two newly introduced parameters, alpha, a rock fragmentation factor, and beta, a stress dissipation factor, inside the modelled, fractured zone. Implemented in a 3-dimensional finite element code developed by the author, the new model simulates the damage zone induced by destress blasting of a mining face to help evaluate the efficiency of destress blasting. Extensive model verification and parametric studies have been undertaken. The effects of the destress blasting pattern, premining stresses and their orientation, and the two destress blasting factors (rock fragmentation factor, and stress dissipation factor) are studied. The model has been applied successfully to Canadian mine case histories. A detailed case study of a cut-and-fill mine stope involving crown and sill pillar destressing has been carried out. It is shown that the new method can be useful in the assessment of destress blasting in deep drift face development and the crown/sill pillar problems in cut-and-fill mine stopes.
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Michaux, Simon P. "Analysis of fines generation in blasting /." [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19129.pdf.
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Hunter, Graham C. "Economic assessment of open pit blasting." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292230.
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Talhi, Korichi. "Aspects of blasting in surface mines." Thesis, University of Surrey, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280422.
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Paine, Andrew Steven. "The mathematical modelling of rock blasting." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315504.
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Oñederra, Italo Andres. "A fragmentation model for underground production blasting /." [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18377.pdf.
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Larson-Robl, Kylie M. "PORE PRESSURE MEASUREMENT INSTRUMENTATION RESPONSE TO BLASTING." UKnowledge, 2016. http://uknowledge.uky.edu/mng_etds/30.
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Coal mine impoundment failures have been well documented to occur due to an increase in excess pore pressure from sustained monotonic loads. Very few failures have ever occurred from dynamic loading events, such as earthquakes, and research has been done regarding the stability of these impoundment structures under such natural seismic loading events. To date no failures or damage have been reported from dynamic loading events caused by near-by production blasting, however little research has been done considering these conditions. Taking into account that current environmental restrictions oblige to increase the capacity of coal impoundments, thus increasing the hazard of such structures, it is necessary to evaluate the effects of near-by blasting on the stability of the impoundment structures. To study the behavior of excess pore pressure under blasting conditions, scaled simulations of blasting events were set inside a controlled sand tank. Simulated blasts were duplicated in both saturated and unsaturated conditions. Explosive charges were detonated within the sand tank at various distances to simulate different scaled distances. Information was collected from geophones for dry and saturated scenarios and additionally from pressure sensors under saturated conditions to assess the behavior of the material under blasting conditions.
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Zagreba, Sergey Victorovych. "FRAGM a blasting fragmentation model of rocks /." Morgantown, W. Va. : [West Virginia University Libraries], 2003. http://etd.wvu.edu/templates/showETD.cfm?recnum=3120.
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Thesis (M.S.)--West Virginia University, 2003.Title from document title page. Document formatted into pages; contains viii, 175 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 109-119).
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Charlesworth, Cathy. "Impact of blasting vibrations in an urban environment." Thesis, Click to view the E-thesis via HKUTO, 2000. http://sunzi.lib.hku.hk/hkuto/record/B42575503.
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Chillara, Naveen. "Abrasive Blasting Process Optimization: Enhancing Productivity, and Reducing Consumption and Solid/Hazardous Wastes." ScholarWorks@UNO, 2005. http://louisdl.louislibraries.org/u?/NOD,209.
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Thesis (M.S.)--University of New Orleans, 2005.Title from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering"--Thesis t.p. Vita. Includes bibliographical references.
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Bedair, Ayman. "Digital image analysis of rock fragmentation from blasting." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40319.
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A novel digital image analysis technique to measure the size of fragments on the surface of a muck-pile is presented in this thesis. The technique takes into consideration the physical characteristics of fragment representation and measurement problems. Using an adaptive smoothing filter prior to edge detection, each fragment on the surface is represented by a group of edge segments outlining its boundaries. These segments are then grouped to form continuous contours.A multi-layer analysis of the digital image is then formulated where fragments on the surface are grouped into three layers, each of which is categorized by global characteristics and is related to other neighbouring layers by local characteristics. These local relationships between the layers are used to approximate the missing parts of the fragment contour.
An extensive analysis of the sieving process is used in building the relationship between the shape and the size of individual fragments. Using this relation, a new multivariable measure for each fragment is developed. These measures are used in estimating the size distribution of the muck-pile and compared with other existing measurement techniques. This comparison proves the robustness of the technique developed in this thesis.
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Saharan, Mani Ram. "Dynamic modelling of rock fracturing by destress blasting." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84840.
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Rockburst control measures have been in practice with continued efforts for improvements since the beginning of the 20th century. The thesis concentrates on the evaluation of destress blasting, which is an important pro-active rockburst control measure. The concept of destress blasting is based on the fracturing of highly stressed rock mass by detonating explosive charge within it. The concept has been carried out ever since the first reported use in a Canadian coal mine circa the early 1930s. Since then, many mines across the continents have applied this technique using a trial-and-error approach with mixed successes. To date, the application lacks scientific base.The aim of this thesis is to identify the governing mechanisms associated with destress blasting applications. A holistic approach is undertaken, which involves a critical analysis of the reported field evidences, development of a numerical procedure and detailed investigations at the micro-mechanical level to investigate the fracturing of rock under confinement by different types and magnitudes of explosive energy.
A numerical procedure is developed in the thesis that carries promising potential to improve the understanding on rock fracturing by explosive energy as well as provides a platform to develop means for enhancing explosive energy utilization. The procedure is validated with reported field observations.
Analyses of destress blasting is made through dynamic modelling by simulating discrete fractures using the developed procedure. A normalized parameter ℓ ci is introduced to investigate fracturing extent after destress blasts. The investigations revealed that destress blasting produces limited fractures aligned along the principal stresses. The fracturing extent reduces with the increase in the confinement. The study indicates that the current practice of destress blasting seemingly provides more psychological benefits than factual benefits from the desired destressing.
The study also introduces a non-dimensional parameter, betaij , which characterizes destressing effects. The parameter not only adequately explains destressing phenomenon, but also offers clarifications to seemingly inexplicable reported field observations of destress blasting. Local fractures around the boreholes aligned along the principal stresses are found to be the cause of reported local stress concentration and rock stiffening post to destress blasting against the desired stress relaxation and softening.
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Erhie, H. E. "Mathematical aspects of the modelling of rock blasting." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235034.
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Khoshrou, Seyed Hassan. "Theoretical and experimental investigation of wall-control blasting methods." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40161.
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Overbreak and damage to rock walls is one of the most serious problems encountered in blasting operations. Several techniques have been developed to control the undesirable effects of rock blasting. These techniques are collectively known as wall-control blasting methods.The stress distribution around pressurized holes has been numerically evaluated, in order to analyze the mechanism of wall-control blasting methods. The effect of blast geometry and the role of discontinuity on this stress field has also been studied in detail. The results obtained by numerical modelling have been verified by controlled blasting experiments, and further supported by analysis of existing roadcuts on a large scale.
It was found that the mechanism of wall-control blast can be explained by the collision and superposition of the stresses between the holes. A narrow fracture zone between the holes was produced by tensile stresses on the centreline. It is neither necessary nor realistic to assume onset of fractures at the midpoint between holes by reinforcement of the stresses from each hole.
The analysis shows that a burden can be defined as being infinite when the ratio of that to the spacing is greater than unity. For pre-split blasting (infinite burden) in an isotropic and homogeneous material the hole separation could range up to 15 borehole diameters. The decoupling ratio between the explosive charge and the borehole diameter should be smaller than 0.5. This ratio would generally be between 0.2 and 0.3 for pre-splitting (infinite burden), and between 0.3 and 0.4 in the presence of a free face.
A discontinuity parallel to the free face and located at the back of the holes causes high stress levels between the discontinuity and the boreholes, resulting is a shattered one in this region. The presence of a similar discontinuity at the front of the holes leads to considerable overbreak and development of an undamaged "hump" of rock between holes. The effect of a discontinuity oriented normal to the centreline at the midpoint between holes has minimal effect on the blast results. As the angle of the discontinuity with the free face decreases from 90$ sp circ,$ the damage zone between the holes and the discontinuity increases, and the shape of the final wall changes from a smooth face to a corrugated shape. A closed-discontinuity or an open discontinuity cemented with strong filling materials has little effect on the results of the blast. However, as the width of the discontinuity increases, the size of the damage zone also increases. An open discontinuity, 50 mm wide or more, plays a role similar to a free face.
In roadcut blast design, hole deviation is a key parameter in determining the quality of the face. However, consistent hole deviation in the same direction has minimal effect in the result of the blast. This type of deviation is usually associated with bedded rocks, with alternating bands of soft and hard rock on the face. The degree of deviation is dependent, amongst other factors, on orientation, thickness, frequency and the position of these bands.
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Cullen, Michael. "Studies of destress blasting at Campbell Red Lake Mine." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61685.
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Mills, Robert Jeffrey. "Abrasive Blasting with Post-Process and In-Situ Characterization." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/49680.
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Abrasive blasting is a common process for cleaning or roughening the surface of a material prior to the application of a coating. Although the process has been in practice for over 100 years, the lack of a comprehensive understanding of the complex interactions that exist with the process can still yield an inferior surface quality. Subsequently, parts can be rejected at one of many stages of the manufacturing process and/or fail unexpectedly upon deployment. The objective of this work is to evaluate the effect of selected input parameters on the characteristics of the blasted surface characteristics so that a more useful control strategy can be implemented. To characterize surface roughness, mechanical profilometry was used to collect average roughness parameter, Ra. Decreasing blast distance from 6” to 4” gave ΔRa = +0.22 µm and from 8” to 6” gave ΔRa = +0.22 µm. Increasing blast pressure from 42 psi to 60 psi decreased the Ra by 0.33 µm. Media pulsation reduced Ra by 0.56 µm and the use of new media reduced Ra by 0.47 µm. Although blasting under the same conditions and operator on different days led to ΔRa due to shorter blast times, there was no statistically significant variance in Ra attributed to blasting on different days. Conversely, a ΔRa = +0.46 µm was observed upon blasting samples with different cabinets. No significant ΔRa was found when switching between straight and Venturi nozzles or when using different operators.
Furthermore, the feasibility of fiber optic sensing technologies was investigated as potential tools to provide real time feedback to the blast machine operator in terms of substrate temperature. Decreasing the blast distance from 6” to 4” led to ΔT = +9.2 °C, while decreasing the blast angle to 45° gave ΔT= -11.6 °C for 304 stainless steel substrates. Furthermore, increasing the blast pressure from 40 psi to 50 psi gave ΔT= +15.3 °C and changing from 50 psi to 60 psi gave ΔT= +9.9 °C. The blast distance change from 8” to 6” resulted in ΔT = +9.8 °C in thin stainless steel substrate temperature. The effects of substrate thickness or shape were evaluated, giving ΔT= +7.4 °C at 8” distance, ΔT= +20.2 °C at 60 psi pressure, and ΔT= -15.2 °C at 45° blasting when comparing thin stainless steel against 304 stainless steel (thick) temperatures. No significant ΔT in means was found when going from 6” to 8” distance on 304 stainless steel, 40 psi and 60 psi blasting of thin SS, as well as angled and perpendicular blasting of thin SS. Comparing thick 304 and thin stainless steel substrates at a 6” blast distance gave no significant ΔT.Master of Science
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Haghighi, Rahim G. "Investigation of relationship between rock fragmentation and burden stiffness ratio in confined bench blasting /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487260531954569.
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Ahmed, Lamis. "Models for analysis of shotcrete on rock exposed to blasting." Licentiate thesis, KTH, Betongbyggnad, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-93716.
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In underground construction and tunnelling, the strive for a more time-efficient construction process naturally focuses on the possibilities of reducing the times of waiting between stages of construction. The ability to project shotcrete (sprayed concrete) on a rock surface at an early stage after blasting is vital to the safety during construction and function of e.g. a tunnel. A complication arises when the need for further blasting affects the hardening of newly applied shotcrete. If concrete, cast or sprayed, is exposed to vibrations at an early age while still in the process of hardening, damage that threatens the function of the hard concrete may occur. There is little, or no, established knowledge on the subject and there are no guidelines for practical use. It is concluded from previous investigations that shotcrete can withstand high particle velocity vibrations without being seriously damaged. Shotcrete without reinforcement can survive vibration levels as high as 0.5−1 m/s while sections with loss of bond and ejected rock will occur for vibration velocities higher than 1 m/s. The performance of young and hardened shotcrete exposed to high magnitudes of vibration is here investigated to identify safe distances and shotcrete ages for underground and tunnelling construction, using numerical analyses and comparison with measurements and observations. The work focuses on finding correlations between numerical results, measurement results and observations obtained during tunnelling. The outcome will be guidelines for practical use. The project involves development of sophisticated dynamic finite element models for which the collected information and data will be used as input, accomplished by using the finite element program Abaqus. The models were evaluated and refined through comparisons between calculated and measured data. First, existing simple engineering models were compared and evaluated through calculations and comparisons with existing data. The first model tested is a structural dynamic model that consists of masses and spring elements. The second is a model built up with finite beam elements interconnected with springs. The third is a one-dimensional elastic stress wave model. The stress response in the shotcrete closest to the rock when exposed to P-waves striking perpendicularly to the shotcrete-rock interface was simulated. Results from a non-destructive laboratory experiment were also used to provide test data for the models. The experiment studied P-wave propagation along a concrete bar, with properties similar to rock. Cement based mortar with properties that resembles shotcrete was applied on one end of the bar with a hammer impacting the other. The shape of the stress waves travelling towards the shotcrete was registered using accelerometers positioned along the bar. Due to the inhomogeneous nature of the rock, the stress waves from the blasting attenuate on the way from the point of explosion towards the shotcrete on the rock surface. Material damping for the rock mass is therefore accounted for, estimated from previous in-situ measurements. The vibration resistance of the shotcrete-rock support system depends on the material properties of the shotcrete and here were age-dependent properties varied to investigate the behaviour of young shotcrete subjected to blast loading. The numerical simulations require insertion of realistic material data for shotcrete and rock, such as density and modulus of elasticity. The calculated results were in good correspondence with observations and measurements in-situ, and with the previous numerical modelling results. Compared to the engineering models, using a sophisticated finite element program facilitate modelling of more complex geometries and also provide more detailed results. It was demonstrated that wave propagation through rock towards shotcrete can be modelled using two dimensional elastic finite elements in a dynamic analysis. The models must include the properties of the rock and the accuracy of the material parameters used will greatly affect the results. It will be possible to describe the propagation of the waves through the rock mass, from the centre of the explosion to the reflection at the shotcrete-rock interface. It is acceptable to use elastic material formulations until the material strengths are exceeded, i.e. until the strains are outside the elastic range, which thus indicates material failure. The higher complexity of this type of model, compared to the engineering models, will make it possible to model more sophisticated geometries. Examples of preliminary recommendations for practical use are given and it is demonstrated how the developed models and suggested analytical technique can be used to obtain further detailed limit values.Inom undermarks- och tunnelbyggande leder strävan efter en mer tidseffektiv byggprocess till fokus på möjligheten att reducera väntetiderna mellan byggetapper. Möjligheten att projicera sprutbetong på bergytor i ett tidigt skede efter sprängning är avgörande för säkerheten under konstruktionen av t.ex. en tunnel. En komplikation uppstår när behovet av ytterligare sprängning kan påverka härdningen av nysprutad betong. Om betong, gjuten eller sprutad, utsätts för vibrationer i ett tidigt skede under härdningsprocessen kan skador som hotar funktionen hos den hårdnade betongen uppstå. Kunskapen i ämnet är knapphändig, eller obefintlig, och det finns inga etablerade riktlinjer för praktisk användning. Slutsatsen från tidigare undersökningar visar att sprutbetong kan tåla höga vibrationer (partikelhastigheter) utan att allvarliga skador uppstår. Oarmerad sprutbetong kan vara oskadd efter att ha utsatts för så höga vibrationsnivåer som 0,5–1 m/s medan partier med förlorad vidhäftning till berget kan uppträda vid vibrationshastigheter högre än 1 m/s. Funktionen hos ung och hårdnande sprutbetong som utsätts för höga vibrationsnivåer undersöks här för att identifiera säkra avstånd och sprutbetongåldrar för undermarks- och tunnelbyggande, med hjälp av numeriska analyser och jämförelser med mätningar och observationer. Arbetet fokuserar på att finna samband mellan numeriska resultat, mätresultat och observationer från tunnelbyggande. Det slutliga resultatet kommer att vara riktlinjer för praktisk användning. Projektet omfattar utveckling av sofistikerade dynamiska finita elementmodeller för vilka insamlad information och data kommer att användas som indata för det finita elementprogrammet Abaqus. Modellerna utvärderades och förfinats genom jämförelser mellan beräknade och uppmätta resultat. Först jämfördes befintliga enkla mekaniska, ingenjörsmässiga modeller vilka utvärderades genom beräkningar och jämförelser med befintliga data. Den första modellen är en strukturdynamisk modell bestående av massor och fjäderelement. Den andra är en modell uppbyggd av finita balkelementet sammankopplade med fjädrar. Den tredje är en endimensionell elastisk spänningsvågsmodell. Spänningstillståndet i sprutbetongen närmast berget, utsatt för vinkelrätt inkommande P-vågor simulerades. Resultat från icke-förstörande laborationsprovningar användes också som testdata för modellerna. Experimentellt studerades P-vågsutbredning i en betongbalk med egenskaper likvärdiga med berg. Cementbruk med egenskaper liknande sprutbetong applicerades på balkens ena ände medan en hammare användes i den andra. Formen hos den genererade spänningsvågen som propagerade mot sprutbetongänden registrerades med accelerometrar utplacerade längs balken. På grund av bergets inhomogena karaktär kommer spänningsvågorna från sprängningen att dämpas ut på vägen från detonationspunkten till sprutbetongen på bergytan. Materialdämpningen hos bergmassan måste därför beaktas och kan uppskattas utifrån resultat från fältmätningar. Vibrationståligheten hos förstärkningssystem av sprutbetong och berg beror av materialegenskaperna hos sprutbetongen och i den här studien varierades de åldersberoende egenskaperna för att undersöka beteendet hos nysprutad och hårdnande sprutbetong utsatt för sprängbelastning. De numeriska simuleringarna kräver realistiska materialdata för sprutbetong och berg, som t.ex. densitet och elasticitetsmodul. De beräknade resultaten var i god överensstämmelse med observationer och mätningar i fält plats, och med de tidigare numeriska resultaten. Jämfört med de mekaniska modellerna kan ett sofistikerat finit elementprogram underlätta modellering av mer komplexa geometrier och också ge mer detaljerade resultat. Det visades att vågutbredning genom berg och fram emot sprutbetong kan beskrivas med tvådimensionella elastiska finita element i en dynamisk analys. Modellerna måste beskriva bergets egenskaper och noggrannheten i dessa parametrar kommer att ha stor inverkan på resultaten. Det kommer att vara möjligt att beskriva vågutbredningen genom bergmassan, från detonationspunkten till reflektionen vid bergytan, det vill säga gränssnittet mellan sprutbetong och berg. Det är acceptabelt att använda elastiska materialformuleringar tills materialet elasticitetsgräns överskrids tills töjningar utanför det elastiska området nås, vilket därmed indikerar materialbrott. Den högre komplexiteten hos den här typen av modell, jämfört med de mekaniska modellerna, kommer att göra det möjligt att analysera mer komplexa tunnelgeometrier. Exempel på preliminära rekommendationer för praktiskt bruk ges och det visas hur de utvecklade modellerna och den föreslagna analysmetodiken kan användas för att fastställa ytterligare detaljerade gränsvärden.
QC 20120427
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Johansson, Daniel. "Fragmentation and waste rock compaction in small-scale confined blasting." Licentiate thesis, Luleå tekniska universitet, Geoteknologi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17100.
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Sub-level caving (SLC) is an important mass mining method, used at LKAB e.g. The caved rock or debris at the SLC interface reduces the fragmentation and the swelling of the blasted ring and it dissipates the explosive energy. These phenomena may immobilize the blasted ring, causing ore losses. There are two major factors that influence the mobilization of the blasted ring, fragmentation and swelling of the blasted material. The caving process is influenced by also the stiffness of the waste rock, which is dependent in some way by the compaction that the blast ring contributes to. To investigate these phenomena in large-scale is very difficult and nearly impossible due to the mining method itself. Therefore model scale tests have been made to understand the mechanisms of rock breakage and therefore fragmentation under relatively confined conditions. To minimize geometrical and geological effects, tests were conducted on Ø140 mm cylinders of magnetic mortar, which fractures like magnetite but is a less variable material. The cylinders were placed inside an Ø300 mm steel or plastic cylinder and confined by packed aggregate. PETN cord with different strengths in a centred hole gave a specific charge between 02 and 2.6 kg/m3. This thesis describes and discusses how fragmentation and compaction, the reverse of swelling, depend on the specific charge for different types of debris confinement. Four different types of debris have been tested and for one of them a confining pressure of about 0.42 or 0.86 MPa was induced by a slotting and bolting of the steel cylinder. The results show both that the passive confinement makes the fragmentation considerably coarser than from free cylinders and that the properties of the debris have a strong influence on both fragmentation and swelling. The effect of the confining pressure was relatively small however and interpreted mainly by changes in debris porosity. The magnetic mortar and the non-magnetic aggregate allow for post-blast magnetic separation. The setup provides extremely repeatable results. The fragmentation of the blasted mortar and the aggregate plus the compaction (reverse swelling) of the confined mortar cylinders have been measured. Free mortar cylinders were used as a reference To date, more than 160 cylinders have been shot and evaluated in terms of fragmentation or compaction. It has been clearly shown that the test set-up is robust and gives repeatable results. The small scale tests are a first step to increase the understanding of confined blasting as in sub-level caving. By using the acoustic impedance between the blasted material and the confining debris, a relationship for both fragmentation and compaction have been found depending on material, specific charge and physical properties of the debris. Regression analysis has been used for both tasks, where the two statistical hypotheses clearly have good agreement with actual data i.e. the prediction models can forecast both the fragmentation and compaction for this set-up with reasonable accuracy The results can be comparable with confined blasting in large scale, this both that it have representative design parameters that fulfil in many ways the scaling laws and the second is that it can be linked to other comparisons between large-scale and small-scale, where the similarities have been shown. The results from this thesis have shown to be a good input for numerical modelling, where confined blasting is one of the new tasks. This will be a part of the coming work to optimally design SLC-rings for maximum output of ore.Skivrasbrytning är en viktig storskalig brytningsmetod som bl.a. tillämpas vid LKAB:s gruvor i Kiruna och Malmberget. Kontaktytan mellan malm och rasmassor reducerar fragmenteringen och hindrar svällningen av den sprängda malmkransen dvs. malmen är inspänd. Detta fenomen kan förhindra rasmassornas rörlighet, vilket i sin tur kan leda till malmförluster. En annan viktigt faktor i processen är även vilken styvhet rasmassorna har, vilket kan relateras till hur kompakterade de är. Ju mindre styvhet, desto mer rörliga är massorna. Om massorna inte är malm, så finns risken att malmen späds ut dvs. en ökad gråbergsinblandning.Att studera detta fenomen under storskaliga förhållanden är mycket svårt, nästintill omöjligt på grund av brytningsmetoden själv. Därför har sprängförsök utförts i modellskala med målet att få bättre förståelse av just inspänningens påverkan på fragmentering och svällning. Genom att använda cylindriska och icke geologiska provmaterial (magnetitbruk), så har de strukturers och randeffekter påverkan kunnat minimeras.Provcylindrarna hade diametern 140 mm och placerades i stålcylinder med diametern 309 mm alternativt ett plaströr med diametern 293 mm. Stålcylindern användes vid undersökningar av fragmenteringen och plaströret användes vid att mätning av kompakteringen av rasmassorna/svällningen av det spränga materialet. I spalten mellan dessa cylindrar, så fylldes rasmassor med varierade egenskaper. Egenskaper som beskrev rasmassorna var beroende på deras hållfasthet, packningsgrad och styvhet. Det sprängämne som användes till majoriteten av försöken var pentylstubin, som placerades i ett centrerat hål inne i provcylindern. Pentylstubin finns med flera olika styrkor, vilket gav för dessa försök ett spann på den specifika laddningen från 0,2 till 2,6 kg/m3. Eftersom magnetitbruk användes, så kunde kompletta fragmenteringskurvor från provcylindrar och uppkrossningskurvor hos rasmassorna fås genom magnetseparering.Resultaten visar att inspänningen till stor grad ökar styckefallet jämfört med fria förhållanden med samma laddningsmängd dvs. ingen inspänning alls. Egenskaperna hos rasmassorna hade likaså stor inverkan på styckefallet. Dagens malmproduktion i bl.a. LKAB går ytterligare mot djupet, vilket i sin tur ökar på trycket på rasmassorna. För att simulera hur ett ökat tryck påverka fragmenteringen, så modifierades stålcylindern till att kunna utföra ett tryck på rasmassorna och därtill den cylinder som skulle sprängas. Denna effekt visades sig dock vara marginell med avseende på medelstyckefall och skillnaderna kunde relateras till rasmassorna egenskaper (porositetsminskning i detta fall). Dock visade det sig att trycket påverkade formen på det fragmenterade materialet, vilket kan vara av vikt för rasflödesmodellerTills dags datum har mer än 160 cylindrar sprängts och utvärderats i avseende på fragmentering eller kompaktering. Försöksupplägget har visat sig vara robust och gett repeterbara resultat. Genom att sedan använda sig av impedansskillnader mellan det sprängda materialet och rasmassorna, så har ett samband visats beroende på provmaterial, specifik laddning och fysikaliska egenskaper hos de omgivande massorna. Regressionsanalyser har gjorts för båda utvärderingarna och de två statistiska hypoteserna som testats har visat sig har bra överenskommelse med uppmätta data.Resultaten kan bli jämförbara med storskaliga förhållanden, både eftersom designen av försöken till stor del är likvärdiga, speciellt för en testad egenskap hos rasmassorna där skallagarna har tagit i beaktande. Ytterligare en sak som talar för att man kan jämföra resultaten med storskaliga förhållanden, är att redovisade data i denna avhandling har anknytning till tidigare försök där likheter mellan storskaliga försök och modellförsök kunnat visas.Denna avhandling kan vara till hjälp likaså vid validering av de numeriska modeller som just har fokus på sprängning under inspända förhållanden.
Godkänd; 2008; 20080905 (ysko)
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Lindsey, Douglas E. "An investigation of blasting criteria for structural and ground vibrations." Ohio : Ohio University, 1989. http://www.ohiolink.edu/etd/view.cgi?ohiou1182441854.
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Chang, Manseok. "Damage criteria for high way bridges subjected to blasting excitations." Ohio : Ohio University, 1990. http://www.ohiolink.edu/etd/view.cgi?ohiou1183487539.
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Loeb, Jeffrey Thomas. "Regulatory mitigation of the adverse environmental effects of urban blasting." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42948.
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Blasting techniques and protective measures exist that can mitigate risks associated with flyrock and the nuisance of vibration, and overpressure. However, these are often misused or not used because there are no prescriptive regulatory requirements and typically, urban blasting guidelines do not exist. The relationship between the increasingly negative publicity that the urban blasting industry receives and the existing state of regulatory control on blasting in urban environments is presented. Specific research points include: 1. Incidents of flyrock, vibration and overpressure related to blasting operations in urban environments were investigated across Canada but with a focus in the province of British Columbia. 2. A comparison and evaluation of blasting regulatory control in Canada, United States and Australia are presented. 3. An analysis of incidents and complaints, complemented with the approaches used to regulate blasting was performed. 4. Provincial and municipal regulators, blasting contractors, and blasting consultants were interviewed to seek advice on practical amendments to Canadian regulations to mitigate the adverse environmental effects of urban blasting. At the provincial level, it is recommended that an amendment to WorkSafeBC’s Blasting Regulations Part 21.66 (1) to hold the blasting company, in addition to the blaster, responsible for flyrock incidents will reduce incidents. At the municipal level, it is suggested that a proposed harmonized blasting bylaw, that includes an education plan in the form of an informative pamphlet, will reduce the number of vibration, and overpressure complaints. This blasting bylaw coupled with delivery of the pamphlet should minimize (i) risk to a municipality, (ii) cost and time commitment to a municipality, (iii) complaints made by concerned residents, and (iv) adverse effects on blaster productivity.
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Prasad, Umesh. "Energy utilisation in comminution and its application to rock blasting." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26412.
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Since blasting is a comminution process, the feasibility of establishing a correlation between the Bond rod mill work index (kWh/t) and some easily measurable physico-mechanical properties relevant to blasting was investigated. Further, the concept of operating blast work index and its potential applications were explored. Four different rock types and a well documented case study of two blasts were selected for this study.The work index is found to be uncorrelated with the density and unconfined compressive strength, slightly related with tensile strength, and well correlated with dynamic rock properties, especially the P-wave velocity and the bulk modulus. The standard deviation in measured compressive and tensile strength values is found to be very high, compared to their seismic and dynamic elastic properties.
The case study encompassed two blasts with identical blast-patterns and rock type consuming almost the same amount of explosive (kg/t) but with very different specific blast energies (MJ/t). The agreement between operating work index of the two blasts (13.4 kWh/t vs. 13.1 kWh/t) and laboratory work index (17.0 kWh/t) was modest (within 30%). The operating work index corresponding to either blast has been used to predict the product size (P$ sb{80}$) of the other. The choice of feed size (F$ sb{80}$) was discussed; whereas the previous researchers had used the theoretical value of infinity, the use of much smaller value, the average of effective burden and spacing, was proposed. This concept is used in a proposed method to estimate blasting energy requirements as a function of blast geometry, rock type and desired product size. Future test work that would provide a data base and validation for this concept is described.
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Jackson, Brett Christopher. "TOTAL COST OPTIMIZATION FOR CONTOUR BLASTING IN THE APPALACHIA REGION." UKnowledge, 2015. http://uknowledge.uky.edu/mng_etds/20.
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This thesis recounts the study of contour blasting practices in the Appalachia coal region. Contour blasting practices vary widely and problems are often encountered. Several different sites were visited and contour blasting practices at each were studied. Based on the information gathered, a comprehensive plan was developed for blasting operations to follow and then was tested and compared to an example of blasting practices without use of the plan. The blasting practices were compared by examining monthly production rates as well as a time study to measure the efficiency a contour blast could be loaded and hauled away and a cost per cubic yard of material determined. The plan was found to be successful in keeping safety while increasing profitability. However, the plan will need to be backed and understood by management in order to achieve the same success.
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BASTOS, MARCELO SOUZA MAGALHAES. "DAMAGE QUANTIFICATION OF DENTINE SURFACE AFTER BLASTING WITH SODIUM BICARBONATE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8201@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROEste trabalho apresenta os resultados da quantificação do dano em superfícies dentinárias de molares humanos após jateamento com bicarbonato de sódio. Após a seleção e preparação das amostras, as mesmas foram divididas em dois grupos experimentais (Grupo Controle e Grupo de Jateamento). Inicialmente, mediu-se a rugosidade e dureza local (microdureza) do Grupo Controle, adotadas como valores padrão. Em seqüência, as amostras do Grupo de Jateamento foram submetidas à diferentes condições de jateamento, variando-se os parâmetros granulometria das partículas de bicarbonato de sódio (60 e 200 mesh), vazão da mistura água-bicarbonato de sódio-ar (mínima e máxima) e tempo de instrumentação (15 e 30 segundos). Finalmente, mediu-se a rugosidade e microdureza da região da dentina, bem como a área de depressões superficiais formada pelo jateamento. Os resultados mostraram que todas as condições de jateamento provocaram danos na região da dentina, caracterizados por aumentos de rugosidade e dureza, bem como o aparecimento de cavidades nesta região. A vazão mínima da mistura água-bicarbonato de sódio-ar provocou maiores rugosidades e endurecimentos na região dentinária. Por outro lado, as maiores áreas de cavidades na mesma região foram criadas por partículas menores quando jateadas com vazão máxima da mistura água-bicarbonato de sódio-ar
This work presents the results concerning the damage quantification in human molar dentine surfaces after blasting with sodium bicarbonate. After selection and preparation, the samples were divided into two experimental groups (Control Group and Blasting Group). Initially, the roughness and local hardness (microhardness) of the Control Group were measured and adopted as standard values. In the sequence, the samples of the Blasting Group were subjected to different blasting conditions, making change in parameters as grain size of the sodium bicarbonate particles (60 and 200 mesh), water-sodium bicarbonate-air mixture outflowing (minimum and maximum) and instrumentation time (15 and 30 seconds). Finally, the roughness and the microhardness of the dentine region were measured, as well as the area of the surface depressions due to blasting. The results showed that all blasting conditions caused damages in the dentine region, characterized by an increase in roughness and microhardness, as well as the creation of cavities in this region. The minimum water-sodium bicarbonate-air mixture outflowing was associated with larger values of roughness and microhardness in the dentine region. On the other hand, larger areas of cavities in the same region were created by smaller particles of sodium bicarbonate when blasted with maximum water-sodium bicarbonate-air mixture outflowing.
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Potana, Sandhya Naidu. "Environmental performance of copper slag and barshot as abrasives." ScholarWorks@UNO, 2005. http://louisdl.louislibraries.org/u?/NOD,216.
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Thesis (M.S.)--University of New Orleans, 2005.Title from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering"--Thesis t.p. Vita. Includes bibliographical references.
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Bezuidenhout, Hendrik Cornelius. "The development of a new non-metallic explosives initiator." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2576.
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Thesis (DTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017.Explosives are used to achieve certain functions in diverse environments, including mining, civil construction, military operations, and demolition. Irrespective of the application, the basic principle of augmentation of energy applies. Energy in the form of heat and shock is released by an initiator. This energy is taken up by an intermediary charge, which in turn propagates to the main explosive charge. Ultimately the energy released from the main explosive charge performs the functions. Initiating systems make use of this exact principle within their own boundaries of confinement. The rate at which this energy transfer takes place as well as the magnitude of augmentation is to a great extent influenced by parameters such as the type of confinement, chemical composition and density of the explosives, as well as other environmental conditions. Traditionally lead azide has been used as the primary explosive component in an initiating system. Pressure from international environmental agencies has discouraged the use of heavy metals in commercial products. Nano-porous silicon has been used together with an oxidiser to form an explosive mixture. The literature has shown that nano-porous silicon-based explosive formulations are sensitive enough to pick up from the energy released by the pyrotechnic composition. The reaction of such nano-porous silicon explosive compositions changes from a deflagration to a detonation. However, their ability to initiate the base charge of an initiating system has not yet been demonstrated. A nano-porous silicon/nitriminotetrazole-based explosive system was developed and characterised. A relative reactivity concept was developed and successfully used to further characterise the new nano-porous silicon explosive. The lead azide primary explosive replacement has been shown to be sensitive enough to pick up from the heat output generated by the delay composition and strong enough to reliably initiate the base charge explosive. The performance of the base charge explosive is primarily a function of its density and the confinement it is used in. An explosive system was developed whereby the base explosive was coated with a polymer to give it compressible characteristics. A ballistic ball indentation evaluation method was developed and effectively applied to characterise explosive performance behaviour under various conditions, including density and confinement. Explosive pellets, pressed separately and at a higher density, have been shown to increase performance compared with explosives consolidated inside an aluminium casing.
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Woldeselassie, Bruck Haile. "The Effect of Blasting in Layered Soils, Example from Finneidfjord, Norway." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18501.
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A case study on the role of blast vibration on the 1996 Finneidfjord landslide was carried out. This catastrophic landslide which claimed four lives has been under investigation during the past decade. The study area has been developed as natural laboratory and different field and lab investigation have been carried out in the process of understanding the event bed. The mechanically weak layer that the landslide used as a slip surface is found 2.8-3.1m below the sea bed and is composed of loose sand layer sandwiched between two very low permeable clay layers. The main focus herein is the effect that the vibration had on the sand layer and see if the energy from it was able to generate an excess pore water pressure or even liquefaction.Literature review on different models for calculating energy from vibration and liquefaction susceptibility is done. The energy calculation models require inputs that involve laboratory test therefore they are to be referred for the future work. As for the liquefaction susceptibility; data from the field and laboratory investigation are utilized and are used for the simple liquefaction susceptibility analysis.Utilizing a FEM software QUAKE/W, part of the GeoStudio software suite, the amount of excess pore water pressure generated due to the dynamic loading from the blast is analyzed. Keeping the parameters of the other materials in the model constant and changing the damping ratio of the sand layer ranging from 1% to 33%, and by changing the geometry of the model an excess PWP in the range of 0.4KPa to 6KPa is obtained. As for the liquefaction susceptibility analysis using the cyclic stress ratio, a factor of safety of 2.3 was obtained leading to the conclusion that liquefaction was not the cause of the landslide. With the excess PWP obtained from the dynamic analysis plus a reading from a piezometer installed close to the slide scar, slope stability analysis is done with a software tool called SLOPE/W which again is part of the GeoStudio software suite. The initial stability condition of the slope, only considering the excess PWP from the piezometer reading, was on the verge of failure. The analysis carried out, considering the result from the dynamic analysis, gave a factor of safety less than one. Based on the results one might conclude that the excess PWP caused the landslide but given the fact that some very important parameters which should be obtained from a lab investigation are lacking, the study can only show that there is a possibility for generation of an excess PWP and for a slope already on the verge of failure, reduction in the effective stress caused by the excess PWP could lead an incidence like in Finneidfjord. Future work for improving the study and some recommendations that could help in dissipating excess pore pressure in such a condition are also forwarded.
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Mortazavi, Ali. "Modelling of rock blasting in jointed media using discontinuous deformation analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0018/NQ45266.pdf.
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Kou, Shaoquan. "Some basic problems in rock breakage by blasting and by indentation /." Luleå, 1995. http://epubl.luth.se/avslutade/0348-8373/180/index.html.
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Harris, Adrian F. "Relationship between surface texture, surface energy and adhesion using grit blasting." Thesis, Oxford Brookes University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284758.
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Bandaru, Ravi Kishore. "Particle breakage in sand blasting due to impact on ductile materials." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3577.
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Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains vii, 94 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 86-87).
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Sharma, Abhinav. "ESTIMATING THE EFFECTS OF BLASTING VIBRATIONS ON THE HIGH-WALL STABILITY." UKnowledge, 2017. https://uknowledge.uky.edu/mng_etds/38.
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The stability of the high-walls is one of the major concerns for open pit mines. Among the various factors affecting the stability of high-walls, blast vibrations can be an important one. In general, worldwide the established respective government regulations and industry standards are used as guidance to determine the maximum recommended levels of the peak particle velocity and frequency from the blast to avoid any effects on the structures around the mining project. However, most of the regulations are meant for buildings or houses and do not concern high-walls.
This thesis investigates the response of high-walls under the effects of vibrations from mine blasting. In this research, the relationship between the high-wall response, the geometry of the slope, the frequency and the amplitude, of the ground vibration produced by blasting, is explored using numerical models in 3DEC. The numerical models were calibrated initially with data collected using seismographs installed in a surface mine operation and recording vibrations produced by an underground mine drill and blast operation. Once the calibration was accomplished, a parametric study was developed to explore the relationships between various parameters under study and its impact on the stability of high-walls.
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Hosein, Shazad Mustapha. "The application of electronic detonators to control the environmental impact of blasting." Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485745.
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In recent years, the interest in electronic detonators has increased due to its reported ability to define sequences that can significantly improve blasting results and lower environmental impact in relation to the mining and quarrying industry. However, few actual scientific studies have been carried out and published. This thesis investigates the use of electronic detonator with the aim of controlling and minimising the environmental impact of blasting. Its use was examined by comparing their performance to current non-electric detonators by performing a series of full scale like-for-like experiments under strict operational procedures in a variety of rock hosts. In addition, two single hole multi deck blasts were carried out to assess the influence of both distance and individual location response. The results obtained indicate that it is not possible to select one electronic detonator timing interval that will give rise to the absolute lowest Peak Particle Velocity for all observation points. However, it showed that it is possible to choose the 'least worst' option for all or just a number of specific monitoring locations. From this it has been possible to establish a methodology that could be used to reduce the peak particle velocities at multiple locations by using single hole blast vibration signatures in conjunction with specific electronic detonator timing intervals. The study has concluded that this would only be possible if, as the blasting pattern encroaches on specific properties, that periodically single hole signature blasts were carried out to establish the shape ofthe relevant actual vibration envelopes. These wave envelopes could be used as the basis for choosing the specific electronic detonator timing intervals to give the lowest common peak particle velocity for the properties concerned thus controlling the environmental impact of blasting.
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Johnson, Catherine E. "Fragmentation Analysis in the Dynamic Stress Wave Collision Regions in Bench Blasting." UKnowledge, 2014. http://uknowledge.uky.edu/mng_etds/16.
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The first step in many mining operations is blasting, and the purpose of blasting is to fragment the rock mass in the most efficient way for that mine site and the material end use. Over time, new developments to any industry occur, and design and implementation of traditional techniques have to change as a consequence. Possibly the greatest improvement in blasting in recent years is that of electronic detonators. The improvements related to safety and increased fragmentation have been invaluable. There has been ongoing debate within the explosives industry regarding two possible theories for this. Shorter timing delays that allow interaction between adjacent shock waves or detonation waves, or the increase in accuracy associated with electronic detonators. Results exist on the improved accuracy of electronic detonators over that of electric or non-electric, but data on the relationship between the collision of dynamic stress waves and fragmentation is less understood. Publications stating that the area of greatest fragmentation will occur between points of detonation where shock waves collide exist, but experimental data to prove this fact is lacking.
This dissertation looks extensively at the head on collision of shock (in the rock mass) and detonation (in the detonation column) waves with relation to fragmentation through a number of small scale tests in concrete. Timing is a vital tool for this collision to occur and is the variable utilized for the studies. Small scale tests in solid masonry blocks, 15 x 7⅞ x 7⅞ inches in size, investigated shock and detonation wave collisions with instantaneous detonation. Blocks were wrapped in geotextile fabric and a wire mesh to contain the fragments so that in situ tensile crack formations could be analyzed. Detonating cord was used as the explosive with no stemming to maintain the shock pressure but reduce the gas pressure phase of the fragmentation cycle. Model simulations of these blocks in ANSYS Autodyn looked at the stress and pressure wave patterns and corresponding damage contours for a direct comparison with the experimental investigation.
Detonation wave collision in a single blast hole was found to positively influence the fragmentation and throw of the material. Mean fragment size decreased compared to tests with no detonation wave collision. Area of greatest throw occurred at the point of detonation collision where a buildup of gas pressure exited the block from one location. Head on collision of shock waves did not positively influence the muck pile. Largest fragments were located at the point of shock collision. The lack of particle velocity with relation to shock collision in previous literature could be attributed to the increased particle size here. Directional particle velocities could actually increase the strength and density of the rock at this location, decreasing the degree of fragmentation rather than increasing it.
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Steele, Katie. "FORENSIC ANALYSIS OF C-4 AND COMMERCIAL BLASTING AGENTS FOR POSSIBLE DISCRIMINATION." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3132.
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The criminal use of explosives has increased in recent years. Political instability and the wide spread access to the internet, filled with "homemade recipes," are two conjectures for the increase. C-4 is a plastic bonded explosive (PBX) comprised of 91% of the high explosive RDX, 1.6% processing oils, 5.3% plasticizer, and 2.1% polyisobutylene (PIB). C-4 is most commonly used for military purposes, but also has found use in commercial industry as well. Current methods for the forensic analysis of C-4 are limited to identification of the explosive; however, recent publications have suggested the plausibility of discrimination between C-4 samples based upon the processing oils and stable isotope ratios. This research focuses on the discrimination of C-4 samples based on ratios of RDX to HMX, a common impurity resulting from RDX synthesis. The relative amounts of HMX are a function of the RDX synthetic route and conditions. RDX was extracted from different C-4 samples and was analyzed by ESI-MS-SIM as the chloride adduct, EI-GC-MS-SIM, and NICI-GC-MS. Ratios (RDX/HMX) were calculated for each method. An analysis of variance (ANOVA) followed by a Tukey HSD allowed for an overall discriminating power to be assessed for each analytical method. The C-4 processing oils were also extracted, and analyzed by direct exposure probe mass spectrometry (DEP-MS) with electron ionization, a technique that requires less than two minutes for analysis. The overall discriminating power of the processing oils was calculated by conducting a series of t tests. Lastly, a set of heterogeneous commercial blasting agents were analyzed by laser induced breakdown spectroscopy (LIBS). The data was analyzed by principal components analysis (PCA), and the possibility of creating a searchable library was explored.M.S.
Department of Chemistry
Sciences
Forensic Science MS
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Djouama, Mohamed Cherif. "Assessment of rock cutting and rock fragmentation by blasting using image analysis." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278384.
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BENDEZU, MARKO ANTONIO LOPEZ. "NUMERICAL SIMULATION OF BLASTING-INDUCED ROCK FRACTURES CONSIDERING THE COHESIVE ZONE MODEL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=30457@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
O estudo de iniciação e propagação de fraturas em rochas devido à energia gerada por explosões é uma tarefa desafiadora em mecânica computacional dada a natureza multifísica e multi-escala do fenômeno. Uma das técnicas utilizadas para simulação deste processo pelo método dos elementos finitos consiste em acompanhar a evolução de fraturas no tempo, com atualizações frequentes da malha de elementos, o que torna as análises demoradas e complicadas, com perda de precisão numérica no processo de atualização dos valores calculados em pontos da malha antiga para os pontos correspondentes da malha nova. O método estendido dos elementos finitos (XFEM) permite a incorporação de enriquecimentos locais, i.e. de um conjunto de funções de interpolação enriquecidas que fornecem valores das variáveis de interesse (deslocamentos, tensões) com maior precisão e eficiência computacional. Além disso, é importante ressaltar, que a presença da fratura, e sua propagação no tempo através da rocha, não é geometricamente modelada e a malha de elementos não precisa ser constantemente atualizada. Quatro diferentes abordagens são examinadas para simular o processo de fraturamento na rocha, com a comparação entre os respectivos resultados: o método XFEM, os elementos de interface coesivas, os elementos finitos com singularidade e a técnica de eliminação de elementos que remove elementos da malha, simulando o fraturamento, quando os mesmos atingem a ruptura de acordo com algum critério. Nesta pesquisa, o método XFEM é aplicado para investigar o desmonte de rocha com base no método dos nós fantasma onde as descontinuidades nos campos de deslocamentos são introduzidas através de novos graus de liberdade em elementos sobrepostos. O maciço rochoso considerado é um granito admitido isotrópico no meio homogêneo ou heterogêneo que tem comportamento elástico linear até o início da quebra, onde a propagação de fraturas utiliza o modelo de zona coesiva. Alguns exemplos numéricos são apresentados aspectos relacionados com o fraturamento de um maciço rochoso sujeito a explosão, a fim de discutir as vantagens e limitações. Além disso, os resultados numéricos são comparados com os obtidos por outros autores utilizando diferentes abordagens numéricas.
The study of propagation of fractures in rocks due to the energy generated by explosions is a challenging task in computational mechanics given the multiphysics and multiscale nature of the phenomenon. One of the most widely used methods for simulation of this process is the finite element method, which follows the time evolution of fractures, with frequent updates of mesh elements to represent the new geometry of the newly fractured material. This approach, besides being computationally time consuming and difficult for the necessity of constant rebuilding meshes, also results in the loss of numerical accuracy when the variables of interest are mapped and interpolated from the old mesh to the Gauss points and nodal points the new mesh. The Extended Finite Element Method (XFEM) local enrichment functions to be easily incorporated into a finite element approximation. The presence of fracture is ensured by the special enriched functions in conjunction with additional degrees of freedom with greater accuracy and computational efficiency. Furthermore, it is important to note that does not require the mesh to match the geometry of the fracture. It is a very attractive and effective way to simulate initiation and propagation of a crack along an arbitrary, solution-dependent path without the requirement of remeshing. Four different approaches are examined to simulate the rock fracturing process, with comparison between respective results: the XFEM, the interelement crack method, the conventional finite element method (FEM) using a remeshing technique and based on the linear fracture mechanics and the element deletion method with Rankine failure-type material model to simulate discrete rock fracture. In this research, XFEM is applied to investigate rock blasting based on the phantom node method where discontinuities in the displacement fields are introduced through new degrees of freedom in overlapping elements. The rock mass considered is a sound granite admitted as an isotropic, homogeneous or heterogeneous medium that remains linear elastic right up the moment of breakage, and then the propagation of cracks using the cohesive zone model. Several numerical examples are presented aspects related to the fracturing of a rock mass under the effect of blast-induced dynamic pressure pulse, in order to discuss the advantages and limitations of each of the aforementioned approaches. Furthermore, the numerical results are compared with those obtained by other authors using different numerical approaches.
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Al-Khayyat, Farah Nabeel Mohammed Tahir. "Surface modification of titanium implants by grit-blasting with novel bioactive glasses." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/33943.
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Introduction: The survival of dental implants depends on osseointegration. Modifications to the implant surface are attractive for promoting the success of the implant. Abrading the surface of the implant with bioactive glass is an attractive option for improving the speed of osseointegration. Aims: To develop a bioactive glass that has the ability to enhance the surface roughness of the implant by embedding particles into the surface and to investigate the effect of grit blast parameters on the removal of the titanium from the surface. Methods: Three glasses based on SiO2-CaO-Na2O-P2O5-CaF2 were synthesized by a melt quench technique. The glasses were characterised and investigated for their bioactivity. Titanium discs were abraded with coarse glass particles by using a grit blast technique with different parameters, such as, distance, air pressure and speed. The depth, width of the abraded line and surface roughness (Ra) were measured by light profilometer. The distribution of the glasses on the titanium surface was measured by SEM-EDX. The biocompatibility of the abraded discs was tested in vitro using MC3T3-E1 cell line. Results: All glasses exhibited an amorphous structure with varied bioactivity. Changing the abrasion parameters influenced the amount of titanium removed and the surface coverage. The harder the glass the lower the amount of titanium removed and the wider the width of the abraded area. The Ra was significantly increased from 0.1μm to 1.6μm. The SEM-EDX analysis confirmed that the glasses were widely distributed and a higher coverage was seen with the harder glass. The abraded discs showed good biocompatibility in vitro. Conclusions: The designed compositions were successfully modifying the surface of the titanium. They are abrasive enough to significantly embed into the titanium surface by using the grit blast technique and increase their surface roughness. TheIntroduction: The survival of dental implants depends on osseointegration. Modifications to the implant surface are attractive for promoting the success of the implant. Abrading the surface of the implant with bioactive glass is an attractive option for improving the speed of osseointegration. Aims: To develop a bioactive glass that has the ability to enhance the surface roughness of the implant by embedding particles into the surface and to investigate the effect of grit blast parameters on the removal of the titanium from the surface. Methods: Three glasses based on SiO2-CaO-Na2O-P2O5-CaF2 were synthesized by a melt quench technique. The glasses were characterised and investigated for their bioactivity. Titanium discs were abraded with coarse glass particles by using a grit blast technique with different parameters, such as, distance, air pressure and speed. The depth, width of the abraded line and surface roughness (Ra) were measured by light profilometer. The distribution of the glasses on the titanium surface was measured by SEM-EDX. The biocompatibility of the abraded discs was tested in vitro using MC3T3-E1 cell line. Results: All glasses exhibited an amorphous structure with varied bioactivity. Changing the abrasion parameters influenced the amount of titanium removed and the surface coverage. The harder the glass the lower the amount of titanium removed and the wider the width of the abraded area. The Ra was significantly increased from 0.1μm to 1.6μm. The SEM-EDX analysis confirmed that the glasses were widely distributed and a higher coverage was seen with the harder glass. The abraded discs showed good biocompatibility in vitro. Conclusions: The designed compositions were successfully modifying the surface of the titanium. They are abrasive enough to significantly embed into the titanium surface by using the grit blast technique and increase their surface roughness. The glass abraded discs show both good bioactivity and biocompatibility in vitro.
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Caballero, Erick, Rosa Calixto, Luis Arauzo, and Carlos Raymundo. "Model for Optimization of Drilling, Blasting and Fragmentation Processes in medium mining." International Institute of Informatics and Systemics, IIIS, 2019. http://hdl.handle.net/10757/656286.
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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.This study aims to propose a new alternative to optimize drilling and blasting processes from the mathematical and geological viewpoint using simulation software. The main objective is to design a systematic model of steps that can generate a simulation through JkSimBlast. This simulation must represent the best alternative for the design of drilling mesh and explosive selection to be implemented in the field. To achieve this goal, a seven-step process diagram was proposed, including geology, design aspects (burden and spacing across the areas of influence algorithm), analysis of physical parameters such as detonation rate, drill-mesh design, explosives selection and fragmentation analysis, simulation tests that could represent the field designs, and selection of the most optimal simulation. For the collection of parameters in the field, we have used MicroTrap Software and WipFrag, which have allowed the design of a mesh according to the needs of the rocky massif. The most optimal simulation was implemented at Caravelí Mining Company-Estrella Unit and had a positive impact on the optimization of drilling and blasting, as the costs of these processes were reduced by 14.6%. Specifically, the costs of explosives were reduced by 2.6% and the costs of drilling steels by 10.4%. The performance of the loading machine advance/shot increased by 13.2% and 15.6%, respectively. Copyright 2019.
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Esen, Sedat. "A non-ideal detonation model for commercial explosives /." [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18338.pdf.
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Kim, Kwangmin. "Blasting Design Using Fracture Toughness and Image Analysis of the Bench Face and Muckpile." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34582.
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Few studies of blasting exist because of difficulties in obtaining reliable fragmentation data or even obtaining consistent blasting results. Many researchers have attempted to predict blast fragmentation using the Kuz-Ram model, an empirical fragmentation model suggested by Cunningham.
The purpose of this study is to develop an empirical model to relate specific explosives energy (ESE) to blasting fragmentation reduction ratio (RR) and rock fracture toughness (KIC).
The reduction ratio was obtained by analyzing the bench face block size distribution and the muck fragment size distribution using image analysis. The fracture toughness was determined using the Edge Notched Disk Wedge Splitting test.
Blasting data from twelve (12) blasts at four (4) different quarries were analyzed. Based on this data set, an empirical relationship, ESE=11.7 RR801.202 KIC4.14 has been developed. Using this relationship, based on the predicted blasting energy input for a desired eighty-percent passing (P80) muckpile fragment size the burden and spacing may be determined.Master of Science
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Cakmak, Baris Bezmi. "Investigation Of Ground Vibrations Induced By Production Blasting At Usak Kisladag Gold Mine." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608744/index.pdf.
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Ground vibrations from blasting are acoustic waves that propagate through the earth. They are also termed seismic waves because their propagation characteristics are similar to the ground motions produced by earthquakes. Amplitude of ground vibration induced by blasting may vary significantly at or around an open pit mine depending on parameters such as the maximum amount of explosive detonating at a time interval and the physical distance between the shot and the location of concern, whereas the frequency of vibration mainly vary depending on the geology and blast delay intervals. Therefore evaluation and assessment of ground vibration condition at or around an open pit mine is necessary.
The objective of the proposed research study is to monitor and record the ground vibration and to investigate and assess the vibration conditions at neighbouring districts that are induced by production blasting operations at Usak KiSladag Gold Mine. In this research study, several parameters such as the ground vibration velocity, the amount of charge per delay, the physical distance to the location of monitoring device or residential structures are recorded, analyzed and evaluated together with the frequencies of the seismic waves. The determined ground vibration velocities are compared with the allowable limits given in Turkish Regulation and US Federal Regulation. Thus, the compliance of the ground vibrations with the above mentioned regulations are discussed and assessed. Furthermore, the parameters which affect the ground vibration are discussed and determined.
In this study, the monitored and the recorded ground vibrations are evaluated from structural damage potential and human disturbance points of views. It is determined that the ground vibration levels recorded during this study and analyzed from the past records comply with Turkish and US Federal regulations. It is concluded that no damage has been occurred in structures at surrounding settlements and the occupants were not disturbed by the direct effect of vibrations in the past and at present. The analysis proved that the blasting operations to be conducted in the future will not create any damage and disturbance provided that the charge detonated per delay is kept less than 155 kg’
s.
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Dare-Bryan, Peter C. "Computer modelling of bench blasting in open pit mines to improve grade control." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423525.
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Calnan, Joshua. "DETERMINATION OF EXPLOSIVE ENERGY PARTITION VALUES IN ROCK BLASTING THROUGH SMALL-SCALE TESTING." UKnowledge, 2015. http://uknowledge.uky.edu/mng_etds/24.
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Blasting is a critical part of most mining operations. The primary function of blasting is to fragment and move rock. For decades, attempts have been made at increasing the efficiency of blasting to reduce costs and increase production. Most of these attempts involve trial and error techniques that focus on changing a single output. These techniques are costly and time consuming and it has been shown that as one output is optimized other outputs move away from their optimum level. To truly optimize a blasting program, the transfer of explosive energy into individual components must be quantified. Explosive energy is broken down into five primary components: rock fragmentation, heave, ground vibration, air blast, and heat. Fragmentation and heave are considered beneficial components while the remaining are considered waste. Past energy partitioning research has been able to account for less than 30% of a blast’s total explosive energy.
The purpose of this dissertation was to account for a greater percentage of the explosive energy available during a blast. These values were determined using measurement techniques not previously applied to energy partitioning research. Four small-scale test series were completed, each designed to isolate individual energy components. Specific energy components measured include borehole chambering, elastic deformation (ground vibration), translational and rotational kinetic energy (heave), and air overpressure (air blast).
This research was able to account for 73% of the total explosive energy. Borehole chambering (13%), rotational kinetic energy (25%), translational kinetic energy (5%), and air overpressure (28%) were determined to be the largest components. Prior research efforts have largely ignored rotational kinetic energy and have only been able to offer predictions for the values of borehole chambering and air overpressure energies.
This dissertation accounted for a significantly higher percentage of total available explosive energy than previous research efforts using novel measurement techniques. It was shown that borehole chambering, heave, and air blast are the largest energy components in a blast. In addition to quantifying specific energy partitions, a basic goal programming objective function was proposed, incorporating explosive energy partitioning and blasting parameters into a framework that can be used for future energy optimization.
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Mothersille, Devon Kenningtham Vernon. "The influence of close proximity blasting on the performance of resin bonded bolts." Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329297.
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Full scale field trials, carried out during the construction of the Penmaenbach Tunnel in North Wales, have shown that two-speed resin bonded rock bolts are resilient to close proximity blasting. Fully grouted 6m long rock bolts, installed within 0.7m of the tunnel face, have shown no significant signs of distress or failure. Instantaneous loads of up to 40% of the characteristic strength of the bolt were observed together with average residual load losses of 5% of the working load, which compares favourably with the acceptable tolerance of 10% working load stipulated by current practice. Analysis has also shown that rock bolts with low prestress sustain greater vibrations and proportionately higher dynamic load changes during blasting. However, bolts with relatively high prestress loads sustain greater induced loads. Empirical relations have been established to describe rock bolt behaviour in terms of induced vibration and scaled distance. In particular, a predictive equation relating dynamic load changes in the experimental rock bolts to scaled distance, is presented. Calculations based on approximate bolting costs have indicated that cost savings of up to 38% of the total bolting cost could have been effected if the results of this work had been implemented at the design stage. Physical modelling work has confirmed that the distribution of loads in the fixed anchor of a resin bonded bolt are non-linear when both static and impulsive loads are applied to the bolt head. Corroboration of the field results has also been established with respect to the significant influence of initial prestress load on dynamic load change. Complementary finite element modelling work has successfully predicted fixed anchor load distributions under static and dynamic loading conditions. Attempts to establish a detailed relation between distance from blast, magnitude of charge and change in residual load, for low to medium capacity rock anchorages on the West Portal of the tunnel, were thwarted by the poor performance of instrumentation with respect to temperature sensitivity. However, a simplistic approach to analysis has enabled the establishment of a tentative predictive relationship.
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Myrsell, Johan. "Effect of shot blasting on processoxidised stainless steel – morphology,chemistry and pickling performance." Thesis, KTH, Materialvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-161877.
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The oxide scale created during manufacturing of stainless steel is often removed by a chemical pickling with mixed acid. Various pre-treatments to pickling are also applied to increase the efficiency of the oxide scale removal. Shot blasting is one such pre-treatment, which operates to remove a certain amount of oxide and also to generate cracks and openings for the subsequent pickling. In this work, three materials, AISI 2205, 430 and 304 have been blasted and later exposed to mixed acid. This was conducted to quantify the effect shot blasting has on the subsequent pickling of stainless steel. Three shot products and two blasting parameters were investigated and varied. Shot blasting significantly reduced the oxide scale but was unable to remove the chromium oxide layer closest to the steel surface. No significant difference was observed when comparing the result from the three shot products after blasting. Increasing the particle velocity or the coverage rate further enhanced the pickling but reduced the amount of oxide removed during blasting. These effects are however relative small, so in practise relatively mild conditions seems preferable for economic reasons. Oxide scale containing hematite was difficult to remove by both shot blasting and pickling.
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Simpson, Brenton. "Modelling of the crystallisation process of highly concentrated ammonium nitrate emulsions." Thesis, Nelson Mandela Metropolitan University, 2011. http://hdl.handle.net/10948/d1012622.
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Highly concentrated ammonium nitrate emulsions are extensively used as an explosive in the mining industry. The emulsion is made from a supercooled aqueous salt solution with various stabilisers and an organic hydrocarbon phase under vigorous stirring to room temperature. The resulting emulsion is thermodynamically unstable and tends to crystallise over time. This is not suitable for the transportation or pumping of the emulsion in its application. This study showed that the crystallisation process of highly concentrated ammonium nitrate emulsions can be influenced by varying the emulsion droplet size as well as the types and ratios of surfactants used during the preparation stage. The results showed that there were significant differences in the rheological properties of the freshly-prepared emulsion, based on both the emulsion droplet size, and the type of surfactant and ratio of surfactants used. A decrease of the emulsion droplet size resulted in the increase of the elastic character, which can be explained by more compact network organisation of droplets. In terms of the different surfactants, it was shown that the Pibsa-Imide stabilised emulsions resulted in an emulsion with the highest storage modulus over the entire strain amplitude regions as well as the highest shear stresses over the whole shear rate region. The study showed that the relatively slow emulsion crystallisation process can be studied by using powder X-ray diffraction (PXRD). The amount of amorphous and crystalline phases present in the sample can be effectively quantified by using the Partial Or No Known Crystal Structural (PONKCS) method which can model accurately the contributions of the amorphous halo. An external standard calibration method, which used a different amorphous material with the crystalline material to obtain a suitable calibration constant, was employed. The results showed that the method would quantify the amount of the fully crystallised emulsion to be between 80 and 90 percent, which was in agreement with the solid content added during sample preparation and confirmed by Thermal Gravimetric Analysis (TGA). The simultaneous TGA / DSC results were able to show the number of solid/solid peak transitions as well as the total moisture content to be around 20 percent by mass in various emulsion samples studied. The study was able to model the crystallisation by using the Avrami and Tobin kinetic relationships which are commonly used for the crystallisation processes of polymers. The Avrami relationship proved to be useful in describing the type of crystallisation that occurred. This was based on literature where the exponent parameter (n) which was between 1 and 4 would relate to different types of crystallisation models. The results of this study showed that the crystallisation process would change for the samples that had shown a longer crystallisation process. The results indicated that the samples prepared with the lower Pibsa-Urea ratio showed a more sporadic crystallisation process, whereas the samples with the higher ratio of Pibsa-Urea showed a more controlled crystallisation process. The study also considered the rheological properties of the fresh emulsion, which showed that droplet size also had an influence on the stress strain relationship of the emulsion droplets.
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Singh, Ajit 1951. "Photographic evaluation of blast fragmentation." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63380.
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