Academic literature on the topic 'Platinum – Metallurgy'

AbstractThe archaeological setting of the La Tolita—Tumaco culture is briefly discussed as a framework for the examination of the metallurgy of the area, in particular the gold—platinum alloys used to make platinum-coated gold objects, platinum—gold sintered alloys, and platinum—gold foil—plated objects. The sophisticated approach to the manipulation of metallic materials resulted in several notable advances being made by the La Tolita—Tumaco culture: the production of extremely fine rectangular wire, bimetallic tumbaga alloys, small lead spheres inlaid with platinum, soldering, granulation, and a degree of sophistication to metalworking that is very impressive and, in some cases, unique in the world. Some selected examples are discussed, and the microstructure of a representative selection of the La Tolita material, bimetallic tumbaga construction, the initial sintered gold—platinum product, platinum-plated gold, and heavily worked gold—platinum composite artifacts are presented.

Based on process mineralogical study of a low-grade Cu-Ni-platinum group metal(PGM) sulfide ore in SW China, the occurrence of Cu and Ni, the distribution of platinum group minerals (PGMs) and their relationships with other minerals are determined in detail, which provides scientific reference for forthcoming mineral processing and extractive metallurgy. The mineralogical results show that 18 individual PGMs containing all the 6 platinum group elements (PGEs) are investigated, and it can be concluded that the PGMs in the ores mainly occur as individual minerals. SEM images show that the PGMs are mainly disseminated in sulphides, most occur as inclusions or semi-inclusions, and part are inlayed along the other minerals to form coarse compound grains. Due to the the complex mineral composition and texture, processing the Cu-Ni-PGM ores by traditional flotation may be difficult to get a good processing performance.

Metallurgy of KGHM Polska Miedź S.A. is one of the world leaders in the production of copper. It is the result of high volume and quality production of copper and silver, as well as the use of modern technology direct to copper process in flash smelting furnace in HMG II. Soon this will be also the case for HMG I. The intention is to modernise, and upgrade technological processes within all the smelters to increase effectiveness, also to decrease production costs, and improve contamination of environment. In the year 2014 production of electrolytic copper increased about 2% in respect to 2013, and reached the record value 577 thousands ton. Production of silver increased 8% attaining value of 1256 ton. These perfect results were obtained through optimisation of smelting processes from one side, and rising the content of own concentrates, and foreign batches with higher content of precious metals. Production of metallic gold in 2014 was equal to 2,5t. Moreover KGHM is the third world producer of rhenium. They produce also lead technical and refined, as well as selenium, nickel sulphate, and platinum-palladium concentrate. The KGHM is also substantial producer of sulphuric acid, what is the direct effect of very efficient technology of desulphurisation of exhausts in the used metallurgical processes. The challenge for future is to increase retrieving of elements associated with copper production on every phase of the production. Due to the use of new technologies one expects also to achieve improved retrieving of other metals. Since 20% of KGHM revenue comes from silver, this is an important position in the overall balance of corporation focused mainly on copper exploitation. This is also why KGHM develops co-operations with scientific centres on the level bigger than laboratory (i.e. demo and/or pilot scales). The corporation is directly involved in research and development (subsidised national and international projects), while the value of these projects exceeds 200 mln PLN. There were created several collaborations with academic institutions targeting improvement of retrieval of energy from exploration processes, increase automation, remote control mining, and others. All of them are state of the art, and very modern technologies. KGHM must stay innovative, to preserve its market advantage. Metallurgy itself using own implemented technologies, resumes extended efforts to explore fully the richness of elements associated with the main metals.

Titanium-platinum (Ti50Pt50) alloy has been identified as a potential candidate for high temperature shape memory alloy (HTSMA) applications such as actuators in jet engines. This work evaluates powder metallurgy as an alternative processing route with the added benefit that near net shaped components can be formed. Spark plasma sintering (SPS) of blended elemental titanium and platinum powders was carried out. The sintering conditions used were: temperatures ranging from 1200 to 1400 °C and sintering times ranging from 10 to 30 minutes. SEM with EDS, XRD and DSC were carried out to study the results. Results showed that SPS only achieved high density, but not homogenisation of the alloys. All sintering conditions resulted in formation of the martensitic TiPt phase of interest, together with some or all of the following phases: Ti, Ti3Pt, Ti4Pt3, Ti3Pt5 and Pt. Post sintering annealing treatments were carried out to homoginise the alloys at 1300 °C for times ranging from 5 to 15 hours. With sufficient annealing times a two phase microstructure was produced with TiPt as the majority matrix phase and Ti3Pt5 as the precipitate phase.

With the implementation of RoHS (the Restriction of Hazardous Substance) Directive banning the use of Lead, Cadmium, Mercury and Hexavalent Chromium, hybrid microelectronic manufacturers are globally embracing the lead free movement. These manufacturers must not only understand the implications of their material choice but must be aware of the interaction between lead free solder alloys and their RoHS compliant thick film materials. It is commonly known that lead free solder alloys process at much higher reflow temperatures than lead containing solder which can directly impact the fired film leach resistance and the loss of adhesion. There are also other concerns; lead free solders alloys generally require a different organic flux system to promote wetting and reflow, but this change may cause a fired film conductor to leach more easily than the flux used in the lead containing solders. The use of lead free solders such as SAC305, SAC405 or 95/5 on a low firing (550–570 °C) pure silver conductor has the tendency of leaching the fired film more readily than conductors containing small amounts of palladium or platinum. Many of these situations provide new challenges for the hybrid circuit manufacturer. There is little information available regarding the effects of the lead free solders on low firing silver thick film conductors. This paper discusses the results of a newly developed Pb and Cd free silver thick film conductor paste with a modified silver powder metallurgy to improve the leach resistance, solder acceptance and adhesion using lead free solder. In addition, the pure silver conductor was fired on top of a low temperature dielectric paste. This conductor was evaluated by comparing lead free solder alloys to traditional tin-lead-silver solder alloys. This study included evaluations based on SEM photos, solderability, leach resistance, and initial and long term adhesions. Results are published describing the difference in behavior between the different solder alloys in conjunction with the different silver powder metallurgy.

The investigation was performed on pure sintered (PM) copper and dilute PM copper-based alloys with 3 and 5.9 wt.% of platinum. Investigated PM samples were obtained using the standard powder metallurgy technique by mixing the elemental powders in proper ratio followed by pressing in hydraulic press and sintering in a hydrogen atmosphere. The PM samples were further cold deformed by rolling at ambient temperature to a total rolling reduction of 60 %. On pre-deformed samples, the low-temperature isothermal annealing up to the 100 hours was accomplished. During all stages of isothermal annealing, the values of Vickers hardness, micro-hardness, and electrical conductivity were measured. Also, the microstructure was analyzed using the scanning electron microscopy (SEM). This investigation has shown a slight increase in all measured properties for both dilute Cu-Pt alloys. An increase in mechanical properties was some more pronounced for more alloyed Cu-5.9wt%Pt alloy. During the low-temperature isothermal annealing, there were no significant changes in properties for pure pre-deformed copper.

There is a great interest in the treatment of spent autocatalyst because, due to large amounts of PGM used by catalytic converters, the autocatalyst scrap is the largest and constantly growing source of PGM available for recycling. A hydrometallurgical method of PGM extraction from honeycomb type catalyst containing platinum (800-1200 ppm) and rhodium (50-60 ppm) using HCl-AlCl$ sb3$-HNO$ sb3$ or HCl-HNO$ sb3$ mixtures was studied. Experimental results of the leaches performed in a bench scale tubular reaction with recycled continuous flow of the leaching solution as well as 1000 cc stirred reactor are presented. The results suggest that Cl$ sp-$ single ion activity plays a decisive role in controlling the PGM dissolution. The extent of PGM recovery increased not by increasing HCl concentration to very high levels, but by keeping a relatively low total Cl$ sp-$ level (2.5 M) with a significant proportion present as AlCl$ sb3$. Rhodium extraction was always 5-10% lower than platinum, and it appears that increasing the AlCl$ sb3$/HCl ratio tends to increase rhodium recovery. High temperature (85-95$ sp circ$C) and an HNO$ sb3$ concentration around 3-3.5 M play very important roles in effectiveness of PGM extraction. The presented method of HCl-AlCl$ sb3$-HNO$ sb3$ tubular reactor leaching supplemented by solvent extraction (Kelex 100) of PGM from pregnant solution appears to be very attractive for small size (5-20 tonnes of catalyst/day) installations.

Using supramolecular principles, we have been designing luminescent lanthanide complexes with a defined hairpin bis-interlacator in order to obtain luminescent probes able to recognise DNA. The complexes are comprised of Platinum(II) terpyridine, which acts as a DNA recognition site and is brought together with a "remote" luminescent lanthanide unit. All the synthetic approaches were based on the accessibility of the lanthanide-platinum complexes by the self-assembly of different components in a one pot reaction. Thus, we have been able to isolate a water soluble heterometallic complex based on thiophenal linkage named [LnPt\(_2\)]Cl\(_2\). The complex has a relatively weak lanthanide luminescence, which increases upon addition of DNA. Photophysical and DNA binding properties of the lanthanide-platinum complex were investigated by UV-vis absorption, luminescent studies and circular and linear dichroism. Oligonucleotides of twelve bases were also used to investigate the intercalation [LnPt\(_2\)]Cl\(_2\) and the mono-intercalator AATP used as control compound. Using bidimensional NMR techniques, we investigated the binding site for [LnPt\(_2\)]Cl\(_2\) and AATP upon interaction with Dickerson-Drew sequence. The sulphur lanthanide-platinum linkage in [LnPt\(_2\)]Cl\(_2\) was replaced with an acetylide one in order to introduce new photophysical features. Thus the self-assembly procedures based on DTPA-bis(amido-acetylide) and a platinum(II) terpyridine led us to isolate a new lanthanide-platinum complex named [LnC\(\equiv\)CPt\(_2\)] (CH\(_3\)SO\(_3\))\(_2\). The photophysical properties and the DNA binding properties toward interaction with CT-DNA were investigated. The complex named LnC\(\equiv\)CPt\(_2\)](CH\(_3\)S)\(_3\))\(_2\) exhibited a relatively strong lanthanide luminescence that increased upon addition of DNA. The bi-functional metal complex [EuLPt](PF\(_6\)) (where Pt=platinum-2,2':6'2"-terpyridine and L=assymmetric DTPA bisamide ligand with a thiopheno pendant arm and a quinoline moiety) was synthesised and the interaction of [EuLPt](PF\(_6\)) with CT-DNA was examined by luminescence spectroscopy, linear and circular dichroism studies and thermal denaturation studies. The [EuLPt](PF\(_6\)) retained the ability to increase its luminescence upon the addition of CT-DNA. The binding properties of the complexes were tested toward interaction with plasmid DNA by gel electrophoresis and properties such as the unwinding angle were measured. The bis-intercalators [LnPt\(_2\)]Cl\(_2\) and [LnC\(\equiv\)CPt\(_2\)](CH\(_3\)SO\(_3\))\(_2\) showed the ability to uncoil DNA almost as well as cisplatin and at low concentrations, while almost double the amount of mono-intercalators, such as [EuLPt](PF\(_6\)) is required to observe the same uncoiling effect.

In order to understand and control the deportment of common impurity elements in the Pt(IV)-Pd(II)-HCl-8-hydroxyquinoline (TN 1911)$ sp{ rm a}$ system, their solvent extraction chemistry in chloride solution has been studied. The investigated elements were Fe(III), Cu(II), Ni(II), Zn(II), Pb(II), Sn(IV), Ag(I), As(V), Sb(V), Bi(III), Se(IV) and Te(IV). Extraction experiments carried out using multi-element and single element feed solutions helped to elucidate the extraction behaviour of the elements with the extractant TN 1911. From the collected data it was deduced that the majority formed anionic chlorocomplexes and extracted via the ion-pair mechanism involving the protonated extractant. Consequently, scrubbing procedures were developed to control the deportment of these elements. These scrubbing steps were then incorporated into a tentative flowsheet which was simulated in a batch-wise fashion in the laboratory. The most contaminating elements were found to be Zn(II), Pb(II), Ag(I), Te(IV), Se(IV) and Bi(III). The first five were effectively scrubbed with 2.0M HCl whereas Bi(III) could only be scrubbed with 2.0M H$ sb2$SO$ sb4$ at A/O ratios of $>$3:1. The element Sn(IV) which was found to build-up in the organic, could only be scrubbed with a 1.0M NaOH solution for long contract times (60 minutes). ftn$ sp{ rm a}$A proprietary alkylated derivative of 8-hydroxyquinoline (Schering Berlin AG).

Thesis (PhD) -- Stellenbosch University, 2014.
ENGLISH ABSTRACT: The process route for the production of base and platinum-group metals from natural sulfide ores commonly requires the conversion of high-iron furnace matte into an iron-lean converter matte. This is followed by pre-treatment through cooling of the iron-lean molten matte, physical processing of the solidified matte and hydrometallurgical metal extraction. Lonmin is the third largest producer of platinum-group metals in the world and utilizes Peirce-Smith converters for blowing high-iron furnace matte with air to a final iron concentration or endpoint. The molten matte is water granulated and solidification occurs via fast-cooling. The solidified matte is ground in a closed circuit ball mill with hydrocyclone classification and subjected to first stage atmospheric leaching. The specification of an ideal or desirable converter iron endpoint requires careful consideration. Most importantly, it must ensure the crystallization of converter matte with mineralogical qualities that are within the setpoints of the downstream unit processes and techniques. An additional consideration is for the final blown converter matte to achieve an optimum bulk concentration of the base metals Ni and Cu and platinum-group metals Pt, Pd, Rh, Ru and Ir. Mattes characteristic of variable iron endpoints were regularly produced at the Lonmin converter plant section. Uncertainty by plant metallurgists in knowing the desirable iron endpoint, particularly within the context of the Lonmin base metal refinery, and poor control has had detrimental effects on the mineralogical quality of the final matte and hence on the processing characteristics of the solidified matte particles downstream. A desirable iron endpoint required investigation, selection and implementation at Lonmin. The primary focus of this study was therefore to quantify the effect of a specific iron endpoint on the mineralogy and mineral chemistry of solidified converter matte. A fundamental examination of the solidification process upon cooling was regarded as critical to an in-depth understanding of the attained mineralogy and mineral chemistry as a function of a specific iron endpoint. It became equally important to quantify the effect of the resultant mineralogy, and hence iron endpoint, on the physical property of mineral structures in relation to downstream grinding, liberation and leaching characteristics. Despite considerable industry context, limited in-depth and coherent studies on the effect of a specific iron endpoint on fast-cooled converter matte systems were found in both industrial and scholarly literature. Previous findings in literature offered a limited quantitative understanding of the effect on mineralogy and mineral chemistry. Phase and cooling equilibria of multi-component, iron endpoint specific Ni-Cu-S matte systems were also not fully available. These would have been particularly useful in understanding the complexities of converter matte solidification as a function of iron endpoint. Physical property knowledge of converter matte mineral structures was hardly available and even less so in relation to grinding, liberation and leaching processes. A comprehensive investigation was therefore required to address these extensive knowledge gaps with respect to fastcooled converter matte systems in an industrial framework. Three Peirce-Smith converter production samples, representative of the extent in variability of iron endpoints attained at the converter plant, were used in a systematic investigation coupled to a novel combination of modern analytical techniques, computational thermochemistry and metallurgical testwork. The modern analytical techniques included the application of high resolution transmission electron microscopy and focused ion beam scanning electron microscopy tomography. Computational thermochemistry was applied through the use of MTDATA phase diagram software. Metallurgical testwork involved laboratory batch grinding at various specific energies. Closely associated leach experiments were also considered relevant to this wide-ranging investigation. The Peirce-Smith converter samples investigated were indicative of mattes that attained specific endpoints of 5.17%, 0.99% and 0.15 weight% Fe. The highest combined bulk concentration of the important base and platinum-group metals was achieved in the matte which attained a specific iron endpoint of 0.99%. The mineralogy of all three converter mattes was dominated by nickel sulfide mineral structures matched to the natural mineral of heazlewoodite. Mineral structures of copper sulfide, NiCu-alloy, spinel and OsRu-alloy were also constituents of the different converter mattes. The attainment of a specific iron endpoint was found to result in measurable mineralogical differences with respect to relative mineral abundances, external morphological characteristics and mineral chemistry. The mineralogical differences were particularly distinct between mineral structures of the high (5.17%) and low (0.99% and 0.15%) iron mattes. Subtle mineralogical differences were evident between mineral structures of the low iron mattes. The 0.99% Fe matte was characteristic of a significantly higher NiCu-alloy relative abundance, compared to the 5.17% Fe matte. The NiCu-alloy structures were found to act as the primary collectors of the economically significant platinum-group metals. Mineralogical observations were used to develop an understanding of the underlying mineralization mechanism of NiCu-alloy structures. High-fidelity color and grayscale 3D reconstructions were produced of the resultant mineralized structures. It was shown theoretically that variations in iron endpoint specific starting compositions of oxygen-free liquid matte systems alter the solidification pathway towards the eutectic. Moreover, a quantitative understanding of liquid phase solidification of the high and low iron matte systems, including oxygen, was developed to within ±2.5 oC. Most of the specific energy available for grinding was expended breaking the nickel sulfide matrix, particularly of the high iron matte. The breakage rates of copper sulfide mineral structures in the 5.17% Fe matte were calculated to be higher than in the 0.15% Fe matte at 25kWh/t specific energy. The degree of copper sulfide liberation was shown to be higher for the 5.17% Fe matte than for the 0.15% Fe matte at the same specific energy of grinding. A higher degree of Ni extraction and Cu cementation could be achieved when leaching low iron matte particles. The production of converter matte attaining a specific iron endpoint of 0.99% was found to be the most suitable with respect to endpoint selection criteria. A practical iron endpoint range of 1.6% to 1.0% was recommended for the production of converter matte with a resultant mineralogical quality within the constraints of the Lonmin base metal refinery. This study offers an integrated understanding of base and platinum-group metals production as a function of a desirable iron endpoint at Lonmin. This was not previously available in metal production literature. New technology for the monitoring and consistent control of such a practical iron endpoint range can subsequently be implemented.
AFRIKAANSE OPSOMMING: Die prosesroete vir die produksie van onedel en platinumgroepmetale uit natuurlike swawelertse vereis gewoonlik die omsetting van ’n ysterryke hoogoondmat in ’n ysterarm omsettermat. Hierna volg voorbehandeling deur die afkoeling van die ysterarm gesmelte mat, fisiese verwerking van die soliede mat, en hidrometallurgiese metaalekstraksie. Lonmin is die derde grootste produsent van platinumgroepmetale ter wêreld en gebruik Peirce-Smith-omsetters om ysterryke hoogoondmat met lug te blaas totdat dit ’n finale ysterkonsentrasie- of ystereindpunt bereik. Die gesmelte mat word met water granuleer, en solidifikasie vind deur middel van snelafkoeling plaas. Die soliede mat word in ’n geslotekringbalmeul met hidrosikloonklassifikasie gemaal en aan eerstestadium- atmosferiese loging onderwerp. Die spesifikasie van ’n ideale of gewenste ystereindpunt verg deeglike oorweging. Bowenal moet dit verseker dat die omsettermat kristalliseer met mineralogiese eienskappe wat binne die setpunte van die eenheidsprosesse en - tegnieke verder af in die prosesstroom val. ’n Bykomende oorweging is dat die uiteindelike geblaasde omsettermat ’n optimale massakonsentrasie van die onedel metale Ni en Cu en die platinumgroepmetale Pt, Pd, Rh, Ru en Ir moet bevat. Matte met die kenmerke van wisselende ystereindpunte is gereeld by die Lonminomsetteraanleg geproduseer. Die onsekerheid van metallurge by die aanleg oor die gewenste ystereindpunt – veral binne die konteks van die Lonmin-raffinadery vir onedel metale – sowel as swak beheer het ’n nadelige uitwerking gehad op die mineralogiese gehalte van die uiteindelike mat, en dus ook op die verwerkingskenmerke van die soliede matdeeltjies verder af in die prosesstroom. Die bepaling van die gewenste ystereindpunt het sorgvuldige ondersoek, seleksie en toepassing deur Lonmin vereis. Hierdie studie is dus hoofsaaklik uitgevoer om die uitwerking van ’n spesifieke ystereindpunt op die mineralogie en minerale chemie van soliede omsettermat te kwantifiseer. ’n Grondliggende ondersoek na die solidifikasieproses by afkoeling is as noodsaaklik beskou vir ’n diepgaande begrip van die verworwe mineralogie en minerale chemie as ’n funksie van ’n spesifieke ystereindpunt. Mettertyd het dit egter ewe belangrik geword om die uitwerking van die gevolglike mineralogie, en dus die ystereindpunt, op die fisiese eienskappe van minerale strukture met betrekking tot maling-, vrystellings- en loogprosesse verder af in die prosesstroom te kwantifiseer. Ondanks heelwat bedryfskonteks, het nóg bedryfs- nóg vakkundige literatuur veel diepte- en samehangende studies oor die uitwerking van ’n spesifieke ystereindpunt op snelafgekoelde omsettermatstelsels opgelewer. Vorige bevindinge in die literatuur het boonop ’n beperkte kwantitatiewe begrip van die uitwerking op mineralogie en minerale chemie getoon. Die fase- en afkoelingsekwilibriums van ystereindpuntspesifieke Ni-Cu-S-matstelsels met veelvuldige komponente was ook nie ten volle beskikbaar nie. Dít sou veral goed te pas gekom het om die kompleksiteite van omsettermatsolidifikasie as ’n funksie van ystereindpunt te verstaan. Kennis van die fisiese eienskappe van die minerale strukture van omsettermat was kwalik beskikbaar, terwyl selfs minder inligting oor maling-, vrystellings- en loogprosesse opgespoor kon word. Daarom was ’n omvattende ondersoek nodig om hierdie beduidende kennisleemtes met betrekking tot snelafgekoelde omsettermatstelsels in ’n nywerheidsraamwerk aan te vul. Drie Peirce-Smith-omsetterproduksiemonsters wat die wisselende bestek van ystereindpunte by die omsetteraanleg verteenwoordig, is in ’n stelselmatige ondersoek gebruik, tesame met ’n vernuwende kombinasie van moderne ontledingstegnieke, gerekenariseerde termochemiese bewerkings en metallurgiese toetswerk. Die moderne ontledingstegnieke sluit onder andere in hoëresolusie-transmissie-elektronmikroskopie (HRTEM) en gefokusdeioonstraalskandering-elektron-mikroskopie (FIB SEM) tomografie. Die gerekenariseerde termochemiese bewerkings is met behulp van MTDATAfasediagramsagteware uitgevoer. Metallurgiese toetswerk het die maling van laboratoriumlotte teen verskillende spesifieke energieë behels. Nou verwante loogproefnemings is ook as relevant vir hierdie omvattende studie beskou. Die bestudeerde Peirce-Smith-omsettermonsters het op matte met spesifieke eindpunte van 5.17%, 0.99% en 0.15 gewig% Fe gedui. Die hoogste gekombineerde massakonsentrasie van die belangrike onedel en platinumgroepmetale is in die mat met ’n spesifieke ystereindpunt van 0.99% gevind. Die mineralogie van ál drie omsettermatte is oorheers deur die minerale strukture van nikkelsulfied, wat met die natuurlike mineraal heazlewoodiet ooreenstem. Die verskillende omsettermatte het ook die minerale strukture van kopersulfied, NiCu-allooi, spinel en OsRu-allooi bevat. Daar is bevind dat die verkryging van ’n spesifieke ystereindpunt tot meetbare mineralogiese verskille in die relatiewe volopheid van minerale, die eksterne morfologiese kenmerke sowel as minerale chemie lei. Die mineralogiese verskille was veral duidelik te sien tussen die minerale strukture van die ysterryke (5.17% Fe) en ysterarm (0.99% en 0.15% Fe) matte. Fyn mineralogiese verskille is ook tussen die minerale strukture van die ysterarm matte bespeur. Die 0.99% Fe-mat het tipies beduidend meer NiCu-allooi as die 5.17% Fe-mat bevat. Die NiCu-allooistrukture tree oënskynlik op as die hoofversamelaars van die ekonomies belangrike platinumgroepmetale. Mineralogiese waarnemings is gebruik om ’n begrip te ontwikkel van die onderliggende mineralisasiemeganisme van NiCuallooistrukture. Die gevolglike gemineraliseerde strukture is met behulp van driedimensionele rekonstruksies met hoë kleurgetrouheid sowel as in grysskaal voorgestel. Daar is teoreties aangetoon dat variasies in ystereindpuntspesifieke beginsamestellings van suurstofvrye vloeibare matstelsels die solidifikasieroete na die eutetikum wysig. Daarbenewens is die vloeifasesolidifikasie van die ysterryke en ysterarm matstelsels, wat suurstof insluit, op sowat ±2.5 oC gekwantifiseer. Die meeste van die spesifieke energie wat vir maling beskikbaar was, is gebruik om die nikkelsulfiedmatriks te breek, veral vir die ysterryke mat. Berekeninge toon dat die breektempo’s van die minerale strukture van kopersulfied by die 5.17% Fe-mat hoër was as by die 0.15% Fe-mat teen ’n spesifieke energie van 25 kWh/t. Die mate van kopersulfiedvrystelling was hoër by die 5.17% Fe-mat as by die 0.15% Fe-mat by dieselfde spesifieke energie vir maling. ’n Hoër mate van Ni-ekstraksie en Cu-sementasie is verkry toe ysterarm matdeeltjies geloog is. Wat eindpuntseleksiemaatstawwe betref, is die produksie van ’n omsettermat met ’n spesifieke ystereindpunt van 0,99% as die mees geskikte aangewys. ’n Praktiese ystereindpuntbestek van 1.6% tot 1.0% word aanbeveel vir die produksie van ’n omsettermat met ’n gevolglike mineralogiese gehalte wat binne die perke van die Lonmin-raffinadery vir onedel metale val. Hierdie studie bied ’n geïntegreerde begrip van die produksie van onedel en platinumgroepmetale as ’n funksie van ’n gewenste ystereindpunt by Lonmin. Hierdie inligting was nie voorheen in literatuur oor metaalproduksie beskikbaar nie. Nuwe tegnologie vir die monitering en konsekwente beheer van so ’n praktiese ystereindpuntbestek kan dus op grond hiervan in werking gestel word.

This thesis investigates the mode of action of cationic reagents in the recovery of platinum group metals (PGMs) by anion exchange solvent extraction. Industry uses a range of extractants to achieve efficient concentration and separation of PGMs in hydrometallurgical processes, but an understanding of the processes at a molecular level is limited and restricts the options to improve efficiency. The research, sponsored in part by Johnson Matthey and Anglo American, explores two different aspects of the mode of action of reagents used to recover chloride and platinum. Chapter 1 reviews the extraction of chloridometalates in hydrometallurgy and other methods used to recover PGMs. The chapter also covers current ideas on whether formation of outer-sphere anion-cation molecular assemblies or whether larger supramolecular aggregates are responsible for the extraction of PGMs. These two separate routes of study can be investigated by various computational and experimental methods, which are discussed in Chapter 2. In Chapter 3, the model systems chosen to develop the methodologies utilised throughout the thesis are presented. The development involves the extraction of chloride ions by tributyl-phosphate (TBP) and then is extended to extraction of PGM chloridometalates in Chapter 4. Computational methods are used to probe the atomistic and supramolecular theories in predicting the most likely assemblies which will be formed in the transfer of anions between the aqueous and organic phase. Slope analysis and the determination of the contents of the organic phase is used to validate computational models, along with spectroscopic techniques to determine shape and size of assemblies formed during extraction. The application of these methodologies to an amide extractant is discussed in Chapter 5. Computational methods predict the probability of formation of specific complex assemblies during the extraction of PtCl62- by protonated forms of the amide. Determination of the stoichiometry involved in formation of the complex assemblies by slope analysis is reported along with analysis of water, metal and chloride content to confirm the computational model. Final conclusions on all systems explored within the thesis and suggestions for future work are presented in the final chapter. The combination of experimental and computational methods are shown to be very efficient in defining mechanisms of extraction, involving determination of structures formed during the process and how and why they form.

An algorithm to estimate the cooling rate of welding seams on the shell plating of a ship, below the waterline, while it is on voyage has been derived. The demand for this technique has arisen from the wish of ship operators to make it possible for the safe repair of ship structures without taking them out of operation. [1] The strength of the shell plating after welding is determined by its metallurgic structure, which is dependent on the cooling rate, its chemical composition and the original grain size of the base material. [2] The cooling rate for this type of welding seam depends on the velocity of the water flow, the distance from the bow, the thickness of the plate, and the heat from the heat input of the welding. The algorithm makes it possible to calculate the cooling rate for a base material affected by a forced flow of fluid by means of Rosenthal’s equation and thus enabling suitable welding parameters to be determined. As the welding parameters can be chosen to fit the specific repair to be made, it is now possible to determine the suitability of a welding procedure in advance. The algorithm is applicable when determining welding parameters at Hot-Tapping operations as well, where the base material is affected by a forced flow of fluid. A number of experiments have been performed and the results support the theoretical model. The research project continues with the aim of finding an algorithm to include the enhanced cooling rate due to the layer of boiling fluid on the back of the base material. A method to improve the measurements of the most important parameter in the algorithm has been developed and makes it possible to build up a quantitative database of typical values for various configurations.