Journal articles: 'Cyanide leaching'

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Tong, Linlin, Qianfei Zhao, Qiang Liu, Zhehao Li, Chongzhe Chi, Yu Zhang, and Hongying Yang. "Cyanide Release Characteristics of Solid Waste in Gold Smelting Process." Minerals 12, no. 10 (October 8, 2022): 1269. http://dx.doi.org/10.3390/min12101269.

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To explore the relationship between total cyanide and easily liberatable cyanide in cyanide tailings and its impact on the environment, the leaching and release characteristics of total cyanide and easily liberatable cyanide in a tailings pond were studied using a dynamic leaching experiment, and a dynamic model was established. The results show that the release concentration of total cyanide in cyanide tailings is higher than that of easily liberatable cyanide. With the increase in leaching time, the release of cyanide is more sensitive to leaching intensity. The first-order kinetic, second-order kinetic, modified Elovich, double constant, and parabolic diffusion equations were used to fit the cumulative release of cyanide. According to the kinetic results of cyanide cumulative release, in addition to the first-order kinetic equation, the other four equations revealed good fitting for the cyanide leaching process, which shows that cyanide released under simulated rainwater leaching was not simply via surface diffusion, but controlled by multiple factors.

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Zhu, Chao, Bao Liang Ge, Zhao Yi Lu, and Wen Zhu. "Biooxidation Pretreatment Cyanide Leaching of a Flotation Gold Concentrate." Advanced Materials Research 581-582 (October 2012): 1106–9. http://dx.doi.org/10.4028/www.scientific.net/amr.581-582.1106.

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This study reached a gold ore which contain 3.83g/t gold, to investigate the available gold recover methods, direct cyanide leaching test and “biooxidation-cyanide” leaching process were utilized after enrich gold by flotation. When regrinding the flotation concentrate to 95% -325mm, the leaching rate of “biooxidation-cyanide” leaching reached 94.47%, compare with direct leaching, the leaching rate increased almost 67%. Obviously bacterium oxidation is a useful pretreatment for gold leaching.

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Feng, Tian Ran, Zhi Bin Han, and Gan Guo Dong. "Industrial Test of HAT6065 Cyanide Leaching Stirring Tank." Applied Mechanics and Materials 552 (June 2014): 315–19. http://dx.doi.org/10.4028/www.scientific.net/amm.552.315.

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HAT type cyanide leaching stirring tank increases gas-liquid mass transfer area to increase leaching speed through changing inflation mode. This article introduces the industrial experiment study situation of HAT6065 cyanide leaching stirring tank with the results show that slurry stirred and suspended evenly without delamination, which can adapt to the condition of high concentration of sulfur, iron and arsenic elements. The leaching rate of HAT6065 cyanide leaching stirring tank is about 6.61% higher than that of conventional cyanide stirring tank.

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Yanbo, Chen, Qin Guanglin, Li Guangsheng, Zhu Xingfu, Yu Congquan, Lu Zhongbo, Ji Qiang, et al. "Experimental study on thiosulfate leaching of gold from a high copper gold concentrate." E3S Web of Conferences 271 (2021): 04001. http://dx.doi.org/10.1051/e3sconf/202127104001.

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The conventional cyanide leaching process is used to extract gold from a high copper gold concentrate. Because the copper associated minerals consume sodium cyanide in large quantities, the cost of the reagents is high and the economic benefit is not ideal. At the same time, a large number of cyanide tail slag are produced, which brings a series of environmental problems. In order to solve the environmental problems caused by excessive sodium cyanide consumption and cyanogen slag, the feasibility of leaching gold by thiosulfate in copper ammonia system was studied. The gold leaching rate of thiosulfate was increased to more than 90% by using the direct thiosulfate leaching process and pretreatment thiosulfate leaching process, which was close to the gold leaching index of sodium cyanide at the production site.

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Pang, Wen Hao, Quan Jun Liu, and Peng Ding. "Experimental Study on Mineral Processing of Carlin-Type Gold Deposits in Guizhou." Advanced Materials Research 756-759 (September 2013): 41–43. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.41.

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The gold ore which contained 4.73 g/t Au was selected from carlin-type gold deposits in Guizhou. Three experiments on the gold ore were carried out. They were direct cyanide leaching, oxidizing roasting-cyanide leaching and flotation-oxidizing roasting-cyanide leaching. The experiments revealed that with the third process, ideal production index were obtained. The optimum conditions were confirmed: combined collector ammonium dibutyl dithiophosphate dosage was 60 g/t and butyl xanthate dosage was 120 g/t. Sodium cyanide dosage was 7000 g/t. As a result, we obtained satisfying selecting targets: The grade of gold was 42.0 g/t in the flotation concentrate. The gold leaching rate was up to 96.18%, and gold recovery was 88.23% after cyanide leaching. It was of important effect on decreasing resources waste and reducing environment pollution to research the project.

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Chao, Xu, Cai Mingming, Gao Tengyue, Li guangsheng, Zhu xingfu, Lu Zhongbo, Chen Yanbo, et al. "Study on Technological Process Innovation of Non-Cyanide Leaching." E3S Web of Conferences 267 (2021): 02064. http://dx.doi.org/10.1051/e3sconf/202126702064.

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Nowadays, there are many gold leaching processes, and the dominant one is cyanidation, but the virulence of cyanidation seriously endangers the environment and human health. In order to reduce environmental pollution and improve the recovery rate of gold, metallurgical workers put forward a variety of new gold leaching methods, which can be roughly divided into two types: one is to develop pretreatment technology on the basis of traditional cyanidation method; The other is non-cyanide leaching of gold. Based on the existing Non-Cyanide leaching technology, this paper puts forward the process innovation of Non-Cyanide leaching technology, thiourea method and dilute nitric acid pre-oxidation treatment process. The thiourea non-cyanide leaching system was investigated. According to the leaching situation of gold and silver in raw ore, the innovative scheme of gold and silver leaching technology was selected. Compared with other treatment methods, thiourea method and dilute nitric acid pre-oxidation treatment technology overcome the danger of high pressure, and the nitrogen oxide gas produced in the dilute nitric acid oxidation process can be recycled, which basically does not pollute the environment.

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Alarcón, Alejandro, Carlos Segura, Carlos Gamarra, and Juan Carlos F. Rodriguez-Reyes. "Green chemistry in mineral processing: chemical and physical methods to enhance the leaching of silver and the efficiency in cyanide consumption." Pure and Applied Chemistry 90, no. 7 (July 26, 2018): 1109–20. http://dx.doi.org/10.1515/pac-2017-0904.

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Abstract The leaching of valuable metals from mineral ores is the basis of several extractive economies around the world, but the strategies employed often need to rely on dangerous compounds such as cyanides. Due to the complex nature of most ores, leaching processes are slow and have a low efficiency in noble metal extraction, which is usually improved by fine-milling the mineral. In this manuscript, we consider this strategy, demonstrating that it may increase the amount of silver leaching, but at the expense of a higher consumption of cyanide, which renders the process inefficient (only 2% of consumed cyanide is employed to complex silver). The increase in the yield of the desired product without the smarter use of dangerous compounds is shown as a paradigm of the need to insert green chemistry principles in industrial processes. We further present the result of two potential strategies for greener mineral processing: the use of ultrasound to eliminate passivating layers formed during the leaching process and the use of chemical pretreatments to eliminate possible sources of passivation. These strategies can increase the amount of silver extraction and simultaneously increase the efficiency in cyanide consumption. The convenience of these pretreatments in the framework of the green chemistry principles, as well as the challenges towards their implementation at industrial scale, is discussed.

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Wang, Wei Zhi, Miao Miao Han, and Chun Guang Yang. "Experimental Research on Cyanidation Leaching of a Gold Ore." Advanced Materials Research 550-553 (July 2012): 2835–39. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.2835.

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The gold ore is oxidized ores, and it is not suitable for flotation separation. The cyanide leaching is used for the recovery of gold. Experimental studies of cyanidation leaching for a oxidized gold ore were carried out. The factors that influence leaching such as grinding size, sodium cyanide quantity, pulp density, extraction time and segmentation leaching were conducted. And experiment pretreatment test with the copper ion which influences leaching. The results demonstrated that the good index of leaching rate 90.11% could be reach.

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Lobanov, V. G., R. E. Khabibulina, O. B. Kolmachikhina, and O. Yu Makovskaia. "Selection of a leaching system for the extraction of gold from the ore of the Byn’govskoye deposit." iPolytech Journal 26, no. 4 (January 2, 2023): 688–96. http://dx.doi.org/10.21285/1814-3520-2022-4-688-696.

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A theoretical substantiation of an environmentally friendly technology for extracting gold from mineral raw materials is presented. In terms of an alternative to conventional cyanide, the authors propose chlorine-bearing derivatives of organic isocyanuric acid (C3H3N3O3). In the studied process, this reagent combines the roles of a long-acting oxidant and complexing agent due to the resulting Cl– ion. For experimental purposes, the rotating disc technique was applied. Experimental results were evaluated by measuring the concentration of gold in solutions using the atomic adsorption method. The theoretical characteristics of gold dissolution using the proposed reagent were studied. In order to evaluate the applicability of the revealed regularities for practical purposes, comparative indicators for leaching gold from the ore of the Byn’govskoye deposit (Sverdlovsk Oblast) using the proposed reagent, cyanide and CYCAD cyanide substitute (China) were evaluated. The dependence of the gold disc dissolution rate on temperature, as well as leaching reagent and hydrochloric acid concentrations, were studied. In disc sample experiments, the exponential dependence of the dissolution rate on the concentration of the studied reagent was established. In this case, the maximum intensity of the process is achieved at a concentration higher than 50 g/dm3. The optimum acidity level comprises 0.3–0.4 g ion/dm3 of hydrochloric acid. Despite an increase in temperature being shown to accelerate the dissolution process, this appears to be technologically unjustified. Under optimal conditions, the gold disc dissolution rate reaches 0.5•10-3 g ion/(cm2•min), which is approximately one hundred times higher than during the dissolution by the cyanic solutions in conventional modes. Close gold extraction values were achieved in the solutions of cyanides and chlorine-bearing derivatives of isocyanuric acid during the leaching of gold from the ore under the comparable conditions. For CYCAD solutions, the same indicator is two times lower. The results of the performed studies demonstrate the high dissolution rate of gold using the proposed reagent along with the technological possibility of leaching gold from ores using this environmentally friendly reagent.

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10

Raphulu, M. C., and M. S. Scurrell. "Cyanide leaching of gold catalysts." Catalysis Communications 67 (July 2015): 87–89. http://dx.doi.org/10.1016/j.catcom.2015.04.011.

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11

Fu, Pingfeng, Zhenyu Li, Jie Feng, and Zhenzhong Bian. "Recovery of Gold and Iron from Cyanide Tailings with a Combined Direct Reduction Roasting and Leaching Process." Metals 8, no. 7 (July 21, 2018): 561. http://dx.doi.org/10.3390/met8070561.

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Cyanide tailings are the hazardous waste discharged after gold cyanidation leaching. The recovery of gold and iron from cyanide tailings was investigated with a combined direct reduction roasting and leaching process. The effects of reduction temperature, coal dosage and CaO dosage on gold enrichment into Au-Fe alloy (FexAu1−x) were studied in direct reduction roasting. Gold containing iron powders, i.e., Au-Fe alloy, had the gold grade of 8.23 g/t with a recovery of 97.46%. After separating gold and iron in iron powders with sulfuric acid leaching, ferrous sulfate in the leachate was crystallized to prepare FeSO4·7H2O with a yield of 222.42% to cyanide tailings. Gold enriched in acid-leaching residue with gold grade of 216.58 g/t was extracted into pregnant solution. The total gold recovery of the whole process reached as high as 94.23%. The tailings generated in the magnetic separation of roasted products, with a yield of 51.33% to cyanide tailings, had no toxic cyanide any more. The gold enrichment behaviors indicated that higher reduction temperature and larger dosage of coal and CaO could promote the allocation of more gold in iron phase rather than in slag phase. The mechanism for enriching gold from cyanide tailings into iron phase was proposed. This work provided a novel route to simultaneously recover gold and iron from cyanide tailings.

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12

Romero, Adam M. "Beyond the Mother Lode." California History 95, no. 1 (2018): 2–24. http://dx.doi.org/10.1525/ch.2018.95.1.2.

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This article narrates California's chemically induced second gold rush through the lens of synthetic cyanide. In coupling California's geological, environmental, and economic history to the changing nature of gold ore in the late 1880s, it explores the role that the development of cyanide leaching and the industrialization of cyanide production had on California's mining landscapes. As such, it places California as a critical node in the globalization of cyanide leaching techniques. In doing so, it links disparate geographies and histories together to explore the chemicalization of California gold mining.

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13

Picazo-Rodríguez, N. G., F. R. Carrillo-Pedroza, Martínez Luévanos, M. J. Soria-Aguilar, and I. Almaguer-Guzmán. "Sº and jarosite behavior during recovery of values from the direct leaching residue of sphalerite using cyanide and glycine." Journal of Mining and Metallurgy, Section B: Metallurgy, no. 00 (2021): 31. http://dx.doi.org/10.2298/jmmb191221031p.

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This paper reports the effect of the components of a direct leaching residue (jarosite and elemental sulfur), on the recovery of valuable metals such as gold and silver. Leaching media such as cyanide and mixtures of cyanide with glycine were used to recover the gold and silver from the residue; however, a low recovery of these metals was obtained. The above due to the negative effect of its components which cause problems in the extraction process such as encapsulation of silver (due to jarosite) and the formation of thiocyanate and re-precipitation of silver (due to sulfur). Various treatments prior to leaching were tested, finding that when the residue is desulfurized with perchlorethylene and subjected to an oxidizing alkaline hydrothermal treatment, the gold extraction increased from 39.73 to 88% and the silver extraction of 64.76 to 94.29%. Additionally, it was determined that when cyanide is assisted by glycine, the latter decreases the cyanide consumption by inhibition of the dissolution of iron and sulfur in cyanide.

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Kirilchuk, Maksim, and Adam Mustapha. "Comparative experiments on the activation cyanide and chloride re-leaching of gold from the secondary mineral material of heaps of Aprelkovo mine." E3S Web of Conferences 192 (2020): 02016. http://dx.doi.org/10.1051/e3sconf/202019202016.

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This article presents the results of comparative experiments on the activation chloride and activation carbonate-cyanide leaching of gold from the secondary mineral material of heaps of Aprelkovo mine. A cyanide scheme with a gradual increase in the cyanide concentration in the pregnant solution was adopted as a control scheme for percolation leaching. To establish the maximum recovery of gold and associated components, preliminary experiments with agitational cyanide leaching were carried out. In the course of the experimental work, some of the problems of gold recovery according to the classical cyanide scheme applicable to this deposit were identified and, thanks to the use of activated solutions, were solved. The reasons for the insufficiently high recovery are clogging and limited access of the complexing agent to encapsulated and chemically bound gold inclusions due to their high dispersion in the crystal lattices of concentrating minerals and the presence in the ore of minerals that tend to absorb water with a pronounced hydration effect.

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Zalesov, M. V., V. A. Grigoreva, V. S. Trubilov, and A. Ya Boduen. "Designing of engineering solutions to enhance efficiency of high-copper gold-bearing ore processing." Mining Industry Journal (Gornay Promishlennost), no. 5/2021 (November 12, 2021): 51–56. http://dx.doi.org/10.30686/1609-9192-2021-5-51-56.

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The modern metals industry is characterised by a downward trend in the quality of ores involved in processing, and conventional methods of extracting useful components are inefficient for raw materials with complex composition. To maintain the growing level of metal production it is required to introduce new efficient technologies for processing of low-grade and refractory ores as well as man-made deposits. The article describes processing methods of refractory raw materials with high cyanide content using copper-gold ores as an example, where gold is the primary commodity, and copper is the accompanying useful component. The most common method of processing copper-gold ores is preconcentration followed by selective leaching of copper and gold. In some cases, technologies involving copper by-products and cyanide recovery from the cyanide leaching solutions offer equally effective options for processing of the copper-gold ores and concentrates. Copper-gold ores are processed at gold mines using the cyanide procedures, supplemented if required by gravity and flotation concentration. In all variations of the cyanide treatment, most of copper minerals actively react with cyanides of alkali metals, binding the CN– ions into the copper complex of [Cu(CN3)]2–. This reaction results in an increased solvent consumption, as well as in number of challenges related to cleaning tailings and slurries from highly toxic cyanide compounds and dissolved copper. In addition to technological complications associated with the need to meet strict requirements for the maximum permissible concentrations, copper accumulated in the cycling solutions also causes a decrease in gold extraction from the processed ores.

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BAS, A. D., E. KOC, E. Y. YAZICI, and H. DEVECI. "Treatment of copper-rich gold ore by cyanide leaching, ammonia pretreatment and ammoniacal cyanide leaching." Transactions of Nonferrous Metals Society of China 25, no. 2 (February 2015): 597–607. http://dx.doi.org/10.1016/s1003-6326(15)63642-1.

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Garza Román, Marleth Roxana, Francisco Raúl Carrillo Pedroza, Nallely Guadalupe Picazo Rodríguez, Ma de Jesus Soria Aguilar, Isaías Almaguer Guzmán, and Josué Chaidez Félix. "Effects of pretreatment and leaching medium on the extraction efficiency of Au and Ag from a chalcopyrite leaching by-product." DYNA 88, no. 218 (August 19, 2021): 119–26. http://dx.doi.org/10.15446/dyna.v88n218.90284.

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Precious metals such as gold (Au) and silver (Ag) are essential to our modern society due to their unique properties, such as high conductivity and physical and chemical resistance. They are teofn concentrated in by-products during the extraction of base metals. In the present work, a chalcopyrite leaching residue, constituted mainly of elemental sulfur and jarosites, was subjected to different pretreatments and leached with different leaching media to recover Au and Ag. The solid residue was pretreated by desulfurization,peroxidation,desulfurization+peroxidation and leached with cyanide, cyanide+glycine, and glycine. For comparison, samples without pretreatment were also leached using the same leaching media. Changes in the mineralogical species were followed to explain the effects of pretreatment and leaching medium on the dissolution of Au and Ag. Results indicate that the highest extraction of gold and silver (Au:99.50%, Ag:46.71%) is achieved by using a combined desulfurization+peroxidation pretreatment and cyanide as leaching medium.

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Ghobeiti Hasab, Mehdi, Fereshteh Rashchi, and Shahram Raygan. "Comparison of Cyanide and Chloride-Hypochlorite Leaching of a Ball Milled Refractory Gold Concentrate with Ultra-Fine Particles." Advanced Materials Research 829 (November 2013): 869–73. http://dx.doi.org/10.4028/www.scientific.net/amr.829.869.

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In this research, cyanide and chloride–hypochlorite leaching of gold from a pyritic concentrate (particle size: −75+53 µm, gold content: 27.15 g/t) were compared. It was shown that only 13.6 % of gold was extracted after 24 h leaching by cyanide, as compared to 37.2 % after 8 h by chloride–hypochlorite. Effect of ultra–fine milling of the concentrate on the leaching was investigated using a high–energy planetary ball mill at different milling times. It was found that the leaching rate of gold by both leachants could be substantially enhanced after the milling of the particles to sub–micron dimensions. This was attributed to the increase of specific surface area and the accumulation of energy in the pyrite particles. After 480 min milling (air atmosphere, 300 rpm, sample/ball:1/20), 96.1 % of gold was extracted by 24 h cyanide leaching, while 100 % extraction could be achieved after only 45 min milling and 30 min chloride–hypochlorite leaching. This was attributed to the oxidation of pyrite by the hypochlorite oxidant and the complete liberation of gold encapsulated in the pyrite particles.

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Yu, Xian Jin, Ya Li Zhang, and Huai Mei Li. "Recovery of Iron from Cyanide Tailings with Reduction Roasting–Water Leaching- Magnetic Separation." Advanced Materials Research 396-398 (November 2011): 486–89. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.486.

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Cyanide tailings have become one kind of the most hazardous solid waste. In order to recycle iron in the cyanide tailings, we present a technique using roasting- water leaching- magnetic separation. After analysis of the different parameters on recovery efficiency of iron, the optimum reaction parameters were proposed as the following: in reduction roasting process, weight ratios of cyanide tailings / activated carbon at 100:10, roasting at 750 °C; the liquid to solid ratio is 15:1 (ml /g), leaching at 60 °C for 5 min at water leaching. The grade of magnetic concentrate 53.8231％Fe and recovery rate of 76.5458％ were obtained. Mineralography of roasted product, water-leached sample were studied by X-ray powder diffraction technique (XRD).

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Liu, Jin, Bin Quan Jiao, and Dong Wei Li. "Study on the Toxicity of Cyanogen-Containing Industrial Waste Residues." Advanced Materials Research 160-162 (November 2010): 927–32. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.927.

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By using a series of tests for corrosivity, acute toxicity and leaching toxicity of cyanide-containing wasteresidues, the toxicity of cyanide-containing wasteresidues has been investigated. According to acute toxicity test, the wasteresidues showed no acute toxicity. The experiment further indicated that the cyanide compounds were tested in the 0.15 ～ 0.60 concentration rang, mean (0.429), standard deviation (0.195) and variation coefficient (45.5%). The pH value range for leaching liquor of slag yard was 9.21～13.09 at the mean 10864, and the standard deviation and variation coefficient were 1.553 and 14.3% respectively. The research revealed that the cyanide compounds content in wasteresidue samples was distributed very unevenly, and the content of cyanide compounds was not exceeded the standard. Based on the current analysis results, those cyanide-containing wasteresidues were defined as hazardous solidwastes with corrosivity.

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Kozhonov, Almaz, Kulgamal A. Nogaeva, and Aleksei V. Kritskii. "Studies on Hydrometallurgical Treatment of Oxydized Gold-Bearing Copper Ore." Materials Science Forum 989 (May 2020): 519–24. http://dx.doi.org/10.4028/www.scientific.net/msf.989.519.

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Inherent problems of oxidized gold-bearing copper ores processing and a comparison of hydrometallurgical methods, applied for such materials, are discussed in this article. Studies on sulfuric acid and cyanide leaching have been carried out, using the following sample of oxidized ore from one of the copper deposits (Kyrgyzstan), %: 15 Mg O, 45.6 SiO2, 0.1 S, 20 Ca O, 12.1 Fe2O3, 0.86 Cu, 1.78 Au, 9.61 Ag. Studies have been carried out. Agitation sulfuric acid leaching able to extract up to 29.9% of copper. At the same time, column sulfuric acid leaching able to extract up to 78.5% of total copper and 85.23% of copper presented by acid-soluble compounds. In case of precious metals, the agitation cyanide leaching is able to extract up to 97.6% of gold in 24 h. Increasing the grinding fineness up to 90% - 74 μm reduces cyanidation duration down to 12 h. The consumption of sodium cyanide is 4.8 kg/t of ore. At the same time, column cyanide allows to extract 73.5% Au and 81.9% Ag during 111 days, whereas 52.4% of gold is recovered in the first 10 days. Consumption of sodium cyanide is 5.45 kg/t. The most efficient ways for processing of such materials are proposed.

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Yessengarayev, Ye K., B. N. Surimbayev, B. S. Baimbetov, S. V. Mamyachenkov, and T. S. Kanaly. "Ore treatment hydrogen peroxide during heap leaching of gold." Kompleksnoe ispolʹzovanie mineralʹnogo syrʹâ/Complex Use of Mineral Resources/Mineraldik shikisattardy Keshendi Paidalanu 316, no. 1 (March 15, 2021): 5–14. http://dx.doi.org/10.31643/2021/6445.01.

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Over the past century, many problems have been focused on the problems of low leaching rate of gold and methods have been developed to intensify the leaching of gold. Among these methods, the use of hydrogen peroxide to accelerate the leaching of gold is known. In order to intensify the leaching process, the indicators of cyanide leaching of gold from ore using hydrogen peroxide were studied. This article presents the results of assay-gravimetric, chemical, and mineralogical analyses of gold-bearing ore from the Sari Gunay Deposit (Iran). The content of sulfide sulfur ore belongs to the category of low-sulphide, by oxidation of sulphur (50.70%) to the category of oxidized ores. Thermodynamic analysis of possible reactions of ore components with hydrogen peroxide is carried out. Laboratory studies on cyanide leaching of gold have shown that the maximum recovery of gold is 52.92% at a concentration of hydrogen peroxide of 0.5%, the recovery of gold without ore treatment is 52.03%. The results of laboratory and column tests with and without treatment with hydrogen peroxide (H2O2–0.5%) were compared. Treatment of gold-bearing ore with hydrogen peroxide during heap leaching of gold increases gold recovery by 1.2% and amounts to 55.89%, without treatment - 54.69%. This increases the consumption of sodium cyanide by 0.04 kg/t.

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Manzila, Archippe Ngwey, Thandazile Moyo, and Jochen Petersen. "A Study on the Applicability of Agitated Cyanide Leaching and Thiosulphate Leaching for Gold Extraction in Artisanal and Small-Scale Gold Mining." Minerals 12, no. 10 (October 14, 2022): 1291. http://dx.doi.org/10.3390/min12101291.

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Mercury amalgamation is the method of choice to recover gold in artisanal and small-scale gold mining (ASGM). However, despite the low cost and simplicity of this method, the use of mercury presents serious health and environmental risks, as well as low efficiency in gold extraction. This study investigates the application of cyanide and thiosulphate leaching as alternatives to mercury amalgamation. This investigation was undertaken by conducting leach experiments using cyanide at 1 g/L, 3 g/L, and 5 g/L, and ammonium thiosulphate at 0.1 M and 0.5 M, on three ore samples originating from an artisanal mining area in Zimbabwe. The operating conditions (T = 26 °C, solids loading: 30%, particle size: −300 + 150 µm) were selected to mimic as closely as possible the conditions of artisanal mining processes. It was found that cyanide leaching was the better performing technology compared to thiosulphate leaching, as it achieved gold extractions of 71.6%, 69.7%, and 67.8% for the three ore samples (Sample 1, Sample 2, and Sample 3, respectively), whereas thiosulphate leaching achieved gold extractions of 54.1%, 35.6%, and 38.0% for the three ores, respectively. Both methods outperformed mercury amalgamation, which typically achieves gold recoveries of 30%–50%. Studying the minerology of the ores, using XRF, XRD, QEMSCAN, SEM-EDS, and a diagnostic leach, revealed the presence of sulphide minerals hosting refractory gold which contributed to the low gold extractions observed. Besides achieving higher gold extraction, cyanide leaching proved to be a system that is easier to control compared to thiosulphate leaching, making it much more attractive to artisanal miners.

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Seflek, Cemaliye, and Oktay Bayat. "Microwave-Assisted Grinding of Bolkardag (Nigde, Turkey) Gold Ore and Enhanced Cyanide Leachability." Metallurgical Research & Technology 115, no. 5 (2018): 508. http://dx.doi.org/10.1051/metal/2018039.

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This experimental work aims at studying the effect of particle size on the microwave pre-treatment for the grindability of Bolkardag (Nigde, Turkey) gold ore for cyanide leaching. Three different particle size batches (−8 + 4.7 mm, −4.75 + 2 mm and −2 + 1 mm) were used for microwave treatment. Each sub-samples were exposed to four different power levels of microwave energy (0.09, 0.18, 0.36 and 0.6 kW) at exposure times of 5, 10, 15 and 30 minutes and then grindability characteristic of the treated samples were investigated with Berry and Bruce comparative grindability method. It was clearly seen that increasing power level and exposure time caused a reduction in comparative Bond Work index. A maximum reduction in Bond Work index (73.54%) was achieved by 0.6 kW at 30 minutes of microwave treatment. Compared to the untreated sample’s results, gold and silver extraction rates increased, using microwave-treated samples, about 7% and 9% after 77 hours cyanide leaching, respectively. Additionally, the hydrated lime added samples (after 0.6 kW at 30 minutes of microwave treatment) were used in the cyanide leaching tests to determine the possible effect. It was observed that there was no significant difference on leaching extraction rates using lime free or lime added samples. Applying microwave pre-treatment before cyanide leaching, the gold and silver extraction rates could be increased and also the cost of communition could be reduced due to easier breakage of the ore due to a significant decrease in Bond Work index.

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Duru, N. "EFFECT OF PRESSURE ON GOLD CYANIDE LEACHING." SUSTAINABLE EXTRACTION AND PROCESSING OF RAW MATERIALS 2, no. 2 (October 10, 2021): 28–35. http://dx.doi.org/10.58903/b15171914.

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Although the effect of high oxygen pressure on gold recoveries at elevated slurry temperatures was previously investigated, the sole effect of the pressure at ambient temperatures on cyanide leaching with the presence of nearly enough oxygen for the cyanide reactions to occur has not been found to be studied. This research work was carried out with the objective of investigating the effect of pressure on the recovery of gold from an oxide gold ore and flotation tailing (Carbon in leach (CIL) feed) samples during cyanide leaching process at room temperature. Pressure cyanidation experiments were run in a batch autoclave under different air and nitrogen gas pressures, and pH conditions. Atmospheric bottle roll leach tests for 24 and 8 hours resulted in 90.5% and 66.4% gold recoveries, respectively, whereas 8 hours batch autoclave leach tests under 90 psi air pressure resulted in 88.8% gold recovery from oxide ore samples. Flotation tailing samples leached under atmospheric and under 90 psi air pressure for 8 hours resulted in 16.8% and 34.5% gold recoveries, respectively.

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Li, Qing, Bao Liang Ge, Jie Liu, and Chao Zhu. "Recovering Gold from a Gold-Bearing Pyrite by Flotation and Chemical Process." Advanced Materials Research 610-613 (December 2012): 81–85. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.81.

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The ore assays 2.5g/t Au, 23.4% S and 56.6% Fe. This research enriched the gold by flotation, and recovered it by a chemical process. The obtained flotation concentrate contains 66.35%g/t gold and 37.06% S with recovery 96.14% and 96.42% respectively. A roasting process was conducted at 900-1000°C for 5.5hrs, followed by cyanide leaching of the residue. The gold leaching rate reaches 87.4% with an adsorption rate of 97.6%. Furthermore, the regrinding of the concentrate to 95% -0.18μm was conducted, and followed by cyanide leaching at pH11.5 for 12hrs. The results show the amount leached gold reaches 92.5% with an adsorption rate of 99.21%, which increases by 1.61% and 5.1% in comparison with the roasting-leaching process.

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Sekisov, A. G., T. G. Konareva, A. Yu Lavrov, V. Yu Burov, and E. S. Emirziadi. "Efficiency of using peroxide-carbonate compounds in reagent complexes for leaching gold hard to recover from placer." IOP Conference Series: Earth and Environmental Science 962, no. 1 (January 1, 2022): 012058. http://dx.doi.org/10.1088/1755-1315/962/1/012058.

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Abstract The article deals with the data of theoretical and experimental studies of the processes of activation gold leaching using reactive peroxide carbonate compounds, obtained by electrophotochemical treatment of solutions of initial reagents of the corresponding composition, in the composition of reagent complexes. The obtained results of the experiments on the interaction of various carbonate and peroxide-carbonate compounds with sodium cyanide in the process of mixing activated and non-activated solutions with aqueous cyanide solutions in different order definitely prove that supramolecular percarbonate-cyanide compounds are being formed in them. It has been established that these activated solutions, prepared on the basis of the initial hydrocarbonate ones, contain metastable compounds that provide a higher rate of gold extraction from crude minerals than standard aqueous cyanic solutions of the same initial concentration.

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Razmakhnin, KK, and PA Vasiljuk. "Technological and environmental features of heap leaching of Delmachik gold-bearing ores deposit." IOP Conference Series: Earth and Environmental Science 991, no. 1 (February 1, 2022): 012044. http://dx.doi.org/10.1088/1755-1315/991/1/012044.

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Abstract The problem of gold ores hydrometallurgical processing with using sodium cyanide is evaluated. The prospects for the development of the use of cyanide-free reagents for leaching gold from ores are studied. The possibility of introducing a cyanide-free environmentally friendly reagent instead of the widely used sodium cyanide was determined. The results of experimental studies on the comparability of the processing of gold ores using sodium cyanide and a reagent based on sodium cyanoate are obtained. The optimal parameters of the technological process for the extraction of gold from ores using a cyanide-free reagent are established.

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Ficeriová, Jana, Peter Baláz, Erika Dutková, and Eberhard Gock. "Leaching of Gold and Silver from Crushed Au-Ag Wastes." Open Chemical Engineering Journal 2, no. 1 (February 14, 2008): 6–9. http://dx.doi.org/10.2174/1874123100802010006.

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Au-Ag noble metal wastes represent a wide range of waste types and forms with various ballast elements and components. The thiourea process of gold and silver extraction from ores, concentrates or secondary raw materials consists of gold and silver leaching into the thiourea solution and the consequent precipitation of these metals from the solution. Due to the non-toxic character of thiourea it is the perspective alternative to the up to now most frequently used cyanide method. The thiourea leaching of gold and silver from electronic waste, goldsmith’s waste and ceramic waste using crushing as the pretreatment step was investigated. For electronic waste, it was possible to achieve 97 % gold and 94 % silver recovery within 120 minutes of thiourea leaching. Up to 98 % of gold and 96 % of silver were recovered from goldsmith’s waste after 60 minutes of leaching. In the case of ceramic waste, we achieved up to 98 % gold and 97 % silver extraction efficiency after only 45 minutes of leaching. In comparison with the classical cyanide leaching, thiourea leaching acts faster and without a harmful environmental impact.

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Dadgar, Ahmad. "Refractory concentrate gold leaching: Cyanide vs. bromine." JOM 41, no. 12 (December 1989): 37–41. http://dx.doi.org/10.1007/bf03220846.

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Parga, José R., Jesús L. Valenzuela, and Cepeda T. Francisco. "Pressure cyanide leaching for precious metals recovery." JOM 59, no. 10 (October 2007): 43–47. http://dx.doi.org/10.1007/s11837-007-0130-4.

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Yang, Yongbin, Meixiang Lai, Qiang Zhong, Qian Li, Bin Xu, and Tao Jiang. "Study on Intensification Behavior of Bismuth Ions on Gold Cyanide Leaching." Metals 9, no. 3 (March 20, 2019): 362. http://dx.doi.org/10.3390/met9030362.

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Gold cyanide leaching is inefficient with conventional cyanidation. Bismuth ions can improve the efficiency of gold cyanidation by intensifying gold dissolution. The electrochemical behavior, structure information, and surface product of gold anodic dissolution were studied during the intensification of bismuth ions on gold cyanide leaching. The electrochemical analysis showed that the bismuth ions can not only improve anode current density, but also make gold dissolve at a lower potential, increase the corrosion current and intensify gold anodic dissolution. The microstructure analysis showed that bismuth ions intensified the cyanide corrosion of the gold surface, causing a large number of loose honeycombs, gullies, pits, and large holes on the gold surface. The XPS, FT-IR, and Raman analysis showed that there is weak information of C≡N in the spectrum of Bi intensification contrasting to that of conventional cyanidation. Cyanide compounds may be the insoluble AuCNads, which does not deposit on the surface of gold plate after Bi intensification cyanidation. The insoluble intermediate AuCNads is likely to react promptly with CN- to form soluble Au(CN ) 2 − , making less insoluble AuCNads deposits on the gold surface. Therefore, bismuth ions can promote the dissolution of insoluble AuCNads, prevents its passivation film to cover around the gold plate, keeps cyanide good contact with gold, and finally accelerates the cyanide dissolution of gold.

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Nazri, Amirul Islah, N. I. Basir, and Muhamad Nazri Murat. "A Conceptual Reactor Design Based on Combination of Pressure Leaching - Electrochemical Deposition Techniques for Study of Gold Recovery from e-Waste." Advanced Materials Research 1113 (July 2015): 187–92. http://dx.doi.org/10.4028/www.scientific.net/amr.1113.187.

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In Malaysia, the amount of electronic waste (e-waste) generated in 2008 was stated to be around 688,000 metric tonnes and was forecasted to increase to 1.11 million metric tonnes in the year 2020 [1]. Typical e-waste contains some elements of precious metal, which is mainly generated from the result of the revolution of computer technology. Currently, the most common technique being practiced to recover gold from e-waste is through cyanide leaching system and subsequent gold recovery techniques which may include electrodeposition. However, due to toxicity of the harmful cyanide, a non-cyanide extraction route is now becoming a necessity to minimize safety and environmental issues. In order to maximize the efficiency and safety of gold recovery from e-waste, a non-cyanide route using a reactor based on electrodeposition technique has been proposed. This paper explains the conceptual reactor design which combines the pressure leaching process of gold from e-waste and the gold recovery using electrodeposition via a non-cyanide route as a safer and environmental friendly process in recovering gold from e-waste.

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Liu, Ziyuan, Jue Kou, Yi Xing, Chunbao Sun, Peng Liu, and Yuxin Zhang. "Ozone Ice as an Oxygen Release Reagent for Heap Leaching of Gold Ore." Minerals 11, no. 11 (November 11, 2021): 1251. http://dx.doi.org/10.3390/min11111251.

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The issue of poor aeration efficiency and low oxygen transfer in the heap leaching of gold has gained considerable attention. In this study, ozone ice was studied as an oxygen release reagent in the cyanide heap leaching of gold at a low temperature of approximately 5 °C, owing to its effective oxidation and clean and green properties. Quartz Crystal Microbalance with Dissipation (QCM-D) was used to monitor the effect of different ratios of cyanide and oxygen concentrations on the gold leaching rate. The results showed that the leaching rate doubled when the dissolved oxygen (DO) was increased from 8.2 mg/L to 12 mg/L at a relatively high cyanide concentration of 60 mg/L. The release of oxygen during the process of ozone ice melting was analyzed by simulating the oxygen-deficient condition of the ore heap in column leaching. In the first stage of ice melting, the DO in the solution increased dramatically, and the rate of increase improved with increased initial ozone concentration in the ice. In the second stage of ice melting, the rate of increase in the DO of the solution was not significantly affected by the initial ozone concentration in the ice; this was consistent with the decomposition rate of ozone. The addition of ozone ice containing 300 mg/L ozone increased the gold extraction by 4.1% in the ore column leaching experiment, compared to a column with no ozone ice. However, continuously increasing the ozone concentration up to 600 mg/L had no further significant effect, because the dissolved oxygen in the leaching solution reached saturation. The results facilitate a better understanding of the decomposition law of ozone in the melting process of ozone ice and help to improve the oxygen deficit state in gold leaching heaps.

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Arham, L. O., F. R. Mufakhir, I. A. Putri, Wahab, H. Z. Hakim, A. S. Handoko, and Sudibyo. "Characterization of gold ore from Babakan Loa Sub-District and leaching study in cyanide solution." IOP Conference Series: Earth and Environmental Science 882, no. 1 (November 1, 2021): 012027. http://dx.doi.org/10.1088/1755-1315/882/1/012027.

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Abstract Research on the characterization of gold ore from Babakan Loa sub-district and studies of leaching in cyanide solution has been carried out. This research was conducted to determine the characteristics of gold ore from Babakan Loa and the leaching behavior in cyanide solution. The preparations carried out were crushing and grinding to obtain several size fractions. The ore characterization was carried out through XRD, XRF, SEM-EDX, and wet chemical analysis. XRD analysis results show that the main mineral phases are quartz, hematite, goethite, kaolinite, montmorillonite, and berlinite. The main constituents of the ore were Si (60.96%), Fe (10.71%), K (5.47%), and Al (19.53%). The Au content was 7.8 ppm, and the results of SEM-EDX analysis show that the gold grain size is smaller than 10µm. The leaching process showed that the highest percent gold extraction data of 92.7% was obtained in experiments with 1000 ppm sodium cyanide concentration, 10% solids percent, and 104-149µm grain size. Increasing the percentage of solids and the reduction in grain size led to a decrease in the percentage of gold extraction. The clay content was suspected to be the cause of the ineffectiveness of the leaching process in this study.

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Heras Romero, Manlio, Nilton Quispe Ciudad, and Juan Vega Gonzales. "Sandioss, an alternative reactive to NaCN for the Au leaching process by agitation for an oxide type mineral." Journal of Sciences and Engineering 2, no. 1 (August 18, 2018): 1. http://dx.doi.org/10.32829/sej.v2i1.46.

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The influence of the Sandioss reagent was studied as an alternative for the gold’s leaching by agitation of a mineral-type oxide. The evaluated variables were: the hydrogen potential (pH) with levels 7, 9 and 11, the concentration of Sandioss leach at 250 ppm, 500 ppm and 750 ppm, and the leaching time at 12, 24 and 48 hours. For each concentration of the leaching agent, a test was conducted in parallel with sodium cyanide at a pH = 11 to prevent the volatilization of cyanide. The solutions taken were analyzed by atomic absorption to determine the gold content in solution and tails were analyzed by fire assay. From the result of the leaching tests it can be concluded that for a better gold extraction with the Sandioss leaching, it is obtained at a concentration of 750 ppm of Sandioss, pH of 11 and time of 48 hours, obtained 79.15% extraction. Finally, the variance analysis at a level of 95% confidence shows that the variables studied significantly influence the extraction of gold and is presented as an alternative to the use of NaCN.

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Picazo-Rodríguez, Nallely G., Ma de Jesus Soria-Aguilar, Josue Chaidez, Manuel Flores, Isaias Almaguer-Guzmán, and Francisco Raul Carrillo-Pedroza. "Analysis of the Behavior of As and Pb during the Pretreatments Applied to a Jarosite Residue for the Recovery of Gold and Silver." Metals 13, no. 1 (January 10, 2023): 138. http://dx.doi.org/10.3390/met13010138.

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The recovery of valuable metals from jarosites is a topic of great relevance regarding the implementation of the circular economy; however, these materials also contain metals such as arsenic and lead, which are harmful to health and the environment. Considering these factors, it is important to monitor these metals at each stage of treatment used to recover the valuable metals. In the present work, the behavior of As and Pb was assessed during the pretreatment conducted on a jarositic residue using direct zinc leaching (DLR), as well as leaching in cyanide and cyanide media with glycine. It was found that when no DLR pretreatment was performed, As and Pb naturally dissolved in the cyanide-leaching medium at concentrations of 34.08 mg/L and 99.12 mg/L, respectively. When an alkaline treatment was conducted on the residue (DLR-AH), it was found that there was no presence of As and Pb in the cyanidation solution, while in the case of the cyanide solution with glycine, we observed 83.35 mg/L of As and 213.63 mg/L of Pb. During the oxidizing alkaline hydrothermal treatment (DLR-AHO), 27.5 mg/L of As and 106.78 mg/L of Pb were detected in the cyanide solution. In the cyanide solution with glycine, there was less dissolution of As and Pb (11.68 and 66.75 mg/L), respectively. Finally, when desulfurization of the DLR was conducted prior to the DLR-AHO treatment, the dissolution of As and Pb increased due to the elemental sulfur covering the arsenopyrite and galena particles, so that, when removed, these were more susceptible to pretreatment and cyanidation.

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Liu, Ziyuan, Jue Kou, Yi Xing, and Chunbao Sun. "Recovery of Gold from Ore with Potassium Ferrocyanide Solution under UV Light." Minerals 11, no. 4 (April 5, 2021): 387. http://dx.doi.org/10.3390/min11040387.

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In this study, potassium ferrocyanide, a nontoxic cyanide precursor in dark and diffuse reflection environment, was applied as reagent for the leaching of gold. The free cyanide ions could gradually release from potassium ferrocyanide solution under the ultraviolet light. Orthogonal leaching experiments were performed in gold ore to analyze the effect of solution pH, potassium ferrocyanide dosage, and temperature in a potassium ferrocyanide solution system under UV light. Response surface methodology (RSM) was applied to explore the role of potassium ferrocyanide in gold leaching; optimized results showed that the gold recovery reached 67.74% in a high-alkaline environment at a 12.6 pH, 3.8 kg/t potassium ferrocyanide dosage, 62 °C, and irradiance of 10 mW·cm−2. The gold leaching kinetics were monitored by quartz crystal microbalance with dissipation (QCM-D) of potassium ferrocyanide solution. The results indicate that the gold extraction process could be divided into two stages: adsorption and leaching, and a rigid adsorption layer formed on the reaction surface. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis of the gold sensor surface after leaching reaction showed that –C≡N appears on the gold sensor surface, and the gold is oxidized to form AuCN complexes.

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Jiang, Mei Guang, Quan Jun Liu, Hong Xiao, and Jun Long Yang. "Cyanide Leaching Experiment Research on Gold - Bearing Tailings." Advanced Materials Research 616-618 (December 2012): 628–32. http://dx.doi.org/10.4028/www.scientific.net/amr.616-618.628.

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The gold grade of the gold mine is high，because of the him particle size is fine，after flotation and gravity separation,the grade of gold is 3.5g/t,In order to increase economic efficiency and improve the resource utilization,this paper studies cyanide leaching of gold ore on the tailings,With studying experiment,the grade of gold is approximately 0.17g/t.the leaching rate of gold is nearly 95%.

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Luo, Wen Jie, Hong Ying Yang, and Zhe Nan Jin. "Study on the Gold Recovery of Double Refractory Gold Ore Concentrate by Biological Oxidation Pretreatment." Advanced Materials Research 1130 (November 2015): 379–82. http://dx.doi.org/10.4028/www.scientific.net/amr.1130.379.

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In this paper, Bacterial oxidation-cyanide leaching experiments were carried out and the carbonaceous substances composition of carbonaceous gold concentrate was been studied. The elemental composition was 9.73 % iron, 9.66 % sulfur, 4.84 % arsenic and 13.23 % carbon which element carbon and organic carbon was 12.11wt.% and 0.06 wt.% respectively. The main carbonaceous substances were elemental carbon which the morphology was dense and similar to graphite. The removal rates of iron, arsenic and sulfur were achieved to 93.78%, 97.02% and 95.54% respectively by bioleaching, and the gold recovery of oxidation residue reached 92.34% by carbon inhibited cyanide leaching process. The sulfide minerals packing problem could be effectively solved by bacterial oxidation process and greatly increased the gold recovery. So the bacteria oxidation and carbon inhibited leaching process is applicable to the carbonaceous gold ore.

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Seriche, Gabriel, Michelle Quilaqueo, Lorena Barros, Minghai Gim-Krumm, Ignacio Cortés, Elizabeth Troncoso, René Ruby-Figueroa, and Humberto Estay. "Integrated Membrane Process Coupled with Metal Sulfide Precipitation to Recover Zinc and Cyanide." Minerals 12, no. 2 (February 10, 2022): 229. http://dx.doi.org/10.3390/min12020229.

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In gold cyanidation plants, which include a zinc cementation process, there is a progressive increase in zinc content in the solution and a higher cyanide concentration in leaching tailings. Consequently, there are opportunities to: (i) recover zinc and cyanide from these solutions, (ii) generate a saleable ZnS by-product, and (iii) reduce cyanide consumption and cyanide concentration in leaching tailings. Previous studies have proposed the use of the SART (Sulfidization, Acidification, Recycling, and Thickening) process for this purpose; however, this process has disadvantages that must be addressed. This study presents the results of the experimental assessment of an alternative process, the SuCy process, which uses an integrated membrane process. The SuCy process is composed of a metal sulfide precipitation coupled with a membrane filtration stage, a membrane contactor step to recover and concentrate cyanide, and a final neutralization and ultrafiltration stage. The flux obtained for zinc sulfide separation was around 0.01 L/m2s, with cyanide recovery of 95% at 60 min, whereas flux for ultrafiltration was 0.22 L/m2s. A comparison with an experimental study of the SART process at laboratory scale showed that the SuCy process could obtain a higher zinc recovery and can reduce the solid–liquid separation equipment by around five times. Therefore, the SuCy process could be a promising alternative for zinc and cyanide recovery in gold cyanidation.

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Luo, Xian Ping, Min Hu, Chang Li Liang, and Qing Hai Ge. "Research on the Gold Ore Leaching in Iodine-Iodide System." Advanced Materials Research 634-638 (January 2013): 3227–33. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.3227.

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Iodine-iodide leaching gold ore is a promising method alternative to cyanide leaching. In this paper, Eh—pH diagram of Au-I--I2-H2O system was established through calculating the equilibrium potentials of the main chemical reactions based on the thermodynamic data of the actual iodide leaching of gold system. Gold ore leaching experiments in iodine-iodide system under different influence factors were carried out to verify the effectiveness of the Eh-pH diagram. The results indicated the diagram of Eh-pH can effectively guide the actual gold ore leaching in iodine-iodide system.

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Elomaa, Heini, Pia Sinisalo, Lotta Rintala, Jari Aromaa, and Mari Lundström. "Process simulation and gate-to-gate life cycle assessment of hydrometallurgical refractory gold concentrate processing." International Journal of Life Cycle Assessment 25, no. 3 (December 26, 2019): 456–77. http://dx.doi.org/10.1007/s11367-019-01723-6.

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Abstract Purpose Currently, almost all cyanide-free gold leaching processes are still in the development stage. Proactively investigating their environmental impacts prior to commercialization is of utmost importance. In this study, a detailed refractory gold concentrate process simulation with mass and energy balance was built for state-of-the-art technology with (i) pressure oxidation followed by cyanidation and, compared to alternative cyanide-free technology, with (ii) pressure oxidation followed by halogen leaching. Subsequently, the simulated mass balance was used as life cycle inventory data in order to evaluate the environmental impacts of the predominant cyanidation process and a cyanide-free alternative. Methods The environmental indicators for each scenario are based on the mass balance produced with HSC Sim steady-state simulation. The simulated mass balances were evaluated to identify the challenges in used technologies. The HSC Sim software is compatible with the GaBi LCA software, where LCI data from HSC-Sim is directly exported to. The simulation produces a consistent life cycle inventory (LCI). In GaBi LCA software, the environmental indicators of global warming potential (GWP), acidification potential (AP), terrestrial eutrophication potential (EP), and water depletion (Water) are estimated. Results and discussion The life cycle assessment revealed that the GWP for cyanidation was 10.1 t CO2-e/kg Au, whereas the halogen process indicated a slightly higher GWP of 12.6 t CO2-e/kg Au. The difference is partially explained by the fact that the footprint is calculated against produced units of Au; total recovery by the halogen leaching route for gold was only 87.3%, whereas the cyanidation route could extract as much as 98.5% of gold. The addition of a second gold recovery unit to extract gold also from the washing water in the halogen process increased gold recovery up to 98.5%, decreasing the GWP of the halogen process to 11.5 t CO2-e/kg Au. However, both evaluated halogen processing scenarios indicated a slightly higher global warming potential when compared to the dominating cyanidation technology. Conclusions The estimated environmental impacts predict that the development-stage cyanide-free process still has some challenges compared to cyanidation; as in the investigated scenarios, the environmental impacts were generally higher for halogen leaching. Further process improvements, for example in the form of decreased moisture in the feed for halide leaching, and the adaptation of in situ gold recovery practices in chloride leaching may give the cyanide-free processing options a competitive edge.

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Hou, Dongzhuang, Lang Liu, Qixing Yang, Bo Zhang, Huafu Qiu, Shisan Ruan, Yue Chen, and Hefu Li. "Decomposition of Cyanide from Gold Leaching Tailingsby Using Sodium Metabisulphite and Hydrogen Peroxide." Advances in Materials Science and Engineering 2020 (October 7, 2020): 1–7. http://dx.doi.org/10.1155/2020/5640963.

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Cyanidation is widely used by most gold mine worldwide and will remain prevail in years (or decades) to come, while cyanide is hazardous, toxic pollutants whose presence in wastewater and tailings can seriously affect human and its environment; hence, it is necessary to control these contaminants. The purpose of this study was to examine the effects through the investigation of changes in pH, concentration, and contact time, and the optimal conditions were obtained. It has been proven that the decomposition of cyanide in solution and tailings increased as the alkalinity in the presence of 0.5 g/L Na2S2O5. An increase in H2O2 (30%) concentration (from 1 to 4 mL/L) increased the decomposition in solution, while the effect on removing cyanide was better when pH was 9 than 8 and 10 in tailings. The cyanide in tailings decreased in the first 4 h and increased after 4 h. The effective and economic conditions for maximum decomposition of cyanide from leach tailings are first treated in 0.5 g/L Na2S2O5 at pH 10 for 3 hours and then 2 mL/L H2O2 (30%) is added to the tailings at pH 9 for 4 hours through comparative study. The findings provide the basis to optimize the decomposition of cyanide from gold leaching tailings in mining or backfilling by using the synergetic effect of Na2S2O5 and H2O2.

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Xiao, Li, Peng Qian, Yang Yu, Peiwei Han, Yongliang Wang, Guoyan Fu, Zhi Sun, and Shufeng Ye. "An environmentally friendly system for high efficient silver recovery from anode slime." Metallurgical Research & Technology 116, no. 2 (2019): 208. http://dx.doi.org/10.1051/metal/2018070.

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Anode slime is an extremely valuable secondary resource for the recovery of silver and has attracted wide attentions. Effective metal recovery is usually constrained by either environmental hazards or high consumption of lixiviant for cyanide and non-cyanide leaching reagents. To tackle these issues in the process of silver recovery from anode slime, this research demonstrated a new leaching system with using an efficient oxidant which encapsulates cyanide into ferric complexes to ensure it not releasing into the environment while effective silver recovery was achieved. Comparing with the traditional tetra-amine copper oxidant, it was found that the dissolution rate of silver was significantly improved and leachate consumption was largely decreased. The effects of stirring speed, sodium thiosulfate concentration, oxidant concentration, solution pH and time on silver dissolution were investigated. When the novel system of iron-encapsulated cyanide was applied to extract silver from anode slime, the final conversion rates of silver was 97% after 60 minutes. This system has great potential in silver recovery from anode slime.

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Wang, Kai, Yi Qi Cui, Xiong Tong, Peng Dong, and Qi Meng. "Study on the Optimal Condition of a Copper-Bearing Gold Ore Cyanide Leaching Using Orthogonal Design." Advanced Materials Research 734-737 (August 2013): 1006–9. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.1006.

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The copper-bearing ore assays 1.7g/t Au, 50.43% Fe and 0.41% Cu. Recovered gold by cyanide leaching, in this study, the orthogonal test design was used to examine effects of NaCN dosage, leaching time, agitation intensity, particle size on gold leaching rate and determine the optimal operation combination for the purpose of increasing gold recovery. Gold extractions of 92.34% were achieved using a particle size of 90%-200 mesh, NaCN dosage of 1.8kg/t, leaching time of 36h and agitation rate of 400r/min.

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Yan, Li, and Ji Shou Zhao. "Study Pressure-Cyanide Dissolution Different of Metal Palladium and Platinum Powder." Advanced Materials Research 734-737 (August 2013): 2514–18. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.2514.

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s: A research study has been undertaken to develop the fundamentals of a method for the direct dissolution of platinum group metals (PGMs). At room temperature and pressures, the reaction between sodium cyanide and platinum group metals (PGMs) does not occur because of poor kinetics. However, at elevated temperatures between 120-180 °C, PGMs can be leached by sodium cyanide like the reaction of gold. In this work, the dissolution of Palladium and Platinum powder were measured in pressure clear cyanide solution. The cyanide leaching reaction mechanism is also discussed.The data at different cyanide concentrations, different temperature and different oxygen pressure are obtained. The dissolution rate off metal Palladium and Platinum powder were found to be a function of the cyanide and oxygen level.

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Rubisov, D. H., V. G. Papangelakis, and P. D. Kondos. "Fundamental Kinetic Models for Gold Ore Cyanide Leaching." Canadian Metallurgical Quarterly 35, no. 4 (October 1996): 353–61. http://dx.doi.org/10.1179/cmq.1996.35.4.353.

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Xie, Feng, and David B. Dreisinger. "Leaching of silver sulfide with ferricyanide–cyanide solution." Hydrometallurgy 88, no. 1-4 (August 2007): 98–108. http://dx.doi.org/10.1016/j.hydromet.2007.03.008.

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Zhao, Ji Shou, X. M. Zhang, and J. H. Dai. "Study on Dissolution Different of Metal Palladium Powder and Place." Advanced Materials Research 1033-1034 (October 2014): 1283–87. http://dx.doi.org/10.4028/www.scientific.net/amr.1033-1034.1283.

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The chemistry of the dissolution of Palladium in pressure-cyanide has not received considerable attention. At room temperature and pressures, the reaction between sodium cyanide and Palladium does not occur because of poor kinetics. However, at elevated temperatures between 100-160 °C, Palladium can be leached by sodium cyanide like the reaction of gold. A research study has been undertaken to develop the fundamentals of a method for the direct dissolution of Palladium In this work, the dissolution of Palladium powder and place were measured in pressure clear cyanide solution. The cyanide leaching reaction mechanism is also discussed. The data of Palladium powder and place at different cyanide concentrations, different temperature and different oxygen pressure are obtained. The dissolution rate of metal Palladium powder and place were found to be relate to the cyanide and oxygen level.

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Journal articles on the topic 'Cyanide leaching'

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