· Ultrasound increased the leaching rate of gold by 25% in Co-NH 3-S 2 O 3 2− system. Ultrasound reduced the leaching time by 8 times. • The internal diffusion step controlled the ultrasound leaching process. • The reaction orders of
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· Abstract. The thermodynamic equilibria and kinetic aspect of gold dissolution in iodine–iodide leaching were studied with emphasis on the effects of pH value and temperature on the system. The results of thermodynamic analysis of iodine in aqueous solution were given and numerous forms of iodine exist mainly in the acid region of pH
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· The purpose of glycine leaching can be achieved due to the strong complex formation (stability constant 18) of gold with glycine. The equation is as follows. (7) Au + + 2NH 2 CH 2 COOH ⇌ Au NH 2 CH 2 COO 2 − + 2H + logK 4 = 18. In alkaline solution, the reaction of gold leaching by glycine is as follows.
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· ISBN 2-980-3247-0-1. 1999. Out of print. Textbook of Hydrometallurgy, 2 nd edition by Fathi Habashi. The book covers the general principles of solution chemistry, engineering. aspects, and
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· Pretreatment is required to improve the recovery of gold from refractory gold ore by exposing the gold surface for leaching. Several oxidation pretreatment methods have been proposed. Roasting is the primary method for pretreating refractory gold ores ( Jin et al., 2019 ; Liu et al., 2019 ; Qin, 2021 ).
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Possibilities and challenges for ionic liquids in hydrometallurgy Esteban Quijada-Maldonado, Julio Romero, in Separation and Purification Technology, 2020Abstract Hydrometallurgy is an efficient way of recovering metal ions from mineral ores where the most important steps are the leaching of the minerals, the recovery and purification of
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· The antimony in refractory gold ores was selectively removed by ultrasound with alkaline sodium sulfide. The removal rate of antimony reaches 94.50% under the optimum conditions: the ultrasonic power is 1500 W, the Na 2 S concentration is 2 mol/L, temperature is 55 °C and time is 60 min and the NaOH concentration is 1 mol/L.
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· Thiourea leaching of gold from a quartz vein type ore without the addition of additive was investigated to show the effect of leaching conditions including Fe 3+ concentration (0.02–0.05 M), thiourea concentration (0.05–0.13 M), pH (1.0–2.5), leaching time (4–7 h) and temperature (25–50 C) on gold extraction and thiourea consumption.
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· Gold leaching was subsequently conducted using a mixed solution of glycine and cyanide (30 g/L glycine and 300 mg kg −1 NaCN). The leaching efficiency accounted during the two-stages were 92.1 %, 85.3
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· Diagnostic leaching results showed 39.7 wt% of total gold was leachable using direct cyanide leaching, and around 33 wt% of undissolved gold was located in pyrite and arsenopyrite. Full article (This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy )
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:Hydrometallurgical RecoveryPublish Year:2020 · Hydrometallurgical gold recovery processes play a pivotal role in the gold mining industry, contributing to more than 90% of global gold production. Among the
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· Kogan (2006) patented a technique for gold recovery from waste electronic equipment. The scrap was added to hydrochloric solution containing 180 g/L HCl and 250 g/L MgCl 2 for 3 h at a temperature of 80–95 °C. During this period 98% of aluminum, 94% of tin, 96% of lead and 94% of zinc were extracted in solution.
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Kinetics, as a fundamental requirement of nearly all industrial activities and engineering researches, plays a great role in leaching processes. Although there are many pieces of research on its application, there is not a clear pathway for investigating the kinetics of leaching and researchers usually follow different strategies in their studies. The
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· Among the leaching reagents examined, hydrochloric acid (HCl) showed great potential for the recovery of metals. The HCl-mediated leaching of waste PCBs was investigated over a range of
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· Orgul, S. Reaction chemistry of gold leaching in thiourea solution for a Turkish gold ore. Hydrometallurgy 67, 71–77 (2002). Article CAS Google Scholar Zhu, P. et al. A new technology for
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· Ferrous and cupric ions have no effect on the leaching kinetics, whereas the rate of leaching of gold is retarded significantly in the presence of silver and cuprous ions. Based on their electrochemical investigations, Li et al. [ 32 ] have proposed that the anodic reaction in dissolution of gold in acid thiocyanate solution happens to be the rate
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· hydrometallurgy ELSEVIER Hydrometallurgy l997) I-20 Model for heap leaching of gold ores by cyanidation A.E. Schez-Chac * , G.T. Lapidus Departamento de Ingenieria de Procesos a Hidrlica, Uniuersidad Automa Metropolitana -- 1. tapalapa. Apdo.
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· After leaching for 48 h, 83% gold extraction was achieved with 0.2 M S 2 O 3 2− with 0.4 kg S 2 O 3 2− consumed per ton of ore. The effectiveness of low thiosulfate concentrations was confirmed by Cao et al. (1992) , who studied the effects of the concentrations of thiosulfate, copper and ammonia on the extraction of gold and silver
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· Hydrometallurgy is a technique within the field of extractive metallurgy to obtain metals from their ores. Hydrometallurgy involve the use of aqueous solutions for the recovery of metals from ores, concentrates, and recycled of residual materials. The Unit processes of hydrometallurgy includes the leaching of particularly low grade ores for
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· Hydrometallurgy Volumes 115–116, March 2012, Pages 1-20 Review Gold leaching by copper(II) in ammoniacal thiosulphate solutions in the presence of additives. Part I: A review of the effect of hard–soft and Lewis acid-base properties and interactions of ions G.
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· To date, various recovery techniques have been developed to recover gold from secondary sources, e.g., pyrometallurgy, hydrometallurgy and bio-hydrometallurgy techniques. Among these methods, hydrometallurgy, which uses cyanide, halide and thiourea, among other substances, as leaching agents, is now the
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· current hotspot in gold hydrometallurgy (Aylmore, 2016). Nevertheless, cyanid at ion will still dominate for a long time, and it is kinetics of gold leaching (Byerley et al., 1973 ; Fleming
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· One of the ways of increasing effectiveness of processing the gold-containing materials may be introduction of direct hydrometallurgy processes. Hydrometallurgical methods of processing differ in low power capacity, simplicity of implement process, decreasing pollution of the environment.
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· Thiosulphate leaching of precious metals has been developed as an alternative and non-toxic technique to the conventional cyanidation. This process has advantages over cyanide in a decreased interference from foreign cations and a lower environmental impact. Ammoniacal thiosulphate solution allows the solubilization of gold
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· The slow gold leaching in both GCS and cyanidation processes can be referred to the coarse gravity gold present, Hydrometallurgy, 152 (2015), pp. 193-203 Google Scholar Oraby and Eksteen, 2015b E.A. Oraby, J.J. Eksteen Gold leaching in cyanide-starved
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· However, if the concentrations of OCl − and I − are equal, solid iodine is formed. In these systems iodide (I − )_is used to form I 3− (responsible for the gold oxidation) and more free iodide needed for the gold complexation is destroyed in the I − -OCl − system than the I − -I 2 system. The formation of solid AuI also explains
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· Conclusion. A microfluidic device has been developed to mimic the conditions of in-situ leaching of gold using an alkaline glycine system at various temperatures and lixiviant concentrations. The device builds on an existing device developed by Kotova et al. (2017) where amonium thiosulfate has been used to extract gold at
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Leaching is a process widely used in extractive metallurgy where ore is treated with chemicals to convert the valuable metals within the ore, into soluble salts while the impurity remains insoluble. These can then be washed out and processed to give the pure metal; the materials left over are commonly known as tailings .
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:Hydrometallurgical ProcessingGold Leaching Process · Over the last century, cyanide leaching has been widely used to recover gold from gold minerals and secondary sources its high efficiency and relatively low
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· After the three stages of TCCA leaching, a gold leaching efficiency was increased to 94.39%. Furthermore, TCCA leaching process could be divided into three steps, the findings of kinetic models revealed that in the early leaching step (0–2 h), TCCA leaching was controlled by solid products layer diffusion model, and yet shifted to be
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