There is currently much interest in how extraction of gold and silver from ores with acidic thiourea solution compares with extraction using alkaline cyanide solution. Agitation leaching tests were performed by the U.S. Bureau of Mines on 14 precious metal ores using sodium cyanide (nacn) and thiourea [(nh2)2cs] as extractants. The objective was to compare the results of the two extractants.
thiourea leaching of gold and silver
T1 - THIOUREA LEACHING OF GOLD AND SILVER - TECHNOLOGY UPDATE AND ADDITIONAL APPLICATIONS. AU - Hiskey, J. B. PY - 1984. Y1 - 1984. N2 - The hydrometallurgical application of thiourea in processing precious metal ores and concentrates has reached the development stage. This paper reviews recent technical literature covering the process ...
2017-9-13 · Jana Ficeriová, Peter Baláž and Eberhard Gock: Leaching of gold, silver and accompanying metals from circuit boards (PCBs) waste 130 0 60 120 180 240 300 360 420 480 0 20 40 60 80 ε 100 Me [ % ] Ni Al Fe Cu Zn t L [ min ] Fig. 1. Recovery of Zn, Cu, Fe, Al and Ni, εMe vs. leaching time, tL for circuit boards (PCBs) waste pretreated by Omniplex-hammer mill, 40/20 Ha (Alpine, Germany).
2018-3-12 · sively for leaching gold and silver since its introduction 100 yr ago. Recently, there has been mch interest in the min- ing and metallurgical processing indus- tries in thiourea as an extractant for gold and silver (1-3, -- -- 6-14).3 Thiourea extracts gold in an acidic medium (pH 11, and at …
1997-7-2 · The thiourea leaching of gold and silver from the gold-bearing silicate ore of the Hishikari mine (Kagoshima, Japan) was studied. The apparent activation energy of the extraction of gold and silver was smaller than that of the reaction rate of thiourea consumption by ferric iron. We carried out the leaching after the leaching solution was preserved for several hours. The gold recovery at 288 K ...
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 ...
2012-6-1 · 2.3. Leaching experiments. The powdered waste PCBs samples were pretreated, filtered, and dried according to the following procedure. The leaching of gold and silver were carried out in the beaker containing the pretreatment power and 40 mL of leaching solution (the mixture solution of thiourea and ferric ion) using 0.5 mol/L sulfuric acid for pH adjustment.
2017-9-13 · Fig. 4. Specific rate constant of gold leaching, kAu/SA vs. milling time, tM for the mechanochemically activated sample. Thiourea leaching of gold from mechanically and mechanochemically activated waste The dependence of gold recovery on leaching time is represented for different mechanically activated samples in Fig. 5.
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 gold ...
Therefore, in cases where gold and silver are in a mixture, reduction can be performed in two stages to precipitate gold and silver metal separately in good yield and high purity. It can be seen in Table 2 that the reduction of gold in thiourea in the presence of silver, copper and iron (II) in only one stage resulted in a product of medium purity.
Au and Ag leaching efficiencies of about 90% and were obtained by one-step thiourea leaching. However, metals such as Fe and Al were also dissolved together. In the two-step process, Fe and Al were dissolved using H 2 SO 4 as a first step, then Au and Ag were recovered using thiourea leaching.
2018-4-15 · Thiourea Silver Leaching. Unlike base metals which are readily soluble in mineral acids, noble metals like gold and silver require the presence of oxidizing and …
2016-5-25 · complex compounds easily that neutralized the gold and silver also reduces the solving rate of them; (Jinshan et al., ; Kai et al., ). Likewise in comparison to thiourea, thiocyanide shows less toxicity, more stability but lower solubility rate (Barbosa, -). Another method is thiosulfate leaching that has been analyzed by
2004-8-1 · The kinetics of thiourea leaching of Ovacik gold ore, Normandy Mining Co., were investigated, and the major leaching parameters were determined. Ovacik is the first project in what is potentially a large new mining industry in Turkey. The main parameters investigated in the leaching tests were particle size, solid/water ratio, pH, thiourea, Fe2(SO4)3 and Na2S2O5 concentrations, agitation rate ...
The thiourea (TU) leaching of gold from refractory ores can be considered an alternative to cyanidation. However, the high reagent consumption causes an increase in cost, which seriously limits its use. In order to effectively reduce the TU consumption, it is necessary to analyze the influencing parameters of gold recovery and TU consumption and apply them to the prediction of the TU leaching ...
The main unit operations in a thiourea leaching method are (1) thiourea leaching (by agitation, dump, or heap leaching), (2) recovery of dissolved gold and silver on activated carbon, (3) carbon elution, and (4) recovery of gold and silver from the elution solutions.
1994-6-1 · The dissolution of gold and silver from concentrate was studied with acidic thiourea solution. The results showed that the gold and silver extraction was severely affected by concentration of thiourea and oxidant, pulp density, etc. Especially, oxidant such …
2007-10-24 · In this paper, the chemistry involved with the leaching of gold by acidic thiourea solutions has been reviewed. The thermodynamics and kinetics of the complexation of thiourea with gold, silver and other associated metals, as well as the degradation of the thiourea itself were discussed.
Silver extraction is generally low in thiourea leaching of gold and silver ores [Açma et al., 1993; Yüce et al, 1994, Çelik, 1996 Tanrıverdi et al., 2005]. Thiourea decomposes to cyanide and ...
2018-1-5 · Leaching Chemistry of Gold Silver and Manganese. Thiourea is a reducing and complexing agent and can be used for the processing of gold and silver. The …
· T1 - THIOUREA LEACHING OF GOLD AND SILVER - TECHNOLOGY UPDATE AND ADDITIONAL APPLICATIONS. AU - Hiskey, J. B. PY - 1984/12/1. Y1 - 1984/12/1. N2 - The review of recent literature relating to the use of thiourea as a lixiviant for gold and silver indicates only a modest level of activity and interest.
2020-6-1 · Cyanide leaching, as a typical traditional method, hardly achieves the cleaner production of gold due to high consumption of auxiliary materials, inefficient production and heavy environmental pollution. In this work, stepwise thiourea leaching was used to extract gold and silver from refractory gold concentrate calcine.
Leaching with a relatively concentrated thiourea solution (1MCS (NH 2) 2) resulted in 83% gold and 75% silver extraction in four hours. With the treated flue dust residue, gold extraction was about 60%. Gold and silver extraction with cyanide was sensitive to both cyanide concentration and oxidizing conditions.
2020-9-15 · minerals Article Analysis and Prediction of the Thiourea Gold Leaching Process Using Grey Relational Analysis and Artiﬁcial Neural Networks Rui Xu 1,y, Xiaolong Nan 2,y, Feiyu Meng 1,*, Qian Li 1,*, Xuling Chen 1, Yongbin Yang 1, Bin Xu 1 and Tao Jiang 1 1 School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; ...
Leaching Gold-Silver Ores With Sodium Cyanide and Thiourea Under Comparable Conditions R.I. 9181 (1988) 13 p. Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona.
Gold Recovery from a Gold Tailing by Floatation and Thiourea Leaching Wen-Juan LI 1, a, Liu-Lu CAI 1, b, Yong-Sheng SONG 1, c, *, Gui -Ying ZHOU 1, d and Yong CHEN1, e 1National Engineering Lab. of Biohydrometallurgy, General research Institute for Nonferrous Metals, Beijing 100088, China; [email protected] , [email protected] , [email protected] ,
The objective of this work was to recover gold and silver from the printed circuit board (PCB) of discarded mobile phones by thiourea leaching. Effects of thiourea concentration, leaching temperature, leaching time, and ferric ion (Fe3+) concentration on the recovery of gold and silver were investigated. The PCB was pretreated physically to reduce the thiourea consumption and enhance the ...
2020-1-19 · Thiourea-thiocyanate leaching system for gold ... for leaching of gold and silver ores was published by Barbosa-Filho and Monhemius (1989). Thiocyanate is a technically viable and interesting lixiviant for gold (Broadhurst and Du Preez, 1993). Leaching is performed between pH 1 and 2, which allows the use of
2021-8-11 · The use of thiourea as an alternative lixiviant to gold cyanidation for processing gold-bearing ores or concentrates was first developed by Soviet metallurgists in the 1940s. However, the interest for thiourea leaching of gold mainly came during the 1980s and 1990s to establish a parallel process.
Leaching Gold-Silver Ores With Sodium Cyanide and Thiourea ... with solubilized as a cationic . extracts in an alkaline medium, and although no oxidant other than air from agitation is generally applied, addition of an oxidant may be beneficial 4. The dissolution of by iy expressed by with solubilized as an anionic …
International audienceThis study deals with solvent extraction of gold and silver from thiourea leaching Au-Ag ore liquors as an alternative to the traditional process involving cyanide. The investigation of extraction mechanism of gold and silver from acidic thiourea solution had not been clearly established to …
Electrochemical measurements were conducted to study the electrochemical behavior of gold (Au) and its commonly associated minerals in alkaline thiourea solutions. The results indicated that without addition of any stabilizer, selective dissolution of Au from stibnite and pyrite was only possible at relatively low thiourea concentrations. As Na >2SiO3 was added, pyrite started ...
A study on the kinetics of acidic thiourea leaching for gold and silver from a sulfide concentrate containing copper and other valuable metals was carried out. Based on the shrinking core model ...
The influence of particle size, thiourea and Fe(3+) concentrations and temperature on the leaching of gold and silver from waste mobile phones was investigated. Gold extraction was found to be enhanced in a PCBs particle size of 100 mesh with the solutions containing 24 g/L thiourea and Fe(3+) concentration of 0.6% under the room temperature.
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