alkaline thiourea leaching gold
alkaline thiourea leaching gold
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alkaline thiourea leaching gold

Research status and prospect of gold leaching in alkaline ...

The mechanism of gold dissolution is the theoretical foundations for gold leaching in thiourea solution. The suitable oxidant should be the substances with moderate redox potential. An efficient stabilizing reagent selected for alkaline thiourea must be satisfied with two conditions: i.e., easily forming hydrogen–sulfur bond and a stable ...

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CN103276206B - Method for leaching gold in alkaline ...

The invention discloses a method for leaching gold in an alkaline thiourea system efficiently and stably. According to the method, under an alkaline condition, thiourea is taken as a gold leaching reagent, sodium hexametaphosphate or trisodium phosphate is taken as a stabilizing agent, calcium peroxide is taken as an oxidizing agent, EDTA (ethylene diamine tetraacetic acid) is taken as a ...

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Gold Leaching in an Alkaline Thiourea Solution - NASA/ADS

adshelp[at]cfa.harvard The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A

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Thiourea Gold Leaching - Metallurgist Mineral Processing ...

Aug 12, 2017  Use of acidic thiourea instead of cyanide would allow for immediate leaching of gold without neutralization and result in considerable savings through the elimination of the neutralization step. For the thiourea process to compete industrially with cyanidation, it is essential to develop efficient process(es) to recover the gold from solution.

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The leaching of gold, silver and their alloys in alkaline ...

The gold leaching rate in solutions containing 0.5 M glycine and 1% peroxide at pH 11 after 48 h of leaching was found to be 0.322 μmol/m2 s, which is comparable to gold leaching rate after six days in thiosulphate–EDTA or thiosulphate–oxalate systems in the presence of thiourea (0.22–0.25 μmol/m2 s).

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Cyanide and Other Lixiviant Leaching Systems for Gold with ...

Jun 10, 2010  Acid leaching systems (pH ⩾ 3)may contain thiourea, thiocyanate, chlorine, aqua regia, or ferric chloride. Chloride is the ligand in the last three systems and the oxidants include chlorine, ferric chloride, hydrogen peroxide, and nitric acid which produce Au(III) anionic complexes, e.g. [AuClJ".

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A Method for Leaching or Dissolving Gold from Ores or ...

lurgical gold extraction routes utilize a leaching step to produce a gold-bearing solution as an intermediate product while the recycling of secondary gold from electronic and precious metal scrap is based on the selective and fast dissolu-tion of the precious metal. Therefore, A Method for Leaching or Dissolving Gold from Ores or Precious

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Optimization of efficient stable reagent of alkaline ...

Jun 13, 2003  Optimization of efficient stable reagent of alkaline thiourea solution for gold leaching Optimization of efficient stable reagent of alkaline thiourea solution for gold leaching Wang, Yun-yan; Chai, Li-yuan; Min, Xiao-bo; He, De-wen; Peng, Bing 2003-06-13 00:00:00 Na2SiO3 and Na2SeO3 were chosen as stable reagents of alkaline thiourea solution substituting Na2SO3, according to the

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Optimizing and evaluating the operational factors ...

Dec 08, 2015  This research was carried out on Aghdareh gold ore. The Aghdareh mine and gold processing plant is located 32 km from Takab city in the western Azerbaijan province, Iran, at 46°58′30′′N and 36°39′29′′E. The grade of gold ore is 3 ppm. Also, cyanide leaching is used to process gold in the Aghdareh mine . The main problem in ...

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Leaching Gold-Silver Ores With Sodium Cyanide and

LEACHING GOLD-SILVER ORES WITH SODIUM CYANIDE AND THIOUREA UNDER COMPARABLE CONDITIONS By J. A. ~isele,' A. E. ~unt,~ and D. L amps shire^ ABSTRACT There is currently mch interest in how extraction of gold and silver from ores with acidic thiourea solution compares with extraction using alkaline cyanide solution.

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NIOSHTIC-2 Publications Search - 10006177 - Leaching gold ...

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 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.

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青海某难浸金矿的工艺矿物学研究 - goldsci.ac.cn

The recovery of gold by the cyanide leaching is less than 50% in laboratory scale.To find the reason for the low recovery of gold by cyanide leaching and ... Leaching kinetics of antimony from refractory gold ore in alkaline sodium sulfide under ultrasound ... Study on the Mechanism and Process of Gold Leaching by Thiourea in the Acid System of ...

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Bibliographies : « University of Stellenbosch ...

Jun 14, 2012  Recent studies have shown that the gold leaching with thiocyanate under alkaline conditions is also viable using oxygen as oxidant. Then this article compares and analyzes the use of different oxidants in acid or alkali environment reaching a 96% leaching efficiency and the techniques of gold recycle from thiocyanate gold solutions.

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NIOSHTIC-2 Publications Search - 10006177 - Leaching gold ...

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 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.

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Leaching Gold-Silver Ores With Sodium Cyanide and

LEACHING GOLD-SILVER ORES WITH SODIUM CYANIDE AND THIOUREA UNDER COMPARABLE CONDITIONS By J. A. ~isele,' A. E. ~unt,~ and D. L amps shire^ ABSTRACT There is currently mch interest in how extraction of gold and silver from ores with acidic thiourea solution compares with extraction using alkaline cyanide solution.

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Selective dissolution of gold in an alkaline thiourea ...

Jun 14, 1997  New aspects in thiourea leaching of precious met- als. J Metals, 1984, 36 (6) : 62~65 lution. But addition of Na2SO3 into alkaline 2 Hiskey J B. Thiourea leaching of gold and silver--Technology thiourea solution can increase the current of Au an- update and additional application. In:Practical Hydromet' 83 7th ode steeply.

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The leaching of gold, silver and their alloys in alkaline ...

The gold leaching rate in solutions containing 0.5 M glycine and 1% peroxide at pH 11 after 48 h of leaching was found to be 0.322 μmol/m2 s, which is comparable to gold leaching rate after six days in thiosulphate–EDTA or thiosulphate–oxalate systems in the presence of thiourea (0.22–0.25 μmol/m2 s). In alkaline glycine–hydrogen ...

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Hydrometallurgical Recovery of Metals from Large Printed ...

Sep 29, 2015  Electronic scrap has been reported to be alkaline in nature 37. ... Orgul, S. Reaction chemistry of gold leaching in thiourea solution for a Turkish gold ore. Hydrometallurgy 67,

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Recovery of gold from solution by reduction-precipitation ...

A process is disclosed for the direct recovery of gold from thiourea, thiocyanate or thiosulfate solutions or acidified thiourea leach liquor. The process comprises reduction precipitation of the gold from solution by the addition of stabilized alkali metal borohydride, preferably sodium or potassium borohydride, at ambient temperature and ...

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Recovery of gold from refractory gold ores: Effect of ...

May 28, 2020  The extraction of gold from refractory gold ores (RGOs) without side reactions is an extremely promising endeavor. However, most RGOs contain large amounts of sulfide, such as pyrite. Thus, investigation of the influence of sulfide on the gold leaching process is important to maximize the utilization of RGOs. In this work, the effects of pyrite on the stability of the thiourea system were ...

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Study on the Gold Leaching Process by Potassium ...

The traditional gold leaching method is cyanidation, which carries serious security and environmental problems. More and more attention is paid to the research on non-cyanide process. A high-arsenic-and-sulphur refractory gold concentrate in Sichuan was taken as the object of study. After the roasting-oxidation pretreatment of the sample, potassium ferricyanide was adopted to carry on the ...

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A review of gold extraction using noncyanide lixiviants ...

Sep 11, 2019  Alkaline sulfur-containing lixiviants, including thiosulfate, polysulfides, and alkaline sulfide solutions, stand out as a promising class of alternatives to cyanide because of their low toxicity, high efficiency, and strong adaptability. In this paper, we summarized the research progress and remaining challenges in gold extraction using these noncyanide reagents.

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New Eco-Friendly, Non-Cyanide Based Alternative for Gold ...

Feb 08, 2017  Cyanide has been the leach reagent of choice in gold mining because of its high gold recoveries, robustness and relatively low cost. As a result, over 85% of all gold extracted worldwide is ...

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Bioleaching gold recovery - SlideShare

Nov 30, 2015  • Thiourea leaching • This method was developed as a potential substitute for cyanidation (of gold as well as silver). Thiourea’s lower toxicity and greater rate of gold and silver dissolution compared to cyanide give it an advantage inreaching commercial application before other non-commercial lixiviants [2].

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(PDF) Gold Extraction and Recovery Processes For Internal ...

Thiourea leaching This method was developed as a potential substitute for cyanidation (of gold as well as silver). Thiourea’s lower toxicity and greater rate of gold and silver dissolution compared to cyanide give it an advantage in reaching commercial application before other non-commercial lixiviants [2].

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Gold Leaching Scientific.Net

When 0.1mmol/L thiourea was presented, the dissolution of gold approximately 1.5 times faster than that of in the absence of thiourea. Leaching of middle-refractory gold ore show that both of the consumption of thiosulfate and leaching rate was decreased compare to the traditional copper–ammonia thiosulfate system.

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THIOSULPHATE LEACHING – AN ALTERNATIVE TO

alternative to cyanidation for some gold bearing ore bodies. Whether the leaching is performed in stirred tank reactors or heaps, the size and type of equipment needed for a thiosulphate leaching flowsheet is very similar to a conventional cyanide leach. SGS is a global technical leader in the field of thiosulphate leaching, and our

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Selective dissolution of gold in an alkaline thiourea ...

Jun 14, 1997  New aspects in thiourea leaching of precious met- als. J Metals, 1984, 36 (6) : 62~65 lution. But addition of Na2SO3 into alkaline 2 Hiskey J B. Thiourea leaching of gold and silver--Technology thiourea solution can increase the current of Au an- update and additional application. In:Practical Hydromet' 83 7th ode steeply.

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Effect of Acid Leaching Pre-Treatment on Gold Extraction ...

The effect of a preliminary acid leaching for the recovery of gold by thiourea from printed circuit boards (PCBs) of spent mobile phones, was investigated. Preliminary leaching is aimed to recover copper in the leachate that would compete with gold in the successive leaching of the residue with thio

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The leaching and adsorption of gold using low ...

The leaching of gold using alkaline amino acids–hydrogen peroxide solutions at low concentrations has ... In addition, it was found that in the presence of thiourea the gold oxidation rate increases (Chandra and Jeffrey, 2004). How-ever, thiourea has been identified as a potential carcinogen and its

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Analysis and Prediction of the Thiourea Gold Leaching ...

Sep 15, 2020  optimization studies for the TU gold leaching process are considered [12]. TU is a kind of water-soluble organic compound which is relatively stable in acidic solution and rapidly decomposed in alkaline solution. Therefore, the TU leaching of gold is generally carried out in the pH range of 1–2 [13].

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Gold Leaching from Refractory Ores—Literature Survey ...

Apr 27, 2007  Gold is then recovered from the oxidized mass by alkaline cyanidation. Beside pretreatments, direct gold recovery from carbonaceous gold ores or concentrates with thiourea or CIL leach process is also feasible.

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☆ph acid or alkaline required in extraction of gold☆

LEACHING GOLDSILVER ORES WITH SODIUM CYANIDE AND THIOUREA UNDER COMPARABLE CONDITIONS By J. A. ~isele,' A. E. ~unt,~ and D. L amps shire^ ABSTRACT There is currently mch interest in how extraction of gold and silver from ores with acidic thiourea solution compares with extraction using alkaline cyanide solution.

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Mechanism of gold dissolving in alkaline thiourea solution ...

Mechanism of gold dissolving in alkaline thiourea solution Li-yuang Chai; Yun-yan Wang download BookSC. Download books for free. Find books

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TECHNICAL NOTE COMPARATIVE CYANIDE AND

assayed. The results indicate that thiourea leaching performs (96.5% extraction at 16 hours) better than (96% extraction at 24 hours) cyanidation. Leaching The gold leaching cells were made of glass and plastic, with a 10 litre capacity at room temperature. The tests were made with ore crushed carefully to -2000 microns at the pH of desired level.

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DISSOLUTION OF GOLD WITH CYANIDE REPLACING REAGENTS

Keywords: gold leaching, ammonium thiosulfate, chloride, thiourea, thiocyanate Introduction The most common hydrometallurgical methods of primary raw material utilization in the production of gold are based on the use of cyanide (Hilson, 2006). In this method a weak sodium cyanide solution (NaCN) of 100-500 ppm is used. Since the Baia Mare

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Hydrometallurgical Recovery of Gold from Mining Wastes ...

Nov 11, 2020  Moreover, thiourea leaching of Au was tested in pilot plants and industrial operations [28, 30]. The pH of the solution, leaching potential, ferric sulfate concentration, thiourea concentration and leaching time are critical parameters for the leaching efficiency . The optimum conditions for thiourea leaching can be achieved by using an ...

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Analysis and Prediction of the Thiourea Gold Leaching ...

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 ...

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Alkaline Oxidative Leaching of Gold-Bearing Arsenopyrite

ALKALINE OXIDATIVE LEACHING OF GOLD-BEARING ARSENOPYRITE ORES By P. Bhakta,1 J. W. Langhans, Jr.,1 and K. P. V. Lei2 ABS"rRACT The U.S. Bureau of Mines developed an alkaline oxidative pretreatment leaching procedure to increase the recovery of gold from arsenopyrite (FeAsS) ores. The best solution compositions for

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N o n c y a n i d e l e a c h i n g o f a n a u r i f e r ...

diagnostic experiments, it appears that gold dissolution in thiocyanate and thiourea systems is limited by passivation due to the formation of either elemental sulfur or sulfur com­ pounds on the gold surface. Key words: Gold leaching, Refractory ores, Thiocyan­ ate, Thiourea Introduction The alkaline cyanide leaching system for gold has been

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Gold-silver Heap Leaching and Management Practices That ...

The percentage of gold and silver produced by leaching operations has increased over recent years and this trend is expected to continue. An alkaline cyanide solution is used as the lixiviant at all heap leach operations. Currently, there are 78 commercially active gold and silver leaching operations in

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