acidic leaching of gold

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Fast and Effective Gold Leaching from a Desulfurized Gold Ore ...

Nov 1, 2013 ... The effects of various leaching conditions for gold extraction from sulfur-containing gold ore using acidic sodium chlorate solution were investigated. The contents of gold and sulfur from the ore were 55.7 g/ton and 11.67 wt %, respectively. It was found that the presence of sulfur greatly inhibited gold...

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Advances in Gold and Silver Processing - 911 Metallurgist

discuss the leaching characteristics of gold in hypochlorite leaching solutions. The dissolution of gold in a hypochlorite solution not only depends on the concentration of the hypochlorite but also on other variables, such as hydrochloric acid, sodium chloride and temperature. The dissolution rate of gold in hypochlorite...

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The dissolution of gold in acidic solutions of thiourea - ScienceDirect

In order to evaluate the potential of acidic thiourea as a reagent for leaching gold, a study was made of the dissolution of gold in acidic solutions of thiourea containing various oxidants. Experiments were conducted on rotating disks of pure gold and on ground gold ores. The chemical oxidants used included iron(III),...

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A REVIEW OF GOLD LEACHING IN ACID THIOUREA SOLUTIONS ...

No passivation of the gold surface is observed in simple acidic solutions. However, in actual leaching systems, some sulfide minerals significantly catalyze the redox reaction between thiourea and ferric ion, causing high thiourea consumption if ferric ion is present in excess. The presence of copper has a deleterious...

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How to Leach Gold Ore With Chlorination | Sciencing

Apr 25, 2017 ... Halogens are reactive, non-metal elements with seven electrons in their outer shell which allow them to easily combine with other elements. The use of chlorine is both the cheapest and most plentiful method for leaching gold. When you mix sodium chloride and hydrochloric acid together, you produce a...

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Patent WO1991013177A1 - Extraction and recovery of gold - Google ...

Sep 5, 1991 ... A process for the hydrometallurgical recovery of gold from gold-bearing material comprising the step of treating gold-bearing material with an acidic ... The invention relates to the extraction and recovery of gold from gold-bearing materials, for example those above mentioned, using leaching methods such...

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A review of gold leaching in acid thiourea solutions | Request PDF

Dec 18, 2017 ... Request (PDF) | A review of gold lea... | Since the initial report of thiourea as a complexing reagent for gold leaching, considerable research has been directed toward the use of thiourea as an alternative to cyanide for gold extraction from different auriferous mineral resources. At the same time, some...

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The dissolution of gold in acidic solutions of thiourea | Request PDF

Dec 19, 2017 ... The dissolution of g... | In order to evaluate the potential of acidic thiourea as a reagent for leaching gold, a study was made of the dissolution of gold in acidic solutions of thiourea containing various oxidants. Experiments were conducted on rotating disks of pure gold and on ground gold ores. The ch...

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Heap leaching - Wikipedia

The method is an acid heap leaching method like that of the copper method in that it utilises sulfuric acid instead of cyanide solution to dissolve the target minerals from crushed ore. The amount of sulfuric acid required is much higher than for copper ores (as high as 1,000 kg of acid per tonne of ore, but 500 kg is more...

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Alternative Leaching Reagents for Gold - Springer Link

Sodium cyanide has been the preponderant leaching reagent for gold due to its excellent extractions from a great variety of ores and its low cost. Although cyanide is poisonous, it has safe industrial and environmental records at the high pH range required in cyanide leaching. In addition, the low concentrations of cyanide...

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The kinetics of pyrite and elemental sulfur reactions during nitric acid ...

technical capabilities of nitric acid leaching. Gold recoveries were improved from 48-68Vo to an average of 937o. Reductions of around 2 kg of cyanide and base per tonne of ore were also shown for most materials. Remaining unrecovered gold could be partially due to elemental sulfur remaining after the pre-oxidation step...

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Process development for recovery of copper and precious metals ...

Aug 5, 2013 ... Process development for recovery of copper and precious metals from waste printed circuit boards with emphasize on palladium and gold leaching ... The precipitation of Au and Ag from acidic thiourea leachate was investigated by using different amounts of sodium borohydride (SBH) as a reducing agent.

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Recycling of Electronic Waste, Using Basic and Acid Leaching

Mar 27, 2016 ... How to cite this paper: Cortes, M.A. and Patiño, M.L.D. (2016) Recycling of Electronic Waste, Using Basic and Acid Leaching. Open Journal of ... TCI, Acidic and Basic Leaching and Electronic Waste. 1. ... Significant amounts of iron, aluminum, copper and some precious metals such as gold and silver can...

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Separation and Recovery of Gold, Copper and Silver from Waste ...

Abstract: A new process involving alkaline dechlorination and acidic leaching is developed for separation and recovery of valuable metals (such as copper, gold and silver) from waste acid residues containing 20.5% sulfur and 3.198% chlorine. It is shown that under the conditions of the liquid/solid ratio of 6:1 mL/g, leaching...

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High Pressure Acid Leach & Pressure Oxidation - ALS Global

High Pressure Acid Leach (HPAL) and Pressure Oxidation (POX) testing services provide a unique opportunity to evaluate and optimise the most economically viable process routes for the recovery of most metals such as nickel from lateritic ores and gold from refractory ores. HPAL and POX are commercially proven and...

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Alternative Gold Leaching Methods - January 2014 (Vol. 83, No. 5 ...

For a number of reasons, strongly acidic alternative methods are less desirable. Let's take a closer look at some of the different alternative leaching options, their strengths and weaknesses. Chlorine. Chlorine was the only commercially available chemical for leaching gold before the cyanide process was developed.

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p. 1-24.pdf

leaching of gold, there has not been any commercial introduction of this leaching system. Leaching is commonly done by using a variety of chemicals which include nitric acid (Krupkowa et. al., 1987), sulphuric acid, nitric acid and hydrogen peroxide. (Kristofova and Karnil, 1996), aqua regia (Lee et al., 1997), ferric chloride...

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Thiourea Leaching of Gold - Imperial Spiral - Imperial College London

Moreover, if using cyanide to treat refractory sulphide gold-containing ore, which have been pre-oxidised to release the gold, the highly acidic solutions produced must be neutralized prior to cyanidation, whereas thiourea can be used directly, since gold leaching occurs in acidic solutions [28]. Despite the proven...

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New Hydrometallurgical Process for Gold Recovery

Abstract: A new hydrometallurgical process has been developed for recovery of gold from secondary sources such as gravitational concentrates from alluvial sands. The method consist in leaching the gold with chlorine resulted from NaClO decomposition in hydrochloric acid medium, [AuCl4]- selective recovery from...

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EARTHWORKS | Acid Mine Drainage

At metal mines, the target ore (like gold, silver, copper, etc) is often rich in sulfide minerals. When the mining ... Acid mine drainage can be released anywhere on the mine where sulfides are exposed to air and water -- including waste rock piles, tailings, open pits, underground tunnels, and leach pads. Acid drainage is often...

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Gold Leaching Using Thiourea | Gold | Redox - Scribd

GOLD LEACHING USING THIOUREA. Thiourea, CSN(NH2)2 is an organic compound which dissolves easily I acid solution in a stable molecular form. Gold dissolves in acidic thiourea solution to form a stable complex, 2Au + 4CS(NH2)2 + 2Fe3+ = 2Au(CS(NH2)2)2+ + 2Fe2+ In the thiourea reaction, ferric iron is used as...

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potential applications of thiourea in the processing of gold - SAIMM

can then be selectively stripped into acidic solution<! of thiourea. Acidic solutions of thiourea have been used to improve the selectivity of the extraction of gold(I)-cyanide from ion-exchange resins loaded with the metal-cyanide usually found in cyanide leach liquors; studies were made on strongly basic ion-exchange resins...

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

either leaching or dissolution operations require highly corrosive media due to the well-known chemical inertness of the noble metal toward most acids and bases.3. Several reagents are known to leach native gold from gold-bearing ores. It has been known for more than a century that alkaline solutions of alkali-metal.

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Thermodynamic and kinetic of iodine−iodide leaching in gold ...

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...

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Leaching of Gold - DocCopper

Because of the need for a complexing agent, pH is also crucial in maximizing the ability of lixiviant to extract gold. The solution's pH will dictate what specie the complexing agent forms in solution and thus the form of the gold complex. In extreme case, as with cyanide, pH not only controls the leaching ability of the solution,...

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Acid Washing – Denver Mineral Engineers

Acid washing has proven to be a very cost-effective means of maintaining the activity of activated carbon. During operation, carbon will typically become fouled due to an accumulation of precipitated mineral salts. This reduces the carbon particle area available for gold and silver adsorption. Cyanide leaching and carbon...

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Alkaline Oxidative Leaching of Gold-Bearing ... - CDC stacks

Sep 5, 1989 ... a jarosite-bearing leach residue. However, controversy exists regarding scorodite's environmental stability (11-12). The acid process necessitates that the residue be thoroughly washed and residual acid neutralized prior to cyanidation for the gold recovery. Ores containing high carbonates will result in...

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Enhanced leachability of gold and silver in cyanide media: Effect of ...

Gold and silver in the calcine product respond poorly to sulphuric acid leaching and therefore are lost to the leach residues. Furthermore, zinc residue from the electrowinning cells usually contains gold and silver. Owing to low grades and fine structure of the gold/sil- ver/zinc residue, recovery of metals by leaching presents.

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Hydro Metallurgical Process Equipment - Koch Knight

The extreme abrasion, high pressure and elevated temperature makes acid-proof brick lined carbon steel autoclave and vessels the chosen material for this process. ... The ore slurry mixed with sulfuric acid enters the pressure leach vessel containing sulfuric acid and is exposed to high temperature and steam pressure.

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pH/ORP Cyanide Leaching Process Understanding Leaching of ...

heap leaching. If the gold exists in a larger, more concentrated state, the ore will be finely ground and leached in a tank. A gold cyanide complex will form as the gold dissolves from the rock or pulp (finely ground ore), according to the equation: 4Au + 8CN- + 2H2O +O2 → 4Au(CN)2 + 4OH-. The control of pH in a cyanide...

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Gold Recovery from its Flotation Concentrate using Acidic Thiourea ...

The method for the recovery of gold from its flotation concentrate using acidic thiourea leaching followed by adsorption on an organosilicon polymer (PSTM-3C) was discussed in the present study. The study had allowed identification of the effect of thiourea, oxidizer and acid concentration, leaching time, temperature and...

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How to Extract Gold From Electronics: 11 Steps (with Pictures)

Aug 13, 2014 ... In this Instructable, I will show you how to extract gold from computers using products most people have lying around in their homes. The way I extract the gold is... ... I am using 3% hydrogen peroxide and the toilet bowl cleaner is 9.5% hydrochloric acid.). Make sure you are outside or in a very well...

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Amino acids key to new gold leaching process - Phys.org

Oct 24, 2014 ... Curtin University scientists have developed a gold and copper extraction process using an amino acid–hydrogen peroxide system, which could provide an environmentally friendly and cheaper alternative to conventional methods.

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gold and silver - EPA

Cyanidation leaching is the primary means of recovery of fine gold and silver. In this process, solutions of sodium or potassium cyanide are brought into contact with an ore which may or may not have required extensive preparation prior to leaching. Gold and silver are dissolved by cyanide in solutions of high pH in the...

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Thiosulphate Stability In Gold Leaching Process - Bibliothèque et ...

Figure 2-1 The Electrochemical Mode1 Of Gold Leaching And Catalysis .................... 2-9. Figure 2-2 Eh-pH Diagram For Gold-thiosdphate-arnmonia S ystem .......................... 2-9. Figure 2-3 Eh-pH Diagram For The Copper-thiosulphate-ammonia Systern .............. 2-10. Figure 2-4 Eh-pH Diagrarn For...

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A Straightforward Route to Tetrachloroauric Acid from Gold ... - MDPI

Aug 18, 2015 ... Research involving gold nanoparticles has increased significantly over the last two decades, creating with it the need for high purity gold chloride (generally in the form of tetrachloroauric acid) as a starting material ..... Konyratbekova, S.S.; Baikonurova, A.; Akcil, A. Non-cyanide Leaching Processes in Gold.

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Oxidative Hydrometallurgy of Sulphide Minerals

Mar 23, 2012 ... At very acid conditions (i.e, pH < 2), it is possible to dissolve metals as Fe and Cu ions. In this context, oxidative leaching with ozone is relevant in copper-iron sulphide and gold- and silver- containing sulphides. Moreover, oxidative leaching of coal-containing iron sulphide might also have a positive impact...

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Recovery of gold,silver and copper from complex gold concentrate ...

Gold,silver and copper were extracted from complex gold concentrate by roasting-acidic leaching-cyanidation process.The experimental results show that the roasting temperature,time,additive and its dosage have great influence on the leaching of gold,silver and copper.The optimal conditions were further determined as...

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Processing technologies for gold-telluride ores - Semantic Scholar

nide leaching tests on synthetic calaverite (AuTe2) and syl- vanite (AuAg)Te2 result in lower gold recoveries [5]. Jayasekera et al. [6] studied the dissolution of calaverite electrochemically in both acidic and alkaline media. It showed that the slow dissolution rate in alkaline cyanide solutions was due to the formation of a...

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Environmentally Benign, Rapid, and Selective Extraction of Gold ...

Jun 30, 2017 ... For instance, the KI/I2 system has a much higher reagent cost than the cyanide system, and the acidic leaching pH of 2, required by the thiourea ... For all the tested methods, the effect of pH on gold leaching from the ores was complex, and the NBS/Py method gave the maximum Au leaching yield of...

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