Jun 11, 2020 A large proportion of the gold processed in the 21 century will be recovered from sulfide ores. Since the sulfide minerals are to some extent soluble in cyanide solutions, there will always be some sulfur species present in the leach solution. It has been shown that soluble sulfide hinders the rate of gold leaching, forming a protective layer of the type AulSx. Electrochemical studies of the ...
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.
Arsenic sulfides such as arsenopyrite have a negative effect in gold leaching. 5. Copper sulfides ores that contain gold associated with copper sulfide minerals belong to this class. Chalcopyrite and chalcosite are the main copper minerals and they have a detrimental effect in gold leaching. 6.
Sep 05, 2018 Five hundred grams of dry-ground ore was leached with 870 mL leach solution containing 0.34 lb NaCN per ton of solution and 2.5 lb lime per ton of ore. The slurry was rolled in a plastic bottle for 24 h at 20 to 25 C. Following cyanide leaching, varying amounts of sulfide were added to the slurry and mixed by rolling for 1 h.
The effect of sulfide and cyanide concentrations on the leaching reaction were investigated, and it was shown that the sulfur formed is chemically attacked by cyanide, resulting in higher leach ...
ground ore was leached with 870 mL leach solution containing 0.34 1b NaCN per ton of solution and 2.S lb lime per ton of ore. The slurry was rolled in a plastic bottle for 24 h at 200 to 2So C. Follow ing cyanide leaching, varying amounts of sulfide were added to the slurry and mixed by rolling for 1 h.
Jan 01, 2020 In cyanide leaching process, these co-associated minerals (or elements) change the physicochemical environment of cyanide leaching solution and affect the interactions between cyanide and gold. Comparatively, the siliceous minerals such as quartz are commonly found in gold ore 16 .
During the cyanide leaching of sulfidic gold ores, the sulfide minerals dissolve into the leach solution and produce metastable sulfur species, such as sulfide, bisulfide, polysulfide, elemental ...
Jun 24, 2015 During leaching with Ferric ion a critical balance between Fe 2 and Fe 3 ions in the leach solution is essential to maintain efficiency of leaching and subsequent electrolysis. The ferric ion is also very sensitive to pH changes, hydrolysis and precipitation of basic ferric salts starting at pH 3.5.
Apr 07, 2018 The discovery of low-grade gold-silver deposits in the United States has resulted in construction of several cyanide-leach carbon-in-pulp (CIP) milling facilities. Gold and/or silver ores typically contain other metals such as mercury and a variety of base metals. Of all the metals most likely present, mercury presents the most serious problem.
The effect of galvanic interactions and sulfide mineral dissolution on the gold leaching kinetics in aerated cyanide solutions is investigated. Gold leaching kinetics were measured using a ...
Abstract Recently, leaching of gold with cyanide has come under scrutiny for its possible detrimental effects to the environment. Also, in some gold bearing ores and concentrates, conventional cyanide leaching is not the best method for gold extraction. This is due to gold particle encapsulation, cyanicides or pregrobbing carbon such as found in refractory ores and concentrates.
Jan 01, 2017 However, most of copper sulfide minerals dissolved well both in water and cyanide solutions, and copper from the minerals consumed DO and cyanide to oxidize and leach. Only in the presence of chalcopyrite, gold leaching was effectively occurred with increasing DO. However, chalcocite and covellite severely retarded gold leaching.
gold cyanide solutions (i-2). Silver sulfide would tie up considerable silver, and iron sulfide forms ferrocyanide, re sulting in cYanide loss. Calcium and so dium sulfides are effective in precipi tating mercury and are not harmful to the gold recovery process. Redissolution of
It is thus clear that the Cyanide leaching of gold in solutions containing sulfide 1099 surface of the gold is passivated when it is exposed to the hydrosulfide solution, and this passivation remains when the gold is transferred to a hydrosulfide free solution.
Abstract. A large proportion of the gold processed in the 21 st century will be recovered from sulfide ores. Since the sulfide minerals are to some extent soluble in cyanide solutions, there will always be some sulfur species present in the leach solution. It has been shown that soluble sulfide hinders the rate of gold leaching, forming a protective layer of the type Au/S x.
This process has been shown to passivate gold leaching in cyanide solutions in the presence of sulfide ions (Jeffrey and Breuer, 2000). However, for pure silver, the formation of a monolayer of ...
Since a large proportion of gold ores contain sulfide minerals, the effects of these minerals on gold dissolution in cyanide solution have interested many researchers. Early studies on the dissolution of gold in cyanide solution in the presence of sulfide minerals have shown that heavy metal components, such as Cu, Fe and Zn, significantly increase the consumption of both cyanide and oxygen ( Habashi,
Sulfide sulfur solution 2M sulfur 2M sodium sulfide Bisulfide sulfur solution 2M sulfur 2M sodium bisulfide Prior to each experiment, gold was electroplated onto the platinum coated quartz electrode at 25A/m2 from a solution containing 0.02M potassium dicyanoaurate, 0.23M potassium cyanide, 0.086M potassium carbonate.
The effect of galvanic interactions and sulfide mineral dissolution on the gold leaching kinetics in aerated cyanide solutions is investigated. Gold leaching kinetics were measured using a rotating electrochemical quartz crystal microbalance (REQCM), which measures the leaching rates in-situ. When the mineral is electrically in contact with gold, the gold dissolution rate increases as a result ...
Carbonaceous gold ores can have the carbon adsorb the gold onto its surface, and as a result will not be recovered from the pregnant solution. Leaching gold from sulfide ores is difficult, at best. Generally, the recovery for cyanide leaching of sulfide or refractory ores is no better than 30%, which is not a worthwhile venture.
2. CYANIDE LEACHING Cyanidation uses solutions of sodium or potassium cyanide as lixiviants (leaching agents) to extract precious metals from ore. Cyanidation techniques used in the gold industry today include heap or valley fill leaching, agitation leaching followed by carbon-in-pulp (CIP), and agitated carbon-in-leach (CIL). Cyanidation is best
A process is described by which copper and optionally silver and gold are recovered from sulfide and oxide ores, concentrates or slag, which contain the metals. The particulate materials are treated with an aqueous solution of an alkali cyanide or alkaline earth cyanide, the laden solution is filtered, if desired, a water-soluble sulfide compound is added to the laden solution or filtered ...
May 21, 2020 The cyanidation of copper flotation tailings containing sulfides for gold recovery is an example of the formation of cyanide complexes with copper and silver during the leaching process 11,12. Figure 4 shows the MLA Automated Minerology image of an ore sample from a copper mine in Mexico, containing chalcopyrite and bornite as copper sulfide ...
The leaching behaviour of a sulphide gold-silver ore was investigated in terms of a relationship between gold and silver extractions and cyanide consumption. Ninity five Au % and 88.0% Ag extractions were obtained under the determined conditions of 24 h leaching duration, -74 m particle size, 40% solids ratio, 4 g/dm3 NaCN concentration, and ...
Antimony ions and especially the sulfide ions had intensive deleterious effects on the gold dissolution.The anodic dissolution of gold was studied in the pure cyanide solution and in the cyanide solution containing various ions and sulfide minerals. The potentiodynamic method was used to study the anodic dissolution reaction.
Gold dissolution and copper suppression during leaching of copper-gold gravity concentrates in caustic soda-low free cyanide solutions Oraby, E. Eksteen, Jacques ( 2015 ) In the cyanidation process, coppergold deposits containing significant amounts of cyanide soluble copper can lead to high cyanide consumption with low gold extraction.
Nov 01, 2019 Cyanidation is the main process in gold leaching. There are several parameters that affect gold recovery and cyanide consumption. In this paper, the effect of the oxidative pretreatment and lead nitrate addition on the cyanidation of Zarshuran refractory gold ore containing 3.32 ppm Au, 1.09% As, and 0.5% sulfur were investigated. Au recovery was increased from 79.4% to 89.4% in the
By 1997 a mill for recovering gold from the Pipeline was up and running. This was the start of something big, over 9,000,000 ounces big. Generally, if the gold content of the ore is 0-0.002% the shiny metal is not economically recoverable. Low grade ore containing 0.03-0.09% gold goes directly to heap leach which begins the leaching circuit.
Gold and silver tailings are generally produced by an alkaline cyanide leach process. ...Gold heap leaching uses an alkaline solution containing cyanide to extract the gold and other precious metals from the ore (Van Zyl, 1985).. Author Jerrold J Marcus. Publisher World Scientific ISBN 9781783264124 Category Page 816 View 709 Download
process discussed above. Instead of cyanide leaching of the cyclone overflow, the gold and sulfide minerals are recovered by flotation. The particles in the cyclone overflow are mixed with chemical reagents to render the surfaces of the gold-containing sulfide minerals hydrophobic (metallic gold is naturally hydrophobic).
Jun 10, 2020 JEFFREY M I, BREUER P L. The cyanide leaching of gold in solutions containing sulfide J. Minerals Engineering, 2000, 13(10) 10971106. Doi 10.1016/S0892-6875(00)00093-5. Article Google Scholar 21 LORENZEN L, DEVENTER J S J V. Electrochemical interactions between gold and its associated minerals during cyanidation J.
Aug 18, 2016 Another big disadvantage of cyanide is the low leaching efficiency of refractory sulfide minerals or gold resources that contain copper or carbonaceous preg-robbing materials. Additionally, these resources afford a higher demand of cyanide and decrease the dissolution yield.
Aug 21, 2020 (4) If the raw gold ore contains arsenopyrite, mercury, selenium and tellurium, they will all react with sodium cyanide. When the deposit contains carbonaceous rock, especially organic carbon, its adsorbability for sodium cyanide is stronger, making it difficult for the cyanide leaching of gold. 3.Cyanide Hydrolysis. In solution, cyanide ...
The exception here is that instead of sending the cyclone overflow for cyanide leaching, it is sent instead for flotation processing. The particles are mixed with chemical reagents to render the surfaces of the gold-containing sulfide mineral hydrophobic. Froth flotation cells bubble air through the slurry.
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