The main method of gold cyanidation gold processing of non-mention

Gold cyanide extraction method is the most common and most stable method of gold and silver ore and materials, but there are also leaching time (leaching cycle) long (one week to one year heap leaching, agitation leaching of 24 to 72 hours), organic carbon, antimony, arsenic, copper, zinc and other harmful elements very sensitive, causing a significant reduction of gold, silver leaching rate, the disadvantage substantial increase in production costs, in particular the Act cyanide is highly toxic, damage to the environment is considerable. Therefore, how to improve gold, silver leaching rate, reduce costs, find an alternative non-toxic or highly toxic cyanide toxicity smaller new technology and new technology is an important research topic.

Non-cyanidation leaching agents include thiourea, oxygen, bromine, iodine, ammonia, thiocyanate, calcium polysulfide and the like.

(1) of the Act thiourea under acidic conditions gold dissolution speed, non-toxic, selective than cyanide, is not sensitive to the base metal impurities, in dealing with some gold-bearing materials, such as anode slime, gold uranium acid and sulfuric acid leaching slag and so have some advantages, but high drug consumption, leaching equipment perishable, the lack of effective method for recovering gold from thiourea solution.

In 1997, it was found that sodium sulfite can inhibit the irreversible decomposition of alkaline thiourea to some extent, promote the dissolution of gold, gold dissolution can select rows from the gold-bearing waste; that the sodium silicate is an alkaline thiourea gold extraction efficiency stabilizer.

(2) a halogen and halide salt used in the Act reagent mainly chlorine, bromine, iodine, chloride, iodide, bromide, etc., e.g., chlorine, hypochlorite, chloride method, K reagent, Geobrom3400 , Bio-D reagents and other oxidants. Chlorine leaching process, both as an oxidizing agent, and as a complexing agent to generate AuCl32-, halogen ions (X-) is Au2 + Au + and strong ligand chloride leaching carbon material suitable for processing gold ore containing arsenic, antimony burn slag, re-election of gold concentrate containing arsenic and pyrite gold ores.

Bromide method is to replace one of the most promising cyanide leach gold extraction process, the advantage of cheap, high leaching, leaching speed, non-toxic, non-corrosive, agents can be recycled, the recovery of gold from the pregnant solution convenient. Many foreign research iodide method using iodine - iodide solution than cyanide leaching method can be obtained with high gold leach rates from iodine - iodide direct electrowinning of gold is also possible.

(3) of the Act nitrile using malononitrile (also known as cyanuric acid nitrile), cyanoacetamide and acetonitrile three kinds of nitrile to extract gold. In dealing with carbonaceous gold ores, nitrile cyanide gold leaching rate is much higher than the law. In dealing with oxidized ores and sulfide ores, its gold leaching with cyanide leaching rate as effective, but its high price.

(4) Method i.e. microorganisms capable of biological agents leach gold, which the cellular components of microbial protein, microbial metabolites of amino acids (glycine, histidine, aspartic acid, etc.). Protein and gold to form a complex with a negatively charged, this complex was purified by amino acid groups of the nitrogen atom, form a stable gold complex.

(5) of the Act coal golden reunion is the use of flotation reagents to improve the hydrophobic characteristics of the gold particle surface by the collision of the mixing process, the hydrophobic gold particles into the Aggregates. Contained gold aggregates through cycles, enrichment and ashing, the resulting ash after baking or other means smelting process to be finished gold.

(6) polysulfide Act and the Act uses lime sulfur and lime sulfur leaching of gold and silver produced by the reaction reagents, chelating polysulfide ions S22-, S32-, S42-, S52-, etc., which gold ions strong complexing ability, in a suitable oxidant (such as potassium permanganate, etc.) with the next, or by means of disproportionation polysulfide ions, can effectively dissolve gold and silver.

(7) Other methods Other methods are humic acid method, FM reducing reagent, thiosulfate method.