Cyanide leaching of gold

Methods cyanide leaching of gold can be divided into two types: percolation cyanide leaching and stirring cyanide leaching.

There are two cyanide leaching methods: tank leaching and heap leaching, and tank leaching is often used to treat 3+. Gold-bearing sand and coarse-grained calcine. When leaching gold-bearing lean ore by heap leaching, the ore is usually crushed below somm (or lomm) in advance according to the disseminated particle size of natural gold and the porosity of the ore. The smaller the ore block tension is, the higher the gold leaching rate is. When cyanide is leached by percolation method, the concentration of sodium cyanide is often. .03%~。 ,2%。 The index of cyanide leaching depends on factors such as gold particle size, sulfide content, ore block size, leaching speed, leaching time, cyanide concentration and washing degree of leaching residue. When treating gold-bearing quartz sand, the leaching rate of gold can reach 85%-90%; When the particle size is coarse, the leaching rate of gold drops to 60%. When cyanide is used for heap leaching, the gold content in your solution is low, so activated carbon is generally needed for adsorption and enrichment. Gold is extracted from solution, which is obtained by electrolytic extraction or zinc replacement desorption of gold-loaded carbon. Stirred cyanide leaching is often used for leaching with particle size less than. 0.3 mm gold-bearing mineral raw materials are leached in compressed air stirring tank, mechanical stirring tank or mixed stirring tank. Leaching includes solid-liquid separation of pulp, countercurrent washing, zinc powder replacing expensive solution and gold mud smelting. The leaching pulp concentration is generally less than 3D%~33%, and when the slime content is high, the leaching pulp concentration should be less than 22% ~ 25 writes；. During operation, lime is added to make the pH value of pulp 29-12; Filling air to keep the concentration of dissolved oxygen in the pulp in the best proportion with the concentration of sodium cyanide; The concentration of sodium cyanide in pulp is usually. .02% one. . 1%。

Many mineral processing plants using stirred cyanidation process use washing method to separate expensive liquid from leaching residue. Washing methods can be divided into decantation, filtration and fluidized washing, and the most commonly used method is continuous countercurrent decantation (CCD method). The thickener used in this method can be divided into single layer and multi-layer.

Many domestic cyanide concentrator adopt 2~3 layers thickener for solid-liquid separation and continuous countercurrent washing. After clarification, filtration and deoxidation, the precious solution is sent to zinc powder for replacement, and the obtained gold mud is smelted to obtain mixed gold (gold-silver alloy). The method of cyanide leaching of silver is similar to cyanide leaching of gold, but it is generally only used to treat a single silver mine. Only when silver exists in the form of natural silver, gold-silver ore, amphibole and amalgam can cyanide leaching obtain satisfactory silver leaching rate. In order to strengthen the cyanide leaching process, since the late 1970s, cyanide carbon pulp method, cyanide carbon leaching method and cyanide resin pulp method have been applied in industry. Oxygen pressure cyanide leaching or adding strong oxidant (such as hydrogen peroxide) can strengthen the leaching process of gold and silver, shorten the leaching time and improve the leaching rate of gold and silver. Hydrocyclone ore.