Main factors affecting tank leaching
When cyanide diafiltration tank leaching, the leaching rate of gold depends on the size of the gold particles, the grinding fineness, ore texture and structure, impurities detrimental to cyanide, cyanide concentration and the amount of leaching solution, percolation rate, percolation time And the factors such as the degree of washing of the leaching residue, the appropriate values ​​of each factor depend on the nature of the material to be immersed.
The size of the gold particles and whether the ore is loose and porous is the decisive factor in determining whether the infiltration process can be treated. When the gold ore in the gold-bearing ore is coarse and porous, it is more suitable for treatment by diafiltration cyanidation.
The leaching rate and the leaching speed of gold are related to the fineness of grinding. The fineness of grinding is high, and the exposure of gold particles is high, which can increase the leaching rate of gold, but the leaching speed will decrease. Therefore, it is better to carry out grading after grinding, and the ore is infiltrated, and the fine mud is stirred and leached, so that the dissociation exposure of the gold particles can be improved, and a certain infiltration speed can be ensured.
The cyanide concentration in the cyanide leaching agent during the infiltration is generally higher than the cyanide concentration in the cyanidation, usually 0.1% to 0.2%, and the cross-flow infiltration is carried out using a plurality of batches of cyanide leaching agent having a gradually decreasing concentration.
When the percolation tank is immersed, the linear velocity at which the liquid level is lowered or rised indicates the infiltration speed. Generally controlled at 50-70mm/h, the leaching speed depends on the particle size, shape and particle size composition of the material to be immersed, the uniformity of the charge, the height of the layer, the mud content and the characteristics of the false bottom filter medium. If the infiltration rate is less than 20 mm/h, it is considered to be difficult to infiltrate the material. When the infiltration rate is too large, it may be caused by the phenomenon of scouring caused by particle size segregation and uneven charging. The infiltration rate is too small, which may be caused by high sludge content or clogging of filter media by sludge and calcium carbonate precipitation. Therefore, the pseudo-bottom filter medium should be periodically sprayed with water or washed with a dilute hydrochloric acid solution to remove the calcium carbonate precipitate.
All impurities that are harmful to cyanide can reduce the leaching rate of gold during leaching cyanide tank leaching. When the content of iron sulfide is high and the oxidation is serious, the ore can be washed with water, alkali or acid before infiltration, and the free acid and soluble salt can be washed away. Alkaline washing neutralizes the acid. Washing with dilute sulfuric acid solution removes steel oxides and carbonates. Addition of cyanide leaching agent in an amount of salt may reduce the adverse effect of lead sulfide component, arsenic, and antimony.
The infiltration time depends on the properties of the ore, the rate of infiltration, the method of loading and unloading, the concentration of cyanide and the consumption basin. The period of a percolation tank in production is generally 4 to 8 days. When the material classification efficiency is not high or the sludge content is high, an infiltration period can be as long as 10 to 14 days.
The degree of washing of cyanide slag is one of the main factors affecting the gold leaching rate. Generally, the leaching cyanidation leaching is finished. It should be washed once or twice, and can be washed one or three times with the concentration washing step by step. Finally, it must be washed 1 or 2 times with water to wash the precious liquid in the gap of the layer as completely as possible.
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