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As a rare metal resource, natural resources of gold deposits are gradually decreasing, and extraction of gold deposits is coming to an end. Refractory gold deposits and gold associated with other minerals have also become the focus of people. At present, cyanidation leaching is the common gold processing method for such gold deposits.
Generally, in the process of gold difficult to process against doing usually select grinding fineness, pH, temperature, stirring speed, cyanide agent, pulp solid-liquid ratio, leaching time, variabling one by one. So that these factors to the influencing factors of gold leaching. In fact, there are other gold leaching factors such as dosage of impurities in the ore, infusions, different ore varies, will not be discussed here. Below, we will explore the influence of these factors on gold leaching one by one.
Generally speaking, the fineness of grinding is related to the relation of inlay of ore, and the fineness of different inlay shape and fineness of ore have influence on the fineness of grinding. Take a gold mine as an example, the natural gold of this gold mine has a relatively fine particle size, and it becomes micrograined gold, 0.037~0.01mm accounting for 56.32%, while the part less than 0.01mm accounts for 36.80%. It is intergranular embedded in various minerals.
After identification, the grindability coefficient is determined to be 0.767. The 0.071mm content was 55%, 65%, 75% and 85%, respectively. The results showed that the recovery rate was better when the 0.071mm content was 85%. In terms of technology, the recovery rate of gold was increased from 82%~85% to 91.0%. Therefore, the grinding fineness should be determined for different gold mines. The grinding fineness has a great influence on the recovery rate.
pH, temperature and stirring speed affect the leaching of gold reason is that in cyanide pulp zhongyi reaction generated by hydrocyanic acid (HCN), hydrocyanic acid volatile and toxic, if the volatilization of hydrocyanic acid from pulp can lead to the loss of cyanide, also can cause environmental pollution, therefore in the process of leaching tend to adjust pH value to 10 ~ 11, uniform mixing, at low temperature, to prevent the volatilization of hydrocyanic acid.
Gold is not active metals, in the process of cyanide leaching, gold can be under the action of oxygen and cyanide complexation reaction (CN), produce a water-soluble melamine aurous acid salt complex [Au (CN) 2-], so the cyanide agent is a key factor determine gold dissolved, in general, to ensure that a certain amount of free cyanide in the pulp, to margin normal cyanide leaching, cyanide agent dosage according to the nature of the ore.
Pulp solid-liquid ratio both pulp density, pulp density will directly affect the leaching rate of gold leaching speed and slurry concentration is too high, the pulp is hard to flow, the gold leaching speed and low leaching rate, pulp density low, while improving the leaching rate and leaching rate of gold, but so requirements for equipment volume increases, the rise in the cost of equipment investment, will also increase, leaching agent dosage, the rise in the cost of production, so want to take a test to determine appropriate solid-liquid ratio.
Due to the cyanide leaching of gold is a relatively slow process, leaching time, generally within 24 h of above, the leaching rate of gold will increase with the leaching time, but to a certain degree, the leaching rate of gold growth slowed, increasing time longer, the leaching rate of gold increase little, taking a carbon arsenic low grade oxidized gold ore as an example, 95% in the grinding fineness, pulp density 33%, PH value of 12, leaching experiment and leaching time for 24 hours, 36 hours, 48 hours, the leaching rate of gold is 81.48%, so for gold leaching, leaching time, to ensure that a certain However, it should be noted that too long leaching time has little effect on the improvement of gold leaching rate.
The reason gold leaching requires inflation is that effective oxidation aid in the dissolution of gold, so inflation increases the solubility of oxygen in the slurry and thus the dissolution rate of gold, usually by means of inflation or agitation in the slurry.
Above are some of the factors can influence the gold leaching, we can get the conclusion is: because gold is extremely lively, therefore, when dealing with difficult to leaching of gold can by changing these factors to improve the leaching rate of gold, of course, the ore samples to qualified beneficiation test institutions ore dressing experiment was carried out to formulate appropriate leaching process and reasonable index is more appropriate choice, avoid to mend after put into production, reduce the loss of concentrator.