Pyrite slag extracts precious metals gold and silver

YA Attja burning and other biochemical leaching from pyrite slag leaching of precious metals Au, Ag, achieved good economic returns and significant environmental effects. In this study, the Leadville pyrite slag was firstly floated and concentrated by froth flotation. Before the cyanide leaching, the pyrite concentrate was treated with different cycles of domesticated 12 weeks of Thiobacillus ferrooxidans. The extraction rate of conventional leaching gold was only 32%, and the extraction rate of silver was 48%. With the bacterial cyanidation leaching treatment, the extraction rate of gold was increased to 95%, and the extraction rate of silver was increased to 98%. In addition, bioleaching does not affect the extraction rate of gold and silver from the sulphide in the slag or from the metal powder of gold or silver.

Lu Tengjia explored a new method for extracting gold and silver from the chlorinated dust mud of pyrite cinder. First, the chlorinated dust of pyrite cinder is passed through reduction smelting, so that a large number of substrates are separated by slag formation, and gold and silver are fully "naked". This exposed gold and silver, after encountering a large amount of particulate lead dispersed in the melt, is quickly captured by the particulate lead to form noble lead. The precious lead ratio is very large, and it is easy to sink to the bottom of the melt, so that the gold and silver chloride dust are separated and all are concentrated in the collector. Since the affinity of lead to oxygen is greater than that of silver and other impurity metals, the lead can be separated by ash blowing to produce a gold-silver alloy containing 93% to 95% of silver. Then, the purpose of separating gold and silver can be achieved by electrolysis. The gold and silver alloys are cast into an anode plate, and the stainless steel plate is used as a cathode. The electrolyte contains silver 100-150 g/l, nitric acid 2-8 g/l, current density. 270 ~ 450A / m ² , the tank voltage is 2 ~ 2.5V. After electrolysis, the silver powder is deposited on a stainless steel plate and periodically washed and dried. Gold is dropped into the electrolytic bag in the form of anode mud, taken out and washed twice with 1:4 nitric acid, and then washed with distilled water until neutral and dried. Gold powder and silver powder are finished products by ingot casting. The average recovery rate of semi-industrial test gold reached 97.1%, and the average recovery rate of silver reached 95.2%. The gold grade can reach 99.5% and the silver grade can reach 99.98%. It has obvious economic and social effects.

Zhang Jincheng conducted an experimental study on the recovery of valuable metals such as gold, silver, copper , lead and zinc from the sulfuric acid slag of the Silver Smelter of the Silver Company. The process of recovering gold and silver by cyanidation after pretreatment with sulfuric acid-salt leaching was carried out. The optimum conditions for cyanidation were as follows: NaCN concentration was 0.03%, pH value was 11. Leaching time was 24 h, and liquid-solid ratio L/S was 2:1. The total recovery of metals was: Au83.68%, Ag21.84%, Cu68.39%, Zn78.21%, Pb71.22%, and the tailings contained about Au1g/t.

The literature describes the process of recovery of fine-grained gold from pyrite cinder by hydrophobic flocculation flotation. The rational test procedure and the pharmaceutical system are determined by the drug selection test and the influencing factor test. The test results show that hydrophobic flocculation flotation is superior to conventional flotation. The addition of non-polar oil can strengthen the hydrophobic flocculation process, significantly improve the grade and recovery of gold. From the pyrite cinder containing 2.94g/t of gold, the gold content is 126.3g/t and the recovery rate is 51.35%. Gold concentrate.