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The common gold extraction processes include gravity separation process, froth flotation process, cyanidation, etc. Froth flotation process is the most widely used in gold extraction, but for different types of gold, we can choose flotation process combined processin order to improve the return on investment.
The combined process between froth flotation process and other processes can usually achieve impressive results for different types of gold ore. Here are several combined process used for gold extraction according to different ore properties:
This method is most commonly used for gold-containing quartz dike. Generally, the xanthate is used as the collector, and the terpenic oil is used as the foaming agent, the gold concentrate is obtained from the weakly alkaline pulp in flotation machine. The flotation concentrate is then sent to cyanaide and leaching, the gold is dissolved by the cyanide, the complex enters the solution, and then the gold mud is obtained by the zinc powder replacement device, and finally the gold mud is smelted to get pure gold.
For vein gold ore with high arsenic and sulfur or high carbon argillaceous, the gold sulfide concentrate can be obtained by the froth flotation, and then the flotation concentrate can be recovered by the thiourea leaching process. Thiourea gold extraction is a kind of increasingly sophisticated gold extraction method with low toxicity. Thiourea acid solution has the fast gold and silver dissolving speed, low toxicity, and east-to-regenerate. The mineral components, such as antimony, arsenic, copper, sulfur, are not sensitive to thiourea gold extraction, but can affect cyanidation gold extraction. Therefore, thiourea leaching process can be use to extract the gold and silver from the gold-bearing mineral that is difficult to treat with cyanidation process. At the same time, the time of thiourea gold leaching process is generally much shorter than that of cyanide gold leaching.
Amalgamation method is often used to extract the oxidized gold ore with coarse nature gold particle and close to the earth’s surface, or the quartziferous primary ore. The size of gold particles is an important factor in the gold extraction of amalgamation method. The particle size is suitable for the amalgamation method is 0.2~0.03 mm. The amalgamation process is featured with simple operation, low cost and quick effect. For the non-ferrous ore containing gold mines, the amalgamation method can be used when the character of free gold is good, the quantity of free gold is enough and without the impurities that are harmful to mercury.
For the flotation concentrate containing high arsenic sulfide, the cyanide tailings are enriched in the concentrate by the impurities (sulfur, iron, arsenic) after the flotation, then become the refractory concentrate with high sulfur and high arsenic, which cannot be sent to cyanide leaching directly. Therefore, the flotation concentrate can be firstly sent to oxidizing roasting for removing the arsenic and sulfur. By this way, the structure of roasting calcine after the roasting is loose, which is conductive to the gold and silver leaching. After that, adopting the high acid pretreatment washing, most impurities are dissolve by the acid, then removed by washing, thus guaranteeing the cyanidation leaching rate, and effectively enriching the gold grade.
In order to reasonably separate gold ore, it is very important to choose the right gold extraction process. First, we should comprehensive analyze the nature of the gold ore, look for the mineral processing enterprise who is qualified with mineral processing test to conclude the scientific mineral processing test report, thus judging what kind of gold extraction process should be selected and achieving the ideal investment returns.