Flotation is the main beneficiation method for various rock gold ores. It is used to treat poor sulfide gold ore, high sulfide gold ore and associated polymetallic gold bearing ore, and can effectively separate various gold bearing sulfide concentrates. In general, the preferential flotation process is adopted, that is, the direct flotation of the gold bearing sulfide ore is carried out. After the qualified flotation gold concentrate is obtained through one roughing and several cleaning and scavenging processes, the subsequent recovery process is carried out.
Flotation is conducive to the comprehensive recovery of mineral resources. For the refractory gold and silver ores that are difficult to be directly mixed with mercury and cyanidated, the combined process of beneficiation and metallurgy is required, and flotation is an indispensable method.
The selection of flotation process flow is usually determined according to the properties of gold and silver ores and product specifications. The common principle process flow is as follows.
A small amount of concentrate is obtained from the sulfide ore containing gold and silver ore quartz vein through flotation, and then cyanidation is carried out. Compared with the whole slime cyanidation process, the flotation concentrate cyanidation process has the advantages of not requiring fine grinding of all ores, saving power consumption, small plant area, and saving capital investment.
For the vein gold ore with high arsenic and sulfur content or high carbon and argillaceous content, the flotation method can be used to obtain the gold containing sulfide concentrate, and then the flotation concentrate is leached with thiourea to recover gold. The thiourea leaching not only has the advantages of fast leaching speed, low toxicity, simple process and convenient operation, but also has the characteristics of high leaching rate, low reagent and material consumption when processing the gold concentrate with high arsenic and sulfur content or high carbon and argillaceous content.
This process is often used to treat refractory gold arsenic ore, gold antimony ore and gold pyrite with extremely high sulfide content. The purpose of roasting is to remove arsenic, antimony and other elements harmful to the cyanidation process.
This method is applicable to vein gold deposits with uneven coarse and fine distribution. In the grinding circuit, coarse-grained gold is recovered by mercury mixing method, and then fine-grained gold is recovered by flotation method. The ore processed by longhui gold mine belongs to gold bearing quartz vein ore of poor sulfide arsenopyrite type. The natural gold is unevenly embedded in the ore, most of which exists in the boundaries and fissures of other minerals, and a small amount in arsenopyrite and sulfide.
The gold bearing iron oxide cap ore in a certain place is deeply weathered, most of the minerals are eroded, the iron pollution is serious, and there are many secondary minerals. The main metal minerals are limonite, manganese minerals, secondary vanadium copper lead ore, hematite, copper blue, cinnabar and natural copper. The gold ore is natural gold, gold and silver ore, and the gangue is clay mineral and quartz. The particle size of natural gold in the ore is fine to -0.02mm, and it is mostly embedded in clay minerals. The limonite contains more than 10g / T of gold, and the gold grade of the raw ore is 10-14g / T.
Most polymetallic sulfide ores containing gold and silver are treated by this method. During flotation, the gold and silver enter the copper, lead and other gold deposits closely associated with them, and then they are sent to the smelter to recover the gold and silver.
This scheme is used to treat quartz sulfide ore containing tellurite, pyrrhotite, chalcopyrite and other sulfide ores. The sulfide ore can be floated from the ore as concentrate, and then the gold and silver in the exposed sulfide ore are roasted and cyanidated. Since the gold and silver content of the medium and tailings after flotation is generally high, cyanidation is required for recovery.
When the gold and silver coexisting with sulfide in the ore cannot be completely recovered by cyanidation, the recovery rate of gold and silver can be improved by re flotation of the cyanide residue.
