Guizhou Gold Mine Gold Extraction Process

The chemical property of gold is stable, and its anticorrosion is good. It can not be oxidized generally from the normal temperature to the high temperature.Because its physical and mechanical properties are good, it is widely used in many areas.The Carlin-type of gold ore is a kind of self-contained ore and it has a greater long-term.It is introduced the characteristic,metallogenesis of the gold in this thesis, and the process mineralogy of the gold is researched in detail. The grade of this gold is 4.8 g/t.The main compositions of this gold are felspar dolomite,sericite,quartz,pyrite,arsenopyrite and realgar.The gold exists in native gold or isomorphous gold.The isomorphous gold mainly exists in metallic mineral of sulfide as pyrite.The particle size of native gold is finer.The gold in the ore is in close with the pyrite. About 69.6% of the gold distributes in the metallic mineral of sulfide. It belongs to unworkable fine dissemination ore.The methods,technics and research trends of Carlin-type of gold in native and abroad are compared in this thesis. In the light of the gold's characteristic, we decide to adopt cyanidation to recover gold. There are 3 kinds of tests:The crude ore is leached by cyanide directly; The crude ore is roasted firstly, then it is leached by cyanide; The concentrative ore floated is roasted by oxidizing firstly, then it is leached by cyanide. We found the floatation is the best way to concentrate gold ore. But there is a higher content of the sulfur and the arsenic in floated gold ore, which can affect the further leachable test. So oxidizing roasting experiment is used to the flotation concentrates.Na2CO3 is used as pH regulator. Soluble glass and sodium hexametahposphate is used as depressor. Lead nitrate and bluestone is used as activating agent. Xanthate and is used as united collector. The floatation process of once rougher flotation-twice concertration-three times scavenging is adopted.The grade of concertative ore is 38.90g/t. The recovery of the ore is 92.10%.The best parameters of the roasting test are:for the first section,the temperature is 500℃,the period is 90 minutes, the flow of the air mass is 6-9L/min; for the second section, the temperature is 700℃,the period is 90 minutes, the flow of the air mass is 15-20L/min. The grade of the gold can reach 49.5g/t after roasting.Finally, the concertrative ore which is floated and roasted by oxidizing is leached through orthogonal experimental design.The liquid-solid ratio is 3:1.The consumption of NaCN is 7kg/t. The consumption of lime is 20kg/t. The period of leaching is 6 hours and pH is 12. The rate of recovery is 87.10%.