research status of refractory gold ore leaching
With the continuous exploitation of gold ore, the development trend of world gold in general is rich ore, easy to deal with the mine is increasingly reduced and depleted, complex ore, refractory ore has become the main production of gold resources. In China, in the proven gold reserves, about 1/3 of the refractory gold resources.
Refractory gold ore is rich in carbon, sulfur, arsenic and other impurities, in the conventional leaching conditions, the gold recovery rate is not high gold ore. Often the cyanide leaching ore leaching rate of less than 80% of the gold ore is called refractory gold ore, the typical refractory ore direct cyanide leaching rate of only 10% -30%. This type of gold ore refractory main reason is arsenopyrite, pyrite and other sulfides of gold formed a package, hindering the gold and cyanide direct contact. At the same time part of the ore also contains activated carbon type organic carbon, leaching gold, the cyanide complex was organic carbon from the solution “hijacking”, leading to direct cyanidation of gold leaching rate is very low.
Difficult to choose the essence of metallurgical ore pretreatment is to open the inclusions so that gold particles exposed to contact with the leaching agent. The purpose is to: ① open the sulfide inclusions, so that the formation of porous gold ore, cyanide solution is conducive to maximum contact with gold particles; ② remove arsenic, sulfur, organic carbon and other harmful impurities hinder cyanide leaching gold and change Its physical and chemical properties; ③ difficult to leaching of gold telluride ore into easily leaching ore. At present, the main pretreatment methods of cyanide leaching gold method are roasting oxidation, hot pressing oxidation, biological oxidation and chemical oxidation. As for the difficulty of selecting metallurgical ore non-cyanide leaching method of halogenated, thiourea, thiosulfate, polysulfide and so on.
The roasting oxidation method is one of the most important methods for pretreatment of refractory gold ore. The main principle is that the gold-coated sulfide minerals are decomposed into porous oxides by high-temperature inflation so as to achieve the goal of exposing the gold particles in the ore. Roasting method is a mature pretreatment method, as the pretreatment of refractory ore has been applied for decades. The method has the advantages of reliable technology, simple maintenance and strong adaptability, and is particularly applicable to refractory ores with both gold-coated sulphide and carbon material.
However, due to the traditional roasting will release a lot of SO2, As2O3 and other harmful gases, pollute the environment, so its application is limited. In the past few years, the roasting technology is still in continuous development, in the process of research and development of oxygen-rich roasting and curing roasting of new technology; in the roasting equipment, mainly in Germany Lurgi-type circulating fluidized bed furnace and Sweden Bo Li closed vacuum system in gold The successful application.