Gold ore mainly refers the mineral which has gold content and exploitation value. According to gold structure and content in the ore, gold ore can be classified into gold mineral, gold bearing mineral and gold carrier mineral.
Currently, the main gold beneficiation is normally that after crushing by crusher and grinding by ball grinder, gravity separation and floatation or chemical method shall be adopted to extract concentrate and tailings, and then through smelting, and the mineral shall become the finished gold.
Gravity separation and floatation are the most common ways adopted in gold ore beneficiation. The operators of domestic gold mines adopt the above two methods to extract gold and have improved a lot in the beneficiation technology and equipment.
Gravity separation is a method to separate ore based on different mineral densities and occupies an important place in modern mineral separation. The main facilities adopted are sluice, shaking table, jigger and short cone hydro-cyclone etc.
Floatation is one of the most widely used methods to treat vein gold ore in gold beneficiation plants. In most cases, flotation is used to deal with sulfur gold-bearing mineral with high floatability and has obvious effect. This is because the gold can be gathered into the sulfur concentrate to the maximum extent through flotation and the tailings can be deserted. The beneficiation cost is very low. Flotation process is also used to handle the polymetallic gold-bearing ore such as gold-copper, gold-lead, gold-copper-lead zinc-sulfur etc. Certainly, the floatation has limitation. When the ore has coarse grain dissemination and the gold granularity is larger than 0.2mm, or when the ore is quartziferous gold-bearing mineral without sulfide, it is unsuitable to use floatation.
Gold separation by chemistry
The current chemical separation methods are mainly amalgamation and cyanidation to extract gold. The amalgamation gold extraction process is an ancient gold-extraction technology which is simple, economic and suitable for collection of coarse grained monomer gold, but it causes too much pollution to the environment, and has been gradually replaced by gravity separation, floatation and cyanidation gold-extraction process. The cyanidation gold-extraction process consists of: cyanidation leaching, washing and filtering of leached ore pulp, gold extraction from cyanide solutions or cyanidation ore pulp, and smelting of finished product which are the basic procedures.
Low grade of oxidized ore takes a certain proportion in the gold ore resources. It is uneconomical to treat this kind of ores by conventional cyanidation gold-extraction process but economical to use heap leaching production process. In heap leaching, the gold-bearing ores are actually placed on the impermeable ground to be permeated and leached with cyanide solutions. When the gold and silver in the ore dissolve, they will flow into the storage pool along the designed trenches on the ground. This liquid containing gold and silver shall be then absorbed by active carbon and then desorbed to retrieve gold and silver.