•Entering leaching tank via hollow shaft, air is agitated and dispersed by rotation of impellers.
•The two new type impellers with large diameter, low speed and low power consumption, which can reduce the wear of carbon
•The moderate stirring intensity, pulp concentration and fineness distributes consistently can improve the adsorption rate and import rate.
With dual impellers rotating and agitating, ore pulps move downward and then diffuse along damping plate. Air is fed in tank from the lower end of shaft, and blended with ore pulps to form uniform suspending mixed liquid.
In the gold cyaniding process, leaching agitation tank is applied to leach and carbon-absorb ore pulps whose fineness is -200 meshes and whose density is less than 45%. Under similar circumstance, it is also applied to agitation and leaching in metallurgy, chemical and light industry.
Leaching Agitation Tank, which is widely use in Cyanidation processes may include the following operations:
1. Agitated tank leaching
2. Heap leaching
3. Carbon adsorption recovery
4. Zinc precipitation recovery
Cyanide leaching is the standard method used for recovering most of the gold
throughout the world today. The process originated around 1890 and quickly
replaced all competing technologies. The reason was strictly economical in
nature. Where amalgamation plants could recover about 60% of the gold present,
cyanide could recover about 90%. Because of the improved recovery, many of
the old tailings piles from other processes have been economically reprocessed
by cyanide leaching. Cyanide is as close to a “universal solvent” for gold
as has been developed. Other leaching reagents will only work on very specific
types of ore.
The standard cyanide leach process consists of grinding the ore to about
80% – 200 mesh, mixing the ore/water grinding slurry with about 2 pounds
per ton of sodium cyanide and enough quick lime to keep the pH of the solution
at about 11.0. At a slurry concentration of 50% solids, the slurry passes
through a series of agitated mixing tanks with a residence time of 24 hours.
The gold bearing liquid is then separated from the leached solids in thickener
tanks or vacuum filters, and the tailings are washed to remove gold and cyanide
prior to disposal. The separation and washing take place in a series of units
by a process referred to as counter current decantation (CCD). Gold is then
recovered from the pregnant solution by zinc precipitation and the solution
is recycled for reuse in leaching and grinding.