Gas generation specialist Oxymat A/S has successfully commissioned three oxygen (O2) plants in Kazakhstan.
All three plants are located in three different places North East from Astana. The construction has been carried out by the company AAEngineering.
The O2 is being used at gold processing plants. All three processing plants are processing of tailings, which was left back from the previous mining operation. The idea is to extract the remaining gold from tailings in which gold content is limited. Therefore, it is crucial to focus on gold recovery by carefully checking the entire extraction process.
Oxymat’s Area Sales Manager, Mirosla Simovic, explained the process, “Gold leaching with a cyanide solution is widely used in the hydrometallurgical process for extraction of gold from ore or concentrate. Although gold is inert to oxidation in present of water, O2 and cyanide gold is oxidized and dissolved to form of soluble aurocyanide complex. The kinetic of this reaction depends on the dissolved O2 level in the slurry. The next step is adsorption of aurocyanide complex from aqueous solution onto the activated carbon. At the end of the leaching process the carbon with adsorbed gold is removed and stripped from the slurry. The gold is extracted in the electrowinning phase, and finally in the smelter to form gold bullions.”
Each processing plant is equipped with an O2 generating line with capacity 100 m3/hour of O2 at 93% purity. The O2 discharge pressure is at six bar in order to maintain the pressure drop over a long oxygen pipeline to the leaching tanks. All critical parameters are provided to the control room to check the oxygen purity, outlet pressure and status of the air compressor.