Bacterial Oxidation Of Refractory Gold Ore And Purification Of Gold Extraction

At present, a third of gold resources are the refractory gold ores. The advantages of bacterial oxidation to deal with the refractory gold ores include economy, efficiency, security and environmental protection. But the arsenic-bearing, cyanide-bearing and thiocyanate-bearing wastewater is produced in the process of bacterial oxidation and gold extraction. The effluent liquor pollutes the environment and rework solution to affect normal operation of process. The paper is focused on purification of arsenic-bearing and thiocyanate-bearing wastewater produced in the process of bacterial oxidation-gold extraction and provides theoretical reference for the application.In the paper, the following methods are used to deal with the acidic arsenic-bearing and thiocyanate-bearing wastewater, including lime method, lime-aluminum salt method, arsenic-iron coprecipitation method, sodium sulfide method, hydrogen peroxide method, acidification method, alkaline-chlorine method and sodium meta-bisulphite/air method. The two processes are compared to learn the influencing factors and their rules. The bacterial tolerance concentration for thiocyanate is determined to optimize the process and meet the cycle.The results show that the bacterial oxidation-gold extraction increase the gold extracting rate of high sulfur arsenic bearing and carbon bearing gold concentrate by78.26%from13.09%which proves biooxidation pretreatment oxidizes the sulfide in the ores availably. The lime-aluminum salt method and arsenic-iron coprecipitation method meet the national effluent standards when deal with the arsenic-bearing and iron-bearing biooxidation liquid waste. The results of removing arsenic and iron by lime-aluminum salt method are better than the arsenic-iron coprecipitation and sodium sulfide precipitation method, but the neutralized residue mass is outclassed, six times, from the latter which means heavy burden on landfill disposal. In the experiments of thiocyanate-bearing wastewater, the bacteria grow normally under0.05g/L thiocyanate. The hydrogen peroxide method and alkaline-chlorine process remove the thiocyanate ion under the concentration, but the traditional acidification method and sodium meta-bisulphite/air method doesn’t achieve the point.