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s <br /> solution to remove calcium carbonate scale and other impurities. In <br /> the second step the gold is removed from the carbon using the Zadra <br /> elution procedure. Elution or desorption is accomplished by <br /> contacting the carbon with a caustic/cyanide solution at elevated <br /> temperatures. The vessel is operated under pressure to ensure the <br /> desired temperatures. The desorption vessel is operated in closed- <br /> circuit with the electrowinning cell . The final step in this process <br /> is to reactivate or regenerate the carbon by passing the carbon <br /> through a kiln. The regenerated carbon is returned to the adsorption <br /> circuit. <br /> The gold will be plated from the desorption solution or <br /> electrolyte by electrowinning. Electrowinning is an electrolysis <br /> procedure that utilizes an insoluble anode. Stainless steel anodes <br /> and steel wool cathodes will be used. The gold is plated onto the <br /> steel wool cathode. The steel wool cathodes are removed periodically <br /> and smelted in a dore furnace. The iron and other impurities are <br /> slagged off and a dore bar containing the precious metals is poured. <br /> The sl urry wi 11 be removed from the 1 each tanks for treatment. <br /> Treatment will use sulfuric acid to lower solution pH levels to below <br /> 9.0 to promote precipitation of some of the salt and metal levels <br /> and to allow liberation and volatilization of the cyanide. The <br /> relationship between cyanide and pH is shown on the enclosed Figure <br /> D.5-1. As shown on this figure, approximately 70% of the cyanide can <br /> be volatilized by pH control . The reactions will be initiated in an <br /> agitated vessel . The pH level will be measured during the treatment <br /> process to ensure that the proposed pH levels are achieved prior to <br /> disposal . ,Additional volatization will occur as a result of the <br /> proposed thin layer disposal method and the exposure of the beach <br /> area to ultraviolet light for a period of time until the next layer <br /> is deposited. <br /> The mill design will include an internal curbing and collection <br /> system within the mill to ensure that in the event of a tank rupture <br /> or leak all solutions are collected and contained within the mill . <br /> D=16 7100875 <br />