China Nonferrous Metallurgy

An enterprise used ammonium chloroplatinate as raw material to refine platinum by hydrazine hydrate reduction-chlorination leaching of crude platinum-platinum precipitation with ammonium chloride. Under the original leaching parameters, the leaching rate of platinum was less than 70%, resulting in low direct yield of platinum. In this paper, the effects of reaction temperature, sodium chlorate dosage and hydrochloric acid concentration on the leaching rate of platinum were investigated. The production practice was carried out and the following conclusions were obtained. Under the experimental conditions of reaction temperature 90℃, sodium chlorate dosage 22% of the weight of crude platinum powder, hydrochloric acid concentration 3.0mol/L, stirring speed 450r/min, liquid-solid ratio 6∶1 and reaction time 4h, the leaching rate of platinum can reach 92.5% by adding sodium chlorate slowly. The production practice shows that the leaching effect is good and stable under the experimental conditions. The platinum leaching rate is maintained at about 92%, which is much higher than the platinum leaching rate of 70% under the original process conditions. The process optimization effect is good. The reaction kettle tank and stirring device used in the process are all titanium materials. The waste gas and wastewater produced enter the gold refining waste gas and wastewater treatment system, and are discharged after reaching the standard.