The aqua regia is used to dissolve sponge platinum,then hydrochloric acid is added to remove nitrate,sodium hydroxide solution is added for complexation,nitric acid is slowly added dropwise to obtain hexahydroxyplatinic acid,and the precipitation is filtered and washed,finally,nitric acid is used to dissolve hexahydroxyplatinic acid to prepare high-purity platinum nitrate solution in this experiment.During this period,conditional experiments are conducted to clarify the optimal conditions for the synthesis and dissolution of hexahydroxyplatinic acid.When the concentration of chloroplatinic acid is 45 g/L,the amount of sodium hydroxide added is 1.8 times the mass of sponge platinum,the endpoint pH of the reaction is 5.5,and the reaction temperature is 80℃,the utilization rate of platinum can exceed 99%,and the synthesis effect of hexahydroxyplatinic acid is the best.When the amount of nitric acid used is 1.3 times the theoretical amount,the dissolution temperature is 50℃,and the dissolution time is 6 h,the dissolution effect of hexahydroxyplatinic acid is the best.After testing,the platinum content in the prepared platinum nitrate solution is 15.86%,and the impurity content meets relevant industry standards.
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