| 摘要 |
<p>PURPOSE:To eliminate the need for regulation of quality level of gold-silver alloy by using the same as an anode and performing electrolysis in an electrolyte of iodine compound and extracting the cathodic deposit by acid having oxidizability and separating the gold-silver alloy into gold and silver. CONSTITUTION:Gold-silver alloy is redeposited on a cathode and made to fine particles by using this gold-silver alloy as an anode and performing electrolysis in an electrolyte of iodide. When iodine compound is user for the electrolyte, the particles are made fine and toxicity is nearly absent and both platinum and palladium are deposited. The cathodic deposit is treated by nitric acid to extract silver and gold is separated as residue. Silver in the extracted liquid of nitric acid is separated as silver chloride. The residual liquid is neutralized and both platinum and palladium are obtained by using a reudcing agent such as sodium boron hydride. Further as the other method, aqua regia is added to the cathodic deposit to dissolve gold. Silver is separated as silver chloride and gold in aqua regia is recovered as metallic gold by the reducing agent. The need for regulation of quality level of gold-silver alloy is eliminated and both gold and silver are easily separated without generation of nitrogen oxide.</p> |
