| 摘要 |
PURPOSE:To obtain easily and rapidly gold of high purity by heating gold recovered from a plating soln. to vaporize metallic thallium contaned in the gold. CONSTITUTION:Gold recovered from a spent gold plating soln. or a gold electroplated article is heated at >400 deg.C for a prescribed time to vaporize thallium contaned in the gold. Simple metallic thallium vaporizes at about 174 deg.C, yet it vaporizes hardly at <=400 deg.C in practice and vaporizes remarkably at >400 deg.C. Accordingly, the heating temp. is regulated to 800-900 deg.C at which gold is not melted and solidified. By this method the number of treating stages is reduced, the cost can be reduced, and gold of high purity can be rapidly obtd.
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