| 摘要 |
PURPOSE:To manufacture high-purity gold for semiconductor use from which V and Th are removed, by extracting gold with methyl isobutyl ketone from the solution of high-purity gold metal, by washing the resulting extract, by mixing a back-extracted solvent containing reducing agent with the above extract, and then by heating the resulting mixture so as to carry out the reduc ing refining of gold. CONSTITUTION:A high-purity gold metal of >=99.99% purity containing V and Th by several ppb is dissolved in aqua regia (m), and the resulting solution (m') is mixed with methyl isobutyl ketone M, which is agitated to undergo extraction separation of gold A'. After the extract M is washed with a wash solution (n) (dilute hydrochloric acid, etc.) several times, a back-extracted solvent O in which a reducing agent such as hydrazine hydrochloride is dissolved is mixed with the above extractant M, and the resulting mixture is heated so as to evaporate methyl isobutyl ketone M and water and reduce the gold A' in the back-extracted solvent O. By this method, the high-purity gold for semicon ductor use in which V and Th content is regulated to <=about 0.1ppb and the counts of radioactive alpha-grains are below the detection limit can be obtained. |
