| 摘要 |
PROBLEM TO BE SOLVED: To obtain a purification process for impure diamond which can safely and efficiently remove the contaminants in diamond through the markedly simplified operation compared to the earliar process by using a specific solvent. SOLUTION: Crude diamond powder contaminated with at least one selected from metals, metal oxides, metal carbides, non-diamond carbon and hexagonal diamond is soaked in a molten salt containing an alkali metal oxide-SO3 -H2 O system to convert the contaminants to substances soluble in the molten salt (soluble in water) or gaseous or vapor substances at an ambient temperature thereby separating and removing the contaminants from the diamond powder. This soaking treatment can select a high temperature condition of >=350 deg.C and the temperature limit is 800 deg.C. The molten salt is constituted so that it may contains a mixture of at least one selected from an alkali metal sulfate, particularly potassium sulfate and sodium sulfate with concentrated sulfuric acid or a substance that can generate sulfuric acid under the environment in which the substance is used. |
