VACUUM REFINING METHOD FOR MOLTEN METAL

PURPOSE:To execute vacuum refining of molten metal in a short time by adding solid compound containing gas component to molten metal, reducing the pressure after dissolving gas, generating fine gas bubble in the molten metal and trapping inclusion with this. CONSTITUTION:The gas of N2, etc., which is soluble in molten metal, is dissolved into the molten metal. At the same time of or after dissolving, the pressure is reduced and the fine gas bubbling is generated in the molten metal. The inclusion in the molten metal is trapped with this bubble and removed. In the vacuum refining method of the above molten metal, the solid compound containing the above gas component of e.g. the ferro manganese nitride containing about 6% N, is added to the molten metal to execute the above gas dissolving treatment. As the above adding method, the solid compound is pulverized under pressurizing and by injecting the gas using the soluble gas, etc., the refining can be executed. By this method, the dissolving of gas component is executed in the short time and the efficiency of the above vacuum refining method is improved.