PURPOSE: To obtain electro-melted magnesia single crystal having large particle diameter in high yield by specifying the electrode diameter, the diameter of the circle passing through the electrodes and an operation parameter to adjust the operation voltage in the melting of magnesia clinker in an electric furnace having embedded electrodes. ;CONSTITUTION: Magnesia clinker is melted in an electric furnace having embedded electrodes while keeping the operation parameter α defined by formula (1) to 10-40. The optimum operation parameter α can be achieved by placing electrodes 2 in such a manner as to contact the melting zones 3 of the electrodes with each other, determining the diameter Dp of the circle passing through the electrodes and setting the operation voltage V to a proper level. The electrodes are inserted to the part near the bottom of the furnace and the electrification of the furnace is started to form a layer of a molten material under the electrodes. The electrodes are gradually pulled upward until the clinker is melted to a prescribed height. The formed electro-melted magnesia is solidified in the furnace and the single crystal parts are separated from the magnesia taken out of the furnace.;COPYRIGHT: (C)1993,JPO&Japio
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