| 摘要 |
PURPOSE:To obtain medium- or low-carbon ferromanganese more economically than by conventional decarburizing processes, by controlling the blow smelting system of molten high-carbon ferromanganese from the former stage of higher decarburizing oxygen efficiency to the latter stage of lower decarburizing oxygen efficiency so as to allow decarburization to proceed smoothly. CONSTITUTION:In the initial stage, an inert gas is bottom-blown into the molten high-carbon ferromanganese usually of about 1,300-1,400 deg.C by >=15pts.vol. based on 100pts.vol. of top-blown O2 gas, by which O2 gas is supplied into vapor phase on the molten-metal surface to subject an exhaust gas to secondary combustion and decarburization is carried out in 60-90% decarburizing oxygen efficiency until the prescribed carbon quantity is reached. Then the molten metal after the above treatment is subjected to bottom-blown blow smelting in which the quantity of bottom-blown inert gas based on 100pts.vol. of bottom- blown O2 gas is regulated to >=20pts.vol. and, with controlling the molten-metal temp. to 1,650-1,800 deg.C, decarburization is carried out until the desired carbon quantity is reached. In this way, decarburization is efficiently exerted until the desired C quantity is reached without adversely affecting the yield of Mn, so that the desired medium- or low-carbon ferromanganese can be obtained.
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