METHOD OF PREPARING FERROMOLYBDENUM ALLOY BRIQUETTE FROM A POWDER MIXTURE OF MILL SCALE AND MOLYBDENUM OXIDE POWDER THROUGH A SOLID-GAS REACTION, AND BRIQUETTE PREPARED BY THE METHOD

摘要

The present invention relates to a method for preparing a ferromolybdenum alloy briquette, wherein the ferromolybdenum alloy is used for adjusting ingredients of a melt in a steelmaking process for manufacturing special steel. More particularly, the present invention relates to a method for preparing a ferromolybdenum alloy briquette, and a briquette prepared by the method, wherein the ferromolybdenum alloy briquette is obtained by: mixing mill scale (mixture of Fe, FeO, and Fe₂O₃) powders discharged from a steel forging process as an iron raw material, and molybdenum oxide (MoO₃) powders as a molybdenum raw material; reducing this mixture in a powdery state using a hydrogen gas; mixing the prepared ferromolybdenum alloy powders and wax and press-molding the resulting mixture; sintering the press-molded mixture at a high temperature in a hydrogen gas atmosphere; and then cooling down the sintered mixture to prepare ferromolybdenum alloy in a briquette form. The method for preparing a ferromolybdenum alloy briquette, according to the present invention, is characterized by comprising the steps of: crushing mill scale (mixture of Fe, FeO, and Fe₂O₃) into a size ranging from 75 μm to 150 μm and simultaneously mixing powdery mill scale (mixture of Fe, FeO, and Fe₂O₃) and molybdenum oxide (MoO₃) powders uniformly; partially reducing the resulting mixture using a hydrogen gas by primarily raising a temperature to a low temperature in a powdery state; completely reducing the resulting mixture using a hydrogen gas by secondarily raising a temperature to a high temperature in a powdery state; cooling down the reduced powder mixture to a low temperature; mixing the prepared ferromolybdenum alloy powders and wax to press-mold the resulting mixture; and cooling down the press-molded mixture after performing heat treatment in a hydrogen gas atmosphere. According to the present invention, the mill scale (mixture of Fe, FeO, and Fe₂O₃) powders, which are industrial by-products, and molybdenum oxide (MoO₃) powders are mixed, and the resulting mixture is reduced in a powdery state through two-stage reduction using a hydrogen gas to thereby form ferromolybdenum alloy powders. Therefore, a reduction rate is faster than that in the case where reduction is performed in a briquette state using hydrogen gas. This reduces the operating temperature, thereby reducing the operating time as well as the volatilized loss of molybdenum oxide. Further, the volatilized loss of molybdenum oxide can be less than a case in which hydrogen reduction is performed in a molten state, and it is unnecessary to use a solid heat source such as aluminum, magnesium and ferrosilicon which are used in a thermite process and for supplementary input, a reducing agent, a slag forming agent such as lime and silica, a colorant, and molding sand. Also, the uniformity in the quality of ferromolybdenum alloy can be maintained, and dust and slag which are secondary environmental pollutants are not generated, thereby reducing investment costs for environment pollutant control equipment. In addition, the present invention has an advantage in reducing material costs by using the mill scale (mixture of Fe, FeO, and Fe₂O₃) powders, which are industrial by-products, as an iron raw material instead of iron powders or scrap iron. Moreover, the present invention provides a green technology capable of adding more value to the wasted mill scale (mixture of Fe, FeO, and Fe₂O₃) from steelmaking processes, thus enabling industrial by-products to be recycled.