Abstract：The free calcium oxide in the calcium-based desulfurizer for hot metal pretreatment in steelmaking was easily converted into calcium hydroxide because of the high hydroscopic property. In the process of pre-desulfurization and feeding, calcium hydroxide would undergo a violent decomposition reaction, resulting in spattering of hot metal and reduction of hot metal temperature, which was not conducive to the control of desulfurization cost. Therefore, the accurate determination of calcium hydroxide in desulfurizer had great significance for desulfurization process. The calcium-based desulfurizer sample for hot metal pretreatment in steelmaking that was placed before and after one month was analyzed by X-ray diffraction. The results showed that, when the content of free calcium oxide was not less than 55%, there was no free water and bound water in desulfurizer, and the water existed only in the form of constitution water of calcium hydroxide. Calcium hydroxide was easily decomposed into calcium oxide and water under high temperature. Taking advantage of this characteristic, the content of calcium hydroxide could be indirectly obtained with conversion from the mass difference of water loss before and after decomposition, which was determined by burning gravimetric method. Thus, the determination of calcium hydroxide content in calcium-based desulfurizer for hot metal pretreatment in steelmaking was realized. The results indicated that, The relative standard deviation (RSD) was least with the particle size not larger than 125 μm and the sample mass of 1.00 g. In burning temperature test, the platinum crucible was used as the burning container and the sample was rapidly weighed by subtraction method. It was found that the calcium hydroxide could be decomposed completely after burning at 580 ℃ for 1.0-1.5 h. Moreover, calcium carbonate and other components in the desulfurizer had no influence on the determination. The proposed method was applied to analyze the calcium-based desulfurizer samples for hot metal pretreatment in steelmaking. The relative standard deviations (n=6) were between 1.1% and 2.0%. The results were basically consistent with those obtained by thermogravimetric analysis method. The recoveries were between 96% and 104%.
朱春要, 陆娜萍, 赵希文, 董登超. 灼烧重量法测定炼钢铁水预处理用钙基脱硫剂中氢氧化钙[J]. 冶金分析, 2021, 41(6): 44-50.
ZHU Chunyao, LU Naping, ZHAO Xiwen, DONG Dengchao. Determination of calcium hydroxide in calcium-based desulfurizer for hot metal pretreatment in steelmaking by burning gravimetric method. , 2021, 41(6): 44-50.
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