钨酸钙球团碳化硅还原试验研究

采用高温炉恒温试验对不同时间、温度及还原剂配比条件下钨酸钙与碳化硅球团还原情况进行研究,结合熔点测试结果分析了球团在升温过程中的物理变化行为,得到各影响因素对球团还原的作用关系及钨直接合金化炼钢工艺的优化条件。结果表明,在1 400～1 500℃时,钨酸钙球团可以被碳化硅还原,还原产物为W、WC、Ca3(Si3O9)及SiO2,球团还原反应可能由固—固、固—液反应共同组成,在升温过程中亦发生碳化硅相变和分解、还原剂的氧化及钨金属的二次氧化;在1 400～1 500℃和10～30min时,低温条件下适当延长反应时间、时间较短条件下适当增加反应温度及适当提高还原剂配比有利于提高球团还原反应率;钨直接合金化电炉炼钢工艺中,采取钨酸钙快速还原,防止钨金属二次氧化措施,可以实现钨酸钙在冶炼早期大部分被还原。

Study on Pellet Reduction of Calcium Tungstate with Carborundum

The reduction of calcium tungstate pellet with carborundum under different reaction time,temperature,and dosage of reductant was studied through constant high temperature test and pellet melting point test.The relationship between the reduction rate and the above factors was analyzed and the optimum parameters of direct alloying steelmaking process were obtained.The results show that the reduction reactions,in solid-solid state or solid-liquid state,can occur at 1 400~1 500 ℃ with the products of W,WC,Ca3(Si3O9) and SiO2.The reactions of carborundum phase transition and decomposition,oxidation of reductant and tungsten also occur in the heating process.At 1 400~1 500 ℃ with the duration of 10~30 min,the reduction rate of the pellet can be improved with longer reaction time at low temperature or shorter time at a high temperature,and with increase in the dosage of reductant.The tungsten direct alloying can be achieved mainly in the early stage of steel making process by calcium tungstate reduce and avoid the oxidation of tungsten.