钒钛磁铁矿煤球团还原过程挥发分的作用

为研究钒钛磁铁矿-煤球团还原过程中挥发分作用,开展了N2气氛下分层试样与两类球团非等温热重还原实验。试样的还原度由失重测定。结果发现,煤粉中的挥发分于400℃左右开始挥发。钒钛磁铁矿-非焦煤球团还原过程非常复杂,可分为四个阶段:挥发分挥发产生CO、H2还原球团、挥发分挥发的CO、H2及其碳氢化合物分解产生的C、H2与固体C共同作用还原球团、C经由气化反应媒介作用还原球团、C直接还原球团。挥发分的挥发能提高球团的气孔率和还原性,但影响较小。分析表明,在四个还原阶段中,C的直接还原作用对球团的还原影响最强,球团的还原度提高率可达0.1748%·℃-1。

添加CaO对钒钛磁铁矿煤球团还原的影响

为改善钒钛磁铁矿煤球团还原条件,提高其还原性,提出将CaO添加入钒钛磁铁矿煤球团中。采用回归正交法设计实验,考察配碳量、温度、CaO添加量等因素对钒钛磁铁矿煤球团还原的影响。在900℃、945℃、1100℃、1255.4℃、1300℃下球团置于电阻炉内定温还原30min,实验结果发现,球团的还原度、金属化率可达90%以上。统计分析表明:温度、配碳量对钒钛磁铁矿煤球团的还原度、金属化率均有显著的影响,其中温度影响最重要;添加少量的CaO能增加钒钛磁铁矿煤球团的气孔率,提高球团的还原性,但影响较小。

Effect of B2O3 addition on oxidation induration and reduction swelling behavior of chromium-bearing vanadium titanomagnetite pellets with simulated coke oven gas

The oxidation induration and reduction swelling behavior of the chromium-bearing vanadium titanomagnetite pellets (CVTP) with B2O3 addition were investigated. Besides, the reduction swelling index (RSI) and compressive strength (CS) of the reduced CVTP were also examined using the simulated coke oven gas (COG). The results suggested that the CS of CVTP was increased from 2448 to 3819.2 N, while the porosity of CVTP was decreased from 14.86% to 10.03% with the increase in B2O3 addition amounts. Moreover, the B2O3 mainly existed in the forms of TiB0.024O2 and Fe3BO5 in both CVTP and the reduced CVTP. Specifically, the CS of the reduced CVTP was elevated from 901 to 956.2 N, while the RSI was reduced from 5.87% to 3.81% as the B2O3 addition amounts were increased. Taken together, B2O3 addition would facilitate the aggregation and diffusion of metallic iron particles, which contributed to reducing the formation of metal iron whiskers and weakening the reduction swelling behavior.