采用热重等温实验研究了970~1150℃内CaS的氧化反应特性,利用红外光谱仪定量分析反应析出SO2气体,通过亚甲基蓝分光光度法测定固体残留物中CaS的含量.实验研究发现,在970~1150℃内,反应呈先失重后增重趋势,固体残留物中都检测出少量CaS的存在.随温度升高,残留固体样品中CaSO4的质量百分比下降,而CaO的质量百分比上升,SO2析出速率急剧增大,1150℃下SO2的析出速率比970℃下的析出速率高了一个数量级.随O2浓度增大,残留固体样品中CaSO4的质量百分比和SO2析出速率轻微上升.降低反应温度和增大O2浓度,有利于提高CaS氧化生成CaSO4的比例.
The oxidation of CaS was studied in the temperature range of 970--1150℃ under O2 atmosphere with different O2 concentrations. Experiments were carried out by a Metteler Toledo TGA instrument under isothermal condition and the exhausted gas was analyzed by the infrared spectral method. The mass fraction of CaS in final decomposition product was analyzed by spectrophotometric measurement with ethylene blue. During the reaction, the samples lose weight at first, and then followed by a rapid mass gain. A little amount of CaS was detected in the residue. CaS is oxidized to form CaSO4 at low temperature and to form CaO at high temperature chiefly, and the release rate of SO2 leaps with the temperature increase, such as the rate at 1150℃ is ten times of that at 970℃. The mass fraction of CaSO4 and the SO2 release rate increase gently with the increase of O2 concentration. Conversion of CaS to CaSO4 increases with temperature decreasing and with increasing O2 concentration.