电石渣-赤泥混合烧结过程有害气体释放特性

Release characteristics of harmful gases during sintering mixed carbide slag and red mud

为研究电石渣-赤泥混合烧结回收氧化铝过程中所产生的气态污染,采用Fact Sage7.1热化学数据库和电石渣实测数据模拟计算了体系升温过程中有害组S,F,P的迁移转化过程及气相产物。结果表明:升温过程中S元素主要以固相CaS形态存在;温度达到925℃时,体系中的F以气态HF的形式开始释放,但大量F仍以固体11CaO·7Al_2O_3·CaF_2形态存在;1 175℃时,含P固体Ca_5(PO_4)_3(OH)全部转化为固相Fe3P和少量含P气态污染物(PH_3,P_2),且PH_3释放量随温度的升高而增大;整个温度区间内(75—1 250℃),S,F,P未形成液态渣相。

In order to investigate the gaseous pollutions during alumina recovery by sintering mixed carbide slag and red mud,the composition of carbide slag was measured. The migration,transformation and gas phase products of the S-,F-,and P-containing species in the heating system were calculated by Fact Sage 7. 1 thermo-chemical software and databases. The results show that S mainly exists as solid phase of CaS. At calcination temperature of925 ℃,the gaseous HF start to appear,while a large amount of F remains in the solid phase of 11 CaO·7 Al2O3·CaF2. The P in the solid of Ca5（PO4）3（OH） is transformed to solid of Fe3 P and a small amount of P-containing gas phase products（PH3 and P2） when the temperature reached 1 175 ℃. The release amounts of PH3 increase with the increase of temperature. S,F,and P cannot be changed into slag phase in the entire temperature region（75-1 250 ℃）.