高铝熔渣物相析出演变规律研究

Study on Evolution of Phase Precipitation in High Aluminum Slags

以改善高铝渣浸出性能为目标,采用DSC实验和SEM-EDS检测方法,研究了高铝渣控温冷却过程中物相析出规律,考察了降温速率、n(CaO)/n(Al_2O_3)和MgO含量对铝酸钙渣物相析出演变规律的影响.结果表明:当降温速率加快时,熔渣凝固过程趋于更大程度的偏析,C_2 S相变愈不充分,粒度粗化,劣化了自粉行为和浸出条件;随着调高渣中n(CaO)/n(Al_2O_3),C12A7的析出温度升高,物相析出活性按照CA→C12A7→C3A逐渐增强;当渣中含有MgO时,物相中出现C_2MS_2,不利于C_2 S物相转变,更为重要的是MgO富集在含铝物相中形成Q相。

To improve the leaching performance of high alumina slags,DSC and SEM-EDS analyses were employed to study the phase precipitation behaviors of high alumina slags during solidification with controlled cooling rates. The effects of cooling rate,n（ CaO）/n（ Al2 O3） and MgO content on the evolution of phase precipitation were discussed. The results show that when the cooling rate increases,the solidification process tends to have severer segregation,the C2 S phase transformation becomes more insufficient and the particle turns obviously coarse,so that the self-pulverization and leaching performance deteriorate. With the increase of n（ CaO）/n（ Al2 O3）in the slags,the precipitation temperature of C12 A7 rises and the activities of precipitation phases increase gradually as CA→C12 A7→C3 A. When the slags contains MgO,the phase of C2 MS2 appears,which is detrimental to the phase transition of C2 S. More importantly,MgO enriching in aluminum-bearing phase leads to the formation of Q phase,which deteriorates greatly the leaching and recovery rate of alumina.