高温二次火法富集粉煤灰中锗的工艺优化

Process Optimization of Germanium Enrichment from Fly Ash by Second Enrichment Process at High Temperature

以含Ge粉煤灰为原料,采用高温二次火法工艺富集粉煤灰中的Ge,重点探究C含量和烧结温度对Ge挥发率的影响,并对其原因进行分析。结果表明,适量的C和适当的烧结温度能促使煤灰中Ge的还原挥发。过量的C会将部分铁氧化物还原为Fe,并与Ge结合形成难挥发的锗酸盐,影响Ge的富集挥发;过高的烧结温度使得C没有充分燃烧生成CO,且部分Ge与CaO、MgO生成复合氧化物,从而降低Ge挥发率。经过前处理的粉煤灰在烧结温度1 700℃、C含量1%、碱度1.0、保温时间1 h的优化条件下,烧结料渣中Ge含量最低,Ge挥发率最高达96.2%。

Using fly ash with germanium as the raw material,the enrichment of Ge from the fly ash was carried out by second enrichment process at high temperature.The effects of C content and sintering temperature on the volatilization rate of Ge were mainly studied,and the reasons were analyzed.The results show that appropriate C content and sintering temperature can promote the reduction and volatilization of Ge in fly ash.Excessive C will reduce part of iron oxides to Fe.And then Fe combines with Ge to form germanate,which is difficult to volatilize,affecting the enrichment and volatilization of Ge.Too high sintering temperature makes C not fully combusted to form CO,and part of Ge combines with CaO and MgO to form composite oxide,which reduces the volatilization rate of Ge.Under the optimum conditions of sintering temperature 1 700 ℃,C content 1%,basicity 1.0 and duration time 1 h,the Ge content of the pretreated fly ash is the lowest and the Ge volatilization rate reaches 96.2%.