粉煤灰“一步酸溶法”蒸发母液焙烧渣中锂的水浸特性

Water leaching characteristics of lithium from mother liquor roasting slag evaporated by"one-step acid dissolution method"of fly ash

粉煤灰“一步酸溶法”提取氧化铝工艺过程中,蒸发结晶工序析出氯化铝晶体后,蒸发母液中锂的含量高达329 mg/L以上,且经过处理后可进一步浓缩,富集达到2.2 g/L,具有很高的提取价值。研究发现蒸发母液通过焙烧浸出可实现锂的浸出率>80%,而主要元素铝的浸出率非常低,从而将锂和铝分离,最终实现锂的提取。文章分别考察了蒸发母液焙烧渣中的锂在不同条件下的浸出特性,研究结果表明,当焙烧温度400℃、焙烧时间20 min时,使用纯水在浸出温度为80℃、浸出时间2.5 h、液固比为9∶1条件下,锂的浸出率可达到85%,而铝的浸出率近似为0。

In the process of extracting alumina from fly ash by"one-step acid dissolution method",after aluminum chloride crystals are precipitated from evaporative crystallization process,lithium content in evaporated mother liquor is up to 329 mg/L and can be further enriched to 2.2 g/L after treatment,which has high extraction value.The research showed that the leaching rate of lithium can be more than 80%by roasting the evaporated mother liquor,while the leaching rate of main element aluminum is very low,so lithium and aluminum can be separated and finally lithium can be extracted.In this paper,the leaching characteristics of lithium in evaporated mother liquor roasting slag under different conditions were investigated.The research results showed that when roasting temperature was 400℃,roasting time was 20 min,the leaching temperature was 80℃,the leaching time was 2.5 h,the leaching ratio of liquid to solid was 9∶1,the leaching rate of lithium could reach 85%,while the leaching rate of aluminum was approximately 0.