钢渣中钙镁离子的选择性浸出行为

钢渣富含大量的碱性氧化物,是CO₂矿化的潜在廉价原料。以乙酸作为浸出剂,探究了钢渣颗粒粒度、浸出温度、时间、固液比和乙酸浓度对钢渣中主要元素钙、镁、铁、硅溶出行为的影响。试验结果表明钢渣颗粒粒径的降低、乙酸浓度的提高均能有效促进钙、镁离子的浸出,同时也发现延长浸出时间反而会带来铁、硅离子浸出率的降低。在乙酸浓度为1 mol/L、浸出温度为80 ℃、浸出时间为90 min、固液比为1∶20的条件下,能够实现钢渣中钙、镁离子的选择性高效浸出,其最高浸出率达到了92%和52%,而铁离子、硅离子为29.5%和15.9%。浸出渣的物相分析表明经乙酸浸出后滤渣中主要的物相为RO相与磁铁相,这意味着乙酸酸浸不仅能够高效浸出钙、镁,其浸出液能够作为CO₂间接矿化的原料,而且浸出后得到的滤渣中富含含铁相,可以作为优质的炼铁原料。

Selective leaching behaviour of calcium and magnesium from steel slag

Steel slag with high amount of alkaline oxides is potentially raw material for CO₂ mineralization. The effects of slag particle size, leaching temperature, leaching time, solid-liquid ratio and acetic acid concentration on the dissolution behavior of calcium, magnesium, iron, and silicon in steel slag were investigated, and acetic acid was used as extractant. The results showed that the reduction of the particle size of steel slag and the increase of acetic acid concentration could promote the leaching of calcium and magnesium ions effectively. Meanwhile, it was found that increasing the leaching time would lead to a decrease in the leaching rate of iron and silicon ions. Under the conditions of acetic acid concentration of 1 mol/L, leaching temperature of 80 ℃, leaching time of 90 min, and solid-liquid ratio of 1∶20, the selective and efficient leaching of calcium and magnesium ions from steel slag can be achieved, and the maximum leaching rate reached 92% and 52%, respectively, while for iron and silicon ions, it was 29.5% and 15.9%, respectively. The phase analysis of the leaching residue indicated that the main phase was RO phase. It was suggested that the acetic acid leaching not only efficiently extracted calcium and magnesium, and its leaching solution could be used as raw material for carbonation. The filter obtained after leaching was rich in iron-containing phase and can be further recovered as a high-grade ironmaking raw material.