煤矸石和赤泥协同提取氧化铝过程矿相转变研究

开展了煤矸石和赤泥协同提取氧化铝研究，考察了添加赤泥对煤矸石活化提取氧化铝及对助剂碳酸钠消耗量的影响，并利用TG-DSC和XRD研究了赤泥添加对煤矸石活化过程的影响。结果表明，“煤矸石-赤泥-Na₂CO₃”混合样中氧化铝的溶出率随Na/Al摩尔比和煅烧温度的增加而增加，在Al/Si摩尔比为1的条件下，当Na/Al摩尔比为1.2、煅烧温度为850℃时，混合样的氧化铝溶出率可达到91.7%，与碳酸钠直接活化煤矸石相比，碳酸钠消耗量可降低77.9%。TG-DSC和XRD的结果表明，煤矸石、赤泥以及碳酸钠在低于700℃时相互作用比较弱，在高于800℃时三者发生相互作用，赤泥的加入由于调整了样品中的Al/Si摩尔比，使反应的最终物相选择性地向Na∶Al∶Si摩尔比为1∶1∶1的霞石和沸石相转化。

Mineral transformation in process of combined extraction of alumina from coal gangue and red mud

Combined extraction of alumina from coal gangue and red mud was studied. The effect of red mud on the alumina extraction of coal gangue and the consumption of Na₂CO₃ was investigated. The effect of the red mud on the activation process of coal gangue by Na₂CO₃ calcination was studied by way of TG-DSC and XRD. The results showed that the dissolution of alumina for the mixed “coal gangue-red mud-Na₂CO₃” sample increased with the Na/Al molar ratio and the calcination temperature. The alumina dissolution of the mixed sample reached 91.7% when the Na/Al molar ratio was 1.2 and the calcination temperature was 850℃ at the Al/Si molar ratio of 1. The consumption of Na₂CO₃ decreased 77.9% at this condition by comparison with that of coal gangue activated directly by Na₂CO₃. The results of TG-DSC and XRD showed that the interactions among coal gangue, red mud and Na₂CO₃ were weak at <700℃ and were strengthened at >800℃. The addition of red mud would make the phases in the mixed sample selectively transformed into nepheline and zeolite with a Na∶Al∶Si molar ratio of 1∶1∶1 owing to the adjustment of the Al/Si molar ratio of the sample.