采用草酸和紫外光催化法处理赤泥(英文)

利用草酸作为浸出剂以除去拜耳法残渣赤泥中的氧化铁,从而提高赤泥的工业应用价值,同时对草酸浸出液进行紫外光照射,将草酸铁还原成草酸亚铁沉淀,实现草酸溶液循环再利用。实验结果表明,在75°C下,赤泥在1mol/L草酸溶液中浸出2h,氧化铁的浸出率可达到96%,浸出后赤泥中氧化铁的含量由17.6%降低至小于1%。在紫外光照催化作用下,1h内浸出液中90%以上的草酸铁转变成草酸亚铁沉淀,剩余草酸可循环再利用。该草酸亚铁为β-FeC2O4.2H2O。对UV催化沉淀的机理进行讨论分析。

Red-mud treatment using oxalic acid by UV irradiation assistance

Red-mud is the residue from the Bayer process,in which the iron minerals should be removed before red-mud is used to produce refractory materials.The iron minerals in red-mud were extracted by oxalic acid solution.The content of Fe(calculated in Fe2O3) in red-mud was reduced from 17.6% to less than 1% after being treated by 1 mol/L oxalic acid solution at 75 ℃ for 2 h.The Fe(III) oxalate solution obtained was then irradiated by UV light,resulting in the precipitation of Fe(II) oxalate.Under UV photocatalysis,more than 90% of Fe(III) oxalate in the extracted solution was transformed into the precipitation of Fe(II) oxalate crystallite(β-FeC2O4·2H2O).The filtrate from the Fe(II) oxalate precipitate filtration could be reused in the next cycle.The mechanism of UV photocatalysis precipitation was also discussed.