针对拜耳法生产氧化铝过程中排放的碱性赤泥无法大规模处理这一世界性难题,提出了钙化-碳化法低成本、大规模综合利用赤泥新工艺.本文以我国的一水硬铝石溶出赤泥的钙化渣为原料,研究了碳化液固比、碳化温度、碳化压力等重要条件对钙化赤泥碳化分解过程的影响.实验表明,适宜的碳化条件为:液固比5∶1、碳化温度120 ℃、CO2压力1.2 MPa.在此条件下,氧化铝回收率为39.3%.经过最终的溶铝过程后,碳化赤泥的主要成分为碳酸钙和硅酸钙,含碱量低于0.5%,可用于制备水泥.
Red mud produced in the Bayer process is a hazardous solid waste difficult to be cosmically treated because of its higher alkalinity.It is a hard nut to crack in the world.A new technology of calcification-carbonation was developed to recover alumina from Bayer red mud.In the present,the diaspore Bayer calcified red mud was decomposed by CO2.The carbonation conditions are:liquid-solid ratio is 5∶1;temperature is 120 ℃;CO2 is 1.2 MPa.Under the condition above,39.3% Al2O3 can be extracted.The XRD showed that composition of the final red mud is CaCO3 , CaSiO4 and Na2O less than 0.5wt%.The treated red mud might be taken as a architeclural.
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