为考察铝土矿生物浸出脱硅的机制,比较了硅酸盐细菌JY03在细菌-矿物接触/非接触模式下与铝土矿的作用,分析浸出过程中铝土矿表面形成的生物膜与钝化膜对溶硅的影响。结果表明,在细菌浸出的前期(0~6 d),铝土矿表面生物膜与钝化膜还未形成,Al与Si的溶出主要受间接接触模式的影响；在6~12 d内,铝土矿表面的生物膜逐渐显现,Si 的溶出速率明显较非接触模式快,Si 的溶出主要受接触模式的影响,12d后,浸出液中 SiO2的浓度高于非接触模式17mg/L左右；在8~12d,Al2 O3沉淀产生,接触模式下Al的溶出速率明显变缓,非接触模式下明显下降；浸矿12d 后,Al2 O3絮凝沉淀在铝土矿表面形成钝化膜,浸出液中 Al2 O3浓度显著下降,SiO2的浓度达到最大值并趋于稳定。因此可以认为,生物膜的形成有利于细菌浸矿溶硅,钝化膜则抑制Al与Si的溶出。
To study desilication mechanism of bauxite bioleaching,the interaction were compared between the silicate bacterium JY03 and bauxite under the microbe-mineral contact/noncontact modes,and the effects of biofilm and passivation coating forming on the bauxite surface in bioleaching system were investigated.The re-sults show that:in initial step of bioleaching(0-6 d),the bauxite surface were not coated by biofilm and passiva-tion coating,and the dissolution approach of Al and Si was mainly under indirect contact mode;6-12d,as the biofilm formed gradually on the bauxite surface,the dissolution rate of Si was mainly under contact mode,sig-nificantly higher than indirect contact mode;after a 12d leaching,the concentration of SiO2 in the leaching solu-tion of contact model was about 17mg/L higher than that in the indirect contact model;in 8-12d,as Al2 O3 sedi-ment was forming,Al dissolution rate slows significantly in contact system,and decreased in indirect-contact system;after 12d-leaching,when a passive film was formed on the bauxite surface by flocculation and sedimen-tation of Al2 O3 ,the Al2 O3 concentration in the leaching solution was decreased significantly,and SiO2 concen-tration reaches a maximum and stabilized.It is concluded that Si,Al dissolution can be promoted by biofilm and inhibited by Al2 O3 passivation coating.
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