拜耳法流程中碳酸钠升高的原因分析及降低措施

Reason Analysis and Reducing Measures of Concentration Increase of the Sodium Carbonate in Bayer Process Flow

由于铝土矿中钙、镁化合物在溶出过程中形成碳酸碱以及铝酸钠溶液吸收空气中CO2形成碳酸钠等原因,导致流程中碳酸钠浓度升高、溶出率低、蒸发器能耗升高等不利影响。通过抑制反苛化反应、强化结晶析盐、采用机械搅拌以及将拜耳法精液与烧结法精液合流碳分等措施,减少了流程中Nc的循环累积,蒸发母液中Nc浓度由46.59g/L降为30.57g/L。

The calcium and magnesium compounds of the bauxite formed carbonate in dissolution process and the sodium aluminate solution absorbed the CO2 in the air formed sodium carbonate and so on.It resulted in the concentration increase of sodium carbonate in the flow,reduced the dissolution rate of alumina and increased the consumption of evaporator energy and other adverse effect.Some improvement measures were taken,such as inhibiting the anti-causticization reaction,strengthening crystallization,adopting mechanical stirring instead of air mixing and gathering the sodium aluminate solution from Bayer process with the sodium aluminate solution from sintering process to carbonating.Therefore,it reduced the amount of Nc accumulation in process and the concentration of Nc in evaporation liquor decreased to 30.57 g /L from 46.59 g /L.