| 摘要 |
PURPOSE:To obtain alumina particles with reduced consumption of NaOH and reduced cost by neutralizing NaOH soln. with Al2(SO4)3 soln., adding Ca(OH)2 to Na2SO4 soln. after separating generated Al(OH)3, and reutilizing formed NaOH soln. for the neutralization reaction. CONSTITUTION:In the stage 1 for forming Al(OH)3, Al(SO4)3 soln. is added slowly for neutralization to form Al(OH)3 as precipitate and Na2SO4 as soln. Then, said Al(OH)3 precipitate is separated from the Na2SO4 soln. by centrifugal separation, filtration, etc., in the next stage 2, and separated precipitate is washed with water. In the third stage 3, Al(OH)3 is dried, dehydrated and calcined to obtain alpha-Al2O3 particles. In the fourth stage 4, Ca(OH)2 soln. is added to the Na2SO4 soln. discharged from the stage 2 to form precipitate the CaSO4 and NaOH soln. The regenerated NaOH soln. in this stage is fed back to the first stage 1 and reutilized circulatorily.
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