关键词: 二次铝灰, 聚合氯化铝, 微量加碱法, 形态

Abstract: Secondary aluminum dross is one of the main by-products in recycled aluminum industry and has been classified as hazardous waste. Long-term stacking or arbitrary disposal for secondary aluminum dross could cause many environmental problems. The secondary aluminum dross from a recycled aluminum company in Wuhan was used to prepare polyaluminum chloride by improved acid leaching process through controlling alkali addition. The effects of material dosing ratio,acid leaching temperature and leaching time on the leaching rate of aluminum from aluminum dross were studied. The effects of alkalinity B value,alkali adding rate and temperature on the morphology of polyaluminum hydrolytic polymerization were studied. The results showed that the optimal leaching conditions of secondary aluminum dross are as follows:material dosing ratio of m( secondary aluminum dross) ∶m(HCl) ∶m(water)= 1 ∶4 ∶4,acid leaching temperature of 85 ℃ and acid leaching time of 2. 0 h,in which the leaching rate of aluminum in the acid leaching solution reached the maximum of 60. 30%. Polyaluminum chloride was prepared by slowly adding 15% Na2CO3 solution into acid leaching solution prepared under optimized conditions. When the alkalinity B is 2. 4,the alkali adding rate is 3. 6 mL / min,and the alkali adding temperature is 80 ℃ ,the content of Alb in the polyaluminum chloride reaches the highest of 57. 49%. The polyaluminum chloride was successfully prepared by this process, realizing the recycling and harmless treatment of secondary aluminum ash.