二段种分法制备氢氧化铝微粉的工艺

为了研究煤矸石酸法提取物硫酸铝的应用及氢氧化铝精细化生产过程,进行了二段种分法制备氢氧化铝微粉的工艺研究.用煤矸石酸法提取的硫酸铝和拜耳法精制的铝酸钠稀释后的溶液反应,生成的浆液经放置老化后即得活性晶种.用活性晶种进行铝酸钠溶液的一段种子分解和二段种子分解,制备氢氧化铝微粉.同时研究了制备过程中种子浆pH、分解温度、种子比值、分解时间、铝酸钠溶液α_k及铝酸钠溶液质量浓度对分解率、氢氧化铝微粉颗粒粒度的影响.结果表明,煤矸石提取物硫酸铝做晶种引发剂,在一定的工艺条件下可制得白度大于99%、Fe₂O₃质量分数小于0.006%、SiO₂质量分数小于0.05%、吸油值小于0.70 mL/g、粒度在0.5~6 μm的氢氧化铝微粉.

Preparation technology of aluminum hydroxide micropowder by two-stage seed separation

In order to study the application of aluminum sulfate extracted by gangue acid method and the fine production of aluminum hydroxide, the preparation technology of aluminum hydroxide micropowder was explored using two-stage seed separation method. The active seeds could be obtained by the reaction of aluminum sulfate extracted by gangue acid method and diluted sodium aluminate solution refined by Bayer method. Subsequently, alumina micropowders were prepared by the decomposition of first and second stage seeds in sodium aluminate solution with active seed. Various factors affected on the decomposition rate and particle size of aluminum hydroxide micropowder were investigated including the pH value of the seed pulp, decomposition temperature, seed ratio, decomposition time, α_kof sodium aluminate solution and sodium concentration of aluminate solution. And the results showed that the as-prepared aluminium hydroxide powder exhibited whiteness above 99%, Fe₂O₃ and SiO₂ content less than 0.006% and 0.05%, respectively, oil absorption value less than 0.70 mL/g and the average particle size in the range of 0.5-0.6 μm.