湿法氟化铝一般采用常压结晶工艺生产,其存在产品结晶水含量高、结晶时间长、产能低等弊端。对此,研究了氟化铝加压结晶工艺技术,考察了结晶压力、结晶时间、晶种添加量、加料温度等因素对氟化铝结晶水含量的影响。优化工艺及条件:将氟硅酸溶液加入反应槽中,加热到70~80 ℃,按照氟硅酸和氢氧化铝物质的量比为1.1:1加入氢氧化铝,在95~105 ℃反应30 min,过滤得到氟化铝溶液和硅胶沉淀;将氟化铝溶液转入高压结晶釜中,添加15%（质量分数）的氟化铝晶种,控制结晶釜内的温度为170 ℃,维持结晶压力为0.7 MPa,结晶时间为3 h;将高压结晶釜内的温度降到80~90 ℃,对结晶后的料浆进行真空抽滤,再经洗涤得到氟化铝软膏;将氟化铝软膏置于120~180 ℃下干燥脱去附着水,再逐步升温至400~600 ℃进行煅烧,除去产品中的结晶水,冷却后得到氟化铝产品。实验结果表明,采用加压结晶工艺制备氟化铝,不仅降低了产品结晶水含量和生产成本,提高了产品质量和产量,而且解决了制约磷化工、氟化工和电解铝行业发展的瓶颈问题。

Crystallization under normal pressure is usually adopted when producing aluminum fluoride by wet method,which suffers from disadvantages such as high crystal water content in product,long crystallization time and low production capacity.Therefore,the aluminum fluoride pressurized crystallization technology was studied and the effects of the factors,such as crystallization pressure,crystallization time,addition amount of crystal seeds and filling temperature on the aluminum fluoride crystal water content were investigated.Optimized process and conditions:Put fluorosicilic acid（FSA） solution into reaction tank,heated up to 70~80 ℃;Added aluminum hydroxide based on the amount-of-substance ratio of FSA to aluminum hydroxide being 1.1:1,and reacted under 95~105 ℃ for 30 min;Filtered to obtain aluminum fluoride solution and silica gel precipitation;Shifted aluminum fluoride solution into high-pressure crystallization reactor,and added 15%（mass fraction） crystal seeds of aluminum fluoride;Maintained inner temperature 170 ℃ and crystallization pressure 0.7 MPa,crystallization lasted for 3 h;Droped the inner temperature to 80~90 ℃,vacuum filtrated the slurry after crystallization,and obtained aluminum fluoride paste after washing;Dried the obtained aluminum fluoride paste under 120~180 ℃ to remove adhering water;Raised temperature gradually to 400~600 ℃ and removed crystal water from product by calcination.The final product of aluminum fluoride was obtained after cooling.The experiment results showed that adoption of pressurized crystallization technology in producing aluminum fluoride can not only reduce both crystal water content in product and cost,improve quality and output,but also solve the bottleneck problem that restricts the development of the phosphorus chemical industry,fluorine chemical industry and electrolytic aluminum industry.