硫酸铝铵法氧化铝前驱体制备工艺研究

发布时间：2018-03-02 11:22

  本文选题：氧化铝前驱体　切入点：硫酸铝铵　出处：《河北科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：氧化铝是一种重要的化工原料,由于具有多种晶型,因而用途十分广泛,可用于电解铝、陶瓷、医药、电子、机械等众多行业行业。氧化铝多是由煅烧其前驱体制得,其前驱体的制备有酸法、碱法、硫酸铵法。硫酸铵法因污染小、产品品质高而优于前两种方法,但是该方法存在的问题之一是通过硫酸铝铵制备的氢氧化铝的颗粒小、滤饼含水量高,造成过滤困难和后续过程能耗过高。本论文针对硫酸铵法存在的问题,以硫酸铝铵为原料,开展氧化铝前驱体生成过程的实验研究,探索制备较大粒径氧化铝前驱体的方法和条件。首先对硫酸铝铵与碱直接沉淀反应制备氧化铝前驱体进行实验研究,探讨碱源、滴加方式、反应溶液的p H值、反应溶液的温度、滴加速度、陈化时间、硫酸铝铵溶液的浓度、晶种用量等条件对所得产品的影响。结果表明,在优化的实验条件下,可以制得粒径为300~400nm、滤饼含水量为70%左右的氢氧化铝样品。采用加入衬底溶液的方法对碱直接沉淀法进行改进。分别加入硫酸铵及硫酸钠做衬底溶液,硫酸钠做衬底溶液时又分单注法和双注法,进行直接沉淀反应实验研究,制得了粒径大并且滤饼含水量低的产品。以硫酸铝铵与氨水直接沉淀反应制备的氧化铝前驱体为原料,采用水热生长法对其处理,对水热操作条件进行考察,制得了粒径达500nm,含水量降低至60~70%的氧化铝前驱体。在上述实验研究的基础上,本论文尝试了在水热条件下原位合成氧化铝前驱体即水热合成法。经过实验操作条件的优选,获得了适宜的制备条件为水热时间为9小时、水热温度为150℃、水热合成环境为弱碱性,晶种的适宜加入量为5.0g/L,氨水与尿素配比为1:40,添加剂为硫酸钾。在此操作条件下,制得的氧化铝前驱体粒径为450~550nm,滤饼含水量降低到了40~50%,可有效降低生产氧化铝过程的能耗,提高经济效益。
[Abstract]:Alumina is an important chemical raw material, because of its many crystal forms, it can be used in many industries such as electrolytic aluminum, ceramics, medicine, electronics, machinery and so on. The precursor was prepared by acid method, alkali method and ammonium sulfate method. The ammonium sulfate method is superior to the former two methods because of its low pollution and high product quality. However, one of the problems in this method is the small size of aluminum hydroxide prepared by ammonium aluminum sulfate. The high moisture content of filter cake causes the difficulty of filtration and the energy consumption of subsequent process is too high. Aiming at the problems existing in ammonium sulfate process, this paper carried out an experimental study on the formation process of alumina precursor with ammonium aluminum sulfate as raw material. Firstly, the preparation of alumina precursor by direct precipitation of ammonium aluminum sulfate with alkali was studied, and the alkali source, the method of dropping and the pH value of the reaction solution were discussed. The effects of temperature, droplet acceleration, aging time, concentration of ammonium aluminum sulfate solution and amount of crystal seed on the product were studied. The aluminum hydroxide sample with the diameter of 300nm and the water content of filter cake is about 70%. The direct alkali precipitation method is improved by adding substrate solution. Ammonium sulfate and sodium sulfate are added as substrate solution, respectively. When sodium sulfate was used as substrate solution, it was divided into single injection method and double injection method to study the direct precipitation reaction. The product with large particle size and low water content of filter cake was prepared. The alumina precursor prepared by direct precipitation reaction of ammonium aluminum sulfate with ammonia water was used as raw material. The alumina precursor with a diameter of 500 nm and a water content of 60 ~ 70% was prepared by hydrothermal growth method and the conditions of hydrothermal operation were investigated. In this paper, the hydrothermal synthesis of alumina precursor in situ under hydrothermal conditions is attempted. The optimum preparation conditions are obtained as follows: hydrothermal time is 9 hours, hydrothermal temperature is 150 鈩，

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