三相水化制备氢氧化镁控制参数研究

发布时间：2018-11-03 14:30

【摘要】：氢氧化镁在环境工程领域的废水处理、烟气脱硫和固废处理与处置中均具有广泛的应用,其制备方法主要有:直接沉淀法、水热法、水化法和物理法。本文针对传统水化制备氢氧化镁的用时长、水化效果较差等缺点,进行了三相水化制备氢氧化镁实验,并确定了一套合适的三相水化控制参数。本文使用一套自行设计并制作的三相水化设备,主要由蒸汽发生器、混合罐、三相反应器所组成。在实验中,首先比较了本文使用的氧化镁在三相和两相水化下反应的水化效果,并进行了缩核模型、经验公式和BNG模型拟合,确定本文使用的氧化镁三相水化使用经验公式拟合。其次,调整三相水化的反应条件参数进行实验,进行了反应压力在0.1OMPa-0.20MPa、氧化镁浆料浓度在5%-15%和高、中、低活性的三种氧化镁三相水化实验。在实验选定的范围内,反应压力优选为0.20MPa,浆料浓度优选为5%,活性优选为相对的高活性。然后,进行了添加水化剂的三相水化实验,水化剂种类为乙酸、乙酸镁、氯化铵,添加浓度为0.05mol/L和0.10mol/L。与纯水水化相比,添加水化剂后,在水化30min时,三种不同浓度的水化剂对水化率提升均在20%以上,水化效果明显提高。最后,对添加水化剂的水化产物进行X射线衍射和电镜扫描的表征,对X射线衍射的特征峰进行对比,比较半峰宽,并计算平均晶粒尺寸,再与在电镜扫描图中可观察到氢氧化镁晶体的变化进行对照分析。本文所采用的三相水化制备氢氧化镁较传统的水化法更加高效。在实验选定的范围内优选高压高温、浆料浓度低、高活性氧化镁粉。还可以通过添加水化剂,大幅提升制备氢氧化镁效率,同时制备得到不同晶体形貌的氢氧化镁。
[Abstract]:Magnesium hydroxide is widely used in waste water treatment, flue gas desulfurization, solid waste treatment and disposal in the field of environmental engineering. Its preparation methods include direct precipitation method, hydrothermal method, hydration method and physical method. In view of the disadvantages of the traditional hydration to prepare magnesium hydroxide such as long time and poor hydration effect, the experiment of preparing magnesium hydroxide by three-phase hydration was carried out, and a set of suitable three-phase hydration control parameters was determined. In this paper, a three-phase hydration equipment designed and made by ourselves is mainly composed of steam generator, mixing tank and three-phase reactor. In the experiment, the hydration effect of magnesium oxide under three-phase and two-phase hydration was compared, and the shrinking nucleation model, empirical formula and BNG model were fitted. The empirical formula of magnesium oxide hydration used in this paper is determined. Secondly, the experiment was carried out by adjusting the reaction conditions of three-phase hydration. The reaction pressure was 0.1OMPa-0.20MPa, the concentration of magnesium oxide slurry was 5-15%, the activity of MgO was medium and low, three kinds of MgO hydration experiments were carried out. In the range selected in the experiment, the reaction pressure is 0.20 MPA, the slurry concentration is 5 and the activity is relatively high. Then, three phase hydration experiments were carried out. The hydration agents were acetic acid, magnesium acetate and ammonium chloride with the concentration of 0.05mol/L and 0.10 mol 路L ~ (-1) 路L ~ (-1). Compared with pure water hydration, when 30min was hydrated, the hydration efficiency of three kinds of hydrants with different concentrations was increased by more than 20%, and the hydration effect was improved obviously. Finally, the hydration products with hydration agent were characterized by X-ray diffraction and scanning electron microscope, the characteristic peaks of X-ray diffraction were compared, the half peak width was compared, and the average grain size was calculated. The change of magnesium hydroxide crystal was compared with that observed in scanning electron microscope. The preparation of magnesium hydroxide by three-phase hydration is more efficient than the traditional hydration method. High pressure and high temperature, low slurry concentration and high active magnesium oxide powder are selected in the selected range of experiments. By adding hydration agent, the efficiency of magnesium hydroxide can be greatly improved, and the magnesium hydroxide with different crystal morphology can be prepared at the same time.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ132.2;X703

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