【作者】 逯双佳；

【导师】 仲剑初；

【作者基本信息】 大连理工大学 ， 化学工程与技术， 2012， 硕士

【摘要】 氧化镁是一种重要的无机化工材料,广泛应用在化工、医药、食品添加、耐火材料、橡胶行业、电子、航天、电力等领域。我国虽然镁资源丰富,但由于长期的开采利用和初级加工产品的出口,高品位矿源越来越少,而且从近些年氧化镁的发展趋势看,产品也趋向于高纯化、精细化。所以改善氧化镁的制备工艺,合理开发利用低品位矿源制备高纯度氧化镁对我国镁质材料工业的发展有着重要意义。本论文主要对以轻烧镁为原料碳化法制备硅钢级氧化镁的工艺过程进行了研究,碳化法制备氧化镁的主要过程为：将轻烧镁经过消化、碳化制得碳酸氢镁水溶液(重镁水),采用络合掩蔽的方法脱除钙、铁等杂质,络合掩蔽杂质后的重镁水经热解、煅烧等过程制得产品氧化镁。研究了消化过程固液比和消化时间等因素对重镁水中各组分浸出率的影响；考察了碳化时间和碳化固液比对重镁水中各组分浓度的影响；对络合掩蔽除杂过程中络合剂用量对杂质脱除的效果和络合剂联合使用的效果进行了探讨；并对热解温度、减压热解和热解前加入添加剂对热解产物沉淀率和最终产品的粒度和形貌的影响也进行了探讨。通过以上的研究确定了适宜的工艺条件,即：消化时,固液比为80g/L,消化时间60min;碳化时,固液比为20g/L,碳化时间为60min,可以得到高镁浓度的重镁水。在掩蔽除杂阶段,200mL重镁水中加入10mL1+1三乙醇胺进行掩蔽除铁,热解阶段在常压90℃条件下热解20min,产品氧化镁中的MgO含量为99.3%,CaO含量0.31%,Fe2O3含量0.042%；或使用草酸和柠檬酸作为复合络合剂时,在200ml重镁水中加入1g柠檬酸和2g草酸,最终产品氧化镁中的MgO含量为98.2%,CaO含量0.24%,Fe2O3含量0.030%；在此条件下得到的氧化镁产品的粒径主要分布在3-4μm的范围内,符合硅钢级氧化镁的化学质量标准和粒度指标。在减压状态下65℃热解20min,重镁水中的镁沉淀率可以达到常压0℃热解的水平,但最终产品氧化镁的粒径主要分布在20-40μm的范围内,产品粒度达不到硅钢级氧化镁的标准。更多还原

【Abstract】 Magnesium oxide is a kind of important inorganic chemical materials, which is widely used in chemical industry, medicine, food adding, refractory materials, rubber industry, electronics and aviation, etc. Although magnesium resources are rich in our country, the high grade sources get less and less due to a long-term exploitation and primary products exporting. In view of developing of magnesium oxide in recent years, the products tend to high purification and fine. Therefore, it has important significance to improve the preparation of magnesium oxide process and reasonablely develop low grade sources for preparing high purity magnesia products.This study is involved in the preparation process of silicon-steel magnesium oxide with carbonization method. The main preparation processes of magnesium oxide using light-burned magnesia as raw materials by carbonization method are as follows. Frist, light-burned magnesia was hydrated and carbonated to obtain magnesium bicarbonate liquor.Then impurities Fe and Ca in magnesium bicarbonate liquor were covered by using a complex method. After that, the treated liquid was pyrolyzed to obtain basic magnesium carbonate which was calcined to get magnesia. The effects of hydration recation time and solid-liquid ratio on the component concentrations of magnesium bicarbonate liquor were discussed. The effects of reaction time and solid-liquid ratio of carbonization on the component concentrations of magnesium bicarbonate liquor were also investigated. Meanwhile the impacts of complexing agent addition and composite complexing agent addition on the removing impurities Fe and Ca were also investigated, respectively. We also gave an insight into the effects of pyrolytic temperature, pyrolytic pressure and adding additives on the particle size and deposition rate of magnesium bicarbonate liquor. Baesd on the above mentioned researches, the suitable processing conditions were obtained. The obtained results indicate that the preferred solid-liquid ratio and reaction time of hydration are80g/l and60min, while the favorable solid-liquid ratio and reaction time of carbonization are20g/l and60min. In the process of impurities removing,10ml triethanolamine(1:1) as a complexing agent was added into200ml magnesium bicarbonate liquid to cover impurities Fe, and then the treated liquid was pyrolyzed at90℃for20min to afford basic magnesium carbonate which was calcined to obtained final magnesia with99.3wt.% MgO,0.31wt.%CaO and0.042wt.%Fe2O3. Meanwhile, when using citric acid and oxalic acid as a composite complexing agent, MgO content of the final product magnesia obtained is more than98.2wt.%. CaO content0.24wt.%and Fe2O3content0.030wt.%under the condition of200ml magnesium bicarbonate liquid with adding1g citric acid and2g oxalic acid. Under the above preferred conditions, the grain size of the final product magnesia is mainly around3-4μm which meets the requirement of quality standard for silicon-steel magnesia. When pyrolizing the treated liquid at65℃for20min at low pressure, the magnesium prepicitation rate of magnesium bicarbonate liquor can reach the level of atmospheric. However, the main grain size of the final magnesia ranges from20to40um which can’t meet the quality requirement of silicon-steel magnesia.更多还原