基于脱硫剂制备的炽热镁渣激冷水合辅以添加剂改性原理研究

In 2012 the megnisum production in China was 85.3% of the world's，and 4,000,000 tons of megnisum slag was discharged. Pidgeon is used in the process of smelting megnisum. When the temperature of the hot megnisum slag decreases, the slag is powdered. It is harmful to the enviroment. If the megnisum slag is mixed with the fly ash, the desulfurization performance is improved finitely by general hydration as desulfurizer. On the other hand it takes the longer time and the high mass ratio of fly ash to megnisum slag to complete hydration process. Based on our research,the project focuses on the improvement method by the directly quenching hydration and additives in desulfurizer preparation of hot magnesium slag so that the hydration time and the mass ratio of fly ash to megnisum slag are reduced. The liguid-solid reaction dynamics is studied in the hydration reactor,which is designed by ourself and can record key parameters on real time.By means of TGA, the influence of the hydration parameters on the desulfurization performance is studied, including the temperature of the hot megnisum slag, the hydration time, the mass ratio of liquid to solid and fly ash to megnisum slag, the types and quantities of the additives, etc. FTIR, XRD and SEM are uesd to analyse the physical and chemical characteristics of the modified megnisum slag and the their products after desulfurization. The relations are obtained between the components and the pore constructures. The character of hydration liguid-solid reaction dynamics and the principle of hydration modify will be obtained. It may provide the theoretical base for the comprehensive utlization of the harmful megnisum slag.

2012年中国的镁产量占世界产量的85.3%，因镁冶炼产生400多万吨镁渣。镁的生产几乎都采用皮江工艺，排出的高温镁渣当温度降低时随之粉化，严重污染环境。镁渣通过常规水合脱硫活性仅略有改善，但是，水合时间却偏长，所需粉煤灰配比也偏高。本课题在已有研究的基础上提出将炽热镁渣直接激冷水合辅以添加剂改性的方法，以期缩短水合时间、减少粉煤灰配比，大幅度提高改性镁渣的活性。通过可在线记录参数的水合反应器，研究激冷水合液固反应动力学特征。借助TGA，比较热渣温度、水合时间、液固比、粉煤灰配比、添加剂的种类和添加量等水合参数对改性脱硫剂活性的影响。利用FTIR、XRD、SEM等仪器分析研究改性镁渣以及脱硫反应产物的物理、化学特性，得出水合条件与改性镁渣物相组成和孔隙结构特性的相关性。通过本项目的研究，将获得炽热镁渣激冷水合的动力学特征和基本原理，为镁渣进一步开发为高活性脱硫剂提供理论基础。

中国的镁产量占世界产量的85.3%，镁的生产几乎都采用皮江工艺，每生产1t镁，就会产生6~7t镁渣。排出的高温镁渣（1200℃）当温度降低时随之粉化，严重污染环境。镁渣主要成分是硅酸钙，具有一定的脱硫潜力。本项目在已有研究的基础上，提出将炽热镁渣直接激冷水合辅以添加剂改性的方法，以期缩短水合时间、减少粉煤灰配比，大幅度提高改性镁渣的活性。研究发现，炽热镁渣进行激冷水合，镁渣的钙转化率提高了212.4%（9.42%-29.43%）；炽热镁渣/粉煤灰激冷水合脱硫剂，钙转化率高达 61.13%，比自然冷却镁渣/粉煤灰水合脱硫剂的钙转化率高 24.43%，最佳的镁渣/粉煤灰激冷水合过程参数灰钙比为20。镁渣激冷水合的最佳参数是：镁渣温度950℃，液固比5%，水合时间6h。自然冷却镁渣/粉煤灰添加乙二酸水合制备脱硫剂，钙转化率高达73.7%，在激冷水合条件下，仅镁渣/添加Na2SO4改性效果最好，钙转化率达40.16%，且最佳添加量为2%。镁渣的激冷水合大大改变了镁渣的微观特性，比表面积，比孔容积大大增加，同时增加了微孔的数量。激冷水合的作用是保持了较多的高活性的β晶型，自然冷却镁渣水合产物β晶型仅为6.3%，激冷水合则高达53.8%。镁渣激冷水合的动力学特征表现为，水合早期由化学反应控制，反应中段由化学反应和扩散共同控制。研究还发现脱硫剂的水合反应程度与其钙转化率呈正相关，即水合反应程度越大，脱硫剂的钙转化率越高。通过本项目的研究，得出了提高镁渣活性的关键水合参数，获得炽热镁渣激冷水合的动力学特征和基本原理，可为镁渣进一步开发为高活性脱硫剂提供理论基础。