分类号：密级：
U D C：学号：417414714061 南昌大学专业学位研究生
学位论文
氨化法制备高纯二氧化硅及高纯石英的过程研究Process Study on Preparation of High Purity Silica and High Purity Quartz by Ammonification Reaction
张琪
培养单位（院、系）：资源环境与化工学院
指导教师姓名、职称：刘晓红教授
指导教师姓名、职称：
专业学位种类：工程专业
专业领域名称：化学工程
论文答辩日期：2016年12月4日
策略路由答辩委员会主席：
评阅人：
2016年 11月日
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摘要
摘要
氟硅酸是磷肥生产中的副产物，任其排放会污染环境，造成氟硅资源的浪费。利用氟硅酸，将其转化为高附加值的硅产品或氟产品有着良好的市场前景
和环保意义。
本实验以氟硅酸为原料，一步氨化反应得到氟硅酸铵溶液，设计铵盐钙盐
除杂，得到净化的氟硅酸铵溶液，经过二步氨化反应得到产品高纯二氧化硅，
然后高温煅烧高纯二氧化硅，制备了高纯晶体石英。对反应过程中的条件进行
了探索和优化。
制备氟硅酸铵溶液的最佳工艺条件为：一步氨化反应终点 pH=3.8~4.0，氨
-1 -1
水滴加速度1.5ml·min ，反应温度25℃，搅拌速度200r·min ，在此优化工艺条件下，氟硅酸铵得率93.6%。
铵盐为添加剂调节氟硅酸铵溶液 pH=6.5，溶液中的 Ca 金属杂质去除率达88.8%，Mg 金属杂质的去
除率达81.2%；钙盐为沉淀剂除杂，溶液中Fe 去除率
为 82.3%，Al 去除率达 79.8%。除杂的最佳工艺条件：m(钙盐)：m(H SiF 折
2 6 100%计)=9wt%，陈化40min，静置9h，最佳工艺条件下，去除了溶液中97.9% 的金属杂质，得到了高纯的氟硅酸铵溶液，除杂效果理想。
当 m(钙盐)：m(H SiF 折 100%计)=9wt%时，产品 SiO 中金属杂质去除率
2 6 2
-1
98.1%，杂质含量小于100μg·g ，属于高纯二氧化硅，产品SiO 纯度达到99.99%。
2
制备高纯二氧化硅的最佳工艺条件：反应终点pH=8.5、反应温度40℃、氨水滴-1
加速度4ml·min 。该条件下，高纯二氧化硅得率94.6%，粒径0.35μm。经由IR、
TG 检测，证明产品是SiO ，XRD 分析，产品SiO 为非晶态；SEM 分析，样品
2 2
分散性良好，呈蓬松多孔状。
高纯二氧化硅在煅烧温度高于1200℃时发生晶型转化，当温度达到1300℃，保温时间为2h 时，无定型SiO 转化为方石英晶体，转化率接近100%；晶化后
2
样品的表面孔道消失，结构更为紧实；高温煅烧后，样品粒径减小，体积收缩，当煅烧温度达到1300℃，体积收缩率达81.89%。电脑截图的快捷键是什么
关键词：氟硅酸；氨化反应；除杂；高纯二氧化硅；高纯石英
I
Abstract
Abstract
Fluorosilicic acid is a byproduct during the production of phosphate fertilize, indiscriminately discharg
ing of it will pollute the environment and cau the waste of resources. Using fluorosilicic acid and converting it into high value-added silicon products or fluorine products has a good market prospects and environmental significance.
变形模量In this experiment, we u fluorosilicic acid to produce ammonium fluorosilicate solution by the first ammonification reaction, and then we finding suitable ammonium salt and calcium salt as addition agent to remove impurities in solution, so we have purified ammonium fluorosilicate solution. After the cond ammonification reaction we can get high purity silica, calcining it in high temperature we will have high purity quartz crystal. We have explored and optimized the condition of the reaction.
The optimum conditions of the first ammonification reaction: the final pH is
-1
3.8~
4.0, the dropping speeding of ammonia is 1.5ml·min , the temperature of the
-1
处理怎么读
reaction is 25℃ and the stirring speed is 200 r·min . The yield of ammonium fluorosilicate is 93.6% under this optimized conditions.
When we put ammonium salt as addition agent into ammonium fluorosilicate solution to change it’s pH to 6.5, we find the impurities removal rate of metal Ca is 88.8%, the rate of Mg is 81.2%. And then we add calcium salt as precipitant into the solution to remove Fe、Al impurities, we notice the impurities removal rate of metal Fe is 82.3%, the impurities removal rate of metal Al is 79.8%. And then we explore the optimum conditions. The optimum conditions is as follows: the mass ratio of calcium salt to fluorosilicic acid is 9:100, aging time of 40 minutes, standing time of 9 hours. Under this condition, we removed 97.9% of the metal impurities in the solution and got the highly pure ammonium fluorosilicate solution. The effect of impurities removal achieved the desired results.
When the mass ratio of calcium salt to fluorosilicic acid is 9:100, the removal rate of metal impurities in SiO can achieve 98.1%, the impurity content is less than
2
II
Abstract
-1
100μg·g which has reached the national standard. The final production can be called as high purity silica and the purity of SiO is 99.99%. The optimum conditions to
2
produce high purity silica: the final pH of 8.5, the reaction temperature of 40℃ and
-1
the dropping speeding of ammonia is 4ml·min . Under the conditions, the yield of silica is 94.6%, the particle size is 0.35μm. The TR test shows that the final product is SiO , the XRD test shows that the sample is amorphous silica and the SEM test
2
shows SiO is fluffy and has good dispersion.
键盘字母排列2
When the calcination temperature is above 1200℃, the high purity silica begins to convert to high purity quartz. And when the temperature reaches 1300℃, holding time is 2 hours, we found that the high purity amorphous silica transform into cristobalite crystals and the conversion rate is clo to 100%. The surface of the sample become more smooth and the structure is more compact. After calcination at high temperature, the particle size of sample reduces and the volume shrinks. When the calcination temperature reached 1300℃, the volume shrinkage rate reached 81.89%
Key words: fluorosilicic acid; ammonification reaction; impurity removal; high purity silica; high purity quartz
III
