煤矸石合成4A分子筛及其在废水中的应用

铝、硅主要是以高岭土形式存在于煤矸石中的，活性非常低。通过添加碳酸钠在一定温度下焙烧煤矸石，使煤矸石中的氧化铝和氧化硅转化为可溶硅铝酸钠，并通过实验确定了影响合成4A分子筛性能的因素。实验表明，碳酸钠与煤矸石质量比为1.2、活化温度为800 ℃、活化时间为1.5 h、n（氧化钠）/n（二氧化硅）为1.8、n（水）/n（氧化钠）为42、晶化温度控制在90 ℃、晶化时间为3 h，制得的4A分子筛的钙离子交换能力为305 mg/g，对废水中铬离子的去除率达到83.6%。

Preparation of 4A molecular sieve from coal gangue and its application in wastewater treatment

As the aluminum and silicon existed in the form of kaolin in the coal gangue，their activities are very low.If the coal gangue is sintered with sodium carbonate at a certain temperature，alumina and silicon dioxide in the coal gangue can be converted into soluble sodium silicoaluminate.The factors that can affect product′s performance were determined by experiments in the synthesis of 4A molecular sieve.Results show that when the mass ratio of sodium carbonate to coal gangue was 1.2，the activation temperature was 800 ℃，the activation time was 1.5 h，the amount-of-substance ratio of Na₂O to SiO₂ was 1.8，the amount-of-substance ratio of H₂O to Na₂O is 42，crystallization temperature was 90 ℃，and crystallization time was 3 h，the calcium exchange ability of the obtained 4A molecular sieve was 305 mg/g and its removal rate to chromium ion in the wastewater reached 83.6%.