蒙脱土酸处理法合成洗涤剂用4A沸石

Synthesis of Detergent-Used Zeolite 4A from Montmorillonite

系统地研究了蒙脱土为原料，经硫酸处理后采用水热转化法合成洗涤剂用４Ａ沸石的方法．考察了酸处理及晶化条件对合成４Ａ沸石质量的影响，探讨了除石英的方法，并进行了４００Ｌ放大实验．结果表明：酸处理条件影响沸石的白度及纯度，晶化条件影响其纯度与粒度，去除石英可提高沸石的纯度．蒙脱土法与水热合成法比较而言，质量相差无几却更经济．

Under an increasing social demand for improving the so-called eutrophication problems in stagnant surface waters, the development of non-phosphated powder detergent is just initiated in our country. Zeolite 4A is the main substitute builders for STPP in non-phosphated detergent, and it can be manufactured from montmoril- lonite, which may greatly reduce the cost. This paper investigates the synthesis of zeolite 4A from montmorillonite in which montmorillonite is treated with sulfuric add at first. Many factors'that have great effects on the qualities of zeolite 4A product, including the acidification conditions and synthesis conditions as well as removing quartz from clay, are studied in detail. And pilot plant scale test of 400L has also been carried out. The results show that the acidification conditions, including acid concentration, weight ratio of solid to liquid, temperature, time, etc, have effect on the whitenes and purity of zeolite 4A product. The optimal acidification conditions are to use 30% H2SO4 solution, 1:3 wright ratio of solid to liquid, at 95, and for 10h. For the synthesis conditions we find: screen and alkalinization of activated silicic add gel, decreasing moral composition of Na2O/H2O of reaction mixture, adding direct agent, increasing rotate speed and etc., can decrease the mean particle size of zeolite 4A product. But if Na2O/H2O>0. 06 hydrated sodalite which is another unexpected type of zeolite would be generated. Consequently the moral composition of reaction mixture (we think better) is 3Na2O:Al3O3: SiO2: 100H2O. bodes adding direct agent can reduce the time of crystallization of zeolite 4A greatly. In addition, cleanup of kettle scale in time can prevent the birth of hydrated sodalite. The results also show that removing quartz impurities from clay can improve the purity and qualities of zeolite 4A. Finally detergent-used zeolite 4A with good qualities is synthesized successfully in the pilot plant scale test of 400L. Main properties of zeolite 4A obtained are: whiteness: 93-95%, ion exchange capacity: 285-322 Ca- CO3/g, particle size distribution: <4um occupying 85-87% and < 10um occupying 99%. These properties of zeolite 4A product have reached or e-coeded the industrial standard of PRC. Compared with conventional method that uses water glass as its silica resource, this method has exactly the same perfect qualities and is more economical.