The Synthesis Of NaY Zeolite By Alumina Semen In Sintering Process

Based on the existing NaY production technology,the NaY zeolite preparation technology relying on the sintering process of alumina production is studied, semen and soluble glass with low modulus in the sintering process are used as the main raw materials.The crystallization mechanism, analytical methods, production technology and factors in the process of the general zeolites and zeolite Y are discussed in this article,and the influence of SiO2/Al2O3 ratios, alkalinity, dosage of directing agent and crystallization time in the synthesis system on NaY zeolite preparation are mainly researched,the effect of the Na2CO3 concentration in the system is also studied.lt has shown that the higher SiO2/Al2O3 ratios and the slower crystallization rate in the synthesis system,the higher SiO2/Al2O3 ratios of production; On the contrary,the higher alkalinity and the faster crystallization rate, the lower SiO2/Al2O3 ratios of production.The addition of crystallization directing agent (CDA) has significant effects on promoting crystallization and preventing generation of impurity phases, the proper dosage is 3.5%～5.0%;The crystallization time should be controlled in the range of 24～36 hours,because the crystallinity of production will take on downward trend if the crystallization time is too long; The concentration of Na2CO3in the synthesis system can be 0-30g/L, there is no significant influence to the synthesis process.According to the results of the research, the NaY zeolite preparation using the alumina semen in sintering process instead of sodium aluminate(ak=2.5) and replacing modulus of 3.2 soluble glass by the modulus of 3.0 one is feasible,and the process conditions is determined as follows:the H2O/Na2O ratios in the synthesis system is 50, the SiO2/Al2O3 ratios is 8.9,the raw materials are added in the following listed order: semen, soluble glass, aluminum sulfate and crystallization directing agent, the dosage of CDA is 5%,the crystallization temperature is 95℃, the crystallization time is above 20 hours.The product of the mentioned process has shown such features:the crystallinity of the NaY zeolite was greater than or equal to 88%, the SiO2/Al2O3 ratios was greater than or equal to 4.8, crystal phase had high purity,the granularity was uniform,experiment had high repeatability. This process can greatly reduce material consumption and production cost.It can reduce production cost￥2591.6/t approximately calculated at the market price in May,2008.Consequently,the process is of great economic benefit and has popularization value.