| Zeolite 4A is crystalline sodium alumina-silicate with a cage structure and has several characteristics, such as ions-exchange, surfactant adsorption. And it is a globally preferred detergent builder replaced STPP. Shandong CHALCO has developed a zeolite process that is grafted on the sinter alumina process. And now, it becomes a biggest manufacture center in Asia.The synthesis system of 4A zeolite is very complex. In this paper, the influence of mole rate, concentration, temperature, crystallization directors and crystallization time on zeolite synthesis with higher concentration was studied. The preferable technique parameters was obtained and applied successfully in the industry.The preferable technique parameters obtained are as follow: SiO2:Al2O3 is in the range of from 1.8 to 2.0, Na2O:Al2O3 is between 2.8 to 3.2 and H2O:Na2O is from 46 to 54. It was found that the crystallization phase would be shifted, impurity be increased in crystalline and the calcium exchanging capacity of zeolite obtained would be reduced if SiO2:Al2O3 is higher. The alkalinity plays a important role in polymerization of silicate ions and the balance of species in the system.As for the concentration, temperature, crystallization directors and crystallization time in the synthesis system, it was found the best conditions are: mixing temperature is in the range of from 60 to 65℃, the crystallization directors is 0.5% (volume percent), the crystallization temperature is 85 ℃ and the crystallization time is about 2 hours.The synthesis techniques with higher concentration have also applied successfully in the industry. In comparison with synthesis techniques of lower concentration, the solid content in crystallization system is increased to 125 from 80 g/L; the cost of water, steam and powder can be greatly reduced. The calcium exchanging capacity of the product is increased from 297 to 306mgCaCO3/g, and calcium exchanging rate is increased from 205 to 215mgCaC(Vg. |
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