粉煤灰碱熔—脱硅制备A型沸石和白炭黑

Preparation of zeolite A and silica from fly ash by alkali fusion-desilication

以工业废物粉煤灰为原料,在传统碱熔水热合成方法的基础上引入脱硅工艺,从碱熔产物中获得脱硅产物和脱硅滤液;再以脱硅产物为原料水热合成A型沸石;以脱硅滤液为原料制备白炭黑。对制备工艺条件进行了优化,并对制备的产品进行了表征。结果表明:碱熔产物经过水洗脱硅,其脱硅产物中硅铝摩尔比接近1∶1,脱硅滤液中硅的质量浓度为16.840 g/L,铝的质量浓度仅为0.084 g/L,硅酸钠和硅铝酸钠得到有效的分离;在NaOH浓度2 mol/L、晶化时间12 h、晶化温度90℃的条件下制备的A型沸石结晶度好,晶相纯度高,所合成的A型沸石的钙离子交换容量满足QB 1768—2003标准要求;制备的白炭黑SiO2质量分数高达93.72%,其各项指标均符合HG/T 3065—1999标准要求。

Using industrial waste fly ash as raw material,and introducing desilication process in traditional alkali fusion hydrothermal synthesis method,desilication products and desilication filtrate were obtained from alkali fusion products.Then the desilication products was used as raw material to synthetize zeolite A by hydrothermal method And the desilication filtrate was used as raw material to prepare silica.The preparation process conditions were optimized and the prepared products were characterized.The results show that:After desilication of alkali fusion products by washing,the molar ratio of silicon to aluminum in the desilication product is close to 1∶1,the mass concentration of silicon and aluminum in the desilication filtrate is 16.840 g/L and only 0.084 g/L respectively,indicating the effective separation of sodium silicate and sodium aluminosilicate;Under the conditions of NaOH concentration 2 mol/L,crystallization time 12 h and crystallization temperature 90℃,the produced zeolite A has good crystallinity and high crystal purity,and the calcium ion exchange capacity of the zeolite A meets the requirements of Chinese light industry standard QB 1768-2003;The mass fraction of the prepared silica is as high as 93.72%,and all indexes of it meet the requirements of Chinese chemical industry standard HG/T 3065-1999.