Hydrothermal synthesis of 13X zeolite by using feldspars separated from waste granite powder

Zeolite has good physicochemical properties such as adsorption, cation exchange, molecular sieving and catalysis to be widely used as selective scavengers of heavy metals from liquid effluents. In this paper, the synthesis method of 13X zeolite using fine granite dust (FGD) resulting from granite processing has been investigated. Both alkaline fusion method (770-830 degrees C, 80 min) and hydrothermal process (95-100 degrees C, 8-12 h) were selected and applied to the synthesize of 13X zeolite. A major disadvantage of synthesis of zeolite by using alkaline fusion method is high sintering temperature. The sintering temperature was lowered from 1300 to 800 degrees C by putting FGD into water and maintaining for 5 min to remove crystalline quartz which has low reactivity. On the other hand, it is important to find rational sintering temperature at which albite is decomposed more easily than kalifeldspar in FGD because 13X zeolite is chemically concerned with sodium (Na). For this, reaction heats of kalifeldspar and albite were calculated at the temperature range of 770-830 degrees C. As a result, it was proved that albite has the possibility to be dissolved thermodynamically more easily than kalifeldspar, but the difference between the heat effects of albite and kalifeldspar is not altered too much in proportion to the increase of temperature. Eventually, 13X zeolite has been successfully synthesized from FGD with low energy and all the other stone processing waste can be recycled by this method.