Novel re-utilization of high-temperature catalytic gasification ash with sodium recovery, aluminum extraction, aragonite and mesoporous SiO2 synthesis

Abstract

Catalytic gasification ash (CGA) is composed of Si, Al, Na and Ca elements, and the reutilization of CGA is important for the industrialization of catalytic gasification. The paper proposes a novel utilization of CGA with Si, Al, Ca and Na divided and utilization. The minerals transformation behaviors during catalytic gasification with Na2CO3 and Ca(OH)2 addition are investigated, and Al and Na are recovered by water leaching and hydrothermal leaching. The characteristics of synthesized aragonite fiber and mesoporous SiO2 are also studied. The results show that water-soluble NaAlO2 and sodium aluminum silicate with low Si/Al ratio generate during catalytic gasification with Na2CO3 and Ca(OH)2 addition. By water leaching, Al recovery can reach 80.2%, at the same time, 62.3% of Na can be recovered. Followed by hydrothermal process, 91.2% of Na in the residue of water leaching can be reclaimed. Meanwhile, the flower-like and cluster needling tobermorite can be synthesized. By CO2-pressured leaching, Ca and Si in the tobermorite are divided with Ca dissolved in the CO2-pressured liquid. Ca converts into aragonite fiber with high aspect ratio, and Si converts into fiber-shaped mesoporous SiO2 with high specific surface area. In a word, Si, Al, Ca and Na in CGA are divided and utilization during three processes: water leaching, hydrothermal leaching and CO2-pressured leaching.