Kinetic analysis on the mesoporous formation of coal gasification slag by acid leaching and its thermal stability

Abstract Coal gasification slag is abundant of unburned carbon and inorganic matters such as silica, alumina and calcium oxide. The mesoporous structure of coal gasification slag can be produced by acid leaching of metal ions. Therefore, it is very important to study the acid leaching process of coal gasification slag. At the same time, in order to broaden the application fields of coal gasification slag, the thermal stability of the as-prepared pore structure should meet the requirements of various occasions. Using coal gasification coarse slag (CS) and coal gasification fine slag (FS) as raw materials, this study investigated the kinetic characteristics of mesoporous formation and optimized the acid leaching conditions. The results of BET, BJH, SEM, XPS and chemical tests showed that under the condition of acid-ash ratio (molar ratio) of 1.0, liquid-solid ratio (volume/mass) of 4:1 and acid leaching temperature of 90 °C, the formation of mesoporous structure by acid leaching was a process of first-order kinetic reaction. According to the analysis of XRD, it was found that the thermal stability of both CS and FS had been greatly improved after acid leaching because of the siliceous enrichment.