Mechanochemical Method to Prepare the White Carbon Black Using Coal Gasification Coarse Slag

Abstract Coal gasification coarse slag (CS), mainly composed of SiO 2 , can be used as silica precursor to prepare white carbon black (WCB). This research provides a new method of the mechanochemical route to produce WCB. The physical and chemical characteristics of WCB all met the relevant China industry standard, which can be applied in various chemical industries such as rubber, coatings, and plastics. The white carbon black was composed of 96.86% SiO 2 and exhibited a white color. The surface area and pore volume of WCB was 533 m 2 / g and 0.75 cm 3 / g , respectively. The WCB was composed of the amorphous phase and a little quartz. The synthesis mechanism of WCB using mechanochemical method was also studied. The mechanochemical milling could trigger the reaction between the Si component and activator. Specifically, the bridging oxygens structure of Si─O─Al bonds or Si─O─Al bonds were broken. During acid leaching, the silicon-oxygen bonds are broken to form anions as either HSiO 4 3 − or HSiO 4 − . The concentration of silicate species passing in the acid solution would increase with the dissolution proceeds. When the Si concentration in the solution becomes oversaturated, the dissolved silicon tends to polymerize and form the silica gel in acidic aqueous media. The other metal elements were dissolved in acid solution. Thus, the WCB with high-purity silicon dioxide were prepared. Therefore, in this study, we develop a friendly mechanochemical technology, which produce WCB in a reproducible way with high yield and under simple and easy operating conditions.