Preparation method of silica gel

The invention relates to a preparation method of silica gel, which is used for preparing inorganic silica gel by extracting siliceous elements from waste concrete rich in SiO2, Al2O3 and other components, and comprises the following steps: crushing, calcining, stripping, ball-milling, preparing a silicon-containing mixture, sol-gel, centrifuging, drying and the like. According to the method, the characteristics of components in the waste concrete blocks are reasonably utilized, the separated old hardened set cement is used as a silicon source to prepare the inorganic silica gel, the method has the advantages of being simple in process, low in synthesis temperature, low in energy consumption and environmentally friendly, and the prepared inorganic silica gel is large in specific surface area and uniform in pore structure; according to the method, the production cost is saved, the economic added value and the utilization rate of the waste concrete and the old hardened set cement are effectively improved, land r