Device and method for preparing silica by taking sodium silicate as raw material

The invention discloses a device and a method for preparing silica by taking sodium silicate as a raw material, and relate to the preparation of silica. The device comprises a sodium silicate solution storage tank, a high-pressure carbonization reaction/aging kettle, a gas compressor, a heat exchanger, a check valve, a back pressure valve, a pumping, filtering and cleaning machine, a slurry preparation tank, a dryer, a carbon dioxide storage tank and a temperature control system. The method comprises the following steps: dissolving solid sodium silicate in water, filtering the obtained object, then adding water into the obtained product so as to obtain a sodium silicate solution, pumping the sodium silicate solution into the kettle, and feeding carbon dioxide into the kettle so as to obtain silica gel; controlling the temperature and carbon dioxide pressure in the kettle, carrying out aging and pore fixing on the obtained product and removing the pressure in the kettle so as to obtain saliferous silica slurry, then transferring the saliferous silica slurry to the pumping, filtering and cleaning machine to carry out solid-liquid separation, washing a filter cake by using water, detecting filter liquor by using a saturated barium hydroxide solution, stopping washing until no precipitation exists, and washing the filter cake by using anhydrous ethanol; and adding ethanol into the filter cake, and stirring the obtained product so as to prepare slurry, and then drying and crushing the obtained object so as to obtain silica. The process is simple, and a subtranslucent silica product with a high pore volume and a large specific surface area is obtained conveniently.