Method for preparing silicon carbide by using composite insulator

The invention discloses a method for preparing silicon carbide by using a composite insulator, and relates to the field of silicon carbide. Comprising the following steps: (1) mixing a composite insulator thermal degradation solid-phase product, graphite and a catalyst, then putting the mixture into ball-milling equipment, setting the ball-milling time to be more than 12h and the ball-milling rotating speed to be more than 400r/min, and carrying out ball-milling to obtain a ball-milled mixture; and (2) carrying out thermal reaction on the ball-milled mixture in an oxygen-isolated gas atmosphere at the thermal reaction temperature of 1000-1200 DEG C for 30-90 minutes to obtain the silicon carbide powder after the reaction is finished. The silicon carbide synthesis reaction temperature is reduced to 1200 DEG C or below, the decommissioned composite insulator pyrolysis product is adopted as the raw material, the reaction temperature and raw material requirements are reduced, economic benefits are remarkably impr