High-strength precoated sand with excellent fluidity and preparation method thereof

The invention belongs to the field of precoated sand, and particularly relates to high-strength precoated sand with excellent fluidity and a preparation method thereof. The preparation method comprises the following steps: mixing crystalline flake graphite, silicon powder and a silane coupling agent, and stirring at a high speed to obtain a flow promoter; silica sand is ground, boric acid is added during grinding, and pretreated silica sand is obtained after grinding is completed; the pretreated silica sand is heated, then phenolic resin, a flow promoter, a urotropine aqueous solution and calcium stearate are sequentially added under the stirring condition, and the high-strength precoated sand with the excellent flowability is obtained after completion. According to the method, the roughing sand is pretreated, so that the strength of the precoated sand can be improved at low cost; in addition, the flowability of the precoated sand is improved by adding a flow promoter, and finally the precoated sand with flow