High-air-permeability green sand for magnesium alloy casting and preparation method of high-air-permeability green sand

The invention relates to the technical field of casting materials, and discloses high-breathability green sand for magnesium alloy casting and a preparation method of the high-breathability green sand. The magnesium alloy casting sand is prepared from the following components in parts by weight: 50-70 parts of magnesium alloy main molding sand (the magnesium alloy main molding sand comprises 20-30 parts of quartz sand, 10-20 parts of red sand, 3-6 parts of alkyl sodium sulfonate, 0.5-1.5 parts of boric acid, 0.5-2 parts of sulfur, 60-70 parts of recycled old sand and the balance of water), 30-50 parts of magnesium alloy auxiliary sand (the magnesium alloy auxiliary sand comprises 45-55 parts of coarse quartz sand, 40-50 parts of fine quartz sand, 5-10 parts of ceramsite and 0.5-1.5 parts of bentonite), 3-6 parts of alkyl sodium sulfonate, 0.5-1.5 parts of boric acid, 0.5-2 parts of sulfur and the balance of water); the original performance of the magnesium alloy molding sand is guaranteed, after the magnesium