Light-weight refractory brick

The invention provides a light refractory brick, which consists of coal gangue calcined grog powder, cyanite powder, raw bauxite powder, hemihydrate gypsum, white cement and polyacrylamide. The addition proportion of the materials in weight portion is as follows: 58 percent of the coal gangue calcined grog powder, 10 percent of the cyanite powder, 25 percent of the raw bauxite powder, 2 percent of the hemihydrate gypsum, 4.94 percent of the white cement, and 0.06 percent of the polyacrylamide. The light refractory brick has the advantages of simple formulation, long service life, small aperture of the produced finished product, high hardness, good heat-resistant performance, and low production cost by using the grog powder calcined by coal gangue as the main material, and certain significance for comprehensive utilization and sustainable development.