Method for preparing lithium orthosilicate by taking coal gangue as a raw material

The invention relates to a method for preparing lithium orthosilicate by taking coal gangue as a raw material. The method comprises the following steps: conducting pre-treatment such as calcination activation, pickling, suction filtration, water washing and drying on coal gangue; mixing the coal gangue with lithium carbonate according to the molar ratio n (Si4) : n (Li) = 1 : 3.8 to 4.2 in a solvent; removing the solvent; and conducting calcination on obtained solid mixture. As the coal gangue, which is solid waste, is taken as a raw material, the method has the advantages that the cost is reduced; and the carbon dioxide absorption effect of lithium orthosilicate obtained according to the method is better.