Method for purifying phosphogypsum by coupling sulfuric acid with silane coupling agent

The invention relates to a method for purifying ardealite by coupling sulfuric acid with a silane coupling agent, which comprises the following steps: grinding: grinding ardealite to obtain ore pulp A; flotation is conducted, specifically, a collecting agent and a foaming agent are added into the ore pulp A, flotation is conducted, and concentrate B is obtained; acid leaching: mixing, heating and stirring the concentrate B and a sulfuric acid solution to obtain ore pulp C; and removing silicon by using a silane coupling agent: filtering the ore pulp C to obtain filter residues, adding a silane coupling agent solution into the filter residues, stirring to react, filtering and drying to complete the purification of the ardealite. According to the method disclosed by the invention, the byproduct ardealite generated in phosphoric acid production by a wet process is taken as a raw material, the ardealite raw material with the whiteness of about 29% can be improved to an ardealite product with the whiteness of more