Preparation method of polyaluminum chloride

The invention discloses a preparation method of polyaluminum chloride. The preparation method comprises the following steps: (1) adding 60-70 parts by weight of hydrochloric acid into a dosing kettlethrough a metering pump and stirring the hydrochloric acid; (2) inputting 30-38 parts of aluminium hydroxide into the dosing kettle and uniformly stirring the mixture to form a solution; (3) transferring the solution in the step (2) to a reaction kettle through compressed air, raising the temperature for polymerization reaction, reducing the temperature after the reaction, and transferring the solution to a filter pressing tank through the compressed air; (4) introducing the compressed air into the filter pressing tank to press the solution into a plate-and-frame filter press for solid-liquidseparation to obtain a liquid product; and (5) feeding the liquid product in the step (4) into a pressure spraying and drying system, and spraying and drying the liquid product to obtain a solid product, that is polyaluminum c