Method for producing building gypsum powder by utilizing papermaking residual liquid

The invention relates to a method for recycling papermaking residual liquid, in particular to a method for producing building gypsum powder by utilizing the papermaking residual liquid. The method disclosed by the invention has the advantages that a production mode which is simple in process, low in energy consumption, green and environment-friendly is provided; the production cost is low; the technical indexes such as strength, cohesiveness, flowability, setting time and the like of the gypsum powder are increased; and renewable resource is fully utilized. The technical scheme adopted by the invention comprises the following steps: taking the papermaking residual liquid as a raw material, mixing, desulfuring, drying, calcining and recovering finished products, wherein a fluidization operating principle and a powerful smashing and classifying device are adopted in the drying and the calcining steps of the invention; a controllable device is adopted to strictly control the calcining temperature and the calcini