Preparation method of phosphogypsum-based filler for waterborne oil paint

The invention discloses a preparation method of phosphogypsum-based filler for a waterborne oil paint. The preparation method comprises the steps: adding phosphogypsum and water into a stirrer for stirring; after ending the stirring, pouring out and standing the mixed material, and carrying out water-material separation after standing; extracting a solid material at a lower layer to obtain purified phosphogypsum; drying the purified phosphogypsum to obtain dried phosphogypsum; calcining the dried phosphogypsum, carrying out cooling after calcining, and carrying out ageing after cooling; mixingthe aged phosphogypsum with water to prepare slurry, adding an organic silicon water repellent into the slurry, then, carrying out stirring, and carrying out drying after stirring to obtain modifiedcalcined phosphogypsum; and grinding the modified calcined phosphogypsum by using a ball mill to obtain the phosphogypsum-based filler for the waterborne oil paint. The phosphogypsum is used as the main raw material, so that t