Abstract: There are large amount of phosphogypsum piled around Jinchuan Mine as waste rock，meanwhile the mining process of Jinchuan Mine have massive demand on cementing materials for backfilling.Early cementing materials are developed using phosphogypsum as main material，in order to reduce filling costs and convert the waste into valuable resources and improve mine environments.With the help of Scanning Electron Microscope (SEM)，the hydration mechanism of 3 d cementing materials based on phosphogypsum was analyzed.The experiment results indicated that，with the mass ratio of 4%，2%，30%,1.5%，early compressive strength of cementing material is 3.46，5.57，9.56 MPa respectively，higher than that of designed requirements.SEM analysis showed that the hydrated calcium silicate gel and ettringite play a decisive role in improving the strength of filling body，through hydration reaction of the cementing material based on phosphogypsum.Early strength cementing material made from phosphogypsum can replace the current 32.5# cement.

Key words: Phosphogypsum, Early strength cementing material, Backfill mining method, Compressive strength