Abstract: In order to reduce the addition of bentonite，which is used for preparation of pellets using magnetite powder as main material，explore the application of low-grade bentonite in pellet industry.Influence of adding compound binder on quality of green pellet was investigated，using compound binder mixed with bentonite purified by hydrocyclones and organic binder CMC.The results show that Φ150 mm and Φ75 mm hydroclones in order，with classification pressure of 0.1 MPa and 0.2 MPa respectively，content of montmorillonite is enriched from 60.25% to 81.04% with yield rate of 60.93% and the recovery rate is 81.95%.When compound binder prepared with CMC dosage is 3% of purified bentonite，screw extrusion is 3 times.The matching ratio of binder in pellets can be reduced to 0.8%，the drop strength of green pellets is 5.2 times，explosion temperature is 475 ℃ and the compressive strength of green pellets is 12.85 N/P，which meet the property requirements of pellet.The use of compound binder to prepare pellets is beneficial to the energy saving，and is one of the development trends in pelletizing industry in the future.

Key words: Ca-bentonite, Purification, CMC, Compound binder