The large storage of iron tailings not only causes environment pollution，but also has the risk of geological disasters.It can be used as paste filling material aggregate，which can solve the harm of tailings and ensure the safety and stability of underground stope.The Waitoushan iron mine adopts filling method.The filling material is composed of iron tailings，cement and water and the filling slurry has a mass concentration of 68%，which belongs to cemented filling with low-concentration whole tailings.Due to the low mass concentration of filling slurry， the whole tailings of iron tailings are coarse.Fine particles such as cement in the slurry are easily lost，which are not only waste cementing materials and affect the strength of the filling body，but also seriously pollute the underground environment.The filling material composition is fixed，and other admixtures and additives are not added，so the filling structure of the mine is single.Aiming at the problems of waste of filling materials and single filling structure in Waitoushan iron mine，the basic properties of Waitoushan iron tailings were studied by relevant tests.The test shows that the iron tailings have a large proportion，a small content of fine particles and poor gradation，so it is not suitable as paste aggregate alone.The fly ash was selected as admixture to supplement the fine particles in the iron tailings.The content of fly ash increased from 0 to 15% in a gradient of 2.5%，and the mass concentration of slurry was 72%，the paste filling material was prepared by mixing all materials.The slump，compressive strength，porosity and water absorption of filling materials with different fly ash content were tested.The results show that with the increase of fly ash content，the slump of slurry increases from 180.2 mm to 240.2 mm，the porosity decreases first and then slightly increases，and the water absorption rate increases.The unconfin compressive strength of filling material specimen could reach 1.359 MPa in 28 days.The results show that the fluidity and unconfined compressive strength of paste filling materials can be improved by adding fly ash，but the amount of fly ash should be no more than 12.5% of the solid mass.The results provide theoretical support for other metal mines to improve the filling structure.

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http://www.goldsci.ac.cn/article/2022/1005-2518/1005-2518-2022-30-5-724.shtml