Abstract: The disposal of uranium tailings underground filling is an important technical support of the uranium "synergetic mining" concept. However， the complex physical and chemical properties of the uranium tailings affect the consolidation and solidification of the cemented backfill， and further restrict the application of the cemented backfill technology of the uranium tailings aggregate. Based on the synergistic effect of characteristics of paste and geopolymer， aiming at problems existing in the surface stacking of uranium tailings and the conventional underground filling disposal， a scientific idea of underground filling based on the fragmentation and wrapping of geopolymer and the stable and cooperative solidification of paste is put forward. The technical indexes of the cemented uranium tailings backfill include mechanical strength， chemical stability， leaching resistance， radon exhalation rate and compatibilization characteristics. The materials composition includes uranium tailings aggregate， geopolymer cementitious material， mineral binder， admixture and water， etc.. The key technologies in the preparation and filling process are particle grading reconstruction of uranium tailings， multiple compounding of filling materials， in-situ monitoring and dynamic adjustment of filling quality. Taking tailings of a uranium tailings pond and compound smelting slag as the study objects， the verification test was carried out. When the backfill with water-solid ratio of 0.25 and cement-sand ratio of 1:4 was cured at (20±1) ℃ and humidity ≥ 95% for 28 days， the maximum uniaxial compressive strength of the specimen was 17.65 MPa， which indicated that the preparation of uranium tailings paste filling system based on geopolymer is feasible. The construction of this system is of certain significance to promote the application of paste filling technology in the field of low or very low level solid waste disposal.

Key words: Paste filling, Geopolymer, Uranium tailings, Synergetic effect, Underground filling