Optimization research of base-phosphogypsum cemented backfill ratio based on orthogonal test

The filling technology of phosphogypsum as aggregate is one of the treatment methods of goaf and solid waste, and phosphogypsum's chemical activity is the key to affect the filling effect. Taking phosphogypsum filling to be carried out in a mine as the object,and the base in quicklime was used as an activator. According to the orthogonal experiment method, 16 groups of ratios were designed to carry out combined experiments. The range method was used to analyze the optimal ratio under each index (slump, 3 d compressive strength, 7 d compressive strength and 28 d compressive strength), and the matrix analysis method was used to analysis and optimize to obtain the feasible optimal ratio, and the index value prediction method was used to predict the mechanical characteristic value of the final ratio. The results indicate that: 1) The content of phosphogypsum is the first main influencing factor under various indexes, and the second main influencing factors for the three indexes of slump, 3 d strength and 7 d strength next time are the slurry concentration. Under the 28 d strength index, the second main influencing factor is lime content. 2) The final parameters of the optimally selected backfill are as follows: phosphogypsum of 20%, cement to tailings ratio of 1:6, slurry concentration of 80%, and quicklime of 1%. Its estimated values of mechanical properties are slump of 10.1936 cm, 3 d strength of 0.6108 MPa, 7 d strength of 1.2734 MPa, 28 d strength of 2.5748 MPa. 3) The influence relation model of different factors is established. The relationship between various index values (slump, 3 d strength and 7 d strength) and the main influencing factors are in accordance with the relationship of Z=Ax2+By2+Cx+Dy+Exy+F. © 2021, Science Press. All right reserved.