Loop test study on the high-concentration cemented filling of full tailings

The high-concentration slurry prepared from full tailings used for mine backfilling can effectively eliminate the disasters caused by underground voids and tailing ponds. Using pipelines to transport filling slurry is the most efficient way, and the pipe resistance is one of the most important parameters. Presently, the loop test method for studying the pipe transportation parameters of filling slurry is closest to engineering reality. To determine the influence of the cement-sand ratio, concentration, and flow velocity of the high-concentration filling slurry prepared from full tailings on the pipe resistance and predict the resistance of industrial filling pipelines, pilot-scale loop tests were performed. A pipe resistance prediction model was established based on the relationship between the shear stress and the shear rate at the pipe wall. The gray correlation method was used to analyze the influence of various factors on the pipe resistance, and the rheological parameters of filling slurry were obtained by linear regression. The results show that the pipe resistance is most sensitive to the mass concentration of filling slurry and increases quadratically. The flow velocity of filling slurry has the second-greatest effect on pipe resistance, and the resistance increases linearly with flow velocity in laminar flow. The cement-sand ratio of filling slurry has a dual effect on the pipe resistance. When the cement-sand ratio is less than 1∶8, the cohesion effect of the cementing material is dominant and increases the pipe resistance. On the contrary, the lubrication effect of the cementing material is dominant and reduces the pipe resistance. The rheological parameters of filling slurry obtained by the loop test are much smaller than those obtained by the rheometer, and the loop test method is more reliable. The error of the pipe resistance prediction model is within 10%.