Experimental study on solidification of tailings by MICP under the regulation of organic matrix

Abstract

Microbial grouting reinforcement technology can improve the strength of tailings to a certain extent, but there is still much room for improvement. To balance the adverse effects of the technology to cure the tailings, this paper introduced the mineralization technology of soft template into the microbial induced calcium carbonate precipitation (MICP), and carried out the experiments on microbial grouting to strengthen the tailings under the control of organic matrix. The results of aqueous solution test showed that the organic matrix can significantly regulate the structural characteristics of calcium carbonate. When the added organic matrix is egg white protein with a volume fraction of 20%, the contribution to the conversion rate of calcium ions in the reaction solution was the largest, and the concentration of calcium ions in the solution at 20 h is reduced by about 83.72% compared with the control group. In the solidification test of tailings, as the egg white concentration increased, the curing unevenness of the tailings was further aggravated. When the egg white volume fraction is 5%, the strength improvement effect of the tailings was the best and the dilatancy characteristic was the most significant. At the same time, the calcium carbonate produced are mostly large-sized calcite, and the corresponding formation amount, cohesive force and internal friction angle are 16.01%, 131.98 kPa and 42.7°, respectively. The study showed that mineralization technology of soft template can promote the MICP technology, which provides a new method for the reinforcement of tailings dam.