Mineralization performance and crystal characteristics of microbial induced carbonate precipitation in lead-zinc tailings under multiple factors

Exploring a low-cost and environmentally friendly cementation method to replace cement bond is a hot topic in tailings cementation backfills. In this study, microbially induced carbonate precipitation technology was used in tailings environment and the mechanisms of mineralization and precipitation of microorganisms were studied, including ambient temperature, pH, cementing solution concentration, and the ratio of bacteria to cement solution. The considered factors are based on tailings backfill site compared to the grouting method, the bacterial liquid and tailings were mixed only once to obtain enough calcium carbonate. The yield and surface morphology of crystal under different parameter conditions were obtained. The experiment results showed that temperature was the most critical factor controlling the yield and morphology of calcium carbonate crystals. The crystal productivity at 35 degrees C was 92.67%, which was 5.34-14.0% higher than that obtained at other temperatures. Compared with other temperature conditions, the crystal grain size was 2.03-5.57 & mu;m at 35 degrees C and the crystal structure was irregular and rough, which was more conducive to adhesion and bonding effect with other materials. The bacterium exhibited higher activity and a greater ability to precipitate crystals within the pH range of 6.0 to 8.0, while the environment at a pH of 9.0 had an obvious inhibitory effect on bacterial activity. There was an inversely proportional relationship between the cementing solution concentration and the amount of crystal precipitation. The utilization rate of bacteria and calcium ions reached the highest when the ratio of bacterial liquid to cementing solution was 1:1. The optimal experimental parameters were determined based on a comprehensive consideration of the crystal yield and experimental cost. The research process provided a theoretical basis for the application of microbial tailings backfill.