Effect of microbial-cemented on mechanical properties of iron tailings backfill and its mechanism analysis

Abstract

In the traditional backfill mining engineering, cement cementation method is generally adopted, but it has high cost and emits a large amount of CO2, which aggravates the greenhouse effect. So that it is important to find a green and environmentally friendly cementing materials to replace cement cementation. Thus, in this paper, microbial induced carbonate precipitation (MICP) is an emerging technology used to assist in cementing iron tailings, and the strength differences between the blank group (CG) and the microbial-cemented iron tailings-based backfill (MIB) are compared, and the purpose is to study the effect of microbial-cemented on mechanical properties of iron tailings backfill and its mechanism analysis. In this study, unconfined compressive strength test, analysis of XRD, TG, SEM and other methods are used, and it is found that pH, inoculated-microbial quantity and curing time all have effects on the MIB. The main conclusions of this study are as follows: The strength of the backfill treated by MICP technology is 5.45–63.33 % higher than that of the CG, further, the optimal pH for microorganisms growth in the iron tailings backfill is 9, the optimal inoculated-microbial quantity is 4 mL when the curing time is 7 d and so on. Finally, the toxicity of MIB leaching is evaluated. The microbial-cemented technology used in this study can provide a test and scientific basis for the application of MICP technology in mining and materials science.