煤矿用微生物胶结充填材料固化机理与多尺度性能研究

Cemented backfill mining technology is an important ground control method for coal mining. Currently, the most popular binder in the backfill material is cement or cement-based material which has a number of disadvantages, such as high cost, high pH, high energy consumption and high carbon emission. In this project, microbial induced carbonate precipitation (MICP) technology is used as the binder to replace the cement in the backfill material. The curing mechanism of microbial cemented backfill (MCB) in coal mines and its multiscale performance are studied in this project with a series of research methods, such as field measurement, lab test, data mining and numerical simulation. Firstly, the internal environment of the cemented backfill slurry and backfill stope are measured, and the effects of commonly used urease producing microbes by MICP in this backfill environment are compared by measure the urease activity and carbonate precipitation capacity. The appropriate microbe and calcium sources are chosen for the cemented backfill and the curing mechanism of MCB is studied. Secondly, main influence factors on the multiscale performance of MCB are selected, the test scheme is designed based on these variables. The rheological and mechanical properties of MCB in different scales are tested and analyzed. Finally, the MCB samples with optimal ratio are cured in the simulated environment of backfill stope and its performance are measured and evaluated. Based on the test results, the monitoring and evaluating methods of MCB’s performance are proposed. The research findings will diversify the backfill material and provide the theoretical foundation to develop the MICP backfill mining technology.

煤矿胶结充填开采技术是一种重要的岩层控制方法，目前所用的胶结料主要是水泥或水泥基材料，存在成本高、碱性强、耗能和排放高等问题。本项目针对充填材料性能优化这一科学问题，提出利用微生物诱导碳酸钙沉积（MICP）技术实现煤矿胶结充填材料固化的思路，采用现场实测、室内试验等综合手段，研究煤矿微生物胶结充填材料的固化机理和多尺度性能。首先，分析煤矿胶结充填料浆和充填开采采场的内部环境，选择可实现胶结充填材料固化的微生物和钙源，研究微生物胶结充填材料的固化机理；其次，筛选微生物胶结充填材料性能的主要影响因素，设计试验研究主控因素作用下材料多尺度流动和承载性能的变化规律；最后，优化设计微生物胶结充填材料配比，测试材料在采场环境下的性能表现，建立材料性能的监控与评价方法。项目的研究成果将丰富胶结充填材料的类型，为MICP胶结充填开采技术的发展提供理论支撑。

项目立足于国家绿色低碳发展的重大需求，针对煤矿充填开采中传统水泥基胶结料高成本、高耗能和高排放的问题，提出利用微生物诱导碳酸钙沉积（MICP）技术实现煤矿胶结充填材料固化的思路。项目采用现场实测、室内试验、数据分析等综合方法，研究了煤矿微生物胶结充填材料的固化机理和多尺度性能。分析了煤矿胶结充填材料料浆内部环境，得出充填料浆为强碱富含多种离子的化学环境，选择巴氏芽孢杆菌作为制备胶结充填材料的微生物，采用氯化钙和乙酸钙等作为钙源，研究钙源浓度、营养盐用量、酶活、骨料粒径等因素对微生物胶结充填材料固结的影响规律。筛选微生物胶结充填材料性能影响因素，针对多尺度条件下微生物胶结充填材料进行力学试验，测试微生物胶结充填材料的性能，测得灌注型微生物胶结充填材料强度可达25.12MPa，拌和型材料的强度为1.20MPa。分析了微生物胶结充填材料内部碳酸钙矿物晶体的晶型、尺寸、位置和分布，得出微生物代谢生成的方解石和球霰石是影响微生物胶结充填材料力学性能的关键因素，从微观矿物尺度揭示了微生物胶结充填材料的固结机理。优化设计了微生物胶结充填材料配比，建立了材料性能监控与评价方法，揭示了微生物胶结充填材料生命周期碳排放和能耗对环境的影响，得出在不可再生资源消耗方面，MICP比水泥、石灰和烧结砖有一定的优越性。综合微生物胶结充填材料的性能和制备工艺，提出了巷式拌和型和巷式灌注型两种微生物胶结充填开采技术思路。相关研究成果获得教育部科学技术二等奖1项，煤炭青年科技奖1项，发表学术论文9篇（SCI收录6篇、EI收录3篇），申请专利7件，获授权发明专利2件，实用新型专利1件，培养硕士研究生2名。项目研究成果可丰富胶结充填材料的类型，推动MICP技术在矿业工程领域的发展，为煤矿微生物胶结充填开采技术的发展提供理论支撑，具有广阔的推广应用前景。