State Key Laboratory of Coal Resources and Safe Mining, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China; School of Mines, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China.
State Key Laboratory of Coal Resources and Safe Mining, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China; School of Mines, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China.
Sci Total Environ. 2021 May 20;770:145241. doi: 10.1016/j.scitotenv.2021.145241. Epub 2021 Jan 20.
Solid-waste coal gangue (CG) mixed with cement as underground backfilling material is widely applied in coal mines throughout China. However, this material can pollute the environment during its production, preparation, and transportation, which is mainly caused by cement. As a cement-free eco-friendly technology, microbially induced carbonate precipitation (MICP) technology can produce biomineralization products to consolidate loose grains, and the microbial growth environment is adapted to underground temperature with no pollution. To this end, this study gets the Bacillus pasteurii with special resistance by strain domestication, proposes a CG-based bio-mineralized underground backfilling material without using cement, and analyses the characteristics of it from macro- to microscopic perspectives by dissolution test, scanning electron microscopy (SEM), Energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results indicate that strain domestication leads to B. pasteurii, which can withstand CG leaching solution and 1 M urea simultaneously. This satisfies the basic requirements of CG based mineralized material. Through the circulation perfusion method, the intact CG based biomineralized specimens are obtained. Macroscopically, the bacteria bind gangue grains into a whole with high biomineral content (11.66%). The utilization rate of mineralizing solution is up to 66.82% which makes good use of raw materials. Microscopically, a new crystal formation is observed, and CG particles are consolidated well where the crystals precipitate to fill the pores and bind the particles together. Hence this method has a significant influence on the deposition of biominerals. Meanwhile the biomineralization improves the microstructure considerably and bonds the CG particles as a whole. A comprehensive analysis of the test results shows that, from an environment viewpoint, the preliminary study of new CG based bio-mineralized material is successful.
矸石-水泥固废胶结材料在我国煤矿地下充填中得到了广泛的应用。然而，该材料在生产、制备和运输过程中会对环境造成污染，主要是由水泥引起的。微生物诱导碳酸钙沉淀（MICP）技术是一种无水泥的环保技术，可以产生生物矿化产物来固结松散的颗粒，并且微生物的生长环境适应地下温度，不会造成污染。为此，本研究通过菌株驯化获得了具有特殊抗性的巴氏芽孢杆菌，提出了一种不使用水泥的基于矸石的生物矿化地下充填材料，并从宏观到微观角度通过溶解试验、扫描电子显微镜（SEM）、能谱分析（EDS）和 X 射线衍射（XRD）分析了其特性。结果表明，菌株驯化使巴氏芽孢杆菌能够同时耐受矸石浸出液和 1 M 尿素，这满足了基于矸石的矿化材料的基本要求。通过循环灌注法，获得了完整的基于矸石的生物矿化试件。宏观上，细菌将矸石颗粒与高生物矿化含量（11.66%）的整体结合在一起。矿化溶液的利用率高达 66.82%，充分利用了原材料。微观上，观察到一种新的晶体形成，矸石颗粒得到了很好的固结，晶体沉淀填充了孔隙并将颗粒结合在一起。因此，该方法对生物矿化的沉积有显著影响。同时，生物矿化大大改善了微观结构，并将矸石颗粒整体结合在一起。综合分析试验结果表明，从环境角度来看，新型基于矸石的生物矿化材料的初步研究是成功的。
