Continuous Extraction and Continuous Backfill Mining Method Using Carbon Dioxide Mineralized Filling Body to Preserve Shallow Water in Northwest China

Yujun Xu, Liqiang Ma, Ichhuy Ngo and Jiangtao Zhai
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Yujun Xu: Key Laboratory of Deep Coal Resources Mining, China University of Mining and Technology, Ministry of Education, Xuzhou 221116, China
Liqiang Ma: Key Laboratory of Deep Coal Resources Mining, China University of Mining and Technology, Ministry of Education, Xuzhou 221116, China
Ichhuy Ngo: Key Laboratory of Deep Coal Resources Mining, China University of Mining and Technology, Ministry of Education, Xuzhou 221116, China
Jiangtao Zhai: Key Laboratory of Deep Coal Resources Mining, China University of Mining and Technology, Ministry of Education, Xuzhou 221116, China

Energies, 2022, vol. 15, issue 10, 1-24

Abstract: The exploitation and utilization of coal resources are not only prone to causing water table lowering, but also produce a large amount of CO 2 and coal-based solid waste. A scientific concept that employs the CO 2 and solid wastes to develop filling bodies and inject them into the mined-out area, to sequestrate CO 2 and mitigate the overburden migration and thus preserve the overlying aquifer, is proposed. Continuous extraction and continuous backfill (CECB) mining was selected as the mining method to meet the aforementioned objectives. Additionally, carbon dioxide mineralized filling body (CMFB) under ambient temperature and pressure was developed, with fly ash as aggregate, and CO 2 gas, silicate additives and cement as accessories. The uniaxial compressive strength (UCS) and tensile strength of CMFB with various curing times and fly ash contents were tested indoors. A physical analogue simulation and FLAC 3D numerical calculation were then successively implemented on the premise of determining a similar material ratio of CMFB in analogue simulation and calibrating the parameters of the CMFB in numerical simulation. The deformation of aquifuge and water level lowering while using CECB and CMFB with various proportion of fly ash were obtained. When using the CMFB with 75% fly ash content and 28 d curing time, the maximum values of vertical displacement, horizontal displacement, inclination, horizontal deformation and curvature of aquiclude were 26 mm, 6.5 mm, 0.12 mm/m, 0.08 mm/m and 0.0015 mm/m 2 , respectively, and the water table decreased 0.47 m. The results show that the CMFB with 75% fly ash is the most appropriate ratio to realize water preservation mining, CO 2 sequestration and harmless treatment of solid wastes, contributing to the green and sustainable development of coal areas.

Keywords: continuous extraction and continuous backfill (CECB); water preservation coal mining; carbon dioxide mineralized filling body (CMFB); aquifuge deformation; shallow water level lowering (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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