Method for evaluation of the cleanliness grade of coal resources in the Huainan Coalfield, Anhui, China: a case study

Abstract

Based on analysis of a large data set and supplementary sampling and analysis for hazardous trace elements in coal samples from the Huainan Coalfield, a generalized contrast-weighted scale index method was used to establish a model to evaluate the grade of coal cleanliness and its regional distribution in the main coal seam (No. 13-1) The results showed that: (1) The contents of Cr, Mn and Ni in the coal seam are relatively high and the average values are greater than 20 μg/g. The contents of Se and Hg are at a high level while most other trace elements are at normal levels. (2) The cleanliness grade of the coal seam is mainly grade III–IV, which corresponds to a relatively good-medium coal cleanliness grade. However, some parts of the seam are at grade V (relatively poor coal cleanliness). (3) Coal of relatively good cleanliness grade (grade III) is distributed mainly in the regions corresponding to the Zhuji-Dingji-Gubei coal mines and in the eastern periphery of the Panji coal mine. Coal of medium cleanliness (grade IV) is distributed mainly in the regions of the Panji-Xiejiaji and Kouzidong coalmines. Relatively poor grade coal (grade V) is distributed in the southwest regions of the coalfield and the contents of Cr, As and Hg in coal collected from the relatively poor coal cleanliness regions often exceed the regulatory standards for the maximum concentration limits.

Prediction of Water-Blocking Capability of Water-Seepage-Resistance Strata Based on AHP-Fuzzy Comprehensive Evaluation Method—A Case Study

“…Furthermore, different from the traditional evaluation of the WBC of an aquifuge, from the perspective of the mining-induced permeability deterioration rate of the overburden, the concept of "three seepage zones" is firstly put forward in this paper, and the scientific connotations of the nominal WSRZ (after coal extraction), which is important for WPCM, are systematically defined. Additionally, the concept of WSRS (before mining) is proposed, and it is classified into five various types on the basis of the initial permeability, thickness, strength, porosity and the stratigraphic structure of the WSRS [75]. The influence mechanism of the type of WSRS on the vertical level and thickness of the nominal WSRZ is revealed.…”

Prediction of the Adaptability of Using Continuous Extraction and Continuous Backfill Mining Method to Sequestrate CO2-A Case Study

“…The adaptability of this concept is investigated, to generalize and apply this method in the future. For common CO 2 sequestration methods, the supercritical CO 2 is injected into the subsurface structures such as abandoned oil reservoirs, deep saline aquifers, un-minable coal seams and so forth [55][56][57]. However, CO 2 may leak and escape into the air again while being confronted with large disturbances of the overlying strata.…”

Groundwater pollution and human health risk based on Monte Carlo simulation in a typical mining area in Northern Anhui Province, China

“…In recent years, investigations by researchers suggest that certain coal mines are facing a water shortage and chemical contamination. The fly ash and coal cinder from coal-mining activities are laden with toxic trace elements and easily enter groundwater via runoff and infiltration (as well as other forces) during coal washing and coal cinder stacking-finally causing surface water pollution and shallow groundwater pollution (Wang et al 2019;Long and Luo 2020;Hu et al 2021). Moreover, excessive midlayer groundwater exploitation causes a decline in water levels as well as an increase in the water level difference between the shallow and mid-layer groundwater bodies.…”