Hydrogeochemical Characteristics and Groundwater Inrush Source Identification for a Multi-aquifer System in a Coal Mine

Correct identification of water inrush sources is particularly important to prevent and control mine water disasters.Hydrochemical analysis,Fisher discriminant analysis,and geothermal verification analysis were used to identify and verify the water sources of the multi-aquifer groundwater system in Gubei coal mine,Anhui Province,North China.Results show that hydrochemical water types of the Cenozoic top aquifer included HCO3-Na+K-Ca,HCO3-Na+K-Mg and HCO3-Na+K,and this aquifer was easily distinguishable from other aquifers because of its low concentration of Na++K+and Cl-.The Cenozoic middle and bottom aquifers,the Permian fissure aquifer,and the Taiyuan and Ordovician limestone aquifers were mainly characterized by the Cl-Na+K and SO4-Cl-Na+K or HCO3-Cl-Na+K water types,and their hydrogeochemistries were similar.Therefore,water sources could not be identified via hydrochemical analysis.Fisher model was established based on the hydrogeochemical characteristics,and its discrimination rate was 89.19%.Fisher discrimination results were improved by combining them with the geothermal analysis results,and this combination increased the identification rate to 97.3%and reasonably explained the reasons behind two water samples misjudgments.The methods described herein are also applicable to other mines with similar geological and hydrogeological conditions in North China.

Working principle and application of HEMS with lack of a cold source

With the increase of mining depth, the temperature of the original rock in deep mines increases. High temperature heat hazards at working surfaces and driving faces are becoming increasingly more serious. Given the problem of mine cooling technologies at China and abroad and the actual conditions of a coal mine, we developed HEMS （High Temperature Exchange Machinery System） with inrushing mine water as the source of cold energy. Combined with the characteristics of a shortage of inrushing water in the coal mine, we proposed the Sanhejian model of HEMS with its lack of a cold source. The cooling engineer- ing construction, given the present conditions in the Sanhejian Coal Mine, consisted of two phases. In phase 1 horizontal water circulation was used as cold energy, while phase II was the geothermal utiliza- tion project. For the key equipment of HEMS-PT or HEMS-T, we provided the operational principle from theory and an actual application. Finally, we analyzed the operational effect of HEMS. After cooling, the temperature at the working face was below 30 ~C, which meets the national regulations. This system opens up new technology to solve the problem of deep mine heat hazards, which makes good sense in energy conservation and pollution reduction, improves the environment and realizes sustainable eco- nomic development.