Chemical Characteristics And Genesis Mechanism Of Mine Water In Xinjulong Coal Mine

The TDS of groundwater in Shandong Juye coalfield is high,and the water quality is poor,which leads to the high salinity of mine water and water treatment is difficult.Study the chemical characteristics and genetic evolution mechanism of groundwater and mine water in this area,which has scientific and application support to study the migration law of mine water pollution in coal mining area and explore the method of governance from the source of mine water formation.Based on the National Key R&D Program of China:“groundwater pollution prevention and control materials and technology in coal mining area”,this paper takes groundwater and mine water in Xinjulong coal mining area as the research object.The chemical characteristics and genetic evolution mechanism of groundwater and mine water in the study area are analyzed and studied by means of data collection,field sampling,water chemical analysis test,mineral composition detection of aquifer rock group,laboratory simulation test and hydrogeochemical simulation.The main conclusions are as follows:(1)The p H value of groundwater in the study area is 6.50?9.68,which is neutral and alkaline,and the salinity is high,reach 3?9 g/L.It belongs to the category of saline water,and the vertical distinction is obvious.The deep water quality is slightly better than that in the shallow part.The hydrochemical types are mainly SO₄-Na and SO₄-Na·Ca.The deep limestone aquifer is obviously disturbed by mining.Some hydrochemical types become SO₄-Ca·Na and SO₄·HCO₃-Na,but still dominated by SO₄-Na.(2)The hydrodynamic conditions of groundwater in the study area is poor,and the aquifer temperature is 43?54°C.The long-term high temperature water-rock interaction,dissolution and evaporation are the main reasons for the high TDS of groundwater in the study area.The occurrence environment of deep Ordovician limestone water is uneven,and the hydrochemical environment and water quality are obviously different.Under the influence of mining disturbance,the hydrochemical characteristics and evolution mechanism of groundwater have changed.The PHREEQC reverse hydrogeochemical simulation results show that a large number of sulfate minerals are dissolved in Neogene aquifer and roof and floor aquifer of No.3coal in Shanxi Formation.There is a certain degree of oxidation in the third layer limestone aquifer of Taiyuan Formation and Ordovician limestone aquifer,but the effect is less than that of reverse cation alternating adsorption and sulfate mineral precipitation.(3)The pH value of mine water is 6.80?8.40,the neutral is slightly alkaline,and the salinity is high affected by groundwater.TDS of mine water from the aquifer of No.3 coal in Shanxi Formation or the third layer limestone aquifer is lower than that of groundwater,and TDS of old goaf water is higher.The reverse hydrogeochemical simulation of mine water was carried out by PHREEQC.The results show that the positive cation alternate adsorption and sulfate mineral precipitation are significant in the formation process of mine water from roof and floor aquifer of No.3 coal in Shanxi Formation and the third layer limestone aquifer of Taiyuan Formation with single source,and the water quality is optimized.In the long-term water-rock(coal)interaction,the water quality of the old goaf water is poor due to the alternating adsorption of oxidation and reverse cation.(4)The mine water was discharged to Zhushui River at 300 m³/h,more than 50%of downstream river flow.The metal elements and toxic substances detect met the emission standards,but increase the content of Li,Mn and Sr in the downstream water.The TDS value of the water at 165m downstream of the drainage outlet is higher than that at 610m upstream.(5)Laboratory water-rock experiments show that the dissolution and precipitation of minerals are the most significant during the hydrochemical evolution process.HCO₃^-,Ca²⁺and Mn are easily dissolved in sandstone,SO₄^2-,Ca²⁺,Mg²⁺and Sr are easily dissolved in limestone,SO₄^2-,Na⁺and Sr are easily dissolved in coal,water-rock interaction is the basis for the formation of groundwater.The participation of coal and gangue is an important factor affecting mine water quality.Mineral dissolution,cation exchange adsorption and redox not only affect the changes of water chemical components,but also affect the acidity and alkalinity of water and redox environment.This thesis has 59 pictures,33 tables,and 104 references.