Geochemistry Effkt Of Gangue Leaching And Its Potential Risk

A serious chemical and physical changes occur after the coal gangue contact with theleaching,and which then produce various components of the solution. Elements componentcategory and content will differ from different extract liquid pH、different weathered degreeof the gangue、different medium, the leaching process will be affκted by various factors also,the complex composition of the leaching and the harmful elements released in other waysWill be bad for the environment. At present, the research of the phenomenon ofenvironmental pollution by coal gangue is relatively common,but the study of the process ofthe harmful elements release、 the chemical leaching mκhanism and the water-rockinteraction is rarely, So it is nκessary to strengthen these areas scientific research.This paper is ground on the item of National Natural Science Fund "Geochemicalbehavior and environmental effκt of potential acid released by coal gangue”(Projκt No.is41002086). The author assessed assessed Sangshuping and Xiayukou coal mine in Hancheng,Shaanxi Province and revealed the coal gangue leaching mκhanism. The results of soakingand leaching experiment were analyzed by means of field monitoring、collκt samples、laboratory tests and the geochemical modeling，and meanwhile we have analyzed thehydrochemical type of the leaching liquid.Which had lay the scientific foundation forutilization and treatment of the gangue. In this paper, the conclusions of the study are asfollows:1. The leaching of gangue is alkalescent, and the pH is7.0~8.0,which mainly due to thealkaline oxide in the coal gangue has dissolved. In the process of leaching, carbonic acidsystem has played a buffer role, keeping solution in a certain acid range.2. immersed liquid pH is fixed, the ion concentration is much affκted by the liquid-solidratio in the soaking experiment (except CO32-). When the leaching time was same, if liquid tosolid ratio is bigger, the ion leaching concentration with is smaller.3.Compared with fresh coal gangue, the higher degree of the weathering coal gangue, thelower the pH of the lixivium from the coal gangue. The concentrations of K+, Ca2+, Mg2+, Cl-,HCO3-, SO42-are higher in the lixivium of the weathered Gangue, and the sequence of thehigher amplitude is Mg2+> K+> SO42-> Cl-> CO32-> Ca2+> HCO3-,but the sort concentration ofNa+has dropped dramatically, bκause the salt is easily dissolved, the salt has been dissolvedearly in the prosess of gangue weathering, and then with the prκipitation come into theenvironment. 4. Flowing through the loess medium,cations and antions have dκreased in the leachate.Maybe bκause the cations and antions are adsorbed by loess, which proving the loess is inhigh absorption ability，and the phenomenon also be a reflκtion of the enrichment level ofmetal elements of the loess medium. But after flowing through the loess medium,theconcentration of cations and cations in the the leachate are increased,which may be duo to thedissolution of corresponding minerals in the silty sand.5. In the leaching process, the saturation index of mineral has increased at differentdegree via phreeqc simulation. In addition to the rock salt(the major ingredient is NaCl), thesaturation index of all minerals are greater than zero, Which conformed that minerals are insupersaturated state, only rock salt saturated index is still less than zero, that could continue todissolve.6. Contacting the the hydro-geological conditions of the Hancheng, according to thechemical composition of groundwater classification chart of A.M.OBЧИΗΗИкOB, the authorhave judged the type of the leaching solution and the leachate from the gangue. Andaccording to the type number, the cations in the tolal cation concentration and the antions inthe tolal antion concentration percentage range have been fixed.