Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

This study has focused on the mineralogical and geochemical characteritics of evaporites from the mine waters and on the variation of constituents in mine water during the evaporation. The evaporites are frequently observed at the rock surfaces contacting mine water. In order to produce evaporites in the laboratory, mine waters were sampled from the abandoned mine areas(HS, LG and BJ) and air-dried at room temperature. During the evaporation of mine waters, TDS, EC values and the concentrations of major and minor ions increased, whereas dissolved oxygen(DO) values decreased with the time. The concentration of Fe increased gradually with evaporation time in the BJ and LG, whereas its relatively high founded in early time but rapidly not detected in the end of time due to removal Fe by formation-adsorption-precipitation of amorphous Fe hydroxide in the HS. Gypsum, epsomite, kaolinite, dolomite and illite were identified in the BJ sample, gypsum and epsomite were observed in the LG sample, and gypsum, epsomite and vermiculite were founded in HS sample by x-ray powder diffraction studies. The infrared spectra for evaporites show major absorption band due to OH stretching, adsorbed molecular water and sulfate stretching, respectively. Evaporites were heated at 65, 150, 250 and 350℃ for one hour in electrical furnaces. Gypsum was transformed into the bassanite at 150℃ and epsomite was transformed into the hexahydrite at 65℃, and then converted into the kieserite at 250℃. With increasing heating temperature, the intensity of absorption OH band(3407.11cm-1), adsorbed molecular water band(1654.39cm-1) and sulfate stretching band(1113.46cm-1) decreased, whereas sulfate stretching bands(668.35cm-1and 603.85cm-1) relatively increased in IR due to dehydration. In the SEM and EDS analysis for the evaporite, gypsum of well-crystallized, acicular, and columnar shapes were observed in HS samples and kaolinite of plate, flakes and hexagonal shapes were distinctly observed in BJ samples, and epsomite of sub-rounded shapes were observed in LG samples.