Mineralogical characterization related to physico-chemical conditions in the pyrite-rich tailings in Guryong Mine, Korea

Abstract The detailed characterization of mineralogical changes with depth in pyrite-rich tailings from an abandoned mine provides insight into the future geochemical progression of the tailings. Based on the pH and mineralogical characterization, the Guryong mine tailings can be divided into four zones: jarosite zone, iron (Fe)-sulfate zone, Fe-oxyhydroxide and gypsum-bearing pyrite zone, and calcite-bearing pyrite zone. The jarosite zone was approximately 50 cm deep from the surface and had secondary gypsum (CaSO4·2H2O) and jarosite [KFe3(SO4)2(OH)6]. The pH of the jarosite zone ranged from 2.3 to 4.0, and the ratio of total Fe to total sulfur (S) ranged from 0.7 to 4.3. These results show that the solid phase, schwertmannite or jarosite, is associated with the total sulfate (SO4) content. The Fe-sulfate zone had low pH values caused by strong pyrite oxidation and greatest amounts of the secondary minerals and acid-leachable heavy metals. The Fe-oxyhydroxide and gypsum-bearing pyrite zone reflects parti...