Geochemistry of Mine water and Tailing at Malanjkhand Copper Deposit

Abstract

The Malanjkhand porphyry copper deposit, located in Madhya Pradesh, is the largest copper mine in Asia. The detailed hydrogeochemical study indicates that mine discharges are highly acidic (3.4–4.4) with very high concentration of Cu (9.2–60.8 mg/L). The pH value of the tailing pond 2.39–2.48 and concentration of Cu 15.6–65.2 mg/L were measured. Groundwater is not polluted while the river downstream of mine is influenced by mine discharges. The water quality of the mine discharges and tailing is mainly affected by the oxidation of chalcopyrite, which present abundantly in the host rock along with minor amount of pyrite. Alpersite, gypsum, epsomite and hexahydrite occur as efflorescent salts during the summer time, and store very high concentration of metals. Alpersite contains Zn (285-391 mg/kg), Ni (62-78 mg/kg) and Cu (7.8-10.9%) whereas epsomite contains Zn (132-160 mg/kg), Ni (35-43 mg/kg) and Cu (3465-4184 mg/kg). Among trace elements in tailing Cu has the highest concentration range (98.2–4492 mg/kg) followed by Mn (131.4–760 mg/kg), Zn (54.3–241 mg/kg), Ni (25.7–170.3 mg/kg) and Pb (12.5–46.4 mg/kg). Tailing rich with efflorescent salt has maximum concentration of metals as well as maximum potential for releasing metals into the aqueous system.