Pasivos ambientales mineros en el noroeste de Argentina: aspectos mineralógicos, geoquímicos y consecuencias ambientales

Abstract

In northwestern of Argentina, the Puna region reaches 3700 m a.s.l. and is characterized by arid\nconditions with high temperature fluctuations and strong winds. In the Puna, there are primary sulfides\nmining exploitations that ceased their activity twenty years ago without a state-of-the-art closure plan. In\nthe abandoned mines, waste rock and tailing impoundments are rich in pyrite and sulfide and are exposed\nto weathering, which negatively impacts the quality of water, vegetation, soil and air. Herein, we present the results of the study of three abandoned mines from northwest Argentina: La Concordia, La Poma, and\nPan de Azúcar. Superficial water, tailing sediments, soils, vegetation and efflorescent salts were sampled\nand analyzed. They show evidence of advanced Acid Mine Drainage process (AMD). Experimental data\nof analogue rain-water behavior show a fast pH drop, and dissolution of heavy metals, when water and\ntailing impoundment sediments are mixed. During the dry season, infiltrated water oxidizes the sulfide\nminerals in the tailings, and efflorescent salts precipitate from the tailings pore water capturing heavy\nmetals, whereas in the raining season, salts are solubilized as well as some metals. The environmental\ndamage will continue if remediation actions are not implemented.