Study of arsenic mobility from arsenopyrite circum-neutral weathering

ENVR 45

Roel Cruz, rcruz@uaslp.mx, Rene Lara-Castro, and Marcos Monroy, monroyma@uaslp.mx. Area de Ingenieria de Minerales, Instituto de Metalurgia, Universidad Autónoma de San Luis Potosí, Av. Sierra Leona 550, Col. Lomas 2a sección, San Luis Potosí, 78210, Mexico
Arsenopyrite (FeAsS) is the most important source of arsenic in ores and polluted soils. Particles of this mineral are exposed to weathering if non-controlled conditions are imposed. The characteristics of the mining sites polluted by arsenic in Mexico are semi-arid climate and circum-neutral carbonate-rich soils. In despite of these conditions, an important alteration of arsenopyrite has been observed, as well as an important arsenic mobility. The aim of our study is to establish the arsenopyrite alteration mechanisms and the effect of the superficial mineral state on the arsenic anion stability under the above described conditions. For this, a methodology based on the combination of electrochemical, geochemical and spectroscopy studies is being applied to arsenopyrite samples collected from the mining site.