Metalloid Attenuation from Runoff Waters at an Historic Orogenic Gold Mine, New Zealand

摘要: The metalloids arsenic and antimony are mobilised through the decomposition of arsenopyrite, pyrite, stibnite at historic Big River Mine. Their content in solid substrates reach levels up to ≈25 wt% As 3.6 Sb, but their concentrations mine water only elevated locally, 0.85 mg/L dissolved 0.007 Sb. Water draining waste rock characterised by neutral pH, mine’s former processing site, oxidation sulphide concentrates has produced acidic conditions, both (pH 3.8) mining residues (paste pH 2–4). Dissolved metalloid being effectively attenuated on site formation secondary phases residues, including scorodite, iron sulphoarsenate, amorphous arsenate. Attenuation is also occurring co-precipitation adsorption onto oxides or hydroxides, clay mineral surfaces. These processes complemented dilution Sb River. Therefore, despite extremely high mobilisation limited, resulting relatively low leaving site.