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Stabilization of Lead in Acidic Mine Filtercake by Addition of Alkaline Tailings
Author(s) -
Davis Andy,
Link Timothy E.,
Baugh Kim,
Witham Richard
Publication year - 1996
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1996.00472425002500050021x
Subject(s) - tailings , chemistry , solubility , sorption , strontium , environmental chemistry , sulfate , alkalinity , calcite , nuclear chemistry , mineralogy , adsorption , organic chemistry
The potential for disposal of acidic Pb‐bearing process waste in an alkaline tailings pond was assessed to ascertain if Pb would become stabilized as opposed to diluted during mixing. This study demonstrated that codisposal of the filtercake residue, consisting of ferrihydroxide, lead sulfate and lead oxide phases (pH = 6.2, Pb = 43 000 mg/kg), with tailings containing abundant calcium and strontium carbonate (pH = 9.8, Pb = 2400 mg/kg) would result in Pb stabilization. The leachable Pb was greater ( p < 0.05%) for a sand‐filtercake mixture compared with the tailings‐filtercake at analogous ratios, demonstrating reactivity between filter cake and tailings. Stabilization occurs because abundant remnant calcite in the tailings neutralizes the acidic filtercake, facilitating sorption of Pb to ferrihydroxide at the pH of the filtercake/tailings mix and a >98.5% decrease in Pb solubility. Sorption ( Kd Pb = 28 600 at pH 7.7) and possible precipitation of Ce‐Pb and Ln‐Pb oxides limit Pb solubility. These data suggest that disposal of acidic filtercake in an alkaline tailings pond would reduce Pb solubility to levels below relevant environmental standards.