Trace element uptake in fresh and aged aluminium oxyhydroxysulfates and hydroxides: Implications for mine drainage-affected environments

Aluminium oxyhydroxysulfates and hydroxides are known to precipitate from mining-generated acidic, neutral basic pH drainage waters that enriched in potentially toxic metal(loid)s. Their role as medium-term (1 year) sinks of Al, As, Cu Ni at values 4, 7 10 was assessed using batch experiments. X-ray diffraction analysis showed basaluminite initially formed 4 7, whereas 10, bayerite or nordstrandite (both Al(OH)3) formed. After 12 months ageing 20 °C, some the recrystallised form alunite, gibbsite, bayerite/nordstrandite unchanged. At took up As but did not take Cu. By end months, released taken by these phases. beginning experiments, were basaluminite, retained gibbsite replaced after months. In only expelled The differences uptake attributed their aqueous speciation relative net surface charge Al oxyhydroxsulfates hydroxides. Release phases likely due incorporation within poorly crystalline original phases, followed progressive release transformed more minerals (at 4) become 10) with ageing. results have significant implications for mineralogy hydroxides, cycling Ni, mine systems.