British Columbia Mine Reclamation Symposium

Toxicity identification evaluation of effluent from a mine Elphick, James R.; Bailey, Howard C.


The toxicity of discharges from mining operations continue to be of concern to the regulatory community and mine operators. Toxicity in discharges may be caused by a variety of factors, including metals, ammonia, pH, process chemicals and total dissolved solids. In this study, a toxicity identification evaluation (TIE) was performed on samples of a discharge from a gold and silver mine which exhibited toxicity in 7-day partial lifecycle tests using the freshwater cladoceran Ceriodaphnia dubia. The results indicated that an organic anion was responsible for toxicity and that phosphorus concentrations in the treatments were correlated with toxicity. Collectively, the data suggested that a phosphine-based collector (Aerophine 34ISA Promoter) used in the metals flotation process was the most likely cause of the observed toxicity. Consequently, the chemical was evaluated for toxicity and its response to the TIE procedures which were effective at reducing toxicity in the discharge sample. These results, and those of a confirmatory spiking study, consistently suggested that Aerophine was the cause toxicity. Efforts at the mine to reduce the residual concentration of this process chemical resulted in reduced toxicity of the discharge.

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