A new method for the characterisation and quantitative speciation of base metal smelter stack particulates

Base metal smelters may be a source of particulates containing metals of environmental concern released to the atmosphere. Knowledge of the quantitative chemical speciation of particulate releases from base metal smelters will be of value in smelter emission fingerprinting, site-specific risk assessments, predictions of the behaviour of smelter stack particulates released to the environment and in resolving liability issues related to current and historic releases. Accordingly, we have developed an innovative approach comprising bulk chemical analysis, a leaching procedure, X-ray diffraction analysis and scanning electron microscopy/electron probe microanalysis characterisation in a step-wise apportioning procedure to derive the quantitative speciation of particulate samples from the stacks of three copper smelters designated as A, B and C. For the A smelter stack particulates, the major calculated percentages were 29 CuSO₄, 20 ZnSO₄.H₂O, 13 (Cu_0.94Zn_0.06)₂(AsO₄)(OH), 11 PbSO₄ and four As₂O₃. For the B smelter stack particulates, the primary calculated percentages were 20 ZnSO₄.H₂O, 20 PbSO₄, 12 CuSO₄ and nine As₂O₃. Finally, we calculated that the C smelter stack particulates mostly comprised 34 ZnSO₄.H₂O, 19 (Cu_0.84Zn_0.16)(AsO₃OH), 11 PbSO₄, 10 As₂O₃ and nine Zn₃(AsO₄)₂. Between 56% and 67% by weight of the smelter stack particulates, including the As, was soluble in water. For these and other operations, the data and approach may be useful in estimating metals partitioning among water, soil and sediment, as well as predictions of the effects of the stack particulates released to the environment.