Heavy Metal Emissions through Particulate Matter from Aluminium Electrolysis

Heavy metal emissions from the aluminium industry are mainly carried from the plant through fugitive particulate matter (PM) originating from the aluminium electrolysis pot room. To evaluate the behaviour of metal-carrying PM, both airborne and settled PM from two different primary aluminium smelters have been characterized and analyzed for composition and particle size distribution, with special emphasis on heavy metals and carbon. In addition, optical particle sensors have been placed at different elevations in one of the plants to determine the concentrations of different particle sizes in fugitive PM. Metals such as Fe and Ni were primarily found as particles together with S and P on partly combusted carbon PM. Settled PM from both plants were generally coarser (mean = 32–39 μm) and had a higher Al:Na ratio compared with airborne PM, with a mean PM of 21–22 μm. The optical sensors measured PM100 concentrations at roof level in the plant 5–6 times higher than the PM10 concentration during fuming events such as anode shift operations.