Objective: To reduce odour levels from Oxalate Kiln at Alcoa’s Pinjarra alumina refinery.
Statement of Findings: The raw bauxite feed stock in Western Australia is unique and contains soil based impurities that when processed release some odours from the refinery. This was particularly the case at the discharge of the Oxalate Kiln at Pinjarra refinery. The odours were tested and found to contain compounds that could be oxidised to reduce the odour levels. The technology chosen to reduce odour is a Regenerative Thermal Oxidiser (RTO). An RTO uses patented honeycomb ceramics to achieve the heat regeneration and thus reducing the operating costs dramatically when compared to a standard Thermal Oxidiser. A major challenge in the application was the presence of caustic compounds in the raw gas and the effect of this on the ceramics, which are predominantly manufactured from an Aluminium base.
Key Conclusions: By utilising the best available technology to oxidise these compounds, the odour levels have been reduced by approximately 99%. The life of the ceramics was greatly increased following the development of a caustic resistant ceramic, which utilises more rare minerals to provide the necessary heat exchange. The technology has also been successfully applied to other applications on Alcoa refineries, namely liquor burning kiln emissions and for destruction of digestion odours.