The AquaCritox^® Oxalate is a hydrothermal decomposition process focussed on treating oxalate found in spent Bayer liquor from the production of alumina from Bauxite. The process does not use an oxidant and operates at optimised pressures and temperatures around 95 to 110 bar and 300 to 315°C.

Hydrothermal decomposition converts sodium oxalate to sodium carbonate and carbon monoxide. Following hydrothermal decomposition, the produced carbon monoxide is catalytically converted to CO₂, while the sodium carbonate product is causticized with calcium hydroxide to sodium hydroxide, which is recycled to the Bayer process, and non-hazardous calcium carbonate, which is mixed with the plant’s bauxite residue output.

Tailored solutions can be offered for waste streams with flow rates up to 10 m³/h. The main OPEX consideration for this process is related to the cost of heating, followed by maintenance relating to high pressure rotating equipment.

Industries

Mineral Processing

Case Studies

Sodium oxalate in Ireland