Dr Raj Kurup

Refining bauxite to produce alumina generates sodium oxalate waste (SOW), which can affect product quality and cause challenges for environmental management.

Historically, most of the SOW has been managed by storing it in holding lagoons, with the rest destroyed in an expensive thermal or aerobic treatment process.

To treat this legacy SOW, Dr Raj Kurup led the development of the Smart Priming Oxalate Removal Enabler — SPORE.

The SPORE innovation enables legacy SOW storage lagoons to be converted into anaerobic reactors that produce valuable by-products, including sodium carbonate and methane. The process achieves this without the ongoing addition of pH neutralisation chemicals.

This captures otherwise unrecoverable by-products from the SOW, and allows the remediated lagoon to be used for treatment of fresh SOW from the refinery.

SOW is separated from a refinery’s Bayer process liquor (BPL) via co-precipitation to solids that contain sodium oxalate, aluminium hydrates and entrapped BPL. The sodium hydroxide in the BPL gives the SOW a pH of 13 — making it highly alkaline — with resulting difficulty in treatment.

This pathway has clear benefits over existing aerobic treatment methods, such as surplus energy generation or lower sludge production, and reduces operational issues and costs.

The next phase of the project aims to resolve the fundamental engineering challenges of implementing the technology for legacy SOW treatment.

The technology is expected to generate additional net revenue for a typical refinery of $4 million with a payback of two years. It also provides an economic solution to the SOW environmental legacy and process efficiency.

SPORE has generated interest from operators worldwide.