Siltbuster and SCS develop process to extract alumina from wastewater
Siltbuster Process Solutions (SPS) has partnered with centrifuge supplier Solids Control Services (SCS) to develop a new process enabling alumina to be recovered from wastewater.
The technology has been piloted at an aluminium casting plant in Norway, and the two companies have worked together to identify the simplest and most practical solution for the extraction of alumina from waste sludge produced by the casting process.
Using Siltbuster’s HB40R Settlement Unit and CM400 Oil Water Separator, the initial trial treated 48m3 of waste sludge by first homogenising it and removing any particles larger than 5mm. Hydro cyclones then classified and purified the alumina into a dewatering bag. This was followed by the use of an inclined plate separator and coalesce media separator to remove any oil from the remaining sludge.
Having separated out the alumina, the final step in the process was to treat the remaining water with Siltbuster’s DAF D10 unit, cleaning it to a high level of purity.
By treating the sludge 1m3 at a time, the trial team could modify the process as the pilot progressed, finding the optimum cut-off point for the hydrocylone. It also enabled the team to continually refine the process and reclaim the most concentrated levels of alumina possible. With further research it has been determined that it would be possible to reduce waste by an additional 30%.
Clwyd Jones, of Siltbuster, said: “Alumina is a valuable commodity in its own right and can be used for a number of industrial purposes in addition to the production of aluminium, for example in spark plug insulators and metallic paint or as a fuel component for solid rocket boosters. Successfully recovering alumina from a plant’s waste sludge is an important commercial benefit for manufacturers and demonstrates how industrial waste can be reduced.”
He continued: “The pilot has shown that the process can easily be scaled up to treat 100m3 of waste sludge per hour. We can increase this further by using multiple streams in parallel, meaning this is a real commercial opportunity for aluminium producers.”
Other beneficial results of the pilot included:
- Recovered alumina can be dewatered at high purity to as low as 20% water dryness
- Water can be cleaned to a high level of purity without the need for additional exotic treatments, further reducing wastewater disposal costs.
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