Residue

Through research spanning over 20 years, Alcoa’s global Technology Delivery Group (TDG), based at Kwinana in Western Australia, has identified a number of possible sustainable uses for bauxite residue. 

TDG’s research was initially driven by our desire to reduce the size of our residue drying areas (a goal shared by our local communities) and extend the life of our refineries.  However, during the 20 years of research, several exciting opportunities have been identified that may benefit surrounding communities.

Alcoa of Australia’s residue (what remains after our bauxite processing) is made up of two components of roughly equal quantity – sand and mud. TDG has developed a carbonation and wash system to process the residue sand - this neutralises any caustic and removes most of the remaining carbonate salts, making the end product (Red Sand™) environmentally benign. 

Red Sand is essentially crushed rock that is red in colour.  Testing shows it can be used as a general fill material, as construction backfill or as a material suitable for road base construction.

Sand supplies, particularly in the South-West of Western Australia are in decline, and Australian construction companies are looking for alternatives. Alcoa’s residue could be a possible solution. Use of Red Sand as a substitute for quarry sand has a range of potential environmental benefits including reducing the clearing of natural bushland for sand quarries and reducing Alcoa’s requirement for
residue containment facilities.
 
Red Sand has the potential to be a cost effective alternative to limestone and traditional sand in road construction. It could also be a high quality construction sand thanks to its excellent drainage and strength characteristics. 

Other potential uses for the sand and mud components of our bauxite residue include: as a soil amendment for broad acre farming and horticultural uses; as a sand for use in concrete manufacture; in effluent treatment ponds and septic systems; for trace metal retention from road runoff, rubbish tips and acid mine drainage; and in ceramic or plastics manufacturing.

In 2009, Alcoa established a project team to drive the commercialisation of Red Sand. Extensive market research throughout 2009 identified several potential markets and Alcoa is exploring possibilities to work with a co-developer that specialises in the production and marketing of sand products.

During 2009, we used 5800 tonnes of bauxite residue in Western Australian trials, up by 4776 tonnes compared with 2008.

For more visit: www.alcoa.com.au/residue.




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