The increasing concern for the environment is a promising factor for a higher activity in the field and a re-evaluation of the economical aspects.
Hind et al in their work, report a number of industrial attempts. RM has been used a pH modifier in the heap leaching of gold ores [R.E. Browner, 1992], in the removal of sulfur compounds from kerosene oil [A.P. Singh, et al, 1993], in the hydrogenation of anthracene [J.J. Llano et al, 1994, J. Alvarez, et al, 1995], coals and aromatic compounds [A. Eamsiri et al, 1992], and as a pigment in anticorrosive marine paints [T. Skoulikidis et al, 1992,].
In India, it is reported that 2.5 million tonnes were absorbed by the cement industry in 1998-99 (more)
In China, it is reported that 10% approximately of RM produced is recycled for further metal extraction or utilized as a raw material for brick production (Fei Peng et al, Chemosphere, 2004 (expected))
In Australia, bricks made from bauxite residue from Alcoa’s alumina processing plant at Kwinana, Western Australia, have been used to build homes in the South-West of Western Australia, according to a report in The West Australian, 1 February 2002. The use of waste bauxite residue was trialled in a test building in the early 1980s. However, the Health Department rejected the building after tests registered radioactivity readings which bordered on the maximum acceptable radiation exposure levels for 19 hours a day. The residue contained radioactive thorium and uranium. The Health Department’s acting director of environmental health, Brian Devine, said that following the 1983 tests, the department would be concerned if any houses were built with the bricks. The West Australian was advised by sources close to Midland Brick, which produced the red sand bricks, that at least three homes were built using the bricks, most likely at Waroona. The former general manager said the company made a batch of bricks with the red mud from Alcoa. A document obtained by The West Australian shows senior Alcoa employees admitting to a 1998 community meeting that the red mud stockpiles near the Kwinana plant exceeded occupational radioactivity limits. Alcoa environmental manager Graham Slessar said that this was wrong. (Source: Australian Fluoridation News Jan-Feb 2002 Edition, http://www.fluoride.org.uk/ausfnews/copy_list.htm)
In Japan, plant scale tests were initiated in 2003 to confirm the possibility of using Residual Bauxite (i.e. dry “red mud”) in cement production. Residual Bauxite was introduced as a raw material along with other raw materials as lime, clay, silica, iron source etc. The tests confirmed that residue added cement, as well as mortar and concrete made from this cement meet the Japanese Industrial Standards (Japan Aluminum Organisation, 2004)
Other attempts for industrial production are being carried out for cement, bricks and roofing tiles production in Greece. The research is still under implementation however pilot plan experiments have already taken place. The alumina producing industry “Aluminium de Grece” has made an agreement with Lafarge cement company for delivering annually 200.000t of dewatered residual bauxite. (more)
A. R. Hind a, S. K. Bhargava, Stephen C. Grocott, “The surface chemistry of Bayer process solids: a review”, Colloids and Surfaces A : Physicochem. Eng. Aspects, 146 (1999) 359–374) R.E. Browner, Miner. Metall. Processes (February 1992), 48
A.P. Singh, P.C. Singh, V.N. Singh, J. Chem. Technol. Biotechnol. 56 (1993) 167
J.J. Llano, R. Rosal, H. Sastre, F.V. Diez, Fuel 73 (1994)
J. Alvarez, R. Rosal, H. Sastre, F.V. Diez, Appl. Catal. A 128 (1995) 259
A. Eamsiri, W.R. Jackson, K.C. Pratt, V. Christov, M. Marshall, Fuel 71 (1992) 449
T. Skoulikidis, P. Vassiliou, N. Diamantis, in: P.J. Tunturi (Ed.), Proceedings of the 12th Scandinavian Corrosion Conference and Eurocorr ‘92, Corrosion Society of Finland, Finland, 1992, p. 475
Fei Peng, Kai-Ming Liang, Hua Shao, An-Min Hu, Nano-crystal glass-ceramics obtained by crystallization of vitrified red mud”, Chemosphere 2004 (expected)
Japan Aluminum Organisation, “A field survey for the enviromental impact assesment of disposal at sea of bauxite residue”, International Maritime Organisation (IMO), Scientific Group (SG) – 27th Meeting, March 2004
Text written by Y. Pontikes. Reflects only personal opinions. Last updated October 28, 2005