The disposal of RM remains a major problem. Reports on this issue in the open literature seem scarce. Below you can find some general information about the disposal of Red Mud as well as the common practice in the USA, India, China, Japan, Spain, France and Greece.
In a research by Hind et al. in 1999, it is reported that conventional disposal methods have revolved around the construction of clay-lined dams or dykes, into which the RM slurry is simply pumped and allowed to dry naturally. The design and construction of such residue impoundments has varied considerably over the years [B. Salopek, J. Strazisar, 1993], with disposal practices generally dependent upon the nature of the immediate environment. The authors, note that the operation of these conventional disposal areas was simple and inexpensive, however the potential impact on the surrounding groundwater and environment, and difficulties associated with surface rehabilitation, forced significant changes in disposal practices [D.J. Cooling, D.J. Glenister, 1992]. This led to the construction of doubly sealed impoundments, incorporating a polymeric membrane as well as clay lining, and drained lakes, having a drainage network incorporated in the lining material, have subsequently seen widespread use. Drained disposal systems have been found to reduce the threat of the residue to the environment, while also increasing storage capacity as a result of better residue consolidation [L.K. Hudson, 1982]. As an alternative, dry disposal of bauxite residue, involving enhanced dewatering and evaporative drying, has also been found to further decrease environmental risks and lower overall disposal costs [D.J. Cooling, D.J. Glenister, 1992].
In another report by Agrawal et al., it is reported that out of 84 alumina plants all over the world, only seven are still practising the sea disposal in a planned manner because of scarcity of land.
One patent on the disposal of RM has been also granted to W. M. Gerald. The title of the patent is “Treatment and disposal of red mud generated in the Bayer Process”, AU701874. The inventors propose a process that produces a RM cake low in caustic and alumina concentration permitting environmentally friendly disposal.
Quite recently, the Virotec International Ltd. (Australia), announcened a treatment process for RM that renders the material safe for a variety of applications. The method is based on the use of seawater, which allows the conversion of “soluble alkalinity” (above all from sodium hydroxide) into low soluble minerals (essentially Ca and Mg hydroxides, carbonates and hydrocarbonates). The pH of RM is also reduced and can be decreased down to pH < 9. This technology is patented and several products with the name Bauxsol™ are available. A study on the environmental behaviour of RM processed with the above technology is also available [C. Brunori et al., 2004]. More information on the patented treatment, can be found elsewhere [H. Genc¸-Fuhrman et al, 2003, H. Genc¸-Fuhrman et al, 2004, H. Genc¸-Fuhrman et al, 2004] and the web site of Virotec.
United States of America
The following text is part of a report issued by the EPA in 1990, under the title: “Report to Congress on Special Wastes From Mineral Processing”. For more information and the original full text, please follow the link.
“Red and brown muds are precipitated from a caustic suspension of sodium aluminate in a slurry and routed to large on-site surface impoundments known as red and brown mud lakes. In these lakes, the red and brown muds settle to the bottom and the water is removed, treated, and either discharged or reused. The muds are not removed, but are accumulated and disposed in place. The muds dry to a solid with a very fine particle size (sometimes less than 1μm). Red muds from bauxite refining are generated at four facilities. The fifth facility, Alcoa in Bauxite, Arkansas, generates a residual that is different in color and is commonly called brown mud. The only difference in the operations generating the two varieties of mud is that red muds at Alcoa/Bauxite are sintered and leached to recover additional sodium aluminate, which changes the color of the material but does not substantially change the chemical characteristics of the waste. Therefore, for purposes of this report, the waste generated at all five facilities, including the brown muds, will be referred to as red muds. Red muds contain significant amounts of iron (20 to 50 percent), aluminum (20 to 30 percent), silicon (10 to 20 percent), calcium (10 to 30 percent), and sodium (10 to 20 percent). Red muds may also contain trace amounts of elements such as barium, boron, cadmium, chromium, cobalt, gallium, vanadium, scandium, and lead, as well as radionuclides…”
“…Non-confidential waste generation rate data were reported for red muds by all five bauxite refining facilities. The aggregate industry-wide generation of red mud wastes by the five facilities was approximately 2.8 million metric tons in 1988, yielding a facility average of nearly 564,000 metric tons per year. Reported annual generation rates ranged from 26,000 to 1.2 million metric tons per facility, though the facility generating the least waste, Ormet/Burnside, produced very little alumina, accounting for only about 1 percent of domestic production. The next lowest reported annual generation rate was 190,000 metric tons. The sector-wide waste-to-product ratio was 0.69 in 1988; waste-to-product ratios for individual facilities ranged from 0.40 to 1.05. The impoundments that receive the muds typically have a surface area of between 44.6 and 105.3 hectares (110 and 260 acres), although one impoundment is 10.1 hectares and another is almost 1,300 hectares. The depth of the impoundments range from 1 to 16 meters (3 to 52 feet), with an impoundment average of 7 meters. As of 1988, the quantity of muds accumulated on-site at the 5 facilities ranged from 500,000 to 22 million metric tons per facility, with an average of 9.7 million metric tons per facility.”
Agrawal et al. provide a table, where the details of the RM disposal practices, after Prasad PM et al. at the Indian alumina plants are summarised:
Source: A. Agrawal, K.K. Sahu, B.D. Pandey, Solid waste management in non-ferrous industries in India, Resources, Conservation and Recycling 42 (2004) 99–120). Reprinted with permission from Elsevier.
Below, on the left you can see a picture from a red mud disposal lake in the vicinity of Kashipur region of Orissa, India. Please follow the link and get informed about the people of Kashipur. On the right, you see a landfill where dry disposal has been taking place. The area is regurarly sprayed with water to reduce dust problems.
The following pictures have been in the following web site: http://www.ir.msisa.ru/english/rd/projects/romelt.htm. In left picture, the pond of NALCO factory in Damandjodi (India) is presented. The slurry has a composition of 45% liquid and 55% solids. Output of Red Mud is 200 t/hour (solids). In the right picture, we see an overview of the 212 hectares pond. There is about 20 million tons of waste products accumulated.
In China things appear to be slightly different. In a research by Fei Peng et al., it is reported that most of the RM disposal is in landfill, however there is a precentage close to 10% of RM that is being recycled for further metal extraction or as a raw material for brick probuction. The authors cite a number of works published [H.Z. Xu, Gold 17 (1996), pp. 17–21 (in Chinese), S.W. Yang, Y.H. Cao and Q. Li, Conservation and Utilization of Mineral Resources 6 (1999), pp. 46–49 (in Chinese), D. Luo and J. Liu, China Mining 11 (2002), pp. 50–53 (in Chinese)]
In Japan, majority of RM is deposited into the ocean after neutralization [J. Hyuna et al., 2004]. However, J. Hyuna et al also reports that aluminum manufacturing companies in Japan have developed pretreatment techniques for bauxite before the Bayer process to reduce the amount of RM discharged (Japan Patent No. Heisei 6-340934, 1994 and Japan Patent No. Heisei 7-47301, 1995).
To be written soon
We have limited information. The practise used to be sea disposal, at least in some cases, but we speculate that this has changed in view of the new European legislation.
The following two pictures present disposal ponds. The pictures have been found in the pdf file “La Bauxaline”, issued by (former) Pechiney for the plant in Gardanne. This disposal method is referred as “lagooning” in the text.
There is only one alumina industry in Greece. The situation concerning the disposal method is changing. Up to now (2006) Red Mud, is discharged through a pipe line at the sea of Antikyra Bay. A new project, involving high pressure filtering and dry disposal and reuse of Red Mud, is under implementation. Information on some aspects of the up to now practised disposal of Red Mud is available at the works of S.P. Varnavas, P.P. Achilleopoulos, 1995 and S.E. Poulos et al., 1996. For information on the new adopted solution, please go to News (date 25/04/2006).
Source: S.E. Poulos, M.B. Collins, C. Pattiaratchi, A. Cramp, W. Gull, M. Tsimplis, G. Papatheodorou, Oceanography and sedimentation in the semi-enclosed, deep-water Gulf of Corinth (Greece), Marine Geology, 134, (1996), 213-235. Reprinted with permission from Elsevier.
Below, you can see (left) the High Pressure Filter Press installation and (right) the dry Red Mud, now called “Ferroalumina”.
A. R. Hind, 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.
B. Salopek, J. Strazisar. The influence of red mud impoundments on the environment. Light Metals (Warrendale, PA, United States) (1993), 41-4.
D.J., Cooling, D.J. Glenister, Practical aspects of dry residue disposal Light Metals 1992, 25-31, Proceedings of the 121st TMS Annual Meeting, Mar 1-5 1992, San Diego, CA, USA, Published by Minerals, Metals & Materials Soc (TMS).
L.K. Hudson, Alumina Production, The Aluminium Company of America, Pennsylvania, 1982.
A. Agrawal, K.K. Sahu, B.D. Pandey, Solid waste management in non-ferrous industries in India, Resources, Conservation and Recycling 42 (2004) 99–120.
W. M. Gerald, Treatment and disposal of red mud generated in the Bayer Process, AU701874.
C. Brunori, C. Cremisini, P. Massanisso, V. Pinto, L. Torricelli, Reuse of a treated red mud bauxite waste: studies on environmental compatibility, Journal of Hazardous Materials, 117(1), (2005), 55-63
H. Genc¸-Fuhrman, J.C. Tjell, D. McConchie, O. Schuiling, Adsorption of arsenate from water using neutralized red mud, J. Colloid Interface Sci. 264 (2003) 327–334
H. Genc¸-Fuhrman, J.C. Tjell, D. McConchie, Increasing the arsenate adsorption capacity of neutralized red mud (Bauxsol™), J. Colloid Interface Sci. 271 (2004) 313–320
H. Genc¸-Fuhrman, J.C. Tjell, D. McConchie, Adsorption of arsenic from water using activated neutralized red mud, Environ. Sci. Technol. 38 (2004) 2428–2434
P. M. Prasad, H. K. Chandwani, H. Mahadevan. Disposal practices for bauxite tailings at the alumina refineries. Transactions of the Indian Institute of Metals (1996), 49(6), 817-839.
F. Peng, K. Liang, H. Shao, A. Hu, Nano-crystal glass-ceramics obtained by crystallization of vitrified red mud, Chemosphere 2004 (expected)
H.Z. Xu, “Technological and economic feasibility study on producing building materials with red mud”, Gold 17 (1996), pp. 17–21 (in Chinese)
S.W. Yang, Y.H. Cao and Q. Li, The status and development of comprehensive utilization of red mud in the aluminum industry, Conservation and Utilization of Mineral Resources 6 (1999), pp. 46–49 (in Chinese)
D. Luo and J. Liu, “New process of utilizing red mud from aluminum treating plant to produce high quality direct-reduction iron”, China Mining 11 (2002), pp. 50–53 (in Chinese)
J. Hyuna, S. Endoha, K. Masudaa, H. Shinb, H. Ohyaa, “Reduction of chlorine in bauxite residue by fine particle separation”, Int. J. Miner. Process., (2004) expected
Japan Patent No. Heisei 6-340934, 1994
Japan Patent No. Heisei 7-47301, 1995
S.P. Varnavas, P.P. Achilleopoulos, Factors controlling the vertical and spatial transport of metal-rich particulate matter in seawater at the outfall of bauxitic red mud toxic waste, The Science of the Total Environment, 175 (1995), 199-205
S.E. Poulos, M.B. Collins, C. Pattiaratchi, A. Cramp, W. Gull, M. Tsimplis, G. Papatheodorou, Oceanography and sedimentation in the semi-enclosed, deep-water Gulf of Corinth (Greece), Marine Geology, 134, (1996), 213-235
For a more extended bibliography on the disposal of Red Mud please refer to Bibliography.
Text written by Y. Pontikes. Reflects only personal opinions. Last updated April 22, 2006.