The red mud involved in the accident is a waste product of the bayer process, which refines bauxite into a form of aluminium oxide called alumina. As the temperature and pressure increases, the solubility of red mud decreases with sodium hydroxide nie et al. Clarification, red mud washing, and liquor filtration. Red mud, a solid waste in the production of alumina by alkaline processes, is mainly composed of alumina, silica, calcium oxide, iron oxide, titania and trace components of gallium and scandium, and it generally exists as a highly alkaline slurry ph 1012. It is present in the form of slurry having 1030% solid materials milacic et al. The following is the composition of the dry red mud of malcomadras aluminium company limited table 3. Utilization of red mud residues from alumina production.
Modeling the hardness and density of recycled polymer red. Its composition depends upon its parent material from which it is produced liu and wu, 2012. Red mud tanrai alumina processing plant contains a big content of oxides, such as. Alumina extraction from red mud by magnetic separation. The samples studied were made from a mixture selected. Review the composition, recycling and utilisation of bayer red mud. Pdf red mud or bauxite residue is a solid waste generated from the. Red mud minimisation and management for the alumina. Red mud contains high quantities of alkaligenerating minerals and metal ions, which can cause significant environmental damage. Many valuable components such as rareearth elements, al, and fe, in rm are difficult to. The major chemical composition of ironrich red mud generated in alumina plants in.
Red mud or bauxite residue is a highly alkaline waste generated from alumina refinery with a ph of 10. Red mud is the solid waste material which is produced during the production of alumina al 2 o 3 in the bauxite industry. The refinery adopted an innovative and investmentfree mud preparation technology, where the material undergoes unaided separation and. Making the most of red mud february 24, 2014 issue vol.
Eventually the reservoir becomes full and the land must be restored to an acceptable grass field or to agricultural production. Bauxite is a multiphase ore that may contain, according to some referen. Up to now 2006 red mud, is discharged through a pipe line at the sea of antikyra bay. Fe 2 o 3, al 2 o 3, sio 2, tio 2, nao, k 2 o, cao and sometimes. Neutralization or its treatment by sintering in presence of additives is one of the methods for overcoming the caustic problem as it fixes nearly all the leachable free caustic soda present in red mud. This interest stems largely from the environmental impacts associated with red mud and the storage costs involved.
Globally, it is estimated that less than 4 million tonnes of the 150 million tonnes of bauxite residue produced annually is used in a productive way. Still, most of the red mud is disposed of by landfill or pumped into holding ponds liu et al. Researchers from csiros mineral resources flagship have developed a process that lowers the cost of refining bauxite aluminium ore to alumina aluminium oxide by treating the waste product generatedred mudto recover a costly ingredient, caustic soda. Characterization and comprehensive utilization of red mud. Characterization and applications of red mud from bauxite. The initial red mud is filtered and washed with deionized water three. Red mud in an liquid state causes harmful effects to human skin.
Activated red mud, adsorbent, lead removal by adsorption. The mud primarily contains nonaluminium compounds present in the bauxite ore and left as residues after its refining along with sodium hydroxide used to dissolve aluminium oxide. With the rapid development of iron and steel industry and aluminum industry, highquality iron ore and bauxite resources become increasingly tense. The performance of red mud adsorbents in the removal of inorganic anions, heavy metals and organic compounds from wastewaters, and gaseous effluents is also discussed. The title of the patent is treatment and disposal of red mud generated in the bayer process, au701874. Toxic red mud flooded thousands of homes this week near the town of devecser, hungary. The bayer process is the cornerstone of global aluminum production.
Alumina is a bright white solid with a trigonal crystal structure, with oxygen atoms in a hexagonalclosepacked arrangement and the aluminium atoms occupying twothirds of the octahedral holes. Mineral compositionof the red mud depends on the mineral composition of the source material bauxite. However, a lot of ironrich bauxite and bayer red mud resources have not been timely and effectively recycled, resulting in serious problems of environmental pollution and wastage of resources. Disposal of the red mud is a major problem due to the large amounts that are created1in seydisehir, turkey, for example, more than 3 million tons of red mud have accumulated over the past few decades.
Geotechnical characterization of bauxite residue red mud. Red mud is a product of the bayer process during the production of alumina hairi et al. Composition and refractory properties of mixtures of. Furthermore, complete utilization of the raw materials, in this case bauxite, meets an ecological concept while ensuring raw material conservation. Utilization of red mud residues from alumina production unknown. The inventors propose a process that produces a rm cake low in caustic and alumina concentration permitting environmentally friendly disposal. As part of this initiative, the company already sells 200250 ktyr of red mud generated at its nikolayev alumina refinery in ukraine. The performance of red mudadsorbents in the removal of inorganic anions, heavy metals and organic compounds from wastewaters, and gaseous effluents is also discussed. Bayers process revolutionized the extraction of aluminum from the.
Composition and properties of red mud in the world have been presented by many researchers in their publications. Red mud or bauxite residue is a solid waste generated from the bayer process. The acid neutralisation capacity of red mud was measured by both rapid and longterm titration of red mud slurries to ph endpoint of 4. Equilibrium composition of sodium aluminate liquors pages.
Alumina is put through a separate process, electrolysis, to make. From a few alumina plants, red mud is deposited on the sea bed under strictly controlled conditions. It also serves as the raw material for a broad range of advanced ceramic products and as an active agent in chemical. Pdf the composition, recycling and utilisation of bayer red mud. The accumulation of redmud or bauxite residue in the world is 30 billion. The main problem with the mud is its strongly alkaline nature, ranging from ph 10 to, and it was this that did the damage in the hungarian spill. Red mud is produced during the bayer process for alumina production. This involves refining the mineral ore bauxite to generate aluminum oxide alumina, which gives aluminum when smelting 1 the bayer process also creates an insoluble mixture of compounds known as red mud rm, which, at present, is regarded as waste.
Outotec red mud filter press plant mudtreatment technologies our mudtreatment technologies use acid, carbon dioxide, or seawater to neutralize the caustic liquor contained in mud, helping you minimize the environmental impact of your mud disposal area. In other words, for each ton of alumina or half ton of aluminum, approximately one ton of red mud based on dry weight is produced. As a waste product of the bayer process the mud is highly basic with a ph ranging from 10 to. According to the grade of raw material bauxite and the production process of alumina, red mud can be divided into bayer red mud and sintering red mud 1,2. The authors present aspects related to red mud composition and the types of treatments applied to red mud to enhance its adsorption or catalytic performances.
The refinery adopted an innovative and investmentfree mud preparation technology, where the material undergoes unaided separation and drying at the bauxite residue disposal area. Stepwise extraction of valuable components from red mud. The bayer process produces large quantities of bauxite residue red mud. Alumina extraction from red mud has been investigated by magnetic separation with threestep treatment. The details of preparing activated red m ud with hea t tr eatment method ar e as f ollo ws. The bayer process uses caustic soda, high pressure, and high temperature to leach alumina from ferruginous residue slurry bauxite residue or red mud. But for every ton of alumina extracted, more than a ton of red mud is produced. Acg plant rejects 1 ton of mud per ton of alumina produced and that each ton of mud contains on average 15 kilograms of caustic soda naoh which has not been recovered by washing 11. It is a mixture of compounds originally present in the parent mineral, bauxite, and of compounds formed or introduced during the bayer cycle. The situation concerning the disposal method is changing. Bauxite residue is the ironoxide rich mine waste from the processing of bauxite ore for the extraction of alumina through the bayer process.
Red mud is a toxic byproduct of the industrial process that refines bauxite, raw aluminum ore, into aluminum oxide, or alumina. Alumina is put through a separate process, electrolysis, to make aluminum metal. There is growing interest in processing and utilizing the red mud byproduct of the bayer process for alumina extraction from bauxite. Fe 2 o 3, al 2 o 3, sio 2, tio 2, nao, k 2 o, cao and. Red mud is the major waste material produced during alumina production. With either 8 to ph red mud or neutralised red mud. Technological enhancements factors tef were determined for the uranium, thorium, actinium series, their progenies, and the nonseries potassium40 using gamma spectrometry. Survey of bauxite resources, alumina industry and the. The overall refining of bauxite to alumina through the bayer process implies the production of a large quantity of a solid waste called red mud the production of 1 t of alumina generally results in the creation of 11.
Physical and chemical properties of sintering red mud and. Adsorptive removal of phosphate from aqueous solutions. Extraction of alumina and sodium oxide from red mud by a. R recovered from waste of silica alumina refractory bricks. The amount of red mud generated in the bayer process varies significantly, in the range of. Composition of red mud componenets weight % al 2 o 3. Essential readings in light metals wiley online books. Alumina, synthetically produced aluminum oxide, al2o3, a white or nearly colourless crystalline substance that is used as a starting material for the smelting of aluminum metal. Recovering metals from red mud generated during alumina. Red mud is the industrial waste generated during the production of alumina. Bauxite processors recycle the caustic soda and pump the residual red sludge into huge settling ponds. We are now in a position to offer our services in the recycling of red mud. Pdf red mud is a solid waste residue of the digestion of bauxite ores with. According to a search result from the web of science based on the term red mud, from 2001 to 2018 the total number of publications and sum of citations were 997 and 14,699, respectively, as shown in fig.
The disposal of red mud leads to a serious environmental threat because of its tiny particle size and high alkaline value. More than 4 million tons of red mud is generated annually in india. This study investigates the level of technological enhancement of normally occurring radioactive materials tenorm in the red mud waste due to the production of alumina in jamaica. This residue is normally discharged into a clay and polymeric membranelined reservoir. Residues from different bauxite have a wide range of composition. Our core products are made in the majority with cement or on occasions with alkali activated material or geopolymer. It is reported that, there are up to 3 million tons of red mud. Dealing with red mud by product of the bayer process. It is the insoluble product after bauxite digestion with sodium hydroxide at elevated temperature and pressure.
Dicalcium silicate in red mud is also one of the main phases in cement clinker, and red mud can play the role of crystallization in the production of cement clinker. A new project, involving high pressure filtering and dry disposal and reuse of red mud, is under implementation. As red mud consists of metal oxides of iron, titanium, silicon, aluminium, it is felt that red mud can be spray coated. Many valuable components such as rareearth elements, al, and fe, in rm are difficult to be utilized owing to their particle size and alkalinity. Adsorption characteristics of activated red mud for lead. Parekh and goldberger 1976 5red mud is a residual waste generated during the extraction of alumina from bauxite by buyers process.
Red mud rm is a solid waste residue derived from the caustic digestion of bauxite ores during the production of alumina. Red mud ph 14 was obtained from the red mud lake and flocculation tanks at the kirkvine alumina company in mandeville, and the nominal asreceived composition is shown in table 1. Two step stir casting process is used to fabricate the composites by varying volume fractions of red mud 5%, 10% and 15% volume fractions. Chemical composition of red mud generated in alumina plants in various countries adapted from. However, a lot of ironrich bauxite and bayer red mud resources have not been. Red mud rm is a byproduct of extracting of alumina from bauxite. Fly ash is mainly composed of sio2 and al2o3, thus can be used to absorb the water contained in the red mud and improve the reactive silica content of. The composition, recycling and utilisation of bayer red mud. The technological enhancement of normally occurring.
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