Physical and chemical properties of sintering red mud and. 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. Alumina is put through a separate process, electrolysis, to make aluminum metal. A new project, involving high pressure filtering and dry disposal and reuse of red mud, is under implementation. 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. Technological enhancements factors tef were determined for the uranium, thorium, actinium series, their progenies, and the nonseries potassium40 using gamma spectrometry. Its composition depends upon its parent material from which it is produced liu and wu, 2012. Our core products are made in the majority with cement or on occasions with alkali activated material or geopolymer. Red mud or bauxite residue is a highly alkaline waste generated from alumina refinery with a ph of 10. Pdf the composition, recycling and utilisation of bayer red mud. 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.
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. Making the most of red mud february 24, 2014 issue vol. With the rapid development of iron and steel industry and aluminum industry, highquality iron ore and bauxite resources become increasingly tense. Clarification, red mud washing, and liquor filtration. The major chemical composition of ironrich red mud generated in alumina plants in. Furthermore, complete utilization of the raw materials, in this case bauxite, meets an ecological concept while ensuring raw material conservation. Essential readings in light metals wiley online books. Bauxite is a multiphase ore that may contain, according to some referen. Red mud is the industrial waste generated during the production of alumina. Eventually the reservoir becomes full and the land must be restored to an acceptable grass field or to agricultural production. The performance of red mudadsorbents in the removal of inorganic anions, heavy metals and organic compounds from wastewaters, and gaseous effluents is also discussed.
The accumulation of redmud or bauxite residue in the world is 30 billion. Alumina extraction from red mud by magnetic separation. Red mud contains high quantities of alkaligenerating minerals and metal ions, which can cause significant environmental damage. Red mud tanrai alumina processing plant contains a big content of oxides, such as. There is growing interest in processing and utilizing the red mud byproduct of the bayer process for alumina extraction from bauxite. Equilibrium composition of sodium aluminate liquors pages. As part of this initiative, the company already sells 200250 ktyr of red mud generated at its nikolayev alumina refinery in ukraine. As the temperature and pressure increases, the solubility of red mud decreases with sodium hydroxide nie et al. Composition of red mud componenets weight % al 2 o 3. 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. Alumina extraction from red mud has been investigated by magnetic separation with threestep treatment.
The refinery adopted an innovative and investmentfree mud preparation technology, where the material undergoes unaided separation and drying at the bauxite residue disposal area. Fe 2 o 3, al 2 o 3, sio 2, tio 2, nao, k 2 o, cao and sometimes. 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. Adsorptive removal of phosphate from aqueous solutions. Extraction of alumina and sodium oxide from red mud by a. 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 bayer process is the cornerstone of global aluminum production. Red mud is the solid waste material which is produced during the production of alumina al 2 o 3 in the bauxite industry. Parekh and goldberger 1976 5red mud is a residual waste generated during the extraction of alumina from bauxite by buyers process. 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. Fe 2 o 3, al 2 o 3, sio 2, tio 2, nao, k 2 o, cao and. Red mud is a toxic byproduct of the industrial process that refines bauxite, raw aluminum ore, into aluminum oxide, or alumina. From a few alumina plants, red mud is deposited on the sea bed under strictly controlled conditions.
The details of preparing activated red m ud with hea t tr eatment method ar e as f ollo ws. Characterization and comprehensive utilization of red mud. Composition and refractory properties of mixtures of. 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. It is a mixture of compounds originally present in the parent mineral, bauxite, and of compounds formed or introduced during the bayer cycle. 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. Pdf red mud or bauxite residue is a solid waste generated from the. Red mud is a product of the bayer process during the production of alumina hairi et al. With either 8 to ph red mud or neutralised red mud. It is present in the form of slurry having 1030% solid materials milacic et al. R recovered from waste of silica alumina refractory bricks. Alumina is put through a separate process, electrolysis, to make.
Red mud is the major waste material produced during alumina production. Residues from different bauxite have a wide range of composition. The acid neutralisation capacity of red mud was measured by both rapid and longterm titration of red mud slurries to ph endpoint of 4. 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. 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. 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. Utilization of red mud residues from alumina production. Stepwise extraction of valuable components from red mud. The bayer process uses caustic soda, high pressure, and high temperature to leach alumina from ferruginous residue slurry bauxite residue or red mud. The samples studied were made from a mixture selected. Many valuable components such as rareearth elements, al, and fe, in rm are difficult to be utilized owing to their particle size and alkalinity. Activated red mud, adsorbent, lead removal by adsorption.
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. 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. 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. Red mud or bauxite residue is a solid waste generated from the bayer process. 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. Survey of bauxite resources, alumina industry and the. This interest stems largely from the environmental impacts associated with red mud and the storage costs involved. It is reported that, there are up to 3 million tons of red mud.
Utilization of red mud residues from alumina production unknown. Red mud minimisation and management for the alumina. It also serves as the raw material for a broad range of advanced ceramic products and as an active agent in chemical. Mineral compositionof the red mud depends on the mineral composition of the source material bauxite. 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. 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. The following is the composition of the dry red mud of malcomadras aluminium company limited table 3. 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. Red mud rm is a byproduct of extracting of alumina from bauxite. Geotechnical characterization of bauxite residue red mud. However, a lot of ironrich bauxite and bayer red mud resources have not been. Modeling the hardness and density of recycled polymer red.
The amount of red mud generated in the bayer process varies significantly, in the range of. Red mud rm is a solid waste residue derived from the caustic digestion of bauxite ores during the production of alumina. The bayer process produces large quantities of bauxite residue red mud. The refinery adopted an innovative and investmentfree mud preparation technology, where the material undergoes unaided separation and. Bauxite residue is the ironoxide rich mine waste from the processing of bauxite ore for the extraction of alumina through the bayer process. Chemical composition of red mud generated in alumina plants in various countries adapted from. Many valuable components such as rareearth elements, al, and fe, in rm are difficult to. Red mud in an liquid state causes harmful effects to human skin. The situation concerning the disposal method is changing.
The title of the patent is treatment and disposal of red mud generated in the bayer process, au701874. Adsorption characteristics of activated red mud for lead. As a waste product of the bayer process the mud is highly basic with a ph ranging from 10 to. Up to now 2006 red mud, is discharged through a pipe line at the sea of antikyra bay. As red mud consists of metal oxides of iron, titanium, silicon, aluminium, it is felt that red mud can be spray coated. The composition, recycling and utilisation of bayer red mud. The initial red mud is filtered and washed with deionized water three. Still, most of the red mud is disposed of by landfill or pumped into holding ponds liu et al. 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. 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.
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. This residue is normally discharged into a clay and polymeric membranelined reservoir. Recovering metals from red mud generated during alumina. 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. Bauxite processors recycle the caustic soda and pump the residual red sludge into huge settling ponds. The disposal of red mud can present an environmental problem simply because there is so much of it. Toxic red mud flooded thousands of homes this week near the town of devecser, hungary. Red mud is produced during the bayer process for alumina production. But for every ton of alumina extracted, more than a ton of red mud is produced. 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.
Composition and properties of red mud in the world have been presented by many researchers in their publications. 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. Bayers process revolutionized the extraction of aluminum from the. Pdf red mud is a solid waste residue of the digestion of bauxite ores with. The technological enhancement of normally occurring. The inventors propose a process that produces a rm cake low in caustic and alumina concentration permitting environmentally friendly disposal. Two step stir casting process is used to fabricate the composites by varying volume fractions of red mud 5%, 10% and 15% volume fractions. Review the composition, recycling and utilisation of bayer red mud. Characterization and applications of red mud from bauxite.
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