Red mud is composed of minerals such as hematite, gibbsite, calcite, quartz, goethite, diaspore, rutile, kaolinite, etc. Effect of red mud on the corrosion of reinforced concrete. International journal for research in applied science. The primary component of red mud is iron oxide which gives the substance its red color. Approximately, 3540% of the processed bauxite ore goes into the waste as alkaline red mud slurry which consists of 1540% solids, and 1. Red mud is the tailings generated from the production process of aluminum industry and is mainly stacked in openair at present, so how to ensure the stability of red mud stockpile is very important. It is the insoluble product after bauxite digestion with sodium hydroxide at elevated temperature and pressure. What are the aluminum properties that confer it a widespread use. This produces a sodiumaluminium solution from which pure al oh3 s precipitated, later to be calcined to produce oxide, from which the metal is recovered.
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 cement. Stockpiling and comprehensive utilization of red mud. Table i chemical composition of aluminium 7075 alloy red mud is a waste obtained after the removal of aluminium from its ore. Total element composition will be analyzed by xray fluorescence spectroscopy xrf mineral composition will be determined by xray diffraction xrd extraction of ree. The first commercial extraction of alumina al 2 o 3 from bauxite has been attributed to henri sainteclaire deville in about 1854 soon after this, in 1888, karl joseph bayer described what is now known as the bayer process, which led to a dramatic reduction in the cost of aluminum metal.
Two step stir casting process is used to fabricate the composites by varying volume fractions of red mud 5%, 10% and 15% volume fractions. How aluminum is made material, manufacture, making, used. Recovery of al2o3, fe2o3 and tio2 from bauxite processing. The red colour is caused by the oxidized iron present, which can make up to 60% of the mass of the red mud. As a rule of thumb, 4 metric tons of bauxite yields 2 tons each of alumina and red mud, and in turn 1 ton of aluminum metal.
The value in recovering materials from red mud would have a tremendous impact for the aluminum industry and for the economy. Behavior of aluminum, arsenic, and vanadium during the. The final red mud contains a residual level of caustic liquid or alkalinity, with a ph of approximately. The addition of red mud delayed the onset of corrosion and possibly also reduced the corrosion rate. A study on microstructure composition of unsaturated red mud.
Bauxite, reserve, alumina, red mud, residue, product. Most alumina refineries are local is the north of china, where is aried and semiaried climate. Regarding mud stockpile of guizhou aluminum factory as the research object, this paper studies the physical and mechanical properties of bayer red mud from wetting process, bayer red mud. In addition to iron, the other dominant components include silica, unleached residual alumina, titanium oxide, and caustic. In some plants, red muds are further processed to produce aluminum oxides. 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. Bauxite tailings, also known as bauxite residue, red mud, red sludge, or alumina refinery residues arr, is a highly alkaline waste product composed mainly of iron oxide that is generated in the industrial production of alumina aluminium oxide, the principal raw material used in the manufacture of aluminium metal and also widely used in the. Possibilities of exploitation of bauxite residue from alumina. The unique project to produce red mud powder has been commissioned in a fully mechanised and automated plant. The bayer process is the cornerstone of global aluminum production. Mineralogy and chemical composition of sampled red mud optimum condition for ree extraction from red mud compounds those could be removed from hospital waste by red mud references. Corrosion characterization of aluminium 6061 red mud metal. In nature, aluminum is found only in chemical compounds with other elements such as sulphur, silicon, and oxygen.
A study on the characterization of red mud harjeet nath1, abanti sahoo2. Red mud chemical composition is presented, and an analysis of existing ways in which they are utilised is executed. A mineralogical assessment on residues after acidic. The mud primarily contains non aluminium compounds present in the bauxite ore and left as residues after its refining along with sodium hydroxide used to dissolve aluminium oxide. Bauxite tailings, also known as bauxite residue, red mud, red sludge, or alumina refinery residues, is a highly alkaline waste product composed mainly of iron oxide that is generated in the industrial production of alumina. Similarly to the change of chemical and minera logical composition of bauxite in dependence on its deposit, the composition of waste mud changes, too. Minor amounts of as 24% are also removed from solution via surface adsorption of as onto the al oxyhydroxides. Red mud or bauxite residue is a solid waste generated from the bayer process. A typical chemical composition is shown in table 1 and a typical. The team was able to efficiently treat red mud particulates with unneutralized vaaa copolymers, down to a vaaa solid composition of 4. Though clearly innovative, according to mishra a method for extracting salable products from red mud in the next five years is all but inevitable.
With stirring and cooling to 60c, aluminum hydroxide aloh 3 hydrargillite precipitates. As the temperature and pressure increases, the solubility of red mud decreases with sodium hydroxide nie et al. The use of red mud as secondary resource to recovery of valuable metals can be one of the solutions to these problems. Bauxite, the most important ore of aluminium, contains only 3060% aluminium oxide al 2 o 3, the rest being a mixture of silica, various iron oxides, and titanium dioxide. Dealing with red mud by product of the bayer process. In india, major producer vedanta aluminium ltd has commissioned a red mud powder processing unit at its lanjigarh refinery in odisha, probably the first of its kind in the alumina industry addressing major environmental hazards. The definitive overview of the science and metallurgy of aluminum, magnesium, titanium and beryllium alloys, this is the only book available covering the background materials science, properties, manufacturing processes and applications of these key engineering metals in a single accessible volume. The red color is caused by the oxidized iron present which can make up to 60% of the red mud. 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 generated red mud to recover a costly ingredient, caustic soda. Also red mud has been used as building materials 3, catalyst 4, inorganic substrate 5, removal agents 68 and absorbent 911, but all these applications use low amounts of generated red mud. Aluminium plants typically produce red mud, and most of them also generate fly ash. Corrosion characterization of aluminium 6061 red mud. Dealing with red mud by product of the bayer process for.
This involves refining the mineral ore bauxite to generate aluminum oxide alumina, which gives aluminum when smelting 1. Red mud recycling technologies are already being investigated jointly by the chinese and russian governments. Composition and properties of red mud in the world have been presented by many researchers in their publications. The chemical composition of the two kinds of red mud determined by xrf analyzer is given in table 1. M e t a l l u r g i e p r o z e s s t e c h n i k recycling results carbothermic. We cant afford to keep collecting red mud in ponds, he opined. About 120,000,000 t red mud would be discharged globally every year 1. In comp arison with red mud it is more solid, because it contains higher portion of solid co mponent, but it has lower content of fe 2o 3 and na 2o. Rm is mainly made up of oxides of iron, aluminum, silicon and titanium. Carbothermic reduction of red mud in an eaf and subsequent recovery of aluminum from slag by pressure leaching in caustic solution.
Red mud in an liquid state causes harmful effects to human skin. The utilisation and recycling of red mud is currently a crucial issue. Rio tinto is a global leader in aluminium, one of the worlds most widely used metals. It is obtained from hindalco, renikoot district, up. Bauxite industry in guinea and value opportunities of the. It comprises of iron, aluminium, titanium and silica along with some other minor constituents. Reclamation of red mud storage area few of red mud storage area is reclamed in china, that is not friendly to the surrounding.
The composition, recycling and utilisation of bayer red mud. Red mud is industrial waste obtained from bayers process that contains different constituents like al2o3, fe2o3, tio2, and na2o etc. For the comprehensive utilization of waste, the mineral component, chemical composition, grain size and microstructure of alumina red mud from henan branch of china aluminum co. Red mud is produced during the bayer process for alumina production. Expected outcome the following outcomes are expected. The nalco red mud contains a higher amount of iron oxides, whereas the alcoa red mud is rich in sio 2. 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. 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. Active in the sector for more than 110 years, today we operate largescale, highquality bauxite mines and alumina refineries and the worlds most modern and competitive aluminium smelters portfolio.
It can be seen from table 2 that the main composition of the red mud from the sintering process is. Jul 08, 2003 red mud is a byproduct of bauxite processing via the bayer process. It is a mixture of compounds originally present in the parent mineral, bauxite, and of compounds formed or introduced during the bayer cycle. This red mud, or bauxite residue, represents a significant challenge to the industry due to its highly caustic. Analysis on physical and mechanical properties of red mud. Bauxite is composed of aluminum hydroxide minerals, including primarily open access. 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 metallic element aluminum is the third most plentiful element in the earths crust, comprising 8% of the planets soil and rocks oxygen and silicon make up 47% and 28%, respectively. Approximately 3540% of the processed bauxite ore goes into the waste as alkaline red mud slurry which consists of 1540% solids and 0. It is important to differentiate between the alkaline waste generated in the bayer process and the tailings generated during the mining of bauxite. Red mud tanrai alumina processing plant contains a big content of oxides, such as. Information on some aspects of the up to now practised disposal of red mud is available at the works of s.
Development of aluminum composites using red mud as. Red mud is the solid waste residue of the digestion of bauxite ores with caustic soda for alumina al2o3 production. The remaining iron, titanium, sodium, silica and other impurities are all discarded. Red mud leachate ph collected from ajka, hungary is neutralized to 99% al is removed from solution during the formation of an amorphous boehmitelike precipitate and dawsonite. Many have said what about the elevated levels of ph in red mud. Red mud is about one million times more alkaline than a neutral material.
Because of the complex physicochemical properties of red mud it is very challenging task for the designers to find out the economical utilization and safe disposal of red mud. Chemistrywise, silicarich red mud seems more suitable for geopolymerization and the silicatoalumina ratio is 2. Chemical and biological leaching of aluminum from red mud. Main categories of red mud and its environmental impacts. Red mud disasters main threat to crops is not toxic. The bayer process is the principal industrial means of refining bauxite to produce alumina aluminium oxide and was developed by carl josef bayer. A new project, involving high pressure filtering and dry disposal and reuse of red mud, is under implementation. Its eds analysis reveals the presence of oxides of iron, silicon, titanium, zirconium etc. With rapid growth of aluminum output in recent years, the discharge amount of red mud increases accordingly.
Red mud a hazardous industrial solid waste red mud world. Red mud or bauxite residue is a highly alkaline waste generated from alumina refinery with a ph of 10. Toxic red mud flooded thousands of homes this week near the town of devecser, hungary. Red mud is a product of the bayer process during the production of alumina hairi et al. Red mud is a toxic byproduct of the industrial process that refines bauxite, raw aluminum ore, into aluminum oxide, or alumina. Stockpiling and comprehensive utilization of red mud research progress. With little scientific knowledge about red muds effects on plant growth, much of the concern focused on toxic metals. The bayer process also creates an insoluble mixture of compounds known as red mud rm, which, at present, is regarded as waste.
With up to 4 inches of red mud coating farmland, concerns arose about red muds potential impact on the 2011 planting of corn, alfalfa, and other crops. With the rapid development of iron and steel industry and aluminum industry, highquality iron ore and bauxite resources become increasingly tense. Unfortunately, for each ton of aluminum produced, around 12 tons of red mud are also produced, creating a massive amount of industrial waste to manage. Red mud is the solid waste residue generated from the alumina refining of bauxite ore, primarily by the bayer process which utilizes caustic soda to dissolve the aluminum silicate. The red mud used for this study was generated in aluminum of greece boeotia, greece s. The red mud used contained 32 % iron in the form of hematite and goethite, 8 % aluminum as aluminum hydroxides and alumina, 4 % titania, 6 % calcium carbonate and desilication product dsp.
The use of red mud not only increases the compressive and tensile strength of products made by this method, it also serves as a colourant. Making the most of red mud february 24, 2014 issue vol. 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. Wang and liu, 2012 measured by using xray diffractometer. The use of any information contained herein by any member or nonmember of the aluminum association is entirely voluntary. Its composition depends upon its parent material from which it is produced liu and wu, 2012. Vickers micro hardness tests are performed and the hardness values vary from hv145 to hv177 with an increase in reinforcement from 0% to 15% volume fraction. The comprehensive utilisation of red mud utilisation in. Red mud was reduced in a tube furnace in an atmosphere of co, co. Hence, the synergistic use of red mud and fly ash makes the aluminium industry more profitable due to the reduced transportation costs of the waste materials and, ultimately, facilitates these industries with better management plans.
O, cao and sometimes a high concentration of valuable metal elements. In the institute of metallurgy of the ural branch of the russian academy of sciences, red mud is utilised by introducing it into the. Analysis of alumina red mud wet flue gas desulfurization. Red mud emerges as the waste material during the production of alumina from bauxite in bayers process. Experimental investigations on mechanical properties of al. May 12, 2016 the most common among the uses of red mud is using it as a building material. China has a target to recycle 10% of all of its red mud, and chalco has already introduced several solutions to recover iron and rare earth metals from red mud waste, so the residues can be used for steel and concrete production.
Described herein is a process that converts the red mud into mineral products that can be used for commercial applications. The chemical composition of the red mud is listed in table1and shows the major constituents of this material such as iron iiioxide, aluminum oxide, calcium oxide and silicon dioxide analyzed by. These wastes can be a substitute for conventional material, when utilized in a best way. Apart from iron oxide, other primary substances within red mud include titanium oxide, residual aluminum oxides, and silica. Characterization and comprehensive utilization of red mud. Microtest approaches like xrf, xrd and sem and routine soil tests were applied to analyze the chemical composition, mineral composition, microstructure and basic physical property indicators of three kinds of red mud, which were the bayer red mud, sintering red mud as well as the mixed red mud prepared by sintering red mud and the bayer red mud at the mixture ratio of 1. Best practice is not a single onesize fits all prescription to bauxite residue management. Washing of red mud with distilled water by taking different ratios of red mud and water. The red mud waste dries to a very fine, powdery solid and contains significant amounts of iron, aluminum, calcium and sodium. This waste product is known from its oxidised iron content as red mud. Alumina red mud from aluminum industry has not been utilized effectively due to its strong alkaline, and so2 is an industrial pollutant which mainly produced by thermal power plants.
In western countries, about 35 million tons of red mud are produced yearly. A typical chemical composition is shown in table 1 and a typical mineralogical composition is shown in table 2. The types and concentrations of minerals present in the muds depend on the composition of the ore and processing conditions. Bauxite residue management australian aluminium council. Stateoftheart formation of red mud during industrial processing of bauxite in the sverdlovsk region russian federation is presented. The disposal of red mud leads to a serious environmental threat because of its tiny particle size and high alkaline value. By increasing the red mud upto 40% to the soil with 3% lime, the best results were come out at 20% red mud soil mixture. Cn102757060b method for dissolving bayer process red mud. The corrosion of steel bars embedded in concrete containing varying amounts of red mud up to 30% of the total binder was tested by electrochemical impedance spectroscopy eis, under partial immersion in a sodium chloride solution. Table 1 chemical composition range % for bauxite residue for main components. Figure 3 shows that removal efficiencies were increased with increasing phosphate concentration up to 30 mg l1 phosphate then decreased.
Alumina is put through a separate process, electrolysis, to make aluminum metal. Abstract rapid industrialization leads to the maximum discharge of waste products which in turn causes the environmental hazards. Which component of the red mud is the more dangerous. Red mud rm is a solid waste product obtained from aluminum industries which is reddish brown in color. In the method disclosed by the invention, the structure and composition of red mud are changed by adopting calcification transformation and pressurizing calcification transformation methods, so that dealkalization and extraction of aluminum can be realized. The aluminum association has used its best efforts in compiling the information contained in this book. Red mud is the tailings generated from the production process of alumina in aluminum industry. There are different aluminum production processes to different bauxites. The key point is to find or to acclimatize plants which are salttolerant and alkalitolerant, but not alien species.
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