Code No:TMS159Price:Rs1400/-Category:Materials & Chemicals: Metals


Summary  : The report gives uses, brief description of the occurance & distribution of different types of bauxites and their structue, its production figures bringing out the export market for this bauxite and necessitates transportation of Eastern Bauxite to considerable distances. Discusses available technologies (their sources & status) being used for removal of iron oxide. The report, also, identifies the areas where the technology needs further development,  the cost of upgradation and the centres where such developmental work can be taken up

Year of Publication : 2001

Table Of Contents : Executive Summary: Scope and Objective of the Study, Introduction : Importance of Bauxite in Everyday\'s life , Relationship and Importance to Industry : Bauxite Consumption in India, Bauxite Beneficiation Technology : International Practices , Assessment of Technology option :Indigenously available technologies, Economic aspects of preferred technology option : Advantages from adopting preferred technology option , Impact of preferred technology option: Spin off from preferred technology option , Glossary, Keywords,   Annexures , Bibliography,  References .

  • Scope and Objectives of the study
  • Importance of the Topic
  • Methodology
  • Limitations
  • Major Observation
  • Recommendations
  • Action Plan

The mineral, Bauxite, is a rich source of alumina for making aluminum. The metal and its alloys have become an integral part of modern, everyday life. Bauxite (and alumina) is also used in refractories, cement, absorbents, steel, abrasives, rubber, plastic, cosmetics, paints, paper, polishes, glass, enamel and ceramics.

Bauxites are essentially aluminum hydroxides and are formed by the decomposition and hydrolysis of aluminum-bearing silicates. World bauxite resources are estimated to be 55 to 75 billion tonnes. Of this, recoverable reserves are estimated to be around 25 billion metric tonnes. The largest recoverable reserves are in Australia followed by Guinea, Brazil, Jamaica, and India. In 1997, mine production was reported in 24 countries, and total world production amounted to about 123 million tonnes.

India is fortunate to have abundant reserves of bauxite – about 2.3 billion tonnes, which are the fifth highest bauxite reserves in the world. Although India is richly endowed in metallurgical grade bauxites, only 1% of the total recoverable reserves is of refractory grade and 0.44% of chemical grade. India produced about 6.5 million tonnes of bauxite during 1998-99. Its internal consumption in the same period was estimated to be nearly 6.4 million tonnes. The balance was exported. In the same period, however, the country is also reported to have imported nearly 27,200 tonnes of calcined bauxite (value Rs. 14 crore app.) and almost 10,000 tonnes of alumina (value app. Rs. 26.5 crore). About 85% of bauxite mined in India are utilized for making alumina (used for manufacturing aluminum metal).


Since bauxite is a naturally occurring mineral, it has a number of impurities, like iron, silica, Titania, calcium, and small quantities of phosphorous, sulfur, zinc, magnesium and various carbonate and silicate minerals. These impurities not only create quality problems, but also increase production costs, besides causing environmental pollution. Therefore, they have to be removed. There are two problems that make purification of bauxite difficult. Both are closely related to one another, i.e., the wide and easy availability, and low price, of high and medium grade bauxites, and the fine dispersion of iron oxides, kaolinitic clays, calcium, and titanium minerals in the crystalline aggregates of marginal or sub marginal bauxite ores.

Most mines abroad subject their run of mine ore (ROM) to the mineral dressing operation most suitable for their material. Crushing the ROM, usually in hammer mills, is an operation practiced worldwide. Depending on the bauxite, and the quality/grade required, the next stages are screening, scrubbing and washing, magnetic separation, and drying and calcining. Magnetic separation to remove iron, however, is normally practiced in a limited way to produce high value, special grade bauxites. At present, the production of bauxite in most operative mines in India is not sufficiently high as to warrant a capital-intensive beneficiation plant, which usually requires a large capacity to be really economical. Hence, ore dressing efforts have been mainly confined to removal of silica by manual and/or mechanized breaking, crushing, manual sorting and dry screening.

Research is being done in most bauxite producing countries to develop cheap and innovative bauxite beneficiation processes. In one Russian process, for example, alumina, ferrosilicon and a cement additive are recovered by the double-phasic reduction electro-smelting of low-grade bauxite ore mixed with lime and a carbon bearing reducing agent. Another process treats high-silica bauxite to recover alumina, synthetic zeolite and rare earth concentrate. Many new methods of magnetic separation are also being tried out. These include rare earth roll separators, super conducting high gradient magnetic separators and open gradient, non-cryogenic high gradient magnetic separators. Other methods being researched include fluidized bed acid leaching, hydrogen assisted beneficiation, and bio leaching. However, despite decades of intensive studies, economical bauxite beneficiation technology, that can satisfactorily remove impurities does not exist today. The main reason is the high cost of fine grinding and the low value of the widely available material.


Research in India is along international lines but confined to the laboratory. The Indian Bureau of Mines, Nagpur (or IBM), the Jawaharlal Nehru Research Development and Design Center, Nagpur (or JNARDDC), and the Regional Research Laboratory, Bhubanesvar (or RRL), all claim to have lab-scale processes that are ready to be upscaled to pilot plant levels. The IBM has done numerous beneficiation tests, using different methods, on various bauxites found in India. The RRL claims to have developed a beneficiation process to produce non-metallurgical grade bauxite, whereas the JNARDDC says it has processes for both metallurgical and non-metallurgical grades. Of the three, only JNARDDC is still researching actively on bauxite beneficiation.

On analysis, the savings (on raw ore cost) brought by JNARDDC's process through beneficiating metallurgical grade bauxite appears to be over 17% and that of non-metallurgical grade at least 19%. Bauxite users in India have indicated that they are willing to pay between 10-50% higher for a reduction in impurities by a similar amount. This would make the production and marketing of beneficiated bauxite more profitable.

bull.jpg (5174 bytes)Scope & objective of the study

The main objective of this study is to identify existing and emerging technologies, the areas where they need further development, the industries and institutions which can take up development work, and assess the technology’s techno-economic potential. To do this, the study covers the following:

  • Bauxite reserves and consumption in India in terms of quality, utility and chemical constituents.
  • The major impurities in bauxite ore, their nature, and characteristics and how these effect different end users like the aluminum metal, alumina, abrasives, refractories and chemical industries.
  • Relation and importance of bauxite beneficiation (for removal of iron oxide) to the end users.
  • Available technologies in India – their source and status.
  • Similar technologies available abroad.
  • Assessment of technologies.
  • Identification of areas where the technology needs further development and the cost of upgrading.
  • Assessment of the cost if same quality material is imported against if the same quality product is produced through induction of technologies for bauxite beneficiation.
  • Identification of centers where development works can be taken up.
  • Identification of industries and institutions who can participate in follow-up activities.


 Importance of the topic

Bauxite is used to produce aluminum, refractories, water purification chemicals and a host of other products. It, therefore, affects almost all aspects of modern, everyday life. In India, for example, aluminum is used in, among others, power transmission lines, refractories in the furnaces of steel and cement plants, and alum in the water purification systems of cities and towns. Hence, the quality and cost of bauxite affect these industries and, in turn, the common man.

Bauxite is basically a rock comprising of hydrated aluminum oxides (like gibbsite, boehmite and diaspore) and impurities in the form of silica, clay, silt, titanium minerals (like rutile, ilmenite and titania ferrous magnetite) and iron minerals (e.g. iron hydroxide, iron oxide, and pyrite). These impurities increase the cost of mining (in some cases up to 40% of bauxite is rejected as low/marginal grade), handling and transportation. More importantly, they increase costs of downstream products because of waste handling and disposal. The impurities also reduce the capacity utilization, productivity and efficiency of the plant. The waste, e.g. in the form of ‘Red-Mud’ formed during alumina production, also contributes to environment and ground water pollution. Further, since the impurities are never fully removed during the manufacturing process, they directly affect end uses. For example, the iron oxides in bauxite affect the RUL (or Refractive ness Under Load) and PCE (or Pyrometric Cone Equivalent) in refractory bricks, especially those used in steel making. Iron oxides start to react (with TiO2, etc.) and melt at around 12000C, because of which the bricks   cannot withstand temperatures of over 15000C. This degrades the bricks at higher temperatures and a furnace wall/roof/floor failure takes place, leading to production loss.

Due to the problems such as those enumerated above, it is widely recognized that bauxite ore should be purified (or beneficiated), preferably where it is mined, to remove iron and other impurities. Most mines in India are already following some form of separation, but these are usually very crude, inefficient and wasteful. Separation is mostly done physically by hand (e.g. separation by color of the ore) or by mechanical sieving after crushing the ore (finer particles usually contain a higher percentage of silica and are, hence, discarded). In a bid to improve matters, a lot of research and development activity is being done both in India and abroad. However, a commercially viable process that can satisfactorily remove the impurities has yet to be developed.


Different bauxites have different peculiar characteristics. However, it is important to note here that gibbsite changes to boehmite on heating (196-202oC) and the crystal structure, of both gibbsite and boehmite, are modified to a spinel-type, cubic structure at 950oC. Since non-metallurgical grade bauxite is calcined at 1100-1700oC, non-metallurgical bauxite grade consumers can utilize both gibbsite and/or boehmite, provided the impurities are restricted to their specifications. The metallurgical industry can also use gibbsite and boehmite, although the former is preferred as it is easily digested in caustic soda at low temperatures (around 125oC). Fortunately, all Indian bauxites are either gibbsitic or boehmitic, or a combination of both. Hence, if impurities were controlled through beneficiation, Indian bauxites would be preferred by both the metallurgical and non-metallurgical industries.

The potential market for beneficiation technologies is over 147 million tonnes of bauxite, of which the domestic market is potentially over 14 million tonnes. A number of bauxite producers in India have indicated their desire to set up beneficiating plants in India and bauxite users have indicated their willingness to pay higher prices (up to 50%) for beneficiated ore.



The study was conducted in five distinct stages. These are:

  • Collection of Primary Data: MSIA personnel met with experts from TIFAC, Planning Commission, relevant associations, etc. and also visited libraries, Internet sites, etc., to collect secondary information on bauxite, bauxite beneficiation techniques, user industries, R&D organizations, etc.
  • Detailed Desk Research: After the above, an in-depth research on bauxite, the impact of iron impurities on end products, and on bauxite beneficiation techniques was carried out using secondary information. Research was conducted on the beneficiation practices being employed by industry, current work being done by leading R&D institutions, and the institutions/industries who can take up follow up activities. The results of this stage were analyzed for the advantages emanating out of bauxite purification through the technologies available in India and abroad. Those expected from emerging technologies, if developed further by industry/institutions, were also studied and analyzed.
  • Contact with Institutions: In this stage, formal contact was established with R&D institutions, agencies involved with the implementation/monitoring/issue of guidelines/etc., and user industries. Please see Annexure I for a list of the institutions and agencies contacted. Next, questionnaires were designed and sent to over 70 producers, user industries and R&D organizations (Annexure II & III), in order to ascertain bauxite reserves in India in terms of quality, utility and chemical and mineralogical constituents. First hand information on the experience of R&D institutions, implementing agencies and industry was gathered. These were mainly related to problems associated with iron impurities and bauxite beneficiation. Information on the major impurities in bauxite ore, their nature, and characteristics, which effect different end users, and on the relation and importance of bauxite beneficiation to the end users, the technologies available in India and abroad, and the current status of technology, etc. was also collected.
  • Field interviews: The information gathered in the earlier stages was subjected to analysis. Then, to verify ground realities, field interviews were conducted with R&D institutions, bauxite producers and end users, and agencies involved with the implementation/monitoring/issue of guidelines/etc.
  • Report: The information thus gathered was re-examined in terms of the criteria arrived at by MSIA and TIFAC experts (see Annexure IV). Then, another meeting was arranged with TIFAC to review the information collected. Here, the institutions that can be involved with follow-up actions were identified. Subsequently, the findings were formatted in the form of a draft report, which basically confirmed to TIFAC specifications. Feedback, if any, will be incorporated into the final report.



Despite all efforts, the study was constrained by the following limitations:

  • Time constraints: Although some R&D organizations and user industries responded promptly, despite reminders most organizations were very tardy with their response. Quite a few simply ignored requests for information on the subject. These led to delays in completing the report.
  • Reluctance and/or refusal to part with information: Most users, producers and R&D organizations, not only in India but also abroad, were reluctant to part with first hand information. Some ignored requests altogether. The study, therefore, had to depend quite often on published information.
  • Inability to extensively cover beneficiation plants abroad: Bauxite beneficiation for the removal of iron is hardly carried out in India and only in some cases abroad. The study was not envisaged to cover field interviews abroad. Hence, it has had to rely only on scarce secondary information available.
  • Laboratory scale processes: Most processes have not been upscaled from laboratory scale. In India, for example, only one process (to remove silica) has been upscaled to a pilot plant level. Therefore, the inability to assess either a commercial beneficiation plant or one in the pilot plant scale has been a major constraint in assessing technology.


 Major observations

During the course of the study some interesting facts came to light. Some of the main ones are as follows:

  • Reckless handling and mining of bauxite, without attempts to upgrade and utilize marginal grades, have led to a depletion of high-quality refractory grade ore. The limitations in quality and availability of this grade have resulted in the DGTD Panel drawing up different specifications to cover regional variations. Since Indian industry is not getting a satisfactory product, the country is increasingly resorting to import of this grade from China and other countries.
  • Almost all producers resort to mineral, color-based, manual sorting to remove comparatively higher iron bearing bauxite ore. This not only increases inefficiency but also causes waste (up to 40% of the ore is rejected) - thus compounding the inefficiency.
  • Most mining operations are done manually or semi-mechanically since the majority of the mines are in the small scale. Due to this, beneficiation technologies to remove iron impurities, which can be expensive, are not being used in the country.
  • Indian ores, e.g. East Coast bauxite, can contain up to 30% of iron oxides, titanium and other impurities. Since they are not removed, they add to transportation costs, lead to lower capacity utilization in downstream plants, increase waste and waste handling costs, and affect the quality of final product. Indian alumina refineries generate almost a million tonnes of waste ("Red Mud"), each year. This is likely to increase to over 6 million tonnes per annum when the new expansions in alumina production come on line in the early 2000s.
  • Although big units like NALCO, HINDALCO, etc. are utilizing state of the art mining techniques, which makes mining more efficient and cheap, even they are not beneficiating their ore. One of the main reasons for this is the lack of a commercially proven beneficiation technology. All iron removal processes under development in India are laboratory scale, and have not been upscaled even to a pilot plant level.



The immediate impact of commercial beneficiation plants based on indigenous technology will be on the mining industry, the Indian bauxite user industry and the country's overall economy. Downstream plant capacities and efficiencies will improve dramatically leading to lower production costs, higher profits and more sales. Imports of bauxite and bauxite-based products will diminish and exports of bauxite-based products will increase. Export of the technology will bring in additional foreign exchange leading to a better balance of payment position for the country. Cheaper downstream products like aluminum will translate into more rural electrification at the same cost. Cheaper and better bauxite based refractories will mean cheaper and better steel and other such products. This will, in turn, lower costs and make products more affordable. In addition, adoption and export of the technology will be a major boost to the Indian R&D effort.

RRL, Bhubanesvar, has discontinued R&D on bauxite beneficiation. JNARDDC, and IBM, Nagpur are controlled by the Government of India's Ministry of Mines. After JNARDDC was formed (in 1989), the ministry ordained that all aluminum research, including those on alumina and bauxite, would be the sole preserve of JNARDDC. The latter has developed laboratory-scale technology for both metallurgical and non-metallurgical grade bauxites (e.g. refractory grade). The details provided by them indicate that there may be between 17-20% cost benefit by beneficiating bauxite ore using their technology. Almost all the bauxite users that have responded have indicated their willingness to pay between 10-50% higher price if the impurities in bauxite ore can be reduced by a similar amount. This means that the total cost benefit may be substantially higher. The Indian bauxite industry is on the look out for a commercially viable technology for bauxite beneficiation and is willing to cooperate in the R&D effort. Towards this end, M/s Orient Abrasives Ltd., a leading supplier, and user, of bauxite ore has extended their support and full cooperation, including use of their existing bauxite crushing and other facilities to the bauxite beneficiation effort.


In light of the above, the following steps are recommended:

  • For further research and technology demonstration: Both metallurgical grade and non-metallurgical grade bauxites are important raw materials for Indian industry. The fast depleting Indian resources of non-metallurgical grade bauxites, especially refractory grade, has forced the country to increasingly resort to import of these grades from abroad. It is, therefore recommended that a pilot plant for beneficiating 100kg/hr of metal grade bauxite, and 10 kg/hr of refractory/special grade bauxite, be set up based on JNARDDC's process.
  • To lower initial investment and running costs: The involvement of M/s Orient Abrasives Ltd. in the R&D effort can reduce operating costs of the pilot plant. The company has indicated its willingness to grind bauxite to specification (which is an expensive process) and allow use of its magnetic separators, etc. BHEL and BARC have also indicated their willingness to be involved in the R&D effort. They have developed state of the art super conducting high gradient magnetic separator systems. These are expected to be very efficient in separating iron impurities from bauxite. Note: Although both BHEL and BARC have indicated their willingness to associate with the project, no firm commitment has yet been made by them for providing the equipment.
  • To make the process more economical: JNARDDC should make suitable modifications in their process to recover titanium dioxide and other valuable constituents present as impurities in bauxite ore. These high value products will make the process more profitable.
  • For successful marketing of the process: Involvement of Indian industrial units, like M/s Orient Abrasives Ltd., that have shown interest in setting up bauxite beneficiation plants and associations like the Federation of Indian Mineral Industries and India Refractory Manufacturers' Association. Note: M/s HINDALCO Industries Ltd., Renukoot, M/s Indian Aluminum Co. Ltd., Radhanagari, and M/s Orissa Industries Ltd., Rourkela, have also indicated their interest in setting up bauxite beneficiation plants.


Action plan

It is suggested that TIFAC monitor the project and supervise the marketing of the technology. The plan for implementing the project is envisaged as follows:

  • Step-I: Project funding - As things stand, JNARDDC has indicated a project cost of Rs. 2.14 crores, for a pilot plant capable of processing 100-kg/hr of metallurgical grade and 10-kg/hr of non-metallurgical grade bauxite. The estimate includes cost of raw material, utilities, manpower, etc. It is suggested that the project be funded by TIFAC under its Home Grown Technology Programme. The time taken to arrange the funding is estimated to be 2 months.
  • Step-II: Location of the pilot plant - The JNARDDC has over a hundred acres in Nagpur on which the pilot plant can easily be located. However, in order to simulate actual commercial plant conditions it may be a good idea to locate the pilot plant at the mine site of M/s Orient Abrasives Ltd., or one of the other companies that have shown interest in setting up beneficiation plants (e.g. HINDALCO). Note: As yet, none of the companies have been approached for setting up the pilot plant at their site.
  • Step III: Installation of pilot plant - It is envisaged that the plant will be set up under the supervision of JNARDDC and MSIA. Civil construction, equipment manufacture, installation of plant and machinery, etc., will be sub-contracted to experienced, technically qualified and reputed parties. The entire procedure, including construction, equipment procurement and installation, and procurement of raw material, is expected to be completed in about 24 months.
  • Step IV: Running, testing, optimization and demonstration - JNARDDC's scientists and technicians will supervise the trial runs and testing in the pilot plant. Other plant personnel are to be hired locally. It is envisaged that the series of beneficiation runs and optimization of the process will involve 12 months. JNARDDC's personnel are also expected to demonstrate the process to potential customers of the technology.
  • Step V: Marketing of technology - The actual marketing will be done by JNARDDC and, if desired, MSIA personnel.