Bauxite is the most important aluminium ore. It consists largely of the minerals gibbsite Al(OH)3, boehmite γ – AlO(OH), and diaspore α-AlO(OH), together with the iron oxides goethite and hematite, the clay mineral kaolinite and small amounts of anatase TiO2. It was named after the village Les Baux-de-Provence in southern France, where it was first discovered in 1821 by geologist Pierre Berthier.

Lateritic bauxites (silicate bauxites) are distinguished from karst bauxites (carbonate bauxites). The early discovered carbonate bauxites occur predominantly in Europe and Jamaica above carbonate rocks (limestone and dolomite), where they were formed by lateritic weathering and residual accumulation of intercalated clays or of clayey dissolution residues of the limestone.

The lateritic bauxites occur in many countries of the tropical belt. They were formed by lateritization of various silicate rocks such as granite, gneiss, basalt, syenite and shale. Compared with iron-rich laterites, the formation of bauxites demands even more intense weathering conditions with a very good drainage. This enables dissolution of kaolinite and precipitation of gibbsite. Zones with highest aluminium content are frequently located below a ferruginous surface layer. The aluminium hydroxide in the lateritic bauxite deposits is almost exclusively gibbsite. Bauxite is strip mined (surface mining) because it is found at the surface, with little or no overburden.

The overall resource position of bauxite in India is over 3 billion tonnes. India occupies 5th place with a share of 7% of world resources. Out of this 80% of resources are of metallurgical grade. Orissa and Andhra Pradesh account for more than 90% of country’s metallurgical grade resources. The balance is distributed in Jharkhand, Chhattisgarh, Karnataka and Maharashtra. The resources of metallurgical grade bauxite are quite adequate. Out of 1700 million tonnes bauxite available in Eastern Ghat Belt in Orissa and Andhra Pradesh only Panchpatmali deposit in Koraput district in Orissa has been developed into a mine. Many other deposits with good potential are yet to be exploited in Orissa and Andhra Pradesh.

Bauxite resources are dominantly located in the peninsular area. The deposits are associated with both high level and low level laterite. Majority of the Indian deposits are associated with high level laterite occurring in Eastern Ghat, Western Ghat, plateaus in Jharkhand and Madhya Pradesh and among the large areas occupied by ‘low-level’ laterite deposits, bauxite has been recorded in Katni area (Madhya Pradesh); Saurashtra and Kutch (Gujarat); Thane and Kolaba (Maharashtra) and also in parts of Kerala and Tamil Nadu. Vast expanse of laterite profile in central and coastal (both east and west) Peninsular India holds promise for addition to the bauxite resources. With the abundance of resources, Eastern Ghats region of Orissa and Andhra Pradesh would be the area of major bauxite mining activities in future. The large deposits of these areas, with reserves of more than 50 million tones, can be reserved for proposed export oriented alumina plants. Additional bauxite resources are required for the brownfield expansion of the existing alumina producers.

Though there are more than 200 mines operating in the country, most of these are small open cast and manually operated. Industry is dominated by five integrated players which are in the manufacture of alumina/ aluminium, viz. the National Aluminium Company Limited (NALCO), a public sector undertaking, Bharat Aluminium Company Limited (BALCO), Hindustan Aluminium Corporation Limited (HINDALCO), Indian Aluminium Comp-any Limited (INDAL), and Madras Aluminium Company Limited (MALCO), all in the private sector.

15 major deposits account for 75% of the country’s production. These are mostly the captive bauxite mines of the major alumina players in the country like Nalco, Hindalco, Balco, Hindalco (Indal), Malco and the mines of GMDC which are either fully mechanized or semi mechanized. Among these, the Panchpatmali bauxite mine of NALCO in Orissa accounts for about 40% of the country’s production.

Major deposits are in East Coast falling in Visakhapatnam and East Godavari districts of Andhra Pradesh and Phulbani, Sundergarh, Bolangir, Sambalpur, Kalahandi, Keonjhar and Koraput districts of Orissa. Other important bauxite occurrences are located in Bilaspur, Surguja and Raigarh districts of Chhattisgarh, Satna, Balaghat, Rewa and Jabalpur districts of Madhya Pradesh, Lohardaga and Gumla districts of Jharkhand, Kolhapur, Raigad, Satara, Sangli, Sindhudurg, Ratnagiri and Thane districts of Maharashtra, Kutch, Jamnagar, Junagarh, Amreli, Bhavnagar, Sabarkantha, Surat, Valsad and Ahmedabad districts of Gujarat State.

The third largest Aluminium Company in India is held by Sterlite Industries which has 51% share holding and by GOI, which holds the remaining 49%. Balco has capacity of 200,000 tpa of calcined alumina, 100,000 tpa of aluminium metal and 270MW power plant.

Bharat Aluminium has its own captive open cast, semi-mechanized, Bauxite mines. Overburden, which is in the form of soil & laterite, is first excavated by a combination of shovel / excavator and dumper in order to expose ore-zone. Mainpat is the primary operative mine, which produces approximately 500,000 tpa of Bauxite. Approximately 100,000- 150,000 tpa Bauxite is procured on commission basis from non-captive mines. There are plans to open another deposit named Bodai-Daldali in Kawardha District in the near future. Manipat has about 5.0 million tonnes of reserves while Bodai-Daldali has 7.11 million tonnes of Bauxite reserves. BALCO uses VSS (Vertical Stud Soderberg) technology to produce Aluminium from Alumina.

The method of mining is open cast semi-mechanized. Overburden, which is in the form of soil & laterite, is first excavated by a combination of shovel / excavator and dumper in order to expose ore-zone. Then the ore zone is drilled and blasted. The blasted ore is subject to sorting in order to upgrade the “Run of Grade” to “Plant Feed Grade” i.e. 48% Al2O3. Sorting is carried out at the mine-face and the rejects associated in the ore zone are back-filled concurrently. The area is then leveled and afforested. The sorted ore is then trucked to the Korba complex for further processing.

Mainpat is the primary operative mine, which produces approximately 500,000 tpa of Bauxite. Approximately 100,000- 150,000 tpa Bauxite is procured on commission basis from non-captive mines. There are plans to open another deposit named Bodai-Daldali in Kawardha District in the near future. Mainpat has about 5.0 million tonnes of reserves while Bodai-Daldali has 7.1 million tonnes of Bauxite reserve.

MALCO was taken over by the Sterlite group, a subsidiary of Vedanta resources in 1995.

MALCO has coal-based Captive Power Plant at the same location. Its captive Bauxite Mines are located within the nearby ranges of Yercaud, Kolli and Palani in Tamil Nadu.

MALCO has its own Bauxite mines in the state of Tamil Nadu at Yercaud (Salem district) having reserves of 0.8 million tonnes and Kolli Hills (Namakkal district) having reserves of 0.9 million tones and has a 40,000 tpa smelter and 80,000 tpa refinery at the Mettur Dam complex

Method of mining used is open cast semi-mechanized. Overburden, which is in the form of soil & moorum, is first excavated by a combination of shovel/excavator and dumper in order to expose ore-zone. Then the ore zone is drilled and blasted. The blasted ore is subject to sorting in order to upgrade the “ROM Grade” to “Plant Feed Grade” i.e. 34% Al2O3. Sorting is carried out at the mine-face and the rejects associated in the ore zone are back-filled concurrently. The area is then levelled and afforested. The sorted ore is then trucked to the Mettur Dam Complex for further processing.