Regional geology.
The area constitutes central part of the extensive laterite-capped plateau of the Maikal Range hills. In plains to the north-western part of the area around Mawai and Kathaitola, gneissose and schistose rocks form the core of the range, whereas around Kukrapani and Taregaon in the south-east, phyllite, slates and quartzites belonging to Chilphi Group are exposed. In the lower part of the plateau, narrow patches of Lametas, represented by calcareous gritty sandstones and pink & white clays are seen in the Kanai river section at Kukri. These are overlain by horizontally disposed basaltic lawa flows of Deccan Trap. Good exposures of Deccan Trap are noticed along the Kukrapani Daldali ghat section. The traps are capped by about 25 m thick laterite. Bauxite is normally found within upper part of the laterite capping.

The Bodai-Daldali deposits are located approximately 260 km from Korba in the Kawardha district of the state of Chhattisgarh.

The Chhattisgarh bauxite deposits are situated over a plateau with steep scarps on both sides, at an elevation of approximately approximately 940 metres above the surrounding land, for Bodai-Daldali. Bauxite is generally one metre to three metres thick and lies within a laterite sequence overlying thick tertiary basalts of the Deccan Traps. The cover of laterite and thin top soil is up to five metres thick but is generally less than two metres. Bauxite outcrops around much of the plateau rims.

A typical profile of the Chhattisgarh deposits comprises topsoil and soft overburden above the laterite. The upper laterite consists of hard, lose or indurated bauxite pebbles and boulders with a clear contact with the underlying hard bauxites. The bauxite occurs in discontinuous lenses up to four metres in thickness with laterite infilling joints and fractures with the bauxite. The contact with the softer lower laterite is usually gradational and irregular.

The bauxite is hard with a natural moisture content of 5.0% to 10.0%, with an in-situ density of 2.4 tonnes per metre to 2.4 tonnes per metre3. It comprises primarily gibbsite with boehmite and minor diaspore. The reactive silica content is low and iron is present in the form of hematite and aluminous goethite.

All mining and transportation at the mine are undertaken by contractors.

The bauxite deposit of Bodai-Daldali Bauxite mines is situated over the plateau and the ground terrain is flat.

As the Bauxite deposit is found in shallow depth, therefore opencast mining method has been adopted. All workings are being carried out by mechanised way, by using excavator of 2.5 to 4.6 Cum size, dumper of 15- to 25 tons capacity, blast hole drill machine, 110 mm dia, dozer and now crusher with screening plant is being proposed instead of manual sorting and sizing.

The over burden is top soil & soft laterite of 0 to 3.00 meters thickness after which there is a hard overburden of thickness varying from 0 to 6.00 meters. The thickness of ore zone is 0 m to 4.00 m and is flat.

In general working is of shallow depth of avg. 4 to 6 m (maximum up to 10 m), therefore concurrent backfilling method has been adopted.

The general practice is to scrap the top soil separately by dozer, or excavator dumper combination and use it for directly spreading over already backfilled compacted area. Drilling and blasting is practiced in hard OB benches and ore benches. Excavation is done by excavator dumper combination.

Since the deposits are boulder in nature, bauxite needs to be separated from laterite and murrum. It is proposed to mechanically crush and screen the ore so as to obtain desired grade bauxite with acceptable silica content.

The backfilling is done in same sequence as it is found in the nature, i.e. hard OB in bottom, then soft OB above the hard OB, then top soil.

The height of OB benches is kept maximum of 6 meters and the ore benches are kept generally of 1 to 4 meters of height as per thickness of ore body.

The blast boreholes of 2 to 4 m depth are being drilled by DTH drills, which are required for blasting. Controlled blast technique is used for keeping the ground vibration, blast through and noise within permissible limit. The blast design and charge per delay are kept strictly as per the requirement of DGMS.

The bauxite extraction limit for Bodai-Daldali Mines granted by MoEF is 1,250,000 tpa.

For getting the bauxite of desired grade and size, from blasted ore muck, it is subjected to mineral dressing, and this will be carried out by two ways.

* Where the deposits is homogeneous in quality, then the ROM will be processed, through mechanized way of mineral dressing by crusher and screening plant sets
* And, where deposit is of heterogeneous w.r.t. Quality, then the ROM will be subjected to manual method of sorting and sizing.