The following processes are exercised from grass root exploration to the production of commercial Bauxite.
- 1 Exploration
- 2 Open Pit Mining
- 3 Benefication
- 4 Haulage
- 5Stock Piling
- 6 Drying
- 7 Transhipping
Explorations involves systematic drilling and pitting of potential exploration target areas identified based on number of exploration tools like satellite imageries (SRTM, thematic mapper, etc.). Exploration drilling/pitting patterns are designed from wider grid (150X150) closed in to (40X40) meter. Based on the outcome of the exploration drilling results mineral resource and ore reserves are identified and delineated.
Since the bauxite mineralization within SMHL mining lease occurs on hill slopes, the mineable ores are extracted on 2-3 meters benches. It is a trucks and excavators loading operation in which 20-30 tons capacity of trucks are utilized to haul ores from mining pit to beneficiation plant.
It is a process in which the metal assays of run off mines are improved and enhanced. Beneficiation is carried out in wet through washing plant and dry through crusher and vibrating power screen plant. The process flow sheet is presented for both wet and dry and they are self-explanatory.
Haulage operations are being performed from different mine pits to run off mine pads located at respective plant sites as well as from respective plant sites to loading port of Nitti-2. Majority of haulage operations are being out-sourced and they are being performed by 10-wheelers 3-4 axle’s trucks with 16-17 cubic meter capacity. The haulage roads within the concession are designed to accommodate safe haulage trucks movement based on Mine Safety and Health Administration (MSHA) standards.
Stock piles are designed for temporary storage of run off mines as well as commercial bauxite based on quality, processability parameters for the ease of better material handling and supply. Washed bauxite and dry beneficiated bauxite received from respective production plants are stocked in various areas in the port based on quality and moisture parameters. Stock piling also facilitates the appropriate blending of bauxite to meet the required quality parameters of final commercial products.
Drying is the process of reduction of natural moisture content (NMC) in bauxite. This process is being performed at the loading port in the dry kiln (120 tons/hour capacity) as well as through natural sun drying. This process enables to meet the final required moisture specification of commercial bauxite as per off-take agreement as well as comply with international maritime solid bulk cargoes (IMSBC) codes.
This operation is being carried out between loading port (Nitti-2) and high Sea (buoy 4) which is 32 nautical miles apart from each other. SMHL owned river-fleet consists of Barges and Push boats are engaged in the transportation of commercial bauxite. The capacity of barges varies between 2000-2500 metric tons. Handymax to Supramax Ocean Going Vessels (OGV) are used to export bauxite from Sierra Leone under FAS or FOB terms.