Premier minerals has extensively focused exploration on the bay of Bengal Beaches, Islands and shaoals of Bangladesh. Resently some research has been made in the three mightly rivers systems the Meghna, Padma and Jamuna.
Mineral Sands Exploration and Technique
Mineral Sands exploration is to establish ore reserves, their volume and grade and so compute the life of the mining operation and the potential profit. Systematic prospecting of beach placer deposits
must precede the investment of funds for acquisition. Faulty conclusions resulting from insufficient or incorrect data will usually lead either to failure or to expenditure which is
disproportionate to the size and value of the deposits.
The main consideration in selecting a testing method is to ensure that it gives a sufficient approximation of the true value of the deposits.
Exploration is usually undertaken in three stages with each succeeding stage depending upon the result of the previous one.
They are respectively, 1. Reconnaissance 2. Scout drilling 3. Close boring and computation of mineral reserves.
Geologists select areas for exploration by researching an area's geology, topography, soil types and geological history (Reconnaissance).
Areas are drilled with a widely spaced grid to identify any occurrence and concentration of minerals (Scout drilling).
If the results are promising, samples are taken from a more closely spaced grid (Close boring). Identifying mineral for new mine sites involves a systematic process of surveys, sampling analyses and evaluation.
During drilling, attention is paid to recording the presence of ground water and base rock, and the detail description of sands with panning results.
After each hole is drilled it is filled in or plugged using cuttings to prevent injury to livestock or native animals.
If drill samples contain significant heavy minerals, further analysis determines the proportions of valuable minerals and their suitability for commercial use.
During the period of exploration in the licensed area under Teknaf Upazila, PML conducted shallow Seismic Refraction Survey and Electrical Resistivity Survey followed by Hand Flipping Drilling to collect sub-surface data of the areas.
PML carried out detailed exploration activities by Percussion Drillings in a grid-pattern. The average depth was 10 meter. Samples were collected at each one meter of interval to carry out the lab analysis of the representative samples.
The collected samples were analyzed by Bangladesh Atomic Energy Commission, Geological Survey of Bangladesh and the Department of Geology, Dhaka University.
Hand Auger Drilling
In most beach mineral placers where the sediments are fine grained, sand samples at shallow depth and relatively
unconsolidated hand auger provides the cheapest and most reliable method of sampling.
The hand auger consists of extendable steel rods, rotated by a T – shaped handle.
Auger drilling is operated with a helical screw which is driven into the ground with rotation
until it is filled; and then lifted out of the borehole to be emptied. The process is repeated
until the required depths is reached or stoped by consolidated, hard material.
Percussion drilling method is used to achieve higher depth penetration. Hand auger is not suitable below the water table whereas the easiest option to collect sample below the water table is percussion drilling method.
This equipment is widely used in our country for soil testing in building construction and large infrastructure