Sustainable Mining by Drilling Operation
Korean Metals Exploration has identified a new surface mining method which could potentially be used on its projects in South Korea. Modern, ‘cutting-edge’ mining and drilling processes are proposed by the Company. Large diameter Pile Top RC drilling technology is well suited to mining the mineralized veins found within the Company’s projects.
Novamera Inc. has developed an innovative and new mining method called Sustainable Mining by Drilling (“SMD”). SMD uses conventional Pile Top RCD drills used successfully by the Construction Industry and the proven Reverse Circulation Drilling (“RCD”) method to extract ore from steeply-dipping narrow vein deposits.
Pile Top Reverse Circulation Drill Rig
Circulation Drilling (“RCD”) with optimized airlift is a proven method for Pile Top RCD drill rigs. There are several manufacturers of Pile Top RCD drills including MH Wirth (Germany), LDD (UK) and Buma CE (South Korea). The drill string components are of modular design and suitable for any depth and hole diameter up to 4.5 metres. Hole diameter should be selected to optimize rate of penetration and vein width. A Pile Top RCD fitted with a 2-metre diameter drill bit is estimated to be capable of “mining” about 7 tonnes of Ore per hour.
The Pile Top RCD is capable of drilling holes with inclinations from 90o (vertical) to 72o. The working deck has variable geometry to keep it level.
Drilling depth is increased by simply adding another drill pipe, using an on-board derrick crane. Each Drill Pipe run is 3m in length and is attached by 8 bolts to the next pipe using a pneumatic air-impact wrench. A Drill Rod Pipe Stabilizer is usually fitted to every 3 runs. The Stabilizer is a non-revolving Drill Pipe fitted with arms which expand out to fit to the hole wall, helping to add stability to the RCD drilling process.
Principle of operation
The crawler-track version of the Pile Top RCD is mobile and can move independently along a cleared line above the vein structure to be mined. The Bottom Hole Assembly is fitted to the gear box-power swivel and inserted into a ‘pilot hole’, previously drilled into the vein structure as part of the Novamera SMD system.
Water supplied from a small dam fills the Production Hole. External Compressed Air is injected into the Drill String above the Drill Bit. This reduces the density of the fluid and the Water Column outside the Drill String is pushed down by atmospheric pressure. Water outside the Drill String flows down, passes the Drill Bit and enters the Pick-up Inner Tube.
Rotation of the Drill Pipe and Bit cuts into the Rock and drilling gradually proceeds to depth. Extra Drill Pipe is added to the Drill String in 3 metre lengths.
The released Rock Cuttings become mixed with Water to form a Slurry, which rises inside the Inner Tube to the surface and is Discharged into the Mud Collection system. Water is separated from the Solids in the Slurry and recycled back to the Drills water supply.
After reaching the final depth, the Drill Pipe and Stabilizers are removed and the Pile Top RCD moves onto the next Hole.
Tailings from the Mill is returned to the drill site as a paste, mixed with Portland Cement and Backfilled into the Hole void. Rehabilitation and revegetation of the drill site can then commence rapidly.
Advantages of Sustainable Mining by Drilling
The advantages of the Sustainable Mining by Drilling method are very significant, and include:
- All operations are conducted from surface. Safety is maximized, as no personnel work underground in “harms way”.
- SMD replaces numerous expensive and complex underground mining and crushing equipment requiring highly skilled operators, resulting in reduced Capital and Operating Costs, reduced environmental footprint, lower carbon emissions and energy consumption. These factors are considered likely to result in community support for SMD mining operations.
- Ore is reduced to -2mm size in a slurry form, which can be fed directly into a mill circuit.
- The drill cuttings can be separated into solids and liquids using a hydrocyclone and the water can be re-cycled with minimal loss for re-use by the Pile top RCD.
- SMD is a highly selective, precision surgical mining operation with minimal dilution. High-grade zones can be targeted and multiple faces can be mined simultaneously, being only dependent only on the number of drills.
- Mining and blending of high-grade and low-grade ores is possible.
- After exiting the mill circuit, the waste rock is returned as paste, mixed with cement and backfilled into the completed Production Hole void. There are no waste dumps or tailings dams. The rehabilitation of each drill site can commence immediately after backfilling.
- Low consumables and spare parts consumption = Low maintenance cost.
- Interchangeable drill bits are specifically engineered to suit different rock types and vein widths.
- Remote operation of the RCD Drills is possible, further enhancing operator safety.