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GEOL-4015
Lecture 8 -Mining Methods 2
| Underground Mining Methods | Unsupported, supported or Caving, meow |
| Underground Mining Methods-Unsupported | -Room & Pillar -Stope & Pillar -Shrinkage stoping -Sublevel stoping |
| Underground Mining Methods -Supported | -Cut and Fill Stoping -Stull Stoping -Square-set stoping |
| Underground Mining Methods -Caving | -Longwall -Sublevel Caving -Block Caving |
| Unsupported Underground Mining | -Self supporting method that requires no major artficial system of support to carry the weight of the overlying rock and overburden. Relies on the walls and natural pillars. |
| Room and Pillar Mining | 3 Categories: Classic, post and step. Used to mine flat lying ore deposits in which the mined out areas (rooms) are separated by pillars of about the same size. Orthogonal at regular intervals. forms rectangular or square pillars for natural support. |
| Room and Pillar Mining-ore types | Ore deposits best suited for Room and Pillar Mining -Coal -Potash -Sodium Chloride -Limestone -Metallic deposits |
| Stope and Pillar Mining | Similar to room and pillar mining. Most widely used for hard-rock. Openings are higher than they are wide, or benching or slabbing techniques are used. |
| Shrinkage Stoping | Vertical stoping method. overhand method where the ore is mined in horizontal slices from bottom to top and remains in the stop as temporary support to the walls and to provide a working platform for the miners. |
| Sublevel Stoping | Veritcal mining method where large open stopes are created within the vein. open stop is meant to be occupied bu the miners and all work (drilling and blasting) must be performed from sublevels. 3 methods:Blasthole, open-ended and vertical crater retreat |
| Sublevel Stoping -Blasthole | Miners create a vertical slot at one end of the stope then work in the sublevels to drill a radial pattern of drillholes. after a set has been drilled, they are loaded and blasted into the open stope. Must be well planned |
| Sublevel Stoping -Open-ended | Slot is developed at one end of the stope. then drill parallel holes from top to bottom of the designated stope using a sublevel at the top of the stope that is the width of the stope. vertical slices of the ore are blasted into open stope |
| Supported Mine Methods | Methods that require some type of backfilll to provide substantial amounts of artificial support to maintain stability in the exploration openings of the mine. Used when the production openings will not remain standing during their life. |
| Cut and fill stoping | Very common, only supported method used today. ore is extracted in horizontal slices and replaced with backfill material which is done after each slice is removed. Backfill:waste fill, pneumatic fill, hydraulic fill with dilute slurry, high-density hydrau |
| Cut and fill- Overhand | Used in deposits that have strong rocks. In the stope area the miners work under the roof and generally have sufficient head room to move their equipment easily through the stope. |
| Cut and fill- drift and fill stoping | -Used for ground conditions that are worse than those for traditional overhand cut and fill stoping. -Can be done overhand or underhand . openings are kept small. horizontal slice is removed by drifting forward, after each drift its filled |
| Cut and fill -underhand stoping | Used in poor quality rock. horizontal slices are taken from the top to the bottom of the stope area. to stabilize the surrounding rock after each slice the area is filled with cemented hydraulic fill. |
| Stull stoping | not used too often. expensive. coupled with room and pillar mining. Timbers and pillars are used for support. When the timbers are in a horizontal deposit they are called posts. in a pitching deposit they are called stulls. |
| Square-set stoping | Least Used . not used in NA at all. most expensive. small blocks of ore are systematically extracted and replaced by prismatic framework of timber sets, framed into an integrated support structure and backfilled level by level to provide support. |
| Square-set stoping Con't | Each timber set consists of a post, cap and girt. Can be done in overhand, underhand or horizontal directions. |
| Caving Methods | Methods associated with induced, controlled massive caving of the ore body, the overlying rock or both. Rock Mechanics are applied to ensure that caving does occur |
| Caving- Longwall method | used for flat lying, thin tabular deposits (coal) in which the long face is established to extract the mineral. While the panel is being mined out the longwall is kept open by supports that form a cantilever or umbrella. roof caves in as mining progresses |
| Caving- Sublevel Caving | Used on near vertical deposits. mining progresses downward while the ore between sublevels is broken overhand, the overlying waste rock caves into the void created as the ore is drawn off. Since only the waste is caved, the ore must be drilled and blasted |
| Caving- Block caving | Masses, panels or blocks of ore are undercut to induce caving, permitting the broken ore to be drawn off below. if there is a hangwall or capping above the ore it will cave too. Developed to mine low grade copper porphyry deposits quickly during WWI |
| Block caving-Block | Block-Regular rectangular/squares are undercut in a checkerboard pattern. the blocks are mined out in alternating order |
| Block caving-Panel | continuous strips of ore are mined across the ore body. Manageable areas are caved simultaneuosly and retreated in panels. |
| Block caving-Mass | no area division, irregularly sized prisms of ore are mined. the plane of contact between the ore and waste is inclined as undercutting proceeds across the ore body. |
| Conventional Mining | Production cycle=cut+dril+blast+load+haul. multitude of faces:therefore the cutting machine operator, the driller, the blaster and the loader all work in seperate areas with less delay. Computer simulations |
| Continuous Mining | Primarily in coal since 1950. Production cycle=mine+haul. depends on the ruggedness and reliability of the continous miner. eliminated steps of cutting, blasting and loading. soft rock applications (coal, salt, potash) |
| Auxiliary Operations | 1)Health and safety (gas and dust control, ventilation, noise abatement) 2)Environment:flood, water 3)Ground control:roof controls(bolts timber...) 4)power supply and distribution |
| Auxiliary Operations Con't | 5)water and flood control 6)Cleanup, waste 7)Material supply 8)Maintenance and repair 9)lighting 10)Communications 11)Construction 12)Personnel Transport |
| Raise Boring | A machine that excavates a circular hole between two levels in a mine, without the use of explosives. drills down to a tunnel. Reamer is attached which drills larger hole while moving upward. |
| Alimak Mining Method | Raise breaks through to the upper access. stope is blasted out from the bottom up |
Created by:
Nxavier