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1618467257201_0 - SURFACE MINING Methods.pptx
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- 7. Surface mining • Itis a type of mining in which soil and rock overlying the mineral deposit (the overburden) are removed. • Surface mining is used when deposits of commercially useful minerals or rocks are found near the surface; that is, where the overburden is relatively thin or the material of interest is structurally unsuitable for tunneling (as would usually be the case for sand , and gravel.(
- 8. • It isthe opposite of underground mining ,in which the overlying rock is left in place, and the mineral removed through shafts or tunnels. • In most forms of surface mining, heavy equipment, such as earthmovers, first remove the overburden. Next, huge machines, such as dragline excavators or Bucket wheel excavators, extract the mineral.
- 32. • The fieldof slope stability encompasses the analysis of static and dynamic stability of slopes of earth and rock-fill dams, slopes of other types of embankments, excavated slopes, and natural slopes in soil and soft rock . • Slope stability investigation, analysis (including modeling), and design mitigation is typically completed by geologists ,engineering geologists , or geotechnical engineers . Slope Stability
- 33. • If theforces available to resist movement are greater than the forces driving movement, the slope is considered stable. • A factor of safety is calculated by dividing the forces resisting movement by the forces driving movement. In earthquake-prone areas, the analysis is typically run for static conditions and pseudo- static conditions, where the seismic forces from an earthquake are assumed to add static loads to the analysis .
- 39. Types of movement •SLIDES
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- 45. • In open-pitmining a Stripping Ratio refers to the amount of waste rock removed to recover ore. For example, a stripping ratio of 3:1 means to recover one ton of ore you must remove three tons of waste rock. • A large Stripping Ratio is less economically efficient than a small one, because that means more rock will need to be moved without generating revenue. • If The ratio is going to be too large, then underground mining will usually be more efficient .
- 46. Where minerals occurdeep below the surface—where the overburden is thick or the mineral occurs as veins in hard rock— underground mining methods are used to extract the valued material. Surface mines are typically enlarged until either the mineral deposit is exhausted, or the cost of removing larger volumes of overburden makes further mining no longer economically viable .
- 48. Problem-4: Calculate the valueof stripping ratio, if a mining company says that during the year 5.4 million tons of material was mined and that the mill processed was 2.1 million tons.
- 49. • “Open pitmining "refers to a method of extracting rock or minerals from the earth through their removal from an open pit or borrow . • "Mountaintop removal mining" (MTR) is a form of coal mining that uses explosives to blast "overburden" off the top of some Appalachian mountains.
- 55. Types of surfacemining "Strip mining“ • It is the practice of mining a seam of mineral by first removing a long strip of overlying soil and rock (the overburden). • It is most commonly used to mine coal or tar sand. Strip mining is only practicable when the ore body to be excavated is relatively near the surface.