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| Chapter 3 - Mining Methods |
| Number |
Topic |
Rule of Thumb |
| 3.01 |
Method Selection |
A flatly dipping ore body may be mined using Blasthole when the height of ore exceeds 100 feet (30m); otherwise, it is mined Room and Pillar. Source: John Folinsbee |
| 3.02 |
Inclination |
Ore will not run on a footwall inclined at less than 50 degrees from the horizontal. Source: Fred Nabb |
| 3.03 |
Inclination |
Even a steeply dipping ore body may not be drawn clean of ore by gravity alone. A significant portion of the broken ore will inevitably remain (“hang”) on the footwall. If the dip is less than 60 degrees, footwall draw points will reduce, but not eliminate, this loss of ore. Source: Chen and Boshkov |
| 3.04 |
Stope Development |
The number of stopes developed should normally be such that the planned daily tonnage can be met with 60% to 80% of the stopes. The spare stopes are required in the event of an unexpected occurrence and may be required to maintain uniform grades of ore to the mill. This allowance may not be practical when shrinkage is applied to a sulfide ore body, due to oxidation. Source: Folinsbee and Nabb |
| 3.05 |
Stope Development |
In any mine employing backfill, there must be 35% more stoping units than is theoretically required to meet the daily call (planned daily tonnage). Source: Derrick May |
| 3.06 |
Ore Width |
Blasthole (longhole) Stoping may be employed for ore widths as narrow as 3m (10 feet). However, this narrow a width is only practical when there is an exceptionally good contact separation and a very uniform dip. Source: Clarke and Nabb |
| 3.07 |
Ore Width |
Sequence problems are not likely in the case of a massive deposit to be caved if the horizontal axes are more than twice the proposed draw height. Source: Dennis Laubscher |
| 3.08 |
Footwall Drifts |
Footwall drifts for blasthole mining should be offset from the ore by at least 15m (50 feet) in good ground. Deeper in the mine, the offset should be increased to 23m (75 feet) and for mining at great depth, it should be not less than 30m (100 feet). Source: Jack de la Vergne |
| 3.09 |
Dilution |
A ton of ore left behind in a stope costs you twice as much as milling a ton of waste rock (from dilution). Source: Peter J. George |
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