| Chapter 24 - Passes, Bins, and Chutes |
| Number |
Topic |
Rule of Thumb |
| 24.01 |
Ore Passes |
The flow regime in an ore or waste pass is determined on the basis of the largest particle size of muck (not some average size). This is the fundamental reason for a grizzly at the dump. For example, if a raisebored pass has a diameter of 2m, particles with a diameter of 0.5m will flow freely (4:1 ratio), particles greater than 1m will not flow (2:1 ratio), and sizes in between will produce intermittent hang ups. Source: Dr. J. D. Just |
| 24.02 |
Ore Passes |
A circular ore pass raise must be 25% larger in area (section) than a rectangular raise to have similar resistance to hangups due to arching. Source: Kirk Rodgers |
| 24.03 |
Ore Passes |
A hangup due to arching is avoided when the ore pass dimension is five times the diameter of the largest particle. Source: Beus, Iversen and Stewart |
| 24.04 |
Ore Passes |
Shot rock containing more than 10% fines passing a 200-mesh screen cannot be sent down an ore pass without incurring blockage from cohesive arching. Source: Rudolf Kvapil |
| 24.05 |
Ore Passes |
Ore passes should be spaced at intervals not exceeding 500 feet (and waste passes not more than 750 feet) along the draw point drift, with LHD extraction. Source: Jack de la Vergne |
| 24.06 |
Ore Passes |
The best inclination for an ore pass in a hard rock mine is 70 degrees from the horizontal. Source: Bob Steele |
| 24.07 |
Ore Passes |
The minimum inclination for a short ore pass is 50 degrees from the horizontal. For a long pass, it is 55 degrees. Source: Harry Pyke |
| 24.08 |
Ore Passes |
Ore passes cannot be employed to any advantage where the ore dips shallower than 55 degrees from the horizontal. Source: Doug Morrison |
| 24.09 |
Ore Passes |
The thrust per cutter on a raisebore head must exceed the compressive strength of the rock by 5,000 psi to achieve a satisfactory advance rate. Source: Jim Seeley |
| 24.10 |
Ore Passes |
When a hang-up is blasted down in an ore pass, the stress induced on the gate from concussion (detonation wave) is only about ¼ the stress introduced by the impact of falling rock. Source: Blight and Haak |
| 24.11 |
Ore Passes |
The size of a glory hole in an open pit should not be greater than the cross-section of the haul trucks that dump into it. Otherwise, you are bound to lose a truck, sooner or later. Source: Sergio Chavez |
| 24.12 |
Bins |
An underground bin larger than 15 feet in diameter should be inclined at the bottom, away from the outlet, at an angle of 65 degrees from the horizontal, to obtain mass flow (as opposed to rat-holing) where wet fines are present. Source: Doug Hambley |
| 24.13 |
Bins |
To determine the live load capacity of a bin in a hard rock mine, the angle of repose may be assumed at 35 degrees from the horizontal (top of bin) and the angle of drawdown assumed at 60 degrees. Source: Al Fernie |
| 24.14 |
Chutes |
For all but sticky ores, the ideal inclination of a chute bottom is 38 degrees from the horizontal. Source: Bob Steele |