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| Chapter 16 - Headframes and Bins |
| Number |
Topic |
Rule of Thumb |
| 16.01 |
Wood Headframe |
The maximum height of a wood headframe is 110 feet. The maximum rope size for a wood headframe is 1.25 inches diameter, which corresponds to an 8-foot or 100-inch diameter double-drum hoist. Source: Jack de la Vergne |
| 16.02 |
Steel Headframe |
A headframe (for a ground mounted hoist) should be designed with the backlegs at an angle of 60 degrees from the horizontal and the rope flight from the hoist at an angle of 45 degrees. Source: Mine Plant Design, Staley, 1949 |
| 16.03 |
Steel Headframe |
It is better to design a headframe (for a ground mounted hoist) such that the resultant of forces from the overwound rope falls about 1/3 the distance from the backleg to the backpost. Source: Mine Plant Design, Staley, 1949 |
| 16.04 |
Steel Headframe |
No members in a steel headframe should have a thickness less than 5/16 of an inch. Main members should have a slenderness ratio (l/r) of not more than 120; secondary members not more than 200. Source: Mine Plant Design, Staley, 1949 |
| 16.05 |
Steel Headframe |
Main members of a modern steel headframe may have a slenderness ratio as high as 160 meeting relevant design codes and modern design practice. Source: Steve Boyd |
| 16.06 |
Steel Headframe |
The cost of a steel headframe increases exponentially with its height while the cost of a concrete headframe is nearly a direct function of its height. As a result, a steel headframe is less expensive than a concrete headframe, when the height of the headframe is less than approximately 160 feet (at typical market costs for structural steel and ready-mix concrete). Source: Jack de la Vergne |
| 16.07 |
Steel Headframe |
At the hoist deck level of a tower mount headframe for Koepe hoisting, the maximum permissible lateral deflection (due to wind sway, foundation settlement, etc.) is 3 inches. (This may favor a concrete headframe.) Source: R. L. Puryear |
| 16.08 |
Steel Headframe |
A concrete headframe will weigh up to ten times as much as the equivalent steel headframe. (This may favor the steel headframe when foundations are in overburden or the mine site is in a seismic zone.) Source: Steve Boyd |
| 16.09 |
Headframe Bins |
To determine the live load of a surface bin for 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 |
| 16.10 |
Headframe Bins |
A bin for a hard rock mine will likely experience rat-holing (as opposed to mass flow) if the ore is damp, unless the dead bed at the bin bottom is covered or replaced with a smooth steel surface at an angle of approximately 60 degrees from the horizontal. Source: Jennike and Johanson |
| 16.11 |
Headframe Bins |
The live-load capacity of the headframe ore bin at a small mine (where trucking of the ore is employed) may be designed equal to a day’s production. For a mine of medium size, it can be as little as one-third of a day’s production. For a high capacity skipping operation, the headframe should have a conveyor load-out, either direct to the mill or elevated to separate load-out bins remote from the headframe. A conveyor load-out requires a small surge bin at the headframe of live load capacity approximately equal to the payload of 20 skips. Various Sources |
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