| Chapter 17 - Conveyors and Feeders |
| Number |
Topic |
Rule of Thumb |
| 17.01 |
Costs |
An underground mine is more economically served by a belt conveyor than railcars or trucks when the daily mine production exceeds 5,000 tons. Source: Al Fernie |
| 17.02 |
Costs |
As a rule, a belt conveyor operation is more economical than truck haulage if the conveying distance exceeds 1 kilometer (3,280 feet). Source: Heinz Altoff |
| 17.03 |
Costs |
The ton-mile cost of transport by belt conveyor may be as low as one-tenth the cost by haul truck. Source: Robert Schmidt |
| 17.04 |
Costs |
The installed capital cost of a long belt conveyor system to be put underground is approximately equal to the cost of driving the heading in which it is to be placed. Source: Jack de la Vergne |
| 17.05 |
Costs |
Operating maintenance cost per year for a belt conveyor is 2% of the purchase cost of equipment plus 5% of the belt cost. To this should be added belt replacement every five to 15 years (five for underground hard rock mines). Source: Hans Nauman |
| 17.06 |
Feed and Feeders |
In a hard rock mine, the product from a jaw crusher to feed a conveyor belt will have a size distribution such that the -80% fraction size is slightly less than the open side setting of the crusher. For example, if the open side setting of the underground jaw crusher is 6 inches, then the d80 product size = 5¾ inches. Source: Unknown |
| 17.07 |
Feed and Feeders |
For an apron feeder, the bed depth of material fed should be uniform and equal to one-half the width of the feeder. Source: Dave Assinck |
| 17.08 |
Feed and Feeders |
A vibratory feeder is best designed for a bed depth of about half its width. Source: Bill Potma |
| 17.09 |
Feed and Feeders |
The free fall of crushed ore to a belt must not exceed 4 feet. Chutes, baffles, or rock boxes should be employed to reduce impact and save belt life. Source: Heinz Schober |
| 17.10 |
Feed and Feeders |
The horsepower requirements for apron feeders listed by manufacturers are generally low. They should be increased by a factor of 30 to 50% to take into account considerations like starting torque, starting when cold, when the bearings are sticky, and when the bearings become worn. Source: Reisner and Rothe |
| 17.11 |
Feed and Feeders |
Power requirements for apron feeders are about twice as high as for comparable belt feeders. Source: Reisner and Rothe |
| 17.12 |
Feed and Feeders |
A well-designed jaw crusher installation has the lip of the chute overlapping the throat of the vibrating feeder by 400 mm (16 inches) to prevent spill resulting from the inevitable blowback of wayward fines. Source: Jean Beliveau |
| 17.13 |
Feed and Feeders |
75-90% of belt wear occurs at the loading points. Source: Lawrence Adler |
| 17.14 |
Belt Conveyor Design |
On well-engineered systems, using appropriate controls to limit acceleration, the (static) factor of safety for belt tension can be reduced from 10:1 to 8:1 for fabric belts and from 7:1 to 6:1 for steel cord belts. Source: D. T. Price |
| 17.15 |
Belt Conveyor Design |
The standard troughing angles in North America are 20, 35, and 45 degrees. In Europe, they are 20, 30, and 40 degrees. A 20-degree troughing angle permits the use of the thickest belts, so the heaviest material and maximum lump size can be carried. A troughing angle of 35 degrees is typically employed for conveying crushed ore. Source: Unknown |
| 17.16 |
Belt Conveyor Design |
For conveying crushed ore, the cross-section of the material load on the belt can usually be accurately calculated using a 20-degree surcharge angle. It should be considered that when conveying over a long distance, the dynamic settling of the load could reduce the surcharge angle to 15 degrees. Source: Al Firnie |
| 17.17 |
Belt Conveyor Design |
Finely crushed or ground ore must be loaded on a flat section of the belt. A good rule of thumb is to leave a bare minimum of 8, and preferably 12, feet of horizontal belt before a vertical curve is even started. Source: Robert Shoemaker |
| 17.18 |
Belt Conveyor Design |
The availability of a belt conveyor is 90%; if coupled with a crusher, the availability of the system is 85%. Source: Wolfgang Guderley |
| 17.19 |
Belt Conveyor Design |
Stacker conveyors (portable or radial) should be inclined at 18 degrees (32%) from the horizontal. Source: Dave Assinck |
| 17.20 |
Belt Conveyor Design |
To prevent a run of fines from reaching the mineshaft, the minimum length of a conveyor to a loading pocket should be such that there is a slope of 15% between the loadout chute and the lip of the station at the shaft. Source: Virgil Corpuz |
| 17.21 |
Belt Conveyor Design |
In-pit conveyors should not be inclined more than 16½ degrees (29%) from the horizontal. Source: John Marek |
| 17.22 |
Belt Conveyor Design |
A downhill conveyor should not be designed steeper than 20%. This is the maximum declination for containing material on the belt under braking conditions. Source: Al Firnie |
| 17.23 |
Belt Conveyor Design |
The pulley face should be at least 1 inch wider than the belt for belts up to 24 inches wide and 3 inches wider for belts greater than 24 inches. Source: Alex Vallance |
| 17.24 |
Belt Conveyor Design |
The length of skirt boards should be at least three times the width of the belt. Source: Jack de la Vergne |