How to Determine the Proper Apron Feeder Size for Mining Applications
The Apron Feeder is specifically designed for handling large, high-density, abrasive and moisture-laden, and highly viscous materials, such as raw coal, iron ore, copper ore, nickel ore and limestone, etc.
In actual mining production, the specification of the Apron Feeder needs to be determined through comprehensive engineering calculations involving key parameters such as plate width, center distance, feeding capacity, maximum feed particle size and driving power.
Pan Width Selection
The width of the apron feeder directly determines the equipment’s carrying capacity and the maximum particle size of the material it can handle. The selection of the plate width mainly considers the maximum feed particle size of the material, the stacking state, the designed feeding volume, and the interface matching with upstream and downstream equipment.
Generally, the effective plate width of the apron feeder must meet the condition: plate width ≥ 2 to 3 times the maximum block size. This golden rule can effectively prevent large blocks of materials from getting stuck between the side baffles and ensure the smooth passage of the materials.
If the proportion of large rock in the material is high, or the material enters the feeding hopper directly without sufficient secondary blasting, then the plate width specification should be appropriately increased based on the conventional calculation.
Center Distance Selection
The center distance refers to the distance between the center of the head sprocket and the center of the tail sprocket of the Apron Feeder. It directly determines the actual conveying length of the equipment.
When choosing the center distance, factors such as the on-site space layout, the distance between the feeding point and the discharging point, whether inclined installation is adopted, and the daily maintenance passage should be considered. In conventional mining projects, the typical range of center distance is:
- Short-distance feeding: 3 m to 6 m
- Medium-distance conveying: 6 m to 15 m
- Long-distance conveying: 15 m and above
For large-scale primary crushing stations in mines, the Apron Feeder is usually installed below the feeding hopper, and the center distance should be strictly designed based on the actual physical distance between the outlet of the silo and the inlet of the primary classifier.
Maximum Feeding Size
The maximum particle size of the materials is an important indicator for determining the structural strength grade of the apron feeder. When selecting, not only the maximum size of the bulk materials should be considered, but also the proportion of large-sized materials, their compressive strength, and the blasting impact force should be evaluated.
According to common working conditions, the recommended plate width and operating parameters corresponding to different maximum feed particle sizes are as follows:
| Max Feeding Size | Recommended Models | Pan width(mm) | Rail(pcs) | Speed(m/s) | Capacity (m³/h) | Length(m) |
| ≤ 350 mm | BL800 | 800 | – | 0.01～0.25 | 50～350 | 2～15 |
| ≤ 470 mm | BL1000 | 1000 | 1 | 0.01～0.25 | 100～510 | 3～20 |
| ≤ 650 mm | BL1200 | 1200 | 1 | 0.01～0.20 | 120～595 | 3～20 |
| ≤ 680 mm | BL1400 | 1400 | 2 | 0.01～0.20 | 140～850 | 6～20 |
| ≤ 700 mm | BL1600 | 1600 | 2 | 0.01～0.20 | 320～1300 | 6～20 |
| ≤ 800 mm | BL1800 | 1800 | 2 | 0.01～0.15 | 500～1560 | 8～20 |
| ≤ 1000 mm | BL2000 | 2000 | 3 | 0.01～0.15 | 500～1850 | 8～20 |
| ≤ 1500 mm | BL2400 | 2400 | 3 | 0.01～0.15 | 500～2700 | 8～20 |
| ≤ 1800 mm | BL2800 | 2800 | 4 | 0.01～0.15 | 1000～4000 | 10～20 |
If there are a large number of extremely large rocks on the site, it is necessary to ensure structural safety by increasing the number of chain tracks (such as from single/double tracks to 3 or 4 tracks), enhancing the impact resistance of the trough plates, and increasing the power of the drive motor.
Capacity Matching
The processing capacity of the Apron Feeder is mainly determined by factors such as plate width, material layer thickness, chain speed, material bulk density, and filling coefficient. The core theoretical calculation formula is:
Q = 3600 × B × H × V × ρ × K
- Q: Processing capacity (t/h)
- B: Effective plate width (m)
- H: Material layer height (m)
- V: Operating chain speed (m/s)
- ρ: Material bulk density (t/m³)
- K: Comprehensive correction coefficient (affected by material fluidity, inclination angle, etc.)
In actual operation, the Apron Feeder mostly adopts a low-speed operation mode (usually between 0.01 and 0.25 m/s), and the advantages of low-speed operation are very obvious: it can significantly reduce the impact of materials on the chain and trough plates, lower mechanical wear, extend the service life of the belt chain and idler wheels, and improve the overall load-bearing stability of the machine.
Matching Of Crusher Capacity And Silo Buffer
Capacity Matching Principle
The designed processing capacity of the Apron Feeder should be slightly greater than or equal to the maximum designed capacity of the crusher. For example, if the primary crusher (such as a jaw crusher or mineral crusher) has a designed capacity of 1000 t/h, the rated processing capacity of the Apron Feeder is usually set at 1000 to 1200 t/h. This ensures continuous and stable material supply while avoiding frequent material accumulation in the upstream silo.
Silo Buffering And Flow Control
The Apron Feeder is not only a conveying device but also a key locking and quantitative feeding device, bearing the huge pressure of the material column in the upper silo and responsible for uniformly controlling the material flow entering the crusher. Considering the instantaneous impact and load fluctuations caused by truck unloading during mining operations, sufficient power and structural strength margin must be reserved during the selection and design process.
Technical Parameters Required For Apron Feeder Selection
In order to accurately calculate the model of the Apron Feeder, the configuration of the track chain, the driving power, and the structural strength, engineers need to collect the following core technical parameters:
Material properties
Material name (such as iron ore, copper ore, limestone, coal, etc.) and erosion characteristics.
Processing capacity requirements
Design rated processing capacity (t/h) and maximum peak processing capacity.
Material density
Bulk density (t/m³) and loose density.
Equipment center distance
The distance (m) between the center of the head sprocket and the center of the tail sprocket.
Installation method
Horizontal installation or inclined installation; if inclined installation, the specific inclination angle (°) must be clearly specified.
Maximum feed particle size
The maximum particle size of the material (mm).
Percentage of large-sized materials
The percentage of the maximum particle size ore in the total materials (%).
Upstream equipment structure
The design scheme of the Feeding Hopper, the size of the hopper opening or the structure drawing (used for calculating the material pressure under the hopper and the starting torque of the motor).
Downstream equipment type
Discharge and receiving equipment, such as Jaw Crusher, Mineral Sizer, coarse crushing reciprocating crusher or Belt Conveyor.
Working power conditions
The actual voltage (V) and frequency (Hz) at the site.
Note: The above parameters and selection range are for reference in the preliminary scheme planning. Due to the different material characteristics of different mining projects, the structure of the feeding hopper, the site space limitations, etc., the final selection specifications and power configuration need to be confirmed by professional engineers through detailed engineering calculations.
