Apron vs Belt vs Vibrating Feeder: Which One and When
In crushing and screening plants, feeders are generally used to feed the crusher ahead of them evenly, at a set capacity and without problems. The crusher may be the primary crusher, which is the first to crush the material coming from the quarry, obtained by drilling and blasting, or a secondary or tertiary crusher, which crushes it at the second or third stage.
This article compares three types of feeder equipment side by side — the apron feeder vs belt feeder, and the apron feeder vs vibrating feeder — on feed size, duty, position in the plant, feed speed, moisture and abrasive material, and capacity. All feeder types are covered in a separate guide.
The Short Answer
Apron feeder vs belt feeder vs vibrating feeder at a glance
| Criterion | Apron feeder | Belt feeder | Vibrating feeder (hopper type) |
|---|---|---|---|
| Feed size | Maximum lump size 152–914 mm for widths between skirts of 457–1829 mm (reference values, Table 1) | The maximum material size for belt feeders is around 100 mm. | Recommended material speeds listed for three size bands: <100 mm, 100–300 mm, >300 mm (Table 2) |
| Duty | Apron feeders that feed primary crushers in particular are heavy-duty feeders. Hopper feeders can also be medium- or light-duty apron feeders. | Relatively medium or light duty compared with primary feeders | Relatively medium or light duty compared with primary feeders |
| Position in the plant | Main (primary) feeder, on its own or combined with a grizzly screen or roller screen | Under a hopper, ahead of secondary and tertiary crushers. Generally used to feed material of limited size stored in hoppers. | Under a hopper, ahead of secondary and tertiary crushers. Generally placed under a hopper of 10–20 m³ capacity. |
| Feed speed | Capacities listed at chain speeds of 4, 6, 8 and 10 m/min (Table 3) | Can be selected between 0.08 m/s and 0.5 m/s; 0.25–0.35 m/s is the belt feeder speed range most used in crushing and screening plants. | Recommended material speed: 0.28 m/s (<100 mm), 0.25 m/s (100–300 mm), 0.22 m/s (>300 mm) (Table 2) |
Feed Size and Maximum Lump Size
In crushing and screening plants, apron feeders that feed primary crushers in particular are heavy-duty feeders.
When sizing an apron feeder, the designer must take into account the maximum lump size of the material to be fed, among other factors. Table 1 can be used as a reference for the average and maximum lump sizes that can be fed according to the width between the apron feeder skirts.
| Width between apron feeder skirts, mm | Average lump size, mm | Maximum lump size, mm |
|---|---|---|
| 457 | 76 | 152 |
| 610 | 102 | 203 |
| 762 | 152 | 305 |
| 914 | 203 | 406 |
| 1067 | 254 | 508 |
| 1219 | 305 | 610 |
| 1372 | 356 | 711 |
| 1524 | 406 | 813 |
| 1829 | 457 | 914 |
Table 1. Reference values of lump sizes that can be fed, by width between apron feeder skirts
The full apron feeder sizing method is covered in a separate guide.
Belt feeders are generally used to feed material of limited size stored in hoppers. The maximum material size for belt feeders is around 100 mm.
For hopper vibrating feeders, Table 2 gives the recommended material speed values.
| Material size, mm | Vibrating deck angle, ° | Material speed, m/s |
|---|---|---|
| <100 | 8–12 | 0.28 |
| 100–300 | 4–8 | 0.25 |
| >300 | 0–4 | 0.22 |
Table 2. Recommended material speed values
Moisture, Clay and Abrasive Material
In the material speed calculation for vibrating grizzly feeders, µm is the factor related to the moisture content and contamination of the material: µm is taken as 1 for dry material, 0.8 for moist material and 0.6 for moist and clayey material. For hopper vibrating feeders, the material property factor µm varies between 0.8 and 1; the smaller values are for light, moist, sticky materials.
Abrasive material: belt feeder vs apron feeder
The main elements of heavy-duty apron feeders are the same as the main elements of the undercarriages of crawler dozers or excavators, which are widely used in the industry. These elements require no lubrication or much maintenance, and their wear is at a minimum level.
Large and abrasive materials are not suitable for belt feeders, because they can easily damage the top cover of the feeder belt. The damage that abrasive and sharp-edged materials do to the belt top cover can be offset to a certain extent by making the cover thicker.
Capacity and Surge Profile
Primary crusher feeder: material dumped from trucks
Feeders that feed primary crushers are heavy-duty and have a hopper of quite rigid construction. They have to withstand the impact of material dumped from trucks. We call these feeders main feeders or primary feeders.
Table 3 gives approximate volumetric capacity values of apron feeders at a bed depth of 1000 mm and different chain speeds.
| Feed capacity, m³/h | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Bed depth d, mm | Chain speed, m/min | Apron pan width, mm | ||||||||
| 900 | 1050 | 1250 | 1500 | 1800 | 2100 | 2400 | 3000 | 3500 | ||
| Width between skirts, mm | ||||||||||
| 800 | 950 | 1150 | 1400 | 1700 | 2000 | 2300 | 2900 | 3400 | ||
| 1000 | 4 | 192 | 228 | 276 | 336 | 408 | 480 | 552 | 696 | 816 |
| 6 | 288 | 342 | 414 | 504 | 612 | 720 | 828 | 1044 | 1224 | |
| 8 | 384 | 456 | 552 | 672 | 816 | 960 | 1104 | 1392 | 1632 | |
| 10 | 480 | 570 | 690 | 840 | 1020 | 1200 | 1380 | 1740 | 2040 | |
Table 3. Approximate capacity values of apron feeders depending on apron pan width and chain speed
The apron feeder capacity formula is covered in a separate guide.
Secondary and tertiary crusher feeder: continuous feed from a hopper
Hopper feeders are generally used in crushing and screening plants to feed secondary and tertiary crushers continuously, evenly and at the same capacity. If these crushers are not fed evenly, they do not work at the desired performance. For example, if cone crushers are not fed evenly and their crushing chamber is not full, wear increases considerably and bearing life shortens because of unbalanced loading. In vertical shaft impactors (VSI), the rock box does not form and crushing performance drops considerably.
These feeders are generally placed under a hopper of 10–20 m³ capacity.
The choice of belt feeder speed depends on the size distribution and abrasiveness of the material fed and on the structure of the hopper feed zone. Depending on these properties, it can be selected between 0.08 m/s and 0.5 m/s. The 0.25–0.35 m/s range is the belt feeder speed range most used in crushing and screening plants.
Capacity calculations for belt feeders and vibrating feeders are covered in separate guides.
Where Each Sits in the Flow Sheet
Depending on the physical properties, size distribution, contamination and moisture content of the material coming from the quarry, main feeders can be:
Vibrating grizzly feeders
Pan feeder with grizzly scalper or roller screen groups
Apron feeders
Apron feeder–grizzly screen or roller screen groups
Reciprocating feeders
Reciprocating feeder–grizzly screen or roller screen groups
Secondary and tertiary crushers, on the other hand, are fed by feeders placed under a hopper of a certain volume, which are relatively medium or light duty compared with primary feeders. We generally call these hopper feeders. They can be:
Vibrating feeders
Belt feeders
Medium- or light-duty apron feeders
MEKA Feeder Range
MEKA feeder product pages: apron feeder, belt feeder, vibrating feeder, pan feeders with grizzly scalper and wobbler feeder.
FAQ
How do apron and belt feeders cope with abrasive material?
The main elements of heavy-duty apron feeders are the same as the main elements of the undercarriages of crawler dozers or excavators; these elements require no lubrication or much maintenance, and their wear is at a minimum level. Large and abrasive materials are not suitable for belt feeders, because they can easily damage the belt top cover; this damage can be offset to a certain extent by making the cover thicker.
What is the maximum material size for a belt feeder?
The maximum material size for belt feeders is around 100 mm. Belt feeders are generally used to feed material of limited size stored in hoppers. Large and abrasive materials are not suitable for them, because they can easily damage the top cover of the feeder belt.
Why do secondary and tertiary crushers need to be fed evenly?
If these crushers are not fed evenly, they do not work at the desired performance. For example, if cone crushers are not fed evenly and their crushing chamber is not full, wear increases considerably and bearing life shortens because of unbalanced loading. In vertical shaft impactors, the rock box does not form and crushing performance drops considerably.
Which feeders are used under a hopper?
Secondary and tertiary crushers are fed by feeders placed under a hopper of a certain volume, which are relatively medium or light duty compared with primary feeders. These hopper feeders can be vibrating feeders, belt feeders, or medium- or light-duty apron feeders. Hopper vibrating feeders are generally placed under a hopper of 10–20 m³ capacity.
MEKA GLOBAL
