Mobile screeners are track-mounted or wheeled screening plants that are being used to screen material effectively onsite. The most common mobile screening plants are tracked scalping and incline screens (often referred to as deck screens). In addition, there are also trommel screen, star screens, and horizontal screens. This article covers scalpers and incline screens only. Mobile screening plants are also used on conjunction with a mobile crushing plant to size material at a high rate effectively.
Selecting the right mobile screener requires considering different aspects of your business and materials.
Often the process starts with one specific problem. To find the perfect mobile screener type you need to look at all future aspects of your business as well. Most important is the feed size that comes with your feed material. A scalping screen might be best used for demolition & contracting applications where you deal with bony and inconveniently shaped materials. An incline screen on the other hand works extremly well in sand & gravel and aggregates applications.
Are you looking to produce 2, 3, 4 or even more finished products at the same time? This determines how many screen decks your mobile screener needs.
| Screen deck(s) | Finished products | Suggested screen |
|---|---|---|
| 1 | 2 | Simple box screen or a mobile scalper (e.g. in a 2 way split configuration) |
| 2 | 3 | Scalping or Incline Screen |
| 3 | 4 | Incline Screen |
Also called scalpers or direct feed screen is suitable for a large variety of applications from heavy-duty scalping to precision screening. Typical applications are sand & gravel, shot rock, soils, dirt, mulch, asphalt millings, aggregates, and street sweepings. The feeder is not covered and the path of bulky material is not obstructed travelling over the top screen deck and on the discharge side. Therefore, this type screen is ideal for scalping fines from bulky feed materials (e.g. asphalt fines from slabs, aggregates from shot rock, dirt from mixed excavated debris). However, you can use this type screen also for precision screening after a crushing process to produce up to 3 finished products (fines, clean stone, and oversize product).
| Pros | Cons |
|---|---|
| ➕ Works well with bulky material mixed with fines | ➖ Limits with fast precision screening and small finished specs |
| ➕ Heavy-duty & robust design | ➖ 3 products only vs up to 4 products with incline screens |
| ➕ Application versatility | ➖ Sometime less convenient to feed with a wheel loader |
| ➕ Easy access to screen box | |
| ➕ Easy to change of screen media | |
| ➕ No hydraulic jacks needed to operate the plant |
Ideal for feeding bulky material such as asphalt slabs, shot rock, and excacvated materials. This type screen is best fed with an excacator. Optional hopper wing extensions facilitate feeding with a wheel loader from the rear. Some scalping screens can be also fed from the side of the machine.
The screen box of scalping screens can be fitted with a variety of screen media. A common configuration is a more heavy-duty screen media (e.g. punch plate, fingers, or bofor bars) on the top deck to absorb the initial brute force of the material dropping onto the screen and a square mesh or elongated mesh screen on the bottom deck for precision screening.
By design, scalping screens always have 2 decks producing up to 3 finished products.
The oversize material is discharged to the front of the machine without any obstructions.
Various manufacturers offer different sizes. The nomenclature of the screen if often related to the screen-box size.
| Mini scalper screen | Compact scalper | Smaller scalper | Large scalper | Big Production | |
|---|---|---|---|---|---|
| Screen-box | 3.5′ x 7′ | 4' x 9' | 5' x 12' | 5' x 16' | 6' x 20' |
| Screen-decks | 2 | 2 | 2 | 2 | 2 |
Mobile incline screens work brilliantly for small materials such as sand & gravel or aggregates (already small crushed product). The steeper screening angle allows for faster screening. This type screen is not designed to handle bulky material at all. A hydraulic tipping grid over the feed hopper prevents large material entering the screen. The tipping grid will tilt by the touch of button on a radio remote control that the operator keeps in his cab to dicard material to the side. This type screen isl also popular in aggregate processing because it can be easily tied into a closed circuit crushing and screening setup.
| Pros | Cons |
|---|---|
| ➕ Excells with small feed material | ➖ No large infeed material possible |
| ➕ Fast screening of small specs | ➖ Hydraulic jacks to support the weight of the feed hooper |
| ➕ Easy feeding with a wheel loader | ➖ Limited application range |
| ➕ Up to 4 finished products | |
| ➕ Optional rinser kit for a cleaner end-product |
The large feed hopper is designed to be fed with wide buckets. The tipping grid can be activiated through a radio remote control clearing the grid from any oversize rock.
The feed conveyor brings the material to the top of the machine. Once on top the material makes a 180° turn rolling back down. If there were any oversize pieces in the feed ,material this is most likely where it would get stuck.
Mobile incline screens are available in 2 or 3 deck configurations producing 3 or 4 finished products respectively. Also the screen angle is steeper and can be adjusted hydraulically. Due to the steeper screen angle you can use different type screen media such as speed harps.
Fines get discharged in the front of the machine and the mids and overs get discharged on the side.
Various manufacturers offer different sizes. The nomenclature of the screen if often related to the screen-box size. Some varients offer a rinser kit for wet screening.
| Small sizer | Medium Sizer | Medium sizer | Large sizer | |
|---|---|---|---|---|
| Screen-box | 5' x 12' | 5' x 14' | 5' x 18' | 5' x 22' |
| Screen-decks | 2 | 2 or 3 deck | 2 or 3 deck | 2 or 3 deck |
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