Screen analysis - review of Metso ES horizontal screen

In the word combination "crushing and screening plant," the word "screening" is the second, indirectly pointing to a secondariness of screening function in the production of rubble. Crushers are more discussed, because they crush and cubiform crushed stone, unfairly overshadowing screens. This is wrong! There is no other way to produce rubble of high quality without effective screening. Let’s talk about screens.

The vast majority of screens that are used on Ukraine pits are inclined screen. They are good enough to separate by class fractions 5-20 or 20-40 mm at qualitative feed material. However, screens with small mash size are becoming less effective in case of small contribution of humidity or debris in the rock. Also, more and more pits start production of fine product size - 2-5 mm, in order to minimize dropout storages and to increase the production of useful fractions. These challenges are not acceptable using old GIL-52 screens.

Therefore, we have decided to pay attention to horizontal screens. At the best practice, they are considered to be the most effective solution for commercial screening, particularly for fines fractions due to the following factors:

  • The speed of the material on the deck below - thus more chances for the particle to be classified correctly. This is especially significant for the so-called critical class - particles similar in size to the size of the mesh;
  • Screens positioned horizontally - active screening surface is bigger. The maximum effect is obtained from decks with installed rubber or polyurethane screens, the thickness of which often takes a lot of useful screen area.
  • Elliptical screen motion - combines the advantages of circular and linear motions. Linea motions provide high screening efficiency and direction of the material along the deck, circular motions protect screens from plugging, as vectors acting on the particles direct them to different directions.
  • High acceleration (up to 6G) - more effective stratification. Material on the screen becomes pseudo-liquid, and the main task at this stage is to send up big particles and allow small particles to reach the deck surface for correct classification soonest. The higher the acceleration – the more effective the process is.

Despite this, horizontal screens are not widely used by local companies. This is because of high cost of such screens for our pits; screens are of high price due of the high requirements for structural strength and expensiveness of three synchronizing shafts - the main driving elements of the horizontal screen.

Metso offered last year a new approach to horizontal screens and the world market obtained a new revolutionary concept based on the use of two self-synchronizing asymmetric operating mechanisms. ES screens have been successfully tested and now we can say with confidence that this innovation is a head taller and more efficient than triple-shaft system. Moreover, horizontal screens are no longer the most expensive machines of a pit, and investments into this equipment pay off very quickly.

The effectiveness of the new screen is 25% higher than of the inclined screen with a similar screening area. The difference is especially noticeable screening of fine material - for example screening of 0-5 mm by 2-5 and 0-2 mm. Also, the screen is effective with wet material that makes it possible to be less dependent on the quality of the rock mass in rainy periods.

Metso is traditionally known for its high quality and reliability. Metso ES screen frame has no welds to the transverse sections, thus ensuring frame strength for a long period of operation.

There is no welding on the side plates, this guarantees optimal durability and increased resistance to mechanical stress. Durability of the structure is also ensured by hack-bolts. In the screen design there is no mechanical synchronizing gear, transmission gear, oil leakages are excluded, and all this along with reliable system to supply axle grease minimizes downtime and maintenance time. Metso ES screens’ security settings comply with the most advanced industry standards. Between decks’ space was increased by more than 50% compared with similar horizontal screens, providing easier and safer access to the equipment during maintenance. Metso ES screen is also equipped with screening covers on the coiled springs to minimize the risk of pinching by the rubber dampers. Additionally, screens’ drive belts are segregated with housing, providing high security level, and the grease is supplied from a central grease unit. Lack of transmission gear reduces noise.

Due to the low installation height of the horizontal screens, they are suitable for renovations when it is needed to install a new larger screen on the existing site. This eliminates the need to change the design of the feed and discharge conveyors. For comparison: ES302 screening surface is 11,4 m2, it has lower installation height than GIL-52 screen that has 7,8 m2 screening surface. So for no reason at all screening capacity is increased by half!

New screens operate at many pits worldwide and show excellent results. We recommend these screens for those rubble pits that need to achieve the following:

  • screening the range of 2 to 10 mm
  • classification of wet or contaminated material
  • classification of material with varying or non-uniform particle size distribution
  • replacement of ordinary inclined screens to increase productivity
  • operation in locations with small installation height.

We are confident that the new product is worth of attention with innovative solutions that will make to look at the horizontal screens again. Together with Metso traditional quality and good service support, these screens will poses their place under the conveyors in Ukraine pits.

 

Metso is a world leader of equipment for production of non-metallic materials. The main advantage of the company is a full range of crushing and screening equipment, which makes possible to implement a variety of projects - from the replacement of the single crusher to the "turnkey" installation of complete lines. Metso manufactures jaw, cone, impact and gyratory crushers as well as inclined and horizontal screen. Each type of equipment is the leader in its class and is constantly being improved. In Ukraine company is represented in Krivoy Rog (Head Office), Kiev, Komsomolsk, Donetsk and Korosten. Metso equipment successfully operates on the pits of such companies as "Unigran", CRH, PSG, “Kowalska”, Lafarge, Basalt AG, Korosten rubble plant, "Altcom" and many others. More than 150 pieces of equipment were installed.

 

 

 

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26-04-2016 16:48