News Engineering, Manufacturing

Pre-shredding moves up a gear

10 November 2021

Scrap; EZR; Pre-Shredder

What are the benefits of processing pre-shredded scrap ? 

Before a possible pretreatment,
today a real added value

The last Best Available Technique (BAT) Reference Document for Waste Treatment published by the European Comission already pointed out the main benefit of the pre-shredder:

 

“The pre-shredder rips up the material fed into the shredder thus ensuring a maximum size for the input materials. Pre-shredding can also reduce the risk of deflagrations, for example when car wrecks that may contain fuel traces are treated.”

 

Up to recent time, the limited output has limited the generalisation of this equipment:

 

“The pre-shredder may not be available for larger shredders whose requisite throughput would need several such units.”

 

The 3 shafts pre-shredders and first generations with lower installed power have been replaced by more efficient MTB pre-shredders with:

    • Higher torque at low and high rotation speed,
  • Higher throughput,
  • Easier maintenance.

 

the new pre-shredder generation, a real benefit!

Scrap processing companies are looking at efficient ways to reduce their shredding operating cost and optimize the scrap recovery. In the past, Ferrous sorting was the main focus. Today the Non-Ferrous recovery including the Shredder light fraction is a key component to the payback of any shredder processing line.

 

One key concept for an optimal sorting is to get homogeneous calibration to reach the best performance of the magnetic and optic separators. A pre-shredded material is not only increasing the shredder production but also improving the output material quality.

 

The first three-shaft pre-shredders were not designed to process high volume or baled scrap. The new generation of MTB pre-shredders are now able to process more than 100 t/h of car bales. Moreover, the main benefit of the three-shafts pre-shredder to provide smaller output sizing is now available in the two-shaft MTB range with even more flexibility thanks to:

 

  • Adjustable shaft spacing
  • Interchangeable claws
  • Full independent shaft speed control

 

New electric drive for energy saving

Pre-shredder requirements are very high. Even when the rotation stops, the shafts need to deliver the maximum torque to break heavy and difficult material. For longer time, manufacturers have relied on hydraulic drives to achieve these requirements.

 

The hydraulic drive is however a compromise between speed and torque. In addition, the multiple steps of energy transformation (Electric -> Mecanic -> Hydraulic -> Mecanic) decrease the overall efficiency of the equipment with significant amount of energy loss in heat. Finaly, the installed power is not the one on the shaft but an indication of the available power somewhere along the drive.

 

Alternative standard electric motors, inefficient to deal with the require torque/speed, have been replaced by high-torque motors with very high torques even at low speed. The innovative MTB multi-pole electric drives are a real alternative to hydraulic system with a direct transfer of electrical energy in mechanical energy.

MTB’S New Range of eDrive pre-shredder 

MTB team and its partners has spent a lot of effort to develop a new generation of pre-shredders with eDrive. The result is exceeding our expectations. It did not only become an alternative to hydraulic but we are confident to have laid a milestone in the pre-shredder evolution.

EZR 1600/63e

380 HP
Servo Drives
installed power

 

145 to 220 mm
5.7 to 8.7 In.
Shaft spacing

EZR 2200/88e

Up to 99 t
at tooth’s end

 

Up to 20 RPM
for fast shaft

EZR 2500/99e

67 t
at tooth’s end
from 0 to 14 rpm

 

975 HP
Installed power
directly on drive

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