The initial motivation for the widespread adoption of preshredders in the United States was the need to prevent explosions in shredders. However, these machines have become increasingly popular for various other purposes, such as optimizing throughput and increasing the efficiency of primary shredders in scrapyards. That’s one of the main topics covered in the November/December 2023 issue of Metals Recycling magazine.

A preshredder is a machine characterized by low speed (4 to 20 revolutions per minute) and high torque, designed to reduce and homogenize items like vehicles, bales, logs, white goods, etc., before they are fed into a primary shredder.

Over the last two to three years, there has been a growing interest in preshredders in the United States, diverging from the previous emphasis on building larger, shredders. Currently only 25% of shredding operations involve preshredding, but this percentage is expected to rise in the future as scrapyards increasingly recognize the advantages and safety benefits associated with having a preshredder.

Metal scrap recovery: what is the best preshredder?

In the context of shredding applications, a twin-shaft shredder is recommended for preshredding, primarily due to its efficiency in achieving the desired size and material quality. This allows for pre-sorting before the subsequent shredding phase, ensuring a purer product.

Consider the Blue Devil, a versatile tool that can serve as a pre-shredder or be seamlessly integrated with other cutting-edge technologies to align with your ultimate goals.

A compelling illustration of our impact can be seen through Alfa Recycling in Germany, where the acquisition of the Blue Devil led to a remarkable 30-40% increase in production. Moreover, the shredder’s downtime has been dramatically reduced, and the risk of explosions has been nearly eradicated, greatly enhancing safety.

Karl-David Schlehenkamp, CEO of Alfa Recycling, affirms, “Currently, we are producing approximately 250 tons per day!”

Advantages of preshredders in scrap operations

Why preshredding has gained popularity in the U.S? Here’s a list of advantages:

  • Identifies large unshreddable items in the feedstock.
  • Increases throughput at the primary shredder by maintaining a consistently filled infeed conveyor.
  • Produces a more uniform feedstock for hammermill processing.
  • Safely shreds baled scrap that would otherwise be challenging.
  • Reduces wear and damage to the primary shredder.
  • Lowers electrical power consumption at the primary shredder.
  • Operates without an operator; computer-controlled and requires only material feeding.
  • Demands minimal maintenance.
  • Combines higher throughput and reduced wear for fewer man-hours per ton at the shredder plant, offsetting the preshredder investment.