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To produce extremely clean shredded product, magnetic separation may not be sufficient. We recommend our Cascade Cleaning System to be installed on the ferrous stream, after magnetic separation. The system design is based upon terminal settling velocities of various product densities. Shredded product is introduced into the top of a Cascade Chamber. A High Volume, Low Pressure Air stream is introduced at the bottom, and travels countercurrent. The light fraction is conveyed to a Cyclone with a Rotary Airlock, which separates the solids from the airstream. The remaining air returns to the fan inlet via a closed loop duct system. When shredded product is introduced, there is always additional outside air that “leaks” into the system. This must be offset by either exhausting that same amount to atmosphere (our competitor’s designs), or by our unique, secondary closed loop, which is our patent #7051880 “Zero Bleed” No emission design.

Technical Design Features:

• Steel Support Structure, with Wrap around Platforms, Ladder access.
• Airstream parts: Heavy Plate Construction, AR400 in wear areas.
• Multiple Access Doors for ease in internal inspection & cleanout.
• Bolt-in AR 400 Liners in Cascade Cleaning Chamber & Flat Back Inlet Elbows.
• Industrial Class IV Fan w/ V-Belt Drive, TEFC Motor w/ Guards.
• Adjustable Airflow Damper & Bypass Gate for adjusting Product “Cut Point”.
• Unique, Patented “Zero Bleed” No emission design.
• Produces cleanest scrap in the industry.

Options: Variable frequency drive, Ceramic lining.


Hammermills’ “Zero Bleed” System is a modification to be added to existing or new air classifier systems which use a “closed loop” design for separating light from heavy fraction. The purpose of this system us to eliminate any bleed off air to atmosphere. For the wellbeing of the environment, this will result in the elimination of particulate being emitted into the atmosphere. For the benefit of the equipment operator, this will result in the elimination of an emission source which requires permitting with the presiding authority.

Typical metal shredder processes use Air Classifiers systems in the process. The primary use is for separating shredded steel from shredder fluff (non-metals). Depending on the original equipment supplier’s design, the bleedoff to atmosphere generally ranges from 5% to 10% of the total air being circulated in the closed loop system. Most systems are operating at a volume and pressure that will accommodate the worst conditions relationg to the process to provide the best results. This generally results in excessive air volume for normal operating conditions.

Another application in the metal shredder process is the separate non-ferrous lighter metals from shredder fluff (non-metals). Excessive air flow results in a loss of metals.

Bleedoff air to atmosphere is required for all current existing technology air classifier systems because the solid product which is to be classified, allows ambient air to leak into the system with the product. Due to the configuration of these air classifier systems, the air that leaks in must be exhausted to atmosphere, after the separation process has been accomplished. If the excess air is not bled to atmosphere, the system will become unbalanced causing various other undesirable areas to pressurize and attempt to leak, finally causing a degradation of process quality and uncontrolled dust leakage to atmosphere.

The “Zero Bleed” System is designed with 4 major components for accomplishing the task of no exhaust to atmosphere, while not affecting process quality. These components consist of:

1. Balance Airgate to allow solid process material to enter the air classifier chamber while minimizing the leakage of ambient air into the same chamber.
2. Re-injection Nozzle & Duct for connection to the original bleedoff stack and positioning adjacent to the Balance Airgate.
3. Secondary Rubber & Metal Seals mounted upstream of the re-injection nozzle, to eliminate the remaining pressure differential between atmospheric air and residual internal negative pressure.
4. Variable Frequency Inverter. Control for providing optimum air flow for all process conditions without needing “worst case” excessive air volume, and maximizing the “Zero Bleed” System performance.

The “Zero Bleed” System is easily retrofittable to all Hammermills’ Cascade Cleaning Systems. They can also be adapted with the same ease to other suppliers air classifiers; such as the TSI “Z-Box”, Newell “ZigZag Box”, American Pulverizer’s cascade copy, and any other brand using a “closed loop” design. Adaptations will require additional engineering for interface to the “Zero Bleed” system.

While the “Zero Bleed” System does eliminate the exhaust stack and exhaust emissions, and should therefore logically eliminate the need to submit to any presiding authority, Hammermills International recommends that you contact your local consultant regarding permit procedures.