Separating metals and plastics from shredded electronics ideally requires the upstream process to send a constant flow to the separation plant. Depending on how the shredder is fed and run, surges of material can make their way downstream causing poor quality. If the shredder is overfed, jams can occur more frequently and increase the downtime. If there is too little material on the conveyor, the shredder is not being utilized to its full capacity.
The customer needed a way to monitor the shredder real time performance and use this data to automate the shredder feed. Consistent hourly throughout was the goal.
As a company who has specialized experience in electronic recycling, Converge Engineering, was able to design and build an innovative solution that fit the customer’s needs.
The Converge Engineering team researched different monitoring methods for each of the bottlenecks. The first step was used a digital conveyor belt scale on the shredder discharge to monitor the shredder throughput. A rolling average of throughput was used to decide how fast to run the shredder infeed conveyor and when to pause it.
The next monitoring control added was an ultrasonic level sensor that monitored the pile height on a roll back conveyor feeding the metal sensor sorter line which is near the end of the sorting plant. Depending on pile height, some material is diverted into another conveyor and onto a holding buffer to prevent overfeeding of the sensor line.
The third control method envisioned used an airflow sensor to monitor the compressed air volume consumed in the metal sensor sorting line. Even though the weight per hour would be consistent and the pile height is monitored feeding the metal sensor sorter, situations could arise where the bulk density of the shredded product varied or metal content was extra dense. In these cases, this third feedback loop enabled all contingencies to be covered by slowing down the rollback conveyor to feed the sensor machine at the correct rate.
- The design allows shredding by “wire” regardless of the material.
- Very little operator interface required
- The downtime was minimal to install
- Plant capacity went up due to consistency
- The line is well balanced yielding proper quality
- Data is logged and allows deeper analytics of line performance over time