June 24, 2019

Rotorshredder makes recycling meatballs even more efficient

Electric motors and motor armatures as ‘meatballs’

Whether waste incineration or large shredder: Electric motors and motor armatures remain. These are called ‘meatballs’ because of their typical color and shape.

BHS-Sonthofen increases amount of copper recovered from motor armatures and electric motors

BHS-Sonthofen has developed a new procedure for processing meatballs in order to increase the amount of copper recovered. Electric motors and motor armatures represent a small fraction of waste from incineration or large shredders, and it is difficult to cleanly separate them by type. Yet they contain a good deal of valuable copper, whose share is up to 22 percent. This impressive new procedure features a Rotorshredder optimized for this process, subsequent materials separation and copper processing using a rotor impact mill.

Innovations often emerge from different paths. In this case, a Dutch customer approached the team at BHS-Sonthofen. Their goal was to optimize a process for recycling electric motors and motor armatures in order to significantly increase non-ferrous metal concentrations without impacting operational efficiency. This request was based on ever-increasing demand for high purity metals, particularly from Asian markets where they are highly prized.

The traditional method uses a hammer mill to crush the meatballs. Given the traditional design of the hammer mill, crushed parts come into contact with each other. The resulting new metal compounds become entangled and subsequently almost impossible to separate into homogeneous fractions. In addition, the hammer mill’s ejectors are designed in such a way that the individual parts inevitably get caught. The greatest challenge faced by the BHS engineering team was to treat the materials in a manner such that clean separation could be achieved.

Impact crushing with the Rotorshredder

The experts at BHS have many years of experience as well as in-depth knowledge of the process – and this paid off. “The most important requirement, along with high product quality, was that the discharged material be of the highest purity possible. In order to attain this goal, we conducted a thorough and in-depth analysis of the process together with the customer. Multiple detailed tests performed at our technical center with the customer’s material served as the foundation for this analysis,” says Nikolas Kaufeisen, Sales Manager at BHS-Sonthofen. “The result is a solution that improves the process in several ways, one that is tailored exactly for this specific application.”

The meatballs are selectively broken down in the BHS Rotorshredder. The hammers, mounted on a vertical shaft, transfer impact forces to the feed material, and the pieces collide with the openings of the grid segments in the doors, which act as stators. The engineers at BHS adapted the mounting brackets for the grid segments especially for this application. This was done in such a way that the adhesions from waste incineration cannot collect behind them, which would otherwise cause the machine get clogged up over time. Grid fixings arranged vertically instead of horizontally prevent material from collecting behind the grid openings. The ejection system is also designed in such a way that the shredded parts drop down across the full width of the discharge conveyor belt and do not come in contact with each other again. This ensures that the material cannot become entangled.

After material discharge, the shredded metal is transported under an overhead magnet mounted alongside the discharge conveyor belt to separate the ferrous fraction from the rest of the material. BHS also optimized this process. If the overhead magnet had been installed at a right angle to the conveyor belt, as would typically be the case, longer iron parts would drag over the belt and become entangled with other parts. Thanks to this optimization, the remaining parts move along the conveyor without becoming caught or stuck on the belt. A cross-flow sifter then uses a stream of air to release the copper portion of the material from stainless steel parts and heated, non-magnetic iron parts.

Copper is processed in the rotor impact mill to deliver a high-quality metal concentrate

The rotor impact mill (RPMX) from BHS is well suited for removing impurities from copper fractions extracted from the material. This is an upgrade to the traditional rotor impact mill, a high-performance crusher with a vertical shaft and unique impeller rotor. The RPMX for recycling applications stands out because of its higher circumferential speed and a smaller milling gap. Copper wires can also be processed, even though their small size had made it difficult to recycle them up until now. The quality of the individual parts improves significantly with the rotor impact mill: Discoloration on the surface of the wire caused by oxidation during waste incineration is removed. The machine also releases the remaining insulation from the copper wires and ensures an optimal particle shape that enables clean separation by type using air separation systems.

The result is a high-quality metal concentrate that is of the same quality as copper recycled from cables. Customers are highly satisfied with the process. At present, there are two of these systems in use in the Netherlands and another one in western France.

 

Extraction of high-grade copper concentrate

BHS-Sonthofen’s upgraded process for recycling meatballs makes it possible to produce high-quality copper concentrate.

Rotor shredder for targeted crushing

The grid segments and impact hammers in the Rotorshredder from BHS-Sonthofen ensures high-precision crushing.

Rotor impact mill for processing the copper fraction

The BHS Rotorshredder crushes meatballs reliably. Special adaptations to the machine’s design ensure that the parts do not become entangled.

After crushing and sorting, the rotor impact mill from BHS processes the copper portion of the material so that oxidations and any adhesions remaining from the waste incineration process are removed.

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