Mixed Results

On average, more than 78 percent of all materials we collect are either reused or turned into raw materials that are reintroduced into the marketplace by our company and its downstream processors. This compares favorably to most shredding operations, which can only convert about 50 percent of their inputs into recoverable product, while the remaining material is consumed in waste-to-energy plants or is landfilled.

The downside of this model is that there are many small and difficult to disassemble products that are often time-consuming and expensive to separate by hand. Hard-to-reach fasteners or glues make manual disassembly a daunting task. Once batteries and other hazardous materials are removed from these electronic devices by hand, we send these devices off to smelters or shredders that are only able to recover minimal amounts of materials for recycling, with the contaminants being burned off or ending up in landfill fluff.

In the fall of 2006, our company was awarded a grant from the Wisconsin Department of Natural Resources (DNR) to install and test a processing line to shred and mechanically separate hard-to-disassemble electronic devices into recoverable material streams. When used in combination with manual disassembly, we believed this shredding and separation system would increase our domestic e-scrap processing yields with minimal capital investment.

By introducing this automated separation technology, our goal was to increase our recovery rate by 14 percent for a total recovery rate of 89 percent. If successful, we expected more demanufacturing operations to procure and operate similar technology, because it would make both economic and environmental sense.

We used proceeds from the DNR grant to help us invest more than $150,000 to purchase and install a new shredding and sorting line into our processing facility in Madison. The equipment consists of a self-dumping cubic-yard box hopper, pre-shred sort table, feed conveyor, shredder, discharge conveyor with cross-belt magnet and sort conveyor. The equipment takes up a relatively small footprint of less than 500 square feet and one to two people can operate the machinery, depending on the electronic devices that are being processed.

The system’s material handling equipment (including the dumping hopper and conveyors) eliminates lifting and reduces the chance of injury to staff. The pre-shred sort table allows operators to visually inspect the materials and remove unsafe items, such as batteries, lamps and CRTs, so that only appropriate equipment continues up the cleated-belt conveyor to the shredder.

The conveyor dumps the equipment into the shredder’s hopper, which then triggers a ram to force the material through the high-speed teeth of the shredding unit. The materials pass through a 2- or 4-inch screen (depending on the material being processed) and are then taken away by the discharge conveyor.

A cross-belt magnet downstream of the shredder picks off ferrous metals, while the remaining fractions are distributed across a flat-belt conveyor. One or two operators then inspect these fractions and pick off any additional recoverable materials by hand. The remaining fractions are collected in a cubic-yard box at the end of the final conveyor.

This very simple shredding and separation system attempts to pull off easily recoverable ferrous scrap for local recovery and keeps the remaining fractions large enough to allow for hand picking of valuable circuit board scrap or plastic. The remaining unsorted fraction could then be shipped to a company with a more advanced automated shredding and separation system in order to recover other valuable raw materials from the mixed materials stream.

After nearly 18 months of study using the new shredder and cross-belt magnet, we came up with mixed results. Depending on the equipment being shredded, we either improved or diminished our recovery values and throughput.

Successful recovery employing the new equipment was almost entirely dependent on the percentage of steel and circuit boards in the material. Network hubs and routers generated an average of 77 percent steel, 5 percent low-value boards and 11 percent high-value boards.
Previously, our downstream processor only recovered steel from these units, with the remainder ending up as landfill fluff. With our new separation technology, we can now sell the separated circuit boards to appropriate smelters for recovery. As a result, we generate more than 3.5 times greater economic returns on these hubs and routers by sorting out the circuit boards for recovery.

In contrast, very few fractions from shredded phones could easily be picked off for recycling using this system. We found negligible steel and only 5 percent of the fractions contained recoverable circuit boards. The remaining mix became contaminated and could not be separated for additional recovery. However, manual disassembly of phones produced a much cleaner recovery stream at a similar throughput.

Another disappointment was the shredder’s performance when processing VCRs and DVD players. The shredder’s ram failed to push VCRs with metal bottoms through the its teeth, and these devices needed to be removed by hand from the shredder.

While we found a few improvements in recovery yield for some items, the overall results of this experiment fell far short of our goal. While this simple shredding and separation line is effective as a low-volume pre-shredder appropriate for media destruction and initial size reduction, it does not improve recovery yields in light of its limits in generating small, uniform fractions that can be automatically separated into different material streams.

At the close of this grant project period, I was able to visit a high-volume e-scrap shredding and separation operation in Canada. This company operates a multi-million dollar processing facility, including a series of shredders and granulators that reduce mixed materials to a uniform size. Once reduced to about 2 millimeters, much of the dissimilar materials are liberated from one another and can then be separated by eddy current, optics, cyclone and other methods. Typically, these types of operations generate mixed plastic, ferrous, aluminum and copper-rich material streams.

However, these systems have limitations, as well. CRTs, LCD screens with backlights and toner cartridges cannot be safely and effectively shredded, separated and recovered using these systems. In addition, to be economical to install and operate, these systems demand high volumes of incoming materials to offset the significant capital investment in equipment. While shredding and separation technology has improved recovery yields from electronic devices throughout the years, they still cannot match the recovery yields of demanufacturers.

We learned our lesson through this grant project. If we want to process small and hard-to-disassemble products through shredding and automated separation, we would prefer to contract with an environmentally responsible, high-volume, heavily capitalized processor that offers shredding and automated separation rather than invest an additional $150,000 in what is essentially a pre-shredder with a cross-belt magnet.

There is still a role for manual disassembly with automated separation in the electronics recycling industry. In the future, we will continue to disassemble the complex and more valuable products and send smaller, low-valued items to the high-volume shredders.

The author is CEO of Cascade Asset Management and can be contacted at (888) 222-8399.