Updating your backend waste stream equipment?

Jun 13, 2023

Chip processing equipment modifies metal scrap to create smaller, flowable chips and reduce overall volume. Images: Shutterstock

Metalworking companies that are thinking about updating their metal scrap processing equipment have a lot to consider, especially with how frequently production takes priority over waste management.

With that in mind, here are answers to three frequently asked questions that can help these operations identify options that will bring the most value:

Q: Metal turnings shredders, horizontal- and vertical-axis crushers, bundle breakers, rolling ring crushers, and hammer mills all seem to achieve the same basic output: They modify metal scrap to create smaller, flowable chips and reduce overall volume. So, what are the unique benefits and limitations of these individual components?

A: Let's tackle this in two groups.

In the first group, we have shredders, horizontal-axis crushers, and bundle breakers, which have one thing in common: they modify low-volume quantities of metal turnings to create flowable chips that are ready for additional downstream processing.

And while all of these systems achieve the same outcome, they each do it differently. Shredders shear the material, bundle breakers tear the material apart, and horizontal-axis crushers rip and grind the material until flowable chips are produced. This reduction is necessary not only to protect the downstream equipment during further processing, but also to promote consistent and efficient results.

Bundle breakers modify bushy wads of metal scrap so that augers and steel belt conveyors can successfully transfer material that would otherwise bounce around an in-feed hopper. Shredders and horizontal-axis crushers, on the other hand, need the metal scrap to be semi-flowable for augers and conveyors to consistently feed the material into the system for modification. The trade-off is that shredders and horizontal-axis crushers provide continuous volume reduction right at the source (though they can also be utilized as free-standing units).

Bundle breakers also break free solid parts and bar ends that may be trapped in the bundle. Shredders and horizontal-axis crushers alone are not recommended for processing material containing solids, such as bar ends and parts pieces.

Shredders, horizontal-axis crushers, and bundle breakers typically operate at low speeds with high torque—their drives usually only need to be 2 to 10 HP. This can help keep energy costs down.

The second group of metal scrap modification systems includes vertical-axis crushers, rolling ring crushers, and hammer mills, which provide heavy-duty processing compared to the components in the first group.

Chip centrifuges and briquetters can be used in the downstream recovery of metalworking fluids from scrap.

Each of these units offer continuous, positive-feed operation, which enables them to process high volumes of metal scrap that are too large for conveyors. The end result of these units is flowable, thumbnail-sized metal chips, and in some instances, fine powders.

In contrast, shredders, horizontal-axis crushers, and bundle breakers produce chips in the range of 2 to 6 in.

These high-volume systems are lower in torque but operate at higher speeds. Vertical-axis crusher motors are usually around 20 HP, while motors for rolling ring crushers need to be upwards of 50 HP. Of these heavy-duty units, vertical-axis crushers are on the lower end of the throughput spectrum—although, if floor space allows, multiple units can be installed to process higher volumes. Rolling ring crushers and hammer mills are both capable of processing high volumes of material.

Regardless of whether you need a light-duty or heavy-duty metal scrap processing system, both levels of volume reduction will help decrease storage needs, lower costs for transporting metal scrap, and maximize value from a recycler.

Q: What are some considerations when it comes to updating equipment to recover cutting fluids from metal scrap?

A: Two advanced systems can be used in the downstream recovery of metalworking fluids from scrap. They are chip centrifuges (also known as chip wringers) and briquetters.

Chip centrifuges dry chips by using centrifugal force to spin cutting fluids off the metal scrap. They can be used as stand-alone units or incorporated into a chip processing system and typically reclaim the highest percentage of fluid.

Briquetters compress the metal scrap into pucks and squeeze out the cutting fluid, producing the densest form of metal scrap that recyclers value. Just because pucks sometimes command higher prices from recyclers, that doesn't automatically mean a briquetter is the right option for your operation. Other questions to ask when deciding include:

If a manufacturer's primary goal is reclaiming cutting fluids and lowering fluid replacement expenses, a wringer usually is the answer. But if the volume of scrap is high and transportation cost is an issue because it must be hauled over longer distances, then minimizing the size of the material through briquetting maximizes value.

Aluminum pucks on average weigh about 125 lbs./cu. ft. (depending on the briquetter manufacturer, unit model, the size of the briquette produced, and the density of material before briquetting). Nevertheless, pucks are nearly 10 times more dense than loose chips, and they enable shops to optimize container space and, therefore, save on storage.

When it comes to chip centrifuges/wringers, three main styles exist:

It should be noted that in models with a top-loading orientation, it sometimes can be difficult to evacuate all the material from the system after operation. This can lead to spent fluid and small metal fines that wear seals out prematurely.

Q: What should shops consider to get the most value from chip processing equipment and optimize ROI?

A: Securing the capital for waste stream processing equipment can be a real hurdle, especially for a complete chip processing system. Naturally, stand-alone components (such as a shredder, crusher, and centrifuge) are less expensive than systems that integrate those components into an end-to-end chip processing system. But in the long run, integrated systems offer several benefits.

They maximize efficiency through automated, continuous processing with higher throughput, which usually translates to a faster ROI.

Even though an individual component takes up less space than a complete system, when you add up the combined floor space that individual components require (including space sacrificed to create safe areas/pathways around the equipment), an integrated system likely takes up less space comparatively.

Compact, turnkey skidded systems can be moved from one location to another to provide tremendous flexibility when plant space needs to be reconfigured to meet new production goals.

Finally, knowing exactly what material the equipment will be running is the key to a durable installation. Simulating processing goals by having your material test-run through the equipment being considered is the best way to validate its capabilities. Whether the test is conducted in-person or remotely, it will provide valuable insight into its effectiveness in your specific application.

Mike Hook is director of sales and marketing at PRAB, 5801 East N. Ave., Kalamazoo, Mich. 49048, 877-558-9834, www.prab.com.