January/February 1995
This design firm applies advanced technology to knotty material separation problems. It has successfully used equipment originally developed for concentrating minerals to squeeze value out of wire chopper tailings and is moving into other recycling areas with the help of new technologies.
By Jeff Borsecnik
Jeff Borsecnik is an associate editor of Scrap Processing and Recycling.
The demonstration begins.
Finely chopped mixed metal and plastic particles drop from a small chute onto a brightly lit, slowly rotating stainless steel drum, which conveys the material beneath a high-voltage electrode. Bits of metal in the mix are imparted with a charge, lifted away from the drum, and deposited on the near side of a splitter plate and down into a collection bin. Meanwhile, the residual strongly charged plastic particles' stick briefly to the drum and fall on the other side of the splitter and into a separate bin.
This electrostatic separator, humming quietly away in a clean bright-orange metal and glass cabinet in an orderly laboratory at Carpco Inc. (Jacksonville, Fla.), is just one small-scale example of the material separation systems Carpco has developed for a range of industrial applications, including equipment designed to pull residual metal from wire chopper tailings or metal contaminants from ground plastic bottles at scrap recycling operations.
Indeed, according to company President Frank S. Knoll, Carpco's lab and pilot-scale plant make up the world's largest testing facility for separation equipment of the sort the firm produces—those that rely on high voltage (electrostatic), magnetic forces, and gravity to do the discriminating. The pilot plant takes up about 15,000 square feet of space—half as much as Carpco's whole manufacturing operation—attesting to its importance to the company's business. The testing facility, in fact, is the backbone behind Carpco's specialty—solving industrial process separation problems in novel ways. The company invites potential customers in various industries around the world to send to its lab samples of commingled materials, generally no larger than a half-inch and possibly as small as bits of dust. The object: to design systems and methods to either segregate the materials into various useful components—say similar minerals headed for different uses—or to remove troubling contaminants so the rest can either be made into new products or disposed of safely and cheaply.
The mixed flow of samples presents a unique opportunity to try different techniques on a wide range of materials and gain in insight into their response to physical processing techniques that would otherwise be difficult to predict," Knoll explains. "And from that base of experience we're able to solve problems that are typically difficult. We see lots of things, try lots of things."
Separating Sands, Then Metal and Plastic
J. Hall "Carp" Carpenter began Carpco out of his basement in 1951 after purchasing the rights to a patented process he had developed for his employer, National Lead Co., to electrostatically separate titanium minerals mined as sand in Florida. These minerals, titanium oxides which might appear as black streaks in beach sand, are used in a variety of products, including paint pigments and aircraft parts.
Carpenter's new company also used and refined complementary techniques for processing mining products based on gravity and magnetism, which led it to expand into separation of silica sands for glassmaking. The next industry it tackled was the Canadian iron ore industry, where Carpco equipment is still used to separate finely ground iron ore particles from silica.
Carpco's move into the recycling business began in the 1970s, when the company realized that electrostatic separation, which depends on a large surface area-to-mass ratio and differences in conductivity of similarly sized particles, would easily separate mixed chopped plastics from nonmagnetic metals. The process was a natural for treating wire chopper tailings, the company's executives figured, and the recyclers they proposed the idea to were eager to cut their losses of valuable copper and aluminum fines not separated from plastic insulators by traditional air separation equipment in wire chopping systems. Since then, two factors have boosted the utility of this application—increasing concern over disposal of wire insulation that is contaminated with metals and development of markets for this recovered polyethylene and polyvinyl chloride, which demand a very clean stream of plastic.
Finding new applications for its already perfected technology has remained a strong suit for Carpco. Versions of its electrostatic separators, for instance, are now used to pull aluminum caps and other fragments from chopped scrap polyethylene terephthalate soft drink bottles, recover precious metals from chopped electronic scrap and refinery slag, separate quartz and limestone, and pull contaminants like bits of fiber or metal from food product streams such as spices, nuts, and seeds.
Working in many different industries has its benefits, says Robert M. Carver, sales engineer in charge of recycling applications. "We can take knowledge from iron ore or titanium minerals or recycling to another area," he says. "That's how we do our problem solving." As an example, he points out that the company has incorporated hydraulic classifiers into most of its separation systems, building on the advantages the classifiers exhibited when Carpco first included them in separators designed for silica sand.
Supporting Research and Development
The key to Carpco's ability to serve such a range of customers—in fact, the key to the small, 50-employee company's ability to compete in its chosen niche, Knoll believes—lies in keeping on the cutting edge of technology. And that means an unswerving emphasis on research and development efforts, such as those its extensive lab and pilot plant enable.
Because of this, Carpco focuses its resources on design engineering. Though the company operates a core manufacturing facility to support its research and development work and fabricate prototype products, it contracts out most regular manufacturing chores like metal fabrication and fiberglass and urethane forming "to people who do manufacturing for a living," explains Knoll.
As a related strategy for staying connected to new technology developments, Carpco frequently works in tandem on separation problems with various universities, including the University of Florida Georgia Tech , Virginia Polytech, and Southern Illinois University. In addition, the firm has joined forces with the High Fields Magnetic Lab, the Bureau of Mines, the Department of Energy, and other government agencies on research projects that have called on Carpco to serve a variety of roles, from providing equipment to performing research-related contracts.
With the expertise this research and development focus provides, Carpco is able to sell its technical services, not only as related to the separation systems it designs, but also independent of equipment sales. For instance, the firm's technical service group performs testing for clients, such as making detailed microscopic analyses of samples (which can range in size "from 100 grams to 1,000 tons," according to the company), producing separation feasibility studies, evaluating customers' separation systems or material problems, and setting up pilot plants for clients.
Such services help support the lab and pilot plant, which then translates back to solving separation problems. Carpco's lab provides an unparalleled resource within the company, says Julie Holloway, the company's customer service manager. "Without the lab, we wouldn't be as successful. They've seen everything," she says. "I can go to them any time I'm in a bind and get an answer."
A Mixed Bag of Tricks
In addition to its electrostatic separators, Carpco produces other types of separation systems, which, like the electrostatic variety, are available on three different scales—for lab use, pilot plants, and production facilities. These products include:
- electro-pneumatic aluminum concentrators, which detect metal particles in a flowing stream of plastic pellets or flakes and eject them with a directed blast of air;
- rare earth drum magnets for separating semimagnetic minerals;
- Humphreys sliding board-like spirals for gravity-centrifugal concentration of mineral particles;
- Floatex hindered settling systems, which classify particles by size and density;
- Mozley hydrocyclones for centrifugal separation of fine particles in water; and
- Wilfley (USA) wet concentrating tables, which separate light particles from heavy ones by bouncing them in a stream of water over riffles.
(Carpco owns the Humphreys Equipment name, having bought that Denver-based company and its Wilfley (USA) table line during the 1980s, while the Floatex and Mozley brand names are built or sold under license from foreign manufacturers. On the flip side, Carpco also licenses companies to produce its separation equipment in various foreign markets, including Australia, Brazil, Malaysia, and South Africa, through business relationships that sprang from earlier services Carpco provided customers in these countries.)
These products add to Carpco's varied bag of tricks in solving complicated separation problems, which more often than not require use of several different types of separation technologies in a series. For example, mining of mineral sands might begin with inexpensive gravity separation to remove the bulk of the unwanted material. Electrostatic equipment would be used next, followed by a final, exacting magnetic separation step.
Similarly, the company also sells a broad range of laboratory tools for use in conjunction with its equipment. "The lab products we sell are for preparation of material so our machines can do a good job," explains Holloway, who oversees laboratory equipment sales in addition to customer service.
There are more than 100 of these lab products, including feed preparation and sampling equipment, such as a sort of collection pitcher with a long narrow sampling spout able to take an accurate cross section sample from a flowing stream; classification (sizing) equipment; measurement tools; magnetic particle and field detectors; a magnetic fluid separator; elemental analyzers; and sample splitters, which ensure that portions of larger samples selected for analysis are truly representative. These tools serve an extremely broad market including education and research facilities and companies in just about any bulk material industry from pharmaceuticals to food processing.
Put these lab equipment sales (which provide Carpco with a flow of revenue much steadier than that generated by its large-scale separation systems) together with the various separation products and engineering services it provides, and it seems clear that Carpco's small size belies its true prominence. And indeed, while Knoll won't discuss the company's actual revenues, he does note that its sales have been growing at a 20-plus-percent clip in the last few years.
About half of this business comes from abroad, including orders from mining-related plants in many far-flung comers of the globe. To cope with this, the company's staff is quite a mixed lot, not only in terms of technical expertise, but also nationality. "We have people from all over the world-South Africa, England, Malaysia, India," says Carver. This mix is necessitated by the "location of the opportunities," says Knoll. "We must have international staff who can deal with a variety of countries because each has its idiosyncrasies in the ways it does business, and we find that people coming from these regions have better insight into what's required to do business best."
The Next Wave—Recycling Promises
Carpco's history has been a series of technological advances followed by broadening application and fine-tuning of the equipment developed as a result. And the company always has new projects in the works. The 1980s, for example, saw it move into wet separation systems for the first time, concentrating on advances in spiral gravity concentrators following the purchase of Humphreys.
The 1990s are ushering in another new era for Carpco, namely the use of superconducting magnets to separate extremely fine particles that are only faintly magnetic. (Magnetic attraction is related to mass, so magnetic separation of very tiny particles requires extremely strong magnets.) The main application for this technology is the kaolin industry, which mines clays and refines them, removing impurities like iron and titanium oxides, to create fillers and coatings such as the material that makes this magazine page glossy. In 1991, the company purchased a producer of superconducting magnets in London and turned it into Carpco SMS Ltd. (the acronym is short for superconducting magnet separation), a 12-employee subsidiary focusing on this technology.
And there are at least two new major recycling projects in the works.
In one, Carpco is teaming up with a German manufacturer on glass cullet sorting systems. The objectives are to first remove contaminants such as stones, ceramics, and metal bits from a stream of glass cullet and then to sort the cullet by color using lasers, a whole new realm of technology for Carpco, which is already very involved in the glass industry on the sand side.
The other big item on Carpco’s project list is a process it has designed to recover plastics and metals from old wire and cable chopper tailings stored in landfills or stockpiles. Because such tailings are likely to have absorbed moisture during underground or outside storage, and water throws off the conductivity characteristics needed for the electrostatic separation methods employed in the company’s existing wire chopper tailing separation systems, the new technology will aim at recovering pure metal and clean plastic streams from the mix using a chemical-free wet separation system.
The project, still under wraps as of this writing (while the company applies for a process patent), should open new doors for Carpco in recycling, making another inroad in its work to solve industrial separation problems.•
This design firm applies advanced technology to knotty material separation problems. It has successfully used equipment originally developed for concentrating minerals to squeeze value out of wire chopper tailings and is moving into other recycling areas with the help of new technologies.