Small pieces of glass once destined for the trash heap now are a major revenue source for Partners Recycling Services, a Baltimore recycling company that processes 1,400 tons per month (tpm).
In January 1999, the company installed five MSS Inc., Nashville, Tenn., glass sorting machines, which process glass fragments between 31/48 inch and 2 inches. The new MSS ColorSort System, which sorts mixed broken glass with light sensors that use infrared and other light frequencies, allows the company to process about 10 tons of glass per hour, approximately three times more than when the glass used to be sorted by two older sorting machines and by hand.
Glass, which is sold to bottle makers, has surpassed paper as the company's biggest revenue generator. And since it started using new sorters, the company has expanded its customer base by 50 percent.
"I think it's a pretty hot market for glass right now. We're able to offer a premium product, and the bottle makers are beginning to hear about us," says Partners Recycling's general manager Monty Davison. "Even if we were processing double the amount of glass, we wouldn't have any trouble selling it."
Partners, which opened in September 1997, has contracts to process paper and comingled recyclables for the city of Baltimore and the counties of Carroll, Howard and Harford in Maryland. In 1998, the company acquired about 40,000 tons of broken glass when it purchased Resource Recovery of Maryland, a glass processing company. Partners also collects glass recyclables from several regional materials recovery facilities (MRFs).
With its large glass inventory, the company needed a more efficient way to process glass, Davison says .
"[The new system] doubled our revenue overnight," Davison says. "It's extremely fast for processing mixed broken glass."
Glass, paper and comingled recyclables are processed at the company's Baltimore MRF/glass recycling plant, and paper is processed at the company's two MRFs, which process 110 tons per day (tpd) of paper. The Westminster, Md., MRF processes paper with a Marathon Equipment Co., Vernon, Ala., baler and the Elkridge, Md., facility uses a Logemann Brothers Co., Milwaukee, baler.
The glass sorters screen and meter the glass fragments, accepting only pieces between 31/48 inch and 2 inches in size. A vacuum system removes paper, plastic and other non-glass materials, and the machine's light sensor sorts the glass according to color.
At Partners, the machines sort green, brown and clear glass in a five-machine system. Two machines receive all three colors and are programmed to pick out brown pieces. The remaining green and clear glass is loaded onto two machines that pick out the green glass. Clear glass - also called flint - remains after the brown and green pieces are sorted. A fifth machine performs a quality check.
Before the new system, small glass fragments often were thrown out because it was too time-consuming to sort the materials by hand, Davison says.
"No glass mills want mixed [glass]. They all want it separated by color," Davison says. "The color sorters really are the only thing that turns these things back into glass bottles."
Davison says the MSS system also allows haulers to bring larger loads. Partners Recycling previously asked haulers to drop off bottles in one piece, but now, trucks can compact the bottles, which leaves room for more recyclables in the trucks.
"Before, bottles had to be treated with kid gloves," he says. "And with the collection of comingled recyclables, by the time it got to our system, we had to break the bottles anyway. Now we can say, 'go ahead and break the glass,' and they are able to take on double or triple the weight."
MRFs that provide the company glass also can reduce labor costs because they don't have to sort the glass, Davison says.
Partners Recycling sells its sorted glass to bottle makers in New Jersey and Pennsylvania, including Leone Industries, Bridgeton, N.J.
The company is considering expanding its operations now that it is able to process higher volumes of glass.
"I see us possibly putting up other facilities and expanding our reach from this facility to bring in more tonnage," Davison says. "One of the things we also are looking at is shipping overseas."
Davison says the company plans to purchase one more glass sorter soon to handle the increased flow of materials. He also expects the sorting machine technology to improve to the point where they can process glass even smaller than 31/48 inch.
"It's going to be interesting to watch it in the next couple years," he says. "With the new technology, you can see the acceptable size getting smaller."
However, MSS Inc.'s Josh Bickman says that technology might be many years away. "The edges of the glass fragments appear opaque to light sensors," he says. "That 'edge effect' makes it difficult for sensors to identify glass color as the pieces become smaller."
The Baltimore glass plant also processes ceramics. Two color sorting machines, manufactured by SEA, Bologna, Italy, remove ceramic-based glass - opaque glass used to make plates and coffee mugs - between 11/42 inch and 2 inches. Another MSS Inc. machine, the ELPAC System, sorts metal from the mixed glass stream before those materials are sent through the ColorSort machines.
Partners Recycling employs 75 workers, including 53 at the MRFs, 12 at the Baltimore glass plant and 10 managers. MSS Inc. manufactures automated sorting systems for glass, plastics, paper and metals.