The “Dream” Recycling Plant
”Resources in -- resources out” principle drives upgrade at Emterra’s Winnipeg MRF
by Barbara McConnell
Ask anyone what important leaps in technology have occurred in the last decade and few would point to material recovery facility (MRF) conveyor belts, star screens and optical sorters as life changing. But to a handful of Canadians who keep millions of tonnes of recyclables out of landfill, that’s exactly what they are.
To Emmie Leung, founder and CEO of Emterra Group -- which owns 14 MRFs across Canada -- the Holy Grail of MRF design is finding the right mix between automation and manual sorting to deliver the best possible end-product quality at the lowest cost.
“When referring to our MRFs, the idiom ‘garbage in-garbage out’ is antithetical to our business goals. Our mantra is ‘resources in -- resources out,'" she says. “As a private sector company, we look for ways to tease out more quality products from our processes without adding cost.”
Her attention has recently been focused on the company’s single-stream MRF in Winnipeg, Manitoba.
Commissioned in 2003 to process 45,000 tonnes of recyclables, its original mechanical bones were state-of-the-art Bollegraaf equipment.
Leung is upgrading the MRF now to a capacity of 100,000 tonnes because the City of Winnipeg is converting its recycling program, which serves about 190,000 households, from a manual blue box system to a cart-based, automated system that will substantially increase the amount of materials captured for recycling. The facility will also process recyclables from the industrial, commercial and institutional (IC&I) sector.
According to Leung, the original Bollegraaf equipment still operates efficiently, so it makes sense to retrofit the plant with modern Bollegraaf and TITECH technology.
Don Holliday, representing Van Dyk Recycling Solutions (the distributor for Bollegraaf and TITECH optical sorting equipment in North America), had helped Leung design and execute the original plant, and is back on the job.
“Our challenge now is to create a state-of-the-art MRF with additional capacity... on an existing 10-year-old frame,” Holliday says.
“This is a classic situation in today’s MRF world,” he adds. “After a decade of processing recyclables, many MRFS are ready for upgrades, not only because of basic wear and tear but also because the technology has evolved so far so fast.”
Leung and Holliday isolated four areas for upgrades: installing a Bollegraaf drum feeder (to provide a consistent flow of material to the in-feed belts); upgrading the star screens (for improved material separation); repositioning the existing eddy current for aluminum and adding a second machine; and, topping off the new system with two near-infrared spectroscopy (NIR) optical sorters.
“Emmie focuses on simplicity of design in a small footprint,” Holliday says. “A huge challenge we faced in designing the retrofit was integrating new equipment into the nice, tight, original design.”
Holliday adds that he enjoys working with Leung because she has a “good grasp of the breakdown of materials, what goes with what, and how the mechanical separation aids overall performance.”
He credits her as the architect of many of the new design features, including the idea of moving the tipping floor into a new, nearby building, thus creating more room for large trucks to manoeuvre and offload. The extra tipping floor space also allows for greater flexibility in managing contingencies such as equipment breakdown.
Van Dyk is installing a Bollegraaf Drum Feeder at the tipping floor. Unlike traditional metering drums that pull materials under them, the Bollegraaf system drives material over the top of the drum, eliminating what in industry vernacular is called “black belt” (meaning the belt is empty).
The Drum Feeder resembles a 40-yard container with a conveyor belt in the bottom and a five-foot diameter drum at one end. A frontend loader fills the container. The conveyor belt inside feeds a regulated, controllable amount of material against the rotating drum. The drum drives materials over the top while it de-clumps and tears bags, ensuring a constant load on the belt leading to the first pre-sort. This will permit Emterra’s frontend loader to do other things for about 20 minutes before the next load is needed.
As long as the container has material in it, the conveyor belt is never empty.
“In a 20-tonne per hour system, if the loader gets busy elsewhere and isn’t feeding materials from the tipping floor, productivity drops to zero,” Holliday says, adding, “Historically, that’s a minimum of 15 to 20 per cent productivity loss."
Another area that can significantly impact plant productivity is the paper/container separator screens. Holliday says that ineffective screens can reduce plant performance by over 30 per cent.
When screens are overloaded or set at a low angle, they function like a conveyor. The capability of the screens to separate paper from containers dictates the number of manual sorters required to quality control the mechanically-separated materials to meet market requirements.
Leung points out that marketing a #8 old newspaper (ONP) grade verses a #6 grade can result in about a $25/tonne difference. Since ONP #8 is about 50 per cent of the material stream, that equates to a $250 an hour difference when running a 20 tonne per hour system. Leung wants high speed for productivity and effective separation for quality.
“Stars” that achieve higher angles are the stars of this show.
Like other MRFs, Winnipeg employs screens studded with star-shaped, circular disks to facilitate material separation by size. The angle of the star deck, spacing of the stars and rotation speed of the star-shafts determine how efficiently containers and other small objects drop to a lower conveyor, while larger items (cardboard, boxboard and paper) are driven over the top of the screen.
The greater the star deck angle, the better the mechanical separation of the system. Inefficient angles allow container contamination in the paper stream and paper in the container stream. Contamination in either stream requires manual quality-control sorting and adds labour costs.
“Losing containers in the paper stream kills you, particularly when they’re high-value aluminum, PET and HDPE,” Holliday says. “You’re losing your highest value commodities in your lowest value commodity!”
Leung is upgrading Winnipeg’s screens to use Lubo “StarScreen” stars.
Lubo is the originator of Starscreen technology. Holliday says that Lubo stars lead the industry in performance. While some screens achieve a maximum angle of 38 to 40 degrees, the Lubo design allows the stars to operate from 38 to 48 degrees (the highest in the industry), which increases separation quality and throughput.
“Replacement stars are a hugely expense,” Leung says, “but that’s offset by the cost associated with decreased productivity and revenues, and increased labour costs. And if we have to add another one-third shift to process leftover materials, then there’s added labour and overhead.
“The economies of scale come into sharp focus.”
Holliday says the upgrade to the latest Lubo star designs and setting the optimum angles and shaft speeds will make Winnipeg’s original Starscreens operate as if they were new, increasing container capture by about 15 per cent.
Eddy current & optical sorters
Winnipeg is currently operating a two-fraction container screen. This is being converted to a three-fraction screen: “overs”, “unders” and “throughs.” (The throughs are the two -inch minus mix that will be dealt with separately.)
The unders are three-dimensional containers with some fibre mixed in -- typically three-dimensional paper such as rolled cereal boxes and telephone books. The “3D” containers will pass under a Bakker Magnet to capture ferrous, and over a large, newly-positioned Bakker eddy current to get aluminum out before the line moves on to a new TITECH NIR optical sorter (set to take off the paper). Taking aluminum early is important because the aluminum reflection signature in the NIR is very similar to paper, which can lead to contamination and lost aluminum value.
Holliday says TITECH is the only optical sorter that can sort paper and, further, that it’s now capable of sorting groundwood-based paper; “A real advancement in NIR technology,” he says.
The second optical sorter removes PET from mixed containers and sends it to manual quality control where non-PET and clamshells are separated from bottle PET. Holliday says using an optical sorter to remove high-value PET ensures there’s little of it left in the mix. (He claims TITECH guarantees a capture and purity rate of over 90 per cent.)
Randy Park, Winnipeg’s supervisor of waste diversion, is encouraged by the planned upgrade of Emterra’s MRF.
“The City of Winnipeg is optimistic that the MRF upgrade will in- crease the quality and quantity of the sellable products while increasing its goal of 50 per cent diversion by 2020,” he says.
The MRF re-design also considered how to save energy; for example, horsepower-hungry pneumatic transport systems have been deleted. Leung and Holliday worked closely with Van Dyk installers to minimize downtime in the current production. Commissioning is expected before the end of the year.
Editor’s note: Emterra Environmental is one of three Emterra Group family companies. The others are Emterra Tire Recycling and Canadian Liquids Processors Limited. Their website is www.emterra.ca
Barbara McConnell, APR, is Principal of McConnell Weaver Strategic Communication in Milford, Ontario. Contact Barbara at firstname.lastname@example.org