Solid Waste & Recycling

Feature

45 Degrees of Separation

In 2002 Winnipeg, Manitoba (population 675,000) went out for bid for a single stream contract covering design, build and operate, including collection. This contract was won by International Paper Ind...


In 2002 Winnipeg, Manitoba (population 675,000) went out for bid for a single stream contract covering design, build and operate, including collection. This contract was won by International Paper Industries (IPI) headquartered in North Vancouver, B.C. Van Dyk Baler Corp. competed and won this opportunity to build not only its first single stream system in Canada but also IPI’s first single stream plant.

This single stream contract replaced an existing blue box contract for “four sort at the curb” collection (fibre, OCC, containers and glass). The 2002 tonnage came in at 28,500 tonnes. Previously the process was laborious (sorting of fibre and containers required two shifts). Current collection still uses blue boxes and tracks at roughly 10 per cent above the 2002 tonnage (and growing). With the new contract, 3-6 plastics were added to the single stream collection. The decision to go with single stream was intended to motivate the citizens to a higher level of participation and to streamline the MRF process.

With the new contract the mixed broken glass is used at the city landfill as road base and ground cover. The 4 per cent residue is sent to landfill at a cost of $22.50/tonne. The single stream collection is operating using six fewer trucks than the previous collection method.

The system

Van Dyk Baler Corp worked with Bollegraaf and with IPI’s input to design a single stream system incorporating Lubo Starscreens. This design was based on Van Dyk’s experience of over 35 single stream facilities operating in the USA (the first installation was in 1995).

The incoming volume is dumped on the tip floor. The concept is to remove all the large OCC by first using the Lubo OCC Starscreen(tm). A pre-sort ahead of the OCC screen removes any large pails and obvious garbage. After the OCC screen there’s a second pre-sort where any small OCC, telephone books and garbage is manually removed.

The materials continue to the Lubo Double Deck ONP Starscreen. Here over 95 per cent of the ONP is removed mechanically. The angle of both screens is hydraulically adjustable, which influences the level of separation. The top deck incline is adjustable from 38 to 45 and the bottom deck incline adjusts from 35 to 45. Three speed control zones on each deck increase the operator’s ability to control separation. This screen is equipped with a patented Quick Disconnect axle removal system. (It takes only two minutes to remove a complete axle with all the stars, and the axle can be removed from the top or from under the screen deck.)

Says Van Dyk’s Don Holliday, “These screens have proven to be a very efficient ONP separator, consistently producing a # 8 ONP grade requiring very few quality-control sorters.

“The 22 square meters of screening surface on this double deck ONP Starscreen is unequalled. We challenge any competitor to achieve the 1.1 to 1.8 tonnes/hour/sorter ratio we have in all our single stream installations where a # 8 grade ONP is produced.”

The remaining fibre and containers go to the Lubo French Banana Starscreen(tm) where a separation of fibres (two dimension) and containers (three dimension) occurs. The angle of the screen is again hydraulically adjustable from 41 to 48, which influences the level of separation, as do four speed-control zones on the deck. All the fibre from the double deck ONP and the Banana screens passes over three quality-control sorting conveyors minimally staffed with sorters to remove any contaminants prior to storage and baling. The separated containers first pass under a Bakker Magnet and then through a Lubo Glass Breaker screen before finally going for manual sorting and then over a Bakker Eddy Current. On this container sorting line the customer added a pneumatic transport system to blow all sorted containers onto large hoppers above the baler feed conveyor.

Results

Actual collected tonnages are up over projections. The system has consistently produced a # 8 ONP that has experienced no rejections at the mill. Staffing levels are falling while throughput is increasing. The tonnes/hour/ sorter ratio currently sits at 1.3 tonnes per sorter per hour for the paper. Overall this single stream system runs on one shift at about 20 tonnes per hour and utilizes 20 staff (including loading, baling and shipping).

Says Holliday, “Realistically, I believe this system will settle down to a consistent average throughput of over 20 tonnes per hour with a staff of around 18 for residential processing. I project that the sorter ratio will reach 1.6 tonnes per hour per sorter for fibre.”

In addition, says Holliday, the company has designed process flexibility to allow for changes to the incoming mix of materials which it anticipates will allow this system to fulfill its 14-year contract.

Guy Crittenden is editor of this magazine.


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