Research & Innovation
The Recycling Challenge
By Pulp & Paper Canada
Minas Basin Pulp and Power Company Limited, located in Hantsport, NS, is proud of the fact that its entire output of recycled paperboard products is made from recycled fibre, reducing the load on the ...
By Pulp & Paper Canada
Minas Basin Pulp and Power Company Limited, located in Hantsport, NS, is proud of the fact that its entire output of recycled paperboard products is made from recycled fibre, reducing the load on the provinces landfill sites by 10.8 million cubic feet. But behind this accomplishment is a decade-long effort to learn how to remove contaminants from the recycled paper board furnish, or the OCCs it uses, and educate suppliers about what the paper mill can and cannot accept in the bales of OCC unloaded at its doors.
Who would guess that suppliers would sweep garbage into their bales of OCC, or toss in the odd engine block, or soak bales with water to up their weight, and the size of the payments due them? Yet in the 1990s, when the Nova Scotia government banned the dumping of OCC in provincial disposal sites, and when Minas Basin was rebuilding its pulp preparation area so it could process 100% recycled fibre, there was a bit of the “wild west” in the recycling culture. There was also a forgivable amount of ignorance on everyone’s part, the mill included, about what the requirements were for paper board furnish. “We didn’t know for a long time what we couldn’t use at the mill,” acknowledges Minas Basin Vice President of operations Terry Gerhardt.
The recycling industry has matured a lot since then, but it still takes constant vigilance on the part of Minas Basin and its sister company, Scotia Recycling, which supplies all of the paper mill’s OCC, to get a decently pure supply of OCC and then remove the inevitable contaminants before the pulp feed reaches the paper machine.
Minas Basin began adding recycled fibre to its groundwood fibre in the early 1950s. By the 1980s the mill was using 50% recycled materials, and gradually increased that to 100% between 1991 and 1995. Demand for OCC rose sharply after the company installed PM2, a 110 inch Fourdrinier in 1995, increasing production capacity from 30,000 to 100,000 tonnes a year. In 2002, the company shut down PM1 and upgraded PM2 Machine to produce 235 metric tonnes of linerboard a day. Today, annual production from the mill is 80,000 tonnes.
In 1995 Minas Basin installed a new pulp prep system — from new controls, equipment and building — that could handle 350 tonnes of OCC a day and clean and reject the contaminants. But completing the equipment list that would remove all of the contaminants took several more years. First, the company had to learn the hard way what would show up in the 1,000-pound bales of what was ostensibly OCC, then figure out how to remove the contaminants and otherwise feed small amounts of non-OCC paper products into pulp prep.
Minas Basin receives 100% of its OCC from Dartmouth-based Scotia Recycling. Established in 1986, it collects bales and delivers over 125,000 tonnes of secondary fibre a year. The greater percentage of its OCC comes from the retail sector, with the industrial and residential sectors providing less material.
Scotia Recycling has grown from having one bailing facility to 15. This has given it more control over the quality, since each bailing facility sorts the material that comes in. Some grocery stores have compactors, but others have bailers, which has the effect of reducing the control Scotia Recycling has over quality.
Identify and educate
In the tough early days, the reject rate from the mill neared 20%. A key strategy for improving OCC quality has been to educate suppliers, which include 35-40 small recyclers. “We go to national chains regularly to explain to them what can and can’t go into their bailers,” says Scotia Recycling President Dwight Whynot. Also, he adds, “The quality of the product has become better because of the Nova Scotia government’s efforts to educate people. The general education level has been brought up and [recyclers] are doing a better job than they were doing five to ten years ago.”
One Scotia Recycling strategy has been to break open bales, identify the suppliers and explain to them what it cannot receive. For example, suppliers are taught not to include hard pack, such as cereal boxes or newsprint with OCC; the mill can only use small amounts of it by gradually bleeding it into the OCC feed.
Glass and bottle caps have been a problem with beer boxes, and Scotia Recycling has worked with breweries to remove them from OCC. A lot of the Atlantic Canada suppliers are also scrap dealers and metal can get in the OCC if they do not clean their balers.
As for underhanded tricks, people used to purposefully put things in the bales, but, says Gerhardt, “We haven’t seen that for years. They know that we watch the bales very carefully.” Whynot adds, “Terry has a very good system in place in the mill to monitor quality. In the past we have cut off certain suppliers if they can’t bring the quality to an acceptable level.”
These efforts have gradually reduced the mill’s reject rate to a current 4.5 to 5% of the 85,000 tonnes a year of recycled material it receives. Still, people are obviously getting rid of material they do not want to deal with, like Styrofoam. There are also the obviously accidental inclusions such as loonies, toonies, new tool sets or brand new radios.
Some contaminants, especially syringes, pose risks to the mill and Scotia Recycling workers. Gerhardt recalls years when a lot of unused needles came into the mill, and twice this summer large quantities of used syringes arrived at one of the Scotia Recycling facilities. “We train our staff to deal with it. We have policies and procedures in place if we see syringes,” says Whynot.
Mill workers used to shovel rejects into boxes, but Minas Basin has taken steps throughout its history to reduce their risk of exposure to potentially dangerous rejects and improve efficiency by automating rejects processing. For example, the company installed a new scavenger in 1995 to collect contaminants. They are run through an Atara Drain screw conveyor, a 2003 upgrade to the Delta system for de-watering, then they are compacted and loaded into a bin. This de-watering has increased the reject material from 30 to 70% solids, reducing the cost of dumping water in the landfill, the final resting place of all of the contaminants removed from the OCC.
Changes in the marketplace have introduced new, unavoidable challenges. Big box stores used to receive a lot of merchandise in brown corrugated cardboard boxes, but they have become much more colourful as manufacturers angle to improve the visibility of their products.
“There is not a lot of equipment that will take out ink, so we have to mix it with brown OCC,” Gerhardt explains. “We don’t want to put [much] high-graphic OCC in because it lightens up our product. If we have a truckload come in with more pre-print than brown OCC, we will put it in a designated area of the warehouse, then mix in six or seven bales of OCC. We don’t try and separate each box, but we will try and mix the bales around with bales of brown boxes.”
A vexing long-term problem that still defies a complete solution is wax. “Wax boxes were a major issue for our mill five to seven years ago. We cannot deal with wax boxes. We were breaking open bales for months and months and measuring how much wax boxes there were,” Gerhardt recalls.
The mill’s technical and process manager Chad MacDonald explains the problems wax boxes create: “Wax does not break down to acceptable particle size. It is noticeable to the eye and usually stands out on our sheet. It may cause difficulties in printing graphics, and at the very least, it creates a poor appearance on the final box product.”
“It is difficult to educate everyone who uses wax boxes on how they affect our process. All it takes is a few bales of wax boxes to upset our system. Internally we have educated our people to watch for heavily contaminated bales, but it is not foolproof. From a process point of view, the quantity of wax varies, so it is difficult to create a piece of equipment that handles all wax concentrations and is still cost effective to run. It is diffi
cult to invest in equipment to remove wax when we are uncertain what the return will be.”
“Stickies” created from the adhesives used on the cardboard boxes are the most difficult contaminant, in MacDonald’s opinion. “Stickies build up on paper machines and cause operational issues and downtime for cleaning. We have developed programs to reduce the impact of stickies, but we continue to work on the problem. Due to their makeup, there is currently no equipment that removes them 100% from the system.”
The mill installed a Gyroclean in 1995 to remove wax and stickies from the liner, and another one in 1998 to remove wax and stickies from the filler. “This improved the appearance of our base ply and prevents wax from bleeding through to the top ply from the bottom during times of heavy contamination or when making light grades of paper. In 2002 we installed a Saturn Clarifier to handle the rejects from both Gyrocleans. This helped clean up our water system and helps prevent wax from returning to the system,” MacDonald explains.
Equipment and Maintenance
The gradual increase in demand for recycled fibre in paper mills in the years since Minas Basin went to 100% use of OCC, encouraged research and development by original equipment manufacturers. As a result, turnkey pulp prep systems are available, according to MacDonald. But at the time Minas Basin was rebuilding its pulp prep to handle 100 % recycled fibre, the equipment demands were not entirely understood. “Before, we didn’t have the knowledge that we needed to get a clean product,” says Gerhardt.
“The Minas Basin project team worked very closely with Fiberprep to modify designs, test new technology and efficiently combine new and old equipment. There was a lot of new technology that needed to be tested and modified to suit a 24/7 industrial environment,” says MacDonald.
There are 400 pieces of equipment in pulp prep, but a few examples of the pieces added in 1995 illustrate the effort required to remove contaminants: A Delta Pulper and Scavenger increases throughput, removes large contaminants and breaks down the OCC, while limiting damage to the fibres. Two Diabolos, one added in 1995 and the other in 1996, remove fibre at the last stages before rejects go to the landfill. An ADS Separator separates good clean fibre from coarse and fine contaminants. ELP Cleaners remove fine grit from the system and a CH10 removes contaminants such as Styrofoam. The Saturn Clarifier removes wax from reject water, resulting in cleaner process water and less water sent to the landfill. In many cases, the equipment that removes contaminants reduces damage to equipment further downstream.
The equipment has maximum contaminant removal rates, which, if exceeded, can cause contaminants to end up in the final product and affect quality. Overloading the equipment with contaminants can also cause plugging, which affects the flow the equipment needs to operate properly. When this happens they kick out and have to be taken offline for cleaning or repair. Overloading can cause premature wear, driving up maintenance costs and reduce equipment efficiency.
For example, the #1 Diabolo will kick out on overload when it gets plugged with too much plastic. If the CH10 becomes overloaded with Styrofoam, it will pass and appear in the final sheet. In addition, too much glass and metal cause premature wear in the High Density Cleaners and increase maintenance costs.
However, paying to truck and dump over 4,000 tonnes of rejects to the landfill every year is the least of Minas Basin’s worries. “If we can keep the quality of our raw product up, it reduces our maintenance costs. If the quality of the raw material is lower standard, it will hit us on maintenance and increase the frequency of maintenance work. If I don’t increase the frequency of maintenance and I let more contaminants go through, it affects the quality of our paper,” Gerhardt explains.
Gerhardt and Whynot are mindful of the fact that if they lean too much on their suppliers, they could start exporting their recycled fibre to markets that do not have to make paper products to as high a standard as North American customers require. “We really don’t have that problem in Atlantic Canada, but the global marketplace is changing. This is something in our industry that we need to be aware of,” says Whynot.
While the supply chain strives to provide clean OCC and Minas Basin works toward its goal of becoming a “green” mill, MacDonald meditates on picture-perfect OCC feed: “Contaminant free OCC would simplify the process and greatly reduce the cost of operations. You would only require a pulper and your product would be ready for refining, then the machine. No equipment, no controls, no management and no energy.”
Carroll McCormick is a professional writer living in the Montreal area.