Straw to Board

A new $45 million plant in Alberta is using a combination of straw and state-of-the-art equipment to manufacture composite board. From Straw to Board Local farmer and AgraFibre Industries straw buyer Mills Anderson, above, is very familiar with the characteristics of straw. “It doesn’t break down and it doesn’t cut easily. It’s a tough material which contributes to the strength of the board.”	1. Straw bales arrive in the yard on a just-in-time basis and are loaded onto a chain infeed conveyor. 2. Passing through a Morbark high speed tub grinder, the straw is chopped into six-inch lengths

3. After separation, the dust is conveyed to the energy room, which features a Konus thermal oil energy system that generates enough heat for the plant and the press.	4. Freshly manufactured composite board is loaded on to a rotating mechanism that sets the boards upright to cool.

Local farmer and straw buyer for AgraFibre Industries, Mills Anderson, seeds a percentage of his acreage in fescue and is very familiar with itscharacteristics. “If you went out with your tractor to disk down wheat straw, one pass and the wheat straw would disappear,” says Anderson. “With fescue, 10 diskings later and you’d still see some straw. It doesn’t break down and it doesn’t cut up easily. It’s a tough material which contributes to the strength of the board.” About 100,000 acres of fescue are grown in the Peace Country each year, represent-ing 98 per cent of the fescue grown in Canada. Fescue is lawn seed and, by a unique combination of weather, soil, and a long spring growing season, the Peace Country is one of the few regions in Canada where the plant will produce seed. As an extremely resilient perennial crop, farmers have either burned the straw by-product or given straw bales away to cattlemen. “If the straw is left in the field, it will totally inhib-it the seed crop that is coming on next year,” says Anderson. “So fescue farmers want to take that straw off.” Depending on distance, AgraFibre Industries pays between $21 and $25 per tonne for straw bales located within a 200- kilometre radius of Wanham, and the com-pany absorbs transportation costs by pick-ing up the straw in the farmer’s yard. So far, it has about 600 farmers on its data-base, with most having agreed to provide some straw to the plant. While a number of strawboard plants have been built recently in North America, company executive vice-president and founder Wes Anderson says there is no such thing yet as a “tried and true” method to produce composite board using straw as the raw material. He says the driving force behind using cereal and grass straws began with technology developed by those using sugar cane straw as a feedstock. The decision to produce composite board consisting of a fescue, timothy, and wheat straw mixture had more to do with market availability than actual board strength. Depending on such conditions as weather and market demand for fescue lawn seed, the amount of land planted in the Peace Country can vary from 70,000 to 150,000 acres. Rather than reacting to changes in market availability of the raw material, Wes Anderson says the company decided to stick with an 80/20 mix in order to avoid confu-sion among their customers. At present, AgraFibre Industries has an agreement to deliver 100 per cent of its prod-uct to furniture and cabinet manufacturer Sauder Industries. The composite board is delivered by truck to furniture manufactur-ing plants in Calgary and Vancouver. The major engineering challenge com-pany planners encountered while designing their production line was in fiberizing the straw. “We are trying to open up the fibre from what is similar to a drink-ing straw and laying it flat without pulverizing it into a powder,” says Wes Anderson. “You don’t want to glue a bunch of drinking straws together because there is no strength in that.” They have overcome this challenge with a German-made Pallmann fiberizer, but he believes that even better fiberizing solutions will soon arrive on the market. Straw bales arrive in the yard on a just-in-time basis, eliminating the need for a large storage area. Mills Anderson says they can produce composite board from fescue bales that have been sitting in the farmers’ yard for three to four years. ACaterpillar telehandler loads each bale onto a chain in-feed conveyor. Once inside, the straw is chopped into six-inch lengths by passing through a high-speed Morbark tub grinder, originally designed for clean up of wood fibre in mill yards. Then the straw is blown pneumatically into a series of Raute Wood live bottom bins. In the first one, the three straw vari-eties are homogenized through a series of rotating shafts. Then a Pallmann hammer-mill chops the straw into inch and a half lengths before another live bottom bin blends it a second time. The Pallmann fiberizer chops the straw to lengths less than three-eighths of an inch. Then it is blown into a large, German-made Ponndorf hot oil dryer, which takes the straw down to a four to five per cent moisture level to allow for proper application of the resin.

The material then proceeds to a German-made Allgier screen, which separates the fibre by length. The dust is conveyed to the energy room, featuring a German Konus thermal oil energy system, and generates enough heat for the plant and the press. Meanwhile, the millimetre size straw that will eventually form the board’s surface material is separated out, as is the larger material up to three-eighths of an inch long. A small percentage is sent back through a cutting device to reduce it to acceptable size. The millimetre size and the three-eighths of an inch size each flow toward the form-ing line into separate Coil glue blenders, manufactured in Vancouver. The glue resin, methylene diphenyl isocyanate (MDI), is a chemical designed to be strong enough to bond the straw fibre without sticking to the press. “Urea formaldehyde didn’t work as effec-tively on straw, so there had to be a designed chemical for that purpose,” explains Mills Anderson. “One of the great advantages of MDI is that after it is heated and pressed in the board, it is an inert substance. There are no emissions of any kind.” The composite board is formed on a series of alloy plates, called cauls, that move in a continuous circular pattern along the pro-duction line. The surface and the core mate-rial are introduced at opposite sides at strate-gic points along the continuous-flow form-ing line, creating a sandwich of material that will vary in thickness depending on the size of composite board being produced. The plant can manufacture board between one quarter and one and a quarter inch thick. The forming head equipment is made in Sweden by Daproma Systems. In order to reduce press time on its main press, AgraFibre Industries uses a Norwegian-made Fjellman pre-press that reduces the size of the sandwiched materi-al from about one foot to four inches thick. Seven cauls loaded with pre-press material are fed into a magazine arrangement and then into the main Fjellman press. It exerts a force of 3,200 tonnes and heats the mate-rial through the use of hot oil between 160 and 180 degrees Celsius. Once the press cycle time is completed, the boards are loaded onto a rotating mech-anism that sits them upright on edge to cool. After curing for two days, they are taken to the finishing and sanding line where they are sawn and sanded using Daproma Systems saws and a Swiss-made Steinneman sander. They are then cut into the required sizes and stored indoors while awaiting delivery. This past summer, the plant was in the final stages of debugging its production line. At full production, press cycle time should take nine minutes. Six weeks into start up, it had already been reduced to only 12 minutes, a point that takes some plants a year to achieve. In operation 24 hours a day, seven days a week, the plant has one production line with a second one to be installed later this year. When in full production, the plant will employ 60 workers, a welcome additional source of employment in this largely rural area. With more than 90 per cent of area farmers working off the farm to earn a steady income, the plant’s work rotation of four days on and four days off suits many who still maintain a farming operation. Mills Anderson says the potential defi-nitely exists for the addition of a value-added facility, such as a furniture manufacturing plant or mobile home manufacturing plant, right on the site. However, at present, man-agement is focused entirely on throttling up the plant to full production.