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Sat, Apr 13, 2024 09:45
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Responses to Straw Pulp Knowledge

Lots and lots of stories about straw pulp last week...

>In 1963 CCA corrugated (board) mill (Circleville, OH) was using straw for making pulp. A year or two later, they converted to making pulp from local hardwoods. Today the mill is shut down. Straw had its problems, like some batches came in with excess water, so you wouldn't get your money's worth. Chuck Green

>The Chillicothe mill pulped straw with the soda process until WWII. It made a fine pulp with low chlorine demand in the bleach plant. However, the straw was harvested once per year and required under-roof storage. It was "on the books" when delivered to the mill vs trees that were not taxed as inventory until harvested 2 weeks before pulping. Straw contains silica and the industry developed and later forgot desilicating technology. If the farmer could store the straw year round it would significantly improve the straw pulp business model.

>I know so much about straw pulp that I do not know where to start. It can be and is used around the world for a wide range of pulp and paper products as well as molded products. The reason why the straw pulp mills in the US went out of business years ago was primarily related to the bale size - 80 lbs - so that they could be moved manually. Cost of labor made the cost of straw too high. This is not a problem any more with the 1500 - 2000 lb bales that can be moved mechanically and that can provide a full 44000 lb load weight on a truck. The main problem will be silica content of 3 - 8% which causes problems in the recovery island. But careful design can offset most of the problems. Also, new recovery technologies such as Siloxy and Electrosep would solve the silica issue. Is it going to be easy to do a large straw pulp mill? The answer is no, but then it's not easy to do a woodpulp mill these days.

>Close: I (Consolidated) was solicited many years ago to help finance a corn stover mill in Iowa. Didn't do it and it never got off the ground. George Mead

>Earlier this year, Kimberley Clark announced that they were researching bamboo and wheat straw as alternatives to wood for their pulp requirements. Maybe KC knows something you don't. Also, I believe that there are one or two recycled board mills in the Northwest that may be using high yield semichemical wheat straw as part of their furnish. Mark Lewis at the University of Washington was working with them. Bob Hurter

>Up into the 1950s, corrugating medium was made from straw pulp at a number of mills across the Midwest from Ohio to Kansas and including Michigan. Most of them subsequently converted to NSSC (Carthage, IN, Circleville, OH, etc.) and subsequently to waste paper before shutting down. Most of those mills had cylinder machines. One of the big problems was getting in a storing a year's worth of raw material in a few months. Queen City Paper Mills, Tipp City, OH bit the dust because their straw pile burned. I have had more recent experience with straw pulp - working on the 1993 start up of a machine in Xin-Yi, Jaingsu, China making sheet fed offset paper from a furnish that included 60% wheat straw pulp. I have also consulted over the past few years at mills in India than make paper from straw pulp along with other agro-fiber pulps. I found it interesting that this issue of Nip Impressions is published on the same day as the Kimberly-Clark news release saying that they are partnering in a venture to make tissue from bamboo to reduce use of trees from the forest.

>Surely an appropriate amount of valid, truth-seeking financial analysis will expose the fallacies in this pulping rebirth. Even "free" straw must be scarce between January and June in Manitoba, so maybe they'll only run part of the year and forgot to do the economic analysis for the whole year, or someone's being duped, as you imply. Dave Bennett

>I called on mills in Indiana some years back that were old straw mills. They all had big warehouses to keep straw from the previous harvest available to produce product. I also remember proposals early in the recycle boom for mills to use corn stover. No doubt it will work, but will it pay out. R G Bergstrom Neenah, WI

>We were approached by a group outside of Calgary in the late '90s about their effort with straw pulp, using the waste from all the wheat fields. We ran a trial that showed some promise. When we visited their small-scale operation and looked at the economics of their process, it quickly became obvious to us their real objective was to sell the chemical "by-product" and selling the fiber that resulted from the process was going to help pay the bills. They didn't put enough effort into the pulp quality issue and did not survive.

>Having worked in China in Shandong province I was always amazed at all the new papermill production in a province without trees but the history of the province is based upon straw pulp. There is still a straw pulp mill at the facility I was located at. It was neat to see the straw piles (looked like thatched roof buildings) and all the forms that the straw pulp was brought to the mill in. I also visited a facility in India now owned by my company that has tumbling straw digesters. That was a look at working history. I too found the comment of the "new" straw pulp sourcing for the mill interesting. The Chinese joint venture partner who now owns several million tons of paper and paperboard capacity started about 30 years ago with a 1 ton per day straw based paper machine.

>The first pulp mill built in South Africa was a straw based mill using technology developed by an Italian by the name of Umberto Pomilio. Pomilio and a colleague patented an electrolytic cell to produce chlorine (poison gas) which was being used as a weapon in trench warfare during World War 1. After the end of the war there was no market for the chlorine produced by Pomilio's plant in Naples, so Pomilio investigated other opportunities for using chlorine produced by his plant in Italy. He came across the soda pulping process, followed by chlorine bleaching. The first Sappi mill, Enterprise Straw was built using this technology. The history of this mill is comprehensively documented in the book, Paper Chain - The History of Sappi authored by Anyhony Hocking and published by Hollard South Africa (1987).

>To make a long story short, during the late 1990's annual ryegrass straw was pulped in a steam explosion system (Staketech) in the Weyco Springfield mill in a 50 TPD system. Annual ryegrass has low crude protein, unlike the perennical variety that is used for cattle feed. When a caustic pump failed, we learned that chemical was not needed and actually produced a better pulp. The strength was equivalent to OCC and box customer feedback was positive. Since no chemical was used, the "brown liquor" was evaporated to a syrup that was mixed with the fines from preparing the straw for pulping. This by-product when fed to chickens and cattle produced excellent weight gains in farm tests. At the prevailing and fluctuating price of chips and OCC, the the fiber cost at the head-box could be adjusted by turning the chip, OCC or straw usage knobs. Key to the project was Willamette grower and baler participation. They had been burned before by straw enthusiasts (bale houses and straw particle board, for example). They would soon no longer be allowed to burn the straw in the field due to smoke issues. The state of Oregon provided funds for development of the field to mill gate process development. Warehouse experience and economics were already established by the perennial ryegrass industry that sends high crude protein straw to Asia, primarily Japan. What do containers contain when they go back for more loads of electronics? Ryegrass feedstaw and christmas trees are the largest products in that market. It had all the ingredients for success. Envision a logo on the produce boxes for which most of the liner was made - "This box made from at least 20% recycled agricultural waste". Enter the corporate skeptics - "We are a forest products company", "Why aren't other companies doing this, too?", "The price of OCC and chips will go down and straw will be too expensive", etc. It took one thumb down to kill the project.


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