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North America's First Tree-Free Pulp Mill

GRAEME RODDEN

(Editor's note: This is an excerpt from a feature in the forthcoming March/April 2019 issue of Paper360° magazine, the official magazine for TAPPI Members, and is offered as a special "sneak peek" for AOTC readers. See links below.)

It is not a new concept—pulp made from non-wood fiber—and it has been discussed for years, but not until now has it again become a reality in North America. Columbia Pulp (Dayton, WA) is about to start up the first North American greenfield pulp mill in quite some time. The revolutionary aspect is that agricultural waste—wheat straw—will be the furnish.


Company CEO John Begley says that wheat straw was a prevalent fiber source in the US Midwest until the 1960s when environmental regulations made it non-feasible. Speaking at the 2018 RISI North American Forest Products Outlook Conference in San Francisco, Begley noted that non-wood fiber had a poor reputation when it came to pulp: weak characteristics and a "dirty" production process.

The renaissance of using wheat straw goes back about 20 years. The area around the Columbia Pulp mill is one of the highest density wheat growing regions in the US. One of the biggest issues for growers was the disposal of the wheat straw.

The annual burning of this agricultural residue following the harvest was creating huge pollution and potential health problems in eastern Washington (45,000 tons/yr of atmospheric emissions). Every year, four to five million acres were being burned. It got to the point where the state imposed a levy on farmers. The money from the levy paid for studies looking at possible methods to commercialize the wheat straw after harvesting.

The issue ended up at the University of Washington pulp and paper school, where Bill McKean and Mark Lewis took it on and developed a process to pulp the straw. Begley says that after a "false start" about seven years ago, the team developed proprietary technology now called the Phoenix Process.

This led to the establishment of Sustainable Fiber Technologies (SFT), of which Lewis is CEO. Laboratory–scale runs showed the viability of the project. "They then contacted me and asked if I could bring it to the commercial stage," Begley explains. This led to the establishment of Columbia Pulp. "It has taken about five years to get to this stage.

"We bought the license for the Phoenix Process from SFT," Begley adds. At the pilot stage, Central National-Gottesman (CNG) was brought in to enhance market awareness and customer satisfaction.

FROM PILOT TO COMMERCIAL
The pilot plant was started in September 2018 and papermakers have shown a lot of interest, according to Begley. "There is growing awareness in the papermaking world for the environmental benefits of it as well as the question of sustainability. We will do a life cycle analysis of the product and we expect it to have a significant competitive advantage."

Columbia Pulp is owned by about 20 individuals and one private equity firm, Columbia Ventures (Vancouver, WA) whose majority owner is Ken Peterson. With firm financing commitments, a technically feasible process, and interested customers, ground was broken for the mill in August, 2017. Startup was scheduled for early 2019. Total cost is estimated at US$200 million.

Columbia Pulp has contracts with about 10 companies that bale the wheat straw for the region's farmers as well as agreements with a few individual farmers. Most of the contracts are for three years.

At capacity, the mill will use 600 tons/day (240,000 tons/yr) of raw material to produce 400 tons/day of pulp and 200 tons/day of biopolymers. The straw is 67 percent cellulose and 33 percent lignin and carbohydrate.

The shelf life of agricultural residue has been questioned. Begley says that wheat straw does pass the test of time, as it were. "It is good for more than a year," he adds. "We have some from 2016 that is showing some degradation. The 2017 stock is still in good shape."

Columbia Pulp will collect the wheat straw within a 100-mi radius of the mill. Within that area, about four million tons of wheat is grown so availability of raw material is not an issue. The wheat straw is baled; each weighs 1,000 lb. Columbia Pulp will buy about US$13 million of straw annually.

Columbia Pulp has five sites set aside for exterior storage. Begley adds that the region is one of exceptionally low rainfall: about 9 inches (22 cm) of moisture annually.

Although proprietary, Begley describes some of the process. It is a sulfur-free chemical process that needs no pressurized or high-temperature vessels. It uses 25 percent less water and only 30 percent of the energy compared to a traditional pulp process. It is a closed system so there is no need for effluent treatment. Therefore, there are economical as well as environmental advantages.

Begley says the wheat straw is put into a large vat where water and chemicals are added. "When dealing with straw," he explains, "it is a weaker fiber than wood so you need to be careful how you process it. It needs to be a milder, gentler process."

After the pulp leaves the retention tank, it goes through what Begley says is a conventional pulping process (refining, pressing, washing) and into a wet lap machine. There is no bleaching. Moisture content of the wet lap bales will be 50 percent.

PAST QUESTIONS ABOUT NON-WOOD NOT AN ISSUE
Asked about the challenges of pulping a non-wood fiber, Begley explains, "Because you don't really cook it, the silica stays in the process. The biggest challenge is the annual nature of the harvest and resulting material handling and storage."

Begley says Columbia's pulp will be similar to hardwood pulp. Fiber length is about equal and it is brighter. "It has a golden hue, like the straw itself," he adds. "We are looking at being a hardwood substitute and it is cleaner than people think."

The main end uses targeted are tissue (most types) and molded products. Packaging is another possibility, says Begley, as are specific grades such as label backing.

In terms of how it can be used, Begley adds that for molded products, wheat straw pulp could be the entire furnish. "Every paper grade is usually a recipe," he explains. "So, it will all be up to the papermaker. A tissue/towel with 50 to 60 percent hardwood pulp could be a goal. Our pulp won't replace softwood."
Begley reiterates that the Columbia pulp will complement, rather than compete with, traditional wood pulps.

"Our plan is to have one grade," Begley continues. "However, some end uses require certain parameters—for example, molded products want lower freeness. But, for the most part, we will target the same pulp product."

Another benefit is that the waste stream (200 tpd) also has revenue potential. The biopolymers can be used in deicing, erosion control, dust suppression, and agro-chemical applications.

About the author: Graeme Rodden is senior editor, North and South America, Paper360°.

To read the rest of this article—plus feature content on Automation, Reliability & Maintenance, and the World Bioeconomy Forum in Finland—subscribe to Paper360° at www.paper360.tappi.org.

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