Deadly paper mill implosion illustrates industry's risks

The chemical process pulp and paper mills use to transform wood into everyday products includes a number of potentially violent points of failure, and some industry experts have been raising red flags for years.

The dangers of this practice became even more evident Tuesday in Longview. There, a large tank of heavily caustic chemicals imploded.

The implosion has likely killed 11 workers and injured several others. It released hundreds of thousands of gallons of these dangerous compounds into the environment, contaminating the Columbia River.

The mill workers I've talked to want full accountability," said U.S. Rep. Marie Gluesenkamp Perez, speaking at a Wednesday news conference. "They want a comprehensive, unbiased investigation into how this could have happened, so the failures can be addressed, so we can have safe jobs and come home to our families at night.

A federal investigation is underway as regulators and industry officials try to piece together what happened and why. What's immediately clear, however, is that the mill, the Nippon Dynawave Packaging Co., carries a long history of clean air, water and safety violations, underscoring a system of problems at the facility and light responses from regulators.

This chemical process itself is called kraft pulping, and it's been in use for well over a century, said Julia Shamshina, an associate professor at Texas Tech University focused on fiber and biopolymer research. It's the dominant practice worldwide in the paper and pulp industries.

At the outset, mixing dangerous chemicals with high temperatures and pressure can amount to a recipe for disaster under the right conditions, Shamshina said.

"If there is any way for an accident to happen, it will," she said.

In simple terms this process requires a mill to place wood chips into a large tank filled with a slurry of caustic chemicals - sodium hydroxide and sodium sulfides (called "white liquor") - where it's cooked under pressure to break down the material.

This is the first risk point in the process, Shamshina said.

The Nippon Dynawave Packaging Co. reported at least one problem with its white liquor holds in August 2020, when an employee left a valve open, spilling up to 5,000 gallons in the process, according to a report filed with the state's Department of Ecology. Mill officials classified the cause of the spill as employee negligence.

The second risk point comes after the mixture is cooked and the mill attempts to recover its own chemicals from the mixture, which is now called "black liquor." A byproduct of this process, called "molten smelt," is particularly dangerous, Shamshina said, because it can cause an explosion if it comes into contact with water.

Ecology cited the mill last December after dozens of gallons of black liquor shot out of a pressure relief valve. A mist of the chemicals settled over the property, spraying as far as the place's central maintenance parking lot, records show.

Black liquor is so corrosive it's comparable to lye, with the potential to burn skin and eyes, cause lung damage and more.

This release in December took place during a "process startup," Ecology determined, noting that the relief valve operated as intended. Because of this, and the relatively small amount of chemicals spilled, state officials took no further action but recommended that the mill review its startup procedures to prevent similar events in the future.

Emergency officials have noted that Tuesday's fatal incident involved white liquor. Further complicating the picture, the tank imploded rather than exploded. Not to mention, this tank held some 900,000 gallons of the liquid.

This could mean several things.

Speaking in general terms, a tank of that size could have been for storage rather than a more active part of the process, said Robin Rogers, a professor emeritus in the department of chemistry and biochemistry at the University of Alabama, Tuscaloosa.

Large temperature swings in the tank could potentially lead to an implosion, Rogers said. If crews attempted to remove quantities of the white liquor without a supply of air or anything else to replace the volume, that could lead to an implosion as well.

All these hazards and more are well known and can be managed, Shamshina wrote in an email, "but when maintenance, inspection, training, or safety systems fail, the consequences can be serious."

"If a facility already has repeated violations, maintenance issues, or other operational problems, often those inherent hazards become much more concerning," she continued.

Other pulp and paper mills across the United States and Europe have seen boiler explosions, corrosive gas and chemical leaks, multiple smelt water reactions and more. These incidents have killed and injured people and polluted the environment.

Further down the process, cellulose is extracted from the mash, which is separated and used for paper products. Many of the leftover chemicals can be recycled and used again.

Even though the Kraft pulping process has been used for generations and perhaps serves as the de facto standard, it's not above criticism or suggestions for improvements, Shamshina said.

She and Rogers are part of a small cadre of experts warning about the risks evident in mill disasters across the world. And they're advocating a gentler, safer process using nontoxic and nonvolatile solvents. But their findings and suggestions have been met with quite a bit of industry pushback, they said.

The time is right to reexamine the industry, however, they argue. As major industries shift away from plastics, and as news of "forever chemicals" contamination spreads, wood-based substitutes are emerging as a viable alternative.

Kraft pulping shouldn't be considered "untouchable" simply because it's been used for so long, Shamshina said.

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