Trying to pinpoint what went wrong at the Androscoggin Mill - Lewiston Sun Journal

Wreckage smolders after an explosion at the Jay paper mill Wednesday. The explosion shook the ground and produced a plume of black smoke that was visible for miles. Russ Dillingham/Sun Journal

JAY — Investigators began Thursday to try to figure out what caused an explosion at the Androscoggin Mill that left part of the complex a smoking ruin but caused no serious injuries.

Just before noon Wednesday, company officials said, one of the plant’s major pieces of equipment, called a digester, blew up, leaving a key section of the paper mill a charred and shattered mess.

It’s already clear, a company spokeswoman said, that without the digester the mill won’t be able to produce pulp “for a significant period.”

The mill’s paper machines, however, were not damaged so its owner, the Pennsylvania-based Pixelle Specialty Solutions is “exploring options to resume paper machine operations as soon as possible to serve our customers,” said Roxie Lassetter, its human resources manager at the mill. How long it might take to restart is uncertain.

While the state fire marshal’s office and others probe the wreckage, the company is trying to figure what, if anything, it can do to keep operating. With so much equipment ruined, the mill’s prospects, which seemed bright, suddenly look less certain.

Gov. Janet Mills said at a Wednesday press conference that “we don’t know yet what the future may bring for the Androscoggin Mill. That will come more fully into view in the coming days.”

Town officials are overseeing a cleanup — warning people the debris blown into the sky and settling in the area could be irritating but isn’t unhealthy.

The town of Jay posted Thursday on social media that “as the mill begins assessing their next steps and what the future holds, we will stand strong with them as a community. This area has already faced so much and we will continue to do it — together.

“To all the workers at the Androscoggin Mill, we are thinking of you and keeping you in our prayers in the days ahead,” the town said.

Fire Chief Mike Booker said that “we are entering into the next stage of this where everyone is concerned about the financial implications, and I definitely share the same concerns.”

Booker said the air quality is safe despite “a nuisance smell.”

He said people who want to sweep up the debris can do but should wear gloves and, if dust is present, a face mask.

“The chemical with the pulp is classified as a mild irritant,” Booker said in a Facebook post, and it “will dissolve over time, and is known as a good fertilizer.”

The mill survived a post-recession paring that wiped out five Maine mills. It was sold in January by the Ohio-based Verso Corp. to Pixelle Specialty Solutions, the largest specialty paper producer in North America. It employs about 500 people and is valued by the town at more than $325 million.

Not every paper mill has an attached pulp mill. Pixelle itself said it had four specialty paper mills, including the one in Jay, and only three of them also produced pulp. It is a material that can be hauled in, though whether it is worth doing financially is part of what the company is figuring out.

Craig Aderman, a retired stationary steam engineer from Freeport, said he worked for years for Sappi Global, which has paper mills in Skowhegan and Westbrook.

He described his job there, at root, as trying “to keep things from blowing up and killing people.”

The digester, he said, is a key component for a paper mill because it’s the place where wood chips are fed in and turned out into a pulp that can be used to make paper. It’s sort of giant pressure cooker.

It is such a central part of the operation that in the summer of 1964, when then-owner International Paper proudly cut the ribbon on a $54 million investment in Jay for a new mill, it proclaimed it had built it “around a gigantic continuous digester, the newest development in the pulp and paper industry.”

“Towering over 210 feet in the air,” the company said, “the digester will be able to manufacture 500 tons of high-quality kraft pulp every day.”

What changes were made in the more than half century since are unclear. Mentions of investments in the mill mentioned online do not mention anything more about its digesters except for a temporary shutdown of one between 2016 and 2018.

What happens in the tall steel vessel is that wood chips are mixed with hot water, sodium hydroxide and sodium sulfide — a brew known in the business as cooking liquor — to break them down.

Experts from the Ernest Orlando Lawrence Berkeley National Laboratory in California said in a report on the process that the ingredients are pressurized and cooked at about 330 degrees for several hours in the digester, allowing the liquid “to permeate the wood chips and dissolve most of the non-fibrous constituents in the wood.”

Aderman said that operating continuously under high pressure, the digester circulates the chips in cooking liquor until they float down to the bottom, where a huge scraper removes the brown pulp for the next step in the paper-making process. Hundreds or thousands of tons of chips can move through daily.

Typically, the pulp is then bleached white, Aderman said.

The risk is that stress fractures can arise on the pressurized vessel, he said, especially at transition points where the shape changes. He recalled finding one once near the top of a vessel in a Sappi plant that could have posed a serious risk.

Normally, he said, close inspections are done annually to make sure there aren’t any problems.

Aderman said it was fortunate nobody was around when the digester at the Pixelle Specialty Solutions-owned mill exploded. But it would not have been unusual that nobody was nearby, he said.

He said in his experience, people checked digesters every couple of hours to eyeball them and see if everything appeared to be running smoothly. They are actually operated from a control room, he said, that doesn’t need to be close by.

Blasts like the one in Jay are rare, Aderman said, and not necessarily catastrophic.

“This is probably one of the worst explosions I’ve heard of,” he said.

At a press conference late Wednesday afternoon, Mills hailed the fact that nobody was seriously hurt in the Jay explosion.

“There’s a common saying that ‘God will not give you more than you can carry.’ And without question the burden for us now is heavy,” she said during her press conference. “But Maine people can carry it and we will carry it. I just want to say, if ever there was a day when we should believe in miracles, today is it.”