A chemical tank implosion at Nippon Dynawave Packaging Co. in Longview, Washington, killed at least one worker, injured nine people and left nine others unaccounted for, according to AP.

Reuters reported that the rupture occurred around 7:15 a.m. local time May 26 at the company’s pulp and paper facility. The tank contained about 900,000 gallons of “white liquor,” a mixture of sodium hydroxide and sodium sulfide used in papermaking, Reuters reported.

AP reported May 27 that responders had paused recovery work until the following morning because the collapsed tank remained unstable and could leak more caustic liquid. Reported injuries ranged from minor to critical and included burns and inhalation injuries. A firefighter was among those injured.

The cause of the implosion remained under investigation. Nippon Dynawave Packaging is a pulp and paper operation associated with Nippon Paper Industries. It is not a Nippon Paint facility.

Sources: Reuters, AP

Material note for the coatings industry: White liquor is a pulp and paper process chemical, not a coatings raw material. However, sodium hydroxide has coatings relevance. A PCI technical article on neutralizers notes that sodium hydroxide is among the strong inorganic bases used as neutralizers in waterborne industrial and automotive coatings.