Hallowell ? A southeast Kansas explosives plant is preparing to resume manufacturing operations, even though the company that once ran the plant remains under a federal criminal investigation.

The license of the Slurry Explosive Corp. was revoked earlier this year. But last week, the Paper, Allied-Industrial, Chemical and Energy Workers International Union said Slurry’s sister company, Universal Tech Corp., applied for the license.

Slurry and Universal are owned by LSB Industries of Oklahoma City.

On April 18, the Bureau of Alcohol, Tobacco and Firearms announced its criminal investigation after the company’s license to manufacture explosives was revoked.

The federal agency had just completed the removal of 4.2 million pounds of explosives from the plant. The plant’s ATF license allowed it to store no more than 90,000 pounds of explosives.

Slurry’s appeal of the revocation was turned down, and the criminal probe continues.

Clive Whiteside, acting plant manager, said Friday when manufacturing operations did resume, Slurry would be a changed plant.

“We’re just making a whole system of changes to the layout and equipment to improve the performance and safety of the operation,” Whiteside said.

Robert Mosley, the ATF director of industry operations based at Kansas City, Mo., said ATF approval of a new license should be forthcoming.

“We’re nearing completion, but not complete,” he said.

In the meantime, Whiteside said plant personnel were continuing to look for the cause of a release of nitric acid fumes Thursday that resulted in the hospitalization of a construction worker and the evacuation of the plant.

It was the only part of the plant not shut down when the ATF seized it in January in connection with the discovery of a storage-limit violation.

The nitric acid solution produced on the line is not an explosive, but it is used as an ingredient in explosives. Because it is not an explosive, the ATF has no jurisdiction over it.

Whiteside said the hospital kept the worker overnight Thursday after the worker complained of lightheadedness and a sore throat.

Whiteside said he reported the release to the Kansas Department of Health and Environment.