Kansas City, Mo. ? The federal government cited a Missouri grain company Thursday for willful safety violations and proposed a hefty fine for an explosion that killed six workers last October at a northeast Kansas grain elevator.

U.S. Labor Secretary Hilda Solis said in a news release the deaths at the Bartlett Grain Co. elevator in Atchison “could have been prevented” if the operators had addressed hazards known in the industry. The Occupational Safety and Health Administration is seeking $406,000 in penalties in addition to the 13 citations.

“Bartlett Grain’s disregard for the law led to a catastrophic accident and heartbreaking tragedy for the workers who were injured or killed, their families and the agricultural community,” Solis said.

Kansas investigators previously determined the Oct. 29, 2011, grain dust explosion was accidental.

A release from the labor department notes that grain dust is nine times as explosive as coal dust. The agency said problems included a lack of proper preventive maintenance and an inadequate emergency action plan.

Bob Knief, the president of Bartlett Grain, said in a written statement that the company plans to prove wrong “OSHA’s unfortunate citations and characterization.” He said the company disagrees with claims that there was a hazardous accumulation of dust before the accident and contends the grain and dust found by OSHA was deposited by the accident.

“The safety of our employees always has been and continues to be our highest priority,” Knief said. “The accident … was the darkest day in Bartlett Grain’s 105 year history. We always will grieve that we cannot restore these men to their families and friends, or their co-workers at Bartlett. From that terrible day, we have believed and stated that we were operating responsibly.”

OSHA also cited Bartlett contractor Topeka-based Kansas Grain Inspection Services Inc. for one willful violation alleging a lack of fall protection for employees working on the top of rail cars, one serious violation alleging lack of a hazard communication program and one other-than-serious violation alleging it failed to provide basic advisory information about respirators to employees. Those violations carry proposed penalties of $67,500. A call to the company wasn’t immediately returned.