A Feb. 21 explosion at the Trojan Corp. near the mouth of Spanish Fork Canyon was probably due to friction or a stirring paddle hitting the explosive material being mixed in a 1,500-pound pot, according to Douglas McVey, administrator of the State Industrial Commission's Occupational Safety and Health Division.

As the result of the explosion, which injured five workers on a bus or in nearby buildings, OSHA has issued a citation charging Trojan with seven serious violations and one lesser violation and fined the company $3,410.The company asked for and received an informal review on the citation, and McVey said a decision is expected in a few days. Depending on the outcome, the company has the right to ask for a formal review.

Although most of the evidence was destroyed in the explosion that demolished one building and damaged several others, McVey said his investigators determined what likely occurred after interviewing witnesses.

Trojan employees were mixing TNT, PETN and RDX (all explosives) into boosters used to initiate blasting agents used in mining. The employees apparently added the ingredients too quickly in the 1,500-pound mixing pot, and the material began to "cheese up" or solidify.

The paddle on the pneumatic motor was barely turning because of the solid state of the material, so the crew reduced the motor speed and went on their break. Just as the crew returned on the bus to the area, the explosion destroyed the building and damaged the bus and several other buildings.

McVey said company officials theorize the torque of the motor bent the shaft of the mixer as it was turning the stiff material and either friction or the paddle hitting the material touched off the blast. McVey said the 1,500-pound pot exploded first, and that caused the two 1,000-pound pots to explode.

In all, a total of 6,000 pounds of materials exploded.

The Feb. 21 explosion had a direct link to an April 21 explosion at the Trojan plant because Junior Underwood, 62, Salem, Utah County, was injured when he used a torch to salvage some material from the building destroyed in February. Although an investigation is still under way, McVey said it appears the material Underwood was cutting was contaminated with explosives.

Ironically, it was the second explosion, although smaller, that caused the most serious injuries in the two incidents. McVey said Underwood lost one finger and part of his left ear.