Investigators Cite Concerns From Fatal Chemical Explosion

The U.S. Chemical Safety and Hazard Investigation Board (CSB) released an update Thursday from its investigation of the Ames Goldsmith Corporation’s Catalyst Refiners, Inc. explosion.  

On April 22, 2026, a chemical reaction killed two employees and injured 22 others, including four first responders. It produced highly toxic vapors during the transfer of chemicals into a wastewater receiving tank at Catalyst Refiners while the facility was being decommissioned.  

Catalyst Refiners refining operations involved processing spent catalyst and recovering silver for reuse. At the time of the incident, the company had ceased silver reclamation, but the facility’s wastewater pretreatment system remained in operation. 

According to the CSB report, employees observed a chemical reaction occurring and a fog forming over the tank. The employee who was operating the pump stopped the flow of nitric acid into the tank. The employee went outside to get some fresh air but then passed out. The employee subsequently regained consciousness. 

 A supervisor, who had been notified about the issue with the chemicals, approached the tank area and also lost consciousness. 

Two additional employees, who were not involved in the chemical transfer, also entered the area to assist. One of these employees pulled the unconscious supervisor away from the tank area.  

The supervisor recovered, but the employee who had come to the supervisor’s assistance, as well as the one who also had entered the area, were both overcome by the vapors emitting from the tank and later died. 

Emergency responders subsequently detected hydrogen sulfide at the facility. A shelter-in-place order was issued for an area within one mile of the facility.  

The CSB found four full-face respirators at the facility, but they were not equipped with filters that would protect against hazardous gases such as hydrogen sulfide. 

Additionally, workers at the facility told the CSB that respirator use was no longer required after the facility transitioned from production to decommissioning. Catalyst Refiners also did not provide or require employees or contractors to use personal gas monitors. 

CSB Chairperson Steve Owens said, “This tragic incident underscores the need to have clear procedures and safely manage the serious chemical hazards that can arise during facility decommissioning.  Although the CSB’s investigation is still ongoing, we are concerned that Catalyst Refiners did not require employees to wear respirators during decommissioning and also never provided or required workers to use personal gas monitors that might have alerted them to the presence of the highly toxic hydrogen sulfide gas.” 

Moving forward the CSB will continue to further analyze several key issues, including: 

•  Chemical hazards and incompatibilities; 

• Decommissioning hazard analysis; 

• Chemical disposal procedures; 

• Personal protective equipment and atmospheric monitoring; and 

• Corporate governance and oversight.