Spent platinum catalyst is recovered from corrugated stainless steel by chemical stripping and recovery. The process is completed by placing the material in lined tanks filled with hydrochloric acid (HCl). Approximately 500 pounds of corrugated stainless steel with platinum coating was inserted into a HCl leaching bath. Prior to starting the process, the supervisor tested the material for reactivity for a period of one hour, and the material showed very little reactivity. Operators began setting up three 500-gallon tanks, each containing the corrugated material. The material was covered with water and 4-5 inches of HCl was then added to the tank. When all three tanks were set up and there was only minimal reactivity observed (occasional bubbles), the operators left the area.
An employee walking through the parking lot noticed smoke coming from the leaching area and reported it to the security guards. The guards and the supervisor headed to the incident area. On arrival, they noticed a large amount of exposed metal above the surface of the bath. The metal was sparking and crackling (indicating catalytic activity) and hydrogen liberated from the reaction was flaring up from time to time as it was ignited by the sparks. There was no evidence of spilled liquid, which indicated that there was a leak from the tank liner.
The fire was extinguished with fire exchangers and water spray, but since the metal was still above the solution level, it flared up again minutes later. The supervisor and an operator added water to the incident tank while at the same time pumping the solution to an adjacent empty tank until the pH of the incident tank was approximately 1. The supervisor placed a fiberglass grating on top of the exposed metal to submerge it below the solution level.
Four photos are attached showing: 1) the material prior to processing, 2) the material ready for processing, 3) the process tank after the fire, and 4) the process tank after the fire with the fire-extinguishing media on top.
- Include the tanks in a regular inspection program. Evaluate their condition and replace if necessary.
- Fill the tanks only half full with leach material.
- Keep the material completely submerged in solution.
- Install a fiberglass grating on top of light material to keep it submerged.