At around 1:30 p.m., molten alumina caught fire in a furnace used to make a mixture of alumina and aluminium oxynitride at a mineral production plant. The fire produced a considerable amount of heat and smoke. The 16 employees of the corundum fusion facility were evacuated. One employee was made slightly ill by the smoke. The firefighters cooled the furnace from the outside. The fire occurred when the bottom of the furnace’s hearth burst, spilling out 7 tonnes of molten alumina that spread over an area of 70 m².

A total of 200 m³ of firewater was needed to cool the furnace’s shell. It could not be contained on the site and was discharged into the Bénétant, a mountain stream.

The accident was caused by a deteriorated gasket. Each time before the furnace is started, this refractory gasket is fitted by technicians.

Since the event, the operator plans to:

• fit ceramic fibre rope between the furnace’s base and duct to prevent leakage of the gasket material;
• use a calibrated product (0.2 to 0.7 mm) for the gasket between the furnace’s shell and cone;
• modify the furnace preparation procedure;
• build a suitable tool for repairing damage to the gasket;
• increase the cooling water capacity;
• install a new emergency exit in the control booth;
• raise awareness and provide training to the facility’s workers on initial emergency response measures.

The inspection authorities for classified facilities asked that the operator update its internal emergency plan to include a scenario of fire caused by a leak of molten material.