Around 6 a.m., dust and gas emissions are emitted when a blast furnace is put back into service after a 5-day shutdown. During the night, between 1 h and 3:40 am, emissions occur due to the sudden formation of a channel in a charge column. The flow distribution is disturbed. The pressure increases and leads to tap holes.

Dust and 2.5 t of blast furnace gas are released. 160 buildings (houses and garden furniture) and 270 cars are impacted by these dust emissions.

5 days earlier, at around 6.50 p.m., hot air (1 100 °C enriched with oxygen) from the cowpers escapes through holes in the pipes with a pressure of 3 bar. As the pipe is lined with refractory bricks, bricks are ejected from the damaged part of the pipe. The blast furnace is then immediately shut down and brought to safety. The plant fire service cools down the site. The fire brigade intervenes. Repairs are carried out. As the blast furnace was shut down without this shutdown being programmed, it could not be restarted according to the normal procedure for programmed shutdowns. When a blast furnace is shut down, a batch with an increased coke content is fed into the furnace 8h avant during the shutdown, which compensates for the energy lost during start-up. As there was no batch available and heat had been lost during the previous five days, the charge was clogged. It was difficult to pass gas through the load column to restart. After repair, the blast furnace was put back into service the day before the accident at about 0600. At start-up, hot air was sent to only 12 of the 30 tuyeres. During the night, at 1 a.m., a first blast consisting of dust and hot gases is emitted for 19 seconds. Then a second at 3:40 am for 45 seconds. These emissions occur due to the sudden formation of a channel in the load column. The pressure rises and causes the safety valves to open.