In a black powder manufacturing shop, a fire broke out on charcoal / saltpetre dusts (binary mix with, in principle, no pyrotechnic components). At the end of the one-tonne drainage cycle, the dropping of a 40-kg counterweight first on the drive pulley, then on the floor, caused the dust to ignite. Damage was limited; a few cans and lids were destroyed by the fire. The operator proceeded with a systematic inspection of all welds on both the counterweight (welds on lids) and pulleys.