Recycling of oil-contaminated mill scale and shredder light-density fractions by injection into blast furnaces

Objective. Oily mill scale sludge and shredder light-density fractions esse ntially comprising plastic wastes have been deposited on waste dumps on man y occasions in the past. For reasons of environmental protection, this type of disposal is today no longer feasible. It was therefore to be examined w hether these materials can be injected into blast furnaces and what effects they have on the hot metal quality and on blast furnace operation. Summary. A pilot plant for the combustion of carbonaceous dust has been dev eloped and constructed at the Institut fur Eisen- und Stahltechnologie of T U Bergakademie Freiberg. It simulates the conditions in a blast furnace, fr om the dust's entry into the blow pipe, and passage through the tuyere, to its arrival in the raceway. A mathematical model has been used to further c alculate the carbon combustion beyond the tuyere blow pipe. Injection of a treated, oil-contaminated mill scale sludge and of a shredde r light-density fraction has been examined. It is, in principle, possible t o inject such materials, which field trials at a blast furnace of Eko Stahl have also confirmed. But their burn-out behaviour is poorer than that of p ulverised coal, and economical operation can be achieved only by the costs of their disposal being paid for.