Patent ID: 6264723
Filing Date: 2001-07-24
Classification: C21B,C21C,Y02P

Abstract:
In a method of manufacturing steel by carrying out successive steps in a process sequence including a blast furnace and an electric steel furnace, the steps including producing pig iron in the blast furnace, transporting the liquid pig iron to the electric steel furnace, charging the electric steel furnace with at most 60% by weight liquid pig iron and with additional iron carriers, operating the melting process in the electric steel furnace, using electric energy and simultaneously using oxygen and injected coal, the improvement comprising operating the blast furnace as a mini-blast furnace having a capacity of 0.3 to 1.0 million tons pig iron per year with 60% by weight to 100% by weight iron pellets, at most 40% coarse iron or/and at most 400 kg coke per ton of pig iron charged through a throat of the mini-blast furnace and with at most 250 kg coal per ton of pig iron injected through tuyeres of the mini-blast furnace, and with hot air enriched with at most 10% by volume oxygen, charging the electric steel furnace with the pig iron produced in the mini-blast furnace and with additional iron carriers including at most 70 percent scrap, and further introducing into the electric steel furnace at most 65 m.sup.3 O.sub.2 /t and fine coal.