Environmentally safe ironmaking
Finex® is an innovative ironmaking process developed for the production of hot-metal based on the direct use of fine ore and non-coking coal.
In the Finex process, fine iron ore is charged in a series of fluidized-bed reactors, passes in a downward direction where it is heated and reduced to direct-reduced iron (DRI) by means of a reduction gas – derived from the gasification of the coal – that flows in the counter-current direction to the ore.
The DRI fines are then hot-compacted to hot-compacted iron, transferred to a charging bin positioned above the melter gasifier and then charged by gravity into the melter gasifier where smelting takes place. The tapped product, liquid hot metal, is equivalent in quality to the hot metal produced in a blast furnace or Corex plant.
The excess gas from the process can be used for a variety of industrial applications. In the Finex process, both capital investment and production costs are much lower than in the blast furnace route, and its environmentally friendly nature ensures that it will be even more attractive in the future.
The unique characteristics of the Finex process and its ability to use low-cost raw materials mean that both capital investment and production costs are much lower than in the blast furnace route. A 1.5-million-ton-per-year Finex plant can produce hot metal more cost effectively than a modern three-million-ton-per-year blast furnace. When oxygen and power plants are included in the comparison, the capital and operating costs of a Finex plant are approximately 20% and 15% lower, respectively, than in the blast furnace route.
Finex technology continues to be developed and optimized by Posco and Siemens Metals Technologies with the goal of further improving the feasibility of the process and its overall competitiveness. The Finex process is thus an outstanding example of highly successful cooperation between plant operator and plant builder, which allows hot metal to be produced in a highly cost-effective and environmentally friendly manner.
SOx, NOx, and dust emissions are significantly lower in the Finex process than in the blast furnace route. This is due to the elimination of the coke oven and sinter plants, both major sources of emissions. The sulfur contained in the coal reacts with limestone to form CaS, which is bound in the slag. Therefore, there is almost no opportunity for SOx to escape into the environment. NOx emissions hardly occur in the Finex process because the metallurgical reactions take place in a reducing atmosphere, unlike the oxidizing atmosphere inherent in the sinter plant, coking plant, and hot-stoves of the blast-furnace route. Dust emissions are also low, due to the integrated and closed nature of the Finex process. It has also been shown that no dioxins are generated in Finex operations.