Disposal of Unconditioned Solid Fuel in Blast Furnaces Operating with High-Pellet Batch
摘要
The proportion of pellets in blast furnace batch and in the overall iron ore feedstock increases every year. The expectation is that the pellet content in iron ore will increase to 90%. At the same time, sintering is not only a method of producing raw material for the blast furnace but an important aspect of waste recycling: both iron ore waste (blast furnace dust, gas treatment dust, and so on) and fuel waste (coke fines and sludge). In the present work, the potential for disposal of unconditioned blast furnace fuel (coke fines, sludge) at a steelworks with no sintering shop is assessed. The method employed is physical modeling with estimation of the fuel consumption at steelworks. When the batch used in pig iron production has a high pellet content, problems arise in disposing of secondary energy resources: coke fines and sludge from coke production, which may be produced in quantities of 20–30 kg/t of pig iron. The solid fuels should account for no more than 10 wt % of the blast furnace briquets. At that rate, carbon-bearing wastes may be completely utilized in the blast furnace if its capacity is no more than 1000 m3, but may be insufficient in the case of larger furnaces. If we consider full-cycle steel plants with pelletized batch, when moderate quantities of ore and carbon wastes (secondary resources) are available, it makes sense to produce briquets from these wastes and then smelt them in the blast furnaces. That will reduce the furnace’s coke consumption. If carbon wastes are produced at rates significantly exceeding 10–20 kg/t of pig iron, either a sales and delivery system must be set up for these products (in addition to briquetting) or else production of iron in rotary hearth furnaces or of blooms (sponge iron) in tubular furnaces must be organized. That will ensure not only disposal of the carbon-bearing wastes but also the production of additional iron from the secondary iron-bearing components.