Production data for coking shop 2 and blast furnace 5 in 1998 mainly confirm the recommendations based on the 1996 results given by the new estimation method. The changes in batch composition adopted are largely useful. Eliminating secondary coking coal and replacing gas-grade coal with soft gas-grade coal improves the operation of blast furnace 5. Eliminating Neryungr coal and increasing the soft-coal content in the batch above 30 percent proves undesirable. In coke-production conditions, during the research period, grades of coal may be ranked in order of decreasing blast-furnace effectiveness as follows: lean sintering coal; soft coal; coking coal; gas-grade soft coal; and gas-grade coal. Less grinding of the coal batch and more prolonged coking, while improving almost all the quality characteristics of the coke, impair the operation of blast furnace 5. The only recommendation not confirmed in the test period is more prolonged coking. This is probably due to the change in the qualitative composition of the coal batch, for which a different duration of coking must be optimal. Changing the batch composition may be expected to increase furnace productivity by a further 8.11 percent and to reduce coke consumption by 6.41 percent. However, the technological parameters selected for improvement of the coke characteristics neutralize any possible positive results. Direct estimation of the influence of coke production on blast-furnace operation is more reliable, simpler, and more economical than the classical method based on quality characteristics of the coke. The classical method is less accurate in blast-furnace control because the outcome of change in coke quality is uncertain. It has been shown that, in some situations, the dependence of blast-furnace operating parameters on the characteristics of coke is qualitatively and quantitatively different from the generally accepted concepts. In addition, some of the most important characteristics of coke quality - for example, the hot strength - are not monitored by existing methods. The new method of evaluating the influence of coke quality on blast-furnace operation directly in terms of its production parameters needs to be tested in practice. If it proves suitable and effective, it should be adopted as the basic technique in coke-production and blast-furnace shops.
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