In order to improve present iron ore agglomeration processes drastically and meet the demands of future trends in iron ore resources suitably, a new agglomeration process named the Hybrid Pelletized Sinter process was studied. On the basis of a prior experimental study and the semi-commercial plant trial, a No. 4 GasFlow Characteristics in Agglomeration ProcessIn an agglomerating plant using the grate system, the control of gas flow passing through the bed is extremely important because it directly affects the productivity and the yield. Recent studies on the sintering process indicate that in the raw material charging unit, avalanches caused by stickiness and repose angle of the quasi-particles occur periodically along the moving direction of the grate. The productive yield of the sinter is reduced by these avalanches.15) This is attributed to the fact that as permeability in the sintering bed changes locally, due to these avalanches, gas flow fluctuates along the bed depth.In order to prevent the avalanches, various charging devices are being studied.15,16) Bycontrast, the HPS process has the following superior characteristics, in comparison with sintering process: (1) The green pellets are more spherical comparedto the quasi-particles.( 2) Since the surface of the green pellets is covered C 1993 ISIJ ISIJ International, Vol. 33 (1993)

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SynopsisIn the iron and steel making shops, some processes are so complex that it is difficult to formulate precise control models. In such cases, process control is made on the basis of the skilled operator's heuristic knowledge. However, utilization of skilled operator's heuristic knowledge is one of the major problems to control the process precisely. In the fuzzy set theory, skilled operator's knowledge is expressed as membership functions to control the process as well as skilled operators.The fuzzy set theory was applied to the on-line control of return fine hopper level at the sintering plant in Fukuyama Works, Nippon Kokan K.K. This was the first application of fuzzy control to the practical operation. The commercial operation has started in August 1986. As the result, the deviation of return fine hopper level decreased from 12 to 4 %/h and the amount of return fine decreased by about 2 kg/t-sinter.

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