Year

1985

Degree Name

Doctor of Philosophy

Department

Department of Metallurgy

Abstract

The investigations described in this thesis are concerned with the effect of the operating conditions on the size segregation of particulate material during flow. Particular emphasis was placed on the effect of operating conditions used in the bell-less blast furnace operations.

In part 'A' of the investigation, the basic experiments were conducted with binary mixtures of sinter particles received from A.I.S. Port Kembla. The segregation of particles during flow on a rectangular plane, a triangular plane and in a 1/17th blast furn ace model on a hard wooden base stock-line was investigated. The segregation study on a triangular plane has not been reported elsewhere. The experimentation on triangular plane provides the information on segregation behavior of particles in converging flow conditions.

In part 'B' of the investigation, size segregation of multi-size sinter mixture flowing on a coke stock-line in the 1/17th model of No. 5 Blast Furnace, A.I.S. Port Kembla, was investigated. Sinter was charged using scaled P.W. top, on a coke stock-line in the model furnace. Radial distribution of harmonic mean size of the particulate samples was then investigated. A few experiments were conducted with the multi-ring charging pattern and with similar charging conditions as used in the 1 : 1 model of NO. 5 BF A.I.S. Port Kembla. The results compared well with the prototype but disagreed with the Kawasaki Steel Corporation Model.

As the information available to-date is insufficient to predict the general segregation model, single-ring charging of the sinter mixture was used for further experiments. In this investigation, the effect of different operating variables on the distribution of the harmonic mean size of samples across the furnace radius was investigated. The variables included in the investigation were flow rate of sinter mixture, rotation rate and angle of the chute, composition of the feed mixture and the height of fall of the mixture. The experiments of this part were designed using statistical methods of experimental design and the analysis of the results was also carried out statistically.

Vacuum suction technique was used for sampling the mixture. The 𝑥2 test, used to compare this technique with freezing technique showed no significant difference at 5% level.

The effect of the position of the sampling radius on the radial size distribution of the samples was found insignificant at 5% level.

The regression equation obtained for single-ring charging provides a quantitative effect of different operating variables on the radial size distribution of the mixture. This equation also provides the relative effect of different variables on the size segregation.

It must be stressed that this is only an initial investigation. Extensive work is still required to completely understand and predict the general segregation behavior of a particulate solids mixture during flow.

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