Method of Dry Granulation and Solidification of Molten Blast Furnace Slag

Abstract

In order to develop the heat recovery process of the retained heat in molten blast furnace slag, several methods to granulate the molten slag and solidification of the molten slag granules were investigated. The developed method of dry granulation by collision of molten slag with a plate has several advantages as (1) low power consumption for granulation, (2) low heat loss during granulation, and (3) relatively short range of dispersion of the slag granules.A slag granule of 5 mm in diameter kept in the air flow is cooled at a rate of about 100 °C/sec in high temperature range and solidifies at a temperature of about 850°C. This means that it takes about 5 seconds to solidify a molten slag granule at a temperature of 1350°C. To accelerate the cooling rate and avoid mutual adhesion of slag granules, it is found to be effective to cool and solidify the slag granules by mixing with powder used as a cooling medium.