Influence of injection process parameters on granulation effect of blast furnace slag to beads
The traditional blast-furnace slag treatment method is water quenching method,but there are many draw-backs of the method,such as,a large amount of waste heat resources are not effectively recycled,water resources are wasted;H2S,SO2 and other pollutants produced in the cooling process pollute the environment.In order to over-come the disadvantages brought by the traditional method,dry granulation method is used to break and granulate the blast furnace slag.On the basis of the traditional air quenching process,water atomization is added to strengthen to break the blast furnace slag,so as to significantly improve the granulation rate and enhance the high-added value of slag.The effects of different injection process parameters(different gas quenching pressures,different nozzle struc-tures,different air-water ratios)on the granulation effect(particle size distribution,bead formation rate,sphericity)of blast furnace slag are studied,and the best injection process parameters are obtained.The results show that the particle size distribution is basically normal,and the particle size is basically concentrated in the range of 0.40-2.36 mm under different process parameters(different air quenching pressures,different nozzle structures,different air-water ratios).At the same time,increase the air quenching pressure and choose the nine-hole nozzle with evenly mixed air-water is more conducive to the slag crushing and granulation,which can obviously enhance the beads for-mation rates and the highest beads formation rate is 85.3％.However,with the increase of pressure,the beads for-mation rates are not a blind increase.the beads formation rates basically remains unchanged more than 0.3 MPa.The greater the pressure,the more smaller the slag beads particle size,the higher the transparency,and the more regular the slag beads shape.Lavar nozzle with directly injecting air and T-type nozzle with injecting air firstly and then mixed with water have poorer granulation effect.When the water amount is less than the air amount,the beads formation rate gradually increases with the increase of the water amount.While when the water amount is greater than the air amount,the beads formation rate decreases slightly with a slow decreasing trend,which providing theo-retical reference for the high value-added utilization of blast-furnace slag.
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