| Emulsification process caused by mechanical agitation of the molten magnesium and NaCl(50 ㏖.%)-KCl salt was employed to prepare salt coated magnesium powders (SCMPs) used as a hot metal desulphurizer. Spherical magnesium particles were observed to be entrapped in the salt when the two liquids kept at 700-820℃ were agitated at 1,000-2,500 rpm and quenched. The friable salt was then easily removed by pulverizing and sieving, so that spherical SCMPs could be prepared. This indicates that molten magnesium droplets are dispersed in the molten salt. The degree of dispersion increases with increasing temperature and agitation time. Process efficiency was evaluated by recovery. Recovery means the portion of the magnesium in SCMPs with size of 300-2,500 ㎛ to the input magnesium, because SCMPs in this size range can be directly used as a hot metal desulphurizer. The recovery decreases with increasing temperature and agitation speed. The maximum recovery of 93.4% was achieved when the two liquids kept at 750℃ were agitated at 1,000 rpm for 15 minutes. An novel phenomenon was also observed that the average particle size of SCMPs remained unchanged for about 25 minutes after cease of agitation. Strong stability of a magnesium-salt emulsion makes the emulsification process suitable for practical production of SCMPs. |
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