Slag skimming is a necessary step in the pyrometallurgical production of copper. However, skimming practice today is more a matter of operator "intuition" than the application of science. As a result, poor skimming often occurs in conventional copper smelting operations and the consequent slag left behind from one part of the rocess cycle entering the next part may cause significant performance losses if the residual slag interferes with the chemistry of the processing in the subsequent step. A physical modeling exercise using water and 1-decanol in a 1/12 scale tank was performed to visualize the slag skimming process from horizontal rotary furnaces and to explore the enhancement of skimming effectiveness by using impinging gas jets in glancing contact with the slag layers. It was observed that the underlying liquid surface circulation created by the gas jets would carry the slag towards the skimmingm mouth. This approach to slag flow control was considered much more effective and less generally damaging than the use of submerged gas injection. It is suggested that profiling the skimming lip to provide more vertical surface for the flag to wet could enhance the rate of slag skimming especially when there is little slag remaining in the vessel.
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