| A 1/12 scale tank was constructed to physically simulate the metallurgical skimming process in order to gain a better insight of the skimming of fluid slag from copper anode furnaces. 1-decanol and water were used to represent the slag and the underlying liquid metal respectively. It was observed that slag skimming was comprised of two steps, a transportation step to carry slag to the skimming lip, and a removal step to move the slag across the lip. The efficiency of the transportation by bath surface circulation was strongly affected by the method of creation of the surface movement. Submerged gas injection failed to carry slag to the lip effectively because of the uncontrollable circulation pattern generated on the bath surface. On the other hand, three impinging gas jets in glancing contact with the bath surface were able to carry slag to the lip effectively. The Re of the jets (I.D. 0.01m) inclined 50° to the horizontal was 6100. The jet configuration was two of the jets were placed close and parallel to the rear wall of the model and faced each other. The third jet was parallel to the model short axis and was directed at the skimming mouth. With the same amount of time, 70% of the slag originally charged to the tank was skimmed with the assistance from the impinging gas jets in comparison to 20% when no jet was used. Detailed analysis of the skimming process revealed that the underlying liquid bath level continuously decreased as the slag was skimmed and resulted in continuous reduction of the skimming rate. In order to compensate the reduction of skimming rate due to bath level reduction, a control strategy was proposed for rotating the furnace continuously to maximize the skimming effectively. |
