Every primary aluminum producer, remelter or recycler of aluminum is faced with the fact that dross is produced in the operation of melting and holding furnaces. A primary producer will encounter two to four (2 - 4 %) percent of dross, while for a remelt or recycling operation the dross formation can exceed ten percent (10 %) by weight of the processed material.
Dross is formed from the oxides and contaminants charged into the furnace and from the oxidation of the metal during the melting process and often also contains flux from the bath treatment. The dross has to be removed from the surface of the bath by skimming it into suitable boxes.
The dross and the liquid aluminum do not separate well and in the skimming operation which is often done manually or by forklift truck, a considerable amount of aluminum is pulled out of the furnace together with the dross. The material discharged into the dross boxes contains a very high percentage of metal, frequently in excess of sixty percent (> 60%) by weight.
If the dross is allowed to remain in the boxes or is dumped on the ground, the metal contained within the dross will continue to oxidize or even start to thermite. The result is that a dross which originally contained sixty percent (60 %) of metal will in a very short period of time deteriorate to only about thirty percent (30 %) metal content.
CETAG of Switzerland, a company specialized in providing Equipment and Engineering Services to the aluminum industry, has taken over and improved a Dross Processing Technology that will prevent the deterioration of the valuable aluminum content in the dross as well as separate and recover very efficiently a high percentage of the entrapped metal from the dross.
The equipment such as the Rotary Dross Cooling System are the main tools for an efficient conservation and recovery of the valuable aluminum.
By using the CETAG Dross Cooling System the over-all Metal Recovery can be increased by ten (10 %) to thirty (30 %) percent.