Smelter Technology Types
Bauxite Alumina Aluminium Smelter Technology 

There are two main types of aluminium smelting technology - Söderburg and Pre-bake. The principal difference between the two is the type of anode used. 
Söderburg technology uses a continuous anode which is delivered to the cell (pot) in the form of a paste, and which bakes in the cell itself. 
Pre-bake technology uses multiple anodes in each cell which are pre-baked in a separate facility and attached to "rods" that suspend the anodes in the cell. New anodes are exchanged for spent anodes - "anode butts" - being recycled into new anodes The newest primary aluminium production facilities use a variant on pre-bake technology called Centre Worked Pre-bake Technology (CWPB). This technology provides for computer controlled precise alumina feeding through the use of multiple "point feeders" and other automated controls. A key feature of CWPB plants is the enclosed nature of the process. Fugitive emissions from these cells are very low, less than 2% of the generated emissions. The balance of the emissions is collected inside the cell itself and carried away to very efficient scrubbing systems (removing particulates and gases) that return the collected material to the cells. Computer technology controls the process down to the finest detail, which means that occurrence of the anode effect - the condition which causes small quantities of PFC's to be produced - can be minimised. All new plant and most expansion of existing plant are based on pre-bake technology.

Environmental Issues
Environmental Challenges 

While significant progress has been made in improving its environmental performance, Söederburg technology is gradually being replaced with pre-bake technology. 
Breakdown of technology types - IPAI Members - 1996 Horizontal Stud Söderburg10.3%
Vertical Stud Söderburg19.4%
Side Worked Pre-bake9.8%
Centre Worked Pre-bake60.3%

Many IPAI Members carry out continuous research into process improvements, particularly energy efficiency and emission levels. Some IPAI Members market their smelting technology. 
Aluminium Maps 

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