OREANDA-NEWS. On 26 January 2009 UC RUSAL, the world’s largest aluminium and alumina producer, announced that it had completed the conversion of one potroom at its Krasnoyarsk Aluminium Smelter (KrAZ) to the colloidal anode paste technology. The economic effect from this innovation at one potroom alone can be up to USD 1 mln annually.

The aluminium production technology using colloidal anode paste is one of the key parameters for the development of the ‘clean’ Soederberg cell. The project launched by the Engineering and Construction Division of RUSAL in 2006 led to several modifications of the Soederberg cell in an effort to bring its performance parameters comparable to those of the pre-bake anode technology in terms of the production efficiency, and helped reduce the environmental impact and optimised the consumption rates for major raw materials.

In 2007, KrAZ set up a pilot carbon area for the production of colloidal anode paste. The smelting process, which uses this type of paste, initially proved its success on twenty smelter’s cells, but already by the end of 2010 this new technology will be proliferated to another four potrooms at KrAZ.

The conversion into the colloidal anode technology is part of the second stage of the environmental modernisation at KrAZ. In parallel with the engineering works on the new cell, which can use colloidal anode paste, the researchers suggested several technical adjustments to reduce the adverse environmental impact. A major achievement among these improvements is that the new cells will help in capturing over 95% of hazardous emissions. And once the conversion is completed at KrAZ, the emissions into the atmosphere will drop considerably.

KrAZ will lower its consumption of pitch by 17%, which will result in a considerable reduction of tar emissions into the atmosphere. After the adoption of the unique technology, hydrofluoric emissions will go down from 0.7 to 0.24 kg, fluorine emissions from 1.62 to 0.6 kg, CO2 emissions from 78.9 to 53.5 kg, benzo(a)pyrene emissions from 0.002 to 0.001 kg per tonne of aluminium.

The Soederberg cell with colloidal anode paste will also be introduced at other RUSAL’s aluminium operations in Bratsk, Irkutsk, Novokuznetsk and Volgograd.