UC RUSAL, the world’s largest aluminium and alumina producer, has completed the conversion of one potroom at its Krasnoyarsk Aluminium Smelter (KrAZ) to the colloidal anode paste technology and says “the economic effect from this innovation at one potroom alone can be up to $1 million annually.” Using colloidal anode paste is one of the key parameters for the development of the ‘clean’ Soederberg cell. The project launched by Rusal’s 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 pre-bake anode technology in terms of 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 20 smelter cells, but already by the end of 2010 this new technology will be extended to another four potrooms at KrAZ.
The conversion to colloidal anode technology is part of the second stage of 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/t 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.
KrAZ was commissioned in 1964 and today is the world’s second largest aluminium facility in terms of production output, which accounts for 27% of the aluminium production in Russia and for 3% of the entire annual global output. In 2008 KrAZ produced 1 Mt of aluminium (which was its first-time achievement). KrAZ is certified to ISO 9001 and ISO 14001 standards.
