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Usable slag and cleaner steel by vanadium extraction
Vanadium in Swedish LD slag is worth more than one billion SEK. By extracting vanadium from the steel manufacturing process, the steel becomes cleaner and you get slag that can be used externally. In addition, you get potential environmental benefits of more than 1 million tonne CO2 and 2 TWh each year for the Swedish steel industry.
LD slag is generated during the production of steel in a so-called LD converter where pig iron is converted to steel through oxidation of converted coal. Since pig iron contains approximately 0.3 % vanadium, this also is oxidised to LD slag.
Limited use for slag
The slag then contains approximately 2.5 % vanadium. That is why the areas for using LD are extremely limited. Today approximately 50 % of LD slag is returned to blast furnaces while the rest is sent to the landfill.
In carrying out the VILD project, Swerim has together with SSAB, LKAB, SSAB Merox and Finnish Ruukki developed a number of different process concepts in which products containing vanadium may be produced (and the vanadium is extracted).
Slag becomes resource
The concept has been tested on both pilot and operation scale levels. Kim Kärsrud, environmental director at SSAB, describes the project:
“What is most important for industry is undoubtedly that the slag is worth something when the vanadium is removed. It is of course also positive if we also become a vanadium supplier. During this journey we have not just learned more about vanadium in slag, we also learned lots about how it acts in the outdoors. Now the project has gone on for so long that we are probably world champion on vanadium.”
There is considerable international interest in the project. Swerim is also testing the usefulness of metal products containing vanadium.