Swedish iron ore contains about 0.1%V. The vanadium is reduced to the hot metal in a blast furnace and oxidised to the slag in a converter. The high V-content, up to 5% V, leads to a very limited external application of the steel slag in Sweden. Since 2004, MISTRA - the Swedish Foundation for Strategic Environmental Research has together with the steel and mining industry in Sweden and Finland initiated and supported a long term project aiming at efficient recovery of vanadium in the slag, and at the same time a useful slag product with low V-content. The proposed concept consists of a reduction step and a phosphorus removal step. This paper will highlight some of the results with focus on the various metallurgical reactors used for slag reduction, including results from recently performed pilot trials using a DC furnace for co-treatment of metallurgical slags and other wastes.