Preferential Removal of Si, Nb and Mn from Pig Iron Containing Nb

The recovery of Nb and Mn for mineral resources, P for a fertilizer, and the production of iron and steel of good quality from a pig iron containing Nb in China have been studied. This report describes the first preferential removal of Si over Nb, and the preferential removal of Nb over Mn, or, the preferential removal of Mn over Nb from the pig iron after desiliconization, bearing in mind a multi-stage continuous refining process, in order to increase the content of an aimed element in the slag recovered. The oxidation rates of elements in pig iron of 1 kg in a graphite crucible were measured by adding Fe2O3, CaO, Na2CO3, and B2O3 onto the bath. The effects of temperature, oxygen feeding rate (Fe2O3 g/5 min), and weight of those reagents upon the oxidation rates were discussed. The results obtained are as follows; (1) The preferential removal of Si over Nb was accomplished with an optimum amount of Fe2O3 at high temperatures. In this case, the reduction of Nb2O5 in slag formed by C in molten pig iron was important. (2) The preferential removal of Nb over Mn from the pig iron after desiliconization was achieved with a basic flux, CaO or Na2CO3. (3) The preferential removal of Mn over Nb from the pig iron after desiliconization was realized with an acid flux, B2O3.