The Study Of Extracting Niobium From Low Silicon Nb-bearing Hot Metal

Niobium is an important alloying elements, The steel that mixed mircrocale Niobiumcan improve its intensity and touguness. The demand of niobium will continue to increasewith the development of the iron and steel industry. The main direction of development ofthe World Steel is micro-alloy steel. Baotou Bayan Obo ore contains more than95%of thecountry’s reserves of niobium resources.The development and utilization of it has importantindustrial value, But because of its low grade niobium mineral resources and special symbioticrelationship cause the difficulties of smelting of niobium. At the same time, Baotou steelwater contains0.015%to0.02%niobium, in order to be able to take full advantage of theniobium resources, we proposed micro-alloying technology, the research of extractingniobium from low silicon Nb-bearing hot metal and direct alloying is one of the project’scontent.the process of smelting low silicon niobium semi-steel by bottom blowing oxygen inthe medium frequency induction furnace was advanced, the appropriate desiliconizationconservation niobium experiment operating conditions are determined.Fe3O4and carbondioxide are used as oxidant in order to selective oxidation extract niobium form the lowsilicon niobium-containing molten iron. niobium phosphorus ratio greater than20niobiumslag.After a series sudy, the following conclusions are obtaioned:（1） In the experiment of desiliconization and conservation of Nb, the reactiontemperature is1350℃, the basicity of the slag is between1.5to2.3, the oxygen flow rateis1m3/h, and the desilication limit is0.15%, it is achieve to achieve desiliconization andconservation of Nb. The high basicity slag reduce desilication limit, but also repression theremoval of Mn.（2） Extracting niobium with carbon dioxide experiment indicates: in the mediumfrequency induction furnace, CO₂is an effective oxidant of extractiong niobium.1350℃ is suitable reaction temperature, the lower concentration of silicon,the more conducive tothe niobium oxide, to the reaction end, niobium oxide rate can reach82%, the niobium slagcontants4.92%Nb₂O₅, and Nb/P reach49.1.（3） In the extracting niobium with solid oxygen experiments: the optinum conditionswere below: Fe3O4added to the amount of5%¹0%; temperature range1300℃¹350℃.It is demand that control the silicon content in low silicon niobium-containing hot metal ataround0.12%, the initial niobium content leads to a higher degree of niobium oxide,niobium oxide rate can reach95%. Niobium slag containing iron beads cause niobium slagcontaining phosphorus, slag contants0.61%Nb₂O₅, niobium phosphorus ratio is2.54.