Study on Alkali Fusion Process of V-Ti Magnetite Concentrate at Lower Temperature

In order to realize the smelting of V-Ti magnetite concentrate at lower temperature,the direct reduction-smelting separation process was studied by coal-based direct reduction technique with NaOH as the alkali fusion agent.Effects of NaOH addition on metallization rate and smelting separation of V-Ti magnetite concentrate were investigated and the phase compositions of the metallized pellets and slag were observed by XRD.The melting points of slags of Na₂O-SiO₂-TiO₂-Al₂O₃-CaO with different Na/Si ratios were calculated by Factsage software.The results show that a higher Na/Si ratio corresponds to a lower melting point of the slag.NaOH can improve the direct reduction and smelting separation performance of V-Ti magnetite concentrate significantly.With increase in Na/Si ratio,the metallization ratio of pellets increases,but the increase amplitude decreases gradually.At a temperature of 1 150 ℃ for 30 min,Na/Si=5.0 and C/O=1.4,the metallization rate of metallized pellet can reach 93.17%.When Na/Si＞4.0,the granalated iron obtained by melting indicates that the flatness is good,and there is no small-sized gramular iron dispersed in the molten titaniam slag.Titanium,aluminum and silicon in the slag obtained by the method mainly exist as sodium salts.The addition of NaOH can realize smelting separation at lower temperatures and promote the separation between slag and metal.