Experiment of direct smelting of niobium containing microalloy wear-resistant plate with niobium containing hot metal
Decarburization of molten iron is an important process of steelmaking, after the converter decarburization of molten iron silicon, vanadium, niobium and other alloying elements are all oxidized, can not be smelted into niobium or vanadium containing steel, so the niobium, vanadium and other elements in molten iron recovery and utilization, to go through the vanadium, niobium extraction process, so that these elements in molten iron oxidation into the slag, and then recovery of niobium and vanadium oxides from the slag. According to statistics, more than 75% of the world's niobium and more than 90% of vanadium are added to steel as alloying elements. Therefore, it is of great significance to simplify the process of recovering niobium or vanadium from niobium or vanadium containing hot metal and improve the economic benefit of smelting niobium or vanadium containing hot metal into niobium or vanadium containing steel.
The researchers studied the method of recovering niobium in niobium containing hot metal by decarburizing and preserving niobium as alloying element and smelting it directly into niobium containing microalloy wear-resistant plate. The experiment was carried out in a vacuum carbon tube furnace, the temperature of hot metal was 1500℃, the oxidant was Fe2O3, the vacuum was 10Pa, and the research of vacuum oxidation smelting with SiO2-CaO-Al2O3 system slag forming agent and slag free was carried out respectively.
The results show that the micro-alloy wear-resistant plate can not decarburize and preserve niobium by simultaneously oxidizing silicon, niobium and carbon in Fe2O3 hot metal without slag. When slagging agent is added, the lower the basicity of slagging agent, the lower the silicon oxidation amount in hot metal, the higher the carbon oxidation amount, the lowest carbon mass fraction decreases to 0.032%, the lowest niobium mass fraction decreases from 0.09% to 0.082%. The higher the alkalinity, the higher the oxidation amount of silicon and niobium in hot metal; Vacuum oxidation smelting can promote carbon oxidation, reduce silicon oxidation, and restrain niobium oxidation. The experiment of direct smelting of niobium from molten iron to niobium containing steel was successfully carried out in a 50kg vacuum induction furnace, which provides a new method for recovering niobium from molten iron and a test basis for industrial direct smelting of niobium containing steel.
