Use of Russian niobium raw materials with a high phosphorus content for complex ferroalloys

Most of the industrial and potentially industrial types of niobium deposits in Russia are characterized by high content of phosphorus. The use of such raw materials when enriching by known methods leads to additional costs and losses of niobium. In this regard, it becomes impossible to obtain standard grades of ferroniobium according to the existing technological schemes. The paper considers the possibility of obtaining complex ferroalloys from Russian niobium raw materials with an increased phosphorus content based on alloys of the Fe-Al-P and Fe-Si-Al-P systems at a variable concentration of aluminum (10-20%) and silicon (10-30%). The process of sublimation of phosphorus from melts is studied in the temperature range of 1400-1700 °C. It's shown that aluminum does not affect in the studied alloys, and silicon contributes to the sublimation of phosphorus. With a significant phosphorus content in the alloy (10-18%), the presence of 20% silicon in the Fe-Si-Al-P system leads to the sublimation of phosphorus up to 20%. It's also shown that an increase in temperature affects an increase in the activity of phosphorus and its sublimation. The intensity of phosphorus sublimation increases especially at temperatures ≥ 1600 ° C.