Potential for obtaining and applying complex niobium ferroalloys

Abstract

This paper provides information regarding the application of niobium in industry and the scale of its production in the world and the Russian Federation. Most of the niobium deposits in Russia consist of pyrochlore, apatitepyrochlore and columbitepyrochlore types of ores. They contain a significant amount of phosphorus. Therefore, all enrichment schemes for these ores contain a dephosphorization stage which increases the price of the product and reduces the degree of niobium extraction. The paper explores the possibility of improving the end-to-end production scheme: niobium ore – beneficiation – niobium ferroalloy. The bulk of ferroniobium is intended for steel microalloying and can be replaced by complex ferroalloys with a reduced niobium content. The paper considers the issues of obtaining complex niobium ferroalloys from a rough concentrate with a weak content of niobium. It has been established that the addition of 25 – 40 % of silicon or 12 – 30 % of aliminum to the twocomponent metal system Fe – Nb causes the transfer of niobium ferroalloys (15 – 20 % Nb) from the refractory category to lowmelting materials. The crystallization temperatures are less than 1400 °C. The substantiation of using a complex niobium ferroalloy instead of ferroniobium is given. This alloy has reduced niobium content and increased silicon or aluminum content. Higher service characteristics of the complex ferroalloy are noted in comparison with ferroniobium (temperature of the initiation of crystallization and density). They indicate an increased assimilation of niobium when using a complex ferroalloy for steel microalloying. The paper presents data on the possibility of dephosphorization of niobium concentrates in the process of pyrometallurgical production of a complex ferroalloy. An improved scheme for the production of niobiumcontaining ferroalloys is proposed. This consists of the use of niobium concentrate for melting the intermediate ferroalloy containing a reduced concentration of niobium oxides and an increased concentration of silicon (aluminum). This ferroalloy can be used effectively for steel microalloying with niobium.