Life cycle assessment of ferroniobium and niobium oxides: Quantifying the reduction of environmental impacts as a result of production process improvements - ScienceDirect
Life cycle assessment of ferroniobium and niobium oxides: Quantifying the reduction of environmental impacts as a result of production process improvements
According to the European Union (EU), niobium (Nb) is considered a critical raw material, not only due to its supply risk but also due to its economic importance to the EU and limited substitutability by other raw materials (European Commission, 2020a). The production of Nb is concentrated in Brazil (92% of the global demand), followed by Canada (6%) and the remaining 2% is distributed amongst Russia, the Democratic Republic of Congo, Rwanda, Nigeria, Burundi, China, Ethiopia, Mozambique and Uganda (European Commission, 2020b), even though many deposits are known in other countries (British Geological Survey, 2011). Currently, the global end uses of Nb are mostly in the form of ferroniobium (FeNb), which in turn is used in steel for the automotive industry (28%), construction (32%), stainless steel (14%) and pipelines for oil and gas (17%). The remaining (9%) is used in chemical applications, mostly in the form of high purity niobium oxide (HP Nb₂O₅) or as pure metal, being the final applications piezoelectric materials, glass and lenses, capacitors, ceramics, carbides and superconducting magnets, such as the one found in magnetic resonance imaging (European Commission, 2020b). The use of niobium alloys, produced with pure Nb, has achieved positive results in the chemical industry, due to its corrosion resistance and mechanical properties (Aimone and Yang, 2018). Recently, new uses of Nb have been investigated with positive prospects for the transition towards low-carbon energy. The use of Nb in wind turbines is already a reality, whereas the development of Nb-based rechargeable batteries, which has been investigated already for a few years (Griffith et al., 2018; Wen et al., 2015; Yabuuchi et al., 2015), has advanced. Besides battery materials, solar panels and intelligent glass are also under development, the latter allowing to filter sunlight radiation and to control the amount of light and heat entering in a building (CBMM, 2021; European Commission, 2020c).
It is clear that Nb is an essential raw material for economic and technological development worldwide, also with great potential to contribute to achieving an environmentally sustainable society via its final applications, such as the ones used for renewable energy and battery technologies, but some attention must be also given to the stages upstream of its final application. The production of Nb and its semi-finished products starts with the extraction of niobium oxide (Nb₂O₅) from Nb-containing ores. The concentration of Nb₂O₅ in the different mineral deposits worldwide is reported to range between 0.0095 and 2.5%, depending on the mineralogy of the region and the weathering conditions. The higher the weathered degree, the higher the Nb content (British Geological Survey, 2011). In terms of production, the mineralogy and concentration in the mineral deposit affect the needed resources to extract and concentrate the Nb₂O₅ into a Nb concentrate that will be processed to produce FeNb, HP Nb₂O₅ or pure Nb. These distinct products and the source of Nb for their production will affect the level and the type of emissions generated during the production steps