Niobium Ore Research Articles

Recovery of niobium and titanium from low-grade niobium ores and the evaluation of Fe5Si3 alloy by-product as oxygen evolution reaction electrocatalysts

A low-grade ore containing 4 % niobium and 7 % titanium has been extracted from Bayan Obo tailing, but its potential has not been fully utilized. This study aims to recover the niobium and titanium elements from this low-grade ores in the form of their carbides. The process involves reducing niobium and titanium to (Nb,Ti)C through a carbothermal process. During this process, iron and silicon are also reduced to Fe-Si intermetallic compounds, allowing (Nb,Ti)C to diffuse into them. Subsequently, selective electrochemical oxidation is used to separate (Nb,Ti)C from the Fe-Si intermetallic compounds in an aqueous ferrous sulfate solution. The Fe-Si intermetallic compounds are first oxidized to the Fe3Si phase, and then to the Fe5Si3 phase in the solution with pH 0.35. The (Nb,Ti)C/matrix interfaces are identified as the preferred site of electrochemical pitting corrosion. By exploiting the electrochemical oxidation reaction of iron in the matrix, (Nb,Ti)C powders are separated along these interfaces. The by-products of this process are FeSi alloys, which are evaluated for their electrocatalytic properties in oxygen evolution reactions. It is found that the Fe5Si3 alloy by-product exhibits good electrocatalytic activity and kinetics in the oxygen evolution reaction, demonstrating its potential for practical applications.

Electrokinetic study of pyrochlore in the presence of calcium and magnesium electrolytes in the context of water reuse

This paper aims to present an adequate methodology for pyrochlore from flotation process sample to be used in fundamentals surface properties studies based on zeta potential measurements under Ca and Mg electrolytes in chlorides and sulfate media. A niobium ore concentrate with small amount of fine particles (−38 µm < 2.5%), composed by 61.8% (Nb2O5), 16.5% (CaO), 7.19% (TiO2), and 6.30% (Na2O), being pyrochlore (92.8%) the Nb-bearing mineral was used. The association of acid leaching (HCl 0.1 mol/L, 70 °C, 120 min, 20 g/L and 300 rpm) and heat treatment (300 °C, 120 min and 5 g/crucible) reduced the sample's flotability by 94% which was suitable for fundamental studies. Ca and Mg ions modified the zeta potential curve of the pyrochlore without causing any changes in the pHPIE, which occurs at pH 3.1. Ca(OH)2 precipitation was not evidenced in the system containing calcium ions. Thermodynamic simulation predicted its precipitation above pH 12.3 which is outside of the range of pH studied (2.0 to 12.0). However, Mg(OH)2 precipitation associated to the formation of metal hydroxy complexes predicted by PHREEQC (version 3.7.3, llnl.dat database) contributed to the reversal in the zeta potential of the sample. The anion supporting the metallic cations also contributed to the zeta potential alteration mainly due to the ionic strength modification associated to sulfate and chloride anion charges. The alternation of chloride and sulfate sources for [Ca + Mg] system did not affect the zeta potential curves.

Main minerals of the Araxá alkali-carbonatite complex, Minas Gerais State, Brazil

The Araxá alkali-carbonatitic complex is a significant source of niobium and phosphate and accounts for approximately 75% of global niobium production. The complex contains magmatic niobium ore minerals, such as natrium-pyrochlore and calcium-pyrochlore, and hydrothermal niobium ore minerals in the form of kenopyrochlore and natrium-pyrochlore. The magmatic micas in the complex are tetraferriphlogopites that exhibit Mg-rich cores surrounded by one or two rims of tetraferriphlogopites formed by hydrothermal alteration. These rims have lower IVAl and Mg apfu (atom per formula unit) values but higher IVFe3+ and Fe2+ contents than the original phlogopite. Microphlogopitite dikes that formed during several episodes of magmatism between 83.48 and 77.4 Ma contain tetraferriphlogopites, phlogopite, eastonite, biotite, and annite-siderophyllite. These micas exhibit variations in Mg2+ and Fe2+ concentrations owing to the magmatic differentiation and subsequent hydrothermal alteration, resulting in rims with higher Mg and lower Fe2+ concentrations than the mica core. The Araxá complex also contains magmatic magnetite that has been further altered by hydrothermal processes, resulting in the formation of ilmenite and the oxidation and crystallization of titaniferous hematite. Magnetite within the microphlogopitites displays variations in the concentrations of Fe3+ and Ti, likely owing to the timing of the intrusion of the microphlogopitites into the Araxá complex. The degree of oxidation of the oxidized ilmenite of the Araxá complex varies based on the intrusions, which occurred before or during hydrothermal activity. Apatite is concentrated in carbonatites, which form a ring around the core of the complex, and disseminated in phlogopite-rich rocks hosting norsethite carbonatite veins in the center of the complex. The apatite in the core rocks exhibits complex zonation with unexpected changes in Ca, P, and Sr concentrations. Apatite in the carbonatite ring was generated during the differentiation of the carbonatite magma, whereas that in the core rocks exsolved from the phosphorus-saturated carbonatite magma (in press). The carbonate minerals dolomite, norsethite, and calcite exhibit compositions grouped around their end-members, suggesting that they formed during different stages of magmatic source differentiation. Strontium differentiation occurs in the magmas corresponding to each endmember, and carbocernaite is exsolved from the Sr-saturated crystals, thus forming micro-inclusions in some carbonate crystals that have been displaced by late-magmatic hydrothermal fluids.

Mineralogical study on the distribution regularity of niobium in various types of ores in the giant Bayan Obo Fe-REE-Nb deposit

The Bayan Obo Fe-REE-Nb deposit is the largest rare earth deposit in the world, which also contains huge amounts of niobium resources, hosting 83% of industrial reserves in China. The previous researches focused on the REE mineralogy, mineralization age and REE source, whereas only a few studies paid attention to the genesis of Nb mineralization. The REE and Nb might present systematic mineralization difference as the degree of REE and Nb mineralization is distinct in different types of ores in host dolomite. Many complicated factors such as low grade, fine-grained dissemination and complex mineral composition are the main obstacles to hinder the effective utilization of Nb. In this study, a variety of niobium-bearing minerals have been identified, including aeschynite, fergusonite, columbite, pyrochlore, fersmite, baotite, and ilmenorutile. The distribution regularity of niobium in various types of ores in the giant Bayan Obo Fe-REE-Nb deposit is asserted. In massive Nb-REE-Fe ore and dolomite-type Nb-REE-(Fe) ore, niobium-bearing minerals are represented by columbite, while niobium mineralization in aegirine-type Nb-REE-Fe ore is characterized by pyrochlore and aeschynite. The major niobium-bearing mineral in the riebeckite -type Nb-REE-(Fe) ore and fluorite-type (banded) Nb-REE-Fe ore is aeschynite, and major niobium-bearing mineral in biotite-type Nb-REE-Fe ore and diopside-type niobium ore is fergusonite. The μ-XRF results and SEM observations display that columbite contains dolomite, magnetite and monazite inclusions and show obvious genetic links with apatite. Columbite, apatite and magnetite in massive Fe-REE-Nb ore and dolomite-type Nb-REE-(Fe) ore occur at same mineral generation, both having magmatic origins. Pyrochlore from aegirine-type Fe-REE-Nb ore also showsclose genetic relationship with apatite, which is formed by fractional crystallization during the magmatic stage of carbonatite. Aeschynite in fluorite-type (banded) Fe-REE-Nb ore, riebeckite-type Nb-REE-(Fe) ore, and fergusonite in biotite-type Fe-REE-Nb ore and diopside-type niobium ore are large in grain size and have hydrothermal origins. Moreover, intensive Nb mineralization in a series of ores related to fluoritization and alkali-metasomatism demonstrates the critical role of hydrothermal process in niobium enrichment in the Bayan Obo deposit. Fluid-rock interaction leads to the generation of alteration minerals, such as fluorite, biotite and aegirine, and contributes to a slash of K, Na and/or F in hydrothermal fluids, facilitating precipitation of niobium-bearing minerals. By using scanning electron microscope (SEM), X-ray energy dispersive analysis (EDS), Micro-XRF spectral analysis (μ-XRF) and TESCAN Intergrated Mineral Analysis (TIMA), detailed mineralogical study on niobium occurrence and typical niobium mineral compositions in various types of Fe-REE-Nb ores was conducted to provide an important reference for mineral processing and niobium prospecting and give a deeper understanding of the niobium anomalous enrichment mechanism of the Bayan Obo Fe-REE-Nb deposit.

Feasibility of High-Density and Non-Segregable Niobium Ore Tailings

Tailings disposal in the form of diluted slurries has a tendency for particle size segregation, where coarse particles settle near the discharge point, and finer particles are carried by the water flux to more distant regions. This causes a loss of reservoir capacity due to voids between the coarser particles and increased water content in the deposit. This work aimed to evaluate the feasibility of reaching non-segregable high-density slurries with fine tailings from the niobium oreflotation process and measure its disposal parameters. The innovation is to achieve increased solids percentage in the settled deposit and to avoid particle size segregation along the slurry path with niobium tailings. The study involved physical, chemical, and mineralogical characterization and semi-pilot thickening tests to produce enough volume of underflow with different bed heights and solids flux rates. Slump, rheology, and flume tests were performed to evaluate underflow disposal characteristics. The results indicated that the thickener bed height did not significantly influence the underflow solids content, yield stress, or slump. The solids flux rate, on the other side, had a greater influence—the higher it was, the lower the solids content, yield stress, and disposal angle, along with a higher slump. In flume tests, a high density of non-segregable tailings slurry was achieved with 1.96 t/m3, corresponding to an underflow with 66.8% solids, 43.9 Pa of yield stress with 0.5 (t/h)/m2, and 0.5 m of bed height.

Niobium, Critical Metal, and Progeny of the Mantle

Abstract Niobium is a critical metal in high demand because of technological advances and the supply risk created by the fact that over 90% of its production is by a single country (Brazil). In this paper, we review the geology of the deposits that are currently being mined and other potentially economic deposits as well as develop models for their genesis. With the exception of the Lovozero deposit (Russia), which is hosted by a layered silica-undersaturated alkaline igneous complex, all the deposits that are currently being mined for niobium are hosted by carbonatites, and most of the deposits with economic potential are also hosted by these rocks. Niobium owes its concentration in carbonatites and alkaline silicate rocks to its highly incompatible nature and the small degree of partial melting of the mantle required to generate the corresponding magmas. The primary control on the concentration of niobium to economic levels in alkaline silicate magmas is fractional crystallization, partly prior to but mainly after emplacement. In the case of silica-undersaturated magmas, the final residue saturates in minerals like eudialyte and loparite to form niobium-rich horizons in the layered complexes that crystallize from these magmas. The final residue, in the case of silica-saturated magmas, crystallizes the pegmatites that are the hosts to the economic niobium mineralization, which commonly takes the form of pyrochlore. In contrast, carbonatitic magmas undergo little to no fractional crystallization prior to emplacement. Moreover, fractional crystallization on emplacement has minimal impact on the concentration of niobium to economic levels. Instead, we propose that the metasomatic interaction of the carbonatitic magmas with their hosts to form rocks like phlogopitite (glimmerite) consumes much of the magma, leaving behind a phoscoritic residue from which pyrochlore crystallizes in amounts sufficient to form economic deposits. Although many niobium deposits display evidence of intense hydrothermal alteration, during which there can be major changes in the niobium mineralogy, the extremely low solubility of niobium in aqueous fluids at elevated temperature precludes significant mobilization and, thus, enrichment of the metal by hydrothermal fluids. However, weathering of carbonatite-hosted niobium deposits leads to supergene enrichment (due largely to the dissolution of the carbonate minerals) that can double the niobium grade and make subeconomic deposits economic. Pyrochlore is the principal niobium mineral in these laterite-hosted deposits, although its composition differs considerably from that in the primary mineralization. This paper evaluates the processes that appear to be responsible for the genesis of niobium ores and provides a framework that we hope will guide future in-depth studies of niobium deposits and lead to more effective strategies for their successful exploration and exploitation.

Mapping critical mineral resources using airborne geophysics, 3D joint inversion and geology differentiation: A case study of a buried niobium deposit in the Elk Creek carbonatite, Nebraska, USA

ABSTRACTCritical minerals are an integral part of the energy transition because of their important and, sometimes irreplaceable, uses in solar panels, wind turbines, electrical vehicles, etc. Mapping critical mineral resources is, therefore, essential to achieving the net‐zero emission goal by 2050. We present a case study on using airborne geophysical data, borehole and physical property measurements to characterize the Elk Creek Carbonatite complex located in the southeast of Nebraska, USA. It hosts the largest known niobium deposit in the United States and contains a high level of rare earth element mineralization. Our goal is to develop a better understanding of the three‐dimensional structures and composition of the Elk Creek Carbonatite complex as well as its critical mineral resource potential. We performed three‐dimensional joint inversion of the airborne gravity gradiometry and magnetic data to produce structurally similar density and susceptibility models. We carried out geology differentiation, a process of classifying recovered physical property values into distinct units, and obtained a three‐dimensional quasi‐geology model for the Elk Creek Carbonatite complex. We identified 12 geologic units, each of which is characterized by a distinct range of physical property values. Our quasi‐geology model, especially Units 9 and 11, shows a remarkable consistency with the borehole assay measurements. Unit 9 is spatially coincident with the known niobium ore zone. Unit 11 represents a significant volume of highly dense and magnetic materials below the deepest boreholes. These materials are likely associated with unexplored niobium mineralization. Our study demonstrates the added value of three‐dimensional geophysical joint inversions and geology differentiation in the context of critical mineral exploration under a thick sedimentary overburden.

Viscosity of niobium oxide systems for production of complex ferroalloys

The relevance of the development of modern technological solutions for the processing of niobium ore materials used for the production of complex ferroalloys of domestic deposits is shown. The need to develop new technological processes of processing is caused by the fact that when switching to new types of niobium concentrates, the chemical and phase compositions of the starting materials change, and, consequently, this leads to a change in the composition and properties of the melting products (both metallic and oxide). Using an electrovibration viscometer, the temperature dependences of viscosity were studied and the crystallization temperatures of oxide melts of the Nb2O5 – SiO2 – CaO – TiO2 – Al2O3 system were calculated. The compositions of the studied samples correspond to phosphorless niobium slags, which can be obtained by carbothermic method from rough concentrates. The samples were obtained by fusing oxide materials in a high-temperature laboratory electric furnace. On the basis of the obtained data, graphical dependences of viscosity – temperature are constructed. It was experimentally established that oxide melts containing 15 – 26 % Nb2O5 are more “long” (having a wide crystallization range) and unfavorable according to the characteristic viscosity – temperature dependence. An increase in the concentration of niobium pentoxide to 40 % translates slags into the category of “short” (with a high crystallization rate). It is shown that an increase in the concentration of niobium oxide Nb2O5 from 15 to 40 % leads to a decrease in the crystallization temperature of melts by 200 °C and a decrease in the viscosity of melts from 1.32 to 0.24 Pa·s at 1350 °C. The improvement of the physico-chemical characteristics of oxide melts with an increase in the concentration of niobium pentoxide can favorably affect the technical and economic indicators of ferroalloy production.

Choosing special methods of selective disintegration and schemes for complex refractory ore

Introduction. The article highlights a new procedure of choosing special methods of disintegration and schemes for complex refractory ore and develops an integrated approach and criteria to comparing different types of crushers and screens, namely, reduction ratio, grinding degree, slime formation degree, and a new selectivity criterion. Research aims to study a new method and derive an equation to determine the crushing in the layer force and a new selectivity criterion. Research methods. The new methods were tested by comparing Otboynoye deposit tantalum ore, Vishnevogorsky deposit niobium ore, and Zashihinsky deposit tantalum-niobium ore crushing in cone inertial and centrifugal impact crushers and a roller press. The process of crushing in machines was studied in the laboratory and semi-industrial conditions. Different operation modes of crushers and screens were also checked. Object of research is tantalum and niobium ore of different deposits. Research results. The crushing selectivity criterion and reduction ratio comparison demonstrated that centrifugal impact crusher and roller press indexes are lower than the cone inertial crusher (KID) indexes. The reduction ratio for different crushing machines is 10.1 for the centrifugal impact crusher, 10.8 for the roller press, and 14.2 for the cone inertial crusher. The selectivity criterion for the crushing machines is 0.632 units for the centrifugal impact crusher, 0.730 units for the roller press, and 0.848 units for the KID. The KID-300А crusher performed the best for Otboynoye deposit tantalum ore and Vishnevogorsky deposit niobium ore. The KID-300А crusher also has the best slime formation degree criterion. The new method has been tested and approved. Summary. The paper analyses different methods and criteria of selective crushing. A new crushing selectivity criterion was proposed based on optical and electron microscopy data. It describes the ratio of liberation in the crushed product and feed.

Potential for obtaining and applying complex niobium ferroalloys

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.

Proizvodnja niobijuma - prikaz procesa od rudnika do proizvoda

A number of industrial and technology sectors have been paying attention to a particular chemical element in recent years, namely niobium (Nb). There are many niobium deposits scattered around the world, and for each deposit different technologies are applied for extraction and processing due to the singular characteristics present at each site. In this paper, a review of the many technologies for niobium production will be presented starting at the mine, through techniques of niobium ore beneficiation and refining, technologies to produce ferroniobium alloy, oxides, special oxides, ammonium niobium oxalate, the separation of niobium from tantalum, and techniques to reduce and purify metallic niobium.

Synergistic deformation in a combination of cemented paste backfill and rocks

In this study, cemented paste backfill (CPB) specimens comprising tantalum–niobium ore tailings and rocks, with various cement–tailings (C/T) ratios of 1:4, 1:8, and 1:10, were evaluated to elucidate the mechanism of synergistic deformation via uniaxial compression tests. The results indicate that the overall strength of the composite body is similar to that of the single CPB specimen. The elastic modulus of the composite body increases as the strength ratio of the two specimens decreases. The strength of the two specimens in the composite body the larger the ratio, the larger the Poisson's ratio of the backfill specimen, but the smaller the Poisson's ratio of the rock specimen. The stress–strain curve of the composite body is similar to that for the single CPB specimen; it can be divided into four stages. This curve indicates that the failure mode primarily manifests as shear and tensile failures in the CPB specimen. For the composite body, the strain of the backfill is significantly larger than that of the rock. However, the deformation in these two materials exhibits good synergy; only limited hysteresis is observed in the change time. During the loading process, the assembly exhibits different acoustic emission (AE) activities for the four stages. The AE ringing count produced by the CPB is significantly higher than that of the corresponding rock when the intensity ratio of the two specimens in the assembly increases. This trend becomes more obvious with an increase in the strength ratio of the two specimens in the composite body. The peak stress of the combined body lags behind the peak of the ringing counts, and the AE characteristics of the combined body reflect the synergy of the failure of the two specimens. The results of the study can provide a reliable theoretical basis and technical reference for the design of structural parameters of infill mining.

The problems of application of domestic ore raw materials in the production of ferroalloys

There is a difficult situation with ferroalloy production in Russia – production has a raw material import dependence in the presence of our own large, although not quite high-quality, in accordance with world standards, mineral resource base. As rule, domestic ferroalloy raw materials are of low quality: a low content of leading elements (manganese, chromium ores), a high content of phosphorus (manganese, niobium ores), sulfur (manganese ores). The paper gives examples of a complex of physicochemical studies and the development of a number of alternative technologies for the smelting of new ferroalloy compositions with Mn, Cr, Nb, W. The scientific studies together with the development of the technology have been carried out to study the effect of ferroalloys composition on consumer properties. Because of the fact that the chemical composition of the ores of most new deposits cannot ensure the production of standard ferroalloys. By help deep physicochemical and technological studies it is possible to create new processes and combinations of different types of ferroalloys from non-traditional domestic mineral raw materials. The alloys are not inferior in terms of technical and economic indicators of products obtained from rich imported ore materials.

On the age of pyrochlore carbonatites from the Ilmeno-Vishnevogorsky Alkaline Complex, the Southern Urals (insights from Rb-Sr and Sm-Nd isotopic data)

Research subject. In this research, we carried out Sm-Nd- и Rb-Sr-dating of pyrochlore carbonatite from the Vishnevogorsky niobium deposit, Ilmeno-Vishnevogorsky Alkaline Complex, Southern Urals. IVC is located in the Ural fold region and is a carbonatite complex of the linear type. Rare metal (Nb-Zr-TR) deposits and occurrences are related to IVC. The age and the duration of IVC deposits formation remains a matter of debate. To determine the age of IVC carbonatites and related niobium ore, we measured Sm-Nd and Rb-Sr isotopic compositions and concentrations of the elements in the minerals (pyrochlore, calcite, apatite, biotite) and bulk sample of pyrochlore carbonatite. Materials and methods. The Sm and Nd isotopic compositions and concentrations were determined on a Finnigan MAT-262L (RPQ) seven-collector mass spectrometer in the static regime at the Geological Institute of the Kola Scientific Center, Apatity, Russia. The Sr and Rb isotopic compositions and concentrations were determined on thermos-ionization mass spectrometer Triton Plus (“Geoanalitik”, IGG UD RAN, Ekaterinburg, Russia). Results. Age of pyrochlore carbonatites from ore zone 140 (Vishnevogorsky deposit, IVC) defined by Sm-Nd and Rb-Sr isotopic methods. Mineral Sm-Nd-isochron (5 points) indicated age 229 ± 16 Ma, mineral Rb-Sr-isochron (5 points) showed similar age 250.5 ± 1.2 Ma. Conclusions. Results Sm-Nd и Rb-Sr dating indicate that the pyrochlore сarbonatites of ore zone 140 crystallized ≈ 250 Ma ago, at the stage of the postcollisional extension, possibly, in connection with exhumation complex, which was accompanied by decompression, partial melting of rocks, involving fluids, dissolution and precipitation of Ordovician-Silurian alkaline-carbonatitе complex. Thus, the formation of the IVC carbonatites and related Nb-ore, which began in Silurian (S), continued in Permian (P) and Triassic (T1-2) and was associated with the post-collision stage of tectonic activity in the Ural Fold Belt.

Production of a Phosphate Concentrate from the Tailings of a Niobium Ore Concentrator

Apatite is the main source of phosphorous for the making of chemical fertilizers. While apatite is usually recovered from phosphate orebodies as the primary product of a mining exploitation, this paper documents the approach taken to produce a phosphate concentrate as a secondary product from the tailings of a niobium ore concentrator. The conventional desliming/flotation scheme used to process phosphate ores was tested and adapted to process one of the reject streams of a niobium concentrator in order to produce a salable phosphate concentrate. For that particular material, it was found that the reverse flotation of apatite yielded better results than the commonly used direct flotation of apatite. The recommended approach to produce the phosphate concentrate is desliming followed by reverse flotation of apatite and an acid leaching of the apatite concentrate to lower the MgO content below the specification for a phosphate concentrate. The obtained phosphate concentrate assays more than 32% P2O5 at a P2O5 recovery of 41%, which although low is found to be economic for the case of processing plant reject tailings.

Application of russian ore raw materials to ferroalloys production

The main problem of ferroalloy production in Russia is the availability of ore raw materials in domestic factories. Only a few types of alloys are produced from our own raw materials (such as ferrosili-con and vanadium alloys). Most ferroalloys are either imported from abroad or smelted from imported raw materials. The difficult situation in domestic ferroalloy production is associated with raw material import dependence. Despite the presence of its own large mineral resources base, although not quite high-quality in accordance with world standards. Domestic ferroalloy raw materials have a low content of leading elements (manganese, chromium ores), a high content of phosphorus (manganese, niobium ores) and sulfur (manganese ores). This requires a conduction of physical and chemical studies and the creation of a number of new alternative technologies. The work shows that it is possible to create new processes and combinations of different types of ferroalloys from non-traditional domestic ore raw materials based on deep physicochemical and technological studies. They are not inferior in terms of their technical and economic indicators of products obtained from imported materials. To successfully solve the problem of providing the ferroalloy industry with domestic ore raw materials, it is necessary to combine the research of geology, enrichment and metallurgy.

Ferroalloy Production Using Russian Crude Ore

The key problem of ferroalloy production in Russia is the availability of crude ore. Only few types of alloys are produced at domestic plants from domestically-produced raw materials (ferrosilicon, vanadium alloys). The bulk of ferroalloys is either imported from abroad or smelted from imported raw materials. The development of ferroalloy production is a challenging situation for Russia: raw material import addiction in the presence of large domestic mineral and raw material base, but substandard in terms of world standards quality. One of the main reasons for this situation (in addition to organizational and financial ones) is a well-established conservative approach to the ferroalloy smelting technology using the same type of crude ore and obtaining products as per GOST Standard. Domestic ferroalloy raw materials, as a rule, are of low quality. They have a low content of main elements (manganese, chromium ores), a high content of phosphorus (manganese, niobium ores), and sulfur (manganese ores). This requires physical and chemical studies and the development of new alternative technologies. It is possible to create new technology processes and different ferroalloy combinations that are not inferior in terms of their technical and economic indicators to products obtained from imported non-traditional domestic ore crude, based on deep physical, chemical and technological studies. For solving the domestic crude ore problem found in the ferroalloy industry, it is necessary for scientists, geologists, processing experts and metal-makers to work together.

FERRONIOBIUM ALLOY FINES AGGLOMERATION THROUGH BRIQUETTING

Brazil is the largest producer of Niobium alloys, with a production of 58,000 tons of Nb2 O5 concentrate in 2016, corresponding to a 92.81% of the world production. The Brazilian Niobium ores grades vary from 0.51 to 2.71%. Ferroniobium (Fe-Nb) is an iron niobium alloy with niobium content of 60-70%. It is the main source for niobium alloying of HSLA steel and covers more than 80% of the worldwide niobium production. In 2014, Brazil produced 51,737 tons of Fe-Nb, being around 90% of it for exportation. In the final stage of the Fe-Nb production, the alloy needs to be crushed in a jaw crusher, which generate fine particles (around 26% of the feed below 10 mm at Niobras/CMOC). The selling price of the fine particles have a significant loss in the market, since the fine particles cannot be used directly in steelmaking. A process to agglomerate the Fe-Nb fine particles into briquettes with size and chemical composition similar to original products was developed. Organic binders were used as well as a lubricant agent. The briquettes were characterized both physically and chemically. For the physical characterization, the briquettes were tested for mechanical and water resistance, thermal shock and Brinell hardness. Briquettes containing addition of 3% of zinc stearate, 2% of iron powder, and 1% of water reached a Niobium content above 62% and contaminants levels of below the standard Fe-Nb specifications. The results indicate that Fe-Nb alloy fines can be technically and economically agglomerate by briquetting.

Treatment Technology for Niobium—Bearing Ore Processing Wastewater of Various Ionic-Dispersion Compositions

Based on the studies into ionic—dispersion compositions of sewage water after mining and processing of niobium ore of the Lovozero deposit, it is substantiated to be expedient to convert some pollution agents from solution to suspension state. A combined process is proposed for treatment of mine wastewater, which is 94% of total sewage water of mining and processing, by integrating coagulation, sorption and flotation techniques. The mathematical model of aggregation of suspension particles with regard to the hydrodynamic mode of coagulation is suggested. The model makes it possible to predict material and dispersion compositions of a new multi-phase system under different temperatures towards automation of the wastewater treatment process. The solution on forming surface properties of activated aqueous dispersions of air using a modified finely dispersed sorbent with intent to intensify the wastewater purification process.

Applying chemometrics to predict metallurgical niobium recovery in weathered ore

Abstract Niobium metallurgical recovery measures how much of the metal content in the ore is separated in the concentrate after the mineral processing stages. This information can be obtained through laboratory tests with ore samples obtained during drilling. Thereunto, representative ore samples are subjected to tests mimicking the ore concentration processing flow, but these experiments are time consuming and costly. The main objective of this study was to develop a more efficient way to obtain the metallurgical recovery information from ore samples. Based on the development of chemometrical studies, the chemical components currently analyzed in the ore with correlation to the metallurgical recovery were identified. These correlated variables were used to build a nonlinear multivariate regression model to explain the response variable, i.e. metallurgical recovery. The Principal Component Analysis was used in this work to define which chemical variables contribute most to explain the metallurgical recovery phenomenon. The Second order regression equation (Response Surface) was the most suitable methodology to explain the metallurgical niobium recovery and was created by the interaction of the five most important chemical variables. After the exclusion of outliers, the linear regression coefficient between the metallurgical recovery calculated and the metallurgical recovery analyzed was 82.59%. The use of the second order regression equation contributes to reduce the amount of experimental analysis to assess the geometallurgical niobium ore response, promoting the reduction of costs for metallurgical characterization of the ore samples. The methodology proposed proved to be efficient, maintaining an adequate precision in the forecasted response.