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We propose a hydrogen-based preliminary reduction process for primary ilmenite before the smelting process in titanium dioxide pigment production, because of its advantages of low energy consumption and carbon dioxide mitigation. The hydrogen-based gaseous reduction of primary ilmenite concentrate was investigated at temperatures between 1273 K and 1473 K (1000 °C and 1200 °C) in an H2–CO atmosphere and compared it with the carbothermic reduction of secondary ilmenite. Between 1273 K and 1373 K, hydrogen reduction was faster than carbothermic reduction for the entire time of the reaction. However, at 1473 K, CO evolution by the Boudouard reaction caused the carbothermic reduction to be faster initially; however, hydrogen reduction was faster after 70 minutes. The phases of the final product by the gaseous reduction were metallic iron, TiO2, and a pseudobrookite solid solution. Numerous cracks and pores were generated, and agglomerated iron was observed throughout the particles. The gaseous reduction reaction was controlled by a chemical reaction with an activation energy of 42 kJ/mol. For the subsequent smelting process, the use of ilmenite concentrate feeds reduced by hydrogen during the preliminary reduction process decreased the energy consumption and CO2 emissions.

To achieve the utilization of the abandoned ultrafine ilmenite (−20 μm) produced in the titanium magnetite processing plant in Panzhihua, the superconducting high-gradient magnetic separation (SMS) technology was proposed in this study. After optimizing the conditions of magnetic intensity, feeding and pulsation, an SMS concentrate with TiO2 grade of 16.03% and TiO2 recovery of 66.39% was obtained through one roughing–one cleaning pre-concentration flowsheet. The specific magnetic force and magnetic force were calculated and analysed to illustrate the pre-concentration mechanism, and the results revealed that the combination of high magnetic field and strong pulsating resulted in the effective pre-concentration of the ultrafine ilmenite in the SMS process. In addition, the magnetic force analysis indicated that the high magnetic intensity and high magnetic gradient are the key factors of the SMS technology. Furthermore, the EDS-Mapping detection certified that the ultrafine ilmenite was concentrated from the gangue minerals using SMS technology.

The presence of iron oxides may provide a sensitive indicator of the effects of cropping practices on coffee plantations. Authors characterized the mineral phases present in soil A horizons at three different farms located in the Department of Tolima within the regions of Líbano and Villahermosa. Our analysis includes X-ray diffraction, Mössbauer spectroscopy, and remote sensing to discriminate the distribution of the different magnetic mineral phases. X-ray diffraction was used to identify the mineralogical properties of iron oxide such as hematite, goethite, and ferrihydrite (Fh), as well as tectosilicate minerals such as albite and sanidine. Mössbauer spectroscopy results for samples taken at room temperature indicate the presence of Fe2+ and Fe3+ mineral phases, which possibly correspond to ilmenite or magnetite. Finally, Sentinel-2A multi-spectral imager (MSI) data was used to map the distribution of iron oxides and study the influence of their distribution throughout the study area. A high correlation between Mössbauer spectroscopy and Sentinel-2A MSI data exists throughout the study area. The results suggest that farms close to the main Nevado del Ruíz Volcano have a more significant mineralogical variability. In contrast, more distant farms are characterized by soils with more iron oxides, the product of weathering, erosion, and human activities.

We present an optimized magnetic separation process to improve the recovery of high-content vanadium and titanium concentrates from vanadium‑titanium magnetite (VTM) ore. The ore chunks were crushed using jaw crushers and then grinded in a laboratory rod mill for different grinding times and studied. Vanadium recovery was dependent on maximizing magnetite and ilmenite recovery. Ilmenite, which is the main source for titanium, existed in the stripes within magnetite; it got pulverized first during milling and remained as relatively coarse particles of magnetite. A grinding time of 15 min was determined as optimum for the grinding conditions of this study, based on the degree of liberation, the grade, and recovery of vanadium. The effect of varying magnetic intensities on the separation behavior of the pre-concentrates was analyzed through magnetic separation of the ground VTM samples. The grade and recovery attained for the vanadium concentrates were 1.12% and 63%, respectively. In addition to vanadium, titanium concentrates were also obtained by medium-intensity magnetic separation and the grade and recovery were 38% and 75%, respectively.

A study on mineral characterization and nano titanium dioxide synthesis from ilmenite ore of Bangka Island, Indonesia, has been carried out using a caustic fusion method and hydrochloric acid leaching. Comprehensive mineral characterization was conducted using X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD) to depict each fractionated particle's elemental composition and mineralogy, i.e., +80, ?80+100, ?100+150, ?150+200, -200+325, and -325 mesh. Other analyses performed are VSM to measure the magnetic properties and SEM to determine the distribution of elements at each particle size. Based on the characteristics of the ilmenite ore, magnetic separation was applied for the initial stage and analyzed gravimetrically. Later processing was the synthesis of nano titanium dioxide, conducted sequentially, including roasting and leaching. Roasting was run at 900°C with and without caustic soda, and then hydrochloric acid was applied. In reference to the elemental analysis, titanium (Ti) concentration is higher in smaller particle sizes and vice versa for iron (Fe) concentration, so the synthesis of nano titanium dioxide was carried out using a -100+150 mesh particle size. The optimum condition for nano titanium dioxide synthesis was 2:1 of NaOH and ilmenite weight ratio, 20% HCl concentration, and 4 hours of leaching time. The nano titanium dioxide (TiO2) obtained was then characterized using XRF, XRD, particle size analyzer (PSA), and transmission electron microscopy (TEM). Roasting with caustic soda showed better nano titanium dioxide purity with 96.04% of TiO2 with particle size in the range of 50–80 nanometers.

The material composition of pseudorutile-leucoxene sandstones of the Pizhemskoye deposit is investigated. It is shown that the formation of minerals of this deposit occurred as a result of metamorphism of primary ilmenite under oxidative hydrothermal conditions with the participation of carbon dioxide, which proceeded with the removal of iron in the form of iron bicarbonate, followed by its transformation into siderite. The main titanium-containing phases formed during the weathering of ilmenite are pseudorutile (Fe2+,Fe3+)2 – nTi3O9 (modified ilmenite) and leucoxene. As the iron was removed, the voids formed in the ore grains of ilmenite were filled with ultrafine quartz, which crystallized from the silica brought by hydrothermal solutions. The products of ilmenite alteration (siderite and iron oxides), as well as clay minerals, could be filtered by meteoric waters through quartz sand (or sandstone) into the lower layers, as a result of which the Pizhemskoye deposit acquired a layered structure. The upper layer is represented by gray-colored sandstones, characterized by a low content of ferrous minerals. The lower layer is red-colored ferruginous sandstones, and the intermediate layer is red-colored siltstones with a high content of clay and ferruginous minerals. Siderite, crystallizing from hydrothermal solutions in the form of a cementing bond, densely filled all the space and pores between the grains of mineral phases, as a result of which it is very difficult to open the ore phases even with fine grinding (

The experimental works of Russian and foreign researchers focused on the behavior of ore minerals, such as titanomagnetite and ilmenite in an oxidizing environment in different temperature ranges, have been analyzed. The optimum temperature conditions and time interval for oxidizing roasting of mineral aggregates have been substantiated. The Medvedevskoe ores are described in brief. Special attention is paid to the mineral assemblages of disseminated titanomagnetite–ilmenite ore subjected to secondary alterations, such as amphibolization, chloritization, saussuritization, albitization, and martitization. The evolution of the phase and structural heterogeneity of titanomagnetite microaggregates is observed as variations in the composition and structure of magnetite–ilmenite exsolution products under collective recrystallization complicated by martitization processes. Oxidizing roasting (T = 1000–1100°C) of titanomagnetite aggregates makes it possible to reduce the degree of their heterogeneity and form stable mineral phases, such as pseudobrookite, hematite, and rutile with subsequent enlargement thereof. The heterogeneous structure of titanomagnetite microaggregates affects the course of heterogeneous oxidation processes in microaggregates of different mineral assemblages. Due to solid-phase transformations, martitized titanomagnetite (with ilmenite lamellae) changes completely with the formation of pseudobrookite–hematite microaggregates. Ilmenite at the contact with hematite, as well as in individual grains, is transformed into complex fine-grained rutile–pseudobrookite aggregates. The newly formed minerals are mostly solid solutions. Pseudobrookite is characterized by a reduced Fe2O3 content (up to 62.71 wt %) with 33.51 wt % TiO2. Hematite as an transformation product of martitized magnetite contains up to 4.90 wt % TiO2. Rutile forms limited solid solutions with pseudobrookite, and Fe2O3 reaches 7.59 wt %. With a decrease in material size, the solid-phase transformation process becomes more active; therefore, the optimum size grades include –0.25 + 0.125 mm and –0.125 + 0.071 mm. The solid-phase transformation of primary ore minerals is almost completed during the roasting for 72 h. The homogenization of mineral aggregates and the enlargement of newly formed Fe- and Ti-bearing minerals makes them better detectable in technological products and improves the general Ti extraction in various products. The results obtained in the course of high-temperature oxidizing roasting of magnetite–ilmenite ores at the Medvedevskoe deposit can be of interest to geologists studying the formation processes of magmatic magnetite–ilmenite deposits, which vary widely in terms of both mineralization composition (from low-grade Ti ores to extremely hard-to-process high-grade Ti ores) and formation conditions (deposits of various depth facies) and depend considerably on the oxygen regime and composition of volatile mineralizing elements (H2O, Cl, F, etc.).

To constrain the mechanisms governing the extremely large variations of Mg and Fe isotopes in magmatic Fe–Ti oxides in layered mafic intrusions, we investigate Mg isotopic compositions of magnetite, coupled with its chemical data and whole-rock major element and Sr-Nd isotope compositions from the Baima layered mafic intrusion in the Emeishan large igneous province, SW China. The Baima intrusion is mainly composed of magnetite-wehrlite and magnetite-troctolite (i.e., oxide-rich rocks) in the Lower Zone, and troctolite and gabbro (i.e., oxide-barren rocks) in the Middle and Upper Zones. Magnetite separates display large Mg isotopic variation, with δ26Mg ranging from −0.17 ± 0.06 to +0.58 ± 0.04‰ in the oxide-rich rocks and from −0.18 ± 0.06 to +0.98 ± 0.04‰ in the oxide-barren ones. The lack of correlation of δ26Mg with trace elements in magnetite and whole-rock Sr-Nd isotopic compositions indicates that the large Mg isotopic variation in magnetite was not produced by fractional crystallization, magma mixing, crustal contamination, and/or trapped liquid shift. Instead, equilibrium isotope fractionation induced by Mg–Fe re-equilibration between magnetite and ilmenite at different subsolidus temperatures controlled the Mg isotopic variation in the oxide-rich rocks; and kinetic isotope fractionation driven by Mg–Fe inter-diffusion between magnetite and olivine and/or clinopyroxene dominated the oxide-barren rocks. Both processes were primarily controlled by the assemblage and modal abundance of coexisting minerals to which magnetite adjoins. Overall, fractional crystallization and subsequent subsolidus diffusion played crucial roles in the genesis of the Fe–Ti oxides in the Baima intrusion. Our results also reveal widespread isotope disequilibrium between coexisting minerals in mafic magma chambers and suggest that Mg isotope geochemistry has a great potential to characterize the formation of Fe–Ti oxides in layered mafic intrusions.

The paper presents results of thermokinetic investigation of the hazard-type reaction of Norwegian and Australian ilmenite ores with sulfuric acid, modified by the addition of elemental sulfur, to increase the process safety in industrial conditions. In the reactions of both ilmenite ores the addition of sulfur caused a reduction of the thermal power generated in the reaction and a decrease in the value of the thermokinetic parameter ΔTmax/Δτ for almost the whole range of initial concentrations of sulfuric acid. It was also found that the addition of sulfur to the reaction did not negatively affect the degree of ilmenite leaching. The interpretation of the obtained thermokinetic curves allowed to determine safe process conditions for both types of titanium raw materials.

The I-type Pan-African Misajé granites, situated in the Western domain of the Central African Fold Belt are among the late-to post tectonic granites that intruded the ante-Pan-African country rocks. In this study, magnetic susceptibility and geochemistry data are integrated to evaluate the productive and non-productive metal potential of these I-type plutonic granites, which comprise Leucocratic granite, Biotite granite, Biotite-hornblende granite, and granodiorites. The magnetic susceptibility of the representative rock samples of the Misajé pluton ranges from 0.001 × 10−3 SI to 33.2 × 10−3 SI. These values indicate the coexistence of both magnetite and ilmenite-series. The magnetite-series (>3 × 10−3 SI; oxidized type) constitute about 32 vol.% while the ilmenite-series ( 1) grains sizes. The Misajé plutonics are high potentially productive in Zn, Th, ilmenite, and magnetite and low productive in Sn, W and Cu though their extension remains limited, probably due to the remobilization of the ancient Paleoproterozoic crust that would have contributed to the dispersing of pre-Pan-African metal deposits.

The intertidal zone as well as sand dunes of Gopalpur coast, Odisha contains heavy minerals of varying proportions ranging from 6.51 to 8.45 wt% out of > 63 µm fractions. The heavy mineral assemblages are ilmenite, magnetite, garnet, sillimanite, zircon, rutile and hornblende of which ilmenite is dominant. Electron probe micro analysis of ilmenite grain indicates that it contains TiO2 in the range of 50.72% to 58.96% and FeO 37.4% to 57.15% in addition to Cr2O3 (0 to 0.12%), NiO (0 to 0.27%), MnO (0.06% to 2.04%) and MgO (0.17% to 2.16%). Mn/Mg ratios show lower values (0.13 to 2.76) for most of the samples, indicating basic rock source such as pyroxene granulites. Few ilmenite grains are having higher Mn/Mg values varying between 4.55 and 6.58, might have been derived from charnockite and khondalites in the hinterland. Scanning electron microscope photographs of ilmenites show sub-rounded to rounded grains with few grains having angular to sub-angular feature. Their micro morphological features indicate effect of mechanical and chemical weathering. Flattened striated surface with grooves feature may be due to mechanical weathering. Etch marks and pits may be due to differential chemical action in low energy sub-aqueous environment of deposition.

The paper presents data on phase relations in garnet-bearing carbonatite from the Tromso Nappe, Norway. The carbonatite matrix consists of calcite–dolomite carbonate with three generations of garnet inclusions (up to 15–20%). The relics of the primary garnets (Grt1) are depleted ( 1300°C. In the experiment with H2O + CO2 fluid, the solidus and liquidus temperatures are ≤950 and 1250°C, respectively. The subsolidus association is calcite, garnet, clinopyroxene, biotite, and accessory minerals: apatite, ilmenite, rutile, and titanite. The garnet and carbonatite melt occur in reaction relationships, as is evident from the garnet zoning with a decrease in the FeO and increase in the MgO, CaO, TiO2, and LREE concentrations. The geological setting, phase relationships, and experimental data indicate that the garnet-bearing carbonatites in the Tromso area were formed in relation to the carbonatization and melting of upper mantle material at high pressures during the collision of the Baltica and Laurentia plates in the course of the Caledonian orogenesis, with subsequent intrusion and crystallization of silicate–carbonate magmas.

Titanium dioxide (TiO2) in mineral dust is considered as one of the driving forces of photocatalytic reaction at the aerosol surface in the atmosphere. As a precursor of mineral dust, soil contains ilmenite (FeTiO3) and titanite (CaSiTiO5), which have lower photochemical reactivities than TiO2. However, Ti species other than TiO2 in aerosol particles are not well recognized due to the lack of observation in ambient samples. In this study, Ti species in size-fractionated aerosol samples collected in the Noto Peninsula, Japan, were determined by macroscopic and semi-microscopic X-ray absorption fine structure spectroscopy. Regardless of aerosol particle size, Ti species were primarily composed of rutile, anatase, ilmenite, and titanite. Semi-microscopic Ti speciation showed that Ti-poor spots associated with mineral dust were composed of a mixture of rutile, anatase, ilmenite, and titanite, and Ti-rich spots were primarily composed of TiO2 (rutile or anatase) derived from authigenic minerals or anthropogenic materials. Thus, the Ti species in aerosol particles, especially mineral dust, were not composed solely of TiO2 polymorphs. Therefore, the photochemical reactivities of Ti in aerosol particles may be overestimated when laboratory experiments or model studies employ TiO2 as the representative Ti species.

Peridotites in ophiolites exposed along Himalayan suture zone open window to study deep Earth processes. We report c.2 km thick well exposed mantle section of Shergol ophiolite in the Indus Suture Zone (ISZ). The mantle section comprises lherzolite, serpentinised peridotite with cumulate chromitites. The in situ evidences from micron-sized mineral exsolutions are studied using optical microscopy, scanning electron microscopy and micro-Raman spectroscopy. From the ISZ lherzolite, ilmenite mineral exsolution is noted in the olivine grain. The exsolved ilmenites are oriented topotactically following former {111} planes of magnetite, providing evidence of spinel precursor. In another observation, the disoriented 1–3 µm wide and 10–80 µm long ilmenite needles are hosted in the olivine, is characterised by Raman peaks at 685, 370 cm−1 with low peaks at 308 cm−1,523 cm−1, 683 cm−1, 693 cm−1 and 731 cm−1 point to mixed mineral phases of magnetite with Cr–Fe–Al. Based on morphologies, crystal-chemical structure and modal calculation of exsolutions, we infer, exsolved Fe–Ti phases in Shergol peridotite is sourced from deeper part of the upper mantle. With the Fe–Ti phases, tiny silicate inclusions in chrome spinel and accompanying opaque base metal sulphides are also observed in the same peridotite, attributes successive stages of partial melting and subsequent cooling of metal enriched mantle. These observations, challenge shallow intra-oceanic arc setting for Shergol ophiolite and proposes, part of exsolved mineral phases in ophiolite has deep Earth origin. These mineral phases would ascent at the shallow mantle level beneath Neotethyan spreading ridge aided by dunite channel.

The effect of pre-oxidation degree of Panzhihua ilmenite concentrate on the gaseous reduction by carbon monoxide was investigated. The raw ilmenite concentrates were pre-oxidized at 600, 700, 800, 900, and 1000 °C for 2 h, respectively. The phase change, FeO content, and morphology after the oxidation at various temperatures were characterized. The oxidation degree was calculated according to the change of FeO content. Thermogravimetry was performed on the oxidized ilmenite concentrate samples (oxidized at 600, 800, and 1000 °C) at 850, 900, and 950 °C, respectively. The results show that the pre-oxidation of ilmenite concentrate can accelerate the reduction process: the higher pre-oxidation degree, the faster reduction rate. The high pre-oxidation degree of ilmenite concentrate is beneficial to accelerate the subsequent reduction process in two ways. Three stages of the reduction process were divided via the first derivatives of reduction degree, and the reduction mechanism and apparent activation energy were discussed subsequently.

In our previous publication, we published a simple, low-cost, and environmentally friendly process for the breaking down of the ilmenite lattice using rotary autoclaving, separation of titanium and iron components, and the conversion of the titanium component to amorphous TiO2 and phase-specific titanium dioxide nanorods. Here, the separated iron component was converted into iron oxide (magnetite and hematite) and iron oxy-hydroxide (akaganeite, β-FeOOH) nanoparticles. The process flow diagram is presented to explain the steps involved. The materials synthesized are fully characterized by X-ray diffractogram (XRD), scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDAX), and Fourier transform infrared (FT-IR), and it is shown that they contain 100% pure iron oxide and iron oxy-hydroxide nanoparticles without any detectable impurities. All of the chemical reactions involved in this process, which contribute to the mechanism of the process, are given. So far, such a low-cost, environmentally friendly, and low-temperature process has not been documented, and the process can be scaled-up for mass production of these nanomaterials used in various technological applications.

The cellulose impregnated phosphorus oxychloride (COP) was newly prepared. Its efficiency was assessed for the first time by removing Cr6+, Pb2+, V5+, and Cd2+ ions from a diluted sulphuric solutio...

Numerous silicate, Fe-oxide, and Cu–Au–Ag microspherules are found in Fe ores and pyroclastic rocks of the Kostenga deposit, Lesser Khingan (Far East of Russia). The silicate spherules contain immiscible Fe and Si glasses, vapor voids, and mineral inclusions. The Fe-oxide spherules host magnetite with a small amount of ilmenite and Fe-rich silicate glass. The Cu–Au–Ag spherules contain inclusions with dominant CuO in their composition. These microspherules are considered to form due to rapid uplift and degassing of liquation-differentiated ore-silicate melts. The possible volcanic formation of ores and precious metal mineralization is discussed for these types of the deposits.

Research subject. Tungsten deposits of the Aginsky and Argunsky structural-formation zones in the Eastern Transbaikalia. The aim was to clarify the sources and conditions for the formation of tungsten mineralisation, as well as to clarify a relationship between magmatism and tungsten mineralisation. The conditions of deposit formation were studied using data on the chemical composition of rocks and ores and the oxygen isotopic composition of the ore veins of tungsten deposits.Methods. The elemental composition of rocks was determined by the methods of X-ray fluorescence and standard chemical analysis; the concentration of rare-earth elements was determined by sorption-atomic emission analysis with inductively coupled plasma (Geological Institute SB RAS, Ulan-Ude). The examination of oxygen isotope composition was carried out at the Geological Institute of SB RAS (Ulan-Ude) using a MIR 10-30 system of laser heating with a 100W CO2 laser and 10.6 microns wavelength in the infrared region in the presence of a BrF5 reagent (analyst V.F. Posokhov).Results and conclusions. It was established that granites in the Kukulbey complex of the Antonovogorsky and Bukukinsky tungsten deposits correspond to granites of an ilmenite series, while the ores in the Spokoininsky deposit are associated with the granites of a magnetite series. A close correlation was established between W with Ta, Nb, Hf and As, indicating similar compositions of ore-bearing sources of the tungsten deposits. For Barun-Shiveinsky, Antonovogorsky and Bukukinsky deposits, the oxygen isotope compositions in the fluid in equilibrium with quartz of the productive stage was calculated, indicating the magmatic sources of mineralisation.

Titanium dioxide is the most common titanium-containing product on the world market, and the demand for it is increasing. The global consumption of TiO2 is 7 – 7.5 million tons annually. Titanium dioxide is mainly obtained from ilmenite and rutile concentrates. The largest producers are China, USA, Germany, UK, Mexico, and Saudi Arabia. In addition to the natural resources of titan, there are man-made sources. This type of resource includes titanium-containing slags obtained as a result of pyrometallurgical processing of ores and concentrates containing titanium dioxide. These slags, in addition to titanium dioxide, contain silicon in the form of dioxide, silicates or aluminosilicates, whose chemical processing is difficult due to their high melting point (more than 2000 °C) and the chemical stability of these compounds in mineral acids (sulfuric, nitric, hydrochloric). Processing of such raw materials is carried out by “classical” chlorine and sulfuric acid methods. The use of fluorides in industry is realized in the production of aluminum, zirconium, uranium, beryllium, niobium, etc., which indicates the possibility of using fluoride methods for titanium slags processing. The article discusses a method for producing titanium dioxide based on the use of ammonium hydrodifluoride NH4HF2 , which has a high reactivity to a number of chemically resistant oxides (oxides of silicon, titanium, aluminum, etc.). The fluoroammonium method for processing titanium slag using NH4HF2 involves slag decomposition of in NH4HF2 melt followed by silicon admixture sublimation. Cleaning from iron, aluminum and other impurities is carried out using a solution of NH4HF2. Further precipitation of titanium with treatment of the precipitate by AlCl3 and ZnCl2 solutions followed by calcination allows to obtain a rutile modification of titanium dioxide.

Natural iron minerals and zero-valent metals have been widely tested as catalysts for the Fenton-like process, but the systematical comparison study about their catalytic performance was rarely conducted, and the risk of the secondary pollution of toxic heavy metals was still not uncertain. In this paper, a comparison study of applying pyrite, ilmenite, vanadium titano-magnetite (VTM), zero-valent iron (ZVI), and zero-valent copper (ZVC) as Fenton-like catalysts for the removal of imidacloprid was performed. The results showed that ZVI exhibited the highest activity among the recyclable solid catalysts with a removal rate of 96.8% at initial pH 3 using 10.78 mmol/L H2O2, due to iron corrosive dissolution. Vanadium titano-magnetite (VTM) exhibited the best activity at first use among tested minerals but with low reusability. Pyrite with stable morphology showed a medium but sustainable ability to degrade imidacloprid, achieving a removal rate of 10.5% in the fifth use. The reaction much favored the acidic condition of initial pH around 2 or 3. Meanwhile, there was a significant positive correlation between removal efficiency and dissolved Fe or Cu concentration. Pyrite was considered to be a promising catalyst in Fenton-like reaction. It was suggested that the system proceeded predominantly through a homogeneous route via dissolved Fe or Cu ions. Except ZVC and VTM, other tested catalysts showed the low possibility of causing secondary pollution of toxic metals in the application of Fenton-like process.

The cost of Ti production can be reduced by replacing rutile ore with abundant and cheap ilmenite ore (FeTiO3). However, the conventional processes for Ti production, including the Kroll process, require significant energy and yield a large amount of byproducts. To overcome these environmental challenges, we investigated the effects of the reaction temperature and time on the sulfurization of FeTiO3 by Na2SO4 below 1673 K. Fe-S-C metal and Ti-rich oxysulfide phases were generated, and the metallic phase could be removed from the oxysulfide phase via magnetic separation. With an increase in temperature, the Fe content in the oxysulfide phase decreased, while the Ti content increased. After the sulfurization of FeTiO3 for 1 h at 1673 K, the Fe content in the oxysulfide phase decreased by approximately 4 wt.%. The Ti content in the obtained oxide was determined through a simple cleaning treatment using dilute hydrochloric acid.

The chemical composition of the mineral ilmenite is useful in mineral exploration for diamonds and in understanding igneous geological processes. This study develops an analytical methodology for accurate analyses of ilmenite by LA-ICP-MS for major, minor, trace element and U–Pb isotopic compositions. Accuracy of chemical compositions by LA-ICP-MS is monitored by comparing with EMPA and accuracy of the LA-ICP-MS U–Pb ages is verified by comparison to published ages for other mineral geochrometers from the same sample. Variation of laser fluence (2, 3 and 5 J cm−2) and calibration materials (Mud Tank zircon, BCR-2g, and TB-1 rutile) are optimized to provide the best accuracy of ilmenite chemical and isotopic compositions. Rutile, as the primary calibration material for Pb/U ratios, produces accurate U–Pb ages within analytical uncertainties. Use of normalization to a 100% metal oxide total for LA-ICP-MS analyses, coupled with mineral stoichiometry calculations, allows for the estimation of Fe2+/Fe3+ ratios that compare well with similar estimates from EMPA (0.23 vs. 0.22 respectively). U–Pb age results from an igneous ilmenite from the Bushveld Complex using this methodology are within uncertainty of the zircon ID-TIMS age of the intrusion (2044 ± 31 Ma (2 s) vs. 2054.4 ± 1.3 Ma (2 s)).

Titanium carbide (TiC) powder was combustion-synthesized in argon from mineral ilmenite and activated carbon (C) using magnesium (Mg) as a fuel. The reactant powders were taken at FeTiO3 : C : Mg molar ratios of 1 : 1 : 3 and 1 : 1.5 : 4.5. The as-combusted products were leached with 1 M HCl at 80 or 90°C to remove byproducts and impurities. Best results (fewer impurities) were obtained for combustion products derived from FeTiO3 : C : Mg green mixtures taken at a molar ratio of 1 : 1.5 : 4.5 and subjected to acid leaching at 90°C for 150 min. After leaching, agglomerated TiC particles have a size of around 100 nm. Ilmenite mineral can be recommended as an alternative source of TiO2 for fabrication of titanium carbide powders.

Reduction of mobile aqueous uranyl complexes can be hindered by the strength of the uranyl-ligand complex and the resistivity of the complexes to electron transfer. Semiconducting solids, such as magnetite (Fe3O4) and ilmenite (FeTiO3), can facilitate otherwise-slow electron transfer between the reductant and oxidant, especially if these species are adsorbed on their surfaces as inner-sphere complexes. Electrons can then be shuttled through the surface or the structure. This process can be facilitated by either finding a new electron transfer path or by weakening or destroying the ligand-uranyl complex. Using in situ electrochemical atomic force microscopy (EC-AFM), we imaged reduction products of uranyl as mediated by magnetite and ilmenite in the absence or presence of the organic ligands, ethylenediaminetetraacetate (EDTA) and oxalate. In situ images of uranyl reduction show gradual nucleation and growth of reduced uranium on the mineral surfaces with decreasing reduction potentials. X-ray photoelectron spectroscopy (XPS) measurements indicate pentavalent uranium as the dominant uranium species resulting from uranyl reduction mediated by magnetite and ilmenite. The reduction potentials of uranyl-organic species relevant to our reaction system, (UVIO2∙oxalate)0 and (UVIO2∙HEDTA)−, are derived using quantum–mechanical modeling and compared with the midpoint potentials obtained from cyclic voltammetry measurements. The spectroscopic, electrochemical, and computational data suggest that the catalysis of Fe-bearing minerals facilitates the reduction of uranyl-organic complexes. U(VI)-oxalate complexes are redox-active and participate directly in the reduction mediated by magnetite. In the presence of EDTA, reduction of uranyl may proceed in concert with ligand exchange between metals (i.e., U and Fe) on the mineral surface. The proposed mechanism is the breaking of uranyl-organic bonds upon interaction with the mineral surface followed by the formation of Fe-organic bonds, thereby allowing the reduction of hexavalent uranyl to pentavalent one.

This study demonstrates a new system for the degradation of emerging pharmaceutical contaminants (e.g., ibuprofen) in water by coupling the naturally occurring ilmenite with hydroxylamine (HA) and persulfate (PS). Ilmenite was able to activate persulfate to generate sulfate radicals (SO4−·) and hydroxyl radicals (HO·). The radical generation was greatly improved by adding small amount of hydroxylamine into the solution, due to the efficient Fe(III)/Fe(II) cycle on the ilmenite surface promoted by HA, which was confirmed by X-ray photoelectron spectroscopy and electron paramagnetic resonance (EPR) spectroscopy analysis. SO4−· and HO· contributed comparably to ibuprofen degradation, which was verified by the radical scavenging tests. The degradation was enhanced with increasing ilmenite, PS and HA dosages, but the HA exhibited strong scavenging effect at its high concentrations. The ilmenite/PS/HA process worked well in the real treated wastewater, because the surface-controlled radical generation was less affected by the water matrix. However, the formation of bromate in the bromide-containing water by this process should be concerned. Ibuprofen was partially mineralized, and the degradation products were identified by ESI-tqMS. A radical-induced degradation pathway was proposed based on the product identification. This work provides the mechanistic insights on persulfate activation based on the surface-controlled catalytic processes. It also offers a new strategy to degrade emerging contaminants in water and sheds light on the environmental functions of natural minerals.

Chrome spinels in carbonate veins of the Onguren Complex, East Siberia, Western Baikal region are predominantly ferrichromite and chrommagnetite (MgO ≤ 0.3 wt %, Mg# ≤ 0.04, Al2O3 ≤ 2.5 wt %; Cr# 0.91–1.00, Fe2+/Fe3+ 0.8–1.4) with a high ZnO content (0.9–4.6 wt %). In the calcite vein, titanian chrome-magnetite is transformed into Cr-bearing titanomagnetite, which decomposes into Ti-depleted magnetite and ilmenite at temperature of 970–1000°С and $${{f}_{{{{{\text{O}}}_{{\text{2}}}}}}}$$ approximately of +0.5…+0.7 QFM. In the dolomite vein, ferrichromite and chrome-magnetite grains contain relict cores of subferrialumochromite (Al2O3 10.6–14.4 wt %, Cr# 0.63–0.73, Fe2+/Fe3+ 4.1–5.2, MgO ≤ 0.52 wt %) with elevated ZnO (3.7–5.1 wt %), TiO2 (3.2–4.1 wt %), and MnO (0.6–1.1 wt %). Ferrichromite and chrome-magnetite are formed during the high-temperature (>600°C) metamorphism of the vein. Superimposed deformations under greenschist facies conditions lead to the formation of magnetite rims around chrome-magnetite grains.

The transformation of CO2 to chemicals and fuels offers a means of CO2 utilization while mitigating the global carbon footprint. An attractive strategy involves the CO2 reforming of methane with ox...

The billions of tons of mineral dust released into the atmosphere each year provide an important surface for reaction with gas-phase pollutants. These reactions, which are often enhanced in the presence of light, can change both the gas-phase composition of the atmosphere and the composition and properties of the dust itself. Because dust contains titanium-rich grains, studies of dust photochemistry have largely employed commercial titanium dioxide as a proxy for its photochemically active fraction; to date, however, the validity of this model system has not been empirically determined. Here, for the first time, we directly investigate the photochemistry of the complement of natural titanium-containing minerals most relevant to mineral dust, including anatase, rutile, ilmenite, titanite, and several titanium-bearing species. Using ozone as a model gas-phase pollutant, we show that titanium-containing minerals other than titanium dioxide can also photocatalyze trace gas uptake, that samples of the same mineral phase can display very different reactivity, and that prediction of dust photoreactivity based on elemental/mineralogical analysis and/or light-absorbing properties is challenging. Together, these results show that the photochemistry of atmospheric dust is both richer and more complex than previously considered, and imply that a full understanding of the scope and impact of dust-mediated processes will require the community to engage with this complexity via the study of ambient mineral dust samples from diverse source regions.

Wumuite, ideally KAl0.33W2.67O9 , is a new mineral species found in the Neoproterozoic Sinian light-weathered biotite–quartz monzonite in the southern part of the Panzhihua–Xichang region (Nanyang village: 26 ∘ 46 ′ 8.21 ′′ N, 101 ∘ 27 ′ 13.86 ′′ E), China. It is associated with quartz, orthoclase, albite, biotite, hornblende, kaolinite, ilmenite, goethite, hematite, zircon, zoisite, tourmaline, monazite-(Ce), allanite-(Ce), scheelite, tellurite, tewite, and an unidentified, potentially new mineral corresponding to WO3 . Wumuite occurs as light green hexagonal tabular crystals, is up to 0.3 mm in diameter, and has a vitreous to adamantine luster and a white streak; i.e., it is transparent. The mineral is brittle with good cleavage parallel to { 10 1 ¯ 0 } and {0001} . It has a Mohs hardness of about 5–6 and a calculated density of 6.52 g cm−3 . Electron microprobe analyses yielded the following (in wt % – average of 10 spot analyses of one sample): K2O 5.55, WO3 91.16, TeO2 0.59, and Al2O3 2.52, with a total of 99.82. The empirical formula for wumuite calculated on the basis of Oapfu=9 is K0.80(W2.68Al0.34Te0.03)∑3.05O9 , ideally K(W2.67Al0.33)∑3O9 or KAl0.33W2.67O9 . The strongest four diffraction lines [ d A ( I ) (hkl)] are 6.261(36)(010), 3.727(30)(001), 3.161(100)(020), and 2.413(40)(021). Wumuite is hexagonal, in space group P 6/mmm, with a=7.2952(5) A, c=3.7711(3) A, V=173.81(2) A 3 , and Z=1 . The crystal structure was solved and refined to a reliability factor of R1 [ F 2 > 4 σ ( F 2 ) ] = 0.025 (wR 2=0.072 ) based on 164 unique reflections (777 measured reflections, R(int)=0.011 ). Wumuite has a hexagonal tungsten bronze (HTB)-type structure. The layers of corner-sharing [(W,Al)O]6 octahedra, with the layers oriented normal to the short (3.7713 A) c repeat and along with the W–O–W links, connect to form a hexagonal ring channel (tunnel). K is distributed in the hexagonal channel. An associated new mineral, tewite, which was discovered in the same area, also has a new tungsten bronze (TB)-type-related structure and has a genetic connection with wumuite in both back-scattered electron (BSE) images and synthetic experiments. The formation of wumuite is likely related to the nearby quartz-vein-type Au mineralization. The mineral was formed by a metasomatic reaction between W-rich hydrothermal fluids and the potassium feldspar in the monzonite.

The ilmenite-chloride process has used for the production of TiCl4 from the ilmenite (FeTiO3) ore, which produces cyclone dust containing mostly iron chloride and includes a range of metal chlorides. The utilization of iron values present in waste chlorides of cyclone dust is becoming a crucial issue to make this process competitive. The current work demonstrates a beneficial process that can selectively separate iron values from the chloride residue. Using CaCO3 as a precipitating agent, the iron component was selectively isolated from the aqueous solution of the chloride residues. The selective extraction of iron was carried out at a wide range of concentrations, and the yield of iron species was over 95%. The precipitate is in the form of Fe(OH)3, which converts to Fe2O3 when annealed in air. In the next step, the remaining metal impurities were removed as solid precipitates through the pH tuning with CaO. Finally, CaCl2 and CaCO3 were obtained by adding CO2 to the residual solution. This study provides a method of treating cyclone residues to recover CaCl2 as well as Fe(OH)3, which represents significant progress towards the utilization of iron-rich wastes.

Ilmenite is the prime mineral used for the production of titania-rich slag and ferrotitanium alloy throughout the globe. In the current research, a 30 kW DC extended arc plasma reactor is employed for the aluminothermic reduction of ilmenite into ferrotitanium. For low-temperature operation, flux is added targeting low melting slag where CaO/Al2O3 ratio is varied from 0.8 to 1.6. Further, to lower down the Al consumption, carboaluminothermic reduction tests are carried out in stages without interruption. The effect of stage-wise reductant addition and CaO/Al2O3 ratio on ferrotitanium yield and titanium recovery is studied, corroborated to the slag chemistry. FeTi26 alloy is obtained through the carboaluminothermic smelting route with 25% excess stoichiometric Al in charge composition. The formation of calcium titanate and calcium aluminates governs slag chemistry and reduction kinetics.

The effects of corrosion temperature, oxygen flow rate and corrosion time on the transformation of metallic iron were systematically studied, and the effects of mineral phases of Fe-bearing products on Ti–Fe separation were investigated. The reaction mechanism of metallic iron in corrosion process was proposed. The results showed that corrosion temperature played a key role in determining the transformation of metallic iron in reduced ilmenite during corrosion process. Under suitable corrosion conditions, Fe-bearing mineral in reduced ilmenite could be converted to amorphous ferric hydroxide, lepidocrocite, hematite and magnetite, respectively, and lepidocrocite was the most easily separated Fe-bearing mineral from corrosion products owing to the significant density difference between lepidocrocite and Ti-rich materials. The Ti-rich material with 77.81 wt.% TiO2 and Fe-bearing product with 52.69 wt.% total Fe were obtained by gravity separation. The Ti recovery ratio and Fe recovery ratio were 91.16% and 86.27%, respectively.

Titanium-bearing magnetite ore is generically defined as magnetite with > 1% titanium dioxide (TiO2) and is usually vanadium-bearing. The iron and titanium occur as a mixture of magnetite (Fe3O4) and ilmenite (FeTiO3) with vanadium oxide usually occurring within the solid solution of the titanium-bearing magnetite phase. These ores are currently widely processed in blast furnaces via modified ironmaking processes. Typically, vanadium is recovered as a by-product from the ironmaking process, while the diluted titania slag is stockpiled. Fluxless smelting in a direct-current open-arc furnace is proposed as an opportunity to improve iron and vanadium recovery and potentially unlock the titanium as a slag product. Slags produced from a pilot study are compared to industrial slags produced from ilmenite. The findings from the pilot test show that slag produced under fluxless smelting conditions in an open-arc electric furnace is remarkably similar to industrial ilmenite slags. The test conditions were varied to evaluate the slag and metal composition, and furnace operation, under increasing reducing conditions. The study showed that the slag and metal product was remarkably similar to industrial slag produced from ilmenite.

Sulfur contamination in coal is an important issue that needs to be handled carefully in the coal chemical-looping combustion process. Sulfur impurities can damage oxygen carriers and decrease thei...

Carbonization of TiO2, which is a process typically used to synthesize TiC, consumes a huge amount of energy. Low-temperature synthesis of TiC from carbon-infiltrated TiO2 has been investigated in this study to develop an energy-saving process. Porous TiO2 was first obtained by hydrochloric acid leaching of ilmenite (FeTiO3) ore. Then, carbon-infiltrated TiO2 was prepared from the porous TiO2 using a tar impregnation method, and its reaction behavior was observed. The carbon-infiltrated TiO2 was completely converted into TiC which contained 3.0 mol pct oxygen at 1300 °C for 2 hours. In contrast, a mixture of reagents TiO2 and carbon did not react when it was subjected to the same treatment. This major difference is due to the effect of close contact between TiO2 and carbon through the nanopores generated in TiO2 obtained by acid leaching of ilmenite ore. It was concluded that this method has significantly lower temperature and much shorter reaction time than those of conventional methods.

The effects of adding 5 to 25 wt pct of ilmenite ore to hematite ore sinter were investigated employing a horizontal tube furnace to clarify the phase development. The temperature was raised nonisothermally at 10 °C/min to 1150 °C in an Ar atmosphere. When the target temperature was reached, 1 L/min of air was injected to allow combustion of the carbon in the pellets. The development of the phases in the sinters was studied using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and electron probe microanalysis (EPMA). The tumbler index (TI) decreased with the increase in ilmenite addition up to 20 wt pct, which increases TiO2 (s) and Fe3O4 (s) content in the sinter blends. Addition of more than 2 wt pct TiO2 (s) to the sinter blends resulted in the formation of perovskite (CaO·TiO2), which affected the development of bonding phases. These changes deteriorated the reduction degradation index (RDI). The estimated melt formation temperature of the sinter blends increased with ilmenite addition up to 15 wt pct and decreased thereafter. An attempt was made to predict the development of phases in the ternary phase diagram of CaO-Fe2O3-TiO2. The reduction behavior of the sinter blends was affected by the type of the bonding phase.

A simple and novel technique for the preparation of anatase TiO2 nanopowders using natural ilmenite (FeTiO3) as the starting material is reported. Digesting ilmenite with concentrated H3PO4 under refluxing conditions yields a white α-titanium bismonohydrogen orthophosphate monohydrate (TOP), Ti(HPO4)2·H2O, which can be easily isolated via gravity separation from unreacted ilmenite. The addition of ammonia to the separated TOP followed by calcination at 500°C completes the preparation of anatase TiO2. Calcination at temperatures above 800°C converts the anatase form of TiO2 to the stable rutile phase. The removal of iron from ilmenite during the commercial production of synthetic TiO2 is problematic and environmentally unfriendly. In the present study, the removal of iron was found to be markedly simple due to the high solubility of iron phosphate species in concentrated H3PO4 with the precipitation of TOP. The titanium content of the prepared samples on metal basis with silica and phosphorous as major impurities was over 90%. Prepared TiO2 samples were characterized using X-ray fluorescence, Fourier-transform infrared spectroscopy, Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, high-resolution transmission electron microscopy, and X-ray diffraction analyses. The photocatalytic potentials of the commercial and as-prepared TiO2 samples were assessed by the photodegradation of rhodamine B dye.

The current rate of industrial production of titanium dioxide, from natural ilmenite, is around 6500 kT per annum. The two main processes used, namely, sulfate and chloride processes, require concentrated corrosive acids and drastic conditions, such as 1000 °C, in open processes, thus contributing to considerable costs and environmental pollution. To reduce the cost and impact to the environment, a closed process involving a rotatory autoclaving followed by refluxing and stationary solvothermal treatment of ilmenite, below 170 °C, was developed. The as-synthesized product is 100% pure titanium dioxide in its amorphous state (24% crystallinity), which has nanorods arranged in a flowerlike morphology. This can be converted to over 99% pure anatase phase with 90% crystallinity and 100% pure rutile phase nanorods with 98% crystallinity by calcining at 350 and 650 °C, respectively. The direct band gaps of the three materials are 3. 40, 3.60, and 3.15 eV, respectively.

The formation of calcium titanate in the carbothermic reduction of vanadium titanomagnetite concentrate (VTC) by adding CaCO3 was investigated. Thermodynamic analysis was employed to show the feasibility of calcium titanate formation by the reaction of ilmenite and CaCO3 in a reductive atmosphere, where ilmenite is more easily reduced by CO or carbon in the presence of CaCO3. The effects of CaCO3 dosage and reduction temperature on the phase transformation and metallization degree were also investigated in an actual roasting test. Appropriate increase of CaCO3 dosages and reduction temperatures were found to be conducive to the formation of calcium titanate, and the optimum conditions were a CaCO3 dosage of 18wt% and a reduction temperature of 1400°C. Additionally, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) analysis shows that calcium titanate produced via the carbothermic reduction of VTC by CaCO3 addition was of higher purity with particle size approximately 50 µm. Hence, the separation of calcium titanate and metallic iron will be the focus in the future study.

The article provides a detailed analysis of research results on the use of various types of titanium raw materials from Russian deposits: primary (titanomagnetite, ilmenite-titanomagnetite), metamorphosed (buried leucoxene and ilmenite-leucoxene sandstones) and complex zircon-rutile-ilmenite placers. All titanium deposits in Russia are characterized by low ore quality, which does not meet technological requirements for the production of pigment TiO 2 and metallic titanium. Main deposits are based on titanomagnetites containing from 3 to 17 % of TiO 2 . Ilmenite is in a subordinate position. Leucoxene sandstones of the Yarega deposit have high titanium content (about 10 %o TiO 2 ). But when they are dressed by known methods, low-quality high-silicon leucoxene concentrates are obtained containing 40 - 50 %o TiO 2 with significant titanium losses. Ilmenite-leucoxene sandstones of the Pizhemskoe deposit contain 3 - 10 %o of TiO 2 . The main titanium-containing phases are pseudorutyl Fe 2 O 3 3TiO 2 and leucoxene. The cementing binder of grains in sandstones is siderite with magnetic properties, which greatly reduces the degree of minerals disclosure during crushing and worsens the conditions for ore dressing in general. Ilmenite-bearing placers consist of fine-grained disseminated ilmenite and are difficult to concentrate. Complex zircon-rutil-ilmenite placers are infected with chromium and other undesirable impurities, which do not allow existing dressing methods to obtain a conditioned ilmenite concentrate. The main problems of using hard-to-concentrate titanium ores of all the above types of deposits and scientifically based ways to solve them are discussed. It is aimed at obtaining high-quality raw materials for the production of titanium metal and pigment TiO 2 with the simultaneous extraction of other valuable components. Particular attention is devoted to studies on the use of mass complex raw materials - titanomagne-tites, which are allocated in three phased directions, lasting for about 200 years - from the beginning of the XIX century to the present.

The activity of polyvalent elements in the geochemical processes is to a considerable extent determined by the valence state. A change in the valence is dependent on many factors, but the redox conditions of the medium where magma is generated are considered the main factor. The ratio between divalent and trivalent iron in magmatic rocks is a reliable and an accessible indicator of the redox conditions that determine a whole set of mineralogical, geochemical and physical parameters including ferruginosity of dark-colored minerals, the ore mineral (magnetite–ilmenite) composition, the weight of the ore fraction, and magnetic susceptibility. Based on the above parameters, the zones are distinguished where magmatic rocks of the magnetite and ilmenite series are developed in the Sikhote Alin Orogenic Belt. All known tin and tungsten deposits and occurrences in the Sikhote Alin are confined to the ilmenite series (the axial zone of the belt). The ilmenite rock series are framed by the magmatic rocks of the magnetite series; the epithermal gold–silver and copper–porphyry deposits are associated with these rocks.

In this study, we have developed a novel method for ilmenite activation. Sodium hypochlorite was used as an oxidant and surface modifier to promote ilmenite flotation. And it has successfully been performed valence transitions of iron atoms on the ilmenite surface, thereby enhancing the action activity between the surface sites of ilmenite and sodium oleate. Eventually the surface Fe3+ content increased from 42.15 to 63.79%. Oxidation by sodium hypochlorite increased the amount of Fe3+ on the ilmenite surface by 21.64% and improved the ilmenite recovery to 95%, while the maximum recovery of ilmenite without sodium hypochlorite addition was only 85%. The activation mechanism of ilmenite by sodium hypochlorite was studied by batch flotation, Zeta potential measurement, X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and reaction thermodynamic analysis. The results of potential measurement show that sodium hypochlorite made the Zeta potentials of ilmenite–sodium oleate system more negative mainly due to the enhanced adsorption effect between them. FTIR results indicate that more prominent absorption peak of iron oleate appeared in the FTIR spectrum of ilmenite treated with sodium oleate after sodium hypochlorite oxidation. XPS analyses suggest that more Fe2+ on ilmenite surface supplied electrons to the oxidant and formed more Fe3+. Reaction thermodynamic analyses also show that compared with Fe2+, Fe3+ was more likely to interact with oleate ions and formed more stable species. In summary, sodium hypochlorite can activate ilmenite and improve its flotation.

The data on investigation of the possibility of breakdown of ilmenite concentrate of the Ariadnensky deposit in Primorsky Krai with ammonium sulfate are presented in the article. For study the ilmenite concentrate and ammonium sulfate interaction, the concentrate and (NH4)2SO4 were mixed based on the formation of sulfates of the main components of the concentrate and then double sulfates of the components of the concentrate and ammonium. The interaction was carried out in glassy carbon crucibles, which were placed in a muffle furnace controller company Nabertherm GmbH (Germany). The weight of sample was 10–40 g. Thermogravimetry, X-ray diffraction and atomic absorption analyses were used in the study. It was found that when the temperature of thermal decomposition of (NH4)2SO4 (3000С) is reached, the interaction of the main components of the concentrate with (NH4)2SO4 begins and proceeds in the temperature range of 300-3600С with the formation of a mixture of double salts well soluble in water - ammonium sulfate and iron compounds (NH4)2Fe2(SO4)3 and NH4Fe(SO4)2 and ammonium sulfate and titanyl of the composition (NH4)2TiO(SO4)2. The interaction at a temperature above 3600С leads to thermal decomposition of the formed double sulfates of ammonium and titanyl and ammonium and iron to sulfates and then oxides. It was shown that water leaching of the product of the interaction of ilmenite concentrate with (NH4)2SO4 at 3600С allows to extract practically all titanium and the bulk of iron to water in the form of well soluble double salts. The conditions for the titanium dioxide separation in the form of anatase from the water leaching solution were found.

Pollution prevention and treatment of reservoir silt constitute important environmental protection challenges. Scandium, a key metal, is found in Chinese reservoir silt. However, due to the low scandium content and complex composition of the silt, it is not feasible to directly extract this valuable constituent. With the aid of scanning electron microscopy and polarizing optical microscopy analyses, samples of silt were examined and the different types of minerals containing scandium identified together with their disseminated features. The results reveal that the silt is a high silicon, calcium, magnesium, aluminum vein ore, containing a small amount of iron and titanium complex mineral groups, among which ilmenite and titanaugite are the main minerals containing scandium. The raw silt contains about 6.6 g/t scandium. Based on the silt composition, particle size distribution, and occurrence state of scandium, studies were conducted on preconcentration of scandium oxide from reservoir silt. Based on the results of these experiments, a beneficiation process was developed and validated on pilot scale based on the use of electrical separation for scandium enrichment. A scandium concentrate was obtained with scandium content of 96.23 g/t and recovery of 62.11 wt.%.

A hydrochloric acid leaching solution of ilmenite contains Fe(III) and Ti(IV) and small amount of Mn(II) and Si(IV). Solvent extraction was employed to separate Ti(IV) and Fe(III) from the leaching...

Congruently grown LiNbO3 (LiTaO3) is known to be highly defective due to its significant Li2O deficiency. We present in this work a comparative study between normal LiNbO3 (LiTaO3) and ilmenite structural LiNbO3 (LiTaO3). Namely, the normal cation stacking sequence is replaced by ilmenite ordering ‘…Nb (Ta) Li vacancy Li Nb (Ta) vacancy Nb (Ta) Li vacancy Li Nb (Ta) vacancy…’. From Safaryan’s approach which combines a ferroelectric phase transition theory and vacancy models, we calculated the Curie temperature in ilmenite LiNbO3 (LiTaO3). We have shown that ilmenite structural LiNbO3 (LiTaO3) is in excellent agreement with the result of the experiment compared to normal LiNbO3 (LiTaO3).

Processing of titanium-containing ores together with the extraction of all the major elements is currently an urgent problem for the usage of mineral products. It is shown that none of the existing processing schemes allows the simultaneous extraction of all the major useful elements such as iron, titanium and vanadium from titanium-containing iron ores. This problem can be solved using a selective extraction of these elements based on ideas regarding the electron reduction mechanism. The following has been experimentally studied: the reaction propagation of solid-phase selective iron reduction that is deep in the grain layer of ilmenite concentrate from the surface of its contact with the powder of carbon-containing material. The results are presented for determining the amount of released metal phase depending on the distance from the concentrate–reducing agent contact boundary. Based on the results regarding the amount of the released metal phase, a conclusion was made for the diffusion processes in a layer of concentrate grains that contact only between themselves, thus determining the rate of iron reduction process. It is shown that near the contact surface between the solid reducing agent and the layer of concentrate grains, the rate of iron reduction is higher than the formation rate of the phases with high iron content from ilmenite. Deep in the ilmenite concentrate layer, the process of iron reduction is preceded by the formation of an iron-containing silicate phase from the concentrate grains, where iron is reduced earlier than it is in the ilmenite grains. The formation of iron-containing silicate phase promotes ilmenite grains to be sintered. Thus, upon the concentrate layer contacting with solid reducing agent in the absence of contact between each ilmenite grain and solid reducing agent, the point contact between grains and void presence within the layer do not prevent the reduction process propagation in the grain layer that contact only with each other.

In this work, in-situ application of natural occurring ilmenite (FeTiO3) for upgrading the producer gas from a pilot-scale bubbling fluidized bed gasifier was performed and its influence on the gas characteristics and gasifier performance was analyzed. Without using ilmenite, the producer gas average composition (volumetric basis, dry gas) was 15.2% CO, 7.6% H 2 , 3.8% CH4 and 15.6% CO2, with 0.50 H 2 :CO molar ratio and 5.0 MJ/Nm3 lower heating value. For this condition, 1.6 Nm3 gas/kg biomass (dry basis) specific dry gas production, 44.5% cold gas efficiency and 68.4% carbon conversion efficiency were attained. Using ilmenite as catalyst, the producer gas average composition (volumetric basis, dry gas) was 13.9% CO, 11.7% H 2 , 4.0% CH4 and 17.9% CO2, with 0.84 H 2 :CO molar ratio and 5.1 MJ/Nm3 lower heating value. For this condition, 1.7 Nm3 gas/kg biomass (dry basis) specific dry gas production, 49.8% cold gas efficiency and 75.5% carbon conversion efficiency were attained. Thus, in-situ application of ilmenite generally improved the gasifier performance and induced an increase of H 2 concentration and H 2 :CO molar ratio in the producer gas of 35.1% and 40.7%, respectively, improving its suitability for advanced gas applications that require high H 2 :CO ratios, such as liquid fuels and chemicals synthesis.

This article introduces research on the synthesis and characteristics of C–TiO2 doped cellulose acetate (CA) nanocomposite film. TiO2 nanoparticles were synthesized from Ilmenite mineral in Binh Dinh, Vietnam, and modified by Stevia Rebaudiana plant in order to serve as a cheap, stable, and eco-friendly photocatalyst that could perform under visible light. Nanocomposite film was obtained by dispersing C–TiO2 on cellulose acetate polymer using a supersonic generator. The prepared material was characterized by X-ray diffractions (XRD), N2 adsorption, Raman spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray analysis (EDX), UV–Vis diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence (PL) emission spectra, scanning electron spectroscopy (SEM), and thermogravimetric/differential thermal analysis (TG-DTA). The film’s photocatalytic efficiency was evaluated via the decomposition of Reactive Red-195 (RR-195) under visible irradiation at room temperature. The results showed that the maximum conversion of RR-195 reached 99.15% at pH = 3 and the activity of the catalyst had a slight decrease after up to four times of recycling, for which the conversion of the fourth reaction was 90.02% for RR-195. This result suggests an efficient treatment method to eliminate organic pollutants from wastewater and stimulate these industrial activities in Vietnam.