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The behavior of Ti-Nb-Ta is crucial to reveal the genesis of island arc magmatism. However, mobilization and fractionation of Ti-Nb-Ta in subduction zone settings remain poorly understood. The discovery of felsic veins rich in coarse-grained rutile within retrograde eclogite of the North Qaidam UHP metamorphic belt provides a unique and novel opportunity to study age variation during rutile formation and alteration, as well as Ti-Nb-Ta mobility and fractionation during fluid/melt-rock interaction. Rutile high-resolution elemental mapping, and U-Pb bulk grain (ID-TIMS), and in-situ U-Pb geochronology have been utilized to focus on the properties of rutile in both, felsic vein and retrograde eclogite host to gain insight into possible similarities and differences. Three groups of rutile were distinguished according to its host rock, trace elements signature, and genetical connection to ilmenite: eclogite-hosted rutile (Rt-1), felsic vein-hosted rutile not associated with ilmenite (Rt-2a), and associated with ilmenite (Rt-2b). Field evidence and rutile trace elements characteristics document the source of vein-hosted rutile to be mainly derived from the eclogite during fluid/melt-rock interaction. Principal Component Analysis reveals that Nb, Ta, Sn, and W are more enriched in Rt-2a compared to Rt-1; Rt-2b has higher Nb, U, and Hf than Rt-2a. High-resolution mapping across large rutile grains shows the enrichment of high field strength elements (HFSEs) in rutile near to ilmenite, which indicates a HFSEs back diffusion from the rutile–ilmenite boundary during the replacement of rutile by ilmenite. The Nb/Ta ratios of Rt-2a are lower than those of Rt-1, which result from different partition coefficients of Nb and Ta during fluid/melt-rock interaction. The diffusion-influenced rutile exhibits suprachondritic Nb/Ta ratios and demonstrates that diffusion of Nb in rutile is higher than that of Ta under identical P-T conditions. Rutiles Rt-1 and Rt-2a yield consistent 206Pb/238U ages of 426-423 Ma, which is similar to the 433 ± 3 Ma determined by ID-TIMS results of bulk rutile grains. This indicates that Ti-Nb-Ta must have been mobilized during the exhumation of deeply subducted continental crust. However, the diffusion-influenced rutile shows a large variation of ages compared to the rutile not associated with ilmenite, demonstrating that the back-diffusion may affect the U-Pb system in rutile. Therefore, when rutile is partially altered into ilmenite or titanite, its dating should be used with caution. Thus, this study demonstrates volume diffusion is a very important geological process to result in extreme HFSEs fractionation and age variation of rutile on the mineral scale. The rutile aggerates that occur in the felsic veins in 3-5m distance to the adjacent retrograde eclogite suggest that Ti-Nb-Ta-rich melts/fluids were transported over a distance of at least several meters and that rutile does not represent a residual phase of the Na-Si-Al-, F- and CH4-bearing fluid/melt environment that formed during anatexis of the subducted continental crust. The formation of rutile-rich aggregates during the generation, transport, and crystallization of subducted continental crust-derived melts/fluids in the deep roots of orogenic belts may be a critical trigger for the depletion of HFSEs in arc magmatic rocks during the formation of the continental crust.

Aluminum matrix composites (AMCs) are extensively using in different fields such as defense automotive, marine, electronics and automobile sectors because of their impressive mechanical properties. This study aims to investigate the tribological and corrosion behavior of AA6061 alloy with the reinforcement of ilmenite (FeTiO3) particles. AA 6061-(FeTiO3) composites were fabricated througha stir casting process with AA 6061 as matrix material and ilmenite (FeTiO3) particles in different wt.% (5%, 10% and 15%) as reinforcement. In this investigation, the composites' properties like hardness, wear behavior, coefficient of friction and pitting corrosion behaviour were evaluated. From these tests, it is noticedthat hardness increased and wear rateand coefficient of friction decreased with the addition of ilmenite as reinforcement in AA6061 alloy. Pitting corrosion resistance of composites with 10%ilmenite is better than remaining composites and base metal.

In this study, AMCs have been prepared by incorporating natural mineral ilmenite (FeTiO3) into base alloy Al–Si17Cu4Mg through stir casting process. Three different size ranges of ilmenite viz. 75–106, 50–75, and 32–50 µm were used to fabricate the composites. The micro-hardness test on different phases has shown good interfacial bonding between the ilmenite particles and the Al–Si17Cu4Mg aluminum matrix. Wear test was carried out at different applied loads ranging from 1 to 7 kg and at sliding velocity of 1.6 m/s to study the influence of particle size range. At an applied load of 1–7 kg, the wear rate was improved by nearly 38% in the run-in wear region and nearly 28% in the steady-state region when compared with base alloy. Moreover, composite containing 15 wt% ilmenite (32–50 µm) has shown maximum improvement in wear resistance more than 50% at all applied loads as compared to Al–Si17Cu4Mg alloy. The wear rate of cast iron used for different automobile applications was also measured and compared with 15 wt% (32–50 µm size) ilmenite-reinforced composite. It was nearly 8% and 5% lower at 1 and 7 kg applied load, respectively. The coefficient of friction of 15 wt% composites reinforced with the ilmenite particles (32–50 µm) was 48 % and 29 % less than Al–Si17Cu4Mg alloy at 1 and 7 kg applied load, respectively. The microstructural analysis of worn surfaces revealed the abrasive and adhesive wear mechanism as the predominant factor of material losses.

X-ray spectral studies of the chemical composition of Irshansk ilmenite concentrates showed that it is leukoxenized mineral with a high (up to 79%) content of titanium oxide and inclusions of pseudorutile. The process of alkaline leaching of Ti4+ from ilmenite is investigated in the work. The study of the temperature effect on the reaction of ilmenite with potassium hydroxide at atmospheric pressure revealed that a temperature of 453 K is sufficient to obtain potassium titanate. A further increase in temperature does not provide a significant increase in the yield of water-soluble titanium. It is found that the optimal and sufficient ratio between ilmenite and potassium hydroxide is 1:2. An increase in the amount of potassium hydroxide in the reaction mixture is unsuitable, since it reduces the yield of soluble titanium and the final product will have a high alkalinity due to the presence of alkali which did not react. The main process of leaching with the formation of solid melt is completed in the first 30 minutes of the process. Infrared spectroscopy and X-ray diffraction showed that potassium titanate (K2TiO3) is formed under the studied conditions of alkaline leaching of ilmenite.

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.

The kinetics and mechanisms of carbothermic reduction of a complex Kalimantan weathered ilmenite (FeTiO3) using palm kernel biomass were investigated in the temperature range 1273–1473 K. The study included a combined thermodynamic assessment together with reduction experiments. Results were contrasted with data from similar experiments conducted using graphite as the reductant. Thermodynamic simulations showed that the major phases formed during reduction were pseudobrookite and metallic iron with reduction using biomass predicted to produce more metallic iron compared to the use of graphite in the same temperature range. Incomplete dissociation of ilmenite by biomass was noted at 1473 K and 30 min reaction time however increasing the reaction time to 180 min resulted in near complete ilmenite dissociation. The kinetic analysis indicated that the reduction process followed a diffusion-controlled mechanism. This was confirmed by a microstructural analysis that showed the reduced ilmenite grains had a three-layer structure. The microstructural analysis also revealed that pores and cracks present in the initial weathered ilmenite promoted metallic iron formation. The apparent activation energy for ilmenite reduction using biomass and graphite was determined to be 217.00 ± 0.06 kJ mol−1 and 239.44 ± 0.06 kJ mol−1, respectively. Based on the findings, a general micro-mechanism for the carbothermic reduction of weathered ilmenite was developed.

The influence of slag composition of FeO/TiO2 (=F/T) ratio, Al2O3/(SiO2+Al2O3) (=A/(S+A)) ratio and oxygen partial pressure ( p O 2 = 10 − 10 t o 10 − 9 a t m ) on the thermodynamic behavior of vanadium oxide in molten ilmenite smelting slag, i.e., FetO-TiO2-MgO-Al2O3-SiO2 system, was investigated at 1550 °C. The distribution ratio of vanadium (= L V ) between molten iron and FetO-TiO2-MgO-Al2O3-SiO2 slag increases with increasing F/T ratio, while it decreases with increasing A/(S+A) ratio. In addition, l o g L V generally increases with increasing theoretical optical basicity of the slag (= Λ s l a g ). Vanadium oxide (VOx) is expected to behave as an acidic component in the present system. Vanadium in ilmenite smelting slags primarily consist of V3+, V4+, and V5+ ions, as determined by Gaussian deconvolution of X-ray photoelectron spectra. A linear relationship between l o g ( w t % V 4 + / w t % V 3 + ) and l o g p O 2 is confirmed. Both (wt% V3+) and (wt% V5+) ions increase with increasing F/T ratio, whereas (wt% V4+) ions show the opposite behavior with increasing F/T ratio, irrespective of A/(S+A) ratio. Meanwhile, (wt% V3+) increase while (wt% V4+) and (wt% V5+) decrease with increasing A/(S+A) ratio. The linear relationship between l o g ( w t % V 3 + / w t % V 5 + ) and l o g ( w t % V 4 + ) has a slope of 1.8, which is good agreement with the theoretical slope of 2.0, which indicates that multi-valent vanadium ion species, i.e., V3+, V4+, and V5+, are thermodynamically balanced based on redox equilibria.

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.

Investigation of the pegmatites of Keffi area was carried out in reflected light microscopy to determine the texture, elemental composition, and the semi-quantitative analysis of the ore minerals from the three groups of pegmatites identified in Keffi area: the non-mineralised, the intermediate and the mineralised pegmatites. Backscattered Electron (BSE) images and Wavelength Dispersive Spectrometry (WDS) were used. Petrographically the portion which is characterised by profuse albitisation, sericitisation and silicification is also associated with the development of cleavelandite, lepidolite, coloured tourmaline and high concentrations of cassiterite and columbite-tantalite (coltan).The order of crystallisation in the pegmatites is from microcline to quartz followed by (plagioclases) oligoclase to albite and by mica (from biotite to muscovite) then by accessory minerals such as black tourmaline, garnet, beryl and lastly oxides of Sn-Nb-Ta. Sphene, rutile, zircon, apatite, ilmenite, and magnetite appeared to be earliest minerals whilst garnet pyrite and chalcopyrite may be syn-metamorphic. Beryl and coloured tourmaline appear to be of hydrothermal phase.

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 effect of conventional thermal pretreatment on the surface properties of ilmenite and its accompanied gangue minerals was investigated using flotation experiments (microflotation and laboratory cell flotation), XRD, XPS and FT-IR analysis and zeta potential and contact angle measurements. After treatment at 600 °C for 25 min as optimal condition, the floatability of ilmenite is improved from 73.5% to 91% at a pH value of 6.3. As demonstrated by XRD and XPS analysis, under this pretreatment condition, the Fe3+ content increases by almost 16.5% without any phase decomposition and structural changes in ilmenite. FT-IR analysis and contact angle and zeta potential measurements give evidences that the improvement of ilmenite floatability can be related to the enhancement of collector adsorption and the formation of a more insoluble hydrophobic layer of ferric iron oleate. The ore flotation experiments show that the thermal pretreatment process without making a significant change in TiO2 content of ilmenite concentrate enhances the TiO2 recovery from 65.4% to 73.7%.

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.

A study is performed of the mechanism behind the effect high-voltage nanosecond electromagnetic pulses and dielectric barrier discharges have on surfaces of ilmenite in air at atmospheric pressure. Fourier-transform infrared spectroscopy, scanning electron microscopy, electron microprobe analysis, microhardness testing, contact angles of surface wetting, and streaming potentials are used to examine the morphology of ilmenite, its physicochemical properties (microhardness, contact angle, and electrokinetic potential), and the structural state of ilmenite surfaces. Advantages are shown of using brief energy treatments (ttreat = 10–30 s) to modify the chemical structure of surfaces of ilmenite and its physicochemical properties in order to improve the efficiency of processing complex titanium ores.

Hematite was recently introduced as a weighting agent in drilling fluids; however, its use has some problems because of the settlement of solid particles (solid sagging). Particularly when it comes to high-pressure high-temperature (HP/HT) wells, sagging causes inconsistency in the drilling fluid and gives rise to serious drilling operational and technical challenges. This work provides a solution to this challenge via a thorough investigation of hematite sagging in water-based mud for HP/HT applications where ilmenite is combined with hematite. The particles of both hematite and ilmenite were first characterized to address their mineralogical and textural features. Field mud formulation was employed using several ilmenite/hematite contents (i.e., 0/100, 25/75, and 50/50% ilmenite/hematite). Then, laboratory experiments were conducted to study the density, pH, and sag performance of the produced drilling fluids. From the sagging tests, the optimal ilmenite/hematite ratio was determined, and rheology, viscoelastic behavior, and filtration properties of the formulated mud were addressed. The tests were conditioned to 300 psi and 250 °F. The results showed a reduction in mud density and pH with increasing ilmenite content, as the density reduced from15 ppg with base hematite until 14.2 ppg for the 50% ilmenite mixture and the pH reduced from 10.5 to 9.3. The static and dynamic sag tests indicated that the addition of 25% of ilmenite solved the hematite-incorporated sagging issue by well placing the sag tendency within the recommended safe range. The 25/75% combination enhanced the yield point (YP) by 37% with only 1 cP increment in plastic viscosity (PV) and an insignificant effect on the gel strength. The YP/PV ratio was improved by 31% indicating better hole cleaning and solid suspension. The filtration behavior of the 25% ilmenite mixture was superior compared to that of the blank hematite because it resulted in 35, 39, and 35% reduction in the filtrate volume, filter-cake weight, and thickness, respectively. This work contributes to improving and economizing the drilling cost and time by the formulation of a stabilized and distinguished-performance drilling mud using combined weighting agents at HP/HT.

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 summarizes authors' earlier and newly obtained experimental data on the formation of phlogopite and chromium-bearing potassium titanates of the crichtonite, magnetoplumbite, and hollandite groups, which are indicator minerals that characterize various stages of modal metasomatism in the upper mantle. Phlogopite-forming reactions were studied in the garnet–orthopyroxene system in the presence of H2O–KCl fluid at 3 and 5 GPa and 900–1000°C as simulating phlogopite formation in garnet peridotites and pyroxenites. Experiments have demonstrated regular variations in Ca and Cr contents in the garnet and Al in the pyroxenes, as well as the composition of the newly formed phlogopite, depending on the concentration of the potassium component (KCl or K2CO3) of the fluid. Experiments on the formation of potassium titanates (yimengite, mathiasite, and priderite) in the chromite–rutile/ilmenite–K2CO3–H2O–CO2 system at 3.5 and 5 GPa and 1200°C have proved that these minerals can be formed when chromite reacts with potassic aqueous–carbonic fluid, but these reactions require additional sources of titanium. These sources may be rutile and/or ilmenite, which are usually also produced by modal metasomatism of peridotites. The experiments thus confirm that the formation of titanates marks the most advanced stages of metasomatism in mantle peridotites. The experiments have shown that the formation of potassium titanates follows the formation of phlogopite, whereas assemblages of the titanates with phlogopite are produced at higher concentrations of the potassium component of the fluid than phlogopite alone. The relationships between the titanates are also a function of the activity of the potassium component in the fluid and, probably, pressure. The relationships and trends reproduced in the experiments clearly illustrate features of mineral assemblages and variations in compositions of minerals from metasomatized peridotites in the lithospheric mantle.

A review of the data available on the composition and abundance of titanium-bearing phases in the Earth’s mantle is provided in the paper. The main attention is paid to the discussion of natural minerals: the patterns of the mineralogy of mantle titanium-bearing phases (rutile, FeTiO3 ilmenite, garnet, pyroxene, spinel and post-spinel phases, phases with ilmenite- and perovskite-type structures, armalcolite) are given, the likely mechanisms of titanium incorporation into mantle phases, as well as the limiting titanium concentrations in these phases are considered. The new experimental data on the composition and conditions of the formation of titanium-bearing minerals and their phase associations at different mantle depths is generalized: phase relations in Ti-bearing systems (MgO–SiO2–TiO2 ± Al2O3) and the influence of titanium on the parameters of the most important phase transformations under the conditions of the mantle are considered. Agreement of the experimental results with the natural data allows us to clarify the patterns of the interphase titanium partitioning and the minor-element composition of the Earth’s deep geospheres.

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.

Background Ilmenite and rutile are naturally occurring titanium-bearing heavy minerals. Sri Lanka consists of ilmenite and rutile in placer deposits mainly along the northeast coast. The commercial value of rutile is higher than ilmenite. Therefore, the current study focuses to upgrade Sri Lankan ilmenite ores using commercially available activated carbon as a reducing agent. Ilmenite fraction was initially separated from raw beach sand using an industrial-scale magnetic separator (Wet high-intensity magnetic separator: sixteen pole model). The mixtures of ilmenite and activated carbon (4 to 1 ratio by weight) were milled using a planetary ball mill for one to four hours at one-hour intervals. Results The milled samples were subsequently heated for two hours continuously at temperatures of 800 °C, 900 °C, 1000 °C, 1100 °C, and 1200 °C, respectively. Initial and annealed samples were analysed using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and X-ray fluorescence (XRF) analyses. XRD pattern of the initial sample was characterized by less percentage of rutile (TiO2) peaks and low crystallinity. However, the number of rutile peaks and crystallinity were increased with respective milling hours and annealed temperature. Besides, XRD analysis indicates a higher number of sharp and intense rutile and elemental iron peaks in the samples annealed above 1000 °C. FTIR analysis of raw ilmenite indicates mainly stretching vibrations of Fe–O. However, vibrational spectral bands around 700 cm−1 in samples annealed above 1000 °C are assigned to Ti–O–Ti stretching vibrations. High TiO2 and TiO2 + Fe2O3 (total) wt. (%) can also be observed in samples annealed above 1000 °C. Conclusions The optimum conditions for carbothermic reduction were obtained at 4 h of ball milling of ilmenite with activated carbon and continuously annealing at 1000 °C for 2 h. Carbothermic reduction is applicable to upgrade Sri Lankan ilmenite ores, and thus this method adds value to heavy mineral resources in Sri Lanka.

Electro-deoxidation of ilmenite (FeTiO3) is an economical production method of FeTi, particularly, if the end use is hydrogen storage. In this study, we show that electro-deoxidation of impure FeTiO3 with Ti content lower than Fe, as in the case of low-grade FeTiO3 ore, results in the formation of a two-phase material consisting of FeTi and Fe2Ti. The presence of Fe2Ti is detrimental to the hydrogen storage efficacy. We show for the first time that it is possible to avoid the formation of Fe2Ti or β-Ti as a second phase under similar operating conditions only by tailoring the composition of the cathode precursor, i.e., the addition of TiO2 to low-grade FeTiO3 so that the atomic ratio of Fe:Ti in the precursor is ~ 1:1. Low-grade FeTiO3 with 10 wt% TiO2 resulted in single-phase FeTi with the atomic ratio of Fe:Ti ~ 1:1 in the precursor and in the final reduced alloy. The hydrogen storage capacity of the single-phase FeTi is nearly 36% higher as compared to the two-phase alloy consisting of FeTi–Fe2Ti.

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.

The present communication describes an investigation on the preparation of metallized composite pellets from ilmenite concentrate. It was observed that the pellet size in the range of 8–12 mm, a binder dosage of 4 wt%, and internal carbon of 5 wt% are the optimum levels that help the pellets attain the desired drop number (~ 10) and dry strength (~ 30 kg/pellet). When subjected to reduction tests at a temperature of 1200 °C for 6 h, the composite pellets show better metallization (~ 80%) than the raw ilmenite pellets with an equal amount of reductant. The reduced ilmenite composite pellets also display a reasonable decrepitation value of 4.9%, thereby making them suitable to be used directly in arc furnaces for titania slag production. A comparative characterization study by SEM–EDS indicated that larger amounts of metallic grains are uniformly distributed throughout the matrix in the composite pellets.

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.

This paper researched the enhanced flotation separation performance of ilmenite and titanaugite using the mixed collector benzhydroxamic acid/dodecylamine (BHA/DDA). The interface assembly mechanism was mainly investigated through in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy combined with the two-dimensional correlation spectroscopy (2D-COS) and X-ray photoelectron spectroscopy (XPS). It has been found that BHA/DDA mixed collectors successfully separate ilmenite from titanaugite at a molar ratio of 8:1. Zeta potential experiments suggested that, in the presence of mixed collector system, the BHA-DDA complex adsorbed on the ilmenite surface via the chemically adsorbed BHA and the electrostatically adsorbed DDA, however, the complex adsorbed on the surface of titanaugite unstably. According to in situ ATR-FTIR combined with 2D-COS and XPS results, the interface assembly mechanism of BHA/DDA is summarized as: the function group of BHA molecules first binds to the metal sites on minerals to form bidentate ligand, then DDA co-adsorbed with BHA on the surface of minerals through hydrogen bonding. DDA may change the adsorption modes of some BHA on the ilmenite surface from four-membered ring to five-membered ring, while the modes on the titanaugite surface is true opposite. Finally, recommended adsorption configurations of the BHA/DDA complex on the two mineral surfaces are proposed.

Chemical looping gasification is an efficient technology to convert biomass into valuable syngas. The iron-based oxygen carriers are a promising option for large-scale commercial applications due to their low cost and environmentally-friendly properties. The present study aims at evaluating the performance of the syngas production from the chemical looping gasification of torrefied woodchips in a pilot-scale bubbling fluidized bed reactor using iron ore and ilmenite as oxygen carriers. The effects of the operating parameters were investigated in this study. The results show that an increase in operating parameters could favor the process performance. Carbon conversion efficiency and the yields accelerate at high operating conditions. Carbon conversion efficiency showed a maximum value of 91.42% for iron ore at the ratio of oxygen carrier-to-biomass of 6, while the gas yield reaches the peak at SBR of 1.4 for ilmenite. The addition of steam in biomass chemical looping gasification improves hydrogen production and syngas quality in the product gas. Despite ilmenite provides better performance for hydrogen production, it characterizes by a lower reactivity compared to iron ore. It is also found that iron ore performs better at lower values of steam-to-biomass ratios and temperatures, while ilmenite shows good results at higher those parameters.

Rosetta ilmenite concentrate has been applied for uranium adsorption from its aqueous solution using batch sorption techniques. The optimised adsorption conditions included, solution pH 5, adsorbent dose (0.025 g/25 ml), uranium initial concentration 200 mg/L, 1 h contact time, and at room temperature (25°C), corresponding to uranium adsorption efficiency of about 74% and uranium uptake 148 mg/g. From kinetic parameters, it was found that uranium adsorption followed pseudo second order kinetics. Besides, the equilibrium data fitted the Langmuir isotherm model well. The various thermodynamic parameter rs were calculated (∆Ho = −14.3 kJ mol−1, ∆So = 0.075 kJ mol−1K−1, ∆Go = −36.65 kJ mol−1), these values an exothermic, randomness, and spontaneous adsorption process, respectively. Uranium is successfully desorbed from loaded ilmenite using 0.5 M H2SO4 for 15 min. contact time.

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...

Interpreting isotopic signatures documented in natural rocks requires knowledge of equilibrium isotopic fractionation factors. Here, we determine equilibrium Fe isotope fractionation factors between several common rock-forming minerals using a comparative approach involving three independent methods: (i) isotopic analyses of natural minerals from a metapelite from Mt. Moosilauke, New Hampshire, for which equilibration temperature and pressure are well constrained to be near the aluminosilicate triple point (T ≃ 500 °C, P ≃ 4 kbar), (ii) Nuclear Resonant Inelastic X-ray Scattering (NRIXS) measurements of Fe force constants of minerals, and (iii) Density Functional Theory (DFT) ab initio calculations of Fe force constants of minerals. The minerals studied for Fe isotopes include, in increasing order of their β-factors: garnet We show how the newly determined equilibrium fractionation factors can be used to address diverse problems in Earth and planetary sciences, notably (i) Fe and Mg isotopic fractionation during anatexis, (ii) Fe isotopic fractionation in lunar ilmenite, and (iii) Ti isotopic fractionation during fluvial transport of minerals.

A clean and efficient route for the utilization of ilmenite concentrates was proposed by direct carbothermic reduction in microwave field. High dosage of Na2CO3, which can be recycled, was added to accelerate the reduction reaction of ilmenite concentrates. After microwave heating in the temperature range of 1073−1123 K for 20 min, the main products were Na2TiO3 and metallic Fe with the metallization ratios being as high as 92.67%−93.21%. The reduction products were processed by water leaching, ball-milling in CO2 atmosphere and magnetic separation in turn. The final products after magnetic separation were Fe-rich materials and Ti-rich materials (90.04 wt.% TiO2), which can be used to produce iron and TiCl4 or TiO2. The optimized heating temperature was 1123 K in terms of metallization ratios, magnetic separation and caking property of the reduction products. Besides, the reduction mechanism of ilmenite concentrates with the addition of Na2CO3 in microwave field was also proposed.

Petrography and rock magnetic properties of the Dalma volcanics (DV) and associated meta-sediments of Singhbhum mobile belt (SMB) are presented to describe magnetic grain size and Fe-Ti oxide mineralogy of the volcano-sedimentary sequence. Petrography revealed the presence of Ti-magnetite, hematite, ilmenite and pyrite in quartz-biotite-sericite-muscovite schists, quartzites, and volcanic rocks. The average value of magnetic susceptibility (χ) is 5.6 × 10−7 m3/kg, anhysteretic remanent magnetization (ARM) is 2.25 × 10−5 Am2/kg, saturating isothermal remanent magnetization (SIRM) is 403.33 × 10−5 Am2/kg, soft IRM is 240.2 × 10−5 Am2/kg, hard IRM is 77.56 × 10−5 Am2/kg, and natural remanent magnetization (NRM) is 54.1 mA/m. The central tendency of the inter-parametric ratio ARM/χ is 0.06 kAm−1, SIRM/χ is 111.04 kAm−1 and S-ratio is 0.8. Based on results, magnetic mineralogy indicated that the bulk magnetic carrier is stable single domain (SSD) or pseudo single domain (PSD) grains of Fe-Ti oxides with minor iron sulphides such as pyrite, greigite and pyrrhotite. Petrography and rock magnetic studies suggest that the magnetic carriers are chiefly secondary in origin and the NRM is modified over time.

Foundations of technology for multicomponent recovery of useful components from titanium-bearing placers of the Ariadnenskoe deposit by pyrohydrometallurgical methods were investigated. Ammonium sulfate and thiourea–thiocyanate leaching solutions were successfully used to isolate titanium dioxide, gold, and a wide range of associated high-tech metals from the concentrate material. The experience gained in deep processing of gold–ilmenite mineral raw materials will help to more reasonably outline the ways to develop the Far East complex deposits in compliance with the principles of rational nature management and environmental protection.

Titanium hydroxide Ti(OH)4 prepared from Rosetta ilmenite concentrate has been applied to uranium adsorption from aqueous solution. The adsorption efficiency was studied in batch experiments in relation to pH, adsorbent dose, uranium initial concentration, contact time, and temperature. The optimum adsorption conditions are as follows: pH 5, adsorbent dose 2 g L–1, uranium initial concentration 400 mg L–1, contact time 1 h, and room temperature (25°C); under these conditions, the uranium adsorption efficiency is about 91% and the uranium uptake is 181 mg g–1. The obtained equilibrium data fit well with the Langmuir isotherm, while the adsorption kinetic data follow the pseudo-second-order model. The thermodynamic parameters were calculated; they show that the adsorption process is spontaneous and exothermic. The Ti(OH)4 sorbent showed good durability; it could be regenerated using H2SO4.

Heavy minerals have become an essential commodity in modern-day technology. The objective of this study is to examine the current status of the heavy mineral industry of Sri Lanka. The present study also examines the economic viability of potential heavy mineral placer deposits, based on geochemical data. Field investigations suggested the occurrence of heavy minerals as beach-placers, and inland/raised beach deposits along the coastline of Sri Lanka. Geochemical results showed the enrichment of TiO2, Fe2O3, Al2O3, and trace elements, and depletion of other major oxides such as Na2O, K2O, MnO, MgO, CaO, and P2O5. Consequently, it suggests the abundance of ilmenite, leucoxene, rutile, sillimanite, garnet, and rare earth element (REE)-bearing heavy minerals in potential placer deposits. In contrast, this study illustrates the exported quantity (in the weight ratio of 35:3:1) of ilmenite, rutile, and zircon minerals during the last decade. Ilmenite is the dominant heavy mineral in Sri Lanka, and thus, its production and price volatilisations are essential to understand the current status and predict the future behaviour of the heavy mineral industry. Statistical observations suggest that the global production and unit price variations of ilmenite have increased gradually from 1950 to 2015. Besides, the forecasted variations in annual global production and unit price changes of ilmenite indicate healthy compound annual growth rates of 1.27% and 1.43%, respectively. However, Sri Lanka has less contribution (< 1%) to global ilmenite production. Consequently, the value addition of ilmenite must be highly encouraged with at least an immediate stage (e.g. synthetic rutile). The present study also highlights possible value addition stages of available heavy mineral resources (low-, intermediate-, or high-level value addition), and discusses action plans to improve the quality of the heavy mineral industry of Sri Lanka. In recommendations, imposing sustainable regulations and policies would uplift the heavy mineral industry of Sri Lanka. For example, value addition to local heavy minerals and terminating raw commodity export are highly recommended.

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.

The modification roasting of ilmenite with gaseous chlorine in fluidized bed at 650 °C–750 °C was conducted, prior to hydrochloric leaching for preparation of synthetic rutile. The modification effects were characterized by redox titration, X-ray diffraction, scanning electron microscopy and X-ray fluorescence spectroscopy analysis. During the modified roasting, one third of reacted ferrous iron in ilmenite was chlorinated to form gaseous FeCl3 while the remaining part was oxidized to ferric state. The oxidation rate was found quite fast which was controlled by chemical reaction mechanism. At 650 °C, Fe2Ti3O9 crystallographic shear phase was the major solid product of roasting, as temperature rose, rutile and hematite phases became the main products. Morphologically, the Fe2Ti3O9 product caused no effect on the morphology of oxidized ilmenite, as gaseous FeCl3 generated and volatilized, submicron cracks were extended in the particles. When roasting at 750 °C, rutile phase emerged and nucleated quickly throughout the particles, and the formed rutile grains became the skeleton while volatilization removal of FeCl3, the roasted ilmenite kept their stability and formed target phase with porous structure. Besides, the silicate gangue of mineral was modified from smooth glass morphology to porous structure with more than 50% of calcium in silicate rapidly chloridized. After hydrochloric leaching, the acquired synthetic rutile from modified ilmenite reached a grade of 85.26 wt.% TiO2, and the harmful MgO and CaO contents were reduced to 0.55 wt.% and 0.19 wt.% respectively. The new process of chlorine modification-hydrochloric leaching shows a great applied prospect for synthetic rutile from low-grade ilmenite.

Major and trace element compositions of garnet, clinopyroxene, orthopyroxene, phlogopite, and ilmenite from garnet peridotite, ilmenite-bearing peridotite (dunites), and clinopyroxene–phlogopite xenoliths, as well as megacrysts of these minerals from the Grib kimberlite, Arkhangelsk diamond province, Russia, have been analyzed. These data are used to propose a model for mantle metasomatism of lithospheric mantle by kimberlite melts, including their generation and evolution, geochemical enrichment of depleted lithosphere mantle, and formation of megacrystic assemblage. The lithospheric mantle beneath the Arkhangelsk diamond province, from its base (depth ~180–210 km) to a depth of ~100–120 km (corresponding to a pressure of 3.5 GPa) experienced extensive metasomatism along the main kimberlite melt channel. Petrography of the peridotite xenoliths indicates a progressive refertilization of depleted harzburgite into garnet lherzolite, phlogopite–garnet wehrlite, and clinopyroxene–phlogopite rocks. Metasomatic refertilization occurred shortly before the capture of these xenoliths by the kimberlite melt. The model melt compositions calculated from garnet–clinopyroxene equilibria in different types of xenoliths and megacrysts show that alkaline–carbonate–ultramafic kimberlite melt acted as a metasomatic agent in the sheared peridotite at the base of the lithospheric mantle. High-Ti garnet and high-Cr clinopyroxene megacrysts in the middle part of the lithospheric mantle, as well as the main volume of garnet lherzolite xenoliths were formed in geochemical equilibrium with the kimberlite melts, which demonstrate an increase of silicate components and fractionation of Fe–Ti phases. The modification could be related to the interaction of ascending carbonate-rich protokimberlite melts with surrounding lithospheric mantle. The similarities in the compositions of garnet, clinopyroxene, phlogopite, and ilmenite megacrysts with minerals of peridotite xenoliths in the Grib kimberlite suggest that these megacrysts are disintegrated fragments of coarsest grained metasomatized garnet lherzolite, ilmenite-bearing peridotite, and clinopyroxene-phlogopite mantle rocks or formed under the same conditions as xenoliths or directly crystallized from metasomatic melts.

This decade is an incredible stage in the history of humanity. Man will return to the Moon to stay there. To successfully fulfill this enormous challenge, scientific staff will use the in-situ resources or ISRU, and terrestrial mining industry knowledge to produce prime matters. Oxygen and hydrogen are the crucial resources to obtain water, rocket fuel, and establish commercial activities between the Earth and the Moon. One alternative to produce oxygen is using metallurgical processing of oxide minerals as ilmenite. Also, iron and titanium could be produced from ilmenite to supply a future lunar aerospace industry, making attractive the exploration of this mineral. This paper discusses the ilmenite deposit features in the equator zone's Marias, especially in Mare Tranquillitatis. The author reviews the feasibility of producing oxygen from the ilmenite in a pyrometallurgical process, reviewing the reactions proposed through thermodynamic calculation with the Software HSC Chemistry 6.0 and the regolith sample’s geological data Apollo 11 to verify ore features that can affect the metallurgical behavior. Besides, there is a summary of the challenges to processing ilmenite associated with the degree of liberation. This research aims to clarify the industrial opportunities and challenges to produce oxygen on the Moon as a framework for future process architecture and equipment design.

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.