Petrogenetic peculiarities of Fe-Ti oxide minerals in the processes of crystallization and evolution of late Cretaceous volcanic complexes of the Lesser Caucasus

Drawing from the determined differences between iron-titanium oxide minerals, we analyzed the conditions of crystallization and evolution of late-Cretaceous magmatic complexes of the Lesser Caucasus. It was found that the rocks of basalt-andesibasalt complex, which correspond to the early substage (upper Coniacian-lower Santonian) of late-Cretaceous volcanism in the Qazakh, Agjakand, Agdara depressions, have crystallized in the conditions of relatively highly- thermobaric crystallization of titanomagnetite, poorly differentiated and evolutionized according to the Fenner trend. In the second substage of volcanism, due to decrease in permeability of the Earth’s crust, the elevation of the remaining magma to the upper horizons was hindered. Therefore, within the Qazakh depression, shallow intermediate sites of crystallization developed where moderately titaniferous magnetite crystallized with the participation of oxidized fluids earlier than hornblende, pyroxene and plagioclase. Thus, the remaining magma evolutionized its composition through Bowen’s reaction series. In the Agjakand and Agdara depressions, change of previous expansion to compaction was the cause of hindering of partly fractioned portion of the magma. The latter thermally interacted with the above-embedded maghemite, hematite and in a number of cases magnetite. In the Khojavand depression, rocks of trachibasalt- trachiodolerite complex, which characterize the late substage of the Santonian volcanism, contain moderately titanium magnetites and maghemites. In the second substage of volcano-plutonism, rocks of tephrite-teshenite complex developed. There, accompanied by oxidized fluids, highly-clayey titanomagnetite crystallized before chrome-diopside and salite. However, the ulvospinel titanomagnetite in teshenites, having associated with barkevikite and kaersutite, crystallized at a relatively higher temperature. Within the Senonian volcanites of the Azykh depression, along with the moderately-titanium magnetite, chromic titanomagnetite and rarely chromite was determined. Similar mineralogical diversities are also characteristic for the Gochas depression.

Leaching Titaniferous Magnetite Concentrate by Alkaline Aqueous Solution

Leaching titaniferous magnetite concentrate with alkali solution of high concentration under high temperature and high pressure was utilized to improve the grade of iron in iron concentrate and the grade of TiO2 in titanium tailings. The titaniferous magnetite concentrate in use contained 12.67% TiO2 and 54.01% Fe. The thermodynamics of the possible reactions and the kinetics of leaching process were analyzed. It was found that decomposing FeTiO3 with NaOH aqueous solution could be carried out spontaneously and the reaction rate was mainly controlled by internal diffusion. The effects of water usage, alkali concentration, reaction time, and temperature on the leaching procedure were inspected, and the products were characterized by X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy, respectively. After NaOH leaching and magnetic separation, the concentrate, with Fe purity of 65.98% and Fe recovery of 82.46%, and the tailings, with TiO2 purity of 32.09% and TiO2 recovery of 80.79%, were obtained, respectively.

Production of Metallic Iron from the Pudo Magnetite Ore using End-of-Life Rubber Tyre as Reductant: The Role of an Underlying Ankerite Ore as a Fluxing Agent on Productivity

This research work investigated the nature of a nonmagnetic ore from Pudo in the Upper West Region of Ghana and its fluxing effect on the extent of reduction of the Pudo titaniferous magnetite ore using pulverised samples of charred carbonaceous materials generated from end-of-life vehicle tyres (ELT) as reductants. Reduction studies were conducted on composite pellets of the Pudo titaniferous magnetite iron ore containing fixed amounts of charred ELT and varying amounts (0%, 10%, 15%, 20%, 30%, 40% and 50%) of the nonmagnetic fluxing material in a domestic microwave oven and the extent of reduction was calculated after microwave irradiation for 40 minutes. Analyses by XRF, SEM/EDS and XRD of the nonmagnetic ore revealed an Ankerite type of ore of the form Ca0.95Fe0.95Mn0.1 (CO3)2. From the microwave reduction studies it was observed that premium grade metallic iron could be produced from appropriate blends of the Pudo iron ores using ELT as reductant, with a measured extent of reduction up to 103.8%. Further, the extent of reduction was observed to increase with an increase in the amount of the nonmagnetic fluxing material (Ankerite) that was added as fluxing agent. Keywords: Ankerite, End-of-life Rubber Tyres, Fluxing Agent, Extent of Reduction

Evaluation of Titania-Rich Slag Produced from Titaniferous Magnetite Under Fluxless Smelting Conditions

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.

PGE-Enrichment in Magnetite-Bearing Olivine Gabbro: New Observations from the Midcontinent Rift-Related Echo Lake Intrusion in Northern Michigan, USA

The Echo Lake intrusion in the Upper Peninsula (UP) of Michigan, USA, was formed during the 1.1 Ga Midcontinent Rift event in North America. Troctolite is the predominant rock unit in the intrusion, with interlayered bands of peridotite, mafic pegmatitic rock, olivine gabbro, magnetite-bearing gabbro, and anorthosite. Exploratory drilling has revealed a platinum group element (PGE)-enriched zone within a 45 m thick magnetite-ilmenite-bearing olivine gabbro unit with grades up to 1.2 g/t Pt + Pd and 0.3 wt. % Cu. Fine, disseminated grains of sulfide minerals such as pyrrhotite and chalcopyrite occur in the mineralized interval. Formation of Cu-PGE-rich sulfide minerals might have been caused by sulfide melt saturation in a crystallizing magma, which was triggered by a sudden decrease in fO2 upon the crystallization and separation of titaniferous magnetite. This PGE-enriched zone is comparable to other well-known reef-like PGE deposits, such as the Sonju Lake deposit in northern Minnesota.

Sorting out of Gusevogorsk deposit titaniferous magnetite ore by technological types by methods of geoinformation modeling and preliminary estimation of their washability

A more complete and complex extraction of valuable components in the development of mineral resources is achieved through the separation of technological types and grades of ores, their separate extraction and processing, which allows to increase the yield, quality and nomenclature of commercial products and to raise the economic efficiency of the extraction and preparation processes. An important element of the separate processing of types of ores is the technology used for their zoning by grades in the open-pit space. Innovative direction in the development of the forecast of quality and preparation characteristics of mineral resources is the methods of geoinformation modeling with the use of Geological and Mining Information System technologies. The paper describes the technique of modeling and separation of ores into technological grades on the example of the Gusevogorskoye deposit of titanomagnetites, and presents the method of express ore preparability analysis with the estimation of the degree of contrast of qualitative characteristics.