Integrated study on obtaining oxide pellets from brown iron ore

Introduction. Currently, the main raw materials for the production of cast iron and steel at metallurgical plants are iron concentrates obtained from magnetite (ferrous) quartzites, titanium-magnetite, and skarn ores. The existing technologies for processing these types of ores, which mainly include separation processes based on magnetic properties, size, separating of equally falling grains, and surface wettability allow us to produce both ordinary iron concentrates and high quality ones. The use of such schemes in the processing of brown iron ore does not allow obtaining high rates of mineral concentration. One of the methods for processing this type of ore is a roasting-magnetic scheme, which allows converting weakly magnetic (non-magnetic) forms of iron into strongly magnetic ones. Research objective is to develop the mode of magnetizing roasting of brown iron ore, technology of concentrating of the burn-out product in order to obtain iron concentrate and oxide pellets. Methods of research. The duration of heat treatment of the charge consisting of iron ore from the Abail deposit and coal from the Ekibastuz deposit and the required mass fraction of solid carbon contained in the coal are determined. Technological studies of the roasted product were carried out in order to obtain a concentrate with a mass fraction of iron at least 67%. According to the developed technology, a batch of iron concentrate was developed in order to obtain and study raw and oxide pellets. Results. The modes of magnetizing roasting of brown iron ore from the Abail deposit and cooling of the roasted material have been developed. A scheme for mineral processing of the roasted material has been developed in order to obtain a concentrate with at least 67% of iron mass fraction. The process of obtaining strong raw and roasted pellets from iron concentrate is studied. Conclusions. The developed mode of magnetizing roasting of the charge consisting of coal and ore from the Abail deposit makes it possible to obtain a roasted product with a degree of magnetization of 93%. The using of desliming of the roasted product makes it possible to remove magnetic floccules from the processing that reduce the concentrate quality, and to obtain a concentrate with a mass fraction of iron of at least 67% in the last stage of magnetic separation. From the iron concentrate, it is possible to obtain oxidized pellets with a strength of at least 200 kg/pellet at temperature of pellets firing of 1325 °C.

Peculiar features of correlation between petrophysical signatures of rocks and distribution of geophysical heterogeneities in the Monchegorsk ore area (Kola Peninsula, northeastern Baltic Shield)

The current article presents stratified data on physical properties of rocks and ores from the Monchegorsk ore area (Kola region). The constructed petrodensity and petromagnetic maps reflect peculiar features of changes in petrophysical parameters of both Paleoproterozoic intrusive rocks and host rocks at the Archean basement of the area. To assess the complementarity degree of physical properties of the rocks and geophysical fields, we additionally analyzed the structure of geophysical anomalies (Δg, ΔZ) in the study area. It allowed constructing a distribution scheme for geophysical heterogeneity in the area and assessing their nature. The conducted studies showed that nickel-bearing and potentially nickel-bearing intrusions in the Monchegorsk ore area were highly dense, but composed of weakly magnetic rocks. Layering of the gabbro-labradorite massif of the Main Ridge is reflected in petrophysical parameters, i. e. endocontact gabbro and gabbronorite show an increased density and magnetic susceptibility compared to leucocratic gabbro and labradorite in the core of the intrusion. Thus, petrophysical data indicate a general increase in the basicity of the rocks towards the bottom of the intrusion. The discrepancy between intense geophysical anomalies and physical parameters of near-surface rocks of the block adjacent to the gabbro-labradorite massif of the Main Ridge in the southeast was revealed. This fact indicates a layer of dense rocks under the supracrustal basement rocks (a complex of gneisses and amphibolized volcanic-sedimentary rocks) and rocks of the Imandra-Varzuga structure. This layer can be composed of potentially nickel-bearing rocks of the Imandra complex, including intrusions of the clinopyroxene-wehrlite formation series exposed in some areas. According to the configuration pattern of the identified axes of local magnetic anomalies, the Archean blocks are considered isolated areas given the uniform pattern they create, i. e. Belomorian — isometric structures, Kola — linearly extended. Therefore, during transformation of the structural plan in the Paleoproterozoic, the Archean blocks gave differentiated responses to the emerging stress-strain state of the environment and were subject to heterogeneous deformations. The performed work, including integrated results of petrophysical studies with the analysis of the structure of geophysical anomalies in the ore region, is relevant in substantiating a strategy for prospecting for new ore occurrences and patterns of their localization, as well as for developing criteria for predicting industrial ores in the region. At the same time, the studies carried out make it possible to answer questions related to the reconstruction of the geodynamic settings that took place during the formation of the region’s crust.

Highly efficient removal of Sb(V) from water by franklinite-containing nano-FeZn composites

The existence of toxic and carcinogenic pentavalent antimony in water is a great safety problem. In order to remove antimony(V) from water, the purpose of this study was to prepare a novel graphene nano iron zinc (rGO/NZV-FeZn) photocatalyst via hydrothermal method followed by ultrasonication. Herein, weakly magnetic nano-Fe–Zn materials (NZV-FeZn, GACSP/NZV-FeZn, and rGO/NZV-FeZn) capable of rapid and efficient Sb(V) adsorption from water were prepared and characterised. In particular, rGO/NZV-FeZn was shown to comprise franklinite, Fe0, and graphite. Adsorption data were fitted by a quasi-second-order kinetic equation and Langmuir model, revealing that among these materials, NZV-FeZn exhibited the best Sb removal performance (543.9 mgSb gNZV-FeZn−1, R2 = 0.951). In a practical decontamination test, Sb removal efficiency of 99.38% was obtained for a reaction column filled with 3.5 g of rGO/NZV-FeZn. Column regenerability was tested at an initial concentration of 0.8111 mgSb L−1, and the treated water obtained after five consecutive runs complied with the GB5749-2006 requirement for Sb. rGO/NZV-FeZn was suggested to remove Sb(V) through adsorption-photocatalytic reduction and flocculation sedimentation mechanisms and, in view of its high cost performance, stability, and upscalable synthesis, was concluded to hold great promise for source water and wastewater treatment.

Integrated Geophysical Evidence for the Middle-Lower Crust Melting of the Songpan-Aba Terrain, NE Tibetan Plateau

The Songpan−Aba region is located on the northeastern edge of the Tibetan Plateau. Tectonically, the area is surrounded by the West Qinling orogenic belt in the north, the Longmenshan orogenic belt in the southeast, and the East Kunlun and Sanjiang orogenic belts in the west and southwest, forming a triangle that provides an ideal location to study the crust-mantle structure and deep tectonics of the eastward extrusion of the Tibetan Plateau. In this study, the magnetic and electrical structures of the Songpan−Aba area were investigated by inversion using high-precision magnetic anomaly and magnetotelluric data to obtain the subsurface magnetization inversion intensity and resistivity of Songpan–Aba and adjacent areas. The results revealed a continuous magnetic layer up to 20 km below Songpan–Aba and its surrounding areas in the south, possibly originating from a magma root southwest of the Longmenshan massif. In the West Qinling, Songpan–Aba, and Longmenshan areas, pervasive low-resistance, weakly magnetic, or magnetic layers were identified below 20 km that might be formed from the molten mantle material extruded from the eastern edge of the Tibetan Plateau.

Geophysical search for fragments of the Sterlitamak meteorite

Relevance is determined by the fact that meteorites are of great importance for the direct study of the substance of the Universe, therefore, when new meteorites fall, maximum efforts are made to detect them and study the conditions of the fall. The purpose of the work is to further study the meteorite crater and search for large fragments of the Sterlitamak meteorite not found at the first stage of study using geophysical methods. The story of the fall and searches for the main fragment of the Sterlitamak meteorite, which fell on August 17, 1990 at 23 h 25 min, on the field of the Sterlitamak state farm is described. When it fell, a crater with a diameter of 10 m and a depth of 4 m was formed. The fall was accompanied by a bright glow and thunderous rumbles. A glow was observed over the crater in the dark. A high-speed searching for the meteorite was organized by collecting meteorite debris around the crater. At the same time, a mine detector was used. The crater was excavated with an excavator to a depth of 18–20 m. Fragments weighing 6.6; 3.06; 0.875; 0.363 kg were found. A year later, the main body weighing 315 kg was accidentally found in the dumps. Chemical analysis of the substance showed that it is an iron-nickel meteorite, 98% of the thickness are the minerals kamacite, tenite and schreibersite. Results. In 2014–2015, the authors carried out magnetic surveying around the crater and on the ice of the lake, which was formed at the excavation site, in order to search for fragments of the meteorite, which were probably missed at the initial stage. Maps of the magnetic field and terrain of the crater are given. Magnetic anomalies are identified, which are presumably associated with new fragments of the meteorite. The probable depths of the meteorite fragments are 2–4 m. In-depth sections of the magnetization for these anomalies obtained by the method of magnetic tomography, are given, as well as the results of a surface survey of the dump area using a metal detector. Weakly magnetic samples were found containing sprayed metal and metal balls with a diameter of 0.5–1.0 mm. These samples originally formed a zone of impact metamorphism, which was destroyed by excavation operations. It is shown that the territory is promising for searching for new large fragments of the meteorite and studying the processes of impact metamorphism. It is planned to further study the crater by means of electrical exploration and GPR sounding.

Detecting Weak Quantum Magnetism at High Pressures

Improved device and method to measure magnetization under high pressure was developed, which brings a quick tool to screen phases of interest in weakly magnetic materials including quantum magnets.

Operational lifetime increase of the pumping equipment when pumping-out contaminated groundwater

Purpose. Solving the problem of increasing the pumping equipment operational lifetime when pumping-out contaminated groundwater in the iron-ore industry by extracting the hard, abrasive part, using magnetic filters based on permanent ferrite magnets. Methods. To produce spherical hard-magnetic ferrite elements that catch finely-dispersed magnetic and weakly-magnetic abrasive particles when pumping-out contaminated groundwater in the iron-ore industry, barium ferrite powder BaО∙6Fe2O3 is applied, which is usually used for obtaining hard-magnetic ferrites. Spherical elements for filling a magnetic filtering installation are obtained by the method of spheroidizing the barium ferrite powder in a dragee machine. Sintering of spherical granules obtained from barium ferrite powder is conducted in a high-temperature atmospheric electric box furnace. The sintered spherical elements made of hard-magnetic barium ferrite are magnetized using a magnetic pulsed toroidal-shaped setup in a pulsed constant magnetic field. Findings. For continuous pumping-out and purification of contaminated groundwater from magnetic, weakly-magnetic and non-magnetic highly abrasive particles with the help of magnetic filters, a scheme of a filtering installation of two sections is pro-posed. A technology for producing spherical permanent magnets from barium ferrite powder has been developed for a filtering installation, which includes a coarse purification column with hollow-spherical permanent magnets of 16-17 mm in diameter and a fine purification column with full-bodied spherical barium ferrite magnets of 6-7 mm in diameter. Originality.The term of pumping equipment operation is doubled if to eliminate abrasive wear due to the filtering two-section installation by filling with barium ferrite spherical magnets. In the case of changing the filter, idle time is reduced by using the supplementary auxiliary column. The possibility of processing filtration products and their use in the field of construction and metallurgy without environmental pollution is substantiated. Practical implications. The scheme of magnetic groundwater purification in the iron-ore industry is proposed, consisting of a filtering column of coarse and fine purification from abrasive particles. A technology for producing spherical magnets with different diameters has been developed to ensure the quality of the process. The research results allow to increase the operational lifetime of pumping equipment by eliminating abrasive wear, which will lead to significant savings in the replacement and repair of centrifugal pumps. Keywords: pumping equipment, groundwater, wear, barium ferrite, spherical magnet, filter, iron-ore industry

An ultra-low magnetic field thermal demagnetizer for high-precision paleomagnetism

Thermal demagnetization furnaces are widely used paleomagnetic facilities for progressive removal of naturally acquired magnetic remanence or the imparting of well-controlled laboratory magnetization. An ideal thermal demagnetizer should maintain “zero” magnetic field in the sample chamber during thermal treatments. However, magnetic field noises, including the residual magnetic fields of the construction material and the induced fields caused by the alternating current (AC) in the heating element are always present, which can contaminate the paleomagnetic results at the elevated temperatures or especially for the magnetically weak samples. Here, we designed a new structure of heating wire named “straight core solenoid” to develop a new demagnetization furnace with ultra-low magnetic field noise. Simulation and practical measurements show that the heating current magnetic field can be greatly reduced by using the new technology. Thermal demagnetization experiments demonstrate that the new demagnetizer can yield low noise results even for weakly magnetic samples.

An ultra-low magnetic field thermal demagnetizer for high-precision paleomagnetism

Thermal demagnetization furnaces are widely used paleomagnetic facilities for progressive removal of naturally acquired magnetic remanence or the imparting of well controlled laboratory magnetization. An ideal thermal demagnetizer should maintain “zero” magnetic field in the sample chamber during thermal treatments. However, magnetic field noises, including the residual magnetic fields of the construction material and the induced fields caused by the alternating current (AC) in the heating element are always present, which can contaminate the paleoamgnetic results at the elevated temperatures or especially for the magnetically weak samples. Here, we designed a new structure of heating wire named “straight core solenoid” to develop a new demagnetization furnace with ultra-low magnetic field noise. Simulation and practical measurements show that the heating current magnetic field can be greatly reduced by using the new technology. Thermal demagnetization experiments demonstrate that the new demagnetizer can yield low noise results even for weakly magnetic samples.