Analysis of the Effect of Dry Magnetic Separation on the Process of Ferruginous Quartzites Disintegration

The paper considers the results of the application of dry magnetic separation on samples of ferruginous quartzites of the Kostomuksha ore field, represented by refractory ore, free-milling ore, and their mixture. The assessment of the influence of the ore texture on the technological parameters of dry magnetic separation indicates their insignificant changes: the yield of the non-magnetic product varies from 12.4 to 13.5%, and the Fetotal content in the magnetic product increases by 1.11–1.14 times. A decrease of at least 15% in the number of harmful impurities was found: S by 16.2–17.3%, SiO2 by 15.5–21.1%, and Al2O3 by 39.1–48.4%. The authors have performed a comparative assessment of the granularity of the initial ore and the magnetic product with the measurement of energy consumption, as well as an analysis of the magnetite liberation on particle sizes of less than 2 mm. It was found that due to the release of a non-magnetic product in the amount of 12.3–14.5%, represented by non-magnetite or weakly mineralized rock varieties, energy consumption for the crushing process is reduced by at least 5%. The mineral liberation assessment showed that mainly free magnetite is contained in the −0.4 mm fineness class. It was found that in the magnetic separation product of the refractory ore sample, the amount of liberated magnetite in the size class −1 + 0 mm increases by 12.1% compared to the initial ore sample. For the free-milling ore sample, the opposite trend is observed: a decrease in the amount of free magnetite by 30.9% in the magnetic product. Analysis of the magnetite liberation in the mixture indicates deterioration in the results obtained during the separate crushing of refractory and free-milling ore and a decrease in the amount of liberated magnetite in the magnetic product by 60% compared to the initial ore.

THE U-Pb AGE AND Lu-Hf ISOTOPE SYSTEMATICS OF ZIRCON FROM THE HULIAIPOLE MET AVOLCANICS, THE AZOV DOMAIN OF THE UKRAINIAN SHIELD: EVIDENCE FOR THE PALEOARCHEAN-HADEAN CRUST

The Azov Domain occurs as a part of a larger Mesoarchean (3.2-3.0 Ga) craton, fragments of which are preserved in the eastern part of the Ukrainian Shield and as a block of the Kursk Magnetic Anomaly (KMA). In the Neoarchean-Palaeoproterozoic time, it was fragmented into several tectonic blocks: Vovcha, Remivka, Huliaipole, Bilotserkivka, and Saltych. The northern part of the Huliaipole Block is composed of tonalite-trondhjemite-granodiorite (TTG) rock association, that hosts the Kosivtsevo greenstone structure. It is composed of metamorphosed rocks of the jaspilite-komatiite-tholeiite association (the Kosivtsevo unit), which corresponds to the Sura Suite of the Konka Series of the Middle Dnieper Domain. The Neoarchean-Paleoproterozoic formations are represented by volcano-sedimentary rocks of the Huliaipole Suite and granitoids of the Dobropillya and Anadol complexes. Granitoids of the Dobropillya complex host numerous pyroxenite, gneiss, and plagioclase granite xenoliths. The U-Pb zircon age of granitoids of the Dobropillya Complex is 2040 Ma and inherited zircon has an age up to 3400 Ma. Small intrusions of two-feldspar granites of the Anadol Complex are widespread in the Ternuvate structure. Their U-Pb monazite age is 2190 Ma. In the central part of the Huliaipole Block, the NW-striking Huliaipole syncline (3.5 × 9 km) occurs. This structure is composed of volcano-sedimentary rocks of the Huliaipole Suite, which unconformably overlie Archean TTG. Felsic and intermediate metavolcanics are confined mainly to ferruginous quartzites of the middle Subsuites. To a limited extent, meta-andesites and felsic metavolcanics are also found in the lower and upper Huliaipole Subsuites. Zircons from meta-andesites and felsic metavolcanics of the Huliaipole Suite are very heterogeneous, indicating their crustal derivation. The U-Pb age of zircon populations from metadacite of the Huliaipole Suite was determined using the LA-ICP-MS method at 3085-2850 and 3700-3360 Ma. In addition, the age of the two crystals exceeded 3800 Ma. According to geological and geochronological data, the Huliaipole Block, 30 × 50 km in size, is composed of rocks and relicts of the Hadean, Archean, and Palaeoproterozoic eons. The oldest nucleoid of the Azov Domain.

LOCALIZATION FEATURES OF URANIUM MINERALIZATION IN THE TASIAST-TIJIRIT TERRANE, THE REGUIBAT SHIELD

The Reguibat Shield is an area of intensive uranium exploration and about 80 ore occurrences have been discovered in recent decades within its borders. The region of the study is located within the Tasiast-Tijirit terrane, which represents a northwestern part of Archean domain of the Reguibat Shield. The rocks of the terrane are of Mesoarchean age. The main types of rocks are migmatites, gneisses and amphibolites, greenstone associations, granitic intrusions and pegmatites. Samples of pegmatites, granites, ferruginous quartzites and sedimentary rocks that showed an increased radiation level after conducting a ground-based radiometric survey were selected for laboratory studies from the host rocks of the Tasiast-Tijirit terrane. The following types of laboratory analyses were used for the study: 1) spectral analysis by laser-luminescence method to determine the uranium content in samples; 2) atomic emission spectroscopy for the general estimation of concentrations of chemical elements in samples; 3) X-ray fluorescence analysis to determine the chemical composition of samples and its trace elements; 4) electron microprobe analysis to determine the morphology of mineralization and the chemical composition of uranium minerals. Among the Tasiast-Tijirit terrane rocks the increased uranium content was found in the following rock associations: pegmatites and granites; ferruginous quartzites within the banded iron formation; calcretes in sedimentary rocks. According to the results of field and laboratory studies, the main factors of the localization of uranium mineralization in calcretes of the OumDherua area were established. The main geological, physical and chemical conditions essential for the formation of uranium mineralization of the calcrete type within the study region were established. It was found that granites and pegmatites could provide source of uranium for ore mineralization in sedimentary formations, such as surficial and calcrete types. The latter are studied and mined quite intensively in the world including the Reguibat Shield. The study results show the high potential for prospecting and exploration of new uranium occurrences within the Tasiast-Tijirit terrane.

Improving the quality of concentrates of Stoilensky GOK JSC with the use of magneticAgravity separation

An innovative high-grade magnetite concentrates production technology has been developed and pilot tested for ferruginous quartzites of the Kursk Magnetic Anomaly. This paper assesses the possibility of using magnetic-gravity separation to obtain high-grade products, suitable for direct metallization, from finely disseminated ferruginous quartzites of the KMA. The results of pilot tests are presented for the current production of high-grade magnetite concentrates from commercial concentrates and for the production of pellets at the Stoilensky GOK, which may be used to draw the following conclusions. Commercial magnetite concentrate may be processed by magnetic-gravity separation. The grade improvement (mass fraction of Fetot) in the pilot tests averaged 1.23 %, while the expected grade increase for industrial MG separation is 1.17 %. Magnetite concentrate for pellet production may also be processed by MG separation. The grade improvement in the pilot tests averaged 1.26 %, while the expected grade increase for industrial MG separation is 1.20 %. Magnetite concentrates are diluted with classes of over 0.045 mm. It is recommended to conduct the tests using classified feed. The processing of MG separation overflows, ground to d80 0.045 mm (the size of stage III industrial grinding), demonstrated the lack of prospects for obtaining any commercial product from this product.

Research of the influence of material composition and size of iron quartzites of the Olenegorsk deposit on the results of dry magnetic separation

On the example of a sample of ferruginous quartzites from the Olenegorskoye deposit, the possibility of preliminary concentration by dry magnetic separation (DMS) has been established. The mineralogical and petrographic studies have shown that, in terms of their textural and structural features and mineral composition, ferruginous quartzites may be divided into two types, differing in the amount of hematite included in their composition, which indicates the possibility of using DMS to generate the following three separation products: magnetite, hematite-magnetite, and rock. DMS with the use of a laboratory drum magnetic separator allowed selecting the upper size limit of 80 mm for lumps entering the separation. At the same time, 24.7 to 26.0 % of all waste and low-mineralized rocks with the mass fraction of Fetot of 4.51 to 6.07 % are transferred to the non-magnetic fraction during the separation of classes of –80+50 and –50+25 mm. For the size class of –25+10 mm, the yield and Fetot values are within the same limits. It has been shown that sulfidecontaining rocks and rocks of increased strength (with the strength coefficient of at least 23) are separated into the non-magnetic fraction. The strength of ferruginous quartzites does not exceed 20. This rock strength ratio confirms improved crushing and grinding efficiency. The possibility of separation of the magnetic fraction with the particle size of –80+25 mm into the following products has been established: the magnetite-hematite product (MF-1 + MF-2) with the mass fractions of Femagn 43.3% and Fehem 14.9 %, and the predominantly hematite product (MF-3 + MF-4) with the mass fractions of Femagn 1.1 % and Fehem 67.9 %.

Ufa mantle ridge fault – main tectonic, geological and minerogenic consequences

Relevance of the work. The data on the structure and properties of the subsoil, obtained on the basis of geophysical studies, make it possible to significantly revise the ideas about the structure and patterns of formation of mineral deposits within the Ufimsky ridge fault and its zone of influence (55º–56º north latitude in the Urals). Purpose of the work: constructing a model of the formation of the Ufa mantle ridge fault and identifying its mineragenic features using the example of deposits of ferruginous quartzite, kyanites and rare earth mineralization. The methodology of the research. The published databases and their summarizing materials on deep seismic sounding of the Urals with the allocation of a mineragenic load characteristic of the Ufa mantle ridge fault and its influence zone were used as a factual basis for the research. Research results. The Ufa ridge fault is a structure formed by the uplift of the upper mantle, presumably at the intersection of intramantle shear faults. The transverse asymmetry of the mantle ridge fault and the later rift-collisional processes are reflected in the overlying complexes and lead to a distortion of the lines of the outcropping of deep faults at the level of the modern erosional section. Horst formation was complicated by rifting-collisional tectonic events with accompanying magmatic, metamorphic, metasomatic, and dislocation processes, accompanied by various types of numerous manifestations and mineral deposits exposed by erosional processes. Schemes of the location of deposits and manifestations of ferruginous quartzites, kyanites and rare earth mineralization in its more eroded part are given as examples confirming the confinement of various types of minerals to the structure of the Ufa mantle ridge fault. Conclusions. The cropping of deposits and occurrences of ferruginous quartzites, kyanite, rare earth mineralization and other minerals is closely related to the development of the Ufa mantle ridge fault.

Magnetic properties of natural weakly magnetic iron oxides of the Kursk Magnetic Anomaly

This paper contains the results of complex studies on magnetic characteristics of a system of basic natural weakly magnetic iron oxides isolated from the oxidized ferruginous quartzites of the KMA. It has been shown that their magnetic characteristics vary over a wide range and substantially depend on the nature of the samples, i.e. represent not only physical, but also genetic characteristics. The contrast in magnetic properties inside the system exceeds the mere hydroxides/quartz contrast; therefore, it is necessary to differentiate the recovery conditions for various iron oxides. For example, the magnetic characteristics of martite and hematite behave differently in different size classes. This dependence is most noteworthy for hematite. It has been shown that, despite the relatively low mass fraction of the ferromagnet, magnetic susceptibility of natural systems of weakly magnetic iron oxides may be an important genetic and diagnostic trait, which must be taken into account when designing all respective separation technology and equipment. The problem under consideration is directly related to mineral processing and the technology must ensure the recovery of both coarse and fine highly and medium magnetic particles into the concentrate.

Determination and choice of optimal cut-off grade value using 3d modeling on the example of domestic bif deposits

Ukraine is in 10 countries with the largest reserves of iron ores, and the iron ore industry and metallurgical complex are budgetary sectors economically important for the country. For now the mining and metallurgical complex is experiencing not the best of times, and experts say that Ukraine is not using its potential, as it should. One of the main steps in inventory calculation is the determination of boundary value. Boundary value is calculated on the basis of geological, economic, technological and social aspects. Using only geological information, you can calculate the most favorable boundary value using geostatistics. The main cut-off parameter that determines reserves quality of ferruginous quartzites, which require enrichment by magnetic separation, is iron associated with magnetite Femagn. The paper proposes a tool for choosing the optimal cut-off grade values for evaluating BIF deposits using the example one of the West Azov group deposit. Comparison of cut-off parameters for reserves calculation of iron ores within the Azov Group deposits is carried out. To find the optimal cut-off grade Femagn using geostatistics and spatial modeling, we analyzed the dynamics of changes in the amount of reserves from changes of cut-off grade Fe. Fluctuations in average Fe grade also were took into account. The paper substantiates the optimal cut-off grade values of Fe associated with magnetite in the range of 12–14 %. The interval of the largest changes in reserves quantity with an increase is fixed for range of 12–18 %. Beyond this interval there is a minimal fluctuation of ore reserves quantity as a result of cut-off grade’s changes. In order to find optimal cut-off grade values using geostatistics and spatial modeling, it is necessary to follow the dynamics of reserves’ quantity changes depend on Fe cut-off grade, as well as to take into account average Fe grade fluctuations when changing cut-off grade.

STUDY OF PHYSICAL-MECHANICAL PROPERTIES OF ASPHALT-CONCRETE SPECIMENS ON ACTIVATED MINERAL POWDERS OF VARIOUS COMPOSITIONS

the article presents the results of testing asphalt samples based on activated mineral powder from silica-containing raw materials. Activated filler was obtained by joint grinding of waste wet magnetic separation (WMS) of ferruginous quartzites of the Kursk Magnetic Anomaly in a spherical planetary mill in the presence of surfactants (stearic acid, adhesive additive Amdor-10) and bitumen. First of all, it should be noted that the use of activated mineral powder in the composition of asphalt concrete mixture led to an increase in the packing density of the composite. This was reflected not only in the technological process, but also contributed to the decrease in the porosity of the mineral core. It was found that the use of surfactants in the process of grinding mineral powder made it possible to increase the strength of asphalt concrete samples. However, the change in the crack resistance and shear resistance of asphalt concrete specimens, determined from the ratio of the corresponding compressive strengths, did not occur (table). This is due to the fact that there has been a proportional change in all the strength characteristics at different temperatures. Analysis of the physical-mechanical characteristics of the properties of asphalt concrete led to the conclusion that it was possible to use activated mineral powder from waste WMS as a component of asphalt concrete mixtures.