-
Date submitted2024-05-15
-
Date accepted2024-11-07
-
Date published2025-04-14
Metacarbonate rocks of the Paleoproterozoic Khapchan series (southeastern part of the Anabar Shield): mineral and chemical composition, metamorphic conditions
The mineral composition of metacarbonate rocks (silicate marbles and carbonate-silicate rocks) of the Khapchan series (southeastern part of the Anabar Shield) was studied, and the PT (pressure and temperature)-parameters of their formation were established. Silicate marbles contain calcite, dolomite, forsterite, clinohumite, spinel, enstatite, diopside, pargasite, meionite, phlogopite, and feldspars. Carbonate-silicate rocks are composed of calcite, quartz, feldspars, diopside, grossular, marialite, and vesuvianite. Carbonate-silicate rocks are significantly enriched in SiO2, Al2O3, FeO, Na2O, K2O, TiO2 and contain less MgO, CaO than silicate marbles. A difference was revealed in PT-parameters determined for silicate marbles (temperatures 700-900 °C and pressure no more than 8 kbar) and for carbonate-silicate rocks (temperatures 680-820 °C, pressures 8-15 kbar). Silicate marbles have a primary sedimentary nature, as evidenced by their rare-element composition and the presence of fragments of host terrigenous rocks. There is no doubt about the primary sedimentary nature of carbonate-silicate rocks, which are very similar in REE distribution spectra and in rare-element composition to silicate marbles. A number of features indicate that metacarbonate rocks have undergone metasomatic alteration. Thus, in silicate marbles, reaction rims are observed around orthopyroxene, forsterite, potassium feldspar, as well as quartz veins bordered by accumulations of phlogopite, feldspars, and diopside. In carbonate-silicate rocks, the development of secondary marialite on potassium feldspar has been established; the rare-element composition of garnet may indicate its metasomatic origin.
-
Date submitted2024-05-03
-
Date accepted2024-11-07
-
Date published2025-04-02
Assessment of ancylite ore dressability by flotation method
For more than 50 years, most rare earth elements were extracted from carbonatite deposits, which can contain different rare earth phases, but the main extracted minerals are bastnaesite, monazite and xenotime. Many studies focused on the improvement and development of dressing circuits for ores of these minerals. However, in some carbonatite complexes, rare earth deposits are composed partly or mainly of ancylite ores. This type of rare earth ores was very poorly studied in terms of dressability – previous experiments with ancylite ores are rare and not productive enough. Ancylite is the main concentrator of rare earth elements in most carbonatite complexes of the Devonian Kola Alkaline Province (northwest Russia). Dressability of ancylite ore from the Petyayan-Vara carbonatite field in the Vuorijärvi alkaline-ultramafic complex was assessed using the flotation method. The complex is one of the most potential rare earth deposits associated with carbonatites in the Kola Region. Petrographic and mineralogical studies demonstrated the occurrence of abundant iron and barite oxide inclusions in ancylite, which imposes restrictions on physical separation of these three minerals. The study of petrogeochemical and mineralogical composition of fractions formed during mechanical grinding of ores to a size less than 2.0 mm showed that even at this stage of sample preparation, the finest-grained fractions (less than 0.071 mm) were enriched in ancylite (to 19 vol.% or more with a content of 15 vol.% in ore). Three classes of reagents were considered as collectors in flotation experiments: fatty acids, alkyl hydroxamic acids, and amino acid derivatives. The reagent from the amino acid derivative class was highly efficient. The use of such a collector in combination with sodium hexametaphosphate depressant made it possible to obtain a flotation concentrate in an open circuit with total rare earth oxides content 33.4 wt.% at 64.7 % extraction.
-
Date submitted2022-04-13
-
Date accepted2022-05-25
-
Date published2022-11-03
Mineralogical and technological features and patterns of selective disintegration of ferruginous quartzites of the Mikhailovskoye deposit
The growing demand for ferrous metallurgy products necessitates the introduction of technologies that increase the efficiency of the processing of iron-bearing raw materials. A promising trend in this area is the implementation of solutions based on the possibility of selective disintegration of ores. The purpose of this work was to establish the laws of selective disintegration of ferruginous quartzites based on the results of the study of mineralogical and technological properties of raw materials. We present data on the study of mineralogical and technological features of ferruginous quartzites of the Mikhailovskoye deposit. The data were obtained using X-ray fluorescence analysis and automated mineralogical analysis. Based on studies of the nature of dissemination and the size of grains of rock-forming and ore minerals, the tasks of ore preparation are formulated. The parameters for the iron and silicon oxide distribution by grain-size classes in the grinding products were established during the study. Based on empirical dependences, the grain size of grinding was predicted, at which the most effective release of intergrowths of ore minerals and their minimum transition to the size class of –44 µm should be achieved.
-
Date submitted2021-03-17
-
Date accepted2021-04-12
-
Date published2021-06-24
Application of the resonant energy separation effect at natural gas reduction points in order to improve the energy efficiency of the gas distribution system
- Authors:
- Andrei M. Schipachev
- Alena S. Dmitrieva
Maintaining the gas temperature and the formation of gas hydrates is one of the main problems in the operation of gas pipelines. Development and implementation of new effective methods for heating the gas during gas reduction will reduce the cost of gas transportation, solve the problem of resource and energy saving in the fuel industry. Study is aimed at increasing the energy efficiency of the natural gas reduction process by using a resonant gas heater to maintain the set temperature at the outlet of the gas distribution station (GDS) and prevent possible hydrate formation and icing of the station equipment. Paper considers the implementation of fireless heating of natural gas and fuel gas savings of heaters due to the introduction of a thermoacoustic reducer, operating on the basis of the Hartmann – Sprenger resonance effect, into the scheme of the reduction unit. By analyzing the existing methods of energy separation and numerical modeling, the effectiveness of the resonant-type energy separation device is substantiated. Modification of the reduction unit by introducing energy separating devices into it will allow general or partial heating of natural gas by its own pressure energy. Developed technology will allow partial (in the future, complete) replacement of heat energy generation at a gas distribution station by burning natural gas.
-
Date submitted2019-10-17
-
Date accepted2020-01-24
-
Date published2020-04-24
Composition and probable ore igneous rocks source of columbite from alluvial deposits of Mayoko district (Republic of the Congo)
The article presents the results of optical, electron microscopic and electron microprobe studies of columbite group minerals, collected during heavy mineral concentrate sampling of alluvial deposits in the Mayoko region (Republic of the Congo). The aim of the study is revealing tantalum niobates ore body in this region. We found that these minerals in loose deposits are represented by two grain-size groups: less than 1.6 mm (fine fraction) and 1.6-15 mm (coarse fraction). The grains of both fractions belong mainly to columbite-(Fe), less often to columbite-(Mn), tantalite-(Mn) and tantalite-(Fe), contain impurities of Sc, Ti, and W. The crystals have micro-scaled zoning (zones varies slightly in the Ta/Nb ratio values) and contains a lot of mineral inclusions and veins represented by zircon, pyrochlore supergroup minerals and others. Columbite-(Fe) and columbite-(Mn) are characterized by an increased content of Ta 2 O 5 up to the transition to tantalite-(Fe) and tantalite-(Mn). This allows us to exclude the formation of subalkaline rare-metal granites, their metasomatites (albitites and greisenes) and carbonatites, from the list of possible columbite ore rocks source in the Mayoko district. Thus, beryl type and complex spodumene subtype rare-element pegmatites of the mixed petrogenetic family LCT-NYF (according to P.Černý) should be considered as a probable root source. The results of the research should be taken into account when developing the methodology for prospecting in this area.