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Date submitted2024-05-17
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Date accepted2024-10-14
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Date published2024-11-12
Black shales – an unconventional source of noble metals and rhenium
The content of noble metals and rhenium in the Lower Paleozoic black shales of the eastern Baltic paleobasin in Russia was estimated. Shales are enriched in platinoids (PGM to 0.12 g/t) and rhenium (to 1.54 g/t). The main accessory elements of noble metals and Re are U, V, Mo, Cu, and Ni. Black shales consist of organic (9-26 rel.%), clay (40-60 rel.%), and silt-sandy (25-50 rel.%) components and a nodule complex (2-5 rel.%) (carbonate, sulfide, phosphate and silicate nodules). Noble metals occur sporadically in the silt-sandy admixture as native forms and intermetallics: Aunat, Au-Ag, Au-Cu, Au-(Cu)-Hg, Au-Hg, Ag-Cu, Pt-Fe. Micromineral phases of noble metals were found in diagenetic sulfides: Aunat, chalcopyrite with Au admixture, pyrite with platinoid admixture. Clay fraction is 10-fold enriched in noble metals as compared to shale – to 0.28 g/t Au, 0.55 g/t Pt, 1.05 g/t Pd, and 1.56 g/t Re. Organic matter sorbs noble metals to a limited extent but accumulates rhenium. Pore space of black shales contains a colloidal salt component (submicron fraction) which is represented by particles smaller than 1,000 nm. The share of submicron fraction in black shales is 0.1-6 wt.%. The submicron fraction contains on average: PGM – 14 g/t, Au – 0.85 g/t, and Re – 4.62 g/t. The geochemical resource of noble metals (Au, Pt, Pd), Re and the accessory elements (U, V, Mo, Cu, and Ni) for black shales as a whole and their submicron fraction was estimated. Black shales are recommended as an integrated source of raw materials.
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Date submitted2022-03-14
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Date accepted2022-05-13
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Date published2022-07-26
Unique titanium Deposits of Timan: genesis and age issues
The article critically analysesthe hypotheses about the formation, age, and sources of material of large Timan titanium deposits, which were previously considered ancient buried placers formed along the weathering crusts of the Riphean shales. We discuss an alternative hydrothermal-metamorphic hypothesis about the formation of these deposits and the source of ore material. It is established that the incoming zircon of different ages (570-3200 Ma), as well as two other geochronometers, rutile and monazite, underwent a thermal effect common for all varieties as a result of a hydrothermal process about 600 Ma ago. According to modern concepts, the closing temperature of the U-Pb system in rutile exceeds 500 °С, which suggests high-temperature conditions for the hydrothermal processing of rutile during the formation of the considered deposits in the Riphean.
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Date submitted2020-04-15
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Date accepted2020-05-13
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Date published2020-10-08
Processing of platinum group metal ores in Russia and South Africa: current state and prospects
- Authors:
- Tatyana N. Aleksandrova
- Cyril О’Connor
The presented study is devoted to a comparative review of the mineral raw material base of platinum group metals (PGMs) and technologies of their processing in South Africa and Russia, the largest PGM producers. Mineralogical and geochemical classification and industrial value of iron-platinum and platinum-bearing deposits are presented in this work. The paper also reviews types of PGM ore body occurrences, ore processing methods (with a special focus on flotation processes), as well as difficulties encountered by enterprises at the processing stage, as they increase recovery of the valuable components. Data on mineralogical features of PGM deposits, including the distribution of elements in the ores, are provided. The main lines of research on mineralogical features and processing of raw materials of various genesis are identified and validated. Sulfide deposits are found to be of the highest industrial value in both countries. Such unconventional PGM sources, as black shale, dunites, chromite, low-sulfide, chromium and titanomagnetite ores, anthropogenic raw materials, etc. are considered. The main lines of research that would bring into processing non-conventional metal sources are substantiated. Analysis of new processing and metallurgical methods of PGM recovery from non-conventional and industrial raw materials is conducted; the review of existing processing technologies for platinum-bearing raw materials is carried out. Technologies that utilize modern equipment for ultrafine grinding are considered, as well as existing reagents for flotation recovery; evaluation of their selectivity in relation to platinum minerals is presented. Basing on the analysis of main technological processes of PGM ore treatment, the most efficient schemes are identified, i.e.,gravity and flotation treatment with subsequent metallurgical processing.
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Date submitted2018-09-07
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Date accepted2018-11-08
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Date published2019-02-22
Assessment of refractory gold-bearing ores based on interpretation of thermal analysis data
- Authors:
- T. N. Aleksandrova
- G. Heide
- A. V. Afanasova
The article presents the results of a study on the possibility to assess refractory gold-bearing ores using thermal analysis data. It studies the flotation concentrates obtained during the enrichment of double refractory sulfide gold-bearing ores. This type of ore is complicated by the fine impregnation of gold in sulphide minerals and the presence of sorption-active scattered carbonaceous matter, which is in close association with sulphides. The results of thermogravimetric and mass spectrometric studies of refractory gold-bearing ores are presented. The obtained fragments for kerogen CH (m/z = 15), C 2 H (m/z = 29) and C 3 H (m/z = 43) indicate the presence of various types of carbonaceous matter in the studied samples. It is justified that the degree of sorption activity of carbonaceous matter depends on the presence of kerogen and bitumen in the ore. High sorption activity of scattered carbonaceous material significantly affects the processing technology of ores and concentrates, both flotation and pyro- and hydrometallurgical methods. Thermogravimetric and mass spectroscopic analyzes can be used to determine the degree of preg-robbing of refractory gold-bearing ores. The obtained results predetermine the direction of creating new methods and technologies in the field of decarburization of refractory gold-bearing ores in the integrated development of solid minerals in the mining regions of Russia.
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Date submitted2017-11-09
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Date accepted2017-12-28
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Date published2018-04-24
Chemical weathering of lower paleozoic black shales of south Sweden
- Authors:
- D. O. Voronin
- E. G. Panova
Lower Paleozoic black shales are widespread in Sweden and form part of the Baltic paleobasin, which deposits are also known in Estonia and the Leningrad Oblast of Russia. These rocks are enriched in a carbon substance and characterized by the significant content of uranium, vanadium, molybdenum, copper, nickel, cobalt, zinc, and lead. Black shales contain high levels of Sr – 968; Ba – 337; U – 229; V – 509; Mo – 165; Zn – 411; Ni – 214; Cu – 112 (ppm) in secondary minerals composition formed on their surface. Retrograde diagenetic conditions facilitate the black shales chemical weathering. Elements of the first (U), second (Mo, Sr, Zn), and third (V) hazard classes are washed out of black shales and secondary minerals and can further enter biological cycles.
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Date submitted2015-10-03
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Date accepted2015-12-10
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Date published2016-08-22
Directions and prospects of using low grade process fuel to produce alumina
- Authors:
- O. A. Dubovikov
- V. N. Brichkin
Power consumption across the globe is constantly increasing for a variety of reasons: growing population, industrialization and fast economic growth. The most widespread gaseous fuel – natural gas – has the low production cost. It is 2-3 times cheaper than liquid fuel production and 6-12 times cheaper than coal production. When natural gas is transported to distances from 1.5 to 2.5 thousand km by the pipeline, its cost with account of transportation is 1.5-2 times less than the cost of coal and the fuel storage facilities are not needed. Plants powered by natural gas have the higher efficiency as compared to the plants operating on other types of fuel. They are easier and cheaper to maintain and are relatively simple in automation, thus enhancing safety and improving the production process flow, do not require complicated fuel feeding or ash handling systems. Gas is combusted with a minimum amount of polluting emissions, which adds to better sanitary conditions and environment protection. But due to depletion of major energy resources many experts see the future of the global energy industry in opportunities associated with the use of solid energy carriers. From the environmental perspective solid fuel gasification is a preferred technology. The use of synthetic gas was first offered and then put to mass scale by English mechanical engineer William Murdoch. He discovered a possibility to use gas for illumination by destructive distillation of bituminous coal. After invention of the gas burner by Robert Bunsen, the illumination gas began to be used as a household fuel. The invention of an industrial gas generator by Siemens brothers made it possible to produce a cheaper generator gas which became a fuel for industrial furnaces. As the calorific value of generator gas produced through gasification is relatively low compared to natural gas, the Mining University studied possibilities to use different types of low grade process fuel at the Russian alumina refineries as an alternative to natural gas, access to which is restricted for some of the regions.
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Date submitted2015-10-07
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Date accepted2015-12-01
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Date published2016-08-22
Evaluating possible industrial applications of combustible shales and shale ash wastes
- Authors:
- N. K. Kondrasheva
- S. N. Saltykova
Today energy consumption is constantly growing while explored reserves of easily accessible oil are depleting, which is a reason why most countries tend to diversify their energy mix, develop non-hydrocarbon energy sources and use domestic types of fuel, including the low grade ones. Thereby interest is raised to such a source of hydrocarbons as combustible shales. Combustible shales appear to be one of the highest-potential types of organic raw materials, which may offset and in future even substitute oil products and gas. The paper is investigating behavior and structure of combustible shales during heat treatment in order to identify their possible industrial applications. A synchronous thermal analysis has been held, chemical composition of combustible shales’ mineral fraction and optimal conditions for shale fines briquetting have been determined.
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Date submitted2015-07-24
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Date accepted2015-09-29
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Date published2016-02-24
Geochemical features and prospects of ore content in black slates in Tajmyr-Severnaya zemlya gold formation
- Authors:
- A. N. Evdokimov
- V. I. Fokin
- N. K. Shanurenko
Gold content, at least twice higher than the gold percentage abundance in Earth’s crust, has been discovered in a number of black slates formations in Tajmyr-Severnaya Zemlya gold province. The article shows the measurement data on organic carbon and ore elements concentrations in carbonaceous sediments, with pyrite, being their constituent, in the region. The dependence of ore elements availability, including gold, on sulphidisation degree in rocks has been identified in an ore bundle of Golyshevskaja strata. The comparison of gold concentrations in sampled monocrystals and pyrite aggregates has been carried out. It has been empirically supported that the content of gold, lead, molybdenum, cobalt, nickel and copper normally grows with the increase of sulphides quantity. Concentrations of chromium, manganese, tin, vanadium decrease respectively; however, titanium and zinc content remains unchanged.
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Date submitted2015-07-26
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Date accepted2015-09-12
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Date published2016-02-24
Technological aspects of extraction of precious and rare metals from carbonaceous rocks
- Authors:
- T. N. Aleksandrova
- E. G. Panova
The results of mineralogical, geochemical and technological research of black shale rocks are given. It is proved that black shales are now regarded as a new promising and innovative source of precious and rare-metal raw materials. It is pointed out that 3 wt. % of black shales samples is colloid-salt fraction (nanofraction) with a particle size less than 1000 nm and it can be extracted with water under specially chosen conditions. The use of water instead of chemically active reagents guarantees the absence of dissolved mineral matrix and clearly shows the colloidal salt component in samples. The results determine the direction of creating some new methods and technologies of carbonaceous feed dressing for integrated development of solid minerals in the mining and oil producing regions of Russia.