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Volumen 49 (2018): Edición 1-4 (December 2018)

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Detalles de la revista
Formato
Revista
eISSN
1899-8526
Publicado por primera vez
05 Feb 2007
Periodo de publicación
1 tiempo por año
Idiomas
Inglés

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Volumen 49 (2018): Edición 1-4 (December 2018)

Detalles de la revista
Formato
Revista
eISSN
1899-8526
Publicado por primera vez
05 Feb 2007
Periodo de publicación
1 tiempo por año
Idiomas
Inglés

Buscar

7 Artículos
Acceso abierto

Jiři Konta (1922-2017)

Publicado en línea: 02 Mar 2019
Páginas: 3 - 5

Resumen

Acceso abierto

Influence of liquid-nitrogen freezing of gas-bearing shale rocks on their compressive strength

Publicado en línea: 02 Mar 2019
Páginas: 7 - 16

Resumen

Abstract

Any definable relation between falling temperature and the compressive strength of shale rocks should provide a useful predictive tool aiding optimization of the results of hydraulic fracturing. In this research, an automeasuring hydraulic press, a thermo-camera and the Fluent ANSYS software were used. The results of laboratory simulations, and the effects of experiments conducted on shale rocks to determine permanent changes in compressive strength, are presented. As both frozen rocks and rocks returned to room temperature show diminished compressive strength. It is suggested that prior freezing of rocks can increase the efficiency of fracturing.

Palabras clave

  • hydraulic fracturing
  • black shales
  • freezing
  • compressive strength
  • modelling
Acceso abierto

Polymetamorphic evolution of pelites inferred from tourmaline zoning – the Rędziny hornfels case study at the eastern contact of the Karkonosze Granite, Sudetes, Poland

Publicado en línea: 02 Mar 2019
Páginas: 17 - 34

Resumen

Abstract

Tourmaline occurring in hornfelses from the eastern envelope of the Karkonosze Granite (Western Sudetes, Poland) reveals at least two stages of crystallization expressed by its complex zoning. The cores and mantles of the crystals probably grew during prograde metamorphism under intermediate pressure-temperature conditions reflected by increasing Mg, Ti and Ca. Outermost rims show enrichment in Al and Ca, indicating growth during contact metamorphism in the presence of an Al-saturating phase. The Ti-content in biotite indicates that the temperature of the contact metamorphic event did not exceed 650ºC. The presence of andalusite and the lack of garnet and cordierite also indicates pressure conditions of ~ 2-3 kbar, typical of the C1 bathozone of Carmichael (1978) or the P1 bathozone of Pattison (2001).

Palabras clave

  • contact metamorphism
  • tourmaline
  • Ti-in biotite
  • Karkonosze-Izera Massif
  • Bohemian Massif
Acceso abierto

Coke and coal as reductants in manganese ore smelting: An experiment

Publicado en línea: 02 Mar 2019
Páginas: 35 - 45

Resumen

Abstract

The effect of coke and bituminous coal on the reduction of medium-grade manganese ore in ferromanganese production was investigated. Charges of 30 kg medium grade manganese ore, 12 kg limestone and varied amounts of coke and coal were smelted in a Submerged Electric Arc Furnace (SAF) at temperatures of 1300°C to 1500°C. The composition of the ferromanganese and the slag were determined by X-Ray Fluorescence. It was found that using coke as a single reductant resulted in a 96% yield of ferromanganese which was higher than by using coal either as a single reductant or in a mixture of coal and coke. It was also found that using coke as a single reductant resulted in the lowest specific energy consumption. Using coal as reductant produced ferromanganese containing high sulfur and phosphorus.

Palabras clave

  • ferromanganese
  • manganese ore
  • coke
  • coal
  • Submerged Electric Arc Furnace (SAF)
Acceso abierto

Trace elements and REE enrichment at Seboah Hill, SW Egypt

Publicado en línea: 02 Mar 2019
Páginas: 47 - 65

Resumen

Abstract

Seboah Hill - a small body of peralkaline granite (< 0.1 km2) in south-western Egypt containing aegirine minerals ± magnesiohornblende ± riebeckite, cut by dikes of riebeckite-aegirine rhyolite, and exhibiting high radioactivity in veins of K-feldspar-aegirine-chalcedony-quartz ± trace hematite ± trace goethite was sampled and analyzed using inductively coupled plasma methods. Whole-rock chemical compositions of 5 granite, 3-rhyolitedike and 10 radioactive vein samples are presented. Of special significance is the enrichment of trace elements and rare earth elements (REE) in the radioactive veins. These include up to 6081 ppm Zr, 4252 ppm Ce, 1514 ppm Nd, 1433 ppm La, 1233 ppm Nb, 875 ppm Y, 388 ppm Pr, 350 ppm Th, 222 ppm Sm, 189 ppm Gd, 159 ppm Dy, 153 ppm Hf, 83 ppm Er, 76 ppm Yb and 58 ppm U. The chondrite-normalized patterns of REE in all samples show only limited variation and have negative europium (Eu) anomalies. These findings suggest that the sources of the REE are genetically related. Values of the Eu anomalies vary from 0.38-0.41 for the radioactive veins, 0.39-0.53 for the granite and 0.31-0.44 for the rhyolite dikes. Eu variations are consistent for different paragentic stages.

Palabras clave

  • Oversaturated peralkaline rocks
  • trace elements
  • REE
  • thorium/uranium anomalies
Acceso abierto

Mineralogy, chemical composition and leachability of ash from biomass combustion and biomass–coal co-combustion

Publicado en línea: 02 Mar 2019
Páginas: 67 - 97

Resumen

Abstract

Ash samples from biomass combustion or co-combustion with coal were analysed. The aim of this study of ash was to determine its mineral and chemical composition, and the chemical composition of solutions obtained during one-step water extraction. Besides the chemical analysis, X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS) were applied.

The mineral and chemical composition of ash samples differ strongly. The content of heavy metals in the ash is generally low, but in some samples the limits of the content of some elements determined for fertilizers or soil amendments are exceeded. The relatively poor correlation between the concentration in leachate and bulk content in ash indicates that numerous elements are present in different forms in the studied samples. The results indicate that the potential use of biomass ash, or ash from biomass–coal co-combustion, requires complex studies that explore ash and leachates.

Palabras clave

  • biomass ash
  • mineral and chemical composition
  • leachability
  • biomass combustion and biomass–coal co-combustion
  • hazardous elements
Acceso abierto

Synneusis: does its preservation imply magma mixing?

Publicado en línea: 02 Mar 2019
Páginas: 99 - 117

Resumen

Abstract

The Ghansura Felsic Dome (GFD) occurring in the Bathani volcano-sedimentary sequence was intruded by mafic magma during its evolution leading to magma mixing. In addition to the mafic and felsic rocks, a porphyritic intermediate rock occurs in the GFD. The study of this rock may significantly contribute toward understanding the magmatic evolution of the Ghansura dome. The porphyritic rock preserves several textures indicating its hybrid nature, i.e. that it is a product of mafic-felsic magma mixing. Here, we aim to explain the origin of the intermediate rock with the help of textural features and mineral compositions. Monomineralic aggregates or glomerocrysts of plagioclase give the rock its characteristic porphyritic appearance. The fact that the plagioclase crystals constituting the glomerocrysts are joined along prominent euhedral crystal faces suggests the role of synneusis in the formation of the glomerocrysts. The compositions of the glomerocryst plagioclases are similar to those of plagioclases in the mafic rocks. The results from this study indicate that the porphyritic intermediate rock formed by the mixing of a crystal-rich mafic magma and a crystal-poor felsic melt.

Palabras clave

  • hybrid rock
  • glomerocrysts
  • porphyritic
  • plagioclase
  • Bathani volcano-sedimentary sequence
7 Artículos
Acceso abierto

Jiři Konta (1922-2017)

Publicado en línea: 02 Mar 2019
Páginas: 3 - 5

Resumen

Acceso abierto

Influence of liquid-nitrogen freezing of gas-bearing shale rocks on their compressive strength

Publicado en línea: 02 Mar 2019
Páginas: 7 - 16

Resumen

Abstract

Any definable relation between falling temperature and the compressive strength of shale rocks should provide a useful predictive tool aiding optimization of the results of hydraulic fracturing. In this research, an automeasuring hydraulic press, a thermo-camera and the Fluent ANSYS software were used. The results of laboratory simulations, and the effects of experiments conducted on shale rocks to determine permanent changes in compressive strength, are presented. As both frozen rocks and rocks returned to room temperature show diminished compressive strength. It is suggested that prior freezing of rocks can increase the efficiency of fracturing.

Palabras clave

  • hydraulic fracturing
  • black shales
  • freezing
  • compressive strength
  • modelling
Acceso abierto

Polymetamorphic evolution of pelites inferred from tourmaline zoning – the Rędziny hornfels case study at the eastern contact of the Karkonosze Granite, Sudetes, Poland

Publicado en línea: 02 Mar 2019
Páginas: 17 - 34

Resumen

Abstract

Tourmaline occurring in hornfelses from the eastern envelope of the Karkonosze Granite (Western Sudetes, Poland) reveals at least two stages of crystallization expressed by its complex zoning. The cores and mantles of the crystals probably grew during prograde metamorphism under intermediate pressure-temperature conditions reflected by increasing Mg, Ti and Ca. Outermost rims show enrichment in Al and Ca, indicating growth during contact metamorphism in the presence of an Al-saturating phase. The Ti-content in biotite indicates that the temperature of the contact metamorphic event did not exceed 650ºC. The presence of andalusite and the lack of garnet and cordierite also indicates pressure conditions of ~ 2-3 kbar, typical of the C1 bathozone of Carmichael (1978) or the P1 bathozone of Pattison (2001).

Palabras clave

  • contact metamorphism
  • tourmaline
  • Ti-in biotite
  • Karkonosze-Izera Massif
  • Bohemian Massif
Acceso abierto

Coke and coal as reductants in manganese ore smelting: An experiment

Publicado en línea: 02 Mar 2019
Páginas: 35 - 45

Resumen

Abstract

The effect of coke and bituminous coal on the reduction of medium-grade manganese ore in ferromanganese production was investigated. Charges of 30 kg medium grade manganese ore, 12 kg limestone and varied amounts of coke and coal were smelted in a Submerged Electric Arc Furnace (SAF) at temperatures of 1300°C to 1500°C. The composition of the ferromanganese and the slag were determined by X-Ray Fluorescence. It was found that using coke as a single reductant resulted in a 96% yield of ferromanganese which was higher than by using coal either as a single reductant or in a mixture of coal and coke. It was also found that using coke as a single reductant resulted in the lowest specific energy consumption. Using coal as reductant produced ferromanganese containing high sulfur and phosphorus.

Palabras clave

  • ferromanganese
  • manganese ore
  • coke
  • coal
  • Submerged Electric Arc Furnace (SAF)
Acceso abierto

Trace elements and REE enrichment at Seboah Hill, SW Egypt

Publicado en línea: 02 Mar 2019
Páginas: 47 - 65

Resumen

Abstract

Seboah Hill - a small body of peralkaline granite (< 0.1 km2) in south-western Egypt containing aegirine minerals ± magnesiohornblende ± riebeckite, cut by dikes of riebeckite-aegirine rhyolite, and exhibiting high radioactivity in veins of K-feldspar-aegirine-chalcedony-quartz ± trace hematite ± trace goethite was sampled and analyzed using inductively coupled plasma methods. Whole-rock chemical compositions of 5 granite, 3-rhyolitedike and 10 radioactive vein samples are presented. Of special significance is the enrichment of trace elements and rare earth elements (REE) in the radioactive veins. These include up to 6081 ppm Zr, 4252 ppm Ce, 1514 ppm Nd, 1433 ppm La, 1233 ppm Nb, 875 ppm Y, 388 ppm Pr, 350 ppm Th, 222 ppm Sm, 189 ppm Gd, 159 ppm Dy, 153 ppm Hf, 83 ppm Er, 76 ppm Yb and 58 ppm U. The chondrite-normalized patterns of REE in all samples show only limited variation and have negative europium (Eu) anomalies. These findings suggest that the sources of the REE are genetically related. Values of the Eu anomalies vary from 0.38-0.41 for the radioactive veins, 0.39-0.53 for the granite and 0.31-0.44 for the rhyolite dikes. Eu variations are consistent for different paragentic stages.

Palabras clave

  • Oversaturated peralkaline rocks
  • trace elements
  • REE
  • thorium/uranium anomalies
Acceso abierto

Mineralogy, chemical composition and leachability of ash from biomass combustion and biomass–coal co-combustion

Publicado en línea: 02 Mar 2019
Páginas: 67 - 97

Resumen

Abstract

Ash samples from biomass combustion or co-combustion with coal were analysed. The aim of this study of ash was to determine its mineral and chemical composition, and the chemical composition of solutions obtained during one-step water extraction. Besides the chemical analysis, X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS) were applied.

The mineral and chemical composition of ash samples differ strongly. The content of heavy metals in the ash is generally low, but in some samples the limits of the content of some elements determined for fertilizers or soil amendments are exceeded. The relatively poor correlation between the concentration in leachate and bulk content in ash indicates that numerous elements are present in different forms in the studied samples. The results indicate that the potential use of biomass ash, or ash from biomass–coal co-combustion, requires complex studies that explore ash and leachates.

Palabras clave

  • biomass ash
  • mineral and chemical composition
  • leachability
  • biomass combustion and biomass–coal co-combustion
  • hazardous elements
Acceso abierto

Synneusis: does its preservation imply magma mixing?

Publicado en línea: 02 Mar 2019
Páginas: 99 - 117

Resumen

Abstract

The Ghansura Felsic Dome (GFD) occurring in the Bathani volcano-sedimentary sequence was intruded by mafic magma during its evolution leading to magma mixing. In addition to the mafic and felsic rocks, a porphyritic intermediate rock occurs in the GFD. The study of this rock may significantly contribute toward understanding the magmatic evolution of the Ghansura dome. The porphyritic rock preserves several textures indicating its hybrid nature, i.e. that it is a product of mafic-felsic magma mixing. Here, we aim to explain the origin of the intermediate rock with the help of textural features and mineral compositions. Monomineralic aggregates or glomerocrysts of plagioclase give the rock its characteristic porphyritic appearance. The fact that the plagioclase crystals constituting the glomerocrysts are joined along prominent euhedral crystal faces suggests the role of synneusis in the formation of the glomerocrysts. The compositions of the glomerocryst plagioclases are similar to those of plagioclases in the mafic rocks. The results from this study indicate that the porphyritic intermediate rock formed by the mixing of a crystal-rich mafic magma and a crystal-poor felsic melt.

Palabras clave

  • hybrid rock
  • glomerocrysts
  • porphyritic
  • plagioclase
  • Bathani volcano-sedimentary sequence

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