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Wyświetlanie 1-15 z 34
Tytuł:
The influence of holmium on catalytic properties of Fe or Cu-modified vermiculites
Autorzy:
Samojeden, Bogdan
Grzybek, Teresa
Kowal, Joanna
Szymaszek, Agnieszka
Jabłońska, Magdalena
Gläser, Roger
Motak, Monika
Powiązania:
https://bibliotekanauki.pl/articles/109844.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
selective catalytic reduction
deNOx
holmium
vermiculite
Opis:
Natural layered clay, vermiculite, was modified and tested as catalyst for the selective catalytic reduction of NOx with ammonia (NH3-SCR). Its modification included the application of the blowing agent (azodicarbonamide), acid treatment and pillaring with Al2O3. Active phase (transition metals: Cu or Fe) was introduced via impregnation. The obtained materials were characterized by N2 sorption (texture), XRD (structure), DR-UV-Vis (oxidation state and aggregation of the active phase), H2-TPR (reducibility of the active phase), in situ DRIFTS (types of adsorbed species due to contact of the sample NH3) and NH3-TPD (type/strength of the acidic sites). The initial modification procedures (treatment with azodicarboamide) resulted in the increase of specific surface area of vermiculite. The introduction of transition metal ions provided a significant amount of acidic sites. The promoting impact of holmium was confirmed by the increased strength of the sites. The highest catalytic activity was exhibited by the sample Fe-containing vermiculite and doped with Ho.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 6; 1484-1495
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Method for efficient distribution of means to reduce CO2 emissions in a set of power plants
Autorzy:
Kałuszko, A.
Powiązania:
https://bibliotekanauki.pl/articles/406407.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
CO2 emissions
reduction
dynamic programming
Opis:
A method for the allocation of technologies of reduction of CO2 emission to sources of emissions based on dynamic programming has been described. The purpose of the application of the method was to develop an efficient strategy of allocating financial means for reducing CO2 emissions from a set of coal and lignite fired power plants (carbon dioxide sources) which enables reduction of the total emissions to the required level within a given time horizon, at the minimum cost. The application of the method is illustrated based on the set of the 20 largest Polish coal and lignite fired power plants.
Źródło:
Operations Research and Decisions; 2013, 23, 2; 55-65
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Feasibility study on preparation of magnesium titanate in carbonthermic reduction of vanadium titanomagnetite concentrates
Autorzy:
Chen, Chao
Sun, Ti-Chang
Kou, Jue
Wang, Xiao-Ping
Zhao, Yong-Qiang
Powiązania:
https://bibliotekanauki.pl/articles/110181.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
vanadium titanomagnetite
carbonthermic reduction
magnesium titanate
formation mechanism
Opis:
Effect of temperature and Mg:Ti ratio on phase composition and microstructure of reduced pellets was investigated to verify the feasibility of preparation of magnesium titanate by adding MgO in carbonthermic reduction of the vanadium titanomagnetite concentrates (VTC). Thermodynamic analysis results showed that magnesium titanate is more easily generated than FeTi2O5 or TiO2 by the reaction of FeTiO3 and MgO under the reductive atmosphere, which was confirmed by the discovery of magnesium titanate at roast experiment. It was found that the optimum conditions for reduction of VTC pellets were temperature of 1250 ºC and Mg:Ti ratio of 2, and the main phases of reduction product were metallic Fe and magnesium titanate (Mg2TiO4). However, trace iron impurities in Mg2TiO4 particles were found by energy-dispersive spectroscopy (EDS), so further purification is required.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 2; 417-425
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of mechanical activation on carbothermic reduction and nitridation of titanomagnetite concentrates
Autorzy:
Wen, Xiaojin
Yu, Wen
Zeng, Danliang
Zhu, Liang Liang
Chen, Jiangan
Powiązania:
https://bibliotekanauki.pl/articles/1446680.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
titanomagnetite concentrates
carbothermic reduction
mechanical activation
titanium nitride
Opis:
The carbothermic reduction and nitridation process of titanomagnetite concentrates with the help of mechanical activation were investigated by particle size analysis, thermodynamic calculation, thermogravimetric analysis, X-ray diffraction analysis, scanning electron microscopy, and energy-dispersive spectroscopy analysis. The thermogravimetric and X-ray diffraction results indicated that either the reduction of iron oxide or the reduction and nitridation of M3O5 to TiN could be promoted significantly with the increase in activation time. The results obtained from scanning electron microscopy and energy-dispersive spectroscopy showed that, when samples were not activated, chunks of and thin M3O5 were derived from the reduction of ilmenite and titanomagnetite. They were severely sintered with impurities to form a dense structure. As a result, M3O5 was difficult to be converted to TiN, especially chunks of M3O5. However, when samples were activated, the sintering degrees of the impurity and M3O5 were mitigated, and the particle size of the iron as a medium for delivering C to M3O5 was decreased in the roasted product. This condition enhanced the diffusion of C to the surface of M3O5. Meanwhile, the bulk of ilmenite was broken in the activation process, which prevented the formation of chunks of M3O5. Thus, the conversion of M3O5 to TiN was promoted.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 5; 33-45
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Temperature on Fe and Ti in Carbothermic Reduction of Vanadium Titanomagnetite with adding MgO
Autorzy:
Li, Xiaohui
Kou, Jue
Sun, Tichang
Wu, Shichao
Zhao, Yongqiang
Powiązania:
https://bibliotekanauki.pl/articles/110204.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
VTM concentrate
temperature
carbothermic reduction
Fe
magnesium titanate
Opis:
Effects of temperature on Fe and Ti in carbothermic reduction of vanadium titanomagnetite (VTM) concentrate with adding MgO at 1100~1500℃ were investigated. It was found that most of Fe in the VTM concentrate existed in the form of magnetite and a small amount existed as ilmenite; Ti in the VTM concentrate was mainly present in the form of ilmenite. The temperature had significant effects on Fe and Ti: increasing temperature was beneficial to decrease the Fe content in the magnesium titanate mixture, and the Fe content could decrease to 5.47% at 1500℃. Thermodynamic analysis showed that FeTiO3 and MgO preferentially reacted to form Mg2TiO4, followed by MgTiO3 and MgTi2O5 when the temperature increased from 1100℃ to 1500℃. Results of X-ray diffraction and scanning electron microscopy-energy dispersive spectroscopy analyzes showed that an intermediate product of MgFe2O4 would formed at 1300~1400℃ in the actual experiment. This caused the Fe content in the magnesium titanate mixture to increase from 21.32% to 22.85% when the temperature increased from 1200℃ to 1400℃. In addition, the size of magnesium titanate particles could increase from a few microns to approximately 100 µm when the temperature increased from 1100℃ to 1500℃, which was conducive to realize the separation of metallic iron and magnesium titanate.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 4; 917-927
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selective reduction of PbSO4 to PbS with carbon and flotation treatment of synthetic galena
Autorzy:
Zheng, Y.-X.
Liu, W.
Qin, W.-Q.
Han, J.-W.
Yang, K.
Luo, H.-L.
Powiązania:
https://bibliotekanauki.pl/articles/110717.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
wastes
lead sulfate
reduction
carbon
lead sulfide
flotation
Opis:
In order to recover lead from the zinc leaching residues, a new technology involving selective reduction of lead sulfate to lead sulfide with carbon followed by flotation was investigated. The reduction thermodynamics of PbSO4 was discussed and the effects of molar ratio of C to PbSO4, reaction temperature and time were examined by thermogravimetry (TG) and XRD. Verification tests were further carried out to prove the conclusions of thermodynamic and TG analyses, and the transformation extent could reach 86.45% under the optimal roasting conditions. The prepared galena was then subjected to micro-flotation tests, and the highest lead recovery could reach up to 75.32%.
Źródło:
Physicochemical Problems of Mineral Processing; 2015, 51, 2; 535-546
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on recovery of lead, zinc, iron from jarosite residues and simultaneous sulfur fixation by direct reduction
Autorzy:
Wang, Y.
Yang, H.
Zhang, W.
Song, R.
Jiang, B.
Powiązania:
https://bibliotekanauki.pl/articles/110933.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
jarosite
direct reduction
recovery
valuable metal
sulfur fixation
Opis:
Jarosite residues, which are generated in a zinc production plant by a hydrometallurgical process, contain a large amount of valuable metal components. In this study, a method was proposed for the recovery of lead, zinc and iron from the residues and simultaneous sulfur fixation through direct reduction followed by magnetic separation. The influences of the roasting temperature, roasting time and the concentration of SO2 gas in the direct reduction process were researched in detail. Results showed that the volatilization rates of lead, zinc and sulfur were 96.97%, 99.89% and 1.09%, respectively, and the iron metallization rate was 91.97% under optimal reduction conditions; roasting temperature 1523 K for 60 min. The magnetic concentrate with the iron content of 90.59% and recovery rate of 50.87% was obtained from the optimal reduction product by grinding and magnetic separation. The optimum fineness for separation 96.56% less than 37 μm accounted with magnetic field strength 24 kA/m. The theoretical analysis was carried out by thermodynamics, X-ray powder diffraction, gas analysis and scanning electron microscopy.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 2; 517-526
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exposition time analysis of AlGaN/GaN HEMT fabrication by electron beam lithography
Autorzy:
Indykiewicz, Kornelia
Paszkiewicz, Bogdan
Paszkiewicz, Regina
Powiązania:
https://bibliotekanauki.pl/articles/173831.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
electron beam lithography
device fabrication
exposition time reduction
Opis:
Electron beam lithography, due to the high design flexibility and high pattering resolution can be used as an exclusive lithography method in device fabrication in R&D reality. To achieve the reasonable time of process exposition, some essential steps and actions must be done. In the article, the main technical and technological dependences, based on AlGaN/GaN HEMT transistor fabrication, will be presented and discussed. As a result of conducted studies, the total time of the most important lithography process expositions will be shown and explained.
Źródło:
Optica Applicata; 2019, 49, 1; 161-166
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects and mechanism of Bayer red mud on co-reduction with a saprolitic laterite ore to prepare ferronickel
Autorzy:
Wang, Xiaoping
Sun, Tichang
Wu, Shichao
Hu, Tianyang
Rong, Lingkun
Powiązania:
https://bibliotekanauki.pl/articles/1449072.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
red mud
laterite ore
co-reduction
ferronickel powder
Opis:
Co-reduction of a saprolitic laterite and waste Bayer red mud was investigated to prepare ferronickel powder. The synchronous reduction and comprehensive recovery of nickel and iron in the low-grade laterite ores and iron in the red mud were realized. At the red mud dosage of 50 wt%, ferronickel powder with nickel and iron grades of 5.58 wt% and 89.91 wt% was obtained. The corresponding nickel and total iron recoveries were 93.11 wt% and 90.23 wt%, respectively. The red mud enhanced the nickel recovery of the saprolitic laterite ore evidently, attributing to the formation of low-melting anorthite, omphacite, and diopside during co-reduction. This led that NiO in the saprolitic ore was released. Meanwhile, obvious melting phenomenon of the roasting system was appeared, enhancing the growth of the ferronickel particles.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 4; 641-652
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analysis of excavation support safety based on experimental studies
Autorzy:
Gorska, K.
Wyjadłowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/178652.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
soldier pile wall
inclinometer measurements
φ/c reduction procedure
Opis:
The article presents the results of inclinometric measurements and numerical analyses of soldier-pile wall displacements. The excavation under investigation was made in cohesive soils. The measurements were conducted at points located at the edge of the cantilever excavation support system. The displacements of the excavation support observed over the period of three years demonstrated the pattern of steady growth over the first two months, followed by a gradual levelling out to a final plateau. The numerical analyses were conducted based on 3D FEM models. The numerical analysis of the problem comprise calculations of the global structural safety factor depending on the displacement of the chosen points in the lagging and conducted by means of the φ/c reduction procedure. The adopted graphical method of safety estimation is very conservative in the sense that it recognizes stability loss quite early, when one could further load the medium or weaken it by further strength reduction. The values of the Msf factor are relatively high. This is caused by the fact that the structure was designed for excavation twice as deep. Nevertheless, the structure is treated as a temporary one.
Źródło:
Studia Geotechnica et Mechanica; 2015, 37, 3; 19-29
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of harmonic vibration of cable-stayed footbridge under the influence of changes of the cables tension
Autorzy:
Pakos, W.
Powiązania:
https://bibliotekanauki.pl/articles/178830.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
cable-stayed footbridge
FEM model
harmonic vibration
vibration reduction
Opis:
The paper presents numerical analysis of harmonically excited vibration of a cable-stayed footbridge caused by a load function simulating crouching (squats) while changing the static tension in chosen cables. The intentional synchronized motion (e.g., squats) of a single person or group of persons on the footbridge with a frequency close to the natural frequency of the structure may lead to the resonant vibrations with large amplitudes. The appropriate tension changes in some cables cause detuning of resonance on account of stiffness changes of structures and hence detuning in the natural frequency that is close to the excitation frequency. The research was carried out on a 3D computer model of a real structure – a cable-stayed steel footbridge in Leśnica, a quarter of Wrocław, Poland, with the help of standard computer software based on FEM COSMOS/M System.
Źródło:
Studia Geotechnica et Mechanica; 2015, 37, 3; 63-71
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An innovative rainwater system as an effective alternative for cubature retention facilities
Autorzy:
Stanowska, Patrycja
Dziopak, Józef
Słyś, Daniel
Starzec, Mariusz
Powiązania:
https://bibliotekanauki.pl/articles/2037699.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
innovative rainwater system
sewage retention canal
rainwater retention
flow reduction
Opis:
The paper focuses on the possibilities of rainwater flow control in an innovative rainwater system which is equipped with a retention canals system. Sewage retention canal is a modern solution that provides effective retention of excess rainwater by using a capacity of sewer pipes and manholes. The retention is possible by using special damming partitions which have flow openings. The hydraulic working of the traditional rainwater system and the innovative rainwater system were compared with each other. The analysis was based on the results obtained from simulations using hydrodynamic modeling. Maximum possible values of rainwater outflow intensity from outlet nodes for the traditional rainwater system and the innovative rainwater system were discussed. On the basis of the analysis it was shown that the innovative rainwater system outweighs the classic rainwater one. It discharges two functions: transports and simultaneously retains excess rainwater in canals.
Źródło:
Studia Geotechnica et Mechanica; 2021, 43, s1; 532-547
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sorption and reduction of chromiumion ions by the chelating ion exchanger Diaion CR20
Autorzy:
Wójcik, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/109632.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
chromium(III)
chromium(VI)
reduction
ion exchange
speciation
chelating resin
Opis:
The chelating ion exchanger Diaion CR20 was applied for removal of chromium(VI) ions in the pH range from 1.5 to 10 and in the presence of 1 M H2SO4. The speciation analysis was used to predict the reduction process. Reduction of chromium(VI) to chromium (III) was observed during the chromium(VI) ions sorption. The kinetic parameters for the pseudo-first-order and pseudo-second-order, Elovich and intraparticle diffusion models were calculated. The most common three isotherm models: Freundlich, Langmuir and Dubinin-Radushkevich were used to describe chromium(VI) uptake. It was proved that the polyamine groups present in selected ion exchanger are able to sorb both chromium(VI) and (III) ions. The maximal sorption capacity towards chromium(VI) ions was estimated at pH 1.5 – 169.49 mg Cr(VI)/g and 159.31 mg Cr(VI)/g in 1 M H2SO4. Both static and column methods were used in the investigations.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 6; 1382-1393
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An innovative technology for recovery of zinc, lead and silver from zinc leaching residue
Autorzy:
Zheng, Y.-X.
Lv, J.-F.
Liu, W.
Qin, W.-Q.
Wen, S.-M.
Powiązania:
https://bibliotekanauki.pl/articles/110688.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
zinc leaching residue
lead sulfate
zinc sulfate
reduction roasting
flotation
Opis:
Zinc leaching residue is a good source of zinc and has a great potential to be utilized. However, it is very difficult to recover lead, zinc and silver from the residue by traditional technologies. In this study, a new technology based on conversions of PbSO4 and ZnSO4 in the residue to their respective sulfides by reduction roasting with coal powder followed by a flotation treatment was developed. The effects of roasting temperature, coal dosage, reaction time and pyrite dosage were investigated at a laboratory scale. The results showed that the conversion extent of PbSO4 and ZnSO4 under the optimal experimental conditions was 71.89 and 69.76%, respectively. A flotation concentrate containing 39.13% Zn, 6.93% Pb and 973.54 g/Mg Ag was obtained from the treated material, and the recovery of Zn, Pb and Ag was 48.38, 68.23 and 77.41%, respectively. The tailing containing ZnFe2O4 or Fe3O4 could be either stockpiled or further disposed.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 2; 943-954
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-temperature carbothermal dephosphorization of Malaysian monazite
Autorzy:
Udayakumar, Sanjith
Sheikh Abdul Hamid, Sheikh Abdul Rezan
Baharun, Norlia
Pownceby, Mark
Powiązania:
https://bibliotekanauki.pl/articles/2146886.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
malaysian monazite concentrate
dephosphorization
carbothermal reduction
rare earth elements
graphite
Opis:
High-temperature carbothermal reduction experiments with graphite powder were conducted to assess the dephosphorization behavior of Malaysian monazite concentrate. Thermodynamic analysis of the possible dephosphorization reactions was conducted to evaluate the feasibility of the carbothermal reduction of the monazite phases. The effects of temperature, particle size, and monazite to carbon ratio were then investigated under different conditions. The carbothermal reduction experiments were conducted based on the Taguchi design method, and up to 97% of phosphorous removal was achieved under optimized conditions. The optimal conditions for dephosphorization were determined as; a reduction temperature of 1350 °C, a particle size of -75 μm, and monazite to carbon molar ratio of 0.3. Microstructural and phase characterization of the dephosphorized products revealed that CeO2, Nd2O3, La2O3, and Pr2O3 oxide phases were prominent, and no residual peaks of monazite remained in the reduced products. The information gained from the study can aid in the design of a suitable post-dephosphorization hydrometallurgical treatment for exploiting Malaysian monazite as a local source of REEs.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 6; 140--155
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 34

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