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Wyświetlanie 1-9 z 9
Tytuł:
Comparison study of crystal and electronic structures for chalcopyrite $(CuFeS_2)$ and pyrite $(FeS_2)$
Autorzy:
Li, Yuqiong
Liu, Yingchao
Chen, Jianhua
Zhao, Cuihua
Cui, Weiyong
Powiązania:
https://bibliotekanauki.pl/articles/1448811.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
chalcopyrite
pyrite
crystal structures
electronic structures
Opis:
Chalcopyrite $(CuFeS_2)$ and pyrite $(FeS_2)$ are commonly associated with each other, and they both belong to semiconductor minerals. The difference in crystal and electronic structures is an important factor for their flotation separation. Using the density functional method (DFT) combined with Hubbard U correction, their crystal and electronic properties are comparatively studied. The calculated results suggest that the use of antiferromagnetic calculations and Hubbard U correction are very important to the accuracy of the chalcopyrite results. Antiferromagnetic calculations combined with a U value of 2.0 eV on chalcopyrite show a band gap of 0.53 eV, which is very consistent with the experimental results of ~0.5 eV. The density of states (DOS) and Mulliken bond population results indicate that stronger hybridization between Fe 3d and S 3p states in chalcopyrite than in pyrite leads to a stronger covalency of Fe-S bonds in chalcopyrite, causing a reduction in the spin magnetic moment (3.5 μB) from the ideal value. In addition, the greater covalency of bonds in chalcopyrite results in greater hydrophobicity of chalcopyrite than pyrite. The DOS results suggest that S has similar electronic properties in pyrite and chalcopyrite. The oxidation states of Fe and Cu ions in chalcopyrite are discussed based on the coordination field theory according to the calculation results, which confirms an oxidation state of $Fe^{3+}Cu^{1+}S_2$.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 1; 100-111
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigating the selectivity of calcium hypochlorite for flotation separation of chalcopyrite and pyrite pre-adsorbed collector
Autorzy:
Yang, Wenhui
Qiu, Xianhui
Yan, Huashan
Wu, Hao
Yang, Liu
Lai, Ruisen
Qiu, Tingsheng
Powiązania:
https://bibliotekanauki.pl/articles/2146919.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
pyrite
chalcopyrite
calcium hypochlorite
flotation separation
Opis:
Bulk flotation is usually used in the flotation of Cu-Fe sulfide ore, and the subsequent concentrate is difficult to be separated because the minerals have adsorbed the collector. In this paper, flotation tests showed that calcium hypochlorite (Ca(ClO)2) had a stronger depression effect on pyrite pre-adsorbed sodium butyl xanthate (SBX), while having a negligible depressive effect on chalcopyrite. A copper concentrate with Cu grade of 33.32% and Cu recovery of 94.47% could be obtained from flotation tests of mixed minerals. The depression performance and mechanism of Ca(ClO)2 were studied by contact angle measurements, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses, the results suggested that Ca(ClO)2 can decomposes SBX on the pyrite surface and oxidizes the mineral surface to form hydrophilic substances, which enhances the hydrophilicity of the pyrite surface. In contrast, Ca(ClO)2 has little effect on chalcopyrite pre-adsorbed SBX, the possible depression model is discussed.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 4; art. no. 150703
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Physico-chemical factors in flotation of Cu-Mo-Fe ores with seawater: a critical review
Autorzy:
Castro, S.
Powiązania:
https://bibliotekanauki.pl/articles/109447.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
pyrite
chalcopyrite
molybdenite
Seawater flotation
Metabisulfite
Opis:
This paper aims to provide a comprehensive review on the physico-chemical factors governing the flotation of Cu-Mo-Fe sulfide ores in seawater, which is different from NaCl or KCl solutions because it contains hydrolysable ions such as Mg2+, Ca2+, HCO3-, CO32-, etc., which can precipitate with lime as hydroxides, Ca, and Mg insoluble salts. Under pH 9.0 Mg2+ ions do not depress molybdenite. However, over the critical pH of precipitation of Mg(OH)2 (pH>10.0), molybdenite is strongly depressed in seawater. This detrimental effect on molybdenite discards the use of lime to depress pyrite in Cu-Mo-Fe ores floated in seawater. In plant practice, the use of sodium metabisulfite (MBS) has replaced lime as a pyrite depressant. It works at pH 6.5-7.0 where the natural floatability of molybdenite is enhanced. Consequently, pH control in rougher and cleaning circuits, and the use of MBS to depress pyrite, have allowed the successful use of non-desalinated seawater in flotation of Cu-Mo-Fe sulfide ores at industrial scale.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 4; 1223-1236
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A study on the effect of active pyrite on flotation of porphyry copper ores
Autorzy:
Molaei, N.
Hoseinian, F. S.
Rezai, B.
Powiązania:
https://bibliotekanauki.pl/articles/109515.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
flotation
optimization
collector
chalcopyrite
active pyrite
Opis:
Active pyrite is one of the most undesirable phenomena in the flotation of porphyry copper ores. Misreported pyrite into copper concentrates decreased the grade and recovery of copper. In this study, the effective parameters on the flotation process including grinding condition and chemical parameters were evaluated in order to decrease the active pyrite recovery by flotation. Firstly, optical microscopic and grinding studies were carried out to determine the optimal particle size and grinding time. The results showed that 43 minutes of grinding is necessary to achieve the optimum liberation degree of 53 µm for flotation. Then, the flotation effective parameters such as pH (7.3, 10, 10.5, 11, 11.5 and 12), collector type (Nascol, Aero 407, Aero 3477 and X231), collector concentration (12 and 25 mg/dm3), depressant concentration (0 and 25 mg/dm3) and frother concentration (0 and 25 mg/dm3) were investigated in a Denver-type laboratory flotation cell with a constant capacity of 2.5 dm3. The results showed that the optimal conditions for chalcopyrite flotation were pH of 11.5, Aero 407 as a collector with concentration of 25 mg/dm3, Dowfroth 250 (DF250) as a frother with concentration of 25 mg/dm3 and Na2SO3 as a depressant with concentration of 25 mg/dm3. The type of collector had greater effect on the chalcopyrite flotation than the other parameters. The recovery and grade of chalcopyrite and pyrite were obtained as 79.95%, 49% and 5.3%, 7.98% using the Aero 407, respectively. Under the optimum conditions, the grade of final concentrate increased from 0.94% to 21.3% with three cleaner stages.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 3; 922-933
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of microwave system location on floatability of chalcopyrite and pyrite in a copper ore processing circuit
Autorzy:
Gholami, Hamed
Rezai, Bahram
Mehdilo, Akbar
Hassanzadeh, Ahmad
Yarahmadi, Mohammadreza
Powiązania:
https://bibliotekanauki.pl/articles/109728.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
microwave technology
chalcopyrite
pyrite
comminution circuits
separation efficiency
Opis:
The present work aims at investigating the effect of microwave local positions (i.e. before crushing (BC), after crushing (AC) and after milling (AM)) on microwave-assisted flotation of chalcopyrite and pyrite in a porphyry copper complex deposit. Individual given samples for each state were pre-treated with a variable power microwave at a power level of 90 to 900W for 15, 30, and 60s. Furthermore, froth floatation experiments were carried out using a laboratory mechanical Denver flotation cell on both microwave-treated and untreated samples. Particle surface properties were characterized by a scanning electron microscopy (SEM) and an energy-dispersive X-ray spectroscopy (EDX) analysis. The results showed that the chalcopyrite and pyrite floatabilities increased monotonically by rising the exposure time and power level for the uncrushed preconditioned samples (BC) due to the enhancement of mineral liberation degrees together with the formation of sulphide species and polysulphides on the mineral surfaces. However, flotation results of treated samples for the crushed one (AC) revealed an optimum range. Formation of intensive oxide layers on the mineral surfaces of milled samples (AM) led to a substantial reduction in their recoveries by increasing the microwave’s power level and the sample’s exposure time. The results obtained from mineral’s floatabilities in recleaner stage showed that the microwave-assisted sample at 900W for 30s at BC state favourably provided 5% higher S.E.’s than that of the untreated sample. Finally, it was concluded that the microwave pretreatment of samples induced the best floatability responses if it located before the crusher.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 3; 432-448
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flotation kinetics and thermodynamic behavior of chalcopyrite and pyrite in high alkaline systems
Autorzy:
Yan, H.
Yuan, Q.
Zhou, L.
Qiu, T.
Ai, G.
Powiązania:
https://bibliotekanauki.pl/articles/110078.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
flotation kinetics
pyrite
chalcopyrite
flotation separation
high alkaline
microcalorimetry
Opis:
The monomineral flotation test and microcalorimetry were used to study the flotation kinetics and thermodynamic behavior of chalcopyrite and pyrite in high alkaline systems of lime and NaOH. The results showed that in these systems there were less hydrophilic substances on the chalcopyrite surface, so that the apparent activation energy of sodium butyl xanthate (SBX) adsorption on chalcopyrite surface was low. This promoted the adsorption of SBX and increased the flotation rate and recovery of chalcopyrite. In contrast, the hydrophilic Fe(OH)3 and SO42- formed by oxidation on the pyrite surface increased the adsorption activation energy of SBX. Thus, the flotation rate and recovery of pyrite were lower. Moreover, in the lime high alkaline system, the hydrophilic calcium film generated on the pyrite surface further hindered the adsorption of SBX, thereby further inhibiting pyrite in this environment. In other words, the lime high alkaline environment increased the apparent activation energy difference of SBX adsorption between chalcopyrite and pyrite compared to the NaOH system, facilitating the flotation separation of chalcopyrite and pyrite. The results can help with the theoretical research of flotation separation of other minerals, and provide guidance for developing low alkaline and lime-free pyrite depressants.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 3; 901-910
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Response surface methodology (RSM) for optimization of chalcopyrite concentrate leaching with silver-coated pyrite
Autorzy:
Salehi, S.
Noaparast, M.
Shafaei, S. Z.
Powiązania:
https://bibliotekanauki.pl/articles/110894.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
chalcopyrite
copper extraction
silver-coated pyrite
optimization
response surface methodology
Opis:
This study aims to leach copper from chalcopyrite and optimizing the leaching process, using the response surface methodology (RSM). The RSM, a D-optimal design with four factors in three levels was employed to evaluate the effect of particle size, temperature, silver-coated pyrite to chalcopyrite ratio and redox potential parameters on the copper extraction efficiency. A quadratic model was then proposed by the RSM to correlate leaching variables. The tests results indicated that the model was significant with the experimental data at a correlation coefficient (R2) of 0.96. The most important parameters of copper extraction efficiency were particle size and silver-coated pyrite-to-chalcopyrite ratio, and also the squared term of particle size (A2), temperature (B2) and redox potential (D2). In addition, the interaction between redox potential and silver-coated pyrite-to-chalcopyrite ratio (CD) was significant. It was shown that the finer the particle size the faster the leaching rate of copper. It was also indicated that by increasing silver-coated pyrite to chalcopyrite ratio of 6:1 copper recovery increased. The maximum recovery of copper (71%) was obtained for the particle size of -38 μm, 70 °C, 420 mV of redox potential, silver-coated pyrite-to-chalcopyrite ratio of 6 and leaching time of 8 hours.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 2; 1023-1035
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improvement of chalcopyrite atmospheric leaching using controlled slurry potential and additive treatments
Autorzy:
Jafari, M.
Karimi, G.
Ahmadi, R.
Powiązania:
https://bibliotekanauki.pl/articles/110092.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
chalcopyrite
improved leaching
controlled oxidation-reduction potential
additive treatment
pyrite
sodium chloride
silica
Opis:
In this study, the synergistic effects of the oxidation-reduction potential (ORP) of leaching slurry and additives (pyrite, sodium chloride and silica) on chalcopyrite atmospheric leaching were investigated. According to the best results of leaching experiments, in the optimum ORP range of 410-430 mV, galvanic (pyrite mass ratio of 4:1), chemical (1.5 mol/dm3 sodium chloride concentration), galvanochemical (pyrite mass ratio of 4:1 and 1.5 mol/dm3 sodium chloride concentration) and mechanical (30 g/dm3 silica concentration) treatments provided 29.8, 46.4, 48.6 and 6.7% increase in the copper recovery, respectively. In galvanic treatments, effective surface corrosion of chalcopyrite was the reason for enhanced chalcopyrite dissolution. In chemical and galvanochemical treatments, considerable surface porosity of chalcopyrite was responsible for accelerated leaching. Also, in mechanical treatments, removing the remained passive layer from the chalcopyrite surface improved leaching. SEM results showed extensive porosity in the chalcopyrite surface in the presence of pyrite and sodium chloride and even more porosity in the presence of their combination. SEM results also showed obviously clean surface of chalcopyrite in the presence of silica. The comparison of ORP-assisted and non-ORP-assisted experiments showed that there were 8, 5.2, 3.9 and 0.5% more copper recoveries in galvanic, chemical, galvanochemical and mechanical treatments with ORP assistance, respectively. The reason was the fewer chalcopyrite surface passivation, which caused the additives to perform better.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 1228-1240
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bacterial Leaching of Polymetallic Ores from Zlatý Chlum Locality
Bakteryjne ługowanie rud polimetalicznych z miejscowości Zlatý Chlum
Autorzy:
Kovarikova, Hana
Janakova, Iva
Cablik, Vladimir
Vrlikova, Vera
Powiązania:
https://bibliotekanauki.pl/articles/318763.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
ługowanie bakteryjne
rudy polimetaliczne
piryt
chalkopiryt
Acidithiobacillus ferrooksydans
bioreaktor
bacterial leaching
polymetallic ores
pyrite
chalcopyrite
Acidithiobacillus ferrooxidans
bioreactor
Opis:
As for geology, Zlatý Chlum is a highly varied locality with frequent metaquarzit, amphibolite, quartz as well as deposits of sulphide ores. This work deals with the use of Acidithiobacillus ferrooxidans to bioleach polymetallic ores (Cu, al, Zn, and Fe) from this locality. Leaching lasted for 5 weeks in a bioreactor that ensured optimal conditions for bioleaching. The results imply that the experiments were successful, leaching 54% of Fe, 28% of Cu and 47% of Al.
Geologicznie Zlatý Chlum jest bardzo zróżnicowanym złożem z częstymi meta-kwarcytami, amfibolitami, kwarcem oraz poli-metalicznymi rudami siarczkowymi. Artykuł dotyczy zastosowania bakterii Acidithiobacillus ferrooxidans do ługowania bakteryjnego rud polimetalicznych (Cu, Al, Zn i Fe) z tej miejscowości. Ługowanie trwało 5 tygodni w bioreaktorze, który zapewniał optymalne warunki do bioługowania. Wyniki pokazują, że eksperymenty zakończyły się powodzeniem, uzyskano stopień wyługowania 54% Fe, 28% Cu i 47% Al.
Źródło:
Inżynieria Mineralna; 2019, 21, 1; 145-148
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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