共查询到20条相似文献,搜索用时 15 毫秒
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R. Padilla E. Olivares M. C. Ruiz H. Y. Sohn 《Metallurgical and Materials Transactions B》2003,34(1):61-68
The sulfidation of chalcopyrite with gaseous sulfur in the temperature range of 325 °C to 400 °C occurs with the formation
of covellite and pyrite as the final products. The rate of sulfidation depends strongly on the temperature, with nearly complete
conversion in less than 30 minutes at 400 °C. Microscopic analysis of partially and completely reacted particles showed that
the sulfidation proceeded topochemically, with a shrinking core of unreacted chalcopyrite surrounded by successive layers
of FeS2 and CuS. The experimental data exhibited an induction period at the beginning of the reaction. An electrochemical mechanism
is proposed for the sulfidation reaction, which involves simultaneous diffusion of Cu− and electrons through the product layers. The rate data showed that the fraction reacted is well represented by a shrinking-core
model controlled by the reaction occurring at the chalcopyrite-pyrite interface, resulting in the conversion-vs-time relationship 1−(1−X)1/3=k(t−t
ind). An activation energy of 98.4 kJ/mol was determined for the temperature range of 325 °C to 400 °C. 相似文献
3.
Chalcopyrite reacts readily with SO3 at about 100°C to form water-soluble sulfates; the reaction is approximately: 3CuFeS2+26SO3→3CuSO4+FeSO4+Fe2(SO4)3+25SO2 The presence of about 4 pct O2 in the gas phase greatly accelerates the reaction presumably due to the complete transformation of ferrous into ferric sulfate in an extremely porous form: 2CuFeS2+17SO3+1/2O2→2CuSO4+Fe2(SO4)3+16SO2 A stoichiometric mixture of SO2+1/2O2 behaves towards chalcopyrite in nearly the same way as SO3 although only in the temperature range 350° to 700°C. 相似文献
4.
The results of the second part of the study into the sulfidizing of the main sulfide minerals of copper-nickel ores, namely, pentlandite, chalcopyrite, and pyrrhotine, by elementary sulfur are presented. The phase compositions of the sulfidizing products are examined by scanning electron microscopy and electronprobe microanalysis, and a mechanism is proposed for the sulfidizing of chalcopyrite under near-equilibrium conditions. 相似文献
5.
The first part of the study into the sulfidizing of the major minerals of copper-nickel ores, namely, pentlandite, chalcopyrite,
and pyrrhotine, by elementary sulfur is presented. The phase composition of the sulfidizing products is determined by scanning
electron microscopy and electron-probe microanalysis and is then used to propose a mechanism for the sulfidizing of pentlandite
under near-equilibrium conditions. 相似文献
6.
The sulfidizing of the main sulfide minerals of copper-nickel ores, namely, pentlandite, chalcopyrite, and pyrrhotine, by
elementary sulfur is studied. The phase compositions of the sulfidizing products are examined by scanning electron microscopy
and electron-probe microanalysis, and a mechanism is proposed for the sulfidizing of nickel-containing pyrrhotine under near-equilibrium
conditions. 相似文献
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DENG Gengfeng JIANG Kun CAO Xia LIAO Chunfa 《中国稀土学报(英文版)》2009,27(5):744-748
With coal gas as a reducing agent, the catalytic reduction of SO2 to sulfur in the flue gas produced in metallurgical processes was studied over catalysts of rare earth-Fe/Al2O3 (REFe/Al2O3). The catalytic activity of the REFe/Al2O3 catalyst on the reduction of SO2 to sul-fur was investigated based on kinds and the contents of rare earths and different preparation method of the catalyst. Additionally, the mecha-nism of this catalytic reduction reaction was also explored. Results showed that different rare earth imposed different effect on the activity of the Fe/Al2O3 catalyst. Especially, the addition of Sm and Dy greatly improved the catalytic activity of Fe/Al2O3. The yield of sulfur over SmFe/Al2O3was increased to 86.62% at 360 ℃, which was 40.5% higher than that over Fe/Al2O3at the same temperature; and the sulfur yield over DyFe/Al2O3was increased to 91.62% at 400 ℃, 26.4% higher than that over Fe/Al2O3. The catalytic activity of REFe/Al2O3 was somehow dependent on the content of rare earth. For SmFe/Al2O3, the content of Sm was optimized to be about 1.0 wt.%. The rare earth catalyst prepared with different methods also showed varied activity. The sulfur yield over rare-earth transition metal catalysts follows the order: Sm and iron solution mixing impregnationSm first, then iron solution impregnationiron first, then Sm solution impregnation. The reaction mechanism of SO2 reduction to sulfur with coal gas was proposed to be an intermediate mechanism. 相似文献
9.
Yasuhiro Konishi Satoru Asai Yuichi Sawada 《Metallurgical and Materials Transactions B》1997,28(1):25-32
This article describes the bioleaching of manganese nodules by thermophilic and mesophilic sulfuroxidizing bacteria, in which
oxidized sulfur compounds are biologically produced from elemental sulfur added to liquid medium and are simultaneously used
to leach nodules. The thermophile Acidianus brierleyi solubilized the manganese nodules faster at 65 °C than did the mesophiles Thiobacillus ferrooxidans and Thiobacillus thiooxidans at 30 °C. Leaching experiments with A. brierleyi growing on elemental sulfur were used to optimize various process parameters, such as medium pH, initial sulfur-liquid loading
ratio, and initial cell concentration. The observed dependencies of the leaching rates at a pH optimum on the initial amounts
of elemental sulfur and A. brierleyi cells were qualitatively consistent with model simulations for microbial sulfur oxidation. Under the conditions determined as optimum,
the leaching of nodule particles (−330+500 mesh) by A. brierleyi yielded 100 pct extraction of both copper and zinc within 4 days and high extractions of nickel (85 pct), cobalt (70 pct),
and manganese (55 pct) for 10 days. However, the iron leaching was practically negligible. 相似文献
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The leaching of chalcopyrite with ferric sulfate 总被引:1,自引:0,他引:1
Tetsuji Hirato Hiroshi Majima Yasuhiro Awakura 《Metallurgical and Materials Transactions B》1987,18(3):489-496
The leaching kinetics of natural chalcopyrite crystals with ferric sulfate was studied. The morphology of the leached chalcopyrite
and the electrochemical properties of chalcopyrite electrodes also were investigated. The leaching of chalcopyrite showed
parabolic-like kinetics initially and then showed linear kinetics. In the initial stage, a dense sulfur layer formed on the
chalcopyrite surface. The growth of the layer caused it to peel from the surface, leaving a rough surface. In the linear stage,
no thick sulfur layer was observed. In this investigation, chalcopyrite leaching in the linear stage was principally studied.
The apparent activation energy for chalcopyrite leaching was found to range from 76.8 to 87.7 kJ mol−1, and this suggests that the leaching of chalcopyrite is chemically controlled. The leaching rate of chalcopyrite increases
with an increase in Fe(SO4)1.5 concentration up to 0.1 mol dm−3, but a further increase of the Fe(SO4)1.5 concentration has little effect on the leaching rate. The dependency of the mixed potential upon Fe(SO4)1.5 concentration was found to be 79 mV decade−1 from 0.01 mol dm−3 to 1 mol dm−3 Fe(SO4)1.5. Both the leaching rate and the mixed potential decreased with an increased FeSO4 concentration. The anodic current of Fe(II) oxidation on the chalcopyrite surface in a sulfate medium was larger than that
in a chloride medium. 相似文献
12.
The leaching of chalcopyrite with ferric chloride 总被引:1,自引:0,他引:1
Tetsuji Hirato Makoto Kinoshita Yasuhiro Awakura Hiroshi Majima 《Metallurgical and Materials Transactions B》1986,17(1):19-28
A comparative study of electrochemical leaching and chemical leaching of chalcopyrite was done to elucidate the leaching mechanism
of chalcopyrite with FeCl3. The leaching rate of chalcopyrite exhibits a half order dependency on the FeCl3 concentration, whereas it is independent of the FeCl2 concentration. The mixed potential of chalcopyrite exhibits a 72 mV · decade−1 dependency upon FeCl3 concentration; no influence on the mixed potential was observed by the addition of FeCl2. In FeCl3 solutions acidified with HC1, the predominant chemical species of Fe(III) was found to be FeCl
2
u+
from equilibrium calculations. The concentration of this species is approximately proportional to the amount of FeCl3 added to the solutions. Based on these observations, an electrochemical mechanism is proposed which involves the oxidation
of chalcopyrite and the reduction of FeCl
2
+
, the predominant species of Fe(III). By converting the leaching rate to electric current density,i, 140 mV · decade−1 dependency of mixed potential,E, against logi is obtained. This dependency of the chemical leaching of chalcopyrite with FeCl3 as well as its activation energy agree with those for electrochemical leaching. These findings strongly support the electrochemical
mechanism of FeCl3 leaching of chalcopyrite.
Formerly Graduate Student, Kyoto University 相似文献
13.
Tetsuji Hirato Hiroshi Majima Yasuhiro Awakura 《Metallurgical and Materials Transactions B》1987,18(1):31-39
A comparative study of electrochemical leaching and chemical leaching of chalcopyrite was performed mainly at 343 K to elucidate
the leaching mechanism of chalcopyrite with CuCl2. Also, the morphology of the leached chalcopyrite surface was studied by using a single chalcopyrite crystal. The leaching
with CuCl2 produced a porous elemental sulfur layer on the chalcopyrite surface, showing a similar morphology to that produced during
leaching with FeCl3. The leaching kinetics were found to be linear over an extended period, followed by an acceleration stage, as a result of
an increase in the reaction surface area. The leaching rate of chalcopyrite was proportional to C(CuCl2)0.5, whereas it was inversely proportional to C(CuCl)0.5. The mixed potential of chalcopyrite exhibited a 66 mV decade−1 dependency upon C(CuCl2), and—69 mV decade−1 upon C(CuCl). Based on these observations together with other findings, an electrochemical mechanism involving the oxidation
of chalcopyrite and CuCl
−
2
and the reduction of CuCl+ was proposed. The Tafel plot between the mixed potential and the current density obtained by converting the rate of chemical
leaching gave a straight line whose slope was in good agreement with that of the electrochemical leaching. These findings
strongly support the electrochemical mechanism of chalcopyrite leaching with cupric chloride. 相似文献
14.
《Canadian Metallurgical Quarterly》2013,52(4):227-233
AbstractPure iron and an Fe–41 wt% Ni alloy are reacted at temperatures in the range 793–1073 K with H2–H2S–N2 atmospheres corresponding to equilibrium P S2 levels from 6.5 × 10?5 to 0.65 Pat The kinetics of iron sulfidation are intermediate in form to linear and parabolic rate laws. The instantaneous parabolic rate constant is found to increase with extent of reaction until a constant value is reached. For fixed equilibrium sulfur pressures, the instantaneous rate increases with hydrogen sulfide partial pressure; for fixed hydrogen sulfide partial pressure, the instantaneous rate decreases as the equilibrium sulfur pressure is increased. It is demonstrated that hydrogen sulfide is the reactant species. A Langmuir-Hinshelwood kinetic model based on the slow dissociation of adsorbed hydrogen sulfide accounts satisfactorily for the unusual gas-phase compositional effects, and also for the rate at which the reacting system approaches steady state. Similar effects are found for the Fe–41%Ni alloy, where nickel sulfide whisker formation results from localized catalysis of the hydrogen sulfide dissociation reaction. 相似文献
15.
N. Kanari I. Gaballah E. Allain N. Menad 《Metallurgical and Materials Transactions B》1999,30(4):567-576
The chlorination behaviors of two chalcopyrite concentrates and their pure constituents in Cl2+N2 were investigated by thermogravimetric analysis (TGA) in nonisothermal conditions up to 1000 °C. The effect of temperature
on the reaction of chlorine with both concentrates was studied between 170 °C and 300 °C under isothermal conditions. The
effects of gas flow rate, chlorine content of the gas mixture, and reaction time on the reaction rate were also investigated.
The reaction products were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results showed that
the kinetics of chlorination of chalcopyrite concentrates generating chlorides of Cu, Pb, Zn, Fe, and S was rapid at about
300 °C. The iron and sulfur chlorides were volatilized, leading to a residue containing valuable metal chlorides. 相似文献
16.
Galvanic conversion of chalcopyrite 总被引:6,自引:0,他引:6
Galvanic interaction between particulate chalcopyrite (CuFeS2) and copper results in the rapid conversion of chalcopyrite to chalcocite. The effects of temperature, surface area, concentration
of sulfuric acid and agitation were systematically evaluated. The kinetics were found to be controlled by a steady-state current
flow controlled by the effective anodic and cathodic surface areas involved in the galvanic couple. The experimental activation
energy was 11.5 and stoichiometric data and reaction products have been characterized. The overall kinetic system has been
evaluated based upon an electrochemical model. 相似文献
17.
《Hydrometallurgy》2008,90(3-4):323-331
Two new process flowsheets have been developed which combine chloride leaching of copper from chalcopyrite with solvent extraction, to selectively transfer copper to a conventional sulfate electrowinning circuit. Chloride leaching with copper(II) as oxidant offers significant advantages for copper including increased solubility and increased rates of leaching. Both process flowsheets were similarly designed with a two stage counter-current leach but differ with respect to iron deportment. The goethite model flowsheet includes sparging of air or oxygen to the second leach stage to aid precipitation of iron as goethite (FeOOH). The hematite model flowsheet precipitates iron as hematite (Fe2O3) downstream from the leach in a dedicated autoclave. A mass balance has been completed for both process flowsheets and this determined the concentrations of copper and iron species in feed liquor returning to the leach following copper solvent extraction.The optimum leach extraction conditions were determined by varying grind size, temperature and residence time for both leach model scenarios. Leach tests were conducted using a chalcopyrite concentrate from Antamina in northern Peru, which contains a low to moderate amount of gangue material. The hematite model was also examined using a Rosario concentrate from Chile which contained chalcocite in addition to chalcopyrite and significant pyrite. Leach tests based on the hematite model were successful in achieving copper extractions > 95% in 4–6 h at 95 °C after fine grinding the concentrate (P90 = 41 μm). However, copper extraction exceeded 99% from the finely ground Rosario concentrate (P90 = 37 μm). In the goethite model leach tests, 89% copper extraction was achieved under optimum conditions in the atmospheric conditions tested. 相似文献
18.
Wang Qingxiang 《钢铁研究学报(英文版)》1998,(2)
Becauseoftheincreasingutilizationofmetalsathightemperatureinindustrialatmospherescon-tainingsulfuranditscompounds,thepractica... 相似文献
19.
George W. McDonald Terrance J. Udovic James A. Dumesic Stanley H. Langer 《Hydrometallurgy》1984,13(2):125-135
The leaching of chalcopyrite in aqueous cupric chloride solutions is treated with a thermodynamic model which incorporates the equilibria associated with the formation of various cupric, cuprous and ferrous chloride complexes. The precipitate from a refluxing slurry of elemental sulfur and aqueous cuprous and ferrous chlorides contained predominantly covellite (CuS) and a small amount of pyrite (FeS2). Mössbauer spectra indicate that there was no chalcopyrite formation. Cupric chloride leaching experiments on both chalcopyrite concentrate and cupric sulfide indicated that the extent of cuprous ion formation in these aqueous cupric chloride solutions is controlled by the thermodynamics of the equilibrium: Conditions which favor the desired complete reduction of cupric ion are discussed. 相似文献
20.
Eung Ha Cho 《Metallurgical and Materials Transactions B》1987,18(2):315-323
Laboratory studies have been conducted on the leaching of chalcopyrite and sphalerite with hypochlorous acid. The effects
of stirring speed, temperature, pH, and hypochlorous acid concentration on the leaching rates have been determined. In addition,
the leaching mechanisms have been resolved by analyzing the concentrations of the reaction products. It has been found that
more than 90 pct extraction of both chalcopyrite and sphalerite can be achieved in one hour using less than 0.3 molar hypochlorous
acid at room temperature. The primary leach products of chalcopyrite and sphalerite were sulfur and sulfate in the mole ratios
of 1 to 1 and 2 to 1, respectively. A mixed kinetic model was applied to explain the leaching rates of chalcopyrite while
a diffusion model was applied to explain the leaching rates of sphalerite. The mixed kinetic model involved steady-state diffusion
of hypochlorous acid through the sulfur layer by a chemical reaction at the reaction interface. Good agreement between these
models and the leaching rates of both minerals was obtained. 相似文献