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1.
X-ray diffraction has been used to study the changes in mineralogy that occur during ammonia leaching of sulfide minerals
and complex bulk sulfide concentrates. Leaching results in high extraction rates (>90 pct) of copper from chalcopyrite, zinc
from sphalerite, and lead from galena. However, under experimental leaching conditions (temperature, 115 °C to 135 °C; par-tial
pressure of oxygen, 1.5 kg/cm 2; pH ∼ 10.0), the pyrite grains are practically inert. Ap-parently, the amount of pyrite in leach residue is constant in absolute
terms. However, its relative percentage changes because the amount of copper and zinc minerals is reduced in the leach residue
during progressive leaching. The products formed during the leaching reaction, such as goethite and lead sulfate, tend to
increase the weight of the leach residue, and thus the relative weight of pyrite remains nearly unchanged. The ratios of selected
line pair intensities of pyrite lines and characteristic (selected) lines of chalcopyrite, sphalerite, and galena are used
to establish the oxidative ammonia leaching kinetics of Cu-Zn-Pb bulk concentrates. That is, the variation in the line pair
intensity ratios, with time, correlates with the changes in the el-emental concentrations in the leach liquor. 相似文献
2.
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 CuCl 2. Also, the morphology of the leached chalcopyrite surface was studied by using a single chalcopyrite crystal. The leaching
with CuCl 2 produced a porous elemental sulfur layer on the chalcopyrite surface, showing a similar morphology to that produced during
leaching with FeCl 3. 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(CuCl 2) 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(CuCl 2), 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
3.
AbstractGalvanic interactions occurring when two sulphide minerals are in contact with each other have been investigated by electrochemical techniques for pairs of the following: pyrite, chalcopyrite, galena and sphalerite. Combination potentials of pyrite electrodes in galvanic contact with a second sulphide were significantly lower than the rest potential of pyrite alone. This suggested electron transfer to pyrite which makes it more reducing. Similar results were obtained with the chalcopyrite galena couple, chalcopyrite becomes more reducing by galvanic interaction with galena.Galvanic interactions are weakened in nitrogenated water due to the lower activity of dissolved oxygen. This is shown by: (a) much smaller drop in potential when pyrite is in galvanic contact with another sulphide in nitrogenated water; (b) Zn 2+ ions released into solution: dissolution of Zn 2+ ions in sphalerite pyrite mixtures is decreased in nitrogenated water; and (c) xanthate uptake at pyrite-sphalerite mixtures is increased by appropriate use of nitrogen.In aerated water the flotation behaviour of a mineral in a mineral mixture differs significantly from that of the single mineral. The use of nitrogen promotes pyrite flotation from the mixture.A model of galvanic coupling and the role of N 2 are discussed. 相似文献
4.
Abstract A multimetallic sulphide concentrate containing sphalerite, galena, chalcopyrite and silver in the matrix of pyrite was decomposed at elevated temperature and oxygen pressures in dilute sulphuric acid solutions for sufficient residence time to yield 95% of the zinc in the pregnant solution while most of the lead and silver remained in the residue together with most of the pyrite. The selective leaching process appeared to follow the diffusion controlled mechanism. The effects of concentration of the leachant, temperature and time of leaching, particle size, oxygen pressure and agitation on the leaching process were investigated. Results indicate the prospect of extracting not only all the metals but also appreciable amounts of elemental sulphur under optimized experimental conditions. 相似文献
5.
The nonoxidative leaching of sphalerite in aqueous acidic solutions was studied from a kinetic point of view. Also the selective
nonoxidation leaching in a hydrochloric acid solution containing a large amount of sodium chloride was examined for a Pb-Zn
sulfide bulk concentrate. The dissolution rates of sphalerites from five different mines appeared to be controlled by a chemical
reaction on the surface of sphalerite. The dissolution rate of sphalerite is of the first order with respect to the hydrogen
ion activity of the solutions. It is also considerably affected by the iron content of the sphalerite sample; a linear relationship
was observed between iron content of the sphalerite and its dissolution rate. The addition of sodium chloride to the hydrochloric
acid solutions greatly enhanced dissolution rates. Compared to the dissolution rates of galena, which were reported in a previous
paper, the dissolution rates of sphalerite were found to be far slower. The difference in the dissolution rates between these
two minerals becomes greater with the addition of sodium chloride to the hydrchloric acid solutions. Based on these findings,
the selective leaching of Pb-Zn bulk concentrate in a hydrochloric acid solution containing a large amount of sodium chloride
was examined. The experimental results clearly showed that the galena was selectively leached, leaving a residue of sphalerite.
NORIO MISAKI formerly Graduate student, Kyoto University 相似文献
6.
采用0.05%SnCl_2—20%HCl作方沿矿的选择溶剂,浸渣以浮选法选出黄铜精矿及黄铁矿的混合精矿产品,与脉石分离。然后进一步浮选混合精矿,分别选出黄铜矿、黄铁矿,并通过矿物量及其含金品位,计算出各种矿物中含金量。 相似文献
7.
The dissolution of galena (PbS) in ferric chloride-hydrochloric acid media has been investigated over the temperature range
28 to 95 °C and for alkali chloride concentrations from 0 to 4.0 M. Rapid parabolic kinetics were observed under all conditions,
together with predominantly (>95 pet) elemental sulfur formation. The leaching rate decreased slightly with increasing FeCl 3 concentrations in the range 0.1 to 2.0 M, and was essentially independent of the concentration of the FeCl 2 reaction product. The rate was relatively insensitive to HCl concentrations <3.0 M, but increased systematically with increasing
concentrations of alkali or alkaline earth chlorides. Most significantly, the leaching rate decreased sharply and linearly
with increasing initial concentrations of PbCl 2 in the ferric chloride leaching media containing either 0.0 or 3.0 M NaCl. Although the apparent activation energy was in
the range 40 to 45 kJ/mol (∼10 kcal/mol), this value was reduced to 16 kJ/mol (3.5 kcal/mol) when the influence of the solubility
of lead chloride on the reaction rate was taken into consideration. The experimental results are consistent with rate control
by the outward diffusion of the PbCl 2 reaction product through the solution trapped in pores in the constantly thickening elemental sulfur layer formed on the
surface of the galena. 相似文献
8.
The leaching kinetics of a low grade-calcareous sphalerite concentrate containing 38% ankerite and assaying 32% Zn, 7% Pb and 2.2% Fe was studied in HCl–FeCl 3 solution. An L 16 (five factors in four levels) standard orthogonal array was employed to evaluate the effect of Fe(III) and HCl concentration, reaction temperature, solid-to-liquid ratio and particle size on the reaction rate of sphalerite. Statistical techniques were used to determine that pulp density and Fe(III) concentration were the most significant factors affecting the leaching kinetics and to determine the optimum conditions for dissolution. The kinetic data were analyzed with the shrinking particle and shrinking core models. A new variant of the shrinking core model (SCM) best fitted the kinetic data in which both the interfacial transfer and diffusion across the product layer affect the reaction rate. The orders of reaction with respect to ( CFe3+), ( CHCl), and ( S/ L) were 0.86, 0.21 and − 1.54, respectively. The activation energy for the dissolution was found to be 49.2 kJ/mol and a semi-empirical rate equation was derived to describe the process. Similar kinetic behavior was observed during sphalerite dissolution in acidic ferric sulphate and ferric chloride solutions, but the reaction rate constants obtained by leaching in chloride solutions were about tenfold higher than those in sulphate solutions. 相似文献
9.
The recovery of copper from chalcopyrite by leaching is complex not only due to the slow dissolution kinetics of this mineral
in most aqueous media but also due to the production of solutions that are heavily contaminated with iron. On the contrary,
the leaching of sulfidized chalcopyrite is very attractive because of a faster and more selective dissolution of copper compared
to the leaching of the untreated chalcopyrite. In this work, the results of leaching in H 2SO 4-NaCl-O 2 solutions of sulfidized chalcopyrite concentrate are discussed. Experiments were carried out with chalcopyrite concentrates
previously reacted with elemental sulfur at 375 °C for 60 minutes. The results showed that the concentration of chloride ions
below 0.5 M, temperature, and leaching time are important variables for the extraction of Cu. On the other hand, Fe extraction
was little affected by the same variables, remaining below 6 pct for all the experimental conditions tested. Microscopic observations
of the leached particles showed that the elemental sulfur produced by the reaction does not form a coherent layer surrounding
the particle, but rather concentrates in certain locations as large clusters. The leaching kinetics can be accurately described
by a nonreactive core-shrinking rim topochemical expression for spherical particles 1 − (1 − 0.45 X) 1/3= kt. The activation energy found was 76 kJ/mol for the range 85 °C to 100 °C. 相似文献
10.
The bioleaching of different mineral sulfide concentrates with thermophilic bacteria (genus Sulfolobus
@#@) was studied. Since the use of this type of bacteria in leaching systems involves stirring and the control of temperature,
the influence of the type of stirring and the pulp density on dissolution rates was studied in order to ascertain the optimum
conditions for metal recovery. At low pulp densities, the dissolution kinetic was favored by pneumatic stirring, but for higher
pulp densities, orbital stirring produced the best results. A comparative study of three differential concentrates, one mixed
concentrate, and one global concentrate was made. Copper and iron extraction is directly influenced by bacterial activity,
while zinc dissolution is basically due to an indirect mechanism that is activated in the presence of copper ions. Galvanic
interactions between the different sulfides favors the selective bioleaching of some phases (sphalerite and chalcopyrite)
and leads to high metal recovery rates. However, the formation of galvanic couples depends on the type of concentrate. 相似文献
11.
AbstractSintered disks of synthetic chalcopyrite were prepared with known amounts of various sulphide impurities. The disks were leached in acidified ferric sulphate solutions to determine the effect of the second phase on the rate of chalcopyrite dissolution. Experiments using inert impurities showed that the observed variations in the leaching rates were caused by the presence of the impurity and not by other effects. Chalcopyrite-cubanite mixtures behave almost additively; chalcopyrite-bornite mixtures dissolve slightly more rapidly than would be expected from their additive rates. The presence of pyrite, molybdenite or stibnite (which reacts to form pyrite) accelerates the chalcopyrite dissolution rate; the presence of galena retards its dissolution. High-iron sphalerite slightly retards the chalcopyrite dissolution but low-iron sphalerites behave erratically. These results are consistent with a galvanic corrosion mechanism except for the observed effects of molybdenite. Résumé Des pastilles frittées de chalcopyrite synthétique contenant des quantites connues de diverses impuretes sulfurées ont été préparées. Les pastilles ont été lixiviées dans des solutions acidifiées de sulfate ferrique afin de déterminer l'effet de la deuxième phase sur Ie taux de dissolution de la chalcopyrite. En utilisant des impuretés inertes, les expériences ont montré que les variations observées dans les taux de lixiviation sont causées par la présence de l'impureté et non par la présence de d'autres effets. Les mélanges de chalcopyrite-cubane se comportent de façon additive; ceux de chalcopyrite-bornite se dissolvent un peu plus rapidement que ce dont on aurait pu s'attendre de la sommation de leurs taux. La présence de pyrite, de molybdénite ou de stibine (laquelle réagit pour former la pyrite) accélère le taux de dissolution de la chalcopyrite; la presence de galène retarde sa dissolution. La sphalérite à haute teneur en fer retarde legerement la dissolution de la chalcopyrite; cette dissolution présente un comportement erratique pour les sphalérites à faible teneur en fer. Les résultats sont en accord avec le mécanisme de corrosion galvanique sauf pour les effets observés de la molybdénite. 相似文献
12.
The leaching of chalcopyrite from several Australian chalcopyrite concentrates by the reaction CuFeS 2 + 4 Fe(III) + Cu(II) + 5 Fe(II) + 2 S 0 obeyed parabolic kinetics in acidified nitrate solution between 25 and 40°C. The chalcopyrite reactivity was dependent on the mineral composition of the concentrate: the presence of pyrite accelerated the reaction markedly, but sphalerite and bismuthinite slowed it slightly. Galvanic interaction between minerals cannot account for this change: instead, the associated minerals must influence the rate determining diffusion of the lattice elements within the chalcopyrite crystal. 相似文献
13.
常压条件下,黄铜矿浸出速率缓慢,难以达到理想的浸出效果。溶液中,黄铁矿与黄铜矿共同存在时,发生"原电池效应"可以促进黄铜矿溶解。探究了在H_2SO_4溶液、H_2SO_4-Fe_2(SO_4)_3溶液和H_2SO_4-H_2O_2溶液中,黄铁矿对黄铜矿浸出的影响。结果表明,黄铁矿可有效促进黄铜矿溶解,但浸出并不完全。在浸出过程中黄铜矿表面形成钝化层,影响物质转移与电子传递效果。钝化层的主要成分为缺金属硫化物和少量单质硫。 相似文献
14.
The kinetics of dissolution of galena (PbS) in CuCl 2-HCl-NaCl media have been investigated using the rotating disk technique. Rapid nonlinear kinetics are observed over the temperature
range 45 °C to 90 °C and for NaCl concentrations from 0 to 4.0 M. The leaching rate is in-dependent of CuCl 2 concentrations >0.1 M but increases with increasing concentrations of either HC1 or NaCl. The leaching rate decreases with
the accumulation of either the PbCl 2 or CuCl reaction product in the leaching medium but is insensitive to the disk rotation speed. The apparent activation energy
for the rate controlling process is 33 kJ/mol, and this value falls to about 15 kJ/mol when interpreted as a dissolution rate
for PbCl 2, whose solubility increases with temperature. The above observations are shown to be consistent with rate control by the
outward diffusion of the PbCl 2 and CuCl reaction products through the solution trapped in the pores of the constantly thickening elemental sulfur layer
which forms on the surface of the galena.
CANMET, Energy, Mines, and Resources Canada, 555 Booth Street, Ottawa, ON, K1A 0G1, Canada. 相似文献
15.
In this study, chalcopyrite concentrate produced in Sarcheshmeh copper plant was subjected to oxidative leaching investigation by cupric ion to determine the effect of several parameters on the copper and iron dissolution, including temperature of leaching, time of holding and cupric concentration as oxidant agent in a range of 38–97 °C, 1.5–8.5 h and 0.2–0.8 M, respectively. The leaching media was chloride providing with 3 M HCl 37% and CuCl2. The experiments were designed by central composite design method. The dissolution of copper and iron was examined. The maximum dissolution of copper 62.64%, was obtained at 85 °C, 7 h and oxidant concentration of 0.7 M. The kinetics model of chalcopyrite leaching and an optimized condition with maximum dissolution of copper and minimum dissolution of iron was obtained by Minitab®18 software. Additionally, the thermodynamics of leaching was investigated by Pourbaix diagrams of copper and iron composition, using HSC Chemistry6 software. It was found that the oxidative leaching process is controlled by diffusion through passivation layer with an activation energy of 19.57 kJ/mol. 相似文献
16.
A leaching investigation of galena with ferric chloride has been carried out as a function of concentration of ferric chloride
and sodium chloride, temperature, and particle size. Three size fractions were considered in this investigation, namely, 48
× 65, 35 × 48, and 28 × 35 mesh. The concentration ranges of ferric chloride and sodium chloride used in this investigation
were 0 to 0.25 M and 0 to 3 M, respectively. The reaction rate mechanism has been discussed in terms of a shrinking core model
developed for cubic systems. Mass transport of ferric chlorocomplex through the product sulfur layer appears to be responsible
for establishing the overall leaching rate under most of the conditions used in this investigation. The apparent activation
energy for the leaching of 28 × 35 mesh galena with 0.1 M FeCl 3, 1 M HC1, and 3.0 M NaCl was found to be about 8.05 kcal/mol (33.7 kJ/mol), which was partially contributed by diffusion
and partially by the heat of reaction of the formation of ferric chlorocomplexes. Rate of dissolution at both 50° and 90 °C
is greatly affected by ferric chloride concentration up to 0.2 M and is essentially constant with ferric chloride concentration
above this value. 相似文献
17.
The thermal treatment of natural sulfidic minerals such as sphalerite, galena, chalcopyrite, and pyrite in an N 2 or H 2 atmosphere was studied to examine the nature of reactions taking place. Such treatments have the potential of avoiding sulfur
dioxide production which is associated with the roasting of complex sulfide ores (CSOs). The thermal treatment of CSO concentrates
at temperatures less than 1000 °C in a nitrogen atmosphere leads to the decomposition of the pyritic matrix to pyrrhotite
and the volatilization of sulfur, galena, and some of the CSOs’ trace elements. Treating the CSO in a reducing atmosphere
converted sphalerite to zinc and produced a solid containing Cu o, Fe o, and silicoaluminates. Selective dissolution of copper may be achieved by a hydrometallurgical process. Hydrogen sulfide
could be reacted with pyrrhotite to form pyrite and hydrogen. A flow sheet is proposed.
M.-CH. Meyer-Joly formerly Researcher with Mineral Processing and Environmental Engineering, Institut National Polytechnique
de Lorraine
K. MALAU formerly Researcher with Mineral Processing and Environmental Engineering, Institut National Polytechnique de Lorraine 相似文献
18.
Chalcopyrite oxidation by CuCl 2 in NaCl solutions has been studied as a function of leaching time, temperature, grain size, Cu( II)/Cu( I) ratio, and Cl − activity. The experiments have been performed under conditions where the solution potential remains almost constant in each
test. Leaching rates are high above 85 °C, and high copper recovery can be obtained provided that high Cu( II)/Cu( I) ratios are maintained. Elemental sulfur is obtained with no sulfate formation. It was observed that the combined influence
of Cu( II)/Cu( I) ratio and Cl − activity on the leaching rate is related to the solution potential, explaining the action of the concentration of chloride
ion in chalcopyrite leaching.
M.BONAN, formerly with Ecole des Mines, is now with Israel Mining Industries. 相似文献
19.
A complex Cu/Zn/Pb ore from Cayeli, Turkey, was reacted with cupric chloride solutions under different conditions. Energies of activation were calculated for dissolution of copper (37 kJ mol ?1), iron (33 kJ mol ?1, zinc (26 kJ mol ?1) and lead (7.5 kJ mol ?1, values which indicate diffusion control of the reaction, probably through the sulphur layer formed round each particle. Particle size/leaching relationships corroborated microscopic assessments and indicated that chalcopyrite dissolved at a very low rate. Calculation of Fe:Cu ratios of metal leached showed considerable dissolution of pyrite from finely-ground ( ) ore. Examination of residues using SEM X-ray fluorescence line scan techniques revealed little attack of large pyrite crystals, suggesting that fine pyrite particles in complex relationship with the sphalerite and chalcopyrite were dissolving. 相似文献
20.
The literature on the ferric ion leaching of chalcopyrite has been surveyed to identify those leaching parameters which are
well established and to outline areas requiring additional study. New experimental work was undertaken to resolve points still
in dispute. It seems well established that chalcopyrite dissolution in either ferric chloride or ferric sulfate media is independent
of stirring speeds above those necessary to suspend the particles and of acid concentrations above those required to keep
iron in solution. The rates are faster in the chloride system and the activation energy in that medium is about 42 kJ/mol;
the activation energy is about 75 kJ/mol in ferric sulfate solutions. It has been confirmed that the rate is directly proportional
to the surface area of the chalcopyrite in both chloride and sulfate media. Sulfate concentrations, especially FeSO 4 concentrations, decrease the leaching rate substantially; furthermore, CuSO 4 does not promote leaching in the sulfate system. Chloride additions to sulfate solutions accelerate slightly the dissolution
rates at elevated temperatures. It has been confirmed that leaching in the ferric sulfate system is nearly independent of
the concentration of Fe 3+, ka[Fe 3+] 0.12. In ferric chloride solutions, the ferric concentration dependence is greater and appears to be independent of temperature
over the interval 45 to 100 °C. 相似文献
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