chalcopyrite leacha chloride

8/8/2019 Chalcopyrite Leacha Chloride

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Acta Metallurgica Slovaca, 10, 2004, Special Issue 2 (174 - 182) 174

LEACHING OF CHALCOPYRITE IN CUPRIC CHLORIDE SOLUTION

Lundstrm M.1, Aromaa J.1, Forsn O.1, Hyvrinen O.2 and Barker M. H.21 Helsinki University of Technology, Laboratory of Corrosion and Material Chemistry,P.O. Box 6200, 02015 HUT, Finland, e-mail: [email protected] Outokumpu Research Oy, Kuparitie 10, P.O. Box 60, 28101 Pori, Finland

LHOVANIE CHALKOPYRITU V ROZTOKU CHLORIDU MENATHO

Lundstrm M.1, Aromaa J.1, Forsn O.1, Hyvrinen O.2, Barker M. H.21

Helsinki University of Technology, Laboratory of Corrosion and Material Chemistry,P.O. Box 6200, 02015 HUT, Finland, e-mail: [email protected] Outokumpu Research Oy, Kuparitie 10, P.O. Box 60, 28101 Pori, Finland

AbstraktOutokumpu HydroCopperTM technolgia bola vyvinut Outokumpu Research. Je to

nov metda vroby medi zaloen na innch lhovacch vlastnostiach roztoku chloridumenatho. Lhovanie sa realizuje pri atmosferickom tlaku, blzko bodu varu vody v reaktores mieanm roztoku, ktor je udriavan na pH 1.5-2.5.

V prci bolo realizovan elektrochemick tdium chovania sa chalkopyritu,najbenejieho minerlu medi, poas jeho rozpania v roztoku koncentrovanho chloridusodnho (250 g/l) s premenlivou koncentrciou menatch inov v rozsahu 0.09-26.6 g/l.

Taktie bol meran vplyv pH (1-3) a teploty (70-90 C).Pre urenie mechanizmu rozpania chalkopyritu boli elektrdy analyzovan

pomocou elektrnovej skenovacej mikroskpie. Pre urenie rchlos kontrolujceho krokulhovania bola pouit metda rotujceho disku. So zvyujcou sa teplotou a koncentrcioumenatch inov pre [Cu2+] > 9 g/l bolo pozorovan proporcionlne zvenie reaknejrchlosti. Niia koncentrcia menatch inov, t.j. [Cu2+] < 9 g/l, nevplvala na rchloslhovania. Vsledky nasveduj tomu, e pri vyom pH sa na povrchu lhovanho

chalkopyritu hromadia oxidy, hydroxidy a chloridy eleza. Pri nich hodnotch pH sachalkopyrit pasivuje a na jeho povrchu bola detekovan vrstva obohaten o sru.

AbstractOutokumpu HydroCopper

TMtechnology was developed by Outokumpu Research. It

is a novel copper production method based on the efficient leaching properties of cupricchloride solutions. The leaching is operated at atmospheric pressure, near the boiling point ofwater in a stirred reactor and the pH is kept between 1.5-2.5.

In the present work, an electrochemical study of the dissolution behaviour ofchalcopyrite, the most common copper mineral, was made in a concentrated sodium chloride

solution (250 g/l) with variable cupric ion concentrations in the range 0.0926.6 g/l. Theeffects of pH (1-3) and temperature (7090 C) were also measured.

In order to investigate the mechanism of the chalcopyrite dissolution, the electrodeswere analysed by scanning electron microscopy. The rotating disk electrode technique wasused to define the rate controlling step in the leaching process. The increase in the reaction

rate was observed to be proportional to the increase in the temperature and to the cupric ionconcentration with [Cu

2+] > 9 g/l. With [Cu

2+] < 9 g/l the cupric ion concentration did not

effect the leaching rate. The results suggested that iron oxides, hydroxides and chlorides


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gathered on the chalcopyrite surface at higher pHs. At lower pHs chalcopyrite passivated anda sulfur rich layer was detected on the surface.

Key words: Chalcopyrite, leaching of chalcopyrite, cupric chloride, sodium chloride,HydroCopperTM

1. IntroductionThere are a great number of research articles on the leaching of sulphide minerals in

chloride media. In highly concentrated chloride solution copper ions readily form cuprouscomplexes, such as [CuCl3]

2-, [Cu2Cl4]2-, [Cu3Cl6]

3- and cupric complexes, such as [CuCl]+,[CuCl2]

0, [CuCl3]-, [CuCl4]

2- [1-3]. The utilization of chloride solutions in chalcopyriteleaching is advantageous due to the aggressive nature of the leaching and to the stability of

cuprous ions due to the formation of the aforementioned chloro-complexes. With pHs > 3,cupric hydroxyl chlorides become important [4]. In general, the leaching of chalcopyrite ismore effective in chloride solutions with cupric ions as the oxidant than in sulfate solutionswith ferric ions as the oxidant. This is possibly due to kinetic rather than thermodynamicconsiderations e.g. the higher rates of electron transfer in chloride solutions than in sulphatesolutions, as the chalcopyrite surface passivates more readily in the presence of sulfate ions.

[5] The formation of passivating reaction product films has been suggested several times insulfate solutions [6, 7]. Munoz et al. [8] concluded that the rate limiting step in the leaching ofchalcopyrite with ferric sulfate was the transport process through the sulfur product layer.Similar behaviour has also been reported in ferric chloride leaching [9].

Recently, Outokumpu has developed a novel leaching process, HydroCopperTM. Inthis process [10,11] as well as in the modified Ecuprex [12] process chalcopyrite is reportedto dissolve according to reaction (1). [13]

CuFeS2(s) + 3Cu2+

(aq) 4Cu+

(aq) + Fe2+

(aq) + 2S0(s) (1)

Wilson et al. [14] suggested similar leaching reactions in cupric chloride solutions,however, via the formation of cuprous chloride complexes (2).

CuFeS2(s) + 3[CuCl]+

(aq) + 11Cl-

(aq) = 4[CuCl3]2-

(aq) + FeCl2(aq) + 2S0

(s) (2)

According to Wilson et al. [14] the ratio of cuprous to cupric ions must be less than1.9 for reaction (2) to be thermodynamically favourable. They also observed that over theconcentration range [Cu2+] = 0.79 - 1.46 M and [Cl-] = 2.82 - 6.21 M at 90 C, neither cupricnor chloride ion concentration influences the rate of chalcopyrite dissolution. In

HydroCopperTM

the leaching of chalcopyrite is done in a cupric chloride solution atatmospheric pressure and at a temperature of 80-100 C. The pH is kept in between 1.5 and2.5. [10,11] The aim of this work is to build a process window of the behaviour ofchalcopyrite in a highly concentrated chloride solution. The effect of temperature, pH and

cupric ion concentration on the dissolution of chalcopyrite is studied.

2. ThermodynamicThe standard free energy of formation for chalcopyrite is 242.70 kJ/mol. The

formation of solvated cupric and cuprous ions is not thermodynamically favourable understandard conditions; the standard free energy of formation, G0, for Cu+ is 50.20 kJ/mol and


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for Cu2+ is 64.96 kJ/mol. However, the formation of chloro-complexes is thermodynamicallyfavourable. [14] When a system is not in a standard state, the equilibrium potential of thereaction can be calculated with the Nernst equation. To draw Fig. 1, the E0 values were

calculated for all equations with HSC 5.11 software by Outokumpu Research. These valueswere imported in to Microsoft Excel and the effect of chloride ion concentration was taken into account by using the Nernst equation.

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

-2 -1.5 -1 -0 .5 0 0.5 1log(cCl-)

Eh

C u2+

C u

CuCl+

CuCl32-

CuCl2-

Fig. 1. E - log c(Cl-) diagram showing the stability of metallic copper, cupric ions and cupric

and cuprous complexes at T = 90 C. [Cu2+] = 1 M (solid line) and [Cu2+] =0.1 M(dashed line).

Fig. 1 shows the effect of cupric ion concentration (0.1 M and 1 M) on the stability ofcopper, cupric ions and cupric and cuprous complexes at 90 C. Increasing the copperconcentration decreases the stability of cupric ions and makes the formation of [CuCl]+ and[CuCl2]

- more likely. Also the effect of temperature on the stabilities was studied. The stablearea of cupric ions decreases as the temperature increases. The [CuCl 2]

- complex is more

stable at 90 C than at 25 C. Otherwise the changes in the stabilities within the temperaturerange 2590 C are small. According to the E-c(Cl

-) diagrams, under HydroCopper

TM

conditions the dominant complex is likely to be [CuCl]+. That suggests that the leaching ofchalcopyrite would more likely occur via the formation of cuprous chloride complexes similarto reaction (2) than according to reaction (1).

3. Materials and proceduresElectrochemical methods such as anodic polarization, potentiostatic measurements

and cyclic voltammetry were used in this study. A rotating disk electrode (RDE) was used todetermine the leaching rate controlling step. Scanning electron microscopy / energy dispersive

(X-ray) spectrocopy (SEM/EDS) was applied to study the composition of reaction productlayers formed on the chalcopyrite.

The concentration of NaCl in the solution was 250 g/l (4.3 M). The cupric ionconcentrations used were 0.09, 0.9, 4.5, 9.0, 17.9 and 26.6 g/l. The temperature was varied

between 70 and 90 C and the pH was adjusted in the range of 1 to 3. The upper pH limit isdefined by the formation of copper oxychlorides.

The working electrodes were made of chalcopyrite from the Pyhsalmi mine in

Finland. The elemental composition of the electrodes was analysed several times with


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SEM/EDS. The composition varied, but the average value was Cu 30.0%, Fe 32.5%, S 36.3%,Si 0.5%, Al 0.4% and Mg 0.3% in percentage by weight. The analysed values were near to thetheoretical composition of chalcopyrite (Cu 34.6 %, Fe 30.4 % and S 34.9 %). The electrodes

were polished between every measurement with rotating and wetted grade 800 waterproofabrasive paper. After polishing the electrodes were rinsed first with de-ionised water, thenethanol and then dried.

A standard three-electrode electrochemical cell was employed for the electrochemicalmeasurements. The vessel was equipped with a thermostated water jacket. In all measurements(except RDE) the cell was stirred with a magnetic stirrer at 500 r.p.m. No purging of gases

was done. The counter electrode was a platinum sheet, the reference electrode was Ag/AgClplaced in a sintered glass tube containing gel of agar powder, potassium chloride and distilledwater. The reference electrode junction was positioned in an external beaker and connected tothe cell via a Luggin capillary. The measurements were carried out using two electrochemicalworkstations: (i) a PAR 273 Potentiostat/Galvanostat controlled by EG&G PARs Model 352Corrosion Analysis Software 1.00 and (ii) Potentiostat/Galvanostat 2000 working together

with a 5050 frequency response analyser (FRA) and 1731 Intelligent/Arbitrary functionsynthesizer (both NF Corporation, Japan) controlled by in-house software.

The dissolution current densities were estimated from anodic polarization curves withthe Tafel method. The rotating disc technique was used to study the mass transport as the

Levich equation (3) predicts the variation in the transport-limited current as a function of theelectrode rotation rate

jlim = 0.62zFD2/3

-1/6

1/2c (3)

where j is the current density (mA/cm2), F is Faradays constant (96,485 C/mol), D is thediffusion coefficient (cm

2/s), is the kinematic viscosity(cm

2/s), is the angular frequency

(1/s (=2f)) and c is the concentration (mol/cm3). In the Levich plot the transport limited

current as a function of the square root of rotation speed should yield a straight line. If the plotgives a linear response, the system can be assumed to be diffusion controlled and the diffusion

coefficient can be calculated.

4. Results4.1. The effect of [Cu2+]

With cupric ion concentration 9 g/l (0.14 M) at pH 2 and 85 C the corrosionpotential was observed to follow the Nernst equation. The increase in the corrosion potentialwas ca. 60 mV/decade of cupric ion concentration (Fig. 2). This is in good agreement with thestudy done by Hirato et al. [15]. They found the effect of CuCl2 concentration (from 0.01 to 1

mol/dm3) on the mixed potential of chalcopyrite to be 66 mV/decade at 70 C in 0.2mol/dm

3

(7.3 g/l) HCl solution. At cupric ion concentrations > 9 g/l the behaviour changed and the

corrosion potential did not follow the Nernst equation.The effect of copper concentration was studied with anodic polarisation

measurements. Increasing the cupric ion concentration, when [Cu2+] > 9 g/l, increased thedissolution rate of the chalcopyrite for the temperature range studied (Fig. 3). When pH 2.5,or the [Cu2+] 9 g/l, the cupric ion concentration did not seem to play an important role in

the dissolution process .


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0.1 1 10

440

460

480

500

520

540

560

580

POTENTIAL(mVvs.

Ag/AgCl)

CUPRIC ION CONCENTRATION (g/l)

70C

75C

80C

85C

90C

Fig. 2. A plot of corrosion potential vs. cupric ion concentration as a function of temperature.

[NaCl] = 250 g/l and pH = 2.

400 500 600 700 800 900 1000

0.0

0.5

1.0

1.5

CURRENTDENSITY(mA/cm2)

POTENTIAL (mV vs. Ag/AgCl)

Cu(II) 26.6 g/l

Cu(II) 17.9 g/l

Cu(II) 9.0 g/l

Cu(II) 4.5 g/l

Cu(II) 0.9 g/l

Cu(II) 0.09 g/l

Fig. 3. Anodic polarisation curves run with cupric ion concentration 0.09, 0.9, 4.5, 9.0, 17.9

and 26.6 g/l. [NaCl] = 250 g/l, T = 90 C, pH = 2 and scan rate = 0.33 mV/s.

The dissolution rates calculated by the Tafel method also changed remarkably whenthe cupric ion concentration was increased from 9 to 17.9 g/l. With cupric concentrationsabove 9 g/l the dissolution increased to over 5 m/h, this increased with increasing cupricconcentration. With cupric concentrations below 9 g/l the dissolution rate was below 2 m/h.The reaction rate controlling mechanism appears to change with cupric ion concentration of 9g/l. This is discussed in more detail in section 4.4.

4.2. The effect of pH on the chalcopyrite dissolutionThe effect of pH on the corrosion potential and the anodic polarisation curves was

remarkable. A low pH, in the pH range 1 to 2.5, was observed to decrease the corrosion


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potential by ca. 20 mV/pH unit. Since protons are not involved in dissolution reactions (1) or(2), a possible explanation is that a reaction product layer forms, which then reacts withprotons.

500 600 700 800 900 1000

0

1

2

3

4

5

6

CURRENTDENSITY(mA/c

m2)


pH 1pH 1.5pH 2pH 2.5

pH 3

Fig. 4. Anodic polarisation curves at pHs 1.0, 1.5, 2.0, 2.5 and 3.0, [NaCl] = 250 g/l, [Cu 2+] =

26.6 g/l, T = 70 C and scan rate = 0.33 mV/s.

Anodic polarization measurements were carried out in the pH range 1 to 3. It wasobserved that the current densities at pH 2.5 and 3 were remarkably greater than those at lowerpHs, Figure 4. The colour of the electrode surface after the experiments depended on the pH:at 1 and 1.5 the surface was golden, at 2 and 2.5 black, gray and brown and at pH 3 rustcoloured.

Potentiostatic measurements (not shown) indicated that the reaction mechanismchanged between pH 2 and pH 2.25. At pH < 2.25 the current density decreases very quickly,which suggests the formation of a passive layer on the surface. Cyclic voltammograms done atpH 2 supports this as no peaks were seen. Quantitative calculations from the SEM analysis onthe electrode surface after the measurement at pH 1.5 showed only copper, iron and an excessof sulfur. Thus the passive layer is suggested to be sulfur rich or possibly pure sulfur. It wasalso observed that at pH 2.25 there is a period of constant current until t = 1100s, after whichthe current density starts to decrease.

Voltammograms at pH 3 showed two peaks at 740 and 870 mV vs. Ag/AgCl, whichare most likely due to the formation of the rust-coloured layer. The current density decreasedwith each subsequent sweep and the reaction rate finally became constant. This indicates that areaction product layer forms and the reaction taking place through that layer reaches steadystate.

The cross cut analysis by SEM/EDS, of an electrode after anodic polarization at pH 3showed the formation of a two-phase layer consisting mainly of iron and oxygen (in the ratio1:2 to 1:3). Low concentrations of chloride and sulfur were also present, but almost no copperor sodium were detected. The colour of the electrode surface after anodic polarization at pH 3was red with cupric concentrations of 17.9 g/l or greater, and more yellow with lower cupricconcentrations. This suggests that at pH 3, with higher cupric ion concentrations, a hematite-like layer is formed on the surface, and with lower cupric ion concentrations a hydrated ironoxide or goethite type layer is formed. [16]

4.3. Temperature EffectIn the temperature range 70 to 90 C at pH 2 an increase in temperature gave a

corresponding increase in the corrosion potential for all cupric ion concentrations. From the


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anodic polarisation measurements it was observed that the increase in temperature wasaccompanied by an increase in the corrosion current density with all cupric ionconcentrationsat pH 2. The current densities doubled when the temperature was increased from 70 C to 90C.

4.4. Reaction controlling mechanismThe polarization curves both with standard and rotating disk electrodes were used to

clarify the mechanism of the rate-controlling step. The activation energy, Ea, was calculated at600, 700 and 800 mV vs. Ag/AgCl. Levich plots were made at 700, 800 and 900 mV vs.Ag/AgCl. From the anodic polarization curves when the cupric concentration was 4.5 or 9 g/l(pH = 2, T = 85 C) then Ea was calculated to be 40-45 kJ/mol. With higher copperconcentrations (17.9 and 26.6 g/l) Ea was < 35 kJ/mol. The Levich plot gave a linear responsewith a cupric ion concentrations of 9 g/l and 17.9 g/l (pH 2, T = 85 C), Fig. 5. With a cupricconcentration of 17.9 g/l the diffusion coefficient was calculated with Levich equation to be4.4 10-6 cm2/s, when the cupric concentration was 9.0 g/l the diffusion coefficient was ca.1/10th of that value. Again, this supports the idea that a reaction product layer is formed on thechalcopyrite surface and the reactions on that layer are diffusion controlled. With cupric ionconcentrations 0.9 and 4.5 g/l, the Levich plot was non-linear.

0 2 4 6 8 10 12 14 16 18

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

LIMITINGCURRENTDENSITY(mA/cm2)

SQUARE ROOT OF ANGULAR SPEED (1/s)

at 700 mV vs. Ag/AgCly = 0.044x + 0.18

at 800 mV vs. Ag/AgCl

y = 0.054x + 0.12

at 900 mV vs. Ag/AgCl

y = 0.056x + 0.11

Fig. 5. Levich plot with cupric ion concentration 17.9 g/l. Limiting current density taken at

700, 800 and 900 mV vs. Ag/AgCl

We propose that with cupric concentrations greater than 9g/l, at pH = 2 and T = 85C, the rate controlling factor is diffusion in the solution. With a cupric concentration of 9 g/lthe reaction is controlled by diffusion through the reaction product layer. With lower cupricion concentrations the reaction is under mixed or chemical control.

5. Discussion and conclusionsFor pHs in the range 1.0 to 2.5 and temperatures in the range 70 to 90 C a critical

copper concentration of 9 g/l was found. Below that concentration limit the corrosion potential

followed the Nernst equation and the increase in the corrosion potential was ca. 60mV/decade. It was also found that [Cu2+] 9 g/l did not have any effect on the reaction rate.Cupric concentrations above 9 g/l increased the reaction rate. The same was calculated from


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Tafel plots, i.e. that [Cu2+] 9 g/l did not affect the dissolution rate and concentrations greaterthan 9 g/l increased the dissolution rate.

The reaction rate control appeared to change around [Cu2+] = 9 g/l. Above that thereaction rate control is assumed to be diffusion in solution, the diffusion coefficient beingca. 4.4 10-6 cm2/s. With [Cu2+] = 9 g/l the reaction is controlled by diffusion through thereaction product layer. With lower cupric ion concentrations the reaction was under chemicalor mixed control. An increase in temperature between 70 and 90 C (at pH 2) was observed to

increase the current densities and the dissolution rates for all cupric ion concentrations.The results indicate that there is a change in the electrochemical behavior of the

system between pH 2 and 2.25 (with [Cu2+] > 9 g/l and T = 70-90 C). Low dissolution ratesat more acidic pH values are due to the rapid formation of a sulfur-rich reaction product layerthat impedes the dissolution of chalcopyrite, supported by the detection of excess surfaceconcentrations of sulfur from the SEM/EDS analysis. The dissolution rates were higher at lessacidic pHs and this is most likely due to the slower formation of the porous iron rich reactionproduct layer. The Fe:O ratio was calculated to be between 1:2 and 1:3.

Together with visual observations the presence of goethite and iron hydroxides issuggested.

440 460 480 500 520 540 560 580 600

0.0

0.2

0.4

0.6

0.8

1.0

1.2

CORROSION

CURRENTDENSITY(mA/cm2)


[Cu2+

] > 9 g/l and pH > 2

[Cu2+

] > 9 g/l and pH 2

[Cu2+

] 9 g/l and pH > 2

[Cu2+

] 9 g/l and pH 2

Fig. 6. A plot of corrosion current density vs. corrosion potential.(i) [Cu2+] > 9 g/l and pH >

2.25, (ii) [Cu2+] > 9 g/l and pH < 2.25, (iii) [Cu2+] 9 g/l and pH > 2.25 and (iv) [Cu2+]

9 g/l and pH < 2.25.

The value ofjcorr was shown to depend not only on the corrosion potential, but it isalso strongly dependent on several solution parameters. The corrosion current density in Fig. 6was determined from the anodic polarization curves by the Tafel method. The highestcalculated values ofjcorr were ca. 1 mA/cm

2. A process window, where the dissolution of

chalcopyrite is possible, can be formed. The pH should be > 2 or the formation of a sulfur-richproduct layer effectively prevents the leaching. The upper limit for pH is the precipitation ofcopper oxychloride which begins around pH 3. Cupric ion concentration should be > 9 g/l.

The best leaching environment is thus one of high cupric ion concentration, high pH and hightemperature, as shown in group (i) of Fig. 6.


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References[1] Berger, J.M., Winand, R., Solubilities, densities and electrical conductivities of aqueous

copper(I) and copper (II) chlorides in solutions containing other chlorides such as iron,zinc, sodium and hydrogen chlorides. Hydrometallurgy 12(1984), pp. 61-81.

[2] Fritz, J.J., Chloride Complexes of CuCl in Aqueous Solution. Journal of PhysicalChemistry 84(1980) 18, pp. 2241-2246.

[3] Fontana, A., van Muylder, J., Winand, R., Etude Spectrophotometrique De Solutions

Aqueuses Chlorurees De Chlorure Cuivreux, a Concentrations Elevees. Hydrometallurgy11(1983), pp. 287-314.

[4] McDonald, G.W., Udovic, T.J., Dumesic, J.A., Langer, S.H., Equilibria associated withcupric chloride leaching of chalcopyrite concentrate. Hydrometallurgy 13(1984), pp.125-135.

[5] Muir, D.M., Basic Principles of Chloride Hydrometallurgy. Chloride MetallurgyII(2002), pp. 759-778.

[6] Hackl, R.P., Dreisinger, D.B., Peters, E., King, J.A., Passivation of Chalcopyrite duringoxidative leaching in sulfate media. Hydrometallurgy 39(1995), pp. 25-48.

[7] Parker, A., Klauber, C., Kougianos, A., Watling, H.R., van Bronswijk, W., An X-ray photoelectron spectroscopy study of the mechanism of oxidative dissolution ofchalcopyrite. Hydrometallurgy 71(2003), pp. 265-276.

[8] Munoz, P.B., Miller, J.D., Wadsworth, M.E., Reaction Mechanism for the Acid Ferric

Sulfate Leaching of Chalcopyrite. Metallurgical Transactions B, 10B(1979), pp. 149-158.[9] Roman, R.J., Benner, B.R., The dissolution of copper concentrates. Minerals Science

and Engineering 5(1973) 1, pp. 3-24.[10] Hietala, K., Hyvrinen, O., HydroCopperTM A New Technology for Copper

Production. In Alta 2003 Copper Conference. Perth, Australia, 22-23 May.[11] Hyvrinen, O., Hmlinen, M., Leimala, R., Outokumpu HydroCopperTM Process A

Novel Concept in Copper Production. In Chloride Metallurgy 2002, 32nd

AnnualHydrometallurgy Meeting. Peek, E., van Weert, G. (eds). Montreal, Qubec, Canada.MetSoc. pp. 609-612.

[12] Olper, M., Maccagni, M., The modified Ecuprex process: A promising hydrometallurgyapproach for chalcopyrite-bearing copper concentrates. In Hydrometallurgy of Copper.Riveros, P.A., Dixon, D.G., Dreisinger, D.B., Menacho, J.H. (eds.). Santiago, Chile,2003. Met. Soc., pp. 319-334.

[13] Habashi, F., Chalcopyrite its Chemistry and Metallurgy. McGraw-Hill, Great Britain,1978, pp. 1, 63, 78, 79.

[14] Wilson, J.P., Fisher, W.W., Cupric Chloride Leaching of Chalcopyrite. Journal of Metals33(1981) 2, p. 52-57.

[15] Hirato, T., Majima, H., Awakura, Y., The Leaching of Chalcopyrite with CupricChloride. Metallurgical Transactions B, 18B(1987), pp. 31-39.

[16] Lundstrm, M., Leaching of chalcopyrite in cupric chloride media. M. Sc. Thesis,Helsinki University of Technology, Espoo, Finland. 2004. p. 96.

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