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Recovery of copper and cobalt in the comparative flotation of a sulfide ore using xanthate and dithiophosphate as collectors

July 2019
International Journal of Engineering and Applied Sciences (IJEAS) 6(7)

DOI:10.31873/IJEAS.6.7.2019.06

Authors:

Alexandria University

Copper and cobalt are two major metals used in industry. They play a role in widely many domains like that electricity, chemistry and electrochemistry. They are contained into several minerals like chalcopyrite, carrolite, chalcocite, etc. associated to pyrite. The froth flotation and behaviors of chalcocite and carrolite were investigated through many flotation tests in order to recovery copper and cobalt. This paper investigates the effect of potassium amyl xanthate (PAX) and sodium dibutyl dithiophosphate (DANA) performance on both copper and cobalt recovery in single roughing flotation. The effect of pH on the flotation is proposed. Some parameters were kept constant such as particle size d80=75 μm, pulp density 10% solids, impeller speed 1300 rpm, and PAX doses of DANA (105 g/t per each) as collectors, dose of DF250 (5 drops) as frother, dose of Na2SiO3 (200 g/t) as dispersant and depressant. Only the pulp pH was varied from the natural pH to 11, using Ca(OH)2 as regulator. According to results, PAX (105 g/t) was found as the best collector for recovery of copper both at natural pH and pH=11. At natural pH, the concentrate was found at 16.1% copper recovery with a yield of 99.63%. At pH=11, the concentrate was found at 16.1% copper recovery with a yield of 99.05%. For the recovery of cobalt, DANA (105 g/t) was found better as the collector at natural pH producing a concentrate at 0.51% cobalt recovery yield of 76.48%. At pH=11, PAX (105 g/t) was found better as the collector. The concentrate was found at 0.91% cobalt with a recovery yield of 85.13%.

: Variation of copper's grade vs time at different pH values

…

: Variation of cobalt's grade vs time at different pH values According to Fig. 5 and 6, we observe that at natural pH, selectivity of DANA is higher than selectivity of PAX. Cobalt recoveries for both collectors are almost the same to the third minute and beyond the third minute, the growth recovery is more pronounced for DANA than for PAX. Thus, with DANA, we obtain a concentrate at 0.51% cobalt at a yield of 76.48%. With PAX, 1.13% cobalt concentrate is obtained with a yield of 47.37%. At pH=11, PAX is largely better from the beginning to the end of cobalt recovery. It gives a concentrate at 0.91% cobalt with a yield of 85.18%, it is most selective.

…

: Determination of rate constant in flotation of copper at different pH values

…

: Determination of rate constant in flotation of cobalt at different pH values In cobalt recovery, the rate flotation constant is higher by DANA at natural pH (0.172 s -1 ) and by PAX at pH=11 (0.203 s -1 ).

…

Chemical analysis of the sample by AAS/ICP

…

Figures - uploaded by Meschack Muanda

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Content uploaded by Meschack Muanda

Content may be subject to copyright.

International Journal of Engineering and Applied Sciences (IJEAS)

ISSN: 2394-3661, Volume-6, Issue-7, July 2019

26 www.ijeas.org

 Abstract— Copper and cobalt are two major metals used in

industry. They play a role in widely many domains like that

electricity, chemistry and electrochemistry. They are contained

into several minerals like chalcopyrite, carrolite, chalcocite, etc.

associated to pyrite. The froth flotation and behaviors of

chalcocite and carrolite were investigated through many

flotation tests in order to recovery copper and cobalt. This paper

investigates the effect of potassium amyl xanthate (PAX) and

sodium dibutyl dithiophosphate (DANA) performance on both

copper and cobalt recovery in single roughing flotation. The

effect of pH on the flotation is proposed. Some parameters were

kept constant such as particle size d80=75 μm, pulp density 10%

solids, impeller speed 1300 rpm, and PAX doses of DANA (105

g/t per each) as collectors, dose of DF250 (5 drops) as frother,

dose of Na2SiO3 (200 g/t) as dispersant and depressant. Only the

pulp pH was varied from the natural pH to 11, using Ca(OH)2 as

regulator. According to results, PAX (105 g/t) was found as the

best collector for recovery of copper both at natural pH and

pH=11. At natural pH, the concentrate was found at 16.1%

copper recovery with a yield of 99.63%. At pH=11, the

concentrate was found at 16.1% copper recovery with a yield of

99.05%. For the recovery of cobalt, DANA (105 g/t) was found

better as the collector at natural pH producing a concentrate at

0.51% cobalt recovery yield of 76.48%. At pH=11, PAX (105

g/t) was found better as the collector. The concentrate was found

at 0.91% cobalt with a recovery yield of 85.13%.

Index Terms— cobalt, copper, dithiophosphate, flotation,

xanthate.

I. INTRODUCTION

The evolution of technology has led the development of

several mining techniques for base metals that are most used.

Copper and cobalt are part and are contained in the oxidized

minerals, sulphide or mixed. They are used in several

disciplines: electricity, robotics, battery manufacturing, metal

alloys, machine building, and the list is not exhaustive [5], [9],

[11], [19].

Copper is a strategic metal and its demand is growing rapidly

[15]. Cobalt has also a great role for the growth of humans,

animals and plants. However, it cannot be taken to avoid

excessively toxic effects. [17]. Copper-cobalt ore from

copper and cobalt come from the Central African Copper Belt

in the Democratic Republic of Congo and Zambia.

Copper sulfide minerals are chalcopyrite CuFeS2, chalcocite

CuS2, bornite Cu5FeS4. Cobalt sulfide minerals are cobaltine

Meschack Muanda Mukunga, Department of Chemical and

Metallurgical Engineering, University of the Witwatersrand, Johannesburg,

South Africa

(CoAsS), carrollite (Cu (Co.Ni)2S4) and linneite (Co3S4).

These minerals are accompanied by pyrite, which is a great

source of iron [3], [4].

Several studies on the treatment of copper-cobalt minerals

were conducted and-have shown that at pH (about 4), the

flotation of cobalt from sulfide already is best using xanthate

collector. When using nitrosonaphthol chelating reagents, the

flotation of cobalt oxides from already is best at the pH of

about 7.5 [4].

The flotation foam of a mineral sulphide Cu-Co produce a

Cu-Co bulk concentrate. During the flotation, Cu-Co float at

natural pH or pH 11 using xanthate or dithiophosphate. This

occurs when the copper mineralization as chalcocite.

Thereafter separating copper and cobalt in the bulk

concentrate is done by raising the pH to at least 11, which

depresses the cobalt minerals. It has been shown that

xanthates float better the cobalt minerals at pH=11 and

dithiophosphates do at natural pH [4].

In this study, we collected samples in the mine of Kalukuluku

in Lubumbashi in the Democratic Republic of Congo.

Chalcocite is abundant copper mineral and carrolite is

abundant mineral cobalt. For flotation tests, potassium

amylxanthate (PAX: C5H11OCS2Na) family of xanthates and

sodium amyl dithiophosphate (DANA:C8H18O2PS2Na)

family dithiophosphates were used as collectors.

Polypropylene glycol methyl ether (Dowfroth 250: DF250)

was used as foaming and sodium silicate (Na2SiO3) as

depressing and dispersant. Slaked lime (Ca(OH)2) was used

as a pH regulator. The latter was varied keeping all other

parameters constant: particle size, pulp density, impeller

speed, reagents doses (PAX, DF250).

Flotation kinetics was treated for study the variation of the

cumulative recovery of a component (copper and cobalt)

proportionally to flotation time [18], as a time-rate recovery

process.

II. MATERIALS AND METHODS

A. Sample

The ore sample on which we worked was from mine of

Kalukuluku in Lubumbashi in the Democratic Republic of

Congo. It has been crushed in a laboratory jaw crusher

(primary) and then in a cylindrical laboratory crusher

(secondary) to have a size <1.7 mm. We collected 25 kg for

the result of our tests. The X-ray diffraction analysis revealed

the presence of chalcopyrite CuFeS2, of chalcocite Cu2S and

Carrolite CuCo2S4 as sulphides. The matrix was made of

quartz SiO2, Dolomite CaMg(CO3)2, Feldspar AlSi3O8 and

talc Mg3Si4O10(OH)2. After analysis by atomic-absorption

ICP, the contents of Table 1 have been revealed.

Recovery of copper and cobalt in the comparative

flotation of a sulfide ore using xanthate and

dithiophosphate as collectors

Meschack Muanda Mukunga

Recovery of copper and cobalt in the comparative flotation of a sulfide ore using xanthate and dithiophosphate as

collectors

27 www.ijeas.org

Table 1: Chemical analysis of the sample by AAS/ICP

Elements

Contents (%)

CuT

3.57

CuOx

0.4

CoT

0.39

Coox

0.01

2.94

0.13

9,765

B. Reagents

PAX and DANA were used as collectors and have been

prepared at 1% by dissolving 1 g in 100 ml of water. Na2SiO3

was used as depressing and dispersant and was prepared at

30% by dissolving 30 g in 100 ml of water. Ca(OH)2 as a pH

regulator was prepared at 20% by dissolving 20 g of CaO in

100 ml water. DF250 has been used as frother. Tap water was

used for the flotation tests. Equation (1) was used for the

passage of g/t to ml for each reagent.

(1)

C. Equipment

The following equipment was used: a laboratory mill

(length: 260 mm, diameter: 180 mm, rotation speed: 100

rpm), a flotation machine DENVER, flotation cell of 2.5 L,

panels, an VIBRA electronic balance, graduated vessels for

reagents, a pH meter, a propipette, a wash bottle of 1 liter, a

pallet.

D. Grinding

1 kg of sample was mixed with 1 l of water in the mill with

50% solids into the mill. This grinding was carried out at

different times 15, 20 and 25 minutes respectively. The pulp

from the mill was placed on a sieve of 75 μm and then the

refusing was oven dried and weighed. According to Fig. 1,

grinding curve was plotted by varying the refusing 75-μm size

vs time.

Fig.1: Grinding curve’s ore of Kalukuluku

For our flotation tests, we had considered 20% of refusing on

the sieve of 75 μm. And in view of Fig. 1, 18 minutes of

grinding has been required.

E. Flotation test

Before the flotation tests in single roughing, pH meter has

been calibrated. The ore was ground for 18 minutes. The pulp

was placed into the flotation cell of 2.5 L. Having lowered the

rotor into the pulp, we operated the operation at 1300 rpm.

We added Na2SiO3 conditioned for 3 minutes and Ca(OH)2

for pH regulation. Note that have worked at natural pH and

pH 11. Then collector (45 g/t) and frother (5 drops) were

added conditioned for 2 minutes. After that, we opened the air

valve at 5 L per min and collected concentrates in fractions of

0.5; 0.5; 1; 1; 2; 2 and 2 minutes respectively. The first 4

fractions were made the head concentrate. All concentrates

and tailings were sent to the laboratory for chemical analysis

by AAS-ICP to determine the amounts of copper and cobalt.

The 60 g/t corresponding to the remaining collector were

added after the recollections fractions coming after the first,

during a conditioning time of one minute. The flotation

kinetics was also evaluated for comparison between PAX and

DANA in recovery of copper and cobalt, using the variation

of constant rate vs time. The flotation scheme in simple

roughing is shown by the Fig. 2.

Fig.2: Diagram of single roughing flotation tests

III. RESULTS AND DISCUSSION

A. Variations recovery vs time and grade vs time

Fig. 2 was used to study concerned variations by changing

every time the pH using Ca(OH)2. We worked in at natural pH

and pH=11. The other parameters were kept constant: d80=75

μm, PAX (105 g/t), DF250 (5 drops), pulp density 10% solids

and impeller speed of 1300 rpm. The pulp produced by

milling for 18 minutes was placed in 2.5 L. Ca(OH)2 was

added (only to adjust pH to 11), PAX and DF250 was added

conditioned for 5 minutes. Then the air intake was introduced

at 5 L per min. Finally, concentrates and tailings were

collected, sent to laboratory for analysis by ICP-AAS to

determine grades of copper and cobalt, as well as recovery

yields.

1) Variations for copper

Figs. 3 and 4 show results of recovery and grade of copper

vs time at different pH values.

By comparison with the results of Fig. 3 and 4, we note that at

natural pH, copper recovery is fast with DANA until the fifth

minute. After the fifth minute, recovery of copper with PAX is

better and gives a concentrate at 16.1% with a yield of

99.63%. At pH 11, the curve of the PAX is better than DANA,

giving a concentrate at 16.1% copper with a yield of 99.05%.

Thus, the copper recovery is quick at natural pH with the

DANA until the fifth minute. After the fifth minute of

flotation, the PAX is better. At pH=11, PAX have a good

selectivity.

International Journal of Engineering and Applied Sciences (IJEAS)

ISSN: 2394-3661, Volume-6, Issue-7, July 2019

28 www.ijeas.org

Fig.3 : Variation of copper’s grade vs time at different pH

values

Fig.4 : Variation of copper’s recovery vs time at different pH

values

These results confirmed that the flotation by PAX is steady in

an alkaline medium condition [16].

2) Variations for cobalt

Figs. 5 and 6 show results of recovery and grade of cobalt vs

time at different pH values.

Fig.5 : Variation of cobalt’s grade vs time at different pH

values

According to Fig. 5 and 6, we observe that at natural pH,

selectivity of DANA is higher than selectivity of PAX. Cobalt

recoveries for both collectors are almost the same to the third

minute and beyond the third minute, the growth recovery is

more pronounced for DANA than for PAX.

Thus, with DANA, we obtain a concentrate at 0.51% cobalt

at a yield of 76.48%. With PAX, 1.13% cobalt concentrate is

obtained with a yield of 47.37%.

At pH=11, PAX is largely better from the beginning to the end

of cobalt recovery. It gives a concentrate at 0.91% cobalt with

a yield of 85.18%, it is most selective.

Fig.6 : Variation of cobalt recovery vs time at different pH

values

At pH=11, PAX is largely better from the beginning to the end

of cobalt recovery. It gives a concentrate at 0.91% cobalt with

a yield of 85.18%, it is most selective. This confirms the study

[14] who said that the alkaline pH depresses pyrite in the

presence of xanthates, increasing the selectivity of the used

collector.

B. Determination of flotation rate constant

Several authors have investigated the first order flotation

kinetics models [1], [6], [8], [10], [12]-[13]. Among those

models, the classic model is investigated for our study and

according to this model; we have calculated the first order rate

constant k from equation (2).

[2] and [7] have shown that the flotation kinetics studies the

quantitative variation of the recovery R of the floatable

mineral in concentrate vs time t.

(2)

where is the maximum recovery achievable or the

cumulative recovery at time infinite (%), is the recovery at

time t (%), k is the first order rate constant (s-1), t is the

flotation time (s). After developing the formula (2), we obtain

equation (3).

(3)

In the case of our study, we evaluate the variation of the factor

vs flotation time to find the rate constant k,

both for copper and cobalt.

1) For copper

According to Fig. 7, at natural pH, the flotation rate constant

is better by DANA till the 5th minute and after that, the

flotation rate by PAX increased till the end of flotation. At

pH=11, the flotation rate is largely best by PAX than by

DANA. In copper recovery, the rate flotation constant is

higher by PAX at natural pH (0.634 s-1) and pH=11 (0.443

s-1). Another very important observation concerning PAX is

that its faster kinetics in the recovery of copper both at natural

pH and at pH=11.

Fig.7 : Determination of rate constant in flotation of copper at

different pH values

In both the values of pH, the first order rate constant for

copper recovery by PAX was found to be higher than that by

DANA.

2) For cobalt

Fig. 8 shows that the rate flotation constant is better by

DANA at natural pH and by PAX at pH=11 from the

Recovery of copper and cobalt in the comparative flotation of a sulfide ore using xanthate and dithiophosphate as

collectors

29 www.ijeas.org

beginning to the end of flotation. Another confirmation is that

the rate flotation constant increases rapidly after the third

minute by DANA at natural pH.

Fig.8 : Determination of rate constant in flotation of cobalt at

different pH values

In cobalt recovery, the rate flotation constant is higher by

DANA at natural pH (0.172 s-1) and by PAX at pH=11 (0.203

s-1).

IV. CONCLUSION

This study was intended to compare the selectivity and

kinetics of PAX and DANA in recovery of copper and cobalt

from a sulfide Copper-Cobalt ore. Keeping the particle size,

pulp density, impeller speed, and reagents doses as constant

parameters, only the pH was varied from the natural and

pH=11. At natural pH, PAX was given the good results for the

recovery of copper obtaining a concentrate of 16,1% with a

yield of 99,63% and a flotation rate constant of 0,634 s-1. For

the recovery of cobalt, DANA was found as better collector

obtaining a concentrate of 0.51% with a yield of 76.48% and a

flotation rate constant of 0,172 s-1. At pH=11, PAX was found

as the better collector for the recovery of both copper and

cobalt obtaining concentrates of 16,1% Cu and 0,91% Co

respectively. The flotation yields were 99,05% and 85,18%

respectively. Flotation rate constants were 0,443 s-1 and 0,203

s-1 respectively. According to these results, it is clearly shown

that at both natural pH and pH=11, the kinetic of copper

recovery is better by PAX than by DANA. However, for the

kinetic of cobalt, DANA is better than PAX at natural pH. It is

therefore recommended that a kinetic study be further

undertaken in acidic conditions.

ACKNOWLEDGMENT

Authors thank the company Chemical of Africa that has

opened the doors for the samples and the laboratory.

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[20]

Meschack Muanda Mukunga: Graduate Engineer in

Department of chemical and metallurgical Engineering at University of

Lubumbashi since year 2016. Secondary school was done and completed in

Imara Institute in Lubumbashi/ DRCongo since 2009. Graduate has been

done at University of Lubumbashi in july 2016. Actually Master student

(student number 2060556) at in department of chemical and metallurgical

engineering, University of the Witwatersrand in Johannesburg/South Africa.

About research, “Optimization of current efficiency in electrowinning of

copper” has been done at MMG company (Kinsevere Mine) in year 2014.

Assistant teacher of Omalanga Pele Pascal Daniel who is teacher at

University of Lubumbashi since 2016

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May 2021

Copper-cobalt oxide ores contain several minerals that are economically treatable by concentration techniques. The most used technique is froth flotation in which selective reagents are used to recover more valuables. It is, therefore, important to examine the optimal doses of those reagents while investigating the behaviors of minerals at the same time. This study explored the influence of lead nitrate Pb(NO3)2 on the froth flotation of oxide ore to increase valuable metals recoveries. Four factors were investigated including Pb(NO3)2 dosage, its conditioning, its addition dose in the 2nd fraction, and sulfidiser dosage. Other parameters were kept constant. The optimum was found at 25 g/t of Pb(NO3)2, conditioning together with sodium silicate (Na2SiO3) for 5 min, the addition of 5 g/t of Pb(NO3)2 in the 2nd fraction, and 3,000 g/t of sulfidiser. Recoveries in concentrates were 79.51 % Copper (Cu) and 60.27 % Cobalt (Co), with grades of 9.49 and 0.67 %, respectively. The conclusion was that the use of Pb(NO3)2 can considerably improve copper and cobalt recoveries.

Comparative Cleaning Stages in Recovery of Copper and Cobalt from Tailings using Potassium Amylxanthate as Collector

Article

Full-text available

Feb 2021

Copper and cobalt demand is projected to be increased from here to 2050 and the challenge is to find treat economically minerals which contains those metals. Several tailings from oxide ores throughout the word contain good grades of copper and cobalt that should be recovered by froth flotation. This paper investigates the recovery of copper and cobalt through reprocessing of spiral classifier tailings by determination of specific reagents dosage. The flotation behaviours of malachite and heterogenite were studied through many roughing and cleaning flotation tests in order to recovery most of copper and cobalt. The effect of specific reagents was be varied and others parameters were kept constant. The highest recoveries of both copper and cobalt in rougher concentrate were respectively 82.51% and 72.51% with grades of 12.52% and 0.99% respectively. However, the cleaner concentrate was 24.54 Cu% and 1.38% Co with recoveries of 69.26 % and 40.7% respectively. It was concluded that the reprocessing of spiral classifier tailings through froth flotation is benefit because it recovers most of desired metal and reduces the risk of their presence on environment through plant tailings. Recycling of cleaner tailings was also proposed.

UTILIZATION OF FLOTATION IN COPPER EXTRACTION FROM POLYMETALLIC ORE

Article

Full-text available

Mar 2020

The aim of this study was to examine flotation of utility metals from poor polymetallic ores and verify the potential for profitable yields in connection with potentially economic deposits of non-ferrous metals. The paper describes results in flotation concentrate research to recover copper from polymetallic ore. The polymetallic ore from Zlate Hory deposit (Czech Republic) was subjected to crushing, grinding, and screening to prepare feed for separation with mesh size under 200 microns. The heavy medium separation was performed in tetrabromethane with a density of 2.967 g.cm-3. The float and sink products were obtained and tested for chemical composition. Next, the treated polymetallic ore sample was subjected to flotation. In flotation, various dosages of collector (PAX) and various pH were tested, at which pyrite was depressed. The recovery of metallic copper in the concentrate increased with the collector dose. As the pH of the medium increased, the pyrite content in the concentrate dropped. The lowest content of pyrite, i.e. 4.01 %, was obtained at pH 10. In the original polymetallic ore, the Cu content was 0.41 % after subsequent treatment and flotation tests, the Cu content increased to 1.38 % with Cu recovery 86.18 %.

Sustainable extraction of base metals from multi-mineralized base metal deposits: A case study of a copper deposit

Conference Paper

Sep 2022

The vision of the Namibian mining industry is “to be a widely respected, as a safe, environmentally responsible, globally competitive, and meaningful contributor to the long-term prosperity of Namibia” . In order to realise this vision, the mining industry is expected to ensure responsible mining and processing of ores while contributing to the gross domestic product (GDP) of the country in the immediate and long term. Socio-economic benefits in the long term can only be realised if the mineral reserves are accurately characterised and quantified to inform the development of optimal process flow sheets for the metal extraction. Namibia is endowed with deposits of various base metals. These include copper (Cu), lead (Pb), zinc (Zn), and tin (Sn). Additionally, Namibia also possesses deposits of energy minerals, namely uranium (U) and lithium (Li) as well as deposits of non-metals such as graphite and fluorspar. The base metal ores are currently mined and processed at various mines in the country, with Pb and Zn mined at Trevali’s Rosh Pinah Zinc Corporation (RPZC) while Sn is mined at Afritin Mining’s Uis Tin Mine. Trigon Metal’s Kombat Copper Mine which resumed operations in 2021 was the only operating copper mine in the country before it was placed on care and maintenance again in August 2022 after seven months of operation. Prior to resumption of mining operations in 2021, Kombat Mine had been dormant for close to two decades. The other three copper mines, namely Otjihase, Matchless and Tschudi are also on ‘care and maintenance’. While the market conditions, especially the copper price, significantly impact the decision to keep the mine in operation, another factor which can force the mine management and investors to cease operation is the significant change in the mineralisation of the orebody. This could result in high operating costs as a result of retrofitting additional sections or simply use of expensive reagents or ‘aggressive’ operating conditions which are, for example, necessitating the use of additional power or water in the processing plant. The need for an advanced mining method e.g., underground method versus opencast method may also be a critical factor. In short, the sustainability of a multi-mineralised mine can be negatively affected if no appropriate flow sheet development consideration is executed timeously. A good example of an orebody with distinct mineralisation is a copper deposit located within the Damara orogenic belt, approximately 20 km west of Tsumeb in northern Namibia. This copper deposit is mainly made up of sandstone and it consists of three mineralisation zones: the oxide zone outcropping on the surface, a transition (mixed) zone in the middle, and the sulphide zone at the bottom2. Copper mineralisation in the oxide zone extends approximately 70 m below the surface; it is mainly composed of copper minerals such as malachite (Cu2CO3(OH)2), azurite (Cu3(CO3)2(OH)2), cuprite (Cu2O), and minor chalcocite (Cu2S). This mineralisation is disseminated through a sandstone and a conglomerate unit lying above a dolomite unit. The transition zone contains a combination of oxides (predominantly malachite) and the sulphides (predominantly chalcocite and bornite, with covellite (CuS) in minor quantities). While the sulphide zone contains chalcopyrite (CuFeS_2), bornite (Cu5FeS4), and chalcocite (Cu2S). Since the processing plant is usually constructed for a specific ore type (e.g., oxide or sulphide), upon depletion of the oxide ore, the mine has two options which are dependent on the prevailing and projected market conditions as well as financial position of the company. The first option is to cease operation and declare the end of life of mine (LOM). Alternatively, the mine can engage in an expansion programme to develop or re-design the process flow sheet for treating other different mineralisation zones. A holistic consideration of the multi-mineralised zones ensures that the processing plant is designed, in phases i.e., phase 1 and 2, to extract copper sustainably and efficiently from all the distinct ore mineralisation zones. For the copper deposit with three mineralisation zones as discussed above, phase 1 would entail processing of the ore extracted from the oxide zone which responds favourably to the low-cost heap leaching with dilute sulphuric acid (H2SO4). The copper sulphide minerals do not respond favourably to leaching unless it is done under reducing and ‘aggressive’ conditions. An example would be the use of microorganisms in bioleaching or at elevated pressures in autoclaves, i.e., pressure leaching. This should be part of phase 2, in which copper should preferably be extracted from the sulphide ore after a concentration stage such as froth flotation to reduce the tonnage, and thereby improving the grade of metal value while reducing the concentration of impurities (gangue) by using pyrometallurgical unit processes in a smelter, such as at Dundee Precious Metals Tsumeb smelter. Such a processing route is characterised by fast kinetics, but it can be energy-intensive. Depending on the ratio of oxide/sulphide minerals, the transition ore can be processed by using the flow sheet for either oxide (i.e., via heap leaching, at adjusted operating conditions, such as increased lixiviant consumption) or sulphide (i.e., smelting, after froth flotation at controlled operating conditions, such as pressure of oxygen to minimise the copper reporting to the slag phase). The authors propose a holistic and more sustainable approach. To ensure a sustainable extraction of multi-mineralised base metal deposits, it is critical to increase the LOM of such operations. The ore from all three mineralisation zones should be extracted as compared to only mining and processing ore from a single mineralisation zone and then closing the mine. Therefore, the proposed approach ensures mining and processing of the ore from all mineralisation zones. The principal aim is to minimise disruption to operations caused by focusing only on specific ore types within a given deposit while knowing very well that the orebody is multi-mineralised. During phase 1, i.e., when processing the oxide ore, a comprehensive metallurgical test work programme should be initiated and fully undertaken to guide the development of the flow sheets for the transition and sulphide ores, with the configuration and/or design of the processing plant pursued towards the end of phase 1 to avoid disruptions to operations after that phase. The alternative is to prolong the LOM after phase 1 by converting the mine into a concentrator to produce the copper concentrate, from both the transition and sulphide ores, which can then be sold to the smelters.

Modeling of Flotation Process-An Overview of Different Approaches

Article

Full-text available

Nov 2015

The modelling of flotation has been reviewed with the aim of identifying their usefulness, significance as well as limitations. From literature it is clear that, various flotation models have been developed based on the processes and sub-processes occurring in flotation. An overview of the literature indicates that various approaches have been adopted in quantifying the process. Flotation models based on kinetics have prevailed in almost all flotation conditions regardless of the ore type and ore characteristics as well as flotation cell configurations. It may be concluded that the classical first order kinetic model is comparatively a better model and can be utilized to optimize the flotation process as it is applicable to both batch and continuous flotation processes with high confidence level.Finally, it is suggested that future work should focus on improving the models which can more accurately predict the prevailing conditions and enable better optimization of the flotation process.

THE KINETIC FLOTATION MODELLING OF CHALCOPYRITE FROM DOMESTIC ORES USING SOFTWARE TOOLS

Conference Paper

Full-text available

Jun 2013

To improve kinetic flotation models, many first-order flotation kinetics models with distributions of flotation rate constants were redefined so that they could all be represented by the same set of three model parameters. As a result, the width of the distribution become independent of its mean, and parameters of the model and the curve fitting errors, became virtually the same, independent of the chosen distribution function. In our case, investigations of the chalcopyrite ores are carried out using the Classical model, Klimpel Model and fully mixed model. According to the experimental results obtained in laboratory, the Classical model is most appropriate for presentation of kinetic flotation, especially by means of MATLAB modeling.

Bioaccumulation of zinc, lead, copper, and cadmium from contaminated sediments by native plant species and Acrida cinerea in South China

Article

Full-text available

Nov 2013
ENVIRON MONIT ASSESS

This research was conducted to search and identify spontaneously growing heavy metal-tolerant plant species that are potentially useful for phytoremediation in contaminated sediment. Five sites were selected for collection of plants growing on polluted shore (river bank) sediment of the Xiang River, China. The concentrations of Zn, Pb, Cu and Cd in plants, sediments, and grasshoppers were determined using flame atomic absorption spectrophotometer (AAS700, Perkin-Elmer, USA). Considering translocation factor and bioaccumulation factor, Rumex crispus (Polygonaceae), Rumex dentatus (Polygonaceae), and Lagopsis supina (Labiatae) could be potentially useful for phytostabilization of metals. R. crispus can be considered potentially useful for phytoextraction of Cd. In light of the biomagnification factors, grasshoppers are deconcentrators for Pb and Cd, microconcentrators for Zn and macroconcentrators for Cu to the plants, respectively. To the best of our knowledge, the present study is the first report on Zn, Pb, Cu and Cd accumulation in R. crispus and L. supina, providing a pioneer contribution to the very small volume of data available on the potential use of native plant species from contaminated sediments in phytostabilization and phytoremediation technologies.

On resource depletion and productivity: The case of the Chilean copper industry

Article

Nov 2018
RESOUR POLICY

How resource depletion affects productivity is a crucial question for several industries. In fact, several natural resource-exporting countries have seen their productivity levels affected by resource depletion. Nevertheless, usually, it is not clear what the real productivity growth is, without discarding the effects of resource depletion in the production structure. The main aim of the paper is to empirically answer a relevant issue regarding the Chilean copper mining industry, which is, the slowdown of its productivity in the last decade, considering in the analysis the role of resource depletion. In particular, we consider resource depletion to be an exogenous and unpaid force that opposes technological change and hence increases costs through time, capturing in this way some stylized facts of, for example, the mining and fishing industries. The decomposition framework was applied to the Chilean copper mining industry, one of the most important in the world, using data from the period of 1985–2015. The econometric results were robust and pointed to the fact that the productivity fell sharply during the period; however, it did not fall as much as the traditional estimation methods pointed out. Our model showed that as much as 15% of this decline was due to the increase of the resource depletion variable (copper ore grade).

Flotation separation of chalcopyrite from galena by sodium humate and ammonium persulfate

Article

Jan 2016
T NONFERR METAL SOC

The flotabilities of chalcopyrite and galena with sodium humate (HA) and ammonium persulfate (APS) as the depressant were studied by flotation test, adsorption measurement and infrared spectroscopic analysis. Single mineral flotation test shows that the slurry oxidation environment and the proper oxidation of galena surface are prerequisites for the depression of galena by sodium humate. The closed-circuit flotation test of copper/lead bulk concentrate shows that the grade and recovery of Cu reach 30.47% and 89.16% respectively and those of Pb reach 2.06% and1.58% respectively in copper concentrate, and the grade and recovery of Pb reach 50.34% and 98.42% and those of Cu reach 1.45% and 10.84% respectively in lead concentrate with HA and APS. The selective depression effect of HA and APS is more obvious than that of potassium dichromate. The results of FTIR analysis and adsorption measurements indicate that the adsorption of sodium humate on the fresh surface of galena is negligible, while after oxidation, sodium humate can be chemically adsorbed on the surface of galena. According to the theory of solubility product, the sodium humate can display the oxidation product PbSO4, after then, adsorb on the surface of lead chemically to produce inhibitory effect. Thus, it can be seen that the combination of HA and APS is an efficient non-toxic reagent to achieve cleaning separation copper/lead bulk concentrate by flotation. The combination of HA and APS is an efficient non-toxic reagent to achieve cleaning for copper/lead bulk concentrate by flotation.

Physical Factors Affecting Recovery Rates in Flotation

Article

Jul 1977

The physical factors that influence the rate of flotation of particles are reviewed. Particular emphasis is placed on the hydrodynamic interactions between particles and bubbles and the dependence of the flotation rate on the particle and bubble sizes. Theory and experiment indicate that the flotation process is first-order with respect to the particle concentration. However, the rate constant is strongly dependent on the particle size and the bubble diameter. For small particles the flotation rate varies approximately as the diameter to the 1. 5 power, so for particles in the range 4 to 30 mu m the rate of removal from a cell is very low. However, it appears that the rate constant should vary inversely as the cube of the bubble diameter so one remedy for low recovery rates would be to use small bubbles of the order of 100 mu m in diameter.

Model Discrimination in the Flotation of a Porphyry Copper Ore

Article

May 1985
MINER METALL PROC

Numerous flotation models have been proposed in the literature. Thirteen of these have been applied to batch flotation data and evaluated with respect to one another using statistical techniques. Flotation tests were carried out on samples of a US porphyry copper ore (Pinto Valley, AZ). The ore was tested using various collector and frother systems to produce different time-recovery profiles. These were used to calculate flotation rate and ultimate recovery parameters for each model. The models were then evaluated statistically to determine the overall fit of the calculated to the observed data and to test the range of significance of the parameters in each model.

Investigation of Flotation Parameters for Copper Recovery from Enargite and Chalcopyrite Mixed Ore

Article

Apr 2012
MATER TRANS

A flotation pre-treatment study for the separation of enargite (Cu 3AsS 4) from chalcopyrite (CuFeS 2) ores of different origins was investigated in this work. The copper ore bearing enargite mineral contained 5.87 mass% As and 16.50 mass% Cu while the chalcopyrite bearing ore contained 0.32 mass% As and 21.63 mass% Cu. The two ore samples were mixed at 7 : 3 (enargite : chalcopyrite) by weight ratio to prepare a mixed ore sample with As content at 3.16 and 18.25 mass% Cu for the flotation study. Effect of particle size, slurry pH, flotation time, collector type, collector addition or dosage and depressants were investigated to evaluate efficiency of enargite separation from chalcopyrite and recovery of both minerals as separate concentrates. For enargite single ore flotation, the 38-75 μm size fraction showed that over 98% of enargite was selectively recovered within 5 min at slurry pH of 4 and As content in the final tailings was reduced to 0.22 mass%. In mix ore (enargite + chalcopyrite) flotation, 97% of enargite was first removed at pH 4 followed by chalcopyrite flotation at pH 8, and over 95% recovery was achieved in 15 min flotation time. The As content in the final tailings was reduced to 0.1 mass%.

Continuous Flotation Testing To Recover a Bulk Sulfide Concentrate From Missouri Lead Ore Tailings

Article

Jan 1989

The Missouri Pb ores are the only domestic Co resource being mined and processed for other metals; therefore, they present a viable short-term opportunity for Co production. Lead, zinc, and copper concentrates are produced from the ore. The Cu concentrate can contain up to 30 pct Co and the Pb concentrate up to 15 pct Co. Since Co is detrimental to the processing of the Zn concentrate; the remainder of the Co is rejected to the tailings. The tailings can contain as much as 50 pct Co originally present in the mined ore. Researchers at the U.S. Bureau of Mines have successfully tested on a continuous basis a process that recovers a bulk sulfide concentrate from mill tailings. The concentrate contains up to one-half of the Co and from 50 to 90 pct of the Pb, Zn, and Cu. Concentrate weight represents 10 pct or less of the total tailings.

Handbook of Flotation Reagents Chemistry, Theory and Practice: Flotation of Sulfide Ores

Article

Jan 2007

Srdjan M. Bulatovic

Handbook of Flotation Reagents: Chemistry, Theory and Practice is a condensed form of the fundamental knowledge of chemical reagents commonly used in flotation and is addressed to the researchers and plant metallurgists who employ these reagents. Consisting of three distinct parts: 1) provides detailed description of the chemistry used in mineral processing industry; 2) describes theoretical aspects of the action of flotation reagents 3) provides information on the use of reagents in over 100 operating plants treating Cu, Cu/Zn, Cu/Pb, Zn, Pb/Zn/Ag, Cu/Ni and Ni ores. * Looks at the theoretical aspects of flotation reagents * Examines the practical aspects of using chemical reagents in operating plants * Provides guidelines for researchers and engineers involved in process design and development. Significant progress in understanding the science of mineral processing over the past several decades has been made, especially in the development of chemical reagents. It should be stressed that chemical reagents used in flotation are the backbone of every flotation process. Therefore, the development of an effective reagent scheme for treatment of mineral ores is closely related to understanding the chemistry and reaction of the individual reagents in relation to characteristics of the particular ore to be treated.