COPPER LEACH FROM BLACK COPPER MINERALS Ma. Cecilia Hernández, Oscar Benavente, Evelyn Melo & Damián Núñez Universidad Católica del Norte, Chile Yuri Zepeda Lomas Bayas Mining Company, Xstrata Copper
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COPPER LEACH FROM BLACK COPPER MINERALS
Ma. Cecilia Hernández, Oscar Benavente, Evelyn Melo & Damián Núñez
Universidad Católica del Norte, Chile
Yuri Zepeda
Lomas Bayas Mining Company, Xstrata Copper
Table of contents
• Project description
• Objectives
• Methodology
• Discussion
• Conclusion
Project descriptionThis project is being carried out by a joint between the
Geology and Metallurgical Engineering departments at the
Universidad Católica del Norte and Compañía Minera Xstrata-
Lomas Bayas, Chile and CORFO INNOVA program.
“Geometallurgical Modelling and Design of a Specific
Process for the Recuperation of Ores with Black Copper
Contents” (08CM01-09) ”
Black copper?
Copper wad
CuO·MnO2·7H2O
Copper pitch
(MnO(OH)CuSiO2·nH2O
Cu (1 – 54 %), Si, Mn, Fe and Al
Traces ofCa, Na, K, Mg, S, P, Cl, Mo, Co, Ni,
As, Zn, Pb, U y V
Copper source
Resources associated with black copper ores are left
without treatment in leach pads and dumps as residues.
Becoming a source of interest, due to they are located in
the existing mines facilities., and represent extra resources
possible to be recovered, increasing and/or extend
productive activity.
Lomas Bayas operates with a head grade of 0.33% total
copper, of which 0.26% is soluble copper and 0.07% is
insoluble. Mineralogical analyses estimate that 30% of
insoluble copper corresponds to black coppers.
There are few studies related with the treatment of black copper
minerals. However, their chemical and physic characteristics
make them similar in their metallurgical behaviour of marine
polymetallic nodules and manganese minerals.
Manganese minerals (MnO2) and marine nodules with Mn/Cu
content are stable in acid or alkaline oxidizing conditions. The
extraction of manganese can take place through sulphuric acid
medium in reductive conditions, incorporating SO2, oxalic acid,
hydrogen peroxide, iron sulphate, direct reduced iron or through
the incorporation of pyrite in a hydrochloric acid media
There is a study of copper dissolution from copper wad mixed
with secondary sulphurs in acid media.
Objectives
Evaluate the effects of different methods of acid leaching on
the dissolution of copper from black copper minerals.
Specific
• Black copper pure samples characterization from two different
ore bodies .
• Metallurgical behavior of black copper in different leach
environments.
Methodology
Two pure black copper samples were collected from the Lomas Bayas mine
(Xstrata) and Mina Sur (Codelco). The samples are reduce in size reaching
a granulometry less than 295 μm.
mineralStandard acidic condition
Temperature 25 °C
Granulometry 100% <295 μm .
Mass 4,8 g
Leaching time 240 min
Sampling time 15, 30, 60, 120, 240 min
Concentration H+ 10 g/L de H2SO4
pH 0,90 Aprox.
Agitation 300 rpm
Oxidant condition
Oxygen 1 L/min
Reductant condition
Ferrous sulfate 1,2 g
SO2 1 L/min
Methodology of Leaching test
Sample Cu(T) (%) Fe(T) (%) Mn(T) (%)
M S 22,8 0,36 8,68
LB 2,59 2,56 2,48
Result and DiscussionClassification of mineral samples
The samples from Mina Sur (MS) and Lomas Bayas (LB) are analysed using
inductively coupled plasma atomic emission spectroscopy (ICP-AES) and
diffraction of X-rays (DRX), electronic microscope (SEM) and Qemscan
microscope.
Chemical composition of black oxide samples.
The DRX analysis of the MS and LB
samples generate spectrums with a
high noise level, characteristic of low
crystallinity. By performing an analysis
of the low concentration compounds,
the presence of copper silicates and
crystalline types of manganese can be
detected
Characterization of mineral samplesÓxido Negro Mina Sur
Operations: Import
Muestra Oxido Negro - File: OxNegro-1A.raw - Type: 2Th/Th locked - Start: 3.000 ° - End: 70.000 ° - Step: 0.020 ° - Step time: 1. s - Temp.: 25 °C (Room) - Time Started: 7 s - 2-Theta: 3.000 ° -
Lin
(Cou
nts)
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2-Theta - Scale
3 10 20 30 40 50 60 70
In the case of the MS sample,
birnessite K,46Mn1,54Mn,46O4(H2O),
plancheite Cu8(Si4O11)2(OH)4H2O,
crednerite CuMnO2, pyrite, Mn(OH)2
lithiodionite CuNaKSi4O10
for the LB samplealbite NaAlSi3O8,
bixbyite FeMnO3
clorite (Mg,Fe)6(Si,Al)4O10(OH)8,
quartz SiO2, illite (K,H3O)Al2Si3AlO10(OH)2
microcline KAlSi3O8, Molysite, FeCl3montmorillonite
Na0.3(Al,Mg)2Si4O10(OH)2*nH2O
natrojarosite, NaFe3(SO4)2(OH)6
nontronite Na0.3Fe2Si4O10(OH)2*4H2O.
The classification by electronic
microscope SEM/EDS of sample
LB show the presence of oxidized
minerals of Si, Mn, Cu, Fe..
SEM/EDS of LB sample
Characterization of mineral samples
Element O Mg Al Si S K Ca Ti Mn Fe Cu Mo
LB 51.9 0.93 8.31 23.6 0.3 3.38 0.56 0.35 3.77 3.41 3.02 0.48
Percentage of elements present in samples from Lomas Bayas.
SEM analysis of the LB sample
permitting a qualitative analysis of
the elements present and also the
associations between them.
It was possible to determine the
presence of oxidized phases
formed by the association of Cu-
Mn-Fe and K, as well as quartz and
oxides of Fe.
SEM Image of sample LB, x300.
(1) areas of association Cu-Mn-Fe-K-O
(2) Si-O
(3) Fe-O (4) Al-Fe-O.
Characterization of mineral samples
Mineralogical Analysis via Qemscan of
samples MS and LB
The analysis by Qemscan microscope
shows the black coppers present in the
samples are copper wad type.
In the MS sample, more than 90%
corresponds to copper minerals. The
10% of gangue is principally composed
of feldspar and kaolinite.
The LB sample is about 20% copper
minerals, and the gangue is mainly
quartz, feldspar, muscovite/sericite and
kaolinite.
Characterization of mineral samples
Mineralogy of copper types in samples MS
and LB.
The distribution of copper types in
each mineral sample can be
observed.
In sample MS, 70% of copper types
are high or low-content copper wad,
while the remaining 30% is mainly
chrysocolla/dioptase.
In LB sample 95 % of the copper
present is low-content copper wad.
Characterization of mineral samples
Leaching test
0%
20%
40%
60%
80%
100%
0 30 60 90 120 150 180 210 240
Extr
acci
ón
, %
Tiempo de Lixiviación, min
Cu Std.
Cu Ox
Cu FeSO4
Cu SO2
Copper and Manganese extraction under different leach condition as a function of
time from MS sample
0%
20%
40%
60%
80%
100%
0 30 60 90 120 150 180 210 240
Extr
acci
ón
, %
Tiempo de Lixiviación, min
Mn Std.
Mn Ox.
Mn FeSO4
Mn SO2
0%
20%
40%
60%
80%
100%
0 30 60 90 120 150 180 210 240
Extr
acci
ón
, %
Tiempo de Lixiviación, min
Cu Std.
Cu Ox
Cu FeSO4
Cu SO2
0%
20%
40%
60%
80%
100%
0 30 60 90 120 150 180 210 240
Extr
acci
ón
, %
Tiempo de Lixiviación, min
Mn Std.
Mn Ox.
Mn FeSO4
Mn SO2
Copper and Manganese extraction under different leach condition as a function of
time from LB sample
Leaching test
CONCLUSIONS
The minerals MS and LB present similar behaviour in leaching
under all studied conditions, and both samples can be classified as
copper wad.
The standard leaching condition produces a lower dissolution of
manganese (2%) and dissolution of copper in the range of 70%.
This condition represents the lowest extraction achieved.
The results obtained from leaching in oxidant conditions are similar
to those from the standard condition, reaching 2% manganese and
73% copper extraction. The addition of an oxidant agent does not
improve the dissolution of black coppers.
CONCLUSIONS
The addition of FeSO4 or SO2 (potential reducing agents) favours
the dissolution of manganese, which increases the extraction of
copper.
The SO2 addition produces a copper extraction of 86.2% and
75.5% for MS and LB respectively, which represent a 15% increase
of in the quantity of copper extracted beside the standard
conditions.
ACKNOWLEDGEMENTS
The authors are grateful for the financial support supplied by the CORFO
INNOVA program and Xstrata Lomas Bayas Mining Company.
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