Synthesis of Copper Oxy-chloride and Iron Oxide Pigments Using Leachaate From the Bioleaching of a Copper Sulphide Minerals Flotation Concentrate

7/29/2019 Synthesis of Copper Oxy-chloride and Iron Oxide Pigments Using Leachaate From the Bioleaching of a Copper Sulphide Minerals Flotation Concentrate

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Authors:

Carlos Souza, Luis Sobral, Dbora Monteiro,

Paula Nascimento, Gabriel Peixoto

Centro de Tecnologia Mineral - CETEM

Synthesis of copper oxy-chloride and iron oxide pigments

using leachate from the bioleaching of a copper sulphide

minerals flotation concentrate


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During the last and recent economic crisis the commodities

prices dropped down dramatically , which pushed the mining

sector to search for technological alternatives to produce

more cost effective final products.

In the copper mine, in particular, the idea was to treat the

leachate, out of the heap leaching process, to precipitate the

iron oxide pigment (FeOOH), widely used in the ceramic and

paint industries, followed by the precipitation of copper oxy-

chloride, also widely used agriculture pesticide .

Introduction


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Copper concentrate particle size distribution

Inner Diameter(mesh)

Particle Size(mm)

Retained Weight

Fraction

(%)

150 0.106 10.7

200 0.074 23.0

325 0.043 27.6

< 325 < 0.043 38.7

Copper content

chalcopyrite (CuFeS2) 70%

bornite (Cu5FeS4) 30%

Bioleaching test

- Support rock

- Microorganisms

Mesophiles Up to 40C

ModerateTermophiles ~40 - ~55C

ExtremoTermophiles ~55 - ~80C

-3mm +6mm


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Outline of the column bioleaching reaction system

Bioleaching test

pH

Eh

O2

CO2

Temperature

Nutrients

Cell Concentrao

Elements Analysis


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Fe3+/Fe2+ = 0.9

Liquor :

18.0 g/L of copper

3.18 g/L of total iron

[Fe3+] = 58.35%

1200 rpm

Experimental

OHFeHOHFe2

3

22

22222


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The filtrate pH was raised to 6.5 by adding 1mol/L sodium hydroxide solution (NaOH), in the

same stirred reactor, where copper hydroxide

was precipitated [Cu(OH)2], and further

separated from the aqueous phase containing,

essentially, sodium sulphate (Na2SO4)

Experimental

2424 )(2 OHCuSONaNaOHCuSO

OHCuClHClOHCu 222 22)(

NaClOHCuCuClNaOHCuCl 2)(.324 222


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Results and discussion

Synthetic pigment

aged for 24h at 50C

Commercial pigment

Natro-jarosite: NaFe3(SO4)2(OH)6

X-ray diffraction


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Synthesized iron oxide pigment, have particle size below 20 m, below 62% of 5

mm and 42% are below 2 m. While the commercialised pigment, by the leader

industry in the Brazilian market, 98% of the particles has size below 20 m, 94%below 5 m and 92% below 2 m

Particle Size Analysis


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Scanning Electron Microscopy

Synthetic pigment

aged for 24h at 50C

(nodular)

Commercial pigment

(Acicular)


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Conclusions

The iron oxide pigment obtained out of the leachate from the bioleaching

of a copper sulphides flotation concentrate, consisting mainly of

chalcopyrite (CuFeS2

) and bornite (Cu5

FeS4

), is considered as apotentially attractive way for recovering iron as an iron oxide pigment

without using organic reagents, as those used in solvent extraction

processes, despite of high selectivity for copper, also present considerable

flammability and toxicity risks.

The pigment obtained in this test work, in the above mentioned

experimental conditions, still have to be optimised so as to improve its

crystallinity, compared with the one commercialised in the Brazilian

market. The synthesized pigment showed particle size 94% below 20 m,

which can be used in the ceramic industry, in the production of special

bricks and cement or even as an adsorbent material.


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Conclusions

The copper oxy-chloride, a widely used agriculture pesticide with broad

spectrum for controlling of fungal diseases in several crops, mainly

horticulture and fruit production, may be obtained easily from the

remaining solution of the iron-base pigment precipitation process by

raising the pH of the copper chloride solution using sodium hydroxide. As

previously mentioned, the copper content of that salt produced in this

study was of 50.7%, which is, to some extent, within the range of those

commercialised in the market (from 30 to 50%).

Documents

Synthesis of Copper Oxy-chloride and Iron Oxide Pigments Using Leachaate From the Bioleaching of a Copper Sulphide Minerals Flotation Concentrate