Ministry of Higher Education and Scientific Research

Dept. of Production Engineering and Metallurgical

Branch: Mining and Extractive metallurgy
_____________________________________________________________________________________

Lap Report

Thermal Extraction of copper

Done by:
Noor Ali Ghayeb

1
 Ministry of Higher Education and Scientific Research
Dept. of Production Engineering and Metallurgical
Branch: Mining and Extractive metallurgy
_____________________________________________________________________________________
Introduction:
Pure copper metal is mostly produced from these ores by concentration, smelting,
and refining. About 80% of the world's copper-from-ore is produced by
concentration/smelting/ refining of sulfide ores. The other 20% is produced by heap
leaching/solvent extraction/electrowinning of oxide, and chalcocite ores.
Copper may be found in a variety of minerals, including chalcocite, chalcopyrite,
bornite, cuprite, malachite, and azurite. It can be found in seaweed ashes, many marine
corals, human liver, and many mollusks and arthropods. Copper metal occurs naturally,
although minerals such as chalcopyrite and bornite are by far the most abundant
sources.
Smelting, leaching, and electrolysis are used to extract copper from these ores and
minerals. Chile, Peru, and China are the three biggest copper-producing countries.
It is found in both its native and combined states. The principal copper ores are:
(I) Copper glance; Cu2S
(ii) Copper pyrites; CuFeS2
(iii) Malachite; Cu (OH)2CuCO3
(iv) Cuprite or (Rubby copper); Cu2O
(v) Azurite; 2CuCO3.Cu(OH)2
Today, chalcopyrite (CuFeS2) is the most frequent source of copper ore, accounting for
around fifty percent of copper production.

Extraction of Copper:
Copper is extracted from its ore by a series of procedures, including mining,
crushing, heating, chemically isolating impurities, refining, and purifying. Creating
useful items from raw resources like copper ore requires a lengthy process but is
possible with careful preparation and attention to detail. Understanding how this
adaptable metal is harvested will help us comprehend exactly how significant this
resource is, given its wide range of historical and contemporary use. Typically, there
are three key phases involved in the extraction of copper from ore. The first phase,
mineral processing, is to release the copper minerals and remove waste elements,
such as alumina, limestone, pyrite, and silica, in order to concentrate the copper
minerals and other nonferrous minerals of value into a product containing between

2
 Ministry of Higher Education and Scientific Research
Dept. of Production Engineering and Metallurgical
Branch: Mining and Extractive metallurgy
_____________________________________________________________________________________
20 and 30 percent copper. The second phase, which may involve smelting or
leaching, eliminates a significant amount of impurities components, particularly iron
and sulfur in the case of sulfide ores. The final process, refining, eliminates all traces
of impurities and yields a copper product with a purity of 99.99 percent. remove
waste elements, such as alumina, limestone, pyrite, and silica, in order to
concentrate the copper minerals and other nonferrous minerals of value into a
product containing between 20 and 30 percent copper.

The second phase, which may involve smelting or leaching, eliminates a

significant amount of impurities components, particularly iron and sulfur in the
case of sulfide ores. The final process, refining, eliminates all traces of impurities
and yields a copper product with a purity of 99.99 percent (Fig.1).

Fig.1

3
 Ministry of Higher Education and Scientific Research
Dept. of Production Engineering and Metallurgical
Branch: Mining and Extractive metallurgy
_____________________________________________________________________________________
Concentration of copper Ore:
The ore is crushed into a fine powder and a suspension is created in water. To
this are added, Collectors and Froth Stabilizers. Collectors (pine oils, fatty acids etc.)
increase the non-wettability of the metal part of the ore and allow it to form froth
and Froth Stabilizers (cresols, aniline etc.) sustain the froth. The oil wets the metal
and the water wets the gangue. Paddles and air constantly stir up the suspension to
create the froth. This frothy metal is skimmed off the top and dried to recover the
metal (Fig.2).

Fig.2

4
 Ministry of Higher Education and Scientific Research
Dept. of Production Engineering and Metallurgical
Branch: Mining and Extractive metallurgy
_____________________________________________________________________________________
Roasting:
The concentrated ore is then roasted in the furnace in the presence of oxygen.
During roasting sulfur, arsenic, antimony are converted into oxides and are removed.

2CuFeS2 + O2 → Cu2S + 2FeS + SO2

S + O2 → SO2
4As + 302 → AS2O3
4Sb + 3O2 → 2Sb2O3
Cuprous sulfide and ferrous sulfide are further oxidized into their oxides.
2Cu2S + 302 → 2Cu2O + 2SO2
2FeS + 302 → 2FeO + 2SO2

Fig.3

5
 Ministry of Higher Education and Scientific Research
Dept. of Production Engineering and Metallurgical
Branch: Mining and Extractive metallurgy
_____________________________________________________________________________________
Objectives of roasting:
• Remove part of the sulphur.
• Convert iron sulphides into iron oxide and iron sulphate to facilitate removal
during smelting.
• To pre-heat the concentrate to reduce amount of energy needed by the
smelter.

Smelting:
Roasted ore is then mixed with coke and sand and is fed into a blast furnace. Hot
air converts FeO to iron silicate (FeSiO3).

FeO + SiO2 → FeSiO3 (Slag)

Cu2O + FeS → Cu2S + FeO
Slag floats over the molten matte of copper (Fig.4).

Fig.4

6
 Ministry of Higher Education and Scientific Research
Dept. of Production Engineering and Metallurgical
Branch: Mining and Extractive metallurgy
_____________________________________________________________________________________
Bessemerization:
Matte contains Cu₂S and some unreacted FeO along with silica as impurity. It is
converted into copper in a special furnace which is known as "Bessemer converter"
(Fig.5).
When air is blown through the matte, the following reactions take place:

2Cu2S + 3O2 2Cu2O + 2SO2

2Cu2O + Cu2S → 6Cu + SO2
2FeS + 3O2 → 2FeO + 2SO2
FeO + SiO2 → FeSiO3

The copper so obtained is called "Blister copper" because, as it solidifies, SO2

hidden in it escapes out producing blister on its surface.

Fig.5

7
 Ministry of Higher Education and Scientific Research
Dept. of Production Engineering and Metallurgical
Branch: Mining and Extractive metallurgy
_____________________________________________________________________________________
Electrolytic refining:
This is the last phase in the pyrometallurgical processing as well as the
hydrometallurgical processing.
• During the electrolytic process, copper anodes and starting sheets are
submerged in an electrolytic solution that consists of copper sulfate and
sulfuric acid. This solution is known as an electrolyte.
• Copper, which originates from the positively charged anode, is deposited in a
pure form on the negatively charged beginning sheet, which functions as the
cathode, as a result of an electric current being run through the solution.
• The anode slimes, which include trace contaminants like as precious metals,
are found near the bottom of the cell and are processed further from there.
• Copper in solution that was produced by a hydrometallurgical process may be
recovered in an electrolytic cell that is analogous to this one by utilizing lead
as the anode. In this case, the electric current takes the copper out of solution
rather than removing it from the anode so that it may be deposited on a cathode
starting sheet (when the metal is plated from solution in this manner, the
process is known as electrowinning).
• Both of these techniques have the ability to produce cathode copper with a
purity that is greater than 99.9 percent.

8
 Ministry of Higher Education and Scientific Research
Dept. of Production Engineering and Metallurgical
Branch: Mining and Extractive metallurgy
_____________________________________________________________________________________

At anode: Cu – 2e¯ → Cu2+

At Cathode: Cu2+ + 2e → Cu

Zinc, nickel, iron, and other contaminants are accumulated as anode mud beneath
the anode.
Long-term exposure of copper pyrites to air and precipitation produces a diluted
solution of copper sulphate. The addition of scrap iron can precipitate copper from
this solution. The product is then refined electrolytically.

Q1/ In roasting process of copper extraction write the chemical term

of partial and completely oxidation?
In the roasting process of copper extraction, the chemical term for partial
oxidation is the conversion of copper sulfide (Cu2S) to copper oxide (Cu2O) and
sulfur dioxide (SO2). The chemical equation for this partial oxidation reaction is:

2Cu2S + 3O2 -> 2Cu2O + 2SO2

On the other hand, the chemical term for complete oxidation in the roasting
process would involve the conversion of copper sulfide (Cu2S) to copper oxide
(CuO) and sulfur dioxide (SO2). The chemical equation for this complete oxidation
reaction is:

2Cu2S + 4O2 -> 2CuO + 4SO2

9
 Ministry of Higher Education and Scientific Research
Dept. of Production Engineering and Metallurgical
Branch: Mining and Extractive metallurgy
_____________________________________________________________________________________
Q2/ How can we make use of the SO2 gas produced in roasting?

SO2 gas is commonly used in the production of copper as it helps in the extraction
of copper from its ores through a process called smelting. When copper ores are
heated in the presence of SO2 gas, the sulfur in the ore combines with the oxygen in
the air to form sulfur dioxide gas. This reaction helps to remove impurities such as
iron and sulfur from the copper ore, leaving behind a purer form of copper.
Additionally, SO2 gas can also be used to produce sulfuric acid, which is a key
component in the leaching process to extract copper from low-grade ores. Overall,
the presence of SO2 gas in the production of copper helps to improve the efficiency
and purity of the final copper product.

Q3/ What are the categories of roasting and smelting reactions?

The categories of roasting reactions include:

1. Oxidation reactions: These reactions involve the addition of oxygen to the metal
ore to form metal oxides.

2. Sulfation reactions: These reactions involve the addition of sulfur to the metal ore
to form metal sulfides.

3. Chlorination reactions: These reactions involve the addition of chlorine to the

metal ore to form metal chlorides.

The categories of smelting reactions include:

1. Reduction reactions: These reactions involve the removal of oxygen from the
metal oxide to obtain the pure metal.

2. Carbon reduction reactions: These reactions involve the use of carbon as a

reducing agent to extract the metal from its oxide form.

3. Electrolytic reduction reactions: These reactions involve the use of electricity to

reduce the metal oxide and extract the pure metal.

10
 Ministry of Higher Education and Scientific Research
Dept. of Production Engineering and Metallurgical
Branch: Mining and Extractive metallurgy
_____________________________________________________________________________________

Q4/ What are the benefit of the silica in smelting process?

Silica acts as an acidic flux during the metallurgy of copper It reacts with the
impurities of iron and form slag. FeS is present is the form of impurity with copper
sulphide ore.

2FeSGangue+3O2→2FeO+2SO2
FeOGangue+SiO2Flux→FeSiO3IronsilicateSlag

The role of silica in the metallurgy of copper is to remove the iron oxide obtained
during the process of roasting as 'slag'. If the sulphide ore of copper contains iron,
then silica SiO2 is added as flux before roasting. Then, FeO combines with silica to
form iron silicate, FeSiO3 (slag).

Q5/ How can we remove the iron from the matte in copper extraction?
In copper extraction, iron can be removed from the matte by a process called
slagging. This involves adding a flux, such as silica or limestone, to the matte in a
furnace. The flux reacts with the iron in the matte to form a slag, which can then be
separated from the copper. This helps to purify the copper and remove impurities
like iron.

Q6/ Write the chemical term that describes the copper production?

11
 Ministry of Higher Education and Scientific Research
Dept. of Production Engineering and Metallurgical
Branch: Mining and Extractive metallurgy
_____________________________________________________________________________________

References

https://www.sciencedirect.com/book/9780080967899/extractive-metallurgy-of-
copper#:~:text=Pure%20copper%20metal%20is%20mostly,of%20oxide%2C%20a
nd%20chalcocite%20ores.

Metallurgy of copper | PPT (slideshare.net)

Extraction of Copper: Detailed Process (scienceinfo.com)

Extraction Of Copper | Mining, Concentration, Smelting | Chemistry | Byju's

(byjus.com)

12