Stages of Hydrometallurgical Processes

Stages of Hydrometallurgical Processes
By
Walid Khalid Abdulkader
1
Content
• Introduction
• Process Stages
 Leaching
 Solution concentration and purification
 Metal recovery
• Hydrometallurgy Versus Pyrometallurgy

 Conclusion
• References
2
Introduction
• Hydrometallurgy is a metal processing technology

that uses a chemical process combining water,
oxygen or other substances in a pressurized or other
vessel to dissolve a metal from its ore, concentrate or
an intermediate product . Further processing is
required to produce high purity metal.[1]
3
Process Stages
• Hydrometallurgy is typically divided into three

general areas:
Leaching
Solution
concentration
and purification
Metal recovery
4
Process Stages
Figure 1: Basic unit processes in hydrometallurgy. [4]

5
Process Stages
• The most important operation in hydrometallurgy is

leaching of properly prepared raw material.[2]
• The most efficient leaching agents are acids, due to

their ability to leach both base and precious metals.
Generally, base metals are leached in nitric acid.[5]
6
Process Stages
The three basic leaching techniques are:
In-situ leaching
Heap leaching
Vat leaching
Agitation leaching
7
Process Stages
 Insitu leaching: In-situ leaching is concerned with the

dissolution of metal values from minerals present in the
undisturbed ore body in place.[4] suitable for low-grade ores [4]
cheaper than other techniques[4]
Figure2: Insitu leaching
8
Process Stages
 Heap leaching: ore is crushed & piled onto an artificial pad

and then solution is trickled on it.[9]
• A major advantage of heap leaching is the elimination of
expensive milling operations since the ore body need not be
crushed to sizes much smaller than 20 to 25 mm.[4]
Figure3: Heap Leaching 9

Process Stages
 Vat Leaching :The ore meant to be leached is loaded into vats

that are typically made of concrete. When leaching has been
completed, the residual solids are dugout of the vat and
replaced by a fresh batch of ore.[4]
Suitable for porous and sandy materials [4]
commonly used to extract gold and silver from ore [11]
10
Process Stages
• Agitation leaching :A process where the soil is

slurried with the extraction fluid for a period of time.
When equilibrium between the metal on the soils
surface and the metal contained by the solution is
approached, the solubilization of the metal in the soil
is slowed, and the extraction is considered to be
complete. [10]
11
Process Stages
Solution purification and concentration : This step usually

involves chemical separations.
removing undesirable impurities to

Purpose increase the metal concentration
• the solution purification can be stated to be achieved by

using any one or a combination of the following
processes[4] :
 ion exchange
carbon adsorption
solvent extraction
12
Process Stages
• Metal recovery: At this point, the metal needs to be

recovered from solution in the solid form. This is either
achieved chemically, or electrochemically.[9]
 Electrowinning: An electrochemical process for precipitating
metals from solution.[9]
The anode is made
out of a material
that will not easily
oxidise or dissolve,
such as lead or
titanium.[9]
Figure4:Electrowining process [4] 13

Hydrometallurgy Versus Pyrometallurgy
• Pyrometallurgy: Pyrometallurgy, or the use of heat

for the treatment, includes smelting and roasting. It
involves heating in a blast furnace at temperatures
above 1500°C to convert waste to a form that can be
refined.[6]
14
•A number of factors are causing a gradual but steady shift

away from the traditional processing routes.[7]
Figure5. Growing importance of Hydrometallurgy [7] 15

• Compared with pyrometallurgy, hydrometallurgical extraction

of metals from their ores is more attractive.
This attractiveness is attributed to:
economical environmental technical
reasons.[8]
16
• Factors such as low temperature processing; low

handling cost of leaching products and possibility of
treatment of low grade ores make leaching more
preferable than high temperature smelting.[8]
• In conventional pyrometallurgical smelting, sulphides

are burnt off, creating SO2 gas, which is released as
air emissions.With hydrometallurgy, there are no air
emissions. [1]
17
• However, some problems may arise during

hydrometallurgical operations. These include:
 difficulties in solid–liquid separation
 effect of impurities on the ease of purification
 The principal disadvantage of hydrometallurgical
operations is probably the process times required to
achieve high metal recovery since these processes
are often carried out at low temperatures compared
to pyrometallurgical processes.[8]
18
Conclusion
• Advantages of hydrometallurgy:
 Much more environmentally friendly than
pyrometallurgy.
 Compared to pyrometallurgy, only a fraction of the
gases liberated into the atmosphere.
 Low capital cost
 Ability of complex and low-grade ores extraction
19
conclusion
• Disadvantages of hydrometallurgy:
 Large amount of water used,  greater potential for
contamination.
 Difficulties in solid–liquid separation
 Impurities problems in purification process
 Times needed for high metal recovery
20
References
• [1] www.vale.com
• [2] Katarzyna OCHROMOWICZ ,Tomasz CHMIELEWSKI-Physicochem. Probl.
Miner. Process. 46(2011) 207-218 , July 2010
• [3] Chapter 82 - Metal Processing and Metal Working Industry
• [4] Chemical Metallurgy: Principles and Practice. Chiranjib Kumar Gupta
• [5] Željko Ka berović *, Marija Korać, Draga a Ivšić, Ves a Nikolić,Milisav
Ra itović , HYDROMETALLURGICAL PROCESS FOR EXTRACTION OFMETALS FROM
ELECTRONIC WASTE, Department of Metallurgical Engineering, Faculty of
Technology and Metallurgy, Belgrade, Serbia
• [6] F.C. Liew,Engineering Department,TES-AMM Singapore,April 2008
• [7] DREISINGER, D, Hydrometallurgical process development for complex
ores and concentrates. Hydrometallurgy Conference 2009, The Southern
African Institute of Mining and Metallurgy,2009.
21
References
• [8] M. Al-Harahsheh , S.W.Kingman, Microwave-assisted leaching—a review,

Hydrometallurgy Volume73,Issues 3-4,June 2004, Pages 189–203
• [9] Hydrometallurgy,Dr. yoozbashizade-Hossein, Industrial University Of Sharif
• [10] http://www.hydrometallurgy.metal.ntua.gr/Heap%20Leaching.htm
• [11] http://www.americhem.biz/_amprep/leaching.htm
22

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What are the main stages of hydrometallurgical processes?

What are the main stages of hydrometallurgical processes?

What are the different leaching techniques discussed?

What are the different leaching techniques discussed?

Stages of Hydrometallurgical Processes

Walid Khalid Abdulkader

• Hydrometallurgy Versus Pyrometallurgy

• Hydrometallurgy is a metal processing technology

• Hydrometallurgy is typically divided into three

Figure 1: Basic unit processes in hydrometallurgy. [4]

• The most important operation in hydrometallurgy is

• The most efficient leaching agents are acids, due to

The three basic leaching techniques are:

 Insitu leaching: In-situ leaching is concerned with the

cheaper than other techniques[4]

Figure2: Insitu leaching

 Heap leaching: ore is crushed & piled onto an artificial pad

Figure3: Heap Leaching 9

 Vat Leaching :The ore meant to be leached is loaded into vats

Suitable for porous and sandy materials [4]

commonly used to extract gold and silver from ore [11]

• Agitation leaching :A process where the soil is

Solution purification and concentration : This step usually

removing undesirable impurities to

• the solution purification can be stated to be achieved by

• Metal recovery: At this point, the metal needs to be

Figure4:Electrowining process [4] 13

• Pyrometallurgy: Pyrometallurgy, or the use of heat

•A number of factors are causing a gradual but steady shift

Figure5. Growing importance of Hydrometallurgy [7] 15

• Compared with pyrometallurgy, hydrometallurgical extraction

This attractiveness is attributed to:

economical environmental technical

• Factors such as low temperature processing; low

• In conventional pyrometallurgical smelting, sulphides

• However, some problems may arise during

• [8] M. Al-Harahsheh , S.W.Kingman, Microwave-assisted leaching—a review,

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