9 - Electrometallurgy.pdf

Metallurgy

1. Electro-
metallurgy
! Oxidation – chemical reaction which
involves the loss of electrons
Fe
0
! Fe
2+
+ 2e
-

! Reduction – chemical reaction that
involves a gain in Electrons
Cu
2+
+ 2e
-
! Cu
0

Basic Terms:
! Anode – the site at which the oxidation
occurs
! Cathode – the site at which reduction or
deposition of the valuable metal occurs

! Electrolyte – the aqueous medium
through which ions move from one
electrode to another
Basic Terms:
1. Electrowinning
" electrolytic extraction process in which
cathodic reduction is used to recover the
valuable metal from the electrolyte which is
derived from a leaching process

anode 2H
2
O → 4H
+
+ O
2
+ 4e
-
cathode 2M
2+
+ 4e
-
→ 2M°

Types of
Electrometallurgical Processes

2. 2. Electrorefining
" the anodic reaction is a metal dissolution
reaction that is the reverse of the cathodic
reduction reaction

anode M → M
2+
+ 2e
-

cathode M
2+
+ 2e
-
→ M

Types of
Electrometallurgical Processes
Types of
Electrometallurgical Processes
3. Cementation
" Precipitation / deposition of a metal of higher
reduction potential to a metal of lower
reduction potential

Cu
2+
+ 2e
-

→ Cu
0
+0.34 V

Fe
0
→

Fe
2+
+ 2e
-

+0.44 V