48
S. Nicol et al.
0
20
40
60
80
100
0
2 0
4 0
6 0
8 0
% Remaining in Slag
Reduction time (min)
Pb
Sn
0
20
40
60
80
100
0.0
2.0
4.0
6.0
8.0
10.0
% Remaining in Slag
Methane Injection (g/100 g of slag)
Pb
Sn
Fig. 4 Reduction of lead with methane injection with respect to time and quantity injected
calculated for the off-gas from the CO/CO 2 reaction couple was more oxidizing than
the Fe/FeO reaction couple. This suggests that the dominant reaction after 5 mins
of reduction or 0.6 g CH 4 /100 g of slag, consuming the majority of the methane, is
the reduction of Fe
2+ in the slag to form an iron phase. This is represented by the
reaction;
3 FeO (l) + CH 4(g) → 3 Fe (s) + CO (g) + 2 H 2 O (g)
This suggests that approximately 40% of the lead in the slag can be recovered
prior to the formation of an iron phase. To recover the majority of the lead present
in the slag, significant co-reduction of iron is required.
An industrial process using methane to reduce PbO dissolved in the slag will
require significant methane addition due to the reduction of iron. Additionally, the