XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3441
shown in Figure 9. These results also show that the rate of
oxidation slows as the reaction proceeds, perhaps to reach-
ing an equilibrium prior to completion conversion.
Chmielewski and Charewicz (1984) also noted the devi-
ation from second order kinetics for their results, as shown
in Figure 10. The conditions for this data set are given in
Table 2. Chmielewski and Charewicz (1984) attributed this
deviation to a change from second order kinetics to a slow
reaction that is first order in ferrous ions. However, they did
not propose any mechanistic model of the reaction kinetics
to demonstrate how such a change might occur.
DISCUSSION
Kinetic Modelling
The kinetics of ferrous ion oxidation have been examined
by several authors, and several proposals have been made.
These are summarized in Table 3.
Most researchers have found that the reaction is close
to second order in ferrous ions and first order in oxygen.
Figure 8. A second-order plot of the concentration of ferrous ions in solution as a
function of the time spent in the batch reactor
Figure 9. The conversion of ferrous ions as a function of tie spent in the batch reactor.
Data reported by Chmielewski and Charewicz (1984)