Laterite Leach Tests

ANSTO Minerals Report C1206 to Lagoon Creek Resources – Westmoreland Deposits
(iii) Effect of ORP
The effect of oxidation potential is shown in Figure 4.10 for Junnagunna and Figure 4.11 for
Redtree. In both cases, similar final uranium extraction results were achieved for leaching at
ORP levels of 500-550 mV. Uranium extraction decreased when leaching at 450 mV.
Addition of 1.0 g/L ferric ion at 500 had a slight impact on the rate of extraction, but there
was little difference after 12 h. A similar result was achieved by leaching at 550 mV, and this
approach would be preferred to adding iron.
U Extraction (%)
100
95
90
85
80
75
70
65
60
0 5 10 15 20 25
Time (h)
550 mV (LC5 C) 500 mV and ferric (LC8 B) 500 mV (LC3 A) 450 mV (LC6 A)
FIGURE 4.10 Effect of ORP on the Leaching of Junnagunna Composite
U Extraction (%)
100
95
90
85
80
75
70
65
60
0 5 10 15 20 25
Time (h)
550 mV (LC6 B) 500 mV and ferric (LC8 C) 500 mV (LC3 B) 450 mV (LC6 C)
FIGURE 4.11 Effect of ORP on the Leaching of Redtree Composite
28