Laterite Leach Tests

ANSTO Minerals Report C1206 to Lagoon Creek Resources – Westmoreland Deposits
Uranium Leach Residue Grade (ppm U3O8)
400
350
300
250
200
150
100
50
0
0 4 8 12 16 20 24
Leach Time (h)
Permanganate R
Pyrolusite R
Permanganate J
Pyrolusite J
FIGURE 4.18 Effect of Oxidant Type on Leach Residue Grade (base case)
4.2.5 Leaching of Jack Ore
As per the agreed work plan, only one leach test was initially carried out on Jack ore, under
the base case optimum conditions determined for the Junnagunna and Redtree. Base case
leaches for the three samples are compared in Table 4.9 and Figure 4.19. As seen in the
figure, the rate of decrease in the residue grade between 2-8 h for Jack ore was substantially
less than that of the other two samples. This result could be due to the very low ferric ion
concentration in the Jack leach liquor, also shown in Figure 4.19.
As the extraction was considerably less than obtained for the other samples, and unlike the
others, significantly less than the dilute leach result (see Table 4.9), additional tests were
undertaken in an effort to improve extraction. Results are shown in Table 4.10 and Figure
4.20. Addition of 1 g/L Fe, leaching at pH 1.2, and leaching at a finer grind of P80 = 150 µm at
pH 1.5 with addition of Fe, all increased the extraction from 87% for base case conditions to
91-91.5%, after 24 h.
Optimum conditions for the Jack sample would either be leaching at pH 1.2, with other
conditions at base case, or leaching at pH 1.5, with addition of 1 g/L Fe. Note that the latter
conditions may occur if Jack ore was blended with either Junnagunna or Redtree because of
the amount of iron dissolved from these ores. Further work is recommended to identify
conditions that could increase extraction from the Jack ore.
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