Laterite Leach Tests

ANSTO Minerals Report C1206 to Lagoon Creek Resources – Westmoreland Deposits
• The Redtree ore contained about 6 times the level of arsenic than the Junnagunna ore,
hence the much higher arsenic levels in solutution. For the Redtree ore the concentrations
of elements in solution generally decreased in the order:
Fe>Al>Si>Ca≈As≈K≈Mg>P
The following general impacts of leach variables were evident:
• The concentrations of all elements, except K, increased with decreasing pH;
• The concentrations of all elements, except Ca and P, increased with increasing
temperature;
• Grind size had little impact on the concentrations of gangue elements in solution;
• The concentrations of all elements increased with increased leaching time;
• The concentrations of all elements were marginally greater in the Junnagunna liquor
compared to Redtree, which was reflected in the acid requirement;
• None of the gangue element concentrations in solutions would be expected to result in
downstream processing problems. The Si concentrations were typical of many of the
acid uranium leach liquors that are currently being processed, but noting that it is the
form of the silica, rather than the total concentration, that results in silica problems;
• Ferric concentrations were reasonably high, which is a positive for leaching, but will
result in some degree of iron loading if IX is used for uranium recovery;
• The concentrations of all ions, except for P and Ca, were considerably less in the Jack
liquors, as reflected by the very low acid requirement.
• The concentrations of the minor elements that could report to final product as penalty
elements, eg Mo, V, Zr, were low. Arsenic was present at 40-180 mg/L for Redtree
ore and may warrant additional attention in regards to waste water treatment.
However, the arsenic levels in solution when the Redtree was combined with
Junnagunna and Jack was lower at ~100 mg/L. It is likely that the vast majority of
arsenic will precipitate as ferric arsenate during a neutralisation process. However, this
still has to be proven.
8.1.6 Unleached Uranium
• The residual uranium minerals after leaching consisted of coffinite (U(SiO4)1-x(OH)4x),
uranium phosphate, probably phosphuranylite (KCa(H3O)3(UO2)7(PO4)4O4·8(H2O)),
and uraniferous zircon, where coffinite was the most common uranium mineral. They
were almost always enclosed in quartz particles. Various amounts of arsenic were
detected in most uranium minerals.
8.1.7 Bulk Leach
The bulk leach results corresponded well with the test on individual ores under the same or
similar conditions.
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