Laterite Leach Tests

ANSTO Minerals Report C1206 to Lagoon Creek Resources – Westmoreland Deposits v
• 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.
Settling Tests
Preliminary settling tests on Junnagunna and Redtree leach slurries at a grind of P80 = 250 µm
showed that the ores had similar settling properties. The preliminary flocculant and thickener
requirements indicate that solid/liquid separation by settling would be applicable. Further
optimisation was carried out in the bulk leach test work phase.
Unleached Uranium
The residual uranium minerals in the leach residues from Junnagunna, Redtree and Jack ores
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. The uranium minerals were almost always enclosed in quartz
particles. Various amounts of arsenic were detected in most uranium minerals.
The major findings from the SEM examination were:
• Coffinite and a uranium phosphate similar in composition to phosphuranylite were
found in all residues. Uraninite/pitchblende, uraniferous zircon and a uranium
phosphate similar in composition to autunite were detected only in the residues of the
Redtree and Jack samples;
• The uranium bearing minerals in the residues of Junnagunna and Redtree were
enclosed within quartz, with the one exception of coffinite intimately intergrown
with zircon in Redtree. They did not appear altered by leaching. It is likely that the
acid solution could not penetrate the enclosing quartz, since no liberated or partially
exposed uranium minerals were found. The coffinite intimately intergrown with
zircon appeared to be refractory to the leaching conditions employed;
• The uranium phosphates in the residue of Jack ore were only partially dissolved,
when they were exposed to the leach liquor. Their solubility was limited under the
test conditions. The other uranium minerals in this residue appeared to be soluble
under the test conditions, since they were detected only as inclusions in quartz.
Moreover, a uraninite/pitchblende grain and a uraniferous zircon grain, which were
enclosed in quartz, were partially dissolved. Their dissolution was limited by the
reduced permeability of the quartz particles.
Sizing of head and leach residue for Junnagunna and Redtree ores showed that high
extractions were obtained for all size fractions, with extraction decreasing slightly in the three