Original EA Amendment

memo To:

Simon Drummond (Hydrobiology)

From:

Peter Papa

CC:

Peter Mellor, Malcolm Paterson, Putri Leony

Date:

25/01/2023

Re:

Mt Morgan Hydrobiology – Total metals and other parameters in the final tailings (HYD-02)

This technical memo presents the Mt Morgan lab test results showing the total metals and other parameters in the final tailings .

1) Introduction There have been several phases of laboratory bench-scale testing where Mt Morgan tailing materials have undergone RIL/CIL under various test conditions tests to optimize gold recovery. The following Phase 4 test result has been presented below (ie; Mundic Test MU4_D), since a full ICP analysis was done on the initial feed solids and final RIL tailing solids for this test. 2) Test Results The tailings material was first ground to the target size of 80% passing 50 microns and then slurried to 40% w/w solids. Cyanide and resin were added for resin-in-leach (3 stages of resin-in-leach were completed). Slurry samples were taken during each of these steps and filtered. ICP analyses were conducted on the resulting solid and solution samples. The following table summarises the test parameters:

Units

TEST MU4_D (Mundic tailings material)

Test Parameters Composite used

- -

D4 Bulk #2 composite

Water used for slurrying

deionised water

Grind size, P80

microns grams % w/w

50

Initial solids weight % solids in the slurry

2,006

40%

Initial NaCN concentration

mg/L

2,000

Air/Oxygen Sparging Contact times Step 1: Cyanide leach Step 2: RIL contact #1 Step 3: RIL contact #2 Step 4: RIL contact #3

-

Oxygen

hr hr hr hr

0 6 4

13

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