Mt Cattlin Annual Ore Resource and Reserve update at 30 June, 2023
Allkem Limited
Allkem Limited

Chart 1

Changes (Mt) in Ore Reserve reported March 2023 to June 2023
Changes (Mt) in Ore Reserve reported March 2023 to June 2023

Figure 4

NPV Sensitivity to Key Revenue and Cost Factor Variables
NPV Sensitivity to Key Revenue and Cost Factor Variables

Tantalum Standards

Tantalum Standards
Tantalum Standards

NW pegmatite core

NW pegmatite core
NW pegmatite core

BRISBANE, Australia, July 31, 2023 (GLOBE NEWSWIRE) -- Allkem Limited (ASX: AKE, “Allkem” or the “Company”) provides an Ore Reserve update for its Mt Cattlin operation in Western Australia.

KEY POINTS

  • Mineral Resource updated to reflect depletion due to mining since 31 Dec 2022 and modest increases due to adjustment to cut-off grade (0.3%) and new pit shell of USD 1,500.

  • The Ore Reserve and planned mining schedule suggests a projected Life-of-Mine for the next 4-5 years (2027-2028) via open pit mining methods.

  • The Ore Reserve has been updated to account for:

    • Mining depletion since the previous Reserve dated 31 March 2023

    • Adjustment to cut-off grade of 0.3% in the same pit shell design as modelled 31 March 2023

    • A correction to the previously stated Ore Reserve released 16 June 2023 which contained a modelling error.

  • The increasing waste/ore strip ratio at depth to access ore via open pit mining methods is being evaluated against an alternate underground mining option.

  • An underground Feasibility Study is expected to be delivered in CY24. It will enable a variety of scenarios to be modelled and will ensure an optimised future mining method is selected.

ORE RESERVE ESTIMATE

The Mt Cattlin Ore Reserve estimate is based on an updated Mineral Resource Estimate released on 17 April 2023. The Mineral Resource was updated after the completion of a major infill drilling program which successfully upgraded Inferred Mineral Resources.

Allkem has reviewed and updated the Mt Cattlin Ore Reserve (Table 1 below), incorporating infill drilling results from the 2NW deposit, depleted mined material and site stockpiles at 30 June 2023 and material to be mined after this date are presented in accordance with JORC (2012) Ore Reserve Reporting.

Table 1: Mt Cattlin Ore Reserve Update as at 30 June 2023

Classification

Location

Ore Tonnes
(Mt)

Grade Li2O (%)

Grade Ta2O5
(ppm)

Contained
Metal (‘000) t
Li
2O)

Contained
Metal (‘000) lbs
Ta
2O5

Proved

In-situ

0.2

0.9

120

1

45

Probable

In-situ

5.2

1.3

130

69

1,500

 

Stockpiles

1.8

0.8

95

13

396

 Total Ore Reserve

7.1

1.2

120

84

1,900

Notes: Ore Reserves mine designs were conducted on a 0.4% Li2O cut-ff grade and Ore Reserves are reported above a marginal cut-off grade of 0.3 % Li2O. Estimates have been rounded to a maximum of two significant figures, thus sum of columns may not equal.

A breakdown of the adjustments are shown in Table 2 and corresponding Chart 1 below.

Table 2: Changes (Mt) in Ore Reserve March 2023 to June 2023

Description

Balance

Grade Li2O (%)

Increase

 

Decrease

Ore Reserve March 31st 2023

7.8

1.2

-

 

-

Depletion

-0.4

1.3

-

-

0.4

Changes to un-mined open pit surface topography/adjustment for in pit tailings

-0.4

1.2

-

-

0.4

Marginal COG from 0.4% to 0.3%

0.1

0.4

0.1

 

-

Ore Reserve 30 June 2023

7.1

1.2

0.1

-

0.8

Chart 1: Changes (Mt) in Ore Reserve reported March 2023 to June 2023

Changes (Mt) in Ore Reserve reported March 2023 to June 2023
Changes (Mt) in Ore Reserve reported March 2023 to June 2023


Reserve Methodology

Pit optimisations have been carried out using a fixed spodumene concentrate sale price of US$1,500/t and an exchange rate of 0.7 USD:AUD. Whittle pit optimisation software has been used to identify the preferred pit shell on which the pit design was based.