Mining Intelligence and News
Australia

Mackay Project

Click for more information

Categories

Summary

Mine TypeSurface
Study CompletedFeasibility
StagePermitting
Commodities
  • Potassium
  • Potash
Mining Method
  • Brine mining
Mine Life... Lock
SnapshotThe Mackay Potash Project is located on Lake Mackay in Western Australia, the largest undeveloped potash-bearing salt lake in the world. The lake contains significant volumes of brine with dissolved potassium and sulphur, suitable for producing high-grade, water-soluble organic Sulphate of Potash (SOP) fertiliser.

The 2020 Definitive Feasibility Study, supported by further process flowsheet testing, established the project’s technical and economic viability.

Western Australian State environmental approval was granted in January 2025, with the Minister for Environment issuing a Ministerial Statement under Part IV of the Environmental Protection Act 1986 (WA). The Commonwealth (DCCEEW) is reviewing the EPA’s assessment and, as of 25 February 2025, has requested outcomes of Agrimin’s Strategic Review before proceeding. The review began in February 2025, with key outcomes targeted for Q4 2025.

Owners

SourceSource
CompanyInterestOwnership
Agrimin Ltd. 100 % Indirect
The Mackay Potash project is held by Agrimin Potash Pty Ltd., a 100% owned subsidiary of Agrimin Ltd.

Contractors

Lock

- subscription is required.

Deposit type

  • Brine
  • Evaporite
  • Sediment-hosted

Summary:

Lake Mackay’s hydrogeological setting and favourable brine chemistry provide important attributes that support the development of a globally significant SOP operation. Lake Mackay hosts the largest SOP deposit in Australia and covers an area of approximately 3,500km2.

Lake Mackay is a brine-hosted potash deposit in a closed basin, salt lake setting. The Mineral Resource is based on the dimensions of the lakebed sediments, the variations in porosity (void space) and the potassium grade within the groundwater.

The drainable porosity (or specific yield) Mineral Resource contains 123Mt of SOP to a maximum depth of 211m. This drainable porosity Mineral Resource represents the static free-draining portion of the total porosity Mineral Resource prior to extraction.

There is a high level of confidence in the geological model for the project. The geology is simple, with brine-hosted in flat lying, relatively uniform, lakebed sediments.

Geology has been used to separate the deposit into different layers for the resource estimate. The upper sandy layer is more porous, beneath which there is a less porous unit overlying the lower clays that are again less porous, prior to reaching the coarser LZ3 sediments.

Within the upper zone (UZ) the lakebed sediments are further separated into top and bottom sub-horizons labelled as UZT and UZB.

The lower zone (LZ) sediments are separated into three sub-horizons labelled as LZ1, LZ2 and LZ3.

These sub-horizon divisions were introduced on account of subtle changes in lithostratigraphy with increasing depth from surface.

Lake sediments are saturated in brine below 0.5m depth from surface which represents the average brine level during the dry season across the lakebed.

A basement surface has been identified from drilling and geophysics, limiting the vertical extent of the lake sediments above. Lakebed sediments extend to a drilling depth of 150m where a basal paleochannel unit has been identified.

The paleochannel is incised into the basement to a maximum depth of 211m. Beyond the extents of the paleochannel the basement surface rises gently towards the east to a depth of between 11m and 25m below surface in the shallowest parts.

Islands are situated on the lakebed surface. These low relief islands (elevation from 362m to 370m) are interpreted to be aeolian in origin and are not included as part of the Mineral Resource estimate.

Sedimentary processes affect the continuity of geology, whereas the concentration of potassium and other elements in the brine is related to water inflows, evaporation and brine evolution in the salt lake.

Dimensions
The top of the resource is defined by the surface of the lakebed and extends below islands at the same elevation between 361m and 362m (AMSL). The base of the resource is defined by the basements surface that varies in depth from 211m maximum to between 11m and 25m below lakebed surface. The resource remains open laterally outside of the Company’s tenements off the lake (where it is covered by sand dunes) and at depth.

Reserves

Lock

- subscription is required.

Mining Methods

Lock

- subscription is required.

Heavy Mobile Equipment

Fleet data has not been reported.

Comminution

Crushers and Mills

Milling equipment has not been reported.

Processing

Lock

- subscription is required.

Commodity Production

Targeted SOP product specifications include >52% K2O.
CommodityProductUnitsAvg. AnnualLOM
Sulfate of potash (SOP) Crystals kt 45021,600

Operational metrics

Metrics
Annual processing capacity  ....  Subscribe
Annual brine extraction  ....  Subscribe
* According to 2020 study.

Production Costs

CommodityUnitsAverage
Site cash costs (produced) Sulfate of potash (SOP) USD  ....  Subscribe
Cash costs Sulfate of potash (SOP) USD  ....  Subscribe
All-in sustaining costs (AISC) Sulfate of potash (SOP) USD  ....  Subscribe
Assumed price Sulfate of potash (SOP) USD  ....  Subscribe
* According to 2020 study / presentation.

Project Costs

MetricsUnitsLOM Total
Pre-Production capital costs $M USD  ......  Subscribe
EBITDA (LOM) $M USD  ......  Subscribe
After-tax Cash Flow (LOM) $M USD  ......  Subscribe
Pre-tax NPV @ 8% $M USD  ......  Subscribe
After-tax NPV @ 8% $M USD  ......  Subscribe
Pre-tax IRR, %  ......  Subscribe
After-tax IRR, %  ......  Subscribe
Pre-tax payback period, years  ......  Subscribe
After-tax payback period, years  ......  Subscribe

Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Oct 25, 2025

Workforce

Total WorkforceYear
...... Subscription required 2020

Aerial view:

Lock

- subscription is required.