AHK: ANSTO TEST RESULTS - 98-99% LREO EXTRACTION FROM SANDY M
Original announcement by asx on
- Company
- Ark Mines Ltd
- Ticker
- AHK
- Exchange
- ASX
- Region
- North Queensland
- Primary commodity
- Rare earths
- Secondary commodities
- Dysprosium, Yttrium
- Document categories
- Metallurgy
- Extracted
- 2026-10-08 01:32:03 UTC
Analysis by Minestarters Atlas
Atlas analysis published:
Minestarters Atlas analysis
Summary
Ark Mines reports successful scoping metallurgical testwork by ANSTO on monazite concentrate from the Sandy Mitchell project. The tests achieved 98-99% light rare earth extraction via acid bake and ~98% via caustic conversion, demonstrating processing flexibility.
Reasoning: The scoping metallurgical testwork demonstrates high recovery rates for light rare earths using conventional processing routes, providing significant de-risking for the project's flowsheet development.
Positive factors
- High light rare earth extraction (98-99%)
- Amenable to both acid bake and caustic conversion routes
- High phosphate removal (97%)
- Excellent monazite liberation (93%)
Negative factors
- Scoping-level results only
- Does not include monazite recovery from ore to concentrate
Facts used in scoring: 4
Classification and evidence
High Recoverypositive
Recovery at or above the exceptional band for the commodity and processing route.
Why it applies: LRE extraction achieved up to 99.6% via acid bake and 98% via caustic leach.
Evidence · text
“achieving high light rare earth extractions of 98% to 99%”
Mill Routeneutral
Processing via mill or concentrator (CIL, CIP, tank leach, flotation).
Why it applies: The primary testwork involved milled concentrate (P80 43um).
Evidence · text
“two on milled concentrate (P80 of 43μm)”
Gravity Routeneutral
Gravity separation forms a material part of the flowsheet.
Why it applies: the document describes a gravity route ("gravity")
Multi-Domain Testedpositive
Variability across ore domains (oxide, transition, fresh) has been addressed.
Why it applies: 3 distinct composites were tested
Extracted facts
Stored fact records: 4. Some facts used in scoring do not have a stored record.
Metallurgical Results (4)
acid bake and water leachSandy Mitchell · rare_earthsRecovery: 98 %Head Grade: 48.7Head Grade Unit: % TREOView all detailsHide details
Identity
- Project
- Sandy Mitchell
- Commodity
- rare_earths
- Region
- australia_qld
- Reported Region
- North Queensland
- Ticker
- AHK
Test Work
- Program Status
- scoping
- Test Type
- acid bake and water leach
- Processing Route
- acid bake and water leach
- Sample
- milled monazite concentrate (P80 43um), 1,100kg/t acid addition
- Grind P80
- 43 µm
Recovery
- Recovery
- 98 %
- Recovery Basis
- actual_test
- Head Grade
- 48.7
- Head Grade Unit
- % TREO
Lab
- Laboratory
- ANSTO
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-10-08T00:00:00.000Z
Reasoning: 98% recovery is strong for a scoping-level acid bake test.
Positive factors
- High recovery at standard acid addition
Evidence · text
“light rare earth (LRE) extraction from the milled concentrate increased from 98% at 1,100kg/t acid addition”
acid bake and water leachSandy Mitchell · rare_earthsRecovery: 99.6 %Head Grade: 48.7Head Grade Unit: % TREOView all detailsHide details
Identity
- Project
- Sandy Mitchell
- Commodity
- rare_earths
- Region
- australia_qld
- Reported Region
- North Queensland
- Ticker
- AHK
Test Work
- Program Status
- scoping
- Test Type
- acid bake and water leach
- Processing Route
- acid bake and water leach
- Sample
- milled monazite concentrate (P80 43um), 1,500kg/t acid addition
- Grind P80
- 43 µm
Recovery
- Recovery
- 99.6 %
- Recovery Basis
- actual_test
- Head Grade
- 48.7
- Head Grade Unit
- % TREO
Lab
- Laboratory
- ANSTO
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-10-08T00:00:00.000Z
Reasoning: 99.6% extraction is exceptional for this processing route.
Positive factors
- Near-total extraction of light rare earths
Evidence · text
“~99.6% at 1,500kg/t”
acid bake and water leachSandy Mitchell · rare_earthsRecovery: 95 %Head Grade: 48.7Head Grade Unit: % TREOView all detailsHide details
Identity
- Project
- Sandy Mitchell
- Commodity
- rare_earths
- Region
- australia_qld
- Reported Region
- North Queensland
- Ticker
- AHK
Test Work
- Program Status
- scoping
- Test Type
- acid bake and water leach
- Processing Route
- acid bake and water leach
- Sample
- unmilled monazite concentrate (P80 170um), 1,500kg/t acid addition
- Grind P80
- 170 µm
Recovery
- Recovery
- 95 %
- Recovery Basis
- actual_test
- Head Grade
- 48.7
- Head Grade Unit
- % TREO
Lab
- Laboratory
- ANSTO
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-10-08T00:00:00.000Z
Reasoning: 95% recovery is good, but confirms kinetic limitations at coarser sizes.
Positive factors
- Still achieves high recovery despite coarser grind
Negative factors
- Lower recovery than milled concentrate
Evidence · text
“unmilled concentrate returned a lower LRE extraction of 95%”
caustic conversion and hydrochloric acid leachSandy Mitchell · rare_earthsRecovery: 98 %Head Grade: 48.7Head Grade Unit: % TREOView all detailsHide details
Identity
- Project
- Sandy Mitchell
- Commodity
- rare_earths
- Region
- australia_qld
- Reported Region
- North Queensland
- Ticker
- AHK
Test Work
- Program Status
- scoping
- Test Type
- caustic conversion and hydrochloric acid leach
- Processing Route
- caustic conversion and hydrochloric acid leach
- Sample
- ground monazite concentrate, caustic conversion + HCl leach
Recovery
- Recovery
- 98 %
- Recovery Basis
- actual_test
- Head Grade
- 48.7
- Head Grade Unit
- % TREO
Lab
- Laboratory
- ANSTO
Review
- Needs Review
- No
- Historical
- No
Dates
- Event date
- 2026-10-08T00:00:00.000Z
Reasoning: Demonstrates high recovery and effective impurity removal via caustic route.
Positive factors
- High recovery via caustic route
- High phosphate removal (97%)
Evidence · text
“delivering approximately 98% light rare earth extraction”
How Atlas produces this analysis
Minestarters Atlas uses automated extraction to summarize mining announcements, identify reported measurements, and classify supporting evidence. Sentiment reflects the extracted narrative and classification rules; it is an interpretation, not a reported measurement. Evidence quotes and context are provided where available. Missing data, low-confidence results, and review flags indicate limitations. Check the original publisher announcement before relying on an interpretation.