Investor Presentaiton
IRON CLAY
MONAZITE
BASTNAESITE
MINERAL
Clay versus Hard Rock REE
Summary of leaching technologies in primary rare earth elements production
PROCESS/STEPS
REE
YEILD
REMARKS
STATUS
1. Hydrochlorid acid (HCI) leaching to
remove non REE carbonate
85-90%
II. Calcination of esidue to form rare earth
oxide
The oldest way to producte
bastnaesite concentrates.
Outdated
1. Digestion with nitric acid (HNO)
or sulphiric acid (H,SO)
1. Roast at 620°C to drive of carbon
dioxide (CO2)
II. 30% HCI leach
I. Alkine conversion rare-earth metal-
fluoride REF, to rare-earth hydroxide
RE(OH),
II. 30% HCL leach
1. Sulphiric acid roast
II. Sodium chloride solution leach
III. Precipitation as sodium double sulphates
1. Digestion in hot sulphiric acid (H_SO)
98%
•Acid choice depends on further
processing: solvent extraction to nitric
acid (HNO) precipitation to sulphiric
acid (H,SO)
Outdated
• Cerium+Ill oxidises to cerium+IV
during roasting will not leach REE
fluorides
Outdated
• Residue is marketable
•Process can be preceded with
hydrochlorid acid leach to extract REE In use
carbonates before alkaline conversion.
Precipitates are converted to chlorides
for further purification with solvent
extraction.
In use
•Process conditions determine what is
leached: only light REE or light + heavy Outdated
REE+thorium
• Cerium cannot be leached if
manganese is present
1. Digestion in hot 60-70% sodium hydroxide
II. Washing residue with hot water
98%
III. Leach with mineral acid of choice
•Thorium is leached together with REE
Trisodium phosphate (Na_PO) is
In use
marketable by-product
1. Heat under reducing and sulphidising
Requires no fine grinding
atmosphere with calcium chloride (CaCl,) and
calcium carbonate (CaCO,)
89%
II. Leach with 3% HCI
•Thorium does not leach, remains in
residue as thorium dioxide (Tho₂)
No manganese problem
In use
I. Salt leach with ammonium sulphate
(NH),SO,
80-90%
Targets physisorbed REE through
cation exchange
In use
I. Leach with saltwater
40%
•Inefficient but cheap process
Research &
development
Advantages of clay
deposits
Project location
Geographic distribution of
resources and production
Element composition
Rare earth element
assemblage and
concentration
Extraction intensity
Relative operating costs
Exploration dynamics
Cost and time
Mine development
Capital expense
Clay REE
Dominated by Asia,
specifically China and
Myanmar
Both light (Nd and Pr) and
heavy (Tb and Dy) rare
earth elements typically exist
Low
Inexpensive aircore drilling
into soft sedimentary
material for swift exploration
Low
Shallow deposits,
progressive mining and
rehabilitation
Hard Rock REE
Mainly China, also projects
in Australia and the U.S. of
America
Predominately light rare
earth elements (Nd, Pr)
High
Costly, hard rock diamond
drilling required for slower,
expensive exploration
High
Large open pit with large
operating fleet and costly
closure
Processing
Style and environmental
impact
Simple, proven, low acid
metallurgy with inert tailings
and solvent recycling
Complex metallurgy, high
temperatures and pressures,
strong acids and often
radioactive tailings
•Dissolves entire clay
1. Acid leach with strong acid (pH<1)
100%
Not used
Source od6metals.com.au
•Incurs significant additional costs
Source: Peelman et al., 2014.
www.desertmetals.com.au
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