Sheldon Coates, Fairstar Resources: Steeple Hill Iron Project: Recovering Alluvial Hematite through Dry and Wet Processing
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Steeple Hill Iron Project:
Recovering Alluvial Hematite
through Dry and Wet
Processing
Sheldon Coates
B. Sc Geology
M.Sc in Mineral Economics
MBA in Technology Management
DISCLAIMER
The information in this presentation provided by Fairstar Resources
Limited and Sheldon Coates is published to inform you about
Fairstar and its activities. Some statements involve risk and
uncertainty, that could cause actual results to differ from estimated
results. All reasonable effort has been made to provide accurate
information, but we do not warrant or represent its accuracy, and
reserve the right to make changes at any time without notice.
To the extent permitted by law, Fairstar Resources Limited accepts
no responsibility or liability for any losses or damages of any kind
arising out of the use of information contained in this presentation.
Recipients should make their own enquiries in relation to any
investment decisions, or decisions based on technical information
provided.
Steeple Hill Iron Project,
Eastern Goldfields of WA • Situated 80km east of Kalgoorlie, WA.
• Centred about 25km north of Trans Australia railway line
• Small, shaly BIF, contains magnetite at depth
• Weathered to hematite at surface, grade 40% to 62% Fe
• Eroded hematite upgraded as it moves downhill and into
shallow creek system
• Hematite becomes subrounded particles, mostly 1-4mm
• Alluvial hematite grade 58% Fe +/-3%, low P , but has
moderate SiO2 7%, and Al2O3 6%. Low LOI 1.7%
Location
Map
Geological Cross Section
Hematite Outcrop
Eroded Hematite at Base of Hill, 59% Fe
Creek System with Hematite Gravel
Hematite Gravel in Creek Bank;
60% Weight Recovery
Exploration of Alluvial Hematite Deposit
• Mapping indicated significant extent of alluvial hematite
• Pitting with excavator confirmed thickness and economic
proportions of hematite. Also that alluvials are free digging
• Aircore Drilling on 200m x 200m grid along 12km of
valley
• One metre samples taken and processed at metallurgical
laboratory to give percentage recovery and grade of
hematite product
• Consistent hematite product grade 58% Fe +/- 3%
Test Pit with Hematite Gravel Bands
Plan of Drilling
and Alluvial
Hematite
Flow Sheet of Metallurgical Testwork
Wet screen to remove slimes (-45um)
Attrition in vertical blade attritioner
Wet screen at 0.6mm, fines to storage for spiralling
Screen at 6.3mm, oversize crushed to -4mm
0.6 –4mm fraction sent to Dense Media Separator (SG3.4)
Sinks dried, weighed and analysed by XRF for Fe suite
Results reported as percentage hematite recovery and grade
1555 one metre samples from 666 holes analysed
DMS Fractions; SG 3.4
Closeup of Hematite Product.
Graph of All Hematite Recoveries
Sorted Hematite Concentrate Recoveries from Alluvials,
minus Duplicate Samples and Twinned Holes
0
10
20
30
40
50
60
70
80
1
35 69
103
137
171
205
239
273
307
341
375
409
443
477
511
545
579
613
647
681
715
749
783
817
851
885
919
953
987
1021
1055
1089
1123
Number of Samples
Hem
atit
e R
eco
very
%
Series1
Graph of Hematite Grades
0
10
20
30
40
50
60
70
1 49 97 145 193 241 289 337 385 433 481 529 577 625 673 721 769 817 865 913 961 1009 1057 1105
Fe%
Sorted Aircore Fe Grades; minus Duplicates and Twinned Holes
Series1
Indicated Resource Estimate
Fairstar believes project is viable at 5% hematite recovery cutoff.
Hematite
Recovery
Percentage
Cutoff
Tonnes
Mt
Recovery
%
Fe
%
SiO2 %
Al2O3 %
P % LOI
%
10%
94
18
58
7.1
6.0
0.01
1.6
7%
118
16
58
7.1
5.9
0.01
1.7
5%
136
15
58
7.2
5.9
0.01
1.7
Problems with Water Usage in Processing
• Significant water required in process plant: 200kg/t ore?
• Water needs to be fresh –brackish to avoid salt contamination of backfill and hematite product
• Water drilling found only hypersaline water nearby in 30km radius; 58 000TDS to 125 000TDS.
• Reverse osmosis expensive, water too salty for RO, and waste hypersaline water disposal a problem
• Low rainfall area, with unreliable rains; dam unfeasible
• Need to source water at some distance; Eucla Basin, costly
• Need to use dry processing where possible to reduce water usage.
• Recover much of water (80% ?) for reuse
Testwork on Hematite Alluvials
• Sizing analysis of hematite alluvials indicates
minimal hematite below 250 microns.
• This ultrafine fraction makes up around 15% -
50% of alluvials ; highly variable
• This ultrafine fraction ( clay and silt) retains water
and it is very hard to recover this water for reuse
• Need to remove ultrafines by dry methods to
improve water recovery
Sizing Analysis: Av 162 Pit Samples
+6.3mm +1mm +63um -63um
Average 3.5% 25.4% 18.8% 52.3%
Min 0% 2.5% 2.3% 6.2%
Max 44.9% 82.4% 57.1% 87.9%
Includes clay samples.
Dry Processing Methods Investigated
• Dry magnetic separation of about 40% of the hematite to
reduce throughput. Magnetic fraction 60.3% Fe. Non
magnetic fraction 57.7%Fe.
• Air Classifiers to remove ultrafine fraction which has
minimal hematite, and retains water
• Fluidised air beds to remove ultrafine fraction, and abrade
surface coating
• ROTEX shaking screens to remove ultrafines
• Air jig to remove ultrafine fraction, and also reduce low
density coarse waste, reducing throughput to plant down
stream
Air Classifier
Diagram
and Results
Fluidised Air Bed Results
Carrier Air Bed : three tests reduced ultra fines (<250 microns)
from 15.9% to 3.0%, 2.4% and 1.25% respectively
Barr-
Rosin
Sample
Coarse
Fraction
>355
microns
Fine
Fraction
212-355
microns
Ultra Fine
Fraction
<212
microns
Comment
Original 80.2% 9% 10.8%
Coarse
Airbed
91.3% 6.2% 2.5% Fluidising
velocity
2m/s
Fines
Airbed
18.5%
0% 35.6% 63.3% Minor loss
of >250u
ROTEX Vibrating Screen Deck
Dry Air
Jig
Air Jig Results; Feed raw ore
Heavy Underflow Light Filter
Mass % 29.81 12.04 39.01 19.14
DMS OF % 19.4 14.6 95.7 N/A
DMS UF% 80.6 85.4 4.3 N/A
Fe2O3 % 58.84 61.51 56.98 N/A
SiO2% 7.22 5.11 8.97 N/A
Al2O3% 5.62 4.19 5.82 N/A
Air Jig Fractions
Comparison of Dry Processing Methods
Method Advantages Disadvantages
Dry Belt magnet Low Cost Only 40% of hematite
extracted
Air Classifier Simple design, very
efficient result
Possible clogging with
damp ore
Fluidised Air Bed Dries ore as well as
separating out fines
High air flow required,
so high power cost
Vibrating Screen Deck Very good removal of
ultrafines
Potential for clogging
of screens if ore damp
Air Jig Removes ultrafines,
and/or removes part of
coarse waste
May need to remove
ultrafines first to
increase efficiency
Testwork to Improve Grade of Hematite
Product
• Hematite average grade is 58% Fe, 7% SiO2, 6% Al2O3.
The silica and alumina need to be reduced, to raise the Fe
grade as each 1% Fe increase is worth about $3/t
• Mineralogy testwork shows minor very fine internal quartz
within hematite granules; not removeable
• Also shows partial silica/clay coating on some granules,
especially in pits. This can be reduced
• Testwork undertaken to ascertain how to reduce the
coating, to achieve product target of 60% Fe
Hematite Product of Laboratory
Additional Trommeling of +250um Ore
• Because the metallurgical laboratory used a small vertical blade
attritioner to clean the drill samples, testwork was undertaken with a
test trommel 1.5m in diameter to approximate full size plant conditions
to clean up the hematite.
• This can be correlated with the residence time required in a full size
scrubber
• Tests were taken with differing residence times, water/sample ratios,
chemical additives and attrition media
• Chemical additives were Claymaster (5ml per litre water),and Liqui-
Sperse with Aus Det Xtra (7.5mls and 2.5mls per litre water)
• Attrition media was 12-15mm crushed gravel, 20% of ore weight
• Results were encouraging with all DMS sinks above 59%Fe
• Attrition media and Claymaster performed best. Latter preferred
Trommel Results
Test No Duration Additives Fe % SiO2 % Al2O3%
Control 3.5mins Minimal water 59.13 5.74 6.08
W 30% 2.5mins Water 30% of
ore
59.30 5.78 6.03
W 50% 3.5mins Water 50% of
ore
59.23 5.78 5.99
L-5 5mins Water 50%
LiquiSperse and
Aus Det Xtra
59.36 5.74 6.04
C-5 5mins Water 50%
Claymaster
59.59 5.55 5.85
A-3.5 3.5mins Water 50%
Gravel 20%
59.69 5.45 5.79
Bioleaching to Reduce Alumina and Silica
Testwork by Dr P Williams (South Africa) indicates P,
SiO2 and Al2O3 in iron ore can be reduced by
bioleaching.
Tests undertaken on SHIP hematite product (0.6- 4mm)
• Fungi Aspergillus niger was used, and produces organic
acids including citric acid and oxalic acids
• Three different concentrations of fermentation medium
used, and each innoculated with 1ml of A niger; 10 million
spores
• 500g of hematite incubated at 30deg C for 10days
• Results showed significant reductions of SiO2, Al2O3,
TiO2, MgO, CaO, Na2O and NiO. Little Fe2O3 was lost
Aspergillus Niger Leach Results
Percentage Decrease Compound 1/1 Pulp Density
500g Hm in 500g
medium
1/2 Pulp Density
500g Hm in 250g
medium
1/5 Pulp Density
500g Hm in 100g
medium
Fe2O3 0.7 0.8 3.8
SiO2 10.6 33.9 22.9
Al2O3 11.4 25.0 18.2
TiO2 12.5 12.5 12.5
MgO 100 100 100
CaO 100 100 100
Na2O 72.7 90.9 90.9
K2O 5.9 17.6 5.9
P 5.9 23.5 5.9
NiO 100 100 100
MnO 0 0 0
Bioleaching with Heterotrophic Bacteria
• Bioleaching used a combination of five different bacterial cultures
• 5ml of each culture in 500ml of growth medium with 250g hematite product (0.6-4mm) from metallurgical laboratory
• Incubated at 30degrees C with agitation (150rpm) for 5 days and a second batch for 10 days
• Hematite head grade 58.630% Fe, 6.855% SiO2, 6.295% Al2O3
• Silica reduced by 16.3% in 5 days and 21.7% in 10days in +1mm
• Alumina reduced by 16.0 in 5 days and 19.7% in 10 days in +1mm
• Fe grade of +1mm increased from 58.630% to 59.628% Fe in 5 days, and up to 59.95% in 10 days. But 20% Hm now as –1mm, 52%Fe
• 20% of Fe into low grade –1mm requires new spiral separation
• Potential problem with other bacterial growth in industrial setup
• Potential problem with water usage and waste disposal -> backfill?
Results of Bacterial Leaching Element
/ Mass
Head
grade
5 Days
+1mm
5 Days
-1mm
10 Days
+1mm
10 Days
-1mm
Mass 250 g 208.45 41.55 198.33 51.86
Fe % 58.63 59.63 52.20 59.95 52.26
SiO2% 6.85 5.74 12.29 5.36 12.42
Al2O3 % 6.29 5.29 8.72 5.06 8.73
TiO2% 0.85 0.75 1.09 0.73 0.83
MnO% 0.06 0.06 0.06 0.06 0.06
MgO% 0.08 0.00 0.00 0.00 0.00
CaO% 0.07 0.00 0.00 0.00 0.00
Na2O% 0.08 0.03 0.04 0.03 0.04
K2O% 0.03 0.03 0.03 0.03 0.03
P% 0.015 0.014 0.015 0.013 0.016
Processing Pathway
Trommel Dry
Air Classifier to remove ultrafines
Dry Screen at 6mm, crush oversize to -4mm
Dry Screen at 1mm; fines to wet spirals
1-4mm to belt magnet; magnetic Hm removed
Non mags to Dry Air Jig ?
Heavy Fractions to Dense Media Separation
Recover water on belt filter
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