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Sheldon Coates, Fairstar Resources: Steeple Hill Iron Project: Recovering Alluvial Hematite through Dry and Wet Processing
 

Sheldon Coates, Fairstar Resources: Steeple Hill Iron Project: Recovering Alluvial Hematite through Dry and Wet Processing

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Sheldon Coates, Chief Geologist, Fairstar Resources Ltd delivered this presentation at the 2013 FE Tech Conference. The event focussed on the economics of processing and the beneficiation of iron ore. ...

Sheldon Coates, Chief Geologist, Fairstar Resources Ltd delivered this presentation at the 2013 FE Tech Conference. The event focussed on the economics of processing and the beneficiation of iron ore. In light of the slowdown in demand for iron ore and pricing decreases, the need to process more efficiently and cost effectively is a challenge. The conference examined on how we can achieve greater value from the iron ore supply chain, with topics addressing optimisation and streamlining processes, applying improved technologies, understanding the ore body and how to properly characterise it, knowing the steel makers needs. For more information please visit the conference website: http://www.informa.com.au/fe-tech

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    Sheldon Coates, Fairstar Resources: Steeple Hill Iron Project: Recovering Alluvial Hematite through Dry and Wet Processing Sheldon Coates, Fairstar Resources: Steeple Hill Iron Project: Recovering Alluvial Hematite through Dry and Wet Processing Presentation Transcript

    • 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 80 70 50 40 Series1 30 20 10 Number of Samples 1123 1089 1055 1021 987 953 919 885 851 817 783 749 715 681 647 613 579 545 511 477 443 409 375 341 307 273 239 205 171 137 103 69 35 0 1 Hematite Recovery % 60
    • Graph of Hematite Grades Sorted Aircore Fe Grades; minus Duplicates and Twinned Holes 70 60 50 Fe% 40 Series1 30 20 10 0 1 49 97 145 193 241 289 337 385 433 481 529 577 625 673 721 769 817 865 913 961 1009 1057 1105
    • Indicated Resource Estimate Hematite Tonnes Recovery Mt Percentage Cutoff 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 Fairstar believes project is viable at 5% hematite recovery cutoff.
    • 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 BarrRosin 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 Underflow 12.04 Light 39.01 Filter 19.14 DMS OF % 19.4 DMS UF% 80.6 Fe2O3 % 58.84 14.6 85.4 61.51 95.7 4.3 56.98 N/A N/A N/A SiO2% Al2O3% 5.11 4.19 8.97 5.82 N/A N/A Mass % Heavy 29.81 7.22 5.62
    • 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 LiquiSperse 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 1/5 Pulp Density 500g Hm in 250g 500g Hm in 100g medium 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