CASE STUDIES USING PORTABLE XRF ANALYSERS DURING SOIL CONTAMINATION AND MINERAL EXPLORATION PROJECTS. Todd Houlahan 21 st IGES, Dublin, Ireland, 2003

Transcription

1 CASE STUDIES USING PORTABLE XRF ANALYSERS DURING SOIL CONTAMINATION AND MINERAL EXPLORATION PROJECTS Todd Houlahan 21 st IGES, Dublin, Ireland, 23

2 Introduction Use of field portable XRF on soil assessment and mineral exploration projects undertaken in Australia 2 projects in detail Environmental Assessment at a Derelict Mine Exploration Drilling (Bowdens Ag Project) Several other projects in brief

3 Portable XRF Derelict Mine Assessment NITON XL-82S (Cd 19 radioisotope) Detection Limits typically 5-1 ppm Bowdens Drilling Project NITON XLi 969 (Am 241 radioisotope) Detection limits typically 1-15ppm Elements detected As, Cr, Cu, Pb, Mn, Hg, Ni, Co, Se, Zn, Fe, Rb, Sr, Zr, Mo Ag, Cd, Sn, Sb, Ba

4 Derelict Mine, NSW (Cu/Au/Talc) State funded rehabilitation program

5 Derelict Mine Copper Data XRF Cu ppm Cu (n=65) y = 1.45x R 2 =.9594 Threshold 5 ppm 1 failure XRF 4869 ppm Lab 7411 ppm Laboratory Cu ppm

6 Derelict Mine Zinc Data Zn (n=88) Threshold 9 35ppm XRF Zn ppm 6 3 y = 1.577x R 2 = failures XRF 3k and 29k Lab 46k and 39k Labo rato ry Zn ppm

7 Derelict Mine Lead Data Pb (n=72) Threshold XRF Pb ppm y =.523x R 2 = ppm 1 failure XRF 453 ppm Lab 164 ppm Laboratory Pb ppm

8 Derelict Mine Project Findings Merits - demonstrated ability to locate hot-spots in the field - applicable for use as part of the derelict mines program - rapid (multi-element) technique - excellent for quickly mapping boundaries (mullock above/below specified threshold levels) - remote location benefits - project management benefits (directing clean up operations) - public relations tool

9 Other Projects (Environmental) Baseline Soil Survey of Broken Hill township >4 soils tested (Pb.94, Zn.96) Copper Smelter Contaminated Soil Survey 4 soils tested (Cu r 2 =.99, As r 2 =.99, Pb r 2 =.92) Former Electroplater Soil Excavation and Remediation 6 soils tested (Ni r 2 =.91, Cr r 2 =.91) Former Dulux Lead Paint Manufacturing Facility 2 soils tested (Pb r 2 =.92) published paper Former Cattle Tick Dip Site approx 5 soils tested (As r 2 =.99) published paper with CSIRO (Commonwealth Scientific and Industrial Research Organisation)

10 Silver Standard Australia (Ag with Pb, Zn and As)

11 Bowdens Ag Project Aims Can XRF be used to reduce assay costs in exploration? Accuracy and precision of XRF on Ag, Pb, Zn and As Can XRF be used to maximise drilling budgets? Assess last 1m of a hole What field testing protocol will work best 1. Testing actual sample sent for assay (apples v apples) 2m interval 2. Testing residual cuttings (apples v nashy pears) 5 m interval

12 Bowdens Ag Results - Method 1 NITON XRF Ag (ppm) Ag (6-8m) y =.6692x R 2 = Ag poor accuracy & precision esp. below 1ppm However Average Ag 6-8m Lab 92 ppm XRF 94 ppm Laboratory Ag (ppm)

13 Bowdens Results Method 1 Zn (6-8m) Pb (6-8m) 12 2 NITON XRF (ppm) y =.8489x R 2 =.9863 NITON XRF (ppm) y =.6676x R 2 = Laboratory (ppm) Laboratory (ppm) Average Zn Average Zn Average Pb Average Pb Lab 1828 ppm Error: -28% Lab 2279 ppm Error: -38% XRF 138 ppm XRF 1413 ppm

14 Bowdens Results Method 2 NITON XRF Ag (ppm) Ag (5-1m) y = 1.881x R 2 = Laboratory Ag (ppm) NITON XRF Ag (ppm) Ag (9-1m) y = x R 2 = Laboratory Ag (ppm) >1ppm better 9-1m Ag Average Lab 187 ppm FPXRF 199 ppm RSD s 49% (118 ppm) 16% (663 ppm)

15 Bowdens Results Method 2 Zn (5-1m) Zn (9-1m) NITON XRF (ppm) 1 5 y =.9778x R 2 =.9441 NITON XRF (ppm) 1 5 y = x R 2 =.9723 RSDs 4% (9 ppm) 7% (2 ppm) Laboratory (ppm) Laboratory (ppm) Average Zn Average Zn Average Zn Average Zn Lab 2657 ppm Error: -2% Lab 5486 ppm Error: -6% RF 2118 ppm XRF 5182 ppm

16 Bowdens Results Method 2 Pb (5-1m) Pb (9-1m) NITON XRF Pb (ppm) y =.7479x R 2 = NITON XRF Pb (ppm) y =.799x R 2 = RSDs 4.7% (18 ppm) 6.9% (2 ppm) Laboratory Pb (ppm) Laboratory Pb (ppm) Average Pb Average Pb Average Pb Average Pb Lab 2134 ppm Error: -34% Lab 5139 ppm Error: -23% XRF 1417 ppm XRF 3949 ppm

17 Bowdens Project Findings XRF can be used to reduce assay costs and as first pass for grade control Can be used to maximise drilling budgets by directing depth of holes in the field (no re-drilling) XRF Testing Method No significant loss of precision between testing methods No significant difference in accuracy between testing methods Merit in testing RC bags in-situ

18 Other Projects (Exploration) Exco Resources (Zn r 2 =.93) also Cu MIM (Xstrata) Exploration RC Drilling program (+2ppm Cu anomalies in basement material Platinum Australia Cr in PGM s Other RC drilling Ni, Cu Core drilling Ti, Cu

19 Acknowledgements Dr Ian Pringle - Silver Standard Australia Paul Frederickson NSW Department of Mineral Resources Alasdair Cooke Exco Resources Tom Wilson - Consulting Earth Scientists Xstrata Copper Australia Thankyou Questions?

20 Bowdens As Data As (6-8m) As (5-1m) XRF y =.366x R 2 =.36 XRF y =.4695x R 2 = Laboratory Laboratory

21 Core Examples