Hawthorn Resources Geochemical Characterisation · 2020. 3. 24. · 1.2 SCOPE OF WORK The scope of work (SOW) completed by SWC for this project included: Review of existing geological

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SOILWATER CONSULTANTS

HAWTHORN RESOURCES GEOCHEMICAL CHARACTERISATION

Prepared for: HAWTHORN RESOURCES

Date of Issue: 12/03/2014

Project No.: HAW-001-1-8

Document Ref: 001-RevB

Distribution:

Electronic Copy – Ian Moody

Soilwater Group (Perth Office)

i

DOCUMENT STATUS RECORD

Project Title: HAWTHORN RESOURCES GEOCHEMICAL CHARACTERISATION

Project No.: HAW-001-1-8

Client: HAWTHORN RESOURCES

Revision History

Revision Code* Date Revised Revision Comments Signatures

Originator Reviewer Approved

A 10/03/14 Issued for internal review RG/ASP SC ASP

B 12/03/14 Issued for client review RG/ASP JN SC

C 12/03/14 Final report issued

Revision Code* A - Report issued for internal review B - Draft report issued for client review C - Final report issued to client

LIMITATIONS

The sole purpose of this report and the associated services performed by Soil Water Consultants (SWC) was to undertake a geochemical characterisation for the proposed Anglo Saxon Project. This work was conducted in accordance with the Scope of Work presented to Hawthorn Resources Limited (‘the Client’). SWC performed the services in a manner consistent with the normal level of care and expertise exercised by members of the earth sciences profession. Subject to the Scope of Work, the Geochemical Characterisation was confined to the proposed open pit at Anglo Saxon. No extrapolation of the results and recommendations reported in this study should be made to areas external to this project area. In preparing this study, SWC has relied on relevant published reports and guidelines, and information provided by the Client. All information is presumed accurate and SWC has not attempted to

verify the accuracy or completeness of such information. While normal assessments of data reliability have been made, SWC assumes no responsibility or liability for errors in this information. All conclusions and recommendations are the professional opinions of SWC personnel. SWC is not engaged in reporting for the purpose of advertising, sales, promoting or endorsement of any client interests. No warranties, expressed or implied, are made with respect to the data reported or to the findings, observations and conclusions expressed in this report. All data, findings, observations and conclusions are based solely upon site conditions at the time of the investigation and information provided by the Client. This report has been prepared on behalf of and for the exclusive use of the Client, its representatives and advisors. SWC accepts no liability or responsibility for the use of this report by any third party.

© Soilwater Consultants, 2013. No part of this document may be reproduced or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission of Soilwater Consultants.


CONTENTS

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CONTENTS

1 INTRODUCTION ................................................................................................................................... 5

1.1 Study Objectives .................................................................................................................................... 5 1.2 Scope of Work ....................................................................................................................................... 5

2 PROJECT DESCRIPTION ...................................................................................................................... 6

2.1 Site Layout............................................................................................................................................. 6 2.2 Site Geology .......................................................................................................................................... 6

3 STUDY METHODOLOGY ..................................................................................................................... 10

3.1 Waste Material Sample Selection ..........................................................................................................10 3.2 Laboratory Analysis ...............................................................................................................................10

4 STUDY RESULTS ............................................................................................................................... 13

4.1 pH & pHox ...............................................................................................................................................13 4.2 Electrical Conductivity ...........................................................................................................................13 4.3 Sulfur Speciation ...................................................................................................................................16 4.4 Acid Neutralising Capacity (ANC) ..........................................................................................................16 4.5 Acid Base Account (ABA) ......................................................................................................................18 4.6 Net Acid Generation (NAG) ...................................................................................................................20 4.7 Geochemical Classification ....................................................................................................................20 4.8 Multi-Element Composition ....................................................................................................................23

5 CONCLUSIONS .................................................................................................................................. 27

6 REFERENCES .................................................................................................................................... 28

LIST OF FIGURES

Figure 1: Regional Location ......................................................................................................................................... 7 Figure 2: Site Layout .................................................................................................................................................... 8 Figure 3: Project Geology ............................................................................................................................................ 9 Figure 4: Drill holes in the Project Area ........................................................................................................................11 Figure 5: pH, pHox and EC profiles ............................................................................................................................14 Figure 6: pH, pHox and EC profiles continued… ..........................................................................................................15 Figure 7: ABA plots .....................................................................................................................................................19 Figure 8: Geochemical classification plots ...................................................................................................................22

LIST OF TABLES

Table 1: Selected samples requiring detailed AMD testing ...........................................................................................10 Table 2: Maximum Potential Acidities (MPA) for the samples analysed at Hawthorn Resources ....................................16


CONTENTS

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Table 3: Potential buffering capacities of the various materials tested at Hawthorn........................................................17 Table 4: Static Net Acid Generation results for the samples tested ...............................................................................20 Table 5: Multi-element composition of selected samples from drill holes PINC164, PINC171, and PINC191 ..................23 Table 6: Multi-element composition of selected samples from drill holes PINC195, PINC198, and PINC199 ..................24 Table 7: Global Abundance Index for the various metals and metalloids for drill holes PINC164, PINC171 and PINC191 ..................................................................................................................................................................................25 Table 8: Global Abundance Index for the various metals and metalloids for drill holes PINC195, PINC198 and PINC199 ..................................................................................................................................................................................26


CONTENTS

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1 INTRODUCTION

Soilwater Consultants (SWC) was commissioned by Hawthorn Resources Limited (Hawthorn) to undertake a geochemical characterisation for the Anglo Saxon Deposit (Project Area). The Anglo Saxon resource will be mined using open pit techniques with the excavated mine waste rock to be disposed of in an adjacent Waste Rock Landform (WRL). As part of the environmental approvals to mine, this geochemical characterisation was undertaken to identify the presence or absence of potential acid rock drainage (ARD) or metaliferous drainage (MD) materials, highly saline or other problematic materials, which may impact on the surrounding environment if managed inappropriately.

1.1 STUDY OBJECTIVES

The specific objectives of this work were to:

Assess the current baseline geochemical conditions existing within areas of Anglo Saxon currently proposed for development.

Undertake an Acid Base Account (ABA) to identify any environmental risks associated with the disturbance of any ARD materials, if present.

Identify any risk of MD following disturbance of the mined materials. Identify other problematic waste characteristics, which if present, may impact on the stability and sustainability of

the WRL. Suggest management strategies for the handling and utilisation of the waste rock materials during mining and

rehabilitation, if required.

1.2 SCOPE OF WORK

The scope of work (SOW) completed by SWC for this project included:

Review of existing geological and assay drill data for Anglo Saxon. Identification of representative drill holes providing sufficient spatial coverage of Anglo Saxon. Undertake and co-ordinate the initial laboratory screening analysis. Selection of samples for additional detailed laboratory analysis to confirm their ARD and MD status. Review of laboratory results and preparation of this report.


PROJECT DESCRIPTION

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2 PROJECT DESCRIPTION

2.1 SITE LAYOUT

The Anglo Saxon Deposit is located approximately 650 km north east of Perth and 140 km north east of Kalgoorlie (Figure 1) within a series of granted Mining and Associated Infrastructure Leases. The proposed operation will consist of a series of starter pits which will eventually merge to form one open cut pit centred on the existing historical workings, with waste rock disposed of to the adjacent historical Waste Rock Landform (WRL) which will be enlarged (Figure 2).

2.2 SITE GEOLOGY

The Anglo Saxon Deposit is located within the Edjudina Terrane of the eastern portion of the Norseman to Menzies Greenstone Belt in the Eastern Goldfields. The major geological groups consist of narrow, elongate lithotectonic domains of Archaean rock units which are equivalent in composition and chronology to the Kalgoorlie greenstones and are now variably overlain by Tertiary and Quaternary transported sediments (Groenwald, 2000). The local geology (Figure 3) consists of a north-west striking sequence of komatiitic and volcanic rocks, predominately andesite to rhyolite facies, and layered mafic to ultramafic intrusions of sub-volcanic origin (Swager, 1995). The sedimentary rock proportion of the greenstones appears to mainly consist of undifferentiated sediments; including shale, siltstone, chert, sandstone and conglomerate. They are typically formed in association with the felsic volcanics and include a significant felsic volcanic component (which is epiclastic in nature)

A domain bounding fault, the north-west to north striking Pinjin Fault, separates the low-medium metamorphic grading Edjudina domain in the west from the higher grading Pinjin Domain in the east. This fault corresponds roughly to the western side of the project boundary. Several further faults and shears exist within the deposit lithology, with two principal structures defining mineralisation termed the Pinjin King Shear and the Anglo Saxon Shear (Williams, 1996). The Pinjin King Shear is restricted to an ultramafic schist unit with minor quartz veining and sulphide rich micas. The Anglo Saxon Shear is developed within quartzo-feldspathic schists containing thin BIF / shale horizons and minor ultramafic schists.

PN: HAW-001-1-8 Prepared by: SC Date: 03/11/14 Reviewed by: ASP Date: 03/11/14 Revision: 1

HAWTHORN RESOURCES Figure 1: Regional Location



HAWTHORN RESOURCES Figure 2: Site Layout



HAWTHORN RESOURCES Figure 3: Project Geology



STUDY METHODOLOGY

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3 STUDY METHODOLOGY

3.1 WASTE MATERIAL SAMPLE SELECTION

The drilling data from a total of 307 drillholes completed in the Project Area (Figure 4) were assessed as part of this characterisation. The drilling was conducted to depth of between 10 and 424 m (down drill hole), with samples collected at 1 or 2 m vertical intervals. Following a review of the drilling data, seven (7) representative drill holes were selected (Figure 4) for further screen analysis. The drill holes selected reached an average depth of 92 m, with samples collected over the entire drill hole lengths at 3 m intervals resulting in 201 samples for screen analysis.

3.2 LABORATORY ANALYSIS

All samples collected (201) were assessed for pH, pHox and electrical conductivity (EC), according to the following methods;

pH – 1:5 soil/water extraction. This parameter measures the existing acidity of the waste materials and gives information on whether previous oxidation of sulfides has occurred and the potential buffering capacity of the materials.

pHox – This measures the pH of the waste materials from addition of 30% hydrogen peroxide which rapidly oxidises any sulfides present. The method followed is outlined in (Stone and Ahern et al., 1998).

EC – 1:5 soil/water extraction. This parameter measures the level of salinity within the waste materials, which may reflect previous oxidation of sulfides.

Following review of the results of the pH, pHox and EC analysis and the review of geological data, a total of 12 were selected for detailed testing to confirm the screen test results and to quantify the potential for acid drainage occurring in response to the proposed mining operation. The samples, listed in Table 1, represent a spread across pH and PHFOX range, and occur throughout the defined deposit to ensure representative sampling. A total of twelve (12) samples were selected, as fewer samples were not deemed sufficient to adequately quantify the risk of acid mine drainage (AMD).

Table 1: Selected samples requiring detailed AMD testing

SWA ID DH ID Client ID Depth From (m) Depth To (m) pH pHOX

13-0366-002 PINC164 H42054 3 4 7.69 5.85

13-0366-006 PINC164 H42066 15 16 7.50 5.66

13-0366-025 PINC164 H42126 72 73 9.45 8.80

13-0366-047 PINC171 H42928 33 34 7.39 5.73

13-0366-080 PINC191 H47046 15 16 6.75 5.60

13-0366-081 PINC191 H47049 18 19 5.69 4.70

13-0366-139 PINC195 H47617 9 10 8.92 7.71

13-0366-144 PINC195 H47633 24 25 8.59 7.35

13-0366-151 PINC195 H47655 45 46 9.03 10.18

13-0366-164 PINC198 H47862 3 4 7.85 6.88

13-0366-165 PINC198 H47865 6 7 7.10 5.51

13-0366-205 PINC199 H47993 39 40 8.73 8.69


HAWTHORN RESOURCES Figure 4: Drill holes in the Project Area



STUDY METHODOLOGY

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The following AMD testing was completed on the 12 selected samples:

Total sulphur (Total S) Sulfate S (SO4-S) Chromium reducible Sulfur (SCR) Acid Neutralising Capacity (ANC) Total Inorganic Carbon (TIC) Net Acid Generation (NAG)

Multi-element composition1 testing was completed on all twelve (12) samples. All external analyses were carried out by Australian Laboratory Services (ALS) which is a National Association of Testing Authorities (NATA) accredited laboratory.

1 Metals and metalloids to assess include: Ag, Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, P, Pb, Sb, Se, Sn, Th, U, V and Zn


STUDY RESULTS

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4 STUDY RESULTS

4.1 PH & PHOX

The depth profiles for the 7 representative drill holes sampled are shown in Figure 5 and Figure 6. The pH of all samples tested (201) varies from 5.15 (moderately acidic) to 9.88 (strongly alkaline), with an average of 8.44 and a median of 8.92 (moderately to strongly alkaline). These pH results indicate that no appreciable acidity is present within the samples, with previous oxidation of appreciable sulfides either not occurring or buffered by contained neutralising capacity which the majority of materials strongly alkaline nature suggests would be readily available. The upper profile (< 40 m depth) tend to be slightly acidic to neutral, whilst the deeper profile material across all drill holes tested shows a strongly alkaline condition. This is likely to reflect the depth of the weathering front in this region, with base of complete oxidation at or above the observed change in redoximorphic conditions.

The pHox of all materials tested varies from 4.70 to 10.18, with an average of 8.19 and a median of 8.8 (moderately alkaline). The down hole profiles show that pHox values closely follow the un-oxidised pH values for each samples tested, with the majority of samples recording a pHox value within 1 pH unit of the corresponding pH value. These results indicate that there is unlikely to be appreciable sulfides within the screen samples, and if present, their released acidity has been completely neutralised by an excess of alkalinity present.

4.2 ELECTRICAL CONDUCTIVITY

The EC (salinity) of the materials tested varies from 7.9 (non-saline) to 105.5 (moderately saline) mS/m, with an average of 31.52 and median of 21.7 mS/m (non-saline). This result reinforces the view that previous oxidation of sulfides is unlikely to have occurred with the samples tested, as breakdown of materials associated with acid production generally increases salt content and precipitation. The results also show that the materials tested are likely to be suitable for use in rehabilitation with no observed chemical limitation to plant establishment and/or growth.

PN: HAW-001-1-8 Prepared by: Date: MM/DD/YY Reviewed by: Date: MM/DD/YY Revision:

HAWTHORN RESOURCES Figure 5: pH, pHox and EC profiles



HAWTHORN RESOURCES Figure 6: pH, pHox and EC profiles continued…



STUDY RESULTS

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4.3 SULFUR SPECIATION

The Total Sulfur (S) results were compared against criteria (i.e. 0.3%) for predicting acid forming potential of a material specified by the Australian Minerals Institute Research Association International (AMIRA, 2002).

The samples were tested for Sulfur Speciation in order to gain an understanding of the proportion of Total S attributable to inorganic sulfide and organic sulfate; with the results of this test work shown in Table 2. This distinction of sulfur mineral type is critical as the oxidation of sulfate minerals produces negligible quantities of acid, and therefore does not pose a risk of AMD. The Western Australian Department of Environment and Conservation (now renamed the Department of Environment and Regulation), assessment criteria for determining acid sulfate soils were used for the purpose of result interpretation (DEC, 2013). The DEC criteria specify that materials with Sulfide S content greater than (>) 0.03 % may potentially be acid producing. The maximum potential acidity (MPA) calculated directly from the S contents is also shown.

Table 2: Maximum Potential Acidities (MPA) for the selected samples

Drill Hole ID

Depth From (m)

Sulfide S Total S SO4-S Sulfide as Total S

% MPASCR

kg H2SO4/t %

MPA kg H2SO4/t

% % MPASulfide

kg H2S04/t

PINC164 3 0.000 0.00 0.040 1.22 0.01 0.03 1.02

PINC164 15 0.000 0.00 0.030 0.92 0.01 0.02 0.69

PINC164 72 0.000 0.00 0.000 0.00 0.00 0.00 0.00

PINC171 33 0.000 0.00 0.020 0.61 0.01 0.01 0.42

PINC191 15 0.000 0.00 0.050 1.53 0.01 0.04 1.20

PINC191 18 0.000 0.00 0.030 0.92 0.01 0.02 0.58

PINC195 9 0.000 0.00 0.010 0.31 0.00 0.01 0.31

PINC195 24 0.000 0.00 0.010 0.31 0.00 0.01 0.25

PINC195 45 0.014 0.43 0.040 1.22 0.00 0.04 1.22

PINC198 3 0.000 0.00 0.030 0.92 0.01 0.02 0.70

PINC198 6 0.000 0.00 0.050 1.53 0.01 0.04 1.18

PINC199 39 0.000 0.00 0.010 0.31 0.00 0.01 0.24

Note: Results for Sulfide S below the limit of reporting (LOR) of 0.005% were assumed to be 0%; Values in bold exceed the criteria of 0.003% for Sulfide S (DEC, 2013) and 0.3% for Total S (AMIRA, 2002).

Results of the Sulfur Speciation found that the Total S content was low, ranging from 0.01 % to 0.05 % with none of the selected samples exceeding the 0.3% AIMIRA criteria value. In terms of Sulfide S content, only one of the samples tested for detailed AMD was found to exceed 0.03% with the rest of the samples containing less than the detectable limit (0.005%). The MPA of this sample group was 0.43 kg H2SO4/t which indicates limited acid producing potential.

4.4 ACID NEUTRALISING CAPACITY (ANC)

The neutralising capacities of the samples that were selected for detailed ARD analysis including Acid Neutralising Capacity (ANC), Total Inorganic Carbon (TIC) and Carbonate Neutralising Potential (CarbNP) are presented in Table 3.


STUDY RESULTS

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Table 3: Potential buffering capacities of the selected samples

Drill Hole ID Depth From

(m) ANC

(kg H2SO4/t) TIC (%)

CarbNP (kg H2SO4/t)

PINC164 3 1.2 0.05 4.1

PINC164 15 4.5 0.05 4.1

PINC164 72 13.0 0.00 0.0

PINC171 33 6.1 0.09 7.4

PINC191 15 0.6 0.05 4.1

PINC191 18 0.0 0.05 4.1

PINC195 9 5.9 0.08 6.5

PINC195 24 3.3 0.00 0.0

PINC195 45 110.0 1.20 98.0

PINC198 3 2.2 0.05 4.1

PINC198 6 0.0 0.05 4.1

PINC199 39 9.1 0.00 0.0

Note: Results for ANC below the LOR of 0.5 kg were assumed to be 0.0 kg

The results show the majority of samples contained negligible ANC, with values ranging from 0.0 kg H2SO4/t to 13.0 kg H2SO4/t. An exception to this was a single sample from drill hole PINC195 at 45 m which had a moderate ANC value of 110.0 kg H2SO4/t.

CarbNP, which is a function of the TIC, can be a more accurate measure of the available alkalinity in the samples. This is because the standard ANC testing procedure can overestimate the buffering potential of a sample as it includes buffering effects of primary silicate minerals, the dissolution of which are generally slow kinetically (particularly ferromagnesian silicates and feldspars) under circum-neutral conditions of pH 6 – 8 (White and Brantley, 1995) and can therefore be ineffective at neutralising acid generation from pyrite oxidation. In general the CarbNP in the samples from Hawthorn Resources are low again with the exception of a single sample from drill hole PINC195 at 45 m which had a moderate ANC value of 98.0 kg H2SO4/t. Though the available alkalinity is low, it is likely to be sufficient in most cases to neutralise any acidity produced as a result of sulfide oxidation.

In the case of several samples the calculated CarbNP is actually slightly larger than the corresponding ANC. It is likely that within these samples, some portion of the buffering species are composed of Fe (siderite) and/or Mn (rhodochrosite) carbonates that generally do not contribute to acid neutralisation under normal weathering conditions (Price, 2009) and therefore are not detected through the normal ANC determination.


STUDY RESULTS

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4.5 ACID BASE ACCOUNT (ABA)

The results of an Acid Base Account (ABA) conducted for the 12 samples tested are presented in Figure 7. The Maximum Potential Acidity (MPA) values are calculated from the Total S contents and assumes that all of the S within each sample occurs in the form of iron pyrite (FeS2) and oxidises according to the equation shown below, which produces the maximum acidity of any sulfide species and therefore gives a ‘worst case’ scenario for acid production.

FeS 154O

72H O Fe OH 2H SO

The Net Acid Producing Potential (NAPP) is calculated by subtracting the ANC or CarbNP value for each sample from the calculated MPA. A positive NAPP value therefore indicates that the sample is likely to be acid producing whereas a negative NAPP value indicates the sample is acid consuming.

The MPA values based on Total S vary from <0.3 to 1.5 kg H2SO4/t. When these MPA values are compared to the ANC the resultant NAPP varies from 0.9 to -108.8 kg H2SO4/t; which equates to a negligible acid production through to a large acid consumption. As discussed in Section 4.3 and 4.4, the ANC does not always accurately reflect total available buffering capacity and therefore the MPA has also been compared with the CarbNP, resulting in NAPP values ranging from <0.3 to -104.8 kg H2SO4/t. These results highlight that the majority of materials tested had very low acid producing potentials.

The ABA plots are shown in Figure 7 which compare the calculated ANC and CarbNP with the S %, with results from mining experience and research showing that the ARD potential of a material can be considered low for materials with a CarbNP/MPA ratio greater than 2 (Price, 2009; Currey et al, 1997). Four samples reported a Buffering Capacity/MPA ratio below 2, with three of these samples reporting a ratio below 1 (i.e. negative NAPP).


HAWTHORN RESOURCES Figure 7: ABA plots


0

4

8

12

16

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16

ANC (kg H

2SO

4/t)

Total S (%)

NAPP = 0

Buffering capacity/MPA = 2


0

4

8

12

16

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16

CarbNP (kg H

2SO

4/t)

Total S (%)

NAPP = 0




STUDY RESULTS

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4.6 NET ACID GENERATION (NAG)

The NAG test involves reaction of a sample with hydrogen peroxide to rapidly oxidise any sulfide minerals present. During the test both acid generation and acid neutralisation reactions can occur, the result representing a direct measure of the net amount of acid generated by the sample material. The NAGpH is a measure of the final pH of the sample material following completion of acid generation and neutralisation reactions. A NAGpH of less than (<) 4.5 indicates a material that a material may be significantly acid producing. Results for NAG capacity are presented in Table 4.

Table 4: Static Net Acid Generation results for the samples tested

Drill Hole ID

Depth From (m)

pH pHFOX NAGpH NAG4.5

(kg H2SO4/t) NAG7.0

(kg H2SO4/t)

PINC164 3 7.69 5.85 5.7 <0.5 4.0

PINC164 15 7.50 5.66 5.7 <0.5 1.8

PINC164 72 9.45 8.80 6.7 <0.5 <0.5

PINC171 33 7.39 5.73 5.8 <0.5 2.3

PINC191 15 6.75 5.60 5.4 <0.5 5.0

PINC191 18 5.69 4.70 5.0 <0.5 4.7

PINC195 9 8.92 7.71 6.5 <0.5 <0.5

PINC195 24 8.59 7.35 5.9 <0.5 2.3

PINC195 45 9.03 10.18 7.2 <0.5 <0.5

PINC198 3 7.85 6.88 5.9 <0.5 4.5

PINC198 6 7.10 5.51 5.3 <0.5 4.7

PINC199 39 8.73 8.69 7.6 <0.5 <0.5

The NAGpH results of the samples presented in Table 4 ranged from 5.0 to 7.2 with an average pH of 6.1. None of the samples reported NAGpH less than 4.5 (i.e. no samples were indicative of sulfide oxidation).

All samples returned less than detection limit values for NAG4.5 which represents an absence of free H2SO4. A number of samples returned positive values of NAG7.0 however which can indicate oxidation of aluminium (Al) and iron (Fe) oxyhydroxides which contribute to acidification in small measures.

4.7 GEOCHEMICAL CLASSIFICATION

The single addition NAG test is used in conjunction with calculated net acid producing potential (NAPP) to classify the acid generating potential of a sample. The NAG test involves the reaction of a sample with hydrogen peroxide to rapidly oxidise all sulfide minerals contained with the sample. During the NAG test both acid generation and neutralisation occur in partnership and therefore the measured NAG pH represents a direct measurement of the net amount of acid likely to be generated by a sample. Samples are placed into one of the following categories:

Non-acid forming (NAF) - Samples classified as NAF may have a significant acid generating potential but have adequate ANC within the samples to neutralise any acidity formed. A sample is classified as NAF when it has a negative NAPP and a final NAGpH ≤4.5. PAF samples in contrast, have significant sulfur content which exceeds the sample’s inherent acid neutralising capacity.


STUDY RESULTS

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Potentially acid forming (PAF) - Samples with a PAF classification pose the risk that they will oxidise and generate acidic drainage when exposed to atmospheric conditions. A sample is generally defined as PAF when it has a positive NAPP and a final NAGpH <4.5.

Uncertain (UC) - An uncertain classification is used when there is a conflict between the NAPP and NAG results (i.e. when the NAPP if positive and the NAGpH <4.5). Uncertain samples require more detailed investigation to determine the acid potential.

None of the samples tested fall below pH 4.5 suggesting that the samples are non-acid generating. On the basis of the Total S results, only three samples were marginally classified as UC (NAF) with the other samples classified as NAF. The results from the assessment based on the Sulfide S data were found to be similar to those from the Total S data, with all but three samples classified as NAF. The three samples that did not classify as NAF were marginally classified as UC (NAF).

A large proportion of samples plot on the NAF/UC border but are less of a risk in terms of acid generation than these results and definitions suggest. The results show that the majority of the samples can be considered barren, with little acid generation capacity or acid neutralising potential, and are therefore considered to be a low risk in terms of ARD production.


HAWTHORN RESOURCES Figure 8: Geochemical classification plots



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4.8 MULTI-ELEMENT COMPOSITION

The multi-element composition of the representative waste materials tested in this investigation is presented in Table 5 and Table 6. Metal contents were compared with the DEC Ecological Investigation Limits (EILs) (DEC, 2010); the EILs represent screening levels within which to provide a first-pass or Tier 1 level assessment of a site.

Table 5: Multi-element composition of selected samples from drill holes PINC164, PINC171, and PINC191

Drill Hole ID PINC164 PINC164 PINC164 PINC171 PINC191 PINC191

Depth (m) 3 15 72 33 15 18

Element LOR EIL

Silver, Ag 0.05 - <0.05 <0.05 0.16 <0.05 <0.05 <0.05

Aluminium, Al 10.00 - 17800 20900 24800 17100 4720 4470

Arsenic, As 0.20 20.0 0.4 0.3 0.8 1.2 0.5 1.2

Boron, B 5.00 - 7 8 <5 7 6 <5

Barium, Ba 0.10 300.0 86.0 110.0 310.0 150.0 38.0 180.0

Cadmium, Cd 0.05 3.00 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

Cobalt, Co 0.10 50.0 5.4 15.0 19.0 13.0 0.9 <0.1

Chromium, Cr 0.05 50.00 31.00 85.00 100.00 49.00 15.00 8.80

Copper, Cu 0.10 100.0 34.0 17.0 19.0 17.0 28.0 38.0

Iron, Fe 5.00 - 30000 46000 39000 39000 24000 33000

Mercury, Hg 0.02 1.00 <0.02 <0.02 <0.02 <0.02 0.07 0.08

Manganese, Mn 0.20 500.0 110.0 71.0 380.0 120.0 49.0 150.0

Molybdenum, Mo 0.50 40.0 0.8 0.8 1.2 0.8 1.3 1.4

Nickel, Ni 1.00 60 27 49 53 32 4 22

Lead, Pb 0.50 600.0 1.1 1.5 1.2 <0.5 0.5 1.1

Antimony, Sb 0.05 - <0.05 0.07 <0.05 0.18 0.06 <0.05

Selenium, Se 0.05 - 0.42 0.09 0.12 0.12 0.17 0.17

Tin, Sn 0.50 50.0 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Strontium, Sr 0.20 - 3.8 2.5 6.7 13.0 3.1 3.8

Thorium, Th 0.05 - 2.90 2.00 3.50 2.50 2.40 3.20

Uranium, U 0.01 - 0.89 0.25 0.15 0.26 0.41 0.65

Vanadium, V 0.20 50.0 53.0 60.0 60.0 52.0 40.0 21.0

Zinc, Zn 5.00 200 38 51 65 49 11 22

Note: Results are in mg/kg units; No guideline is indicated by (-); Values in bold exceed the EIL (DEC, 2010)

For drill holes PINC164, PINC171, PINC191, there were two elements where the results were found to marginally exceed and one element result found to exceed the EILs. Barium, Ba, in drill hole PINC164 at depth 72 m was marginally elevated. The EIL for Vanadium, V, was exceeded for the three samples from PINC164 at depths 3 m, 15 m and 72 m and for the one sample from PINC171 at depth 72 m. The Chromium, Cr, EIL was exceeded for two samples from PINC164 at depths 15 m and 72 m.


STUDY RESULTS

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Table 6: Multi-element composition of selected samples from drill holes PINC195, PINC198, and PINC199


Depth (m) 9 24 45 3 6 39

Element LOR EIL

Silver, Ag 0.05 - <0.05 <0.05 <0.05 <0.05 <0.05 <0.05

Aluminium, Al 10.00 - 5970 16200 14900 10700 10800 22000

Arsenic, As 0.20 20.0 0.7 1.8 0.7 1.2 0.4 1.2

Boron, B 5.00 - 8 6 <5 42 27 9

Barium, Ba 0.10 300.0 40.0 160.0 53.0 70.0 21.0 350.0

Cadmium, Cd 0.05 3.00 <0.05 <0.05 0.07 <0.05 <0.05 <0.05

Cobalt, Co 0.10 50.0 1.3 16.0 15.0 <0.1 <0.1 68.0

Chromium, Cr 0.05 50.00 22.00 38.00 30.00 89.00 230.00 140.00

Copper, Cu 0.10 100.0 16.0 29.0 25.0 15.0 14.0 35.0

Iron, Fe 5.00 - 30000 40000 36000 46000 66000 50000

Mercury, Hg 0.02 1.00 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02

Manganese, Mn 0.20 500.0 74.0 200.0 520.0 120.0 160.0 2200.0

Molybdenum, Mo 0.50 40.0 0.6 0.9 1.6 0.9 1.0 1.0

Nickel, Ni 1.00 60 10 35 32 12 13 130

Lead, Pb 0.50 600.0 1.7 2.2 1.3 2.9 5.4 3.1

Antimony, Sb 0.05 - <0.05 <0.05 <0.05 0.07 0.08 <0.05

Selenium, Se 0.05 - 0.10 0.25 0.10 0.31 0.47 0.19

Tin, Sn 0.50 50.0 <0.5 <0.5 <0.5 0.6 <0.5 <0.5

Strontium, Sr 0.20 - 15.0 8.3 28.0 11.0 4.1 8.3

Thorium, Th 0.05 - 2.80 2.80 2.90 3.70 4.70 3.40

Uranium, U 0.01 - 0.42 0.81 0.25 1.20 1.50 0.73

Vanadium, V 0.20 50.0 41.0 56.0 36.0 86.0 110.0 64.0

Zinc, Zn 5.00 200 12 67 49 18 19 120

Note: Results are in mg/kg units; No guideline is indicated by (-); Values in bold exceed the EIL (DEC, 2010)

For drill holes PINC195, PINC198, PINC199, there were three element results where the results were found to marginally exceed and three element results found to exceed the EILs. Drill hole PINC199 at depth 39 m marginally exceeded the EILs for Barium, Ba, Cobalt, Co and Vanadium, V. Drill hole PINC199 also exceeded the EILs for Chromium, Cr, Manganese, Mn, and Nickel, Ni. Drill hole PINC198 at depths 3 m and 6 m exceeded the EILs for Chromium, Cr, and Vanadium, V. The results for PINC195 only marginally exceeded the EILs limits for Manganese, Mn, at depth 45 m and Vanadium, V, at depth 24 m.

The EILs do not take into account mineralized zones, which can have elevated metal and metalloid contents exceeding the EIL criteria. Site specific information therefore needs to be used in conjunction with the EILs to access the applicability of the criteria values. In this case the EILs were compared with the Average Crustal Abundances (ACA) expected for the various elements tested, shown in Table 7 and Table 8, in order to provide a context within which to interpret the EILs.


STUDY RESULTS

25

The relative element enrichment of the 12 samples was determined using the Geochemical Abundance Index (GAI), through Equation 1:

log1.5 ∗

Where: C = element content in sample (mg/kg) ACA = average crustal abundance (Bowen, 1979)

A GAI of zero (0) indicates that the content of the element is less than, or similar to, the ACA. A GAI of 3 corresponds to a 12-fold enrichment above the ACA. While a GAI of 6 indicates a 96-fold or greater enrichment above the ACA. In general, a GAI greater than (>) 3 indicates significant enrichment. Elemental compositions were compared against the DEC EILs (DEC, 2010) to identify metals and metalloids that, if present, may pose a risk to the surrounding environment or to environmental values as a result of non-acid metalliferous drainage.

Table 7: Global Abundance Index for the various metals and metalloids for drill holes PINC164, PINC171 and PINC191


Depth (m) 3 15 72 33 15 18

Element ACA

Silver, Ag 0.07 0 0 1 0 0 0

Aluminium, Al 82000 0 0 0 0 0 0

Arsenic, As 1.50 0 0 0 0 0 0

Boron, B 10 0 0 0 0 0 0

Barium, Ba 500 0 0 0 0 0 0

Cadmium, Cd 0.11 0 0 0 0 0 0

Cobalt, Co 20 0 0 0 0 0 0

Chromium, Cr 100 0 0 0 0 0 0

Copper, Cu 50 0 0 0 0 0 0

Iron, Fe 41000 0 0 0 0 0 0

Mercury, Hg 0.05 0 0 0 0 0 0

Manganese, Mn 950 0 0 0 0 0 0

Molybdenum, Mo 1.5 0 0 0 0 0 0

Nickel, Ni 80 0 0 0 0 0 0

Lead, Pb 14 0 0 0 0 0 0

Antimony, Sb 0.2 0 0 0 0 0 0

Selenium, Se 0.05 2 0 1 1 1 1

Tin, Sn 2.2 0 0 0 0 0 0

Strontium, Sr 370 0 0 0 0 0 0

Thorium, Th 12 0 0 0 0 0 0

Uranium, U 2.4 0 0 0 0 0 0

Vanadium, V 160 0 0 0 0 0 0

Zinc, Zn 75 0 0 0 0 0 0


STUDY RESULTS

26

Table 8: Global Abundance Index for the various metals and metalloids for drill holes PINC195, PINC198 and PINC199


Depth (m) 9 24 45 3 6 39

Element ACA

Silver, Ag 0.07 0 0 0 0 0 0

Aluminum, Al 82000 0 0 0 0 0 0

Arsinic, As 1.50 0 0 0 0 0 0

Boron, B 10 0 0 0 1 1 0

Barium, Ba 500 0 0 0 0 0 0

Cadmium, Cd 0.11 0 0 0 0 0 0

Cobalt, Co 20 0 0 0 0 0 1

Chromium, Cr 100 0 0 0 0 1 0

Copper, Cu 50 0 0 0 0 0 0

Iron, Fe 41000 0 0 0 0 0 0

Mecury, Hg 0.05 0 0 0 0 0 0

Manganese, Mn 950 0 0 0 0 0 1

Molybdenum, Mo 1.5 0 0 0 0 0 0

Nickel, Ni 80 0 0 0 0 0 0

Lead, Pb 14 0 0 0 0 0 0

Antimony, Sb 0.2 0 0 0 0 0 0

Selenium, Se 0.05 0 2 0 2 3 1

Tin, Sn 2.2 0 0 0 0 0 0

Strontium, Sr 370 0 0 0 0 0 0

Thorium, Th 12 0 0 0 0 0 0

Uranium, U 2.4 0 0 0 0 0 0

Vanadium, V 160 0 0 0 0 0 0

Zinc, Zn 75 0 0 0 0 0 0

Note: Values in bold represent significant enrichment compared to the ACA for Table 7 and Table 8.

No samples were found to be significantly enriched, meaning the samples tested had GAI results of 3 or below. These results indicate that in general the level of elemental abundance measured within the samples is within the range expected for natural background conditions.


CONCLUSIONS

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5 CONCLUSIONS

SWC were engaged by Hawthorn Resources to undertake a geochemical characterisation. As part of the environmental approvals for the mine, this geochemical characterisation was completed to identify the presence or absence of potential ARD, highly saline materials and other problematic materials, which may have an impact on the surrounding environment.

In order to determine the presence of ARD in the material from Hawthorn Resources, drill holes were selected as representative of the site and 201 samples collected to determine a range of parameters including pH, pHFOX, EC as well as more detailed ARD characterisation on 12 of those samples.

The major findings from the investigation of the 12 samples following the screen test were:

The results of pH and pHox testing on the 201 samples selected for screen analysis showed that the majority of materials were alkaline in nature, with pHox testing indicating that appreciable sulfides were unlikely to be present.

The results of EC testing on the 201 samples selected for screen analysis showed that the salinity levels were generally low (i.e. non-saline) indicating that excessive salinity in oxide or waste rock material would not impede future rehabilitation efforts.

The results from the geochemical classification show that the majority of the materials had a negative NAPP and were classified as NAF, with three samples returning UC (NAF) classifications.

Total metal content of all materials tested was low based on the EILs however there were five (5) instances where the results marginally exceeded the EILs and five (5) instances where the results exceeded the EILs;. PINC199 at depth 39 m marginally exceeded the EILs for Barium, Ba, Cobalt, Co and Vanadium, V. The results for PINC195 marginally exceeded the EILs limits for Manganese, Mn, at depth 45 m and

Vanadium, V, at depth 24 m. Drill hole PINC199 exceeded the EILs for Chromium, Cr, Manganese, Mn, and Nickel, Ni. Drill hole PINC198 at depths 3 m and 6 m exceeded the EILs for Chromium, Cr, and Vanadium, V.

Based on the GAI, the total metal content of the sample results indicated that in general the level of elemental abundance measured is within the range expected for natural background conditions.

No specific materials handling measures will need to be implemented as the materials tested showed no adverse geochemical properties.


REFERENCES

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6 REFERENCES

AMIRA (2002) ARD Test Handbook. Project 387A. Prediction and Kinetic Control of Acid Mine Drainage. AMIRA International. Melbourne, Australia.

Bowen, H. J. M. (1979) Environmental Chemistry of the Elements. Academic Press. New York, USA. DEC (2010) Assessment Levels for Soils, Sediment and Water. In Contaminated Sites Management Series. February.

Department of Environment and Conservation, Government of Western Australia. Perth WA. DEC (2013) Idenitification and Investigation of Acid Sulfate Soils and Acidic Landscapes, Acid Sulfate Soils Guideline

Series. March. Contaminated Sites Branch, Environmental Regulation Division: Department of Environment and Conservation. Perth, Western Australia.

Groenwald, P. B., Painter, M. G. M., Roberts, F. I., McCabe, M., Fox, A. (2000) 1:100,000 geology Menzies to Norseman - an explanatory note. In: Western Australian Geological Survey, p. 53

Price, W. A. (2009) Prediction Manual for Drainage Chemistry from Sulphidic Geologic Materials. MEND Report 1.20.1. CANMET Mining and Mineral Sciences Laboratories. Smithers, British Columbia, Canada.

Stone, Y., Ahern, C. and Blunden, B. (1998) Acid Sulfate Soils Manual 1998. Acid Sulfate Soil Management Advisory Committee. Wollongbar, NSW, Australia.

Swager, C. P. (1995) Geology of the Pinjin 1:100,000 sheet. In: Western Australia Geological Survey, 1:100,000 Geological series explanatory notes

White, A. F. and Brantley, S. L. (1995) Chemical weathering rates of silicate minerals: an overview. Chemical Weathering Rates of Silicate Minerals, 31, 1-22.

Williams, R. E. (1996) Pinjin Project Mining Leases M31/78, M31/79, M31/113 and GML31/1458. Combined Annual Report for the period 5/10/95 - 4/10/96. In. Burdekin Resources N.L.

Documents

Hawthorn Resources Geochemical Characterisation · 2020. 3. 24. · 1.2 SCOPE OF WORK The scope of work (SOW) completed by SWC for this project included: Review of existing geological