Heron Resources Limited (ASX:HRR, “Heron” or the
“Company”) is pleased to report results from a
metallurgical testwork program undertaken on the shallow G2 Lens at
its wholly owned Woodlawn Zinc-Copper Project in New South Wales,
Australia. The G2 Lens represents the first mineralisation to be
accessed in the underground operation and is not currently reported
within the operations Ore Reserves.
- Shallow G2 Lens represents the first mineralisation to be
accessed in the underground mine
- Three mineralisation styles identified in G2 Lens:
- G2 Hanging Wall (G2HW) – high grade polymetallic mineralisation
with elevated precious metals
- G2 Main Lens (G2 Main) – polymetallic and zinc stringer
mineralisation
- G2 Copper (GC) – copper mineralisation
- Testwork on all mineralisation styles returned results
exceeding Feasibility Study metallurgical recovery assumptions
- G2HW returned very high precious metals in copper and lead
concentrates
- Further drilling scheduled to expand G2 Lens towards mine
access point
Commenting on these results Heron’s Managing Director, Mr Wayne
Taylor said: “The Company is extremely pleased with the developing
tonnage and the recently received metallurgical testwork results
for the G2 Lens. The results demonstrate that a significantly
better concentrate product quality can be produced at higher
recoveries in most cases when compared to the assumptions applied
in the Woodlawn Feasibility Study (FS). All three mineralisation
styles performed extremely well and, while of very limited tonnage,
the precious metal levels in the G2HW copper and lead concentrates
were particularly exciting. We are looking to target an expansion
to the G2 and G2HW mineralisation in the expanded drilling program
that is currently underway.”
G2 Lens Metallurgical Test
Work
The shallow position of the G2 Lens has resulted
in this area becoming a focus for recent exploration activity. The
first concerted phase of work in 2017 resulted in the reporting of
an initial Mineral Resource for this area (refer to Mineral
Resource table at the end of this release and Heron’s release to
the ASX dated 13 November 2017). The first phase of work did not
close off the lens to the south (towards the mine access point) and
the initial drill holes in the second phase intersected strong
mineralisation in both the G2 and G2HW. While the G2 Lens is
currently of limited tonnage, it represents the likely first
production source for the underground operation. A
metallurgical testwork program was undertaken to assess processing
performance and the resulting zinc, copper and lead concentrate
qualities. Diamond drill core from this area has resulted in the
identification of three different mineralisation styles -
polymetallic containing high grade precious metals (G2HW);
polymetallic and zinc stringer (G2 Main); and copper mineralisation
(GC).
Drill core samples were composited to provide
representative samples of the expected run-of-mine ore (with
dilution included) for each of the three mineralisation types.
Testwork program design started with the standard flotation
reagent regime used in the Feasibility Study (FS) and involved
further optimisation tests. The testwork was carried out at
AMML laboratories in Gosford, NSW (AMML). AMML have provided
metallurgical services for Heron since the Company’s involvement in
the project, and have considerable experience with flotation of
mineral concentrates.
The testwork results are provided in Table 1
below. Copper and lead concentrates are of very good quality,
and are well above the targets that were established during the FS.
Zinc concentrate grades and recoveries are also good, being
on or slightly better than target. Also, the G2HW sample
contained notably higher grades of precious metals in the feed ore
with resulting elevated grades reported through to the copper and
lead concentrates.
The strong results returned for the G2
mineralisation provides the Company with confidence that these ore
types will be able to be readily processed through the plant and
may provide the project with enhanced revenue results in the early
stages of underground mining operations.
Table 1: G2 Lens Metallurgical Test
Results May 2018
|
|
|
Feasibility StudyUG Feed |
GC Copper |
G2 Main |
G2HW |
Head Grades |
Copper |
% |
1.3 |
1.3 |
0.4 |
0.7 |
|
Lead |
% |
2.6 |
0.0 |
2.0 |
6.2 |
|
Zinc |
% |
7.2 |
0.1 |
5.4 |
10.2 |
|
Silver |
ppm |
50.0 |
5.0 |
12.0 |
504.0* |
|
Gold |
ppm |
0.9 |
N/A |
N/A |
4.0 |
Copper Concentrate |
Copper |
Grade % |
27.0 |
31.6 |
28.5 |
27.7 |
|
|
Cu Recovery % |
60.0 |
81.2 |
77.7 |
62.8 |
|
Silver |
Grade ppm |
|
58.0 |
200.0 |
5500.0 |
|
|
Ag Recovery % |
10.0 |
28.0 |
18.0 |
25.0 |
|
Gold |
Grade ppm |
|
0.4 |
4.0 |
17.0 |
|
|
Au Recovery % |
7.0 |
10.0 |
25.0 |
6.0 |
Lead Concentrate |
Lead |
Grade % |
45.0 |
|
56.2 |
59.6 |
|
|
Pb Recovery % |
70.0 |
|
88.3 |
89.2 |
|
Silver |
Grade ppm |
|
|
258.0 |
1900.0 |
|
|
Ag Recovery % |
46.0 |
|
60.8 |
58.0 |
|
Gold |
Grade ppm |
|
|
2.8 |
30.0 |
|
|
Au Recovery % |
30.0 |
|
26.2 |
64.0 |
Zinc Concentrate |
Zinc |
Grade % |
55.0 |
|
55.0 |
62.7 |
|
|
Zn Recovery % |
88.0 |
|
89.5 |
79.5 |
|
Silver |
Grade ppm |
|
|
19.0 |
149.0 |
|
|
Ag Recovery % |
25.0 |
|
11.9 |
6.8 |
* Result is an estimate due to mass balance and
assayed head grade discrepancy for Ag.
An exercise was undertaken to compare the
relative values of the different concentrates to that assumed in
the FS. The results show that the G2HW generated a copper
concentrate four times the value of that determined for copper
concentrates in the FS under the same commercial terms, whilst the
lead and zinc concentrates were three and two times their
respective values in the FS. In the case of the copper and
lead this was at recoveries above that assumed in the FS, with zinc
being slightly less. As previously noted, production from G2
Main and G2HW is not currently included in the FS mine plan,
which is based upon Ore Reserves only, thereby providing upside
potential to the early stage project economics.
Additional G2 Lens Drilling
The recent G2 Lens drilling has shown the
mineralisation to continue to the south and is not closed off. This
trend extends the lens towards the underground portal and for early
stage mine planning further definition of the lens extents is
required. The Company will undertake a further seven hole (1,200m)
DDH program targeting the interpreted limits of the G2 Lens to the
southeast, and infill areas to finalise mine access design and
stope planning.
Figure 1: G2 Main Long Section showing
recent drilling intercepts and planned drilling. View to
northeast.
http://www.heronresources.com/tsximages/20180508/080518_fig1.jpg
About Heron Resources
Limited:
Heron’s primary focus is the development of its
100% owned, high grade Woodlawn Zinc-Copper Project located 250km
southwest of Sydney, New South Wales, Australia.
G2 Mineral Resource Estimate 2017 (reported
in Heron’s ASX release 13 November 2017) (Cut-off
grades are 7% ZnEq for polymetallic, and 1% Cu for copper
mineralization)
Indicated Mineral Resources
Lens |
Domain |
Resource Category |
Quantity (kt) |
ZnEq (%) |
Zn (%) |
Cu (%) |
Pb (%) |
Au (g/t) |
Ag (g/t) |
G2
Main |
Polymetallic |
Indicated |
100 |
11.9 |
6.3 |
0.5 |
3.1 |
0.41 |
41 |
GC |
Copper |
Indicated |
39 |
5.5 |
0.1 |
1.5 |
0.0 |
0.36 |
10 |
Total |
Combined |
Indicated |
139 |
10.1 |
4.5 |
0.8 |
2.3 |
0.40 |
33 |
Inferred Mineral Resources
G2 Main |
Polymetallic |
Inferred |
25 |
11.9 |
6.1 |
0.4 |
3.2 |
0.76 |
46 |
G2HW |
Polymetallic |
Inferred |
6 |
54.0 |
13.7 |
0.7 |
7.9 |
6.33 |
878 |
GC |
Copper |
Inferred |
28 |
5.3 |
0.1 |
1.5 |
0.0 |
0.34 |
8 |
Total |
Combined |
Inferred |
58 |
13.3 |
4.0 |
0.9 |
2.2 |
1.16 |
117 |
Compliance Statement (JORC 2012 and
NI43-101)
The technical information in this report is
based on information reviewed by Mr. David von Perger, who is a
Member of the Australian Institute of Mining and Metallurgy
(Chartered Professional – Geology). Mr. von Perger is a full
time employee of Heron Resources Limited and has sufficient
experience, which is relevant to the style of mineralisation and
type of deposit under consideration and to the activity which he is
undertaking to qualify as a Competent Person as defined in the 2012
edition of the “Australasian Code for Reporting of Exploration
Results and “qualified person” as this term is defined in Canadian
National Instrument 43-101 (“NI 43-101”). Mr. von Perger has
approved the scientific and technical disclosure in the news
release.
Zinc equivalent calculation
The zinc equivalent ZnEq calculation takes into
account, mining costs, milling costs, recoveries, payability
(including transport and refining charges) and metal prices in
generating a Zinc equivalent value for Au, Ag, Cu, Pb and Zn.
ZnEq = Zn%+Cu%*3.12+Pb%*0.81+*Au g/t*0.86+Ag g/t*0.03. Metal
prices used in the calculation are: Zn US$2,300/t, Pb US$ 2,050/t,
Cu US$6,600/t, Au US$1,250/oz and Ag US$18/oz. It is Heron’s
view that all the metals within this formula are expected to be
recovered and sold. Metallurgical metal recoveries used for
the formula are 88% Zn, 70% Pb, 70% Cu, 33% Au and 82% Ag; these
are based on historical recoveries at Woodlawn and supported by
metallurgical test work undertaken during the 2015-16 feasibility
study.
JORC 2012 Table 1 (provides information
for drill sample collection and metallurgical methods)
Section 1: Sampling Techniques and Data - this
applies to both the elemental analysis that is relevant to the
metallurgical results plus the actual metallurgical testwork
undertaken.
(Criteria in this section applies to all
succeeding sections)
Criteria |
JORC Code explanation |
Commentary |
Sampling techniques |
- Nature and quality of sampling (eg cut channels, random chips,
or specific specialised industry standard measurement tools
appropriate to the minerals under investigation, such as down hole
gamma sondes, or handheld XRF instruments, etc). These examples
should not be taken as limiting the broad meaning of sampling.
- Include reference to measures taken to ensure sample
representivity and the appropriate calibration of any measurement
tools or systems used.
- Aspects of the determination of mineralisation that are
Material to the Public Report.
|
- Samples from the diamond-core holes are taken from HQ3 sized
core and sampled on a nominal 1 metre basis taking into account
smaller sample intervals up to geological contacts. The core
is cut in along the core orientation line (where available).
Generally in massive sulphide zones one portion is quartered for
assaying, half the core is preserved for metallurgical testing and
the remaining quarter is retained as reference material in the core
trays.
- The metallurgical samples are placed in core trays and
labelled, prior to transport to the Company’s metallurgical
laboratory, Australian Minmet Metallurgical Laboratories Pty Ltd
(AMML) in West Gosford, NSW, Australia. The samples are
stored in a freezer at Woodlawn and AMML to minimise any oxidation
prior to the testwork.
|
Drilling techniques |
- Drill type (eg core, reverse circulation, open-hole hammer,
rotary air blast, auger, Bangka, sonic, etc) and details.
|
- Diamond-core drilling is being undertaken by Sandvik DE710 rigs
with mostly HQ3 sized core being drilled. Various techniques
are employed to ensure the hole is kept within limits of the
planned position. The core is laid out in standard plastic
cores trays.
|
Drill sample recovery |
- Method of recording and assessing core and chip sample
recoveries and results assessed.
|
- The core is transported to an enclosed core logging area and
recoveries are recorded. Recoveries to date have been better
than 95%. The core is orientated where possible and marked
with 1 metre downhole intervals for logging and sampling.
|
Logging |
- Whether core and chip samples have been geologically and
geotechnically logged to a level of detail to support appropriate
Mineral Resource estimation, mining studies and metallurgical
studies.
|
- The diamond core is geologically logged by qualified
geologists. Geotechnical logging is also being undertaken on
selected sections of the core. Samples for metallurgical
testing are being kept in a freezer to reduce oxidation prior to
being transported to the metallurgical laboratory.
|
Sub-sampling techniques and sample preparation |
- For all sample types, the nature, quality and appropriateness
of the sample preparation technique.
|
- For elemental determination, all core samples are crushed then
pulverised in a ring pulveriser (LM5) to a nominal 90% passing 75
micron. An approximately 250g pulp sub-sample is taken from the
large sample and residual material stored.
- A quartz flush (approximately 0.5 kilogram of white,
medium-grained sand) is put through the LM5 pulveriser prior to
each new batch of samples. A number of quartz flushes are
also put through the pulveriser after each massive sulphide sample
to ensure the bowl is clean prior to the next sample being
processed. A selection of this pulverised quartz flush
material is then analysed and reported by the lab to gauge the
potential level of contamination that may be carried through from
one sample to the next.
- The metallurgical samples are composited based on estimated Ore
Reserve grades allowing for mining dilution. The composites
are prepared by mixing the various crushed combinations of the
original metallurgical samples together at AMML. The
composite head assay of the sample is compared to calculated head
assay as a check that the compositing and mixing procedure has been
effective.
|
Quality of assay data and laboratory tests |
- The nature, quality and appropriateness of the assaying and
laboratory procedures used and whether the technique is considered
partial or total.
- Nature of quality control procedures adopted (eg standards,
blanks, duplicates, external laboratory checks) and whether
acceptable levels of accuracy (ie lack of bias) and precision have
been established.
|
Elemental Analysis
- Sample preparation and assaying is being conducted through ALS
Laboratories, Orange, NSW with certain final analysis of pulps
being undertaken at the ALS Laboratory in Brisbane QLD.
- Gold is determined by 30g fire assay fusion with ICP-AES
analysis to 1ppb LLD.
- Other elements by mixed acid digestion followed by ICP-AES
analysis.
- Assay laboratory quality control standards (blanks, standards
and duplicates) are inserted at a rate of 5 per 35 samples for ICP
work.
Metallurgical Testwork
- The metallurgical testwork has been undertaken by AMMML under
the supervision of Heron’s Process Manager, Mr Desmond O’Sullivan
(MAusIMM).
- Only sighter tests were undertaken at this stage. That
is, no locked cycle tests have been done.
- The test followed the standard Heron processing flowsheet
described in the Woodlawn feasibility study reports available in
Heron’s website. This entailed:
- Crush to nominal 1mm size
- Pulverise to 75 micron
- Conduct Cu float
- Pulverise to 30 micron and conduct Zn & Pb float
- Pulverise rougher concentrate to 15 micron and produce cleaner
Cu, Zn and Pb floats.
- Results are reported for grade and recovery for the Cu, Zn and
Pb concentrates.
- Au and Ag grades and recoveries are also reported for the 3
concentrates.
- A mass balance calculation is performed as part of the checking
procedure.
- Some 5-6 float tests were performed on each of the 3 samples
types with only reagents being adjusted each time to optimise
results. The final optimised test was then re-done to check
the repeatability of the result.
- All assays were determined through ALS Laboratory in Brisbane,
Australia,
|
Verification of sampling and assaying |
- The verification of significant intersections by either
independent or alternative company personnel.
- Documentation of primary data, data entry procedures, data
verification, data storage (physical and electronic)
protocols.
- Discuss any adjustment to assay data.
|
- An internal review of results was undertaken by Company
personnel. No independent verification was undertaken at this
stage.
- All field and laboratory data has been entered into an industry
standard database (DataShed) using a contract database
administrator (DBA) in the Company’s Perth office. Validation
of both the field and laboratory data is undertaken prior to final
acceptance and reporting of the data.
- Quality control assay samples from both the Company and the
Laboratory are assessed by the DBA and reported to the Company
geologists for verification. All assay data must pass this
data verification and quality control process before being
reported.
|
Location of data points |
- Accuracy and quality of surveys used to locate drill holes
(collar and down-hole surveys), trenches, mine workings and other
locations used in Mineral Resource estimation.
|
- The drill collars were initially located with a combination of
handheld GPS and licenced surveyor using a DGPS system, with
accuracy of about 1m. The final drill collars are “picked up”
by a licenced surveyor with accuracy to 1 centimetre.
- While drilling is being undertaken, downhole surveys are
conducted using a downhole survey tool that records the magnetic
azimuth and dip of the hole. These recordings are taken
approximately every 30 metres downhole. As a check, certain
holes are also being surveyed with gyroscopic methods, with some 10
percent of holes drilled in the current program also surveyed by
this method after drilling has been completed.
|
Data spacing and distribution |
- Data spacing for reporting of Exploration Results.
- Whether the data spacing and distribution is sufficient to
establish the degree of geological and grade continuity appropriate
for the Mineral Resource and Ore Reserve estimation procedure(s)
and classifications applied.
- Whether sample compositing has been applied.
|
- The diamond drilling is mostly following-up in various
directions from previous intercepts with a nominal spacing in the
range 20-40m. This drill hole spacing will be sufficient to
provide Mineral Resource estimates in the future.
|
Orientation of data in relation to geological structure |
- Whether the orientation of sampling achieves unbiased sampling
of possible structures and the extent to which this is known,
considering the deposit type.
|
- The drilling orientation is designed to intersect the
mineralised lenses at a close to perpendicular angle. The
mineralised lenses are dipping at approximately 50-70 degrees to
the west and the drilling is approximately at 60 degrees to the
east. This will vary from hole to hole.
|
Sample security |
- The measures taken to ensure sample security.
|
- The cut core samples are secured in green plastic bags and are
being transported to the ALS laboratory in Orange, NSW via a
courier service or with Company personnel/contractors.
|
Audits or reviews |
- The results of any audits or reviews of sampling techniques and
data.
|
- A review and assessment of the assay (ALS) laboratory
procedures was under taken by Company personnel in late 2014 and
again in 2017 resulting in some changes to their sample pulverising
procedure.
- The metallurgical laboratory (AMML) procedures are reviewed by
Company personnel from time to time during visits to their
facilities.
|
Section 2: Reporting of Results (this provide general
information and background to the results)
(Criteria listed in the preceding section also
apply to this section.)
Criteria |
JORC Code explanation |
Commentary |
Mineral tenement and land tenure status |
- Type, reference name/number, location and ownership including
agreements or material issues with third parties such as joint
ventures, partnerships, overriding royalties, native title
interests, historical sites, wilderness or national park and
environmental settings.
- The security of the tenure held at the time of reporting along
with any known impediments to obtaining a licence to operate in the
area.
|
- The Woodlawn project is located 250km south-west of Sydney in
the state of New South Wales. The area is on the Great
Australian Dividing range and has an elevation around 800m above
sea-level. The mineral and mining rights to the project are
owned 100% by the Company through the granted, special (Crown and
Private Land) mining lease 20 (SML20). The lease has been
renewed to the 16 November 2029.
- The project area is on private land owned by Veolia who operate
a waste disposal facility that utilises the historical open-pit
void. An agreement is in place with Veolia for the Company to
purchase certain sections of this private land to facilitate future
mining and processing activities. A cooperation agreement is
also in place between Veolia and the Company that covers drilling
and other exploration activities in the area.
|
Exploration done by other parties |
- Acknowledgment and appraisal of exploration by other
parties.
|
- The Woodlawn deposit was discovered by the Jododex JV in 1970
and open-pit mining began in 1978 and continued through to 1987.
The project was bought outright by Rio Tinto Ltd (CRA) in 1984 who
completed the open-pit mining. Underground operations commenced in
1986 and the project was sold to Denehurst Ltd in 1987 who
continued underground mining up until 1998. The mineral
rights to the project were then acquired by TriAusMin Ltd in 1999
who conducted studies on a tailings re-treatment process and
further underground operations. Heron took 100% ownership of
the project in August 2014 following the merger of the two
companies. Some 980 surface and underground drill holes have
been completed on the project to date and various studies
undertaken.
|
Geology |
- Deposit type, geological setting and style of
mineralization.
|
- The Woodlawn deposit comprises volcanogenic massive sulphide
mineralisation consisting of stratabound lenses of pyrite,
sphalerite, galena and chalcopyrite. The mineralisation is
hosted in the Silurian aged Woodlawn Felsic Volcanic package of the
Goulburn sub-basin on the eastern side of the Lachlan Fold
Belt.
|
Drill hole Information |
-
- A summary of all information material to the understanding of
the exploration results including a tabulation of the following
information for all Material drill holes:
|
- A table detailing the drill hole information is given in the
body of the report.
|
Data aggregation methods |
- In reporting Exploration Results, weighting averaging
techniques, maximum and/or minimum grade truncations (eg cutting of
high grades) and cut-off grades are usually Material and should be
stated.
- Where aggregate intercepts incorporate short lengths of high
grade results and longer lengths of low grade results, the
procedure used for such aggregation should be stated and some
typical examples of such aggregations should be shown in
detail.
|
- The reported assays are weighted for their assay interval
width. The majority of the assay interval widths are 1 metre, but
this weighting does take into account the non 1 metre intervals and
weights the average assay results accordingly.
- For the results reported here no weighting was included for
specific gravity (SG) measurements that have been taken for all
sample intervals as the samples within the intervals are of a
similar SG.
|
Relationship between mineralization widths and intercept
lengths |
- These relationships are particularly important in the reporting
of Exploration Results.
- If the geometry of the mineralisation with respect to the drill
hole angle is known, its nature should be reported.
|
- The massive sulphide zone intercepted in the drilling to date
is at an angle to the drill axis and therefore the true width is
estimated to be some 0.8 of down-hole width. That is, a
down-hole intercept of 16m equates to a true width of 12m.
This is only an approximation at this stage and will be better
estimated as the orientation of the Lenses is better defined.
|
Diagrams |
- Appropriate maps and sections (with scales) and tabulations of
intercepts should be included for any significant discovery being
reported These should include, but not be limited to a plan view of
drill hole collar locations and appropriate sectional views.
|
- Where relevant, a diagram showing the hole positions relevant
for current phase of exploration is included in the release.
Other maps and diagrams showing the location of the Woodlawn
Project are included in other recent Company releases.
|
Balanced reporting |
- Where comprehensive reporting of all Exploration Results is not
practicable, representative reporting of both low and high grades
and/or widths should be practiced to avoid misleading reporting of
Results.
|
- The reporting is considered to be balanced and all relevant
results have been disclosed for this current phase of
exploration.
|
Other substantive exploration data |
- Other exploration data, if meaningful and material, should be
reported including (but not limited to): geological observations;
geophysical survey results; geochemical survey results; bulk
samples – size and method of treatment; metallurgical test results;
bulk density, groundwater, geotechnical and rock characteristics;
potential deleterious or contaminating substances.
|
- Selected drill holes are being cased with 50 millimetre PVC
tubing for potential down-hole DHEM surveying which is undertaken
on the majority of the holes drilled.
- Geotechnical logging is undertaken nominally 25m either side of
the massive sulphide lenses.
- Archimedes method SG measurements are determined for all
sampled intervals.
|
Further work |
- The nature and scale of planned further work (eg tests for
lateral extensions or depth extensions or large-scale step-out
drilling).
|
- The fifth phase of drilling at Woodlawn commenced in March 2018
with some 2,000 to be drilled initially. The program was primarily
designed to infill and expand the Lisa and G2 Lens positions. This
program is ongoing and will be expanded to better delineate the G2
mineralisation at its southern end (additional 7 holes for
1,200m).
- The results of the metallurgical are being further assessed,
however, no further testwork on G2 material is currently
planned.
|
For further information, please visit www.heronresources.com.au or contact:
Australia:
Mr Wayne Taylor
Managing Director and Chief Executive Officer
Tel: +61 2 9119 8111 or +61 8 6500 9200
Email: heron@heronresources.com.au
Jon Snowball
FTI Consulting
+61 2 8298 6100
jon.snowball@fticonsulting.com