Sandfire Resources America Inc. (“Sandfire America” or the
“Company”) is pleased to announce its maiden Mineral
Reserve and the results of the Feasibility Study (the
“
Feasibility Study”) for the Johnny Lee deposit at
its Black Butte Copper Project in White Sulphur Springs, Montana,
USA, pursuant to National Instrument 43-101 – Standards of
Disclosure for Mineral Projects
(“
NI 43-101”).
The Feasibility Study relates solely to Mineral
Reserves located on the Johnny Lee copper deposit, the cornerstone
deposit at the Black Butte Copper Project (the "Johnny Lee
Deposit" or the “Project”).
The Company is also pleased to announce an
updated Mineral Resource for the Lowry copper deposit (the
"Lowry Deposit"), which is located approximately
3km south-east of the Johnny Lee Deposit, pursuant to
NI 43-101.
All dollars in this announcement are US dollars
unless otherwise stated.
Feasibility Study Highlights:
- Maiden Mineral Reserve of 8.8 million tonnes at 2.6%
copper for 226,100 tonnes of contained copper defined
for the Johnny Lee Upper and Lower Copper Zones.
- The Project has been designed to meet or exceed all of
the standards and obligations required under the Project’s
stringent Mine Operating Permit conditions.
- The Johnny Lee Deposit underpins an 8-year mine
life and is designed to be mined at 1.2 million
tonnes of ore per annum.
- Forecast production totaling 805,000 dry metric tonnes of
copper concentrate containing 189,500 tonnes of copper
metal over the life of the mine.
- Average annual production of ~23,000 tonnes of copper
metal at a C1 cash cost of
US$1.51/lb.
- The Project is forecast to generate $1.3 billion in
gross sales and $518 million in pre-tax net
cashflow during mine operations, based on a copper price
of US$3.20/lb.
- The Project has a pre-tax
NPV5% of $124.9 million
(IRR=17%) and a post-tax NPV5% of $77.6 million (IRR=13%).
- Average annual post-tax cashflows of $77.8 million per
annum for the first five years of operations.
- Construction capital cost of $274.7
million.
- Updated Inferred Mineral Resource of 8.3 million tonnes
at 2.4% copper for 199,500 tonnes of contained copper
completed for the Lowry Deposit, 3km south-east of Johnny Lee:• The
updated Mineral Resource is based on updated geological modeling,
resource estimation, classification, and mineralogy/recovery
assumptions.• The Lowry Deposit is not covered by the current
environmental permits and will need to undergo a further permitting
and approvals process.
Commenting on the Feasibility Study completion
and key outcomes, Sandfire America CEO and Project Director Rob
Scargill stated: “The positive outcomes of the Feasibility Study
show that we can deliver a robust underground mining project at
Black Butte that meets the world’s highest environmental standards
while at the same time creating jobs, opportunities and significant
direct and indirect benefits for the State of Montana.
“This is one of the highest-grade copper
deposits in the world and one of the very few fully-permitted and
development-ready copper assets globally. The Feasibility Study
delineates a clear pathway to unlocking its value for our
shareholders in a manner that is consistent with world-best
practice in ESG and community engagement.
“The Project will employ 240 full-time, highly
paid employees along with 20-30 full-time contractors as well as
providing significant economic benefits for all stakeholders in the
local community and Montana at large. We have already commenced
pre-construction earthworks on the site employing over 30 Montanans
through local contractors, in addition to our own dedicated
team.
“We are excited about the opportunity to move
this high-quality project forward and position it to meet what is
increasingly emerging as a new era of demand for copper driven by
its growing use as a key input to renewable and clean energy
applications, including the electrification of transportation
globally.
“Meanwhile, the updated Mineral Resource for the
Lowry Deposit demonstrates the significant exploration potential at
the Black Butte Copper Project. The deposit is located just 1.8km
from the underground access portal for the Johnny Lee Deposit and
is a high priority for our next round of exploration.”
Black Butte Copper Project
Overview
The Black Butte Copper Project consists of 3,223
hectares of fee simple lands under mineral lease by the Company and
525 unpatented mining claims on U.S. Forest Service Lands (USFS),
leased by the Company, totaling 4,037 hectares. The Black Butte
Copper Project is located in south-central Montana in Meagher
County, 27 km north of White Sulphur Springs.
The Johnny Lee copper deposit was discovered by
a joint venture between Cominco American Inc. and Utah
International in 1985. The Johnny Lee copper deposit is comprised
of two zones of mineralization: an upper copper zone
(“UCZ”) situated at depths of 40m – 210m below
surface and an underlying lower copper zone
(“LCZ”) at depths of 340m – 520m below
surface.
A mine operating plan (“MOP”)
application for the extraction of mineralized rock from both zones
of the Johnny Lee Deposit was submitted to the Montana Department
of Environmental Quality (“MT DEQ”) in December
2015 and, following revisions, was deemed to be complete and
compliant. A draft MOP permit was issued by the MT DEQ on
September 18, 2017 and the Environmental Impact Statement
(“EIS”) process started soon thereafter and was
completed on March 13, 2020. The MOP proposes underground mining of
the Johnny Lee Deposit using a drift and fill mining method and
production of a copper concentrate by milling and froth flotation.
Mill tailings will be used for underground paste-fill support and
the surplus deposited in a double-lined cemented tailings storage
facility.
A legal challenge to the issuing of the Mine
Operating Permit has been filed in the 14th Judicial Court of
Montana. The same parties have also objected to the Company’s
leasing of mitigation water rights that have preliminary approval
from the Montana Department of Natural Resources and Conservation
(MT DNRC). The water rights have to be finalized prior to start of
production.
To date, the legal challenge has not resulted in
any interference with development activities and construction
continues. While the Company does not believe that either of these
challenges have any merit, they do have the potential to delay the
development timeline.
The Lowry Deposit, a similar style copper
deposit to the Johnny Lee Deposit, is located approximately 3km to
the south-east of the Johnny Lee Deposit.
For further details about the Project, please go
to the Sandfire Resources America Inc. website at
www.sandfireamerica.com.
Johnny Lee Deposit - Mineral
Reserve
The Mineral Reserve was prepared in accordance
with Canadian Institute of Mining and Metallurgy and Petroleum
(“CIM”) Definition Standards and will be supported
by a technical report (the “Technical Report”)
pursuant to NI 43-101, to be published and filed on the Company’s
website and SEDAR profile within 45 days.
A net smelter return (“NSR”)
was calculated for each block in a block model based on
metallurgical recovery, grade, and payability factors. Mine design
shapes were created to reach a cut-off value of $70/t which was
used for guidance to create detailed designs. All mining blocks
then had dilution and recovery applied to them and were tested for
economic viability. The mining stope and level designs with
dilution and mining recovery factors applied determined the Mineral
Reserve shown in Table 1.
Table 1 – Mineral Reserve Johnny Lee Deposit
Class |
Diluted Tonnes |
Cu Grade |
Contained Cu Metal(t) |
Proven |
1,998,000 |
3.0% |
60,700 |
Probable |
6,804,000 |
2.4% |
165,400 |
Total |
8,802,000 |
2.6% |
226,100 |
Notes:
1. The qualified person, as such term is
defined, for the Mineral Reserve is Brad Evans MAusIMM CP(Mining).
2. Effective date: October 19, 2020. All Mineral Reserves have been
estimated in accordance with CIM definitions, as required under NI
43-101. 3. Mineral reserves were estimated using a $3.10 /lb copper
price and a NSR cut-off value of $70/t. 4. Tonnages are rounded to
the nearest 1,000 t, metal grades are rounded to one decimal place.
All units are metric. 5. Rounding as required by reporting
guidelines may result in summation differences. 6. Average
metallurgical recovery is 84%
The Mineral Reserves identified in Table 1
comply with CIM definitions and standards for a NI 43-101 Technical
Report. Detailed information on mining, processing, metallurgical,
and other relevant factors demonstrate, at the time of the
Technical Report, that economic extraction is justified. The
Feasibility Study did not identify any mining, metallurgical,
infrastructure or other relevant factors that may materially affect
the estimates of the Mineral Reserves or potential production.
Table 2 below shows the Mineral Reserves broken out by zone.
Table 2 – Mineral Reserves for the Johnny Lee
Deposit by Zone
Zone |
Class |
Diluted Tonnes |
Cu Grade |
Contained Cu Metal(Tonnes) |
UCZ |
Proven |
1,159,000 |
2.2 |
% |
25,900 |
Probable |
5,693,000 |
2.1 |
% |
116,900 |
Total |
6,852,000 |
2.1 |
% |
142,800 |
LCZ |
Proven |
839,000 |
4.1 |
% |
34,800 |
Probable |
1,111,000 |
4.4 |
% |
48,500 |
Total |
1,950,000 |
4.3 |
% |
83,300 |
Grand Total |
Total |
8,802,000 |
2.6 |
% |
226,100 |
Economic Analysis
The Feasibility Study economic analysis is based
on the Johnny Lee Deposit Mineral Reserves. The Feasibility Study
does NOT include the Lowry Deposit.
The copper price assumption adopted for the base
case is $3.20/lb from the start of production.
The Project’s pre-tax NPV at a 5% discount rate
is estimated to be US$124.9M with an IRR of 17%. Cash Costs (C1)
are estimated to be $1.51/lb of copper. The life-of-mine all-in
sustaining cost is estimated to be $1.63/lb of copper. Payback of
start-up capital is achieved approximately 3 years from
commissioning.
Table 3 – Economic Sensitivity Analysis for the
Johnny Lee Deposit
Black Butte Copper Project - FS
Case |
Pre-Tax NPV Sensitivity Impacts |
Sensitivity Variables |
Confidence Ranges |
$ Millions , Pre-Tax |
NPV @ 5% |
Worst |
Best |
Worst |
Best |
Point |
Cu
Selling Price |
-10 |
% |
10 |
% |
$30 |
$216 |
$125 |
Cu
Grade |
-10 |
% |
10 |
% |
$33 |
$214 |
$125 |
Cu
Recovery |
-10 |
% |
10 |
% |
$33 |
$214 |
$125 |
Concentrate Shipping Costs - Land |
10 |
% |
-10 |
% |
$116 |
$130 |
$125 |
Opex -
Mining |
10 |
% |
-10 |
% |
$108 |
$138 |
$125 |
Opex -
Process |
10 |
% |
-10 |
% |
$107 |
$140 |
$125 |
Capital -
Mining |
10 |
% |
-10 |
% |
$113 |
$133 |
$125 |
Capital - Process & Admin |
10 |
% |
-10 |
% |
$105 |
$142 |
$125 |
Johnny Lee Mineral Reserve Estimation Methodology and
Parameters
Mining Methods
The Black Butte Copper Project Johnny Lee
deposit contains two zones – the UCZ and the LCZ. Both of these
zones are characterized as being high-grade, laying at low angles
and with relatively narrow widths. All deposits have anomalous
silver and cobalt mineralization; however copper is the only
economic product considered in the Feasibility Study.
Geotechnical data was gathered from logging of
the diamond drill core performed by Sandfire America geologists as
well as part of previous work by MDEng (MDEng, 2015). Specific
geotechnical holes were drilled along the projected main decline
and one of the ventilation raises and logged by Mining Plus. Mining
Plus in collaboration with Sandfire America geologists undertook a
quality assurance and quality control (QA/QC) audit of the data
gathered. Acoustic Televiewer and oriented core data were used to
determine structural information. In addition to the data logging,
multiple rock property tests were performed on different rock
types.
The Johnny Lee Deposit will be accessed by a
single main ramp driven from surface. The ramp dimensions will be
5m wide by 5m high and excavated with a flat back to maximize the
stability of the flat dipping joint sets that are prevalent
throughout the Project. The ramp will be excavated at a maximum
gradient of -15% from the surface and pass to the east of the UCZ
and then spiraling down to the LCZ. Ventilation and secondary
egress will be through 3 main ventilation raises.
All material handling will be by trackless
underground equipment with 51-tonne haul trucks hauling ore
directly from stope areas to either a surface ore pad or the
surface crusher.
The mining method will be a combination of drift
and fill and cut and fill depending on the height of the orebody.
All openings will be completely backfilled with Paste Backfill to
allow for the complete extraction of the orebody. In the UCZ where
the orebody is wider a Primary-Secondary-Tertiary method, where the
tertiary stopes are extracted through an unsupported slash
retreat.
Mineral Processing and Metallurgical
Test Work
Previous metallurgical test work programs
undertaken by the Company indicated that production of a copper
concentrate from the LCZ by froth flotation recovered 93.3% to
96.6% of the copper resulting in a concentrate grading 27.0% to
30.8% copper. Tests on UCZ composites during the same test programs
showed a wide range of copper recoveries (61.9% to 91.2%) at
concentrate grades of 18.5% to 24.5% copper. Mineralogical
investigation of UCZ metallurgical composites indicated that copper
sulphide liberation was the primary metric that defined
metallurgical performance.
Systematic mineralogical investigation of UCZ
drill intercepts was undertaken to define the vertical and lateral
variability in copper sulphide liberation throughout the entire
UCZ. This study also allowed the geometry of the supergene
alteration zone (at the intersection of Fault 1 and the
brittle-ductile shear zone) to be resolved. The supergene altered
zone comprises 2.2% of the total volume of the UCZ.
Based on the mineralogy derived geometallurgical
model, 19 PQ diameter (85 mm) diamond drillholes were targeted to
intersect the complete range of UCZ copper liberation types. From
these drillholes, 21 metallurgical composites were developed,
including two composites from the supergene alteration zone.
Comprehensive batch rougher and cleaner
flotation tests were completed on all 21 UCZ metallurgical
composites to determine the optimum primary grind size, reagent
suite, rougher regrind size and flowsheet configuration for UCZ
ore. Tests undertaken with site water showed no significant
differences to those completed with laboratory tap water. Two
rounds of locked-cycle tests were conducted, using a representative
subset (seven to eight composites) of the UCZ composites using
slightly different regrind sizes and different grinding media.
Based on the test work the optimized flowsheet for the UCZ was
developed:
Primary grind to 35 µm P80; Lime addition
to rougher flotation circuit to maintain pH = 9.5; Rougher
flotation using aero 3477, mono-sodium phosphate and dextrin;
Regrind of rougher concentrate to 10 µm P80; Lime addition
during regrind to maintain cleaner flotation circuit pH = 9.5;
Additional mono-sodium phosphate and dextrin added during regrind;
Three stage cleaner flotation circuit with cleaner scavenger;
Additional aero 3477 added to cleaner flotation circuit; and
Polyfroth w31 added to cleaner flotation circuit.
The locked-cycle tests on non-supergene altered
composites, using the optimized flowsheet recovered 70.6% to 90.1%
of the copper into a concentrate assaying 16.9% to 27.1% copper.
Locked-cycle testing of a supergene altered UCZ composite recovered
69.8% of the copper into a concentrate assaying 14.1% copper. A
blend of the six non-supergene altered composites was used to
create an UCZ global composite. Locked-cycle testing of this
composite recovered 81.6% copper into a concentrate assaying 24.4%
copper.
Given the amount of variability in non-supergene
altered UCZ composites, the relationship between copper recovery
and categorized proportional geometallurgical core logging,
comprehensive geochemistry and systematic mineralogy was evaluated
in detail. Of these, mineragraphy-defined copper sulphide
liberation metrics showed the best correlation with recovery. The
regression-based formula below defines the relationship between
variability batch test cleaner copper recovery (from the 19,
non-supergene altered composites) with five mineralogy derived
metrics:
Variability test Cu cleaner recovery = 94.144 +
(0.10615*(A+B)) + (-0.28667*(C+D)) + (-0.26708*E)
A =% Chalcopyrite interlocked with
marcasite/siegenite; B =% Chalcopyrite interlocked with gangue; C
=% Chalcopyrite in ternary grains; D =% Chalcopyrite in quaternary
grains; E =% pyrite.
There is a robust linear correlation between the
variability test cleaner copper recoveries and the cleaner
recoveries from the six locked-cycle tests on non-supergene altered
UCZ composites using the optimized UCZ flowsheet. This linear
correlation is defined by:
Locked-cycle test Cu cleaner recovery = (0.6619
* variability test Cu cleaner recovery) + 31.231
The formulae above were used to convert the
mineragraphy metrics from 113, non-supergene altered UCZ mineralogy
composites spaced throughout the UCZ (both laterally and
vertically) into expected copper recoveries. Inverse distance
weighted squared (“ID2”) interpolation of these
copper recovery metrics has been used to create a copper recovery
model for the UCZ that has been integrated with the Mineral
Resource model. Based on the process outlined above, estimated
copper recoveries for the UCZ range from 68.2% to 87.9%.
The supergene altered zone has been assigned a
copper recovery estimate of 69.8% based on the locked-cycle test of
the supergene altered composite.
A batch, single-stage cleaner flotation test on
a LCZ composite, using the UCZ flowsheet, recovered 92.3% copper to
a concentrate assaying 26.1% copper. Locked-cycle testing was
undertaken using a blend of the UCZ global composite (76%) and the
LCZ composite (24%). Copper in the feed was 93.2% recovered into a
concentrate grading 21.5% copper. The metallurgical balance
indicated that there were no negative synergies between blending
the two feed sources. Based on previous and recent test work, a
global 93% copper recovery has been assigned to the LCZ.
Analyses of the copper concentrates from
locked-cycle testing of UCZ composites has reported potentially
deleterious levels of arsenic. There is no correlation between the
arsenic concentration of the feed composites and that in the
concentrates as only certain arsenic bearing minerals (primarily
tennantite) preferentially deport to the concentrate. There is a
strong linear correlation between the tennantite percentage of the
feed, estimated using systematic mineragraphy, and the arsenic
levels in copper concentrates from locked-cycle tests. This
correlation is defined by the formula:
Locked-cycle test cleaner concentrate as grade
(ppm) = (8048.4 * tennantite%) + 3202.6
This formula has been used to convert the
tennantite concentrations for the systematic mineralogy composites
into expected arsenic concentrations in copper concentrate. ID2
interpolation has been used to create an arsenic in concentrate
block model which has been integrated with the copper recovery and
Mineral Resource models. Based on the tennantite concentrations,
arsenic in UCZ concentrates is expected to range from 3,202 to
14,876 ppm.
Based on analyses of the concentrate produced
during locked-cycle testing of a master LCZ composite a global
arsenic in concentrate value (230 ppm) has been assigned to LCZ
ore.
Recovery Methods
Metallurgical test work indicates that the
copper in the UCZ and LCZ can be recovered to a concentrate by
crushing, grinding, and froth flotation processes. The UCZ ore
requires a fine primary grind (38 µm P80) and a very fine regrind
(10 µm P80) of the rougher concentrate to achieve optimized
recoveries. The LCZ ore does not require such fine grinds to
achieve optimized recoveries. However, as it will be blended with
UCZ ore in small volumes, the blended ore will be treated using the
process as optimized for UCZ ore. Metallurgical test work has
demonstrated that there are no reductions in copper recovery to
concentrate from UCZ or LCZ ore by blending and processing the
blend using the flowsheet optimized for UCZ ore.
Infrastructure
The layout and surface footprint of all
aboveground infrastructure for the Project has been designed as
part of the MOP application submitted to the MT DEQ. The ground
infrastructure in the MOP includes: access roads, site roads, mine
portal, ventilation raises, processing plant, reclamation
stockpiles, temporary waste rock storage, cemented tailings
facility, process water pond, contact water pond, storage water
pond, non-contact water reservoir, sub-surface infiltration
gallery, power lines, pipelines, workshops, store, offices and
parking.
Capital and Operating Costs
Capital Cost Estimates
The Project capital cost estimate has been
developed for the Feasibility Study and is based upon an Engineer,
Procure and Construction Management (“EPCM”)
approach for the construction and commissioning of the Project
facilities. This includes mine, plant and infrastructure, the
process plant and infrastructure, general mine infrastructure and
roads.
A capital cost of $274.7 million, including
contingency, has been developed for the Project and includes all
costs before the commencement of production. The capital costs have
been estimated to a ±15% accuracy. The breakdown of the Project
Capital is given in Table 4.
Table 4 – Project Capital cost breakdown
Area |
Capital Cost $M |
Mining |
$65.1 |
Site Infrastructure |
$91.4 |
Mineral Processing & WTP |
$72.7 |
Project In-directs (EPCM & Owner Costs) |
$20.5 |
Contingencies (mine, process, infrastructure & in-directs) |
$25.0 |
Total Project |
$274.7 |
Mining Operating Costs
Operating costs have been developed using the
parameters specified in the process design criteria. Annual
operating costs and costs per tonne mined has been developed. The
mining operating cost estimate has been developed on the basis of
ore to the ROM pad at the same rate as the processing plant name
plate of 1.2 million tonnes per annum. The operating cost estimate
is $27.8 million per annum or $22.82 per tonne of ore supplied to
the ROM.
Process Plant Operating Costs
Operating costs have been developed using the
parameters specified in the process design criteria. Annual
operating costs and costs per tonne milled has been developed.
Operating costs for the treatment plant have been estimated to an
accuracy of ±15%. The costs are presented in United State dollars
(USD$) and are based on prices obtained during the second quarter
of 2019 (2Q19) and exclude the VAT cost components.
The processing operating cost (excluding
freight) estimate has been developed on the basis of a process
plant feed tonnage of 1.2 million tonnes per annum. The processing
operating cost (excluding freight) estimate is $29.43 million per
annum or $25.52 per tonne milled.
Risks Affecting Potential
Development
Environmental
The Company conducted exploration under
Exploration License #00710 issued by the MT DEQ. Regulations
include the bonding of exploration disturbances to ensure
reclamation is completed. The Company currently has an obligated
bond of $137,365 for completion of the reclamation of the 2018/2019
Phase 2 and earlier drill programs. These obligations will be
released when the reclamation is completed by the Company and
inspected and approved by the MT DEQ. In addition, there are
approximately 37 monitoring wells/test wells, and one water well,
and 15 piezometers currently in place that will ultimately need to
be removed during closure and reclamation.
Potential short- and long-term impacts caused by
mining activities were evaluated from several perspectives: impacts
to the environment during operation and closure, issues or impacts
that could materially affect the mine’s ability to extract the
Mineral Reserves, and socio-economic impacts.
Potential impacts to the environment were
addressed in detail in the Environmental Impact Statement (MT DEQ,
2019 and 2020).
In addition to the approved MOP there are 27
other permits or plans that need to be approved by Federal, Montana
State, or Meagher County authorities. These permits and plans
cover: water quality, water rights, water supply, wetlands and
streambed preservation, aquatics monitoring, dam safety, sewerage
disposal, air quality, invasive vegetation, tribal communications,
cultural resources, community impact, mining infrastructure, mining
operations and emergency response. Work has been initiated on all
but four of these permits/plans (which are largely administrative).
To date, five permits/plans have been approved, nine applications
have been submitted and nine applications are in the process of
being compiled.
Legal
The MOP was designed to meet the requirements of
the Montana Metal Mine Reclamation Act and the rules and
regulations governing the act. Additional permits including a
Montana Pollutant Discharge Elimination System
(“MPDES”) were obtained through the MT DEQ.
Compliance with the applicable legal
requirements is demonstrated by the MT DEQ’s approval of the
following: MOP, Air Quality Permit, MPDES and construction storm
water permit. A draft Environmental Impact Statement was published
by the MT DEQ on March 11, 2019, as required under the
Montana Environmental Policy Act, and finalized on March 13, 2020.
Subsequently, the MT DEQ issued a Record of Decision for the mine
on April 9, 2020, identifying MT DEQ’s decision, the reasons
for the decision and special conditions surrounding the decision
and its implementation.
As previously reported, a legal challenge
against the Project regarding the mine operation permit continues
with a potential hearing expected in late October in front of Judge
Spaulding of the 14th Judicial Court. To date, the legal challenge
has not resulted in any interference with development activities
and construction continues.
Leasing of mitigation water rights has
preliminary approval from the Montana Department of Natural
Resources and Conservation (MT DNRC). However, there are objections
which will slow down the process. The water rights have to be
finalized to start production. While we do not believe that either
of these challenges have any merit, they do have the potential to
delay the project development timeline.
For additional information, please refer to the
document entitled “Management Discussion and Analysis for the year
ended June 30, 2020”, which the Company filed on the Company’s
SEDAR profile at www.sedar.com on August 25, 2020.
Lowry Deposit – Mineral
Resources
The updated Mineral Resource statement for the
Lowry Deposit is summarized in Table 3. The Mineral Resource
statement is supported by recent updates to the geological
modeling, resource estimation, and mineralogy with recovery
assumptions in addition to historic drilling, analyses, and
studies. The Lowry Deposit contains no Mineral Reserves, and
therefore is not included in the Feasibility Study. The Lowry
Deposit has a much lower density of drilling than the Johnny Lee
Deposit. Mineralization is hosted in two distinct zones of >
1.2% Cu mineralization. These zones are termed the Lowry middle
copper zone (“LMCZ”), and the Lowry lower copper zone (“LLCZ”).
A total of 51 drillholes have been used for the
2020 Lowry Deposit Mineral Resource. Drillhole intersection spacing
in the LMCZ ranges from 40 – 100 m. The LMCZ is hosted by a
succession of massive sulphide and pyritic shale with interbedded
conglomerate, carbonaceous shale and shale.
Ten mineralogical composites from the LMCZ have
been investigated (McArthur, 2019). Using the regression-based
relationship derived for the Johnny Lee Deposit UCZ, an average Cu
recovery of 86% is estimated for the Lowry Deposit in both the LMCZ
and the LLCZ.
The >1.2% Cu zones are surrounded by
>0.25% Cu mineralization referred to as Halo mineralization. The
Halo mineralization is largely confined to the host unit but does
transgress the hanging wall and footwall contacts in places.
Many of the drillholes that intersected the LMCZ
were stopped-short of the LLCZ, consequently drillhole spacing in
the LLCZ is larger than that of the LMCZ, ranging from 60 –
200m.
Mineral Resource classification was assigned to
the Lowry Deposit block model by the QP based upon: geological
knowledge, continuity of Cu grade within mineralized zones,
thickness of the mineralized zones, confidence in the underlying
data (logging, assay, and physical testing), spatial continuity as
determined through variography for Cu, recovery data, kriging
quality variables (kriging efficiency, average distance to samples,
and estimation run pass), and drill sample spacing on a domain
basis. Blocks within the LMCZ and LLCZ have been categorized as
Inferred classification consistent with NI 43-101 and the CIM
Definition Standards. Mineralized material in the LUCZ and the halo
mineralization was not deemed acceptable for classification at this
time but represents mineralization potential with future studies. A
combination of wireframe volumes and scripting of specific blocks
was used to apply the appropriate block classification of Mineral
Resource categories.
Summary Mineral Resources have been estimated
and reported using an economic cut-off grade (CoG) applied to
copper as estimated in the resource block model. This Mineral
Resource statement is supported by drilling, analyses, geological
modelling, and extensive metallurgical studies to provide updated
recoveries.
Table 5 – Lowry Deposit Mineral Resource
effective October 15, 2020 – SRK Consulting (U.S.), Inc.
Category |
Quantity (Mt) |
Cu (%) |
Total Metal (kt) |
LMCZ |
Inferred |
5.7 |
2.5 |
144.5 |
LLCZ |
Inferred |
2.6 |
2.1 |
55.0 |
Combined LMCZ + LLCZ |
Inferred |
8.3 |
2.4 |
199.5 |
Source: SRK, 2020
- The effective date for this Mineral Resource is October 15,
2020. All significant figures are rounded to reflect the relative
accuracy of the estimates. Copper assay values were capped where
appropriate;
- Mineral Resources are not Mineral Reserves and do not have
demonstrated economic viability. Inferred Mineral Resources have a
high degree of uncertainty as to their economic and technical
feasibility. It cannot be assumed that all or any part of an
Inferred Mineral Resources can be upgraded to Measured or Indicated
Mineral Resources;
- Metallurgical recovery of copper has been assigned to the Lowry
Deposit using the mean recovery of 86% Cu based on mineralogical
and regression-based analyses;
- To demonstrate reasonable prospects for eventual economic
extraction of Mineral Resources, a cut-off grade of 1.20% copper
based on metal recoverability assumptions, long-term copper price
assumptions of $3.20/lb, mining costs, processing costs, G&A
costs totaling $71/t;
- There are no known legal, political, environmental, or other
risks that could materially affect the potential development of the
Mineral Resources other than those outlined in the Management
Discussion and Analysis of the June 2020 Company Quarterly Report
and identified above. All Mineral Resources are located within land
currently under control or lease to Sandfire Resources America
Inc.
Table 6 shows the tabulated grade-tonnage curve
data to assess the sensitivity of Mineral Resources to changes in
CoG.
Table 6 - Tabulated Grade-Tonnage Data by Cut-off
Grade
Cut-off |
cu_pct |
Tonnage |
|
Increment |
Increment |
Inc Grade |
Inc Tonnage |
|
0.25 |
2.29 |
9,020,421 |
|
0.25 |
0.50 |
0.41 |
2,807 |
|
0.50 |
2.30 |
9,017,614 |
|
0.50 |
0.75 |
0.67 |
59,156 |
|
0.75 |
2.31 |
8,958,458 |
|
0.75 |
1.00 |
0.90 |
249,515 |
|
1.00 |
2.35 |
8,708,943 |
|
1.00 |
1.25 |
1.15 |
604,577 |
|
1.25 |
2.44 |
8,104,366 |
|
1.25 |
1.50 |
1.37 |
837,993 |
|
1.50 |
2.56 |
7,266,373 |
|
1.50 |
1.75 |
1.63 |
827,930 |
|
1.75 |
2.68 |
6,438,443 |
|
1.75 |
2.00 |
1.88 |
1,079,210 |
|
2.00 |
2.84 |
5,359,232 |
|
2.00 |
2.25 |
2.12 |
1,380,083 |
|
2.25 |
3.09 |
3,979,150 |
|
2.25 |
2.50 |
2.36 |
865,160 |
|
2.50 |
3.29 |
3,113,990 |
|
2.50 |
2.75 |
2.62 |
816,074 |
|
2.75 |
3.53 |
2,297,915 |
|
2.75 |
3.00 |
2.87 |
505,766 |
|
3.00 |
3.71 |
1,792,150 |
|
3.00 |
3.25 |
3.12 |
526,143 |
|
3.25 |
3.96 |
1,266,006 |
|
3.25 |
3.50 |
3.37 |
349,693 |
|
3.50 |
4.18 |
916,314 |
|
3.50 |
3.75 |
3.62 |
250,177 |
|
3.75 |
4.39 |
666,137 |
|
3.75 |
4.00 |
3.86 |
210,985 |
|
4.00 |
4.63 |
455,152 |
|
4.00 |
>4.00 |
4.63 |
455,152 |
|
Comparison to Previous Mineral Resource
Estimates
The previous Mineral Resource for the Lowry
Deposit was completed in 2013 (effective date July 12, 2013) as
part of the Company’s Preliminary Economic Assessment (the
“PEA”). Continued flotation testing since the
release of the PEA report has shown unfavorable results for
polymetallic products other than Cu given the current economic
assumptions. Therefore, for the 2020 Mineral Resources at the Lowry
Deposit, Co, Ag, and Au have been excluded.
The 2020 updated classification for Lowry
Deposit Mineral Resources is aligned with the 2019 Johnny Lee
Deposit classification. This has resulted in a change from the 2013
Lowry Deposit Mineral Resources which reported a combination of
indicated and inferred Mineral Resources at the time. Updated 3D
wireframing of the major mineralized zones, spatial continuity
analyses, and a review of estimation criteria has resulted in the
updating of Lowry Deposit resources to be entirely classified as
inferred Mineral Resources.
The total quantity of Mineral Resources has
increased in 2020 from the 2013 statement. This is due to inclusion
of the LLCZ, which was not part of the 2013 resource estimate, as
well as updated mineralized 3D wireframes and the estimation of
Specific Gravity (“SG”) values compared to assignment of mean SG
data in 2013.
The average Cu grade has decreased in the 2020
Mineral Resources compared to the 2013 statement. This is due to
changes in the composite size from 1.0 m in 2013 to 1.5 m in 2020,
use of ordinary kriging (“OK”) estimation method
in 2020 compared to Inverse Distance Weighting (“IDW”) to the third
power, improved search neighborhood incorporating multiple samples
and search ellipsoid aligned with the dominant directions of
mineralization, reduced CoG of 1.2% Cu from 1.6% Cu in 2013, and
modified domains constraining estimation to zones of approximately
greater than 1.2% Cu.
Lowry Resource Estimation Methodology
and Parameters
Mineral Resource estimation was performed for
the Lowry Deposit by SRK Consulting (U.S.) Inc.
(“SRK”) using Maptek™ Vulcan™ software. The focus
of estimation was on Cu as the key economic variable of interest.
SRK performed an extensive review of all historic geological and
drilling data on the Lowry Deposit including QA/QC and general data
verification. Estimation of Cu and SG was performed using a
combination of OK and IDW to the power of two based on a multi-pass
method within modeled domains. Domains were modeled using a
combination of lithostratigraphic data and grade shelling.
In areas of limited data that did not meet the
minimum criteria for estimation in the final pass, a scripted value
was assigned to the block variable by domain. The scripted value
assigned is the variable mean from capped composites by domain. A
limited number of blocks in the Lowry block model met this
criterion and were located primarily in the LUCZ domains and are
excluded from Mineral Resource calculations.
SG was estimated in the block model using a
two-pass method of IDW2 with varying search neighborhoods by
domain. As with quality variables, blocks not estimated in the last
pass were scripted a mean value based on composite data. As there
is less SG data compared to quality analytical variables, a greater
number of blocks were scripted with the domain mean.
Each mineralized domain has a unique search
neighborhood based on the Cu variogram, mineralization thickness,
and data spacing within the domain. For most domains, the
directionality of the search ellipsoid was varied by block based on
the average orientation of the domain’s modeled wireframe.
The primary mineralized domains of LMCZ and LLCZ
show that the majority of blocks were populated in the first pass
with all remaining blocks estimated in the second pass. In the
LUCZ, due to limited data, the percentage of blocks estimated in
the first few passes show that portions of the domain exhibit
limited confidence in estimated quality while large portions are
low confidence and thus populated in either a large search pass or
with scripted mean values. As a result, the LUCZ does not contain
Mineral Resources at this time but represents mineralized potential
for targeted future work programs at the Lowry Deposit.
Lowry Deposit Copper Recovery
Estimation
Mineralogical test work at the Lowry Deposit was
used for a regression-based analysis derived from similar
mineralization style observed at the Johnny Lee Deposit. The
resultant outcome shows an 86% recovery of Cu assumption. For the
purposes of determining Mineral Resources, the average of 86%
recovery was applied in the determination of total contained
Cu.
Lowry Deposit Determination of Cut-off
Grade for Resource
To demonstrate reasonable prospects of eventual
economic extraction of Mineral Resources at the Lowry Deposit, a
cut-off grade was applied that accounts for assumed metallurgical
recovery of Cu, operational costs, and long-term market-driven Cu
pricing. Metallurgical recovery was assigned at 86% Cu recovery
based on mineralogical test work and regression analysis based on
mineralogical similarities with work done at the nearby Johnny Lee
Deposit. Operational costs were assumed consistent with work
completed at Johnny Lee Deposit with a US$71/tonne assumed cost. Cu
price assumptions are based on US$3.20/lb derived from a mean of
multiple market-based long-term pricing forecasts. Using these
assumptions, a cut-off grade of 1.2% Cu was applied to the Lowry
Deposit.
It is the opinion of the QP that the estimation
for Cu and SG in the Lowry block model is appropriate given the
data spacing, geological model, and data variability per domain.
Some domains contain limited data, therefore were estimated using a
simplified neighborhood and estimation method such as IDW2. In
domains that are better informed with drilling data, OK was used
when an acceptable variogram was calculated.
Qualified Persons
The technical information contained in this news
release related to the Johnny Lee Deposit has been reviewed and
approved by Erik Ronald, M. Eng., P.Geo, RM-SME, Principal Resource
Geology Consultant, SRK, Brad Evans, MAusIMM, CP(Mining), and
Deepak Malhotra Ph.D. RM-SME, Resource Development Inc. Messrs.
Ronald, Evans and Malhotra are qualified persons, as such term is
defined in NI 43-101 for Mineral Resources, Mineral Reserves and
metallurgical processing respectively. Messrs. Ronald and Malhotra
are independent of the Company. For additional detailed information
on the key assumptions, parameters and methods used to estimate the
Mineral Reserves, along with other information about the Johnny Lee
Deposit, please refer to the Technical Report to be filed.
The technical information contained in this news
release related to the Lowry Deposit has been reviewed and approved
by Messrs. Ronald and Malhotra. The Mineral Resource block model
and estimation for the Lowry Deposit was reviewed and accepted by
Messrs. Ronald and Malhotra acting as qualified persons for Mineral
Resources. The final Mineral Resource classification and
calculations were performed by Mr. Ronald using Maptek’s Vulcan™
software. Domaining of copper mineralization was performed by
Sandfire America staff using Leapfrog Geo™ software and reviewed by
the qualified persons.
The qualified persons referred to above have
verified the data disclosed in this news release, including
sampling, analytical, and test data underlying the information or
opinions contained in this news release.
Contact Information: Sandfire
Resources America Inc. Nancy Schlepp, VP of CommunicationsMobile:
406-224-8180 Office: 406-547-3466 Email:
nschlepp@sandfireamerica.com
Additional information on Sandfire Resources
America Inc. can be viewed on SEDAR under the Company’s profile at
www.sedar.com or on Sandfire Resources America Inc.’s website at
www.sandfireamerica.com
Cautionary Note Regarding Forward-Looking
Statements: Certain disclosures in this document constitute
“forward looking information” within the meaning of Canadian
securities legislation, including statements regarding the Mineral
Resource and Mineral Reserve estimates, the proposed mining plans
and recovery methods, estimates of capital, operating costs and
sustaining, estimates of other costs and payments, the estimated
amount of future production, both produced and metal recovered,
cash flow, internal rate of return (IRR), pre and post-net present
value, mine life, payback, gross sales, estimated recoveries, the
number of persons to be employed by the Project and economic
returns and benefits from an operating mine, the Feasibility Study
and the expected timing of filing thereof, and expected
outcomes.
Forward-looking statements include statements
that are predictive in nature, are reliant on future events or
conditions, or include words such as "expects", "potential",
"anticipates", "plans", "believes", "considers", "significant",
"intends", "targets", "estimates", "seeks", attempts", "assumes",
and other similar expressions.
In making these forward-looking statements, the
Company has applied certain factors and assumptions that the
Company believes are reasonable, including those assumptions
previously set out in this news release and the following
assumptions: that the Company will receive required regulatory
approvals, the Company’s successful advancement of the Black Butte
Copper Project, the expected positive results from the Project
based on the estimates and findings contained in the Feasibility
Study, that the Company will continue to be able to access
sufficient funding to execute its plans, that the Company is able
to procure equipment and supplies in sufficient quantities and on a
timely basis, that the Company’s exploration and development
activities on the Black Butte Copper Project will not be affected
by actions of environmental activists or other special interest
groups, that the results of exploration and development activities
will be consistent with management’s expectations, the assumptions
underlying internal rates of return and net present value are
valid, that capital costs and sustaining costs will be as
estimated, that the assumptions underlying Mineral Resource and
Mineral Reserve estimates are valid, that no unforeseen accident,
fire, ground instability, flooding, labor disruption, equipment
failure, metallurgical, environmental or other events that could
delay or increase the cost of development will occur, that the
current price and demand for copper and other metals will be
sustained or will improve; that general business and economic
conditions will not change in a materially adverse manner; and the
continuity of economic and political conditions and operations of
the Company.
However, the forward-looking statements in this
document are subject to numerous risks, uncertainties and other
factors, including factors relating to the Company’s operation as a
mineral exploration and development company and the Black Butte
Copper Project, that may cause future results to differ materially
from those expressed or implied in such forward-looking statements,
including those risks previously set out in this news release and
the following risks: the risk that any of the assumptions on which
the forward looking information is based prove to be incorrect or
invalid, the risk of unexpected variations in Mineral Resources and
Mineral Reserves, grade or recovery rates, the possibility of cost
overruns or unanticipated costs and expenses, uncertainties
relating to the availability and costs of financing needed in the
future, that actual costs of restoration activities are greater
than expected and that changes in Project parameters as plans
continue to be refined result in increased costs, results of
exploration and development activities will not be consistent with
management’s expectations, uncertainties involved in the
interpretation of drilling results and geological tests; delays in
obtaining or inability to obtain required government or other
regulatory approvals or financing, failure of plant, equipment or
processes to operate as anticipated, the risk of accidents, labor
disputes, inclement or hazardous weather conditions, unusual or
unexpected geological conditions, ground control problems,
earthquakes, flooding; interference with the Company’s exploration
or development activities by environmental activists or other
special interest groups; inability to procure equipment and
supplies in sufficient quantities and on a timely basis; the
risk that estimated costs will be higher than anticipated and the
risk that the proposed mine plan and recoveries will not be
achieved, the risks disclosed in the Company’s most recently filed
Management Discussion and Analysis and the Company’s other
continuous disclosure filings filed under the Company's profile at
www.sedar.com and all of the other risks generally associated with
the development and operation of mining facilities.
There can be no assurance that such statements
will prove to be accurate, and actual results and future events
could differ materially from those anticipated in such statements.
Readers are cautioned not to place undue reliance on
forward-looking statements. The Company does not intend, and
expressly disclaims any intention or obligation to, update or
revise any forward-looking statements whether as a result of new
information, future events or otherwise, except as required by
law.
CAUTIONARY NOTE TO US READERS. As a Canadian
reporting issuer, the Company is subject to rules, policies and
regulations issued by Canadian regulatory authorities and is
required to provide detailed information regarding its properties
including mineralization, drilling, sampling and analysis, security
of samples and Mineral Resource and Mineral Reserve estimates. In
addition, as a Canadian reporting issuer, the Company is required
to describe Mineral Resources associated with its properties
utilizing Canadian Institute of Mining, Metallurgy and Petroleum
(“CIM”) definitions of “indicated” or “inferred”,
which categories of resources are recognized by Canadian
regulations but are not recognized by the United States Securities
and Exchange Commission (“SEC”).
The SEC allows mining companies, in their
filings with the SEC to disclose only those mineral deposits they
can economically and legally extract or produce. Accordingly,
information contained in this News Release regarding our mineral
deposits may not be comparable to similar information made public
by U.S. companies subject to the reporting and disclosure
requirements under the United States federal securities laws and
the rules and regulations of the Commission thereunder.
Neither the TSX Venture Exchange nor its
Regulation Services Provider (as that term is defined in the
policies of the TSX Venture Exchange) accepts responsibility for
the adequacy or accuracy of this release.
Sandfire Resources America (TSXV:SFR)
Graphique Historique de l'Action
De Nov 2024 à Déc 2024
Sandfire Resources America (TSXV:SFR)
Graphique Historique de l'Action
De Déc 2023 à Déc 2024