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Boliden Summary ReportResources and Reserves | 2018
Kankberg – Åkulla Östra
Prepared by Birger Voigt
Boliden Summary Report, Resources and Reserves 2018, Kankberg – Åkulla Östra| 2
Table of contents1 Summary 3
1.1 Competence 3
2 General introduction 4
2.1 Pan-European Standard for Reporting of Exploration Results,
Mineral Resources and Mineral Reserves – The PERC Reporting
Standard 4
2.2 Definitions 4
3 Kankberg 6
3.1 Major changes 6
3.2 Location 6
3.3 History 7
3.4 Ownership 7
3.5 Permits 7
3.6 Geology 8
3.7 Drilling procedures and data 9
3.8 Exploration activities and infill drilling 11
3.9 Mining methods, mineral processing and infrastructure 12
3.10 Prices, terms and costs 15
3.11 Mineral resources 16
3.12 Mineral reserves 18
3.13 Comparison with previous year 18
3.14 Reconciliation 20
4 References 23
4.1 Internal references 23
Appendix 1 – Brief history
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1 SUMMARY
This summary report is issued annually to inform the public (shareholders, potential
investors and their advisers) of the mineral assets in the Kankberg mine held by Boliden
Mineral AB.
The Kankberg mine is located approximately 10 km west of the Boliden Area Operations
process plant in Boliden, and produces gold and tellurium from a deposit hosted by felsic
volcanic and volcaniclastic rock types. The mine has been in production since 2012 and has
since then increased the annual production capacity to ca 450 000 t.
In 2018, the mine produced 456 979 t grading 4.4 g/t Au, 10.7 g/t Ag and 188.3 g/t Te. In
it’s lifetime the mine has produced 2 394 kt grading 3.7 g/t Au, 9.3 g/t Ag and 162.5 g/t Te.
A summary of Mineral Resources and Mineral Reserves are presented in Table 1.
Table 1. Mineral Resources and Mineral Reserves in Kankberg 2018-12-31
Classificationkt Au
(g/t)Ag
(g/t)Te
(g/t)
2018Bi
(g/t)kt Au
(g/t)Ag
(g/t)
2017Te
(g/t)Bi
(g/t)
Mineral Reserves
Proved 2 720 3.8 12 182 94 2 410 3.8 11 181 102
Probable 1 510 3.4 8 153 81 2 130 3.5 10 168 86
Total 4 220 3.7 10 171 89 4 530 3.7 11 175 95
Mineral Resources
Measured 260 4.0 11 155 88 190 3.8 8 130 91
Indicated 600 5.2 7 151 97 310 4.7 8 117 67
Total M&I 860 4.8 8 152 94 500 4.4 8 122 76
Inferred 1 390 5.2 9 209 137 1 360 5.5 8 168 109
1.1 CompetenceTable 2. Contributors and responsible competent persons for this report
Description Contributors Responsible CP
Compilation of this report Birger Voigt Gunnar Agmalm
Geology and exploration Birger Voigt, Susanne Holmen
Resource estimations Lina Åberg
Mineral processing Marie Lundberg
Mining Tina Žižek
Environmental and legal permits
Gunnar Agmalm is Boliden’s Ore reserves and Project Evaluation manager and a member of
AusIMM1 and FAMMP2 Birger Voigt is Mine Geologist at the Kankberg Mine.
1 Australian Institute of Mining and Metallurgy2 Fennoscandian Association for Metals and Minerals Professionals
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2 GENERAL INTRODUCTION
This report is issued annually to inform the public (shareholders and potential investors) of
the mineral assets in Kankberg held by Boliden. The report is a summary of internal reports
for Kankberg. Boliden is changing reporting standard from Fennoscandian Review Board
(FRB) to the Pan-European Reserves and Resources Reporting Committee (PERC) “PERC
Reporting Standard 2017”. The PERC Reporting Standard is an international reporting
standard that has been adopted by the mining associations in Sweden (SveMin), Finland
(FinnMin) and Norway (Norsk Bergindustri), to be used for exploration and mining
companies within the Nordic counties.
The previously used FRB standard will no longer be maintained. The PERC standard has
more clearly defined requirements on reporting and on Competent Persons. Boliden is
currently in the process of updating procedures and many of the reports and estimations
summarized here are compiled according to the previous standard (FRB). We consider this
data accurate and reliable. The process of creating PERC compliant estimations, studies and
reports for all Projects and Mines is underway.
2.1 Pan-European Standard for Reporting of Exploration Results, Mineral Resources and Mineral Reserves – The PERC Reporting Standard
PERC is the organisation responsible for setting standards for public reporting of
Exploration Results, Mineral Resources and Mineral Reserves by companies listed on
markets in Europe. PERC is a member of CRIRSCO, the Committee for Mineral Reserves
International Reporting Standards, and the PERC Reporting Standard is fully aligned with
the CRIRSCO Reporting Template.
The PERC standard sets out minimum standards, recommendations and guidelines for
Public Reporting of Exploration Results, Mineral Resources and Mineral Reserves in Europe.
2.2 Definitions
Public Reports on Exploration Results, Mineral Resources and/or Mineral Reserves must
only use terms set out in the PERC standard.
Figure 1. General relationship between Exploration Results, Mineral Resources and Mineral Reserves (PERC 2017)
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2.2.1 Mineral Resource
A Mineral Resource is a concentration or occurrence of solid material of economic interest
in or on the Earth’s crust in such form, grade or quality and quantity that there are
reasonable prospects for eventual economic extraction.
2.2.2 Mineral Reserve
A Mineral Reserve is the economically mineable part of a Measured and/or Indicated Mineral
Resource.
It includes diluting materials and allowances for losses, which may occur when the material is
mined or extracted and is defined by studies at Pre-Feasibility or Feasibility level as
appropriate that include application of Modifying Factors. Such studies demonstrate that, at
the time of reporting, extraction could reasonably be justified.
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3 KANKBERG
The Kankberg mine is located approximately 10 km west of the Boliden Area Operations
processing plant in Boliden, and produces gold and tellurium from a deposit hosted by felsic
volcanic and volcaniclastic rock types. The mine has been in production since 2012 and has
since then increased the annual production capacity to ca 450 000 t. Mining activity is taking
place in 5 stopes and on average 4 to 5 stopes are in production at any given time and one
primary backfill area.
In 2018, the mine produced 456 979 t grading 4.4 g/t Au, 10.7 g/t Ag and 188.3 g/t Te. In
it’s lifetime the mine has produced 2 394 kt grading 3.7 g/t Au, 9.3 g/t Ag and 162.5 g/t Te.
3.1 Major changes
No major changes or happenings have occurred during the year.
3.1.1 Technical studies
No technical studies have been carried out during 2018. However, steps to investigate and
expand on the currently used density of rock types and spatial density variation has been
initialized.
3.2 Location
The present day Kankberg Au mine is situated 10 km from the processing plant in Boliden
(Figure 2). The Au deposit is located at a depth of 200 – 700 m, below the former Åkulla
Östra open pit mine.
Figure 2. Kankberg is situated 10 km from Boliden. The 1,5 km ramp from the entrance of the old Kankberg mine to Kankberg/Åkulla Östra is drawn in blue
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3.3 History
The Kankberg Au deposit was discovered in 1995 and have been drilled periodically from
1995 to 2010. During 1997-1999 a ramp was driven from the old Kankberg mine and in 1999
1 350 t grading 2.4 g/t Au were mined when the ramp passed through the mineralisation. In
2006 11 100 t grading 4.6 g/t Au and 18 g/t Ag were mined for processing tests. During
2007 - 2008 a new drilling programme was completed. At the same time a study for
extraction of tellurides showed good potential for profitability. Further drilling was done in
2009 - 2010, which by May 2010 concluded the geological part of the feasibility study. The
feasibility study was ready in January 2011 and in February 2011 environmental permit was
granted. Development of the mine service facilities and ramps were initiated in May 2011.
Production began in February 2012. See Appendix for a summarised history.
Since beginning of operations until 2018-12-31, 2 395 062 t grading 3.44 g/t Au, 10.5 g/t Ag
and 156.5 g/t Te have been milled.
3.4 Ownership
The deposit is 100% owned by Boliden as well as the ground above it.
3.5 Permits
The Kankberg mine is covered by the mining concessions Östra Åkulla K nr. 1 which is valid
until 2026-02-05 and Östra Åkulla K nr. 2 (black triangle in Figure 3), which is valid until
2034-11-10. A requisite license in accordance with the Environmental Law was issued in
April 2011. Covering the concessions and nearby area Boliden holds an exploration license
Kankberg nr. 1006, which is valid until 2020-11-07.
Figure 3. Exploration licence Kankberg nr. 1006 blue line. Mining concession Åkulla Östra K n. 1 broken line and K nr. 2 black triangle
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3.6 Geology3.6.1 Regional
The Kankberg mine lies within the eastern part of the Skellefte field (Figure 4). The Skellefte
field is one of the most important mining regions in Sweden containing numerous
polymetallic sulphide deposits, vein Au deposits and porphyry Cu-Au-Mo deposits. The
majority of known ore deposits in the Skellefte field occur within the upper parts of the
Skellefte group. The Skellefte group is a regionally dominant sequence of volcanic rocks that
were formed during a period of intense, extensional, continental margin arc volcanism about
1.89 Ga ago (Allen et al. 1996).
Figure 4. Geological map of the Skellefte district. Kankberg is situated in the eastern part of the distrcit (modified after Kathol & Weihed, 2005)
3.6.2 Local
The bedrock in the Kankberg area is dominated by volcanic rocks of primarily dacitic and
rhyolitic compositions forming quartz-feldspar porphyritic, rhyolitic and dacitic rock types.
The felsic magmas forming these volcanics intruded as shallow (subvolcanic) dykes and sills
and extruded as lavas at the surface where they mixed with sediments and mass flows derived
from volcanic slopes. The volcanism initiated a convection of solutions through the rocks.
These solutions dissolved and transported minerals and metals to sites of deposition.
After the major volcanic period had ended the area were subsequently deformed and folded.
This resulted in a dominantly vertical trend of the rocks and structures. At a later stage,
brittle deformation took place. Fractures and fissures were intruded by mafic magma forming
basaltic and andesitic dykes, which are common in the Kankberg area.
3.6.3 Property
3.6.4 Mineralization
The Kankberg Au deposit is hosted by primarily quartz-feldspar porphyry, volcaniclastic and
quartz-andalusite rock types. These rocks form a very competent body, which is surrounded
by dacites. In general, a sericite+pyrite±quartz-rich alteration zone is superimposed on the
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contact between the host rocks and the surrounding dacites. The host rocks are strongly
altered by silicification, andalusite ± topaz alteration and to a varying degree seritization.
The Au-mineralisation is primarily found within the quartz-andalusite±topaz alteration and
consists of fine-grained native gold, Au-Ag alloys and gold-tellurides. The Au mineralisation
is “divided” into 5 informal ore bodies known as FW1, FW2, M1, M2 and M4 (Figure 5).
Elevated gold grades also occur outside the quartz-andalusite alteration where gold is often
associated with sulphide minerals (pyrite, sphalerite and chalcopyrite).
Figure 5. Schematic illustration of orebodies. FW1 (bright red), FW2 (red), M1 (blue), M2 (grey) and M4 (green). A) plan view, B) S-N profile looking west
3.7 Drilling procedures and data
Diamond core drilling has been carried out for the purpose of exploration and infill drilling.
Exploration drilling is being carried out by the UGN department, who contract’s Protek AB
for the actual core drilling. Infill drilling is being carried out by Boliden personal (G1N), who
operates two in-house drill rigs.
3.7.1 Drilling techniques
Exploration drilling is done using two Diamec U6 drill rigs and wireline 56 systems. This
produce 39 mm drill core.
Infill drilling is done using two drill rigs, Diamec U6 and U4 and wireline 56 systems. During
the autumn 2018 the Diamec U4 was replaced with a Diamec S6.
3.7.2 Downhole surveying
Exploration drilling: Downhole surveying is carried out by Protek personel using an Inertial
Sensing isGyro instrument. About 10 drill holes have been downhole surveyed using a Reflex
Gyro instrument.
Infill drilling: Downhole surveying is carried out by Boliden personel (G1N) using a Reflex
Maxibor II instrument.
In case of an instrument is being sent for service and/or repair, Protek and Boliden personal
loan each other’s instruments.
3.7.3 Sampling
Drill core is logged at Boliden’s core logging facilities in Boliden. Logging is done in
WellCAD software and data is uploaded to an acQuire® database. Sampling adhere to
lithological contacts and generally a sample length of about 2 m is aimed for (>90% of all
samples).
Exploration drill holes are cut with a diamond saw and one half is sent for analysis, the other
half is kept for reference.
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Infill drill holes are not split or sawn in half and the whole core, of the part that is sampled,
is sent for analysis. The remaining part of the core is stored for a year, after which it is
discarded.
3.7.4 Density
During the year, beginning in February 2018, Boliden has been requesting measurements of
specific gravity of drill core samples along with chemical assaying. Every fifth sample is
measured using Archimedes principle and all samples are measured using a pycnometer. An
evaluation of the measurements is ongoing.
During the feasibility study for the mine a density of 2.9 t/m3 was determined to be used for
rock classified as ore and a density of 2.8 t/m3 was determined to be used for rock classified
as waste.
3.7.5 Analysis and QAQC
Sample preparation, chemical assaying and measurements of specific gravity is carried out by
ALS Minerals. As part of the QAQC pulp duplicates are sent from ALS to Hazen Reasearch
for Te analysis. Table 3 shows an overview of the methods used.
Table 3. Overview of ALS’s designation of analytical methods. Over-range method applies to samples where assay result reached upper detection limit of primary method
Method Over-range method
Preparation PREP – 22
Assay Au Au-ICP21 Au-GRA21
Assay other ME-M561 Ag-OG62/Ag-GRA21
S-IR08
Te-AA62
(As, Cu, Pb, Zn)-OG62
Specific gravity (core) OA-GRA08
Specific gravity (pulp) OA-GRA08c
Au-ICP21 is a package of fire assay with an ICP-AES analysis. ME-MS61 is a package of a 4-
acid digestion process with an ICP-MS analysis. Periodic table of elements show which
elements (marked in yellow) are assayed for at the Kankberg mine.
H HeLi Be B C N O F NeNa Mg Al Si P S Cl ArK Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br KrRb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I XeCs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At RnFr Ra Ac¨ Ku Ha
* La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
¨ Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
Quality assessment and quality control is continuously monitored using international
Certified Reference Material (CRM), in-house standards, blanks and umpire lab checks (pulp
duplicates). The aims of the exploration and infill drilling differ slightly and the selection of
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the standards/CRM’s used and QAQC procedures therefore differ slightly to address these
aims.
Infill drilling insert QAQC samples according to these guidelines:
Blanks: 1st blank as the 5th - 10th sample, rate 1:50, and after visible gold and/or
particularly strongly mineralised zones
Standards: rate 1:50, grade of standard reflecting suspected grade of mineralised
zone, proportion; 10% low grade (G315-3), 80% medium grade (G913-8) and 10%
high grade (62e/f)
Check assays: rate 1:50, limited to sample series of more than 50 samples, anywhere
in sample series
This result in an average QAQC usage of approximately 5.4% (standards = 2.7%, blanks =
1.7% and check assays = 1.0%).
Table 4. Overview of standards used. During the year, supply of OREAS 62e ran out and Oreas 62f was introduced instead
Type Elements Provider Product Code Gold by Fire Assay (ppm)mean
Gold by Aqua Regia (ppm)mean
Silver (ppm)mean
CRM Au Geostats Pty Ltd
G315-3 1.97 1.97 3.0
CRM Au Geostats Pty Ltd
G913-8 4.87 4.93 8.09
CRM Au OREAS 62e 9.13 9.37 9.86
CRM Au OREAS 62f 9.71 9.59 5.47
In-house
Au Boliden Mineral AB
BS-AU-2 0.50 2.28
Exploration drilling follows the QAQC recommendation given by the Exploration
department. The guidelines themselves are documented in the internal document (Munck, N;
C20556). This result in a QAQC sample frequency of ca. 3% in-house standards, 1.5% CRM,
2% blanks and 0.5% check assays.
3.8 Exploration activities and infill drilling
During the year, a combined total (exploration and infill) of approximately 48 100 m were
drilled. Out of this approximately 7 000 m were exploration drilling on targets outside the
block model extends.
The block model is currently updated twice a year, and between bm_G1N2017_2_2 (as pr.
Sept 20, 2017) and bm_G1N2018_2 (as pr. Sept 20, 2018) 238 new drill holes of 43 933.05 m
have been added to the dataset used for the update.
Exploration drilling was focused on areas above and below the current Life of Mine Plan
(LoMP) whereas infill drilling mainly focused on drilling areas within the LoMP to required
level of confidence for upgrading reserve categorization (Figure 6).
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Figure 6. Exploration drilling (red) and infill drilling (green). LoMP presented by the block model in categorization colours. A) looking west, B) oblique looking southwest
3.9 Mining methods, mineral processing and infrastructure3.9.1 Mining methods
The mining method in the Kankberg mine is a cut and fill process. The ore is mined in 6 m
high horizontal stopes (7 m if it is a bottom stope). The stopes are stacked into levels, which
are accessed from the ramp (Figure 7). The mining starts from a bottom undercut and
advances upwards. The mining cycle is comprised of; drilling of the ore, loading of blast
holes, blasting, loading of the ore, cleaning of the exposed rock and reinforcing with
cemented iron rods and shotcrete (Figure 8). Once the stope is mined, media like water,
power supply and ventilation is retreated, as the stope is backfilled with waste material. The
fill material serves both as support for the stope walls and as working platform for the next
stope. The width of stopes varies between 4.5m to 10m. Where the width of the stope
exceeds 10 m, pillars of 6 x 6 m are placed (solid reinforced rock left behind) at 10 m interval
within the stope. On average 4 to 5 different stopes are in production at any given time and
one primary backfill area.
Figure 7. Schematic illustration of mining method
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Figure 8. Simplified view of the mining cycle
3.9.2 Mineral processing
Ore is delivered by truck to the industrial area where each truck is weighed on a truck scale
in order to determine the tonnage arriving to the industrial area. Ore arriving at the industrial
area is either taken directly into the processing plant or stored in a stockpile. Separate stock
piles are kept for each of the individual mines in the Boliden area. Ore from the different
mines is processed in campaigns where fresh ore from the mine is combined with ore from
stockpiles. The feed tonnage to the processing plant is determined using a weighing system
with a stationary belt scale. Feed tonnage and weights from the trucks scale are used to
determine current tonnage on the stockpiles.
In the processing plant the ore is ground in two stages (Figure 9). The primary mill is a fully
autogenous mill and the secondary mill is a pebble mill fed with pebbles extracted from the
primary mill. The ground ore is classified using screens and hydrocyclones. A gravimetric
concentrate containing coarse grained gold bearing minerals is produced in the grinding
circuit. The gravimetric concentrate is packed in big bags and delivered by truck to the
Rönnskär smelter.
Flotation is used to produce a precious metals and tellurium concentrate. The concentrate is
accumulated in a leaching tank over a four to five week campaign. After the completion of a
campaign, the concentrate is leached with hot cyanide leaching. The gold containing solution
is then separated from the tellurium-rich leach residue using a belt filter. Electrowinning is
used to precipitate the precious metals in the solution to a sludge that is melted and cast into
doré bullions that are delivered to the smelter.
The tellurium bearing leach residue is leached in a different leaching process in order to
recover the tellurium to a tellurium cement, which is packed in big bags and sold to
customers.
Cyanide leaching at ambient temperature is performed on flotation tailings. Gold and silver is
leached and recovered similarly to gold in the hot leaching process.
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Metallurgical accounting where a sum of products calculated using assays from daily
composite samples of main process streams and assays and tonnage for delivered products
together with feed tonnage is used to determine the head grade of the ore.
Figure 9. Simplified overview of the different stages of ore processing
3.9.3 Infrastructure
The infrastructure comprises a main ramp system extending downwards from the old
Kankberg mine to a main level at -400z below surface, where workshop facilities,
underground control room, crew quarters and storage of different kinds are located (Figure
10). From there the ramp leads to a northern ramp and southern ramp system, which both
extends upwards and downwards. The ore bodies are located between the northern and
southern ramp system. The main control room is located above ground.
Ventilation, water management, power supply, communications and control systems are
integrated to create a fully monitored and to a large degree automated control and
management environment of the mine.
Figure 10. Inclined view of the infrastructure, looking west
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3.10 Prices, terms and costs
Boliden’s planning prices, which are an expression of the anticipated future average prices
for approximately 10 years, are presented in table 5. Ore value based upon planning prices,
recovery and grade are presented in Table 6.Table 5. Metal prices and currency rates
Metal prices Budget
2019
LTP
2020->
Gold USD/tr.oz 1 227 1 200
SEK/kg 351 381 289 357
Silver USD/tr.oz 14.8 17.0
SEK/kg 4 241 4 099
Tellurium USD/kg 35 30
SEK/kg 312 225
Currency rates Budget
2019
LTP
2020->
USD/SEK 8.90 7.50
EUR/SEK 10.62 8.85
EUR/USD 1.19 1.18
Table 6. Budget and long term ore values for planning. NSR = Net Smelter Return
ORE VALUE (NSR)
Element
BUD LTP
Factor(SEK/t* grade)
Grade Recovery(%)
Value(%)
Factor(SEK/t* grade)
Grade Recovery(%)
Value(%)
Au 306.61 3.92 87 96 247.17 3.29 86 96
Ag 1.62 11.9 34 2 1.38 10.2 34 2
Te 0.18 194.1 56 3 0.13 172.1 56 3
Budget and LTP prices are used for budget and long term planning respectively. The mining
cut-off 525 SEK/t is used to guide mining design and in reserve and resource estimation. A
marginal cut-off of 300 SEK/t is used for material in stopes that is below mining cut-off, but
that needs to be mined anyway. The stope as a whole needs to be at or above 525 SEK/t.
Mining, transportation and processing costs are outlined in Table 7.
Table 7. Costs
Costs (SEK/t)
Mining (except transport of ore in mine) 335
Transportation of ore in mine 40
Transportation of ore 25
Process (without fixed expenditures) 125
Total 525
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3.11 Mineral Resources
Using commercially available software packages (Leapfrog, Datamine Studio, Snowden
Supervisor) a 3-dimensionel block model is created into which grade estimations are
interpolated. The project limits and coordinates are in the local Boliden mine system,
“G1NSYSTEMET”. The overall model extends and parameters are outlined in Table 8. The
parent block size of 6*6*6 m is based on drill hole spacing of approximately 10-20 m. For
the purpose of short term planning a sub-blocked model (block sizes down to 1.5 m) based
upon the same estimation parameters is created.
Table 8. Parent block model parameters
Origin Cell size Number
of cells
X 3897 6 110
Y 997 6 90
Z -753 6 110
Statistical and geostatistical studies, sample length analysis, compositing, variogram analyses
define the estimation parameters. Domaining is done on gold grade shells implicitly modelled
in Leapfrog. These grade shells are; 0.5 ppm (waste grade, WG), 1.0 ppm (low grade, LG)
and 2.0 ppm (high grade, HG). The blocks affiliation with grade shells are written into the
block model. The grade estimation is done using ordinary kriging. Block model validation is
done using statistical comparison of composites against block model estimates, validation
plots and visual validation against informing composites. Mineral Resource is classified into
Measured, Indicated and Inferred category. Only small portions of the block model remain
unclassified. The Mineral Resource classification is based upon evaluation of drill hole
density and continuity of mineralization (slope of regression is used as a rough quantifier for
the quality of the block estimate). Generally a sample spacing of at least 60x60 meters is
required for Inferred, 20x20 meters is required for Indicated and 10x10 is required for
Measured.
The block model is covered by what is regarded as mined-out, LoMP (mining design) and
outside LoMP volumes (Figures 11 and 12). Only small isolated parts (not shown in Figures
11 and 12) of the block model are not covered by these volumes.
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Figure 11. Oblique view (looking southwest) of the category classification of the block model. Infrastructure and mined-out shown in grey
Figure 12. View of W - E profile (A) and S - N (B) profile of the category classification of the block model
The reported Mineral Resource (Table 9) is the portion of the block model within the outside
LoMP volume, including sill pillers and inferred resources that lie within the LoMP. The
Mineral Resource is reported from the high grade shell only.
The Mineral Resources and Reserves are reported with waste rock dilution and recovery
percentage per category as presented in Table 9.
Table 9. Waste rock and dilution per category
Waste rock
dilution (%)
Recovery
(%)
Category
3.5 100 RESCAT=1 (Proven) Reserve
15 85 RESCAT=2 (Probable) Reserve
3.5 90 RESCAT=3 (Measured) Resource
15 75 RESCAT=4 (Indicated) Resource
20 70 RESCAT=5 (Inferred) Resource
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3.12 Mineral reserves
The reported Mineral Reserves (Table 11) are based on the LoMP (mining design). In general
Mineral Resources that are covered by the LoMP are converted into Mineral Reserves (Table
10).
Table 10. Resources conversion
Mineral Resources into Mineral
Reserves conversion
(only within the LoMP)
Resources Reserves
Measured → Proven
Indicated → Probable
Inferred Not converted
Vertical pillars within the LoMP are not included in the Reserves since it is unlikely that they
can be mined.
Sulphur and Copper are not represented in the ore value.
Table 11. Mineral Resources and Mineral Reserves Kankberg 2018-12-31
Classification kt Au
(g/t)
2018Ag
(g/t)Te
(g/t)Bi
(g/t)kt Au
(g/t)
2017Ag
(g/t)Te
(g/t)Bi
(g/t)Mineral Reserves
Proved 2 720 3.8 12 182 94 2 410 3.8 11 181 102
Probable 1 510 3.4 8 153 81 2 130 3.5 10 168 86
Total 4 220 3.7 10 171 89 4 530 3.7 11 175 95
Mineral Resources
Measured 260 4.0 11 155 88 190 3.8 8 130 91
Indicated 600 5.2 7 151 97 310 4.7 8 117 67
Total M&I 860 4.8 8 152 94 500 4.4 8 122 76
Inferred 1 390 5.2 9 209 137 1 360 5.5 8 168 109
3.13 Comparison with previous year
Mineral Reserves have decreased by 311 862 t compared to last year. This is year no new
stopes have been added to the LoMP. The mined out material of 456 903 t has only partially
been compensated by 145 042 t added by changes in mining design brought about by change
in economic parameters (NSR) and results of infill drilling (Table 12).
Boliden Summary Report, Resources and Reserves 2018, Kankberg – Åkulla Östra| 19
Table 12. Changes to mineral reserve
Mineral Resources have increased by 385 735 t. This is mainly due to results of exploration
adding 292 483 t and changes of mining design, which added 93 252 t in the inferred
category (Table 13).
Table 13. Changes to mineral resource
Boliden Summary Report, Resources and Reserves 2018, Kankberg – Åkulla Östra| 20
3.14 Reconciliation
Reconciliation is done every month (Table 14) and summarized on a yearly basis (Table 15).
Reconciliation at Kankberg is complicated due to overlapping time-shifted timelines of
production, processing and final reporting of result from the smelter.
Table 14. 2018 monthly reconciliation of mine production and mill output
Month
Mined according to grade models Mill output
ton Au Ag Te NSR ton Au Ag Te NSR
t g/t g/t g/t kr/t t g/t g/t g/t kr/t
Jan 42 250 4.3 11.5 230.4 1 406 35 562 3.9 8.7 155.4 1 152
Feb 37 728 6.3 10.7 183.8 2 013 52 762 5.3 11.7 187.9 1 648
Mar 38 921 6.3 9.5 181.2 2 021 27 678 5.1 12.1 153 1 574
Apr 36 550 3.7 9.0 144.6 1 197 30 996 5.8 10.9 130.6 1 914
May 38 663 2.6 8.1 136.7 850 46 860 3.1 13.0 138.3 1 123
June 31 065 3.2 8.6 140.2 955
July 11 768 2.6 27.0 150.7 868
Aug 44 623 2.0 8.7 175.1 615 60 413 2.0 7.0 127.0 645
Sep 30 388 3.9 11.2 213.5 1 174 52 171 3.3 11.0 292.0 1 042
Oct 51 962 3.9 12.1 188.1 1 185 36 180 5.2 13.3 201.8 1 609
Nov 55 758 6.5 14.1 237.6 2 062 24 779 8.2 14.3 295.4 2 722
Dec 49 071 4.5 11.9 205.8 1 424 48 604 4.3 9.7 176.3 1 458
2018 456 979 4.4 10.7 188.3 1 378 427 773 4.2 11.3 182.5 1 364
Graph 1. 2018 monthly reconciliation of mine production and mill output
Table 15. Yearly reconciliation of mine production and mill output
Year
Mined according to grade models Mill output
ton Au Ag Te NSR ton Au Ag Te NSR
t g/t g/t g/t kr/t t g/t g/t g/t kr/t
2012 174 878 2.7 7.7 121.9 1 043 108 949 2.3 4.7 109.0 965
2013 246 542 3.5 7.2 126.3 1 073 324 755 3.2 8.7 133.6 947
2014 324 534 3.5 9.5 149.1 1 044 339 798 3.7 10.1 160.8 1012
2015 371 633 3.5 9.7 183.0 1 057 377 019 3.1 10.2 157.6 937
2016 413 517 3.5 8.8 161.4 1 008 412 345 3.2 11.3 164.3 977
2017 405 995 4.0 9.3 165.6 1 293 404 422 3.5 12.6 147.6 1 106
Boliden Summary Report, Resources and Reserves 2018, Kankberg – Åkulla Östra| 21
Graph 2. Yearly reconciliation of mine production and mill output
Kankberg also do reconciliation against Mill Head Grade. Stream sampling from the mill
input (after grinding stage) creates a daily composite sample (Head Grade sample), which is
analysed at the Mill Lab (Fire Assay). Previous study (2017) of daily composite samples has
shown that the analysis of composite samples is a good approximation for the grade of the
ore entering the mill. The reconciliation of Mined vs. Head Grade is presented in Table 16.
Table 16. 2018 monthly reconciliation of mine production and mill head grades
Month
Mined according to grade models Mill head grade
ton Au Ag Te ton Au Ag Te
t g/t g/t g/t t g/t g/t g/t
Jan 42 250 4.3 11.5 230.4 35 758 4.1 11.0 184.0
Feb 37 728 6.3 10.7 183.8 52 762 5.2 12.4 183.0
Mar 38 921 6.3 9.5 181.2 27 038 7.4 13.1 217.0
Apr 36 550 3.7 9.0 144.6 30 996 5.3 9.8 176.9
May 38 663 2.6 8.1 136.7 46 860 2.9 9.6 153.7
June 31 065 3.2 8.6 140.2
July 11 768 2.7 10.8 141.3
Aug 44 623 2.0 8.7 175.1 59 134 2.2 9.0 133.1
Sep 30 388 3.9 11.2 213.5 51 580 3.3 10.9 215.4
Oct 51 962 3.9 12.1 188.1 36 180 5.0 13.8 208.6
Nov 55 758 6.5 14.1 237.6 24 779 10.1 17.6 314.0
Dec 49 071 4.5 11.9 205.8 47 789 6.1 14.3 228.9
2018 456 979 4.4 10.7 188.3 424 643 4.6 11.8 192.4
Boliden Summary Report, Resources and Reserves 2018, Kankberg – Åkulla Östra| 22
Graph 3. 2018 monthly reconciliation of mine production and mill head grades
Table 17. Yearly reconciliation of mine production and mill head grade
Year
Mined according to grade models Mill head grade
ton Au Ag Te ton Au Ag Te
t g/t g/t g/t t g/t g/t g/t
2017 405 995 4.0 9.3 165.6 419 673 3.8 11.4 165.8
2018 456 979 4.4 10.7 183.8 424 643 4.6 11.8 192.4
Stock pile at Kankberg held 8 415 t of ore at the beginning of the year and 48 765 t of ore by
the end of the year.
Boliden Summary Report, Resources and Reserves 2018, Kankberg – Åkulla Östra| 23
4 REFERENCES
Allen, R.L., Weihed, P., Svensson, S-Å. (1996): Setting of Zn-Cu-Au-Ag massive sulphide
deposits in the evolution and facies architecture of a 1.9 Ga marine volcanic arc, Skellefte
district, Sweden. Economic Geology 91, p.1022-1053.
Kathol, B., Weihed, P (eds.). (2005): Description of regional geological and geophysical maps
of the Skellefte District and surrounding areas, ISBN 91-7158-678-4, SGU: Ba 57
Pan-European Standard for reporting of Exploration results, Mineral Resources and Mineral
Reserves (The PERC Reporting standard 2017.) www.percstandard.eu
4.1 Internal references
For access to internal references contact author or the Head of Department of relevance.
Agmalm, G. (2011): Kankberg, Åkulla Östra mineralization Feasibility Study. Boliden DMS#:
474882.
Bohlin, N.-J. (2010): Mineralogical study of ore samples from Åkulla Östra. Boliden,
TM_REP2009/037.
Baldwin, S. (2018): Kankberg campaign Reconciliation DV_MEMO 2018/01, Boliden DMS
#11900535.
Fahlgren, J. (2015a): A lithogeochemical review of the Kankberg Au-Te deposit, Boliden
Area. Boliden, GP2015-25.
Fahlgren, J. (2015b): GeoGuide_Kankberg_AuTe_Geology_JF_20150415.
Lundberg M. (2018): Mineral processing, Pers. Comm. 2018.
Lundh, J., Holmen-Fröberg, S., Nordfeldt, P., Munck, M., & Wasström, A. (2016):
Kankberg/Åkulla Östra Au-Mineralisation: Exploration Report, 2015 to 1Q2016. Boliden,
GP 2016-20.
Munck, N. (2017): U QA_QC Guideline and work flow (C20556).
Voigt, B. (2017): Kankberg/Östra Åkulla Au-mine, Mineral Reserves and Resources as of
2017-12-31, Boliden Mineral Reserves and Resources Report 2017, DMS# 1160696.
Voigt, B. (2018): Reserves and Resources G1N 2018-12-31, Boliden Mineral Reserves and
Resources Report 2018 (Excel), DMS# 1307888.
Wasström, A. (1997): Au-mineraliseringen i Åkulla Östra. Boliden, GP97003.
Wasström, A., Agmalm, G., & Nilsson, P. (1999): Exploration Report- Status Report 1999
Åkulla Östra Mine Investigation- Geology. Boliden, GP 99 021.
Boliden Summary Report, Resources and Reserves 2018, Kankberg – Åkulla Östra| 24
Wasström, A., Agmalm, G., & Sandström, B. (2009): Åkulla Östra Au-mineralisation and
resource estimation 2007-2009. Boliden, GP 2009-47.
Žižek, T. (2018): Mining methods, Pers. Comm. 2018.
Åberg, L. (2018): Mineral Resource estimate for Kankberg, Boliden Ore Reserves Report
2018.
Boliden Summary Report, Resources and Reserves 2018, Kankberg – Åkulla Östra| 25
Appendix 1
Brief History
1927 Exploration started in the Åkulla area.
1928 - 1933 Electrical ground measurements. At Åkulla Östra Cu-Au-Zn mineralisation
was found in 4 drill cores.
1938 A drift is made from Åkulla Västra under this mineralisation. A Cu-Au
mineralisation associated with quartz-filled cracks was discovered at a depth
of 130 m.
1939 Åkulla Östra consists of several small sulphide lenses. The drift was filled
with water.
1943 - 1952 Geological exploration and geophysical ground measurements.
1967 - 1969 Drilling and planning for open pit.
1984 Some drill holes drilled in the “Deep-seated sulphide ore” project. No new
mineralisations were found.
1991 A new exploration campaign with geophysical ground measurements and
geological surveying.
1994 Detailed geological outcrop logging and a new drilling campaign. The first
drill hole intersected a new 10 m wide massive pyrite lens at a depth of 260
m in December. The grades were ‘too low’ but the drilling campaign
continued due to geological and geophysical interpretations indicating
mineralisation at a deeper level.
1995 On 1 March a new type of Au mineralisation was found in a strong Si-Al
alteration zone at a depth of 350 m. This alteration zone had mineable
thicknesses with high Au contents.
1996 First metallurgical tests on sample material from drill cores.
1997 - 1998 Åkulla Östra B lens is mined in open pit.
1997 Ramp commenced towards Åkulla Östra Au mineralisation.
1998 - 1999 Exploration within the Åkulla Östra Mine commenced. 20 drill holes.
1998 Processing tests on 1 350 t from the ramp.
2004 - 2006 Åkulla Östra Mine exploration continued. Exploration department drilled
86 drill holes of which 3 were extensions of existing drill holes.
2006 Test mining and a pilot processing test on 11 100 t. Some material from the
1999 ramp was used to clean the line.
2007 A drilling programme of 27 drill holes was initiated, of which one was an
extension of an existing drill hole.
2008 The drilling programme was concluded. Conceptual study on extraction of
tellurides shows good potential for profitability. Analyses campaign on
tellurides.
2009 - 2010 A new ramp is started and a new drilling campaign is completed.
2011 - Infill drilling programme commences.
2012 - Production begins.