Bulk Sampling of Mineral Proyects
Bulk Sampling of Mineral Proyects
Bulk Sampling of Mineral Proyects
MINERAL PROJECTS
PDAC Convention 2015
Session: The Economic Implications of Grade
Tuesday, March 3, 2015
DD
One in one million
H
(½ NQ core at 30-metre spacing)
• “Sample” – Representative
A bulk sample should be representative of the deposit geology and
mineralization and should concentrate on the pay-back tonnage
PRESENTATION OUTLINE
• Purposes of bulk sampling
• What constitutes a bulk sample?
• Examples and outcomes
EXAMPLES & OUTCOMES
Project Location Commodity Mining Tonnes Outcome
Verification of Deposit Geology & Grade Estimate
British
Brucejack Au (Ag) U/G 10 300 Updated Feasibility Study
Columbia
Cameron Lake Ontario Au U/G 12 000 Project shelved
Farley Lake Manitoba Au O/P 10 000 Mined 1996 to 1999; 1.7 M t @ 3.9 g/t Au
Meliadine Nunavut Au U/G 33 700 Being developed. Reserves 12 Mt @ 7.4 g/t Au
Nalunaq Greenland Au U/G 23 200 Mined 2004 -2009, 2011/13; 0.7 M t @ 15 g/t Au
Determination of Mill Head Grades
Lockerby Ni-Cu-PGM- Complete
Sudbury U/G Results accepted for metal payment
McCreedy West Au production
Minera Dayton Chile Au O/P tonnage Determination of heap-leach feed grade
Input 100
tonnes
Output 2 x 30 kg Field
Samples
SAMPLE TOWER FIELD SAMPLING
SAMPLE PREPARATION AND ASSAYING PROTOCOL
Source: Snowden
2009
Geology
ation (1 1 0 0 ) Lode
Round 98 W
Iron Form
0) Lode
Quartz Vein (100
(here barren)
Mineralized Iron Formation (1100 Lode)
IF
IF
Quartz
IF Veinlets
Face of Round 98 W
Bulk Gold Grades - Mineralized Iron Formation
(1100 Lode)
Geology - Boudinaged Quartz Vein (1000 Lode)
Round 95 E
Quartz Vein (1000 Lode)
Face of Round 95 E
Face of Round 95 E
Bulk Gold Grades - Boudinaged Quartz
Vein (1000 Lode)
Gold Grade Distribution - Boudinaged Quartz
Vein
(1000 Lode Longitudinal Section)
Grade Continuity
Quartz Vein (1000 Lode)
Grade distribution fairly
erratic requiring tight
drill-hole spacing
Mineralized Iron
Formation (1100 Lode)
Grade distribution more
continuous
High grades at west end
coincident with
secondary quartz-vein
development
Reliability of Meliadine Bulk Sample Results
Sediments outside Lode 298 0.9 2.8 3.1 5 96 0.6 1.2 2.0
Sediments within Lode 354 1.9 5.8 3.1 10 95 1.2 2.4 1.9
Iron Formation, “low-grade” 206 4.7 7.0 1.5 20 95 4.3 5.6 1.3
Iron Formation, “high-grade” 482 17.5 16.8 1.0 90 99.8 17.4 16.3 0.9
Quartz Vein 1000 336 33.2 46.4 1.4 165 98 31.1 36.9 1.2
Sediments with erratic gold-grade populations (high CV) require significant capping
Mineralized units with “well-behaved” gold-grade populations (low CV) require less
severe capping
Statistical evaluation of all gold-grade populations inside a lode is the wrong
approach
Average gold grades 2008: bulk sample 8.8 g/t; capped channels 9.0 g/t; capped
chip panels: 10.9 g/t
Block-Model Predictions and Bulk Sample Results
Spacing Au Au
DDHs Tonnes Au (g/t) Tonnes Au (g/t)
(metres) (ounces) (ounces)
Mineralized Iron Formation (1100 Lode)
Snowden June
20 15 to 30 6 960 8.6 1 924 6 670 9.1 1 960
2008
AEM 2011 40 15 to 20 9 207 10.9 3 231 8 812 11.6 3 279
Boudinaged Quartz Vein (1000 Lode)
Snowden June
11 10 to 50 4 655 27.3 4 114 4 262 20.9 2 872
2008
AEM 2011 43 10 to 20 8 375 15.1 4 068 7 048 15.9 3 596
1100 Lode – Relatively easy to estimate due to steady width and reasonable grade continuity
1000 Lode – Difficult to estimate due to changing width (boudinaged) and poor grade
continuity
PRESENTATION OUTLINE
• Purposes of bulk sampling
• What constitutes a bulk sample?
• Examples & outcomes
• How to treat a bulk sample
• Field sampling and laboratory protocols
• Quality control
• Example – Meliadine Project, Nunavut
• Conclusions
CONCLUSIONS
• Bulk Sampling provides information crucial for a feasibility study
otherwise not obtainable
(Gold) grade verification, including capping levels
Physical and grade continuity (variogram) verification
Determination of drill-hole spacing required for resource estimation
Mining conditions (water) and geotechnical information
Large-scale samples for metallurgical testing
• While expensive, bulk sampling is cheaper (and better for one’s
reputation) than a failed mining investment
• Positive side effects include shortening of pre-production
development once a production decision has been made;
availability of initial crushed tonnage for milling
ACKNOWLEDGEMENT