Gold (Au), capped gold, silver (Ag) and capped silver grades (refer to section 17.3 for
capping levels) were estimated for each vein and stockwork parent block (1m x 5m x
5m for BB, CZ and NZ, and 5m x 10m x 2.5m for SE, SZ and NE) using inverse
distance to the power of two interpolation (ID2
). Nearest neighbour (NN) and ordinary
kriged (OK) estimates were completed for comparison and validation purposes.
The grades where capping was applied are identified by their field names, which
incorporate the grade field and the capping applied.
The strike-length of the Kupol deposit as modeled is close to 4.0 km long. Overall vein
zone orientation strikes north-south with ±25° local variations. It dips steeply to the
east at 70° to near vertical. To best represent local vein orientation, multiple search
orientation domains were created. They controlled search orientation ellipses only;
they were not used as “hard” boundaries to composite selection during grade
estimation.
The final grade estimation plan was the result of numerous test runs. Visual and
statistical checks were completed after each test run, and the estimation plan was
modified to achieve a suitable estimate.
Stockwork and vein blocks were estimated separately; only vein composites were
used to estimate vein blocks and stockwork composites for stockwork blocks. Vein
blocks in the Premola Fault were estimated with vein composites. The grades of other
materials were not estimated.
Au and Ag estimation into the block model was performed using Micromine and
Datamine three dimensional mining softwares. The estimation techniques chosen were
ID2
and OK due to the relatively low coefficient of variation (CV) in the sample data
following the selection of an appropriate capping. The 1 m composites were used for
grade estimation. A three step search strategy was adopted which varies the minimum
and maximum number of samples and for the last search, the search volume was
expanded. The search parameters used in the estimation were oriented to match the
dip and strike of the veins. Estimation parameters used for all grades are presented in