technical report on the nechalacho deposit, thor lake project ...

Table 18-2
Development Tonnage Breakdown
Avalon Rare Metals Inc. – Thor Lake Project
Resource Class Tonnage
TREO NMR
‘000 t ppm TREO $/t
Inferred > C$300/t 62 15,425 489
Inferred < C$300/t 67 7,467 210
Indicated > C$300/t 29 16,521 550
Indicated < C$300/t 1 6,856 232
No Class $0/t 135 0 0
Total 294 6,604 206
STOPING
Zones less than 18 m high
Stopes will be mined in a primary and secondary sequence. Primary stopes will be 15 m wide,
while the secondary stopes will be 16 m wide to leave extra space and ensure the maintenance
of good ground conditions in the secondary extraction sequence. There will be a one metre skin
between primary and secondary stopes to minimize backfill dilution. For mineralized zones up
to 18 m high the stopes will be excavated in an overhand cut and fill sequence in one lift. Each
cut will be developed using a 5 m by 5 m heading followed by the slashing of walls resulting in a
15 m by 5 m cut. Adjacent primary stopes will be developed simultaneously in a progressing
chevron pattern. The second lift will begin once the undercuts have been filled with paste.
Primary stopes will be developed with a 5 m wide by 5 m high central drive followed by two 5 m
wide slashes to attain the planned 15 m width. For stopes up to 18 m high the stope
development will commence at the top elevation and subsequent lifts will be taken by benching
the floor using the development jumbos.
Development of secondary stopes will begin once the adjacent primary stopes have been filled.
The secondary stopes will be developed with a 5 to 6 m wide drift down the center of the stope
and the remaining width will be slashed and remote mucked. In the secondary stopes a one
metre thick skin will be left on each side to reduce the amount of dilution from backfill. In the
course of blasting it is assumed that a portion of the skin will fail and <strong>report</strong> to the muck pile.
Zones over 18 m high
For zones in excess of 18 m high the stopes will again be developed in a primary – secondary
sequence with the same widths as above (Figures 18-6 and 18-7). However, for secondary
stopes, the ore will be extracted by long hole stoping. The top cut will be developed to the full
Technical Report 43-101 – March 13, 2011 Page 18-12
Prepared by Avalon Rare Metals Inc.