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

comprises double salt precipitation of the light rare earths followed by sequential solvent
extraction steps to isolate zirconium, the rare earths, niobium, and tantalum.
Double salt precipitation, which is a classic means of separating the light and heavy rare earths,
involves the addition of sodium ion to a sulphate solution of the rare earth elements. This has
been tested and the resulting product metathesized and dried to produce a light rare earth
hydrated oxide precipitate. The yield of light rare earths to this precipitate was high (up to 96%)
but some co-precipitation of yttrium and heavy rare earths was observed. This does not
represent a loss of heavy rare earths since they <strong>report</strong> to the light rare earth product but further
work is under way to optimize the double salt precipitation step and other solution operations.
Solution reduction tests have been completed and a suitable process developed. Solvent
extraction tests have been done and more work is planned.. Based on available data and
published information from other proposed or actual solvent extraction plants, the plant included
in the pre-feasibility study consisted of three sequential solvent extraction circuits for recovery of
zirconium, rare earths, and niobium and tantalum.
It is expected that testwork will continue on all aspects of the hydrometallurgical process over
the next several months and will culminate in a hydrometallurgical pilot plant planned for late
2011.
The net recoveries expected, as <strong>report</strong>ed in the earlier Technical Report, are provided in Table
16-1. Testwork is continuing to confirm that these recoveries are obtainable from other samples
from the Thor Lake project.
Table 16-1
Flotation and Hydrometallurgical Recoveries
Avalon Rare Metals Inc. – Thor Lake Project
Feed to
Concentrate
Concentrate to
Product
Net
Recovery
ZrO 2 89.7% 90.0% 80.7%
TREO 79.5% 93.0% 73.9%
HREO 79.5% 93.0% 73.9%
Nb 2 O 5 68.9% 80.0% 55.1%
Ta 2 O 5 63.0% 50.0% 31.5%
Technical Report 43-101 – March 13, 2011 Page 16-4
Prepared by Avalon Rare Metals Inc.