Tahera
- type of RC drill bits affecting test grade?
Tahera Diamond Corporation is a unique
Canadian-owned diamond mining company. ... Tahera Diamond
Corporation: Announces 2007 first quarter results release ...
www.tahera.com
Tahera Diamond Corporation (TAH:TSX) is
a Canadian diamond mining company headquartered in Toronto, Ontario.
Tahera's Jericho Diamond Mine represents Canada's third, and
Nunavut's first, diamond mine.
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Question
asked on Jun 12, 2007 by Rene
Sugar <rene_sugar2 @gmx.net>
I've got a question that you might want to ask Tahera.
From what I understand, RC drilling breaks up the kimberlite. In one of
Tahera's reports, they mention the grade being affected by the type of drill bit
used.
Also, from what I have read, the 2005 Muskox test results were based upon
samples from core drilling and not RC drilling. The 2006 Muskox test used large
diameter RC drilling. |
Corporate Head Office
Tahera Diamond Corporation
P.O. Box 1020,
T.D.C. Postal Station
77 King Street West
Toronto, Ontario
Canada M5K 1P2
Tel: (416) 777-1998
Fax: (416) 777-1898
Toll Free: 1-877-777-2004
Email: investor_relations@tahera.com
Email: resume@tahera.com |
Given the test results based upon core drill sampling, the test results based
upon RC drill sampling could be significantly under reporting the grade of the
Muskox kimberlite depending upon the type of drill bits used.
What type of drill bits were used by "North West Sequoia drilling of
Calgary" to collect the last Muskox sample?
From Tahera's own data, using RC drilling, the grade returned varies
significantly depending upon the type of drill bit used.
Bit Grade
--- -----
Drag 119 cpht
Mission 47 - 65 cpht
Ballistic 29 - 49 cpht
Digger 12 - 17 cpht
http://tahera.com/Theme/Tahera
/files/OtherReports/rocking
.pdf
Here is the excerpt from the report:
"Information received late in 2005 from De Beers indicates significant
breakage of stones during the RC drilling and sampling program. A number of
different drill bits were used in the program resulting in a wide range of
diamond breakage and recovered grade. The
two drill holes which used a Drag bit had a sample grade of 119 cpht while the
Mission bit
intervals graded between 47 to 65 cpht. The intervals using a Ballistic bit
averaged between 29 and 49 cpht and the Digger bit intervals averaged between 12
and 17 cpht. Recoveries also varied depending on the type of drill bit used. In
total, 37% of the diamonds recovered in the RC sample were significantly broken
(as defined by more than 5% of the original stone being removed, due to fresh
breakage).
This RC sample may have pulverised the rock to the point of crushing larger
diamonds. The De Beers report states that suggestions of stone breakage are much
more evident in the drill chip [RC] sample."
Some comment to
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