warwick grigor comments, page-11

Diamond drilling ?Ernest henry mine uses rc drilling to define their resource..here is the full article dated jan 2003..
Brokers
demanding accurate
projections of mineral inventories,
mine operators have turned to
state-of-the-art equipment which
can help provide the answers.
One of the programmes for ore
estimation at MIM Holdings Ltd’s
Ernest Henry copper-gold mine in
north west Queensland is from
acQuire Technology.
In a presentation to an acQuire
users conference in Perth, Ernest
Henry mine geologist Dwayne
Povey said that over the 15 years of
the planned mine life more than
700 million tonnes of ore and
waste will be mined.
The mill provides for up to 10 mt
per annum of ore to be extracted
from the open cut to produce
about 360,000t of concentrate
containing 100,000t of copper and
125,000 ounces of gold.
On current designs, the final
dimensions of the pit will see a
perimeter of 5 km, a diameter of
1.3 km and a total depth of 570m.
Povey said the deposit lies
within a south-east plunging
breccia system developed in a
sequence of altered porphyritic,
intermediate volcanic rocks.
The breccia body dips 30-50°
SSE and lies between a hanging
wall sequence of variable altered
felsic volcanic rocks and a footwall
sequence of carbonate altered
mafic volcanic rocks and siltstone.
Economic mineralisation is
hosted by a breccia comprising
strongly altered and replaced
felsic volcanic fragments in a
matrix assemblage of
predominantly magnetite,
chalcopyrite and carbonate.
The magnetite, copper and gold
minerals are thought to have been
introduced to these rocks around
1,500 million years ago as a result
of the nearby intrusion of a large
granite pluton.
Fluids from the granite passed
through fractures, altering and
replacing some minerals and
forming the minerals. The
combined thickness of the
mineralised sequence is about
250m and the width averages
300m with the orebody open at
depth and to the southwest.
Povey said that to define the
orebody a staggered grid grade
control pattern 15m by 15m RC
drilling is carried out. Holes are
typically 48m deep with 2m
sample intervals. An on-site
laboratory assays all grade control
and blasthole samples.
Earlier this year an upgrade of
acQuire saw transfer of all access
databases to data entry objects in
acQuire, and this required retraining
of geotechnicians and
simplification of acQuire with
shortcut keys.
The upgrade saw data triggers
and validation tables integrated,
eliminating errors created through
matching access data to acQuire
which provides for error-free
confidence.
Also part of the upgrade has
been specific built forms allowing
geotechnicians to view various
datasets which include waste rock
characteristics, high sulphur
content and at the same time
provide for high quality control,
and load checking for gradecontrol
drilling programmes.
Page 89
Exactness is a prime
requirement with modern
technology in establishing
ore reserves and resources.