After 75 years
Scene» deep in the reopened Ore Knob mine in Athc Counly. A. A Dundos hold» ftalilight during
"mucking oul" operotion; right, perfect core reco.er, »ho.n by Vol Sheet», diamond drill operotor,
on the 840-foot le.el— (Photo» from "Mining World.**)
Copper!
North Carolina*» rich
old Ore Knob field
once more is put
into production.
North Carolina's first major copper
mine since ihe late IX(H)’s is currently
under development by Appalachian
Sulphides. Inc., wholly owned sub¬
sidiary of the Nipissing Mines Co..
Ltd., of Toronto, Canada. Appa¬
lachian Sulphides is developing an ex¬
tension of the historic Ore Knob ore
body, located II miles cast of Jeffer¬
son, in the northwest corner of the
State.
Shaft sinking has been completed
and mine development work is now
under way. Construction of the 700-
ton-per-day mill started in June 1956.
The first workings at the Ore Knob
property date back over a century to
1855. At that time the ore body was
developed by four shafts varying in
depth from 30 to 90 feet. The ore.
"black copper" or chalcocitc, was re¬
ported to have averaged 20 per cent
copper.
After a short period of initial opera¬
tion, the mine was not worked regu¬
larly again until 1873 when it was
taken over by new management. Seven
additional shafts were sunk and the
four existing shafts were deepened.
Two of the shafts exceeded 400 feet in
depth and the remainder ranged from
60 to 250 feet deep. A smeller with
two reducing furnaces and a refining
furnace (using charcoal for fuel) was
constructed on the site.
By 1883 the price of copper had
declined to 9 cents a pound and the
mine was closed. During the 10-year
period from 1873 to 1883, it is esti¬
mated that over 200,000 tons of ore
were mined and 25,000,000 pounds of
copper recovered.
In December of 1942 the U. S.
Bureau of Mines started a diamond
drilling program to determine the
southwest, northeast, and downward
extensions of the deposit. Twenty
holes, totaling 4,945 linear feet, were
drilled along the strike of the vein, and
75 feet of drifting and cross-cutting
were completed for underground drill
stations. Several of the holes from an
16
underground station on the southeast
side of the vein indicated that the ore
body pinched down to narrower
stringers and plunged to the southwest.
Nipissing Mines became interested
in the Ore Knob property in 1953 and
the present manager, Philip Eckman.
supervised an exploration program
that included an electro-magnetic sur¬
vey. Diamond drilling, contracted by
Sprague & Hcnwood, Inc., of Scranton.
Pennsylvania, was started in Decem¬
ber 1953. Thirty-eight holes, totaling
27,752 feel, were drilled primarily on
the southwest projection of the ore
body indicated by the Bureau’s results.
Ore intersections were made in 15
holes with deepest ore indication at
1,150 feet
Copper Averages 3.0 Per Cent
Based on the results of diamond
drilling, the ore body averages 14.4
feet in width, is at least 3,300 feet
along the strike, has a rake length of
3,550 feet, and varies from 200 to 550
feet in vertical height. Present ore re¬
serves stand at 1,330,300 tons of 3.0
per cent copper and 14 per cent
sulphur.
'Hie ore deposit can best be de¬
scribed as a steeply dipping (70°)
tabular sulphide body striking N.
64° E. and raking to the southwest at
20°. It is thought to be a mineralized
fault and consists of brccciatcd frag¬
ments of wall rock surrounded and re¬
placed by sulphides. Ore minerals arc
This article is a digest of an article
appearing in “Mining World,” and is
republished by special permission.
chalcopyritc. pyrrhotitc, and pyrite,
with very minor amounts of sphalerite.
Shaft Sunk to 1,037 Feel
A vertical, three-compartment shaft
was collared in May 1955. Cowin and
Company, mining contractors of Bir¬
mingham. Alabama, was awarded the
contract to sink the shaft to a depth of
1,037 feet and to cut six stations. The
job was completed in July 1956.
How Ore Will Be Mined
As the shaft was sunk in the foot-
wall of the ore body, crosscuts will be
driven to intersect the ore. Initial work
started on the 560, 700, and 840
levels. Drifts will be driven along the
footwall of the ore body and waste and
ore passes will be raised from the 840
to the 560 level.
Present knowledge of ground condi¬
tions favors mining by either sub-level
sloping or shrinkage sloping. Ore will
be mined in blocks with pillars left be¬
tween blocks. Loading points will be
in short crosscuts driven at right angles
to the drift and spaced 25 feet apart.
Ore and waste will be hoisted in
3-ton bottom dump skips by a Nord-
berg
б1/*
-fool by 42-inch double-drum
hoist powered by a 250-hp. G.E. “Tri-
Clad” induction motor. The skips will
dump directly into a partitioned steel
bin with a storage capacity of 700 tons
of ore. and 150 tons of waste.
Results of Flotation Tests
Denver Equipment Company, Den¬
ver. Colorado, designed the crushing
and milling flowsheet.
The Ore Testing Division of Denver
(Continued on page 28)
THE STATE. APRIL 20. 195*7
