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Collection: Directories and Documents > Pamphlets
Mining Methods in Grass Valley District California From Transactions of the American Institute of Mining and Metallurgical Engineers by J A Fulton and A B Foote (PH 2-6) (1927) (14 pages)
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Page: of 14
~ 600.surface, . the ore is again sorted) and about, 26 ‘per cent, of the ‘aterial
joisted is discarded as waste; nevertheless: about 60 per pent. of ihe ot
Tt is the intention to sink the vertical shaft, and to ae sinking this !':
incline shaft until the two meet. This mecting point
ft down the incline from the! 6300 level, (making it ‘the 8600 level) and .
7
MINING sTHODS Ny GRAB ‘VALLEY, a “OALIPORNTA epee i
material that reaches the mill i is waste.s signe ae Hot ah
Later Develop: 0
.
Since 1922, another yein Hi the ‘North Star min nb, finan an ‘the i
opposite direction to the North Star vein and crossing it’ at the 6300 level, bs
has been developed by an incline shaft underneath the North Star shaft Wie
toa distance of 1000 ft. down the dip of the. yein below. the 6300 level. if me
ill be about 2300.
about 2000 feet vertically below, the 4000 level, where fhe, vertical shaft}.
outs the North Star vein. The vertical shaft will then! pe 3600 ft. deep, .
It is now expected that the two shafts will meet sy the latter part . ee
Hy
ee 1926. ha Sepa sorett {a ee
: . Mine Openings rete Real af a ah
The main incline enact is 6300 ft. long and has anh! average Hah of
26°; its ver tical depth at the bottom is 2400 ft.. The vertical shaft is 1600 j=
ft, deep and meets this incline shaft 4000 ft, from the collar., -Both shafts in
have three compartments; the two skip compartments : are 4 ft. 8 in. by .
5 ft,, the third compartment, which is ‘5 by 5 ft, ig used for the tools . 3
and material cage or truck, pipes, etc. ’'The inclined phaft is timbered .
only in a few places; the vertical shaft is’ timbered with 10 by 10-in. i
wall and end plates with 8 by 10in. dividers. Timber is necessary t0 .
support guides, rails, and pipes. , The ground stands without timbering. H ‘ME
In the vertical shaft, for 40 ft. below the collar, the timbering is kunited : =
f j
on wire lathe; below. that point the timbering is eae le and aac . a
indefinit g Jace 22 years. eae initely. It has now been in p eal turn and traveling j
through the vertical shaft, the skips making verti
the bottom of fhe mine. i Hee baate Na al
“Underrownd. Development ‘f Ae i
Main levels, 5 by 7 ft. in cross -section, ate run at age ont .
on the vein, Water is conveyed } in ener ditohes run eal irl
g-in. pipes for Go i
of the track, As the drifts are run, 24 se, for particularly large, ' ‘
laid; sometimes additional , 4-in. pipes estes
stopes, ‘Ventilation pipes. are usually, g-in, pce sometimes er BP ‘.
are used. ards eh j is ay heey 3 uth d f al : 5
iY youn pos i) ‘ar tha
gratis are not dimbored na ‘al, ce pee Hae is dipped in) i
put i in to, hold up 1900 ‘rooks Hyhere roquired ih Hi
veal } et ag f}
é
down the incline shaft to reach