Charter Oak Mine : exploring Montana's mining history on the Helena National Forest

2004·0.27 MB·English

by  United States. Forest Service

Historic, Archive Document
Do not assume content reflects current
scientific knowledge, policies, or practices.

Oak
Charter
Exploring Montana
s
Mining History
on the
Helena National Forest
The Mill Process
, ,1
10
.
l
Loadout Deck
1.
Aerial trambucketsandmetal orecartscarried
leadandsilveroreexcavatedfrom2000leetof
undergroundworkings towooddecks at tlie top
of tlie mill.Only theuppertram towerruin Las
survived.Minersdumpedwasterock from tbeir
diggings into Luge(nowpartly reclaimed)piles
outside of tunnel entrances (adits).
2. First Ore Bin and Chute
On tliewooddecks,minersemptied tlie metal-
bearing ore intoalarge,open bin at tlietop of
tlie mill. Down acliute tliey tossed over-sized
or 11011-orebearing rock (gangue).
3. Pacific Jaw Crusher
Inside tlie mill,orewasslioveledfrom thebin
intoaPacificJawCrusher.Itshingedjaw
movedforwardandaway fromastationary
jaw,providing immensecrushing power.
Cobb hammersand ironswere used to
knockoffgangueandclearjams.Handsand
fingers were at risk when cobbing.
3
4. Conveyor Belt
A
conveyorbelt carried tlie crushedore toasecond
orebin at the centerof the mill building.Itsdrivers
were tightenedorloosenedby ahomemadebucket
counter-weightfilledwithscrap iron.
5. Second Ore Bin
The secondorebin,located between thejawand
ballcrushers,isstillfullolcoarsely crushedmetallic
ore ready lorfurtherprocessing.
6. Ore Feed
Depending on coarseness,ore in the second bin
waseither run through agrizzly screener or fed
directly into theball mill.Tirevibratinggrizzly
screenedover-sizedpiecesandsent thesifted
oretotheball mill.
7. Ball Mill
A
rotatingball mill,filledwithfist-sizedsteelballs,
waterandchemicals,thoroughly pulverizedtheore
concentrate intoa finepulp.Thiswasavery noisy
part of theoperation.Discarded millingballscan
be seen inside and outside the mill building.
8. Rake Classifier
A
classifiernext totheball mill rakedtke
orepnlpup anddown a longtrough.Tkis
komemadeequipment separated tke finebj
groundoretkatwasready forflotation from
coarsermaterial tkat still neededmore
pulverizing in tkeball mill.
A
9. Denver Sub- Flotation Cells
Finishedpulpwaspouredfromtkeball mill
intometalflotation tanksorcells,wkickwere
infusedwitkwater,chemicalsandair.Ore
particlesattackedtobubblesas they rose
throughtkecellsandcollectedin athick
froth.Chemicalsconditionedtkepulp(lime,
sulfuricacid),createdbubbles(pineoil,
cresylicacid),attractedmineralstobubbles
(xantkates),andactivated(coppersulphate)
ordepressed(lime,crjanide)flotationof
particularminerals.
10. Drying Area-Loading Deck
Thefrothconcentratewasdried,bagged,
storedand then sent to tke smelter in East
Helena.Tkecellswereflushed intoanow
reclaimedtailingspileon tkeLittleBlackfoot
Riverfloodplainbelowtkemill.
Past to Present
1912 The Charter Oak lode claim is
locatedby FredHopkins; first silver-leadore
production reported in 1916.
—
1920s Annual silver-lead ore production
fluctuateswidely from 1 to164tons.
—
1930s Operations cease during the Great
Depression.
—
1940s Fred Hopkins leases mine&to his
brotherRalph,wholormsHopkins Sons
Mining Company; operation significantly
upgradedtoproducecriticalWorldWarII
strateg—icminerals—lead,zincandcopper.
GovernmentOrderL-208closes
all minesnot producing metals forthewar
effort.Thesearepeakproductionyearsat
the mine.
—
1930s The mine is leased to James T.
Bonner,who forms theCharterOakMining
Company and upgrades the mill equipment.
There is intermittent production at the mine.
Assaying ores from nearby mines alsooccurs.
—
1960s Last reported ore production.
—
1970s Claims above Charter Oak are
workedbu John Hopkins,son ofRalph
Hopkins,Henry Lauri and otherElliston
miners.
—
1980s The claims and mill are sold to
LeeAdams,whounsuccessfully attempts
actjanideheapleachoperation.
—
1990s Mill tailings spotted in the Little
BlackfootRiver;the minecomplexisgiven
totheForest Service;reclamationand
historicpreservation projectscompleted.
—
2000s The site is listed in the National
RegisterofHistoricplaces in 2001 and is
open forpublicvisitation.
——————
.
NATIONAL AGRICULTURAL LIBRARY
022506050
— Self-guided Walking Tour
Theself-guidedwalkingtourfollowsalooptrail
constructedby theHelenaHighSchoolX-CelClass.
Themetalpostsdemarcatetkefollowingvarioussite
andminereclamation features.
1 Main residencecakin;onceoccupiedby tkeHopkins
andBonnerfamilies.
2 Old mobile,gasgenerator(minustkemotor);once
usedtopowertkeminingoperation beforeit was
—electrifiedintke1930s.
3 Woodflotationcells;usedduringtkeearliestdays
oftkeoperation.
4 Frenchdrain;aciddischargefrom mineadits is
partiallycleanedbyflowingoverrockfillin
—thissmallditch,constructed1998.
3 Boneyard; old mininganddomesticequipment
representingover60yearsofminingactivities.
6 Aditandminewasterockdumpremovedin1998;
dischargingtunnelandadit.
7 Compressorbuilding;ventilated underground
workingsandprovidedpowerandwaterfortkedrills.
8 Adit:reconstructedtunnelandaditwithminecart
andtracksleadingtomillbuilding.
9 —WorldWarIIvintageballandflotation mill.
10 Assayoffice;usedandupgradedformany years.
Improvements to the CharterOak Mine & Mill
site and the production ofthis trail guide are
a result of a cooperative effort between the
X-Cel Productionsclass of Helena High School,
the Helena National Forest and the Helena
Forest Foundation.
Formoreinformation, pleasecallthe
HelenaNational Forest
at406-449-5201.
Persons ofany race, color, origin, sex. age. religion, or with
any handicapping conditions are welcome to use and enjoy all
facilities, programs, and services of the USDA. Discrimination
in any form is strictly against agency policy, and should be
reported to the Secretary ofAgriculture, Washington, DC 20250.