The photos below are what we saw.
Next to the visitor's center, there were a
number of antique
pieces of mining equipment. This is a steam engine used to run
a water pump.
The outside grounds were nicely landscaped and
included this multiple golden barrel cactus.
The growth pads of the
barrel cactus was filled with intricate structures.
This is a tooth from the
bucket of one of the production shovels. These wear out
and must be replaced every few weeks.
This is a steam-powered hoist.
This is an actual hoist head frame that was
moved to the visitor's center site.
Another steam-powered
water pump.
This is a small shovel bucket. The
current buckets are 6 times bigger.
This is a very early model
gas or kerosene-powered internal combustion
motor. The item on the top is an open radiator
tank. On the ground to the left is a drill bit.
This is a bucket used in
one of their smelter operations at another facility.
This is a 16 cylinder, 4000
cubic inch, 2700 hp diesel motor that puts out 8000 ft-lbs of torque and weighs 15,000 pounds.
Electric motors made rapid
inroads into the mining industry. They were much more efficient
and maintainable
than steam engines. The sled above is a water pump
driven by an
electric motor.
A much slusher bucket and
winch which is used in underground mines.
This is a 310 ton Terex haul truck that can
carry 160 tons of ore. Photos below show the current generation
of trucks.
I can only imagine the
effort required to change a tire.
I am surprised that the
truck was not sold as scrap. The tires are on the order of $80K each
when new.
We piled into the shuttle
bus for the tour and got a view of the tailings pond in the
distance (the white
area). The tailings are powdered rock and are pumped
with water to the pond where the water is reclaimed.
Soon we came upon one of
the current generation Komatsu trucks. This one was chugging up the grade from the
pit carrying overburden for dumping on the rim.
These trucks cost about $5M each and are diesel electric and are run
24/7 until a maintenance cycle is required.
The grade up to the dump
is steep and the trucks can only do about 6 mph when fully
loaded.
The first stop on the tour
was the pit overlook. In mining since the late 1950s,
they have moved 5-6 Panama Canal's worth of material. A
matrix of drill holes are being dug to allow emplacement of
explosive
slurry. These holes can be seen to the left of the drilling rig
in the center of the photo. Once the matrix
is completed, the
holes will be filled with explosive slurry and primers and
the whole shelf will be dislodged and then removed.
Depending on the copper content of the material, it will
either be loaded
into trucks and hauled to the dump site or to the
crusher for ore extraction. The steps on the left represent
the final
slope of the pit. All material not conforming
to that slope will be dispositioned to either the
dump or the crusher over time.
This bucket shovel is removing
overburden for transport to the dump site. The pond at the top of the
photo is at the
local water table. The shovels are electrically
driven with 4160 volt three-phase lines.
A
drilling rig is preparing blasting holes for slurry. Meanwhile, haul trucks are taking
ore to the crusher.
This shelf has already been
blasted into rubble. The rubble is being loaded into the
haul trucks.
Empty trucks
are always available to allow 100% duty cycle on the shovel.
The power cable for the shovel is visible
crossing the light-colored rock.
5-6 buckets are required
to fill a truck.
The haul trucks dwarf
conventional vehicles.
This pit is massive, but
nowhere near the biggest open pit copper operation. That
honor, I believe, goes to the mine at Silver City, NM. Santa Catalina Mountains
and their 9800'
peak are visible on the far horizon.
These trucks get going
over 30 mph when empty on the
downhill run.
The steep grades up to the
dump wall slow the trucks to 6 mph when fully loaded.
One of the settling ponds
where copper concentrate is separated from the processing
fluids.
Depending on the ore recovery schedule
and what is being removed from the pit, extra crushed ore
can be stored to
provide feed material when pockets of low concentration
ore is encountered in the pit. The partially
processed ore can later be added to the feedstock for
the ball mills.
When the partially processed
material is re-introduced to the feedstock, the material is passed through a
set of magnets to remove any steel grinding balls that may
have escaped into the ore. This is to prevent damage to the crushing machine.
The ball mills use 16 lb steel shot
to crush the ore into powder. As the mill turns, the
balls fall onto the ore and perform the crushing.
There are a set of these mills running 24/7.
The powdered ore is mixed
with water and a set of chemicals to neutralize acids from the
minerals and float
the copper to the top of these tanks. Scrapers push the concentrate into troughs where it is
washed out into settling ponds for recovery.
At the completion of the
tour, we returned to the Visitor's Center to see some of the displays. On
the exit from the facility, we spotted this awesome
christate sahauro near the road.
Normal sahauros have a circular
growth cap. This
christate has a growth line. Note the light colored
line at the crest of the cactus.
From the mine, we headed
south to Tubac to see the presidio. Most of the
exhibits were dimly lit, but still interesting. This
is a hand
made grinding wheel used for producing flour.
This is the way that the
indians did it: a metate and mano.
Another hand-made grinding wheel, this one
a bit more sophisticated.
To the east of Tubac, the Multi-mirror
telescope was visible on the peak of Mt. Hopkins.
An old wagon at the Tubac museum.
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Photos and Text Copyright Bill Caid 2013,
all rights reserved.
For your enjoyment only, not for commercial use.