Intro to Mining Resources

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Intro to Mining Resources

• Key Concepts in this Unit
• Obtaining metal resources from the earth is a
  very involved process.
• Many things need to be taken into consideration
  when deciding whether or not to open a mine.

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The products that we use everyday come from the
earth
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We all know that products dont just get dug out
of the ground
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But many people dont realize that even the raw
materials we use to make products must be
processed before they are usable when they are
dug out of the ground.
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CASE STUDY

• What does it take to get the Aluminum that makes
  up this can?

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About Aluminum

• Third most abundant element in earths crust
  (after oxygen and silicon)
• Has a low density for a metal and resists
  corrosion.
• Based upon this chemical structure, will it be
  found in nature as pure Aluminum?
• NO

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Aluminum is present in a high quantity in the
rock of this area...
So how do you get the resource?
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Either dig a tunnel underground

• But this can
• be dangerous (collapse potential, build up of
  harmful gases, high exposure to dust)
• be difficult to efficiently get the resource to
  the surface

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OR strip away the surface (open pit mine)

• But this can cause a significant disruption of
  the ecosystem of the area.

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Once the vegetation and soil is removed, you need
to loosen up the rock

• HOW?

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Once you have loosened the rock by blasting, you
can dig out the rock that contains the aluminum.
Heres what it looks like

• This is the rock Bauxite (a.k.a. aluminum ore)
• It contains the mineral Gibbsite (AlOH3).
• It also contains other minerals that are not
  useful.

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Removing the Aluminum from the Bauxite requires
many steps

• Pulverization--
• Rock is crushed into pieces of about 3cm
  diameter.
• WHY?

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2) Chemical Separation

• Sodium Hydroxide (NaOH) is added in order to
  dissolve the Aluminum into a liquid as Alumina.

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3) Density Separation

• The sodium hydroxide solution is stirred around
  in the giant vat
• Heavier rock fragments settle
• to the bottom.
• Then the solution is filtered,
• which separates the waste material from the
  liquid that contains the aluminum.

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The waste material is coated with Sodium
Hydroxide. What is NaOH?

• Since NaOH is a strong base
• The waste material must be neutralized (by adding
  acid) before it can be returned back to the
  environment.

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4) Electrolysis is used to separate the Oxygen
from the Aluminum in the liquid Alumina (Al2O3)

• Carbon electrodes attract the Oxygen, thus
  forming Carbon Dioxide freeing up the Aluminum.
• This process consumes about 16,000 KWH of
  electricity for every ton of Aluminum produced.
• For reference, the average home in CT uses 700
  KWH of electricity in a month.

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So is it worth it to recycle Aluminum cans?

• Recycling aluminum
• SAVES 95 of the energy needed to make the can
• Reduces impact on ecosystems since fewer mines
  need to be produced

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Hungary, October 2010
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• When the tailings dam burst, a wave up to 7 feet
  high rushed through the town carrying a very
  basic solution of toxic metals into the nearby
  town.
• 10 deaths, 120 injuries from this event.

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Is this how all metals are produced?

• While not all metal resources are processed in
  the same way, all metals will require several
  steps to extract and purify the resource.