Download Smelting Copper

HS CHEMISTRY Smelting Copper
Contributed by Jessica Favela-Casillas
BACKGROUND
Copper is smelted starting from a copper ore, usually called Chalcopyrite, CuFeS 2. It is combined
with limestone and sand to produce Iron Oxide, FeO, and leaves Copper Sulfide. The Copper
Sulfide is then melted and burned to release another pollutant, Sulfur Dioxide, a pollutant that
is linked to long-term health problems for those exposed to it. For every ton of copper
produced at a refinery such as Asarco, 1.5 tons of slag and two tons of sulfur dioxide are
produced and released into the atmosphere.
Students explore the separation of copper from a compound through chemical means in a
manner similar to that of a refinery or smelter and discover the impact of pollutants
generated from the smelting and extracting.
Introduction: Students examine the chart below and discuss implications for the waste products
in the environment.
Process materials inputs and pollution outputs for copper smelting and refining
Process
Material input
Air emissions
Process wastes Other wastes
Copper
Copper ore,
Flotation
Tailings containing
concentration
water, chemical
wastewaters
waste minerals
reagents,
such as limestone
thickeners
and quartz
Copper leaching Copper
Uncontrolled
Heap leach waste
concentrate,
leachate
sulfuric acid
Copper smelting Copper
Sulfur dioxide,
Acid plant blow
concentrate,
particulate
down
siliceous flux
matter
slurry/sludge, slag
containing
containing iron
arsenic,
sulfides, silica
antimony,
cadmium,
lead, mercury
and zinc
Copper
Copper matte,
Sulfur dioxide,
Acid plant blow
conversion
scrap copper,
particulate
down
siliceous flux
matter
slurry/sludge, slag
containing
containing iron
arsenic,
sulfides, silica
antimony,
cadmium,
lead, mercury
and zinc
Electrolytic
copper refining
Blister copper,
sulfuric acid
Slimes containing
impurities such as
gold, silver,
antimony, arsenic,
bismuth, iron,
lead, nickel,
selenium, sulphur
and zinc
Discuss: Asarco smelted copper and other compounds for almost 100 years. How does the
information in the chart make you feel about being so close to the Asarco smelter? What do
you think was done with the waste? How do you use copper? Now that the smelter is closed,
where is copper smelted today?
EXPLAIN
Asarco has smelted copper, and like many refineries, there is chemical waste left over that has
harmed people and the environment. The following chemical reactions demonstrate the
pollutants produced by refineries.
Compare the reactants to the products. Identify each part of the equation identifying the metal
being smelted, the compound it is being separated from and the waste.
1.
2.
3.
4.
5.
6.
7.
8.
9.
2 CuFeS2 + 3 O2 → 2 FeO + 2 CuS + 2 SO2
2 CuS + 3 O2 → 2 CuO + 2 SO2
2 FeS(l) + 3 O2 + 2 SiO2 (l) →2 FeSiO3(l) + 2 SO2(g)
2 FeS + 3 O2 → 2 FeO + 2 SO2
CuCO3 ------> CuO + CO2
2 Zns + 3 O2  2 ZnO + 2 SO2
2 SO2 + O2  2 SO3
ZnO + CO Zn (vapor) + CO2
List all the waste
EXPLORE
Purpose: You will perform a chemical experiment demonstrating a chemical reaction that
separates a metal from a compound and determine what was is left over.
Materials: Copper (II) chloride, one piece of aluminum foil (10 cm x 10 cm), 250 mL beaker,
stirring rod, thermometer, distilled water, stopwatch, safety goggles, balance
Procedure
1. Measure 3 grams of copper (II) chloride and make observations about its physical
appearance.
2. Pour 100 mL of distilled water into the copper (II) chloride. Stir with the stirring rod.
3. Make an observation about the copper chloride dissolved in water.
4. Take the mass of your aluminum.
Solid Copper (II) Chloride
Copper (II) chloride
dissolved in water
Solid Aluminum
5. Lightly crumble the aluminum foil and place in the beaker. You can push it under the
surface with the stirring rod.
6. Make as many observations as you can about the reaction in the beaker.
Observation of reaction:
What do you see happening? Color? What is Dissolving?
What do you feel?
Measuring Copper
1. With tongs, extract the chunk of “left over” aluminum. Allow all liquid to fall back into
beaker. Take the mass of the aluminum.
2. Shape the Filter paper into a cone and filter the contents into an empty beaker scrape
the Copper, Cu, off. Take its mass. Record.
Mass of copper (II) chloride which
reacted
Mass of aluminum metal (initial)
Mass of leftover aluminum wire (final)
Mass of aluminum metal which reacted
Mass of copper actually produced
Initial – final
Aluminum
In this lab, copper (II) chloride reacts with aluminum metal in a single displacement reaction.
Use the Data collected above. ALWAYS DO A “NEED” AND “GIVEN” TO SOLVE THESE
PROBLEMS.
1. Write a balanced chemical equation for the single replacement reaction of copper (II)
chloride with aluminum metal to produce copper metal and aluminum chloride.
1.a. Calculate the number of moles of copper (II) chloride used.
1. b. Calculate the number of moles of aluminum metal used.
2. Determine the limiting reactant.
3. What is the excess reactant? There are only two reactants:
4. How much excess reactant (in grams) is left over once the reaction is completed?
Analysis:
Looking at the access reactants, is excess reactant a larger quantity than the copper produced?
What happened to the Aluminum and the Chloride that reacted?
Write the chemical equation:
What element was desired to be extracted?
What waste was left over?
In a smelter, if copper was extracted using these chemical means, what happens to the left over
chemicals?
What can you do to ensure that these are disposed properly?
What tests can you conduct to insure that the land is safe for others to settle on a smelter site?
Share the information you have learned about copper smelting with someone younger than you.
What do they think about it? What can we do about it?