Questions for the Case Study Copper Mining
Make a flow chart that illustrates the different steps in copper mining and
purification, noting the differences between sulfidic and oxidic ore
processing.
1. Copper-containing minerals are listed below in Table 1.
(a)
For each mineral assign oxidation numbers to all the elements
present.
(b)
In what oxidation states does copper tend to exist? What
other elements are usually parts of copper minerals?
(c)
For each mineral listed calculate the % Cu by mass.
(d)
Which minerals are richest in Cu? Choose the 5 minerals
containing the most copper by mass.
(e)
Of the five minerals with the most copper, use the specific
gravity to find which mineral has the most copper in the
smallest volume of rock.
In preparation for the lab answer the following questions:
Qualitative Identification of Metals (Method C)
2. List the metal ions which readily precipitate in the presence of chloride
ion.
3. Why is it that Ag+ can be detected directly in the leachate by addition
of chloride ion but Pb2+ can’t?
4. Why is PbCO3 soluble in acid while PbSO4 is not?
5. Write a net ionic reaction for each step in the qualitative tests for Ag+,
Pb2+, Fe2+, Fe3+ and Zn2+ .
6. Divide the minerals listed in Table 2 into two categories: those that are
amenable to refining via hydrometallurgical techniques and those that
are not. For each of the minerals that can be refined with
hydrometallurgy, calculate the amount of copper, in grams, that could
be recovered from 1 ton of the pure mineral.
7. Calculate also the volume of oxygen gas at 1 atmosphere pressure
necessary to convert 1 ton of ore containing 1.25% Cu in the form of
chalococite to native copper.
8. The Nifty Copper Operation run by WMC in their 1996 - 1997 season
milled 0.705 million tons of ore using 313 Megajoules per ton of ore.
Use the data you calculated in Session 2 about the amount of copper
present in ores to determine the amount of energy required per
kilogram of copper produced.
9. Using table data determine the costs per kg Cu associated with
hydrometallurgy.
10.
The chemical reactions associated with leaching are described in
words below. Write the net ionic chemical reaction that is described.
(a)
Non-sulfide copper ores are easily leached by sulfuric acid.
For example, write a net ionic reaction for the leaching of
Tenorite by H2SO4.
(b)
An ore body contains many different minerals. When H2SO4
acts on heaped ore that contains FeS2 (pyrite) the sulfur is
oxidized by oxygen from the air.
11.
List the environmental and economic considerations in
hydrometallurgical processing.