Our Planet
Grade 4: Rocks, Minerals, and Erosion (Carter and Josh)
Outcome 2: Present how humans uses of rocks and minerals affect the self, society and the
environment
Lesson #3
Purpose: Students will identify how and where minerals, such as potash, sodium sulphate, salt,
kaolin, uranium, copper, coal, diamond, and gold are extracted in Saskatchewan
Objective: To educate students about where and how the minerals are extracted and where they
are located geographically in the province.
Indicator: Students will exhibit how these minerals are extracted by identifying the tools that are
used to obtain the minerals that are present in Saskatchewan. As well the students will identify
the uses for these minerals and which everyday product they are used in.
Background Information:
Commercial potash is mined through 2 different methods; one being the conventional
underground mining and solution mining techniques. The conventional mining method does have
a depth limitation of 1200 meters or 4325 feet. This is the limitation for the solution that is used
to mine the potash; the solution consists of a salt and slvinite. If the shafts of the conventional
mines go much further, they can force the sedentary rocks to collapse and they are even prone to
flooding the cavern if dug too deeply. Using the solution to mine potash does have some benefits
including a lower up-front capital cost and a shorter ramp-up time. Traditional potash mining is a
more invasive method which causes the soil and other rocks and minerals to be disturbed during
the digging process. However this process has a deeper limitation on how far it can go; which is
about 1500 meters or 5437.5 feet. The solution that is used during this process is a sodium
chloride mixed and heated with sulfuric acid to produce sodium sulfate and sodium sulfate is
eventually mixed in with hydrogen chloride gas. This chemical reaction was discovered in 1772
by Carl Wilhelm Scheele who first used it with limestone and coal. Due to this solution being
water soluble the water can be used again after a few weeks of allowing the water to sit.
Natural sodium sulfate deposits are found in several alkaline lakes with constrained
drainage in the southern part of Saskatchewan. In its natural form its is commonly Glauber’s salt
or mireabilite. Sodium sulphate can also be produced artificially through several chemical
processes. Currently about 50% of sodium sulphate is artificial in the world. Saskatchewan is a
world leader in naturally produced sodium sulphate, currently producing 6% of the total world
supply. During the production stage several techniques may be used to extract the product,
depending on the nature of the deposit. Common practices include dredging the solution or
pumping brine into evaporation ponds, where natural evaporation concentrates the minerals and
crystallization occurs. The sodium sulfate crystals are then extracted from the mixture. In
Saskatchewan there are 2 grades of sodium sulfate, the first is a salt cake grade, which is used for
wood digestion in the pulp and paper industry; the second is a detergent grade product that is
used in detergents, glass, dyes, textiles, tanning, and in the chemical industry.
The first step in the creation of salt extraction is by dissolving chromium into a molten
salt phase at a suitable temperature. This is important due to the achievement of dissolution of
oxides. According to Fajans’ rules this will produce covalent metal chlorides and release chloride
ions which break up the chemical bonds between metal and oxygen atoms, leading to the
formation of corresponding soluble metal chlorides and captures oxygen in dyaluminum trioxide.
The second step is to subject electrolysis in order for the metal to bond to the cathode deposit.
These metals can be selectively electrodeposited from the salt melt. The process is designed and
combined in 2 steps.
Kaolin is also known as China clay; and is composed of hydrated aluminosilicate clay
mineral called kaolinite. Traditional kaolin mining has been done by hydraulic high-pressure jest
of water; which is used to break up impotent portions of kaolinised granite and disperse kaolinite
particles. Both of these components of the granite form into a type of slurry. Another mining
process includes ripping, drilling, and blasting to improve the yields and unkaolinised material is
removed for tipping, although some is processed into aggregate. “Dry” mining has been
introduced in recent years to improve mining efficiency, more selective extraction, and improved
yields. Kaolinised granite is extracted primarily by shovels and trucks to ensure the quality of the
material.
Open pit mining, also known as strip mining, is the most common type of mining when
mining for uranium. This is the removal of superficial soils and uneconomic rock to get to the
ore that is below. This type of mining is only possible when uranium ore is near the surface
(approximately less than 400 feet). Once the ore is exposed there are a series of benches or steps
cut into the ore to make it more accessible and easier to remove. Pumps maybe used to aid in the
cutting process. Underground mining is also used to get higher concentrations of uranium. The
ore is drilled and blasted to create debris which is then transported to the surface then to a mill.
Milling is used for traditional underground and open pit mining, the ore may only have a few
percentage of uranium in them (usually less than .3%). The process includes crushing and
pulverizing the ore into very fine fragments and adding water to create slurry. The slurry is them
mixed with sulfuric acid or alkaline solution to release the uranium from the host rocks. About
95-98% of the uranium can be removed from the rocks. From the acid or the alkaline solution,
uranium oxide or yellow cake is precipitated. This is not the most purest form, and the uranium
is sent to another plant to be enriched.
Copper extraction is a process that converts a series of chemical, physical and
electrochemical processes. In most mining operations copper ore is usually concentrated and
therefore is roasted to convert sulfides to oxides, which smelted the ore to produce matte. Next
the ore undergoes a refining process which starts are the electrolytic process. The sulfur dioxide
gas that is produced during this process is captured and turned into sulfuric acid which aids in the
extraction of the copper ore.
To reach the coal if the deposits are not to deep wells are drilled sideways so trucks can
circulate. If it is to deep down, vertical wells are drilled and a system of elevators and
connections to the surface are installed. There are 2 methods of extracting coal. The First being
the room and pillar method which involves leaving large pillars spaced at regular intervals in
each seem to support the celling. At each level where coal is present the well are linked to a
network of huge galleries that can extend over dozens. The second method is the long-wall
method which involves using a machine called a cutter, that looks like a huge plow. This
machine pushes and cuts through the coal seem. It recovers the ore as it goes along and lets the
celling collapse behind it. This situation is called caving.
The extraction of diamonds involves using an open pit procedure to loosen and hollow
the diamonds rich material for further processing. The vary geometry Kimberlite pipe supports
this method in which layers of the earth are removed and then benched down to a lower level
connected by roads. This pipe narrows with depth which supports open mining processes which
need to also narrow as the mine gets deeper. The second type of diamond extraction is known as
underground mining. Underground mining methods are used when manual open pit methods for
extraction become to costly. The process involves essentially dissolving deeper into the
kimberlite pipe using intricate underground tunneling systems. Tunneling patterns are dug into
the host rock and into the remaining kimberlite deposit of the pipe under the open mine.
In most cases cyanide solutions are used to extract gold, however this is a significant risk
and problem environmentally. This is a risk due to the potential for catastrophic cyanide spills
that could inundate an ecosystem of toxic levels of cyanide. Gold mining operators now take
additional precautions to prevent this problem. They do this by containing the layers of ore and
ground up rock in special leach pads that are lined with a plastic membrane to prevent leaching.
The cyanide is also captured and recycled.
Activity:
1. Plan field trip to any near by area that has one of the type of resources/mineral listed above
2. Students will have permission slips signed by parents
3. Students will fill out sheets on how these resources.minerals are extracted from this
geographical location
4. Students will then present which mineral they chose, how it is extracted, and why they chose
this mineral to teacher in written form
Materials:
Permission slips
Note pads
Pens