Meaning of mining
Mining is the extraction of valuable substances found within the rocks, mud or alluvium.
Minerals in their raw state are called ores.
Mining methods used
The main mining methods used are:
Open-cast method: The minerals are obtained by blasting and quarrying rocks which contain
the mineral. Such rocks are found near the ground surface. It is also called quarry or pit method.
Shaft method: This is used when the minerals lie far below the ground. Deep vertical tunnels
have to be dug to reach it. These tunnels are called shafts. It is also called underground method.
Adit method: This is when the mineral lies deep underneath and side tunnels are used to mine it. Most minerals mined this way are found on the slopes of mountains and can only be reached using side tunnels.
Panning method: Mud is scooped from the river bed in pans and washed until all the impurities are removed and pieces of minerals are then collected.
Examples of such minerals are gold and diamonds
Dredging method: This is when large machines called dredgers are used to scoop the mineral into large mounds. This is used to mine minerals like salt and soda ash.
Drilling method: This is used when minerals like oil and gas lie far below the ground surface. Large metal structures called derrick are used in the drilling. Once they reach the oil, it is pumped out.
Soda ash
Soda ash is the leading mineral export of Kenya.
It is produced from a rock known as trona which is found in Lake Magadi area on the floor of the Rift Valley.
Mining is done using dredging method.
The mineral is scooped from the lake using a dredger and then transported
to the factory where it is crushed to form soda ash.
It is then packed, transported to Mombasa ready for export.
Soda ash is mainly exported to Canada and Japan.
Uses of Soda ash
It is used in the following ways:
a) to manufacture glass
b) to manufacture washing soap or detergents
c) caustic soda is used to soften hard water
d) to make paper
e) to make dyes
f) to make some kinds of medicines.
Salt
Salt is found together with soda ash on Lake Magadi.
However, it is mainly mined along the Kenyan coast from Malindi, Southward to Ngomeni.
Sea water is led to evaporation ponds where it is left exposed to the sun until the salt crystals
form.
These crystals are then scooped by people or using dredgers and heaped into mounds to
dry.
They are then cleaned, ground and packed.
Salt is exported mainly to India and Japan through the port of Mombasa.
Uses of salt
a) it is used in the manufacture of paper and dyes.
b) it is used to preserve food.
c) it is added to food in order to improve its taste.
d) it is used in the manufacture of animal feeds.
Limestone
Limestone is the raw material used to manufacture cement.
Limestone is mainly mined at Athi River near Nairobi and at Bamburi near Mombasa.
The limestone along the Coast extends to Mombasa Island and is mainly formed from remains of corals.
Limestone rocks are dug up in large masses using open cast method and crushed using large mechanical rollers.
The powder is then mixed with chemicals and heated in large boilers before it is dried to form cement. Cement is mainly exported to countries in Eastern Africa and COMESA region.
It is also used locally.
Uses of limestone
a) it is used to manufacture cement which is used in the building industry.
b) limestone is also used to manufacture marble.
Fluorspar
Fluorspar is the second most important mineral in Kenya.
It is mined at Kimwarer in the Kerio Valley of the Rift Valley.
The rocks containing the minerals are dug up using the open cast method and crushed using large grinders.
The crushed rock is then mixed with chemicals to separate fl uorspar from rock wastes.
Fluorspar is then packed ready for export.
The main importers of the fluorspar are the former USSR countries, Germany, India and Japan
Uses of fluorspar
It is used in:
a) making steel and aluminium
b) making tin cans for packing foods
c) the manufacture of sulphuric acid used to make car batteries
e) oil refineries
Diatomite
Diatomite is mined at Kariandusi on the fl oor of the Rift Valley.
This mineral is formed from skeletons of very tiny animals called diatoms.
As a result, diatomite rock has many tiny holes in it.
It is dug up using open cast method, crushed and then packed.
Uses of diatomite
It is used:
a) in the manufacture of chalk
b) in fi ltration plants that purify water
c) to manufacture white-wash that is used to paint walls
d) in hospitals to make plaster used to support fractured bones
e) in making of insulators
f) to make fi re-proofi ng and lining of furnaces in industries because it does not get destroyed easily by fire.
Gemstones
Gemstones are precious stones which are found in rocks.
They are precious mainly because they are durable and valuable.
As a result, they are used to make ornaments.
Gemstones are mined using panning method.
Some are mined through open cast method if they are found near the surface as part of the rock.
Uses of gemstones
Marble
Marble is a hard stone that is beautiful.
It is formed when layers of rock are exposed to high temperatures and pressure.
It is mined through open cast method. The rock is removed from the ground and loaded into trucks. It is then taken to the factory where it is polished.
Sand
Sand is formed from hard rocks through the process of weathering.
These rocks are called granites.
They have large crystals and break up to form grains of sand.
When it rains, these grains are then removed through erosion by running water and deposited into river valleys.
They are harvested by scooping them using spades or using mechanical loaders.
Main sand deposits are found along dry river valleys in Machakos, Makueni and Kitui Districts.
They are also found along Rivers Nyando, Yala and Tana.
These valleys are found in areas with large granite rocks.
Uses of sand
a) it is mixed with cement and used in the building industry.
b) it is used in glass making.
Mining of selected minerals in Africa
Petroleum mining in Nigeria
Nigeria is the leading producer of oil in Africa.
The main mining areas are: the Niger Delta, around Port Harcourt, Oloibiri and along the
Coast of the Atlantic Ocean.
Some deposits are found off the coast in the Atlantic Ocean.
Oil is a mineral that is formed from remnants of dead plants and animals hence known as fossil fuel.
Over a long period of time, the dead plants and animals are covered with layers of rocks whose weight press on them slowly putting them under great heat and pressure.
This in turn, causes tiny droplets of oil to form.
Millions of oil droplets then gradually come together to form oil drops that gradually collect within rocks.
Porous or permeable rocks allow liquids to pass through them while non-porous or impermeable rocks do not.
On either side of the rock containing oil, there is a non-porous rock which does not allow liquids to pass through it.
To get the oil out to the surface, the rocks are drilled using derricks until the oil is reached.
It then comes to the surface through the derrick.
Together with oil, gas and water are also found, and these are also mined.
Most of the oil and natural gas produced are exported under the conditions set by the Oil Producing and Exporting Countries (OPEC) of which Nigeria is a member.
The main oil refi neries are at Port Harcourt and Kaduna.
Uses of petroleum
a) Oil is refi ned to produce different kinds of fuel like petrol, diesel and paraffi n.
b) Oil is used to manufacture lubricants.
c) Tar used for tarmacking roads is produced from oil.
d) Oil is used to make plastic and bitumen products.
e) Oil is used to make synthetic fi bres.
Copper mining in Zambia
Zambia is the leading producer of copper in Africa.
The mining region is towards the north, neighbouring the Democratic Republic of Congo. Copper is mainly mined using shaft method.
The main mining towns are Ndola, Chingola, Mfulira and Kitwe.
Copper is then processed into copper ingots before it is exported.
Copper is exported through the port of Dar es Salaam along the Tazara Railway.
The Tazara railway line was funded by the Chinese government to assist Zambia to export her copper through Tanzania.
This is because Zambia is a landlocked country.
Uses of copper
a) Because of its soft nature, copper is able to bend easily and therefore, it is used for
making ornaments.
b) Because copper is a good conductor of heat, it is used in the manufacture of
electricity wires and transformers.
c) It is used to make utensils like cooking pots.
d) It is used to make copper statues.
e) Copper is used in making coins which are a form of currency.
f) It is mixed with other metals to produce alloys like brass and bronze.
These are used in industries.
Gold mining in South Africa
Gold is a precious mineral which occurs in layers of rocks known as banket.
It is believed that gold in these rocks was formed by rivers carrying eroded rock material
into the sea many millions of years ago.
These materials then got transformed to gold through great heat and pressure.
In South Africa, gold is mainly mined in the region known as The Rand.
The greatest deposits are found around Johannesburg.
It is mainly mined using shaft method although alluvial gold is found along river beds and can be obtained by washing river mud using the panning method.
When the rock reaches the surface, it is crushed and gold is separated from rock material through a chemical process.
Gold is then smelted to remove any remaining impurities.
Uses of gold
a) Gold is the most precious mineral ever to be discovered, and because of this, it
fetches very high prices on the international market.
b) It is also used as an international currency.
c) It is used to make ornaments.
Contribution of mining to the economy of each mining country
a) Export of minerals earns foreign exchange.
b) Money earned from the exports if well used can improve the living standards of
the people.
c) Mining leads to the development of towns.
d) It provides materials for other industries.
e) It creates jobs.
f) Mining activities encourage agriculture because there is need of food for workers.
g) The government earns revenue through taxes paid and sale of licenses.
Problems associated with mining in Africa
a) Mining activities need a lot of money which many African countries do not
have.
b) Sometimes mines collapse killing miners.
c) Many minerals from Africa, except gold, diamonds and oil do not fetch a high price
on the world market.
d) Many mining activities are done by foreign companies which take most of the profi ts.
e) Open craters sometimes cause accidents.
f) Mining leads to development of other related industries.
g) Promotes the development of social amenities in the mining towns.
Effects of mining to the environment
a) Mining activities cause air and water pollution.
b) After processing mineral ores, mounds of rock wastes are dumped on the ground,
spoiling the beauty of the environment.
c) Mining leaves behind open craters that spoil the beauty of the environment.
d) Open cast mining causes a lot of noise pollution which affects people living near
the mines.
e) Some quarries fi ll with water and become breeding grounds for mosquitoes.
f) Before any mine is set up, large areas of forest and other vegetation are cleared.
This may lead to desertifi cation.
