Major impurity elements in iron ore are silicon, aluminum, phosphorus, and sulfur. Often, a chemical separation is the only method able to remove phosphorus from iron ores. Phosphorus can occur as phosphorus-containing minerals (e.g., apatite) and being finely dispersed in hematite in oolitic ironstones or in goethite in goethitehematite banded iron formation ores. An acid leach can remove phosphate present as discrete minerals and associated with hematite in oolitic ironstones. With goethitic ores, a heating treatment before a caustic or acid leach is necessary to make the phosphorus accessible to chemical separation. The amount of phosphorus removed increases with an increasing heating temperature up to 1300C. Silica, alumina, and sulfur usually are removed along with the phosphorus.
At present, there are about 300 kinds of iron ore in nature. According to their chemical composition, iron ore can be divided into magnetite, hematite, limonite and siderite. But according to the different magnetization coefficient of iron ore, iron ore is divided into strong magnetic and weak magnetic minerals, which provides the basis for the selection of beneficiation technology. Different properties of iron ore, the processing technology is completely different.
Polymetallic magnetite often contain silicate and carbonate minerals, cobalt pyrite, chalcopyrite or apatite, etc. It is suggested to adopt the combined process of weak magnetic separation and flotation, that is, the weak magnetic separation process is used to recover iron first, and then the flotation process is used to recover sulfide or apatite, which is conducive to obtaining a higher concentration index.
Single weak magnetite mainly includes hematite, siderite, limonite and siderite. Because this kind of mineral involves many kinds and has a wide range of particle size, the ore dressing method is also more complicated, which usually adopts the process of gravity separation, flotation, strong magnetic separation or their combination.
Polymetallic weakly magnetic iron ore refers to phosphorus-containing hematite and siderite ore. Most ore beneficiation plant will first use gravity separation, flotation, strong magnetic separation or combined process to recover iron minerals, then use the flotation process to recover phosphorus or sulfide.
Obviously, due to the large variety and complex nature, most iron ore will use multiple beneficiation combined processes to obtain ideal beneficiation indicators. It is recommended that mine owners must do a good job of beneficiation tests, and rationally choose the appropriate iron ore beneficiation process based on the final report results.
At present, there are about 300 kinds of iron-bearing minerals found in nature. According to their chemical composition, iron ore can be divided into magnetite, hematite, limonite and siderite; The specific magnetic susceptibility of the material is different, and iron ore is divided into strong magnetic and weak magnetic minerals, which also provides a basis for the selection. The beneficiation process of iron ore of different nature is also completely different.
Multimetal-containing magnetite gangue minerals often contain silicate and carbonate minerals, cobalt pyrite, chalcopyrite or apatite, etc. It is recommended to use a combined weak magnetic separation-flotation process, that is, use weak magnetic separation The process first recovers iron, and then uses the flotation process to recover sulfide or apatite, which is conducive to obtaining higher beneficiation indexes.
Generally, the combined process of weak magnetic separation and flotation is also divided into two types: weak magnetic separation-flotation and flotation-weak magnetic separation. The difference between these two processes lies in the destination of the conjoined magnetite and sulfide.
This shows that under the same grinding particle size, the combined process of flotation and magnetic separation can obtain iron concentrates with low sulfide content and sulfide concentrates with high recovery rate.
Single weakly magnetic iron ore mainly includes hematite, siderite, limonite, and hematite (spiegelite)-siderite ore. Due to the variety of minerals involved in this kind of minerals and a wide range of particle sizes, the beneficiation method will be more complicated, often using gravity separation, flotation, strong magnetic separation or their combined processes.
The flotation process is mainly used for the separation of fine-grained and particulate weakly magnetic iron ore, including two process flows of positive flotation and reverse flotation. Among them, the positive flotation process is suitable for quartz hematite ore without easy pumice gangue, and the reverse flotation process is suitable for ore with easy flotation gangue.
However, due to the low grade of strong magnetic separation concentrates of most weak magnetic iron ore, and the low processing capacity of the gravity separation process unit, the combined process of strong magnetic separation and gravity separation is often used, that is, the strong magnetic separation process is first used to discard a large amount of waste. Qualified tailings, and then use the gravity separation process to further process the strong magnetic concentrate to improve the grade of the concentrate.
Polymetallic weakly magnetic iron ore refers to phosphorus-containing hematite and siderite ore. Most concentrators will first use gravity separation, flotation, strong magnetic separation or a combined process to recover iron minerals, and then use the flotation process to recover phosphorus or sulfide.
It is not difficult to see that due to the large variety and complex nature, most iron ore will use multiple combined beneficiation processes to obtain ideal beneficiation indicators. It is recommended that mine owners must do a good job of beneficiation tests, and rationally choose the appropriate iron ore beneficiation process based on the final report results.
Prominer has been devoted to mineral processing industry for decades and specializes in mineral upgrading and deep processing. With expertise in the fields of mineral project development, mining, test study, engineering, technological processing.
Investigations were carried out, on a low grade siliceous iron ore sample by magnetic separation, to establish its amenability for physical beneficiation. Mineralogical studies revealed that the sample consists of magnetite, hematite and goethite as major opaque oxide minerals where as silicates as well as carbonates form the gangue minerals in the sample. Processes involving combination of classification, dry magnetic separation and wet magnetic separation were carried out to upgrade the low grade siliceous iron ore sample to make it suitable as a marketable product. The sample was first ground and each closed size sieve fractions were subjected to dry magnetic separation and it was observed that limited upgradation is possible. The ground sample was subjected to different finer sizes and separated by wet low intensity magnetic separator. It was possible to obtain a magnetic concentrate of 67% Fe by recovering 90% of iron values at below 200m size.
Gold in iron ore samples is separated from iron (major matrix cation), antimony and vanadium using anion exchange resin in (0.2 M) HBr, potassium peroxodisulfate and acetone:water:nitric acid media. The exchangeable anion Cl of the ion exchanger Dowex 1X 4 is replaced by Br using (6 M) HBr solution. Certified reference material DGP-M1, spiked ferric magnetic oxide, gold radioactive tracer 198Au and gold standard solutions are used to study the adsorption efficiency and the yield recovery of tetrabromoaurate AuBr4 from the resin. Ten eluents have been tried to elute gold from the column, and it has been found that a 10 ml potassium peroxodisulfate and 240 ml acetone:water:nitric acid [125:5:5] solution fulfills the objective. The set up of the separation procedure allows quantitative adsorption of gold by the resin, while the major matrix cation (Fe) and others (Cd, Ag, Cu, V, Sb, Ti) have been passed through the column with the feeding solution (0.2 M) HBr. The resin selectivity coefficient (K) of separating Au from Fe has been found to be KFeAu6.41011. The eluted Au is treated with K2S2O8 and H2O2 for spectrophotometric determination as rhodamine-B complex at 555.6 nm. The linearity, detection limit, precision, and accuracy of the determination method have been found to be up to 2.0 g g1, 0.018 g g1, 0.009 g g1 and 3%, respectively.
In this chapter we build on what was done in the previous two chapters. After learning that rocks contain minerals, we now explore how the minerals may be extracted so that they may be utilised. Mining plays an important role in the wealth of a country. Learners will therefore learn about the mining industry in South Africa and the impact that mining may have on a country and the globe.
The mining industry is an important industry in South Africa. It involves a number of industries working together. Exploration is followed by excavation, which is followed by crushing and milling to reduce the size of the rocks. This is followed by extraction (removing the valuable minerals from the ore) and finally refining. Each of these processes are discussed in this chapter. The idea is not that learners should know all the terms off by heart, but rather that they grasp the bigger picture. A number of different processes are needed with each one dependent on the efficiency of the step before. The flow diagram exercise towards the end of the chapter is meant to consolidate the chapter content and help learners realise the continuous nature of many industrial processes.
A research project is also included in this chapter. Let the learners choose one industry and research the different aspects of mining covered in this chapter for their chosen industry. The following mining industries can be researched: gold, iron, copper, diamond, phosphate, coal, manganese, chromium or platinum group metals (PGMs). Learners could also choose their own.
The projects need to be handed out in the beginning of the term/chapter. Learners can then present their projects at the end of the chapter, by doing a poster or an oral, or both. For the orals, we suggest you work with the language department so that learners can be assessed there as well. If posters are done, then we suggest you put these up for display for the whole school to see. Learners can stand at their posters during breaks where learners from other grades have the opportunity to come and have a look at their work and ask questions about it.
The project has a two-way purpose, firstly for learners to continue learning about doing research, finding information and presenting the information to others, and secondly, for learners to explore careers in this industry. Part of what they should include in their research is a section on careers in mining.
In the previous two chapters you have learnt about the spheres of the Earth especially the lithosphere. The lithosphere consists of rocks, which contain minerals. Minerals are natural compounds formed through geological processes. A mineral could be a pure element, but more often minerals are made up of many different elements combined. Minerals are useful chemical compounds for making new materials that we can use in our daily lives. In this chapter we are going to look at how to get the minerals out of the rocks and in a form that we can use. This is what the mining industry is all about.
You already know that minerals in rocks cannot be used. Many processes are used to make minerals available for our use. We need to locate the minerals. We must determine whether these concentrations are economically viable to mine. Rocks with large concentrations of minerals, are called ores. Mining depends on finding good quality ore, preferably within a small area.
The next step is to get the rocks which contain the mineral out of the ground. Once the ore is on the surface, the process of getting the mineral you want out of the rock can start. Once the mineral is separated from the rest of the rock, the mineral needs to be cleaned so that it can be used.
This project should be handed out in the beginning of the chapter so that learners have time to work on it. Information for the project is provided in the sections in the chapter, but learners also need to find information on their own. Guiding questions are provided to help learners.
One of the most important steps in mining is to find the minerals. Most minerals are found everywhere in the lithosphere, but in very, very low concentrations, too low to make mining profitable. For mining to be profitable, high quality ore needs to be found in a small area. Mining exploration is the term we use for finding out where the valuable minerals are.
Today technology helps mining geologists and surveyors to find high quality ore without having to do any digging. When the geologists and surveyors are quite sure where the right minerals are, only then do they dig test shafts to confirm what their surveying techniques have suggested.
In all these methods we use the properties of the minerals and our knowledge of the lithosphere to locate them underground, without going underground ourselves. For example, iron is magnetic so instruments measuring the changes in the magnetic field can give us clues as to where pockets of iron could be.
Exploration methods are used to find, and assess the quality of mineral deposits, prior to mining. Generally a number of explorative techniques are used, and the results are then compared to see if a location seems suitable for mining.
Remote sensing is the term used to gain information from a distance. For example, by using radar, sonar and satellite images, we can obtain images of the Earth's surface. These images help us to locate possible mining sites, as well as study existing mining sites for possible expansion.
Rare earth elements are a set of 17 elements on the Periodic Table, including the fifteen lanthanides and scandium and yttrium. Despite their names, they are found in relatively plentiful amounts in the Earth's crust.
Geophysical methods make use of geology and the physical properties of the minerals to detect them underground. For example, diamonds are formed deep in the Earth at very high temperatures, in kimberlite pipes of igneous rock. The kimberlite pipe is a carrot shape. The first kimberlite pipe to be detected was in Kimberley in South Africa. The pipe was mined, eventually creating the Big Hole.
Geochemical methods combine the knowledge of the chemistry of the minerals with the geology of an area to help identify which compounds are present in the ore and how much of it is present. For example, when an ore body is identified, samples are taken to analyse the mineral content of the ore.
When colonialists arrived, they realised the potential mineral wealth of South Africa as gold, and later diamonds, were discovered. They ruthlessly took land from the local people wherever minerals were found, completely ignoring their right to ownership and access.
De Beers purchased the mining rights and closed all access to diamond mining areas. Anyone entering the area would be prosecuted and the sale of so-called 'illegal' diamonds was heavily punished. Other large mining companies have tried to claim the right to the minerals that they mine.
Once the ore body has been identified, the process of getting the ore out of the ground begins. There are two main methods of mining - surface mining and underground mining. In some locations a combination of these methods is used.
Surface mining is exactly what the word says - digging rocks out from the surface, forming a hole or pit. In South Africa, this method is used to mine for iron, copper, chromium, manganese, phosphate and coal.
Let's look at coal as an example. For surface mining, the minerals need to be close to the surface of the Earth. Most of the coal found in South Africa is shallow enough for surface mining. Usually the rocks are present in layers. To expose the coal layer, the layers above it need to be removed. The vegetation and soil, called the topsoil, is removed and kept aside so that it can be re-deposited in the area after mining. If there is a layer of rock above the coal face, called the overburden, this is also removed before the coal can be excavated. Once all the coal has been removed, the overburden and topsoil are replaced to help in restoring the natural vegetation of the area. This is called rehabilitation.
There is a growing emphasis on the need to rehabilitate old mine sites that are no longer in use. If it is too difficult to restore the site to what it was before, then a new type of land use might be decided for that area.
When you mine you are digging into solid rock. The rock needs to be broken up into smaller pieces before it can be removed. Holes are drilled in the rock and explosives, like dynamite, are placed inside the holes to blast the rock into pieces. The pieces are still very large and extremely heavy. The rocks are loaded onto very large haul trucks and removed. Sometimes the rocks (ore) are crushed at the mining site to make them easier to transport.
Mining trucks are enormous. They are up to 6 meters tall, that's higher than most houses. These trucks can carry 300 tons of material and their engines have an output 10-20 times more powerful than a car engine.
Often the minerals are not found close to the surface of the Earth, but deeper down. In these cases underground mining, also called shaft mining, is used. Examples of underground mining in South Africa are mining for diamonds, gold and sometimes the platinum group metals (PGM).
The PGMs are six transition metals usually found together in ore. They are ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) and platinum (Pt). South Africa has the highest known reserves of PGMs in the world.
Sometimes the ore is very deep, which is often the case with diamonds or gold ore. In these cases mine shafts go vertically down and side tunnels make it possible for the miners and equipment to reach the ore. A structure called the headgear is constructed above the shaft and controls the lift system into the vertical shaft. Using the lift, it can take miners up to an hour to reach the bottom of the shaft.
The TauTona Mine in Carletonville, Gauteng is the world's deepest mine. It is 3,9 km deep and has 800 km of tunnels. Working this deep underground is very dangerous. It is very hot, up to 55C. To be able to work there, the air is constantly cooled to about 28 C using air-conditioning vents.
South Africa is a world leader in the gold mining industry. We have been doing gold mining for more than a century and our mines are the deepest in the world. Until 2010 we were the leading producer of gold in the world. Gold is a lustrous, precious metal which has a very high conductivity.
Yes it is, the mines are very deep, of the deepest in the world. Mining deep underground is difficult and dangerous because of the heat and lack of oxygen. Rocks can also collapse because of the pressure.
One of the methods used in underground mining is called room and pillar, and is often used for mining coal. Part of the mine is open to the surface and part of it is underground. The coal face is dug out, but pillars of coal are left behind to keep the tunnels open and support the roof. Machines called continuous miners are used to remove the coal. The coal is loaded onto conveyor belts and taken up to the surface for further crushing.
This section looks at methods to get very large rocks crushed and ground until it is as fine as powder. The first concept that needs to come across here is that minerals are inside rocks and by crushing rocks, the minerals are exposed at the surface of the rock fragment. Only then can chemicals be used to extract the mineral. An analogy with a choc chip biscuit is used to demonstrate this principle. The second concept is that a lot of energy is needed to break rocks. This is a very energy-intensive step in the mining industry, and one of the reasons why mining is so expensive.
This lesson can be introduced by demonstrating the principle explained above to the class. Use choc chip biscuits and crush them with your fingers. This is to get the minerals (choc chips) out. The next step is to separate the choc chips from the crumbs - also a step in the mining process.
Mineral crystals are spread throughout rocks, just like chocolate chips are spread throughout a choc chip biscuit. Sometimes we can see the chocolate chips from the outside, but most of the time the chips are not visible because they are inside the biscuit.
The only way to find out how many choc chips there are is to crush the biscuit. In the same way we can sometimes see mineral crystals from the outside of the rock, but mostly we don't know what minerals there are and and what concentrations are inside the rock. The only way to find out is to break the rock into smaller and smaller pieces.
Once we have crumbled the choc chip biscuit, the chocolate pieces can be separated from the crumbs. In the same way in the mining process the valuable minerals can be separated from the unwanted rock. The unwanted rock is called waste rock.
Let's look at an example. You have learnt in the previous chapter that copper minerals are found in rocks. In South Africa, the Bushveld Igneous Complex is an area which stretches across the North West and Limpopo Provinces. Igneous rock with high mineral content is found here. Here they mine for PGMs, chromium, iron, tin, titanium, vanadium and other minerals using open pit and underground mining. The rocks from the mines are transported by conveyor belts to crushers. Jaw crushers and cone crushers break the huge rocks into smaller rocks.
You can demonstrate this to your class by placing some pieces of broken up biscuit into a plastic container with some marbles or ball bearings. Place the lid on the container and then shake it so that the marbles help to crush and break up the biscuit pieces even further.
This process of reducing the size of the rocks requires a lot of energy. Just image how hard it is to break a rock. How much more energy do you think is needed to crush a rock until it is like sand? This is one of the steps in the mining process that is very expensive because energy is needed to drive the process.
Most minerals are found as compounds in rocks. Only a few minerals are found in their pure form, in other words not bound to any other element. Examples of minerals found in their pure form are gold and diamonds (diamonds consist of the element carbon).
Some rocks are used as is, and do not need to be crushed into powder, or involved in minerals extraction. For example phosphate rock itself can be used as a fertiliser, or it can be used to make phosphoric acid. Sand, or the mineral silicon dioxide (SiO2) is used in the building industry. Coal found in sedimentary rock, is crushed into the appropriate size and used as fuel for electricity generation or the iron-making process.
Before the minerals can be used, they need to be separated from the waste rock. A number of different separation techniques are used. These techniques are based on the properties of the minerals. Different minerals are often found together, for example copper and zinc, gold and silver or the PGMs. A combination of techniques are used to separate the minerals from the waste and then the minerals from each other.
Sorting by hand is not a very effective method to separate out the minerals you want. It can only be used in exceptional situation or by individuals, for example many people mine for alluvial diamonds by hand in rivers in Angola. It is a cheap and easy process to do individually, but it is not feasible on an industrial scale.
Iron is a metal with magnetic properties. Iron ore can be separated from waste rock by using magnetic separation techniques. Conveyor belts carry the ore past strong electromagnets which remove the magnetic pieces (containing the iron) from the non-magnetic waste. How do you think this works? Study the following diagram
The magnetic iron ore will fall into the container on the right as it is attracted to the magnetic roller and travels around the bend of the magnet for a longer period, whereas the non-magnetic waste drops straight down due to gravity, as the magnet turns, and falls into the first container on the left.
One of the first methods for mining gold was that of panning, a technique where ore is mixed with water and forms a suspension. When it is shaken, the dense particles of gold sink to the bottom and could be removed.
Let the learners work in groups of three. The value of the activity is the process of doing it, and not so much the end product. Learners will want to separate every single bead in the process and this is not possible, nor does it happen in the mining industry. Valuable materials do end up as waste.
When choosing beads to separate, ensure that there are a variety of shapes, round and flat, small and large. Most plastic beads will float on water, but metallic ones will sink. The piece of carpet is provided to make the tray rough, but still smooth enough for round beads to roll off, and flat beads to stick. Choose the smallest flattest beads to represent the valuable materials.They will remain on the carpet in the tray more easily.
To separate by density, learners can drop the beads into water - some beads will float and others will sink. To separate by size, learners can use the mesh and let the smaller beads fall through into the cup, with the larger ones staying behind.
As an extension, include some beads which are identical in shape and size, but different colours. At this point, learners will want to hand sort them. Tell learners that hand sorting, although effective and is used by individuals, it is a very time-consuming process and therefore almost never done in the mining industry. Ask learners if they have any other ideas. This is where chemical properties come in. For example, tell learners that one colour bead reacts with an acid and the other does not. Get learners to discuss how they would then separate the beads knowing this. A real world example is that silver reacts with chlorine, but gold does not.
As you have seen in the activity, separating a mixture can be done using different properties, depending on the different properties of the beads. There could be a number of different ways to separate the beads depending on which type of bead you want to select (considered to be the most valuable ones).
Size separation is used frequently in mining to classify ore. For example, when iron ore is exported, it needs to be a certain size to be acceptable to the world market. Coal that is used in power stations also needs to be a certain size so that it can be used to generate electricity effectively.
Flotation makes use of density separation, but in a special way. Chemicals are added to change the surface properties of the valuable minerals so that air bubbles can attach to them. The minerals are mixed with water to make a slurry, almost like a watery mud. Air bubbles are blown through the slurry and the minerals attach to the bubbles. The air bubbles are much less dense than the solution and rise to the top where the minerals can be scraped off easily.
The focus of this activity is to illustrate the principle of flotation and for learners to practice explaining their observations. They will have to apply what they know about density to be able to explain what they see. This activity can also be modified by letting the learners predict what they think will happen before they add the peanuts and raisins to the tap water; and again before they add it to the soda water. The outcome might not be what they expected and the value of the activity is for them to try to explain what they see.
The activity can be done as a classroom demonstration, but it is more effective if done by the learners in pairs. The one learner can use the tap water, and the other the soda water. A suggestions is to buy packets of peanuts and raisins separately, otherwise oil from the peanuts can coat the raisins, causing some of the raisins to rise. The raisins can also be rinsed in acidulated water because they are often dressed with oil before sale for visual enhancement.
Learners should observe that the peanuts and raisins sink to the bottom in the tap water and remain there since they are more dense than water. However, in the soda water, the peanuts and raisins initially sink to the bottom, but then the peanuts start to rise. Small bubbles from the soda water attach to the peanuts' oily surface and cause them to rise to the surface.
The methods mentioned so far are all physical separation methods. Sometimes they are sufficient to separate minerals for use, like coal or iron ore. But more often the element that we are looking for is found as a chemical compound, and so will have to be separated by further chemical reactions. For example, copper in Cu2S or aluminium in Al2O3. What is the name for the force that is holding atoms together in a compound?
Once the compound is removed from the ore, the element we want needs to be separated from the other atoms by chemical means. This process forms part of refining the mineral, as you will see in the next section.
There are many different methods used to concentrate and refine minerals. The choice of methods depends on the composition of the ore. Most of the methods however, make use of chemistry to extract the metal from the compound or remove impurities from the final product. We will discuss the extraction of iron from iron ore as an example.
Iron atoms are found in the compounds FeO, Fe2O3 and Fe3O4 and in rocks like haematite and magnetite. South Africa is the seventh largest producer of iron ore in the world. Iron has been mined in South Africa for thousands of years. South African archaeological sites in Kwa-Zulu Natal and Limpopo provide evidence for this. Evidence of early mining activities was found in archaeological sites dating mining and smelting of iron back to the Iron Age around 770 AD.
The first iron mining techniques used charcoal which was mixed with iron ore in a bloomery. When heating the mixture and blowing air (oxygen) in through bellows, the iron ore is converted to the metal, iron. The chemical reaction between iron oxide and carbon is used here to produce iron metal. The balanced chemical equation for the reaction is:
This extraction method is still used today. The bloomery is replaced with a blast furnace, but the chemistry is still the same. Iron ore, a type of coal called coke (which contains 85% carbon) and lime are added to the top of the blast furnace. Hot air provides the oxygen for the reaction. The temperature of a blast furnace can be up to 1200C. The reaction takes place inside the furnace and molten iron is removed from the bottom. Lime (calcium carbonate or CaCO3) is added to react with the unwanted materials, such as sand (silicon dioxide or SiO2). This produces a waste product called slag. The slag is removed from the bottom and used for building roads. Iron is used to make steel. Hot gases, mainly carbon dioxide, escape at the top of the furnace.
For safety reasons, this experiment should rather be demonstrated. Ensure that you wear safety glasses when performing this experiment. It is quite easy to do, but takes a long time to actually react. The blow pipe needs to redirect the flame into the hollow in the block. Blow through the top of the blue part of the flame. Use a straw to extend the blow pipe so that you can stand a bit further away from the flame. Ensure that a steady stream of heat gets right into the middle of the mixture so that it glows red hot for a while. The video link in the Visit box also shows how the experiment is performed (and the mistakes made). The product can clearly be seen in the video.
In this experiment carbon was used to remove the oxygen from the lead(II) oxide. The carbon and oxygen form carbon dioxide, and the lead is left behind as a metal. This is the same process that is used in iron extraction in the blast furnace, that we discussed above. Coke, which is mainly carbon, removes the oxygens from the iron(III) oxide to form carbon dioxide and leaves behind the iron metal.
The iron that is formed in the blast furnace often contains too much carbon - about 4% where it should contain not more than 2%. Too much carbon makes the iron brittle. To improve the quality of the iron, it needs to be refined by lowering the amount of carbon. This is done by melting the metal and reacting the carbon with pure oxygen to form carbon dioxide gas. In this way the carbon is burned off and the quality of the iron improves. The iron can now be used in the steel-making process. Carbon reacts with oxygen according to the following chemical equation:
Most minerals go through chemical extraction and refining processes to purify them for use in making materials and other chemical products. These are then distributed to where they are needed, for example, coal is distributed to coal power stations and slag is distributed to construction groups for building roads. The mining industry supplies the manufacturing industry and the chemical industry with its raw materials, for example iron is distributed to steel manufacturing industries.
Long before diamonds were discovered in the Kimberley area and the Gold Rush in Pilgrim's Rest and Witwatersrand areas in the late 1800s, minerals have been mined in South Africa. At Mapungubwe in the Limpopo Province evidence of gold and iron mining and smelting was found which dates back to the early 11th century AD. However, it was the large scale mining activities that accelerated the development of the country.
South Africa has a wealth of minerals. We are the world's largest producers of chromium, manganese, platinum, vanadium and andalusite; and the second largest producer of ilmenite, palladium, rutile and zirconium. We are the third largest coal exporter, fifth largest diamond producer and seventh largest iron ore producer. Up to 2010 we were the world's largest gold producer, but our gold production has declined steadily over a number of years. We are currently fifth on the list of gold producers.
The Bushveld Igneous Complex has the world's largest primary source of platinum group metals, indicated on the map in light blue. It is one of the most important mining areas in South Africa due to its abundance of minerals.
Learners need to develop their own symbols for each mineral that is mined, and also colour code the map. The map is blank and so they must find out where each town is located and add it to the map. Let them also fill in the name of the city/town/area in which they live. If there are mining activities in your area which is not indicated on this table, let the learners add it to the list. The list provided is not exhaustive, but it is still fairly long. If you want to make the activity simpler, learners can also chose a certain number of minerals to represent.
There are two types of diamond mining, alluvial (which is found on the coast or in inland rivers which have washed through kimberlite pipes) and kimberlite (which is found inland). What is the link between these two types of diamond mining?
This activity is meant to consolidate the knowledge from this chapter. Each industry will have its own unique flow diagram. The idea is for the learners to realise that it is a continuous system where the one process feeds into the next one to produce a useful end product. This activity links up with the research project and should give learners a good guide for doing and presenting their research projects.
Coal mining: Finding coal seams through exploration in Mpumalanga, Free State and KwaZulu Natal mining for coal using open pit mining removing the coal by blasting and drilling loading onto haul trucks and removing from mine crushing the coal sorting into different sizes distribution to power stations electricity generation
Mining has played a major role in the history of South Africa. It accelerated technological development and created infrastructure in remote areas in South Africa. Many small towns in South Africa started because of mining activity in the area. It also created a demand for roads and railways to be built. Most importantly it created job opportunities for thousands of people. Even today many households are dependent on the mining activities for jobs and an income. Mining is an important part of our economic wealth. We export minerals and ore to many other countries in the world.
Mining activities also have a negative impact on the environment. In many cases the landscape is changed. This applies particularly to surface mines (open pit mines), where large amounts of soil and rock must be removed in order to access the minerals. The shape of the landscape can be changed when large amounts of rocks are dug up from the Earth and stacked on the surface. These are called mine dumps. Open pit mines also create very large unsightly and dangerous holes (pits) in the ground that change the shape of the land.
Air and water pollution can take place if care is not taken in the design and operation of a mine. Dust from open pit mines, as well as harmful gases such as sulphur dioxide and nitrogen dioxide, could be released from mining processes and contribute to air pollution. Mining activities produce carbon dioxide. Trucks and other vehicles give off exhaust gases.
If the mining process is not monitored properly, acid and other chemicals from chemical processing can run into nearby water systems such as rivers. This is poisonous to animals and plants, as well as to humans who may rely on that water for drinking.
An example are pollutants (dangerous chemicals), called tailings, left over from gold mining which pose a threat to the environment and the health of nearby communities. Dangerous waste chemicals can leak into the groundwater and contaminate water supplies if the tailings are not contained properly.
There are no specific answers for this activity. It is an open discussion. We suggest that you discuss the impact of mining in South Africa through this activity. The idea is that learners should come up with all the issues and think about the impact of what we as humans do. The answer to solving the issues is not necessarily to close down all mining activity.
Use the following concept map to summarise what you have learnt in this chapter about mining of mineral resources. What are the three types of mining that we discussed in this chapter? Fill these into the concept map. Remember that you can add in your own notes to these concept maps, for example, you could write more about the environmental impacts of mining.
Phalaborwa is home to one of the largest open pit mines in the world. The original carbonate outcrop was a large hill known as Loolekop. Archaeological findings at Loolekop revealed small scale mining and smelting activities carried out by people who lived there long ago. An early underground mine shaft of 20 meters deep and only 38 centimeters wide were also found. The shafts contained charcoal fragments dating the activities to 1000 - 1200 years ago.
In 1934 the first modern mining started with the extraction of apatite for use as a fertiliser. In 1946 a well known South African geologist Dr. Hans Merensky started investigating Loolekop and found economically viable deposits of apatite in the foskorite rock. In the early 1950s a very large low grade copper sulfide ore body was discovered.
In 1964 the Phalaborwa Mine, an open pit copper mine, commenced its operations. Today the pit is 2 km wide. Loolekop, the large hill, has been completely mined away over the years. A total of 50 different minerals are extracted from the mine. The northern part of the mine is rich in phosphates and the central area, where Loolekop was situated, is rich in copper. Copper with the co-products of silver, gold, phosphate, iron ore, vermiculite, zirconia and uranium are extracted from the rocks.
The open pit facility closed down its operation in 2002 and has now been converted to an underground mine. This extended the lifetime of the mine for another 20 years. The mine employs around 2500 people.
2000 million years ago this area was an active volcano. Today the cone of the volcano is gone and only the pipe remains. The pipe is 19 km2 in area and has an unknown depth, containing minerals like copper, phosphates, zirconium, vermiculite, mica and gold.
This mine was a leader in the field of surface mining technology with the first in-pit primary crushing facility. This meant that ore was crushed by jaw crushers before taken out of the mine. They also used the first trolley-assist system for haul trucks coming out of the pit. Today the mine has secondary crushing facilities, concentrators and a refinery on site.
In 1982 a series of cavities with well-crystallised minerals were discovered, for example calcite crystals up to 15 cm on edge, silky mesolite crystals of up to 2cm long and octahedral magnetite crystals of 1-2 cm on the edge.
All Siyavula textbook content made available on this site is released under the terms of a Creative Commons Attribution License. Embedded videos, simulations and presentations from external sources are not necessarily covered by this license.