MENTION THE VARIOUS GEOGRAPHIC SPOTS OF METAL DEPOSITS?


The map below shows where some of the most important metals are mined.



IRON There are vast deposits of iron ore around the world. The largest deposit is at Kursk, about 500 km south of Moscow in the former Soviet Union. It is estimated that this area has over 10 billion tonnes of iron ore reserves. Other large deposits are in the southern Urals, North America and Australia. The two ores which contain the most iron are black ‘magnetite’ and red ‘hematite’.



ALUMINIUM The main aluminium ore is ‘bauxite’. It is much more scarce than iron ore and is also more expensive to produce into metal. Cape York, Northern Queensland, Australia has the world’s largest bauxite deposits. Here, 25 per cent of the world’s aluminium is produced, although Indonesia, Jamaica, Brazil and Western Australia also have huge deposits.



COPPER The ‘copper-belt’ of Zambia-Democratic Republic of Congo is one of the largest copper ore deposits in the world.



Elements in the Earth’s crust



Six metals — aluminium, iron, calcium, sodium, potassium and magnesium make up just 24 per cent of the Earth’s crust. Oxygen and silicon make up another 75 per cent, leaving only one per cent for all the other naturally-occurring elements in the Earth’s crust.





































Picture Credit : Google




































WHAT ARE THE ENVIRONMENT CONCERNS OF METALS?


Metals are extremely useful for our daily activities. But the process of finding, extracting and refining metals can damage our environment. Furthermore, we live in an age where radioactive metals are widely used. These highly reactive metals combine to give off powerful energy which can be used in industry and for military weapons. The radioactive emissions from these devices can have a devastating effect on our environment.



Wildlife



When metals are extracted from the ground the vegetation and soil covering the deposit are removed. Sometimes a new road is needed to access the site. These actions can cause erosion, destroy wildlife habitats and impair the natural beauty of an area. Aquatic life in nearby water sources may also be affected.



Pollution



By their nature, metals are strong and resistant to corrosion. Scrap metal is therefore a serious waste product. It spoils the natural beauty of a landscape. Abandoned cars are a particular problem. Mercury used in car head lamps and antilock braking systems can release toxic chemicals into the environment, causing harm to human health and wildlife.



Waste metal



Metal is a valuable material and consequently waste metal is rarely deposited in landfill waste sites. Instead this strong and hard-wearing material is reused or recycled again and again. Scrap metal companies have licences that allow them to deposit and store metal in a safe manner. This helps to prevent toxic chemicals from being released into the environment.



Recycling



Recycling metal saves natural resources, uses less energy than the mining process and reduces air and water pollution. Scrap metal recycling is well developed throughout the world. Scrap metal is commonly mixed with ‘new’ metal to make new products, such as in the steel-making process



What you can do



Many metal items in your home can be reused or recycled. Recycling aluminium tins and cans is one way that you can help to save energy and conserve the world’s natural resources. Old computers and other electrical equipment can also be reused. Why don’t you ask about recycling schemes in your local area?




































Picture Credit : Google



































WHICH ARE CALLED MODERN METALS?


Scientists continue to discover and develop new metals and alloys which can be used in modern technology and industry. The aviation industry in particular, requires metals that are strong and light. For this reason aluminium alloys are often used to make planes. Titanium is used for high speed aircraft that get very hot and some engine parts are made of steel. As fossil fuels run out, the search also goes on for lightweight metals that can be used to convert chemical energy into electrical energy. These metals could be used to make batteries or fuel cells.



Each metal has its own particular properties. So we may choose different metals to do different jobs. When an electric current passes through tungsten wire it glows but does not melt. This makes it ideal for light bulbs. Forks need to be cheap and strong but must not rust. Stainless steel is a suitable choice. See if you can find out why other metals in these pictures are being used.



A lot of metals and metal alloys have been used to make this coach. The body and chassis are mostly made of metal. The battery contains lead plates; all the wiring is copper; the trim is probably chromium or stainless steel; and the door handles are plated zinc alloy. The wheels may be an alloy of magnesium and aluminium and the light bulbs contain tungsten. A catalytic converter, made from rare metals such as palladium, rhodium and platinum, can be placed in the exhaust system to make the engine fumes cleaner. The converter changes polluting gases, such as carbon monoxide, into cleaner substances.





































Picture Credit : Google




































HOW DO THEY METALS ARE BEING CUT AND JOINED?


Some metal objects can be made from one piece of metal. But others have to be made from a number of different pieces. Metal can be cut with an ‘oxyacetylene torch’. This torch uses the gases oxygen and acetylene which burn together at over 3,000° C. This is hot enough to cut through steel by melting it. Lasers are used to concentrate heat and cut through metal very quickly and accurately.



When a metal is heated it can melt. If two almost-melted edges are placed together and allowed to cool, they will form a strong joint called a weld. Riveting and soldering are other permanent ways to join metals.



Welding



A gas torch can be used to melt the edges of two pieces of metal. They then fuse together with some added molten metal. When the metals cool they form a strong joint.



Riveting



The rivet is pushed through holes in overlapping plates so that the pointed end pokes through. This end is hammered flat to hold the pieces tightly together.



Soldering



Soldering is used like glue to join delicate pieces of metal. Solder is an alloy of tin, lead and antimony. Molten solder is applied to the joint where it fuses the pieces together.



































Picture Credit : Google


































HOW DO WE MOULD THE METAL INTO DIFFERENT SHAPES?


Look at the metal objects around you — perhaps you can see a bicycle wheel, a key or a spoon. Each of these objects has its own special shape. Many metals may appear so hard and strong that it seems impossible to change their form. Powerful machinery, made of even stronger metals, can shape and bend many metals.



When metals are purified they are made into blocks or slabs. The metal can then be shaped to make the many different objects we use. Some metals, such as copper and gold, can be shaped while they are cold. But others, like steel, are more easily shaped when they are red hot.



Forging



A red hot ‘ingot’ can be shaped by pounding with a metal ‘ram’. Usually the bed of the forge and the ram hold two halves of a mould called a ‘die’.



Casting



Hot liquid metal is poured into a mould where it solidifies. The mould is broken open and the metal ‘casting’ is released.



Rolling



A red hot slab may be passed backwards and forwards between rollers. The slab gradually gets longer and thinner — like dough under a rolling pin.



Extrusion



Soft lead alloys can be made into thin-walled tubes by ‘extrusion’. When the ram hits the metal, the metal is forced up the sides, forming a tube.



Drawing



A tempered metal rod is pulled through a die. This process is repeated through narrower dies until the rod becomes a long thin wire.



Machining



Metal which has been shaped may need to be trimmed in a ‘lathe’. The rotating metal is held firmly while a sharp, hard blade trims it.


































Picture Credit : Google