- Created by: j_eshun
- Created on: 22-04-15 18:25
Methods of extracting metals
In the Earth's crust are metals and also metal cmpunds such as gold, iron oxide etc. However, when they are found in the crust they usually are mixed with other substances. To be able to use these and make them useful we nees o extract the metal/metal compound.
Metal ore- a rock with metal inside of it , with a high enough concentration that it becomes economical to extract the metal/metal compound.
Ores are mined out and sometimes they need to be concentrated before the metal is extracted and purifyed.
Reactive metals are extracted by electrolysis and less reactive ines by a reaction with carbon or carbon monoxide
electrolysis chemical decomposition, by passinganf eletric current through a liquid/solution containing ions that are broken down in =to simpller substances
The transition metals are the metals in the centre of the periodic table, between group 2 and 3.
-they are all good conductors of heat and electricity
-they are all metals
-they can all be hammered and bent into a shape.
The three main and most noteworthy elements are:
...they all produce a magnetic field
Transition Metals- Iron
Iron is extracted from its ore through a blast furnace. Iron ores contain iron oxide, the oxygen has to be extrated so that we ar left with iron
Blasting Furnace- smeelting furnce which has a blast of hot compressed air which comes from below.
iron oxide + carbon → iron + carbon dioxide
the ironoxide has been reduced to iron and the carbon has oxidised to become carbon dioxide.
Its so hot in the furnace that carbon monoxide can also decompose and reduce iron oxide
iron oxide + carbon monoxide → iron + carbon dioxide
Transition Metals- Copper & The Future of Copper
Copper is a good conductor of electricity, as it is soft and bendy, making it good for wiring. Copper is a good conductor of heat. It iks unreactive to water, so it is good for plumbing and pipes.
Some of the copper ores are very copper-rich. this ,eams it has a high concentration of copper compunds that can be extracted from the ore. The copper can be extracted through smelting. It can then be purified by electrolysis.
During electrolysis the positive ions molve towards the negative ones, these are deposited as copper metalS.
We are running out of colpper-rich ores, so research to finding new wayhs to extract copper from low grade ores are ujnderway, as scientists are trying to come up with ways that done harm the enviroment, and mining involves huge open mines that produce a lot of waste rock.
Phytomining- Some plants can absorb the copper compounds in the soil. The plants concentrate the compounds. The plants are then burnt because the ash contains copper compounds.
Bioleaching- some bacteria absorb the compounds, they then produce solutions called leachates which contain the compounds.
Transition Metals: Aluminium and Titanium
Aluminium and Titanium have a low density. They hve thin layers of their oxides on their surface whuich prevents corrosion by stopping air and water getting in to the metal.
- fighter aircraft
Extracting metals and making alloys- Aluminium and
-artificial hip joints
-nuclear power station pipes
Existing metods of extracting the two metals or their compounds
-have many stages
-need large amounts of energy
They are largely recycled because less energy is needed to recycle instead of to extract. It also preserves less resources, thus being better for the environment.
Alloy- a mixture of two or more elements, with at least one being a metal. They contain atoms of different size makng them harder and stronger as its difficult for the layers of atolms to slide over one another.
Examples of Alloys:
-Brass- (used in electrical fittings) 70% copper and 30% zinc
-18 carat gold (used in jewellery) 75% gold and 25% copper and other metals
-Duralumin (used in aircraft) 96% aluminium and 4% copper and other metals
Iron and Steel
Pure iron is soft and easily shaped, this is due to the regular layers of atomsw it has. So the layers slip and slide over one anothe.
Iron from the blast furnace has carbon and a few other impurities, making it brittle. So usually some of the carbon is taken out to produce Steel.
Carbon iks removedd from the iron when oxygen is blown into it. The oxygen reacts with the carbon producing carbon dioxide and carbon monoxide. Vanadium and chromium are added to make alloys. There are many tyoes dependng on the element is was mixed with.