Flashcards in C1 3 Extracting Metals Deck (17)
What is a metal ore?
A metal ore contains enough of a metal to make it economic to extract the metal. Ores are mined and might need to be concentrated before the metal is extracted and purified.
How do we calculate whether it's worth extracting a metal?
• How easy it is to extract it from its ore
• How much metal the ore contains
How do we extract metals?
We extract metals by looking at its place in the reactivity series. A more reactive metal will displace a less reactive metal.
We can find many metals such as copper, lead and zinc combined with oxygen. We can use carbon to extract the metal from their oxides as carbon is more reactive than any of these metals.
The removal of oxygen from a compound is called REDUCTION.
Metals more reactive than carbon:
Metals more reactive than carbon cannot be extracted from their ores using carbon so they are extracted using electrolysis.
How do we extract iron from iron ore?
We reduce the iron using carbon in a blast furnace.
However, the iron from the blast furnace has limited uses.
• Contains impurities, this makes it brittle
• This cast iron is used to make man-hole covers and wood burning-stoves
What is an alloy?
An alloy is a mixture of metals and other elements.
How do we make carbon steels?
Carefully controlled quantities of carbon and other elements are added to iron to make alloys of steel with different properties. In the case of carbon steels, we remove most of the carbon from cast iron. These are the cheapest steels to make and can be used in knives, cars and machinery.
Important examples of steels:
• Low carbon steels which are easily shaped
• High carbon steels which are very hard but brittle
• Stainless steels which are resistant to corrosion
Properties and uses of aluminium:
• Low density
• Excellent conductor of electricity
• Doesn't corrode, thin layer of aluminium oxide
• Drinks cans
• Cooking foil
Aluminium is extracted using electrolysis.
Properties and uses of titanium:
• Very strong and very resistant to corrosion
• Doesn't corrode
• Less dense than most metals
• High melting point
• Bodies of high-performance aircraft
• Parts of nuclear reactors
• Replacement hip joints
Titanium can be extracted using carbon but this would make the titanium very brittle. A more reactive metal must be used to extract titanium, but this costs a lot of energy and money as there are many stages in the extraction process.
What are the two main methods to extract copper?
• We react copper with sulphuric acid to make a copper sulphate solution. Then we extract the copper from the solution. The copper can be extracted by reacting the copper sulphide with oxygen to get copper and sulphur dioxide and also by displacement with scrap iron.
• The other process is smelting. We heat copper ore very strongly in a furnace with air to produce crude copper
Extracting copper from low-grade ores:
• Bioleaching- bacteria feed on low-grade ores. By biological and chemical processes, we get a solution of copper ions. Scrap iron and electrolysis is used to get the copper.
• Phytomining- Plants absorb copper ions from low-grade ores. Then the plants are burned and the metals can be extracted from the ash. Sulphuric acid is added and then displacement with scrap iron and electrolysis follows.
Where are the transition metals found?
Transition metals are found in the central block of elements in the periodic table. They have very useful properties.
Problems with extracting metal ores:
• Pollutant gases
• Acid rain
• Habitats destroyed