Metal Extraction Flashcards
What is a metal ore?
A rock containing enough metal to make it worthwhile extracting the metal from it
In many cases the ore of a metal is an ….
the ore of aluminium is …
oxide
bauxite - aluminium oxide
How are metals extracted from their ores?
Using a chemical reaction
Why do the economics of metal from ore extraction change with time? (2)
If market price of the metal drops it might not be worth extracting it, or it might be worth increasing extraction if price increases
As tech improves it might become possible to extract metals previously unextractable so now might be worth money
What are the two ways metals are extracted from their ores?
Reduction
Electrolysis
What do some ores have to do before the metal is extracted?
Be concentrated to get rid of the unwanted rocky material
What can electrolysis also be used for besides extracting metals?
Purifying them
How are some metals extracted through reduction?
The oxygen is removed by reacting the metal oxide ore with carbon to leave the metal and carbon dioxide
What determines whether the metal can be extracted with carbon?
Its place on the reactivity series
If the metal is less reactive than carbon it will be….
If it is more reactive it will be …
extracted using reduction with carbon
extracted by electrolysis
What is the bad thing about electrolysis for a company?
It’s expensive
How do metals more reactive than carbon have to be extracted?
Example…
by electrolysis of its molten compound.
aluminium
Why is electrolysis more expensive than reduction with carbon?
Example:
It uses a lot of energy
Very high temperatures are required to melt aluminium oxide which is very expensive
How is copper extracted from its ore? describe…
Reduction … easily, in a furnace which is heated which is called smelting
Why is impure copper unuseful?
What’s used to purify it?
It contains impurities which stops it conducting electricity well which is bad as it’s used to make electrical wiring
Electrolysis
What does electrolysis mean?
The breaking down of a substance by splitting it with electricity
What does electrolysis require?
A liquid to conduct the electricity called the electrolyte
What does the electrolyte have and what do these do?
Free ions that conduct electricity
What happens to electrons at the positive electrode? then at the negative electrode?
So what happens to the ions?
They are taken by the +ve and given away by the -ve
They gain or lose electrons and so become atoms or molecules and are released
How do you use electrolysis to get copper? (describe)
- Electrons and the +ve electrode
- -ve electrode
- Impurities
- What is the electrolyte?
Electrons are taken of copper atoms at the positive electrode causing them to go into the solution as Cu2+ ions
Cu2+ ions near the -ve electrode gain electrons and turn back into copper atoms
The impurities are dropped under the +ve electrode as sludge whilst pure copper atoms bond to the -ve electrode.
Copper II sulphate solution containing Cu2+ ions
What can also be used to extract copper?
A displacement reaction
What will happen if you put a reactive metal in a solution of a dissolved metal compound?
What can be sued to displace copper from copper sulphate solution?
The reactive metal will displace the less reactive metal
Iron
Why is it important to recycle copper? (2)
The amount of copper rich ores is limited
Demand is growing and this may lead to shortages in the future
What are the two ways scientists have come up with to extract copper from low grade ores or the ground?
What is the advantage and disadvantage to these techniques?
Phytomining
Bioleaching
They have a smaller impact on the environment than traditional methods but they are slow
What is phytomining? (4 stages)
Growing plant in soil that contains copper
The plants can’t use or get rid of the copper so it eventually builds up in their leaves
The plants are harvested dried and burned in a furnace
The copper can be collected from the ash left in the furnace
What is bioleaching? (3 stages)
Bacteria is used to separate copper from copper sulphide
The bacteria get energy from the bond between copper and sulphur separating, separating the copper from the ore in the process
The leachate, the solution produced contains copper, this can be extracted through filtering.
Why is mining for metal ores good? (4)
Useful products can be made
It provides local people with jobs
This brings money into the area
So facilities such as hospitals and infrastructure can be improved
Why is mining for metal ores bad? (4)
It causes noise
Scarring of the landscape
Loss of habitats
Deep mine shafts can be dangerous for a long time after the mine is abandoned
Why is mining for metals bad?
It uses a lot of energy which requires the burning of fossil fuels
Why is burning fossil fuels for mining bad? (4)
They are running out so it’s important to conserve them
It contributes to acid rain
Global dimming
and Climate change
Why is recycling metals good in relation to fossil fuels?
and energy?
and for the earth’s resources?
and for pollution?
It uses only a small fraction of the energy required to mine ores and extract new metal
it’s cheaper as it uses less
there is a finite amount of metal ores so it conserves these
It cuts down the amount of rubbish sent to landfills that take up space and pollute the environment.
