Other Methods of Extracting Metals Flashcards
How are metals more reactive than carbon extracted?
Electrolysis of molten compounds (liquid, so the ions can move).
How is electrolysis used to extract metals more reactive than carbon?
The metal is melted, and an electric current is passed through it. The metal is discharged at the cathode and the non-metal at the anode.
What is needed in a large amount for electrolysis?
Electricity
Why is electrolysis so expensive?
Because electricity is expensive, and there are also costs associated with melting or dissolving the metal ore so it can conduct electricity.
Why is extracting metals using reduction with copper cheaper than electrolysis?
Carbon is cheap, and also acts as a fuel to provide the heat needed for the reduction reaction to happen.
Which is cheaper to extract: metals higher up or lower down the RS?
Metals lower down the RS are cheaper.
What are scientists doing to prevent shortages of ores in the future?
Looking into new ways of extracting metals from low-grade ores (ores that only contain small amounts of the metal), or from the waste that is currently produced when metals are extracted.
What is bioleaching?
This uses bacteria to separate metals from their ores e.g. copper can be separated from copper sulfide this way.
How does bioleaching work?
The bacteria get energy from the bonds between the atoms in the ore, separating out the metal from the ore in the process. The leachate (the solution produced by the process) contains metal ions, which can be extracted by electrolysis or displacement with a more reactive metal.
What is phytoextraction?
This involves growing plants in soil that contain metal compounds.
How does phytoextraction work?
The plants can’t use or get rid of the metals so they gradually build up in the leaves. The plants can be harvested, dried and burned in a furnace. The ash contains metal compounds from which the metal can be extracted by electrolysis or displacement reactions.
What are the advantages of bioleaching?
- does not need high temperatures.
- scrap iron can be used to displace copper from the leachate; cost-effective.
What are the disadvantages of bioleaching?
- it produces toxic substances, such as sulfuric acid, which damages the environment.
What are the disadvantages of phytoextraction?
- It is slow.
