Obtaining and Using metals

Question 1

What are the environmental and economic advantages of recycling metal?

Answer 1

● Recycling​ ​is​ ​important​ ​to​ ​achieve​ ​sustainable​ ​development
○ Requires​ ​less​ ​energy​ ​to​ ​melt​ ​and​ ​remould​ ​metals​ ​than​ ​it​ ​does​ ​to​ ​extract
new​ ​metals​ ​from​ ​their​ ​ores
○ Mining​ ​ores​ ​is​ ​bad​ ​for​ ​the​ ​environment​ ​as​ ​large​ ​quarries​ ​are​ ​created,
which​ ​produce​ ​noise​ ​pollution​ ​and​ ​dust
○ Also,​ ​recycling​ ​allows​ ​for​ ​waste​ ​metals​ ​to​ ​be​ ​reused,​ ​saving​ ​money,
helping​ ​the​ ​environment​ ​and​ ​the​ ​supply​ ​of​ ​valuable​ ​raw​ ​materials (meaning​ ​metal​ ​ores​ ​will​ ​last​ ​longer)

Question 2

State what a Life Cycle assessment is

Answer 2

A Life Cycle Assessment measures the environmental impact of a product throughout its life. This is from obtaining the raw materials to disposal.

Question 3

What is the first stage of an LCA and what should be considered in it?

Answer 3

The first stage is extraction and processing of raw materials.

We should consider the effects of extraction.
e.g. The extraction of crude oil can cause oil spills that cause environmental damage.
The mining of metal ores can damage the environment by destroying habitats

We should consider if the raw materials are renewable or finite. e.g. plastic bags made of crude oil which is finite

Question 4

What is the second stage of an LCA and what should be considered in it?

Answer 4

The second stage is manufacture of the product and packaging.

Manufacturing may produce a large amount of electricity to run a machine or release pollutants.

Question 5

What is the third stage of an LCA and what should be considered in it?

Answer 5

Use and maintenance of the product.
When using a product, energy and water may be utilised e.g. washing machines use large amounts of energy and water.

Should consider whether a product is single or multi-use. e.g. plastic bottles are single-use because the micro plastics may get into the water supply.

Question 6

What is the fourth stage of an LCA and what should be considered in it?

Answer 6

Disposal of the product.
Possible disposal methods include recycling, incineration and landfill.
Incineration can be useful as it generates electricity but also produces carbon dioxide (a pollutant)

Question 7

What are the disadvantages of LCAs?

Answer 7

Some companies may use part of a LCA or a simplified LCA to show their product in a favourable manner.
As well, some factors are subjective or based on personal judgement like the effects of pollutants.

Question 8

What are the main things which should be considered at each stage of an LCA?

Answer 8

-The energy used
-The water used
-Pollutants released
-Transportation

Question 9

Why can’t aluminium be extracted using carbon like some other metals?

Answer 9

Aluminium is above carbon in the reactivity series, so it is too reactive to be reduced by carbon alone.

Question 10

Why are carbon electrodes used in the electrolysis of aluminium oxide?

Answer 10

Carbon electrodes are used because they are good conductors of electricity and can withstand the high temperatures required for the process.

Question 11

Why do carbon electrodes need to be replaced during the electrolysis of aluminium oxide?

Answer 11

They react with oxygen to form carbon dioxide, which wears them away.

Question 12

Why is electrolysis of aluminium oxide conducted using cryolite?

Answer 12

Cryolite acts as a solvent and lowers the melting point, reducing energy costs.

Question 13

Why is the electrolysis of aluminium considered an expensive process?

Answer 13

Electrolysis of aluminium is expensive due to the high energy costs associated with melting aluminium oxide and maintaining the electrical current required for the process.