Tuesday, April 18, 2023

Phytomining & Bioleaching

L.O: To understand the terms phytomining and bioleaching

Parys Mountain copper mines, Amlwch (Wales), 1989 What is the impact of this?

Copper mines in Waleshttp://www.bbc.co.uk/wales/history/sites/themes/society/industry_copper.shtml

Electrolysis

• Electrolysis is very expensive to complete and open cast mines also have a massive ecological impact. Copper can be also be obtained from copper salts using scrap iron, however in recent years two new approaches have been made to extract pure metals: -

• Phytomining• Bioleaching

Phytomining•P

hytomining uses plants to absorb naturally occurring metal compounds (including copper) when they grow

•Once a significant amount of metal compound has been absorbed the plants are burned, producing ash which contains the metal compounds

• This method can also be used to extract metals from contaminated land

• Brassicas (cabbage family) can be used to extract cadmium, cobalt and nickel

• Look at the celery which has been left in copper sulfate (blue leaves)!

Phytomining Practical•C

omplete the practical to produce pure copper

1.Brassica plants have been grown in conditions with large amounts of naturally occurring metal compounds (specifically copper)

2.The plants have subsequently been ‘ashed’ in the fume cupboard

3.Add sulfuric acid to the ash

4.Filter the mixture

5.Leave to dry and then displace using iron filings…

•What evidence is there that the experiment has worked?

Displacement•A

dding the iron fillings to the copper sulfate solution will cause a displacement reaction

•The iron is more reactive than the copper, displacing it to form iron sulfate and copper

Bioleaching•B

ioleaching uses bacteria to produce leachate solutions that contain metal compounds…

•Some bacteria can live by using the energy of the bonds between sulfur and copper – in doing so this separates the metal from the ore

•Bioleaching is extremely energy efficient, however it is very slow…

Metal Theft•M

etal theft is increasing in the UK – currently it is the fastest growing theft

•This is because metal prices are steadily increasing (with the cost of the raw materials / oil used for machinery to extract / power electrolysis)

•Recycling metals is a way to cheapen their overall cost…