C14 The Earth's resources Flashcards
What is sustainability?
Using resources to meet the needs of society now, without endangering the ability of future generations to meet their needs
Explain how potable water is produced from fresh water
- Fresh water is collected from an appropriate source such as rivers, streams or lakes
- The water is passed through filter beds, usually made of sand and gravel, which removes undissolved solids
- The water is sterilised using chlorine, but sometimes ozone or UV light, which destroys harmful microbes
What is an ore?
A rock which contains enough metal to make it economically worthwhile to extract the metal
describe the properties of copper
- Unreactive so corrosion resistant
- Very good conductor of heat and electricity
- High melting point
- Malleable and ductile
Uses of copper
- Electrical wiring
- Gas and water pipes
- Sauce pan bases
How could you extract copper from its ore?
Reduction by carbon
Explain how phytomining works
- Plants grow on soil contains low-grade copper ore
- Plants take up copper from the soil by their roots
- Plants are burnt and the ash dissolved in sulphuric acid to produce copper sulphate
- Copper displaced by adding iron
- Impure copper purified using electrolysis
Explain how bioleaching works
- Bacteria feed on low-grade copper ores
- Through biological and chemical processes, a solution of copper ions is produced
- Copper is displaced by adding iron
- Impure copper is purified using electrolysis
Traditional methods of extracting copper
Smelting
- copper ore is heated to high temperature in a furnace to produce impure copper
Sulphuric acid
- copper can also be extracted using sulphuric acid to produce copper sulphate
- the copper can then be extracted via a displacement reaction
Impure copper is then electrolysed to produce pure copper
Explain the electrolysis of impure copper
- Impure copper is used for the anode
- Pure copper is used for the cathode
- Uses copper sulfate solution
- At the anode, copper atoms from impure copper are oxidised to copper ions
- Copper ions transported from anode to cathode
- At the cathode, copper ions from impure copper are reduced to copper atoms
- As the atoms of the impurities are not transported, the copper that builds up on the cathode is extremely pure
Problems of traditional methods of extracting copper
Mining:
- produces large amounts of waste rock
- destroys habitats
- scars the landscape
Smelting:
- requires lots of energy for smelting and then electrolysis
- only worth extracting from high-grade ores which are finite resources
What is meant by a high-grade ore?
Rock that contains a high percentage of metal
What is meant by a low-grade ore?
Rock that contains a low percentage of metal
Advantages of bioleaching
- Very energy efficient
- Simple process than smelting, which requires fewer expert staff to operate, reducing costs
- Used to extract copper from low grade ores which are unsuitable for smelting
- Produces less sulphur dioxide emissions than smelting
Disadvantages of bioleaching
- It is very slow, takes a long time for companies to earn money from their investment in a bioleaching business
- The process can produce toxic chemicals which may run off into rivers and other sources of drinking water
- Once started, the process can take a long time to stop should a pollution problem arise
Advantages of phytomining
- Decontaminates polluted ground
- Obtain metal from ground where other extraction methods would not be suitable
- Carbon emissions are lower than for smelting
Disadvantages of phytomining
- Copper produced isn’t pure and requires electrolysis, so it is not energy efficient
- Growing high yielding plants reduces nutrients in the soil and may require a high input of fertilisers to maintain growth
- The concentration of metals in plants is very low
- It is dependent on good growing conditions such as adequate rainfall
What is phytomining?
The extraction of copper from low-grade copper ore, using plants
What is bioleaching?
The extraction of copper from low-grade ores, using bacteria
Similarities between phytomining and bioleaching
- Both methods produce a solution of metal compounds, more concentrated than they were in the low-grade ore
- The metal compounds can be processed to obtain the metal, by displacement reaction with iron and/or by electrolysis
Environmental impacts of the production, usage and disposal of Lego
- Packaged in cardboard boxes and plastic bags, plastic comes from crude oil
- Transported around the world, ships and lorries use fossil fuels
- Lego cannot be recycled, most goes to landfill
- Heat is used to melt the plastic so it can be moulded into shape, much of this energy comes from burning fossil fuels, leads to pollution
What are life cycle assessments?
Used to assess the impact on the environment caused by manufactured goods at each stage of their life (from cradle to grave)
What are the four stages that need to be considered when carrying out LCAs?
- Extract and process raw materials
- Manufacturing and packaging
- Use and reuse of product
- Disposal of the produce at the end of its useful ‘life’
How is a LCA carried out?
- Listing all the energy and material inputs and outputs to the environment
- Inputs = raw materials, energy
- Outputs = atmospheric emissions, waterborne wastes, solid wastes, coproducts
- Evaluating the environmental impact of these inputs and outputs
- Interpreting the results to make decisions about using one material, process, product to service over another
