Chemistry - 14 The Earth's Resources - 14.4 Extracting Metals From Ores & 14.5 Life Cycle Assessments & 14.6 Reduce, Reuse and Recycle

Ore

a rock which it is economically worth extracting metal from

What is copper used for? [2]

- pipes

- wiring

What properties of copper make it useful? [3]

- high electrical conductivity

- doesn't oxidise (rust)

- malleable

Low-grade ore

ore containing a small amount of a desired mineral

Methods for extracting copper [2]

- sulfuric acid is used to produce copper sulfate, from which copper is extracted

- smelting

Smelting of copper ore

copper or is heated to a high temperature in a furnace to produce impure copper

How is copper extracted from copper sulfate? [2]

- electrolysis of copper sulfate

- displacement from copper sulfate by iron, then electrolysis

How is pure copper extracted from impure copper?

electrolysis using the impure copper as the positive electrode

Bioleaching

flooding ore sites with bacteria to produce leachate solutions containing metal compounds

Leachate

liquid from an ore site undergoing bioleaching

Phytomining

using plants to absorb metal compounds, then burning them and extracting the compounds from the ash

How are copper compounds extracted from the ash in phytomining?

sulfuric acid is added and a copper sulfate leachate is collected

LCA stands for ...

Life Cycle Assessment

Life Cycle Assessment

evaluation of the effects a product has on the environment over its life

What is included in a Life Cycle Assessment? [5]

- transportation and distribution for each stage

- extraction and processing of raw materials

- manufacturing and packaging

- use and reuse

- disposal

How is an LCA carried out? [3]

- listing all material and energy inputs and outputs to the environment

- evaluating potential environmental impacts of inputs and outputs

- interpreting results to make decisions about using one material, process, product or service over another

Outputs included in an LCA [4]:

- atmospheric emissions

- waterborne waste

- solid waste

- energy dissipation

Carbon footprint vs. LCA [2]

- carbon footprint only accounts for release of carbon dioxide and other greenhouse gases

- LCA accounts for all products

Problems with LCAs [2]:

- some impacts are not quantifiable and rely on personal value judgements

- LCAs can be selectively used to promote a product

How is the problem of personal bias overcome in LCAs?

peer review

What do 'reduce, reuse, recycle' campaigns aim to reduce? [3]

- use of limited resources

- use of energy

- waste produced

What metals should specifically be recycled? [4]

- aluminium

- steel

- iron

- copper

How does recycling metal help the environment? [3]

- less fossil fuels used for energy for extraction

- less limited resources used

- less mining needed (hurts habitats and causes pollution)