Recycling metals and life-cycle assessments

A life-cycle assessment (LCA) adds up the environmental impact of a product from start to finish. Recycling can cut that impact.

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Recycling metals

Some metals, such as gold, resist oxidation and stay shiny; others, such as iron, corrode.
Advantages of recycling metals: saves limited ores; usually uses less energy than extracting new metal; less mining damage and less waste in landfill.
Disadvantages: metals must be collected, sorted and transported, which costs money and energy.

The four stages of an LCA

1. Obtaining raw materials (mining, drilling, growing).
2. Manufacturing the product and its packaging.
3. Using the product (energy, water, repairs).
4. Disposal at the end of its life (landfill, incineration, recycling).
At each stage, an LCA looks at use of energy, water and resources, and at pollution and waste.

Evaluating LCAs

Example data for practice (made up for this lesson):
Per 1000 bagsPaper bagsPlastic bags
Energy used to make (MJ)1500500
Uses before disposal14
Biodegradable?YesNo
Worked example

Using the example table, calculate the energy used per use for each type of bag (per 1000 bags).

  1. Paper: 1500 MJ ÷ 1 use = 1500 MJ per use
  2. Plastic: 500 MJ ÷ 4 uses = 125 MJ per use

Answer: Paper 1500 MJ per use; plastic 125 MJ per use. But plastic does not biodegrade, so an LCA must weigh several factors.

Key idea

Recycling metals saves ores and energy and reduces mining and landfill, but collecting and sorting cost energy. An LCA covers raw materials, manufacture, use and disposal. Some effects, such as pollution, are hard to measure, so LCAs can involve judgements and be used selectively.

Quick check

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Extra practice

2 more questions

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  1. Making 1000 paper bags uses 600 MJ of energy. Each bag is used 3 times. How much energy is used per use (per 1000 bags), in MJ?

    Show the answer

    Answer: 200 MJ

    600 ÷ 3 = 200 MJ per use.

  2. Which stage of a life-cycle assessment includes using a product?

    1. Marketing
    2. Obtaining raw materials
    3. Disposal
    4. Use and operation
    Show the answer

    Answer: Use and operation

    The four stages: raw materials, manufacture, use, disposal.

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Sources and references

Checked by the GCSE-ready editorial team, 17 October 2026. Last updated 2 October 2026. Spotted a mistake? Tell us and we will fix it.

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