11.04.5 Reducing Use of Resources

Syllabus

The reduction in use, reuse and recycling of materials by end users reduces the use of limited resources, use of energy sources, waste and environmental impacts.
Metals, glass, building materials, clay ceramics and most plastics are produced from limited raw materials. Much of the energy for the processes comes from limited resources.
Obtaining raw materials from the Earth by quarrying and mining causes environmental impacts. Some products, such as glass bottles, can be reused.
Glass bottles can be crushed and melted to make different glass products. Other products cannot be reused and so are recycled for a different use.
Metals can be recycled by melting and recasting or reforming into different products.
The amount of separation required for recycling depends on the material and the properties required of the final product. For example, some scrap steel can be added to Iron from a blast furnace to reduce the amount of Iron that needs to be extracted from Iron ore.
Students should be able to evaluate ways of reducing the use of limited resources, given appropriate information.

What does this mean?

Problems with extracting raw materials

Most raw materials are not renewable - they don't grow back.

And most of them are extracted from the ground by quarrying or mining.

One day we may run out of these resources - they are already getting harder to find.

And industrial mining creates huge environmental impacts.

Modern mines can destroy huge areas of land.

And the spoil tips can destroy even more.

And water travelling through old mines can become dangerously polluted.

Even when we try to minimise these impacts mining uses huge amounts of energy - most of which comes from non-renewable sources.

Reusing materials

In the past it was usual for milk to be delivered in bottles.

It takes a lot of energy to make a glass bottle.

But the milkman would pick up the empties, they would be washed and re-filled and could be used again many times.

When the bottle was no longer fit to be used it was melted down and recycled into a new glass bottle - which took much less energy than making a new one.

Recycling

These days we don't directly reuse materials very much.

We're more likely to recycle them.

Used plastic milk bottles are collected, sorted, melted and reformed into new products.

This sounds almost as good but there isn't just one type of plastic.

If they're not sorted out then the recycled plastic will be poor quality.

And bottles often have different plastics in the lids and the labels etc.

And sorting is very expensive - so recycled plastic is sometimes no cheaper than new, better quality plastic.

Lots of materials are recycled though: glass, plastics, metals.

It's quite easy for a scrap yard to separate Iron from Aluminium, for instance.

But Copper, Brass and Bronze would be more of a challenge.

So recycled metals are usually used where we don't need to control the quality of the metal quite as much.