HOW IS SALT EXTRACTED?

C3 Lesson 4

Learning Outcomes

All … will list the different ways salt can be extracted

Most …will describe the two main ways of extracting salt from below the ground

Some … will evaluate the impact salt extraction can have on the environment

Match the maps to the resource

Limestone

Coal

Salt

How did they get there?

How did Britain used to look? How has it’s position on Earth changed over time?

Where did the coal come from? Where did the limestone come from?

Can you think of ways in which the rock salt formed?

Salt in Cheshire The Rock salt at Winsford

was formed 220 million years ago when England was covered by inland seas.

Hot temperatures evaporated the waters extremely slowly leaving large salt deposits under the earth in and around Cheshire.

Over time the rock salt has been trapped under layers and layers of other sedimentary rocks.

Where do we get salt from?

We get salt from two main sources, what are they?

1. Sea water – by evaporation

2. Rock salt – by mining or solution mining

On an A4 spread, start a brainstorm of these three methods – you need to know them in detail

Different salts, different uses

sea salt – used in foods and chemical industry as it is the cheapest to make. Sea salt has to be purified before it can be eaten

Mining salt – used directly on roads when it is icey

Solution Mining Salt – used largely by chemical industries

Sea salt

Video on sea salt production

1. Mining

Also known as Dry Salt Mining – see video

1. Salt Mining in the 19th Century Traditionally, men were lowered down a

tunnel and used picks and shovels to excavate the salt. It was carried up to the surface and sold.

Eventually technology advanced and power tools and controlled explosions were used.

Mining in the 21st Century Now mining is much more mechanised

and involves large, precision machinery.

2. Solution Mining

Instead of digging for the rock, water is used to dissolve the salt and then pumped back up to the surface

SOLUTION MINING ANIMATION Solution Mining Video withformation of rock salt

Salt mining and the environment Make a list of the impact that Dry Salt

and Solution Mining might have on the environment

You should think about plant life as well as animal and human

You should think about the amount of energy, and therefore fuel, is required in each method.

EXTENSION: can you think about the risk involved in each method of salt mining

Rock Salt in Crowborough

A deposit of rock salt has been found beneath Crowborough.

In your groups decide on two things: A – Should we mine for the rock salt? B – Which method should we use?

Factors to consider:• What infrastructure will be required?

(think about roads, traffic, trains, housing, factories)

• Can Crowborough cope with a new industry in the area?

• Which method of mining will be most economical and environmentally friendly?

What is your final decision?

As a class vote for what you want to do about the rock salt in Crowborough.

Who is most likely to benefit from your decision?

Who is it going to have greatest impact on?

Will anyone lose out?

What are the risks? Are the outweighed by the benefits?