why_we_need_limestone - Miss Emms

siennatearfulUrban and Civil

Nov 25, 2013 (3 years and 6 months ago)

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What
is the
link?

Limestone: is it worth it?


Why we need limestone


Where limestone comes from


The impact quarrying has on


The local community


The economy


The environment


Today we are finding out……

Activity

How does it involve limestone?

Eat a
sandwich

Acid soils are treated

with limestone

Limestone is added to bread to increase the
calcium content

List 5 things you have done today……

What is Limestone?


Limestone is made up of
shells
of
dead
sea
creatures. It contains carbon that has been
locked away for millions of years.




Layers of these built up over millions of
years, and were squashed together until they
formed limestone
.




It
is a sedimentary
rock, it is porous and
often contains fossils.

Types of Limestone

There
three different types of limestone
:




Chalk

is a very
soft (formed under low pressure)
and high purity CaCO
3



Marble

is a
metamorphic

rock it is
the hardest
form of limestone, as it was subjected to lots of
pressure when it was
formed. (no fossils!)



Limestone

is the third type and is formed at a
medium pressure
. It is often
coloured

by other
chemicals e.g. iron compounds.

Chemical Stuff


Limestone is made of
calcium carbonate
(CaCO
3
).




Calcium carbonate
is
insoluble

in water.



It is
a
base
. (It will react with acids)



Acid rain erodes limestone



H
2
SO
4

+ CaCO
3



CaSO
4

+ CO
2

+ H
2
O

and its uses

Where do we find

Limestone?


Sedimentary rock formed in
shallow tropical seas millions
of years ago



The Yorkshire Dales and the
Peak District have a lot of
high purity Limestone from
coral reefs and other sea
creatures!



It is permeable and
susceptible to weathering
Karst

scenery is spectacular
Tourism

Malham

Cove, Yorkshire Dales

Limestone caves

What
else can
limestone be used for?


Limestone is fairly resistant,
but it is still easy to cut
making it ideal for use as a
building material.



Building
walls



Building houses



Limestone is also used to
make
glass, mortar, cement
and concrete




More about limestone


Limestone is dug up out of the ground
in
quarries


A
bout
150 million tonnes
of limestone
are quarried
in Britain each year, for
many different uses…




1. Building
Stuff


Limestone has been used for building for many
centuries.


Many old buildings are made out of limestone
.
(the Pyramids, St Paul’s etc)


Very little limestone quarried is used in this way


Aggregate is the largest use of limestone


Crushed stone is used to make concrete


Aggregate is used as
roadstone


Limestone is not the best material to use,
but it is one of the easiest to extract.

2. Aggregate (crushed stone)

3. Cement


When limestone is heated with clay it forms
cement, a substance that sets gradually when
it reacts with water
.




Cement can be made into mortar by adding
sand and water. Mortar is used to set the
bricks in walls, as when it dries it acts as an
adhesive between the bricks
.

4. Concrete


Cement can also be made into concrete
by adding water, sand and small stones or
gravel.



Concrete is used for all kinds of building
work, including paths, walls and large
buildings
.


Reinforced concrete has steel bars in it

5. Glass


Typical everyday glass is called soda lime
glass.


It
is mostly made from sand, but limestone
is also added to it before it is heated up
.


It also contains sodium carbonate (which is
itself made from limestone)



6. The chemicals industry


High grade limestone is used as a raw
material for the chemical industry


It is used in…


water treatment


manufacture of tablets, paper, leather and
plastics, toothpaste, soaps and detergents


food as an additive to increase calcium
content (for humans and animals!)


To make other useful chemicals, e.g. sodium
carbonate


7. Agriculture


Acid rain can make soil acidic. Limestone
is used to
neutralise

it.



This is because calcium carbonate is a
base (an insoluble alkali
)


It is also used to supply plants with
calcium, plants cannot grow well without
calcium as it is needed to make cell walls.

8. Neutralising acid lakes


Burning fossil fuels gives off
sulfur

dioxide


Sulfur

dioxide dissolves in rain to form
sulfuric

acid


Acid rain pollutes lakes


Lime is added to neutralise it


9.
Desulfurisation


Fossil fuels are burnt to generate
electricity in power stations.


This releases
sulfur

dioxide into the
atmosphere.


Waste gases can be
desulfurised

by
passing them through a slurry of
limestone (or slaked lime)

10. Making steel


Limestone is added to the blast furnace to
remove acidic impurities in the iron ore.


The liquid slag formed floats on top of the
molten iron, it is poured away leaving the iron
behind.

What has limestone ever done for us?

Rank the uses of limestone in order of importance,
be prepared to justify your choices!

Quarrying

Quarrying and Mineral extraction


Before the industrial revolution quarrying was
used to provide limestone as a building material,
by men with axes.



Nowadays the rock is blasted with explosives to
provide crushed rock to make cement, and for
aggregate.



To build1km of road around 500
lorry loads of crushed stone
are needed!


Is there an alternative?

Most Limestone comes
from the national parks,
Why?



Cheap and easy to
extract


V
ery abundant


Hard and resistant


H
uge demand.

Quarry aerial photos


http://www.webbaviation.co.uk/gallery/v/e
nvironment/quarries/


Case study:
Topley

Pike Quarry


Your mission (that you are choosing to
accept whether you like it or not!!!) is to
weigh up the pros and cons for the
proposed extension to the quarry, and
write a letter to the National Park
Authority explaining your views……



To be continued…..






(for homework!!)

What are the effects on…


The local community? (jobs, noise, traffic, amenities…)


The economy? (tourism, jobs, industry, small businesses…)


The environment? (wildlife, pollution, regeneration…)