bonnybridge iron works
The next big industry to come to Bonnybridge was IRON FOUNDING.
IRON FOUNDRIES made many useful and often very beautiful objects from iron through a process called MOULDING and CASTING.
SO WHAT DO IRON FOUNDRIES DO?
Basically they buy slabs of iron (called 'pig iron') which have been make from rocks containing iron ('iron ore') dug out the ground. The iron ore is put into a large coal-fired furnace along with some other materials. This furnace is so hot that the rocks melt and the iron inside the rocks can be separated out from the waste rock (called 'slag') and left to cool into slabs. Watch this animation here to see how it works.
Iron foundries buy the slabs (PIG IRON) and re-melt the 'pigs' in their own furnaces until it the iron is molten and runny. This 'molten iron' is runny enough to be poured into moulds (like making models from plaster of Paris). When the iron cools it hardens and the moulds can be broken open and the new shape appears.