The Uses of Limestone in the Production of Iron and Steel, in Road-building

Limestone is a very important material in the making of iron and steel. Iron ores, such as haematite, contain iron oxide. The production of iron involves reducing this iron oxide to iron in a furnace.
In steel-making, limestone is used as a flux to remove impurities during the process. A flux is a substance that is melted to make a slag. Slag is stony waste matter separated from metals during the smelting or refining of ore.
When haematite is heated in a blast furnace with coke (a form of carbon derived from coal) and limestone, a series of chemical reactions occur. The coke reacts with the oxygen in the air to form carbon dioxide, which then reacts with more coke to form carbon monoxide.
The carbon monoxide then reduces the iron oxide in the haematite to iron. The limestone reacts with impurities, such as sand in the iron ore, to form a slag. This slag can then be tapped off from the mixture.
The blast furnace employs calcium oxide (quicklime) produced from limestone to assist in removing acidic impurities from the iron.
In the construction industry, particularly in road-building, limestone is a crucial component. It is crushed and used as an aggregate, which is a material, or a combination of materials, both coarse and fine, that are used in construction.
Crushed limestone is used as a base for road construction and is also utilised in the production of asphalt. A mixture of aggregates, binder and filler, asphalt is used primarily in road construction and maintenance.
Limestone is chosen due to its strength, stability, and durability. It has the ability to maintain its form under traffic loads and can withstand the effects of weather.
In addition, limestone is also used in the production of cement, which is a key ingredient in concrete. Cement making begins in a limestone quarry where limestone is chemically converted into a substance called lime.