What is Limestone?
Limestone is a sedimentary rock composed of calcium carbonate, mostly formed by the accumulation and subsequent solidification of marine fossil debris. 
Yes, it’s a rock filled with tightly packed fossils. But limestone’s calcium carbonate is one of the most utilitarian industrial minerals. It’s the rubble underneath almost every road. It fronts many public monuments. But it’s been the hero ingredient of building mortar for millennia. And it remains so for modern cement. Another offshoot - soda ash - is a foundation stone of the chemical industry. It’s in paper and soap, plastics and rubber, glassmaking and industrial waste treatments. It’s a fertiliser and soil conditioner. It’s in food supplements. It’s in steel smelting. It’s behind hydrochloric acid. And while its industrial use often entails heavy CO2 emissions, treated limestone shows promise for carbon capture and storage.​
How is it used?
Limestone is one of the most useful and versatile of all industrial minerals. It is used to manufacture lime which, when mixed with clay or argillaceous material, produces cement.

When fired to temperatures of approximately 1480ºC, it produces fused material consisting of complex silicates and aluminates in the form of hard, glossy balls known as cement clinker. The clinker is then cooled and sent to storage for export or grinding into cement. A small percentage of gypsum is generally added to the clinker at the grinding stage as a retardant to prevent premature setting of concrete. 

Limestone is also used in the production of soda ash (sodium carbonate) for the chemical industry with applications in paper, soap and detergent manufacture, tanning, water treatment, and industrial waste treatment. Sodium carbonate is an important component in glassmaking. 
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Did you know?
The world consumes approximately 1.5 billion tonnes of cement per year?  
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Where is Limestone mined in South Australia?
Limestone is widespread in South Australia including at Penrice, on the Fleurieu Peninsula, in the Mount Lofty Ranges, Yorke Peninsula, Flinders Ranges and Stuart Shelf.
 
Adbri produces a range of lime, clinker and cement products at its Angaston and Birkenhead sites.