Holcim (New Zealand) Ltd - How we make lime

Burnt Lime
Limestone (CaCO3) is blasted and crushed at a quarry and then stockpiled at the plant. It is then fed into a rotary kiln and burnt at temperatures up to 1200 degrees C. This process removes CO2, leaving CaO (burnt lime) as the final product. The burnt lime is then passed through a crusher and graded into various sizes. At McDonald’s Lime, for example, there are three sizes, 10-25 mm, 9.5 mm all in and 3 mm all in. The final product is trucked or railed in bulk to the customer.

Hydrated Lime
The manufacture of hydrated lime involves the regulated addition of water to burnt lime. In this relatively simple process, burnt lime of less than 3mm is mixed with water and passed through a hydrator and a (size) classifier. The final product is delivered to the customer in either bulk or bagged form.