Quicklime (calcium oxide)

Some of the lump lime is processed further to make quicklime. To do this the material is first pre-crushed to grain sizes smaller than 20 mm using an impact mill. The pre-crushed material is then finely ground (pulverized) in a roller mill with an integrated air-classifier. From there the quicklime is delivered to the storage silos or to the bagging plant.

Quicklime is available in two different qualities, nekafin® 2 and nekasol® 10, mainly differing in grain size. nekafin® 2 has a lower coarse fraction content.

nekafin® 2 and nekasol® 10 can both be transported in bulk by rail or truck or bagged in bags of up to 20 kg. nekasol® 10 is also available in 50 kg bags. Both qualities are also available in big bags (800-1000 kg).

nekafin® 2 is used in the manufacture of sand-lime brick products. For this purpose, a mixture of quicklime, silica sand and water is compressed into moulds to form bricks that are then cured for several hours by exposing them to hot steam in high-pressure autoclaves. After cooling, the white bricks are ready for use immediately. The quicklime used in the process should be reactive and free of any colouring component such as iron or manganese as the bricks are often used un-plastered.

In waste incineration plants large quantities of acid effluents that come from the scrubbing of flue gases need to be neutralized with milk of lime before they can be discharged. Milk of lime is typically produced in on-site slaking units using nekafin® 2. Quicklime should be properly slaked, i.e. show the desired reactivity, and have a high content of free calcium oxide.

nekasol® 10 is used mainly for soil stabilization purposes. Where a road is to be built on clayey soil, the soil should first be appropriately treated to prevent construction vehicles from sinking into it and, later, to prevent the constructed road from sagging under its own weight. Such stabilization is achieved by adding calcium oxide to the clayey subsoil prior to paving. The slaking reaction of quicklime causes water to be extracted from the soil. In addition, calcium ions react with the clay minerals contained in clay creating granules of clay particles that can be easily compacted. Lime-stabilization thus helps achieve stable subsoil for road construction. Also in this case a reactive, high-purity calcium oxide is required.