The largest consumers of lime products are iron, steel and construction industry, pulp and paper industry, chemical industry, sugar industry and agriculture. Significant amounts of lime are used for environmental protection (neutralization of waste water and waste gas).
In industrialized countries, the consumption of lime now stands at about 85 kg per capita per year. The global production of lime, including small producers in developing countries, as well as producers of lime for their own needs (steel mills, paper mills and sugar), is estimated at 300 million tons per year. The market receives about 120 ml tons per year.
Building lime is referred to the product obtained by firing up a full selection of carbon dioxide and calcium-magnesium rocks containing no more than 8% of clay and sand impurities. As raw materials carbonate rocks – limestone, chalk, coquina, dolomitic limestone are used.
Types of lime
According to the number contained in the lime silicates and calcium, giving it hydraulic properties, the following types are distinguished:
- Air lime, providing hardening of mortars and preservation of strength at normal humidity;
- Hydraulic lime, providing solidification and strength retention solutions used both in air and in water. A more universal solution is massively utilised by architectural innovators, such as Telling, focusing on hydraulic lime and lime mortar technologies.
In the air lime the amount of silicate and calcium aluminate-ferrites usually vary in the range of 4-12%, in some cases up to 20%. With the content of 25-40% of lime clinker minerals it shows weak hydraulic properties, such lime is called poor hydraulic lime. Strong hydraulic lime contains from 40 to 90% of silicates and alumino-ferrates.
By referring to the air contained in the main lime oxide, it can be:
Calcium lime contains 70-96% of CaO and 2% MgO. Malomagnezialnaya lime consists of 70-90% of CaO and 2-5% of MgO. The lime magnesia contains 5-20% of MgO, in dolomite this mark equals 20-40%.
Depending on the options for further processing of the calcined product there are several types of air lime:
- Quicklime lump lime – single piece of pumice consisting mainly of Ca (OH);
- Ground quicklime – powdered product grinding lump lime;
- Hydrated lime (slaked) – hydrated lime – fine powder resulting from lump lime quench certain amount of water, and consisting essentially of Ca (OH);
- Lime putty – pasty product clearing lump lime consisting mainly of Ca (OH) and mechanically admixed water;
- Milk of lime – white suspension, wherein the calcium hydroxide is partly dissolved and partly suspended.
By blanking time all sorts of air quicklime are divided into three groups:
- Fast slacking – blanking period of not more than 8 minutes;
- Mid slaking – blanking period of not more than 25 minutes;
- Slow slaking – blanking period of no less than 25 minutes.
Lime powder is obtained by grinding or blanking (hydration) lump lime, divided into: lime without additives and with additives.
Features and specifications
In the production of building lime the following materials are used: carbonate rocks and minerals (granulated blast-furnace slag, active mineral additives, quartz sand).
Air quicklime without additives is divided into three classes; slaked powdered with additives is divided into 2 classes and hydrated (slaked) products without additives and with additives are divided into 2 classes as well.