Lime kiln

A lime kiln is a kiln used to produce quicklime from limestone. The process itself is known as lime, and the name created by the Occupation Kalkbrenner is derived from this plant from. The importance of lime burning shows up in numerous places called lime kiln and its coat of arms.

History

The selective processing of limestone a versatile building material is one of the oldest and still most important technical production. The oldest evidence of lime production for processing in screed floors of cult -like plants come from the mountain temple of Gobekli Tepe in Anatolia and 11,000 years old. In ancient times the art of lime burning was widespread. As fuel, wood, peat or coal was used originally. The first institutions to were so-called pile, while later simple Feldöfen were used without Walling. Simple earth pits, where lime was burned in the 20th century, can be found in large numbers in the wooded Bükk in Northeast Hungary.

Lime kiln on the crest of Lažánky in the Czech Republic

Historic lime kiln at the Open Air Museum in Maria Saal

Former lime kilns in Wriezen

Lime kiln Brandenburg (built 1890) at Kronenburg

Chemical processes

Calcium carbonate ( CaCO3, limestone) are at temperatures from 900-1200 ° C carbon dioxide ( CO2) and changes into calcium oxide ( CaO, lime ), this is referred to by the deacidification of limestone. This step is referred to as calcination. The quicklime is then further processed with water to lime paint, lime or hydraulic lime.

Technical implementation

The procedure has changed from a technical perspective throughout history again and again. Just as in many other chemical engineering processes, which were previously more or less inevitably, discontinuous manufactured, modern, industrial processes are based on continuous processes.

Historic lime kiln

The main steps were:

• Filling the lime kiln
• Firing
• Expulsion of water
• Covering with clay
• By annealing

Industrial production

Nowadays lime is supplied in the form of limestone from a lime quarry and heated in vertically operating ring or shaft or in rotary kilns or Wirbelstromöfen to about 900-1300 ° C. The advantage of this method lies next to the economical continuous process also improved mass and energy exchange between the solid and gaseous phase.

The furnaces are going continuously from above, charged with a mixture of 90 % limestone and 10% coke. This mixture passes through, slowly sliding down the different temperature zones of the furnace. In the lower and middle area of the shaft furnace burns the coke and generates the required for the chemical reaction temperature. Below is the quick lime is discharged via a rotary plug.