Lime Production Switzerland

Modern lime production at KFN in Switzerland

Production

Know-how to refine Swiss lime

Nature has built up a rich reservoir of lime-containing stone over millions of years. The calcium-carrying sediments contain limestone with a calcium carbonate (CaCO3) content of more than 98 % - a purity unreached anywhere else in Switzerland. Using this unique raw material, we at KFN produce a wide range of lime and gravel products for an ample spectrum of industrial uses, taking advantage of decades of experience both as a company and of our staff, special expertise in the field and the most modern technology. Get to know our individual production steps. 

Lime production with most modern technology
Kalkproduktion Sprengen

Blasting

In thousandths of a second

Limestone is mined in open-cast mining and usually stoped by blastings. The blastings on the terrace-form steps demand the highest of precisions. Based on an exact drilling plan, our blaster and his team drill up to twelve blast holes. In dealing with the explosive, they obey the strict safety proceedings, as occupational safety is a top priority for us. The fuses are ignited with only thousandths of a second between the individual ignitions. Even though to the human ear it appears to be one single blast, this very short delay ensures that the blast's effect on the surroundings is kept to a minimum. The blast lifts the limestone slightly and breaks this raw material out of the mountain in big, raw boulders. 

Crushing

High Performance crushers

Gigantic loading machines with steel chain protected wheels carry the rock bulk onto dumpers. In the pre-crushing plant, jaw crushers act like huge nut-crackers, crunching the delivered rocks of different sizes between their steel plates. Once the stones have reached a certain size, they are washed. This removes all impurities and very fine particles. Thus refreshed and sorted, they travel from one conveyor belt to another, over oscillating screens with different mesh sizes, being sorted according to their size class. Now our crushed limestone is ready for being processed into the different KFN lime and limestone products. For the production of quicklime, only stones of the highest purity are used.

Lime production Crushing
Lime production Burning

Burning

Fully automatic burnt lime production

If you heat up limestone to a very high temperature, the carbon dioxide evaporates and calcium carbonate (CaCO3) is turned into calcium oxide (CaO). This so-called burnt lime or quicklime has lost nearly half of its weight in the process. At KFN, this burning process takes place fully automatic, at a temperature of around 1100 °C in our shaft kiln. Within 24 hours, up to 200 metric tons of highly reactive quicklime can be produced. More than a third of this quicklime is then comminuted, again in a jaw crusher, thus converting it into our lump lime nekafer®.

Grinding

In ground condition many possible uses

For our finer lime products nekafin® 2, nekafin® 0 and nekasol® 2, the quicklime coming from the shaft kiln has to be ground intensively. To this end, a part of the quicklime is first coarsely comminuted in an impact mill. The second, finer comminuting takes place in a roller mill. It uses air pressure to separate the finely ground material into the integrated separator. Here, the end product is separated from the airflow, while the coarser parts fall back into the grinding chamber. 

Lime production grinding
Lime production slaking

Slaking

Heat with water and pulverize

If you put quicklime in contact with water, it will absorb the water, getting very hot in the process, and then converts into slaked lime. We use this natural process: in a first step of the slaking process, we add water to our quicklime. The resulting lime powder is dried by the reaction heat and is removed from the slaking trough to be subsequently refined to our lime products nekablanc® 0, nekapur® 2, nekagard® 2 and nekapur® 5