20 Jun Mining and burning
As the inhabitants of Mønsted became Christians more than 1000 years ago they at the same time got them selves a new extra source of income, ”lime quarrying and lime burning”. The new religion required churches preferably built of stone. The stones were held together with mortar made with slaked lime, a new building material in Denmark.
Under the fields of Mønsted there was limestone, previously a worthless rock, now an income source (it never was enough for creating wealth). During the next 200 years more than 2000 stone churches were built, app. 10 each year.This building activity launched the limestone industry in Mønsted, which did not come to an end until 1978.
The location of Mønsted near Viborg, the ”capital of Jutland” with 12 parish churches, a cathedral, monestaries, a bishop addicted to building projects, and wealthy citizens, meant that Mønsted always could count on customers buying the burned limestone, which was essential for a stable procuction. Calcinated at about 1000 °C the limestone (CaCO3) liberates carbon dioxide (CO2)and is converted into burned limestone(CaO). As the burned limestone cools it absorbs water and is converted into slaked limestone (Ca(OH)2). The slaked limestone is converted into limestone when it absorbs the carbon dioxide of the air. Of this reason burned limestone is no stock item and must be used for building purposes shortly after production. An efficient limestone industry requires a market that continuously can take delivery of the burned limestone.
As Viborg in the 16. Century weakens, Mønsted had allready found a bigger market. In the 1860´s with the highest production ever were about 3000 loads of burned limestone brought from Mønsted and neighbouring Daugbjerg to buyers all over Jutland.
The limestone was burned in shaft kilns, like a wide chimney with a possible height of 5 m and width of 4 m. In the kiln the limestone was piled so that a wide pocket was created at the fuel input hole where the flue gas could burn. As long as the woods at Mønsted existed the kilns were fired with wood, but allready in the 16. Century the woods were cut down and the limeburners had to use heather from the wast Alhede.
The kilns had to cool before unloading. The permanent firing and cooling required much fuel. As at the end of the preceding century new kilns were introduced that could be loaded and unloaded witout cooling, the old kilns were outdated from one day to the next. Lime burning was now an industry that required more capital than simple farmers could bring up.
In 1872 the farmers of Mønsted sold all limestone rights to the big company ”Mønsted Kalkværker” that later became a part of ”De jydske Kalkværker”. The red factory building with the, at that time, modern kilns is a memorial for the industrial history of the last hundred years in Mønsted.
In 1997 the Danish Nature Agency acquired the Limestone Caves of Mønsted. The acquisition was directly caused by the owners closure of the caves in 1995 those having been open to visitors for many years.This was regarded as unfortunate by many people and the Danish Nature Agency initiated legal proceedings for protection and reopening of the caves. In the end the state took over the caves, the limestone factory and app. 10.000 hectares of land. In this way all interests in the property were considered. Above all the goal was to secure the caves as the most important hibernation site for bats in Europe but also to secure the cultural historical, the recreative and geological interests connected with the site.