Bentonite is a clay that has a yellowish appearance. This clay was discovered in 1890 not far from the town of Fort Benton in the American state of Wyoming. The latter named the clay "bentonite" in reference to its place of discovery.
in the rock.
Significant areas with bentonite deposits in Germany
To the right and left of the Isar lie the areas that are considered decisive for the extraction of bentonite. These are the regions around Landshut and Moosburg. Further deposits can be found in the Swabian region near Thannhausen. Bentonites are also found in the region of Landau in Lower Bavaria. These occurrences are supplemented by clays with a montmorillon focus. These are found in Schleswig-Holstein and in the Westerwald.
Details about the bentonite deposits in Bavaria
The area of deposits with bentonite is distributed in Bavaria over an area of 250 square kilometers. The bentonite deposits are located at an altitude of between 450 and 480 meters. There are now secured bentonite deposits that can be mined, the amount of which is ten million tons. If 350,000 tons are mined annually, this means that supplies will be secured for a period of 25 to 30 years. The deposits of bentonite in Bavaria usually offer a typical lenticular appearance. Their diameter can be several kilometers.
Insight into the history of bentonite extraction
At the beginning of the 20th century, the extraction of bentonite began in the areas of Landshut, Mainburg and Moosburg. The first offer of the clay was as coloring earth. Some time later, the clay was presented on the market as bleaching earth. About five decades have passed up to the present point of view of bentonite extraction. The picture of extraction was once determined by laborious extraction in underground mining. In the meantime, extraction takes place only in opencast mining, with between seven and ten opencast mining operations located within the aforementioned triangle.
Chemical modification is not absolutely necessary in every case. This is clearly demonstrated by cat litter, which is manufactured using untreated calcium bentonite. Furthermore, the pet food, cosmetics and food industries are also supported in their applications by natural bentonites. In some cases, the swelling behavior differs. Some bentonites have a higher swelling and water-binding capacity.
There are two ways of activation. One is alkaline activation, which increases an already existing good swellability. There is also acid activation to increase the surface area of bentonite.