Black Hills Bentonite (Exploration, Mining, and Reclamation)

Bentonite seams are commonly visible throughout the Wyoming landscape.

Exploration for new bentonite beds is normally accomplished with auger bit drilling. Once the auger drill stem reaches the soft bentonite it sinks very rapidly, which indicates to the driller that bentonite has been found. The auger flights are then withdrawn and the "sticky" bentonite is sampled from the flights for quality analysis.

Bentonite mining Bentonite is mined by surface "open pit" methods. Various types of heavy equipment including bull dozers and rubber-tired scrapers are used to remove the shale rock overlying the bentonite.

Topsoil, as well as the underlying material, is carefully removed and stockpiled. These "overburden" materials as they are called will be placed back and reseeded once the bentonite has been removed. The bentonite which is exposed during this process can be as little as 1 1/2 feet or as much as 10 feet thick. This is the material which is mined and processed.

Many bentonite manufactures prefer to "field dry" the exposed bentonite prior to hauling it to the processing plants. This is accomplished by plowing and discing while taking advantage of the low humidity and sunny days to dry the bentonite prior to its removal. The moisture level prior to "field drying" can exceed 30%. This process will normally extract 15 to 20% of the moisture from the clay prior to hauling.?

RECLAMATION

Reclamation, Black Hills Bentonite
Plant growth is monitored on reclaimed lands.

Once restored, reclaimed land shows
little effect of mining operations.