By Chisom Ibemere
Bentonite is a clay that consist mostly of montmorillonite which is formed by the weathering of Volcanic ash in sea water or by hydrothermal circulation which converts Volcanic glass into clay minerals. Bentonite clay is also known as aluminium Phyllosilicate.
Bentonite is a swelling clay that has the capacity to absorb large amount of water raising the volume by up to a factor of 8. This quality makes Bentonite beds unfit for construction and building purposes but can be used in groundwater sealants and mud drilling.
Bentonite can be divided based on the quality of sodium and calcium cation they contain, the swelling index and PH. The three classification includes the natural sodium bentonite, natural calcium bentonite and activated calcium bentonite (sodium-calcium).
Natural sodium bentonite contain a lot of impurities and are benefitial on wine. They have moderate and same quantity of sodium and calcium, swelling index and basic PH close to 9.
The natural calcium bentonite contains small portion of sodium and high calcium. It has a very low swelling index and neutral PH. The activated calcium is widely used with a high swelling index and PH between 9-10. It has a high level of exchangeable sodium and calcium.
Bentonite are used as a binding agent in Iron ore pellets production. In Engineering, Bentonite are basically used as lubricants and support system in foundation and diaphragm walls and pipe Jackings. They are mainly used in wastewater purifications due to their absorption properties. They are used as supplements in animal feed.
Bentonite can be found in Edo, Kogi, Ogun, Ondo, Adamawa, Plateau and Borno States. They are popular in Nigerian market but basically known as Nzu or Ndom in Efik.
Bentonite was first mined in Nigeria in 1961 in Bende Local Government Area of Old Abia State in the Eastern part of Nigeria.