Quality Control

• CHEMICAL COMPOSITION:

  Hydrous aluminum Silicate containing small amounts of alkaline earths.
  (Mg, Ca) O, Al2 O3 5 SiO2, nH2O [where n is equal to about 8]

   

  PHYSICAL CHARACTERS:

  This clay varies in colour from white [with reddish tinge], to green. In silu colour is darker while on exposure it fades out. When immersed in water it swells many times and forms a gel. It has a high bonding property. The specific gravity is 2.4 to 2.8 and refractive index 1.547 to 1.55, it's fusion point varies from  1330˚ C to 1430˚ C

  Physical properties of Bentonite are as follows :

  	Kutch	Bhavnagar
  Moisture at  105˚	11.17 %	10.34%
  Specific gravity	2.52	2.43
  Liquid limit	546	539
  pH30˚C	9.20	9.80
  Gel value	60	10
  Swelling index	28.5 ml	18 ml
  Base exchange capacity meg/100 gm	87.36	64.53
  Viscosity
  [a] 600 rpm	176	5.0
  [b] 300 rpm	166	2.5
  Filter loss	17.5 ml	36.5 ml
  Exchangeable Ca++ ion	0.43%	0.27%

  TYPES

  There are mainly two types of Bentonite.

  • High swelling (Sodium Bentonite)
  • low swelling (Calcium Bentonite)

   

  USES

  • It is used in preparation of drilling mud for oil well drilling.
  • For a catalyst in Petroleum refining.
  • In ferrous and non ferrous metallurgy as a foundry sand bond.
  • It is also used in pharmaceuticals, cosmetics etc.
  • It is also used as a thixo-trophic agent to prevent setting of mixed paints.
  • It is used for lining canals and earthen dam in civil engineering.
  • At present sodium Bentonite is used in large quantities as a binding agent in pelletizing of iron ore fines.
  • It is also used in ceramics and insecticides.

  Most of the industrial applications involve the swelling property of Bentonite to form viscous water, suspensions. Depending upon the relative preparations of clay and water, these mixtures are used as bonding plasticifying and suspending agents.