Kaolin Clay (Aluminium Silicates)

There are various uses of Kaolin Clay. As an industrial chemical material supplier, we supply functional anhydrous and hydrous aluminium silicates material that could be used for the various chemical industries. Kaolin Clay has different functions and applications when used in different products such as those used in coatings, plastics, rubber, and cement products.

Kaolin in general refers to a naturally occurring mineral, kaolinite which is white or off-white in colour, in the form of hexagonally shaped, stacked platelets, of irregular orientation.

In commercial Kaolin grades, they are generally produced in the following ways:

  1. Air floatation – a simple and inexpensive process where the raw kaolin is ground, air floated to its various classes based on its size, and dried. Usually this type of production method would result in end products that are poor in colour, higher in residue, and tend to be abrasive.
  2. Water washed – is a more intensive and expensive production process as it involves more steps in its production process. It consist of blunging, slurring, sieving, grinding, centrifuging, classifying, treatment via chemicals or magnetic treating, concentrating and drying to achieve a certain level of purity, particle size, brightness and residue. Some grades may also undergo an attrition milling to delaminate or shear the stacked platelets into individual constituent plates. Even after drying the finished product still retain their crystalline bound water with about 14% of hydration in weight.
  3. Calcined – this type of clays are water washed grade which has an additional steps added to it. It is further ground and heated up to and above 650°C, and then ground again to break apart fused particles formed during the high temperature heating process. Calcine method includes:
    • Flash method – very fast heating using pneumatic conveyors
    • Soak methods – very long heating time as much as twenty to thirthy minutes using gravity with either of the below methods:
      • Vertical designs
      • Rotary designs
  4. Surfaced modified – uses the above processed calcined material as a substrate for further surface treatment. There are many types of surface treatment available and treatment types would depend on what kind application the intended product is used for. Treatments includes mercapto, amino or organofunctional silane treatments reacted on the kaolin surface and then later crosslinked with the target polymer type required. This kind of treatment would improve chemical bonding strength between the polymer and kaolin clay and achieve superior property requirement for the final product.

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