Minerals (Category B)
Ball Clay is a highly plastic variety of clay of Kaolinite group like China clay and fire clay, but has less refractoriness. The chemical composition of ball clay is similar to that of China clay, except that the ball clay contains a large proportion of silica.
The main utility of ball clay lies in the plasticity, high bonding qualities and tensile strength. It is therefore, used in bled with non- - plastic to semi - plastics clays for obtaining requisite plasticity. It is added in various proportions for the preparation of body composition of various sanitary wares, bathtub tiles, porcelain, etc.
The BIS has prescribed the following specification (IS: 4589 - 1968) for ball clay for use in the ceramic industry: -
The material shall be in the form of lumps or power, free from any foreign matter and shall be highly plastic when wet. The lumps shall slake in water and from a smooth suspension when dispersed. The color of the material when fired at 1350o C shall be light gray or light cream and free from any specks or patches.