BALL CLAY
Ball clay acts as binding agent and contributes to plasticity, workability and strength a pre-fired ceramic body. Some are highly valued for their fluid and casting properties, particularly in the manufacture of sanitaryware.
BBC Mines and Minerals have at its disposal ball clays with a range of different properties. By blending selected clays from different locations, we can provide high quality products for a range of ceramic applications.
Key Properties:
- High plasticity;
- High unfired strength;
- Highly controlled rheological properties;
- Controlled organic content;
- Controlled residue;
- Excellent workability
CHINA CLAY
Kaolin, also called china clay, soft white clay that is an essential ingredient in the manufacture of china and porcelain and is widely used in the making of Ceramics, paper, rubber, paint, and many other products.
Kaolin is mixed with water in the range of 20 to 35 percent, it becomes plastic (i.e., it can be molded under pressure), and the shape is retained after the pressure is removed. With larger percentages of water, the kaolin forms a slurry, or watery suspension.
In the manufacture of whiteware the kaolin is usually mixed with approximately equal amounts of silica and feldspar and a somewhat smaller amount of a plastic light-burning clay known as ball clay. These components are necessary to obtain the proper properties of plasticity, shrinkage, vitrification, etc., for forming and firing the ware. Kaolin is generally used alone in the manufacture of refractories.
Properties of our Kaolin clay in Ceramic Industry
- High fusion temperature
- White burning characteristics
- Particularly suitable for the manufacture of whiteware, porcelain, and refractories.
- The absence of any iron, alkalis, or alkaline earths in the molecular structure of kaolinite confers upon it these desirable ceramic properties.
FELDSPAR
Feldspar are used as a flux in the firing of ceramic ware. When a body is fired, the feldspar melts at a lower temperature than clay or silica, due to the presence of Na+, K+, or Ca2+ ions, and forms a malten glass which cause solid particles of clay to cling together. When the glass solidifies it gives strength and hardness to the body
The tendency to form a glass is strongly correlated to the viscosity of a Melt.
- In general, Molten feldspars are rather Viscous which is ascribed to the existence of polymerized silicon-aluminum -oxygen tetrahedra liquid.
- Despite lower melting point, the alkali feldspars produce much more viscous liquids than anorthite.
- In the case of albite this is interpreted as evidence for a higher degree Of polymerization in the melt.
- In the case of orthoclase it is due to the formation Of leucite, KAISi20„ crystals.
- In au cases glasses are produced under the cooling rates normally encountered Ceramic processing.
- Albite Melts at the tower temperature than orthoclase, but the addition of increases the Melting temperature of soda feldspar while decreasing that of potash feldspar (down to a Minimum at about 22% anorthite). Similarly a 50%: 50% Mixture Of albite and oråoclase Melts at a lower temperature than either end Member.
- Often Mixtures Of fluxes are employed to take advantage of eutectic Melting
- Lithium bearing Minerals are Often very effective fluxes used conjunction feldspar since such combinations form deep eutectics.
QUARTZ
- Quartz is a mineral
- Often quartz is clear to milky, With other color variation depending on what impurities are present in its formation
- It is mainly Composed of Silicon Dioxide
- It is the second most abundant mineral on earth after Feldspar
- Quartz is usually mined from veins within the rock
- Quartz is often used in glass making as well as decorative gemstones in jewelry
- Common gemstone names for Quartz are amethyst, Citrine, Jasper, rose quartz and smoky Quartz.