Chamotte is fired clay. The characteristics of chamottes depend on the clay chosen, the mixture and the firing conditions.
For the production of chamottes, exquisite clays are shredded, mixed with water and are than formed to a plastic body in a press. After cutting it into portions of 15 kg – 20 kg an automatic setting system stacks the clay bodies on tunnel kiln cars. After drying, the different qualities are fired in tunnel kilns between 1080 °C and 1300 °C.
Chamotte in lumps
Chamottes in lumps are defined clay mixtures that are fired in two gas tunnel kilns after an additional homogenisation in a double shaft mixer and clay cleaner. The production process allows a flexible arrangement on the tunnel kiln cars as well as a specific firing curve for obtaining ceramic properties, such as water absorption and coefficient of thermal expansion.
The firing process in the gas tunnel kiln creates a very constant chamotte. Important criterions for chamottes are:
- Thermal expansion
- Firing colour
After the firing process, the chamotte lumps are milled in an impact mill followed by a Kent mill. A low iron grinding by using a high power magnetic separator, even allows a reduction of low magnetic components. The following sieving divides the chamotte into different grain sizes, for example fractions of 0-0,5 mm or 0-1 mm.
Milled Chamotte is made by non-ferrous dry grinding of chamotte, classified according to their grain size. The technical facilities allow the production of specific grain compositions or of fractionated deliveries. Milled chamotte are a semi-finished product and therefore they cannot be used alone, so they are a component of:
- Casting bodies for sanitary ceramics and for the production of stove tiles
- Plastic bodies, for example bodies for the split tile production
- Creaton ceramic bodies for stove tiles and other large-sized ceramics