Thursday, 10 October 2013

Quarrying & Processing of Porcelain Clay

Porcelain stone and kaolin are important raw materials in the production of porcelain. Pocelain stone is a stony material while kaolin is a clay material. Porcelain stone is usually grayish white. Kaolin is known as porcelain clay amongst the locals. The word kaolin came from a mountain called Kaolin Mountain, which translates to high hill. It is pure white, light yellow, light grey or rose when it contains impurities. Porcelain stones and kaolin have different ingredients and origin. As such, the methods of quarrying and processing different from each other.   
After quarrying, workers usually crack the mineral into pellets the size of eggs before grinding them to fine powder in mortars using water-powered trip-stamper. The powder then goes through the process of washing, precipitating, drawing off and bodying before it is made into blocks of clay like bricks called ‘The White Dunzi’. They are then used by workshops to compound porcelain clay.  This method of processing porcelain stone has a history as long as Jingdezhen itself and is still being used today. The owners usually clear away the raw materials in mortars and wash the clay at intervals and the water-powered trip-stampers are left to run the entire day. 

 Sketch map of washing Kaolin (clay)

Pic 1 

Pic 2
  Pic 1&2
The main tools for quarrying the porcelain stone and porcelain clay

Flow chart of washing powdered porcelain stone to make Dunzi

Pic 3       The trip-stampers are pounding hard on different mills

Pic 4        Above – The clay bed and settling basin
                Below – The clay bed

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