What is the calcination process of Liaoning kaolin?

What is the calcination process of Liaoning kaolin? Let's get to know.

The clay formed by the combination of kaolin and water will deform under external force. After the external force is removed, the deformation property, namely plasticity, can still be maintained. It is the basis of Liaoning kaolin calcination process and also the main technical index. Plasticity is usually expressed by plasticity index and plasticity index. Plasticity index refers to the liquid limit water content of kaolin minus the plastic limit water content, expressed as a percentage, that is, W plasticity index=100 (W liquid limit - W plastic limit). Plasticity index represents the molding performance of kaolin, which can be obtained by directly measuring the load and deformation of clay balls when crushed under pressure with a plastometer. The higher the plasticity index, the better the molding performance. The plasticity of kaolin can be divided into four grades.

Liaoning kaolin calcination process bonding refers to the combination of kaolin and non plastic raw materials to form a plastic clay mass with certain drying strength. The determination of adhesion is to add standard quartz sand (its mass composition is 0.25-0.15 particle size accounting for 70%, and 0.15-0.09mm particle size accounting for 30%) into kaolin. It can be judged according to the high sand content when the plastic mud mass can still be maintained and the flexural strength after drying. The more sand is added, the stronger the binding capacity of this kaolin is. Generally, the kaolin with strong plasticity has strong bonding ability.

The sintering property of Liaoning kaolin calcination process refers to that when the formed solid powder kaolin green body is heated to its melting point (generally above 1000), the material spontaneously fills the grain gap and densifies. The state where the porosity drops to a low value and the density reaches a large value is called sintering state, and the corresponding temperature is called sintering temperature. When heating continues, the liquid phase in the sample increases and the sample begins to deform. The temperature at this time is called the phase transition temperature. The interval between sintering temperature and transition temperature is called sintering interval. The sintering temperature and sintering range are important parameters for determining the blank formula and selecting the kiln type in the ceramic industry. Low sintering temperature and wide sintering range (100-150) are good materials. The sintering temperature and range can be controlled by mixing flux and different types of kaolin in proportion.

The sintering shrinkage of Liaoning kaolin calcination process refers to a series of physical and chemical changes (dehydration, decomposition, mullite formation, melting of fusible impurities, and the equality of glass to fill the interspace between particles) that cause product shrinkage during the sintering process of dry kaolin body. It can also be divided into linear shrinkage and volume shrinkage. As with drying shrinkage, excessive sintering shrinkage will easily lead to green body cracking. In addition, if a large amount of strain is added to the green body during baking, crystal transformation (cubic hexagonal) will occur, which will cause its volume expansion and reverse contraction.

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