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The métakaolin
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VERSION FRANCAISE
TECHNOLOGY TRANSFER


Demeter Technologies wishes to inform businesses of the opportunity of the creation of industrial production units for the pozzolanic binder- metakaolin, which can be used in all fields of construction.

Flash calcination technology, developed by Demeter Technologies, allows local businesses, for a manageable investment, the opportunity to become a major player in the production of hydraulic binders.

Following the agreement of the installation of an industrial metakaolin production unit, the technology transfer between Demeter Technologies and the business is implemented.
Find more details on the Technology Transfer page.

 

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METAKAOLIN

Metakaolin has been used as a binder with lime in numerous buildings since ancient times :
"Long before Portland cement existed, the Romans used the pozzolanic properties of calcinated clay materials mixed with lime. The Pantheon in Rome can be seen today as a perfectly preserved example of this technique."

G. Escadeillas, F. Cassagnabère, C. Magniont, A. Tafraoui Université de Toulouse ; UPS/INSA ; LMDC (Laboratory of Materials and the Durability of Buildings)



What is metakaolin ?

Kaolin is a flaky, white clay rock, essentially composed of kaolinite. Kaolin is formed by hydrothermal or meteoric degradation of minerals, feldspathoids and other silicates.

This kaolin clay is ground and then calcinated at 750°C, which causes disorganisation of the crystalline structure : the end product is metakaolin. This has a pozzolanic reaction in the presence of lime (or Portlandite in concrete applications).
The calcination is brought about by a process developed by Demeter Technologies : it is Flash calcination, a new economical and environmentally sound technology.


2 methods of obtaining metakaolin

The traditional method : calcination in a fixed bed or more often in a rotary kiln. The clay is introduced in the form of balls and is calcinated for 5 hours at 750° C. The balls of kaolin are transformed into balls of metakaolin by a structural loss of water. These balls are then ground. This method leads to a great deal of wear and tear and high energy consumption.

The Flash method : The kaolin clay is ground and the fine particles are calcinated in a few seconds. This method, associated with energy recycling uses around 40% of the energy consumed in the traditional method. It also results in significant technical advantages in the end product.


The Pozzolanic principle

The clays possess a latent capacity to be transformed by calcination at a moderate temperature, into pozzolan with a similar nature to slag from a blast furnace and other fly ash of which the characteristics, the usage and the criteria of usage are known.

Among the numerous types of clay which exist, kaolinites are the best adapted  to this metamorphosis. Metakaolin, in fact, presents remarkable qualities, in particular hydraulic properties when combined with water and limestone, when the limestone is added directly or liberated by the cement during its hydration. This property was used by the Romans, who mixed limestone and bricks of ground clay for the production of mortars in the construction of their works. Smectites are also transformable in identical conditions, although metasmectite is less reactive in the short term, and is more energy intensive than metakaolin.

Well known and highly valued by industrial consumer and specialised laboratories, metakaolin is produced on a relatively modest scale in the world. This can be explained by the high production cost, due to the extremely energy intensive method of production.
Flash technology developed by Demeter Technologies allows for the product to be repositioned in the market and to make it into a binder suitable for mass consumption.

 
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