Importance

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Abstract

A castable refractory composition for use in the production of cast refractory piece, which comprises 1 part by weight of a phosphoric acid solution (H.sub.3 PO.sub.4) having a concentration ranging from 40 to 85% and its primary acidic function partially neutralized by reaction with vermiculite; from 0.1 to 2.5 parts by weight of a mineral such as wollastonite that is refractory and of fibrous structure and may react with one part of the acidic functions of the phosphoric acid that are still free or not neutralized yet; from 0.1 to 2.5 parts by weight of another mineral such as serpentine, MgO or synthetic olivine, containing at least one cation that may react with another part of the acidic functions of the phosphoric acid that are still free or not saturated yet; and from 0.28 to 1.45 parts by weight of water, being provided that the more concentrated is the phosphoric acid solution, the higher is the amount of water to be present in the composition. When the composition according to the invention is processed in a mixer, it passes from a granular state to a plastic state, and then to a liquid state, without need for any external heating. At that time, the composition may be cast to produce refractory pieces that may be used up to 1000C..degree.. These pieces have very good thermal insulation characteristics, and in particular, a very good behaviour with respect to molten aluminum.

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First Claim