Sodium aluminate
The aluminate of sodium is a inorganic chemicals of great industrial importance. It constitutes a source of Hydroxyde of aluminum used in a great number of technical applications. In form Anhydrous, it acts of a white crystalline solid, mixed Oxyde of Sodium and Aluminum, of Chemical formula NaAlO2, Na2O · Al2O3, or Na2Al2O4.
The sodium aluminate is produced industrially by dissolution of the aluminum hydroxide in a solution of Soude (NaOH). The aluminum hydroxide (Gibbsite) east dissolves in an aqueous NaOH solution with 25%, at a temperature close to the point of boiling. The use of a solution more concentrated welds some leads to a semi-solid product. The process must be implemented in a container in Nickel or Acier, and the solution containing the aluminum hydroxide must be maintained with boiling until the formation of a pasty product. The mixture is then cooled, which leads to the formation of a solid containing approximately 70% of NaAlO2. This solid is crushed, then the powder is dehydrated in a revolving kiln. The finished product contains approximately 90% of NaAlO2, as well as traces (~1%) of water and NaOH.
In the applications of water treatment, the sodium aluminate is used like additive for the water-softeners, like agent coagulant to facilitate the Floculation, and to eliminate the dissolved Silice. In the sector of construction, it is employed to accelerate the solidification of the Béton, mainly in the event of freezing. It is also used in the paper Industrie, for the manufacture of refractory bricks, the production of Alumine (...).
Safety
The sodium aluminate is very soluble in water, the formed solution being a strong base which reacts violently with the acids. The councils of precaution during the use are thus those of a corrosive substance.
See too
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Hydroxide of aluminum
External bonds
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international Card of safety