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AssigneeDegussa AG
InventorsClaas-Juergen Klasen, Birgit Bertsch-Frank, Thomas Lieser, Peter Schubert, Klaus Mueller
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The invention relates to a method for increasing the storage stability of sodium percarbonate (2 Na.sub.2 CO.sub.3.3 H.sub.2 O.sub.2) by coating with a sodium perborate. According to the present invention wet sodium percarbonate salt, obtained by reacting sodium carbonate with hydrogen peroxide in aqueous phase and separating the salt from the aqueous phase, is treated with a solution or suspension containing sodium perborate in a solid-liquid separator by a kind of displacement wash. In contrast to previously known methods, according to the present invention a greater storage stability is attained with smaller quantities of perborate coating.
A method for the preparation of stabilized sodium percarbonate formed of a sodium percarbonate core and a coating containing sodium perborate of the formula NaBO.sub. 2.H.sub.2 O.sub.2.nH.sub.2 O, wherein n is 0, 1, 2 or 3 comprising spraying a wet sodium percarbonate salt with 5 to 100 1 of the solution or suspension containing sodium perborate per 100 kg of the wet salt, the sodium perborate content of which, expressed as NaBO.sub.2.H.sub.2 O.sub.2 is from 15 to 450 g/l, and separating excess solution or suspension simultaneously or subsequently from solid.
A method for the preparation of stabilized sodium percarbonate formed of a sodium percarbonate core and a coating containing sodium perborate of the formula NaBO.sub. 2.H.sub.2 O.sub.2.nH.sub.2 O, wherein n is 0, 1, 2 or 3 comprising spraying a wet sodium percarbonate salt with 5 to 100 1 of the solution or suspension containing sodium perborate per 100 kg of the wet salt, the sodium perborate content of which, expressed as NaBO.sub.2.H.sub.2 O is from 15 to 450 g/l, and separating excess solution or suspension simultaneously or subsequently from solid, wherein said separating is carried out by a centrifuge.
A method for the preparation of stabilized sodium percarbonate comprising forming a sodium percarbonate core by reacting sodium carbonate with hydrogen peroxide in aqueous phase, crystallizing the resulting sodium percarbonate to obtain a wet sodium percarbonate having mother liquor adhering thereto, spraying said wet sodium percarbonate salt with 5 to 100 liters of a solution or suspension containing sodium perborate per 100 kg of said wet salt, the sodium perborate content of which, expressed as NaBO.sub.2.H.sub.2 O.sub.2 is from 15 to 450 g/l, displacing the mother liquor adhering to said wet sodium percarbonate salt by said solution or suspension of sodium perborate so as to completely coat said sodium percarbonate with a coating containing sodium perborate of the formula NaBO.sub.2.H.sub.2 O.sub.2.nH.sub.2 O, wherein n is 0, 1, 2 or 3.
Dependencies are inferred from the claim text.