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US 3,983,215 AGranted
Process for preparing NaOH.3.5 H.sub.2 O crystals
AssigneeAjinomoto Co., Inc.
InventorsChuji Hirata, Yasunori Yokogawa, Tsutomu Tabira
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Abstract
NaOH.3.5 H.sub.2 O crystals are prepared by cooling a slurry of 32 to 34% aqueous NaOH solution containing NaOH.3.5 H.sub.2 O seed crystals to below the temperature for saturating the aqueous NaOH solution with respect to NaOH.3.5 H.sub.2 O and separating the precipitated crystals.
Claims9
A process for preparing NaOH.3.5 H.sub.2 O crystals, which comprises:
- cooling a slurry of 32 to 34% homogeneous aqueous NaOH solution and NaOH.3.5 H.sub.2 0 seed crystals at 4.degree. to 6.degree. C,
- continuously adding 38 to 40% homogeneous aqueous NaOH solution to the slurry at 4.degree. to 6.degree. C while maintaining the concentration of the aqueous NaOH solution at 32 to 34% NaOH;
- precipitating NaOH.3.5 H.sub.2 O crystals from said solution to form a slurry of said precipitated crystals in the solution;
- continuously removing a part of the produced slurry;
- and
- separating the precipitated NaOH.3.5 H.sub.2 O crystals therefrom.
3 more elements
A process for preparing NaOH.3.5 H.sub.2 O crystals, which comprises;
- adding a member selected from the group consisting of NaOH, H.sub.2 O, aqueous NaOH and mixtures thereof to an NaOH solution containing NaOH.3.5 H.sub.2 O seed crystals at a temperature of from 10.degree. to 0.degree. C, so as to adjust the concentration of NaOH in the liquid phase of said NaOH solution to from 32 to 34% NaOH ##EQU8## by weight;
- precipitating NaOH.3.5 H.sub.2 O crystals from said 32 to 34% NaOH solution;
- and
- separating said precipitated NaOH.3.5 H.sub.2 O crystals from said solution.
1 more element
A process for preparing NaOH.3.5 H.sub.2 O crystals, which comprises:
- cooling a slurry mixture of a homogeneous aqueous NaOH solution of 32 to 34% ##EQU9## by weight NaOH containing sodium chloride and NaOH.3.5 H.sub.2 O seed crystals to below the temperature for saturating said solution with respect to NaOH.3.5 H.sub.2 O;
- precipitating NaOH.3.5 H.sub.2 O crystals from said 32 to 34% NaOH solution;
- and
- separating said precipitated NaOH.3.5 H.sub.2 O crystals from said solution.
1 more element
Dependencies are inferred from the claim text.