Industrial process for continuous production of zeolite A
First Claim
1. A process for the continuous preparation of zeolite A, suitable for use in detergents to soften calcium containing waters, having a constant homogeneity and quality wherein at least about 90 percent of the product has a granulometry within a range of 4 microns and a median diameter between about 1 and about 10 microns is characterized by:
- (a) instantaneously and continuously mixing at an elevated temperature in a reaction zone subjected to strong suction;
(i) a sodium silicate solution prepared from silica and NaOH which contains a minimal excess of NaOH and a SiO2 /Na2 O molar ratio ≧
2.8 to 1; and
containing about 45 to 105 g/l of NaOH and about 120 to 350 g/l of SiO2 ;
(ii) a sodium aluminate solution made from alumina and NaOH having an excess of NaOH solution, and containing about 80 to 110 g/l of NaOH and about 50 to 65 g/l of Al2 O3 ;
(b) precipitating the zeolite while continuously stirring the resulting solution at an elevated temperature and while restricting the volume of the reaction zone to insure that there is a local excess of dissolved alumina in relation to dissolved silica in the solution;
by;
(i) introducing the sodium silicate and sodium aluminate solutions into the suction zone created by a rapidly rotating turbine; and
(ii) adjacently surrounding the turbine with plates constructed and arranged to restrict the volume in which the above silicate and aluminate solutions are initially mixed;
(c) continuously removing the precipitated zeolite A and resulting liquor to a crystallization zone;
(d) continuously stirring the resultant precipitate and liquor in the crystallization zone at an elevated temperature until the desired crystallization is obtained;
(e) maintaining the concentration of the liquor in the crystallization zone between about 2 to 10 g/l of Al2 O3 ;
(f) removing the most dense or larger particles in suspension at the bottom of the crystallization zone; and
(g) recovering the zeolite A containing at least about 90 percent of the particles within a range of about 4 microns and having a median diameter between about 1 and 10 microns and an ion exchange capacity greater than 85 mg. Ca++ /g of dry product.
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Abstract
A process for continuous preparation of zeolite A of constant and homogeneous quality, consisting of instantly and continously mixing a sodium silicate solution and a sodium aluminate solution in the correct proportions and at an elevated temperature followed by transfer of the resulting slurry to a crystallization reactor. The product is recovered from the crystallization reactor washed and dried.
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Citations
6 Claims
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1. A process for the continuous preparation of zeolite A, suitable for use in detergents to soften calcium containing waters, having a constant homogeneity and quality wherein at least about 90 percent of the product has a granulometry within a range of 4 microns and a median diameter between about 1 and about 10 microns is characterized by:
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(a) instantaneously and continuously mixing at an elevated temperature in a reaction zone subjected to strong suction; (i) a sodium silicate solution prepared from silica and NaOH which contains a minimal excess of NaOH and a SiO2 /Na2 O molar ratio ≧
2.8 to 1; and
containing about 45 to 105 g/l of NaOH and about 120 to 350 g/l of SiO2 ;(ii) a sodium aluminate solution made from alumina and NaOH having an excess of NaOH solution, and containing about 80 to 110 g/l of NaOH and about 50 to 65 g/l of Al2 O3 ; (b) precipitating the zeolite while continuously stirring the resulting solution at an elevated temperature and while restricting the volume of the reaction zone to insure that there is a local excess of dissolved alumina in relation to dissolved silica in the solution;
by;(i) introducing the sodium silicate and sodium aluminate solutions into the suction zone created by a rapidly rotating turbine; and (ii) adjacently surrounding the turbine with plates constructed and arranged to restrict the volume in which the above silicate and aluminate solutions are initially mixed; (c) continuously removing the precipitated zeolite A and resulting liquor to a crystallization zone; (d) continuously stirring the resultant precipitate and liquor in the crystallization zone at an elevated temperature until the desired crystallization is obtained; (e) maintaining the concentration of the liquor in the crystallization zone between about 2 to 10 g/l of Al2 O3 ; (f) removing the most dense or larger particles in suspension at the bottom of the crystallization zone; and (g) recovering the zeolite A containing at least about 90 percent of the particles within a range of about 4 microns and having a median diameter between about 1 and 10 microns and an ion exchange capacity greater than 85 mg. Ca++ /g of dry product. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification