Preparation of improved zeolites

Claim 1

A method for the production of improved zeolite A products which comprises reacting a calcined kaolin clay in a first digestion stage with a source of alkali metal in aqueous solution, the amount of alkali metal in the first digestion stage being about 15-40 wt. % of the total weight of alkali metal to be contained in the final zeolitic batch composition comprising the zeolite A product and liquid phase mother liquor, the digestion step being conducted at a temperature of about 40°-65° C and under conditions of high shear, said high shear comprising high dispersive agitation which has sufficient magnitude and intensity to establish high shear zones and intense turbulence and maintain each crystal in a discrete, segregated condition, thereafter gradually increasing the temperature of the resulting mixture to the range of about 80°-100° C while maintaining said conditions of high shear and adding the remaining 60-85 wt. % of the alkali metal to be contained in the final zeolitic batch composition while continuing the conditions of high shear, thereafter permitting the resulting mixture to cool and recovering the zeolitic A product from the mixture by separation from the mother liquor.

Claim 2

A method for the production of improved zeolite A products which comprises reacting a calcined kaolin clay in a first digestion stage with a source of alkali metal in aqueous solution, the amount of alkali metal in the first digestion stage being about 15-40 wt. % of the total weight of alkali metal to be contained in the final zeolitic batch composition comprising the zeolite A product and liquid phase mother liquor, the digestion step being conducted at a temperature of about 40°-65° C and under conditions of high shear, said high shear comprising high dispersive agitation which has sufficient magnitude and intensity to establish high shear zones and intense turbulence and maintain each crystal in a discrete, segregated condition, thereafter gradually increasing the temperature of the resulting mixture to the range of about 80°-100° C while maintaining said conditions of high shear and adding the remaining 60-85 wt. % of the alkali metal to be contained in the final zeolitic batch composition while continuing the conditions of high shear, thereafter permitting the resulting mixture to cool and recovering the zeolitic A product from the mixture by separation from the mother liquor.

Claim 15

A method for the production of improved zeolite A products which comprises calcining a kaolin clay to convert said clay to a metakaolin phase, slurrying said calcined clay in an aqueous medium for reaction with sufficient alkali metal hydroxide to form a zeolite A product of the following general formula: 1.0 ± 0.2 Me.sub.2 O : Al.sub.2 O.sub.3 : 1.85 ± 0.5 SiO.sub.2 : X H.sub.2 O wherein Me is alkali metal and X is 0 or an integer of up to 5; adding to said slurry of calcined clay about 15-40 wt. % of the total weight of alkali metal hydroxide to be contained in the final zeolitic composition which comprises the zeolite A product and liquid phase mother liquor, heating said mixture at a temperature of about 40°-65° C in a first digestion stage under conditions of high shear, said high shear comprising high dispersive agitation which has sufficient magnitude and intensity to establish high shear zones and intense turbulence and maintain each crystal in a discrete, segregated condition, thereafter gradually increasing the temperature of the resulting mixture to the range of 80°-100° C while maintaining the conditions of high shear, adding the remainder of the alkali metal hydroxide to the mixture to complete the alkali metal hydroxide addition, stopping the conditions of high shear and permitting the mixture to cool for a period of 1 to about 4 hours to obtain optimum crystal growth, separating the precipitated zeolite A product from the mother liquor containing sodium aluminate ions, and recycling the mother liquor containing the sodium aluminate ions to the first digestion stage of the next batch to supply sodium oxide ions to the initial mixture.

Claim 16

A method for the production of improved zeolite A products which comprises calcining a kaolin clay to convert said clay to a metakaolin phase, slurrying said calcined clay in an aqueous medium for reaction with sufficient alkali metal hydroxide to form a zeolite A product of the following general formula: 1.0 ± 0.2 Me.sub.2 O : Al.sub.2 O.sub.3 : 1.85 ± 0.5 SiO.sub.2 : X H.sub.2 O wherein Me is alkali metal and X is 0 or an integer of up to 5; adding to said slurry of calcined clay about 15-40 wt. % of the total weight of alkali metal hydroxide to be contained in the final zeolitic composition which comprises the zeolite A product and liquid phase mother liquor, heating said mixture at a temperature of about 40°-65° C in a first digestion stage under conditions of high shear, said high shear comprising high dispersive agitation which has sufficient magnitude and intensity to establish high shear zones and intense turbulence and maintain each crystal in a discrete, segregated condition, thereafter gradually increasing the temperature of the resulting mixture to the range of 80°-100° C while maintaining the conditions of high shear, adding the remainder of the alkali metal hydroxide to the mixture to complete the alkali metal hydroxide addition, stopping the conditions of high shear and permitting the mixture to cool for a period of 1 to about 4 hours to obtain optimum crystal growth, separating the precipitated zeolite A product from the mother liquor containing sodium aluminate ions, and recycling the mother liquor containing the sodium aluminate ions to the first digestion stage of the next batch to supply sodium oxide ions to the initial mixture.