Production of anhydrous sodium metasilicate in a fluidized bed

Claim 2

A PROCESS FOR PRODUCING UNIFORM SPHERICAL ANHYDROUS SODIUM METASILICATE PARTICLES OF HIGH ATTRITION RESISTANCE AND A MINIMUM DUST CONTENT, SAID PROCESS COMPRISING: A. PROVIDING A PLURALITY OF ANHYDROUS SODIUM METASILICATE PARTICLES N A FLUIDIZATION ZONE; B. CONTACTING SAID PARTICLES IN SAID FLUIDIZATION ZONE WITH AN UPWARDLY FLOWING STREAM OF HEATED AIR HAVING A SUPERFICIAL VELOCITY OF BETWEEN ABOUT 75 AND ABOUT 200 FEET PER MINUTE THEREBY PROVIDING A DILUTE UPPER PHASE OF INE PARTICULATE ANHYDROUS SODIUM METASILICATE AND A LOWER DENSE FLUIDIZED BED OF SAID PARTICLES OF ANHYDROUS SODIUM METASILICATE; AND

Claim 3

A process according to claim 1 wherein the particles in said fluidized bed are maintained at a temperature between about 125* and about 350*C.

Claim 4

The process of claim 2 wherein the aqueous sodium metasilicate liquor is sprayed in an upwardly direction into said lower dense fluidized bed.

Claim 5

The process of claim 2 wherein the aqueous sodium metasilicate liquor is sprayed horizontally into said dense fluidized bed.

Claim 6

A process according to claim 1 wherein said air prior to passing through said fluidization zone is heated to a temperature of about 250* to about 1,000*C.

Claim 7

A process according to claim 1 wherein said aqueous sodium metasilicate liquor contains between about 40 and 60% sodium metasilicate in water.

Claim 8

A process according to claim 1 wherein said aqueous sodium metasilicate liquor is prepared by digesting sand with NaOH at an elevated temperature between about 190* and about 240*C. and under a pressure between about 140 and about 325 psi prior to being injected into the fluidized bed.

Claim 9

A process according to claim 1 wherein the aqueous sodium metasilicate liquor contained less than 1.0% by weight of CO2.

Claim 10

A process for producing uniform spherical anhydrous sodium metasilicate particles of high attrition resistance, said process comprising: a. providing a plurality of anhydrous sodium metasilicate particles in a fluidization zone; b. contacting said particles in said fluidization zone with an upwardly flowing stream of air having a superficial velocity of between about 75 and about 200 feet per minute which is heated prior to passing through the zone to a temperature of about 250* C. to 1,000* C. thereby providing a dilute upper phase of fine particulate anhydrous sodium metasilicate and a lower dense fluidized bed of said particles of anhydrous sodium metasilicate; and c. contacting said particles in said fluidized bed with an aqueous sodium metasilicate liquor to produce crystallized anhydrous sodium metasilicate said aqueous sodium metasilicate liquor being sprayed directly into said fluidization zone below the meniscus separating said dilute upper phase and said lower dense fluidized bed.

Claim 11

A process for producing uniform spherical anhydrous sodium metasilicate particles of high attrition resistance, said process comprising: a. providing a plurality of anhydrous sodium metasilicate particles in a fluidization zone; b. contacting said particles in said fluidization zone with an upwardly flowing stream of air having a superficial velocity of between about 75 and about 200 feet per minute which is heated prior to passing through the zone to a temperature of about 250* C. to 1,000* C. thereby providing a dilute upper phase of fine particulate anhydrous sodium metasilicate and a lower dense fluidized bed of said particles of anhydrous sodium metasilicate; and c. contacting said particles in said fluidized bed with an aqueous sodium metasilicate liquor to produce crystallized anhydrous sodium metasilicate said aqueous sodium metasilicate liquor being sprayed directly into said fluidization zone below the meniscus separating said dilute upper phase and said lower dense fluidized bed.

Claim 12

A process according to claim 9 wherein the particles in said fluidized bed are maintained at a temperature between about 125* and about 350*C.

Claim 13

A process according to claim 9 wherein said aqueous sodium metasilicate liquor is prepared by digesting sand with NaOH at an elevated temperature between about 190* and about 240*C., and under a pressure between about 140 and about 325 psi prior to being injected into the fluidized bed.