US 4,291,002 AGranted

Process for producing sodium carbonate from complex brines

AssigneeKerr-McGee Chemical Corporation

InventorsDonald S. Arnold, James L. Fairchild, Donald A. Nichols, Merlin D. Coe

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Abstract

A process for the production of sodium carbonate wherein sodium bicarbonate is recovered from a brine containing sodium carbonate by carbonation of the brine under controlled conditions. The sodium bicarbonate is crystallized from the carbonated brine in a multi-stage carbonating, cooling and crystallization process after which it is filtered to produce wet cake. The wet cake is subjected to predrying to provide a predried wet cake of a specified free moisture content and mixed with recycle light ash to provide a dryer feed of specified moisture content to alleviate problems of product fouling or plugging of the dryer. The light ash from the dryer then is bleached and subjected to recrystallization, screening, centrifuging and drying to provide a dried sodium carbonate possessing, after evaporation of the water of hydration and free moisture, less than 0.10 percent moisture and chemical and physical properties meeting commercial dense ash specifications.

Claims12

Dependent claims

A process for producing sodium carbonate comprising:

providing a brine containing sodium carbonate;
subjecting said brine to carbonation in carbonators to produce a hot carbonated brine slurry containing crystallized sodium bicarbonate;
maintaining the temperature level of said carbonated brine slurry in said carbonators within a range of from about 125 degrees F. to about 165 degrees F.;
passing said hot carbonated brine slurry to a multistage crystallizer to precipitate additional crystallized sodium bicarbonate in the slurry;
filtering said slurry to produce at least one stream comprising a sodium bicarbonate filter cake or wet cake;
withdrawing said filter cake or wet cake and subjecting said filter cake or wet cake to pre-drying by heating in a pre-dryer to produce without substantial decomposition a predried wet cake possessing a free moisture content of from about 6 percent to about 12 percent by weight of solids;
withdrawing said predried wet cake;
passing said predried wet cake to a mixer wherein said predried wet cake is mixed with a portion of an unbleached light ash produced by drying said predried wet cake in a dryer to form a mixture;
maintaining the mixing ratio of said predried wet cake and said unbleached light ash such that an amount greater than 110 percent by weight of the quantity of unbleached light ash which is stoichiometrically required to chemically bind all of the free moisture in said predried wet cake is introduced into said mixture;
withdrawing the mixture from the mixer;
passing said mixture to said dryer wherein said mixture is dried without substantial sticking of the mixture to the heat transfer surfaces of the dryer to produce said unbleached light ash and a dryer off gas;
withdrawing a portion of said unbleached light ash from the dryer and mixing said portion of unbleached light ash with said predried wet cake in the mixer to form said mixture;
withdrawing another portion of said unbleached light ash from the dryer and subjecting said portion to bleaching in a bleacher to remove organic impurities to produce a bleached light ash;
subjecting said bleached light ash to recrystallization and drying to produce recrystallized sodium carbonate;
and,
withdrawing and recovering said recrystallized sodium carbonate.

13 more elements

A process for producing sodium carbonate comprising:

providing a brine containing sodium carbonate;
subjecting said brine to carbonation in carbonators maintained at elevated temperature to provide a carbonated brine slurry containing crystallized sodium bicarbonate;
passing said carbonated brine slurry to a multistage crystallizer to precipitate additional crystallized sodium bicarbonate in the slurry;
filtering said slurry to produce at least one stream comprising a sodium bicarbonate filter cake or wet cake;
passing said filter cake or wet cake to a pre-dryer to produce a predried wet cake;
maintaining the temperature level in said pre-dryer at an elevated temperature to produce without substantial decomposition a predried wet cake possessing a free moisture content of from about 6 percent to about 12 percent by weight of solids;
passing said predried wet cake to a mixer wherein said predried wet cake is mixed with a portion of an unbleached light ash produced by drying the predried wet cake in a dryer to provide a dryer feed mixture;
maintaining the mixing ratio of said predried wet cake and unbleached light ash such that an amount greater than about 110 percent by weight of the quantity of unbleached light ash which is stoichiometrically required to chemically bind all of the free moisture in the predried wet cake is introduced into the mixer;
passing said dryer feed mixture to the dryer wherein said dryer feed mixture is dried without substantial sticking of the dryer feed mixture to the heat transfer surfaces of the dryer to produce said unbleached light ash;
withdrawing a portion of said unbleached light ash from said dryer and mixing said portion of unbleached light ash with the predried wet cake to provide said dryer feed mixture;
passing the remaining unbleached light ash in said dryer to a bleacher wherein organic contaminants are oxidized to produce bleached light ash;
passing said bleached light ash to a recrystallization and drying process to produce recrystallized sodium carbonate;
and,
recovering said recrystallized sodium carbonate.

11 more elements

Dependencies are inferred from the claim text.