Production of sodium carbonate

Claim 2

A process for the preparation of dense sodium carbonate from crude trona, containing an insoluble fraction, which has shortite therein, which comprises calcining the crude trona at a temperature and for a time sufficient to convert the sodium sesquicarbonate in the crude trona into sodium carbonate and provide anhydrous calcined crude trona, containing a soluble and an insoluble fraction in solid phase therein, introducing the soluble sodium carbonate fraction from said calcined crude trona in solid phase together with the insoluble fraction and an aqueous solvent containing at least 6.2 percent of sodium carbonate previously dissolved therein, into a dissolver, and forming an aqueous solution of the sodium carbonate in the presence of the insoluble solid phase fraction in said dissolver, separating said solution of sodium carbonate from the insoluble solid phase, removing entrained solids from said solution of sodium carbonate to provide a clear solution, evaporating said clear solution and recovering sodium carbonate monohydrate crystals therefrom and calcining said crystals to dense soda ash aNd recycling the mother liquor from said monohydrate crystals to the evaporators for further monohydrate crystal recovery therefrom, contacting said insoluble solid phase with an aqueous solvent to recover additional sodium carbonate solution therefrom and form an unsaturated solution of sodium carbonate containing at least 6.2 percent of sodium carbonate therein, separating said unsaturated solution from the insoluble phase, and discarding the insoluble phase and recycling said unsaturated sodium carbonate solution recovered from the insoluble phase to the dissolver and dissolving more sodium carbonate therein.

Claim 3

The process of claim 2 in which the anhydrous calcined crude trona is contacted initially with an aqueous solution of sodium carbonate containing in excess of 6.2 percent of sodium carbonate therein.

Claim 4

Process of preparing soda ash from crude trona having insolubles containing shortite therein, which comprises calcining the crude trona at a temperature and for a time sufficient to convert said crude trona into anhydrous crude sodium carbonate having insolubles therein, introducing the sodium carbonate content of said crude sodium carbonate in solid phase together with said insolubles and an aqueous solvent having in excess of 6.2 percent of sodium carbonate previously dissolved therein into a dissolver and forming an aqueous solution of said sodium carbonate in the presence of said insolubles, separating the said solution of sodium carbonate and the insolubles, recovering sodium carbonate monohydrate crystals from said sodium carbonate solution and calcining to produce soda ash, adding additional water to said insolubles and forming an unsaturated solution of sodium carbonate from the sodium carbonate contained in said insolubles, separating said unsaturated solution from the insolubles and using said unsaturated solution in the dissolving solution in said dissolver.

Claim 5

The process of claim 5 in which the crude trona is calcined at a temperature of about 200* C.

Claim 6

Process of producing dense soda ash from calcined crude trona which comprises dissolving the sodium carbonate values in calcined crude trona in water containing in excess of 6.2 percent of sodium carbonate dissolved therein to from a substantially saturated solution of sodium carbonate while the insolubles in said calcined crude trona remain suspended in the dissolving solution, separating the insolubles from the dissolved sodium carbonate and recovering sodium carbonate monohydrate crystals from said dissolved sodium carbonate and calcining to produce soda ash, adding makeup water to the insolubles and recovering additional sodium carbonate solution having in excess of 6.2 percent of sodium carbonate therein from the insolubles, separating the insolubles from said additional sodium carbonate solution and using said additional sodium carbonate solution to dissolve the sodium carbonate values in calcined crude trona.

Claim 7

Process for producing dense sodium carbonate from crude trona containing insolubles therein which comprises calcining the crude trona to convert the crude trona into crude sodium carbonate containing insolubles therein, dissolving the sodium carbonate values in said crude sodium carbonate in the presence of said insolubles in a countercurrent unsaturated dissolving liquor stream to produce a saturated solution of sodium carbonate containing said insolubles, separating said solution into a saturated stream of sodium carbonate and a stream of insolubles, clarifying said saturated stream of sodium carbonate and evaporating and recovering sodium carbonate monohydrate crystals therefrom and calcining to produce soda ash, recirculating the mother liquor from said sodium carbonate monohydrate crystals to the evaporator circuit to recover more sodium carbonate monohydrate crystals therefrom, flowing said stream of insolubles to a washing and diluting station, diluting and washing said insolubles with fresh incoming water to recover additional sodiUm carbonate values therefrom and form an unsaturated solution of sodium carbonate, separating said unsaturated solution of sodium carbonate from said insolubles, discarding the insolubles and cycling said unsaturated solution of sodium carbonate countercurrent to the calcined crude sodium carbonate flow to dissolve more sodium carbonate values from said calcined trona therein.

Claim 8

The process of claim 8 in which the countercurrent stream of unsaturated sodium carbonate solution used to dissolve sodium carbonate values from said crude sodium carbonate has in excess of 6.2 percent of sodium carbonate dissolved therein.

Claim 9

In a process for preparing refined soda ash from crude trona, calcining the crude trona at a temperature and for a time sufficient to convert the crude trona into crude sodium carbonate, mixing the crude sodium carbonate with an aqueous solution of sodium carbonate containing at least 6 percent sodium carbonate to form a substantially saturated solution of sodium carbonate, separating the saturated solution of sodium carbonate from the gangue solids, removing slimes from said saturated solution of sodium carbonate, evaporating said saturated solution to crystallize sodium carbonate crystals therefrom, separating the sodium carbonate crystals from the mother liquor and calcining to produce soda ash and recycling the mother liquor to the evaporator circuit.

Claim 10

The process of claim 10 in which the calcining temperature is between about 150* C. and about 800* C.

Claim 11

The process of claim 10 in which there is provided a multiple effect evaporating circuit for said evaporation of said saturated solution to crystallize sodium carbonate crystals therefrom and in which mother liquor from said sodium carbonate crystals is recycled to an evaporator for further evaporation of mother liquor for the recovery of further sodium carbonate crystals therefrom.

Claim 12

The process of claim 12 in which the evaporator to which the mother liquor from the sodium carbonate crystals is recycled is a single effect evaporator.

Claim 13

The process of claim 10 in which there is provided a multiple effect evaporating circuit for said evaporation of said saturated solution to crystallize sodium carbonate crystals therefrom and in which mother liquor from said sodium carbonate crystals is recycled to an evaporator in which all further evaporation of said recycled mother liquor for recovery of additional sodium carbonate crystals therefrom occurs.

Claim 14

The process of claim 14 in which there is separation of the sodium carbonate crystals from recycled mother liquor in mixture with the sodium carbonate crystals and mother liquor from the remainder of the said evaporating circuit.