SI20636A - Method of formulating alkali metal salts - Google Patents

Abstract

Methodology for formulating sodium bicarbonate and potassium sulfate. In one embodiment, sodium sulfate and ammonium bicarbonate are reacted to form sodium bicarbonate with the remaining liquor or brine treated with sulfuric acid to remove carbonates with subsequent precipitation of potassium sulfate. A further embodiment employs ammonium bicarbonate, ammonia gas or carbon dioxide to precipitate sodium bicarbonate. The result of the methods is the production of high quality fertilizer and food grade sodium bicarbonate.

Description

AIRBORNE INDUSTRIAL MINERALS INC.,

Canada

METHOD FOR FORMING ALKALINE METAL SALTS

The field of technology

The present invention relates to a method for forming alkali metal salts, more particularly to the present invention relates to a method of generating sodium bicarbonate of sufficient quality for consumption and potassium sulfate of sufficient quality for fertilizer.

BACKGROUND OF THE INVENTION

With respect to the method for the formation of alkali metal salts, the known state is quite extensive. Sodium bicarbonate, for example, was prepared in as many different ways than was known. Nevertheless, previous units of action for the synthesis of bicarbonate were hampered by inefficient use of energy, which directly increased the cost of synthesis. An additional limitation to the use of known processes is the fact that they do not use the operating units required for salt preparation effectively.

Typically, a single high-quality product is designed, with associated by-products of insufficient quality for commercial use, or excessive investment would be required to make these by-products commercially viable.

A representative of the known state is U.S. Pat. No. 3,429,657, which was granted February 25, 1969, and the applicant was D'Arcy. The above source discusses a method for the recovery and production of sodium salts. According to the source, the brine carrying the potassium is reacted with sodium perchlorate to precipitate the potassium perchlorate. Potassium is removed by ion exchange with sodium and free potassium can then be combined with chloride, sulfate or nitrate, among others.

Industrial usability

The present invention is useful in the fertilizer industry.

Description of the invention

One of the purposes of one embodiment of the present invention is to provide a method for the production of sufficiently good quality sodium bicarbonate and potassium sulfate, characterized in that this method comprises the following steps:

a) obtaining a source of liquid sodium sulfate;

b) obtaining a source of ammonium bicarbonate;

c) contacting sodium sulfate and ammonium bicarbonate;

d) precipitation of sodium bicarbonate and formation of a liquid;

e) precipitating the sodium bicarbonate and forming the liquid by contacting the liquid from step d) with sodium sulfate;

f) saturation of the liquid from step e) with sodium sulfate; g) filtering solids from the liquid of step f);

h) bringing the liquid from step g) into contact with sulfuric acid to precipitate carbonates;

i) cooling the liquid from step h) to 0 ° C to form a Glauber salt precipitate;

j) heating the fluid from step i) to between 30 ° C and 40 ° C; and

k) precipitation of potassium sulphate by contacting the liquid from the step

j) with potassium chloride.

It is a further object of one embodiment of the present invention to provide an iso method for the formation of sufficiently high quality sodium bicarbonate and potassium sulphate, characterized in that the method consists of the following steps:

a) obtaining a source of liquid sodium sulfate;

b) obtaining a source of ammonium bicarbonate;

2o c) contacting sodium sulfate and ammonium bicarbonate;

d) precipitation of sodium bicarbonate and formation of liquid;

e) precipitating the sodium bicarbonate and forming the liquid by contacting the liquid from step e) with sodium sulfate;

f) saturating the liquid from step e) with anhydrous sodium sulfate;

g) filtering solids from the liquid of step f);

h) contacting the liquid of step g) with at least one of the following substances: ammonium bicarbonate, ammonium gas or carbon dioxide to precipitate sodium bicarbonate;

i) cooling the liquid from step h) to 0 ° C to form a precipitate of sodium bicarbonate and sodium sulfate; and

j) precipitation of potassium sulphate by contacting the liquid of step i) with potassium chloride.

It has been found that, after the formation of sodium bicarbonate, considerable success has been achieved in the removal of sodium sulphate in the form of Glauber salt and sodium bicarbonate by keeping the liquid at 0 ° C. The solubility of the Glauber salt in the system is observed by the phase diagram of ammonium sulfate - sodium sulfate. By increasing the amount of sodium sulfate in the bicarbonate ring by increasing the recycling of Glauber's salt, there is a tendency to reduce the solubility of bicarbonate and increase the efficiency of the process.

With regard to the conversion of the starting reagents to potassium sulfate, success in particular was achieved by maintaining the molar ratio of potassium and ammonium ions to five (5) or higher. This ratio allows for high conversion efficiency in the second stage of the process.

Short description of the pictures

Figure 1 is a flowchart showing the first part of one of the methods of the present invention;

Figure 1a shows the second part of the process shown in Figure 1; s Figure 1b shows the third part of the process shown in Figure 1;

Figure 2 is a flowchart showing the first part of a variation of the process of the present invention;

Figure 2a shows the second part of the process shown in Figure 2; and

Figure 2b shows the third part of the process shown in Figure 2.

Similar figures in the figures indicate similar elements.

Methods of carrying out the invention

Referring now to the drawings, the drawings 1 to 1b inclusive show the process of the first embodiment of the present invention.

The source of liquid sodium sulfate 10 dissolved in fresh water and centrate water 12, which is described below. The solution is stirred at 40 ° C in container 14 to achieve a specific gravity of 1.30. The solution is filtered in a filter 16, which may for example comprise a 5 micron filter. Solids

2o 18 is removed while the filtrate 20 is transferred to the first sodium bicarbonate crystallization vessel 27.

The starting materials - water, ammonia and carbon dioxide, all of which are numbered 24 - are reacted in vessel 22 to synthesize ammonium bicarbonate. The formed ammonium bicarbonate is centrifuged in centrifuge 26, the solid product being fed into the crystallization vessel 27. The recycle loop 28 recirculates the ammonium bicarbonate solids and the liquid into the reaction vessel 29. The result of the combination in vessel 29 is the formation of sodium bicarbonate. The mixture was filtered with a filter 30 and centrifuged. Sodium bicarbonate is washed with water in a container 32 and centrifuged in a centrifuge 34 and the solid is retained as sodium bicarbonate of sufficient quality to be used for nutrition. The fresh water is returned to the container 14.

io The liquid from filter 30 has a specific gravity of 1.25 and its contents include approximately 10.4% sodium sulfate, 17.1% ammonium sulfate, 8% sodium bicarbonate and excess ammonium bicarbonate to react with Glauber's salt (to be described in below). The liquid is reacted in vessel 36 at 40 ° C, the Glauber salt being formed in the cooling phase of the process discussed later to form sodium bicarbonate from excess ammonium bicarbonate in crystallization vessel 29. Alternatively, ammonium bicarbonate can be added to the second stage (container 36) in the form of a solid, a diluted solid or a solution. Solid sodium sulfate from source 41 is added to the liquid from vessel 36 in a container 40 to form a saturated sodium sulfate / ammonium sulfate solution. Sufficient ammonium bicarbonate may be present to complete the reaction in solution, but some may be added resulting in a liquid having a specific gravity of 1.285. The diluted solid from the vessel is filtered by filter 42. The sodium bicarbonate solids 48 are removed to the vessel 32 and the liquid 44 is further treated by additional separation of the sodium bicarbonate returned to the vessel 32. The liquid 44 is then discharged into the vessel 46 ( Figure 1A). The flow volume in the bicarbonate circuit can be controlled by evaporation of the purified sodium sulfate in the feed material to produce solid sodium sulfate to allow the saturation of the circuit.

Returning to Figure 1A, container 46 contains sulfuric acid to precipitate carbonate compounds. The liquids thus treated were cooled to 0 ° C in cooler 48 to obtain the Glauber salt and filtered in filter 50. The resulting Glauber salt was returned to the sodium bicarbonate crystallization vessel 36.

The filtrate contains 25.25% by weight of ammonium sulphate and up to 11% by weight of sodium sulphate and is fed into a container 52, heated to between 30 ° C and 40 ° C and combined with solids 65 from filter 66. This solution is transferred to a container 54 where solid potassium chloride is reacted to form 20% by weight of ammonium chloride solution, which also contains about 20.2% by weight of ammonium chloride, 6.7% by weight of potassium chloride, 4.9% by weight of sodium chloride, 2.3% by weight of (x) ₂ SO ₄ , where x = Na, K, and solid mixed crystals of potassium sulfate with 10% - 20% ammonium sulfate.

The solution is filtered on filter 56, the solid fraction containing by weight about 5% potassium chloride, 80% - 85% potassium sulfate and 10% 15% ammonium sulfate. The solid fraction in vessel 58 is combined with potassium chloride water and brine from vessel 60. The potassium solid is centrifuged and filtered in filter 62 and recrystallized with potassium chloride solution at 25 ° C. The remaining ammonium sulfate is converted to potassium sulfate. More than 98% of the potassium sulfate level can be reached.

s In further units of the process, the liquid or filtrate from the potassium sulfate stages and specifically from the filter 56 is treated according to the process units shown in Figure 1c. The liquid is evaporated off in a evaporator to concentrate the ammonium chloride liquid so that, after cooling in the solution, the potassium chloride and residual sulfates are minimized, io The solution is filtered with a filter 66 and the solid material 67 is recycled to the container 54. The filtrate which contains about 22% to 30% ammonium chloride, reacts with lime in reactor 68, with the released ammonia being recycled. The moldable calcium chloride can be fed into a stabilization vessel 70 or a scrubber 72, as intended for later use.

When the process of this first embodiment of the invention was thus described, an example of the process will now be described.

EXAMPLE 1

NEUTRALIZATION OF BICARBONATE

BEFORE THE POTASSIUM SULPHATE PROCEDURE

Initial Substances - 1 liter at 1.3 specific gravity 360 g / l Na ₂ SO ₄

Phase 1

Production of NaHCO ₃

Brine output at reaction completion:

130 g Na ₂ SO ₄ 10.4% Na ₂ SO ₄

213.8 g (NH ₄ ) ₂ SO ₄ 100 g NaHCO ₃ 907 g H? O

1350.8

41 ° C

17.1% (NH ₄ ) ₂ SO ₄ 1,250 spec. weighted at 0.95 I

8.0% NaHCO ₃ solution

In this way 172 g of NaHCO ₃ is obtained as a solid

Grade 2 consumption 55 g NH ₃ A) 25.07 g NH ₃ + 64.9 g CO ₂

142.5 g CO ₂ B) 51.2 g NH ₃ + 132.6 g CO ₂

Second LEVEL 0.95 I brine will dissolve the following:

-1010

A) 1 mol B) 2 moles At ₂ SO ₄ 10 H ₂ O At ₂ SO ₄ 10 H ₂ O (332 g) (644 g) 272 g Na ₂ SO ₄ 16.2% Na ₂ SO ₄ 414 g Na ₂ SO ₄ 20.7% Na ₂ SO ₄ 213.8 g of (NH _{4) 2} SO ₄ 12.8% (NH ₄ ) ₂ SO ₄ 213.9 g (NH ₄ ) ₂ SO ₄ 10.7% (NH ₄ ) ₂ SO ₄ 100 g NaHCO ₃ 5.9% NaHCO ₃ 100 g NaHCO ₃ 5.0% NaHCO ₃ 1087q H ₂ O 65.1% H ₂ O 1267q H ₂ O 63.4% H ₂ O 1672,8 1999 1,275 specific gravity and 1,313 I brine 1 1,300 specific gravity and 1.5 I brine

STAGE 2 Composition of the final solution

A) B) 167.3 g Na ₂ SO ₄ 10% On ₂ SO ₄ 200 g Na ₂ SO ₄ 10% On ₂ SO ₄ 311 g (NH _{4) 2} SO ₄ 18.9% (NH ₄ ) ₂ SO ₄ 412 g (NH _{4) 2} SO ₄ 20.2% (NH ₄ ) ₂ SO ₄ 131 g NaHCO ₃ 8% NaHCO ₃ 160 g NaHCO ₃ 8% NaHCO ₃ 1087 a H ₂ O 63.1% H ₂ O 1267 ah ₂ o 61.8% H ₂ O 1644.5 g of solution 2039 g of solution

-1111

Production of NaHCO ₃ 92.9 g Production 193.2 g NaHCO ₃ Specific gravity 1,265 and is obtained 1,285 specific gravity and 1.6 I is obtained 1.31 And brines brine NEUTRALIZATION OF BICARBONATES 412 g (NH _{4) 2} SO ₄ 200 g Na ₂ SO ₄ + 160 x 98 = 93.3 g H ₂ SO ₄ 160gNaHCO ₃ 84 (2) 1267 g H? O

2039 g (1.61)

1,285 specific gravity io It becomes:

412 g (NH ₄ ) ₂ SO ₄ 335 g Na2SO4 1267 g H? O

2014 g at 1,265 = (1,61) and it is necessary to add Na ₂ SO ₄ to saturate 1,30 specific gravity 1,61 x 1,30 = 2080

Therefore:

412 g (NH _{4) 2} SO ₄

2o 400 g Na ₂ SO ₄

-1212

1267 g 0? 0 2079 g total (1,61)

Cooling 412 g (NH _{4) 2} SO ₄ 28.7% 116 g Na ₂ SO ₄ 8.0% 907 g H _? About 1435 g of solution 63% Initial substances NH4CI 330,8 g 21.9 KCI 130 g 8,6% NaCI 94.7 g 6.3% x-SO4 50 3.3% HgO 907 g 1512 g 60.0 at 33% NH ₄ CI then: - 2.8% KCI then: -2.0% K ₂ SO ₄

Therefore: 330.8 = 1002 g .33

-1313

Evaporation burden = 907 - 623 = 284 g

0.79 t / t To ₂ SO ₄ add 0.51 to rinse

1,291 H ₂ O / 1 Na ₂ SO ₄

K ₂ SO ₄ reaction

a) K ₂ SO ₄ from (NH ₄ ) ₂ SO ₄ = 412 x 174 = 543 g

132

b) K ₂ SO ₄ from Na ₂ SO ₄ = 116x174 = 142g

142

c) losses of K ₂ SO ₄ - -43 g

TOTAL K ₂ SO ₄ 642 g

Recovery of KCI

a) KCI Temporarily Broken Reaction = 685 x 2 x 74 = 582 g

174

b) KCI lost due to restrictions = 50 g

c) therefore: need for KCI = 623 g

Utilization K _? SO ₄ = 642 x 100 = 93.7%

685

-1414

KCI conversion rate = 582 x 100 = 92.1%

632

FOUNDATION: One tonne of starting material Na ₂ SO ₄

Starting materials Product Phase One 0.1531 NH ₃ 0.396 t CO ₃ 2.52 t H ₂ O 0.481 NaHCOs Second phase 644 g Na ₂ SO ₄ 10 H ₂ O 0,142 t NH ₃ 0,368 t CO ₂ 0.53 t NaHCOs Bicarbonate neutralization + Na ₂ SO ₄ saturation 0,261H ₂ SO ₄ 0,18tNa ₂ SO ₄ filtered to produce clear brine cooler at 0 ° C - BTUji 1.8tNa ₂ SO ₄ 10 H ₂ O colder brine 1.14 t (NH ₄ ) ₂ SO ₄ 28.7% 0.32 t At ₂ SO ₄ 8.0% 2.52 at H, O 63% 3.99 t total KC1 = 1.76 t 1.78tK ₂ SO ₄ evaporation up to 33% NH ₄ CI 0.92 t NH ₄ CI brine 1.29 t / t Na ₂ SO ₄ 0.08 t KCI SOLID SUBSTANCES

-1515

0.051 K ₂ SO ₄ 1.73 t H? O 2.78 total 0.28 t KCI 0.08 t K7SO4 0.36 t recycling lime process at 85% away 0.29 t NH ₃ 0,571 CaO Brine: 0.955 CaCI2 0.08 t KCI 0.05 t K ₂ SO ₄ 1.73 t H ₂ O 2.815 t at 75 to 90 ° C

Turning now to Figures 2 to 2b, they schematically show an alternative flow chart. According to this reaction scheme, liquids are saturated with anhydrite prior to the production of sodium bicarbonate.

s In this embodiment, sodium bicarbonate is produced in crystallization unit 22 and generally undergoes similar steps as those shown in Figures 1 to 1b. The brine or filtrate is saturated with anhydrous sodium sulfate in vessel 36 and filtered with filter 38 to remove insoluble matter which is then disposed of. The filtrate from this process is reacted in vessel 80 with ammonium ioc bicarbonate. Alternatively, the filtrate can be reacted with ammonia or carbon dioxide to precipitate sodium bicarbonate. The solution was filtered with filter 82 and the sodium bicarbonate remained. The sodium bicarbonate is combined with the sodium bicarbonate from filter 30 and then washed, centrifuged and dried. These rates are not shown.

-1616

The residual filtrate has the following approximate composition by weight: 10% sodium sulfate, 24% ammonium sulfate and 8% sodium bicarbonate. The solution has a specific gravity of 1.285 at 40 ° C.

From this stage, the filtrate solution is cooled in cooler 84 to about 0 ° C to produce a filtrate containing by weight about 5% sodium sulfate, 28% ammonium sulfate and 6% sodium bicarbonate. The solution is filtered through filter 86, the precipitated sodium bicarbonate and sodium sulfate are recycled back to the bicarbonate crystallization vessel 32, while the filtrate in the vessel 88 is reacted with potassium chloride to io synthesize first grade potassium in a purity range of about 75% up to 90%. The result is high quality potassium sulphate which is highly rated. The product is washed with water at a conventional rinsing rate of 96, and the recyclate is discharged into a container 94.

The solution from filter 90 was evaporated in an evaporator 98 (Figure 2A) to concentrate the ammonium chloride liquid, minimizing potassium chloride and sulfates after cooling. The solution is filtered using a filter 100 whereby the precipitated potassium chloride and (x) SO ₄ , at which x = K, Na, is recycled into the container 88.

The filtrate from filter 100 containing ammonium chloride, potassium chloride and potassium 2o sulfate is taken to evaporator 102. Sodium bicarbonate supports the reaction and consequently the ammonia and carbon dioxide are released. These gases are then cleaned / treated using appropriate techniques.

The resulting calcium chloride is then discarded or sold.

-1717

EXAMPLE 2

NO BICARBONATE NEUTRALIZATION

Initial Substances - 1 liter at 1.3 specific gravity 360 g / l Na ₂ SO ₄

PHASE 1

Production of NaHCO ₃

Brine output at reaction completion:

130 g Na ₂ SO ₄ 10.4% Na ₂ SO ₄ 40 ° C

213.8 g (NH ₄ ) ₂ SO ₄ 100 g NaHCO ₃

907 g H? O

17.1% (NH ₄ ) ₂ SO ₄

1,250 spec. weighted at 0.95 I

8.0% NaHCO ₃ solution

1350,8

In this way, 172 g of NaHCO ₃ are obtained as a solid, and 55 g of NH ₃ are consumed

142.5 g CO ₂ are Na ₂ SO ₄ Resaturation: Brine will withstand 150 g Na ₂ SO ₄ . This brine is then filtered and introduced into the second stage NaHCO ₃ crystallizer.

-1818

INITIAL SUBSTANCE REACTION OUTPUT SALT PRODUCT 280 g Na ₂ SO ₄ 35.9 g NH ₃ 130 g Na ₂ SO ₄ 177 g NaHCO ₃ 213,8g (NH _{4) 2} SO ₄ 92.9 g CO ₂ 353 g (NH ₄ ) ₂ SO ₄ 100 g NaHCO ₃ 100g NaHCO ₃ 907 g H? O 907 q H _? Oh 1490,8 g 1490 g 1,151 at 1.32 1,285 specific specific weights heavier 1,151 th most common 23.7% (NH ₄ ) ₂ SO ₄

The outlet brine was then cooled to 0 ° C.

The composition of the brine is: 5.0% Na ₂ SO ₄ , which means 60 g Na ₂ SO ₄ precipitate as 136 g Na ₂ SO ₄ 10 H ₂ O, precipitate and remove 76 g H ₂ O.

Therefore: 907 - 76 = 831 g H ₂ O.

Brine composition at 0 ° C and specific gravity 1.26 70 g Na ₂ SO ₄ 353 g (NH ₄ ) ₂ SO ₄ 100 g NaHCO ₃ 831 g H? O

TOTAL 1354 g

-1919

About 1 liter of brine.

K2SO4

a) 70 g Na? SO ₄ x 174 = 85.8

142

b) 353 g (NH ₄ ) ₂ SO ₄ x 174 = 465.3 g

132

OUTPUT SALT:

283 g NH ₄ CI 21.9% 57 g NaCl 4,8% 119 g (KNaHCO ₃ ) 9.2% 831 g H ₂ O 1290

Heat to 33.0% g of NH ₄ CI.

Releasing NH ₃ and CO ₂ from the evaporator but NH ₄ CI solutes KCI but not NaCI. 15 The KCI is recovered in the same manner as described in Example 1.

FUNDAMENTAL: One tonne of starting material Na? SO ₄

-2020

Starting materials Product First phase 0.15 tNH ₃ 0.48 t NaHCO ₃ 0.396 t CO ₂ 2.52 t H ₂ O Second phase 0.10 t NH ₃ 0.49 t NaHCO ₃ 0.26 t CO ₃ 0.42 t Na ₂ SO ₄ cooled to 0 ° C 0.4 t Na ₂ SO ₄ 10 H ₂ O colder brine 0.19tNa ₂ SO ₄ 5% 0.98 t (NH ₄ ) ₂ SO ₄ 26% 0.28 t NaHCO ₃ 7.4% 2.31 t H? O 61.4% 3.76 t total KCI = 1.62 t 1.8tK ₂ SO ₄ evaporation up to 33% NH ₄ CI solids brine circuit control = 0.71 H ₂ O 0.98 t NH ₄ CI 0.28 t KCI rinsing = 0.5 t 0.08 t KCI 0.08 t K ₂ SO ₄ v evaporator 1.2 t H ₂ O / 1 Na ₂ SO ₄ 0.15 t NaCI 0.36 t 0.19 t NaCl from CO ₃ 1.57 t H ₂ O 2.97 t lime process at 85% 1.01 t CaCI ₂ efficiency 0.08 t KCI

-2121

0.61 tCaO 0.34 t NaCl 1.57 t H ₂ O 3.01 at 75 to 90 ° C

EXAMPLE 3 - NEUTRALIZATION OF BICARBONATE - NO EVAPORATION

AMMONIUM CHLORIDE

5 Solution omitted: from # 1 412 g (NH ₄ ) ₂ SO ₄ 335 g Na ₂ SO ₄ 1267 o H? O 2014 g at 1,265 = 1.60 I

Cooling to 0 ° C gives a filtered solution:

412 g (NH _{4) 2} SO ₄ 28.7% 116 g Na ₂ SO ₄ 8.0% 907 g H ₂ O 1435 g of solution

This brine was then heated to 25 ° C, with KCI solids added to produce K ₂ SO ₄ . The output brine from the K ₂ SO ₄ circuit has the following composition:

NH4CI 330.8 g 21.9% 20 KCI 130 g 8,6%

-2222

NaCI 94.7 g 6.3% x-SO ₄ 50 g 3.3% x = Na / K h? q 907 о 60

1512 g

This brine is then heated and reacted with lime to recover the ammonia and avoid the evaporator. The KCI attracts CaCI ₂ brine instead of being recovered in the evaporator. This represents a 15 to 20% loss of K on CaCI ₂ brine. KCI and CaCI ₂ brine can be reduced to as low as 1.0% by adding CaCI ₂ / KCI brine to solid Na ₂ SO ₄ . Potassium is efficiently collected as a syngenite precipitate (CaSO ₄ · K ₂ SO ₄ · x H ₂ O) at 0 to 100 ° C, with temperatures of 20 to 30 ° C being preferred so that the minimum solubility of SO ₄ is maintained and the reaction proceeds at a reasonable rate.

is CaCI ₂ Composition

343.3 g of CaCl2 22,5% 130 g KCI 8.5% 94.7 g NaCl 6.3% 50 gx SO ₄ 32.% (Na / K) 907 a H ₂ O 59.5% 1525 g 100%

-2323

140 g Per ₂ SO ₄ additives: outlet brine outlet cake

234.8 g CaCI ₂ 17.8% 15.25 g KCI 1.1% 31 Og CaSO ₄ »K ₂ SO. 209 g NaCl 15.9% + 100 g H ₂ O 50 gx SO ₄ 3.8% 807 61.3%

The outlet brine can be deposited in deep wells and the outlet cake can be mixed into the K ₂ SO ₄ product as a binder or further processed to remove CaSO ₄ .

The cake can be reacted with (NH ₄ ) ₂ HCO ₃ from the starting material of the process

NaHCO ₃ and CaSO ₄ reacted rapidly to produce brine (NH ₄ ) ₂ SO ₄ and K ₂ SO ₄ and a CaCI ₃ precipitate to be removed. (NHa) ₂ SO ₄ / K ₂ SO ₄ brine is recycled to a K ₂ SO ₄ crystallizer of the first stage.

Claims (15)

PATENT APPLICATIONS 1. A method for forming sodium bicarbonate of sufficient nutritional quality and potassium sulphate, characterized in that this method comprises the following steps: a) obtaining a source of liquid sodium sulfate; b) obtaining a source of ammonium bicarbonate to precipitate sodium bicarbonate; io c) contacting said sodium sulfate and said ammonium bicarbonate; d) precipitation of sodium bicarbonate and formation of liquid; e) filtering said sodium bicarbonate; f) saturation of the liquid from step e) with sodium sulfate; g) contacting said liquid with ammonium carbonate, ammonium gas or carbon dioxide to precipitate further sodium bicarbonate; h) filtering the precipitated sodium bicarbonate from step g); i) Combining sodium bicarbonate precipitates from steps e) and h) 2o and rinsing to produce sodium bicarbonate of sufficient quality for consumption; j) cooling the liquid from step i) to 0 ° C to form at least a Glauber salt precipitate; -2525 k) treating the liquid from step j) with sulfuric acid to convert the carbonate minerals to sulfate minerals and to release carbon dioxide gas; l) heating the fluid from step k) to between 30 ° C and 40 ° C; and 5 m) precipitation of potassium sulphate by contacting said liquid from step I) with potassium chloride. 2. The method of claim 1, wherein the method further comprises a step of separating the precipitated potassium sulfate and washing with potassium chloride. Method according to claim 2, characterized in that the method further comprises the step of treating the liquid from said separation step of the precipitated potassium sulphate with lime to release ammonium gas. 4. The method of claim 3, 2o, characterized in that the method further comprises the step of recycling said ammonium gas into step g). -2626 5. The method of claim 4, wherein the method further comprises the evaporation step of the filtrate of claim 4. s Method according to claim 1, characterized in that said sodium sulfate has a specific gravity at 40 ° C of between 1.30 and 1.34. io Method according to claim 1, characterized in that said liquid from step d) has a specific gravity of 1.25 and contains by weight 10.4% sodium sulfate, 17.1% ammonium sulfate, between 8% and 12% sodium bicarbonate and in excess of ammonium bicarbonate. A method according to claim 1, characterized in that said sodium sulfate from step e) contains Na ₂ SO ₄ · 10 H ₂ O. 20 Method according to claim 1, characterized in that said fluid of step f) has a specific gravity at 40 ° C of 1.285. -2727 10. The method of claim 1, wherein said fluid from step k) is a saturated liquid of sodium sulfate, ammonium sulfate and sodium bicarbonate. A method according to claim 1, characterized in that said potassium sulfate is obtained in a yield of at least 80%, with a purity of at least 98%. 12. A method for forming sodium bicarbonate of sufficient nutritional quality and potassium sulphate, characterized in that this method comprises the following steps: a) obtaining a source of liquid sodium sulfate; b) obtaining a source of ammonium bicarbonate; c) contacting said sodium sulfate and said ammonium bicarbonate; d) precipitation of sodium bicarbonate and formation of liquid; e) precipitating the sodium bicarbonate and forming the liquid by contacting the liquid from step d) with sodium sulfate; f) saturation of said liquid from step d) with sodium sulfate; g) filtering solids from said fluid from step e); -2828 h) contacting said liquid from step f) with sulfuric acid to precipitate carbonates; i) cooling said liquid from step h) to 0 ° C to form a Glauber salt precipitate; s j) heating said liquid from step I) to between 30 ° C and 40 ° C; and k) treating said liquid from step j) with potassium chloride to precipitate potassium sulfate; l) evaporating the liquid from step k) to recover the potassium in the recycling values to step k); and 10 m) drying said potassium sulfate. Method according to claim 12, characterized in that the method further comprises the step of treating the liquid remaining from is step I) with lime and ammonium chloride. 14. The method of claim 13, wherein the ammonium gas is released and recycled. 15. The method of claim 12, wherein -2929 that the potassium chloride solution used is recycled to step k).