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:
This application claims the benefit of U.S. Provisional Application No. 60/103,969, filed Oct. 13, 1998. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a method of formulating alkali earth salts and more particularly, the present invention relates to a method of gene rating food grade sodium bicarbonate and fertilizer grade potassium sulfate. 
     BACKGROUND OF THE INVENTION 
     A significant amount of prior art has been promulgated with respect to the formulation of alkali earth salts. Sodium bicarbonate, as an example, has been prepared in as many different ways as it has been known. Despite this fact, previous unit operations for bicarbonate synthesis have been hampered by inefficient energy use which results directly in increased synthesis costs. As a further limitation, known processes do not make efficient use of the unit operations involved in the preparation of salts. Typically, a single high quality product is formulated with concomitant byproduct formation of a quality inadequate for commercial purposes or that would require too substantial an investment to render them commercially viable. 
     Representative of the prior art is U.S. Pat. No. 3,429,657, issued Feb. 25, 1969, to D&#39;Arcy. The reference discusses a method for recovering and producing potassium salts. In the reference, a potassium bearing brine is reacted with sodium perchlorate to precipitate potassium perchlorate. The potassium is removed by ion exchange with sodium and the free potassium is then combined with chloride, sulfate, nitrate inter alia. 
     SUMMARY OF THE INVENTION 
     One object of the present invention is to provide a method of formulating food grade sodium bicarbonate and potassium sulfate, comprising the steps of: 
     a) providing a source of liquid sodium sulfate; 
     b) providing a source of ammonium bicarbonate; 
     c) contacting the sodium sulfate and the ammonium bicarbonate; 
     d) precipitating sodium bicarbonate and forming a liquor; 
     e) precipitating sodium bicarbonate and forming a liquor by contacting the liquor from step d) with sodium sulfate; 
     f) saturating the liquor from step e) with sodium sulfate; 
     g) filtering solids from the liquor of step f); 
     h) contacting the liquor from step g) with sulfuric acid to precipitate carbonates; 
     i) cooling the liquor from step h) to 0° C. to form Glauber&#39;s salt precipitate; 
     j) heating the liquor from step i) to between 30° to 40° C.; and 
     k) precipitating potassium sulfate by contacting the liquor from step j) with potassium chloride. 
     A further object of the present invention is to provide a method of formulating food grade sodium bicarbonate and potassium sulfate, comprising the steps of: 
     a) providing a source of liquid sodium sulfate; 
     b) providing a source of ammonium bicarbonate; 
     c) contacting the sodium sulfate and the ammonium bicarbonate; 
     d) precipitating sodium bicarbonate and forming a liquor; 
     e) precipitating sodium bicarbonate and forming a liquor by contacting the liquor from step e) with sodium sulfate; 
     f) saturating the liquor from step e) with anhydrous sodium sulfate; 
     g) filtering solids from the liquor of step f); 
     h) contacting the liquor from step g) with at least one of ammonium bicarbonate, ammonia gas or carbon dioxide to precipitate sodium bicarbonate; 
     i) cooling the liquor from step h) to 0° C. to a precipitate of sodium bicarbonate and sodium sulfate; and 
     j) precipitating potassium sulfate by contacting the liquor from step i) with potassium chloride. 
     It has been found that following the sodium bicarbonate formulation, significant success in cooling the liquor to 0° C. is realized for removing sodium sulfate as Glauber&#39;s salt and sodium bicarbonate. Glauber&#39;s salt solubility in the system is contemplated by the ammonium sulfate-sodium sulfate phase diagram. By increasing the sodium sulfate in the bicarbonate circuit with increased Glauber&#39;s salt recycle, there is a tendency to decrease the bicarbonate solubility and increase the process efficiency. 
     Regarding the conversion of the starting reagents to potassium sulfate, particular success has been encountered by maintaining a mole ratio of five (5) or greater for the potassium and ammonium ions. This ratio ensures high conversion efficiency in the second stage of the process. 
     Having thus described the invention, reference will now be made to the accompanying drawings illustrating preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a process flow diagram illustrating a first part of one process according to the present invention; 
     FIG. 1 a  illustrates a second part of the process illustrated in FIG. 1; 
     FIG. 1 b  illustrates a third part of the process illustrated in FIG. 1; 
     FIG. 2 is a is a process flow diagram illustrating a first part of a variation of the process according to the present invention; 
     FIG. 2 a  illustrates a second part of the process illustrated in FIG. 2; and 
     FIG. 2 b  illustrates a third part of the process illustrated in FIG.  2 . 
    
    
     Similar numerals in the figures denote similar elements. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, FIGS. 1 through 1 b  illustrate the process according to a first embodiment. 
     A source of liquid sodium sulfate  10  dissolved in fresh water and centrate water  12  discussed herein after. The solution is mixed in vessel  14  at 40° C. to a specific gravity of 1.30. The solution is filtered in filter  16  which, as an example, may comprise a 5 micron filter. The solids  18  are disposed of while the filtrate  20  is passed into a first sodium bicarbonate crystallization vessel  27 . 
     Feeds of water, ammonia and carbon dioxide all denoted by numeral  24  are reacted in vessel  22  in order to synthesize ammonium bicarbonate. Formulated ammonium bicarbonate is centrifuged in centrifuge  26 , with the solid product being passed into crystallization vessel  27 . A recycle loop  28  recirculates ammonium bicarbonate solids and liquor into reaction vessel  29 . The result of the combination in vessel  29  is the formulation of sodium bicarbonate. The mixture is filtered by filter  30  and centrifuged. The sodium bicarbonate is washed with water in vessel  32 , centrifuged in centrifuge  34  and the solid retained as food grade sodium bicarbonate. The wash water is returned to vessel  14 . 
     The liquor from filter  30  has a specific gravity of 1.25 with the contents including approximately 10.4% sodium sulfate, 17.1% ammonium sulfate, 8% sodium bicarbonate and excess ammonium bicarbonate for reaction with the Glauber&#39;s salt (discussed herein after). The liquor is reacted in a vessel  36  at 40° C. with Glauber&#39;s salt formulated in the cooling phase of the process, which will be discussed later, to produce sodium bicarbonate from the excess of ammonium bicarbonate from crystallization vessel  29 . Alternatively, the ammonium bicarbonate may be added to the second stage (vessel  36 ) as solid, slurry or solution. 
     To the liquor from vessel  36  is added to solid sodium sulfate from source  41  in vessel  40  to formulate a saturated liquor of sodium sulfate/ammonium sulfate. Sufficient ammonium bicarbonate may be present to complete the reaction is solution or some may be added to result in the liquor having a specific gravity of 1.285. The slurry from vessel  40  is filtered with filter  42 . The sodium bicarbonate solids  48  are passed to vessel  32  and the liquor  44  is further processed with additional separation of sodium bicarbonate, which is returned to vessel  32 . The liquor  44 , is then passed to vessel  46  (FIG.  1 A). Circuit volume from the sodium bicarbonate circuit can be controlled by evaporating the purified sodium sulfate in the feed to produce solid sodium sulfate to ensure circuit saturation. 
     Returning to FIG. 1A, vessel  46  contains sulfuric acid to precipitate carbonate compounds. The so treated liquor is cooled to 0° C. in chiller  48  to recover Glauber&#39;s salt and filtered in filter  50 . The recovered Glauber&#39;s salt is returned to the sodium bicarbonate crystallization vessel  36 . 
     The filtrate contains 25.25% by weight ammonium sulfate and up to 1% by weight sodium sulfate and is passed into a vessel  52  heated to between 30° C. and 40° C. and combined with solids  65  from filter  66 . This solution is passed into vessel  54  where solid potassium chloride is reacted therewith to formulate a 20% by weight solution of ammonium chloride also containing, by weight approximately, 20.2% ammonium chloride, 6.7% potassium chloride, 4.9% sodium chloride, 2.3% as (x) 2 SO 4 , where x=Na, K, and solid mixed crystals of potassium sulfate with 10%-20% ammonium sulfate. 
     The solution is filtered in filter  56 , with the solid fraction containing approximately by weight, 5% potassium chloride, 80%-85% potassium sulfate, 10%-15% ammonium sulfate. The solid fraction is combined in vessel  58  with water and potassium chloride brine from vessel  60 . The potassium sulfate solid is centrifuged and filtered in filter  62  and recrystallized with a solution of potassium chloride at 25° C. The remaining ammonium sulfate is converted to potassium sulfate. Grades of greater than 98% potassium sulfate are achievable. 
     In further unit operations, the liquor or filtrate from the potassium sulfate operations and specifically from filter  56  is processed in accordance with the unit operations set forth in FIG. 1 c . The liquor is evaporated in evaporator in order to concentrate the ammonium chloride liquor such that upon cooling the potassium chloride and residual sulphates are minimized in solution. The solution is filtered with filter  66  with the solid material  67  recycled to vessel  54 . The filtrate containing approximately 22% to 30% ammonium chloride is reacted with lime in reactor  68  with liberated ammonia recycled. The calcium chloride formed may be passed to a settler  70  or scrubber  72  depending on intended subsequent uses. 
     Having set forth the process according to this first embodiment, reference will now be made to an example of the process. 
     EXAMPLE 1 
     BICARBONATE KILL PRIOR TO POTASSIUM SULFATE PROCESS 
     Feed—1 liter @ 1.3 S.G. 360 g/l Na 2 SO 4    
     1st STAGE 
     Production of NaHCO 3    
     Brine Exit at reaction termination: 
     
       
         
               
               
               
               
               
             
               
               
             
               
               
               
             
           
               
                   
               
             
             
               
                 130 g 
                 Na 2 SO 4   
                 10.4% 
                 Na 2 SO 4   
                 40° C. 
               
               
                 213.8 g 
                 (NH 4 ) 2 SO 4   
                 17.1% 
                 (NH 4 ) 2 SO 4   
                 1.250 S.G. @ 0.95 l 
               
               
                 100 g 
                 NaHCO 3   
                  8.0% 
                 NaHCO 3   
                 solution 
               
               
                 907 g 
                 H 2 O 
               
               
                 1350.8 
               
             
          
           
               
                 This makes 172 g NaHCO 3  solids 
                 SECOND STAGE ESTIMATE 
               
             
          
           
               
                 consumes 
                   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   
               
               
                   
               
             
          
         
       
     
     2nd STAGE 0.95 l of brine will dissolve the following: 
     
       
         
               
               
             
               
               
               
               
             
               
               
               
             
               
               
             
               
               
               
               
             
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 A) 1 Moles Na 2 SO 4 10H 2 O (332 g) 
               
             
          
           
               
                   
                 272 
                 g Na 2 SO 4   
                 16.2% Na 2 SO 4   
               
               
                   
                 213.8 
                 g (NH 4 ) 2 SO 4   
                 12.8% (NH 4 ) 2 SO 4   
               
               
                   
                 100 
                 g NaHCO 3   
                  5.9% NaHCO 3   
               
               
                   
                 1087 
                 g H 2 O 
                 65.1% H 2 O 
               
               
                   
                 1672.8 
                   
               
             
          
           
               
                   
                 1.275 S.G.   and   1.313 l brine 
                   
               
             
          
           
               
                   
                 B) 2 Moles Na 2 SO 4 10H 2 O (644 g) 
               
             
          
           
               
                   
                 414 
                 g Na 2 SO 4   
                 20.7% Na 2 SO 4   
               
               
                   
                 213.9 
                 g (NH 4 ) 2 SO 4   
                 10.7% (NH 4 ) 2 SO 4   
               
               
                   
                 100 
                 g NaHCO 3   
                  5.0% NaHCO 3   
               
               
                   
                 1267 
                 g H 2 O 
                 63.4% H 2 O 
               
               
                   
                 1999 
               
             
          
           
               
                   
                 1.300 S.G.   and   1.5 l brine 
               
               
                   
                   
               
             
          
         
       
     
     2nd STAGE Final Solution Composition 
     
       
         
               
               
             
               
               
               
               
               
             
               
               
             
               
               
               
               
               
             
               
               
             
               
               
               
               
             
               
               
             
               
               
               
               
             
               
               
               
               
               
             
               
               
               
             
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 A) 
               
             
          
           
               
                   
                 167.3 
                 g Na 2 SO 4   
                 10% 
                 Na 2 SO 4   
               
               
                   
                 311 
                 g (NH 4 ) 2 SO 4   
                 18.9% 
                 (NH 4 ) 2 SO 4   
               
               
                   
                 131 
                 g NaHCO 3   
                 8% 
                 NaHCO 3   
               
               
                   
                 1087 
                 g H 2 O 
                 63.1% 
                 H 2 O 
               
               
                   
                 1644.5 
                 g Solution 
               
             
          
           
               
                   
                 Production of NaHCO 3  92.9 g 
               
               
                   
                 S.G. 1.265 and makes 1.31 l brine 
               
               
                   
                 B) 
               
             
          
           
               
                   
                 200 
                 g Na 2 SO 4   
                 10% 
                 Na 2 SO 4   
               
               
                   
                 412 
                 g (NH 4 ) 2 SO 4   
                 20.2% 
                 (NH 4 ) 2 SO 4   
               
               
                   
                 160 
                 g NaHCO 3   
                 8% 
                 NaHCO 3   
               
               
                   
                 1267 
                 g H 2 O 
                 61.8% 
                 H 2 O 
               
               
                   
                 2039 
                 g Solution 
               
             
          
           
               
                   
                 Production of 193.2 g NaHCO 3   
               
               
                   
                 S.G. 1.285 and makes 1.6 l of Solution 
               
               
                   
                 BICARB KILL 
               
             
          
           
               
                   
                  412 g (NH 4 ) 2 SO 4   
                   
                   
               
               
                   
                  200 g NaSO 4   160 g NaHCO 3  1267 g H 2 O 
                  + 
                 
                   
                     
                       
                         
                           
                             160 
                             
                               84 
                                
                               
                                 ( 
                                 2 
                                 ) 
                               
                             
                           
                           × 
                           98 
                         
                         = 
                         
                           93.3 
                            
                           
                               
                           
                            
                           g 
                            
                           
                               
                           
                            
                           
                             H 
                             2 
                           
                            
                           
                             SO 
                             4 
                           
                         
                       
                     
                             
                     
                         
                     
                   
                 
               
               
                   
                 2039 g (1.61) 
               
               
                   
                     1.285 S.G. 
               
               
                   
                 This becomes: 
               
               
                   
                  412 g (NH 4 ) 2 SO 4   
               
               
                   
                  335 g NaSO 4   
               
               
                   
                 1267 g H 2 O 
               
             
          
           
               
                   
                 2014 g @ 1.265 = (1.61) 
               
               
                   
                 must add Na 2 SO 4  to Saturation of 1.30 S.G. 
               
               
                   
                 1.61 × 1.30 = 2080 
               
               
                   
                 Therefore: 
               
               
                   
                  412 g (NH 4 ) 2 SO 4   
               
               
                   
                  400 g NaSO 4   
               
               
                   
                 1267 g H 2 O 
               
               
                   
                 2079 g total (1.61) 
               
               
                   
                 Cooling 
               
             
          
           
               
                   
                  412 g (NH 4 ) 2 SO 4   
                 28.7% 
                   
               
               
                   
                  116 g NaSO 4   
                  8.0% 
               
               
                   
                  907 g H 2 O 
                 63%   
               
               
                   
                 1435 g Solution 
               
               
                   
                 Feed to Evaporator 
               
             
          
           
               
                   
                 NH4C1 
                 330.8 g 
                 21.9 
                   
               
               
                   
                 KC1 
                 130 g 
                 8.6% 
               
               
                   
                 NaC1 
                 94.7 g 
                 6.3% 
               
               
                   
                 x-SO 4   
                 50   
                 3.3% 
               
               
                   
                 H 2 O 
                 907 g 
                 60.0 
               
               
                   
                   
                 1512 g 
               
             
          
           
               
                   
                 @ 33% NH 4 Cl 
                 then: −2.8% KCl 
               
               
                   
                   
                 then: −2.0% K 2 SO 4   
               
             
          
           
               
                   
                 
                   
                     
                       
                         
                           Therefore 
                            
                           
                             : 
                           
                            
                           
                               
                           
                            
                           
                             330.8 
                             .33 
                           
                         
                         = 
                         
                           1002 
                            
                           
                             
                                 
                             
                              
                             
                                 
                             
                           
                            
                           g 
                         
                       
                     
                             
                     
                         
                     
                   
                 
               
               
                   
                 Evaporation Load = 907 − 623 = 284 g 
               
               
                   
                 0.79 t/t Na 2 SO 4   
               
               
                   
                 add 0.5 t for washing 
               
               
                   
                 1.29 t H 2 O/t Na 2 SO 4   
               
               
                   
                 K 2 SO 4  Reaction 
               
               
                   
                 
                   
                     
                       
                         
                           
                             a 
                             ) 
                           
                            
                           
                               
                           
                            
                           
                             K 
                             2 
                           
                            
                           
                             SO 
                             4 
                           
                            
                           
                               
                           
                            
                           from 
                            
                           
                               
                           
                            
                           
                             
                               ( 
                               
                                 NH 
                                 4 
                               
                               ) 
                             
                             2 
                           
                            
                           
                             SO 
                             4 
                           
                         
                         = 
                         
                           
                             
                               412 
                               132 
                             
                             × 
                             174 
                           
                           = 
                           
                             543 
                              
                             
                               
                                   
                               
                                
                               
                                   
                               
                             
                              
                             g 
                           
                         
                       
                     
                             
                     
                         
                     
                   
                 
               
               
                   
                   
               
               
                   
                 
                   
                     
                       
                         
                           
                             b 
                             ) 
                           
                            
                           
                               
                           
                            
                           
                             K 
                             2 
                           
                            
                           
                             SO 
                             4 
                           
                            
                           
                               
                           
                            
                           from 
                            
                           
                               
                           
                            
                           
                             
                               N 
                                
                               a 
                             
                             2 
                           
                            
                           
                             SO 
                             4 
                           
                         
                         = 
                         
                           
                             
                               116 
                               142 
                             
                             × 
                             174 
                              
                             
                                 
                             
                              
                             
                                     
                             
                           
                            
                           
                               
                           
                           = 
                           
                             142 
                              
                             
                               
                                   
                               
                                
                               
                                   
                               
                             
                              
                             g 
                           
                         
                       
                     
                             
                     
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                       
                         
                           
                             
                               
                                 
                                   
                                     
                                       
                                         
                                           
                                             
                                               
                                                 c 
                                                 ) 
                                               
                                                
                                               
                                                   
                                               
                                                
                                               Losses 
                                                
                                               
                                                   
                                               
                                                
                                               of 
                                                
                                               
                                                   
                                               
                                                
                                               
                                                 K 
                                                 2 
                                               
                                                
                                               
                                                 SO 
                                                 4 
                                               
                                             
                                           
                                           
                                             
                                                 
                                             
                                           
                                           
                                             
                                               = 
                                               
                                                 
                                                   
                                                     - 
                                                     43 
                                                   
                                                    
                                                   
                                                       
                                                   
                                                    
                                                   g 
                                                 
                                                 _ 
                                               
                                             
                                           
                                         
                                         
                                           
                                             
                                                 
                                             
                                           
                                           
                                             
                                               
                                                   
                                               
                                                
                                               
                                                 TOTAL 
                                                  
                                                 
                                                     
                                                 
                                                  
                                                 
                                                   K 
                                                   2 
                                                 
                                                  
                                                 
                                                   SO 
                                                   4 
                                                 
                                               
                                             
                                           
                                           
                                             
                                               
                                                   
                                               
                                                
                                               
                                                 642 
                                                  
                                                 
                                                     
                                                 
                                                  
                                                 g 
                                               
                                             
                                           
                                         
                                       
                                     
                                   
                                 
                               
                             
                           
                            
                           
                               
                           
                            
                         
                          
                         
                             
                         
                       
                     
                             
                     
                         
                     
                   
                 
               
               
                   
                   
               
               
                   
                 KCl Recovery 
               
               
                   
                 
                   
                     
                       
                         
                           
                             a 
                             ) 
                           
                            
                           
                               
                           
                            
                           KCl 
                            
                           
                               
                           
                            
                           intermig 
                            
                           
                               
                           
                            
                           reaction 
                         
                         = 
                         
                           
                             
                               685 
                               174 
                             
                             × 
                             2 
                             × 
                             74 
                           
                           = 
                           
                             582 
                              
                             
                                 
                             
                              
                             g 
                           
                         
                       
                     
                             
                     
                         
                     
                   
                 
               
               
                   
                   
               
               
                   
                 b) KCl lost to tails = 50 g 
               
               
                   
                 c) Therefore : KCl need = 632 g 
               
               
                   
                   
               
               
                   
                 
                   
                     
                       
                         
                           
                             K 
                             2 
                           
                            
                           
                             SO 
                             4 
                           
                            
                           
                               
                           
                            
                           yield 
                         
                          
                         
                             
                         
                         = 
                         
                           
                             
                               642 
                               685 
                             
                             × 
                             100 
                           
                           = 
                           
                             93.7 
                              
                             % 
                           
                         
                       
                     
                             
                     
                         
                     
                   
                 
               
               
                   
                   
               
               
                   
                 
                   
                     
                       
                         
                           KCl 
                            
                           
                               
                           
                            
                           Conversion 
                            
                           
                               
                           
                            
                           Efficiency 
                         
                         = 
                         
                           
                             
                               582 
                               632 
                             
                             × 
                             100 
                           
                           = 
                           
                             92.1 
                              
                             % 
                           
                         
                       
                     
                             
                     
                         
                     
                   
                 
               
               
                   
                   
               
             
          
         
       
     
     BASIS: One Tonne of Na 2 SO 4  Feed 
     
       
         
               
               
             
               
             
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
             
               
               
               
             
           
               
                   
               
               
                 Inputs 
                 Product  
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 First Stage 
               
             
          
           
               
                 0.153 t NH 3   
                 0.48 t NaHCO 3   
               
               
                 0.396 t CO 3   
               
               
                  2.52 t H 2 O 
               
               
                 Second Stage 
               
               
                   644 g Na 2 SO 4 10H 2 O 
                 0.53 t NaHCO 3   
               
               
                 0.142 t NH 3   
               
               
                 0.368 t CO 2   
               
               
                 Bicarb Kill + Na 2 SO 4  Saturation 
                 Filter to Produce clear brine 
               
               
                 0.26 t H 2 SO 4   
               
               
                 0.18 t Na 2 SO 4   
               
               
                 Cooler to 0° C.   -BTU&#39;s 
                  1.8 t Na 2 SO 4 10H 2 O 
               
             
          
           
               
                 Cooler brine 
                 1.14 t (NH 4 ) 2 SO 4   
                 28.7% 
               
               
                   
                 0.32 t Na 2 SO 4   
                  8.0% 
               
               
                   
                 2.52 gt H 2 O 
                 63% 
               
               
                   
                 3.99 t Total 
               
             
          
           
               
                 KC1 = 1.76 t 
                 1.78 t K 2 SO 4   
               
             
          
           
               
                 Evaporation to 33% NH 4 Cl 
                 0.92 t NH 4 Cl brine 
                   
               
               
                 1.29 t/t Na 2 SO 4   
                 0.08 t KCl 
                 SOLIDS 
               
               
                   
                 0.05 t K 2 SO 4   
                 0.28 t KCl 
               
               
                   
                 1.73 t H 2 O 
                 0.08 t K 2 SO 4   
               
               
                   
                 2.78 Total 
                 0.36 t Recycle 
               
             
          
           
               
                 Lime Process @ 85% off 
                   
               
             
          
           
               
                 0.57 t CaO 
                 0.29 t NH 3   
                   
               
               
                   
                 Brine: 
                 0.955 CaCl 2   
               
               
                   
                   
                  0.08 t KCl 
               
               
                   
                   
                  0.05 t K 2 SO 4   
               
               
                   
                   
                  1.73 t H 2 O 
               
               
                   
                   
                 2.815 t @ 75 to 90° C. 
               
               
                   
               
             
          
         
       
     
     Turning to FIGS. 2 through 2 b , an alternative processing scheme is schematically depicted. In this reaction scheme, prior to the production of sodium bicarbonate, the liquors are saturated with anhydrite. 
     In this embodiment, sodium bicarbonate is produced in crystallization unit  22  and undergoes generally similar steps as set forth for FIGS. 1 through 1B. The brine or filtrate is saturated with anhydrous sodium sulfate in vessel  36  and filtered with filter  38  to remove insolubles which are discarded. The filtrate from this operation is reacted with ammonium bicarbonate in vessel  80 . As an alternative, the filtrate could be reacted with ammonia or carbon dioxide to precipitate the sodium bicarbonate. The solution is filtered with filter  82  and the sodium bicarbonate remains. The latter is combined with the sodium bicarbonate from filter  30  and then washed, centrifuged and dried. These steps are not shown. 
     The filtrate remaining has a composition of approximately, on a by weight basis, 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 a chiller  84  to approximately 0° C. in order to produce a filtrate containing approximately, on a by weight basis 5% sodium sulfate, 28% ammonium sulfate and 6% sodium bicarbonate. The solution is filtered with filter  86  and precipitated sodium bicarbonate and sodium sulfate are recycled back to the bicarbonate crystallization vessel  32 , while the filtrate is reacted with potassium chloride in vessel  88  to synthesize first stage potassium sulfate in a purity range of about 75% to 90%. The solid potassium sulfate is repulped with potassium chloride brine from vessel  92  in vessel  94 . This results in high quality, high grade potassium sulfate. The product is washed with water in a conventional washing stage  96  with recycle to vessel  94 . 
     The solution from filter  90  is evaporated in evaporator  98  (FIG. 2A) to concentrate ammonium chloride liquor whereby upon cooling the potassium chloride and sulfates are minimized. The solution is filtered using filter  100  with the precipitated potassium chloride and (x)SO 4 , where x=K, Na, recycled to vessel  88 . 
     The filtrate from filter  100  containing ammonium chloride, potassium chloride and potassium sulfate is passed into evaporator  102 . The sodium bicarbonate backs the reaction and as a result, ammonia and carbon dioxide are released. These gases are then scrubbed/handled using suitable techniques. The calcium chloride generated is then discarded or sold. 
     EXAMPLE 2 
     NO BICARBONATE KILL 
     Feed—1 liter @ 1.3 S.G. 360 g/l Na 2 SO 4    
     1 st STAGE 
     Production of NaHCO 3    
     Brine Exit at reaction termination: 
     
       
         
               
               
               
               
             
               
             
           
               
                   
               
             
             
               
                 130 
                 g Na 2 SO 4   
                 10.4% Na 2 SO 4   
                 40° C. 
               
               
                 213.8 
                 g (NH 4 ) 2 SO 4   
                 17.1% (NH 4 ) 2 SO 4   
                 1.250 S.G. @ 0.95 l 
               
               
                 100 
                 g NaHCO 3   
                  8.0% NaHCO 3   
                 solution 
               
               
                 907 
                 g H 2 O 
               
               
                 1350.8 
                   
               
             
          
           
               
                 This makes 172 g NaHCO 3  solids 
               
               
                 consumes   55 g NH 3   
               
               
                      142.5 g CO 2   
               
               
                   
               
             
          
         
       
     
     Resaturation with Na 2 SO 4 : brine will hold 150 g Na 2 SO 4 . This brine is then filtered and fed to the second stage NaHCO 3  crystallizer. 
     
       
         
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
             
           
               
                   
               
               
                   
                 REAC- 
                   
                 PRO- 
               
               
                 FEED 
                 TION 
                 EXIT BRINE 
                 DUCT  
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 280 
                 g Na 2 SO 4   
                 35.9 g NH 3   
                 130 
                 g Na 2 SO 4   
                 177 g 
               
               
                 213.8 
                 g (NH 4 ) 2 SO 4   
                 92.9 g CO 2   
                 353 
                 g (NH 4 ) 2 SO 4   
                 NaHCO 3   
               
               
                 100 
                 g NaHCO 3   
                   
                 100 
                 g NaHCO 3   
               
               
                 907 
                 g H 2 O 
                   
                 907 
                 g H 2 O 
               
               
                 1490.8 
                 g 
                   
                 1490 
                 g 
               
               
                 1.151 
                 @ 1.32 S.G. 
                   
                 1.285 
                 S.G. 
               
               
                   
                   
                   
                 1.151 
                   
               
             
          
           
               
                   
                 23.7% 
                 (NH 4 ) 2 SO 4   
               
               
                   
                   
               
             
          
         
       
     
     The exit brine is then cooled to 0° C. 
     Brine composition is: 5.0% Na 2 SO 4  which mean 60 g Na 2 SO 4  precipitates as 136 g of Na 2 SO 4 10H 2 O precipitate and remove 76 g of H 2 O. 
     Therefore: 907−76=831 g H 2 O 
     Brine composition @ 0° C. and 1.26 S.G. 
     70 g Na 2 SO 4    
     353 g (NH 4 ) 2 SO 4    
     100 g NaHCO 3    
     
       831g H 2 O 
     
     
       1354g TOTAL 
     
     About 1 liter brine                K   2          SO   4                     a   )                       70                 g                   Na   2          SO   4       142     ×   174     =   85.8                   b   )                       353                 g                     (     NH   4     )     2          SO   4       132     ×   174     =     465.3                 g                                  
     EXIT BRINE: 
     
       
         
               
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 283 
                 g NH 4 Cl 
                 21.9% 
                   
               
               
                   
                 57 
                 g NaCl 
                  4.8% 
               
               
                   
                 119 
                 g (KNaHCO 3 ) 
                  9.2% 
               
               
                   
                 831 
                 g H 2 O 
               
               
                   
                 1290 
               
               
                   
                   
               
             
          
         
       
     
     Boil up to 33.0% NH 4 Cl. 
     Release of NH 3  and CO 2  from evaporator but NH 4 Cl salts out KCl and not the NaCl. KCl is recovered same as in Example 1. 
     BASIS: One Tonne Na 2 SO 4  Feed 
     
       
         
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 INPUTS 
                 PRODUCT 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 First Stage 
                 0.15 
                 t NH 3   
                 0.48 
                 t NaHCO 3   
               
               
                   
                 0.396 
                 t CO 2   
               
               
                   
                 2.52 
                 t H 2 O 
               
               
                 Second Stage 
                 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 of Na 2 SO 4 10H 2 O 
               
             
          
           
               
                 Cooler Brine 
                 0.19 
                 t Na 2 SO 4   
                 5% 
                   
               
               
                   
                 0.98 
                 t (NH 4 ) 2 SO 4   
                 26% 
               
               
                   
                 0.28 
                 t NaHCO 3   
                 7.4% 
               
               
                   
                 2.31 
                 t H 2 O 
                 61.4% 
               
               
                   
                 3.76 
                 t Total 
               
             
          
           
               
                 KCl 
                 1.62 
                 t 
                 1.8 
                 t K 2 SO 4   
               
             
          
           
               
                 Evaporation to 33% 
                   NH 4 Cl 
                 Brine 
                 Solids 
               
             
          
           
               
                 Circuit Control = 
                 0.7 
                 t H 2 O 
                 0.98 
                 t NH 4 Cl 
                 0.28 
                 t KCl 
               
               
                 Washing = 
                 0.5 
                 t 
                 0.08 
                 t KCl 
                 0.08 
                 t K 2 SO 4   
               
               
                 To evaporator 
                 1.2 
                 t H 2 O/t Na 2 SO 4   
                 0.15 
                 t NaCl 
                 0.36 t 
               
               
                   
                   
                   
                 0.19 
                 t NaCl from CO 3   
               
               
                   
                   
                   
                 1.57 
                 t H 2 O 
               
               
                   
                   
                   
                 2.97 
                 t 
               
             
          
           
               
                 Lime Process @ 85% efficiency 
                 1.01 
                 t CaCl 2   
               
               
                 0.61 t CaO 
                 0.08 
                 t KCl 
               
               
                   
                 0.34 
                 t NaCl 
               
               
                   
                 1.57 
                 t H 2 O 
               
               
                   
                 3.0 
                 t @ 75-90° C. 
               
               
                   
               
             
          
         
       
     
     EXAMPLE 3 
     BICARBONATE KILL—NO EVAPORATION OF AMMONIUM CHLORIDE 
     
       
         
               
               
             
               
               
               
             
               
               
             
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Feed Solution: from #1 
               
             
          
           
               
                   
                 412 
                 g (NH 4 ) 2 SO 4   
               
               
                   
                 335 
                 g Na 2 SO 4   
               
               
                   
                 1267 
                 g H 2 O 
               
               
                   
                 2014 
                 g @ 1.265 = 1.60 λ 
               
             
          
           
               
                   
                 Cooling to 0° C. yields a filtered solution of: 
               
             
          
           
               
                   
                 412 
                 g (NH 4 ) 2 SO 4   
                 28.7% 
               
               
                   
                 116 
                 g Na 2 SO 4   
                  8.0% 
               
               
                   
                 907 
                 g H 2 O 
               
               
                   
                 1435 
                 g solution 
               
               
                   
                   
               
             
          
         
       
     
     This brine is then heated to 25° C. where KCl solid is added to produce K 2 SO 4 . The exit brine from the K 2 SO 4  circuit has the following composition: 
     
       
         
               
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 NH 4 Cl 
                 330.8 g 
                 21.9% 
                   
               
               
                   
                 KCl 
                 130 g 
                 8.6% 
               
               
                   
                 NaCl 
                 94.7   
                 6.3% 
               
               
                   
                 x-SO 4   
                 50 g 
                 3.3% 
                 x = Na/K 
               
               
                   
                 H 2 O 
                 907 g 
                 60 
               
               
                   
                   
                 1512 g 
               
               
                   
                   
               
             
          
         
       
     
     This brine is than heated and reacted with lime to recover the ammonia and bypass the evaporator. The KCl reports to the CaCl 2  brine rather than being recovered in the evaporator. This represents a 15 to 20% loss of K to the CaCl 2  brine. The KCl in the CaCl 2  brine can be reduced to as low as 1.0% by adding solid Na 2 SO 4  to CaCl 2 /KCl brine. The potassium is effectively collected as apprecipitated of syngenite (CaSO 4 .K 2 SO 4 .xH 2 O) at 0 to 100° C. with preferred temperatures of 20 to 30° C. so that SO 4  solubility is kept to minimum and the reaction occurs at a reasonable rate. 
     CaCl 2  Brine composition 
     
       
         
               
             
               
               
               
               
             
               
             
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 CaCl 2  Brine Compostion 
               
             
          
           
               
                 343.3 
                 g CaCl2 
                 22.5% 
                   
               
               
                 130 
                 g KCl 
                 8.5% 
               
               
                 94.7 
                 g NaCl 
                 6.3% 
               
               
                 50 
                 g x SO 4   
                 32.% 
                 (Na/K) 
               
               
                 907 
                 g H 2 O 
                 59.5% 
               
               
                 1525 
                 g 
                 100% 
               
             
          
           
               
                 140 g Na 2 SO 4  addition: 
               
             
          
           
               
                   
                 Exit Brine 
                 Exit Cake 
               
             
          
           
               
                 234.8 
                 g CaCl 2   
                 17.8% 
                   
                   
               
               
                 15.25 
                 g KCl 
                 1.1% 
                   
                 310 g CaSO 4 .K 2 SO 4   
               
               
                 209 
                 g NaCl 
                 15.9% 
                   
                 + 100  g H2O   
               
               
                 50 
                 g x SO 4   
                 3.8% 
               
               
                 807 
                   
                 61.3% 
               
               
                   
               
             
          
         
       
     
     The exit brine can be deep well disposed of and cake can be blended into the K 2 SO 4  product as binder or further processed to remove the CaSO 4 . 
     The cake can be reacted with (NH 4 ) 2 HCO 3  from the NaHCO 3  process feed and the CaSO 4  reacts quickly to produce a brine of (NH 4 ) 2 SO 4  and K 2 SO 4  and a filter CaCl 3  precipitate which is disposed of. The (NHa) 2 SO 4 /K 2 SO 4  brine is recycled to K 2 SO 4  first stage crystallizer. 
     Although embodiments of the invention have been described above, it is not limited thereto and it will be apparent to those skilled in the art that numerous modifications form part of the present invention insofar as they do not depart from the spirit, nature and scope of the claimed and described invention.