Processes for the production of citric acid
The present application pertains to methods for making metal oxides and/or citric acid. In one embodiment, the application pertains to a process for producing calcium oxide, magnesium oxide, or both from a material comprising calcium and magnesium. The process may include reacting a material comprising calcium carbonate and magnesium carbonate. Separating, concentrating, and calcining may lead to the production of oxides such as calcium oxide or magnesium oxide. In other embodiments the application pertains to methods for producing an alkaline-earth oxide and a carboxylic acid from an alkaline earth cation-carboxylic acid anion salt. Such processes may include, for example, reacting an alkaline-earth cation-carboxylic acid anion salt with aqueous sulfur dioxide to produce aqueous alkaline-earth-bisulfite and aqueous carboxylic acid solution. Other useful steps may include desorbing, separating, and/or calcining.
1. A process for producing an alkaline-earth oxide and a carboxylic acid from an alkaline earth cation-carboxylic acid anion salt wherein the process comprises:
reacting an alkaline-earth cation-carboxylic acid anion salt with aqueous sulfur dioxide to produce aqueous alkaline-earth-bisulfite and aqueous carboxylic acid solution;
desorbing sulfur dioxide from said aqueous alkaline-earth-bisulfite and aqueous carboxylic acid solution to produce alkaline-earth-sulfite solid and aqueous carboxylic acid solution;
separating said alkaline-earth-sulfite solid from said aqueous carboxylic acid solution; and
calcining said alkaline-earth-sulfite solid to produce alkaline-earth-oxide, cement, or a combination thereof.
2. The process of claim 1 wherein said alkaline-earth cation comprises calcium cation.
3. The process of claim 1 wherein said alkaline-earth cation comprises magnesium cation.
4. The process of claim 1 wherein said carboxylic acid anion salt comprises citric acid anion salt.
5. The process of claim 1 which further comprises separating aqueous carboxylic acid solution into isolated carboxylic acid and water.
6. The process of claim 5 which further comprises absorbing sulfur dioxide with said water to generate aqueous sulfur dioxide for the reacting step.
7. The process of claim 5 wherein said isolated water comprises dissolved sulfur dioxide.
8. The process of claim 7 which further comprises separating sulfur dioxide from the isolated water.
9. The process of claim 1 which further comprises absorbing said desorbed sulfur dioxide in water to produce aqueous sulfur dioxide.
10. The process of claim 1 wherein said calcining said alkaline-earth-sulfite solid produces sulfur dioxide.
11. The process of claim 10 which further comprises absorbing said sulfur dioxide in water to produce aqueous sulfur dioxide.
12. The process of claim 1 which further comprises reacting said alkaline-earth-oxide with water to produce alkaline-earth-hydroxide.
13. The process of claim 12 wherein said alkaline-earth-hydroxide is dissolved in water.
14. The process of claim 12 wherein said reacting produces heat and wherein said heat is used desorb sulfur dioxide, separate water, or both.
15. The process of claim 12 wherein said reacting produces heat and wherein said heat is used in the process.
16. The process of claim 12 which further comprises reacting said alkaline-earth-hydroxide with a solution comprising a carboxylic acid to form alkaline-earth cation-carboxylic acid anion salt.
17. The process of claim 16 wherein said alkaline-earth-hydroxide is dissolved in water.
18. The process of claim 16 wherein said alkaline-earth-hydroxide comprises calcium hydroxide.
19. The process of claim 16 wherein at least a portion of said alkaline-earth cation-carboxylic acid anion salt is a solid.
20. The process of claim 19 which further comprises separating said alkaline-earth cation-carboxylic acid anion salt using solid-liquid separation.
21. The process of claim 1 wherein said separating comprises a solid-liquid separation step.
22. The process of claim 1 wherein the process is conducted in the presence of a low diatomic oxygen environment.
23. The process of claim 1 wherein said calcining is conducted under conditions to substantially prevent the formation of sulfate.
24. The process of claim 1 which further comprises producing a precipitated alkaline-earth-carbonate from said alkaline-earth-hydroxide.
25. The process of claim 24 wherein said precipitated alkaline-earth-carbonate comprises calcium carbonate, magnesium carbonate, or both.
26. A process for producing calcium oxide and carboxylic acid from a calcium cation-carboxylic acid anion salt wherein the process comprises:
reacting a calcium cation-carboxylic acid anion salt with aqueous sulfur dioxide to produce aqueous calcium bisulfite and aqueous carboxylic acid;
desorbing sulfur dioxide from said aqueous calcium bisulfite and aqueous carboxylic acid solution to produce calcium sulfite solid and aqueous carboxylic acid solution;
separating said calcium sulfite solid from said aqueous carboxylic acid solution; and
calcining said calcium sulfite solid to produce calcium oxide, cement, or a combination thereof.
27. A process for producing calcium oxide and citric acid from calcium citrate wherein the process comprises:
reacting calcium citrate with aqueous sulfur dioxide to produce aqueous calcium bisulfite and aqueous citric acid;
desorbing sulfur dioxide from said aqueous calcium bisulfite and aqueous citric acid solution to produce calcium sulfite solid and aqueous citric acid solution;
separating said calcium sulfite solid from said aqueous citric acid solution; and
calcining said calcium sulfite solid to produce calcium oxide, cement, or a combination thereof.