Process for the preparation of natural salt formulations for seawater substitution, mineral fortification

Patent metadata

Field	Value
Publication number	US-9259663-B2
Application number	US-201214365896-A
Country	US
Kind code	B2
Filing date	Dec 27, 2012
Priority date	Dec 29, 2011
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

The present invention relates to natural crude salt formulations arid their cost-effective preparation. In particular, the invention discloses the fractionation of seawater into three fractions which can thereafter be suitably combined to reconstitute seawater in its pristine form for its various applications such as growth of marine microbes, flora and fauna in a marine environment, especially where such environments have to be created in locations far removed from the sea and/or where there is a requirement to modify the composition of seawater to better its performance. The fractions can also be blended appropriately to exclude the major constituent, namely sodium chloride, and thereby be useful for mineralization/re-mineralization of waters which are deficient in mineral nutrients such as calcium, magnesium, potassium, sulphate and bicarbonate including rain water and desalinated waters obtained through thermal/RO desalination. The invention can be practiced most cost-effectively in solar salt works operated on sea brine.

First claim

We claim:

1. A process for the preparation of natural salt formulation, wherein the process comprises the steps of:
(a) collection of sea brine of 2.5-4.0° Bé;
(b) subjecting sea brine as obtained in step (a) to solar evaporation till 25° Bé density to obtain salt composition of fraction I which is substantially free of sodium chloride and contains calcium, sulphate and carbonate/bicarbonate as the main constituents, and a brine rich in sodium chloride and other constituents;
(c) feeding the resultant brine of step (b) into another crystallizing pan and continuing solar evaporation of the saturated brine till the density reaches 28.5-31.0° Bé density to separate out much of the sodium chloride in the sea brine as fraction II, without being particularly concerned about the purity of sodium chloride, and leaving a mother liquor bittern largely free of NaCl;
(d) harvesting the salt as obtained in step (c) in the open sun;
(e) feeding the mother liquor bittern as obtained in step (c) into another crystallizing pan and continuing solar evaporation to close to solidification stage to obtain fraction III;
(f) harvesting the salts crystallized as obtained in step (e); and
(g) mixing the fractions (I), (II) and (III) as obtained in step (b), (d) and (f) in the proportions in which these are obtained to produce a natural salt formulation mimicking a dry sea or optionally;
(h) mixing only the fractions (I) and (III) in ratio ranging between 1:3 to 1:6 to obtain natural salt formulations which are substantially free of sodium chloride while containing other constituents in the sea brine, particularly calcium, magnesium, potassium, carbonate/bicarbonate, sulphate and micronutrients.

2. The process as claimed in claim 1 , wherein the sea brine as obtained in step (a) of claim 1 was clarified through flocculation or ordinary filtration or preferably ultrafiltration to separate out suspended matter including cysts, spores and microbes prior to charging into pans for evaporation in step (b).

3. The process as claimed in claim 1 , wherein the salt composition of fraction I recovered in step (b) having a free moisture content of 3-5% (w/w) was optionally added into the mother liquor of step (e) prior to further evaporation to soak in some of the moisture, and in the process reducing to some extent the evaporation load while still obtaining a product which is dry to handle.

4. The process as claimed in claim 1 , wherein natural salt formulation as obtained in step (g) of claim 1 , was used for reconstitution of sea water by re-dissolving of salts into fresh water sources.

5. The process as claimed in claim 4 , wherein the natural salt formulation is useful for the survival and growth of marine fauna and flora in an aquarium.

6. The process as claimed in claim 4 , wherein the natural salt formulation is useful for the growth of marine bacteria and microalgae and is useful as a substitute for ordinary seawater or special media such as Zobell marine broth and ASNIII medium.

7. The process as claimed in claim 4 , wherein the salinity of the seawater is made to vary as desired by varying the amount of the salt which is added.

8. The process as claimed in claim 1 , wherein the natural salt formulations obtained in step (h) are used for fortification of mineral-deficient water having 10-250 mg·L-1 total dissolved solids to give nutritious water having 300-500 ppm total dissolved solids, with desired amounts of calcium, magnesium, potassium, bicarbonate and sulphate, and low levels of sodium chloride as prescribed in various standards for potable and irrigation water.

9. The process as claimed in claim 1 , wherein evaporation of the sea brine can be undertaken under more controlled conditions employing forced evaporation methods in part or in full.

10. The process as claimed in claim 1 , wherein re-dissolution of the salts in water was accelerated by increasing surface, heating, subjecting to microwave treatment.

11. The process as claimed in claim 1 , wherein solutions of the salts are filtered to remove coarse and finely suspended matter prior to use.

12. A method for the use of natural crude salt fractions isolated from sea brine towards cost-effective reconstitution of seawater and mineral fortification, said fractions having the compositions as follows:
1. fraction I containing much of the calcium, bicarbonate/carbonate and a part of the sulphate in sea brine, and comprising Ca2+=20-23% (w/w), Mg2+=0.05-0.2% (w/w), Na+=0.75-1.5% (w/w), SO42−=48-54% (w/w), Cl−=2.3-3% (w/w), along with small amounts of CO32−/HCO3− whose absolute amount varies depending on CO2 concentration and pH, and traces of other constituents present in sea brine which may get co-crystallized or occluded or remain from adhering brine;
2. fraction II consisting essentially of sodium chloride in the sea brine separated out with an eye on minimizing the NaCl content in fractions I and III and without being particularly concerned about the purity of the NaCl;
3. fraction III which has useful constituents such as magnesium, sulphate and potassium while excluding much of the sodium chloride in seawater, and comprising Ca2+=0.08-4.15% (w/w), Mg2+=11-15% (w/w), Na+=3-6% (w/w), SO42−=16-19.5% (w/w), Cl−=38-40% (w/w), K+=3.5-4.5%(w/w).

13. The method for the use of natural crude salt fractions isolated from sea brine as claimed in claim 12 for fortification of mineral-deficient water, wherein mixing of fractions (I) and (III) was carried out in ratio ranging between 1:3 to 1:6.

14. The method for the use of natural crude salt fractions isolated from seawater as claimed in claim 12 for reconstitution of seawater, wherein mixing of fractions (I), II and (III) was carried out in the same weight proportions as in which they were obtained in steps (b), (d) and (f) respectively of claim 1 .

Assignees

• Council Scient Ind Res

Inventors

• Ghosh Pushpito Kumar
• Upadhyay Sumesh Chandra
• Mishra Sandhya Chandrikaprasad
• Mohandas Vadakke Puthoor
• Srivastava Divesh Narayan
• Shahi Vinod Kumar
• Sanghavi Rahul Jasvantrai
• Thampy Sreekumaran
• Makwana Babulal Surabhai
• Pancha Imran
• Pal Ruma
• Sen Ramkrishna

Classifications

• C12N1/12

  Unicellular algae; Culture media therefor (as new plants A01H13/00) · CPC title

• A23L33/16

  Inorganic salts, minerals or trace elements · CPC title

• Y02W10/37

  using solar energy · CPC title

• A01G33/00

  Cultivation of seaweed {or algae} · CPC title

• C01F11/18

  Carbonates · CPC title