FORM - 2
THE PATENTS ACT, 1970 (39 of 1970)
PROVISIONAL SPECIFICATION (See section 10; rule 13)
"UTILIZATION OF DISTILLER WASTE LIQUOR EMANATING FROM SODA ASH PLANT"
NIRMA LIMITED
A Company Incorporated Under The Indian Companies Act,
having its registered address at
Nirma House, Ashram Road,
Ahmedabad-380009 ,Gujarat State, India.
The following specification particularly describes the invention:

FIELD OF THE INVENTION
The present invention relates Utilization Of Distiller Waste Liquor emanating from Soda Ash Plant to recover marine grade gypsum & solar salt by reacting calcium chloride with magnesium sulphate of sea water. This invention particularly relates to Utilization of distiller waste in clear form to recover marine grade gypsum and solar salt.
BACKGROUND OF THE INVENTION
This invention relates to process for the utilization of distiller waste liquor emanating from soda ash plant. This invention particularly relates to Utilization of distiller waste in clear form after separation of solids in settling ponds to recover valuable products like High purity marine gypsum and solar salt. Moreover, these products recovered by the proposed invention are easily harvestable and are crystalline in nature.
High purity marine gypsum is mainly used in cement plant in combination with clinker and in several industries as starting material for preparing gypsum boards as well as Plaster of Paris. Solar salt plays an important role in manufacturing of soda ash and caustic soda.
Moreover, this invention is eco friendly as it totally eliminates discharge of distiller waste liquor emanating from soda ash plant which is discharged into the sea. There is a high risk of contamination and pollution of water and land as various industries tend to discharge the industrial waste in the same. This invention utilizes waste liquor obtaining marine grade high purity marine gypsum and solar salt and further eliminates discharge of distiller waste liquor into the sea. Thus the proposed invention does not contaminate sea water. This invention utilizes distiller waste liquor to its full extent and obtains products of higher quality which are utilized in industries at an optimum level thereby making the invention efficient and economical.
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PRIOR ART
There are various processes extracting gypsum and solar salt. Amongst them , U.S. Pat. No. 7,014,832 dated Mar. 21, 2006 titled "An improved process for simultaneous recovery of industrial grade potassium chloride and edible salt enriched with KCI (Low sodium salt) from bittern" discloses a process wherein the main objective is recovery of industrial grade potassium chloride and low sodium edible salt from. The process comprises, mixing low sulphate concentrated feed bittern (a by-product of salt industry) of density 31.5 to 32.5 0Be' (sp.gr. 1.277-1.289) with high density end bittern of density 36.5 to 37.5 0Be' (sp.gr. 1.336-1.35), thereby producing low sodium carnallite, from which industrial grade potassium chloride is produced. The resultant bittern is evaporated in forced evaporation system, thereby producing crude carnallite, from which low sodium salt that would be beneficial to persons suffering from hypertension is produced. When sulphate-rich bittern is used, such bittern is desulphated with CaCI2 that is generated from carnallite decomposed liquor through reaction with lime, and wherein low B2O3-containing Mg(OH)2 is a byproduct.
U.S. Pat. No. 2003008006 dated May. 1, 2003 titled " Recovery of common salt and marine chemicals from brine " discloses a process wherein the main objective is recovery of common salt, potassium chloride, concentrated magnesium chloride with enriched bromide, and high purity magnesia from brine in an integrated manner, said process comprises preparation of calcium chloride by reaction of hydrochloric acid generated in the process with limestone, desulphation of brine with calcium chloride, production of sodium chloride of superior quality in solar pans, solar evaporation of bittern thereby producing carnallite and end bittern, processing carnallite through established processes to produce potassium chloride, recovering end bittern containing highly concentrated magnesium chloride and enriched bromide and calcination of a part
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of the end bittern after solidification to produce high purity magnesia and hydrochloric acid utilizable in the process.
A paper in Salt Research and Industry by Sanghavi J.R., titled "Potassium chloride recovery from sea bittern by desulphation process using calcium chloride as precipitant" discloses a process wherein the main objective is recovery of potassium chloride from sea bittern of 28 0Be' by desulphation using 40% solution of calcium chloride thereby precipitating gypsum which was separated & the desulphated bittern was evaporated & sodium chloride was collected at 32 0Be'and carnallite was recovered at 35.6 0Be'. It was observed that when 28 OBe' bittern was desulphated, the density of bittern fell to 25.5 0Be' with gypsum obtained was very fine & it was difficult to collect from the pan. Gypsum remained as slurry even after 15 days in pan during field experiments. Sodium chloride fraction recovered at 32 OBe' invariably contained 1-3% CaSO4. Carnallite analysis being: 16-19% KCI, 12-15% NaCI & 27-30% MgCI2. However, this is economically feasible only if calcium chloride is available at nominal cost on the plant site.
A paper in Chemical Age of India, Vol.17, No.8, August 1966 by Joshi J.M., Sanghavi J.R., Seshadri K., titled "Potassium chloride recovery from mixed salt using distiller waste liquor of soda ash plant" discloses a process wherein the main objective is recovery of potassium chloride by using distiller waste liquor of soda ash factory for desulphation of mixed salt obtained from salt bitterns. Desulphated liquor, by solar evaporation, yields a mixture of potassium chloride & sodium chloride as first fraction & carnallite as second fraction. The recovered fractions are worked out for pure potassium chloride by known methods. Saturated solution of mixed salt was prepared by dissolving 50kg mixed salt in 94 liters of water. Mixed salt solution was treated with concentrated calcium chloride solution (CaCI2 =39.1%) in stoichiometric proportion to that of magnesium sulphate content. Precipitated gypsum slurry was filtered & desulphated solution was concentrated in pans by solar evaporation. Two different fractions were collected at 320Be' of KCI-NaCI mixture and at 36.40Be' of carnallite.
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A paper in Journal of Scientific & Industrial Research, 1958, Vol. 17A, No. 3 by Gadre G.T., Rao A.V., Bhavnagary H.M., titled "Potassium chloride from sea bittern: Part I" discloses a process wherein the main objective is recovery of potassium chloride of 97-99% purity from waste bittern of marine salt industry. The desulphation of bittern was carried out using commercial calcium chloride. Sulphate-free bittern deposits, on concentration, the double salt, KCI.MgCI2.6H2O, from which potassium chloride is recovered by leaching it with cold water or by cooling a supersaturated solution of the double salt. The bittern discharged from saltpans at 29-300Be' contains magnesium & potassium salts. Further concentration to 340Be' deposits common salt containing magnesium sulphate & double salt. It is, therefore, necessary to remove magnesium sulphate prior to the concentration of the bittern for obtaining carnallite. This can be achieved by double decomposition with calcium chloride. After the insoluble calcium sulphate filtered, the bittern contains mainly potassium & magnesium chlorides from which carnallite can be crystallized by concentration. Calcium sulphate is precipitated out from the bittern at room temperature by addition of calcium chloride, 10% in excess of theoretical amount. After agitating for 1 hour, the precipitate is filtered off & washed with water to remove adhering potassium chloride. The desulphated bittern is concentrated to a point when the temperature of the boiling solution is 1230C. It is cooled to room temperature when crude double salt, KCI.MgCI2.6H2O, crystallizes out. The latter is dissolved in water & the solution concentrated to supersaturation point (b.p. 1150C). The liquor is then cooled to 200C when potassium chloride separates, which is filtered, washed with a solution of potassium chloride & dried at 1100C.
Presently distiller waste liquor emanating from soda ash plant is discharged into sea after settling and/or after dilution with sea water and pH adjustment. Thus in the existing technologies the waste liquor is not use at the optimum level and as a waste product thrown into the sea that contaminates and pollutes sea water.
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DRAWBACKS OF PRIOR ART
The existing processes have various drawbacks which are stated below:
1. They generally do not totally use waste liquor emanating from soda ash plant.
2. The distiller waste liquor from soda ash plant when discharged into the sea without extraction of the said products extensively contaminates and thus pollutes_sea water.
3. They generally produce gypsum which is slimy in nature and difficult to filter.
4. The Gypsum obtained from these processes is not of high quality.
5. They are not efficient, non eco-friendly and cumbersome to perform.
To overcome these drawbacks associated with the present practices the inventor has developed a new process for utilizing distiller waste liquor emanating from soda ash plant completely and thus eliminating total discharge of waste liquor into the sea. The upsides associated with the proposed process are stated below:
1. It uses distiller waste liquor emanating from soda ash plant to recover marine grade gypsum and solar salt crystalline in nature.
2. It completely eliminates discharge of distiller waste liquor into the sea water thus helping to protect sea water and making it eco friendly.
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3. Gypsum recovered from this process is of high purity which can be harvested easily from pans.
4. The proposed invention is efficient, eco friendly, cost effective and convenient.
5. The products obtained by this process are of high purity.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide a process for the recovery of high purity marine gypsum and solar salt by reacting calcium chloride with magnesium sulphate of sea water where the products are crystalline in nature.
Another object of this invention is to eliminate disposal of distiller waste liquor emanating from soda ash plant thus helping to protect sea water and making it eco friendly.
Another object of the present invention is to produce high purity gypsum, crystalline in nature which can be easily harvested from pans, from the desulphation process thus making the process convenient to use.
Another object of the present invention is to utilize distiller waste liquor to its full extent and obtain products of higher quality which are utilized in industries at an optimum level thereby making the invention efficient and economical.
DESCRIPTION OF THE INVENTION
The proposed invention provides integrated process for simultaneous recovery of marine grade gypsum and solar salt with significantly higher yield of gypsum and solar salt, which comprises of following steps:
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(a) Distiller waste emanating from soda ash plant settled in settling ponds to obtain the clear effluent.
(b) Desulphation of sea water of density in the range of 5-6°Be' with clear effluent containing calcium chloride and sodium chloride to produce marine gypsum and solar salt.
(c) Allowing the resulting sea water of step (b) to evaporate in a solar pan till density of 24 °Be' (sp.gr.1.200) is reached.
(d) Crystallizing from the residual brine NaCI in the form of natural
solar salt and thereby obtaining a magnesium chloride-rich end
bittern of 27-29°Be'.
Thus the proposed invention performs the above steps and extracts high purity marine gypsum and solar salt with a higher yield. Moreover, potassium chloride and crude salt and bromine are also extracted with higher purity.
Dated this 12th day of July, 2007.
To,
The Controller of Patents, The Patent Office,
At Mumbai.
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