Title of Invention	A METHOD OF PRODUCING PRECIPITATED CALCIUM CARBONATE USING BRINE AND A SYSTEM THEREOF
Abstract	The invention relates to a method of producing precipitated calcium carbonate using brine comprising the steps of removal of magnesium from brine to form a substantially magnesium free brine; neutralization of the magnesium free brine by addition of an acid: and addition of soda ash to the neutralized brine to obtain precipitated calcium carbonate and a brine solution. The invention also relates to a system for the treatment of brine comprising a first filtration system for filtering out magnesium and other impurities from the brine: a neutralizer section for the addition o\" an acid to the brine from the first filtration system so as to obtain a brine with a pH value in the range of 6.5 to 7.5; a reactor for the addition of soda ash to the brine from the neutralizer section so as to obtain a brine solution with precipitated calcium carbonate.

Title of Invention

A METHOD OF PRODUCING PRECIPITATED CALCIUM CARBONATE USING BRINE AND A SYSTEM THEREOF

Abstract

The invention relates to a method of producing precipitated calcium carbonate using brine comprising the steps of removal of magnesium from brine to form a substantially magnesium free brine; neutralization of the magnesium free brine by addition of an acid: and addition of soda ash to the neutralized brine to obtain precipitated calcium carbonate and a brine solution. The invention also relates to a system for the treatment of brine comprising a first filtration system for filtering out magnesium and other impurities from the brine: a neutralizer section for the addition o\" an acid to the brine from the first filtration system so as to obtain a brine with a pH value in the range of 6.5 to 7.5; a reactor for the addition of soda ash to the brine from the neutralizer section so as to obtain a brine solution with precipitated calcium carbonate.

Full Text	FORM 2THE PATENTS ACT, 1970 (39 of 1970) &THE PATENTS RULES, 2003COMPLETE SPECIFIC A TION (See section 10, rule 13) /. Title of the invention A METHOD OF PRODUCING PRECIPITATED CALCIUM CARBONATE USING BRINE AND A SYSTEM THEREOF 2. Applicant(s) Name Nationality Address TATA CHEMICALS LIMITED India Bombay House. 24 Homi Modi Street. Mumbai-400 001 3. Preamble to the description COMPLETE SPECIFICATIONThe following specification particularly describes the invention and the manner in which it isto be performed. The invention refers to the treatment of brine and the recovery of useful elements from brine. More particularly, the invention relates to a method and system of utilizing brine for the production of precipitated calcium carbonate. Background of the Invention Chemical plants use various ingredients for the manufacture of desired compounds and generate large quantities of effluent. A plant for the manufacture of soda ash is one such example. Sodium carbonate, soda ash or washing soda finds wide use in industry including the manufacture of glass, pulp and paper, detergents, chemicals such as sodium silicates and sodium phosphates and often as an alkaline agent in many chemical industries. Soda ash is synthetically produced in large quantities from sodium chloride generally from a process referred to in the industry as the Ammonia Soda process or So\|\a\ process. The process describes the conversion of sodium chloride to sodium carbonate using ammonia and limestone. The sodium chloride for the Solvay process is required in solution form and is referred to as brine. Raw brine is obtained by dissolving solar salt in sea water and contains impurities such as Calcium [Ca] and Magnesium [Mg\| which cannot be tolerated in the soda ash making process. These impurities in the raw brine are removed by a brine purification process wherein the raw brine is treated with Milk of Lime \|Ca(OH);\| and soda ash to precipitate magnesium and calcium in the form of Mg(OU): and CaCO3;. The resultant brine free of impurities, essentially calcium and magnesium is referred to as pure brine and used in the soda ash manufacturing. The brine purification effluent is 2 " typically' disposed off to the sea after necessary treatment as required for compliance with environment norms. I his brine effluent comprises of elements, essential!) magnesium and calcium that are capable of being utilized in different industries. There is an increasing demand useful elements are recovered from the effluent so as to work towards a sustainable environment and economies of production be achieved. Calcium carbonate finds many uses in industry including as filler for certain plastics and rubber, as an opacifying agent in paints and surface coatings. In the food and pharmaceutical sector it has been used as an antacid, source of calcium and as a buffering or dissolution aid in soluble tablets. In addition calcium carbonate also finds use in the paper industry as a paper coating for brightness, smoothness, opacity and ink receptivity. Calcium carbonate is typically produced using high quality limestone. I he limestone is calcined to produce quick lime and the quick lime is hydrated to give milk o( lime. The milk of lime is in turn carbonated to give precipitated calcium carbonate in a slurry form. The slurry is filtered, washed and dried to obtain the final product. This process o\' precipitated calcium carbonate production is energy intensive and requires high quality limestone. Summary of the Invention The invention provides for a method of recovering precipitated calcium carbonate from Brine purification process. 3 The invention relates to a method of producing precipitated calcium carbonate using brine comprising the steps of removal of magnesium from brine to form a substantially magnesium free brine: neutralization of the magnesium free brine b\ addition of an acid; and addition of soda ash to the neutralized brine to obtain precipitated calcium carbonate and a pure brine. The invention also relates to a system for the treatment of brine comprising a first filtration system for filtering out impurities from the brine: a neutralize!- section for the addition of an acid to the brine from the first filtration s\stem so as to obtain a brine with a pH value in the range of 6.5 to 7.5: a reactor for the addition ol* soda ash to the brine from the neutralizer section so as to obtain a brine solution with precipitated calcium carbonate. Brief Description of Accompanying Drawings: I he accompany ing drawings illustrate the preferred embodiments of the invention and together with the following detailed description serve to explain the principles of the invention. I IG. I is a schematic illustration of a brine treatment plant for the production of precipitated calcium carbonate in accordance with an embodiment of the invention. Detailed Description of Invention To promote an understanding of the principles of the invention. reference will he made to the embodiment illustrated in the drawing and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system. and such further applications of the principles of the invention as illustrated 4 therein being contemplated as would normally occur to one skilled in the art to which the invention relates. The invention has been described with reference to the functioning of a soda ash plant. However, as would be obvious to a person in the art. the teachings of this document may be applied to any plant employing a brine refining section. 'Hie in\ention describes a method of treating brine to produce precipitated calcium carbonate. The invention also describes a system for manufacturing precipitated calcium carbonate from brine purification. The teachings of this document provide for the recovery of calcium carbonate from brine such that the calcium carbonate obtained is a vendible product and is obtained in an efficient manner not requiring excessive readjustments to the existing plant or requiring external elements to be added. In addition, the document describes methods of utilizing brine to generate pure brine for the soda ash plant. In addition, the document describes methods of reducing net waste disposed to the environment from a plant. With reference to the accompanying figure the preferred embodiment for a method and s\stem for the treatment of brine has been illustrated. Brine as required for the soda ash production is prepared using any brine preparation method as may be known, including conventional methods of adding solar salt to sea water. This raw brine is first treated for the removal of magnesium by the addition of milk of lime or calcium In dioxide \|Ca(OH);>] resulting in the precipitation of magnesium as magnesium h\dioxide \|Mg(OH)2\|. The magnesium free brine 42 is then sent for further processing in accordance with the teachings of this document. The magnesium free brine is first filtered at a first 5 filter system 12 that removes siliceous material and certain oxides such as l<: i he silica and other impurities removed at the first filter system may be disposed or se for use in cement manufacture> The filtrate 13 from the first filter system 12 is then sent to a neutralizer section 14. The neutralize!- section adds an acid, preferably hydrochloric acid \|ll( I \| to the filtrate 13 from the first filter system 12. The neutralization of the filtrate is done u> covert insoluble form of calcium, such as calcium sulphate, calcium oxide to soluble forms of calcium such as calcium chloride. Thus neutralization of the filtrate causes all the calcium ion forms to be reactive to soda ash. It is preferred that the filtrate is neutralized up to pi I in the range of 6.5 to 7.5. The neutralized filtrate I 5 is then sent to a reactor 16 where soda ash 46 is added \o the filtrate 15 in excess of the equivalent calcium present in the neutralized filtrate 15. I he addition of soda ash is accompanied by constant agitation in the reactor 16 a\ is conventionally done in a brine refinery section. The addition of soda ash at this stage results in the conversion of all forms of calcium such as calcium chloride into calcium carbonate. This calcium carbonate gets precipitated in the solution on account of low solubility. This solution 17 is then sent to a clarifier I 8 where pure I iquid brine 19 is taken as overflow and sent to the soda ash plant 20 and the underflow 21 from the clarifier is collected separately and sent to a second filter system 22. This underflow 21 is rich in calcium carbonate solids with little pure brine. At the second filter system 22 the underflow 21 is filtered and the filtrate 27 obtained from the second filter system is sent to the soda ash plant 20 for utilization. I he 6 solids 23 retained in the second filter system are repulped with water 40 at repulping station 24 and may be sent for nitration at a third filter system 26. The filtrate 28 from the third tiller system is also sent to the soda ash plant 20 for suitable utilization whereas the residue solids, comprising essentially of calcium carbonate is sent to a drying section 30 using air 36. I he precipitated calcium carbonate from the drying section is then sent to a milling section 32 where the precipitated calcium carbonate is pulverized into the desired particle size and sent to a packing or silo section 34. The method and system as described above does not require any substantial modification to the existing brine refinery section for a plant besides the addition of a neutralize!-section with filtration system. It will readily be appreciated by those skilled in the art that the present invention is not limited to the specific embodiments herein shown. Thus variations may be made within the scope and spirit of the accompanying claims without sacrificing the principal advantages of the invention. 7 We Claim: A method of producing precipitated calcium carbonate using brine comprising the steps of: a. removal of magnesium from brine to form a substantial!) magnesium free brine; b. neutralization of the magnesium free brine by addition of an acid: and c. addition of soda ash to the neutralized brine to obtain precipitated calcium carbonate and a brine solution. A method of producing precipitated calcium carbonate as claimed in claim I wherein magnesium free brine is neutralized to obtain a pi I value in the range of 6.5 to 7.5. A method of producing precipitated calcium carbonate as claimed in claim 1 wherein the acid is hydrochloric acid. A method of producing precipitated calcium carbonate as claimed in claim 1 wherein soda ash added to the neutralized brine is in excess o\' equivalent calcium present in the neutralized brine. 8 A method of producing precipitated calcium carbonate as claimed in claim I wherein the neutralized brine is agitated during addition of soda ash. A method of producing precipitated calcium carbonate as claimed in claim I wherein the brine solution containing precipitated calcium carbonate is clarified to separate the precipitated calcium carbonate from the brine solution. A method of producing precipitated calcium carbonate as claimed in claim 6 wherein the brine solution obtained after clarification is sent to a soda ash plant. A method of producing precipitated calcium carbonate as claimed in claim 6 wherein water is added to the precipitated calcium carbonate obtained from the clarification and the solution so obtained is filtered to produce filtered precipitated calcium carbonate. A method of producing precipitated calcium carbonate as claimed in claim 8 wherein the filtered precipitated calcium carbonate is washed with water. A method of producing precipitated calcium carbonate as claimed in claim 8 wherein the filtered precipitated calcium carbonate is dried and packed. 9 A system for the treatment of brine comprising: a. a first filtration system for filtering impurities from the Magnesium free brine. b. a neutralize!" section for the addition of an acid to the brine from the first filtration system so as to obtain a brine with a pH value in the range of 6.5 to 7.5: c. a reactor for the addition of soda ash to the brine from the neutralize!" section so as to obtain a brine solution with precipitated calcium carbonate. A system as claimed in claim 1 1 wherein the reactor has agitation means for agitating the brine. A system as claimed in claim 11 comprising a clarifier for separating brine from the precipitated calcium carbonate in the brine solution. A system as claimed in claim 13 comprising a second filter system for filtering the precipitated calcium carbonate received from the clarifier. A method of producing precipitated calcium carbonate using brine substantial!) as herein described with reference to and as illustrated by the accompanying drawings. 10 A system for treatment of brine substantially as herein described with reference to and as illustrated by the accompanying drawings. 11 ABSTRACT The invention relates to a method of producing precipitated calcium carbonate using brine comprising the steps of removal of magnesium from brine to form a substantially magnesium free brine; neutralization of the magnesium free brine by addition of an acid: and addition of soda ash to the neutralized brine to obtain precipitated calcium carbonate and a brine solution. The invention also relates to a system for the treatment of brine comprising a first filtration system for filtering out magnesium and other impurities from the brine: a neutralizer section for the addition o\' an acid to the brine from the first filtration system so as to obtain a brine with a pH value in the range of 6.5 to 7.5; a reactor for the addition of soda ash to the brine from the neutralizer section so as to obtain a brine solution with precipitated calcium carbonate. Figure 1 12

Full Text

FORM 2THE PATENTS ACT, 1970 (39 of 1970) &THE PATENTS RULES, 2003COMPLETE SPECIFIC A TION (See section 10, rule 13)
/. Title of the invention A METHOD OF PRODUCING PRECIPITATED CALCIUM CARBONATE USING BRINE AND A SYSTEM THEREOF
2. Applicant(s)
Name Nationality Address
TATA CHEMICALS LIMITED India Bombay House. 24 Homi Modi Street. Mumbai-400 001

3. Preamble to the description
COMPLETE SPECIFICATIONThe following specification particularly describes the invention and the manner in which it isto be performed.

The invention refers to the treatment of brine and the recovery of useful elements from brine. More particularly, the invention relates to a method and system of utilizing brine for the production of precipitated calcium carbonate.
Background of the Invention
Chemical plants use various ingredients for the manufacture of desired compounds and generate large quantities of effluent. A plant for the manufacture of soda ash is one such example.
Sodium carbonate, soda ash or washing soda finds wide use in industry including the manufacture of glass, pulp and paper, detergents, chemicals such as sodium silicates and sodium phosphates and often as an alkaline agent in many chemical industries.
Soda ash is synthetically produced in large quantities from sodium chloride generally from a process referred to in the industry as the Ammonia Soda process or So|\a\ process. The process describes the conversion of sodium chloride to sodium carbonate using ammonia and limestone.
The sodium chloride for the Solvay process is required in solution form and is referred to as brine. Raw brine is obtained by dissolving solar salt in sea water and contains impurities such as Calcium [Ca] and Magnesium [Mg| which cannot be tolerated in the soda ash making process. These impurities in the raw brine are removed by a brine purification process wherein the raw brine is treated with Milk of Lime |Ca(OH);| and soda ash to precipitate magnesium and calcium in the form of Mg(OU): and CaCO3;. The resultant brine free of impurities, essentially calcium and magnesium is referred to as pure brine and used in the soda ash manufacturing. The brine purification effluent is
2

" typically' disposed off to the sea after necessary treatment as required for compliance with environment norms.
I his brine effluent comprises of elements, essential!) magnesium and calcium that are capable of being utilized in different industries. There is an increasing demand useful elements are recovered from the effluent so as to work towards a sustainable environment and economies of production be achieved.
Calcium carbonate finds many uses in industry including as filler for certain plastics and rubber, as an opacifying agent in paints and surface coatings. In the food and pharmaceutical sector it has been used as an antacid, source of calcium and as a buffering or dissolution aid in soluble tablets. In addition calcium carbonate also finds use in the paper industry as a paper coating for brightness, smoothness, opacity and ink receptivity.
Calcium carbonate is typically produced using high quality limestone. I he limestone is calcined to produce quick lime and the quick lime is hydrated to give milk o( lime. The milk of lime is in turn carbonated to give precipitated calcium carbonate in a slurry form. The slurry is filtered, washed and dried to obtain the final product. This process o\' precipitated calcium carbonate production is energy intensive and requires high quality limestone.
Summary of the Invention
The invention provides for a method of recovering precipitated calcium carbonate from Brine purification process.
3

The invention relates to a method of producing precipitated calcium carbonate using brine comprising the steps of removal of magnesium from brine to form a substantially magnesium free brine: neutralization of the magnesium free brine b\ addition of an acid; and addition of soda ash to the neutralized brine to obtain precipitated calcium carbonate and a pure brine. The invention also relates to a system for the treatment of brine comprising a first filtration system for filtering out impurities from the brine: a neutralize!- section for the addition of an acid to the brine from the first filtration s\stem so as to obtain a brine with a pH value in the range of 6.5 to 7.5: a reactor for the addition ol* soda ash to the brine from the neutralizer section so as to obtain a brine solution with precipitated calcium carbonate. Brief Description of Accompanying Drawings:
I he accompany ing drawings illustrate the preferred embodiments of the invention and together with the following detailed description serve to explain the principles of the invention.
I IG. I is a schematic illustration of a brine treatment plant for the production of precipitated calcium carbonate in accordance with an embodiment of the invention.
Detailed Description of Invention
To promote an understanding of the principles of the invention. reference will he made to the embodiment illustrated in the drawing and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system. and such further applications of the principles of the invention as illustrated
4

therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
The invention has been described with reference to the functioning of a soda ash plant. However, as would be obvious to a person in the art. the teachings of this document may be applied to any plant employing a brine refining section.
'Hie in\ention describes a method of treating brine to produce precipitated calcium carbonate. The invention also describes a system for manufacturing precipitated calcium carbonate from brine purification.
The teachings of this document provide for the recovery of calcium carbonate from brine such that the calcium carbonate obtained is a vendible product and is obtained in an efficient manner not requiring excessive readjustments to the existing plant or requiring external elements to be added. In addition, the document describes methods of utilizing brine to generate pure brine for the soda ash plant. In addition, the document describes methods of reducing net waste disposed to the environment from a plant.
With reference to the accompanying figure the preferred embodiment for a method and s\stem for the treatment of brine has been illustrated. Brine as required for the soda ash production is prepared using any brine preparation method as may be known, including conventional methods of adding solar salt to sea water. This raw brine is first treated for the removal of magnesium by the addition of milk of lime or calcium In dioxide |Ca(OH);>] resulting in the precipitation of magnesium as magnesium h\dioxide |Mg(OH)2|.
The magnesium free brine 42 is then sent for further processing in accordance with the teachings of this document. The magnesium free brine is first filtered at a first
5

filter system 12 that removes siliceous material and certain oxides such as l<: i he silica and other impurities removed at the first filter system may be disposed or se for use in cement manufacture> The filtrate 13 from the first filter system 12 is then sent to a neutralizer section 14. The neutralize!- section adds an acid, preferably hydrochloric acid |ll( I | to the filtrate 13 from the first filter system 12. The neutralization of the filtrate is done u> covert insoluble form of calcium, such as calcium sulphate, calcium oxide to soluble forms of calcium such as calcium chloride. Thus neutralization of the filtrate causes all the calcium ion forms to be reactive to soda ash. It is preferred that the filtrate is neutralized up to pi I in the range of 6.5 to 7.5.
The neutralized filtrate I 5 is then sent to a reactor 16 where soda ash 46 is added \o the filtrate 15 in excess of the equivalent calcium present in the neutralized filtrate 15. I he addition of soda ash is accompanied by constant agitation in the reactor 16 a\ is conventionally done in a brine refinery section. The addition of soda ash at this stage results in the conversion of all forms of calcium such as calcium chloride into calcium carbonate. This calcium carbonate gets precipitated in the solution on account of low solubility.
This solution 17 is then sent to a clarifier I 8 where pure I iquid brine 19 is taken as overflow and sent to the soda ash plant 20 and the underflow 21 from the clarifier is collected separately and sent to a second filter system 22. This underflow 21 is rich in calcium carbonate solids with little pure brine.
At the second filter system 22 the underflow 21 is filtered and the filtrate 27 obtained from the second filter system is sent to the soda ash plant 20 for utilization. I he
6

solids 23 retained in the second filter system are repulped with water 40 at repulping station 24 and may be sent for nitration at a third filter system 26. The filtrate 28 from the third tiller system is also sent to the soda ash plant 20 for suitable utilization whereas the residue solids, comprising essentially of calcium carbonate is sent to a drying section 30 using air 36. I he precipitated calcium carbonate from the drying section is then sent to a milling section 32 where the precipitated calcium carbonate is pulverized into the desired particle size and sent to a packing or silo section 34.
The method and system as described above does not require any substantial modification to the existing brine refinery section for a plant besides the addition of a neutralize!-section with filtration system.
It will readily be appreciated by those skilled in the art that the present invention is not limited to the specific embodiments herein shown. Thus variations may be made within the scope and spirit of the accompanying claims without sacrificing the principal advantages of the invention.
7

We Claim:
A method of producing precipitated calcium carbonate using brine comprising the steps of:
a. removal of magnesium from brine to form a substantial!)
magnesium free brine;
b. neutralization of the magnesium free brine by addition of an acid:
and
c. addition of soda ash to the neutralized brine to obtain precipitated
calcium carbonate and a brine solution.
A method of producing precipitated calcium carbonate as claimed in claim I wherein magnesium free brine is neutralized to obtain a pi I value in the range of 6.5 to 7.5.
A method of producing precipitated calcium carbonate as claimed in claim 1 wherein the acid is hydrochloric acid.
A method of producing precipitated calcium carbonate as claimed in claim 1 wherein soda ash added to the neutralized brine is in excess o\' equivalent calcium present in the neutralized brine.
8

A method of producing precipitated calcium carbonate as claimed in claim I wherein the neutralized brine is agitated during addition of soda ash.
A method of producing precipitated calcium carbonate as claimed in claim I wherein the brine solution containing precipitated calcium carbonate is clarified to separate the precipitated calcium carbonate from the brine solution.
A method of producing precipitated calcium carbonate as claimed in claim 6 wherein the brine solution obtained after clarification is sent to a soda ash plant.
A method of producing precipitated calcium carbonate as claimed in claim 6 wherein water is added to the precipitated calcium carbonate obtained from the clarification and the solution so obtained is filtered to produce filtered precipitated calcium carbonate.
A method of producing precipitated calcium carbonate as claimed in claim 8 wherein the filtered precipitated calcium carbonate is washed with water.
A method of producing precipitated calcium carbonate as claimed in claim 8 wherein the filtered precipitated calcium carbonate is dried and packed.
9

A system for the treatment of brine comprising:
a. a first filtration system for filtering impurities from the Magnesium
free brine.
b. a neutralize!" section for the addition of an acid to the brine from the
first filtration system so as to obtain a brine with a pH value in the
range of 6.5 to 7.5:
c. a reactor for the addition of soda ash to the brine from the neutralize!"
section so as to obtain a brine solution with precipitated calcium
carbonate.
A system as claimed in claim 1 1 wherein the reactor has agitation means for agitating the brine.
A system as claimed in claim 11 comprising a clarifier for separating brine from the precipitated calcium carbonate in the brine solution.
A system as claimed in claim 13 comprising a second filter system for filtering the precipitated calcium carbonate received from the clarifier.
A method of producing precipitated calcium carbonate using brine substantial!) as herein described with reference to and as illustrated by the accompanying drawings.
10

A system for treatment of brine substantially as herein described with reference to and as illustrated by the accompanying drawings.

11

ABSTRACT
The invention relates to a method of producing precipitated calcium carbonate using brine comprising the steps of removal of magnesium from brine to form a substantially magnesium free brine; neutralization of the magnesium free brine by addition of an acid: and addition of soda ash to the neutralized brine to obtain precipitated calcium carbonate and a brine solution. The invention also relates to a system for the treatment of brine comprising a first filtration system for filtering out magnesium and other impurities from the brine: a neutralizer section for the addition o\' an acid to the brine from the first filtration system so as to obtain a brine with a pH value in the range of 6.5 to 7.5; a reactor for the addition of soda ash to the brine from the neutralizer section so as to obtain a brine solution with precipitated calcium carbonate.
Figure 1
12

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Patent Number

257038

Indian Patent Application Number

1618/MUM/2007

PG Journal Number

35/2013

Publication Date

30-Aug-2013

Grant Date

28-Aug-2013

Date of Filing

24-Aug-2007

Name of Patentee

TATA CHEMICALS LIMITED

Applicant Address

BOMBAY HOUSE, 24 HOMI MODI STREET, MUMBAI

Inventors:

#	Inventor's Name	Inventor's Address
1	S. S. BANERJEE	TATA CHEMICALS LTD. MITHAPUR-361345 DIST JAMNAGAR
2	DINESH K. MISTRY	TATA CHEMICALS LTD. MITHAPUR-361345 DIST JAMNAGAR
3	NAJMUL H. KHAN	TATA CHEMICALS LTD. MITHAPUR-361345 DIST JAMNAGAR

PCT International Classification Number

C01F11/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA