Indian Patents. 255321:PROCESS FOR EXTRACTION OF FINE IRON FROM RED MUD

Title of Invention	PROCESS FOR EXTRACTION OF FINE IRON FROM RED MUD
Abstract	The present invention discloses extraction of fine iron from Bayer Process red mud of alumina industry. The major impurities, sodalite (L08Na2OAl2O3l.68SiO2l.8H2O), quartz (SiO2) and amorphous substances were removed only by simple decantation and centrifuged technique from red mud and red mud slurry.

Full Text	STATEMENT OF INVENTION: The present invention discloses simple extraction technique of fine iron form red mud. Composition of red mud depends on origin of bauxite ore and chemical treatment during alumina extraction. Red mud is highly alkaline in nature having pH value above 13. It is reduced with the help of CO2 to obtain a pH value of 10-9 from 13. Subsequently, bio degradable anionic, nonionic surfactants, phosphates and small quantities of adjuvant called, extran is added when the pH of red mud solution is in between 10 to 9. Then, red mud solution is heated for 30 minutes at 50° to 80° C, with stirring rate at 5 s-1. By this process, fine iron settles down and other lighter substances emulsifies due to formation of C02-in-water microemulsions. Simple decantation process is carried out to remove amorphous substances. BACKGROUND OF INVENTION: In the past, attempts have been made to extract iron from red mud. In 1976, a method has been proposed to extract a-iron using cone. HSO4, HC1 and SO2 gas [European journal of soil Sciences: 27(4), 478- 486 (1976)]. Recently, a method of extracting iron form red mud has been developed using EDTA and magnetic separation principle [Mineral Engineering: 19, 1603-1605 (2006)]. Few patents have been granted in different countries for invention of iron extraction form red mud. US Patent Nos. 6248302 Bl and 2001005 Al by exposing red mud to a digester containing acid and high temperature to separate out iron. US Patent No. 3,574,537 discusses suitable method of extracting iron using SO2 from the solution of red mud. Japanese Patent No. J54137-499 adds sulfuric acid first then ammonia is used to reduce trivalent iron to divalent. Hydrolization separates out, however adjustment of pH values is necessary. German Patent No. 2653762 uses a process comprising of heating red mud to temperature in the range of 250° C to 350° C adding concentrated H2SO4 or SO2 gas leaching the sulphates formed with water and separating the solution. Further, chemical treatment and separation process followed by roasting at 900° to 1000° C. Till date, an efficient and cost effective method of extracting iron form red mud has not been proposed in spite of great potential exist for this technology. Red mud, being a waste material, usually contains 30% to 60% of iron oxides depending on source of origin. Thousands of tons of red mud are generated during extraction of alumina using Bayer Process. Therefore, development of eco-friendly and economic method of extraction of fine iron from red mud finds suitable for industrial application. OBJECT OF THE INVENTION: The objective of the invention is to develop a cost effective process for extraction of fine iron from red mud. As the method is simple only by the addition of water, surfactants and moderate heating, resources needed for extraction is reduced to a great extent. In addition the method outlines a procedure for effective utilization of waste material red mud. The basic purpose of this invention is to propose a simple and efficient method having potential for industrial application. SUMMARY OF INVENTION: A process of extraction of fine iron from red mud is developed by simply using water, surfactant and global warming CO2 gas. Extraction of fine iron from red mud depends on pH value and temperature of red mud solution. Initially, CO2 gas is passed over red mud solution to react with water producing H2CO3 so that pH value of the solution can be reduced to the range of 10-9. Then surfactants are added to the solution at this condition. Red mud solution is heated to 50° to 80 °C with constant stirring at 5 s"1. Doing so, fine iron being heavier particles settles down and other particles reacts with surfactants to form colloidal solution. Simple decantation procedure helps to separate out iron. The % (w/w) of extracted fine iron oxide is usually ~ 85%. Extracted iron can be used in steel plants for production of steel. Utilization of red mud can minimize the cost of waste management of aluminum industry with regard to requirement of vast area of red mud pond. Moreover other environmental problem can also be minimized. The method is quite eco-friendly and further, there is no problem in the reprocessing or disposal of the by-product. DRAWINGS (if any) Fig: The steps of extraction process are shown in figure 1. Fig: The SEM image of extracted fine iron obtained in Example 1 is shown in figure 2. Fig: The EDX analysis spectrums of recovered fine iron obtain in Example 1 is shown in figure 3. DETAILED DESCRIPTION The existing methods of extracting iron from red mud using acidic and magnetic separation methods involve huge resources in terms of energy consumption and reagents. Therefore, these methods increase the cost of extraction. Further, pollutants generated from such processes causes environmental hazards. Air dried red mud is mixed with water in 1:10 (w/v) ratio. The mixing is carried out in a glass container provided with stirrer. Then CO2 gas is passed through the above solution at a rate of 5 ml/rnin with constant stirring till it reaches up to a pH of 10-9. After that biodegradable anionic and nonionic surfactants, extran (5%v/v) is added at (1:100) (v/v). The red mud solution is heated at a temperature of 50°- 80° C for 30 minutes to lhour with constant stirring at 5 s" . The heavier fine iron settled down in the bottom of the container which is separated by decantation and washing. EXAMPLE - 1: 1 Kg of red mud deriving form the treatment of NALCO Damanjodi bauxite according to the Bayer Process was used. The major oxides composition of air dried red mud in %(w/w) were as follows: Fe203 (52.39), A1203 (14.73), Ti02 (3.30), Si02 (8.44), Na20 (4.00). Air dried red mud was mixed with water in 1:10 (w/v) ratio having a pH of about 11.5. The mixing was carried out in a glass container provided with stirrer. Then C02 gas was passed through the above solution at a rate of 5 ml/min with constant stirring till it was reached up to a pH of 10-9. After that biodegradable anionic and nonionic surfactants, extran (5%v/v) was added at (1:100) (v/v) to red mud solution. The red mud solution was heated at a temperature of 50°- 80° C for 30 minutes with constant stirring at 5 s-1 The heavier fine iron oxides were settled down in the bottom of the container. The fine iron was separated decantation. Further, the separate fine iron was washed and dried. The product was dried in oven at 105°C for 2 hours before analysis. The composition of the recovered fine iron oxide was: Fe2O3 (92.25%) along with A12O3 (5.68%) and TiO2 (2.07%). The iron content of fine iron oxide was 71.71 %(w/w), and other elements were Al (3.01%), Ti (1.24%), O (24.05%). Further, the amount of fine iron extracted from the red mud (1 Kg) as obtained by separation, washing, and drying was as follows: Fine iron= 0.922gm/Kg and 0.717gm/Kg Fe. EXAMPLE - 2: The procedure described in Example 1 was repeated except that red mud was added in amount of 10 Kg. The composition of the resulting recovered fine iron from the solution was as follows: Major elements of recovered fine iron were in %(w/w): Fe (70.52%), Al (3.32%), Ti (1.28%), O (24.88%). Further, the amount of fine iron extracted from the red mud (10 Kg) as obtained by separation, washing, and drying was as follows: Fine iron as Fe = 7.05 Kg/l0Kg CLAIMS We claim: 1. A process for treatment of the red mud obtained from the alumina industry, comprising the steps of: preliminary filtration of said red mud to recover caustic using ultrasonic agitation, addition of water to red mud and CO2 to reduce the pH to 10-9. The surfactant is added and heated to a temperature of 50°-80° C for 30 minutes with constant stirring; to achive separation of fine iron from the red mud. 2. A process according to claim 1, wherein the recovery of caustic is carried out by the process of centrifuge filtration. 3. A process according to claim 1, wherein the air dried red mud is mixed with water in 1:10 (w/v) ratio. The mixing is carried out in a glass container provided with stirrer. 4. A process according to claim 1, wherein the CO2 gas is passed through the above solution at a rate of 5 ml/min with constant stirring till it reaches up to a pH of 10-9. 5. A process according to claim 1, wherein the biodegradable anionic and nonionic surfactants, extran (5%v/v) is added at (1:100) (v/v). 6. A process according to claim 1, wherein the reaction is carried out at 50°-80° C, with stirring rate at 5 s" . 7. A process according to claim 1, wherein the fine iron settles down and other lighter substances emulsifies due to formation of CO2-in-water microemulsions. Simple decantation process is carried out to remove amorphous substances. 8. A process according to claim 1, wherein the said reaction is carried out for 30min to 1 hour. 9. A process according to claim 1, wherein the fine iron is isolated by settles down in hot condition at above 50°C. 10. A process according to claim 1, wherein the fine iron is separated by decantation and washing. Fine iron whenever obtained by the process according to the proceeding claim. The present invention discloses extraction of fine iron from Bayer Process red mud of alumina industry. The major impurities, sodalite (L08Na2OAl2O3l.68SiO2l.8H2O), quartz (SiO2) and amorphous substances were removed only by simple decantation and centrifuged technique from red mud and red mud slurry.

Full Text

STATEMENT OF INVENTION:
The present invention discloses simple extraction technique of fine iron form red mud. Composition of red mud depends on origin of bauxite ore and chemical treatment during alumina extraction. Red mud is highly alkaline in nature having pH value above 13. It is reduced with the help of CO2 to obtain a pH value of 10-9 from 13. Subsequently, bio degradable anionic, nonionic surfactants, phosphates and small quantities of adjuvant called, extran is added when the pH of red mud solution is in between 10 to 9. Then, red mud solution is heated for 30 minutes at 50° to 80° C, with stirring rate at 5 s-1. By this process, fine iron settles down and other lighter substances emulsifies due to formation of C02-in-water microemulsions. Simple decantation process is carried out to remove amorphous substances.
BACKGROUND OF INVENTION:
In the past, attempts have been made to extract iron from red mud. In 1976, a method has been proposed to extract a-iron using cone. HSO4, HC1 and SO2 gas [European journal of soil Sciences: 27(4), 478- 486 (1976)]. Recently, a method of extracting iron form red mud has been developed using EDTA and magnetic separation principle [Mineral Engineering: 19, 1603-1605 (2006)]. Few patents have been granted in different countries for invention of iron extraction form red mud. US Patent Nos. 6248302 Bl and 2001005 Al by exposing red mud to a digester containing acid and high temperature to separate out iron. US Patent No. 3,574,537 discusses suitable method of extracting iron using SO2 from the solution of red mud. Japanese Patent No. J54137-499 adds sulfuric acid first then ammonia is used to reduce trivalent iron to divalent. Hydrolization separates out, however adjustment of pH values is necessary. German Patent No. 2653762 uses a process comprising of heating red mud to temperature in the range of 250° C to 350° C adding concentrated H2SO4 or SO2 gas leaching the sulphates formed with water and separating the solution. Further, chemical treatment and separation process followed by roasting at 900° to 1000° C. Till date, an efficient and cost effective method of extracting iron form red mud has not been proposed in spite of great potential

exist for this technology. Red mud, being a waste material, usually contains 30% to 60% of iron oxides depending on source of origin. Thousands of tons of red mud are generated during extraction of alumina using Bayer Process. Therefore, development of eco-friendly and economic method of extraction of fine iron from red mud finds suitable for industrial application.
OBJECT OF THE INVENTION:
The objective of the invention is to develop a cost effective process for extraction of fine iron from red mud. As the method is simple only by the addition of water, surfactants and moderate heating, resources needed for extraction is reduced to a great extent. In addition the method outlines a procedure for effective utilization of waste material red mud. The basic purpose of this invention is to propose a simple and efficient method having potential for industrial application.
SUMMARY OF INVENTION:
A process of extraction of fine iron from red mud is developed by simply using water, surfactant and global warming CO2 gas. Extraction of fine iron from red mud depends on pH value and temperature of red mud solution. Initially, CO2 gas is passed over red mud solution to react with water producing H2CO3 so that pH value of the solution can be reduced to the range of 10-9. Then surfactants are added to the solution at this condition. Red mud solution is heated to 50° to 80 °C with constant stirring at 5 s"1. Doing so, fine iron being heavier particles settles down and other particles reacts with surfactants to form colloidal solution. Simple decantation procedure helps to separate out iron. The % (w/w) of extracted fine iron oxide is usually ~ 85%. Extracted iron can be used in steel plants for production of steel. Utilization of red mud can minimize the cost of waste management of aluminum industry with regard to requirement of vast area of red mud pond. Moreover other environmental problem can also be minimized. The method is quite eco-friendly and further, there is no problem in the reprocessing or disposal of the by-product.

DRAWINGS (if any)
Fig:
The steps of extraction process are shown in figure 1.
Fig:
The SEM image of extracted fine iron obtained in Example 1 is shown in figure 2.
Fig:
The EDX analysis spectrums of recovered fine iron obtain in Example 1 is shown in
figure 3.
DETAILED DESCRIPTION
The existing methods of extracting iron from red mud using acidic and magnetic separation methods involve huge resources in terms of energy consumption and reagents. Therefore, these methods increase the cost of extraction. Further, pollutants generated from such processes causes environmental hazards.
Air dried red mud is mixed with water in 1:10 (w/v) ratio. The mixing is carried out in a glass container provided with stirrer. Then CO2 gas is passed through the above solution at a rate of 5 ml/rnin with constant stirring till it reaches up to a pH of 10-9. After that biodegradable anionic and nonionic surfactants, extran (5%v/v) is added at (1:100) (v/v). The red mud solution is heated at a temperature of 50°- 80° C for 30 minutes to lhour with constant stirring at 5 s" . The heavier fine iron settled down in the bottom of the container which is separated by decantation and washing.
EXAMPLE - 1:
1 Kg of red mud deriving form the treatment of NALCO Damanjodi bauxite according to
the Bayer Process was used. The major oxides composition of air dried red mud in
%(w/w) were as follows: Fe203 (52.39), A1203 (14.73), Ti02 (3.30), Si02 (8.44), Na20
(4.00).
Air dried red mud was mixed with water in 1:10 (w/v) ratio having a pH of about 11.5. The mixing was carried out in a glass container provided with stirrer. Then C02 gas

was passed through the above solution at a rate of 5 ml/min with constant stirring till it was reached up to a pH of 10-9.
After that biodegradable anionic and nonionic surfactants, extran (5%v/v) was added at (1:100) (v/v) to red mud solution. The red mud solution was heated at a temperature of 50°- 80° C for 30 minutes with constant stirring at 5 s-1 The heavier fine iron oxides were settled down in the bottom of the container. The fine iron was separated decantation. Further, the separate fine iron was washed and dried.
The product was dried in oven at 105°C for 2 hours before analysis. The composition of the recovered fine iron oxide was: Fe2O3 (92.25%) along with A12O3 (5.68%) and TiO2 (2.07%). The iron content of fine iron oxide was 71.71 %(w/w), and other elements were Al (3.01%), Ti (1.24%), O (24.05%).
Further, the amount of fine iron extracted from the red mud (1 Kg) as obtained by separation, washing, and drying was as follows: Fine iron= 0.922gm/Kg and 0.717gm/Kg Fe.
EXAMPLE - 2:
The procedure described in Example 1 was repeated except that red mud was added in amount of 10 Kg. The composition of the resulting recovered fine iron from the solution was as follows:
Major elements of recovered fine iron were in %(w/w): Fe (70.52%), Al (3.32%), Ti (1.28%), O (24.88%).
Further, the amount of fine iron extracted from the red mud (10 Kg) as obtained by separation, washing, and drying was as follows: Fine iron as Fe = 7.05 Kg/l0Kg

CLAIMS
We claim:
1. A process for treatment of the red mud obtained from the alumina industry, comprising the steps of: preliminary filtration of said red mud to recover caustic using ultrasonic agitation, addition of water to red mud and CO2 to reduce the pH to 10-9. The surfactant is added and heated to a temperature of 50°-80° C for 30 minutes with constant stirring; to achive separation of fine iron from the red mud.
2. A process according to claim 1, wherein the recovery of caustic is carried out by the process of centrifuge filtration.
3. A process according to claim 1, wherein the air dried red mud is mixed with water in 1:10 (w/v) ratio. The mixing is carried out in a glass container provided with stirrer.
4. A process according to claim 1, wherein the CO2 gas is passed through the above solution at a rate of 5 ml/min with constant stirring till it reaches up to a pH of 10-9.
5. A process according to claim 1, wherein the biodegradable anionic and nonionic surfactants, extran (5%v/v) is added at (1:100) (v/v).
6. A process according to claim 1, wherein the reaction is carried out at 50°-80° C, with stirring rate at 5 s" .
7. A process according to claim 1, wherein the fine iron settles down and other lighter substances emulsifies due to formation of CO2-in-water microemulsions. Simple decantation process is carried out to remove amorphous substances.
8. A process according to claim 1, wherein the said reaction is carried out for 30min to 1 hour.
9. A process according to claim 1, wherein the fine iron is isolated by settles down in hot condition at above 50°C.

10. A process according to claim 1, wherein the fine iron is separated by decantation and washing. Fine iron whenever obtained by the process according to the proceeding claim.

The present invention discloses extraction of fine iron from Bayer Process red mud of
alumina industry. The major impurities, sodalite (L08Na2OAl2O3l.68SiO2l.8H2O), quartz (SiO2) and amorphous substances were removed only by simple decantation and centrifuged technique from red mud and red mud slurry.

Documents:

884-KOL-2009-(19-09-2012)-ABSTRACT.pdf

884-KOL-2009-(19-09-2012)-CLAIMS.pdf

884-KOL-2009-(19-09-2012)-CORRESPONDENCE.pdf

884-KOL-2009-(19-09-2012)-DESCRIPTION (COMPLETE).pdf

884-KOL-2009-(19-09-2012)-FORM-1.pdf

884-KOL-2009-(19-09-2012)-FORM-13.pdf

884-KOL-2009-(19-09-2012)-FORM-2.pdf

884-KOL-2009-(19-09-2012)-FORM-3.pdf

884-KOL-2009-(19-09-2012)-FORM-5.pdf

884-KOL-2009-(19-09-2012)-OTHERS.pdf

884-kol-2009-abstract.pdf

884-kol-2009-claims.pdf

884-kol-2009-description (complete).pdf

884-kol-2009-drawings.pdf

884-kol-2009-form 1.pdf

884-kol-2009-form 18.pdf

884-kol-2009-form 2.pdf

884-kol-2009-form 3.pdf

884-kol-2009-specification.pdf

abstract-884-kol-2009.jpg

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Patent Number

255321

Indian Patent Application Number

884/KOL/2009

PG Journal Number

07/2013

Publication Date

15-Feb-2013

Grant Date

12-Feb-2013

Date of Filing

19-Jun-2009

Name of Patentee

NATIONAL INSTITUTE OF TECHNOLOGY

Applicant Address

NATIONAL INSTITUTE OF TECHNOLOGY ROURKELA-769 008 DIST: SUNDARGARH

Inventors:

#	Inventor's Name	Inventor's Address
1	MR. RAMESH CH. SAHU	NATIONAL INSTITUTE OF TECHNOLOGY ROURKELA-769 008 DIST: SUNDARGARH
2	DR. BANKIM CHANDRA RAY	NATIONAL INSTITUTE OF TECHNOLOGY ROURKELA-769 008 DIST: SUNDARGARH
3	DR. RAJ KISHORE PATEL	NATIONAL INSTITUTE OF TECHNOLOGY ROURKELA-769 008 DIST: SUNDARGARH

PCT International Classification Number

B03B

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA