Title of Invention	A PROCESS FOR THE PREPARATION OF γ-Fe2O3 FROM THE CRUDE FERROUS SULPHATE OF STEEL PLANT
Abstract	The present invention relates to the prepration of pure γ- Fe2O3 from pickle liquor a waste product of Steel Plants. Applying the techniques of reductive dissolution an oxidative hydrolysis. After filtration the samples were ground in acetone medium, vacuum dried and roasted at 350°C. The samples confirm to γ- Fe2O3 on XRD examination.

Full Text

The present invention relates to a method for the preparation of y-Fe2O3 from crude Fe(II) sulphate waste. Ferrous sulphate is obtained as a waste from the pickle liquor of steel plants. It is estimated that about 2000 tonnes of ferrous sulphate is obtained annually from pickling vats of Rourkela Steel Plant alone. A lot of ferrous sulphate is also produced by the Indian Rare Earths Ltd. as a waste, while preparing titanium dioxide from ilmenite and disposal or utilisation of such waste has attracted considerable attention throughout the world. Ferrous sulphate solution could also be obtained by dissolving the waste iron scraps from fabrication industries in sulphuric acid. In RRL, Bhubaneswar a number of possibilities have been considered to utilise these wastes. Single phase y-Fe2C3 is an important material used as recording medium in applications such as magnetic tapes and other information storage devises like drums and discs. Its use in ferrite compositions is also well known. It is a ferrimagnetic compound with inverse spinel structures in which iron(III) cations occupy both tetrahedral and octahedral sites. Reference may be made to Magnetic Oxide, Vol.2, published by Wiley - Interscience, New York, 1975 wherein D.J. Craik described the commercial synthesis of FeaOs from synthetic goethite (a- FeOOH). It involves dehydration of goethite to areduction to Fe and final re-oxidation to - Reference may by made to J. Mater. Sci., 9 (1974) 430 wherein V. Rao etal. reported the preparation of y-FeaOa from iron(II) carboxylate, using iron(II) oxalate dihydrate as the starting material. Reference may be made to Bull. Mater. Sci., 3a (1981) 201 wherein K. Shesan et al also prepared y-Fe2O3 using iron(II) oxalate dihydrate as the starting material. Reference may be made to Thermochim. acta. 112 (1987) 231 wherein A. Venkataraman et al reported the synthesis of y-Fe2C3 from thermal decomposition of ferrous fumarate. Reference may be made to Thermochim. Acta, 115 (1987) 215, wherein A. Venkataraman et al reported the synthesis of y-Fe2O3 by thermal decomposition of ferrous succinate. Reference may be made to J. Therm. Anal. 35 (1989) 2115, wherein A. Venkataraman et al reported the synthesis of Y-Fe2O3 by thermal decomposition of ferrous tartarate. Reference may also be made to Thermochim. Acta. 125 (1988) 173, wherein M.M. Rahman et al reported the synthesis of y-Fe2O3 by thermal decomposition of ferrous malonate. The drawbacks of the processes developed are that they used pure chemicals, hence the products are costly. But in the present invention a metallurgical industry waste is used as raw material and the steps involved in the process do not require any sophisticated technology. A method is developed for the preparation of single phase y-Fe2O3 which finds use as magnetic material in recording devices. Ferrous sulphate is obtained as a waste in steel plants, as well as in synthetic rutile industry. It can be prepared by dissolving iron scraps of fabrication industries in dil sulphuric acid. However the present work has been carried out on the waste ferrous sulphate obtained from the pickling vats of steel plant. The ferrous sulphate is dissolved in dil FfeSC^ in the presence of a small amount of iron powder, filtered and diluted with half its volume of ethyl alcohol to obtain re-crystallised iron (II) sulphate heptahydrate in the pure form. Solution of this ferrous sulphate is neutralised and then treated with NaOH solution (10 % more than stoichiometrically required amount) and subjected to hydrothermal agitation at temperatures ranging from 50 to 80°C along with air bubbling for 6h. The precipitate of iron oxyhydroxide is filtered, washed, dried and identified by XRD. After roasting this material at 350°C, the product is identified by XRD to be single phase y- Fe203. The novelty of the invention is that it provides a simple and precise method for preparation of a value added product i.e. y-Fe2O3 from waste ferrous sulphate. The main objective of this invention is to develop a method for the preparation of y- FeaOs from ferrous sulphate obtained as waste in metallurgical industry. Another objective of this invention is to solve the disposal problem of an industrial waste. Still another objective of this invention is to decrease environmental pollution. Yet another objective of this invention is reduction of y-Fe2Os import. Yet another objective of this invention is to prepare pure FeSC^. VFkO after the first step of this process. Yet another objective of this invention is to prepare iron oxy hydroxide, after the second step of this process, which can adsorb heavy metal pollutants from industrial effluents and also serve as a starting material for the preparation of ferrites and pigments. Accordingly the present invention provides a process for the preparation of y-FeaOa from crude iron (II) sulphate waste, which comprises treating the iron (II) sulphate waste with dilute sulphuric acid in the presence of a small amount of iron scrap or powder, filtering and re-crystallising the FeSO4.7H2O from the above said filtrate by adding ethyl alcohol, oxidative hydrolysing the above said re-crystallised iron(II) sulphate solution by using air as oxidant and sodium hydroxide solution as precipitant, at a temperature ranging from 40 to 100 ° C to obtain iron oxy-hydroxide followed by calcination at a temperature ranging between 320 -360°C for a period of 5-7 hrs to obtain the desired yhi an embodiment of the present invention the temperature used in oxidative hydrolysis of re-crystallised iron(II) sulphate solution is preferably in the range of 50-80° C The essential steps involved in the process are as follows : (a) Treatment of FeSO4 obtained from the pickling vats of steel plants with dil FSC in the presence of a small amount of iron scrap/powder. (b) Re-crystallisation of FeSO4.7H2O from the above ferrous sulphate solution by the addition of ethyl alcohol. (c) Preparation of iron oxy-hydroxide from a solution of the re-crystallised ferrous sulphate by oxidative hydrolysis using air as oxidant and sodium hydroxide as precipitant. (d) Wet grinding of the material, prepared as above in acetone medium followed by vacuum drying. (e) Calcination of the material at 350°C for 6h to prepare 76263 The following examples are given by the way of illustration and therefore should not be construed to limit the scope of the invention. Example -1 200 ml of solution containing 28g of re-crystallised FeSC4,7H2O (A) is taken in a reaction vessel, subjected to neutralisation with 10% NaOH solution (B) till appearance of a very very faint precipitate, followed by dropwise addition of 90 ml of (B) along with stirring. The vessel is placed in a thermostatic bath maintained at 50°C and the reaction mixture inside is subjected to stirring along with air bubbling for 6h. The precipitate thus formed is filtered, washed with 2% NFLtNOs and 5% ammonia solution respectively, dried at 110 ± 5°C, subjected to wet grinding in acetone medium and vacuum drying. The iron oxyhydroxide thus formed is heated at 350°C for 6h to yield 7.5g of single phase yExample 200 ml of solution containing 28g of re-crystallised FeSO4. 7H2O (A) is taken in a reaction vessel, subjected to neutralisation with 10% NaOH solution(B) till appearance of a very very faint precipitate, followed by dropwise addition of 90 ml of (B) along with stirring. The vessel is placed in a thermostatic bath maintained at 65°C and the reaction mixture inside is subjected to stirring along with air bubbling for 6h. The precipitate thus formed is filtered, washed with 2% NFLjNOs and 5% ammonia solution respectively, dried at 110 ± 5°C, subjected to wet grinding in acetone medium and vacuum drying. The iron oxyhydroxide thus formed is heated at 350°C for 6h to yield 7.0g of single phase y-FeaOs. ExampIe-3 200 ml of solution containing 28g of re-crystallised FeSO,. THaO (A) is taken in a reaction vessel, subjected to neutralisation with 10% NaOH solution(B) till appearance of a very very faint precipitate, followed by dropwise addition of 90 ml of (B) along with stirring. The vessel is placed in a thermostatic bath maintained at 80°C and the reaction mixture inside is subjected to stirring along with air bubbling for 6h. The precipitate thus formed is filtered, washed with 2% NFLjNOs and 5% ammonia solution respectively, dried at 110 ± 5°C, subjected to wet grinding in acetone medium and vacuum drying. The iron oxyhydroxide thus formed is heated at 350°C for 6h to yield 7.0g of single phase y-FeaOa. Example-4 200 ml of solution containing 28g of re-crystallised FeSO^FfeO (A) is taken in a reaction vessel, subjected to neutralisation with 10% NaaCOs solution (B) till appearance of a very very faint precipitate followed by dropwise addition of 90 ml of (B) along with stirring. The vessel is placed in a thermostatic bath maintained at 50°C and the reaction mixture inside is subjected to stirring along with air bubbling for 6h. The precipitate thus formed is filtered, washed with 2% NFLtNOa and 5% ammonia solutions respectively, dried at 110 ± 5°C, subjected to wet grinding in acetone medium and vacuum drying. The iron oxyhydroxide thus formed is heated at 350°C for 6h to yield 7g of single phase aThe main advantages of the present invention are : 1. Development of a simple method for the preparation of y-FeaOa from crude iron(II) sulphate, a metallurgical waste. 2. The FeSO4,7H2O prepared from the crude steel plant waste can serve as a pure chemical. 3 Iron oxy-hydroxide obtained after the second step of the process can be used as a starting material for the preparation of iron based red pigments. 4. The same iron oxy-hydroxide can also serve as the starting material for the preparation of ferrite. 5. The steps adopted in this process are simple and the process is inexpensive. We Claim: 1. A process for the prepration of γ-Fe2O3 from crude iron (II) sulphate waste, which comprises: treating FeSO4.7H2O with ethyl alcohol, oxidative hydrolyzing the above said recrystallised iron (II) sulphate solution by using air as oxidant and sodium hydroxide solution as precipitant, at a temperatute ranging from 40 to 100°C to obtain iron oxy-hydroxide followed by calcination at a temperature ranging between 320-360°C for a period of 5-7 hrs to obtain the desired γ-Fe2O3 2. A process as claimed in 1, wherein the temperature used for oxidative hydrolysis is preferably in the range of 50-80°C. 3. A process for the prepration of γ-Fe2O3 from crude iron (II) sulphate waste, substantially as herein described with refrence to the examples accompanying this specification.

Documents:

1203-DEL-2002-Abstract-(27-01-2009).pdf

1203-del-2002-abstract.pdf

1203-DEL-2002-Claims-(27-01-2009).pdf

1203-del-2002-claims.pdf

1203-DEL-2002-Correspondence-Others-(27-01-2009).pdf

1203-del-2002-correspondence-others.pdf

1203-del-2002-correspondence-po.pdf

1203-del-2002-description (complete).pdf

1203-DEL-2002-Form-1-(27-01-2009).pdf

1203-del-2002-form-1.pdf

1203-DEL-2002-Form-18-(27-01-2009).pdf

1203-del-2002-form-18.pdf

1203-del-2002-form-2.pdf

1203-del-2002-form-3.pdf