Title of Invention

AN IMPROVED PROCESS FOR THE PRODUCTION OF HIGH GRADE SYNTHETIC RUTILE

Abstract

An improved process for the production of high grade synthetic rutile which comprises: a) heating ilmenite with coal at a temperature in the range of 850-1250°C with 30 - 100% coal for 0.5 to 8 hrs till the complete reduction of iron oxide to metallic state. b) cooling rapidly the resultant of step (a) to room temperature and removing the unreacted coal and ash by known physical methods selected from sieving, magnetic separation, c) oxidising the product obtained in step (b) in presence of air and catalyst in an aqueous medium comprising of 0.5 - 2.5% NH4CI and 0.1 to 10% of carbonyl compounds at a solid liquid ratio of 0.2 to 0.6% at a temperature of 20 to 35°C for a period of 1 - 8 hrs, d) separating the iron oxide from the said product obtained in step (c) by washing with water, e) rutilating the product obtained in step (d) after removal of iron oxide by heating in presence of air at a temperature in the range of 650 - 900°C. for 0.15 to 2 hrs., f) leaching the said rutilated product obtained in step (e) with dilute mineral acid such as herein described, in the conventional way at a temperature of 50 - 100°C and recovering the synthetic rutile by filtration, washing and drying

Full Text

This invention relates to an improved process for the for the production of high grade synthetic rutile. Synthetic rutile prepared by this process is useful as (i) Starting material for producing Ti02 pigment, (ii) Starting material for the production of titanium metal, (iii) Welding electrode flux material, (iv) In certain types of colour paints in place of Ti02 pigment. The present invention provides an improved process for producing high quality synthetic rutile through a catalytically enhanced process devoid of many of the pollution problems associated with the present methods. So the industries to which the invention can apply are: Ti02 pigment and titanium metal manufacturing industries and ilmenite processing industries. Natural rutile which is the starting material for the chloride route of processing is scarce in nature while ilmenite which is the titanium mineral is abundantly available. Hence it becomes essential to prepare synthetic rutile from ilmenite which can be used in place of natural rutile. Many routes have been reported for the production of synthetic rutile by different workers, but only very few of them have been found to be attractive industrially. A number of review articles have appeared on the beneficiation of ilmenite to synthetic rutile. A few of them are by S.K. Jain et al (Ind. J. Technol. 15(9), 1977, 398-402), P.K. Jena et al (Ban. Met., 5, 1973, 107- 117), J.A. Kahn (J. Metals, July 1984, 33-38), Moldran lullu et al (Chem. Abstr., 84 (1976), 78476 p) and S. Yamada (Ind. Minor., London, 100, 1976, 33-40). The different methods available for the preparation of synthetic rutile can be classified based on the physico chemical principles involved in the processing as given below. In the fusion method ilmenite is fused with alkali- metal compounds such as NaOH, Na^CO-,, NaHSOA, Na9S, etc. to convert it £* O ft £ » , k to a soluble product. It is then leached with acids and titanium and iron values are recovered from the solution (E.M. Khairy, M.K. Hussain and K.A. Baraway, NML Tech. J., 10 (4) 1968; K.V.V. Nair, Bull. Central Res. Instt., Uni. Travancore, 11 (1952), 106; A.K. Sharova and A.A. Fotiyev, Izev. Sibirskogo. Otd. Akad. Nauk. S.S.S.R., 4 (1959) 52; Y. Tokimoto and H. Hattori, J. Chem. Soc. Jpn. Ind. Chem. Soc., 58 (1955) 654; S. Prasad and J.B.P. Tripathi, Ind. J. Appl. Chem., 21 (1958), 162; A.S. Gaskin and A.E. Ringwood, Australian Patent 222517 (1959); G. Jabsen, Norwegian Patent 21693 (1910), Chem. Abstr., 6 (1912) 2153; L.E. Barton, U.S. Patent 1201541 (1917), Chem. Abstr., 11 (1917) 279; Fr. Patent 483780 (1917), Chem. Abstr. 12 (1918) 1000; Br. Patent 106585 (1916), Chem. Abstr. 11 (1917) 2575; Norwegian Patent 29194 (1918); Chem. Abstr. 14 (1920) 1418; Belgian Patent 447709 (1942), Chem. Abstr. 41 (1947) 7064; H.H. Hoekje and R.A. Kearley, Ger. Patent 1058463 (1959), Chem. Abstr. 55 (1961) 5892; I A.K. Sharova and A.A. Fotipev, Chem. Abstr. 53 (1959) 20717, T. Shino, T. Tanaka, Y. Tanaka and Y. Takimoto, Jap. Patent 8771 (1950). The fusion method has not become commercially attractive as it has got a number of problems like large quantity of effluents, corrosion and high cost of the chemicals which make it economically unattractive. Another method for the preparation of synthetic rutile is direct acid leaching using mineral acids like H2S04 and HC1. The Ti02 and iron oxide present in ilmenite get dissolved in H^SO^ on digestion. On digestion with HC1 only the iron oxide present gets dissolved selectively (E.N. Kramer, U.S. Patent 2437164 (1948); British Titan Products Company Ltd., Br. Patent 1085359 (1967); Ching-Lung Lo and T.S. Mackey, Wah Chang Corp. U.S. Patent 3193376 (1965); G.S. Davar Ind. Patent 124558 (1969), Kenzo Ishihara Outline of Ishihara Sangyo Kaisha Ltd. (1970); Columbia Southern Chemical Corp. , Br. Patent 795164 (1958); N.N. Murach and L.G. Povedskaya USSR Patent 116155 (1958); N.A. Aawal, M. Rehman, S.A. Tarafder and A.M.S. Hug. Chem. Abstr. 85 (1976) 146321 g). Partial reduction of ilmenite followed by acid leaching is another method which is used industrially at various parts of the world. Carbon is usually used as the reductant where the ferric oxide present in ilmenite is reduced to the ferrous state. The iron is then removed by leaching with mineral acids. Under this category a number of techniques are used with minor variations. The important ones among them are the following (R.I; Jaffe-"and H.M. Burte, Titanium Sci. and Technol. Vol. I (Eds.); R.I. Jaffe * .. .. :'•" and H.M. Burte, Plenum Press, New York, London 1973; J. Burastero, Chem. Abstr. 89 (1978), 26787 z; T. Kurata, M.E. Emi Satoshi, 0. Kunihiko, T. Tstutomu and S. Isamu, Jpn. Kokai 7693714 (1976). Certain ilmenites were found to be easily reducible after a preoxidation. Srilankan ilmenite was found to have such a behaviour (M.G. Mu. Ismail, J. Amarashekara and J.S.N. Kumarasinghe, Intl. J. Miner. Process 10(2) 1983, 161-164). A careful preoxidation and reduction of ilmenite followed by acid leaching was suggested by Kerr. Me. Corp (Rado Theodore A., C. Kerr Me. Corp., U.S. Pat. 4199552 (1980). Ilmenite was subjected to reduction using coal where the iron oxide was converted to the metallic state which was then converted to the oxide by aqueous aeration rusting in presence of a catalyst (B.F. Bracanin, R.J. Clements and V. John, Proc. Austr. Inst. Min. Metall., 275 (1980) 33-42). Indian ilmenite was subjected to reduction followed by acid leaching which gave a synthetic rutile with about 2-3% iron. (Annie George, V.S. Kelukutty, L.G. Radhika, P.N. Mohan Das and P.K. Rohatgi, J. Mater. Sci., 19 (5) (1984, 1522). Electrolytic dissolution of the metallic iron from reduced ilmenite for the production of synthetic rutile with high Ti02 content was also reported (Allan Benjamin Wils6n,':':.Ger. Offen. 2557411 (1977, Mori. Tado Oshi, Kato Akemi and" Kawakami Naboru, Jpn. Kokai, 77128817, (1977). Grey et al have reported a process where ilmenite is reduced with coal which is then subjected to acid leaching before or after aeration rusting (I.E. Grey, M.J. Hollit, A. Brian, B. O'Brien, Austr. Pat., 9346047 (1993), Austr. Pat. 649946 (1994), U.S. Pat. 5427749 (1995)). In another process reduced ilmenite was subjected to aqueous oxidation and then high temperature acid leaching (Ishihara, Sangio, Kaisha, Japn. Pat. 58199720 (1983)). Reduction of ilmenite followed by the oxidation of metallic iron in aqueous solution in presence of ozone or oxygen followed by acid leaching for the preparation of synthetic rutile is also reported (H. Walter, European Pat. 612654 (1994). Solid state reduction followed by oxidation and acid leaching of Indian ilemnite for producing synthetic rutile was also reported (P.N. Mohan Das, A.D. Damodaran, S. Velusamy and S. Sasibhushanan, Ind. Pat. 1033/DEL (1991). A better quality synthetic rutile with brownish yellow colour was prepared from Indian ilmenite by subjecting the ilmenite to metallisation, aeration rusting, rutilation and acid leaching (P.N. Mohan Das, A.D. Damodaran, K.H. Bhat, S. Velusamy and S. Sasibhushanan, Ind. Pat. 1262/DEL 1997). Direct chlorination of ilmenite in presence of carbon at "'8SO°C-950°C where iron chloride and titanium tetrachloride are formed is another method for processing ilmenite. The chlorides were then separated and TiCl4 was oxidised to give Ti02. (D. Wendel D.C. Jr. U.S. Pat. 4332615 (1982), U.S. Pat. 4085189 (1978); J.K. Heymer, G. Stephan and H. Werner, Ger. Offen. 3203482 (1983)). Another important method for processing ilmenite is the reduction smelting in electric arc furnace. As this is a highly energy intensive process it is practised in places where cheap and abundant electrical energy is available. In this process reduction and smelting of ilmenite are simultaneously carried out in an electric arc furnace in presence of carbon. This process is commercially practised in Sorel, Canada and the titania rich slag produced is used for the production of Ti02 pigment through the sulphate route (G.W. Elger, B.E. Kishi, S.E. Rhoads, U.S. B.M.R.I. 8140 (1976, 31); D.J. Swinden and D.G. Jones, Trans. Inst. Min. Metall. Sec. C, 87 (1978) 83-87; A.J. Merchant and N.A. Warner, Trans. Inst. Min. Metall. C, 101 (1992), 177-182, R.H. Nifziger, Trans. Inst. Min. Metall. C. 87 (1978) 120; P.K. Mishra, S.K. Singh, B.C. Acharya, B.C. Mohanty and P.K. Sahoo, Min. Processing, Recent Advances and Future Trends, Conf. Proc. (1995) 875-878, (Eds.) S.P. Mehrotra and Shekar Rajeev, Allied • •£• Publ., New Delhi; G.M. Denten, A. Schoukens and S. Francois, European Pat. 583126 (1994). Application of plasma for the production of Ti02 slag has been reported (W.H. Gauvin, M.G. Drouet and R.J. Munz, Jnl. of Metals, Dec. 1987, 14-17). Another process is reported for the production of TiC^ rich slag where prereduced ilmenite is smelted in a plasma furnace producing pig iron and slag which is more economical than the arc smelting (A.D. Damodaran, P.N. Mohan Das, K.H. Bhat, B.C.R. Mohanty and P.S. Mukherjee, Ind. Patent 804/DEL/1997. Out of the various processes proposed by a number of researchers the ones which are put into practise for commercial production are very few. They are (i) partial reduction followed by acid leaching which has got the disadvantage that all the iron values are going to the effluent adding to pollution problems. Also high temperature and high pressure leaching is required. (ii) In the slag process even though the iron values are recovered as pig iron the electrical energy consumption is very high for the process which makes it unsuitable for places where electrical energy is not available at lower cost. Moreover the Ti02 content Of the slag is low. (iii) The process which is followed in Australia where the iron oxide present in ilmenite is reduced to metallic state followed by catalytic oxidation and acid leaching is more environment friendly as most of the iron is removed "as • ^ solid iron oxide. The main disadvantage of the process/.is that the catalytic conversion of metallic iron to iron oxide is very slow. In the actual process reduced ilmenite has to be suspended in NH4Cl solution and aerated upto 14 to 16 hrs which seriously affects the productivity of the plant. Any improvement in the reduction, rusting (catalytic oxidation) and leaching process will be highly desirable considering the fact that the process is more environment friendly. One of the steps where improvement is highly required is the catalytic oxidation of reduced ilmenite. The process has to be accelerated whereby all the metallic iron has to be converted to iron oxide within a minimum time. The main object of the present invention is to improve the rate of the catalytic oxidation of reduced ilmenite whereby the process time can be reduced considerably. We have observed that certain chemical compounds added to the system help in faster removal of iron as oxide. We have found that certain carbonyl compounds individually or in combination (0.1 to 10%) when added to the NH4C1 (1 to 2.5%) catalyst during the catalytic oxidation reduces the processing time to nearly half. Various compounds like formaldehyde, acetaldehyde, glyoxal, glucose, sucrose, starch, acetone,- acetfe acid, methanol, ethanol etc. which contain carbonyl' groupjs favour faster completion of the reaction. In the process which is presently used for the preparation of synthetic rutile reduced ilmenite containing metallic iron is subjected to catalytic oxidation using NH^Cl as catalyst. During the process the metallic iron is converted to solid iron oxide which is separated from the system. This reaction is very slow and takes upto 14 to 16 hrs for completion. This delay in completion of the reaction seriously affects the productivity of synthetic rutile by this method. Even after the rusting reaction, it was observed that about 8 to 15% of iron remains in the product unremoved and the Ti02 content is 80-85%. An improvement in the process not only decreases the iron content in the product but also will help in reducing the processing time to nearly half as this step is the most time consuming in the flow sheet. Accordingly the present invention provides an An improved process for the production of high grade synthetic rutile which comprises: a) heating ilmenite with coal at a temperature in the range of 850-1250°C with 30 - 100% coal for 0.5 to 8 hrs till the complete reduction of iron oxide to metallic state. b) cooling rapidly the resultant of step (a) to room temperature and removing the unreacted coal and ash by known physical methods selected from sieving, magnetic separation, c) oxidising the product obtained in step (b) in presence of air and catalyst in an aqueous medium comprising of 0.5 - 2.5% NH4CI and 0.1 to 10% of carbonyl compounds at a solid liquid ratio of 0.2 to 0.6% at a temperature of 20 to 35°C for a period of 1 - 8 hrs, d) separating the iron oxide from the said product obtained in step (c) by washing with water, e) rutilating the product obtained in step (d) after removal of iron oxide by heating in presence of air at a temperature in the range of 650 - 900°C. for 0.15 to 2 hrs., a) leaching the said rutilated product obtained in step (e) with dilute mineral acid such as herein described, in the conventional way at a temperature of 50 -100°C and recovering the synthetic rutile by filtration, washing and drying In a preferred embodiment of the invention the reduction was carried out with coal ranging from 30 - 100% w/w of ilmenite for a period ranging from 2 - 5hrs. The unreacted coal & ash is removed by known physical methods such as sieving, magnetic separation. In another feature of the invention is the catalytic oxidation is effected by suspending the reduced ilmentite in a mixture of 1 to 2.5% (w) NH4CI and 0.1 to 10% carbonyl compound(s) at a solid liquid ratio of 0.2 to 0.6% for a period upto 8 hrs. Carbonyl compounds used are selected from glyoxal, methanol, formaldehyde, acetone, acetic acid, starch, glucose, sucrose, ethyl alcohol, formic acid, etc. In this process maximum quantity of iron is removed in lesser time thereby increasing the efficiency of the reaction. When NH4CI alone is used the enrichment in terms of TiC>2 is only 82.5% in 8 hrs which has been increased to about 91% when these compounds are used. This shows that more quantity of iron is getting removed as solid oxide thus reducing the load on the acid leaching or even avoiding the necessity of leaching thereby reducing the effluents and consequently the pollution problems. The synthetic rutile prepared by this method is of better quality which should be a much better raw material for chlorination as the Ti02 content is higher. The reduction is effected at temperatures above 950°C rutilation if required between 700-800°C and the leaching if required may be carried out at about 85°C or above. Reduction of ilmenite is carried out with coal at 850 to 1250°C for 2 to 5 hrs where the iron oxide present in ilmenite gets reduced to metallic iron. After cooling it was sieved for removing the unreacted coal. Coal fines and ash were removed by magnetic separation. Reduction was carried out in rotary kiln. For converting the metallic iron to the oxide through the catalytic oxidation, reduced ilmenite was suspended in an aqueous solution containing 1 to 2.5 percentage (w/w) NH^Cl and the carbonyl compound or its mixtures (0.1 to 10% v/v or w/v). The solid to liquid weight ratio was maintained from 0.05 to 0.5. The pH of the solution was adjusted to 3 to 5 if required with HC1. Air was bubbled through the suspension with continuous stirring. After the completion of the reaction which takes 5 to 8 hrs, the iron oxide was separated and the ilmenite was washed well. Rutilation of the product was carried out by heating the beneficiated ilmenite containing 3 to 6% iron in presence of air at 650 to 900°C when the ferrous oxide as well as metallic iron if present gets oxidised to ferric oxide. The rutilated ilmenite is given a mild acid wash if needed with dil. HC1 for 2 to 6 hrs at temperatures upto 90°C. After cooling and filtration the product was washed with water and dried. The invention is described in detail *in the following examples which are provided by way of illustrations only and should not be construed to limit the scope of the invention. Reduced ilmenite prepared in a commercial rotary kiln was used for all the experiments and the conditions used were as described earlier. The rutilation and acid leaching conditions were also the same for all the experiments, as given earlier. Hence these steps are not described in the following examples. EXAMPLE ii 125 gms of reduced ilmenite was suspended in 500 ml of 1.5% (w/w) NH4C1 and the pH was adjusted to 4 with HC1. Air from a blower was bubbled through the solution at the rate of 2-5 litres/min. with continuous stirring of the suspension. The speed of the stirrer was adjusted at 700 to 1100 r.p.m. The reaction was allowed to continue upto 12 hrs. Samples were regularly taken, washed, dried and analysed for iron and Ti02 content after removal of iron oxide. The experiments were repeated several times. It was observed that when NH4C1 alone was used the iron removal was very slow. After 8 hrs of reaction the total iron and Ti02 contents of the sample were 12.96% and 82.51% respectively, while after 12 hrs the values were 9.70 % and 84.58% respectively. This experiment is taken as the reference for comparison. All further experiments given in the following examples were done using 125 g of reduced ilmenite and 500 ml of the solution containing 7.5 g of NH4C1 and the required volume or weight of the particular carbonyl compound or their mixtures. Stirring rate was the same for all the experiments at 700 to 1100 r.p.m. Air flow was at the rate of 2 to 5 lits/min. All the experimental conditions and preparation of the sample as well as analytical methods were the same for all the experiments. Typical examples using the various compounds and results are given below. EXAMPLE 2 Glyoxal Amount of glyoxal used was 10 ml of 40% glyoxal solution. Free acid was not added as the pH was 4. Results: (Table Removed) EXAMPLE 3 Methanol Amount of methanol added was 15 ml. pH was not adjusted since it was already 4. Results: (Table Removed) EXAMPLE 4_i Formaldehyde Amount of formaldehyde added was 9.4 ml of 37-41% solution. pH was not adjusted since it was already 4. Results: (Table Removed) The product obtained after catalytic oxidation for 8 hrs containing 89.27% Ti02 was rutilated at 750°C for half an hour.It was then leached with 20% HC1 at 80-90°C with a solid content of 50% for 3 hrs. The product was filtered, washed, dried and analysed. The synthetic rutile thus obtained had a Ti02 content of 94.87% and total iron 1.5% and was light brown in colour. EXAMPLE 5_L Acetone Amount of acetone used 15 ml. No free acid was added as the pH was 4. Results: (Table Removed) EXAMPLE 6 Acetic acid Amount of acetic acid added was 7 ml and the pH was 4 on adding the acid. Results: (Table Removed) EXAMPLE 7: Starch 15 g starch was added and con. HC1 was added to adjust the pH to 4. Results: (Table Removed) EXAMPLE 8 Glucose Amount of glucose added was 10 g. pH was adjusted using cone HC1. Results (Table Removed) EXAMPLE 9 Sucrose Amount of sucrose added was 15 g. pH was adjusted using cone. HC1. Results: (Table Removed) EXAMPLE 10: Mixture of methanol and acetic acid Amount of methanol added was 10 ml and acetic acid added was 5 ml. pH was not adjusted. Results: (Table Removed) The product obtained after aeration for 8 hrs was subjected to acid leaching at 80-90°C for 3 hrs using 20% HC1 with a solid content of 50%. The product was filtered, washed, dried and analysed which was found to contain 96.79% Ti02 and 2.2% total iron which is considered as a high grade synthetic rutile. EXAMPLE 11: Mixture of Glyoxal and acetic acid Amount of glyoxal added was 10 ml and acetic acid added was 5 ml. pH was not adjusted. Results: (Table Removed) EXAMPLE 12: Mixture of ethanol and acetic acid Amount of ethanol added was 10 ml and acetic acid added was 5 ml pH was not adjusted. Results: (Table Removed) EXAMPLE 13: Mixture of Sucrose and Acetic acid Amount of sucrose added was 10 gms and cone, acetic acid 5 ml. pH 4 on adding acetic acid. Results: (Table Removed) EXAMPLE 14: Mixture of Acetone and acetic acid Amount of acetone added was 10 ml and cone, acetic acid 5 ml. pH was not adjusted. Results: (Table Removed) EXAMPLE 15: Mixture of glyoxal and acetone Amount of glyoxal (40%) added was 7.5 ml and that of acetone 7.5 ml. pH was 4 on addition and hence acid was not added. Results: (Table Removed) EXAMPLE16: Mixture of Methanol and Acetone Amount of methanol added was 10 ml and that of acetone 5 ml. pH was 4 on addition and hence acid was not added. Results: (Table Removed) EXAMPLE 17: Mixture of Formic acid and acetic acid Amount of formic acid added was 10ml and of acetic acid 5ml. pH of the solution was not adjusted. Results: (Table Removed) Quilon ilmenite and commercially available NH4Cl, HC1 and other carbonyl compounds were used for these experiments. The broad limits of the reaction conditions are as follows: Reduction temperature should be between 950°C and 1100°C with excess of carbon with a residence time of 3 to 4 hrs. Catalytic oxidation reactions may be carried out at room temperature with 0.5 to 10 percentage (w/v or v/v) of the carbonyl compound with or without the adjustment of pH. Rutilation if needed should be carried out at 700 to 900°C and the oxidation should be complete which takes upto 2 hrs. Acid leaching if required should be carried out below 90°C with dil. HC1. Leaching time ranges from 1 to 8 hrs. When NH4Cl is used as the catalyst even though major portion of metallic iron gets converted to iron oxide a good quantity of iron is still left in the product without conversion which has to be dissolved out using acids. This necessitates the acid leaching step whereby some quantity of ferric chloride is generated as effluent. When the carbonyl compounds are used as catalysts very small quantity of iron is left behind in the product which shows that the catalytic conversion reaction- takes place more efficiently probably converting all the metallic iron to iron oxide. When the individual carbonyl compounds are used as catalysts, after the reaction the TiC>2 content in the product reaches nearly 90% containing less than 7% iron. This shows that about 1-2% of metallic iron is unreacted which however can be removed by rutilation and acid leaching. When a mixture of two of the compounds are used almost all of the metallic iron as well as some of the oxide is getting removed giving a product with high TiOo content probably avoiding the necessity of acid leaching. This becomes significant because if acid leaching is avoided or if the iron removed by acid leaching is very less the process becomes highly enviro friendly producing no or very less effluents. This process is suitable for processing reduced ilmenites with lower metallisations as even the unreduced iron oxides are getting removed during the reaction. The product obtained in this process is high grade synthetic rutile which can be used as the starting material for the production of TiC^ pigment and titanium metal through the chloride route. This material can also be used as the welding electrode flux material. The product is black without rutilation while with rutilation it will be light brown in colour. We Claim: 1. An improved process for the production of high grade synthetic rutile which comprises: a) heating ilmenite with coal at a temperature in the range of 850-1250°C with 30 - 100% coal for 0.5 to 8 hrs till the complete reduction of iron oxide to metallic state. b) cooling rapidly the resultant of step (a) to room temperature and removing the unreacted coal and ash by known physical methods selected from sieving, magnetic separation, c) oxidising the product obtained in step (b) in presence of air and catalyst in an aqueous medium comprising of 0.5 - 2.5% NH4CI and 0.1 to 10% of carbonyl compounds at a solid liquid ratio of 0.2 to 0.6% at a temperature of 20 to 35°C for a period of 1 - 8 hrs, d) separating the iron oxide from the said product obtained in step (c) by washing with water, e) rutilating the product obtained in step (d) after removal of iron oxide by heating in presence of air at a temperature in the range of 650 - 900°C. for 0.15 to 2 hrs., f) leaching the said rutilated product obtained in step (e) with dilute mineral acid such as herein described, in the conventional way at a temperature of 50 - 100°C and recovering the synthetic rutile by filtration, washing and drying. 2. An improved process as claimed in claim (1) wherein the reduction was carried out with coal ranging from 30 to 100% w/w of ilmenite for a period ranging from 2 to 5 hrs. 3. An improved process as claimed in claims 1 to 2 wherein the catalytic oxidation is effected by suspending the reduced ilmenite in a mixture of 1 to 2.5% (w/w) Mm Cl and 0.1 to 10% (v/v) carbonyl compounds at a solid liquid ratio of 0.2 to 0.6 for a period upto 8 hrs. 4. An improved process as claimed n claims 1 wherein the carbonyl compound is selected from glyoxa, methanol, formaldehyde, acetone, acetic acid, starch, glucose, sucrose, ethyl alcohol & formic acid . 5. An improved process for the production of high grade synthetic rutile substantially as herein described with reference to the examples.

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