FIELD OF THE INVENTION

[0001] The present invention, in general, relates to the production of high quality synthetic rutile from llmenite with no acidic or harmful by products. Particularly, the invention relates to an environmental friendly process for beneficiation of llmenite to synthetic rutile. More particularly, the present invention relates to an uncomplicated process for the production of high grade beneficiated llmenite with significant Ti02 content and saleable Iron oxide as byproduct.

DESCRIPTION OF PRIOR ART

[0002] In the prior art literature, a number of processes for beneficiation of llmenite have been established, in response to the growing need of high grade synthetic rutile. The operating plants for the production of TiO2 from natural sources such as llmenite exemplifies well known Chloride processes. Sulphate processes and various Slag based technologies. However it is too difficult to generate a sufficiently pure titanium dioxide product economically and the processes are complicated at best.

[0003] As per the prior-art literature, the commercial processes for the production of synthetic rutile namely, the Benilite (BCA), Becher, Ishihara, Murso Process have been established and some of them are limited owing to environmental hazards such as emission of acidic and harmful by products. In the midst of them the industrially well proven and currently being used as environmental friendly process is the Becher process, wherein ammonium chloride solution is used for leaching in aeration. Most of the said processes comprise steps of pre-treatment of the ore, followed by partial leaching in acids, and the process may also include Magnetic separation and/or seeding steps for the removal of Iron residues from llmenite. So as to obviate the prerequisites in the said processes, alternative methods for beneficlation of llmenite have been exemplified and patented.

[0004] For example, the Pub.No.WO2001000531 describes an economical hydrometallurgical process for producing pigment grade Ti02 from titaniferous mineral ores and in particular from llmenite ore wherein the ore is leached with hydrochloric acid solution in optimal conditions of temperature, pressure and concentrations. Further, US Pat No. 5427749 (Hollitt.et al) teaches a process for producing synthetic rutile from titaniferous ore, in which the acid leaching process using strong mineral acids under agitated conditions have been demonstrated for the removal of impurities.

[0005] US Pat No. 7780756 (Barnes , et al) teaches a process for producing separable iron and titanium oxides from an ore in a carbon bed rotary hearth furnace and mechanical separation of solid Iron metal granules from the titanium oxide-rich slag; wherein the process includes magnetic or other separation procedure for removal of impurity grains which do not metalize.

[0006] Herein is the Patent illustrated for the production of titanium dioxide from llmenite without using Magnet. The US Pat No.7008602, Pub.No. WO2003089674, and European Patent EP1499752 discloses an economical process for the beneficiation of titaniferous ore with saleable Iron as by-product, in which the acid leaching is performed by concentrated Sulphuric acid. Although the process is economical, the environmental hazards are high in comparison with the other well known processes.

[0007] Owing to the necessity of environmental friendly and simplified processes for the beneficiation of llmenite, improved version of the conventional method, Becher process (I.P No. 74905), have also been patented. For example, US Pat No. 5601630 and EP 0612854 disclose a process for the production of synthetic rutile, in which ozonated oxygen is used instead of air for aeration.

[0008] Herein is the other environmental friendly process disclosed in prior-art for beneficiation of llmenite. The Indian Patents I.P. No.196947 (Mohan das, et al) and I.P. No.230902 (Mohan das, et al), titled an improved process for the production of high grade synthetic rutile, discloses a process for the pre-treatment of llmenite and leaching of reduced llmenite with ammonium chloride and carbonyl compounds mixture. The US Pat No. 6,306,195 (Das , et al), I.P. No.218313, titled Process for the preparation of high grade synthetic rutile and pig iron, discloses a process for the preparation of high grade synthetic rutile from llmenite with pig iron as a by-product. In all these processes the coal fines and ash are removed using magnetic separation phase.

[0009] In comparison with the prior-art literature, the present invention discloses an eco-friendly process for beneficiation of llmenite without the use of magnetic separator. Moreover the present invention comprises tine steps of pre-treatment of llmenite ore at low temperature and leaching of the ore with the acid of lower concentration. Also the said process accomplishes the production of high quality beneficiated llmenite with saleable Iron oxide as by-product

[0010] Accordingly, herein disclosed an advantageous and eco-friendly process for Industrial scale production of beneficiated llmenite along with saleable Iron oxide as by-product, wherein the yield of Ti02 content is 90-92%.

SUMMARY OF THE INVENTION

[0011] It is therefore the primary objective of the present invention is to propose an environmental friendly process for beneficiation of llmenite to synthetic rutile with no acidic and harmful by products.

[0012] It is another objective of the invention is production of high grade beneficiated llmenite with significant TiOa content and saleable Iron oxide as byproduct.

[0013] It is a further object of the invention to propose a low cost and simple process for the large-scale production of beneficiated llmenite.

[0014] Accordingly, the present invention proposes an eco-friendly process for the production of high grade beneficiated llmenite, having significant Ti02 content of 90-92%, and saleable Iron oxide as byproduct, the said process comprising the steps of:

• Oxidation in the presence of air at the temperature range of 825-875°C for 30 minutes;

• Reduction using a reducing agent mixture of Petroleum Coke and Ferrous ammonium sulphate at the temperature of 900-950°C for 3-4 hours for metallization of Iron; and

• Removal of petroleum coke in vibrating screens.

• Leaching of reduced llmenite with 1 % ammonium chloride solution in the presence of air for 5hrs for the removal Iron oxide;

• Leaching with 0.5 molar dilute solution of Sulphuric acid for 2 hrs for the removal of residual Iron & other impurities; and

• Recovering the synthetic rutile by conventional method.

[0015] these and other objects, features, and advantages of the present invention will become more apparent from the ensuing detailed description of the invention.

BRIEF DESCRIPTION OF ACCOMPANYING FIGURE

[0016] The sole Figure here of is Flow Chart Illustrating beneficiation of llmenite to Synthetic rutile in accordance with the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF INVENTION

[0017] The preferred embodiments of the present invention will now be explained in detail with reference to the accompanying drawing. It should be understood however that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. The following description, examples, and drawing are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art on how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail.

[0018] The present invention discloses an environmental friendly process for beneficiation of llmenite to synthetic rutile of significant TiOa content and saleable Iron oxide as by product, as illustrated in FIG.1.

[0019] As per one of the preferred embodiments of the present invention, the llmenite ore is beneficiated by three-step process, wherein the llmenite ore is first subjected to oxidation in presence of air at a temperature of about 825-875°C for half an hour. The oxidized llmenite is then reduced using reducing agent mixture of petroleum coke and ferrous ammonium sulphate mixture in the ratio 1:0.5:0.2 at the temperature range of 950-990°C for 3-4 hours for metallization of iron. The reduced llmenite ore containing metallic Iron is then subjected to sieving by the use of vibrating screens for the removal of Petroleum Coke. The reduced ilmenite, as such without adjusting the pH, is then leached with 1 % ammonium chloride solution in the presence of air for 5 hours for the removal of Iron oxide. After removing Iron oxide from Ilmenite, the leached sample is then leached with 0.5 molar dilute solution of sulphuric acid for 2 hours for the removal of residual iron and other impurities. In the said processes, leaching occurs at the temperature of about 70-90''C and most preferably at SOX.

[0020] During the primary leaching step, the Iron in ilmenite precipitates out as ferrous oxide, which is then separated from the ore mixture using Cyclonic separation procedure. The leached liquor is then spray-dried to remove the Iron oxide as dry powder, which is saleable. As mentioned above, the leached ore mixture is then subjected to consequent leaching without the adjustment of pH. After leaching with ammonium chloride, and subsequently with dilute sulphuric acid, the processed mixture is subjected to Cyclonic separation procedure for the separation of leached ilmenite from iron oxide. Methods for recovering the beneficiated Ilmenite from the liquid phase are well known to persons skilled in the art and include, but are not limited to filtration, settling, and drying. The beneficiated ore is then dried or subjected to Calcination process in order to remove bound water and residues and to obtain high grade synthetic rutile.

[0021] Ultimately the above said process is found to yield results with Ti02 content of 90-92% in beneficiated ilmenite, and Iron oxide separated as by-product.

[0022] As per another embodiment of the present Invention, llmenite ore is beneficiated by the said process, wherein the reducing agent mixture of Ferrous Sulphate and Petroleum coke is utilized instead of Ferrous ammonium sulphate in the reduction process. The said reduction process is found to be low and the yield of beneficiated llmenite shows Ti02 content of 74-75% and residual Iron of 14-15%, at same conditions of temperature.

[0023] Accordingly the present Invention exemplifies a process for up-gradation of Ti02 content by the usage of ferrous ammonium sulphate as a reducing agent mixture.

[0024] The Invention is now illustrated by, but is not limited to, the following examples:

Example 1

[0025] Ten Kgs of raw llmenite containing 55-59% TiOa and 25-26.5% total iron is air oxidised for half an hour in a furnace at 850°C. The air oxidised ilmenite is then reduced with 2 Kgs of ferrous ammonium sulphate and 5 Kgs of pet coke for 3-4 hrs at a temperature of about 950°C in a furnace. The reduced ilmenite after removal of petroleum coke is leached with 1% solution of ammonium chloride with air purging at a temperature of 80°C. The pH of the solution is as obtained and is leached for 5 hrs. After ammonium chloride leaching and removal of Iron oxide, the leached ilmenite is again leached with a 0.5 molar solution of concentrated sulphuric acid at 80°C for 2 hours. The leached ilmenite is dried and analysed and was found to have 90-92% TiOa and only 4-5% of residual Iron.

Example 2

[0026] Ten Kgs of raw ilmenite containing 55-59% Ti02 and 25-26.5% total iron is air oxidised for half an hour in a furnace at 850°C. The air oxidised ilmenite is then reduced with 2 Kgs of ferrous sulphate and 5 Kgs of petroleum coke for 3-4 hrs at a temperature of about 950°C in a furnace. The reduced ilmenite after removal of petroleum coke is leached with 1% solution of ammonium chloride with air purging at a temperature of 80°C. The pH of the solution is as obtained and is leached for 5 hrs. After ammonium chloride leaching and removal of Iron oxide the leached ilmenite is again leached with a 0.5 molar solution of concentrated sulphuric acid at 80°C for 2 hours. The leached ilmenite is dried and analysed and was found to have 74-75% TiOa and residual Iron of 14-15 %.

[0027] While using ferrous ammonium sulphate in the reducing agent mixture, the reduction process is improved, and the metallization of Iron is faster, at the optimum temperature. Further, the yield of TiOa content is upgraded to 90-92% wherein the residual Iron is 4-5% only. The above result clearly indicates that the usage of ferrous ammonium sulphate as a reducing agent is beneficial for up-gradation of Ilmenite.

[0028] It will be obvious to those skilled in the art that other control methods and apparatuses may be derived from the combinations of the various methods and apparatuses of the present invention as taught by the description and the accompanying drawings and these shall also be considered within the scope of the present invention. Further, description of such connbinations and variations is therefore omitted above.

CLAIMS

We Claim:

1. An eco-friendly process for the production of high grade beneficiated llmenite, having significant Ti02 content in the range of 90-92%, and saleable iron oxide as byproduct, the said process comprising the steps of:

• oxidation of llmenite in the presence of air;

• reduction of llmenite using reducing agent mixture; and

• leaching of reduced llmenite primarily with dilute solution of ammonium chloride and blowing air, and subsequently with Sulphuric acid.

2. The process as claimed in claim 1, wherein the oxidation is carried out at a temperature range of 825-875°C, for at least 30 minutes.

3. The process as claimed in claim 1, wherein the reduction is carried out at a temperature from about 950°C to about 990°C, for at least 3-4 hours.

4. The process as claimed in claim 1, wherein the reducing agent mixture is a combination of Ferrous ammonium sulphate and Petroleum Coke in a substantial ratio.

5. The process as claimed in claim 1, wherein petroleum coke is removed subsequent to reduction using vibrating screens.

6. The process as claimed in claim 1, wherein the concentration of ammonium chloride solution for primary leaching is 1%.

7. The process as claimed in claim 1, wherein the concentration of sulphuric acid for leaching is 0.5 Molar.

8. The process as claimed in claim 1, wherein leaching is performed at a temperature range of 70-90°C.

9. The process as claimed in claim 1, wherein the saleable Iron oxide powder is obtained by Cyclonic separation procedure.

10. The process as claimed in claim 1, wherein high grade Synthetic rutile is recovered from the processed mixture using suitable means.