Title of Invention	A PROCESS FOR THE PREPARATION OF PIGMENT GRADE TITANIUM DIOXIDE FROM ILMENITE AND/OR TITANIA SLAG
Abstract	The present invention provides a process for the preparation of pigment grade titanium dioxide by reacting titanium ore or slag with sulphuric acid to obtain the filter cake. Extracting titanium sulphate and iron sulphate from the filter cake treating it with water or sulphuric acid followed by filtration and calcining the residue to obtain titanium dioxide. Hydrolyzing the sulphate containing filtrate to obtain the titanium dioxide hydrate, followed by calcining to obtain the desired titanium dioxide pigment.

Title of Invention

A PROCESS FOR THE PREPARATION OF PIGMENT GRADE TITANIUM DIOXIDE FROM ILMENITE AND/OR TITANIA SLAG

Abstract

The present invention provides a process for the preparation of pigment grade titanium dioxide by reacting titanium ore or slag with sulphuric acid to obtain the filter cake. Extracting titanium sulphate and iron sulphate from the filter cake treating it with water or sulphuric acid followed by filtration and calcining the residue to obtain titanium dioxide. Hydrolyzing the sulphate containing filtrate to obtain the titanium dioxide hydrate, followed by calcining to obtain the desired titanium dioxide pigment.

Full Text	The present invention relates to a process for preparation of pigment grade titanium dioxide from ilmenite and/or titania slag . The titanium dioxide, TiO2 occurs in nature in the form of rutile, anatase and brookite. It is of outstanding importance as a white pigment because of its scattering properties, its chemical stability and lack of toxicity. It is also an important inorganic pigment in terms of the quantity produced. Besides this, titanium dioxide has utility in plastic, paint industries and also finds use for production of titanium. Hither to known existing chemical processes where pigment grade titania is produced by two different ways i.e., sulfate route and chloride route. The sulphate process depends on the break down of the titanium containing raw materials such as ilmenite with concentrated sulphuric acid followed by hydrolysis and calcinations of the hydrate to produce titanium dioxide and a lots of spent acid is generated along with the Iron (II) sulphate. In the chloride route the raw materials are chlorinated at 900-1200°C. Titanium tetrachloride is separated by distillation and the same is burnt at 900-1400°C to form TO2. Reference to the same are made here (JOM, April, 1994; US patent no.5830420, 3rd Nov. 1998; US patent 5, 277, 816, Jan 11, 1994; US patent 4, 986, 742 Jan, 22, 1991; J Barksdale, Titanium 2nd edition, Ronald press comp.. New York, 1966, p 240; Dupont US 2098025, 1935, US 2098055, 1935). The hither to known sulphate processes have got some disadvantages that it generates lots of waste materials including excess spent acid, iron (II) sulphate causing lots of pollution problems. Cases are there where this wastes are dumped in the sea which has resulted the sea water pH very low. This has drawn attention of pollution departments and environmentalist. In the invented process the above said disadvantages are to certain extent overcome by putting a few novel steps in the sulphate route circuit. The main objective of the present invention is to develop a process for preparation of pigment grade titanium dioxide. Another objective of the invention is to utilize ilmenite and/or titanium slag, sulphuric acid as the raw materials. Accordingly the present invention provides a process for preparation of pigment grade titanium dioxide from ilmenite and/or titania slag, the said process comprising the steps of: a) reacting titania ore or slag with 50-100% sulphuric acid with solid to liquid ratio ranging between 1:4 to 1:10, for a period of 5- 8 hrs to obtain a liquid slurry, b) filtering the above said slurry, followed by washing with water to obtain a filter cake, c) recycling the filtrate as obtained from step b to step a, d) treating the above said filter cake obtained in step (b), with water or dilute sulphuric acid to eatract the titanium sulphate or iron sulphate , follwed by filtration to obtain a residue and a filtrate, e) calcining the above said residue obtained in step(d), at a temperature of 850-950°C to obtain the calcined titanium dioxide. f) hydrolyzing the sulphate containing filtrate solution obtained in step (d) at temperature of 90°C-100°C to obtain the titanium dioxide hydrate and g) calcining the above said hydrate at a temperature of t 850-950°C for a period of 10-20 minutes to obtain the desired titanium dioxide pigment. In an embodiment of the present invention the titanium ore used is ilmenite In still another embodiment the titanium slag used is obtained by plasma smelting of ilmenite. The novelty of the present invention lies in the use of titanium slag as the raw material and the use of water or dilute sulphuric acid as solvent for the extraction of titanium sulphate which ultimately reduces the production of spent material and makes this process eco-friendly. The following typical example given below is to illustrate how the invention is carried out in actual practice and should not be construed to limit the scope of this invention Example - 1 100 g. of titania slag containing titania (76.6%) is made to react with sulphuric acid (50%) at a solid to liquid ratio 1:8 for a period of 6 hours to form a slurry. This slurry is decanted, filtered and washed. The filtrate and wash water were recirculated to the initial step. Then the titanium sulphate and iron sulphate were extracted by putting the water or dilute sulfuric acid. Then the solution was filtered to get the residue which on calcinations at 900°C gives calcined titanium dioxide. The sulphate containing solution was hydrolysed at 96-99°C and titanium hydrate thus formed is calcined at 700°C for 15-30 minutes to produce pigment grade titanium dioxide. Example - 2 Titania slag containing 85% titania made from plasma smelting of ilmenite is made to react with hot sulphuric acid (80%) at a solid to liquid ratio 1:5 for a period of 6 hours to form a slurry. This slurry is decanted, filtered and washed. The filtrate and wash water were recirculated to the initial step. Then the titanium sulphate and iron sulphate were extracted by putting the water or dilute sulphuric acid. Then the solution was filtered to get the residue which on calcinations at 900°C gives calcined titanium dioxide. The sulphate containing solution was hydrolysed at 96-99°C and titanium hydrate thus formed is calcined at 700°C for 15 -30 minutes to produce pigment grade titanium dioxide. The advantages of the invention are following.: a) The process involves inclusion of few novel steps in the sulphate route circuit. b) The process involves use of titania slag as the raw materials. c) The process produces both anatase and rutile grade titania unlike in the conventional sulphate process. d) The process is environmentally pollution free process. We claim 1. A process for preparation of pigment grade titanium dioxide from ilmenite and / or titania slag, the said process comprising the steps of: a) reacting titania ore or slag with 50-100% sulphuric acid with solid to liquid ratio ranging between 1:4 to 1:10, for a period of 5-8 hrs to obtain a liquid slurry, b) filtering the above said slurry, followed by washing with water to obtain a filter cake, c) recycling the filtrate as obtained from step b to step a, d) treating the above said filter cake obtained in step (b) with water or dilute sulphuric acid to extract the titanium sulphate or iron sulphate , followed by filtration to obtain a residue and a filtrate, e) calcining the above said residue obtained in step(d), at a temperature of 850-950°C, to obtain the calcined titanium dioxide, f) hydrolyzing the sulphate containing filterate solution obtained in step (d), at temperature of 90°C-100°C, to obtain the titanium dioxide hydrate and g) calcining the above said hydrate, at a temperature of 850-950°C, for a period of 10-20 minutes to obtain the desired titanium dioxide pigment. 2. A process as claimed in claim 1, wherein the titanium slag used is obtained by plasma smelting of ilmenite. 3. A process for preparation of titanium dioxide from ilmenite and /or titania slag substantially as herein described with reference to the examples.

Full Text

The present invention relates to a process for preparation of pigment grade titanium dioxide from ilmenite and/or titania slag .
The titanium dioxide, TiO2 occurs in nature in the form of rutile, anatase and brookite. It is of outstanding importance as a white pigment because of its scattering properties, its chemical stability and lack of toxicity. It is also an important inorganic pigment in terms of the quantity produced. Besides this, titanium dioxide has utility in plastic, paint industries and also finds use for production of titanium.
Hither to known existing chemical processes where pigment grade titania is produced by two different ways i.e., sulfate route and chloride route. The sulphate process depends on the break down of the titanium containing raw materials such as ilmenite with concentrated sulphuric acid followed by hydrolysis and calcinations of the hydrate to produce titanium dioxide and a lots of spent acid is generated along with the Iron (II) sulphate. In the chloride route the raw materials are chlorinated at 900-1200°C. Titanium tetrachloride is separated by distillation and the same is burnt at 900-1400°C to form TO2. Reference to the same are made here (JOM, April, 1994; US patent no.5830420, 3rd Nov. 1998; US patent 5, 277, 816, Jan 11, 1994; US patent 4, 986, 742 Jan, 22, 1991; J Barksdale, Titanium 2nd edition, Ronald press comp.. New York, 1966, p 240; Dupont US 2098025, 1935, US 2098055, 1935).
The hither to known sulphate processes have got some disadvantages that it generates lots of waste materials including excess spent acid, iron (II) sulphate causing lots of pollution problems. Cases are there where this wastes are dumped in

the sea which has resulted the sea water pH very low. This has drawn attention of pollution departments and environmentalist.
In the invented process the above said disadvantages are to certain extent overcome by putting a few novel steps in the sulphate route circuit.
The main objective of the present invention is to develop a process for preparation of pigment grade titanium dioxide.
Another objective of the invention is to utilize ilmenite and/or titanium slag, sulphuric acid as the raw materials.
Accordingly the present invention provides a process for preparation of pigment grade titanium dioxide from ilmenite and/or titania slag, the said process comprising the steps of:
a) reacting titania ore or slag with 50-100% sulphuric acid with solid to
liquid ratio ranging between 1:4 to 1:10, for a period of 5- 8 hrs to
obtain a liquid slurry,
b) filtering the above said slurry, followed by washing with water to obtain
a filter cake,
c) recycling the filtrate as obtained from step b to step a,
d) treating the above said filter cake obtained in step (b), with water or dilute sulphuric acid to eatract the titanium sulphate or iron sulphate , follwed by filtration to obtain a residue and a filtrate,
e) calcining the above said residue obtained in step(d), at a temperature of 850-950°C to obtain the calcined titanium dioxide.

f) hydrolyzing the sulphate containing filtrate solution obtained in step (d) at temperature of 90°C-100°C to obtain the titanium dioxide hydrate and
g) calcining the above said hydrate at a temperature of t 850-950°C for a period of 10-20 minutes to obtain the desired titanium dioxide pigment.
In an embodiment of the present invention the titanium ore used is ilmenite
In still another embodiment the titanium slag used is obtained by plasma smelting
of ilmenite.
The novelty of the present invention lies in the use of titanium slag as the raw material and the use of water or dilute sulphuric acid as solvent for the extraction of titanium sulphate which ultimately reduces the production of spent material and makes this process eco-friendly.
The following typical example given below is to illustrate how the invention is carried out in actual practice and should not be construed to limit the scope of this invention
Example - 1
100 g. of titania slag containing titania (76.6%) is made to react with sulphuric acid (50%) at a solid to liquid ratio 1:8 for a period of 6 hours to form a slurry. This slurry is decanted, filtered and washed. The filtrate and wash water were recirculated to the initial step. Then the titanium sulphate and iron sulphate were extracted by putting the water or dilute sulfuric acid. Then the solution was filtered to get the residue which on calcinations at 900°C gives calcined titanium dioxide. The sulphate

containing solution was hydrolysed at 96-99°C and titanium hydrate thus formed is calcined at 700°C for 15-30 minutes to produce pigment grade titanium dioxide.
Example - 2
Titania slag containing 85% titania made from plasma smelting of ilmenite is made to react with hot sulphuric acid (80%) at a solid to liquid ratio 1:5 for a period of 6 hours to form a slurry. This slurry is decanted, filtered and washed. The filtrate and wash water were recirculated to the initial step. Then the titanium sulphate and iron sulphate were extracted by putting the water or dilute sulphuric acid. Then the solution was filtered to get the residue which on calcinations at 900°C gives calcined titanium dioxide. The sulphate containing solution was hydrolysed at 96-99°C and titanium hydrate thus formed is calcined at 700°C for 15 -30 minutes to produce pigment grade titanium dioxide.
The advantages of the invention are following.:
a) The process involves inclusion of few novel steps in the sulphate route circuit.
b) The process involves use of titania slag as the raw materials.
c) The process produces both anatase and rutile grade titania unlike in the conventional sulphate process.
d) The process is environmentally pollution free process.

We claim
1. A process for preparation of pigment grade titanium dioxide from ilmenite and / or titania slag, the said process comprising the steps of:
a) reacting titania ore or slag with 50-100% sulphuric acid with solid to liquid ratio ranging between 1:4 to 1:10, for a period of 5-8 hrs to obtain a liquid slurry,
b) filtering the above said slurry, followed by washing with water to obtain a filter cake,
c) recycling the filtrate as obtained from step b to step a,
d) treating the above said filter cake obtained in step (b) with water or dilute sulphuric acid to extract the titanium sulphate or iron sulphate , followed by filtration to obtain a residue and a filtrate,
e) calcining the above said residue obtained in step(d), at a temperature of 850-950°C, to obtain the calcined titanium dioxide,
f) hydrolyzing the sulphate containing filterate solution obtained in step (d), at temperature of 90°C-100°C, to obtain the titanium dioxide hydrate and
g) calcining the above said hydrate, at a temperature of 850-950°C, for a period of 10-20 minutes to obtain the desired titanium dioxide pigment.

2. A process as claimed in claim 1, wherein the titanium slag used is obtained by
plasma smelting of ilmenite.
3. A process for preparation of titanium dioxide from ilmenite and /or titania slag
substantially as herein described with reference to the examples.

Documents:

1201-DEL-2002-Abstract-(17-09-2008).pdf

1201-del-2002-abstract.pdf

1201-DEL-2002-Claims-(17-09-2008).pdf

1201-del-2002-claims.pdf

1201-DEL-2002-Correspondence-Others-(17-09-2008).pdf

1201-del-2002-correspondence-others.pdf

1201-del-2002-correspondence-po.pdf

1201-DEL-2002-Description (Complete)-(17-09-2008).pdf

1201-del-2002-description (complete).pdf

1201-DEL-2002-Form-1-(17-09-2008).pdf

1201-del-2002-form-1.pdf

1201-DEL-2002-Form-18-(17-09-2008).pdf

1201-del-2002-form-18.pdf

1201-DEL-2002-Form-2-(17-09-2008).pdf

1201-del-2002-form-2.pdf

1201-DEL-2002-Form-3-(17-09-2008).pdf

1201-del-2002-form-3.pdf

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Patent Number

225748

Indian Patent Application Number

1201/DEL/2002

PG Journal Number

50/2008

Publication Date

12-Dec-2008

Grant Date

27-Nov-2008

Date of Filing

29-Nov-2002

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110 001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	PRATIMA MISHRA	REGIONAL RESEARCH LABORATERY, (CSIR), BHUBANESWER, ORISSA, INDIA.
2	RAMCHANDRA KRISHNARAO GALGALI	REGIONAL RESEARCH LABORATERY, (CSIR), BHUBANESWER, ORISSA, INDIA.

PCT International Classification Number

C01G 23/047

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA