1 Manufacture of Titanium Dioxide

ByKaran Ved (116220)

Manish Kumar(1161)Manoj Kumar(1161)

Supervisor:Sri A. Venu Vinod

Associate Professor

2 Introduction

Titanium dioxide is a substance as old as the earth itself. It is one of the top fifty chemicals produced

worldwide.

3 TiO2

Forms: rutile and anatase and brookite. Source: IlmeniteIt is a white, opaque and naturally-occurring mineral.Titanium dioxide exhibits a Tetragonal crystal structure.

4 Future Prospects of Titanium Dioxide TiO2 output growth will be rather small (~2-

2.5% per year) in the near future. Demand growth ~5% China shows significant increase in

consumer-driven sectors in economy, will be a leader in titanium dioxide consumption in the near future.

5 Literature Review: History First successful attempt to produce relatively pure

titanium dioxide from ilmenite ore was made by Rossi in USA in 1908.

The first titanium pigment company which intially produced composite pigments commenced production at Niagara Falls in 1918.

6

The event that revolutionized the titanium dioxide industry was the development of Chloride Technology by M/s. Du-Pont around 1959.

The chloride technology took the US industry by storm and in a short span, most of the sulphate route plants were closed or replaced by chloride route plants.z

7

1918 4000

1925 10000

1939 100000

1965 1400000

1970 2000000

1985 3000000

1996 4200000

2014 5100000

Global TiO2 production 1925-2014

8 Review: History in India Travancore Government was obsessed with the idea that it

could undertake the economic manufacture of titanium dioxide, as the State possessed high grade ilmenite.

The Travancore Government, however lacked the confidence to start the venture on its own.

The Government, therefore, brought pressure on the four mining companies which at that time operated in the State, to get one of their foreign clients interested in the manufacture of titanium dioxide in Travancore.

9

British Titans Products Ltd. produced 387 tons of anatese in 1952.

In the meantime, foreign prices came down appreciably below the domestic cost and the company's financial resources also got exhausted.

10 Presently in India Consumption of titanium dioxide in India is increasing by 9-10%

annually according to BAC (Bank Of America Corporation) report.

India becomes one of the most prospective markets for titanium dioxide. The demand for it is estimated at the level of 150,000 tons annually. (According to the report “Titanium Dioxide Market in India: Business Report”)

Although we have one of the world’s largest deposits of the ore, about 70% of the titanium oxide demand in India is satisfied by import deliveries.

11 India has the 3rd largest Ilmenite deposits after China and Australia.

Rutile - 7.4 million tons. It is 17.6% of the total world deposits. India has mines of Ilmenite in Kerala, Tamil Nadu, Andhra

Pradesh, and Orissa. The mine production of Ilmenite in India accounted for

5,50,000 tons in 2010(Top 5). Ilmenite exported. The per capita consumption of titanium dioxide in USA is about

3.4 Kg. The consumption in Asia-Pacific region is about 0.2 Kg. The Indian consumption, however, is extremely low at less than 0.05 Kg

12 Uses There are two commercial grades of titanium dioxide

available worldwide – pigment grade and ultra-fine or nano grade.

It is used extensively in paint, paper, plastic and other industries. High purity titanium dioxide is an important electronic material.

Solar cells to sweets, toothpaste and medicine. Titanium dioxide has a variety of uses, as it is odorless and

absorbent. In cosmetics, it serves several purposes. It is a white pigment, an opacifier and a sunscreen.

13 Concern has arisen from studies that have pointed

to titanium dioxide as a carcinogen and photo catalyst, thus creating fear in consumers.

Titanium dioxide is regarded as an inert, non-toxic substance according to its MSDS.

NIOSH recommends that fine TiO2 particles be set at an exposure limit of 2.4 mg/m3, while ultrafine TiO2 be set at an exposure limit of 0.3 mg/m3.

14

15 1. Pigments

Whiteness and opacity - paints and coatings (including glazes and enamels), plastics, paper, inks, fibers and food and cosmetics.

Most widely used white pigment. Titania is very white and has a very high refractive index – surpassed only by diamond.

Exposed applications - resistance to discoloration under UV light.

16 2. Photo catalysis

Titania acts as a photo sensitizers for PVCs, and when used as an electrode coating.

enhances the efficiency of electrolytic splitting of water into H2 & O2

17 3. Oxygen Sensors

Even in mildly reducing atmospheres titania tends to lose oxygen and become sub stoichiometric.

Semiconductor, electrical resistivity of the material can be correlated to the oxygen content of the atmosphere to which it is exposed.

18 4. Antimicrobial Coatings

photo catalytic activity - self cleaning and disinfecting properties under exposure to UV radiation.

medical devices, food preparation surfaces, air conditioning filters, and sanitary ware surfaces.

19 5. In air cleaners TiO2 photocatalysts - purification of indoor air.

Malodorous substances such as ammonia, hydrogen sulfide, acetaldehyde, toluene, methyl mercaptan, etc., involve serious risks to health or comfort. Their concentrations in indoor air are always low, which is very suitable for TiO2-based air purification.

A photocatalyst-type air cleaner is typically composed of TiO2-based filters, UV lamps, and a fan for air circulation. The filters feature honeycomb-type construction or three-dimensional porous structure for minimum pressure drop.

can decompose the adsorbed pollutants instead of accumulating them, and thus it exhibits better air-cleaning performance.

can also kill the bacteria floating in indoor air.

20 Future uses

Visible-light Photocatalysts Light source

21

Chloride Process rutile form 800-1200 ºC Chlorine is reacted in a fluidized bed reactor with a titanium-containing

mineral, e.g., mineral rutile (which is not readily attacked by sulfuric acid), under reducing conditions(presence of coke) to form anhydrous titanium (IV) chloride.

Purification of the anhydrous tetrachloride requires separation by fractional condensation.

Conversion of the tetrachloride to titanium dioxide may be accomplished by either direct thermal oxidation or reaction with steam in the vapour phase at temperatures in the range of 900-1400 ºC.

A minor amount of aluminum chloride is generally added to promote formation of the rutile form. The titanium dioxide is washed, calcined, and packaged.

22 Sulphate Process Anatase Slag is digested with sulfuric acid and the product is diluted with water or dilute acid. Most of the titanium dioxide from the ore is solubilized as a titanium oxo-sulfate and iron

is present in its +II oxidation state. The resulting liquor is clarified by sedimentation to remove insoluble residues such as

silica. Iron is removed by crystallization as its sulfate salt (FeSO4•7H2O), followed by filtration.

A small portion of the clarified liquor is neutralized with alkali to produce anatase micro crystals. These micro crystals are then introduced into the mother liquor, which is then hydrolyzed under carefully controlled conditions to produce crystals of anatase.

These are subsequently filtered, washed, calcined, and micronized. During calcination, the final temperature reaches about 800 -850 ºC.

23 ComparisonAspects Sulfate Process Chloride Process

Waste Disposal FeSO4 is formed in large No such huge amounts of solid

amounts leading to disposal wastes is encountered.Problem.

Product quality Produces low grade anatase Produces a higher grade rutile

pigment. Pigment.

Water Pollution Disposal of spent acid into No such problem iswater bodies causes pollution encountered.

Water usage Huge amount of water is Comparatively less amount of

required. Water is required.

24 Chloride Process

Titanium dioxide containing feedstock is subjected to high temperature carbo-chlorination to produce titanium tetra chloride, which is thereafter converted to titanium dioxide by oxidation.

25 Production Reactions The reactions involved in the manufacture of titanium

dioxide are,

1. 2TiO2 + 4Cl2 + 3C 2TiCl4 + CO2 + 2CO (Impure) 2. TiCl4 + O2 TiO2 + 2Cl2 (Pure) 3. SiO2 + 2Cl2 + C SiCl4 + CO2

4. 2FeO + 3Cl2 + C 2FeCl3 + CO2

26 Process Description Feedstock containing, titanium dioxide (85% pure) and

finely divided coke are added to chlorine gas in a reactor, where the titanium dioxide undergoes chlorination reaction at 800 ºC. Titanium tetrachloride and chlorides of iron and silicon are formed by the following reactions.

2TiO2 + 4Cl2 + 3C 2TiCl4 + CO2+ 2CO

SiO2 + 2Cl2 + C SiCl4 + CO2

2FeO + 3Cl2 + C 2FeCl3 + CO2

1.5 atm, 1 hour

27

The gas stream from the cooler is cooled to 137ºC where TiCl4 is condensed. The effluent gas is then sent to a converter, where Carbon monoxide is converted into Carbon dioxide. The condensed pure TiCl4 liquid at its bubble point is fed to the oxide burner.

Pure TiCl4 liquid is vaporized and burnt with oxygen to form titanium dioxide solid (0.3µm particle size) and chlorine gas. The reaction takes place at a temperature of 1000ºC.

TiCl4 + O2 TiO2 + 2Cl2

The stream containing chlorine gas and titanium dioxide solids are separated using a high efficiency Cyclone Separator. The Chlorine gas is recycled to the Chlorinator. The product is removed, cooled and surface treated.

28 Surface Treatment of Product: Pure TiO2 base pigments, have a relatively reactive

surface. The majority of commercial pigments are therefore coated. Improve wetting and dispersion in different media

(water, solvent or polymer) Improve compatibility with the binder and dispersion

stability Improve color stability Improve durability Increase air in the film in flat latex paints

29

Alumina, silica and/or zirconia, deposited onto the core TiO2 particles by a wet precipitation process.

A final coating of polyol or other organic chosen to enhance the dispersion of the pigment in a resin system and/or dry bulk handling characteristics is then added.

Pigment is dried, intensively milled and packed into bags.

30

The coatings on TiO2 pigments are deposited under very closely controlled conditions of time, temperature and pH to develop the required characteristics.

The final analysis of a surface coating shows only part of the expertise in making high performance TiO2 pigments. Order of addition and precipitation as well as the processes parameters are critical to making the optimum product.

31

32 Assumptions for Material Balance

There is no material loss from any equipment along any flow line by any means. There is no accumulation of material in any equipment, steady state exists.

Number of working days of the process reactor is assumed to be 330 days producing product with a purity of 98%.

In distillation column, purity of TiCl4 in distillate is assumed to be 98%.

Capacity of Plant is taken as 20000 TPA

33 Reaction Mass Balance

Reaction 1TiCl4 + O2 TiO2 + 2Cl2

Material In (kg/h) Material Out (kg/h)

TiCl4 6545 654.5

O2 110.16 110.16

TiO2 - 2474.74

Cl2 - 4407.2

Total 7646.6 7646.6

34

Reaction 22TiO2 + 4Cl2 +3C 2TiCl4 + CO2+ 2CO

Material In (kg/h) Material Out (kg/h)

TiCl4 - 6545

TiO2 3234.96 485.244

Cl2 5761.12 864.168

C 729.05 109.38

CO2 - 757.4

CO - 963.96

Total 7646.6 7646.6

35

Reaction 3 SiO2 + 2Cl2 + C SiCl4 + CO2

Material In (kg/h) Material Out (kg/h)

SiO2 190.29 -

Cl2 450.66 -

C 38.01 -

SiCl4 - 538.26

CO2 - 139.4

Total 677.96 677.96

36

Reaction 42FeO + 3Cl2 +C 2FeCl3 + CO2

Material In (kg/h) Material Out (kg/h)

FeO 380.58 -

Cl2 565.06 -

C 31.78 -

FeCl3 - 859.25

CO2 - 116.53

Total 677.96 677.96

37 Ore composition

RAW MATERIALREQUIRED AMOUNT(kg/h)

TiO2 (ore) 3805.83

Chlorine2315.43

Carbon795.79

Oxygen1266.91

38 Chlorinator

ChlorinatorTiO2

SiO2

FeO

TiCl4

SiCl4

FeCl3

CO2

CO

Coke

39 Chlorinator Mass BalanceMaterial entering Mass (kg/h) Material leaving Mass (kg/h)

TiO2 3234.96 TiCl4 6545

SiO2 190.29 SiCl4 538.26

FeO 380.58 FeCl3 859.25

Coke 798.84 CO2 1013.33

Cl2 6776.84 CO 965.96

Cl2 864.168

Coke 110.35

TiO2 485.24

Total 11381.51 Total 11381.51

40 Cooler

TiCl4

TiO2

CO2

CO

Cl2

SiCl4

FeCl3

Coke

TiCl4

TiO2

CO2

CO

Cl2

SiCl4

FeCl3

Coke

Cooler

41 Condenser

TiCl4

TiO2

CO2

CO

Cl2

SiCl4

FeCl3

Coke

TiCl4

CO2

CO

Cl2

SiCl4

Condensate (FeCl3, TiO2, Coke)

Condenser

42 Distillation Column

TiCl4

CO2

CO

Cl2

SiCl4

TiCl4

CO2

CO

Cl2

SiCl4

43 Distillation Column Mass Balance

Material In (kg/h) Material Out (kg/h)

Distillate Residue

TiCl4 6545 6512.1 32.81

CO2

CO 3381.63 132.9 3248.81

Cl2

SiCl4

Total 9926.63 6645 3281.63

44 Oxide Burner

TiCl4

O2

TiO2

TiCl4

O2

Cl2

Oxide Burner

45 Oxide Burner Mass Balance

Material In (kg/h) Material Out (kg/h)

TiCl4 6512.8 651.21

TiO2 - 2462.57

O2 1096.24 109.61

Cl2 4385.57

Total 7608.94 7608.94

46 Degassing & Cyclone Seperator

Cyclone SeperatorTiCl4

Cl2

O2

TiO2

TiO2

Cl2

TiCl4, O2

47 Mixer

Chlorine recycle= 4385.57kg/h Chlorine inlet required as feed to chlorinator= 6776.84kg/h Fresh chlorine required= 6776.84-4385.57=2391.27kg/h

Cl2 feed

Recycle Cl2Fresh Cl2

48 References M. Gopala Rao and Marshall Sittig, “Dryden’s Outlines of Chemical Technology”, 2nd Ed., East-

West press, 2005. pp.65-70. George. T. Austin, “Shreve’s Chemical Process Industries”, Fifth edition, McGraw Hill Book

Company, 2005. pp. 124-127. R. H. Perry and Don W. Green, “Perry’s Chemical Engineers’ Hand Book”, 7th Ed., Mc-Graw Hill

International edition, 2002. pp. 3-96, 3-150, 3-211. McCabe, Warren L. Smith, “Unit Operations of Chemical Engineering”, Seventh edition, Mc-

Graw Hill Book Company, 2005. pp. 836-850. Robert E. Treybal, “ Mass- transfer Operations”, 3rd Ed. , Mc-Graw Hill Book Company, 1981.

pp. 187-200, 300-309. “Encyclopedia of Chemical Technology”, by Kirk and Othmer 4th Ed “Chemical Economic Handbook” , journal Stanford Research Institute