INTRODUCTION

. In 1932, M/s F.X.Periera & Sons (Travancore) Pvt. limited established the first fully fledged mineral

industry in Chavara. The industry taken over by Government of Kerala in 1956 and converted as a limited

company in 1972 in the name “THE KERALA MINERALS AND METALS LTD”. Commercial

production of Titanium Dioxide started in 1985 with an installed capacity of 22,000 MT/annum and now

KMML is the only integrated plant in the world of Titanium Chemicals and Metals that undertakes

Mining, mineral separation, titanium dioxide pigment manufacture at one complex. It brings titanium

dioxide more to our everyday life in numerous ways. Be it the dress we wear, the cosmetics we use, the

medicines we take, the paints we decorate our home with or the utility plastic products, our products are

there.

It has the integrated Titanium Dioxide facility having mining, mineral separation, synthetic Rutile and

pigment-production plants. Apart from producing Rutile grade Titanium Dioxide pigment for various

types of industries, it also produces other products like Ilmenite, Rutile, Zircon, Silimenite, Synthetic

Rutile etc.

The company has three units:

1) Mineral Separation unit (MS Unit)

2) Titanium Dioxide Pigment Unit (TP unit)

3) Titanium Sponge Unit

Manufacturing Titanium Dioxide through the chloride route, KMML produces pure Rutile grade

Titanium dioxide pigment. The different grades churned out by KMML under brand name KEMOX is a

ready market product.

The Process at MS Unit is as follows:

Wet Concentration Plant

Beach washing sand having low grade heavy mineral content is upgraded using  spiral concentrators at various

stages. 

The concentrate thus obtained is washed with fresh water and dehydrated using hydro cyclone

Dryer Plant

Fluidized bed dryer is used to remove the moisture and to maintain sand temperature at 100 degree Celsius

Furnace oil is used as fuel for the fluidized bed dryer

High capacity fans are used for fluidization of sand

Dried concentrate is fed to dry mill

Dry Mill

Concentrate is separated into conducting and non-conducting fractions by using high-tension electrostatic

separators

Conducting fraction is further separated into magnetic (Ilmenite) and non-magnetic fraction (rich in Rutile) by

using magnetic separators

Non-conducting fraction is transferred to Zircon plant for producing zircon

Non-magnetic fraction is transferred to Rutile recovery plant for the separation of Rutile

Finished product of dry mill is Ilmenite

Rutile Recovery Plant

Non-magenetic fraction is processed at various stages  using High Tension Electrostatic Separators, Induced

Roll Magnetic Separators and seived in suitable mesh to produce specified quality Rutile.

Rutile is packaged in 50 Kg bags

Zircon Plant

Non-conducting fraction is fed through series of non-conductor cleaner configuration High Tension /Electrostatic

Separators fafter seiving with suitable mesh for purifying non- conducting fraction

Air tables are operated to remove quartz and Sillimenite ifrom  Zircon rich sand

Zircon concentrate from air tables are fed through series of high tension electrostatic / magnetic separators for

the production of zircon

Zircon is packaged in 50 Kg bags

 

ILMENITE BENEFICIATION PLANT

Kerala has the richest and one of the most extensive heavy metal deposits in the world these deposits

stretch along the sea coast between kayamkulam and Neendakara, a trait generally known as Chavara coast. The main constituents in the deposits are ilmenite, Rutile, leucoxene, silimenite, zircon, and monazite. The first three are titanium bearing minerals and hence used for the manufacture of titanium dioxide pigment and titanium sponge metal.

KMML entered into technical collaboration with M/s Benelite Corporation of America, M/s woodball duckham of U.K. and M/s Kerr mc gee Chemical Corporation of America, respectively for the supply of basic technology for the pigment production.

In IBP plant the raw ilmenite containing 55 to 60% TiO2 is processed to obtain beneficiated ilmenite of 90 to 92% TiO2 which is the following process operations.

ROASTING

Raw ilmenite is fed at the rate of 9.0 T/Hr with 10% petroleum coke into a rotating kiln called roaster. The ferric oxide in the raw ilmenite is first subjected to high temperature reduction to ferrous oxide in the presence of petroleum coke at a temperature of 900 to 9500C. The reduced ilmenite is discharged through a rotary cooler having cooling water tubes and collected in a hopper.

Reaction

C + CO2 2 CO

2C + O2 2CO

Fe2O3 + C 2FeO

Fe2O3 + CO 2FeO + O2

LEACHING IN DIGESTORS

45 tons of reduced ilmenite is charged in a digestor and leached with 19 to 20% dilute HCl twice. During leaching the ferrous oxide and other impurities are dissolved in HCl. Firstly with 51 m3 acid and secondly with 42 m3 acid. The spent leach liquor is blown down to the storage tanks from where it is pumped to acid regeneration plant for regenerating the acid. The leached ilmenite after washing with 50m3 wash water is dumped into the launders. From the launder it is pumped to the belt filter where it is filtered and filtered leached ilmenite is send to calciner through belt conveyor.

digestor

TANK FARM

The spent liquor and wash liquor blown down from the digesters are pumped to the respective storage respective storage tanks from where it is pumped to the acid regeneration plant for regenerating acid. The recovered acid received from ARP and makes up acid from the storage tank are pumped together using ratio controller to get mixed acid of 19 to 20% concentration for the use in the digesters.

CALCINATION

Leached ilmenite is fed into calciner at the rate of 4 to 6 T/Hr through screw feeder where it is calcined at 5000C to remove moisture volatile matter. The material is cooled by natural draft in the cooler. The cooled beneficiated ilmenite is screened and sends to the BI go down through bucket elevator and belt conveyor.

ACID REGENERATION PLANT

PRECONCENTRATION

Spent leach liquor from the spent liquor storage tank is pumped to the pre concentrator recycle tank. The pre concentrator recycle pump continuously circulates liquor from the recycle tank to the pre concentrator. In the pre concentrator the circulating liquor is made to contact with hot gases coming from the dry cyclone sets .This results in hot gases being cooled from about 3750C – 960C, the heat so released

being used to evaporate water from the circulating liquor. The circulating liquor drains back to the recycle tank.

Acid regenretion plant

SPRAY ROASTING

From the recycle tank, the pre concentrator liquor is pumped to spray boom assemblies situated at the top of the spray roaster by a roaster feed pump through a fine filter. Spray nozzles are present at spray booms which atomizes the liquor into the top of the roaster. There are four burners present at the bottom portion of the roaster. Tangential firing of these burners into the roaster causes some of the hot gases to spiral upwards. The liquor droplets flowing down from the spray nozzles come in contact with hot gases and reaction takes place. Water and free hydrochloric acid (HCl) content of liquor are evaporated by the hot gases .this spray dried chlorides are then reacted to form hydrogen chloride and an appropriate oxide. The reactions are as follows:

FeCl2 + 4H2O + O2 2FeO2 + 8 HCl

4 FeCl2 + 3 H2O Fe2O3 + 6HCl

The oxide that is formed as a result of this discharged from the gases leaving out. These gases are passed through dry cyclones which are set before flowing on to preconcentrator. The oxide is retained in the cyclone set and is returned to the oxide slurring box.

HYDROGEN CHLORIDE ABSORPTION

The gases from the wet cyclones are passed upwards through the absorber where they are contacted countercurrent with absorber feed liquor fed from the absorber feed liquor fed from the absorber head tank. This results in virtually all the hydrogen chloride content of the gas stream being absorbed to form recovered acid containing 18.8%. The recovered acid flows by gravity to the recovered acid storage tanks.

The gases from the top of the absorber are then passed upwards through the tail scrubber where it is contacted counter currently with tail scrubber circulating liquor in order to remove most of the residual HCl content. The gases pass from the top of the tail scrubber to the exhaust fan to the exhaust fan damper. The gas from the exhaust fan damper is discharged to the exhaust stack.

OXIDE SLURRY SYSTEM

The oxide from the roaster and dry cyclones is discharged into the oxide slurring box. The oxide is blown through the oxide slurry launder by a copious supply of water into the slurry tank. From the tank it is pumped to the slurry pond. The water supply of the slurry box consists of clarified water from the slurry pond via the water pumps.

PIGMENT PRODUCTION PLANT (PPP)

The pigment plant is designed and installed based on the “Chloride Process” being successfully operated by Kerr McGee Chemical Corporation of USA at Hamilton, Mississippi.

The annual capacity of the plant is 40000 MT of Rutile grade pigment. The basic raw materials are Beneficiated Ilmenite, Petroleum Coke and Chlorine. Rutile grade Titanium Oxide is the best known pigment presently available. The consumers of product are paint, textile, paper and plastic industries.

There are five major sections in the plant.

1. Raw material handling Unit-100

2. Chlorination Unit-200

3. Oxidation Unit-300

4. Pigment finishing Unit-400

5. Chemical storage Unit-500

PROCESS DESCRIPTION

The raw materials, BI (Beneficiated Ilmenite) and PC (Petroleum Coke) are conveyed from respective storages to hoppers from where they are pneumatically conveyed to the chlorinators in the first section. Chlorine from the Chlorine storage is also conveyed to the chlorinators and at a temperature of 800 to 9000C. Ilmenite reacts within the chlorinators to produce Titanium Tetra Chloride vapours. The metallic chlorides present in the BI are mostly removed as solids initially after chlorination. The balance impurities are removed as solids, initially after chlorination. The balance impurities are removed by adding special treating oil and by distillating the TiCl4 in the purification section. The purified TiCl4 is the product of U200.

Aluminium Chloride is added to the liquid TiCl4, vaporized, preheated and oxidized to produce raw pigment in U 300.Since the TiO2 precipitates from the vapor phase reaction, specially quality silica sand is used to transport the pigment from the Oxidiser.The Chlorine evolved during oxidation is recycled to U200.The TiO2 and sand are made into the slurry and classified to remove most of the sand. The slurry of the sand and Raw Titanium Dioxide pigment is the product of U 300.

The TiO2 slurry produced in the oxidation section is taken through a series of operations in the finishing section, U-400 to impart certain properties and qualities to the pigment as well as to remove particles of sand left in the slurry. A number of treating chemicals are added in this section and after treatment the pigment cake filtered out, washed, dried and size reduced by Micronisation. The micronized pigments have extremely small particle size averaging about 0.2 microns. This finely sized pigment is cooled and bagged as product.

The various chemicals required are stored in storage section, U 500 and fed to the Finishing section as

required.

UNIT 200

In the chlorinators D201,D202 and D203 BI react with Cl2 gas in the presence of petroleum coke to produce TiCl4 vapor and other metallic chlorides at about 800-9000c.The gas passes through a cross over pipe where a spray of crude liquid TiCl4 cools these to about 2000C.This cooled gas is passed in to the cyclones F201,F202,F203 and from there to condensing column(D205).At the bottom of the cyclone the unreacted ore, coke particles and the metallic chlorides are removed and discharged to a waste solid sump (F1569) from where they are pumped to the Effluent Neutralization Plant. The gases from the Cyclone enter the Condensing Column (D205) from the bottom. Crude TiCl4 cooled in the water cooled heat exchangers (E204&E205) enters the top of the condensing column and condenses the upward flowing TiCl4 gas. The crude TiCl4 then flows by gravity to a Quench surge tank (F204) and from that to crude TiCl4 tank (f205).The quench tank F204 holds the crude TiCl4 that is used for spraying at crossover pipe and circulating to the top of the condensing column by pumps G203&G204.

The gas leaving the top of the condensing column is passed through water-cooled condensers E206 A&B ,knock out pot D207, Refrigerated condensers E207 A&B and another knockout pot D208 to

recover all remaining crude TiCl4.After being cooled to -200Cin the refrigerated condensers, the gas passes through

Chlorination plant

Acid Scrubber(D1556) and the Tail Scrubber(D556).The vent gas from the tail scrubber passes through the lime scrubber(D1501 where it gets scrubbed with 4% Lime slurry)then into Caustic Scrubber(D1502).The HCl produced from acid scrubbers is pumped to IBP. Crude TiCl4 that has been collected in F205 is well over 99.5% pure. However this must be further purified for use in succeeding Oxidation section. The crude TiCl4 is pumped to the reactor D213 where it is heated and vanadium chloride get reacted with the treating oil to form a compound, which separated from TiCl4 by distillation. The required temperature is maintained in the reactor D213 by circulating the contents through a steam heated reboiler. The vapour boils off and pass through the heavy ends column D215.The product TiCl4 is cooled in the heavy ends condenser E215 and collected in the heavy ends accumulator D219.From this accumulator part of the product is returned to the column as reflux and the balance pumped to pure TiCl4 storage tanks (D222, D223, D224) for storage and supply to the Oxidation section.

Reaction

TiO2+2Cl2+2C TiCl4+2CO

TiO2+2Cl2+C TiCl4+CO2

acid scrubber

UNIT 300 (OXIDATION UNIT)

PROCESS DESCRIPTION

In this unit purified TiCl4 from U-200 is mixed withAlCl3 and vapour of this mixture is oxidized in the oxidizer with Oxygen in pressure of LPG flame to produce TiO2 pigment. Chlorine which is obtained as a byproduct is filtered, cooled, dried and compressed before sending back to U-200 for chlorination of titanium ore there. Pure tickle from tickle storage tank is pumped using tickle transfer pumps (G-235 / G- 236) through a heater (E-323) at temperature of 1200C to 1350C to AlCl3 dissolving tank (D-303). Pre- calculated quantity of AlCl3 is mixed with the tickle in this tank (D-304) from which the feed material for further process is drawn. Quantity of AlCl3 to be added varies for different grades of raw pigments produced. AlCl3 is added for enhancing nucleation reaction.

Tickle and AlCl3 solution from D-304 is taken to tickle feed vaporizers (E-301/ E-302) where it is vaporized using steam in nickel tube bundles and the vapour is send to the tickle pre-heater at a temperature of 1450C to 1900C through glass lined pipes. In the tickle pre-heater this vapour is pre-heated to 3300C- 3700C using LPG burners.

Oxygen from Oxygen Plant is pre-heated to 9400C to 9800C in the oxygen pre-heater and sent to the oxydiser forms a flame. Then the pre-heater tickle vapour is admitted into the oxydiser where the TiCl4+AlCl3 vapour reacts to produce pigment particles and chlorine. Silica sand is also fed into the oxiydiser to erase the pigment from downstream cooling tube sides. Potassium Chlorides injected downstream of the oxydiser for deaglomerationof the pigment. Even though the oxidation reaction is initiated at elevated temperatures; after starting the reaction, it is exothermic and a large amount of heat is

generated. For increasing the rates of the production using this heat generated, some amount of TiCl4+AlCl3 vapour from feed vaporizer outlet is directly admitted into the reaction zone downstream of oxydiser, bypassing the tickle pre-heater.

The reaction products pass through the reactor cooling tube where the products are cooled to below 4500C and enter the pigment separator. The pigment particles along with the silica sand falls to the bottom of the separator. These particles are dumped into the pre treatment sump and slurried using water / make up water. The pH and density of the slurry are controlled by adding required quantity of NaOH, water and SHMP solution.

This slurry is pumped to primary and secondary classifiers for removing the sand. The slurry after removing the sand is pumped to the storage tanks (F-401,402,403). The sand separated is washed, dried, sieved and re-cycled with fresh make up sand. The gaseous products of the reaction (mainly chlorine) leaves the top of the pigment separator – at a temperature of 3500C to 4500C and needs filtering in the bag filter to remove the pigment particles carried along with the gas. But as the bags in the bag filter cannot withstand temperatures above 2000C – 2500C, the inlet gas temperature to bag filter to be brought down. This is done by mixing cooled, recycled gas with the pigment separator outlet gas at the entry point to bag filter. For this, a major portion of the gases which the recycle gas blower draws from bag filter is cooled in the recycle gas cooler (E-324/E-325) and is sent back to the inlet of bag filter. The product gas from the recycle gas blower discharge is filtered again in the Guard filter and cooled in the Methanol chiller. The cooled gases then pass through a knock-out pot where the condensable components are drained out. This cooled recycle gas is then scrubbed in the H2SO4 scrubber for drying and then compressed using Chlorine compressors and sent back to U-200 for chlorination of titanium ore.

PROCESS DESCRIPTION OF U 400

1) SAND MILLING AND CLASSIFICATION :

Pigment slurry from storage tanks F-401/402/403 is pumped to Trash screen S.425 (100 mesh vibrating screen) which removes sand and trash. The screened slurry flows to F.412 tank by gravity flow. From this tank slurry is pumped to sand mill R-412A/B where pigment grinding with sand is done for releasing absorbed gases like TiCl4 and Oxygen. Sand milled slurry is stored in D.423 tank and from there; slurry is pumped to grits classifier S-402A/B and to vibrating screen S-404A/B to screen out grits and sand. Screened slurry flows to D.424 tank and from there slurry is pumped to product classifiers S-416A/B/C. Product classifier separates 5 microns particles as overflow for treatment and slurry is stored in treatment feed tank F-414.

2) TREATMENT :

In treatment, various chemicals such as sodium silicate, sodium aluminate, etc. are added which when neutralized with caustic soda or sulphuric acid from hydrous oxides. Hydrous oxide particles are very small compared to titanium dioxide particles and tend to coat individual pigment particles.

Treatment is done in F415A/B tank on batch basis. This tank is provided with steam sparger and agitator having two speeds (20 rpm & 30 rpm). Using G-417A & B pumps required quantity of raw slurry is pumped to treatment tank. Required quantity of filtrate is taken in the tank using G-428 pump. The treatment chemicals from U 500 are connected to F.415A/B tank. A batch meter installed near the treatment tank is provided with flow totaliser, flow indicator and start- stop switches for each of the four chemicals used for treatment. The required quantity of chemicals can be set in the flow totaliser. After batch treatment is completed, the whole contents are transferred to F-418 tank.

FILTRATION AND DRYING :

Treated slurry is pumped to filter tank F-418. From this tank, slurry is feed to first stage filter S-407A or B. Cake is formed on the filter by applying vacuum to the drum and the cake is washed by spraying hot water through nozzles. The cake is discharged to the re-pulper, where it is agitated after dilution with water. From the re-pulper slurry goes to F-423 tank by gravity flow. From F-423 tank, it is pumped to second stage filter and after washing and re-pulping slurry goes to F-424 tank. Pigment slurry from F-424 is pumped to de-watering filter S-411A/B .De-watering filter is different from washing filter since no washing is given.

The cake from the de-watering filter is falling into extruder which form pigment cake into chute which drops into the tunnel dryer conveyor. Macroni is carried into the drying chambers by the conveyor. As the pigment passes through the drier, it losses moisture and pigment is discharged to the vibrating conveyor C-417. At this stage moisture content will be less than 1% and organic addition is sprayed at the discharge of the conveyor. This Macroni is stored in F-425 through bucket elevator C-418 and screw conveyor C-428.

3) MICRONISATION AND CONDENSATE COOLING :

Dried pigment is micronized in the micronisation section. The purpose of micronisation is to reduce the particles size to 0.28 microns. Super heated steam at 17.6Kg/cm2 is used as the grinding medium. “MACARONI” from feed bin F-425 fed to screw feeder C-421A/B, which feeds Macroni to Microniser at an adjusted rate. The pigment is injected into the Micronized chamber by a high pressure steam ejector. Superheated steam which passes through the nozzle of the Microniser attains supersonic velocity. At this velocity pigment particles collide with each other and particle size are reduced. The steam escaped to a condenser/scrubber and micronized pigment is cooled and conveyed by low pressure air to secondary cyclone and from there to Product Bin. The steam and non-condensable gas are drawn away by a fines scrubber and Ventury scrubber by a vacuum pump to the atmospheric vent. The slurry from F-432A/B(scrubber) flows to surge tank to surge tank D-412 from where it is recycled back to F-432A/B by pumping through heat exchangers E-401A/B and E-402A/B .