The Pigment Production Plant at KMML consists of 3 units.
Chlorination Plant (U 200)
- Beneficiated Ilmenite (BI) from Ilmenite Beneficiation Plant is chlorinated to produce Titanium Tetra Chloride (Tickle).
- Chlorine reacts with Titanium Dioxide and other metallic oxide impurities in BI in the presence of petroleum coke at a temperature of 900 Deg C in a fluidised bed chlorinator to produce chlorides of Titanium and other impurity metals.
- Impure TiO2 + 2Cl2 = TiCl4 + CO2 / CO + Metal chlorides
- The chlorides of impurity metals are removed from Titanium Tetra Chloride by direct cooling with liquid Titanium tetra chloride and cyclonic separation of solid impurities.
- The Titanium Tetra Chloride vapour is then condensed and stored.
- The Impure TiCl4 is condensed out of the waste gases in a number of cooling stages.
- The gases are contacted with cold TiCl4 liquid in a Quench Condensing Column. Most of the TiCl4 gas is condensed here.
- More TiCl4 is recovered by passing the remaining gases through water-cooled exchangers.
- And finally pass through refrigerant cooled exchangers to complete the recovery of TiCl4.
- TheTitanium tetra chloride is further purified by distillation to obtain pure Titanium Tetra Chloride in the liquid form which is stored in storage vessels.
Oxidation Plant (U 300)
- In this plant Titanium Tetra Chloride is vapourised, pre-heated and oxidised with oxygen to produce raw Titanium Dioxide at a high temperature. The raw Titanium Dioxide obtained from this plant is formed into slurry with Water and pumped to storage tanks for surface treatment in the finishing plant.
- TiCl4 + O2 + Heat = TiO2 (Rutile) + 2 Cl2 + Heat
- A new technology “Supported Combustion Process” was developed in-house, by which the fragile silica was replaced with metallic pipes (Inconel- 600).
- The concept of supported combustion process envisages replacement of failure prone quartz pipes (silica) in TiCl4 preheater with a suitable material of construction which can render longer operational life and can withstand the corrosive reactants without affecting oxidation reaction.
- This required alteration of the existing process conditions to suit the new material of construction with necessary process changes to effect the oxidation reaction.
Pigment Surface Treatment and Finishing (U 400)
- The function of Unit-400 is to process the raw titanium dioxide and render it suitable for final customer sales.
- This is achieved by coating the surface for the individual titanium dioxide particles.
- There are several steps required prior to coating the particles to obtain a saleable product.
- The process can be broken down as follows:
- Slurry storage: Pigment slurry storage into which Unit-300 feeds and from which Unit-400 draws.
- Sand milling: Breaking down any lumps or clusters of pigment particles & polishing the pigment particle surface for surface coating.
- Classification: A 3 stage process which removes any oversize particles from the slurry stream.
- Treatment: Coating the pigment particles according to pre-determined recipe.
- Filtration / Washing: A 3 stage filtration process in rotary drum filters which separates treated pigment cake from slurry and removes as much water in third stage. The 1st two stages are washing and last is dewatering. Followed by, Pressure filtration in modern energy efficient “Larox filter”.
- Drying: Removing the rest of the water of the cake in steam heated tunnel dryer in macaroni form. Final moisture will be around 1 or less than 1% depending on the specific grade. Then drying the cake in modern spin flash dryer and the final product is in the powder form with moisture less than 1%.
- Micronising: Grinding the pigment into a very fine powder using superheated steam as grinding medium in micronisers.
- Bagging / Palletising: Putting it into 25 Kg bags - 40 bags in a pallet, using modern packaging systems.
The following grades of Titanium Dioxide pigment are presently manufactured in Unit - 400
- KEMOX – RC 800
- KEMOX – RC 800 PG
- KEMOX – RC 802
- KEMOX – RC 813
- KEMOX – RC 822
- KEMOX – RC 808
- KEMOX – RC 804
The treatment procedures and the pigment characteristics vary from grade to grade.