Chloride vs Sulfate Process — Which TiO2 Should You Buy?
The two TiO2 production routes have different particle physics and different economics. Choose based on application and cost sensitivity.
Titanium dioxide is manufactured by two industrial routes: the chloride process and the sulfate process. The two routes produce TiO2 of slightly different physical and optical character, with significantly different cost structures. Understanding the difference is essential for grade selection.
Chloride process starts with high-titanium-content feedstocks (ilmenite ore upgraded to synthetic rutile, or natural rutile sand). Feedstock is chlorinated with petroleum coke at ~1000°C to produce gaseous TiCl4. The TiCl4 is purified and then oxidized at ~1500°C with oxygen to produce TiO2 vapor that condenses into very fine, narrowly-distributed particles. The byproduct is chlorine, which is recycled.
Sulfate process starts with lower-grade ilmenite ore. The ore is digested in concentrated sulfuric acid to produce titanyl sulfate, which is hydrolyzed at temperatures around 110°C to produce hydrated TiO2. The hydrated TiO2 is calcined to ~900°C to produce final TiO2 particles. The process produces significant ferrous sulfate byproduct that must be managed.
Particle size and color: - Chloride process produces narrower PSD (typical D50 0.25–0.30 μm), tighter standard deviation, and brighter undertone (CIE b* typically 1.5–2.0) - Sulfate process produces broader PSD, slightly higher metallic impurity carry-through, and slightly yellower undertone (CIE b* typically 2.0–2.5) - The difference is most visible in semi-gloss and gloss paints; matte/flat finishes typically don't show it
Cost: - Chloride process requires high-grade feedstock and is capital-intensive — typical capex is $4000+/ton of capacity - Sulfate process can run on lower-grade ilmenite, is older technology, capex is roughly $1500–2000/ton - Operating cost differential is ~$300–500/ton in favor of chloride at typical feedstock prices, but the raw material flexibility of sulfate gives it cost advantage in some periods
Geography: - Most US, EU, and Chinese chloride capacity is post-2010 — newer, larger plants - Most Chinese sulfate capacity is older — historically the dominant Chinese route, with ongoing modernization - LB Group, Tronox, Chemours, and Kronos all operate both routes
Application fit: - Premium coatings (automotive OEM, coil coatings, premium architectural) → chloride - Premium plastics (engineering plastics masterbatch, outdoor PVC) → chloride - Cost-sensitive coatings (economy interior paint, primers) → sulfate often acceptable - Inks, paper, rubber, fiber delustering → either, depending on cost vs spec - Anatase grades → exclusively sulfate (chloride anatase is rare and expensive)
The right choice depends on specific application requirements. Our SEMITI chloride grades (996, 706, 902, 826D, 880, 960, 2310, etc.) cover the chloride-process needs; SEMITI 298, 218, 248 cover sulfate; A100, A101, A200 are sulfate anatase. Customer-specific recommendation available on inquiry.