TiO₂ Filter Cloth Engineering Questions & Reference Envelope
Published process data and engineering parameters for sulfate-process metatitanic acid dewatering and pigment filtration across HVBF and vertical pressure filters.
This document summarizes public chemical, mechanical, and weave data governing titanium dioxide (TiO₂) filter cloth selection. No blanket recipe is prescribed; all parameters require verification against your specific plant flowsheet, temperature, and operating vacuum.
Published technical parameters for TiO₂ filtration
Filtration of metatitanic acid presents demanding conditions of high acidity, submicron solids, and thixotropic cake rheology. The table below correlates industry reference parameters with their verification status:
| Parameter | Engineering Content | Source | Status |
|---|---|---|---|
| Chemical envelope & polymer selection | Published literature reports polypropylene (PP) monofilament or PVDF for hot sulfuric acid (pH < 1.0, 65°C to 80°C). Polyester (PET) is excluded due to acid hydrolysis risk. | Public Process Reference (Ullmann) | Public material reference |
| Micron retention & pore structure | Targeted for primary metatitanic acid particles (0.2 to 0.4 µm) and flocculated aggregates. Our recommended starting envelope: 80 to 140 L/dm²·min (≈ 26.2 to 45.9 CFM/ft² @ 200 Pa ΔP), confirmed by slurry testing. | Our recommended starting envelope | Recommended starting envelope |
| Surface finish & cake release | High-pressure thermal calendering on the slurry contact face creates a smooth plane that minimizes scale keying and facilitates scraper discharge. | Plant Engineering Survey | Public process reference |
| Mechanical seam & alloy specification | High-alloy clipper fasteners (e.g. Hastelloy C-22 or 904L) with PEEK pintle wire are specified in hot-acid, high-chloride circuits. Evaluated per plant chloride analysis. | Corrosion Engineering Handbooks | Customer-specific requirement |
| Edge reinforcement & tracking guides | Ultrasonic edge sealing combined with vulcanized synthetic rubber tracking guides, configured to plant pulley profiles. | Machine Specification Standard | Customer-specific requirement |
Key questions before specifying TiO₂ filtration media
1. Acid concentration and thermal limits
Sulfate-route hydrolysis liquor contains 20% to 25% free sulfuric acid at 65°C to 80°C. Standard polyester (PET) degrades rapidly through acid hydrolysis under these conditions. Polypropylene (PP) provides chemical resistance, while PVDF is evaluated for extreme operating temperatures.
2. Micron retention vs blinded pores
Precipitated metatitanic acid includes fine primary particles (0.2 to 0.4 µm). Using an overly dense cloth causes rapid depth blinding. Media design balances surface filtration with continuous return-strand washing.
3. Seam metallurgy and chloride levels
Dissolved chloride ions in acidic recycle liquor cause stress-corrosion cracking in standard stainless steels. High-alloy clippers (Hastelloy C-22, 904L) or seamless fabric joints are evaluated based on slurry chloride content.
4. Cake discharge and thixotropic release
Hydrous titanium dioxide cakes can adhere tenaciously to uncalendered fibers. Controlled thermal calendering flattens surface yarn crowns, minimizing mechanical keying and supporting complete cake release.