Key Equipment for Titanium Dioxide Production via Sulfate Process from Ilmenite

Introduction to Sulfate Process for Titanium Dioxide Production

The sulfate process remains one of the primary industrial methods for producing titanium dioxide (TiO₂) from ilmenite ore. This complex chemical process involves multiple stages including ore preparation, digestion, crystallization, calcination, and finishing. The quality and efficiency of TiO₂ production heavily depend on the proper selection and operation of key equipment throughout the manufacturing chain. This article examines the critical equipment requirements with particular focus on grinding and milling operations that significantly impact process efficiency and final product quality.

Process Overview and Equipment Requirements

The sulfate process begins with ilmenite ore preparation, where proper size reduction is crucial for subsequent chemical reactions. The process involves dissolving ilmenite in sulfuric acid, followed by purification, hydrolysis, and calcination to produce TiO₂ pigment. Each stage demands specific equipment characteristics to ensure optimal reaction rates, product purity, and energy efficiency. The grinding and milling operations particularly influence the digestion efficiency in sulfuric acid, as finer particles increase the surface area available for chemical reaction.

Critical Size Reduction Stages in TiO₂ Production

Primary Crushing of Ilmenite Ore

Initial size reduction of raw ilmenite ore is typically accomplished through jaw crushers or gyratory crushers that reduce large chunks to manageable sizes of 50-100mm. This primary crushing stage prepares the material for subsequent fine grinding operations. The choice of primary crusher depends on ore characteristics, including hardness, abrasiveness, and moisture content.

Intermediate Grinding for Optimal Digestion

Following primary crushing, intermediate grinding reduces particle size further to enhance the efficiency of the digestion process in sulfuric acid. At this stage, the material typically needs to be reduced to below 30mm to prepare for fine grinding. Equipment such as hammer mills or cone crushers may be employed, with careful consideration of wear resistance due to the abrasive nature of ilmenite.

Fine Grinding for Maximum Reactivity

The most critical size reduction occurs in the fine grinding stage, where ilmenite is ground to optimal fineness for acid digestion. The target particle size distribution significantly impacts reaction kinetics, acid consumption, and ultimately TiO₂ yield. Traditional ball mills have been widely used, but modern operations increasingly favor more efficient vertical roller mills and specialized grinding systems that offer better energy efficiency and particle size control.

Advanced Grinding Solutions for TiO₂ Production

Vertical Roller Mills for Intermediate Grinding

For the intermediate grinding stage where particle sizes need to be reduced from 50mm to below 30mm, the MTW Series Trapezium Mill offers an excellent solution. With an input size capacity of ≤50mm and output fineness ranging from 30-325 mesh (up to 0.038mm), this equipment bridges the gap between primary crushing and fine grinding. The MTW series features several technological advantages particularly relevant to ilmenite processing:

• Anti-wear shovel design with combined blades reduces maintenance costs
• Curved air channel optimization minimizes energy loss and improves transmission efficiency
• Integral cone gear transmission achieves 98% transmission efficiency
• Wear-resistant volute structure enhances air classification efficiency

With capacity ranging from 3-45 tons per hour depending on model selection, the MTW Series provides the flexibility needed for various production scales in TiO₂ manufacturing. The MTW215G model, with 280kW main motor power and capacity of 15-45 tons/hour, is particularly suitable for medium to large-scale TiO₂ production facilities.

Ultrafine Grinding for Enhanced Reactivity

For the final grinding stage where maximum surface area is critical for efficient acid digestion, the SCM Ultrafine Mill represents the state-of-the-art in comminution technology. Capable of producing powders with fineness ranging from 325 to 2500 mesh (D97≤5μm), this equipment significantly enhances the reactivity of ilmenite in sulfuric acid. The technological advantages include:

• High efficiency and energy savings with capacity twice that of jet mills and 30% lower energy consumption
• High-precision classification with vertical turbine classifiers ensuring precise particle size cut
• Durable design with special material rollers and grinding rings extending service life multiple times
• Environmental protection with pulse dust collection efficiency exceeding international standards and noise levels below 75dB

The SCM series operates through a main motor driving three-layer grinding rings to rotate, with material dispersed to the grinding track by centrifugal force, followed by roller pressing and layered grinding. The SCM1680 model, with 315kW main motor power and capacity of 5.0-25 tons/hour, provides the high capacity needed for large-scale TiO₂ production while maintaining precise particle size control essential for optimal digestion efficiency.

Technical Considerations for Equipment Selection

Material Characteristics and Wear Resistance

Ilmenite’s abrasive nature demands equipment with exceptional wear resistance. The grinding elements must withstand continuous exposure to hard, abrasive particles without significant degradation in performance. Modern mills address this challenge through specialized materials for grinding components, including high-chrome alloys, nickel-hard iron, and ceramic composites that offer extended service life in ilmenite grinding applications.

Particle Size Distribution Control

Precise control over particle size distribution is crucial in TiO₂ production. Over-grinding increases energy consumption unnecessarily, while under-grinding reduces digestion efficiency. Advanced classification systems integrated with grinding mills enable tight control over the product fineness, ensuring optimal particle size for subsequent process stages. The vertical turbine classification system in the SCM Ultrafine Mill exemplifies this capability, providing accurate particle size cuts without coarse powder contamination.

Energy Efficiency Considerations

Grinding operations typically account for a significant portion of energy consumption in TiO₂ production. Modern equipment designs focus on reducing specific energy consumption through optimized grinding mechanisms, efficient classification systems, and intelligent control systems. Comparative studies show that advanced vertical roller mills and ultrafine grinding systems can reduce energy consumption by 30-40% compared to traditional ball mill systems, contributing significantly to overall process economics.

Integration with Downstream Processes

Impact on Digestion Efficiency

The particle size achieved in grinding operations directly influences the digestion stage where ilmenite reacts with sulfuric acid. Finer particles with higher surface area promote more complete reaction, reducing acid consumption and improving TiO₂ yield. Additionally, controlled particle size distribution prevents operational issues such as excessive viscosity or foaming during digestion. The precise control offered by advanced grinding systems ensures optimal conditions for this critical chemical reaction.

Influence on Product Quality

Beyond process efficiency, grinding operations indirectly affect final product quality. Consistent particle size distribution in the ilmenite feed contributes to more uniform crystal growth during hydrolysis and calcination stages, ultimately influencing pigment properties such as opacity, tinting strength, and durability. The ability of modern grinding systems to produce narrow particle size distributions supports the manufacturing of high-grade TiO₂ pigments with consistent quality characteristics.

Environmental and Operational Considerations

Dust Control and Emission Management

Grinding operations generate significant dust that must be contained to meet environmental regulations and protect worker health. Modern grinding equipment incorporates advanced dust collection systems, with pulse-jet dust collectors achieving efficiency rates exceeding international standards. Fully enclosed negative pressure operation in systems like the SCM Ultrafine Mill ensures dust emissions remain below 20mg/m³, addressing one of the key environmental challenges in TiO₂ production.

Noise Reduction Strategies

Industrial grinding operations traditionally generate high noise levels, creating workplace challenges. Contemporary equipment designs incorporate comprehensive noise reduction technologies including acoustic enclosures, vibration damping systems, and optimized mechanical designs that reduce noise levels to 75-80dB, well within acceptable limits for industrial environments.

Future Trends in Grinding Technology for TiO₂ Production

The evolution of grinding technology continues to focus on further reducing energy consumption, enhancing particle size control precision, and increasing equipment reliability. Emerging trends include the integration of artificial intelligence for real-time optimization of grinding parameters, development of advanced wear-resistant materials extending component life, and hybrid systems combining multiple grinding principles for maximum efficiency. These advancements will further improve the economics and environmental performance of TiO₂ production via the sulfate process.

Conclusion

Proper selection and operation of grinding equipment are crucial for efficient and economic production of titanium dioxide via the sulfate process. The transition from traditional ball mills to advanced vertical roller mills and ultrafine grinding systems represents significant progress in addressing the technical challenges of ilmenite processing. Equipment such as the MTW Series Trapezium Mill for intermediate grinding and SCM Ultrafine Mill for final size reduction offer compelling advantages in terms of energy efficiency, particle size control, wear resistance, and environmental performance. As TiO₂ manufacturers face increasing pressure to improve efficiency and reduce environmental impact, continued innovation in grinding technology will play a vital role in shaping the future of the industry.