Titanium Dioxide Production via Ammonium Fluoride Leaching
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Solution Overview
Problem
Current processes for producing titanium dioxide from titanium ores containing iron result in impurities, instability, unsatisfactory particle size, and environmental hazards, with high costs and by-product disposal issues.
Innovation Solution
A process involving the reaction of titanium ores with ammonium fluoride, followed by hydrolysis and pyrohydrolysis stages, effectively separates titanium and iron, producing stable titanium dioxide with controlled particle size and recycling ammonia and ammonium fluoride, eliminating waste products and reducing energy expenditure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional processes are used to produce titanium dioxide from titanium ores containing iron, then production cost and complexity are reduced, but the resulting titanium dioxide has unsatisfactory purity, stability and particle size
Solution Approach 1:
The patent applies parameter changes by conducting hydrolysis at two distinct pH stages (first at pH 7.0-8.5, then at pH 10.0-13.0) and pyrohydrolysis at two temperature stages (first at maximum 450°C, then at maximum 1000°C). These controlled parameter variations enable precise separation of titanium from iron impurities while controlling particle size to 0.1-4.0 μm, achieving high manufacturing precision through systematic parameter optimization.
Solution Approach 2:
The patent segments the production process into distinct sequential stages: (a) leaching with ammonium fluoride, (b) filtration to separate solid residue, (c) two-stage hydrolysis at different pH levels, (d) second filtration, and (e) two-stage pyrohydrolysis at different temperatures. This segmentation allows each stage to optimize for specific separation and purification objectives, achieving high purity titanium dioxide while making the overall process manageable and controllable.
2Loss of substance
If conventional processes are used to produce titanium dioxide, then energy expenditure is reduced, but waste by-products are produced that require disposal
Solution Approach 1:
The patent recovers and recycles ammonia evolved during hydrolysis and ammonium fluoride used in leaching, converting waste streams into reusable materials. The iron content is transformed into Fe2O3 red pigment, a valuable commercial product. This recovery approach eliminates waste by-products while the energy consumption is reduced through optimized process conditions and heat management in the pyrohydrolysis stages.
3Reliability
If conventional processes are used to produce titanium dioxide, then production speed is maintained, but the titanium dioxide obtained has unsatisfactory stability under UV irradiation
Solution Approach 1:
The patent performs preliminary purification actions by removing iron impurities through selective leaching with ammonium fluoride and staged hydrolysis before the final pyrohydrolysis step. This preliminary removal of destabilizing impurities ensures that the titanium dioxide produced has high UV stability (6-7 times more stable than conventional products) while maintaining production efficiency through continuous process optimization and direct marketing quality achievement.
4Manufacturing precision
If multi-stage hydrolysis and pyrohydrolysis are implemented, then titanium dioxide stability and purity are improved, but process complexity increases
Solution Approach 1:
The patent uses systematic parameter changes across two hydrolysis stages (pH 7.0-8.5 then pH 10.0-13.0) and two pyrohydrolysis stages (maximum 450°C then maximum 1000°C) to achieve progressive separation and purification. Each parameter change targets specific chemical equilibria to maximize titanium recovery while leaving iron in the solid residue, achieving high purity through controlled thermodynamic and kinetic conditions rather than complex mechanical separation equipment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process yields titanium dioxide that is 6-7 times more stable under UV irradiation, with a suitable particle size for direct marketing, no waste by-products, and the iron content is converted into a valuable red pigment, while reducing energy consumption and environmental impact.
Implementation Method 1
A process for the separation of iron from titanium based on their different solubilities in ammonium fluoride solution is described
Implementation Method 2
the aqueous solution thus obtained is subjected to hydrolysis, the hydrolysis comprising a first stage at pH 7.0-8.5 and a second stage at pH 10.0-13.0
Implementation Method 3
the solid residue is subjected to pyrohydrolysis, the pyrohydrolysis comprising a first stage at a maximum temperature of 450° C. and a second stage at a maximum temperature of 1000° C.
Data Source
AI summary
A process is described for the production of titanium dioxide by the treatment with ammonium fluoride of titanium ores containing iron; the process comprises the following steps: (a) the titanium ore containing iron is reacted with an aqueous NH4F and/or NH4HF2 solution; (b) the aqueous dispersion thus obtained is filtered with consequent separation of a solid residue and an aqueous solution containing titanium salts; (c) the aqueous solution thus obtained is subjected to hydrolysis, the hydrolysis comprising a first stage at pH 7.0-8.5 and a second stage at pH 10.0-13.0; (d) the aqueous dispersion thus obtained is filtered and the solid residue is subjected to pyrohydrolysis, the pyrohydrolysis comprising a first stage at a maximum temperature of 450° C. and a second stage at a maximum temperature of 1000° C.