1. Introduction of Titanium dioxide

TiO₂ (CAS No. 13463-67-7) has three crystal habits which are brookite, anatase and rutile. Among these, brookite is usually existed in ore in natural world, and people usually use the anatase and rutile types to obtain titanium dioxide. As it exists natually in titanium ore, rutile and other titanium ores, it should be chemically extracted and purified before use.

Titanium dioxide is a kind of white pigment in industrial field. The application is so wide that requirements for titanium dioxide is very large. The well-known titanium dioxide process are Sulphate Process and Chloride Process. And 56% of the titanium dioxide manufacture are coming from Chloride Process, 70% of which come from big manufacturer in U.S. like Dupont, while other countries are mainly using the Sulphate Process. One big titanium dioxide manufacturer - Shanghai Titanos Industry Co., Ltd is a leading producer who uses the method of Sulfuric acid in China.
 

2. Three Different Titanium Dioxide Production Methods

1). Sulfate Process

One typical titanium dioxide production method - Sulfate Process is usually based on the batch method, which features as flexible production equipments and adjustable production load. And this method could produce anatase titanium dioxide and rutile type products. However, for its good complex technology, it needs more than 20 steps to give good-qualitytitanium dioxide.

The detailed titanium dioxide manufacturing method- Sulfate Process is as below: Mix smashed rutile / high titanium slag and hard coke to react with chlorine to give titanium tetrachloride. Secondly, the products is being purified and then be oxidized to have titanium dioxide. Finally, go through a listing of processes as drying and smashing to give the final product titanium dioxide.

The titanium dioxide manufacturing process is clearly explained by the following reaction equations:  
2TiO₂ + 3C + 4Cl₂→2TiCl₄ + 2CO↑+ CO₂↑
TiCl₄+O₂→TiO₂ + 2Cl₂

2). Chloride Process

Another itanium dioxide manufacturing method - Chloride Process is usually supposed to be much more qualified than others, for it is usually obained in continuous manufacturing. Its production method is much more simpler, with less control points in titanium dioxide manufacture. However, it also has its disadvantages. As it should be produced in continuing manufacturing, the operation of the production equipment has low flexibility, and then the manufacturers will face the problem of unadjustable production load.

This titanium dioxide process is as below: Firstly, utilize the ilmenite as raw material to have acidolysis in sulfuric acid to produce iron(II) sulfate; Then the by-product is being processed in acid water to have titanium salt in the digestion solution; Thirdly, the solution go through a listing of processes of filtering, fractionation, and others to give pure titanium dioxide.

The titanium dioxide manufacturing process could be clearly showed by the following reaction equations:
H₂SO₄ + TiO₂→TiOSO₄ + H₂O
Ti(SO₄)₂ + H₂O→ TiOSO₄ + H₂SO₄
TiOSO₄ + H₂O→H₂TiO₃↓+ H₂SO₄ H₂TiO₃·SO₃→TiO₂+H₂O+SO₃↑

3). Hydrochloric Acid Process

At the same time, foreign big companies are continuously develping superfine nanometer titanium dioxide and new products with special properties. The nanometer titanium dioxide has wide applications in many fields, such as industrial catalysis, functional materials, hydrogen storage material and efficient filling materials and so on. Besides, some special technology has been developed. Alatir Nano-materials Inc. has develped one new production technology which is called Hydrochloric Acid Process.

The main technology routes are as below:



3. Aftertreatment of Titanium dioxide

The products obtained from the above three titanium dioxide manufacture methods are pure products, and it should be delt with improving its application performance to enhance its properties, such as weather resistance, wettability, covering power, gloss and dispersibility in many different medium solvents, plastic, colloid solutions and so on.

Therefore a listing of aftertreatment are needed, including wet grinding, inorganic films, washing, drying, Jet Milling and others. The coating is specially important in aftertreatment, usually including wet process and dry process.

One usual coating way is as below:
Al₂ (SO₄ )₃ + 4NaOH → Al₂O₃ + 2Na₂ SO₄ + 2H₂O
H₂SO₄ + 2NaAlO₂ → Al₂O₃ + Na₂SO₄ + H₂O
Na₂SiO₃ + H₂SO₄ → SiO₂ inH₂O + Na₂SO₄ + H₂O
4NaOH + Zr(SO₄)₂ → ZrO₂ + 2Na₂SO₄ + H₂O

After treatment, TiO₂ is provided with good performance to be used in the market.