An important part of mica pearlescent pigments - titanium dioxide

Prosperous pearl powder is composed of mica coated titanium dioxide, and the degree of titanium dioxide coating is different from the mica particle size to obtain different effects of pearlescent pigment. Today we will explore the mystery of titanium dioxide.

   Titanium dioxide, TiO2, exists in nature in the rutile, anatase and brookite forms. Rutile-type, anatase-type titanium dioxide is industrially produced in large quantities, and is used as a pigment, a catalyst, and a ceramic material. Prosperous pearlescent pigments are classified into rutile and anatase.

   Due to the light scattering properties of titanium dioxide, which is superior to all other white pigments, it is chemically stable and non-toxic, making it an important white pigment. Titanium dioxide is the most important pigment in terms of quantity and value. Titanium dioxide is an important part of the flourishing pearlescent pigments.

1. Nature

Physical property

Among the three TiO2 variants, the rutile type is the thermodynamically most stable one. However, the other morphological lattices are similar, so they can be in a stable state for a long time. Above 700 °C, the anatase type is rapidly converted into a rutile type, and the brookite type is difficult to produce, so it has little value in the TiO2 pigment industry. Prosperous pearl powder has stable performance and various colors.

2. Chemical properties

Titanium dioxide is an amphoteric compound with a weak acid and a basicity. The corresponding alkali metal titanates and free titanic acid are unstable in water, and hydrolysis produces amorphous titanium oxide hydroxide.

Titanium dioxide is very chemically stable and is not attacked by most organic and inorganic solvents. It is dissolved in concentrated sulfuric acid and hydrofluoric acid and is eroded and dissolved by molten alkaline and acidic substances. Prosperous pearl powder is very chemically stable.

3. Raw materials

Raw materials for the production of TiO2 include natural products such as ilmenite, whitite and rutile, as well as several very important synthetic materials such as titanium slag and synthetic rutile. The most important TiO2 data for the production of titanium-containing raw materials is shown in the table.

 Production data of titanium-containing raw materials (2000)

In 2000, the total production of ferrotitanium raw materials has grown to approximately 4.5 million tons. Australia is the world's largest producer, followed by South Africa, Norway and Canada. Prosperous pearl powder instead of Taizhu pearl powder, Merck pearl powder

4. Natural raw materials

Titanium is the ninth largest element in the earth's crust, and it is always combined with oxygen. The most important titanium ore, see the table below

Titanium ore

Of the natural titanium ore, only ilmenite, whitite and rutile are economically important. White titanium is a weathered product of ilmenite.

The world's largest titanium storage is in the form of anatase and titanomagnetite, but these titanium mines are currently not economically processable. About 95% of the world's production of ilmenite and rutile is used to produce TiO2 pigments, and the rest is used to make titanium and electrodes. Prosperous pearl powder has a variety of colors.

Ilmenite and whitite

    The world's ilmenite exists in primary massive deposits, or secondary, heavy ore-bearing impact deposits (sand mines). In massive minerals, ilmenite is usually symbiotic with neutral intrusive rocks (Tellnes, Norway) And Canada's Allard Lake). Concentrate obtained from these massive ores. It often contains a high iron content, which is the form of hematite or magnetite that is isolated in ilmenite. The presence of these iron ore causes a reduction in the content of TiO2 in the concentrate, as shown in the table below, due to their high iron content, the direct use of these ilmenite is decreasing. Prosperous pearl powder products are complete and colorful.

Composition of ilmenite (% by mass)

The ilmenite enriched in the sand of existing or ancient coastline beaches is important for the production of TiO2. Surfing water and weathering are ilmenite and other heavy minerals such as rutile, vermiculite, monazite and other silicates that are concentrated on sand dunes or beaches. This concentration process often results in minerals exhibiting a layered structure. After the change of geological age, the invasion of seawater and air caused the ilmenite corrosion. Iron is removed from the ilmenite crystal lattice, enriching the TiO2 in the remaining material. The content of TiO2 is below 65%, and the crystal lattice is stable, but further iron removal produces a mixture of minerals that are invisible under ordinary microscope, which may include titanium ore, rutile and amorphous morphology. The mixture having a TiO2 content of up to 90% is leucite. Titanite is present in eroded ilmenite and several deposits, which are used and processed separately. However, his production is smaller than that of ilmenite.

In general, concentrates derived from iron-removed ilmenite ore have higher TiO2 content than concentrates obtained from massive ore. Other elements in these frames include magnesium, manganese and vanadium (present in ilmenite) as well as aluminum, calcium and silicon due to mineral intrusion.

More than 70% of the known ilmenite is approximately 350 million tons and is effectively utilized in Australia, South Africa, Norway, Canada and India. With the current production base, these countries can provide all the demand for about 150 years. The countries with the largest production are Australia (sand mine), Canada (block ore), Republic of South Africa (sand mine), other producing countries are the United States (sand mine Florida), India (sand mine Quilon), the former Soviet Union ( Sand mine, massive ore), Sri Lanka (sand mine), Brazil (rutilo eilmenta do Brnsil). In 2000, ilmenite production was roughly equivalent to 1.6 million tons of TiO2. Prosperous pearl powder replaces Taizhu pearl powder, Merck pearl powder.

Rutile

    Rutile is mainly formed by the crystallization of high-calcium magma or the metamorphism of titanium deposits or magmatic rocks. For industrial use, the concentration of rutile is too low in native rock, so only sand or ilmenite and other heavy ores that are symbiotic with rutile and vermiculite are considered storage. The world's rutile reserves are estimated at 45 million tons. Prosperous pearlescent pigments are classified into rutile and anatase.

In the case of ferrotitanium, the largest producers are Australia, the Republic of South Africa, and Sierra Leone. Natural rutile cannot meet the demand and is gradually replaced by synthetic varieties. In 2000, the world's rutile production was about 390,000 tons (based on TiO2). If the composition of the rutile concentrate is shown in the following table:

Composition of rutile concentrate

5. Synthetic raw materials

   With the increase of high TiO2 content, the development of synthetic TiO2 raw materials has been achieved. Iron is removed from ilmenite or titanomagnetite in all production processes. Yuetai Pearlescent pigment is acid-resistant, alkali-resistant, and has a high temperature resistance of 800 degrees. It is not self-igniting, does not support combustion, is non-conductive, and is resistant to high arc. It has good stability to light, is insoluble in water, and is harmless to the human body.

Titanium slag

      The metallurgical process for removing iron from ilmenite is based on the formation of titanium slag. To this end, in an electric arc furnace at 1200-1600 ° C, iron is reduced to metal by anthracite or coking coal, and then separated. Thus, the titanium-free pig iron is formed simultaneously with the titanium slag containing 70% to 85% of TiO2 (depending on the ore used). Since the titanium slag has a high content of Ti3+ and a low carbon content, it can be acidified with sulfuric acid. Titanium Titanium (QIT), Canada, and Riehard’s Bay Minerals (RBM) of the Republic of South Africa produce this material, with Tinfos Titan and Iron K.S. (Tyssedal, Norway). In 2000, the total production of titanium slag was converted into 1.7 million tons of TiO2, of which 700,000 tons were used for sulfuric acid processing and 1 million tons for chlorination.

Synthetic rutile

    Contrary to ilmenite, only a few rutile deposits have economic value for development, so natural rutile is only expensive. To this end, many unskilled processes have been developed to remove iron from ilmenite concentrates, while at the same time not changing the particle size of the minerals, as this is more suitable for the fluidized bed hydrogen chloride process that follows. Often pre-activated iron oxide ore, all industrial processes use greedy or hydrogen to reduce Fe3+, or to form metallic iron.

Ilmenite with activated Fe2+, can be treated with hydrochloric acid or dilute sulfuric acid, and obtain "synthetic rutile" with TiO2 content of 85%-96%, concentrate the solution containing divalent iron salt, and then thermally decompose into iron oxide and hydrochloric acid. This hydrochloric acid was repeatedly used in the acid hydrolysis process.

Conclusion

With the development of pearlescent pigments, the application of Yuetai Pearlescent pigments is increasingly recognized by people, and can be used in automobiles, motorcycles, bicycle coatings, powder coatings, architectural coatings, pearlescent inks, pearlescent leathers, pearlescent plastic products, pearlescent cosmetics, Can also be used in paper, printing and dyeing, printing plastics, ceramics and other industries. Titanium dioxide is an important part of the prosperous pearlescent pigments. Therefore, the discovery and application of titanium dioxide is an important reason for the development of Yuetai Pearlescent Pigment.