Iron Oxide Pigment Development Overview and Related Applications (1)

Among various types of pigments, the production and sales volume of iron oxide pigments is second only to titanium dioxide. It is the second largest inorganic pigment and the largest color pigment. Iron oxide pigment has many colors, wide color spectrum, high hiding power and strong coloring power. There are three main colors: red, yellow and black. Through the deployment, the composite pigments of the series of orange, brown and green can also be obtained. Iron oxide pigments have good light, weather, acid, alkali and solvent resistance, and are also non-toxic. They are widely used in construction materials, coatings, inks, plastics, ceramics, papermaking, magnetic recording materials and other industries.

::: Overview of Iron Oxide Pigment Development:::

Among various types of pigments, the production and sales volume of iron oxide pigments is second only to titanium dioxide. It is the second largest inorganic pigment and the largest color pigment. Iron oxide pigment has many colors, wide color spectrum, high hiding power and strong coloring power. There are three main colors: red, yellow and black. Through the deployment, the composite pigments of the series of orange, brown and green can also be obtained. Iron oxide pigments have good light, weather, acid, alkali and solvent resistance, and are also non-toxic. They are widely used in construction materials, coatings, inks, plastics, ceramics, papermaking, magnetic recording materials and other industries.

The titanium dioxide byproduct ferrous sulfate as raw material, can produce many kinds of iron oxide products, is the best way to deal with ferrous sulfate.

1. Ordinary iron oxide pigment

1.1. Production of Iron Red by Calcining

About 80 iron oxide grades are sold on the U.S. market, and about 20 of them are calcined green blushers. Japan's calcined iron oxide production is the largest in the world with an annual output of about 200,000 tons, but its products are mainly used as magnetic materials. material. China's several factories based on the Zibo Cobalt industry are produced by the calcination method, but their products are of lower quality and are not widely used. The quality and the commonly used iron-nitric acid method widely used in China are far from each other.

At present, 60% of iron oxide pigments in the world are used in building materials and 30% in coatings. Both types of iron oxides are required to have good color and dispersibility, and iron oxides used in building materials must also have high tinting strength (low tinting strength will increase the amount of pigments added, affecting the properties of materials such as strength .) The ferro-red particles produced by the green cesium calcination process are relatively large in size, dark in color, and low in coloring power. They can not basically be used in construction materials, which greatly reduces their application range.

1.2. Liquid Iron Oxide Production of Iron Red and Iron Yellow

Sodium ferrous sulfate is neutralized with caustic soda (or ammonia) to form ferrous hydroxide, which is oxidized with air by oxidizing ferrous hydroxide, and ferrous sulfate is oxidized with air in the presence of seed crystals. The ferrous sulfate is continuously added dropwise during the reaction. Alkali (or ammonia), to maintain a certain concentration of ferrous iron and PH, through the control of the development of shade can be obtained from a series of light to dark color iron oxide. The difference between the process of producing iron red and iron yellow is that the preparation conditions of the seed crystal are different, the iron yellow seed is obtained under the acidic condition, and the iron red seed is obtained under the alkaline condition. The production of one ton of iron oxide by air-phase liquid-phase oxidation requires about 3.5 to 4 tons of ferrous sulfate heptahydrate, 3 tons of caustic soda, or 0.45 tons of liquid ammonia.

The production of iron oxide by liquid-phase oxidation is still in the laboratory stage in China, and there are no industrial production devices yet. The main reason is that there is a big gap between the product quality and the mature iron sheet method. In addition, it needs to consume a large amount of alkali or ammonia, and there is no advantage in production cost. However, as one of the effective ways to treat titanium dioxide by-product ferrous sulfate, this is a set of very worthy of research production process, the key is two points: First, find an effective way to control the uniform growth of particles, improve product quality; second is The sodium salt or ammonia salt of the reaction is recycled and used to reduce production costs.

1.2.1. Ammonia iron red

Using ammonia to neutralize ferrous sulfate to alkalinity (PH=8.5~9.5), the primary seed γ-FeOOH was oxidized by air oxidation, and γ-FeOOH was transformed into real nucleation α-Fe2O3 under the induction of Fe2+. A process of renucleation.