Red Magician in Life -- Iron Oxide Red

Iron oxide red, also known as iron red, ferric oxide, etc., is a red or dark red powder with a chemical formula of Fe₂O₃; its particle size range is between 0.5 and 2μm, density is about 5.25g/cm³, melting point is 1565℃, it is non-toxic, insoluble in water, but soluble in hydrochloric acid and sulfuric acid. Iron oxide red has high hiding power and tinting power, and its light resistance, heat resistance, alkali resistance, dilute acid and corrosive gas resistance are excellent; it is an ideal pigment and colorant, playing an important role in the world of color.

Production process

Dry process

Green vitriol calcination method: This process uses steel pickling liquid and sulfuric acid titanium dioxide byproduct-green vitriol (FeSO₄·7H₂O) as raw materials, and calcined to obtain iron red. The product color is controlled by calcination temperature and time.

Iron yellow calcination method: Use dry iron yellow powder and calcine it in a calcination furnace to obtain brown iron oxide red. The color is affected by the calcination temperature, iron yellow particle size and calcination time.

Iron black calcination method: The cleaned iron black is calcined at high temperature to oxidize FeO to Fe₂O₃. The product color is affected by the calcination temperature, calcination time and iron black particle size.

Ferrous sulfate-soda ash calcination method: Soda ash (Na₂CO₃) and green vitriol (FeSO₄·7H₂O) are mixed in a molar ratio of 1:1.25, and iron red is obtained through a calcination process. This method is carried out at a temperature of 700°C, and the product is a finished product after washing and drying.

Wet process

Sulfate method: This method first manufactures seed crystals, then puts the seed crystals into a reaction tank containing Fe²⁺ solution, introduces oxygen, oxidizes Fe²⁺ to Fe³⁺, and then combines with OH⁻ in water and deposits on the surface of the seed crystals, gradually forming red iron oxide. This method has a long production cycle, but can produce iron red of various shades, and the product particles are soft and easy to disperse.

Nitrate method: Similar to the sulfate method, but using nitrate as a reactant, this method is more expensive, but the product performance is better.

Mixed salt method: It is a compromise between the sulfate method and the nitrate method. The cost is close to the sulfate method, while the performance is between the sulfate method and the nitrate method. It strikes a balance between production cycle and performance.

Application field

Building and building product materials: Red iron oxide is widely used as a pigment or colorant in the construction field, covering indoor and outdoor concrete surfaces such as walls, floors, ceilings, etc., as well as architectural ceramics and glazed ceramics, such as tiles, floor tiles, roof tiles, etc.

Coatings and protective substances: Red iron oxide is not only used for coloring various coatings, but also used in water-based interior and exterior wall coatings, powder coatings, oil-based paints, toy paints, decorative paints, furniture paints, etc. It not only stabilizes the color, but also provides protection and prolongs the service life of the product.

Plastic products and rubber products: In the production of plastic and rubber products, red iron oxide is widely used as a colorant, including thermosetting plastics, thermoplastics, and rubber products such as automobile inner tubes, aircraft inner tubes, and bicycle inner tubes.

Industrial use: Red iron oxide is widely used in the industrial field, especially in the construction, rubber, plastics and coatings industries. It is not only an important component of colored cement, concrete floor tiles, terrazzo and other fields in the construction industry, but also plays a key role in coatings, paints, hardware products and other industries.

Other applications: Red iron oxide also plays an important role in cosmetics, paper, leather and other fields, giving natural and bright colors to cosmetics and providing unique coloring effects for paper and leather products.