Application and preparation of iron oxide yellow

The main component of iron oxide yellow is iron oxide, chemical formula Fe2O3·H2O, is a hydrate of iron oxide. The greatest use of iron oxide is as a pigment. According to the color is divided into iron oxide red, iron oxide yellow, iron oxide black, iron oxide brown by iron oxide red, iron oxide black (and iron oxide yellow) mixed.

Character

Lemon yellow to brown powder. The relative density is 2.44 ~ 3.60. Melting point 350 ~ 400℃. Insoluble in water, alcohol and acid. The fine powder is a crystalline iron oxide hydrate. Due to the different production methods and operating conditions, the degree of hydration, crystal structure and physical properties are very different. Coloring power, covering power, light resistance, acid resistance, alkali resistance, heat resistance are good. Above 150℃, crystalline water is decomposed, and above 400℃, most of it turns red. Inhalation of dust can cause pneumoconiosis, the maximum allowable concentration in the air is 5mg/m2.

Processing method

Method: Ferrous sulfate oxidation method Sulfuric acid and iron filings react to produce ferrous sulfate, add sodium hydroxide and through air oxidation preparation of crystal core, then add ferrous sulfate and iron filings in the suspension of crystal core, heating air oxidation, through pressure filtration, rinsing, drying, grinding to produce iron oxide yellow. The reaction equation is as follows：

Fe+H2SO4→FeSO4+H2↑

FeSO4+2NaOH→Fe(OH)2+Na2SO4

4Fe(OH)2+O2→4FeOOH+2H2O

H2SO4+Fe+7H2O→FeSO4·7H2O+H2↑

FeSO4·7H2O+O2→2Fe2O3·H2O↓+4H2SO4+2H2O

Reaction conditions: 74g iron filings were added into 1000ml 15% sulfuric acid to react until the iron filings disappeared, producing a concentration of about 200g/L ferrous sulfate. Add enough 30% sodium hydroxide into the above solution of ferrous sulfate, and stir continuously to convert 40% of the iron into ferrous hydroxide [Fe(OH)2]. Air is passed at 30 ~ 35℃ to oxidize Fe into Fe and form crystal nuclei. Then 90g/L of iron filings were added to the mixture to generate 7g/L of crystal nucleus and 40g/L of ferrous sulfate. The mixture was heated to 85℃, and the air was pumped at the speed of 600L/h to oxidize for 64h, and then filtered, washed, dried and crushed to produce aqueous iron oxide yellow.

APPLICATION 

1.iron oxide yellow pigmentin all kinds of concrete prefabricated parts and building materials as pigment or coloring agent, directly into the cement application. Various interior and exterior colored concrete surfaces, such as walls, floors, ceilings, pillars, porches, pavements, parking lots, staircases, stations, etc.
2.Iron oxide yellow pigment is suitable for coloring and protection of various coatings, including water-based interior and exterior coatings, powder coatings, etc. 

3.Iron oxide yellow pigment is suitable for coloring plastic products, such as thermosetting plastics and thermoplastics, and rubber products, such as automobile inner tube, aircraft inner tube, bicycle inner tube and so on.
4.widely used in the construction of artificial marble, terrazzo coloring. It is a pigment of watercolor, oil color, paint, rubber,leather and so on. Used as an intermediate of iron oxide pigments, such as iron oxide red, iron black, etc.