Ferrous sulfate oxidation method: add enough 30% sodium hydroxide to the solution containing ferrous sulfate 150g/L under stirring, so that 40% of iron is precipitated as Fe3+(OH)3, and at the same time at 30 ~ 35 ℃, pass through. Air oxidizes Fe2+ to Fe3+, and the pH value drops from 6 to 3.5, forming a crystal nucleus. Then add ferrous sulfate (14 times that of the crystal nucleus), adjust the pH value to 4 with sodium hydroxide, then oxidize at 80 ℃ with air, and then spray dry to obtain goethite iron oxide. The above-mentioned iron oxide is placed in a converter, passed into a hydrogen stream containing 20% water vapor, heated at 425 to 450 ° C, and then heated at 100 to 150 ° C in a nitrogen stream containing 10% air to obtain a ferrous oxide containing ferrous oxide. 28% iron oxide black pigment, the particle length and width are 0.7μm and 0.5μm respectively, the specific surface area is 8m2/g, and the tinting strength is as high as 180%.
MAGNETITE ,The mineral magnetite, ferroferric oxide, Fe3O4, is isometric, commonly occurring in octahedrons, dodecahedrons, and massive, granular, and laminated forms. It is brittle with an uneven fracture; cleavage is not distinct, but with pressure an octahedral parting may develop; hardness, 5.5–6.5; specific gravity, 5.18; luster, metallic to dull; color, iron black, streak, black. It is opaque and strongly magnetic; when possessing polarity it is known as lodestone.
Black mineral, black streak, submetallic or dull to metallic luster. Contains 72.4% iron.
Readily recognized by strong attraction by magnet. Soluble in powder form in hydrochloric acid.
Decomposes at 1538C to ferric oxide Fe2O3.
Diagnostic aid, magnetic resonance imaging (MRI); treatment of iron deficiency.
Black iron oxide (Fe3O4) is a synthetic inorganic pigment,
produced by oxidation of iron (II) hydroxide obtained from the
action of alkali on iron (II) sulfate solution. The composition of the
pigment corresponds with that of magnetite. The pigment is of fine
texture, but has only low tinting strength in paint and other coatings.
It is mainly used as a colorant in fillers, primers, and undercoats.
The major black pigments in the paint industry are carbon blacks.
Structure and conformation
Fe3O4, magnetite [1309-38-2], also has a spinel structure, and has a
black color.
