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The Properties and Preparation Methods of Iron Trioxide

wallpapers Industry 2020-09-30

Iron trioxide is an inorganic substance with the chemical formula Fe2O3—red or dark red amorphous powder. The relative density is 5~5.25, and the melting point is 1565°C (decompose at the same time). Insoluble in water, soluble in hydrochloric acid and sulfuric acid, slightly soluble in nitric acid. The hiding power and tinting power are extreme, no oil permeability and water permeability. It is stable in the atmosphere and sunlight, resistant to polluted gases, high temperature and alkali. The dry-process products of this product have coarse and hard crystal particles, which are suitable for magnetic materials, polishing and abrasive materials. Wet-processed products have small and soft crystal particles, which are ideal for coating and ink industry.

Iron trioxide is a red to reddish-brown powder. Odourless. Insoluble in water, organic acids and organic solvents. Soluble in inorganic acid. There are two types: α-type (positive magnetic) and γ-type (diamagnetic). Products produced by the dry process generally have a fineness below 1μm. Stable to light, heat and air. Relatively stable to acid and alkali. Strong tinting power. The relative density is 5.12~5.24. The lower the content, the lower the relative density. The refractive index is 3.042. Melting point is 1550℃, decomposing at 1560℃.

There are wet and dry preparation methods. Wet-process products have fine crystals, soft particles, easy to grind, and easy to use as pigments. Dry-process products have large crystals and hard particles, which are suitable for magnetic materials and polishing materials.

Wet

FeSO4+2NaOH=Fe(OH)2+Na2SO4

4Fe(OH)2+O2+2H2O=4Fe(OH)3

4FeSO4+4H2O+O2=2Fe2O3↓+4H2SO4

Fe+H2SO4=FeSO4+H2↑

Quickly react a certain amount of 5% ferrous sulfate solution with excess sodium hydroxide solution (the alkali excess is required to be 0.04~0.08g/ml), and pass air at room temperature to make it all become reddish-brown ferric hydroxide colloidal solution, As the nucleus of deposited iron oxide. Using the crystal mentioned above the heart as a carrier, ferrous sulfate as a medium, and air, in the presence of metallic iron at 75-85°C, ferrous sulfate reacts with oxygen in the mood to form iron oxide (i.e. iron red) and deposits on the crystal nucleus Above, the sulfate radicals in the solution reacts with the metallic iron to regenerate ferrous sulfate, which is then oxidized by air to form iron-red and continues to deposit, so that the circulation to the end of the whole process will generate red iron oxide.

Nitric acid reacts with iron to produce ferrous nitrate, which is cooled and crystallized, dehydrated and dried, then ground and calcined at 600-700°C for 8-10 hours, washed, dried and crushed to obtain iron oxide red product.

4Fe(NO3)3→2Fe2O3+12NO2↑+3O2↑

Fe2O3·nH2O→Fe2O3+nH2O

Iron oxide yellow can also be used as raw material, and iron oxide red can be obtained by calcining at 600~700℃.


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Tag: Iron Trioxide