Obtaining pigment material by conversion of green vitriol in the presence of inorganic additives

The process of obtaining pigment materials in the FeSO₄ – H₂SO₄ – CaCO₃ – M – O_2(air) – H₂O system, where M is inorganic additive (Al₂(SO₄)₃, H₃PO₄, H₃BO₃), using microwave and heat treatment, has been studied. The dependence of the degree of conversion of Fe (II) compounds on the process conditions and chemical composition of inorganic additive has been established. It is shown that the degree of conversion of Fe (II) compounds in the presence of Al₂(SO₄)₃ under given conditions is 1.5–2.0 times higher than that for H₃PO₄ and H₃BO₃. The difference in the phase and dispersed composition of pigment materials obtained after microwave and heat treatment of the reaction mixture in the presence of Al₂(SO₄)₃, H₃PO₄, H₃BO₃ is noted. It was found that the studied iron–calcium-containing produkts mainly contain a highly dispersed phase with a particle size of 0.1–10.0 microns, have pigment properties and are characterized by a rich red-brown color, the shades of which are influenced by the composition of the inorganic additive.

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