METHOD FOR PRODUCING IRON- AND MANGANESE-CONTAINING PIGMENTS FROM INDUSTRIAL WASTE Russian patent published in 2021 - IPC C01G49/06 C01G45/02 C01F5/40 C08K3/13 C08K3/22 

FIELD: chemistry.

SUBSTANCE: invention relates to the field of metallurgical and chemical technology of inorganic substances, namely to processing of manganese-containing waste, and can also be used in production of manganese-containing products. The iron- and manganese-containing pigments are produced from industrial waste including manganese-containing compounds, an oxidising agent, a barium-containing compound, wherein blast furnace processing sludge containing manganese, iron and silicon, aluminium, calcium, magnesium, iron and manganese oxides in the amount of 28 to 31% wt. is used as manganese-containing compound, spent sulphuric acid solution containing 2 to 5% H₂SO₄ and 18 to 20% Fe₂SO₄ in the amount of 47 to 48% wt. is used as an oxidising agent, technical barium oxide in the amount of 14 to 15% wt. and additionally carryover dolomite dust in the amount of 8 to 9% wt. are used as a barium-containing compound, wherein the waste is processed in two stages, at the first whereof the blast furnace processing sludge is treated with the spent sulphuric acid solution to a pH of 4.0 to 4.5, the resulting suspension is neutralised by adding the carryover dolomite dust to a pH of 7.0 to 7.5, the residue is isolated from the suspension, dried in a combined "fluidised bed" dryer at a temperature of 320 to 340°C with excess oxygen and simultaneously ground to a particle size of 10 to 15 mcm producing a red iron oxide pigment; and at the second stage, the carryover dolomite dust is added to the filtrate isolated from the residue, upon completing the reactions, a manganese-containing residue is isolated from the resulting suspension, mixed with technical barium oxide and transferred to a combined "fluidised bed" dryer, wherein the mixture is heat-treated at a temperature of 500 to 550°C with excess oxygen and simultaneously ground to a particle size of 10 to 15 mcm producing a green pigment. Additionally, excess water is evaporated from the filtrate isolated from the manganese-containing residue at a temperature below 20°C, magnesium sulphate crystalline hydrate is produced, isolated from the resulting suspension, sent to a combined "fluidised bed" dryer, dried therein at a temperature of 110°C and simultaneously ground to a particle size of 50 to 60 mcm.

EFFECT: producing high quality pigments and reducing the consumption of scarce raw materials; the technology also makes it possible to produce magnesium sulphate crystalline hydrate - epsomite, exhibiting high strength and heat resistance.

1 cl, 1 dwg, 2 tbl, 2 ex