PROCESSING METHOD OF CORROSION INHIBITOR CONTAINING COMPOUNDS OF HEXAVALENT CHROMIUM AND SEA WATER Russian patent published in 2020 - IPC C01G37/02 C02F1/62 C02F1/70 C02F9/04 C02F9/10 C22B5/04 C02F101/22 C02F103/08 

FIELD: chemistry.

SUBSTANCE: invention can be used in cleaning solutions containing compounds of hexavalent chromium and sea water, specifically for cleaning spent solution of corrosion inhibitor containing 100–2,000 mg/l of potassium chromate K₂CrO₄. Method of processing a corrosion inhibitor containing a hexavalent chromium compound involves acidifying the starting solution to pH 2–3, treating the acidified solution with a reducing agent with reducing Cr(VI) to Cr(III) and obtaining a precipitate of Cr(III) hydroxide, recovering the obtained precipitate. For neutralization of acidified solution and reduction of Cr(VI) to Cr(III) as reducing agent there used is sodium salt Na₂SO₃ or NaHSO₃. To the obtained solution is added 10–20 % solution of iron sulphate FeSO₄⋅7H₂O or ferric chloride FeCl₂⋅4H₂O. Solution is then neutralized with NaOH solution to pH 8–9, and a flocculant is added. Obtained precipitate is separated by filtration and subjected to two-step thermal treatment, which includes drying at 100–120 °C for at least 2 hours and heat treatment at 300–310 °C for 60–70 minutes. Then, aluminothermic reduction of the treated precipitate is performed to obtain ferrochromium and aluminothermic slag.

EFFECT: invention increases efficiency of processing solutions containing compounds of hexavalent chromium by improving quality of cleaning and recycling precipitation to obtain commercial products.

1 cl, 2 ex, 1 dwg