Mekhanobr Engineering CJSC (Russia):

Maksimov I. I., Doctor of Engineering Sciences, Professor, Deputy General Director on Scientific Work

Otrozhdyonnova L. А., Ph. D. in Engineering Sciences, Leading Researcher

Zavarina R. I., Researcher

Yegorova V. G., Researcher

Belov А. Ye., Engineer

E-mail (common): science@mekhanobr.spb.ru

A technology, developed for beneficiation of sulfide copper ores with low lead content, requires addition of potassium bichromate into sulfide copper flotation cycle in order to increase copper concentrate grade through depression of lead minerals, remaining in flotation slurry. Potassium bichromate consumption is 225 g/t, with that, Cr (VI) ions concentration in flotation tailings exceeds the sanitary norms several times over. The paper presents a brief review of application of waste water purification methods from Cr (VI) compounds by means of reagents, as described in the literature. It is shown, that reducing agent dosage depends on Cr (VI) starting concentration in waste water and upon рН of purified water. Sodium sulfite was applied for waste water purification from Cr (VI) compounds, and tested for a wide pH range. It was established, that the best results were provided through decrease of starting water рН (рН = 8) to рН = 3 by means of its acidization. Waste water heating was not required.Two stages of purification from Cr (VI) and Cr (III) were joined into one operation through addition of solid flotation tailings to purification cycle. Duration of purification operation was ~ 15 min. The paper presents the purification circuit flow sheet, and shows Cr (VI) and Cr (III) contents in discharged water — 0.01 and 0.03 mg/dm³, respectively.

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