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The use of Primene 81R as extraction agent of chromium present in solid wastes containing nickel, iron and copper has been studied. The waste was leached with a sulphuric acid solution up to pH 3 and oxidation of Cr(III) to Cr(VI) with Caro acid was also studied. Because of the negative result of oxidation, the treatment was applied on Cr(III) directly. Extraction/scrubbing/stripping process was studied in the leach. The composition of organic phase used in the extraction step was 10 % v/v Primene 81R, 10 % isodecanol and kerosene. All the iron, 91 % Cr, 10 % Ni and large part of the copper contained in the initial leach solution are recovered in the organic phase. In the scrubbing stage (with a sulphuric acid solution at pH 1,4), all the copper and nickel and 30 % Cr go to the washing liquor, while all the iron and 70 % Cr remained in the organic phase. In the stripping stage (with a 2N NH 4 OH or 2N NaOH solution) all the iron and chromium are recovered as a precipitate of highly absorbent hydroxides. After the treatment mentioned, 63 % Cr and 100 % Fe are recovered as a mixture of hydroxides, and 28 % of the initial chromium, all the nickel and the copper are found in the washing liquor.

Extracción de cromo con disolventes orgánicos. III parte. Aplicación al tratamiento de residuos polimetálicos industriales