D. De Juan et al., Chromium extraction with organic solvents - Part 3. Application to the treatment of polymetallic industrial residues, REV METAL M, 34(5), 1998, pp. 391-398
The use of Primene 81R as extraction agent of chromium present in solid was
tes containing nickel, iron and copper has been studied. The waste was leac
hed with a sulphuric acid solution up to pH 3 and oxidation of Cr(III) to C
r(VI) with Care acid was also studied. Because of the negative result of ox
idation, the treatment was applied on Cr(III) directly. Extraction/scrubbin
g/stripping process was studied in the leach. The composition of organic ph
ase used in the extraction step was 10 % v/v Primene 81R, 10 % isodecanol a
nd kerosene. All the iron, 91 % Cr, 10 % Ni and large parr of the copper co
ntained in the initial leach solution are recovered in the organic phase. I
n the scrubbing stage (with a sulphuric acid solution at pH 1,4), all the c
opper and nickel and 30 % Cr go to the washing liquor, while all the iron a
nd 70 % Cr remained in the organic phase. In the stripping stage (with a 2N
NH4OH or 2N NaOH solution) all the iron and chromium an recovered as a pre
cipitate 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 l
iquor.