Recovery of Metal Values from Secondary Resource

Abstract

The ‎‎input waste was KanthalA4 grade alloy spired in 8-25 mm outer diameter. A sample weighing ≈250 g was leached in HCl or aqua regia at ‎‎room temperature. The acidic leachate was filtered and the pH value was increased ‎to ‎‎4.0 -9.2 with the addition of 3 M ammonia solution. The leachate was freed from iron by H2O2 addition. Chromium ions were separated from nickel ions by pH adjustment and solvent extraction using Lewatite MP 600 ionic exchanger. Ammonium hydroxide gave insoluble hydroxide ppt that was ‎‎filtered and washed. Different organic salts of acetate Ni(OCOCH3)2, oxalate C2O4, citrate C6H6O5 with ∆E of 74.16 KJ/ mol with Ni and 139.33 KJ/ mol with Cr. Inorganic ‎salts were also prepared like Ni(NO3)2.6H2O, dichloride NiCl2, basic carbonate NiCO3.2Ni(OH)2 as well as free ‎metals ‎of nickel and chromium. The effect of the process parameters was ‎studied. The time of synthesis decreased by stirring at 300 rpm by about 11 %. Ascorbic acid solution reduces the Ni and Cr hydroxide to their respective free metal to give spherical nanoparticles ‎having the molecular size of 15-35 nanometer. SEM showed that Ni particles are ‎spherical in morphology. XRD and XDS showed Ni and Cr are pure.