Development of an efficient process for the recovery of zinc and iron as value added products from the waste chloride solution

• Solvent extraction of Zn and Fe from spent pickle liquor with Cyanex 923 was studied.
• Precipitation-stripping of Zn and Fe was carried out from loaded organic phase.
• Highly pure zinc oxide was produced by calcining the zinc oxalate precipitate.
• Ferrous oxalate precipitated from the stripped solution using scrap Fe-powder.
• Highly pure hematite was produced by calcining the ferrous oxalate precipitate.

The present paper deals with the recovery of the Zn(II) and Fe(II)/Fe(III) from the waste chloride solution of steel industry using solvent extraction and precipitation-stripping process for the synthesis of high purity value added products. The extraction of zinc and iron was performed using Cyanex 923. It was observed that Cyanex 923 selectively extracted Zn(II) and Fe(III) from the acidic chloride solution leaving behind Fe(II) in the raffinate. The loaded organic was stripped efficiently using oxalic acid to precipitate Zn(II) as zinc oxalate and Fe(III) was transferred to the aqueous phase as highly soluble ferric oxalate solution while simultaneously regenerating the Cyanex 923. The zinc oxalate was calcined to obtain the high purity zinc oxide (99.9% pure). Further the ferric oxalate solution was reduced by using Fe-powder to get ferrous oxalate, which on calcination yielded pure hematite. The oxalates and oxides were characterized by chemical analysis, XRD and SEM studies to establish the purity and morphology of the as-synthesised products.

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