Extraction of acid and iron values from sulphate waste pickle liquor of a steel industry by solvent extraction route

Abstract

The extraction of sulphuric acid from the actual solutions generated during the process of pickling of steel from a local tube company dealing with the processing of iron and steel tubes using Alamine 336 has been studied in detail. Various parameters were optimised for the maximum extraction of acid such as concentration of organic extractant, time for equilibration, O/A ratio, acid concentration in the feed, temperature for extraction was varied from 30 to 60 °C. Stripping of loaded acid was done with distilled water at 60 °C. Stripping parameters studied were, temperature and time effect on equilibration, O/A ratio, multiple contact of the same strippant with fresh loaded organic. The effects of the numbers of extraction and stripping stages on the extraction and stripping of sulphuric acid recovery are discussed. After the extraction of acid from WPL, iron values in the raffinate were extracted with a binary solvent mixture consisting of MIBK and D2EHPA which shows a synergistic effect on iron extraction.