Extraction of Zinc from Hydrochloric Acid Media Using Secondary Carboprimary Amine Extraction System

Abstract

Spent pickle liquor is a kind of perilous liquid rubbish containing of zinc, iron ions and other environmentally harmful elements. Therefore, the discharging of solution is limited due to the ecological environment issues. A novel cleaning process for the recovery of zinc from spent pickle liquor using solvent extraction is proposed. The extraction system is composed of secondary carboprimary amine(N1923), isooctanol and kerosene. The spent pickle liquor after ultrasonic enhanced reduction pretreatment is studied experimentally, and the effective parameters such as the concentration of extractant, organic phase composition and phase ratio on the extraction are investigated. The concentration of zinc ions in raffinate is only 0.01 g/L by three-stage counter-current extraction, and the raffinate can be used to prepare iron salt water purifier. H2SO4 solution is used to strip the loaded organic phase to obtain zinc-rich solution with 5.39 mol/L zinc, and the zinc-rich solution from the process can be used to prepare zinc oxide. The stripping unloaded organic phase can be recirculated and no emulsification or scale accumulation is observed during the process. Kinetic, slope method, FT-IR, HRMS and Raman are used in combination with density functional theory (DFT) to analyze the extraction mechanism and the structure of the extraction complexes, the results showed that the extraction mechanism of N1923 is in accordance with the pseudo primary kinetic model, the stoichiometric ratio of the extraction reaction is 1, which is anion-exchange, and the extraction complex is [(RNH3)ZnCl3]. An efficient, low-consumption, convenient, safe and sustainable treatment method was provided for the recovery of zinc from pickling waste streams, and lays the foundation for industrialization.

Keywords: Solvent extraction, Ultrasonic enhanced reduction, Spent pickle liquor, Exchange of anions