Selective leaching of Zn from spent alkaline batteries using environmentally friendly approaches

• Type: Article in International Scientific Journal
• Date: 2017

Authors

Sadeghi, SM (Author) Other; Vanpeteghem, G (Author) Other; Neto, IFF (Author) Other; Helena Soares (Author) FEUP

Journal

Title: Waste Management

Vol. 60

Pages: 696-705

ISSN: 0956-053X

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 16 Citations

Scopus - 24 Citations

Other information

Authenticus ID: P-00M-K8D

DOI: 10.1016/j.wasman.2016.12.002

Abstract (EN): The main aim of this work was to evaluate the possibility of using microwave or ultrasound to assist the efficient and selective leaching of Zn from spent alkaline batteries and compare the results with those obtained using the conventional method. Two different strategies were applied: acid leaching of a washed residue and alkaline leaching of the original residue. In both (acid and alkaline) approaches, the use of microwave- or ultrasound-assisted leaching increased the extraction of Zn compared with the best results obtained using conventional leaching [acid leaching (1.5 mol/L H2SO4, 3 h, 80 degrees C), 90% of Zn extracted; alkaline leaching (6 mol/L NaOH, 3 h, 80 degrees C), 42% of Zn extracted]. With acid leaching, 94% of the Zn was extracted using microwave-assisted leaching (1 cycle, 30 s, 1 mol/L H2SO4), and 92% of the Zn was extracted using ultrasound-assisted leaching (2 min, 0.1p, 20% amplitude, 1 mol/L H2SO4). Ultrasound-assisted leaching resulted in a more selective (Zn/Mn ratio of 5.1) Zn extraction than microwave-assisted leaching (Zn/Mn ratio of 3.5); both processes generated a concentrated Zn solution (>= 18.7 g/L) with a purity (83.3% and 77.7%, respectively) that was suitable for electrowinning. With alkaline leaching, microwave- (1 cycle, 3 min, 4 mol/L NaOH) and ultrasound-assisted (14 min, 0.1p, 20% amplitude, 4 mol/L NaOH) leaching extracted about 80% of the Zn and less than 0.01% of the Mn, which resulted in lesser concentrated Zn solutions (approximately 16.5 g/L) but with high purity (>99.5%) that was suitable for the recovery of Zn by precipitation. The microwave- and ultrasound-assisted leaching strategies used in this work proved to be efficient and environmentally-friendly approaches for the extraction of Zn from spent alkaline residues since a concentrated Zn solution with adequate purity for subsequent Zn recovery was obtained using significantly decreased leaching times and concentrations of chemicals.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10