%0 Journal Article
%T Extraction of Zinc and Manganese from Alkaline and Zinc-Carbon Spent Batteries by Citric-Sulphuric Acid Solution
%A Francesco Ferella
%A Ida De Michelis
%A Francesca Beolchini
%A Valentina Innocenzi
%A Francesco Vegli¨°
%J International Journal of Chemical Engineering
%D 2010
%I Hindawi Publishing Corporation
%R 10.1155/2010/659434
%X The paper is focused on the recovery of zinc and manganese from alkaline and zinc-carbon spent batteries. Metals are extracted by sulphuric acid leaching in the presence of citric acid as reducing agent. Leaching tests are carried out according to a full factorial design, and empirical equations for Mn and Zn extraction yields are determined from experimental data as a function of pulp density, sulphuric acid concentration, temperature, and citric acid concentration. The highest values experimentally observed for extraction yields were 97% of manganese and 100% of zinc, under the following operating conditions: temperature , pulp density 20%, sulphuric acid concentration 1.8£¿M, and citric acid 40£¿g . A second series of leaching tests is also performed to derive other empirical models to predict zinc and manganese extraction. Precipitation tests, aimed both at investigating precipitation of zinc during leaching and at evaluating recovery options of zinc and manganese, show that a quantitative precipitation of zinc can be reached but a coprecipitation of nearly 30% of manganese also takes place. The achieved results allow to propose a battery recycling process based on a countercurrent reducing leaching by citric acid in sulphuric solution. 1. Introduction The battery market is steadily increasing worldwide: this behaviour requires a new approach in the management of these devices once they are exhausted [1]. In many countries alkaline and zinc-carbon spent batteries were still landfilled or incinerated up to the end of 2008, instead of being recycled, recovering valuable secondary raw materials and avoiding dispersion of heavy metals in the environment. Several European Countries have autonomously developed national collection systems and infrastructures to collect and recycle all kinds of portable batteries, despite the old Directive 91/157/EEC EEC (and subsequent amending acts of Directives 93/86/EEC and 98/101/EC) that covered only batteries and accumulators containing more than 0.0005% mercury, more than 0.025% cadmium, and more than 0.4% lead (percentages by weight) [2]. These Countries have arranged a financing system that is able to cover all costs related to the recycling activities by applying a surcharge on battery selling price [1]. In 2007 members of the European Battery Recycling Association (EBRA) recycled about 31,079 tonnes of portable batteries and accumulators: compared to the previous year there was a little improvement (30,865 tonnes in 2006) [3]. In more detail, quantities of batteries recycled by EBRA¡¯s members were 26,941 tonnes
%U http://www.hindawi.com/journals/ijce/2010/659434/