Current Research Paper Recovery of zinc from ashes of automobile tire wastes by pH controlled solutions of ammonium chloride KEYWORDS Fly ash; Zinc oxide; Zinc recovery; Leaching; Ammonium chloride. ABSTRACT This paper concerns the recovery of zinc from fly ashes generated by incineration plant of automobile tire wastes. The recovery is obtained by two extraction steps with a pH-controlled ammonia chloride solution. The ashes contain about 51% wt of zinc, 1% wt of iron and aluminium and small quantities (less than 0.1% wt) of cobalt, copper and lead. Various factors affect the performance and efficiency of leaching: temperature, concentration, pH and time were studied using a factorial experimental design. After two steps with ammonium chloride 3mol/L, L/S=6 ml/g, pH 5.4–0.1 and T=72–3C the leaching liquor has been purified in a simple step by cementation with metallic zinc powder without activation. Traces of Pb, As, Sb, Se, Mo, Ni have been cleared by cementation with zinc. The fly ash and residue composition was determined by X-ray and its elemental composition by ICP-OES and IC. The obtained results show that recovery efficiency amounts to 98% wt for zinc; the concentration of zinc in the leach liquors reaches more than 45 g/L while most of the iron is not leached. The purified solution containing zinc allows the direct recovery of high grade zinc by electro-deposition.  2008 Trade Science Inc. - INDIA INTRODUCTION The absolute prohibition of disposing tires in any form, also grinded , in dumping sites has come in force in Italy beginning from July 2006 following the most recent European legislation. The accomplishing of this regulation will involve an increase of the activities concerning the tire disposal: retread activities, energy and material recovery, pyrolysis etc. According to ETRA (European Tyre Recycling Association) data, the percent of tires disposed in dumping decreased from 62% in 1992 down to 26.4% in 2003. The share destined to energy recovery, on the contrary, increased from 14% up to 24.4% in the same period [1] . The results obtained by incinerating the tires in the modern, high technological plants show that is possible to comply with both economical (energy and material recovery) and ecological (low emissions) requirements. It can be F.Baldassarre 1 , P.Bruno 1 , M.Caselli 1 *, P.Ielpo 1 , G.Cornacchia 2 , A.Canonico 2 , G.Chita 3 1 Dipartimento di Chimica, Universita degli studi di Bari, Via Orabona 4, 70126 Bari, (ITALY) 2 Enea ACS PROT-STP, CR Trisaia (Matera), SS106 Jonica Km 419+500, (ITALY) 3 CNR , Istituto di cristallografia, Via G.Amendola 122, Bari, (ITALY) Tel: 00390805442021; Fax 00390805442129 E-mail: caselli@chimica.uniba.it Received: 5 th March, 2008 ; Accepted: 10 th March, 2008 Environmental Science An Indian Journal Trade Science Inc. Volume 3 Issue 2 ESAIJ, 3(2), 2008 [206-211] April 2008 Environmental Science