ZINC RECOVERY FROM TYRE ASHES: A PROFITABLE AND CLEAN SOLUTION TO THE PROBLEM

摘要

A hydrometallurgical process, already developed and fully tested at industrial scale for other primary and secondary raw material applications, is proposed as an easy, clean and profitable treatment for the recycling of tyre ashes. Using the Modified ZINCEX Process an ultra pure zinc solution is obtained from the zinc oxide present in the ashes of tyres (65-75%). The zinc is recovered after three simple stages: dissolving by leaching under atmospheric pressure, mild acid and other soft conditions, purifying by zinc solvent extraction, and finally product recovery. The product can be recovered as SHG zinc metal by electrowinning, zinc oxide or hydroxide by precipitation, or zinc salts by crystallisation or evaporation. The type of product recovered will depend on the particular conditions of capacity, recycling needs, market conditions, and/or installations, etc...This treatment, if applied, will enhance and substantially increase the economical profitability, reducing waste and simultaneously increasing the total product recycling of used tyres. Typical results are: very high zinc yields (consistently higher than 98%), hardly any leaching residues (less than 40%), low operating costs and, above all, an extremely pure product.