استخراج فلز روی از کانیهای سیلیکاتی به روش هیدرومتالورژی

Abstract:

Zinc is found in Iran mainly as oxidized ores; Silicate phases :

Hemimorphite, Zn۴(OH)۲Si۲O۷.H۲O and Willemite , Zn۲SiO۴

, and also as the Carbonate phases like Hydrozincite, Zn۵(CO۳)۲(OH)۶ and Smiths-onite, ZnCO۳.

Various processing techniques show that the non-silicate minerals can be easily leached by acid. Willemite and the hemimorphite phases can also be leached by acid. However, zinc recovery apparently is poor this phenomena has been described to chelation or adsorption of Zn ion by colloidal /polymeric sillicic acid.

Colloidal silica forms an unfilterable gel or poorly filterabel gelatious percipitate which concludes all or much of the zinc sulfate that can only be washed with difficulty using an excessive quantity of wash water. Besides of the costs, this causes the dilution of the zinc sulfate solution.

In this research , the effects of pH, temperature, time, ionic strenght and the zinc content of ore on the zinc recovery in leaching the silicate ores in sulfuric acid and converting the colloidal silica to an easily filterable form, have been tested.

Neutralisation , coagulation and percipitation of silicic acid by Al۳+ and Fe(III) ions, distinctly improve zinc recovery.

Dehydration of silica by evapuration the water in leach solution or the  fast leaching technique also have been practiced .

Recovery of zinc more than ۹۰% is obtaind