The kinetics of zinc silicate leaching in sodium hydroxide

The alkaline leaching kinetics of a zinc silicate ore assaying 34.1% Zn, 11.1% Fe and 22.9% SiO2 is studied in sodium hydroxide solutions. Speciation diagrams indicate zinc dissolution as [Zn(OH)4]2− and SEM analysis showed a progressive reduction in particle size during leaching which supports the shrinking particle model. The process is chemically controlled with an activation energy of 67.8 ± 9.0 kJ/mol and reaction order with respect to NaOH determined as 1.44 ± 0.46.