Dissolution kinetics of low-grade zinc silicate ore in hydroxide solution

A kinetic study of the leaching on a low-grade zinc silicate ore by concentrated sodiun hydroxide (NaOH) solution has been investigated. The effects of reaction time, temperature, NaOH concentration and particle size on the dissolution rate of zinc were examined. It was found that the dissolution rate of zinc is significantly influenced by temperature, particle size and concentration of NaOH solution. When an ore sample of -53+38 µm size was leached for 2 hrs at 85oC in the presence of 5 M sodium hydroxide solution, at liquid:solid ratio of 10:1 and agitation speed of 400 rpm, the zinc recovery was about 78%. The kinetic study indicate that the process is chemically controlled with an activation energy of 52.45 kJ/mol.