Kinetics of pressure leaching of niobium ore by sulfuric acid

• Kinetics of pressure leaching of niobium ore by sulfuric acid is firstly investigated.
• Under the optimum conditions, over 98% niobium was leached.
• The oxygen pressure had little effect.
• The leaching of niobium in sulfuric acid media depends largely on the temperature.
• The linear kinetics model 1-(1 − x)1/3 = kt represents the niobium leaching well.

The current study was carried out to investigate the kinetics of pressure leaching of niobium ore in sulfuric acid media. The effects of stirring speed, oxygen pressure, sulfuric acid concentration, particle size and temperature on the leaching efficiency of niobium were studied. It was found that over 98% niobium was leached by mixing the ground ore to − 74 μm with sulfuric acid concentration 10 M, and heating for 2 h at 200 °C. The pressure leaching of niobium ore in sulfuric acid solution depends largely on the temperature and follows a surface reaction control kinetic model. An activation energy value of 43 kJ/mol was determined for the temperature range of 100 °C to 200 °C.