Kinetics of leaching selenium from Ni-Mo ore smelter dust using sodium chlorate in a mixture of hydrochloric and sulfuric acids

摘要

The kinetics of leaching selenium from Ni-Mo ore smelter dust in H_2SO_4-HCI-H_2Osystem was investigated.The effects including leaching temperature and time, particle size of the smelting dust, stirring speed, acidconcentration and the coefficient β (the molar ratio of sodium chlorate to selenium in the smelter dust) onleaching of selenium were studied. The results indicated that the leaching of selenium increased sharply withthe increase of temperature. The leaching of selenium reached 98% at 95℃ and stirring speed of 350 rpm for150 min with the particle size of —0.15 mm, initial [H~+] concentration of 8 mol/L, the solid/liquid ratio of1:5 g/mL and the coefficient β of 3.33. The leaching process was controlled by the surface chemical reactionand the kinetics of leaching selenium from Ni-Mo ore smelter dust followed the model of "shrinking core".The apparent activation energy of leaching selenium was determined to be 44.4 kJ/mol, which wasconsistent with the values of activation energy reported for the surface chemical reaction control. Thekinetics equation of leaching selenium from Ni-Mo ore smelter dust was expressed as1 -(1-η)~(1/3) = 185.4 exp(-44400/RT)t.which coincided with the experimental results.