Fabrication of nano-sized powders from waste solution by spray pyrolysis process

Abstract

In order to efficiently recycle the Fe-Ni waste acid solution resulting from shadow mask processing, a spray pyrolysis process was used to fabricate the nano-sized Ni-ferrite powder with the average particle size below 100 nm. The properties of the nano-powder were investigated as function of reaction temperature, concentration and injection speed of raw material solution. As the reaction temperature increases from 800 to 1100°C, the average particle size of the powder increased accordingly, the microstructure of it gradually became solid which is close to the theoretical density, and the surface area of it decreased significantly. Along with the temperature rise, the formation rate of NiFe2O4 phase also increased. As the concentrations of iron and nickel elements in waste solution increased, the average particle size became larger, the particle size distribution became more irregular, the surface area of the powder decreased. Along with the increase of the concentration, the formation rate of NiFe2O4 phase increased significantly. As the air pressure increases up to 1 kg/cm2, the average particle size of the powder decreased slightly, yet the ratio of the Ni-ferrite phase kept almost unchanged. As the air pressure increases up to 3 kg/cm2, the average particle size and the ratio of the Ni-ferrite phase decreased significantly, yet the particle distribution size appears much more uniform. © 2005 The Japan Institute of Metals.