The technique of hydrothermal stripping from mixed aqueous-organic systems is a promising method for synthesizing oxide ceramic powders for high-performance applications. Some factors influencing heterogeneous hydrothermal stripping with water from iron-loaded organic phase of naphthenic acidisooctyl alcoholkerosene, such as initial concentrations of iron and naphthenic acid, concentration of Fe2O3 搒eed, temperature and time, were investigated. Based on the experimental results, the rate equation was established. Nano-ferric oxide powders were obtained by the technique of hydrothermal stripping from the iron-loaded organic phase. The results suggest that the heterogeneous hydrothermal stripping proceeds in 3 steps: adsorption of naphthenic acid dimers and naphthenic complex of iron onto the surface of seed? hydrolysis of adsorbed complex of iron, and condensation of hydrolyzed complex. The process activation energy is 115 kJ/mol and the heterogeneous hydrothermal stripping is controlled by a chemical reaction (the hydrolysis of naphthenic complex of iron).
Some factors effected on heterogeneous hydrothermal stripping from iron-loaded organic phase of naphthenic acid-isooctyl alcohol-kerosene,such as the concentrations of initial iron and naphthenic acid,the weight of"seed"of Fe2O3,temperature and time,were investigated.The process rate equation and the relation between stripping percent and time needed were established.The results showed the proces activation energy was 114 kJ·mol-1 and the heterogeneous hydrothermal stripping was controlled by the hydrolysis of naphthenic compound of iron.
Structural changes for mechanically activated pyrite,sphalerite,galena and molybdenite with or without the exposure to ambient air,were systematically investigated using X-ray diffraction analysis(XRD),particle size analysis,gravimetrical method, X-ray photo-electron spectroscopy(XPS)and scanning electron microscopy(SEM),respectively.Based on the above structural changes for mechanically activated sulfide ores and related reports by other researchers,several qualitative rules of the mechanisms and the effects of mechanical activation for sulfide ores are obtained.For brittle sulfide ores with thermal instability,and incomplete cleavage plane or extremely incomplete cleavage plane,the mechanism of mechanical activation is that a great amount of surface reactive sites are formed during their mechanical activation.The effects of mechanical activation are apparent.For brittle sulfide ores with thermal instability,and complete cleavage plane,the mechanism of mechanical activation is that a great amount of surface reactive sites are formed,and lattice deformation happens during their mechanical activation.The effects of mechanical activation are apparent.For brittle sulfide ores with excellent thermal stability,and complete cleavage plane,the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation.The effects of mechanical activation are apparent. For sulfide ores with high toughness,good thermal stability and very excellent complete cleavage plane,the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation,but the lattice deformation ratio is very small.The effects of mechanical activation are worst.
