| Iron-mud is the solid waste which produced from amino-dye andamino-intermediate production process. It is also a kind of secondary resource withhigh amount of ferric oxide. Nowadays, most recovering methods have defects suchas low use ratio, secondary pollution and so on. So the research ofenvironment-friendly technology for iron-mud disposing and recycling has therealistic, economical and social significance.The iron-mud disposing technology through traditional dry-process to produceferric oxide red with high quality was studied. The optimum conditions are as follow:the sulfuric-acid addition concentration is 50.91%, the calcined temperature is 800℃and the last time is 1 hour.Supercritical oxidation method used water as supercritical medium wereinvestigated to dispose and recycle iron-mud environment-friendly. A supercriticaloxidation set-up, which used austenic steel as body material, integral forging andout-dot heating, were built. The optimal conditions with this set-up were: iron-mud towater ratio is 20g/100g, feeding air pressure is 0.25MPa, and reacted at 30MPa for 3hours. The samples can be changed to bright-colored red dye through firing at 800℃for 1 hour.The samples were characterized by XRD, EPMA TPR and chromatic aberrationexperiment. The results showed that both the dry process and supercritical oxidationmethod could acquire α-Fe2O3;supercritical oxidation could get rid off organicimpurity absolutely in iron-mud, while dry process couldn't;and the color differenceof ferric oxide red are resulted from different crystal size and structure defect: thebigger crystal size and/or the less crystal defect formed, the brighter colored ferricoxide red obtained.
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