Patents
A process for preparation of monodispersed iron oxide of high coercivity which comprises : (i) Preparing aqueous solution of iron chloride of concentration in the range of 50 to 150 g/L by dissolving electrolytic iron powder or scrap iron in hydrochloric acid, (ii) Purifying the iron solution prepared from scrap iron by solvent extraction using methyl isobutyl ketone or tri-n-butyl phosphate with organic: aqueous (O/A) ratio in the range 2:1 to 4:1, (iii) Adding Ammonium Hydroxide solution to Iron Chloride for precipitating iron as iron hydroxide while stirring with the help of suitable stirrer and maintaining the pH of the hydroxide slurry in the range 2.5 to 3.5, (iv) Autoclaving the iron hydroxide slurry in the temperature range of 140 to 220 °C for 2 hours to precipitate hematite and cooling thereafter to 70 °C, wherein the concentration of iron in the hydroxide slurry during hydrothermal precipitation is in the range of 10 - 50 g/L (v) Filtering the slurry and washing the precipitate for complete removal of chloride and drying in the temperature range of 50 to 80°C for 48 hours.