the first mixture then blast pump is started to charge air into the first mixture for oxidation for about 10 hours with a introduction amount of air controlled at 700 l h and during the oxidation process the ph value of the first mixture is controlled within a range of 6 u2266 ph u2266 8 and when the ph value is lower than 6 the naoh solution is added supplementarily at a feeding speed of 15 ml min until the ph value reaches about 7 8 and the oxidation is deemed to be finished when the molar ratio of fe 2 fe t is less than 1 yielding a second mixture in this example the alkali ratio of the hydroxide solution added in steps 3 and 4 totally and the ferrous salt solution is 1 05 5 the second mixture obtained in step 4 is filtered and washed with water until the content of na in obtained filter cake is less than 0 5 and then is dried at 90 u00b0 c to yield the amorphous iron oxide hydroxide the method for preparing amorphous iron oxide hydroxide in this example comprises following steps 1 250 3 g solid feso 4 u2022 7h 2 o is prepared into an aqueous solution having a concentration of 1 8 mol l and is placed in a beaker 2 90 g solid naoh is weighed out and is prepared into an aqueous solution having a concentration of 4 mol l and is placed in a beaker 3 the hydroxide solution and the ferrous salt solution are mixed in.