Abstract: A purified solution containing iron chloride and manganese chloride, having a phosphorus content not higher than about 0.007 wt. % with respect to the total content of iron and manganese. The method for producing the purified solution comprises the steps of dissolving manganese containing raw material in hydrochloric solution; oxidizing the solution; adjusting the pH of the solution to 2.5.about.4.5 to form insolubles; and separating the insolubles from the solution. This solution can be utilized to produce a mixed powder of an iron oxide and a manganese oxide. The mixed powder is useful for producing a high-quality soft ferrite.

Abstract: A method for producing a powdered iron oxide comprises the steps of adjusting the pH of a crude iron chloride solution to 2.5-4.5; reducing the P content of the solution by mechanical stirring or air bubbling and filtering; and oxidizing the solution into a powdered iron oxide having a maximum P content of 0.005 wt. %. The P content of the solution may also be reduced by ultrafilter treatment. The soft ferrite made by using the powdered iron oxide by this process shows excellent magnetic properties.

Abstract: The present invention relates to a method for removing a silicic compound from the waste liquor of steel pickling. A filtering method using a filter fabric or biscuit plate is impractical as an industrial method because the filtering medium becomes clogged.The present invention is characterized by an adsorption method in which silicic compounds are adsorbed on adsorbent substrates in an optional part of an adsorption bed.The present invention is characterized in that the waste liquor is passed through the adsorption bed for a two-month period or longer without clogging occurring.