Removal of impurities contained in iron ores

A method of removing one or more impurities from an iron-containing feedstock, the method comprising:

• grinding the iron-containing feedstock in the presence of a grinding aid to provide a pretreated iron-containing feedstock, the grinding aid comprising an alkali metal chloride, a fluoride salt, or a combination thereof;
• contacting the pretreated iron-containing feedstock with an acid solution to form a purified iron-containing feedstock and a used acid solution, the acid solution comprising 1 wt % to 20 wt % of an inorganic acid having a pKa of less than −1, an organic acid, or a combination thereof, based on a total weight of the acid solution;
• and
• solid-liquid separating the purified iron-containing feedstock from the used acid solution,
• wherein an amount of aluminum, silicon, or a combination thereof is less in the purified iron-containing feedstock than in the iron-containing feedstock.

A method of removing one or more impurities from an iron-containing feedstock, the method comprising:

• grinding the iron-containing feedstock in the presence of a grinding aid to form a pretreated iron-containing feedstock, the grinding aid comprising an alkali metal chloride, a fluoride salt, or a combination thereof;
• contacting the pretreated iron-containing feedstock with a caustic solution having a hydroxide concentration of at least 30 wt % at a temperature of at least 90° C. to form a purified iron-containing feedstock and a used caustic solution, the caustic solution and the iron-containing feedstock having a ratio of at least 2.5 mL/g;
• and
• solid-liquid separating the purified iron-containing feedstock from the used caustic solution,
• wherein an amount of aluminum, silicon, or a combination thereof is less in the purified iron-containing feedstock than in the iron-containing feedstock.