Apr 22, 2019 Ore dressing of iron is done by (A) froth floatation process (B) magnetic separation (C) hand picking (D) all of the above. Solution (C) Illustration 3. The flux used in extraction of iron is (A) limestone (B) silica (C) flint (D) feldspar. Solution (A) Illustration 4. Impurities physically associated with minerals are (A) slag (B) flux (C.