LUBRICANT

PURPOSE:To provide a lubricant which is inexpensive, excellent in endurance, etc., and suitable for use in preventing the occurrence of guide shoe flaw in the hot rolling of pipes by kneading a mixture of magnetic iron oxide prepared from a waste pickling solution with a refractory component, a binder and water. CONSTITUTION:A lubricant is prepared by mixing inexpensive magnetic iron oxide prepared from a waste pickling solution of steel, etc., with a refractory component, e.g. Al2O3 or MgO, a binder, e.g. water glass, and water. The magnetic iron oxide is prepared by mixing a waste pickling solution of steel, etc., with an alkali(ne earth) metal (hydr)oxide, e.g. MgO, Ca(OH)2 or NaOH, the air and, if necessary, hot steam to cause a reaction thereamong to thereby form Fe3O4, and separating and washing the precipitated Fe3O4 thus formed with water. If necessary, 1 pt.wt. said lubricant is mixed with 3-5 pts.wt. aggregate, e.g. crushed iron ore.