Another alternative mode of preparation includes admixing the finely divided refractory-grade
alumina and water, but without any iron, to form a thick mixture which is passed through a roll-type briquetting machine, pelleting mill, or tabletingpress. Prior to passing the alumina ball into the cavities of the mill or press, an iron particle such as a burr is inserted into each cavity and can be held in the cavity by such as a cleat or small magnet. The iron-particle containing pellets aresubsequently treated to produce balls in effect with an internal iron piece or burr.