@Jimmy Shelter's responder declarado (em relação a Orodruin, pós-fabricação de um anel):
Potential evidence of a future use of it was for making the battering ram Grond in the War of the Ring.
Wikia LOTR contém não citado em vez de apontar para Barad-dûr:
Grond was forged in Mordor by Smithies of Barad-dûr during the final years of the Third Age, specifically for use by the army besieging the city of Minas Tirith in Gondor. It shared its name, in homage, with the "Hammer of the Underworld," a great mace wielded by Morgoth, Sauron's former master.
Existe suporte canônico para qualquer uma dessas teorias, especialmente a Orodruin?
Na LOTR propriamente dita, não encontrei menção de localização além dos "ferreiros sombrios de Mordor":
Great engines crawled across the field; and in the midst was a huge ram, great as a forest-tree a hundred feet in length, swinging on mighty chains. Long had it been forging in the dark smithies of Mordor, and its hideous head, founded of black steel, was shaped in the likeness of a ravening wolf; on it spells of ruin lay. Grond they named it, in memory of the Hammer of the Underworld of old. Great beasts drew it, Orcs surrounded it, and behind walked mountain-trolls to wield it. (The Return of the King)