Abstract: Formed briquettes of high green strength, high shatter and good compressive strength in the cured state from a composition comprising a metal- and/or carbon-containing waste, one or more reactible isocyanate group containing materials and one or more hydroxyl group containing materials and magnesia. The product can be easily formed by mixing all components at room temperature, introducing the same into a mold, applying pressure and thereafter permitting the same to set. Setting is rapid, and the product can be handled within minutes after molding. The product finds particular use as a replacement in whole or in part for metal and/or carbon sources in steel-making; it has the excellent advantages that the metal and/or carbon content thereof is extremely high and it introduces no harmful impurities into, e.g., steel during steel making.