Résumé dans la langue de publication, traduction non disponible Waste disposal material and method for stabilizing wastes containing toxic heavy metals such as lead, cadmium, mercury, chromium and nickel in order to prevent these metals from exuding from the wastes, especially alkaline fly ash discharged from waste incinerators, not only in the course of disposal from waste incinerators, not only in the course of disposal thereof but also after being left to stand for long. The disposal material comprises polyvalent-metal salts of phosphoric acid and contains, as required, cement, porous silicon dioxide, aluminum silicate and iron powder. The disposal method comprises mixing the disposal material with the waster, optionally adding waste to the mixture followed by kneading, and aging and solidifying the mixture, thus stabilizing efficiently the toxic heavy metals contained in industrial wastes or in dusts such as Eash or bag ash discharged from municipal waste incinerators, especially Eor bag ash containing slaked or quick lime flown thereinto, to thereby reduce the amount of the exudates. The disposal material can be applied also to the disposal of slag discharged from mines, stabilization of heavy metals contained in the soil contaminated therewith, and disposal of the sludge containing heavy metals resulting from waste water treatment.