Binding heavy metals in waste incinerator ash, by mixing with acidic iron oxide or iron hydroxide

摘要

The ash is mixed with iron hydroxide or iron oxide having an acidified surface. A method for binding heavy metals and/or heavy metal compounds (especially copper, antimony and molybdenum) present in ash from the floor of a waste incinerator comprises slaking the ash by passing it through a water bath and then ageing the wet ash by treating it with a carbon dioxide-rich gas. The optionally aged ash is mixed with a material which comprises iron (hydr)oxide and has an acidified surface. Independent claims are also included for the following: (1) Use of an iron ore concentrate with an acidified surface (e.g. fine iron ore) for binding heavy metals and/or heavy metal compounds present in ash from the floor of a waste incinerator which has been slaked with water in a liquid/solid (L/S) ratio of 0.17-4 (0.8) l/kg in order to produce ash which has a reduced leachable content; and (2) Aggregate, especially suitable for use as a building material, obtained by mixing optionally washed and aged ash from the floor of a waste incinerator with an iron (hydr)oxide-comprising material having an acidified surface.