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US 5,512,257 AGranted
Process for the treatment of flue particulates
AssigneeVon Roll Umwelttechnik AG
InventorRudolf Frey
Life of this patent
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Abstract
Fly ash from incineration plants is treated with an acidic aqueous solution for the purpose of removing heavy metals. The residual solid matter is filtered. The filtration residue is treated with a precipitating agent for heavy metals. The thereby obtained inert residue can be directly dumped.
Claims17
A process for the treatment of fly ash from an incineration plant to obtain a fly ash substantially free of soluble heavy metal components,
- comprising the steps of:
- treating the separated fly ash with an acidic aqueous solution to obtain a liquid of about pH 3 containing at least one dissolvable heavy metal component selected from the group consisting of zinc, cadmium, mercury and lead present in the fly ash and residual solid matter containing unextracted soluble heavy metal components, the acidic aqueous solution being washing liquid from a flue-gas scrubber of the incineration plant containing hydrogen chloride and sodium sulfate;
- separating the liquid from the residual solid matter by filtration to obtain a cake of filtration residue containing unextracted dissolvable heavy metal components;
- washing said cake of filtration residue with an aqueous solution of a precipitating agent for heavy metals, thereby binding said dissolvable heavy metals remaining in the filtration residue within said cake of filtration residue in an insoluble form, and recovering said cake of filtration residue containing the heavy metals present in an insoluble form.
1 more element
Dependencies are inferred from the claim text.