Removal of elements from coal fly ash

摘要

A method for removing elements, including heavy metals, from fly ash and from fly ash resulting from removal of SOx/NOx from flue gas using Na2CO3/NaHCO3/trona, is described. An aqueous suspension of the fly ash and/or a solution of the leachate from the fly ash is treated with dissolved ferrous compounds, such as FeSO4.7H2O and/or FeCl2.4H2O, at a chosen initial acidic pH, and the precipitation of the ferrous ions as the solution basifies sequesters the trace elements.

主权项

1. A method for removing at least one element from fly ash, comprising:
treating said fly ash with an acidified liquid; allowing the acidified liquid to become basic by reaction with said fly ash, forming a basified liquid; dissolving at least one ferrous compound in the basified liquid, forming a precipitate of the ferrous compound, whereby said at least one element is sequestered by the precipitate; and separating the precipitate from the basified liquid.