PROCESS FOR PRODUCING MAGNESIUM OXIDE FROM ALKALINE FLY ASH OR SLAG

摘要

The invention provides a process for producing magnesium oxide from fly ash or slag comprising magnesium and iron, the process comprising: leaching the fly ash or slag with an aqueous mineral acid solution to produce a leaching solution and a residue, the leaching solution comprising a magnesium salt and an iron sa precipitating the iron salt by increasing the pH of the leaching solution to above 3.5, and separating the leaching solution from the precipitated iron sa and forming magnesium oxide by decomposing the magnesium salt present in the leaching solution.