The invention relates to a process for manufacturing compounds based on one or more silicates of alkali metals and/or of alkaline-earth metals, optionally in the form of mixed silicates that combine at least two of these elements, said process involving: (i) preferably a conversion reaction (1) in which halides of said alkali metals and/or of said rare earths and/or of said alkaline-earth metals are converted into the corresponding sulfates; (iii) a conversion reaction (2) in which said sulfates together with silica are converted into the corresponding silicates, the heat supply needed for this conversion being provided, at least in part, by a combustion reaction (3) using a submerged burner or a plurality of submerged burners.