Patent ID: 8621889

Claim:
A process for manufacturing compounds based on one or more silicates of alkali metals and/or of alkaline-earth metals and/or of rare earths, optionally in the form of mixed silicates that combine at least two of these elements, said process comprising (a) a conversion reaction (2) in which sulfates of said alkali metals and/or of said rare earths and/or of said alkaline-earth metals 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 at least one submerged burner, wherein to carry out combustion reaction (3), the at least one submerged burner is fed with at least one fuel in gaseous form including sulfur-based compound and (b) a conversion reaction (1) for converting halides of said alkali metals and/or of said rare earths and/or of said alkaline-earth metals into the corresponding sulfates which then are involved in reaction (2).