Process for the selective froth-flotation of phosphate and carbonate minerals from finely-divided phosphate-carbonate-silicate ores or concentrates

A process for the separate recovery of phosphate and carbonate minerals from finely-divided phosphate-carbonate-silicate ores or concentrates with a carbonate to phosphate ratio of over 1 is disclosed, in which an anionic collector agent is added to an aqueous slurry of these ores and concentrates, the slurry is then exposed to froth-flotation in order to separate a silicate-bearing residue from phosphate-carbonate concentrate, thereafter (a) the combined phosphate-carbonate concentrate is either treated with a base in order to remove the collector-agent coatings from the surfaces of the mineral particles, whereafter the combined concentrate is froth-flotated with a cationic collector agent using a depressing agent for carbonate in order to recover the phosphate concentrate and the carbonate concentrate separately, or (b) the aqueous slurry to which the anionic collector agent has been added and which has been froth-flotated is treated with sulfur dioxide or carbon dioxide in order to inactivate the collector-agent coatings on the surfaces of the carbonate minerals, whereafter the slurry is froth-flotated in order to obtain separately recovery of a phosphate concentrate and a carbonate concentrate.