Enrichment process by flotation of phosphate-containing ores with carbonated and/or siliceous gangues, by amphoteric collecting agents

The present invention relates to an enrichment process, by flotation, of sedimentary ores containing phosphate, and comprising a gangue of the carbonated type and in some cases a gangue of the siliceous type, wherein an amphoteric product of formula is at least used as collecting agent, in which formula: R is of form R1 or R1O-, R1 being a saturated or unsaturated alkyl radical, either linear or branched, and comprising between 5 and 19 carbon atoms. R' and R'' are H or -Aq-Z, bearing in mind that for R'', when n is greater than 1, there can be in the molecule simultaneously radicals H and radicals -Aq-Z. Ap and Aq are polymethylene chains containing between 1 and 4 carbon atoms, n is a number equal to O or an integer between 1 and 5, Z is a radical selected from the carboxylic, the sulphonic and the phosphonic radicals, and in obtaining the flotation of the carbonated gangue by a reverse flotation in "basic medium .