Method of floating calcium carbonate ore and flotation reagent therefor

A method of cleaning calcium carbonate ore containing silicate impurities which comprises subjecting said ore to a froth-flotation process in the presence of a cationic collector, wherein the collector is a combination of a quaternary ammonium compound having the formula ##STR3## wherein one or two of the group R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are selected from a hydrocarbon group having 8-36 carbon atoms and the remaining groups are selected from a hydrocarbon group having 1-7 carbon atoms or a hydroxyalkyl group having 2-7 carbon atoms and A is an anionic counterion and an alkylene oxide adduct having the formula ##STR4## wherein R.sub.5 is a hydrocarbon group having 8-22 carbon atoms, A.sub.1, A.sub.2 and A.sub.3 are alkylene oxide groups having 2-4 carbon atoms, R.sub.6 is an alkylene group having 2-3 carbon atoms, n.sub.1, n.sub.2 and n.sub.3 are 3-20 and the sum of all of n.sub.1, n.sub.2 and n.sub.3 is 10-40, and s is 0-3, wherein the weight ratio of the quaternary ammonium compound to the alkylene oxide adduct is 3:2-11:1 and recovering the calcium carbonate from the remainder, while removing the contaminating silicates with the float.