This invention relates to an composition, comprising A) at least one quaternary ammonium compound which is a collector for the reverse flotation of magnesium minerals from calcium carbonate B) at least one antifoam agent C) a solvent
and its use in the reverse flotation of calcium carbonate.

A method of defoaming a system subject to foaming by using a defoamer composition is disclosed. The defoamer composition contains (a) 80 to 100 wt. % of a decarboxylated rosin acid (DCR) having a density of 0.9 to 1.0 g/cm.sup.3, a flash point of 135 to 175 C., an acid value of <50 mg KOH/g, measured according to ASTM D465, and a viscosity of 15 to 60 cSt at 40 C., measured according to ASTM D-445; and (b) 0 to 20 wt. % based on total weight of the defoamer composition of at least one component selected from the group consisting of nanoparticles, surfactants, hydrophobic compounds, and mixtures thereof. The defoamer composition is very effective in controlling unwanted foam formation or reduce already formed foam in the system.

A foam control agent or formulation including at least one polyol lipid having a polyol ester of fatty acid (PEFA) compound.