The invention relates to a method for separating insoluble components from sylvinite, wherein the sylvinite is suspended in a saturated salt brine, a coagulating agent is added to the suspension, and a foaming agent is then added to the composition thus obtained, said foaming agent comprising and ether and/or ester, wherein a) the ethers of formula 1 correspond to R—O—R′ (1), where R is a linear or branched alkyl or alkenyl groups having 2 to 30 carbon atoms and R′ is a linear or branched alkyl or alkenyl groups having 1 to 30 carbon atoms; b) the esters are derived from monovalent or multivalent alcohols having 1 to 30 carbon atoms (alcohol radicals); or c) the ethers and/or esters are cyclic, wherein the ring size is 6 to 30 carbon atoms.