The necessity of additional extraction of alkali from nepheline sludge and increase of its activity is shown. The chemistry of interaction of alkaline phases of nepheline sludge with lime milk and carbon dioxide is given. On the basis of experimental studies, the technological mode of extraction of alkali from nepheline sludge is substantiated. The changes made in the apparatus-technological scheme necessary for the process are presented. Experimental-industrial results of application of lime treatment are given.