By researching the nonmetallic minerals in molybdenum tailings, this paper investigated the possible application of sodium dodecyl glycinate (SD) to deslimed tailings as an alternative to the large dosage and complex flotation reagent systems of conventional combination collectors (dodecylamine and sodium oleate). The floatability differences of nonmetallic minerals under different SD dosages were analyzed via pure mineral flotation experiments, and the adsorption behavior of SD onto different mineral surfaces was analyzed by quantum chemical calculations. The results of the calculated adsorption structures and energies of the different mineral surfaces show that SD was chemically adsorbed onto the albite (001), phlogopite (010), diopside (110), dolomite (101), calcite (104) and calcite (101) surfaces and that physical adsorption occurred at the phlogopite (001) surface. The corresponding adsorption trend was dolomite > calcite > diopside > albite > phlogopite. These results theoretically verify the feasibility of applying SD to the flotation of nonmetallic minerals in tailings and provide a basis for the selection of inhibitors needed for separating phlogopite from other minerals. In the flotation of deslimed molybdenum tailings, the recoveries of the nonmetallic minerals achieved with SD were close to those in pure mineral flotation, which was greater than the recoveries achieved with dodecylamine and sodium oleate (NaOl), and the dosage was reduced by approximately 25%.