The possibility of using cascading air classifiers to produce narrow fractions of quartz sands used as components of dry building mixtures has been investigated. Experimental efficiency and boundary between the separation of quartz sands and airflow velocity for two types of cascading classifiers have been obtained. Mathematical models of dry separation of sands in largeness for these devices have been developed. A computer experiment was conducted, which showed the possibility of obtaining a fraction of sand: 0-3 mm; 0-0,63 mm; 0,63-3 mm; 0,63-1,25 mm; 1,25-3,0 mm; 0.315-0.63 and 0-0.315 mm. At the same time, the entire list of fractions was obtained only on a more efficient poly-cascade device. It has been established that it is possible to simultaneously obtain all the submitted fractions of quartz sand at the installation, consisting of consecutively arranged classifiers with minimal losses of up to 7 % in tails, represented by dust particles with a size of less than 0,16 mm. An example of technological and design parameters of an industrial plant with a capacity of about 4 t/h with an energy consumption of no more than 1.5 kWh/t is given. The height of the classifier for a given capacity with a diameter of 0.5 m will be about 3 m.