The interrelated group of inventions relates to methods and devices for raw material lump separation and can be used for dressing ferrous and non-ferrous metal ores, mining chemical feedstock, secondary raw material and technogenic waste. The essence of the inventive method and device lies in that a useful component containing lump and a barren rock is irradiated by an ultrahigh frequency electromagnetic field (UHF). Said radiation frequency is selected in such a way that the electromagnetic wave penetration depth dependent of lump material properties is greater than the lump maximum linear dimension at the peak attenuation of the electromagnetic wave. UHF electromagnetic radiation energy absorbed by the lump material initiates the heating of the components thereof, wherein the component exhibiting a greater electrical conductivity absorbs the greater amount of UHF energy than the component exhibiting a lower electric conductivity during the same time, whereby the heating temperatures of the useful component and the barren stock measured after irradiation are different. The temperature law depends on the mass ratio of the lump components exhibiting different properties and is recorded by a thermographic system. Said invention makes it possible, under the same conditions, to increase the useful component content from 6-10 % to 18-25 %, the increment of the useful component mass ratio by 4.5 %, to reduce the useful component tailing up to 3 % and the energy consumption by 5 % by decreasing the raw material dilution during the processing thereof.