Modification of the surface and technological properties of geomaterials under the exposure of a dielectric barrier discharge

We studied the mechanisms of changes in the structural state of the surface, mechanical (microhardness), physicochemical and technological properties of sulfide minerals and quartz when exposed to a pulse-periodic dielectric barrier discharge in air at atmospheric pressure. Scanning electron microscopy, microhardness testing, wetting angle determination and other methods have been used. Various modes of the development of a barrier discharge with a change in the applied voltage and pulse repetition rate are considered, and the operating parameters of the pulses initiating the discharge, at which the most significant changes in the structure-sensitive properties of minerals were observed, are established. In the process of plasma processing of minerals, the gas temperature in the working zone of the discharge cell of the barrier discharge did not exceed the temperature of the dielectric barrier and remained on the order of room temperature for 10-60 s. Samples of minerals were exposed to a pulsed barrier discharge in two different ways, namely: (i) macro-samples of minerals were placed in the discharge, so that the working surfaces of the samples were located on the surface of the dielectric barrier. (ii) The mineral particles of the crushed samples were separated from the dielectric barrier by a small air gap, therefore, the mineral particles could move over the barrier during the discharge process. As a result of the action of low-temperature plasma products, electric field and other factors, softening of minerals, changes in morphology, roughness, contact angle of wetting of the surface of mineral samples and flotation activity of sulfide minerals from the time of plasma treatment occurred. The results of this work indicate the fundamental possibility and efficiency of using a dielectric barrier discharge in air at atmospheric pressure to soften the finely disseminated mineral complexes and to improve the technological (flotation) properties of sulfide minerals. (authors)