2025 - Sustainable Industrial Processing Summit
SIPS2025 Volume 12. Intl. Symp on Mining, Mineral and Geomechanics
| Editors: | F. Kongoli, L. Guo, L. Liu, G.N. Anastassakis, L. Andric, K. Aravossis, V. Chanturiya, I. Chatjigeorgiou, D. Fuerstenau, V. Panayotov, J. Rubinstein |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2025 |
| Pages: | 240 pages |
| ISBN: | 978-1-998384-60-0 (CD) |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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ATMOSPHERIC PRESSURE DIELECTRIC BARRIER DISCHARGE PLASMA FOR THE PRACTICAL APPLICATIONS IN THE NATURAL MINERALS PROCESSING
Igor Bunin1; Maria Ryazantseva2; Irina Khabarova2;1N.V.MELNIKOV'S INSTITUTE OF COMPREHENSIVE EXPLOITATION OF MINERAL RESOURCES, RUSSIAN ACADEMY OF SCIENCE (ICEMR RAS), Moscow, Russian Federation; 2RESEARCH INSTITUTE OF COMPREHENSIVE EXPLOITATION OF MINERAL RESOURCES RUSSIAN ACADEMY OF SCIENCE, Moscow, Russian Federation;
Type of Paper: Regular
Id Paper: 31
Topic: 5
Abstract:
Plasma treatment of ores, and ore concentrates is used most often to improve the separation performance of ore minerals and non-metallic gangue, as well as for the “plasma grinding” (softening) of ores to reduce the time of subsequent mechanical grinding and energy costs. Non-equilibrium, low-temperature plasma of dielectric barrier discharge (LTP-DBD), characterized by high pressure (hundreds of Torr), high electron temperatures (electron temperatures can reach several electron volts), and low temperature of the process gas (close to the temperature of dielectric barriers) [1] is considered the most precise, efficient, and safe tool for modifying the composition, structure, and properties of the surfaces of various materials, including geomaterials [2–5]. A DBD occurs in a gas under the action of an alternating voltage applied to the conducting electrodes, provided that at least one electrode is covered with a dielectric layer on the side of the discharge gap. The discharge can be carried out in oxygen or air at atmospheric pressure, room temperature, and natural air humidity, i.e., under normal conditions and without the use of a special plasma gas. For practical applications, the problem of obtaining a diffuse discharge in air at atmospheric pressure is relevant, since in this case the effect of the DBD plasma spreads uniformly over the largest possible area [1,3]. During the our experiments, the mineral samples filled the gap between the active metal electrode and the dielectric barrier and were separated from the electrode by a small air gap. The mineral particles were affected by the following DBD factors: a high-strength pulsed electric field, ionic wind, and low-temperature plasma products in the form of chemically active compounds, such as ozone O3, and other agents. When conducting experiments on the effect of DBD on the structural and physicochemical properties of minerals, the following rational parameters of pulses initiating a barrier discharge we established in [3]: duration of the leading edge of the pulse 250–300 ns, pulse duration 8µs, voltage on the electrodes in the barrier discharge cell 20 kV, repetition frequency of the pulses initiating the discharge ~15 kHz, time range of plasma minerals treatment was ttreat=10–150 s. The dimensions of the electrodes of the DBD discharge cell significantly exceeded the length of the interelectrode gap, which was 5mm. According to SEM, defects of a regular triangular shape formed on the surface of galena samples due to the removal of microcrystalline fragments due to ponderomotive forces in the region of a strong electric field. On the surface of chalcopyrite, the formation of irregularly shaped defects was observed, and on the surface of sphalerite, microchannels of electrical breakdown formed, bordered by the sinter formation material of oxide microphases. The change in the morphology of the surface of sulfides caused softening, and a significant decrease in the microhardness of minerals as a whole by 20–30%. Short (ttreat=10 s) treatment of pyrrhotite caused a shift in the electrode potential of the mineral to negative values (φ=−60mV, at pH 9.7–12) [4], which predetermines the effect of reducing the sorption activity of pyrrhotite with respect to xanthate, hence its flotation recovery reduction. In [5] rational conditions were determined for ttreat=30–40s) plasma pretreatment, in which the efficiency of pyrite and arsenopyrite separation in monomineral flotation increased considerably: an increase in pyrite recovery was 27% while the yield of arsenopyrite decreased by 10–12%. Thus, the method of plasma-chemical processing of geomaterials with using of DBD has great prospects for practical applications in the processes of selective separation of semiconductor ore minerals (sulfides, oxides). In rock-forming minerals, the following features of changes in surface properties when exposed to DBD were established [3]. With increasing plasma treatment time of the quartz samples ttreat=10–150s, smoothing of surface irregularities and the formation of microdefects of irregular shape (≤3µm) occurred This caused weakening and a monotonous decrease in the microhardness of the mineral from 1420 up to 1320 kgf/mm2 in the original and modified at ttreat=150 s states, respectively. The maximum relative change (decrease) in microhardness ∆HVmax was ~7%. The contact angle of wetting the quartz surface with water changed nonmonotonically. As a result of short-term exposure (ttreat=10–30s), the contact angle increased from 44° to 53°, which indicates an increase in the hydrophobicity of the mineral’s surface, while with an increase in ttreat, a gradual decrease in the contact angle was observed to initial values. The possibility of modifying the hydrophobicity of quartz by energy impacts can be used in industrial processes for separating the mineral from impurities and selective (reverse) flotation of ferruginous quartzites.