Siberian Federal University (Krasnoyarsk, Russia):

Gilmanshina T. R., Associate Professor, Candidate of Engineering Sciences, gtr1977@mail.ru
Koroleva G. A., Associate Professor, Candidate of Chemical Sciences, gakorol47@mail.ru
Dyakonova V. Ya., Associate Professor, Candidate of Engineering Sciences, Associate Professor, VDyakonova@sfu-kras.ru
Kaplichenko N. M., Senior Lecturer

The combined sulfur contained in natural graphites reduces the heat transfer, increases the consumption of thermal energy, and leads to atmospheric pollution by harmful emissions when used by foundries. The aim of this work is to develop activation methods that would enable effective reduction of the sulfur content in cryptocrystalline graphite. For graphite desulfurization, electroexplosive-pulse activation, oxidation leaching, and vapor-air oxidation were used. For the electroexplosive-pulse activation, a setup was used in which the graphite slurry with the solid/liquid ratio of S : L = 1 : 3 was poured into the discharge chamber and treated at the given power values, producing two explosions. The setup had the following characteristics: the intere-lectrode gap of 8 mm, the maximum energy of the power block storage devices of 10 to 12 kJ, the operating voltage of 40 kV, and the pulse repetition rate of 0.01 to 0.1 Hz. Laboratory oxidation leaching was carried out under the following conditions: the leaching time of 2 hours, the ratio of S : L = 1 : 10, and the use of sodium hypochlorite with the working solution concentration of 10–20 % as the oxidizing agent. For vapor-air oxidation, a flow-through unit was used. In the course of the work, the effectiveness of electroexplosive-pulse activation, oxidation leaching, and vapor-air oxidation for cryptocrystalline graphite desulfurization was established, which reduce the mass fraction of sulfur from 0.30 to 0.25, 0.18 and 0.15 %, respectively.

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