V. A. Chanturiya

Use of High-Power Electromagnetic Pulses in Processes of Disintegration and Opening of Rebellious Gold-Containing Raw Material

Possible mechanisms of mineral particle disintegration under the action of high-power electromagnetic pulses on gold-containing sulfides and enrichment products are described theoretically for the first time. The results of experimental investigations are presented, and the theoretical substantiation is given for the effect of synergetic influence of high-power electromagnetic pulses with a wide range of their parameters and pore moisture on the opening of rebellious gold-containing raw material of different type and subsequent gold extraction.

On the field-emission properties of sulfide minerals under high-power nanosecond pulses

The mechanism of absorption of the energy of high-power electromagnetic nanosecond pulses due to the field emission from the surface of natural semiconductors is considered. The limitations and possibilities of implementing this mechanism in sulfide minerals (pyrite and arsenopyrite) are demonstrated.

Changes in the functional chemical composition of the surfaces and microhardness of kimberlite minerals under the action of nanosecond high voltage pulses

Using a set of physicochemical methods (XPS, analytical electron microscopy, the adsorption of acid–base indicators, and measuring microhardness), the effectiveness of nonthermal action produced by nanosecond high voltage pulses for targeted changes in the phase (functional chemical) composition and technological properties of rock-forming minerals of kimberlites and diamonds is shown. According to data obtained via XPS and SEM-EDX analyses, pulse energy actions damage the surface microstructure of dielectric minerals with the subsequent formation of traces of surface breakdowns and microcracks, softening rockforming minerals, and reducing their microhardness by 40–66% overall. The following changes in the functional chemical composition of a geomaterial surface are established through the adsorption of acid–base indicators: mutual transformations of the Brønsted base, Lewis base, and Brønsted acid sites on a calcite surface under the action of an electromagnetic pulse and the hydroxylation and/or formation of carbonyl groups on a diamond surface, doubling the diamond electrokinetic potential in the negative range.

Structural and phase transformations of sulfide mineral surfaces irradiated by nanosecond electromagnetic pulses

The effect of high-voltage nanosecond electromagnetic pulses on the phase composition of chalcopyrite and sphalerite surfaces is investigated by IR-Fourier spectroscopy, XPS, and UVS. Electromagnetic pulse treatment results in the formation and accumulation of copper and/or iron sulphates Mex(SO4)y in superficial chalcopyrite layers, zinc sulphate ZnSO3, and carbonate ZnCO3 on sphalerite surfaces, changing their electrochemical and physicochemical properties; i.e., a rise in electrode potentials creates favorable conditions for anionic collector sorption and promotes sulfide flotation activity.

Theory and Applications of High-Power Nanosecond Pulses to Processing of Mineral Complexes

This paper reviews current research in high pulsed power technologies for processing of precious metals containing refractory ores and natural mineral aggregates. This is a branch of experimental engineering physics that critically depends on national priority research projects for its dynamic development. The aim of the manuscript is to show progress in the study of nanosecond processes involved in the disintegration and breaking-up of mineral complexes with fine disseminated precious metals. The manuscript presents results of theoretical and experimental studies of the mechanisms of the nonthermal action of high-power electromagnetic pulses with nanosecond leading edge, pulse duration, and high electric field strength on natural mineral media. Experimental data are presented to confirm the formation of breakdown channels and selective disintegration of mineral complexes as a result of pulse irradiation. This makes for efficient access of lixiviant solutions to precious metal particles and enhances precious metal recovery into lixivia during leaching. The paper shows the advantages of high-energy pulse treatment that provides a stable gain in valuable components recovery (5–80% gain for gold and 20–50% for silver) and at the same time helps to reduce energy consumption and cost of products in the processing of resistant gold-containing ores and beneficiation products from Russian deposits. X-ray photoelectron spectroscopy was used for determining the relationship between electromagnetic pulses energy and the surface chemical composition for pyrite and arsenopyrite. It has been concluded that impulsive treatment influences oxidation and hydrophobicity of the minerals and, therefore, it allows for the control of the hydrophobic–hydrophilic mineral surface balance.

MECHANISMS OF DISINTEGRATION OF MINERAL MEDIA EXPOSED TO HIGH-POWER ELECTROMAGNETIC PULSES

This report is devoted to the following plausible mechanisms of disintegration of mineral substances exposed to high-power electromagnetic pulses (HPEMP) with high electric field strength: loosening of mineral structure through electrical breakdown; disintegration due to development of mechanical stresses at the boundary between the dielectric and conductive mineral components; electromagnetic energy absorption by thin metallic films or layers thinner than the characteristic skin layer. Disintegration through these mechanisms would proceed efficiently only provided that the size of the mineral sample exposed to HPEMP exceeds a definite minimum value, which is due to low concentration of the irradiating energy.

Energy concentration in electric discharges between particles of semiconducting sulfide minerals under the action of high-power nanosecond pulses

A model for development of electric discharges between particles of sulfide minerals (pyrite) under the action of high-voltage nanosecond pulses is proposed. It is shown that through discharges in a layer of pyrite particles lead to energy concentration in small contact regions between particles; the concentrated energy is sufficiently high for local decomposition (disintegration) of mineral complexes.

Influence Exerted by Storage Conditions on the Change in Properties of Copper-Nickel Technogenic Products

The changes in technological properties of sulfide minerals of copper-nickel ore of technogenic products under conditions of humid climate are considered. It is shown that the concentration selectivity decreases during storage.

Change in technological properties of technogenic sulfide-contained raw material in the storage process

Results of modeling of changes in technological properties of sulfide minerals (pyrrhotite, pentlandite, and chalcopyrite) present in mining-industrial wastes stored in a climate in which evaporation prevails over precipitation are reported. It is proved that flotation activity of chalcopyrite and, in particular, of pentlandite diminishes, pyrrhotite increases, and selectivity and flotation of combined sulfides with respect to other minerals increases insignificantly. The content of water-soluble salts, dominated by nickel sulfates, increases with storage time.

Influence of liquid phase and products of its radiolysis on surface properties of pyrite and arsenopyrite

A feasibility study has been made on improving the contrast of processing properties of pyrite and arsenopyrite, irradiated by accelerated electrons, when these minerals are in the form of neutral, weakly alkaline, and alkaline aqueous suspensions. It has been shown that as a consequence of change in the surface composition, sorption species, and quantity of adsorbed xanthate and its derivatives, the contrast of flotation properties of pyrite and arsenopyrite can be increased by regulating the irradiation dose of the mineral suspension.