PSI - Issue 13

Igor Bunin et al. / Procedia Structural Integrity 13 (2018) 1971–1976 Author name / Structural Integrity Procedia 00 (2018) 000–000

1972

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1. Introduction The study and purposeful alteration of physicochemical properties of solids to enhance efficiency of material utilization in modern production processes is the critical goal of such industrial branches as catalysis, adsorbent manufacture and mineral processing. Investigations into influence of the high-intensity impulse field parameters on surface and bulk properties of different geomaterials, including nonconducting and semiconductive ore minerals attract interest from both theoretical and applied viewpoints, namely, to get insight into mechanisms for structural phase transformations with defect formation at different structural levels and to modify purposefully structure and sensitivity of minerals, as well as to improve efficiency of refractory ore processing, see, e.g., Bunin et al. (2017). Mechanical comminution processes are most energy intensive processes which account for more than half of the total energy consumed in mineral industries, see, e.g., Aditya et al. (2017). A new application of the high-voltage pulse electrical comminution technology in hybrid procedures using electrical comminution and mechanical grinding to prepare the flotation feed, rather than using excessive pulse energy to fully disintegrate ore to the flotation size, elaborated by Parker et al. (2015). An important problem in processing diamond-bearing kimberlites is developing new, highly-effective methods for increasing the quality of concentrates via kimberlite softening, which could leave diamond crystals intact during ore milling and for improve the contrast between the electrophysical, luminescent, and physicochemical properties of diamonds and rock minerals. In this paper, we present the main results of the experimental studies on the directional modification of the surface chemical (phase) composition as well as the structural, chemical and process properties of Ca-bearing and rock forming minerals of the diamond-bearing kimberlites under non-thermal impact of high-power (high-voltage) nanosecond electromagnetic pulses (HPEMP), see, e.g., Chanturiya et al. (2001) and Chanturiya et al. (2011). The rational parameters for preliminary treatment of natural dielectric minerals by HPEMP in order to increase the technological properties of geomaterials, due to changes in the chemical surface composition, hydrophobicity, microhardness and floatability and of minerals, are determined and experimentally proved.

Nomenclature HPEMP high-power (high-voltage) nanosecond electromagnetic pulses treat t treatment time by high-voltage nanosecond pulses, s HV Vickers microhardness, MPa ∆ HV relative variations in microhardness, % pK α protolytic equilibrium constant ζ electrokinetic potential, V V electrostatic surface potential, V Ө contact angle, deg E bond binding energy

2. Experimental 2.1. Minerals, specimens, and HPEMP treatment conditions

The studies were performed using monomineral fractions of calcium-bearing minerals (calcite, scheelite, and fluorite) from the Tyrnyauz deposit (Russia). We also used the specimens of rock-forming mineral in Yakut diamond bearing kimberlites (deposits of Russian). The experiments were carried out on the mineral specimens ground down to –100 +63 µm and polished sections 1×1×0.45 cm in size. By using simultaneously a Varian VistaCCD, ICP–AES device and inductively coupled plasma, we employed atomic emission spectroscopy to determine the gross contents of elements in each sample of the mineral (see Table 1 and Table 2; the content of minor impurities is not given).