Influence of High-Voltage Electromagnetic Pulses on Technological Properties of Diamond Crystals and Kimberlite Rock-Forming Minerals

At a Glance

Metadata	Details
Publication Date	2019-12-30
Journal	Inżynieria Mineralna
Authors	Nataliya Anashkina, I. Zh. Bunin, G. K. Khachatryan
Analysis	Full AI Review Included

Technical Documentation: Diamond Material Enhancement via High-Voltage Nanosecond Pulse Processing

Source Paper Analysis: Influence of High-Voltage Electromagnetic Pulses on Technological Properties of Diamond Crystals and Kimberlite Rock-Forming Minerals (Anashkina et al., 2019)

Executive Summary

This research validates a novel, non-thermal processing technique using High-Power Electromagnetic Pulses (HPEMP) to selectively modify the mechanical and surface properties of diamond and ore matrix minerals, offering significant advantages for diamond recovery and mineral processing.

Selective Softening: HPEMP treatment successfully reduced the microhardness of kimberlite rock-forming minerals (olivine, calcite, serpentine) by 40-66%, facilitating easier ore grinding and processing.
Diamond Preservation & Strengthening: Crucially, the non-thermal HPEMP action simultaneously increased the strength properties of the diamond crystals by generating B2 type crystal lattice microsift defects (platelets), ensuring diamond integrity during subsequent grinding.
Enhanced Floatability: Natural diamond flotation activity increased by 14% (from 47% to 61%) due to the detachment and destruction of hydrophilic mineral micro- and nanophases from the diamond surface.
Non-Thermal Mechanism: The process utilizes nanosecond high-voltage pulses (~50 ns duration, ~25 kV amplitude) to induce structural changes without bulk heating, preventing thermal damage to the diamond.
Surface Purity: XPS and IR spectroscopy confirmed that HPEMP effectively cleanses the diamond surface, removing strongly adhesive clayish mineral coatings and hydrocarbon impurities.
Industrial Application: The results indicate the principal possibility of using pulsed energy impacts to intensify diamond flotation and improve overall recovery efficiency in diamond-bearing kimberlites.

Technical Specifications

The following hard data points define the parameters of the HPEMP treatment and the resulting material changes observed in the study.

Parameter	Value	Unit	Context
HPEMP Pulse Amplitude (U)	~25	kV	Applied voltage
Electric Field Strength (E)	~10⁷	V m^-1	Field component in interelectrode space
Pulse Duration (τ)	~50	ns	Duration of nanosecond pulse
Pulse Front Time (τ)	1-5	ns	Rise time of the pulse
Pulse Repetition Frequency	100	Hz	Standard ambient conditions
Single Pulse Energy	~0.1	J	Energy used for non-thermal action
Rock Microhardness Reduction	40-66	%	Decrease observed in olivine, calcite, and serpentine
Diamond Floatability Increase	14	%	Absolute increase (from 47% to 61%)
Optimal Flotation Treatment Time	≤ 30	s	Time required for maximum hydrophobic floatable diamonds
B2 Defect Signature	1365	cm^-1	Absorption line indicating increased platelet concentration (FTIR)

Key Methodologies

The experimental procedure focused on non-thermal structural and surface modification using high-voltage nanosecond pulses, followed by comprehensive material characterization.

Sample Selection: Used AS-120 synthetic diamonds (-50 + 40 µm) and natural technical diamonds (-2 + 1 mm), alongside milled kimberlite rock-forming minerals.
HPEMP Treatment: Samples were subjected to nanosecond high-voltage video pulses (U ~25 kV, 100 Hz frequency) for treatment durations ranging from 10 to 150 seconds.
Non-Contact Discharge: Synthetic diamonds were treated without ohmic contact, allowing for nanosecond pulse atmospheric pressure dielectric barrier discharges.
Vickers Microhardness Testing: Microhardness (HV) of polished mineral sections was measured using a PMT-3M meter to quantify the softening effect (HV = (0.189 P / d²) 10⁶).
Structural Defect Analysis (FTIR): Fourier Transform Infrared Spectroscopy (Nicolet-380) was used to monitor the systematic increase in the absorption coefficient of the 1365 cm^-1 line, confirming the formation of B2 lamellar defects (platelets) in the diamond lattice.
Surface Chemistry Analysis (XPS): X-ray Photoelectron Spectroscopy (Kratos Axis Ultra DLD) was employed to analyze changes in surface phase composition, particularly the altered chemical state of oxygen atoms (O 1s level) and surface oxidation.
Flotation Testing: Floatability of natural diamonds was measured in distilled water using Hollimond’s tube to quantify the increase in hydrophobicity after HPEMP treatment.

6CCVD Solutions & Capabilities

6CCVD provides the high-quality, defect-engineered MPCVD diamond materials necessary to replicate, optimize, and scale the advanced processing techniques demonstrated in this research. Our capabilities ensure precise control over crystal structure and surface finish, critical for both fundamental research and industrial application in advanced mineral processing.

Applicable Materials for HPEMP Research

To successfully replicate or extend this research, materials with controlled purity and structural integrity are essential for reliable defect engineering (B2 platelet formation) and surface modification studies.

Optical Grade Single Crystal Diamond (SCD):
- Application: Ideal for fundamental studies on defect engineering, such as the controlled introduction of B2 platelets (as observed via FTIR at 1365 cm^-1). High purity ensures that observed changes are solely due to HPEMP interaction, not background impurities.
- Capability Match: 6CCVD offers SCD plates up to 500 µm thick with Ra < 1nm polishing, perfect for high-resolution surface analysis (XPS, LSCM).
High Purity Polycrystalline Diamond (PCD):
- Application: Suitable for scaling up industrial testing, particularly for large-area exposure to HPEMP fields, simulating ore processing volumes.
- Capability Match: 6CCVD supplies PCD plates/wafers up to 125mm in diameter, allowing for large-scale, high-throughput experiments. Polishing to Ra < 5nm is available for inch-size PCD.
Boron-Doped Diamond (BDD):
- Application Extension: While not the primary focus, BDD electrodes could be used as robust, chemically inert electrodes for generating or monitoring the HPEMP discharge in harsh, aqueous environments (e.g., flotation circuits).

Customization Potential & Engineering Services

The success of HPEMP treatment relies on precise material geometry and surface preparation. 6CCVD offers full customization to meet specific research requirements:

Requirement from Research	6CCVD Customization Capability	Benefit to Client
Specific Sample Dimensions	Plates/wafers up to 125mm (PCD) and custom laser cutting.	Provides large-area samples for industrial scale-up or precise geometry for lab testing.
Ultra-Low Surface Roughness	Polishing to Ra < 1nm (SCD) and Ra < 5nm (PCD).	Essential for accurate surface characterization (XPS, LSCM) of mineral film detachment and oxidation effects.
Integrated Electrodes	Custom metalization services (Au, Pt, Pd, Ti, W, Cu).	Allows researchers to integrate electrodes directly onto the diamond surface for in-situ monitoring or controlled spark generation during HPEMP application.
Substrate Thickness	SCD/PCD layers from 0.1 µm up to 500 µm; Substrates up to 10 mm.	Enables optimization of material mass and thermal properties for high-energy pulse interaction studies.

Engineering Support

6CCVD’s in-house PhD team specializes in defect engineering and surface chemistry of MPCVD diamond. We offer expert consultation to researchers and engineers working on similar Advanced Mineral Processing and Structural Defect Engineering projects. We can assist with material selection to optimize B2 defect concentration for maximum crystal strength and durability.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

For optimization of diamond processing technology the influence of nanosecond high voltage pulses on mechanical and technological properties of diamond crystals and kimberlite rock-forming minerals (calcite, olivine, serpentine) was investigated. Using methods of Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), microscopy and mikrohardness mea - surement the changes of structural, physic-chemical surface properties, and microhardness of minerals as the result of impacts, was studied. Non-thermal impacts caused a decrease of kimberlite rock-forming minerals microhardness in general to 40-66% as the result of surface microstructure destruction which is caused by formation of micro cracks, traces of surface breakdown and other defects. At the same time, the pulse energy impact on natural diamonds led to formation of B2 type crystal lattice microsift defects, elevated concentration of which increases the hardness properties of crystals. The obtained result indicates possibility of applying pulsed energy effects to improve the softening efficiency of diamond-bearing kimberlites rock-forming minerals without damaging the diamond crystals and ensuring their preservation by the subsequent grinding of ores. The effect of increasing the natural diamonds flotation activity by 14% (from 47% to 61%) was experimentally established as a result of processing diamond crystals with nanosecond pulses (~ 10-50 sec), which indicates the principal possibility of using pulsed energy impacts to intensify the diamond flotation during pro - cessing diamond-bearing kimberlites.

Tech Support

Original Source

DOI: https://doi.org/10.29227/im-2019-02-23