Sand modification with a saponite clay suspension as a waste of the diamond mining industry
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-12-15 |
| Journal | Construction and Geotechnics |
| Authors | A. L Nevzorov, Yu. V Saenko, A. M Shiranov |
| Institutions | Northern (Arctic) Federal University |
| Citations | 1 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Advanced Materials for Geotechnical Flow Control
Section titled âTechnical Documentation & Analysis: Advanced Materials for Geotechnical Flow ControlâReference: Nevzorov A.L., Saenko Yu.V., Shiranov A.M. Sand modification with a saponite clay suspension as a waste of the diamond mining industry. Construction and Geotechnics. 2022. Vol. 13. No. 4. Pp. 103-115. DOI: 10.15593/2224-9826/2022.4.08
Executive Summary
Section titled âExecutive SummaryâThis research investigates the modification of sand permeability using saponite clay suspensions derived from diamond mining waste, a process known as clogging (or colmatation). While the application is geotechnical, the methodology highlights the critical need for robust, high-precision materials in demanding experimental environments.
- Core Achievement: Successful reduction of sand hydraulic conductivity (k) by up to 39 times (kâ/km ratio) by filtering saponite clay suspension through sand pre-treated with chalk (CaCO3).
- Methodology: Permeability testing conducted in Triaxial Test Chambers (Geocomp LoadTrac II/FlowTrac II) under high confining pressure (100 kPa) and controlled hydraulic gradients (up to I=10).
- Material Challenge: The experiment involves the long-term filtration of highly abrasive, high-concentration (0.58-0.63%) clay suspensions, demanding extreme chemical inertness and wear resistance from the testing apparatus components (e.g., porous disks, flow channels, pressure sensors).
- Critical Flow Rate: Maximum clogging depth was achieved by maintaining a suspension flow rate above 3.5 m/day, requiring precise, stable flow control under variable pressure.
- 6CCVD Value Proposition: 6CCVD provides chemically inert, ultra-hard MPCVD diamond materials (SCD/PCD) ideal for manufacturing durable, high-precision components necessary for replicating or extending this type of abrasive, high-pressure flow research.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points define the demanding experimental environment and results achieved in the permeability tests:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Sample Diameter | 73 | mm | Triaxial Test Sample |
| Sample Height | 145 | mm | Triaxial Test Sample |
| Confining Pressure | 100 | kPa | Maintained in Triaxial Chamber |
| Initial Hydraulic Conductivity (kâ) | 1.3 to 2.05 | m/day | Unmodified sand (Kcom 0.90-1.00) |
| Clay Suspension Concentration | 0.58-0.63 | % | Saponite clay solids |
| Primary Clay Particle Size | < 0.001 | mm | Highly dispersive fraction (91.5-94.2%) |
| Additive Concentration (Chalk/Dolomite) | 3 or 5 | % | By mass of dry sand |
| Maximum Hydraulic Gradient (I) | 10 | Dimensionless | Applied during suspension filtration |
| Critical Flow Rate for Clogging | > 3.5 | m/day | Recommended minimum flow velocity |
| Max Reduction Factor (Chalk 5%) | 39 | times | Ratio of kâ/km |
| Final Hydraulic Conductivity (km) (Chalk 5%) | 0.03 | m/day | Lowest measured permeability |
Key Methodologies
Section titled âKey MethodologiesâThe experimental procedure focused on controlled filtration and permeability measurement using specialized triaxial equipment designed to simulate in-situ stress conditions while handling abrasive suspensions.
- Sample Preparation: Alluvial fine sand samples (73 mm diameter, 145 mm height) were prepared at three compaction coefficients (Kcom: 0.90-0.92, 0.93-0.96, 0.96-1.00). Chalk (CaCO3) or Dolomite (CaCO3¡MgCO3) additives (3% or 5%) were incorporated into the middle third of the sample height.
- Initial Saturation & kâ Measurement: Samples were saturated with distilled water (bottom-up flow, I=0.25, 12 hours). Initial hydraulic conductivity (kâ) was measured at four hydraulic gradients (I=0.25, 0.5, 0.75, 1).
- Suspension Filtration (Clogging): Saponite clay suspension (0.58-0.63% concentration) was filtered through the samples (top-down flow). The hydraulic gradient was gradually increased (starting at I=2, increasing every 10 minutes) up to I=10 to maintain a flow velocity above 3.5 m/day. Filtration continued for 60 minutes at the maximum gradient.
- Cleaning Phase: The perforated upper disk was cleaned by circulating distilled water in the over-platen space for 12 hours to remove settled saponite particles.
- Final km Measurement: The hydraulic conductivity (km) of the modified sand was measured again using distilled water (bottom-up flow) at the four standard hydraulic gradients (I=0.25, 0.5, 0.75, 1).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research, while focused on geotechnical engineering, relies on highly precise, durable instrumentation to manage abrasive flow and high-pressure environments. 6CCVDâs MPCVD diamond materials offer superior performance for critical components in such advanced testing apparatus.
Applicable Materials for High-Performance Geotechnical Testing
Section titled âApplicable Materials for High-Performance Geotechnical TestingâThe long-term reliability and precision of flow measurements in the presence of abrasive clay particles and high confining pressures necessitate materials with extreme hardness, chemical inertness, and dimensional stabilityâproperties inherent to CVD diamond.
| Application Requirement | 6CCVD Material Recommendation | Rationale & Benefit |
|---|---|---|
| Abrasive Flow Control | Mechanical Grade PCD | Extreme wear resistance (Mohs 10) for flow restrictors, valve seats, and pump components handling high-velocity, abrasive clay suspensions (saponite). Ensures long-term calibration stability. |
| Porous Media/Filters | Custom SCD/PCD Plates | Diamond porous disks or supports offer superior stiffness and chemical resistance compared to traditional ceramics or metals, preventing deformation under 100 kPa confinement and resisting chemical attack from the clay/water mixture. |
| High-Pressure Sensing | SCD Substrates | Used as chemically inert, thermally stable substrates for embedding thin-film pressure or temperature sensors within the triaxial cell, ensuring accurate data acquisition in harsh environments. |
| Electrokinetic Studies (Extension) | Heavy Boron-Doped Diamond (BDD) | For future research extending modification methods (e.g., electrokinetic enhancement of clogging), BDD electrodes offer unparalleled electrochemical stability and corrosion resistance in aqueous media. |
Customization Potential for Advanced Instrumentation
Section titled âCustomization Potential for Advanced Instrumentationâ6CCVD specializes in delivering custom diamond solutions tailored to unique engineering demands, ensuring researchers can push the boundaries of their experimental setups.
- Custom Dimensions: The paper utilized 73 mm diameter samples. 6CCVD can supply large-area PCD plates up to 125 mm in diameter, ideal for manufacturing large-scale, high-durability porous filters or pressure plates for triaxial cells and consolidation apparatus.
- Precision Polishing: We offer ultra-smooth polishing (Ra < 1nm for SCD, < 5nm for inch-size PCD), critical for minimizing friction and ensuring uniform stress distribution in high-pressure piston/platen interfaces within the triaxial chamber.
- Integrated Metalization: 6CCVD provides internal metalization services (Au, Pt, Pd, Ti, W, Cu). This capability allows for the integration of custom electrical contacts or sensor traces directly onto diamond components (e.g., flow meters or BDD electrodes) that are exposed to the corrosive suspension.
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team provides expert material consultation to optimize diamond selection and design for complex scientific and engineering challenges. We can assist researchers in designing diamond components that guarantee dimensional stability and chemical inertness for similar High-Pressure Flow and Permeability Testing projects.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
The results of the laboratory water permeability tests of a sand modified by a saponite clay fraction from the diamond mining industry waste are presented. The filtration of clay suspension through a landfill ground bed as a method of the additive enrichment is approved. The experimental apparatus consisted of the triaxial test chambers and semi-automatic devices for water and suspension supplying. The chambers excluded a sidewall leakage in the samples and provided required values of the vertical and horizontal stresses when measuring permeability. The samples of an alluvial fine sand and a sand mixed with 3 and 5 % a chalk and a dolomite were investigated. After preliminary saturation the rate of distilled water flow through the samples were determined at four values of hydraulic gradient. Then the filtration of a suspension containing up to 0.58-0.63 % clay particles was conducted. After that, the pore disks at the top of samples were washed by circulating water flow. At the last step of experiments the velocity of water flow was measured again at four values of hydraulic gradient. The experiments indicated that the modification of the sand by clogging the pores by the saponite clay fraction from a suspension flow is possible if a sand comprises the additives causing the aggregation of clay particles. The hydraulic conductivity of a sand with 3 % chalk decreased by 15-31 times, with 5 % - by 15-39 times at different values of relative compaction. The effect of a dolomite addition was not significant, the hydraulic conductivity decreased by a maximum of 14.3 times. To achieve the maximum depth of clogging, it is recommended to filtrate the suspension through a loose sand at a hydraulic gradient that provides a flow rate more than 3.5 m/day, after that, the sand layer should be compacted.