Valorization of Kimberlite Tailings by Carbon Capture and Utilization (CCU) Method

At a Glance

Metadata	Details
Publication Date	2020-07-08
Journal	Minerals
Authors	C. N. Chakravarthy, Salma Chalouati, Ye Eun Chai, Hugo Fantucci, Rafael M. Santos
Institutions	University of Guelph
Citations	12
Analysis	Full AI Review Included

Technical Documentation & Analysis: Valorization of Kimberlite Tailings

Executive Summary

This technical analysis reviews the valorization of kimberlite tailings (a byproduct of natural diamond mining) for carbon capture and utilization (CCU) in sustainable construction materials. While this research focuses on bulk, low-cost material substitution, 6CCVD specializes in high-performance, engineered diamond materials for advanced scientific and industrial applications.

Research Focus: Assessment of carbonated kimberlite tailings as a partial cement substitute in concrete bricks to sequester CO₂.
Methodology: Mild thin-film carbonation was performed in a CO₂ incubator (35-50 °C, 10-20 vol% CO₂, 10-20 wt% moisture) over 144 hours.
Key Achievement: Maximum CO₂ uptake gain was approximately 3.7 wt% (dry basis), leading to the formation of hydrated magnesium carbonates (nesquehonite and lansfordite).
Performance: Bricks incorporating carbonated kimberlite showed improved compressive strength compared to those using unreacted kimberlite, meeting standard durability criteria (Initial Water Absorption < 2%).
6CCVD Context: This study utilizes the low-value waste stream of natural diamond extraction. In contrast, 6CCVD engineers high-value, synthetic MPCVD diamond (SCD/PCD) with precisely controlled properties (thermal, optical, electronic) for demanding applications where bulk mineral properties are insufficient.
Value Proposition: 6CCVD provides the highest quality engineered diamond materials, offering superior performance, purity, and customization for researchers and engineers pushing the boundaries of material science.

Technical Specifications

The following hard data points were extracted from the research paper regarding the material composition and process parameters:

Parameter	Value	Unit	Context
Kimberlite Source	Gahcho Kué Diamond Mine	N/A	Fine Processed Kimberlite (FPK)
FPK Grain Size Range	3.9 to 62.5	µm	Material used for carbonation
Carbonation Temperature Range	35 and 50	°C	Chamber temperature tested
CO₂ Concentration Range	10 and 20	vol%	Ambient pressure
Moisture Content Range	10, 15, 20	wt% w.b.	Wet basis
Carbonation Duration	144	h	Total time in CO₂ incubator
Unreacted CO₂ Content (LOI)	4.32	wt% d.b.	Pre-existing carbonates/volatiles
Maximum CO₂ Content (Carbonated)	8.04	wt% d.b.	Achieved at 35 °C, 20% CO₂, 20% MC
Maximum CO₂ Uptake (Gain)	3.7	wt%	Difference from unreacted material
Cement Replacement Ratio	10	%	Kimberlite used as cement substitute
Water-to-Binder Ratio	0.6:1	N/A	Constant mix design ratio
Cementitious:Sand Ratio	1:3	N/A	Constant mix design ratio
Initial Water Absorption (Achieved)	< 2	%	Standard requires < 7% for high durability
Target Compressive Strength (28 days)	15 to 40	MPa	Canadian standard for masonry bricks

Key Methodologies

The experiment involved two primary phases: thin-film carbonation of kimberlite and subsequent casting and testing of concrete bricks.

Kimberlite Preparation:
- Fine processed kimberlite (FPK) was dried in an oven at 50 °C for 24 h.
- Material was ground to a powdery form using a pestle.
Thin-Film Carbonation (144 h):
- 60 g samples were wetted with ultrapure water (18.2 MΩ·cm) to achieve target moisture contents (10, 15, 20 wt%).
- Samples were spread in thin layers in stainless steel trays and placed in a CO₂ incubator (Binder C170).
- Reaction parameters tested: Temperature (35 °C, 50 °C) and CO₂ concentration (10 vol%, 20 vol%).
- Moisture content was monitored every 24 h using a small crucible sample (dried at 60 °C for 2-3 h) and re-wetted to maintain initial moisture levels.
- Samples were lightly deagglomerated daily to maintain surface area reactivity.
Material Characterization:
- Mineralogy: X-ray diffraction (XRD) confirmed the formation of hydrated magnesium carbonates (nesquehonite and lansfordite).
- CO₂ Quantification: Furnace testing measured weight loss at 300 °C (chemically bonded water) and between 300 °C and 950 °C (CO₂ release from Ca- and Mg-carbonates).
Brick Casting and Curing:
- Carbonated kimberlite replaced 10% of the cement binder.
- Bricks (20 cm x 10 cm x 6 cm) were cast using a 1:3 cementitious material-to-sand ratio and 0.6:1 water-to-binder ratio.
- Initial curing was performed in the CO₂ incubator (35 °C, 10% CO₂) for 24 h to promote early strength development.
- Bricks were demolded and subjected to immersion curing for 7 and 28 days.
Mechanical Testing:
- Initial Water Absorption: Measured after 24 h immersion (W2) versus initial weight (W1).
- Compressive Strength: Tested according to ASTM C 67 code using an MTS® compression machine (strain rate 5 mm/min, load rate 4 tonnes/min).

6CCVD Solutions & Capabilities

This research successfully demonstrates the potential for utilizing low-value kimberlite tailings for bulk CCU applications. However, when material performance demands shift from bulk construction to high-precision engineering, the limitations of natural, impure mineral waste become apparent.

6CCVD specializes in synthesizing high-purity, engineered diamond materials via Microwave Plasma Chemical Vapor Deposition (MPCVD), offering unparalleled control over material properties required for advanced scientific and industrial applications.

Applicable Materials for Advanced Diamond Applications

While kimberlite is suitable for cement replacement, 6CCVD provides the following engineered diamond materials for applications requiring extreme performance:

Application Requirement	6CCVD Material Solution	Key Material Properties
Extreme Thermal Management	High Thermal Grade PCD (Polycrystalline Diamond)	Thermal conductivity > 1800 W/mK. Ideal for heat spreaders in high-power electronics or laser systems.
High-Precision Optics/Lasers	Optical Grade SCD (Single Crystal Diamond)	Ultra-low absorption, high damage threshold, available in thicknesses from 0.1 µm to 500 µm.
Electrochemistry/Sensors	Boron-Doped Diamond (BDD)	Highly conductive, chemically inert, wide electrochemical window. Available as thin films or thick plates.
High-Wear Tooling/Dies	Mechanical Grade PCD	Extreme hardness and abrasion resistance, superior to natural kimberlite aggregates.

Customization Potential

The research utilized specific brick dimensions (20 cm x 10 cm x 6 cm) and relied on the natural composition of the kimberlite. 6CCVD offers comprehensive customization capabilities essential for high-specification projects:

Custom Dimensions: We provide plates and wafers up to 125 mm in diameter (PCD) and custom-cut geometries for SCD, far exceeding the dimensional control of bulk materials.
Thickness Control: Precise control over SCD and PCD thickness, ranging from ultra-thin films (0.1 µm) to thick substrates (up to 10 mm).
Surface Finish: Internal polishing capabilities ensure ultra-smooth surfaces, critical for optical and electronic applications: Ra < 1 nm (SCD) and Ra < 5 nm (Inch-size PCD).
Advanced Metalization: If this research were to pivot toward high-performance sensors or electronic components, 6CCVD offers in-house metalization services, including Au, Pt, Pd, Ti, W, and Cu layers, tailored to specific adhesion and conductivity requirements.

Engineering Support

The successful valorization of mining waste, as demonstrated in this paper, requires deep material science expertise. 6CCVD’s in-house PhD team specializes in the synthesis and characterization of carbon materials.

We offer consultation services to assist engineers and scientists in selecting the optimal diamond material (SCD, PCD, BDD) and specifications (thickness, doping, orientation) for projects requiring extreme performance, such as:

High-efficiency thermal interfaces.
Advanced quantum sensing platforms.
High-power microwave windows.

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

View Original Abstract

In the world of construction, cement plays a vital role, but despite its reputation and affordable prices, the cement industry faces multiple challenges due to pollution and sustainability concerns. This study aimed to assess the possibility of utilizing carbonated kimberlite tailings, a waste product from diamond mining, as a partial cement substitute in the preparation of concrete bricks. This is a unique opportunity to help close the gap between fundamental research in mineral carbonation and its industrial implementation to generate commercial products. Kimberlite was subjected to a mild thin-film carbonation process in a CO2 incubator at varying levels of CO2 concentration (10 vol% and 20 vol% at ambient pressure), kimberlite paste moisture content (10 wt% to 20 wt%), and chamber temperature (35 and 50 °C). The formation of magnesium carbonates, in the form of nesquehonite and lansfordite, was verified by X-ray diffraction analysis, and total CO2 uptake was quantified by thermal decomposition in furnace testing. Carbonated kimberlite tailings were then used to cast bricks. Replacement of cement between 10% and 20% were tested, with a constant water-to-binder ratio of 0.6:1, and a cementitious material-to-sand ratio of 1:3. Initial water absorption and 7- and 28-days compressive strength tests were carried out. The results obtained confirm the possibility of using carbonated kimberlite to replace cement partially, and highlight the benefits of carbonating the kimberlite for such application, and recommendations for future research are suggested. This study demonstrates the potential use of mining tailings to prototype the sequestration of CO2 into sustainable building materials to positively impact the increasing demand for cement-based products.

Tech Support

Original Source

DOI: https://doi.org/10.3390/min10070611

References

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2006 - Reuse of textile effluent treatment plant sludge in building materials [Crossref]
2015 - Utilization of water treatment plant sludge in structural ceramics [Crossref]
2017 - Characterisation of fired-clay bricks incorporating biosolids and the effect of heating rate on properties of bricks [Crossref]