Historical diamond mine waste reveals carbon sequestration resource in kimberlite residue

Jones, Thomas R.; Poitras, Jordan; Paterson, David L.; Southam, Gordon

doi:10.1016/j.chemgeo.2022.121270

Cited by 8 publications

(9 citation statements)

References 37 publications

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“…Fine kimberlite tailings displayed significantly higher plant abundance than the coarse kimberlite tailings, with or without topsoil mixes, and may be attributed to the differences in the availability of important nutrients for plants between the two sites (Jones et al, 2023;Reid & Naeth, 2005). While an absence of organic F I G U R E 4 Abundance of plant species spontaneously colonising treatments of fine and coarse kimberlite tailings.…”

Section: Discussionmentioning

confidence: 99%

Success in restoring native plant communities on kimberlite mining dumps in the Afro‐alpine Drakensberg region of Lesotho

Ntloko,

Mokotjomela,

Mphafi

et al. 2024

Ecology and Evolution

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Rehabilitation strategies for degraded mine dumps have generally seen limited success due to different complications associated with mining biophysical disturbance. In this study, we tested a combination of two methods to expedite revegetation of kimberlite tailings at Letseng Diamond Mine (i.e., in the Afro‐alpine areas of Lesotho). We ran trials on different growth media located on fine and coarse kimberlite tailings (i.e. sites) mixed with different substrate combinations and topsoil and sowing a seed mix comprised of native plant species. Overall, as predicted, fine kimberlite tailings displayed significantly higher plant abundance than coarse kimberlite tailings, and sown seeds performed significantly better than spontaneous colonisation by emerging species. Kimberlite tailings mixed with topsoil (100 mm) showed significantly greater plant abundance, and similarly, when coarse kimberlite tailings were introduced to fine tailings. Physicochemical analyses of growth media components suggested that topsoil provided additional nutrients and that plants could readily access available nutrients in the fine kimberlite tailings. We noted a gradual significant increase in plant abundance over 5 years, enhanced by new plant species emerging from the topsoil seed bank or by natural seed dispersal. Although plant abundance differed significantly, both fine and coarse kimberlite tailings displayed high plant species diversity (H = 3.4 and D = 0.95 and H = 3.5 and D = 0.95, respectively). Out of 36 emerging plant species, 15 species spontaneously colonised both growth media. The significant variation in abundance among plant species between treatments was mostly attributed to dominant forb species, namely Chrysocoma ciliata, Glumicalyx montanus, Oxalis obliquifolia, Senecio inaequidens and Trifolium burchellianum. We have identified suitable growth media for plant community restoration on kimberlite tailings in the Drakensberg alpine area using a seed mix of native plant species in combination with natural seed dispersal from the surrounding pristine environment. We provide evidence for using two complementary approaches to optimise native plant community development during restoration in the Drakensberg alpine area.

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Section: Discussionmentioning

confidence: 99%

Success in restoring native plant communities on kimberlite mining dumps in the Afro‐alpine Drakensberg region of Lesotho

Ntloko,

Mokotjomela,

Mphafi

et al. 2024

Ecology and Evolution

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“…Mineral carbonation occurring naturally in other diamond mine residue facilities, such as those present at the Cullinan diamond mine, does not show evidence of carbonate passivation. These 50-year-old residue deposits show continued carbonation via ongoing mineral breakdown, even with the system wide development of secondary carbonate mineralogy covering nearly all the discrete grains [ 7 ].…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the mineral substrate in which any proposed carbonation acceleration is to take place must be susceptible to weathering. Kimberlites are one such substrate, with well-known low-temperature alteration reactions—transforming unaltered kimberlite (blue ground) into a weathered/friable kimberlite (yellow ground), and the resulting carbon sequestration via the formation of secondary carbonate minerals [ 2 , 7 , 14 , 25 , 29 ]. This natural phenomenon, occurring in kimberlites exposed to Earth’s surface weathering conditions, could be accelerated as a by-product of extraction and crushing [ 19 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

“…This study is part of Project Carbon Vault™, an initiative set-up by the De Beers Group aimed at offsetting CO 2 emissions associated with diamond mining. The ultramafic residue produced by extracting diamonds from kimberlite has the potential to sequester large amounts of CO 2 through mineral carbonation [ 7 , 12 ]. The aim of this study is to examine the impact of microbial activity on the degree of mineral carbonation in kimberlite, where changes in the biogeochemical weathering conditions increases the amount of carbonate precipitated over time.…”

Section: Introductionmentioning

confidence: 99%

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Accelerated mineral bio-carbonation of coarse residue kimberlite material by inoculation with photosynthetic microbial mats

et al. 2023

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Microbiological weathering of coarse residue deposit (CRD) kimberlite produced by the Venetia Diamond Mine, Limpopo, South Africa enhanced mineral carbonation relative to untreated material. Cultures of photosynthetically enriched biofilm produced maximal carbonation conditions when mixed with kimberlite and incubated under near surface conditions. Interestingly, mineral carbonation also occurred in the dark, under water-saturated conditions. The examination of mineralized biofilms in ca. 150 µm-thick-sections using light microscopy, X-ray fluorescence microscopy (XFM) and backscatter electron—scanning electron microscopy-energy dispersive x-ray spectrometry demonstrated that microbiological weathering aided in producing secondary calcium/magnesium carbonates on silicate grain boundaries. Calcium/magnesium sulphate(s) precipitated under vadose conditions demonstrating that evaporites formed upon drying. In this system, mineral carbonation was only observed in regions possessing bacteria, preserved within carbonate as cemented microcolonies. 16S rDNA molecular diversity of bacteria in kimberlite and in natural biofilms growing on kimberlite were dominated by Proteobacteria that are active in nitrogen, phosphorus and sulphur cycling. Cyanobacteria based enrichment cultures provided with nitrogen & phosphorus (nutrients) to enhance growth, possessed increased diversity of bacteria, with Proteobacteria re-establishing themselves as the dominant bacterial lineage when incubated under dark, vadose conditions consistent with natural kimberlite. Overall, 16S rDNA analyses revealed that weathered kimberlite hosts a diverse microbiome consistent with soils, metal cycling and hydrocarbon degradation. Enhanced weathering and carbonate-cemented microcolonies demonstrate that microorganisms are key to mineral carbonation of kimberlite.

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“…EWM of mine wastes has steadily gained the attention of the mining industry. For instance, De Beers’ CarbonVault project aims to use kimberlite mine wastes from their diamond operations for CO 2 mineralization to reduce net GHG emissions. − For example, Stubbs et al demonstrated that mine wastes from the Venetia Diamond Mine (South Africa) remove CO 2 from the atmosphere and recommended management practices to accelerate CDR.…”

Section: Passive Ewm At Minesmentioning

confidence: 99%

The Mining Industry’s Role in Enhanced Weathering and Mineralization for CO₂ Removal

Power,

Paulo,

Rausis

2023

Environ. Sci. Technol.

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Enhanced weathering and mineralization (EWM) aim to remove carbon dioxide (CO 2 ) from the atmosphere by accelerating the reaction of this greenhouse gas with alkaline minerals. This suite of geochemical negative emissions technologies has the potential to achieve CO 2 removal rates of >1 gigatonne per year, yet will require gigatonnes of suitable rock. As a supplier of rock powder, the mining industry will be at the epicenter of the global implementation of EWM. Certain alkaline mine wastes sequester CO 2 under conventional mining conditions, which should be quantified across the industry. Furthermore, mines are ideal locations for testing acceleration strategies since tailings impoundments are contained and highly monitored. While some environmentally benign mine wastes may be repurposed for off-site use� reducing costs and risks associated with their storage�numerous new mines will be needed to supply rock powders to reach the gigatonne scale. Large-scale EWM pilots with mining companies are required to progress technology readiness, including carbon verification approaches. With its knowledge of geological formations and ore processing, the mining industry can play an essential role in extracting the most reactive rocks with the greatest CO 2 removal capacities, creating supply chains, and participating in lifecycle assessments. The motivations for mining companies to develop EWM include reputational benefits and carbon offsets needed to achieve carbon neutrality.

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Historical diamond mine waste reveals carbon sequestration resource in kimberlite residue

Cited by 8 publications

References 37 publications

Success in restoring native plant communities on kimberlite mining dumps in the Afro‐alpine Drakensberg region of Lesotho

Success in restoring native plant communities on kimberlite mining dumps in the Afro‐alpine Drakensberg region of Lesotho

Accelerated mineral bio-carbonation of coarse residue kimberlite material by inoculation with photosynthetic microbial mats

The Mining Industry’s Role in Enhanced Weathering and Mineralization for CO₂ Removal

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Historical diamond mine waste reveals carbon sequestration resource in kimberlite residue

Cited by 8 publications

References 37 publications

Success in restoring native plant communities on kimberlite mining dumps in the Afro‐alpine Drakensberg region of Lesotho

Success in restoring native plant communities on kimberlite mining dumps in the Afro‐alpine Drakensberg region of Lesotho

Accelerated mineral bio-carbonation of coarse residue kimberlite material by inoculation with photosynthetic microbial mats

The Mining Industry’s Role in Enhanced Weathering and Mineralization for CO2 Removal

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The Mining Industry’s Role in Enhanced Weathering and Mineralization for CO₂ Removal