Draft:Tailings stratification and mineralogy
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Comment: Please explain "This contribution shall become part of the Lemma Tailings"If this is already n an article (Lemma Tailings is not one, yet at least), please merge it into that article without the need for a review.There is little point in a review until you clarify your meaning,ngh 🇺🇦 FiddleTimtrent FaddleTalk to me 🇺🇦 13:58, 11 November 2024 (UTC)
This contribution shall become part of the Lemma Tailings
Tailings stratification and mineralogy
[edit]The extraction of economic minerals results in an accumulation of tailings on the surface, mostly in tailings ponds, that occupy a large amount of land.[1] Stratification is inherent to sedimentation, as the heavier particles settle before the lighter particles. Yet, tailings can also represent an untapped resource, as many tailings contain valuable secondary minerals. These could be recovered, contributing to the circular economy and reducing the need for new mining operations. Analysing the mineralogy of tailings can reveal the presence of economically valuable minerals, such as rare earth elements or aother metal resources. This is particularly important, as global demand for these resources continues to grow. A thorough understanding of tailings stratigraphy helps to identify the most promising areas for recovery and informs processing methods that allow mineral recovery to be maximized while minimizing environmental issues.
Tailings stratification
[edit]
Tailings stratification is the layering of tailings due to the distribution in particle size as well as the difference in specific density. The compactness of the sandy to silty tailings[2] influences the permeability, which will influence the drainage ability of the tailings and thus the infiltration line.[3] The infiltration line is the pathway through which water can enter in a specific area,[3] and it affects the safety and stability of tailings ponds.
Furthermore, the tailings' compactness affects how much water they can hold. This also affects how strong and stiff they get to be. The more compact the tailings are, the smaller the permeability coefficient and the stronger the water-holding capacity. Rather than consisting of a single uniform body, tailings are usually composed of multiple layers of sediment that differ in grain size and mineralogical composition[4] The grain size of tailings can show great fluctuations due to the deposition of larger and finer particles, which influences the tailings stratification and shear strength. When more finer than larger particles settle, it weakens the tailings, which may result in the settled layer holding more water. This could create the saturation line, affecting how safely the tailings storage facility (TSF) can be operated.
Mineralogical composition in tailings causes the cementation of layers. Sulfide enriched layers can form protective cemented layers. These layers will usually not form in systems with a homogeneous distribution of Iron (Fe) bearing sulfide. Therefore, tailings stratification is greatly influenced by the presence of minerals which have a great influence in the cementation of the tailings' layers, by the grain size distribution which influences the compactness and density of the tailings. However, there are other factors that influence tailings' stratification, such as topography, geological setting, climate, tailings deposition process and lastly how long the tailings have been stored in the TSF.
Tailings mineralogy
[edit]Carbon Mineralization
[edit]Carbon mineralization is a natural process that occurs over hundreds or thousands of years, where certain minerals, such as in mine tailings, react with atmospheric carbon dioxide to form solid carbonates. This process effectively sequesters and removes carbon dioxide from the atmosphere. Ultramafic mine tailings, rich in magnesium-bearing minerals such as serpentine, olivine and brucite, are highly reactive due to their reduced grain size from crushing and have been historically and currently produced in substantial quantities facilitating carbon mineralization.[5] Using these tailings for carbon mineralization can reduce the costs associated with the extraction and processing of ultramafic rocks, which is often energy intensive. The mineralogy of these tailings can vary substantially depending on the type of commodity being mined.[6]
As an example, the Baptiste nickel project in British Columbia, Canada, is known for its potential to mineralize carbon in its tailings. Similarly, the Gahcho Kué diamond mine in the Northwest Territories, Canada, has kimberlite pipes with the potential for carbon mineralization. Tailings from this mine contain a mix of minerals that can facilitate carbon mineralization, contributing to the overall reduction of atmospheric carbon dioxide concnetrations. Ultramafic mine tailings are a promising avenue for carbon mineralization, providing both an effective means of Carbon dioxide storage and a way to utilize waste materials from mining operations.
Secondary Mineralisation
[edit]Secondary mineralization in tailings involves the formation of new minerals from the alteration or weathering of primary minerals found in mine waste. These secondary minerals develop within tailings impoundments due to weathering processes following mining and milling activities. A key factor in this mineralization is the oxidation of sufide minerals, which alters dissolved species concentrations, porewater pH and the overall mineralogy. Within the oxidation zone, primary minerals such as sulfides and carbonates are depleted, leading to the formation of secondary minerals. These secondary minerals are critical, as they help to regulate the concentrations of dissolved species in the pore water.[7]
This study focused on tungsten secondary minerals in tailings generated during a two-year mining operation at the Mount Pleasant Tungsten Mine, approximately 60 km south of Fredericton, New Brunswick. Initially, the tailings were submerged but were exposed to atmospheric oxygen following a dam failure in 1997. The primary mineralogy of the deposit consists mainly of quartz, topaz, fluorite, micas, clays, chlorite, K-feldspars and opaque minerals including wolframite. While the tailings are not extensively oxidized, certain areas have elevated sulfate and metal concentrations including lower pH values.
Biomineralization
[edit]Biomineralization in tailings refers to the process by which living organisms, particularly microbes, contribute to the formation of minerals through their metabolic activities. Acidophilic chemolithotrophic bacteria like Thiobacillus are vital to mineralization processes and play a critical role in biomineralization processes in mine tailings. Examples are those found at the abandoned Kam Kotia mine near Timmins, Ontario, Canada, which has been inactive for about 30 years. These bacteria catalyze the production of toxic, acidic metal leachates that can severely affect natural ecosystems.[8]
Under oxidizing conditions, acidophilic chemolithotrophs oxidize ferrous (Fe (II)) sulfides to produce sulfuric acid and ferric (Fe (III)) iron. These bacteria increase the rate of iron (Fe (II)) oxidation at low pH. Certain species, such as Acidithiobacillus ferrooxidans, can also reduce iron (Fe (III)) in both aerobic and anaerobic environments at very low pH. In addition, sulfate-reducing bacteria (SRB) can indirectly influence the iron cycle in mine tailings by reacting with soluble iron (Fe (II)) to form iron sulfide precipitates. Although sulfate-reducing bacteria (SRB) typically prefer neutral, reducing conditions, they have been found in acid mine drainage environments, indicating potential acid tolerance. Although oxygen generally inhibits their activity, recent studies suggest that sulfate-reducing bacteria (SRB) can remain viable in oxygenated conditions and even engage in aerobic sulfate reduction in well-oxygenated microbial mats.
References
[edit]- ^ Chen, S.; Jin, A.; Zhao, Y.; Wang, J. (2023). "Formation mechanism and deformation characteristics of stratified cemented tailings backfill under noncontinuous filling system". Construction and Building Materials. 389: 131623. doi:10.1016/j.conbuildmat.2023.131623. ISSN 0950-0618.
- ^ Graupner, T.; Kassahun, A.; Rammlmair, D.; Meima, J.a.; Kock, D.; Furche, Markus; F., Adrian; S., Axel; Melcher, F. (2007). "Formation of sequences of cemented layers and hardpans within sulfide-bearing mine tailings (mine district Freiberg, Germany)". Applied Geochemistry. 22 (11): 2486–2508. Bibcode:2007ApGC...22.2486G. doi:10.1016/j.apgeochem.2007.07.002. ISSN 0883-2927.
- ^ a b Geng, W.; Song, Z.; He, C.; Wang, H.; Dong, X. (2024). "The Impact of Fine-Layering of Tailings Dam on the Variation Pattern of Infiltration Lines". Applied Sciences. 14 (2): 950. doi:10.3390/app14020950. ISSN 2076-3417.
- ^ Meima, J. A.; Graupner, T.; Rammlmair, D. (2012). "Modeling the effect of stratification on cemented layer formation in sulfide-bearing mine tailings". Applied Geochemistry. 27 (1): 124–137. Bibcode:2012ApGC...27..124M. doi:10.1016/j.apgeochem.2011.09.024. ISSN 0883-2927.
- ^ Gras, A.; Beaudoin, G.; Molson, J.; Plante, B. (20 July 2020). "Atmospheric carbon sequestration in ultramafic mining residues and impacts on leachate water chemistry at the Dumont Nickel Project, Quebec, Canada". Chemical Geology. 546: 119661. Bibcode:2020ChGeo.54619661G. doi:10.1016/j.chemgeo.2020.119661. ISSN 0009-2541.
- ^ Wynands, E. (2021). Carbon mineralization in ultramafic mine tailings via CO₂ injection. Science, Faculty of; Earth, Ocean and Atmospheric Sciences, Department of (Thesis). University of British Columbia. doi:10.14288/1.0402341. hdl:2429/79796.
- ^ Petrunic, Barbara M.; Al, Tom A.; Weaver, Louise; Hall, Douglas (2009). "Identification and characterization of secondary minerals formed in tungsten mine tailings using transmission electron microscopy". Applied Geochemistry. 24 (12): 2222–2233. Bibcode:2009ApGC...24.2222P. doi:10.1016/j.apgeochem.2009.09.014. ISSN 0883-2927.
- ^ Fortin, D.; Davis, B.; Beveridge, T.J. (1996). "Role of Thiobacillus and sulfate-reducing bacteria in iron biocycling in oxic and acidic mine tailings". FEMS Microbiology Ecology. 21 (1): 11–24. doi:10.1111/j.1574-6941.1996.tb00329.x.