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The need to explore more complex and low-grade silver ores and to develop novel and cost-effective processes to recover silver from waste is becoming an important challenge. This paper aims to characterize old, low-grade, silver tailings generated by the former Zgounder silver mine, located in Morocco. Understanding the mineralogical composition, p...
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In this work, we study the froth flotation process of chalcopyrite, with emphasis on the influence of the presence of sludges and clays into the pulp during flotation. For this purpose, the chalcopyrite was mechanically prepared (crushing and grinding), the material was classified (between mesh 100 and 120 and the particle sizes were measured). In...
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... Flotation is the most suitable beneficiation process for the recovery of silver-bearing galena, and the available reports concentrate on lowalkaline circuits (Drif et al., 2018;Qing et al., 2008;Wang et al., 2013). In addition, there are some reports using high-alkaline circuits (Song et al., 2021;Xie and Luo, 2002). ...
... Wang et al. (Wang et al., 2013) used ammonium dibutyl dithiophosphate as collector and obtained a good flotation index of 87.25 % silver recovery and 88.45 % lead recovery. They are also usually used in mixture with other concentrating reagents such as xanthate (Drif et al., 2018;Lan et al., 2016b) and diethyldithiocarbamate (Luo et al., 2011;Qing et al., 2008). Due to the difference in optimal pulp environment between dithiophosphate (around pH 8.5) and diethyldithiocarbamate (around pH 11) (Song et al., 2021), mixing the two can broaden the pH of silver-bearing mineral flotation; thereby improving the stability of the flotation circuit. ...
... Flotation is a physicochemical method often used to upgrade low-grade silver in sulfide ore before the pretreatment and leaching process [8][9][10]. The silver mineral can be recovered by selective ore bulk flotation depending on the amount of minerals of interest to the ore [11]. Sulfide minerals of silver exhibit slow leaching or extraction rates, are called refractory silver ore and require a high cyanide concentration and a long leaching time to increase the recovery [12]. ...
... The effect of stirring speed on the silver dissolution in the range of 50-300 rpm is shown in Fig. 3. The rate of dissolution of silver decreases as the stirring speed increases because hydrogen peroxide decomposes at high rates of stirring speed, as shown in Eq. (11). Furthermore, the result at 200 rpm is similar to the result at 300 rpm. ...
In this article, the dissolution kinetics of pure metallic silver in acetic acid with a hydrogen peroxide solution were carried out. The effects of stirring speed, acetic acid concentration, hydrogen peroxide concentration, and temperature were examined. The results show that increasing the stirring speed decomposes the hydrogen peroxide and negatively affects the dissolution rate of silver. In addition, an acetic acid concentration in the range of 0.25–1 M has a positive effect and a negative effect in the range of 1–3 M. A hydrogen peroxide concentration in the range of 0.5–2 M has a significantly positive effect on the dissolution rate, while it has a negative effect in the range of 2–3 M. The temperature in the range of 61.5–70 °C has a negative effect due to the decomposition of hydrogen peroxide. The shrinking core model was applied to all parameters to obtain the dissolution kinetics. The dissolution process of silver was controlled by the surface reaction-controlled shrinking core model, i.e. 1-(1-X)1/3 = kst, with an activation energy of 28.80 kJ/mol.
... Flotation is the most widely used mineral processing technique in this field (Broadhurst and Harrison, 2015;Lamia, 2017;Nadeif et al., 2019). Previous laboratory-and intermediate-scale studies have shown that froth flotation is a feasible and cost-effective process for removing contaminant-bearing sulfur minerals from mine waste (Amar et al., 2020b;Benzaazoua et al., 2017;Benzaazoua et al., 2008;Bois et al., 2005;Drif et al., 2018;Noirant et al., 2019). Nonetheless, its effectiveness depends on various physicochemical (e.g., reagent type and concentration, mineral surface state, conditioning pH) (Derhy et al., 2022;El-bouazzaoui et al., 2022a) and hydrodynamic parameters (e.g., rotation speed, air flow). ...
... In order to accentuate the differences in surface features of sulfur minerals (hydrophobic state) and non-sulfide gangue minerals (NSG), particular reagents (e.g., collectors, frothers, and activators) are added to the slurry prior to the flotation process (Adkins and Pearse, 1992;Uçurum and Bayat, 2007;Wills and Finch, 2016). The reagent types and quantities are the key parameters that greatly influence the separation performance during the flotation process (Drif et al., 2018;Ghodrati et al., 2020;Mehrabani et al., 2010). In this context, the optimization of the process parameters is important to develop a process flowsheet for successful desulfurization of mine tailings to prevent CMD generation. ...
Sulfide ore processing generates finely ground mine tailings that often contain sulfide minerals such as pyrite, pyrrhotite, arsenopyrite, and gersdorffite. These minerals can generate acid mine drainage or contaminated neutral drainage (CND) due to weathering (aqueous oxidation by oxygen, and bacterial activity). Contaminated neutral mine drainage affects the surrounding environment by contaminant release (e.g., As, Ni, Fe, Cu, and Zn), which is one of the most challenging environmental issues for the mining industry. This paper examines the feasibility of desulfurization by flotation at the laboratory scale as a sustainable tailings management approach to prevent CND generation from tailings produced by the Amaruq mine (Nunavut, Canada). The flotation tests were conducted using a five-level statistical experimental design (DOE) using five parameters that include: collector dosage (PAX), activator dosage (CuSO4), frother dosage (MIBC), pH, and solid content (Cs). The response surface methodology (RSM) was used to predict sulfur recovery and to choose the optimal conditions of flotation. The mineralogical properties of the samples before and after reprocessing were investigated by combining optical microscopy, X-ray diffraction spectroscopy (XRD), and the quantitative evaluation of materials by scanning electron microscopy (QEMSCAN®). The trace element (As, Co, Ni, etc.) microanalysis of the identified minerals was quantified using electron probe micro-analyser (EPMA), and the bulk chemical composition was analyzed using induction furnace, X-ray fluorescence, and ICP-AES/MS. Finally, the geochemical behavior of the initial (WTT) and desulfurized (DWT) tailings was evaluated using kinetic weathering cells. The main results demonstrated that sulfur recovery can reach up to 97 % using the following optimal conditions: pH of 11.5, PAX dosage of 158 g/t, CuSO4 dosage of 300 g/t, MIBC dosage of 55 g/t, and Cs of 29.3 %. Moreover, the residual sulfides within the desulfurized tailings were completely locked within the non-sulfide gangue minerals as analyzed by QEMSCAN® and optical microscopy. Kinetic testing was performed on WTT and DWT to assess their contaminant release rates (especially As, Ni, Cu, Fe, and Zn). The desulfurized material did not cause any significant risk of contaminated mine drainage generation. All released contaminants were below the limits of Quebec provincial legislation.
... As described previously, arsenopyrite comprises more chemically bound Au than pyrite, and Au within the arsenopyrite is a gold solution Au + [26]. Ag is predominantly associated and recycled with Au, raising the potential for simultaneous recovery of both Au and Ag [27]. Ta Nang ore held higher metal contents including Fe, As, Ag, and Au than other ores collected at the Ural Federal District, Orenburg region, Russia [1]. ...
To date, bioleaching using bacterial consortia is widely regarded as an eco-friendly alternative to the traditional mining approaches due to its cost-effectiveness, feasibility, and sustainability. In the present study, for the first time, gold-bearing sulfide ore collected at Ta Nang mine, Vietnam was mineralogically characterized and subjected to bioleaching trial using indigenous bacterial consortia. The ore contains arsenopyrite, pyrite, galena, sphalerite, and chalcopyrite, of which the major metals were iron (4.78%), arsenic (1.73%), lead (0.43), and zinc (0.33%). After enrichment, a total of 19 iron- and sulfur-oxidizing bacteria were isolated and classified into six distinct genera including three previously described Bacillus, Pseudomonas, Acidithiobacillus, and three firstly reported heterotrophic Glutamicibacter, Providencia, and Stenotrophomonas from gold ore origin. Moreover, an autotrophic Acidithiobacillus sp. TNG6.3, sharing a 16S rRNA sequence of 95.1% identity with the closest sequence of the type strain A. caldus KU, represented a novel candidate species. The establishment of bioleaching utilizing enriched bacteria from gold ore consequently led to the removal of Ag (99.1%), Zn (37.9%), As (37.0%), and Fe (32.2%) from ore after 21 days of treatment, respectively. The present findings highlighted the potential of acidophilic bacteria originated from gold ores for extending applications in bioleaching of metals in Vietnam.
... Fundamental and applied research in mineral deportment of the critical minerals and elements is needed to, at a minimum, establish new proxies to estimate the abundance of important elements that are not routinely analyzed and, more preferably, develop new tools that industry can apply to efficiently and accurately assess mineral deportment throughout the mineral exploration and mining value chain (e.g., Nuss and Eckelman, 2014;Frenzel et al., 2017). New research in extracting critical elements from tailings piles, for example, is providing a path forward in this research space (e.g., Drif et al., 2018;Parbhakar-Fox et al., 2018;Guanira et al., 2020), but there is also mineral resource and economic opportunity for proactive mineral deportment research done prior to and/or during mining activities (e.g., Frenzel et al., 2019). This will not only provide the world with the critical raw materials for a sustainable future but also allow mining operations to extract the most value from their ores. ...
The critical minerals and elements are natural substances that are essential to modern life but have insecure supply. This lack of a secure supply clashes with the increasing importance of these elements, especially given their use in technologies needed to reduce global CO2 emissions and mitigate against anthropogenic climate change. In this contribution we review the by-product nature of the critical elements Co, Se, Te, Cd and Re and their inherited uncertainties in reported refined annual production as well as the origin transparency of their main-product metal concentrates, namely Cu, Ni, Zn and Mo. We explore the geological and geographical barriers to critical mineral and element supplies as well as how the lack of and uncertainties in available data hinder our ability to estimate global resources with confidence.
... The rejected minerals are called tailings and they consist of finely ground rocks and chemical additives which are often stored in tailings storage facilities (TSFs) [15]. Tailings can contain residual (non-)metalliferous minerals that can be valorised due to less efficient processing technologies of the past or because the contained minerals were not exploitable but are used as RMs in modern technologies [16][17][18][19][20][21]. Indeed, there are efforts to improve tailings-related safety by monitoring or the removal of contaminants for instance [22][23][24]. ...
Mapping the raw material (RM) potential of anthropogenic RMs, such as tailings, requires a comprehensive assessment and classification. However, a simple procedure to quickly screen for potentially viable RMs recovery projects similar to reconnaissance exploration of natural mineral RMs is missing. In this article, a quick and efficient approach to systematically screen tailings storage facilities (TSFs) is presented to evaluate if a particular TSF meets the criteria to be assessed in a more advanced study including costly on-site exploration. Based on aspects related to a TSF’s contents, physical structure, surroundings, potential environmental and social impacts, and potentially affected stakeholders, it guides its user in compiling the information at local scale in a structured manner compliant with the United Nations Framework Classification for Resources (UNFC). The test application to the TSF Bollrich (Germany), situated in a complex environment close to various stakeholders, demonstrates that a quick and remote assessment with publicly accessible information is possible. Since an assessment of tailings under conventional classification codes from the primary mining industry neglects relevant aspects, it is concluded that tailings should be considered as anthropogenic RMs. The developed screening approach can help to create a TSF inventory which captures project potentials and barriers comprehensively.
... Fundamental and applied research in mineral deportment of the critical minerals and elements is needed to, at a minimum, establish new proxies to estimate the abundance of important elements that are not routinely analyzed and, more preferably, develop new tools that industry can apply to efficiently and accurately assess mineral deportment throughout the mineral exploration and mining value chain (e.g., Nuss and Eckelman, 2014;Frenzel et al., 2017). New research in extracting critical elements from tailings piles, for example, is providing a path forward in this research space (e.g., Drif et al., 2018;Parbhakar-Fox et al., 2018;Guanira et al., 2020), but there is also mineral resource and economic opportunity for proactive mineral deportment research done prior to and/or during mining activities (e.g., Frenzel et al., 2019). This will not only provide the world with the critical raw materials for a sustainable future but also allow mining operations to extract the most value from their ores. ...
... The exacerbating water pollution by pathogenic contaminants and heavy metals (such as copper, gold, silver (>1000 ppb in waters even kilometres from mine sites [1,2]) makes it a pressing issue to create safe and potable drinking water from local water sources for remote households at industrial and mining areas [3,4]. Centralized water treatment systems, depending on reliable large-scale infrastructure and sustained power supply, are not feasible in these low-income or remote areas [5]. ...
In remote industrial areas, access to safe drinking water is often hindered by local water contamination and unreliable infrastructure. Hence, energy-effective water treatment and safe storage technology is vital and highly desirable to tackle complex water pollution caused by heavy metals and pathogenic contaminants for boundary circumstances. Here, we originally engineered a multifunctional gravity-driven membrane system to provide a household-level approach to pathogenic disinfection and biofouling prevention. Facile one-step polyphenol deposition strategy was applied on microporous membranes, tailoring the membrane surface with enhanced positive charge, favorable hydrophilicity and metal-binding ability. When applied in gravity-driven filtration of simulated multi-component wastewater containing heavy metals and pathogenic contaminants, the as-prepared membrane achieved > 6 log pathogenic reduction. Metal ions could be in-situ captured and stabilized at membrane interface via natural binding and reduction by polyphenol-engineered surface chemistry, endowing ensuing membranes with improved antibacterial activity. By virtue of enhanced membrane surface properties and antimicrobial synergy, such engineered membrane platform showed potent efficacy in biofilm prevention with 97% reduced ATP content and easy permeation recovery (more than 90%) in cyclic operation. This study is promising for developing low-energy and easy-to-use membrane system to improve contaminated water sources in remote and underdeveloped areas at household level.
... In nature, silver is often associated with sulfide minerals such as chalcopyrite, sphalerite and pyrite (Drif et al., 2018;Zhao et al., 2015). Silver bearing chalcopyrite usually contains up to 2∼3 wt% silver (Bakhsh, 2018;Kotkova et al., 2018). ...
... This technique was applied by Nadeif et al. [8] to reprocess tailings from an abandoned mine to avoid acid mine drainage and to recover the residual metals (Au, Ag, and Cu). The same approach was adopted by Drif et al. [9], who succeeded in recovering silver-bearing minerals, mainly in the form of sulfides, from low-grade tailings by froth flotation processing. By doing so, the authors proved that the cleaned tailings are inert and do not present any leaching risk according to a toxicity characteristic leaching procedure test (TCLP). ...
The mining industry continues to face many challenges due to its potential environmental impacts [...]
