scholarly journals Potential of Mechanochemically Activated Sulfidic Mining Waste Rock for Alkali Activation

2021 ◽  
Author(s):  
He Niu ◽  
Lugas Raka Adrianto ◽  
Alexandra Gomez Escobar ◽  
Vladimir Zhukov ◽  
Priyadharshini Perumal ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Chemical Reactivity ◽  
Construction Materials ◽  
Mining Industry ◽  
Mining Waste ◽  
Waste Rock ◽  
Alkali Activation ◽  
Curing Conditions ◽  
Grinding Mechanism ◽  
Diffuse Reflectance Infrared

Abstract Sulfidic mining waste rock is a side stream from the mining industry with a potential environmental burden. Alkali activation is a promising method for transforming mining waste into construction materials. However, the low reactivity of minerals can be a sizeable challenge in alkali activation. In the present study, the reactivity of waste rock was enhanced by mechanochemical treatment with a LiCl-containing grinding aid. X-ray diffraction (XRD) and diffuse reflectance infrared Fourier transform (DRIFT) analysis were utilized to display the structural alteration of individual minerals. A schematic implication of the grinding mechanism of mica was provided according to the results of transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The alkaline solubility displayed the enhanced chemical reactivity of the waste rock, in which Si and Al solubility increased by roughly 10 times and 40 times, respectively. The amorphization of aluminosilicate is achieved through chemical assisted mechanochemical activation. Sulfidic waste rock, as the sole precursor in alkali activation, achieved a 28-day compressive strength exceeding 10 MPa under ambient curing conditions. The simulation of the upscaled grinding process was conducted via the HSC Chemistry® software with a life-cycle assessment. The results showed that mining waste rock can be a promising candidate for geopolymer production with a lower carbon footprint, compared to traditional Portland cement. Graphical Abstract

Mine waste reuse and reprocessing: an important step for the implementation of the circular economy in Europe

2021 ◽  
Author(s):  
Françoise Bodénan ◽  
Yannick Ménard ◽  
Patrick d'Hugues
Keyword(s):  
Circular Economy ◽  
Mine Waste ◽  
Construction Materials ◽  
Mining Industry ◽  
Mining Waste ◽  
Management Approach ◽  
Secondary Resources ◽  
Mineral Fraction ◽  
Long Term Treatment

<p>Whereas there are growing needs for mineral resources (metals for the energy and digital transitions<br>and construction materials), the mining industry must produce them from poorer, more<br>heterogeneous and more complex deposits. Therefore, volumes of mine waste produced (including<br>tailings) are also increasing and add up to waste from mining legacy. For example in Europe (x27): 732<br>Mtons of extractive waste are generated per year and more than 1.2 Btons of legacy waste are stored<br>all over the European territory. The localisation (and potential hazards) are well known and covered<br>by the inventories carried out in EU countries under the Mining Waste Directive.<br>At the same time, Europe is implementing the circular economy approach and put a lot of emphasis<br>on the resource efficiency concept. In this context, reprocessing operation to recover both metals and<br>mineral fraction is studied with the objective of combing waste management (reducing final waste<br>storage and long-term impact) and material production from secondary resources.<br>Numerous industrial experiences of reprocessing of mine waste and tailings exist all over the world to<br>recover metals such as copper, gold or critical raw materials - CRM They concern mainly active mine<br>where both primary and secondary resources are considered in profitable operations; for example in<br>Chile, South Africa, Australia. Mineral fraction recovery is often not considered which still leaves the<br>industry with a high volume of residual minerals to store and manage.<br>In addition, legacy mining waste are potentially available for reprocessing. In this case, numerous<br>mining liabilities issues need to be managed. Some of the European legacy mining waste have residual<br>valuable metals that could be recovered but some of them have very low metal contents. In Europe,<br>classical rehabilitation operations – usually at the charge of member states and local authorities – is<br>the priority and concern the reduction of instabilities and impacts to the environment including heap<br>remodelling, covering and water management with long-term treatment. Completing this risk<br>management approach by a circular economy one is a very active R&D subject in EU27.<br>This presentation will give an overview of EU research projects which tackled the legacy mining waste<br>challenge from inventory to process development. Several process flowsheets to recover metals were<br>designed and tested on several case studies with CRM – REE, Co, W, Sb, etc. Initiatives to reuse mineral<br>fraction are also underway and should be ready for commercialisation in the coming years.<br>Resources efficiency concept and the circular economy implementation starts on mining sites. In order<br>to facilitate the implementation of this approach, the technical solutions will need to be included in<br>innovative global initiatives covering also legal (liability management), environmental (Life Cycle<br>Analysis approaches) and social (acceptance) questions.</p>

Characterization and valorization of the waste from the abandoned Kettara mine and the gypsum quarry in Sidi Tijji (Marrakech-Safi Region, Morocco).

2020 ◽  
Author(s):  
Assma Bouiji ◽  
Omar witam ◽  
Mounsif Ibnoussina
Keyword(s):  
Cultural Change ◽  
Raw Materials ◽  
Mine Waste ◽  
Research Work ◽  
Construction Materials ◽  
Mining Waste ◽  
Waste Rock ◽  
Natural Habitats ◽  
Waste Products ◽  
Integrated Recovery

<p>In Morocco, no measures have been taken to manage residual waste from operational or abandoned mining and quarries sites.</p><p>Indeed, significant quantities of mine waste, composed of concentrator residues and sterile waste, have been abandoned after the closure of operations without any effective management or rehabilitation planning.</p><p>These residues could have harmful impacts on the environment: soil and water pollution, destruction or disturbance of natural habitats, visual impact on the countryside...</p><p>The valorization and sustainable management of mining waste appear to be adequate solutions to major environmental problems. The construction sector can be a profitable sector to absorb chemically stable mining waste.</p><p>The objective of this research work is to study the feasibility of recycling waste from the abandoned Kettara mine (Morocco) and gypsum waste rock in Sidi Tijji (Morocco) as raw materials in construction materials.</p><p>The study consists first of a geological characterization and then a characterization of the physical, chemical and mineralogical properties of the residues, followed by an evaluation of the mechanical properties of the composite mixtures based on the chemically stable residues.</p><p>The Kettara mine is located in the Jbilet Central Mountains, 30 km northwest of Marrakech. Geologically, the pyrrhotite district of Kettara corresponds to the outcrop area of the volcano-sedimentary series of Saghlef shales. For the gypsum quarry at Sidi Tijji, which is part of the Safi basin, characterized by Jurassic outcrops essentially formed by gypsum and carbonate formations.</p><p>Mineralogical and chemical analysis have shown that these waste products are still rich in minerals such as the waste from the Kettara mine; the FeO3 concentrated amounts to 55.6%. In addition, gypsum waste rock represents a concentration of 28.9% CaO. Therefore, a low water content for the majority of samples.</p><p>Adapting to the principles of integrated recovery and management of mining and quarry waste requires a cultural change within the industry, but also in the ministries concerned.</p><p><strong>Keywords</strong>: Valorization, mine waste, mines and quarries, construction materials.</p>

scholarly journals Alkali Activation of Silicate Mine-Tailings: Response to Different Activator Sources

Proceedings ◽  
2019 ◽  
Vol 34 (1) ◽  
pp. 10
Author(s):  
Perumal ◽  
Illikainen
Keyword(s):  
Sodium Silicate ◽  
Sodium Carbonate ◽  
Mine Tailings ◽  
Construction Materials ◽  
Mining Industry ◽  
Sodium Silicate Solution ◽  
Sodium Sulphate ◽  
High Alumina ◽  
Alkali Activation ◽  
Early Age

To attain sustainability in construction industries, it is important to explore industrial side-streams as a potential replacement for traditional construction materials. This will avoid the depletion of natural resources and helps in preserving the environment. In this way, mining industry attracts the attention of scientific community for the huge volume of tailings generated along with the problem of disposal. This paper mainly focuses on silicate tailings (MT) from two different mining sources with high magnesium (HM) and high alumina (HA) content. To study the possibility of using these tailings as precursors in alkali activation, different activators such as, sodium silicate (Na2SiO3), sodium sulphate (Na2SO4) and sodium carbonate (Na2CO3) were employed. It was noted that the mine tailings took longer time to set in case of activators other than sodium silicate. The milled tailings were co-grinded with the respective solid activators (10%) and mixed with 30% of sodium silicate solution (accelerates setting), to make cylindrical paste specimens. The specimens were cured at 60 °C for 24 h. The results shown that tailings rich in magnesium (MT-HM) activated with sodium carbonate gives high early age strength i.e., 60% increase in average strength compared to other activators. Whereas, sodium silicate helped in achieving 10% increase in early age strength of high alumina tailings (MT-HA). However, this was not the case for the later ages. At 7th day of testing, sodium silicate activated MT-HM shown a strength improvement from 2 MPa to 6 MPa with the formation of magnesium silicate hydrate and hydrotalcite. MT-HA activated with sodium sulphate resulted in a maximum strength of 8.5 MPa due to the ettringite and zeolite in the system. Sodium carbonate does not show comparable results at 7th day of testing though it shown improvement in strength with age. It is also important to consider that there are other oxides like calcium and iron present in these tailings which could also have impacted the results.

scholarly journals Influencing Factors of the Mineral Carbonation Process of Iron Ore Mining Waste in Sequestering Atmospheric Carbon Dioxide

2021 ◽  
Vol 13 (4) ◽  
pp. 1866
Author(s):  
Noor Allesya Alis Ramli ◽  
Faradiella Mohd Kusin ◽  
Verma Loretta M. Molahid
Keyword(s):  
Carbon Dioxide ◽  
Particle Size ◽  
Chemical Composition ◽  
Iron Ore ◽  
Divalent Cations ◽  
Mining Industry ◽  
Mining Waste ◽  
Aluminum Silicate ◽  
Mineral Carbonation ◽  
Carbonation Process

Mining waste may contain potential minerals that can act as essential feedstock for long-term carbon sequestration through a mineral carbonation process. This study attempts to identify the mineralogical and chemical composition of iron ore mining waste alongside the effects of particle size, temperature, and pH on carbonation efficiency. The samples were found to be alkaline in nature (pH of 6.9–7.5) and contained small-sized particles of clay and silt, thus indicating their suitability for mineral carbonation reactions. Samples were composed of important silicate minerals needed for the formation of carbonates such as wollastonite, anorthite, diopside, perovskite, johannsenite, and magnesium aluminum silicate, and the Fe-bearing mineral magnetite. The presence of Fe2O3 (39.6–62.9%) and CaO (7.2–15.2%) indicated the potential of the waste to sequester carbon dioxide because these oxides are important divalent cations for mineral carbonation. The use of small-sized mine-waste particles enables the enhancement of carbonation efficiency, i.e., particles of <38 µm showed a greater extent of Fe and Ca carbonation efficiency (between 1.6–6.7%) compared to particles of <63 µm (0.9–5.7%) and 75 µm (0.7–6.0%). Increasing the reaction temperature from 80 °C to 150–200 °C resulted in a higher Fe and Ca carbonation efficiency of some samples between 0.9–5.8% and 0.8–4.0%, respectively. The effect of increasing the pH from 8–12 was notably observed in Fe carbonation efficiency of between 0.7–5.9% (pH 12) compared to 0.6–3.3% (pH 8). Ca carbonation efficiency was moderately observed (0.7–5.5%) as with the increasing pH between 8–10. Therefore, it has been evidenced that mineralogical and chemical composition were of great importance for the mineral carbonation process, and that the effects of particle size, pH, and temperature of iron mining waste were influential in determining carbonation efficiency. Findings would be beneficial for sustaining the mining industry while taking into account the issue of waste production in tackling the global carbon emission concerns.

scholarly journals Fayalite Slag as Binder and Aggregate in Alkali-Activated Materials—Interfacial Transition Zone Study

Proceedings ◽  
2019 ◽  
Vol 34 (1) ◽  
pp. 1 ◽  
Author(s):  
Adediran ◽  
Yliniemi ◽  
Illikainen
Keyword(s):  
Transition Zone ◽  
Sodium Hydroxide Solution ◽  
Coal Fly Ash ◽  
Construction Materials ◽  
Fine Powder ◽  
Silicate Solution ◽  
Interfacial Transition Zone ◽  
Alkali Activation ◽  
Fayalite Slag ◽  
Alkali Activated

Alkali-activated materials (AAMs) are an environmentally friendly option for Portland cement mortars and concretes. Many industrial residues such as blast furnace slag and coal fly ash have been extensively studied and applied as AAM precursors but much less focus has been on the use of fayalite slags. Water-cooled fayalite slag comes in granular form, which is then milled into fine powder (d50 ~10 microns) prior to its alkali activation. In addition, the un-milled granular fayalite slag can be used as an aggregate to replace sand in mortar. The alkaline solution utilized for the study was a mix of 10 M sodium hydroxide solution and commercial potassium silicate solution. A liquid to solid ratio of 0.15 was held constant for all the mixes. The particle size distributions of the binder and the aggregates were optimized, and the microstructure and chemical composition of the interfacial transition zone (ITZ) was studied using scanning electron microscope coupled with energy dispersive X-ray spectroscopy. ITZ is a region that exists between the aggregate and the binder and this can influence the mechanical and transport properties of the construction materials. The results showed that the mechanical properties of mortar having fayalite slag as aggregate and binder was significantly higher than one with standard sand as aggregate. No distinct ITZ was found in the samples with fayalite slag as aggregate. The outer rim of the fayalite slag aggregate participated in the hardening reaction and this significantly contributed to the bonding and microstructural properties of the mortar samples. In contrast, an ITZ was observed in mortar samples with standard sand aggregates, which contributed to its lower strength.

scholarly journals Synthesis, Computational Pharmacokinetics Report, Conceptual DFT-Based Calculations and Anti-Acetylcholinesterase Activity of Hydroxyapatite Nanoparticles Derived From Acorus Calamus Plant Extract

2021 ◽  
Vol 9 ◽  
Author(s):  
Sushma Pradeep ◽  
Anisha S. Jain ◽  
Chandan Dharmashekara ◽  
Shashanka K. Prasad ◽  
Nagaraju Akshatha ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Density Functional ◽  
Chemical Reactivity ◽  
Acetylcholinesterase Activity ◽  
Acorus Calamus ◽  
Hydroxyapatite Nanoparticles ◽  
Transmission Electron ◽  
In Silico Studies ◽  
Crystalline Nature

Over the years, Alzheimer’s disease (AD) treatments have been a major focus, culminating in the identification of promising therapeutic targets. A herbal therapy approach has been required by the demand of AD stage-dependent optimal settings. Present study describes the evaluation of anti-acetylcholinesterase (AChE) activity of hydroxyapatite nanoparticles derived from an Acorus calamus rhizome extract (AC-HAp NPs). The structure and morphology of as-prepared (AC-HAp NPs) was confirmed using powder X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM). The crystalline nature of as-prepared AC-HAp NPs was evident from XRD pattern. The SEM analysis suggested the spherical nature of the synthesized material with an average diameter between 30 and 50 nm. Further, the TEM and HR-TEM images revealed the shape and size of as-prepared (AC-HAp NPs). The interplanar distance between two lattice fringes was found to be 0.342 nm, which further supported the crystalline nature of the material synthesized. The anti-acetylcholinesterase activity of AC-HAp NPs was greater as compared to that of pure HAp NPs. The mechanistic evaluation of such an activity carried out using in silico studies suggested that the anti-acetylcholinesterase activity of phytoconstituents derived from Acorus calamus rhizome extract was mediated by BNDF, APOE4, PKC-γ, BACE1 and γ-secretase proteins. The global and local descriptors, which are the underpinnings of Conceptual Density Functional Theory (CDFT), have been predicted through the MN12SX/Def2TZVP/H2O model chemistry to help in the comprehension of the chemical reactivity properties of the five ligands considered in this study. With the further objective of analyzing their bioactivity, the CDFT studies are complemented with the estimation of some useful computed pharmacokinetics indices, their predicted biological targets, and the ADMET parameters related to the bioavailability of the five ligands are also reported.

scholarly journals Pollution Characteristics of Sb, As, Hg, Pb, Cd, and Zn in Soils from Different Zones of Xikuangshan Antimony Mine

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Saijun Zhou ◽  
Andrew Hursthouse ◽  
Tengshu Chen
Keyword(s):  
Risk Index ◽  
Hydride Generation ◽  
Morphological Characteristics ◽  
Soil Samples ◽  
Mining Waste ◽  
Waste Rock ◽  
Residual Fraction ◽  
Chemical Extraction ◽  
Underground Tunnel ◽  
Sequential Chemical Extraction

Major sources of pollution during the antimony (Sb) mining and processing are mining waste rock, smelting waste, tailings dam, and underground tunnel wastewater. The aim of the present study was to assess magnitude of pollution from Sb mine by taking four types of samples: soil in the mining waste rock zone, soil in the smelting zone, soil in tailings zone, and soil in underground tunnel wastewater zone. Sixty soil samples from the four zones were taken for experimental work, and the contents and morphological characteristics of the six potentially toxic elements (PTEs) such as Sb, As, Hg, Pb, Cd, and Zn in the soil samples were measured by using a hydride generation atomic fluorescence spectrometer (AFS-9700). The results show that the soil of the mine area is seriously polluted. The average contents of Sb, As, Hg, Pb, Cd, and Zn in the soil reach 1267.20 mg·kg−1, 94.44 mg·kg−1, 1.46 mg·kg−1, 184.19 mg·kg−1, 8.54 mg·kg−1, and 1054.11 mg·kg−1, respectively. There exists good correlation between the PTEs in the soil, with Sb strongly positively correlated with As, Hg, Pb, and Zn. The intensity of pollution is highest in the antimony-smelting zone, where the potential ecological risk index is over 15,000, followed by the tailings zone and mining waste rock zone, with the underground tunnel wastewater zone being the lowest. Using sequential chemical extraction, the elements are associated with the residual fraction, followed by organic-sulfide fraction, and smaller portions in the Fe-Mn oxide, carbonate, and exchangeable fractions. There are great differences in the speciation content of different elements in different sampling zones. The study implicates that Sb-smelting zone is the potential source of PTEs and maximum metals are associated with residual phase, out of which significant portion is associated with mobile fraction or phase.

Alkali activation of fly ash. Part III: Effect of curing conditions on reaction and its graphical description

Fuel ◽  
2010 ◽  
Vol 89 (11) ◽  
pp. 3185-3192 ◽  
Author(s):  
M. Criado ◽  
A. Fernández-Jiménez ◽  
A. Palomo
Keyword(s):  
Fly Ash ◽  
Alkali Activation ◽  
Curing Conditions

Strength Development Characteristic of Cementless Mortar for Repair of Concrete

2018 ◽  
Vol 774 ◽  
pp. 277-282
Author(s):  
Gum Sung Ryu ◽  
Kyung Taek Koh ◽  
Gi Hong An ◽  
Hyeong Yeol Kim ◽  
Sung Choi
Keyword(s):  
Concrete Structures ◽  
Strength Development ◽  
Alkali Activation ◽  
Curing Conditions ◽  
Granulated Blast Furnace Slag ◽  
Repair Materials ◽  
Binder Ratio ◽  
Development Characteristic ◽  
High Bond ◽  
High Bond Strength

Repair materials for concrete structures are often required to exhibit high bond strength at a concrete substrate, and it typically consists of ordinary Portland cement (OPC) incorporating expensive admixtures at a low water-to-binder ratio. Meanwhile, cementless mortar employs alkali-activation of cementless and pozzolanic precursors such as ground granulated blast-furnace slag (GGBFS) and fly ash (FA). The final product develops strength relatively faster than OPC, and its strength can be flexibly talyored by controlling the type and dosage of the activator. The present study investigates the strength development characteristic of cementles mortar for use in repair of concrete structures. Independent variables include mix proportions and curing conditions, which were chosen to optimize the performance of the cementless mortar.

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