Research

21 pages, 2157 KiB

Open AccessArticle

Potential of Tailing Deposits in Chile for the Sequestration of Carbon Dioxide Produced by Power Plants Using Ex-Situ Mineral Carbonation

by Oscar Marín, José O. Valderrama, Andrzej Kraslawski and Luis A. Cisternas

Minerals 2021, 11(3), 320; https://doi.org/10.3390/min11030320 - 19 Mar 2021

Cited by 11 | Viewed by 4092

Abstract

In this study, the potential of copper tailing deposits in Chile for the sequestration of carbon dioxide (CO₂) via ex-situ mineral carbonation integrating the recovery of valuable metals was assessed. An inventory of tailing deposits and CO₂ sources existing in [...] Read more.

In this study, the potential of copper tailing deposits in Chile for the sequestration of carbon dioxide (CO₂) via ex-situ mineral carbonation integrating the recovery of valuable metals was assessed. An inventory of tailing deposits and CO₂ sources existing in Chile was constructed to determine the most suitable site for the installation of a future mineral carbonation plant and to evaluate the technical, economic, and environmental feasibility of CO₂ capture, separation, and transport from the source to the mineral carbonation plant. The data of the inventory of tailings deposits in Chile were obtained from the National Service of Geology and Mining. For the thermoelectric plants installed in Chile, data of energy production were obtained from the Energy National Commission. Through the use of the technique for order preference by similarity to ideal solution (TOPSIS) method and sensitivity analysis, the optimum location in the region of Antofagasta to install a mineral carbonation plant was identified. In addition, the results show that in the region of Antofagasta five tailing deposits have the potential to sequester between 66 to 99 Mt of CO₂. Meanwhile, thermoelectric plants in 2018 produced about 9.4 Mt of CO₂ that is available to be sequestered, with a maximum generation potential of 21.9 Mt of CO_2eq per year. The methodology and the study presented can be considered as a preliminary study to identify tailings that require further analysis. Full article

(This article belongs to the Special Issue Cleaner Production in Mineral Processing)

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14 pages, 2195 KiB

Open AccessArticle

Improving the Flocculation Performance of Clay-Based Tailings in Seawater: A Population Balance Modelling Approach

by Gonzalo R. Quezada, Matías Jeldres, Pedro Robles, Norman Toro, David Torres and Ricardo I. Jeldres

Minerals 2020, 10(9), 782; https://doi.org/10.3390/min10090782 - 04 Sep 2020

Cited by 3 | Viewed by 2102

Abstract

A population balance model described the flocculation of clay-based mining tailings in treated seawater with reduced magnesium content. For the treatment, 0.06 M of lime was added to the liquor, generating solid magnesium complexes that were subsequently removed by vacuum filtration. Magnesium content [...] Read more.

A population balance model described the flocculation of clay-based mining tailings in treated seawater with reduced magnesium content. For the treatment, 0.06 M of lime was added to the liquor, generating solid magnesium complexes that were subsequently removed by vacuum filtration. Magnesium content varied between 10–1440 ppm when mixing raw seawater with treated seawater. The aggregate size was analysed by the Focused Beam Reflectance Measurement (FBRM) technology. The model follows the dynamics of the aggregation-rupture and it provides a good approximation to the temporal evolution. A decrease in collision efficiency was implemented as an indicator of the polymer depletion, describing the size reduction. Lower magnesium content makes larger aggregates with a higher fractal dimension, but an increase in the concentration of clays reduces both the size of aggregates and the fractal dimension, indicating more open and porous structures, with higher permeability to the passage of fluid. The model efficiently illustrates the experimental data, with R-square (R²) greater than 0.9 and Goodness of Fit (GoF) greater than 95% in most cases, wherein the fitting parameters allowed for analysing the impact of magnesium and clays on the collision efficiency, collision frequency, and fragmentation rate. The model is predictive with few parameters, and it is potentially a powerful tool for water management optimisation. Full article

(This article belongs to the Special Issue Cleaner Production in Mineral Processing)

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15 pages, 2913 KiB

Open AccessArticle

Uranium (VI) Recovery from Black Shale Leaching Solutions Using Ion Exchange: Kinetics and Equilibrium Studies

by Omirserik Baigenzhenov, Alibek Khabiyev, Brajendra Mishra, M. Deniz Turan, Merey Akbarov and Tatyana Chepushtanova

Minerals 2020, 10(8), 689; https://doi.org/10.3390/min10080689 - 31 Jul 2020

Cited by 4 | Viewed by 4028

Abstract

This work studies the removal of uranium ions from chemically leached solutions by sorption using two weak and two strong base anionites. Batch sorption experiments were performed to evaluate the optimum conditions at pH 1.2–2.2, 1.0 g resin dose for 1–12 h contact [...] Read more.

This work studies the removal of uranium ions from chemically leached solutions by sorption using two weak and two strong base anionites. Batch sorption experiments were performed to evaluate the optimum conditions at pH 1.2–2.2, 1.0 g resin dose for 1–12 h contact time at room temperature. These experiments addressed sorption kinetics and sorption isotherm. The maximum sorption capacity reached 55.8 mg/g at room temperature. The kinetics data are well described by the pseudo-second-order kinetic model at initial uranium concentration of 0.62 mg·L⁻¹. To describe sorption kinetics pseudo-first-order, pseudo-second-order and intraparticle diffusion models were proposed. Studies indicated that the sorption of uranium can be fitted by a pseudo-second-order kinetic model very well. Equilibria were described by Langmuir, Freundlich, and Dubinin–Radushkevich equations. The experimental sorption isotherm is successfully described by the Langmuir model. Full article

(This article belongs to the Special Issue Cleaner Production in Mineral Processing)

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21 pages, 6153 KiB

Open AccessArticle

Yoko–Dovyren Layered Massif: Composition, Mineralization, Overburden and Dump Rock Utilization

by Evgeniy V. Kislov and Lyudmila I. Khudyakova

Minerals 2020, 10(8), 682; https://doi.org/10.3390/min10080682 - 30 Jul 2020

Cited by 7 | Viewed by 3320

Abstract

Ultramafic–mafic complexes are widely developed in the Earth’s crust. They contain deposits of various minerals. The Yoko–Dovyren intrusive in the North Baikal Region, Russia, is considered an example of an intrusive containing diverse mineralization: Ni-Cu, Platinum group elements, Cr, Zr, B, and blue [...] Read more.

Ultramafic–mafic complexes are widely developed in the Earth’s crust. They contain deposits of various minerals. The Yoko–Dovyren intrusive in the North Baikal Region, Russia, is considered an example of an intrusive containing diverse mineralization: Ni-Cu, Platinum group elements, Cr, Zr, B, and blue diopside. During the development of the deposit, a huge amount of magnesium-containing rocks are moved to dumps and have a negative impact on the environment. To minimize this process, overburden and host rocks need to be involved in production, thereby avoiding the movement of rocks into dumps. The construction materials production is main industry using this rocks. Therefore, the purpose of these studies was to determine the quality of magnesium-containing rocks and the possibility of their use in construction. As a result of the complex works performed, it has been determined that these rocks have required physical and mechanical characteristics. Concretes in large and small aggregates from magnesium-containing rocks were obtained. It has been concluded that they are superior to concrete from granite rubble and quartz sand in terms of their strength indicators. The use of magnesium-containing rocks, without allowing them to fall into dumps, will allow us to create clean, environmentally safe mining enterprises. Full article

(This article belongs to the Special Issue Cleaner Production in Mineral Processing)

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12 pages, 2744 KiB

Open AccessArticle

Effect of Additive Material on Controlling Chromium (Cr) Leaching from Coal Fly Ash

by Erda Rahmilaila Desfitri, Ulung Muhammad Sutopo, Yukio Hayakawa and Shinji Kambara

Minerals 2020, 10(6), 563; https://doi.org/10.3390/min10060563 - 23 Jun 2020

Cited by 4 | Viewed by 2281

Abstract

Coal fly ash contains a considerable number of toxic elements that can be leached into the environment, such as chromium (Cr), thereby quickly leading to severe contaminations. In this research, the leaching behaviors of Cr were analyzed from 14 kinds of coal fly [...] Read more.

Coal fly ash contains a considerable number of toxic elements that can be leached into the environment, such as chromium (Cr), thereby quickly leading to severe contaminations. In this research, the leaching behaviors of Cr were analyzed from 14 kinds of coal fly ash samples collected from the electrostatic precipitators of coal-fired thermal power plants in Japan. The level of Cr concentration found in the samples varied from 0.00 to 82.93 μg/L. However, Cr toxicity depends on its valence state; Cr⁶⁺ is more toxic than Cr³⁺. Additive materials containing high calcium content were used to control the leaching concentration of Cr, such as Ca(OH)₂, paper sludge ash, and blast furnace cement. This research used several instruments. An X-ray fluorescence was adopted to measure the major chemical composition of the fly ash samples and the additive materials. A thermogravimetric analyzer was used to examine the calcium compounds in the additive materials. Inductively coupled plasma was used to determine the Cr leaching concentrations from the fly ash samples. Findings showed that the three-additive mixture had a promising effect on controlling the Cr leaching concentrations. These results were also supported by FactSage 7.2 simulation. Full article

(This article belongs to the Special Issue Cleaner Production in Mineral Processing)

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14 pages, 4091 KiB

Open AccessArticle

Cleaner Production of Chromium Oxide from Low Fe(II)-Chromite

by Qing Zhao, Chengjun Liu, Peiyang Shi, Lifeng Sun, Maofa Jiang, Henrik Saxen and Ron Zevenhoven

Minerals 2020, 10(5), 460; https://doi.org/10.3390/min10050460 - 19 May 2020

Cited by 5 | Viewed by 3338

Abstract

Sulfuric acid-based leaching is a promising cleaner method to produce chromium salts, but its feasibility for treating low Fe(II)-chromite still remains to be proven. A Box–Behnken design (BBD)-based set of experiments for sulfuric acid leaching of low Fe(II)-chromite was utilized in this work [...] Read more.

Sulfuric acid-based leaching is a promising cleaner method to produce chromium salts, but its feasibility for treating low Fe(II)-chromite still remains to be proven. A Box–Behnken design (BBD)-based set of experiments for sulfuric acid leaching of low Fe(II)-chromite was utilized in this work for generating an experimental dataset for revealing the functional relationships between the processing parameters and the extraction yields of Cr and Fe. The dependent variables were found to exhibit strong intercorrelations and the models developed on the basis of statistical criteria showed excellent prediction accuracy. The optimum process conditions of leaching treatment were found to be a temperature of 176 °C, a dichromic acid/chromite mass ratio of 0.12, and a sulfuric acid concentration of 81%. Furthermore, the dissolution behavior of chromite in the leaching process and the effect of dichromic acid were experimentally investigated. It was found that the decomposition efficiency was highly dependent on the Fe(II) content of chromite, and that the dichromic acid acted both as an oxidant and a catalyst in the leaching process. On the basis of the results of this study, a novel process for treating low-Fe(II) chromite was proposed. Full article

(This article belongs to the Special Issue Cleaner Production in Mineral Processing)

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13 pages, 2936 KiB

Open AccessArticle

Analysis of Kaolin Flocculation in Seawater by Optical Backscattering Measurements: Effect of Flocculant Management and Liquor Conditions

by Ricardo I. Jeldres, Matías Jeldres, Michael R. MacIver, Marek Pawlik, Pedro Robles and Norman Toro

Minerals 2020, 10(4), 317; https://doi.org/10.3390/min10040317 - 31 Mar 2020

Cited by 6 | Viewed by 2414

Abstract

Optical backscattering (OBS) signal values were used to evaluate the flocculation of kaolin slurries and seek the implications of using seawater. Two anionic flocculants were applied to kaolin suspensions at several dosages and in water of varying pH and electrolyte concentration. An OBS [...] Read more.

Optical backscattering (OBS) signal values were used to evaluate the flocculation of kaolin slurries and seek the implications of using seawater. Two anionic flocculants were applied to kaolin suspensions at several dosages and in water of varying pH and electrolyte concentration. An OBS height scan method was used to estimate the degree of aggregation, supernatant quality, and solids concentration of the sediments. The residual solids of the supernatant depended of the extent of particle coagulation before flocculant was added, where the pH and salinity displayed a significant impact on flocculation. The OBS results were highly sensitive to the presence of fine particles, which was estimated in parallel from the focused beam reflectance measurements (FBRM.) In seawater, without flocculant added, the samples had increased root-mean-square scattering (F_rms) values and larger final sediment volume than samples prepared in water with lower electrolyte concentration. This indicates a higher initial state of aggregation of the particles in seawater. Then, the aggregation degree was best linked to the square-weighted chord length distribution of the FBRM data, which intensifies the sensitivity to coarse aggregates. Full article

(This article belongs to the Special Issue Cleaner Production in Mineral Processing)

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13 pages, 1087 KiB

Open AccessArticle

The Role of Gangue Mineralogy on Flowsheet Development in Fluorite Processing

by Jestos Taguta, Kebone Carol Teme and Portia Ngobeni

Minerals 2020, 10(3), 237; https://doi.org/10.3390/min10030237 - 06 Mar 2020

Cited by 1 | Viewed by 3671

Abstract

Fluorite, CaF₂, is considered a strategically important mineral as it is a raw material for many strategic industries. Froth flotation is reported to be the most efficient and economically viable process for the production of an acid-grade product with a CaF [...] Read more.

Fluorite, CaF₂, is considered a strategically important mineral as it is a raw material for many strategic industries. Froth flotation is reported to be the most efficient and economically viable process for the production of an acid-grade product with a CaF₂ content of at least 97%. Selective flotation of fluorite from gangue minerals, e.g., calcite and barite, is challenging because these minerals have similar physicochemical properties. This study employed batch flotation tests coupled with mineralogical analysis to design suitable customised flowsheets and efficiently optimised reagent regimes for optimum production of acid-grade fluorite concentrate from two different fluorite ores by the froth flotation process. The effect of pulp temperature on fluorite flotation was investigated in this study with the objective of lowering pulp temperatures in fluorite flotation. The results showed that an acid-grade CaF₂ concentrate could be obtained from the flotation of both ores at ambient pulp temperatures. This eliminates the requirement for high-temperature pulp treatment, which would result in a significant reduction in thermal energy costs. This study showed that an understanding of gangue mineralogy is key to process optimisation for acid-grade CaF₂ production. Although an acid-grade CaF₂ concentrate could be produced from both ores, the flowsheets and reagent regimes were markedly different. For instance, the production of an acid-grade CaF₂ product from a high quartz and calcite ore was achieved by employing a simple rougher–multiple cleaner flotation circuit using tannin and sodium silicate as calcite and quartz depressants, respectively. On the other hand, the production of an acid-grade CaF₂ product from the flotation of the pyritic ore required a pre-sulphide flotation stage for upfront sulphur removal and the use of a sulphide depressant. Multiple stages of cleaning were required for improved selectivity in the flotation of both ores. Full article

(This article belongs to the Special Issue Cleaner Production in Mineral Processing)

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11 pages, 3930 KiB

Open AccessArticle

Extraction of Boron from Ludwigite Ore: Mechanism of Soda-Ash Roasting of Lizardite and Szaibelyite

by Xin Zhang, Guanghui Li, Jinxiang You, Jian Wang, Jun Luo, Jiaoyang Duan, Tao Zhang, Zhiwei Peng, Mingjun Rao and Tao Jiang

Minerals 2019, 9(9), 533; https://doi.org/10.3390/min9090533 - 31 Aug 2019

Cited by 20 | Viewed by 4205

Abstract

Ludwigite ore is a typical low-grade boron ore accounting for 58.5% boron resource of China, which is mainly composed of magnetite, lizardite and szaibelyite. During soda-ash roasting of ludwigite ore, the presence of lizardite hinders the selective activation of boron. In this work, [...] Read more.

Ludwigite ore is a typical low-grade boron ore accounting for 58.5% boron resource of China, which is mainly composed of magnetite, lizardite and szaibelyite. During soda-ash roasting of ludwigite ore, the presence of lizardite hinders the selective activation of boron. In this work, lizardite and szaibelyite were prepared and their soda-ash roasting behaviors were investigated using thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope and energy dispersive spectrometer (SEM-EDS) analyses, in order to shed light on the soda-ash activation of boron within ludwigite ore. Thermodynamics of Na₂CO₃-MgSiO₃-Mg₂SiO₄-Mg₂B₂O₅ via FactSage show that the formation of Na₂MgSiO₄ was preferential for the reaction between Na₂CO₃ and MgSiO₃/Mg₂SiO₄. While, regarding the reaction between Na₂CO₃ and Mg₂B₂O₅, the formation of NaBO₂ was foremost. Raising temperature was beneficial for the soda-ash roasting of lizardite and szaibelyite. At a temperature lower than the melting of sodium carbonate (851 °C), the soda-ash roasting of szaibelyite was faster than that of lizardite. Moreover, the melting of sodium carbonate accelerated the reaction between lizardite with sodium carbonate. Full article

(This article belongs to the Special Issue Cleaner Production in Mineral Processing)

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14 pages, 5738 KiB

Open AccessArticle

A Clean Process to Prepare High-Quality Acid-Soluble Titanium Slag from Titanium Middling Ore

by Jiqing Han, Jing Zhang, Wei Feng, Xiao Chen, Li Zhang and Ganfeng Tu

Minerals 2019, 9(8), 460; https://doi.org/10.3390/min9080460 - 27 Jul 2019

Cited by 7 | Viewed by 2503

Abstract

A direct reduction-magnetic separation-alkali leaching-dilute acid washing method was proposed to prepare high-quality acid-soluble titanium slag (HQASTS) from titanium middling ore. The relevant potential pH diagrams were built, and the analysis results showed that the pH values for alkali leaching and dilute acid [...] Read more.

A direct reduction-magnetic separation-alkali leaching-dilute acid washing method was proposed to prepare high-quality acid-soluble titanium slag (HQASTS) from titanium middling ore. The relevant potential pH diagrams were built, and the analysis results showed that the pH values for alkali leaching and dilute acid washing should be higher than 13.50 and lower than 1.00, respectively. Increasing temperature was beneficial to alkali leaching but not to dilute acid washing. The effects of operating parameters on the TiO₂ content and impurity oxides extraction ratios of titanium slag were investigated, and the optimal experimental conditions were obtained. The HQASTS was obtained with TiO₂ and Fe₂O₃ content of 75.37 wt % and 0.96 wt %, respectively, under the above conditions. Furthermore, the leaching mechanism was studied by chemical analysis and X-ray diffraction (XRD) technology, and it was found that the alkali leaching-dilute acid washing process presented in this work could avoid the encapsulation of the unreacted anorthite by the calcium aluminum spinel generated in alkali leaching. Full article

(This article belongs to the Special Issue Cleaner Production in Mineral Processing)

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