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Dr. Ricardo I. Jeldres
Departamento de Ingeniería Química y Procesos de Minerales, Universidad de Antofagasta, Antofagasta 1270300, Chile. Researcher in Centro CRHIAM Project Anid/Fondap/15130015

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Research Keywords & Expertise

0 Nanoparticles
0 Thickening
0 Interest in population balance modelling of flocculation processes
0 Leaching and flotation operations
0 And rheological studies

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Correction
Published: 19 August 2021 in Metals
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The authors wish to make the following corrections to this paper

ACS Style

David Torres; Luís Ayala; Ricardo I. Jeldres; Eduardo Cerecedo-Sáenz; Eleazar Salinas-Rodríguez; Pedro Robles; Norman Toro. Correction: Torres et al. Leaching Chalcopyrite with High MnO2 and Chloride Concentrations. Metals 2020, 10, 107. Metals 2021, 11, 1312 .

AMA Style

David Torres, Luís Ayala, Ricardo I. Jeldres, Eduardo Cerecedo-Sáenz, Eleazar Salinas-Rodríguez, Pedro Robles, Norman Toro. Correction: Torres et al. Leaching Chalcopyrite with High MnO2 and Chloride Concentrations. Metals 2020, 10, 107. Metals. 2021; 11 (8):1312.

Chicago/Turabian Style

David Torres; Luís Ayala; Ricardo I. Jeldres; Eduardo Cerecedo-Sáenz; Eleazar Salinas-Rodríguez; Pedro Robles; Norman Toro. 2021. "Correction: Torres et al. Leaching Chalcopyrite with High MnO2 and Chloride Concentrations. Metals 2020, 10, 107." Metals 11, no. 8: 1312.

Journal article
Published: 07 July 2021 in Metals
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This research aims to analyze the impact of sodium tripolyphosphate (STPP) as a rheological modifier of concentrated kaolin slurries in seawater at pH 8, which is characteristic of copper sulfide processing operations. The dispersion phenomenon was analyzed through chord length measurements using the focused beam reflectance measurement (FBRM) technique, complementing size distributions in unweighted and square-weighted modes. The reduction of the rheological properties was significant, decreasing from 231 Pa in a reagent-free environment to 80 Pa after the application of STPP. A frequency sweep in a linear viscoelastic regime indicated that by applying a characteristic dosage of 0.53 kg/t of STPP, the pulp before yielding increases its phase angle, which increases its liquid-like character. Measurements of the chord length verified the dispersion of particles, which showed an apparent increase in the proportion of fine particles and a reduction of the coarser aggregates when STPP was applied. Measurements of the zeta potential suggested that the high anionic charge of the reagent (pentavalent) increases the electrostatic repulsions between particles, overcoming the effect of cations in seawater. The results are relevant for the mining industry, especially when the deposits have high contents of complex gangues, such as clays, that increase the rheological properties. This increases the energy costs and water consumption needed for pumping the tailings from thickeners to the tailing storages facilities. The strategies that allow for the improvement of the fluidity and deformation of the tailings generate slack in order to maximize water recovery in the thickening stages.

ACS Style

Williams Leiva; Norman Toro; Pedro Robles; Edelmira Gálvez; Ricardo Jeldres. Use of Multi-Anionic Sodium Tripolyphosphate to Enhance Dispersion of Concentrated Kaolin Slurries in Seawater. Metals 2021, 11, 1085 .

AMA Style

Williams Leiva, Norman Toro, Pedro Robles, Edelmira Gálvez, Ricardo Jeldres. Use of Multi-Anionic Sodium Tripolyphosphate to Enhance Dispersion of Concentrated Kaolin Slurries in Seawater. Metals. 2021; 11 (7):1085.

Chicago/Turabian Style

Williams Leiva; Norman Toro; Pedro Robles; Edelmira Gálvez; Ricardo Jeldres. 2021. "Use of Multi-Anionic Sodium Tripolyphosphate to Enhance Dispersion of Concentrated Kaolin Slurries in Seawater." Metals 11, no. 7: 1085.

Journal article
Published: 01 July 2021 in Minerals
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A simple criterion is proposed to quantitatively estimate the resistance of aggregates based on incremental mechanical shear disturbances. Aggregate strength can be affected by the hydrodynamic conditions under which flocculation occurs; therefore, an experimental method is standardized to determine the resistance of aggregate structures that are formed under defined conditions of salinity (NaCl 0–0.1 M), mixing time (3 min), and mean shear rate (G = 273 s−1). Kaolin particles were flocculated in saline solutions with an anionic flocculant of high molecular weight. The method involves increasing the mean shear rate (G = 0–1516 s−1). Each increment represents a new experiment that starts from the base of 273 s−1. Target aggregates are increasingly fragmented as mechanical disturbance increases. The monotonic relationship between the mean shear rate increments (ΔG) and the final size of the aggregates is used for a quantitative estimate of the resistance of the target aggregates since this resistance underlies this relationship. The evolution of aggregate size is analyzed by the Focused Beam Reflectance Measurement (FBRM) method, which may capture the chord length distribution on concentrated slurries. To estimate and compare the resistance of the target aggregates in solutions with different salinities, a pseudo-first-order model that describes the rupture degree as a function of shear rate increments obtains the characteristic shear rate. The rupture percentage is reached with considerably lower agitation increments at higher salinity than at low salinity. This criterion is expected to help improve the efficiency of solid–liquid separation processes, especially in plants operating with seawater, be it raw or partially desalinated.

ACS Style

Matías Jeldres; Luis Ayala; Pedro Robles; Edelmira Gálvez; Williams Leiva; Pedro Toledo; Ricardo Jeldres. A Criterion for Estimating the Strength of Flocculated Aggregates in Salt Solutions. Minerals 2021, 11, 713 .

AMA Style

Matías Jeldres, Luis Ayala, Pedro Robles, Edelmira Gálvez, Williams Leiva, Pedro Toledo, Ricardo Jeldres. A Criterion for Estimating the Strength of Flocculated Aggregates in Salt Solutions. Minerals. 2021; 11 (7):713.

Chicago/Turabian Style

Matías Jeldres; Luis Ayala; Pedro Robles; Edelmira Gálvez; Williams Leiva; Pedro Toledo; Ricardo Jeldres. 2021. "A Criterion for Estimating the Strength of Flocculated Aggregates in Salt Solutions." Minerals 11, no. 7: 713.

Journal article
Published: 21 June 2021 in Metals
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Molecular dynamic simulations of polyacrylic acid polyelectrolyte (PAA) analyzed its interaction with the main minerals that make up characteristic tailings of the mining industry, in this case, quartz, kaolinite, and montmorillonite. The simulations were carried out with the package Gromacs 2020.3. The interaction potentials used were General AMBER Force Field (GAFF) for PAA and CLAYFF-MOH for mineral surfaces. The SPC/E model described water molecules and Lennard-Jones 12-6 parameters adjusted for SPC/E model were used for Na+ and Cl ions. The studied systems were carried out at pH 7, obtaining stable adsorption between the PAA and the studied surfaces. Interestingly, the strongest adsorptions were for montmorillonite at both low and high salt concentrations. The effect of salinity differs according to the system, finding that it impairs the absorption of the polymer on montmorillonite surfaces. However, a saline medium favors the interaction with quartz and kaolinite. This is explained because montmorillonite has a lower surface charge density and a greater capacity to adsorb ions. This facilitated the adsorption of PAA. It was possible to identify that the main interaction by which the polymer is adsorbed is through the hydroxyl of the mineral surface and the COONa+ complexes. Molecular dynamics allows us to advance in the understanding of interactions that define the behavior of this promising reagent as an alternative for sustainable treatment of complex tailings in highly saline environments.

ACS Style

Gonzalo Quezada; Eder Piceros; Pedro Robles; Carlos Moraga; Edelmira Gálvez; Steven Nieto; Ricardo Jeldres. Polyacrylic Acid to Improve Flotation Tailings Management: Understanding the Chemical Interactions through Molecular Dynamics. Metals 2021, 11, 987 .

AMA Style

Gonzalo Quezada, Eder Piceros, Pedro Robles, Carlos Moraga, Edelmira Gálvez, Steven Nieto, Ricardo Jeldres. Polyacrylic Acid to Improve Flotation Tailings Management: Understanding the Chemical Interactions through Molecular Dynamics. Metals. 2021; 11 (6):987.

Chicago/Turabian Style

Gonzalo Quezada; Eder Piceros; Pedro Robles; Carlos Moraga; Edelmira Gálvez; Steven Nieto; Ricardo Jeldres. 2021. "Polyacrylic Acid to Improve Flotation Tailings Management: Understanding the Chemical Interactions through Molecular Dynamics." Metals 11, no. 6: 987.

Review
Published: 15 February 2021 in Hydrometallurgy
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Magnesium and magnesium-derived alloys are critical to a diverse set of industries, due to their particular physicochemical properties, including biocompatibility, low density, mechanical dampening, and hydrogen-storage capacity. Moreover, the magnesium compounds are themselves vital in agricultural, pharmaceutical, construction and broad industrial applications. Leaching is a critical step in the recovery of magnesium from magnesium-bearing ore, and the most common leaching agents are organic and inorganic acids, as well and ammonium salts, the efficacy of which depends on the mineral feed. Organic acids are used with minerals having fast leaching kinetics; these acids have less dissolving power but are more selective and are less destructive to the equipment. In contrast, inorganic acids have more dissolving power and are easier to source. However, the inorganic acids are less selective and cause more damage to equipment, as they complicate pH control. The objective of this work has been to review studies on the kinetics of magnesium mineral extraction, and the effects of critical parameters depending on the feed mineral and the reagents. Several works are presented on the leaching kinetics of natural and calcined dolomite and magnesite, and hydrated magnesium salts, as well as ferromagnesian silicates and serpentinite, which are important sources of magnesium. It has been shown that the most influential parameters in dissolving magnesium are the temperature and the reagent concentration, which have a direct effect on magnesium extraction rates. However, there is a point at which increases in these parameters result in more impurities and/or have insignificant effects on magnesium dissolution. Particle size has an inverse relationship to magnesium extraction since the area of contact with the leaching surface is greater with smaller particles. The effect of the agitation speed is insignificant with magnesite feeds, given that the process is controlled largely by surface chemical reactions, while the leaching kinetics of serpentinite is controlled by diffusion through the product layer.

ACS Style

Yessica González; Alessandro Navarra; Ricardo I. Jeldres; Norman Toro. Hydrometallurgical processing of magnesium minerals – A review. Hydrometallurgy 2021, 201, 105573 .

AMA Style

Yessica González, Alessandro Navarra, Ricardo I. Jeldres, Norman Toro. Hydrometallurgical processing of magnesium minerals – A review. Hydrometallurgy. 2021; 201 ():105573.

Chicago/Turabian Style

Yessica González; Alessandro Navarra; Ricardo I. Jeldres; Norman Toro. 2021. "Hydrometallurgical processing of magnesium minerals – A review." Hydrometallurgy 201, no. : 105573.

Journal article
Published: 11 December 2020 in Colloids and Surfaces A: Physicochemical and Engineering Aspects
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Stabilization of synthetic clay-rich tailings in seawater with sodium polyacrylate (NaPA) has been studied by measurements of yield stress, viscoelastic moduli, zeta potential, and particle chord length distribution. The tailings are kaolin-quartz and sodium montmorillonite-quartz mixtures in seawater at pH 8 at which all surfaces are anionic. The yield stress of both tailings decays exponentially with the dose of NaPA. Reducing the initial value of yield stress to a preset fraction (1-1/e) requires 52 g/ton NaPA for kaolin-quartz and 31 g/ton NaPA for montmorillonite-quartz tailing. At these dosages, in the linear viscoelastic range, both tailings respond similarly to the presence of NaPA, increasing their liquid-like character and suspension stability. The stabilizing action of NaPA is supported by a slight increase of the negative zeta potential and a clear shift of the particle size distribution to the finer sizes. The underlying stabilizing mechanism involves steric-electrostatic repulsion of the clay particles. These results suggest an alternative to improve the management of clay-rich tailings in processes that use raw seawater at natural pH.

ACS Style

Matías Jeldres; Pedro Robles; Pedro G. Toledo; Manuel Saldaña; Luciano Quezada; Ricardo I. Jeldres. Improved dispersion of clay-rich tailings in seawater using sodium polyacrylate. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2020, 612, 126015 .

AMA Style

Matías Jeldres, Pedro Robles, Pedro G. Toledo, Manuel Saldaña, Luciano Quezada, Ricardo I. Jeldres. Improved dispersion of clay-rich tailings in seawater using sodium polyacrylate. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2020; 612 ():126015.

Chicago/Turabian Style

Matías Jeldres; Pedro Robles; Pedro G. Toledo; Manuel Saldaña; Luciano Quezada; Ricardo I. Jeldres. 2020. "Improved dispersion of clay-rich tailings in seawater using sodium polyacrylate." Colloids and Surfaces A: Physicochemical and Engineering Aspects 612, no. : 126015.

Journal article
Published: 10 November 2020 in Minerals Engineering
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Mineral processing produces large volumes of dilute tailings that are flocculated and thickened, returning water to the process. The drive towards more sustainable processing has seen seawater considered to replace fresh water usage and an increased focus on how flocculation conditions can influence the fractal-like aggregates formed. The fragility of such structures and the likelihood that they change with time makes their study challenging. A synthetic tailings slurry of quartz and kaolin in seawater was flocculated at different mixing times and flocculant dosages, with aggregate size monitored over time by focused beam reflectance measurement (FBRM) and hindered settling rates determined after set reaction times. A model relating hindered settling rate to size as estimated by FBRM was used to derive an aggregate fractal dimension (Df) at each time. With flocculation at typical tailings solids concentrations rapid, aggregate breakage will normally dominate after very short reaction times. Under mild mixing conditions, settling rates are higher than expected from sizes measured in real time due to aggregate growth continuing after mixing ceases, leading to inflated Df estimates. An apparent decline in Df under more intense mixing was consistent with an increased presence of high aspect ratio (low effective porosity) aggregate fragments, supported by in situ aggregate imaging at different reaction times. In contrast, the observed trends for a reduction in Df with mixing intensity and an increase with dosage are both thought to represent the expected aggregate structure changes for the synthetic tailings. While estimating aggregate structural properties by relating FBRM sizes to settling rates can offer useful insights, it is important to recognise the aggregation state observed by FBRM under mixing applied to induce flocculation may differ from that which exists during hindered settling. Values of Df derived in this manner must therefore be viewed with caution.

ACS Style

Williams H. Leiva; Phillip D. Fawell; Christian Goñi; Norman Toro; Ricardo I. Jeldres. Temporal evolution of the structure of tailings aggregates flocculated in seawater. Minerals Engineering 2020, 160, 106708 .

AMA Style

Williams H. Leiva, Phillip D. Fawell, Christian Goñi, Norman Toro, Ricardo I. Jeldres. Temporal evolution of the structure of tailings aggregates flocculated in seawater. Minerals Engineering. 2020; 160 ():106708.

Chicago/Turabian Style

Williams H. Leiva; Phillip D. Fawell; Christian Goñi; Norman Toro; Ricardo I. Jeldres. 2020. "Temporal evolution of the structure of tailings aggregates flocculated in seawater." Minerals Engineering 160, no. : 106708.

Journal article
Published: 27 October 2020 in Metals
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Chalcocite (Cu2S) has the fastest kinetics of dissolution of Cu in chlorinated media of all copper sulfide minerals. Chalcocite has been identified as having economic interest due to its abundance, although the water necessary for its dissolution is scarce in many regions. In this work, the replacement of fresh water by sea water or by reject brine with high chloride content from desalination plants is analyzed. Additionally, the effect of adding MnO2 from available manganese nodules in vast quantities at the bottom of the sea is studied. Reject brine shows better results than sea water, and the addition of MnO2 to the brine significantly increases the kinetics of chalcocite dissolution in a short time. H2SO4 concentration is found to be irrelevant when working at high concentrations of chloride and MnO2. The best results, 71% Cu extractions in 48 h, are obtained for reject brine, 100 mg of MnO2 per 200 g of mineral and H2SO4 0.5 mol/L. The results are expected to contribute to a sustainable process of dissolution of chalcocite by using the reject brine from desalination plants.

ACS Style

David Torres; Emilio Trigueros; Pedro Robles; Williams Leiva; Ricardo Jeldres; Pedro Toledo; Norman Toro. Leaching of Pure Chalcocite with Reject Brine and MnO2 from Manganese Nodules. Metals 2020, 10, 1426 .

AMA Style

David Torres, Emilio Trigueros, Pedro Robles, Williams Leiva, Ricardo Jeldres, Pedro Toledo, Norman Toro. Leaching of Pure Chalcocite with Reject Brine and MnO2 from Manganese Nodules. Metals. 2020; 10 (11):1426.

Chicago/Turabian Style

David Torres; Emilio Trigueros; Pedro Robles; Williams Leiva; Ricardo Jeldres; Pedro Toledo; Norman Toro. 2020. "Leaching of Pure Chalcocite with Reject Brine and MnO2 from Manganese Nodules." Metals 10, no. 11: 1426.

Journal article
Published: 20 September 2020 in Colloids and Surfaces A: Physicochemical and Engineering Aspects
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The scarcity of water resources for mining activities drives the search for new low-quality water sources such as well-water and seawater. Seawater was found to be a promising alternative, but it may pose significant operational challenges, for example, when it needs to be recovered from the tailings in thickening stages for subsequent recycling. This is mainly explained by the high saline environment and colloidal magnesium precipitates that are generated at highly alkaline conditions. In this work, we use molecular dynamics (MD) simulations to understand the affinity of the flocculant with colloidal magnesium precipitates and the main minerals that make up a mining tailing such as quartz and kaolinite. The results are contrasted with the in-situ characterization of aggregates through the Focused Beam Reflectance Measurement (FBRM). Through X-ray diffraction, it was found that the magnesium precipitates are mainly composed of brucite crystals. The MD results allowed to explain the experimental results, mainly when solid magnesium precipitates appear at high pH, where the flocculant loses its effectiveness sharply. This is related to the undesired association among the flocculant with brucite. The adsorption is mainly carried out by the interaction between the deprotonated oxygen from the acrylic group of the polymer and the oxygen from the hydroxide of the brucite surface. There is also a significant contribution of hydrogen bonding between nitrogen from the acrylamide group and oxygen from the hydroxide.

ACS Style

Gonzalo R. Quezada; Matías Jeldres; Norman Toro; Pedro Robles; Pedro G. Toledo; Ricardo I. Jeldres. Understanding the flocculation mechanism of quartz and kaolinite with polyacrylamide in seawater: A molecular dynamics approach. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2020, 608, 125576 .

AMA Style

Gonzalo R. Quezada, Matías Jeldres, Norman Toro, Pedro Robles, Pedro G. Toledo, Ricardo I. Jeldres. Understanding the flocculation mechanism of quartz and kaolinite with polyacrylamide in seawater: A molecular dynamics approach. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2020; 608 ():125576.

Chicago/Turabian Style

Gonzalo R. Quezada; Matías Jeldres; Norman Toro; Pedro Robles; Pedro G. Toledo; Ricardo I. Jeldres. 2020. "Understanding the flocculation mechanism of quartz and kaolinite with polyacrylamide in seawater: A molecular dynamics approach." Colloids and Surfaces A: Physicochemical and Engineering Aspects 608, no. : 125576.

Journal article
Published: 04 September 2020 in Minerals
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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.

ACS Style

Gonzalo R. Quezada; Matías Jeldres; Pedro Robles; Norman Toro; David Torres; Ricardo I. Jeldres. Improving the Flocculation Performance of Clay-Based Tailings in Seawater: A Population Balance Modelling Approach. Minerals 2020, 10, 782 .

AMA Style

Gonzalo R. Quezada, Matías Jeldres, Pedro Robles, Norman Toro, David Torres, Ricardo I. Jeldres. Improving the Flocculation Performance of Clay-Based Tailings in Seawater: A Population Balance Modelling Approach. Minerals. 2020; 10 (9):782.

Chicago/Turabian Style

Gonzalo R. Quezada; Matías Jeldres; Pedro Robles; Norman Toro; David Torres; Ricardo I. Jeldres. 2020. "Improving the Flocculation Performance of Clay-Based Tailings in Seawater: A Population Balance Modelling Approach." Minerals 10, no. 9: 782.

Review article
Published: 05 August 2020 in Ore Geology Reviews
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Global warming is one of the most significant issues of today. Carbon dioxide is the primary contributor to climate change, and is mainly formed by the energy sector; thus, it is imperative to expand the total decarbonisation of this industry. Another global concern is the high demand and low supply of critical metals due to the constant growth of technological advances. These elements are essential for the manufacturing of advanced technology, green technology, and emerging industries. Currently, there is global tension and unrest over how the critical metals market is developing, with one example regarding China, which has an apparent monopoly on the mining, refining, and technical expertise associated with rare earth elements. China currently provides approximately 90% of the production of rare earth elements, causing conflicts with the European Union, the USA, and Japan due to their dependence on these raw materials. Another controversial case is the production of cobalt in the Democratic Republic of the Congo, which dominates in the global production (60% of the world’s production of Co). Despite this, the Democratic Republic of the Congo is one of the poorest countries in the world. The constant depletion of high-grade minerals from the Earth's surface forces the search for new alternative sources of the critical metals. The abundance of minerals within the sea is of relevance, with large deposits of marine nodules, ferromanganese crusts, and massive polymetallic sulphides. These are of great interest to the mining industry, as it is estimated that the largest reserves of various critical metals are found on the seabed, in addition to the largest reserves of cobalt, nickel, and manganese, and a considerable amount of rare earth elements. The exploitation of mineral resources from the seabed by the company Deep Sea Mining Finance Limited (DSMF) is currently being developed, which might promote the expansion of this market throughout the world. The wealth of minerals in the seabed may be a solution to the shortage of critical metals in the market, may decrease political tensions between countries worldwide, and may promote the large-scale deployment of renewable energy.

ACS Style

Norman Toro; Pedro Robles; Ricardo I. Jeldres. Seabed mineral resources, an alternative for the future of renewable energy: A critical review. Ore Geology Reviews 2020, 126, 103699 .

AMA Style

Norman Toro, Pedro Robles, Ricardo I. Jeldres. Seabed mineral resources, an alternative for the future of renewable energy: A critical review. Ore Geology Reviews. 2020; 126 ():103699.

Chicago/Turabian Style

Norman Toro; Pedro Robles; Ricardo I. Jeldres. 2020. "Seabed mineral resources, an alternative for the future of renewable energy: A critical review." Ore Geology Reviews 126, no. : 103699.

Journal article
Published: 30 July 2020 in Minerals
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The combined use of the Radial Basis Function Network (RBFN) model with pretreated seawater by biomineralization (BSw) was investigated as an approach to improve copper tailings flocculation for mining purposes. The RBFN was used to set the optimal ranges of Ca2+ and Mg2+ concentration at different Ph in artificial seawater to optimize the performance of the mine tailings sedimentation process. The RBFN was developed by considering Ca2+ and Mg2+ concentration as well as pH as input variables, and mine tailings settling rate (Sr) and residual water turbidity (T) as output variables. The optimal ranges of Ca2+ and Mg2+ concentration were found, respectively: (i) 169–338 and 0–130 mg·L−1 at pH 9.3; (ii) 0–21 and 400–741 mg·L–1 at pH 10.5; (iii) 377–418 and 703–849 mg·L−1 at pH 11.5. The settling performance predicted by the RBFN was compared with that measured in raw seawater (Sw), chemically pretreated seawater (CHSw), BSw, and tap water (Tw). The results highlighted that the RBFN model is greatly useful to predict the settling performance in CHSw. On the other hand, the highest Sr values (i.e., 5.4, 5.7, and 5.4 m·h–1) were reached independently of pH when BSw was used as a separation medium for the sedimentation process.

ACS Style

Grecia Villca; Dayana Arias; Ricardo Jeldres; Antonio Pánico; Mariella Rivas; Luis A. Cisternas. Use of Radial Basis Function Network to Predict Optimum Calcium and Magnesium Levels in Seawater and Application of Pretreated Seawater by Biomineralization as Crucial Tools to Improve Copper Tailings Flocculation. Minerals 2020, 10, 676 .

AMA Style

Grecia Villca, Dayana Arias, Ricardo Jeldres, Antonio Pánico, Mariella Rivas, Luis A. Cisternas. Use of Radial Basis Function Network to Predict Optimum Calcium and Magnesium Levels in Seawater and Application of Pretreated Seawater by Biomineralization as Crucial Tools to Improve Copper Tailings Flocculation. Minerals. 2020; 10 (8):676.

Chicago/Turabian Style

Grecia Villca; Dayana Arias; Ricardo Jeldres; Antonio Pánico; Mariella Rivas; Luis A. Cisternas. 2020. "Use of Radial Basis Function Network to Predict Optimum Calcium and Magnesium Levels in Seawater and Application of Pretreated Seawater by Biomineralization as Crucial Tools to Improve Copper Tailings Flocculation." Minerals 10, no. 8: 676.

Review
Published: 29 July 2020 in Minerals
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Given the active growth of emerging technology industries, it has become essential to have large quantities of critical metals to meet the current demand. In the Chilean mining industry, there is a depletion of high-grade mineral ores, and there is hence a need to increase production levels in the copper industry and diversify its market by extracting other elements. One of the strategies is to foster the production of lithium batteries, but the manufacture requires reserves of cobalt (Co) and manganese (Mn). Currently, Co reserves are not being exploited in Chile, and Mn production is almost negligible. This is due to the apparent shortage of high-grade ores on the land surface of the country. Given this scenario, the seabed manganese nodules are presented as a good alternative due to their high average grades of Co and Mn, which in turn would allow the growth of strategic value-added industries including lithium battery production. Chile’s current environmental regulations prevent the exploitation of marine resources. However, given technological advances worldwide, both in collection mechanisms and extractive processes, in addition to the needs generated from the future strategic plans, leads us to think about a project to exploit manganese nodules locally.

ACS Style

Norman Toro; Ricardo I. Jeldres; Javier A. Órdenes; Pedro Robles; Alessandro Navarra. Manganese Nodules in Chile, an Alternative for the Production of Co and Mn in the Future—A Review. Minerals 2020, 10, 674 .

AMA Style

Norman Toro, Ricardo I. Jeldres, Javier A. Órdenes, Pedro Robles, Alessandro Navarra. Manganese Nodules in Chile, an Alternative for the Production of Co and Mn in the Future—A Review. Minerals. 2020; 10 (8):674.

Chicago/Turabian Style

Norman Toro; Ricardo I. Jeldres; Javier A. Órdenes; Pedro Robles; Alessandro Navarra. 2020. "Manganese Nodules in Chile, an Alternative for the Production of Co and Mn in the Future—A Review." Minerals 10, no. 8: 674.

Journal article
Published: 19 May 2020 in Metals
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Black coppers are mineraloids with a high content of Cu and Mn. These have an amorphous crystalline structure that makes them refractory to conventional leaching processes. For this reason, these mineral resources are not incorporated in industrial leaching heap processes and are taken to dumps. In the present study, an agglomerate pretreatment process incorporating NaCl is evaluated, and a curing stage, followed by acid-reducing leaching for Cu and Mn dissolution from a high-grade black copper mineral. For this, an experimental design was developed both to evaluate the impact of the dependent variables on the response, to generate analytical models that represent the copper and manganese recoveries under the set of sampled conditions. The models indicate that the curing time and the NaCl concentration have a primary effect on the recovery of both elements. In contrast, the optimization model suggests that the optimal operating levels are reached at relatively high levels of time (>130 h) and of NaCl concentration (>22 kg/t).

ACS Style

Manuel Saldaña; Edelmira Gálvez; Ricardo I. Jeldres; Catalina Díaz; Pedro Robles; Manish Kumar Sinha; Norman Toro. Optimization of Cu and Mn Dissolution from Black Coppers by Means of an Agglomerate and Curing Pretreatment. Metals 2020, 10, 657 .

AMA Style

Manuel Saldaña, Edelmira Gálvez, Ricardo I. Jeldres, Catalina Díaz, Pedro Robles, Manish Kumar Sinha, Norman Toro. Optimization of Cu and Mn Dissolution from Black Coppers by Means of an Agglomerate and Curing Pretreatment. Metals. 2020; 10 (5):657.

Chicago/Turabian Style

Manuel Saldaña; Edelmira Gálvez; Ricardo I. Jeldres; Catalina Díaz; Pedro Robles; Manish Kumar Sinha; Norman Toro. 2020. "Optimization of Cu and Mn Dissolution from Black Coppers by Means of an Agglomerate and Curing Pretreatment." Metals 10, no. 5: 657.

Journal article
Published: 11 May 2020 in Metals
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In this study, weak acid in the curing and leaching stages of copper ore was incorporated, and we analyzed its effect on the dissolution of copper and final impurities. The weak acid corresponds to a wastewater effluent from sulfuric acid plants produced in the gas treatment of copper smelting processes. This effluent is basically water with high acidity (pH-value low at 1), which contains several toxic elements and some valuable metals. The results indicated that there is no positive or negative effect on the incorporation of the weak acid in the curing stage, while the case of the leaching stage is favored. Toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) toxicity tests were performed on the solid leaching residues, determining that they accomplish the stability ranges of the impurities (Pb, Cd, Hg, Cr, Ba, Se, As, and Ag).

ACS Style

Giselle Araya; Norman Toro; Jonathan Castillo; Danny Guzmán; Alexis Guzmán; Pía Hernández; Ricardo I. Jeldres; Rossana Sepúlveda. Leaching of Oxide Copper Ores by Addition of Weak Acid from Copper Smelters. Metals 2020, 10, 627 .

AMA Style

Giselle Araya, Norman Toro, Jonathan Castillo, Danny Guzmán, Alexis Guzmán, Pía Hernández, Ricardo I. Jeldres, Rossana Sepúlveda. Leaching of Oxide Copper Ores by Addition of Weak Acid from Copper Smelters. Metals. 2020; 10 (5):627.

Chicago/Turabian Style

Giselle Araya; Norman Toro; Jonathan Castillo; Danny Guzmán; Alexis Guzmán; Pía Hernández; Ricardo I. Jeldres; Rossana Sepúlveda. 2020. "Leaching of Oxide Copper Ores by Addition of Weak Acid from Copper Smelters." Metals 10, no. 5: 627.

Journal article
Published: 06 May 2020 in Minerals Engineering
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In areas where access to water of good quality is limited, the use of seawater in mineral processing can be an option. However, the dewatering of waste tailings is adversely affected, particularly when this follows processing at higher pH. The flocculation response of a synthetic clay-based tailings in seawater to different pH conditions was examined in detail, focusing on conditions promoting precipitation of the divalent cations present. Flocculated aggregate growth and breakage during turbine mixing were monitored in-situ in terms of chord length distributions (by focused beam reflectance measurement) and aggregate image capture, with the resultant hindered settling rates also determined. It was found that flocculation in seawater was substantially impaired at pH values greater than 10.3 due to the precipitation of magnesium species. The addition of the precipitated phase to the synthetic tailings increases both the surface area exposed to flocculant and the number of particles or micro-aggregates then needing further aggregation to attain acceptable settling rates. The direct use of seawater in processing operations without resorting to full desalination does not necessarily have detrimental impacts on tailings flocculation and thickening, provided the operation is conducted at a pH that prevents the precipitation of magnesium present within the process liquors.

ACS Style

Jahir J. Ramos; Williams H. Leiva; Claudia N. Castillo; Christian F. Ihle; Phillip D. Fawell; Ricardo I. Jeldres. Seawater flocculation of clay-based mining tailings: Impact of calcium and magnesium precipitation. Minerals Engineering 2020, 154, 106417 .

AMA Style

Jahir J. Ramos, Williams H. Leiva, Claudia N. Castillo, Christian F. Ihle, Phillip D. Fawell, Ricardo I. Jeldres. Seawater flocculation of clay-based mining tailings: Impact of calcium and magnesium precipitation. Minerals Engineering. 2020; 154 ():106417.

Chicago/Turabian Style

Jahir J. Ramos; Williams H. Leiva; Claudia N. Castillo; Christian F. Ihle; Phillip D. Fawell; Ricardo I. Jeldres. 2020. "Seawater flocculation of clay-based mining tailings: Impact of calcium and magnesium precipitation." Minerals Engineering 154, no. : 106417.

Correction
Published: 14 April 2020 in Metals
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The authors wish to make the following corrections to this paper

ACS Style

David Torres; Luís Ayala; Manuel Saldaña; Manuel Cánovas; Ricardo I. Jeldres; Steven Nieto; Jonathan Castillo; Pedro Robles; Norman Toro. Correction: Torres, D. et al. Leaching Manganese Nodules in an Acid Medium and Room Temperature Comparing the Use of Different Fe Reducing Agents. Metals 2019, 9, 1316. Metals 2020, 10, 506 .

AMA Style

David Torres, Luís Ayala, Manuel Saldaña, Manuel Cánovas, Ricardo I. Jeldres, Steven Nieto, Jonathan Castillo, Pedro Robles, Norman Toro. Correction: Torres, D. et al. Leaching Manganese Nodules in an Acid Medium and Room Temperature Comparing the Use of Different Fe Reducing Agents. Metals 2019, 9, 1316. Metals. 2020; 10 (4):506.

Chicago/Turabian Style

David Torres; Luís Ayala; Manuel Saldaña; Manuel Cánovas; Ricardo I. Jeldres; Steven Nieto; Jonathan Castillo; Pedro Robles; Norman Toro. 2020. "Correction: Torres, D. et al. Leaching Manganese Nodules in an Acid Medium and Room Temperature Comparing the Use of Different Fe Reducing Agents. Metals 2019, 9, 1316." Metals 10, no. 4: 506.

Journal article
Published: 04 April 2020 in Metals
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Covellite is a secondary copper sulfide, and it is not abundant. There are few investigations on this mineral in spite of it being formed during the leaching of chalcocite or digenite; the other investigations on covellite are with the use of mineraloids, copper concentrates, and synthetic covellite. The present investigation applied the surface optimization methodology using a central composite face design to evaluate the effect of leaching time, chloride concentration, and sulfuric acid concentration on the level of copper extraction from covellite (84.3% of purity). Copper is dissolved from a sample of pure covellite without the application of temperature or pressure; the importance of its purity is that the behavior of the parameters is analyzed, isolating the impurities that affect leaching. The chloride came from NaCl, and it was effectuated in a size range from –150 to +106 μm. An ANOVA indicated that the leaching time and chloride concentration have the most significant influence, while the copper extraction was independent of sulfuric acid concentration. The experimental data were described by a highly representative quadratic model obtained by linear regression (R2 = 0.99).

ACS Style

Kevin Pérez; Norman Toro; Manuel Saldaña; Eleazar Salinas-Rodríguez; Pedro Robles; David Torres; Ricardo I. Jeldres. Statistical Study for Leaching of Covellite in a Chloride Media. Metals 2020, 10, 477 .

AMA Style

Kevin Pérez, Norman Toro, Manuel Saldaña, Eleazar Salinas-Rodríguez, Pedro Robles, David Torres, Ricardo I. Jeldres. Statistical Study for Leaching of Covellite in a Chloride Media. Metals. 2020; 10 (4):477.

Chicago/Turabian Style

Kevin Pérez; Norman Toro; Manuel Saldaña; Eleazar Salinas-Rodríguez; Pedro Robles; David Torres; Ricardo I. Jeldres. 2020. "Statistical Study for Leaching of Covellite in a Chloride Media." Metals 10, no. 4: 477.

Journal article
Published: 31 March 2020 in Minerals
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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 (Frms) 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.

ACS Style

Ricardo I. Jeldres; Matías Jeldres; Michael R. Maciver; Marek Pawlik; Pedro Robles; Norman Toro. Analysis of Kaolin Flocculation in Seawater by Optical Backscattering Measurements: Effect of Flocculant Management and Liquor Conditions. Minerals 2020, 10, 317 .

AMA Style

Ricardo I. Jeldres, Matías Jeldres, Michael R. Maciver, Marek Pawlik, Pedro Robles, Norman Toro. Analysis of Kaolin Flocculation in Seawater by Optical Backscattering Measurements: Effect of Flocculant Management and Liquor Conditions. Minerals. 2020; 10 (4):317.

Chicago/Turabian Style

Ricardo I. Jeldres; Matías Jeldres; Michael R. Maciver; Marek Pawlik; Pedro Robles; Norman Toro. 2020. "Analysis of Kaolin Flocculation in Seawater by Optical Backscattering Measurements: Effect of Flocculant Management and Liquor Conditions." Minerals 10, no. 4: 317.

Journal article
Published: 17 March 2020 in Metals
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Studying the dissolution of chalcocite allows to understand the behavior of the most abundant secondary sulfide ore in copper deposits, while digenite (Cu1.8S) and other intermediate sulfides (Cu2−xS) are often associated with chalcocite. The most common mechanism of dissolution is by two stages, and chloride ions benefit the kinetics of dissolution. In this study, a pure chalcocite mineral (99.9% according to XRD (X-Ray Diffraction) analysis) is leached in chloride media using NaCl and wastewater as the sources of chloride. Magnetic leaching tests are performed at 65, 75, and 95 °C, using a particle size between −150 and + 106 μm. Chloride concentration and leaching time are the main variables. A substantial dissolution of chalcocite was obtained with 0.5 M H2SO4, 100 g/L of chloride and a leaching time of 3 h. The apparent activation energy (Ea) derived from the slopes of the Arrhenius plots was 36 kJ/mol. The XRD analysis proves the presence of elemental sulfur (S0) as the main component in the leaching residue. No significant differences in copper extraction were detected when using 100 g/L of chloride ion or wastewater (39 g/L).

ACS Style

Kevin Pérez; Ricardo I. Jeldres; Steven Nieto; Eleazar Salinas-Rodríguez; Pedro Robles; Víctor Quezada; Juan Hernández Avila; Norman Toro. Leaching of Pure Chalcocite in a Chloride Media Using Waste Water at High Temperature. Metals 2020, 10, 384 .

AMA Style

Kevin Pérez, Ricardo I. Jeldres, Steven Nieto, Eleazar Salinas-Rodríguez, Pedro Robles, Víctor Quezada, Juan Hernández Avila, Norman Toro. Leaching of Pure Chalcocite in a Chloride Media Using Waste Water at High Temperature. Metals. 2020; 10 (3):384.

Chicago/Turabian Style

Kevin Pérez; Ricardo I. Jeldres; Steven Nieto; Eleazar Salinas-Rodríguez; Pedro Robles; Víctor Quezada; Juan Hernández Avila; Norman Toro. 2020. "Leaching of Pure Chalcocite in a Chloride Media Using Waste Water at High Temperature." Metals 10, no. 3: 384.