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Minerals
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Interactions of Chemical Reagents with Clay Minerals
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Interactions of Chemical Reagents with Clay Minerals

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Processing and Extractive Metallurgy".

Deadline for manuscript submissions: closed (25 January 2021) | Viewed by 14144

Special Issue Editor

Dr. Ricardo Jeldres

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Guest Editor
Departamento de Ingeniería Química y Procesos de Minerales, Universidad de Antofagasta, Antofagasta, Chile
Interests: interest in population balance modelling of flocculation processes, thickening, leaching and flotation operations, and rheological studies, in particular related to the impact of organic reagents, nanoparticles, and liquor ionic composition on interfacial processes
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The presence of complex gangue like phyllosilicates is increasingly challenging for the mining industry. Clays negatively impact the different stages of mineral processing, including leaching, froth flotation, comminution, solid-liquid separation, tailings handling and storage. Generally, clays are associated with lower recovery of valuable minerals in flotation and contamination of their concentrate, reduction of the permeability of heap leachings, increase of rheological properties of slurries, low settling rates in thickening operations, etc. Each of these stages involves specific chemical reagents that largely determine the efficiency of the processes, and are decisive in economic, environmental and social matters.

In this special issue, we are interested in improving the understanding of the interactions between the surface of clays with the various chemical reagents that are applied in the mining industry, including collectors, frothers, pH modifiers, polyelectrolytes, coagulants, rheological modifiers, dispersants, surfactants, etc.

Dr. Ricardo Jeldres
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • clays
  • chemical reagents
  • froth flotation
  • tailings handling
  • rheology
  • tailings storage
  • heap leaching

Published Papers (4 papers)

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Research

16 pages, 20825 KiB  
Article
A Criterion for Estimating the Strength of Flocculated Aggregates in Salt Solutions
by Matías Jeldres, Luis Ayala, Pedro Robles, Edelmira Gálvez, Williams H. Leiva, Pedro G. Toledo and Ricardo I. Jeldres
Minerals 2021, 11(7), 713; https://doi.org/10.3390/min11070713 - 1 Jul 2021
Cited by 1 | Viewed by 1846
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Interactions of Chemical Reagents with Clay Minerals)
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24 pages, 6135 KiB  
Article
Flocculation of Clay Suspensions by Anionic and Cationic Polyelectrolytes: A Systematic Analysis
by Ahmad Shakeel, Zeinab Safar, Maria Ibanez, Leon van Paassen and Claire Chassagne
Minerals 2020, 10(11), 999; https://doi.org/10.3390/min10110999 - 10 Nov 2020
Cited by 24 | Viewed by 6021
Abstract
The characteristics of clayey suspensions, majorly composed of quartz microparticles, in the presence of anionic and cationic polyelectrolytes were investigated using different techniques. A wide range of clay concentrations was used, i.e., from 0.07 to 1000 g/L for different experimental techniques, based on [...] Read more.
The characteristics of clayey suspensions, majorly composed of quartz microparticles, in the presence of anionic and cationic polyelectrolytes were investigated using different techniques. A wide range of clay concentrations was used, i.e., from 0.07 to 1000 g/L for different experimental techniques, based on the fact that the clay concentration possible to analyze with selected experimental methods was significantly different. The optimum flocculant to clay ratio was defined as the ratio that gives the fastest initial floc growth by static light scattering or fastest initial settling velocity by settling column experiments. In case of anionic polyelectrolyte, it was observed that the optimum flocculant dose depends on the amount of cations present in the system. For suspensions made with demi-water, a lower optimum flocculant dose (<1 mg/g) than for suspensions prepared in tap water (2.28 mg/g) was observed. At these lower salinities, the supernatant remained turbid in all the experiments and was, therefore, not a good measure for optimal anionic based flocculation. The equilibrium floc size at a given shear rate was found to be independent on the shear history of the floc and only dependent on the current applied shear. This was confirmed by both light scattering and rheological analysis. In case of cationic polyelectrolyte, the optimum flocculant ratio (5–6 mg/g) corresponded to the ratio that gives the lowest electrophoretic mobility for each clay concentration and to the ratio that gives the fastest settling velocity for the highest clay concentrations (12–15 g/L), where static light scattering measurements were not possible. All investigation techniques, therefore, proved to be good indicators for predicting the optimum flocculant to clay ratio. For the lowest concentrations (1.75–8.7 g/L) studied by settling column measurements, the optimum flocculant ratio was observed to increase with decreasing clay concentration, for fixed mixing conditions. The optimum flocculant to clay ratio was not always corresponding to the clearest supernatant and the size of flocs at optimum dosage was dependent on the mixing efficiency. The equilibrium floc size at a given shear rate was found to be dependent on the shear history of the floc and the current applied shear. This was confirmed by both light scattering and rheological analysis. Full article
(This article belongs to the Special Issue Interactions of Chemical Reagents with Clay Minerals)
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12 pages, 17318 KiB  
Article
Molybdenite Flotation in the Presence of a Polyacrylamide of Low Anionicity Subjected to Different Conditions of Mechanical Shearing
by Darwin Estrada, Luver Echeverry, Andres Ramirez and Leopoldo Gutierrez
Minerals 2020, 10(10), 895; https://doi.org/10.3390/min10100895 - 9 Oct 2020
Cited by 7 | Viewed by 3057
Abstract
Polyacrylamides (PAM) are used as flocculants in the copper-molybdenum mining industry to improve the settling rate of flotation tailings. These types of reagents are recirculated to flotation in the water that is recovered from the thickeners, and as a result of this practice [...] Read more.
Polyacrylamides (PAM) are used as flocculants in the copper-molybdenum mining industry to improve the settling rate of flotation tailings. These types of reagents are recirculated to flotation in the water that is recovered from the thickeners, and as a result of this practice they can cause depression of flotation of some important minerals such as molybdenite. The objective of this work was to study the effect of a PAM of 11.9% of degree of anionicity on the flotation of molybdenite. The effect of the anionic PAM on molybdenite flotation was studied under different levels (three) of flocculant mechanical shearing. The flotation data was discussed along with intrinsic viscosity, adsorption, induction time, and electrophoretic mobility measurements. It was found that the non-sheared PAM (NS–PAM) had the strongest depressing effect on molybdenite flotation, followed by the moderately sheared PAM (MS–PAM). The depressing effect of the strongly sheared PAM (SS–PAM) was negligible. The flotation data correlated with the induction time measurements that showed that molybdenite became more hydrophilic in the presence of the NS–PAM. The SS–PAM has no effect on the induction times. Further work is ongoing to understand the effect of PAM on molybdenite flotation in the presence of clay minerals and different aqueous media. Full article
(This article belongs to the Special Issue Interactions of Chemical Reagents with Clay Minerals)
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14 pages, 4100 KiB  
Article
Permeability and Adsorption–Desorption Behavior of Rare Earth in Laboratory Leaching Tests
by Xiaojun Wang, Hao Wang, Can Sui, Lingbo Zhou, Xiao Feng, Chengguang Huang, Kui Zhao, Wen Zhong and Kaijian Hu
Minerals 2020, 10(10), 889; https://doi.org/10.3390/min10100889 - 7 Oct 2020
Cited by 13 | Viewed by 2676
Abstract
In order to investigate the influence of the ion exchange process on the permeability of rare earth ore bodies in the leaching process, a laboratory-scale comparative experiment with ammonium sulfate solution and deionized (DI) water as leaching solutions is conducted. Compared with the [...] Read more.
In order to investigate the influence of the ion exchange process on the permeability of rare earth ore bodies in the leaching process, a laboratory-scale comparative experiment with ammonium sulfate solution and deionized (DI) water as leaching solutions is conducted. Compared with the DI water leaching test, the permeability coefficient of the rare earth ore sample leached by the ammonium sulfate solution gradually decreases at the beginning and then increases with the completion of leaching. The physical and morphological evolutions of rare earth ore samples in this comparative experiment are also monitored by nuclear magnetic resonance and scanning electron microscopy. It is concluded that the change in the permeability coefficient arises from the adsorption–desorption of a large number of clay microparticles, resulting in a dynamic evolution of pore structures. Further mechanism analysis suggests that the change in internal ionic strength caused by ion exchange and leaching solution seepage promotes the adsorption–desorption behavior of clay microparticles. Full article
(This article belongs to the Special Issue Interactions of Chemical Reagents with Clay Minerals)
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