Special Issue "Physical Separation and Enrichment"

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

Deadline for manuscript submissions: 1 July 2019

Special Issue Editor

Guest Editor
Dr. Saeed Farrokhpay

Université de Lorraine, GeoRessources Laboratory, CNRS, CREGU, UMR 7359, 2 rue du Doyen Marcel Roubault, 54518 Vandœuvre-lès-Nancy, France
Website | E-Mail
Interests: flotation; rheology; froth stability; dispersion; clays; aggregation; nickel laterite; titania; tailings; physical separation

Special Issue Information

Dear Colleagues,

Physical separation is one the main methods of recovering valuable minerals from an ore (in addition to flotation and hydrometallurgy). Physical separation includes gravity concentration, classification techniques such as hydrocyclones and air classifiers, solid–liquid separation (e.g., thickeners and clarifiers), magnetic separation, and electronic sorting. This Special Issue will discuss the latest findings of using physical separation in mineral processing. In particular, it will target the optimisation of physical separation methods to recover strategic metals, including rare earth elements. Papers from both academia and industry are welcome.

Dr. Saeed Farrokhpay
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 papers will be 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 1400 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

  • gravity separation
  • falcon
  • hydrocyclone
  • magnetic separation
  • flotation

Published Papers (8 papers)

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Open AccessArticle
Numerical Simulation of Flow Field Characteristics and Separation Performance Test of Multi-Product Hydrocyclone
Minerals 2019, 9(5), 300; https://doi.org/10.3390/min9050300
Received: 14 April 2019 / Revised: 15 May 2019 / Accepted: 15 May 2019 / Published: 16 May 2019
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Abstract
A traditional hydrocyclone can only generate two products with different size fractions after one classification, which does not meet the fine classification requirements for narrow size fractions. In order to achieve the fine classification, a multi-product hydrocyclone with double-overflow-pipe structure was designed in [...] Read more.
A traditional hydrocyclone can only generate two products with different size fractions after one classification, which does not meet the fine classification requirements for narrow size fractions. In order to achieve the fine classification, a multi-product hydrocyclone with double-overflow-pipe structure was designed in this study. In this work, numerical simulation and experimental test methods were used to study the internal flow field characteristics and distribution characteristics of the product size fraction. The simulation results showed that in contrast with the traditional single overflow pipe, there were two turns in the internal axial velocity direction of the hydrocyclone with the double-overflow-pipe structure. Meanwhile, the influence rule of the diameter of the underflow outlet on the flow field characteristics was obtained through numerical simulation. From the test, five products with different size fractions were obtained after one classification and the influence rule of the diameter of the underflow outlet on the size fraction distribution of multi-products was also obtained. This work provides a feasible research idea for obtaining the fine classification of multiple products. Full article
(This article belongs to the Special Issue Physical Separation and Enrichment)
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Open AccessArticle
The Effect of the Characteristics of the Partition Plate Unit on the Separating Process of −6 mm Fine Coal in the Compound Dry Separator
Minerals 2019, 9(4), 215; https://doi.org/10.3390/min9040215
Received: 15 January 2019 / Revised: 24 March 2019 / Accepted: 30 March 2019 / Published: 4 April 2019
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Abstract
Although compound dry separation technology has been applied to industrial applications for +6 mm size fraction of coal separation, the technology has not been widely applied in the separation of fine coal (−6 mm). In this study, the effect of the partition plate [...] Read more.
Although compound dry separation technology has been applied to industrial applications for +6 mm size fraction of coal separation, the technology has not been widely applied in the separation of fine coal (−6 mm). In this study, the effect of the partition plate unit characteristics on both the average density of particles in the bed uniformly and the final separation results in a fine coal separation process were studied. According to the results, the standard deviations of the corresponding density distribution were 0.08, 0.14, and 0.07 when the height of the partition plate was 2.5 cm, the partition plate angle was 35°, and the distance from the apex of partition plate on the backplane, was 12 cm, respectively, which were the lowest values at the same level. These results showed that the average density of particles in the bed was uniformly, and its corresponding density distribution contour map was more regular. When the amplitude was 2.8 mm, the frequency was 29 Hz, the height of the partition plate was 2.5 cm, the partition plate angle was 35°, and the distance from the apex of the partition plate to the backplane was 12 cm; as a result, the E value was 0.115 g/cm3, the yield of the concentrate was 69.24%, the ash content was 12.52%, and the separation effect was better. The characteristics of the partition plate unit have an important effect on the separating process of −6 mm fine coal in the compound dry separator. Full article
(This article belongs to the Special Issue Physical Separation and Enrichment)
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Open AccessArticle
The Effect of Inlet Velocity on the Separation Performance of a Two-Stage Hydrocyclone
Minerals 2019, 9(4), 209; https://doi.org/10.3390/min9040209
Received: 28 February 2019 / Revised: 23 March 2019 / Accepted: 26 March 2019 / Published: 30 March 2019
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Abstract
The “entrainment of coarse particles in overflow” and the “entrainment of fine particles in underflow” are two inevitable phenomena in the hydrocyclone separation process, which can result in a wide product size distribution that does not meet the requirement of a precise classification. [...] Read more.
The “entrainment of coarse particles in overflow” and the “entrainment of fine particles in underflow” are two inevitable phenomena in the hydrocyclone separation process, which can result in a wide product size distribution that does not meet the requirement of a precise classification. Hence, this study proposed a two-stage (TS) hydrocyclone, and the effects of the inlet velocity on the TS hydrocyclone were investigated using computational fluid dynamics (CFD). More specifically, the influences of the first-stage inlet velocity on the second-stage swirling flow field and the separation performance were studied. In addition, the particle size distribution of the product was analyzed. It was found that the first-stage overflow contained few coarse particles above 40 μm and that the second-stage underflow contained few fine particles. The second-stage underflow was free of particles smaller than 10 μm and almost free of particles smaller than 20 μm. The underflow product contained few fine particles. Moreover, the median particle size of the second-stage overflow product was similar to that of the feed. Inspired by this observation, we propose to recycle the second-stage overflow to the feed for re-classification and to use only the first-stage overflow and the second-stage underflow as products. In this way, fine particle products free of coarse particle entrainment, and coarse particle products free of fine particle entrainment can be obtained, achieving the goal of precise classification. Full article
(This article belongs to the Special Issue Physical Separation and Enrichment)
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Open AccessArticle
Scrubbing and Inhibiting Coagulation Effect on the Purification of Natural Powder Quartz
Minerals 2019, 9(3), 140; https://doi.org/10.3390/min9030140
Received: 27 January 2019 / Revised: 19 February 2019 / Accepted: 19 February 2019 / Published: 26 February 2019
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Abstract
The low removal efficiency of fine clay impurities in natural powder quartz (NPQ) is the main problem that affects the practical utilization of this natural resource. In this work, detailed characterizations of NPQ and clay impurities in NPQ were analyzed by SEM-EDS, mineral [...] Read more.
The low removal efficiency of fine clay impurities in natural powder quartz (NPQ) is the main problem that affects the practical utilization of this natural resource. In this work, detailed characterizations of NPQ and clay impurities in NPQ were analyzed by SEM-EDS, mineral liberation analysis (MLA) and impurities distribution analysis. A combined physical purification process, including sieving, scrubbing and centrifugation, was applied to remove the clay impurities. It was observed that the fine clay impurities adhering on quartz surface were effectively liberated by scrubbing, and the content of Fe2O3 and Al2O3 in the concentrate decreased from 0.48% and 0.40% to less than 0.01% and 0.02% at pH 9.3 or when the dosage of sodium hexametaphosphate (SHMP) was 1 × 103 g/t. The coagulation interaction between quartz and impurities including hematite and orthoclase were analyzed based on the classical Deyaguin-Landau-Verwey-Overbeek (DLVO) theory. The results indicated that the main coagulation affecting the separation efficiency was the heterocoagulation between quartz and impurities and homocoagulation among hematite particles. Furthermore, adding regulators such as sodium hydroxide (NaOH) or SHMP could significantly decrease the zeta potential of minerals and thus increase the total interaction energy (VT), which could effectively improve the dispersion of these fine impurity particles, and consequently improve the removal efficiency of impurities. Reverse increase of the zeta potential of minerals in strongly alkaline solutions or excessive SHMP were detected, which was likely the main factor limiting the further improvement of the purification efficiency. Full article
(This article belongs to the Special Issue Physical Separation and Enrichment)
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Open AccessArticle
The Study on Numerical Simulation and Experiments of Four Product Hydrocyclone with Double Vortex Finders
Minerals 2019, 9(1), 23; https://doi.org/10.3390/min9010023
Received: 14 November 2018 / Revised: 16 December 2018 / Accepted: 24 December 2018 / Published: 30 December 2018
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Abstract
A hydrocyclone is an instrument that can effectively separate multi-phase mixtures of particles with different densities or sizes based on centrifugal sedimentation principles. However, conventional hydrocyclones lead to two products only, resulting in an over-wide particle size range that does not meet the [...] Read more.
A hydrocyclone is an instrument that can effectively separate multi-phase mixtures of particles with different densities or sizes based on centrifugal sedimentation principles. However, conventional hydrocyclones lead to two products only, resulting in an over-wide particle size range that does not meet the requirements of subsequent operations. In this article, a two-stage series, a four product hydrocyclone is proposed. The first stage hydrocyclone is designed to be a coaxial double overflow pipe: under the effect of separation, fine particles are discharged from the internal overflow pipe, while medium-size particles are discharged from external overflow pipe before entering the second stage hydrocyclone for fine sedimentation. In other words, one-stage grading leads to four products, including the first stage underflow, the first stage overflow, the second stage underflow, and the second stage overflow. The effects of structural parameters and operational parameters on flow field distribution in hydrocyclone were investigated via a study of flow field distribution in multi-product hydrocyclones using numerical simulations. The application of four product hydrocyclone in iron recovery shows that the grade and recovery of iron concentrate exceed 65.08% and 86.14%, respectively. This study provides references for understanding the flow field distribution in hydrocyclones and development of multi-product grading instrument in terms of both theory and industrial applications. Full article
(This article belongs to the Special Issue Physical Separation and Enrichment)
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Open AccessArticle
The Process of the Intensification of Coal Fly Ash Flotation Using a Stirred Tank
Minerals 2018, 8(12), 597; https://doi.org/10.3390/min8120597
Received: 14 November 2018 / Revised: 13 December 2018 / Accepted: 14 December 2018 / Published: 17 December 2018
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Abstract
Pulp preconditioning using a stirred tank as a pretreatment process is vital to the flotation system, which can be used to improve the flotation efficiency of mineral particles. The kinetic energy that is dissipated in the stirred tank could strengthen the interaction process [...] Read more.
Pulp preconditioning using a stirred tank as a pretreatment process is vital to the flotation system, which can be used to improve the flotation efficiency of mineral particles. The kinetic energy that is dissipated in the stirred tank could strengthen the interaction process between mineral particles and flotation reagents to improve the flotation efficiency in the presence of the preconditioning. In this paper, the effect of the conditioning speed on the coal fly ash flotation was investigated using numerical simulations and conditioning-flotation tests. The large eddy simulation coupled with the Smagorinsky-Lilly subgrid model was employed to simulate the turbulence flow field in the stirred tank, which was equipped with a six blade Rushton turbine. The impeller rotation was modelled using the sliding mesh. The simulation results showed that the large eddy simulation (LES) well matched the previous experimental data. The turbulence characteristics, such as the mean velocity, turbulent kinetic energy, power consumption and instantaneous structures of trailing vortices were analysed in detail. The turbulent length scale (η) decreased as the rotation speed increased, and the minimum value of η was almost unchanged when the rotation speed was more than 1200 rpm. The conditioning-flotation tests of coal fly ash were conducted using different conditioning speeds. The results showed that the removal of unburned carbon was greatly improved due to the strengthened turbulence in the stirred tank, and the optimal results were obtained with an LOI of 3.32%, a yield of 78.69% and an RUC of 80.89% when the conditioning speed was 1200 rpm. Full article
(This article belongs to the Special Issue Physical Separation and Enrichment)
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Open AccessCase Report
Heavy Mineral Sands in Brazil: Deposits, Characteristics, and Extraction Potential of Selected Areas
Minerals 2019, 9(3), 176; https://doi.org/10.3390/min9030176
Received: 15 January 2019 / Revised: 21 February 2019 / Accepted: 6 March 2019 / Published: 13 March 2019
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Abstract
In Brazil, heavy mineral sand deposits are still barely exploited, despite some references to Brazilian reserves and ilmenite concentrate production. The goal of this project is to characterize and investigate the potential recovery of heavy minerals from selected Brazilian placer occurrences. Two areas [...] Read more.
In Brazil, heavy mineral sand deposits are still barely exploited, despite some references to Brazilian reserves and ilmenite concentrate production. The goal of this project is to characterize and investigate the potential recovery of heavy minerals from selected Brazilian placer occurrences. Two areas of the coastal region were chosen, in Piaui state and in Bahia Provinces. In all samples, the heavy minerals of interest (ilmenite, monazite, rutile, and zircon) were identified by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques and also quantified by X-ray fluorescence spectrometry (XRF) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The total heavy minerals (THM) in the Piaui samples were 6.45% and 10.14% THM, while the figure for the Bahia sample was 3.4% THM. The recovery test of the Bahia sample, using only physical separation equipment such as a shaking table and magnetic separator, showed valuable metallurgical recoveries at around or greater than 70% for each stage, and the final concentrate of pure ilmenite was composed of up to 60.0% titanium dioxide after the differential magnetic separation. Another aim is to compile accessible information about Brazilian heavy mineral main deposits complemented with a short economic overview. Full article
(This article belongs to the Special Issue Physical Separation and Enrichment)
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Open AccessTechnical Note
Separation of Monazite from Placer Deposit by Magnetic Separation
Minerals 2019, 9(3), 149; https://doi.org/10.3390/min9030149
Received: 23 January 2019 / Revised: 19 February 2019 / Accepted: 19 February 2019 / Published: 28 February 2019
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Abstract
In this study, mineralogical analysis and beneficiation experiments were conducted using a placer deposit of North Korea, on which limited information was available, to confirm the feasibility of development. Rare earth elements (REEs) have vital applications in modern technology and are growing in [...] Read more.
In this study, mineralogical analysis and beneficiation experiments were conducted using a placer deposit of North Korea, on which limited information was available, to confirm the feasibility of development. Rare earth elements (REEs) have vital applications in modern technology and are growing in importance in the fourth industrial revolution. However, the price of REEs is unstable due to the imbalance between supply and demand, and tremendous efforts are being made to produce REEs sustainably. One of them is the evaluation of new rare earth mines and the verification of their feasibility. As a result of a mineralogical analysis, in this placer deposit, monazite and some amount of xenotime were the main REE-bearing minerals. Besides these minerals, ilmenite and zircon were the target minerals to be concentrated. Using a magnetic separation method at various magnetic intensities, paramagnetic minerals, ilmenite (0.8 T magnetic product), and monazite/xenotime (1.0–1.4 T magnetic product) were recovered selectively. Using a magnetic separation result, the beneficiation process was conducted with additional gravity separation for zircon to produce a valuable mineral concentrate. The process resulted in three kinds of mineral concentrates (ilmenite, REE-bearing mineral, and zircon). The content of ilmenite increased from 32.5% to 90.9%, and the total rare earth oxide (TREO) (%) of the REE-bearing mineral concentrates reached 45.0%. The zircon concentrate, a by-product of this process, had a Zr grade of 42.8%. Consequently, it was possible to produce concentrates by combining relatively simple separation processes compared to the conventional process for rare earth placer deposit and confirmed the possibility of mine development. Full article
(This article belongs to the Special Issue Physical Separation and Enrichment)
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