Editorial

2 pages, 180 KiB

Open AccessEditorial

Editorial for Special Issue “Gravity Concentration”

by Carlos Hoffmann Sampaio and Weslei Monteiro Ambrós

Minerals 2021, 11(12), 1355; https://0-doi-org.brum.beds.ac.uk/10.3390/min11121355 - 30 Nov 2021

Cited by 1 | Viewed by 1339

Gravity concentration is the process by which particles of different densities, sizes, and shapes separate from each other when under the action of gravity or centrifugal forces [...] Full article

(This article belongs to the Special Issue Gravity Concentration)

Research

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16 pages, 10422 KiB

Open AccessArticle

High Concentration Fine Particle Separation Performance in Hydrocyclones

by Yuekan Zhang, Meng Yang, Lanyue Jiang, Hui Wang, Jinguang Xu and Junru Yang

Minerals 2021, 11(3), 307; https://0-doi-org.brum.beds.ac.uk/10.3390/min11030307 - 16 Mar 2021

Cited by 12 | Viewed by 3680

Abstract

The vast majority of current research on hydrocyclone field centrifugal separation focuses on low concentration fluids having volume fraction less than 3%. For high-concentration fluids having volume fractions greater than 10%, which are often encountered in engineering, the law governing particle motion and [...] Read more.

The vast majority of current research on hydrocyclone field centrifugal separation focuses on low concentration fluids having volume fraction less than 3%. For high-concentration fluids having volume fractions greater than 10%, which are often encountered in engineering, the law governing particle motion and the classification mechanism are still unclear. In order to gain insights into the interaction between fine particles in the high concentration hydrocyclone field and to improve the hydrocyclone separation performance of these particles, a Dense Discrete Phase Model (DDPM) of the Euler-Eulerian method under the Ansys Fluent 14.5 software was employed. Numerical simulations were carried out to study the characteristics of the hydrocyclone field of dense particles and the influence of parameters, such as the diameter of the overflow outlet, diameter of the underflow outlet, and material concentration, on separation performance. The trajectories and separation efficiencies of two kinds of fine particles with different densities and six different particle sizes at high concentration were obtained. The results show that for the hydrocyclone classification of high-concentration fine particles, particles with large density and small particle size are more likely to enter the internal cyclone and discharge from the overflow. Particles with small density and large particle size are more likely to enter the external cyclone and discharge from the underflow. The research results of this topic could provide a feasible reference and theoretical basis for the centrifugal separation of high-concentration fine particle fluid. Full article

(This article belongs to the Special Issue Gravity Concentration)

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19 pages, 11338 KiB

Open AccessArticle

Production of Vanadium Concentrate from a Small-Scale Lead Vanadate Deposit by Gravity Concentration: A Pilot Plant Study

by Ivan Silin, Devrim Gürsel, Dario Kremer, Klaus M. Hahn and Hermann Wotruba

Minerals 2020, 10(11), 957; https://0-doi-org.brum.beds.ac.uk/10.3390/min10110957 - 27 Oct 2020

Cited by 5 | Viewed by 3667

Abstract

The renewable energy revolution calls for high-performing materials and makes metallic compounds like lithium, cobalt, nickel and vanadium more and more critical. Innovations contribute to inventions and developments like vanadium redox flow batteries for large-scale energy storage systems with numerous technological advantages. Potential [...] Read more.

The renewable energy revolution calls for high-performing materials and makes metallic compounds like lithium, cobalt, nickel and vanadium more and more critical. Innovations contribute to inventions and developments like vanadium redox flow batteries for large-scale energy storage systems with numerous technological advantages. Potential shortages of vanadium and its sources will contribute to turbulence in vanadium pricing. Nowadays, main sources and production sites of vanadium are located in Russia, China and South Africa. About 85% of vanadium applications are ferroalloys and high-performance alloys, which make production and price of vanadium dependent on the iron ore market. Partial covering of a potential vanadium demand may be achieved by an exploitation of lead vanadate ore deposits as alternative vanadium source. In the present work, the processing of a lead vanadate ore, mainly containing vanadinite and descloizite was investigated. Based on ore characterizations and preliminary beneficiation tests, a flowsheet was developed to design a small-scale processing plant, including comminution, dewatering and gravity separation. Preliminary laboratory tests and samples from the small-scale processing plant show promising results for the recovery of vanadium in a lead vanadate concentrate with a grade of 12 to 16% V₂O₅ and a recovery of 68 to 75%. Full article

(This article belongs to the Special Issue Gravity Concentration)

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13 pages, 1393 KiB

Open AccessArticle

Destoning the Moatize Coal Seam, Mozambique, by Dry Jigging

by Carlos Hoffmann Sampaio, Weslei Monteiro Ambrós, Bogdan Cazacliu, Josep Oliva Moncunill, David Selemane José, Gerson Luis Miltzarek, Irineu Antônio Schadach de Brum, Carlos Otávio Petter, Eunírio Zanetti Fernandes and Luis Felipe Silva Oliveira

Minerals 2020, 10(9), 771; https://0-doi-org.brum.beds.ac.uk/10.3390/min10090771 - 31 Aug 2020

Cited by 6 | Viewed by 3578

Abstract

This paper proposes pre-beneficiation studies by air jigs of the coal layers from a Moatize coal deposit. Pre-beneficiation, also called destoning, removes tailings before the beneficiation plant. The air jigs operate in the same granulometric size range as the heavy-media cyclones (HMCs) that [...] Read more.

This paper proposes pre-beneficiation studies by air jigs of the coal layers from a Moatize coal deposit. Pre-beneficiation, also called destoning, removes tailings before the beneficiation plant. The air jigs operate in the same granulometric size range as the heavy-media cyclones (HMCs) that are installed in the preparation plant. With the destoning, the heavy-media circuit operates with a lower coal feed and higher organic matter contents, increasing its cutting efficiency and lowering operational costs. The use of air jigs reduces the total water consumption in the plant, which is especially important for the region where the plant is installed, as water is particularly scarce. Four coal layers of the Moatize coal deposit were studied, which are currently exploited in the mine. As main results of the study, it is possible to say that the concentration of lights (feed of the preparation plant) and heavies (waste fraction) in air jigs can be carried out with reasonable efficiencies for all coal layers studied, making air jigs a feasible option for coal destoning. Full article

(This article belongs to the Special Issue Gravity Concentration)

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10 pages, 1697 KiB

Open AccessArticle

Recovery of Ultra-Fine Tungsten and Tin from Slimes Using Large-Scale SLon-2400 Centrifugal Separator

by Tao Xiong, Xiangjun Ren, Meifang Xie, Yuhuan Rao, Yongjun Peng and Luzheng Chen

Minerals 2020, 10(8), 694; https://0-doi-org.brum.beds.ac.uk/10.3390/min10080694 - 05 Aug 2020

Cited by 4 | Viewed by 2590

Abstract

China is very rich in tungsten and tin resources, but most of them are finely disseminated with gangues, and thus, fine grinding is required for effective separation, which results in the abundant production of ultra-fine tungsten and tin values into slimes and tailings. [...] Read more.

China is very rich in tungsten and tin resources, but most of them are finely disseminated with gangues, and thus, fine grinding is required for effective separation, which results in the abundant production of ultra-fine tungsten and tin values into slimes and tailings. The SLon centrifugal separator is highly effective in recovering ultra-fine heavy particles, because it operates on the centrifugal acceleration of particles in the flowing film of a few millimeters thick. The recovery of ultra-fine tungsten minerals from a slime assaying 0.22% WO₃, in which 81.85% distributed in −40 µm fraction, was investigated using large-scale SLon-2400 centrifugal separator. Under optimized operating conditions, it produced a primary tungsten concentrate assaying 1.65% WO₃ at a high recovery of 77.83%. Moreover, it produced a primary tin concentrate assaying 1.56% Sn at a high recovery of 79.85% from a tin slime assaying 0.27% Sn, in which 74.78% Sn was distributed in −40 µm fraction; then, followed by the flotation cleaning process, a final tin concentrate assaying 16.23% Sn with 66.7% recovery was produced. It was particularly noted that in this large-scale centrifugal separator, the three-conical separation drum stuck with abrasion-resistant ceramic slices on its inner surface played a key role for achieving high constant separation performance. It was concluded that the SLon centrifugal separator has important application prospects for high-efficient recovery of ultra-fine heavy minerals from slimes and tailings. Full article

(This article belongs to the Special Issue Gravity Concentration)

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20 pages, 4428 KiB

Open AccessArticle

Characterisation and Modelling of Gravity Pre-Concentration Amenability Using LST Fluidisation in a REFLUX^TM Classifier

by Callan Lowes, James Zhou, Teresa McGrath, Jacques Eksteen and Kevin Galvin

Minerals 2020, 10(6), 545; https://0-doi-org.brum.beds.ac.uk/10.3390/min10060545 - 16 Jun 2020

Cited by 4 | Viewed by 2770

Abstract

Samples of the feed, underflow and overflow from water-based separations conducted using a continuous REFLUX^TM Classifier involving inclined channels with a 3 mm spacing have been fractionated. Another REFLUX^TM Classifier operating in a semi-batch configuration using a dense fluidising medium of [...] Read more.

Samples of the feed, underflow and overflow from water-based separations conducted using a continuous REFLUX^TM Classifier involving inclined channels with a 3 mm spacing have been fractionated. Another REFLUX^TM Classifier operating in a semi-batch configuration using a dense fluidising medium of lithium heteropolytungstates (LST) was used to determine the density distributions of the three streams. The partition surface of the separator was quantified, and the technique was validated against sink/float data for a −300 + 38 µm chromite ore separation. It was found that the LST flow fractionation determined the D₅₀ with remarkable accuracy across the entire size range, with the Ep values also very good above 75 µm. For water-based continuous separations involving a gold ore covering the size range −1.0 + 0.090 mm, the D₅₀ varied with particle size to the power −0.22 and the Ep remained relatively constant at approximately 170 kg/m³ for each of the narrow particle size ranges. These results were consistent with the partition surface validated based on the much finer size range of the higher density chromite ore. The performance of the continuous system was then modelled, with the results shown to agree well with separations conducted on the feed. This approach has been developed as an alternative to using the sink/float test, thus offering a new option with both a lower cost and minimal health and environmental risk. The findings from this study can in turn be used to assess the amenability of a given ore to gravity pre-concentration. Full article

(This article belongs to the Special Issue Gravity Concentration)

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Review

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49 pages, 16933 KiB

Open AccessEditor’s ChoiceReview

Gravity Concentration in Artisanal Gold Mining

by Marcello M. Veiga and Aaron J. Gunson

Minerals 2020, 10(11), 1026; https://0-doi-org.brum.beds.ac.uk/10.3390/min10111026 - 18 Nov 2020

Cited by 33 | Viewed by 16161

Abstract

Worldwide there are over 43 million artisanal miners in virtually all developing countries extracting at least 30 different minerals. Gold, due to its increasing value, is the main mineral extracted by at least half of these miners. The large majority use amalgamation either [...] Read more.

Worldwide there are over 43 million artisanal miners in virtually all developing countries extracting at least 30 different minerals. Gold, due to its increasing value, is the main mineral extracted by at least half of these miners. The large majority use amalgamation either as the final process to extract gold from gravity concentrates or from the whole ore. This latter method has been causing large losses of mercury to the environment and the most relevant world’s mercury pollution. For years, international agencies and researchers have been promoting gravity concentration methods as a way to eventually avoid the use of mercury or to reduce the mass of material to be amalgamated. This article reviews typical gravity concentration methods used by artisanal miners in developing countries, based on numerous field trips of the authors to more than 35 countries where artisanal gold mining is common. Full article

(This article belongs to the Special Issue Gravity Concentration)

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31 pages, 5920 KiB

Open AccessReview

Jigging: A Review of Fundamentals and Future Directions

by Weslei M. Ambrós

Minerals 2020, 10(11), 998; https://0-doi-org.brum.beds.ac.uk/10.3390/min10110998 - 10 Nov 2020

Cited by 27 | Viewed by 15302

Abstract

For centuries, jigging has been a workhorse of the mineral processing industry. Recently, it has also found its way into the recycling industry, and the increasing concerns related to water usage has led to a renewed interest in dry jigging. However, the current [...] Read more.

For centuries, jigging has been a workhorse of the mineral processing industry. Recently, it has also found its way into the recycling industry, and the increasing concerns related to water usage has led to a renewed interest in dry jigging. However, the current scenario of increasing ore complexity and the advent of smart sensor technologies, such as sensor-based sorting (SBS), has established increasingly challenging levels for traditional concentration methods, such as jigging. Against this background, the current review attempts to summarize and refresh the key aspects and concepts about jigging available in the literature. The configuration, operational features, applications, types, and theoretical models of jigging are comprehensively reviewed. Three promising paths for future research are presented: (1) using and adapting concepts from granular physics in fundamental studies about the stratification phenomena in jigs; (2) implementing advanced control functions by using machine vision and multivariate data analysis and; (3) further studies to unlock the potential of dry jigs. Pursuing these and other innovations are becoming increasingly essential to keep the role of jigging as a valuable tool in future industry. Full article

(This article belongs to the Special Issue Gravity Concentration)

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