Minerals

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17 pages, 4541 KiB

Open AccessArticle

SAG Mill Grinding Media Stress Evaluation—A DEM Approach

by Murray Mulenga Bwalya, Oliver Shwarzkopf Samukute and Ngonidzashe Chimwani

Minerals 2025, 15(4), 431; https://doi.org/10.3390/min15040431 - 20 Apr 2025

Viewed by 137

The volatility of commodity prices has obligated primary metal producers to continuously seek ways of cutting costs in mineral processing units. Improving the wear characteristics and reducing the probability of grinding media fracture can potentially reduce production costs. Characterisation of the impact-loading environment [...] Read more.

The volatility of commodity prices has obligated primary metal producers to continuously seek ways of cutting costs in mineral processing units. Improving the wear characteristics and reducing the probability of grinding media fracture can potentially reduce production costs. Characterisation of the impact-loading environment and stress induced into the grinding media in SAG mills aids manufacturers in developing grinding media with superior mechanical properties. Such grinding media development emanates from a firm understanding of the SAG process supported by computer modelling tools and well-established engineering designs. The discrete element method (DEM) is a numerical technique for evaluating collision behaviour in particulate systems. This paper discusses the application of the DEM to estimate survivability and stress, induced into grinding media in a SAG mill. Full article

(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation: 3rd Edition)

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16 pages, 8803 KiB

Open AccessArticle

Time-Dependent Tap Density Modeling of Graphite Milled by Vibrating Disc Mill

by Gülşah Güven, Ugur Ulusoy, Fırat Burat, Behrad Mojtahedi and Guler Bayar

Minerals 2025, 15(4), 403; https://doi.org/10.3390/min15040403 - 11 Apr 2025

Viewed by 274

Abstract

Graphite, which is a key anode material for LIB, needs to have a high tap density (d_t) to reach a high volumetric energy density. Since d_t is directly correlated with particle size, particle size distribution, and particle shape, it [...] Read more.

Graphite, which is a key anode material for LIB, needs to have a high tap density (d_t) to reach a high volumetric energy density. Since d_t is directly correlated with particle size, particle size distribution, and particle shape, it can usually be improved by optimized grinding. So, determining the ideal grinding time by modeling the change in d_t over grinding time can yield substantial benefits like time, energy, and economy. However, the grinding time-dependent d_t modeling of graphite has never been reported before. Therefore, in this study, the relationship between the measured d_t values and grinding times of graphite particles by a vibrating disc mill (VDM) was investigated. Then, the empirical time-dependent d_t models were established with high R² values. The experimental and predicted d_t values were found to be close to each other. Among all tested fitting models, the exponential model (d_t = ae^−bt) was found to be the best-fitting model, having the highest R² and lowest error values. This approach provides guidance in the powder flow and processing of ground mineral materials, in the preparation processes of high-density graphite LIB anode material, as well as in graphite grinding in other mills in the industry, as well as in different electrode materials. Full article

(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation: 3rd Edition)

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12 pages, 1466 KiB

Open AccessArticle

Proposal of a Method for Calculating the Bond Work Index for Samples with Non-Standard Feed Particle Size Distribution

by Vladimir Nikolić, Jesus Medina Pierres, Maria Sanchez Calvo, Juan M. Menéndez-Aguado, Milan Trumić, Maja S. Trumić and Vladan Milošević

Minerals 2025, 15(4), 358; https://doi.org/10.3390/min15040358 - 28 Mar 2025

Viewed by 279

Abstract

Determining the Bond grindability test in a ball mill is one of the most commonly used methods in the mining industry for measuring the hardness of ores. The test is an essential part of the Bond work index methodology for designing and calculating [...] Read more.

Determining the Bond grindability test in a ball mill is one of the most commonly used methods in the mining industry for measuring the hardness of ores. The test is an essential part of the Bond work index methodology for designing and calculating the efficiency of mineral grinding circuits. The Bond ball mill grindability test has several restrictions, including the sample’s initial particle size distribution (PSD). This paper presents a method for calculating the Bond work index when the Bond ball mill grindability test is performed on samples with non-standard PSD. The presented equation includes a correction factor (k) and is applicable only for P₁₀₀ = 75 μm. The defined method is then compared with methods proposed by other researchers, and conclusions are drawn as to which method results in less deviation. The presented model resulted in a mean square error of 0.66%. Full article

(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation: 3rd Edition)

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24 pages, 5830 KiB

Open AccessArticle

Assessing the Impact of Surface Blast Design Parameters on the Performance of a Comminution Circuit Processing a Copper-Bearing Ore

by Hervé Losaladjome Mboyo, Bingjie Huo, François K. Mulenga, Pieride Mabe Fogang and Jimmy Kalenga Kaunde Kasongo

Minerals 2024, 14(12), 1226; https://doi.org/10.3390/min14121226 - 2 Dec 2024

Viewed by 1857

Abstract

Open-pit mining remains the dominant method for copper extraction in current operations, with blasting playing a pivotal role in the efficiency of downstream processes such as loading, hauling, crushing, and milling. This study assesses the impact of surface blast design parameters on the [...] Read more.

Open-pit mining remains the dominant method for copper extraction in current operations, with blasting playing a pivotal role in the efficiency of downstream processes such as loading, hauling, crushing, and milling. This study assesses the impact of surface blast design parameters on the performance of a comminution circuit processing a copper-bearing ore. The analysis focuses on important design parameters such as burden, spacing, stemming, and powder factor, evaluating their influence on the fragment size distribution and downstream comminution circuit performance. Using the Kuz-Ram model, four novel blast designs are compared against a baseline to predict the size distribution of rock fragments (X80). Key performance indicators throughput and specific energy consumption are calculated to evaluate the comminution circuit performance. Results demonstrated that reducing the X80 from 500 mm to 120 mm led up to a 20% increase in throughput and a 29% reduction in total specific energy consumption. Furthermore, achieving finer particle sizes through more intensive blasting contributed to a reduction in total operating costs by up to 12%. These findings provide valuable insights for optimizing blast design to improve comminution circuit performance, contributing to sustainable mining practices by reducing energy consumption, operating costs, and the environmental footprint of mining operations. Full article

(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation: 3rd Edition)

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12 pages, 2307 KiB

Open AccessArticle

Experimental Study on the Influence of Rotational Speed on Grinding Efficiency for the Vertical Stirred Mill

by Biliang Tang, Bo Cheng, Xianzhou Song, Haonan Ji, Yijiang Li and Zhaohua Wang

Minerals 2024, 14(12), 1208; https://doi.org/10.3390/min14121208 - 27 Nov 2024

Cited by 2 | Viewed by 803

Abstract

The rotational speed of the agitator is one of the important parameters that affect the grinding efficiency of the vertical stirred mill. Increasing the speed will improve the grinding effect, but it will increase energy consumption, and determining a reasonable speed setting is [...] Read more.

The rotational speed of the agitator is one of the important parameters that affect the grinding efficiency of the vertical stirred mill. Increasing the speed will improve the grinding effect, but it will increase energy consumption, and determining a reasonable speed setting is a system issue. The effects of different speeds on energy consumption, product particle size, and grinding efficiency were analyzed in this study. An experimental vertical stirred mill was used to grind iron ore, and five different speed parameters from 175 rpm to 350 rpm were set as variables. It was found that increasing the rotational speed will increase the grinding effect, but it will trigger more energy consumption. A new evaluation index to comprehensively reflect the grinding efficiency of the mill, which was defined as the ability of a mill to grind the same product per unit of time and energy consumption, was proposed. The grinding efficiency was calculated when the particle size of iron ore powder decreased to −45, −38, and −28 μm at different speeds. It can be seen that the growth rate of energy consumption is faster than that of the percentage of particle size, which leads to a continuous decrease in grinding efficiency with the increase in rotational speed. If high processing capacity is pursued within a certain period of time, high speed can be chosen, but it will result in energy loss. On the contrary, the low speed can be chosen, if considering grinding economy. Full article

(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation: 3rd Edition)

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19 pages, 15038 KiB

Open AccessFeature PaperArticle

Enhancing Iron Ore Grindability through Hybrid Thermal-Mechanical Pretreatment

by Sefiu O. Adewuyi, Hussin A. M. Ahmed, Angelina Anani, Abdu Saeed, Haitham M. Ahmed, Reem Alwafi and Kray Luxbacher

Minerals 2024, 14(10), 1027; https://doi.org/10.3390/min14101027 - 14 Oct 2024

Viewed by 1176

Abstract

Grinding is an important process of ore beneficiation that consumes a significant amount of energy. Pretreating ore before grinding has been proposed to improve ore grindability, reduce comminution energy, and enhance downstream operations. This paper investigates hybrid thermal mechanical pretreatment to improve iron [...] Read more.

Grinding is an important process of ore beneficiation that consumes a significant amount of energy. Pretreating ore before grinding has been proposed to improve ore grindability, reduce comminution energy, and enhance downstream operations. This paper investigates hybrid thermal mechanical pretreatment to improve iron ore grinding behavior. Thermal pretreatment was performed using conventional and microwave approaches, while mechanical pretreatment was conducted with a pressure device using a piston die. Results indicate that conventional (heating rate: 10 °C; maximum temperature: 400 °C), microwave (2.45 GHz, 1.7 kW, 60 s), and mechanical (14.86 MPa, zero delay time) pretreatments improved the studied iron ore grindability by 4.6, 19.8, and 15.4%, respectively. Meanwhile, conventional-mechanical and microwave-mechanical pretreatments enhanced the studied iron ore grindability by 19.2% and 22.6%, respectively. These results suggest that stand-alone mechanical pretreatment or microwave pretreatment may be more beneficial in improving the grinding behavior of the studied fine-grain iron ore sample. The results of the mechanical pretreatment obtained in this study may be used in a simulation of the HPGR system for grinding operations of similar iron ore Full article

(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation: 3rd Edition)

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13 pages, 4021 KiB

Open AccessFeature PaperArticle

Accuracy and Precision of the Geopyörä Breakage Test

by Marcos Bueno, Thiago Almeida, Leonardo Lara, Malcolm Powell and Homero Delboni

Minerals 2024, 14(8), 738; https://doi.org/10.3390/min14080738 - 23 Jul 2024

Viewed by 859

Abstract

The Geopyörä breakage test uses two counter-rotating wheels to nip and crush rock specimens with a tightly controlled gap between rollers. This paper presents the detailed measures conducted to evaluate the accuracy and precision of energy measurements across various ore types using the [...] Read more.

The Geopyörä breakage test uses two counter-rotating wheels to nip and crush rock specimens with a tightly controlled gap between rollers. This paper presents the detailed measures conducted to evaluate the accuracy and precision of energy measurements across various ore types using the Geopyörä. Force measurement was assessed just for its precision. The outputs were compared directly to the drop weight test (DWT) measures of fragmentation at the same energy and fitted A and b parameters. Test reproducibility was evaluated using a Round-Robin methodology, testing several samples in multiple laboratories. The results confirmed that the new test has sufficient accuracy to match DWT results and excellent precision to assure reproducibility. Full article

(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation: 3rd Edition)

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23 pages, 8995 KiB

Open AccessArticle

Evaluation of Ni-Cu Ore from Zapolyarnoe Based on Mineralogical and Physical Properties before and after Comminution

by Arturo H. Bravo, Holger Lieberwirth and Oleg Popov

Minerals 2024, 14(5), 493; https://doi.org/10.3390/min14050493 - 7 May 2024

Cited by 1 | Viewed by 1225

Abstract

For the effective comminution and subsequent enrichment of mineral ores, comprehensive knowledge of their mineralogical and physical properties is required. Using an integrated methodology, this study evaluated samples of polymetallic Ni-Cu ore from Zapolyarnoe, Russia. Several analytical techniques were utilised, including optical microscopy, [...] Read more.

For the effective comminution and subsequent enrichment of mineral ores, comprehensive knowledge of their mineralogical and physical properties is required. Using an integrated methodology, this study evaluated samples of polymetallic Ni-Cu ore from Zapolyarnoe, Russia. Several analytical techniques were utilised, including optical microscopy, microindentation with Vickers geometry, the Point Load Test, and Mineral Liberation Analysis (MLA). The purpose of this study was to determine mineral associations, physical features, and enrichment during jaw crusher comminution. The acquired properties included the Point Load Strength Index, Vickers Hardness Number, and fracture toughness. The MLA method characterised seven fractions in terms of particle size distribution, degree of liberation, association, and modal mineralogy. Magnetite, pyrrhotite, pentlandite, and chalcopyrite were calculated in terms of wt% and their textural features. The enrichment of each ore phase in fractions with particle sizes smaller than 400 µm was determined. The influence of this enrichment was discovered to be correlated with various textural and structural parameters, such as intergrowth, grain size, and crack morphologies after indentations. In addition, the chromium content of magnetite contributed to an increase in the fracture toughness values. Despite the complexities involved, even limited samples of materials provide valuable insights into processing behaviour, emphasising the importance of considering mineralogical parameters in comminution studies. Full article

(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation: 3rd Edition)

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35 pages, 21260 KiB

Open AccessArticle

Calibrating the Digital Twin of a Laboratory Ball Mill for Copper Ore Milling: Integrating Computer Vision and Discrete Element Method and Smoothed Particle Hydrodynamics (DEM-SPH) Simulations

by Błażej Doroszuk, Piotr Bortnowski, Maksymilian Ozdoba and Robert Król

Minerals 2024, 14(4), 407; https://doi.org/10.3390/min14040407 - 16 Apr 2024

Cited by 1 | Viewed by 1901

Abstract

This article presents a novel approach to calibrating the digital twin of a laboratory mill used for copper ore milling. By integrating computer vision techniques for real-time data extraction and employing DualSPHysics simulations for various milling scenarios, including balls only, balls with ore, [...] Read more.

This article presents a novel approach to calibrating the digital twin of a laboratory mill used for copper ore milling. By integrating computer vision techniques for real-time data extraction and employing DualSPHysics simulations for various milling scenarios, including balls only, balls with ore, and balls with slurry, we achieve a high degree of accuracy in matching the digital twin’s behavior with actual mill operations. The calibration process is detailed for mills with three different diameters, highlighting the adjustments in simulation parameters necessary to account for the absence of ore. Understanding the dynamics between the suspension within the mill and the operation of the grinders is crucial for the future improvement of the grinding process. This knowledge paves the way for optimizing the process, not only in terms of the quality of the end product but primarily in terms of energy efficiency. A profound understanding of these interactions will enable engineers and technologists to design mills and grinding processes in a way that maximizes efficiency while minimizing energy consumption. Full article

(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation: 3rd Edition)

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