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3 pages, 182 KiB

Open AccessEditorial

Grinding and Concentration Technology of Critical Metals

by Juan M. Menéndez Aguado

Metals 2022, 12(4), 585; https://doi.org/10.3390/met12040585 - 30 Mar 2022

Viewed by 1126

Abstract

The production and supply of raw materials in a global market are not without risks, and both the recent COVID-19 pandemic and the current one (Russia–Ukrania conflict) raised public awareness about the importance of multiple value chains [...] Full article

(This article belongs to the Special Issue Grinding and Concentration Technology of Critical Metals)

Research

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13 pages, 3365 KiB

Open AccessArticle

Study of Comminution Kinetics in an Electrofragmentation Lab-Scale Device

by Angel R. Llera, Ana Díaz, Francisco J. Pedrayes, Juan M. Menéndez-Aguado and Manuel G. Melero

Metals 2022, 12(3), 494; https://doi.org/10.3390/met12030494 - 14 Mar 2022

Cited by 3 | Viewed by 1576

Abstract

A significant challenge in mineral raw materials comminution is the improvement of process energy efficiency. Conventional comminution techniques, although globally used, are far from being considered power-efficient. The use of high-voltage electric pulses in comminution is a concept that is worthy of study; [...] Read more.

A significant challenge in mineral raw materials comminution is the improvement of process energy efficiency. Conventional comminution techniques, although globally used, are far from being considered power-efficient. The use of high-voltage electric pulses in comminution is a concept that is worthy of study; despite its lack of industrial-scale validation after several decades of lab-scale research, it seems promising as a pretreatment leading to energy savings. In this article, the Cumulative Kinetic Model methodology is adapted to model the comminution effect in an electrofragmentation device, and study a dunite rock ore. The results show that product particle size distribution (PSD) can be predicted with reasonable accuracy using the proposed model. Full article

(This article belongs to the Special Issue Grinding and Concentration Technology of Critical Metals)

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7 pages, 258 KiB

Open AccessArticle

Variability of the Ball Mill Bond’s Standard Test in a Ta Ore Due to the Lack of Standardization

by Gloria González García, Alfredo L. Coello-Velázquez, Begoña Fernández Pérez and Juan M. Menéndez-Aguado

Metals 2021, 11(10), 1606; https://doi.org/10.3390/met11101606 - 9 Oct 2021

Cited by 5 | Viewed by 1310

Abstract

There is no doubt about the practical interest of Fred Bond’s methodology in the field of comminution, not only in tumbling mills design and operation but also in mineral raw materials grindability characterization. Increasing energy efficiency in comminution operations globally is considered a [...] Read more.

There is no doubt about the practical interest of Fred Bond’s methodology in the field of comminution, not only in tumbling mills design and operation but also in mineral raw materials grindability characterization. Increasing energy efficiency in comminution operations globally is considered a significant challenge involving several Sustainable Development Goals (SDGs). In particular, the Bond work index (w_i) is considered a critical parameter at an industrial scale, provided that power consumption in comminution operations accounts for up to 40% of operational costs. Despite this, the variability of w_i when performing the ball mill Bond’s standard test is not always understood enough. This study shows the results of a variability analysis (a 3³ factorial design) performed to elucidate the influence on w_i of several parameters obtained from the particle size distribution (PSD) in feed and product. Results showed a clear variability in the work and grindability indexes with some of the variables considered. Full article

(This article belongs to the Special Issue Grinding and Concentration Technology of Critical Metals)

12 pages, 1686 KiB

Open AccessArticle

Particle Size Distribution Models for Metallurgical Coke Grinding Products

by Laura Colorado-Arango, Juan M. Menéndez-Aguado and Adriana Osorio-Correa

Metals 2021, 11(8), 1288; https://doi.org/10.3390/met11081288 - 16 Aug 2021

Cited by 12 | Viewed by 2635

Abstract

Six different particle size distribution (Gates–Gaudin–Schuhmann (GGS), Rosin–Rammler (RR), Lognormal, Normal, Gamma, and Swebrec) models were compared under different metallurgical coke grinding conditions (ball size and grinding time). Adjusted R², Akaike information criterion (AIC), and the root mean of square error [...] Read more.

Six different particle size distribution (Gates–Gaudin–Schuhmann (GGS), Rosin–Rammler (RR), Lognormal, Normal, Gamma, and Swebrec) models were compared under different metallurgical coke grinding conditions (ball size and grinding time). Adjusted R², Akaike information criterion (AIC), and the root mean of square error (RMSE) were employed as comparison criteria. Swebrec and RR presented superior comparison criteria with the higher goodness-of-fit and the lower AIC and RMSE, containing the minimum variance values among data. The worst model fitting was GGS, with the poorest comparison criteria and a wider results variation. The undulation Swebrec parameter was ball size and grinding time-dependent, considering greater b values (b > 3) at longer grinding times. The RR α parameter does not exhibit a defined tendency related to grinding conditions, while the k parameter presents smaller values at longer grinding times. Both models depend on metallurgical coke grinding conditions and are hence an indication of the grinding behaviour. Finally, oversize and ultrafine particles are found with ball sizes of 4.0 cm according to grinding time. The ball size of 2.54 cm shows slight changes in particle median diameter over time, while 3.0 cm ball size requires more grinding time to reduce metallurgical coke particles. Full article

(This article belongs to the Special Issue Grinding and Concentration Technology of Critical Metals)

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11 pages, 1236 KiB

Open AccessArticle

Unveiling the Link between the Third Law of Comminution and the Grinding Kinetics Behaviour of Several Ores

by Victor Ciribeni, Juan M. Menéndez-Aguado, Regina Bertero, Andrea Tello, Enzo Avellá, Matías Paez and Alfredo L. Coello-Velázquez

Metals 2021, 11(7), 1079; https://doi.org/10.3390/met11071079 - 5 Jul 2021

Cited by 4 | Viewed by 1542

Abstract

As a continuation of a previous research work carried out to estimate the Bond work index (w_i) by using a simulator based on the cumulative kinetic model (CKM), a deeper analysis was carried out to determine the link between the [...] Read more.

As a continuation of a previous research work carried out to estimate the Bond work index (w_i) by using a simulator based on the cumulative kinetic model (CKM), a deeper analysis was carried out to determine the link between the kinetic and energy parameters in the case of metalliferous and non-metallic ore samples. The results evidenced a relationship between the CKM kinetic parameter k and the grindability index gbp; and also with the w_i, obtained following the standard procedure. An excellent correlation was obtained in both cases, posing the definition of alternative work index estimation tests with the advantages of more straightforward and quicker laboratory procedures. Full article

(This article belongs to the Special Issue Grinding and Concentration Technology of Critical Metals)

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11 pages, 2697 KiB

Open AccessFeature PaperArticle

Variability Study of Bond Work Index and Grindability Index on Various Critical Metal Ores

by Gloria G. García, Josep Oliva, Eduard Guasch, Hernán Anticoi, Alfredo L. Coello-Velázquez and Juan M. Menéndez-Aguado

Metals 2021, 11(6), 970; https://doi.org/10.3390/met11060970 - 17 Jun 2021

Cited by 11 | Viewed by 3351

Abstract

It is a well-known fact that the value of the Bond work index (w_i) for a given ore varies along with the grinding size. In this study, a variability bysis is carried out with the Bond standard grindability tests on [...] Read more.

It is a well-known fact that the value of the Bond work index (w_i) for a given ore varies along with the grinding size. In this study, a variability bysis is carried out with the Bond standard grindability tests on different critical metal ores (W, Ta), ranging from coarse grinding (rod mills) to fine grinding (ball mills). The relationship between w_i and grinding size did not show a clear correlation, while the grindability index (gpr) and the grinding size showed a robust correlation, fitting in all cases to a quadratic curve with a very high regression coefficient. This result suggests that, when performing correlation studies among ore grindability and rock mechanics parameters, it is advised to use the grindability index instead of the Bond work index. Full article

(This article belongs to the Special Issue Grinding and Concentration Technology of Critical Metals)

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11 pages, 1809 KiB

Open AccessArticle

A Comparative Study of Energy Efficiency in Tumbling Mills with the Use of Relo Grinding Media

by Nikolay Kolev, Petar Bodurov, Vassil Genchev, Ben Simpson, Manuel G. Melero and Juan M. Menéndez-Aguado

Metals 2021, 11(5), 735; https://doi.org/10.3390/met11050735 - 29 Apr 2021

Cited by 6 | Viewed by 3323

Abstract

An evaluation of Relo grinding media (RGM, Reuleaux tetrahedron-shaped bodies) performance versus standard grinding media (balls) was made through a series of grinding tests, including a slight modification of the standard Bond test procedure. Standard Bond tests showed a reduction in the Bond [...] Read more.

An evaluation of Relo grinding media (RGM, Reuleaux tetrahedron-shaped bodies) performance versus standard grinding media (balls) was made through a series of grinding tests, including a slight modification of the standard Bond test procedure. Standard Bond tests showed a reduction in the Bond ball mill work index (w_i) of the mineral sample used in this study when using Relo grinding media. The modified Bond test procedure is based on using the standard Bond ball work index test but changing the circulating loads (350%, 250%, 150%, 100%). The comparative tests with RGM were carried out at the same number of revolutions as the grinding tests with balls at respective circulating load. The RGM charge yielded a 14% higher net undersize product than balls, which hints at improving energy efficiency and the potential for significant mining industry benefits. Full article

(This article belongs to the Special Issue Grinding and Concentration Technology of Critical Metals)

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13 pages, 6813 KiB

Open AccessArticle

Grinding Kinetics Study of Tungsten Ore

by Jennire V. Nava, Alfredo L. Coello-Velázquez and Juan M. Menéndez-Aguado

Metals 2021, 11(1), 71; https://doi.org/10.3390/met11010071 - 31 Dec 2020

Cited by 10 | Viewed by 1866

Abstract

The European Commission (EC) maintains the consideration of tungsten as a critical raw material for the European industry, being the comminution stage of tungsten-bearing minerals an essential step in the tungsten concentration process. Comminution operations involve approximately 3–4% of worldwide energy consumption; therefore, [...] Read more.

The European Commission (EC) maintains the consideration of tungsten as a critical raw material for the European industry, being the comminution stage of tungsten-bearing minerals an essential step in the tungsten concentration process. Comminution operations involve approximately 3–4% of worldwide energy consumption; therefore, grinding optimization should be a priority. In this study, the grinding behavior of tungsten ore from Barruecopardo Mine (Salamanca, Spain) is analyzed. A protocol based on Austin’s methodology and PBM is developed in order to study the influence of operational and geometallurgical variables on grinding kinetics. In addition to the kinetic parameters, the breakage probability (S_i) and breakage function (B_ij) is determined. The selection function was formulated for the Barruecopardo Mine with respect to the mill speed. Full article

(This article belongs to the Special Issue Grinding and Concentration Technology of Critical Metals)

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19 pages, 3723 KiB

Open AccessArticle

Kinetics of Dry-Batch Grinding in a Laboratory-Scale Ball Mill of Sn–Ta–Nb Minerals from the Penouta Mine (Spain)

by Jenniree V. Nava, Teresa Llorens and Juan María Menéndez-Aguado

Metals 2020, 10(12), 1687; https://doi.org/10.3390/met10121687 - 17 Dec 2020

Cited by 9 | Viewed by 2627

Abstract

The optimization of processing plants is one of the main concerns in the mining industry, since the comminution stage, a fundamental operation, accounts for up to 70% of total energy consumption. The aim of this study was to determine the effects that ball [...] Read more.

The optimization of processing plants is one of the main concerns in the mining industry, since the comminution stage, a fundamental operation, accounts for up to 70% of total energy consumption. The aim of this study was to determine the effects that ball size and mill speed exert on the milling kinetics over a wide range of particle sizes. This was done through dry milling and batch grinding tests performed on two samples from the Penouta Sn–Ta–Nb mine (Galicia, Spain), and following Austin methodology. In addition, the relationships amongst Sn, Ta and Nb content, as metals of interest, the specific rate of breakage S_i, the kinetic parameters, and the operational conditions were studied through X-Ray fluorescence (XRF) techniques. The results show that, overall, the specific rate of breakage S_i decreases with decreasing feed particle size and increasing ball size for most of the tested conditions. A selection function, α_T, was formulated on the basis of the ball size for both Penouta mine samples. Finally, it was found that there does exist a direct relationship amongst Sn, Ta and Nb content, as metals of interest, in the milling product, the specific rate of breakage S_i and the operational–mineralogical variables of ball size, mill speed and feed particle size. Full article

(This article belongs to the Special Issue Grinding and Concentration Technology of Critical Metals)

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11 pages, 1023 KiB

Open AccessArticle

Application of the Cumulative Kinetic Model in the Comminution of Critical Metal Ores

by Victor Ciribeni, Regina Bertero, Andrea Tello, Matías Puerta, Enzo Avellá, Matías Paez and Juan María Menéndez Aguado

Metals 2020, 10(7), 925; https://doi.org/10.3390/met10070925 - 9 Jul 2020

Cited by 10 | Viewed by 2360

Abstract

Over the last decades, several reliable mathematical models have been developed for simulating ore comminution processes and determining the Work Index. Since Fred Chester Bond developed the Work Index standard procedure in 1961, numerous attempts have been made to find simpler, faster, and [...] Read more.

Over the last decades, several reliable mathematical models have been developed for simulating ore comminution processes and determining the Work Index. Since Fred Chester Bond developed the Work Index standard procedure in 1961, numerous attempts have been made to find simpler, faster, and economically more advantageous alternative tests. In this paper, a Bond test simulation based on the cumulative kinetic model (CKM) has been checked on a spreadsheet. The research has been accomplished by conventionally determining the kinetic parameters for some Ag and Au ores and for three pure minerals and one rock that are common constituents of the gangue rock. Analysis of the results obtained allowed to develop a simplified procedure for calculating the kinetic parameters and their application to Work Index determination through simulation. Full article

(This article belongs to the Special Issue Grinding and Concentration Technology of Critical Metals)

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Review

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16 pages, 3837 KiB

Open AccessReview

A Review of Alternative Procedures to the Bond Ball Mill Standard Grindability Test

by Vladimir Nikolić, Gloria G. García, Alfredo L. Coello-Velázquez, Juan M. Menéndez-Aguado, Milan Trumić and Maja S. Trumić

Metals 2021, 11(7), 1114; https://doi.org/10.3390/met11071114 - 12 Jul 2021

Cited by 7 | Viewed by 2656

Abstract

Over the years, alternative procedures to the Bond grindability test have been proposed aiming to avoid the need for the standard mill or to reduce and simplify the grinding procedure. Some of them use the standard mill, while others are based on a [...] Read more.

Over the years, alternative procedures to the Bond grindability test have been proposed aiming to avoid the need for the standard mill or to reduce and simplify the grinding procedure. Some of them use the standard mill, while others are based on a non-standard mill or computation techniques. Therefore, papers targeting to propose a better alternative claim to improve validity, to reduce test duration, or to propose simpler and faster alternative methods for determining the Bond work index (w_i). In this review paper, a compilation and critical analysis of selected proposals is performed, concluding that some of the short procedures could be useful for control purposes, while the simulation-based procedures could be interesting within a process digitalisation strategy. Full article

(This article belongs to the Special Issue Grinding and Concentration Technology of Critical Metals)

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