Editorial

8 pages, 1251 KiB

Open AccessEditorial

Special Issue “Advanced Techniques and Efficiency Assessment of Mechanical Processing”—Editorial Note and Critical Review of the Problems

by Daniel Saramak

Minerals 2021, 11(12), 1428; https://doi.org/10.3390/min11121428 - 17 Dec 2021

Viewed by 1469

Abstract

The value chain of metal production consists of a number of processing steps that result in obtaining the final metal product from the given raw material [...] Full article

(This article belongs to the Special Issue Advanced Techniques and Efficiency Assessment of Mechanical Processing)

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Research

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14 pages, 5425 KiB

Open AccessArticle

Application of Wavelet Filtering to Vibrational Signals from the Mining Screen for Spring Condition Monitoring

by Natalia Duda-Mróz, Sergii Anufriiev and Paweł Stefaniak

Minerals 2021, 11(10), 1076; https://doi.org/10.3390/min11101076 - 30 Sep 2021

Cited by 7 | Viewed by 1577

Abstract

The main task of mineral processing plants is to further process the raw material extracted in the mining faces into a concentrate with the highest possible concentration of the final product. In practice, it is a complex process in which several stages can [...] Read more.

The main task of mineral processing plants is to further process the raw material extracted in the mining faces into a concentrate with the highest possible concentration of the final product. In practice, it is a complex process in which several stages can be distinguished. After the ore has been transported to the surface by the skip shaft, one of the first steps is sieving the ore, which is typically performed using vibrating mining screens. In a typical Ore Enrichment Plant, the screening process is carried out by several such machines. This is a typical bottleneck in the technological chain. For this reason, the main challenge for users is to achieve the highest reliability and efficiency of these technical facilities. The solution is to focus on predictive maintenance strategies based on the development of monitoring and advanced diagnostic procedures capable of estimating the time of safe operation. This work was developed as part of an advanced diagnostic system ensuring comprehensive technical conditioning and early fault detection of components such as the engine, transmission, bearings, springs, and screen. This article focuses on vibration data. The problem of damage detection in the presence of periodically impulsive components resulting from falling feed material on the screen and its further screening process has been considered. These disturbances are of a non-Gaussian noise nature, the elimination of which is essential to extract the fault-related signal of interest. One solution may be to properly smooth and filter the raw signal. In this article, a wavelet filtering technique is applied. First, the wavelet filtering procedure is described. In the next step, the performance of a wavelet filter is investigated depending on its parameters. Then, the results of wavelet filtering are compared with such methods as low-pass filtering and smoothing using a moving average. Finally, the impact of wavelet filtering on the calculation of screen trajectories is investigated. Full article

(This article belongs to the Special Issue Advanced Techniques and Efficiency Assessment of Mechanical Processing)

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15 pages, 6061 KiB

Open AccessArticle

Assessment of Selected Characteristics of Enrichment Products for Regular and Irregular Aggregates Beneficiation in Pulsating Jig

by Tomasz Gawenda, Daniel Saramak, Agata Stempkowska and Zdzisław Naziemiec

Minerals 2021, 11(7), 777; https://doi.org/10.3390/min11070777 - 17 Jul 2021

Cited by 5 | Viewed by 1719

Abstract

Article concerns problem of jig beneficiation of mineral aggregates and focuses especially on problem of separation of hard-enrichable materials. Investigative programme covered tests in laboratory and semi-plant scale and material with different content of regular and irregular particles, along with various particle size [...] Read more.

Article concerns problem of jig beneficiation of mineral aggregates and focuses especially on problem of separation of hard-enrichable materials. Investigative programme covered tests in laboratory and semi-plant scale and material with different content of regular and irregular particles, along with various particle size fractions, was under analysis. Two patented solutions were utilized as methodological approach and densities and absorbabilities of individual products were determined and major novelty of approach consist in separate beneficiation of regular and irregular particles. Results of laboratory investigations showed that more favorable separation effectiveness was observed for the narrow particle size fractions of feed material. In terms of absorbability difference between separation products from I and IV layer was 0.4–0.5% higher for regular particles, and up to 0.5% higher for irregular grains. Differences in densities of respective products were 0.1% higher for regular particles. Results of semi-plant tests confirmed the outcomes achieved in laboratory scale. The qualitative characteristics of separation products in terms of micro-Deval and LA comminution resistance indices were one category higher for regular particles, and two categories higher for irregular grains, comparing to the raw material. Full article

(This article belongs to the Special Issue Advanced Techniques and Efficiency Assessment of Mechanical Processing)

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14 pages, 4976 KiB

Open AccessArticle

A Numerical Study of Separation Performance of Vibrating Flip-Flow Screens for Cohesive Particles

by Chi Yu, Runhui Geng and Xinwen Wang

Minerals 2021, 11(6), 631; https://doi.org/10.3390/min11060631 - 14 Jun 2021

Cited by 19 | Viewed by 2305

Abstract

Vibrating flip-flow screens (VFFS) are widely used to separate high-viscosity and fine materials. The most remarkable characteristic is that the vibration intensity of the screen frame is only 2–3 g (g represents the gravitational acceleration), while the vibration intensity of the screen surface [...] Read more.

Vibrating flip-flow screens (VFFS) are widely used to separate high-viscosity and fine materials. The most remarkable characteristic is that the vibration intensity of the screen frame is only 2–3 g (g represents the gravitational acceleration), while the vibration intensity of the screen surface can reach 30–50 g. This effectively solves the problem of the blocking screen aperture in the screening process of moist particles. In this paper, the approximate state of motion of the sieve mat is realized by setting the discrete rigid motion at multiple points on the elastic sieve mat of the VFFS. The effects of surface energy levels between particles separated via screening performance were compared and analyzed. The results show that the flow characteristics of particles have a great influence on the separation performance. For 8 mm particle screening, the particle’s velocity dominates its movement and screening behavior in the range of 0–8 J/m² surface energy. In the feeding end region (Sections 1 and 2), with the increase in the surface energy, the particle’s velocity decreases, and the contact time between the particles and the screen surface increases, and so the passage increases. When the surface energy level continues to increase, the particles agglomerate together due to the effect of the cohesive force, and the effect of the particle’s agglomeration is greater than the particle velocity. Due to the agglomeration of particles, the difficulty of particles passing through the screen increases, and the yields of various size fractions in the feeding end decrease to some extent. In the transporting process, the agglomerated particles need to travel a certain distance before depolymerization, and the stronger the adhesive force between particles, the larger the depolymerization distance. Therefore, for the case of higher surface energy, the screening percentage near the discharging end (Sections 3 and 4) is greater. The above research is helpful to better understand and optimize the screening process of VFFS. Full article

(This article belongs to the Special Issue Advanced Techniques and Efficiency Assessment of Mechanical Processing)

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10 pages, 4525 KiB

Open AccessArticle

Assessment of Sortability Using a Dual-Energy X-ray Transmission System for Studied Sulphide Ore

by YiRan Zhang, Nawoong Yoon and Maria E. Holuszko

Minerals 2021, 11(5), 490; https://doi.org/10.3390/min11050490 - 04 May 2021

Cited by 7 | Viewed by 2379

Abstract

In hard rock mining, sensor-based sorting can be applied as a pre-concentration method before the material enters the mill. X-ray transmission sensors have been explored in mining since 1972. Sorting ore of acceptable grade and waste material before processing at the mill can [...] Read more.

In hard rock mining, sensor-based sorting can be applied as a pre-concentration method before the material enters the mill. X-ray transmission sensors have been explored in mining since 1972. Sorting ore of acceptable grade and waste material before processing at the mill can reduce the amount of tailings per unit of valuable metal in the mining operation and have many economic benefits. Ore samples used in this paper are from a polymetallic carbonate replacement deposit (gold-silver-lead-zinc sulphide) in Southeast Europe. This paper focuses on how the Dual-Energy X-ray Transmission (DE-XRT) data is generated and used for ore characterization and sortability for this sulphide ore. The method used in the DE-XRT analysis in this project is based on the dual-material decomposition method, which is used in the medical industry for radiology. This technique can distinguish sulphides from non-sulphides. However, the correlation developed between the DE-XRT response and the metal content is lacking. As a result, the DE-XRT response can only classify the material effectively but cannot reliably predict the metal content. Full article

(This article belongs to the Special Issue Advanced Techniques and Efficiency Assessment of Mechanical Processing)

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12 pages, 2342 KiB

Open AccessArticle

Multidimensional Optimization of the Copper Flotation in a Jameson Cell by Means of Taxonomic Methods

by Tomasz Niedoba, Paulina Pięta, Agnieszka Surowiak and Oktay Şahbaz

Minerals 2021, 11(4), 385; https://doi.org/10.3390/min11040385 - 03 Apr 2021

Cited by 3 | Viewed by 2547

Abstract

Three factors were measured in the flotation process of copper ore: the copper grade in a concentrate (β), the copper grade in tailings (ϑ), and the recovery of copper in a concentrate (ε). The experiment was conducted by means of a Jameson cell. [...] Read more.

Three factors were measured in the flotation process of copper ore: the copper grade in a concentrate (β), the copper grade in tailings (ϑ), and the recovery of copper in a concentrate (ε). The experiment was conducted by means of a Jameson cell. The factors influencing the quality of the process were the particle size (d), the flotation time (t), the type of collector (k), and the dosage of the collector (s). The considered vector function is then (β(d, t, k, s), ϑ(d, t, k, s), ε(d, t, k, s)). In this work, the optimization was based on determining the values of the adjustable factors (d, t, k, s). The goal was to obtain the possibly highest values of the functions β and ε (maximum) with the possibly lowest values of the function ϑ (minimum). To this end, taxonomic methods were applied. Thanks to the applied method, the optimum—with the adopted assumptions—was found. The presented methodology can be successfully applied in the search for the optima in a variety of technological processes. Full article

(This article belongs to the Special Issue Advanced Techniques and Efficiency Assessment of Mechanical Processing)

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15 pages, 5521 KiB

Open AccessArticle

Kinetic Energy Calculation in Granite Particles Comminution Considering Movement Characteristics and Spatial Distribution

by Qing Guo, Yongtai Pan, Qiang Zhou, Chuan Zhang and Yankun Bi

Minerals 2021, 11(2), 217; https://doi.org/10.3390/min11020217 - 20 Feb 2021

Cited by 2 | Viewed by 1944

Abstract

Profound knowledge of the movement characteristics and spatial distribution of the particles under compression during the crushing of rocks and ores is essential to further understanding kinetic energy release law. Various experimental methods such as high-speed camera technology, the coordinate method, and the [...] Read more.

Profound knowledge of the movement characteristics and spatial distribution of the particles under compression during the crushing of rocks and ores is essential to further understanding kinetic energy release law. Various experimental methods such as high-speed camera technology, the coordinate method, and the color tracking method were adopted to improve the understanding of particles’ movement characteristics and spatial distribution in rock comminution. The average horizontal velocities of the four size particles α, β, γ, and δ are statistically calculated. The descending order of the particles’ average velocity is γ, β, α, and δ. In comparison, the descending order of the particles’ kinetic energy is α, β, γ, and δ. Moreover, the contribution of α particles to the total kinetic energy exceeds 70%. The spatial distribution characteristics of coarse and fine particles show different results. The probability of fine particles appearing in the range closer to the center area is greater, while the position of large particles appears to be more random. The color tracking results show that super-large particles generated by crushing are on the specimen’s surface, while small particles are generally produced from inside. The above results indicate a connection between the particle generation mechanism, movement characteristics, and spatial distribution in the comminution process. Full article

(This article belongs to the Special Issue Advanced Techniques and Efficiency Assessment of Mechanical Processing)

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16 pages, 6966 KiB

Open AccessArticle

A New Belt Ore Image Segmentation Method Based on the Convolutional Neural Network and the Image-Processing Technology

by Xiqi Ma, Pengyu Zhang, Xiaofei Man and Leming Ou

Minerals 2020, 10(12), 1115; https://doi.org/10.3390/min10121115 - 11 Dec 2020

Cited by 21 | Viewed by 3794

Abstract

In the field of mineral processing, an accurate image segmentation method is crucial for measuring the size distribution of run-of-mine ore on the conveyor belts in real time0The image-based measurement is considered to be real time, on-line, inexpensive, and non-intrusive. In this paper, [...] Read more.

In the field of mineral processing, an accurate image segmentation method is crucial for measuring the size distribution of run-of-mine ore on the conveyor belts in real time0The image-based measurement is considered to be real time, on-line, inexpensive, and non-intrusive. In this paper, a new belt ore image segmentation method was proposed based on a convolutional neural network and image processing technology. It consisted of a classification model and two segmentation algorithms. A total of 2880 images were collected as an original dataset from the process control system (PCS). The test images were processed using the proposed method, the PCS system, the coarse image segmentation (CIS) algorithm, and the fine image segmentation (FIS) algorithm, respectively. The segmentation results of each algorithm were compared with those of the manual segmentation. All empty belt images in the test images were accurately identified by our method. The maximum error between the segmentation results of our method and the results of manual segmentation is 5.61%. The proposed method can accurately identify the empty belt images and segment the coarse material images and mixed material images with high accuracy. Notably, it can be used as a brand new algorithm for belt ore image processing. Full article

(This article belongs to the Special Issue Advanced Techniques and Efficiency Assessment of Mechanical Processing)

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Review

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12 pages, 2188 KiB

Open AccessReview

Challenges in Raw Material Treatment at the Mechanical Processing Stage

by Daniel Saramak

Minerals 2021, 11(9), 940; https://doi.org/10.3390/min11090940 - 29 Aug 2021

Cited by 4 | Viewed by 2219

Abstract

This paper concerns problems related to the mechanical processing of mineral raw materials. The aspects explored were limited to the analysis of comminution technologies in terms of their effectiveness and energy consumption, modeling and simulation approaches, the assessment of crushing results, and environmental [...] Read more.

This paper concerns problems related to the mechanical processing of mineral raw materials. The aspects explored were limited to the analysis of comminution technologies in terms of their effectiveness and energy consumption, modeling and simulation approaches, the assessment of crushing results, and environmental aspects. This article includes investigation of new technologies of comminution, comparing HPGR, high-voltage pulses, and electromagnetic mills. In the area of modeling and optimization, special attention was paid to the approximation of the particle size distribution of crushing products by means of Weibull, log-normal, and logistic functions. Crushing products with an increased content of fines were well characterized by Weibull’s distribution, while log-normal function adequately described HPGR products with a relatively low content of fines. Full article

(This article belongs to the Special Issue Advanced Techniques and Efficiency Assessment of Mechanical Processing)

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