Ore Samples Research Articles

Machine learning model for deep exploration: Utilizing short wavelength infrared (SWIR) of hydrothermal alteration minerals in the Qianchen gold deposit, Jiaodong Peninsula, Eastern China

The Jiaodong Peninsula in the eastern North China Craton is renowned globally as a major gold province. Notably, the Jiaojia orefield is an important gold-producing district in this region, and its depths are inferred to offer substantial prospecting potential, underscoring the need for innovative exploration tools to uncover concealed orebodies. The Qianchen gold deposit in the southern part of the Jiaojia orefield is characterized by the disseminated-stockwork-style orebodies at depths of ca. –1000 to –1800 m, with three mineralization stages, namely (I) pre-ore K-feldspar-quartz stage, (II) quartz-sericite-gold-polymetallic sulfide stage (main Au mineralization stage), and (III) post-ore quartz-calcite stage. Systematic short-wavelength infrared (SWIR) spectral analysis reveals that sericite group minerals developing in Stage II are the predominant and wide-distributed alteration minerals at Qianchen. Their spectral characteristics demonstrate a shift in the Al-OH absorption feature wavelength positions (Pos2200) to longer wavelengths (>2205 nm) within the orebodies. This shift is likely due to strong water–rock interactions leading to Fe and Mg substituting for Al in octahedral sites. Orthogonal partial least squares discriminant analysis (OPLS-DA) indicates that the H2O, OH, and FeOH spectral bands (Variable Importance in the Projection (VIP) ≥ 1) of sericite are crucial for distinguishing between gold ores and barren wall rocks. Additionally, Long Short-Term Memory (LSTM) models demonstrate that spectral data of sericite can be used to predict ore samples with an accuracy of 82 %, validated by receiver operating characteristic analysis (84 %), and blind test results demonstrate that the predicted grade closely aligns with the actual grade. Therefore, it is concluded that SWIR spectral characteristics of sericite group minerals can serve as an effective indicator for prospecting the Qianchen concealed gold mineralization. This study highlights the potential of coupling between machine learning and SWIR spectral data of alteration minerals to uncover the concealed lode gold mineralization.

An automated mineralogy derived criterion for clustering ore samples for mineral liberation studies

Correctly determining the optimal grinding size is crucial for mineral processors, yet it poses several challenges. Still popular among practitioners, the empirical determination of the grinding target involves time-consuming and resource-intensive laboratory routines employed for generating quality, recovery and energy curves from which the target size is set. This approach becomes even more challenging for mines with diverse ore textures, requiring extensive testing on numerous samples to accurately capture the behaviour of the entire ore body. Consequently, a more efficient experimental method is highly desirable. A solution for reducing the laboratory effort is clustering samples according to the mineral liberation characteristics. This paper introduces a novel multivariate criterion for statistical clustering of ore samples for mineral liberation studies, derived from SEM-based automated mineralogy data. The criterion considers three variables: two coefficients (named A and k) derived from the exponential correlation equation between degree of liberation and the top size of the size fraction, and the overall degree of liberation, both easily obtained from the liberation spectrum for a top size of 1 mm. The effectiveness of the proposed criterion has been experimentally demonstrated. It was concluded that the clustering process correctly grouped samples with similar mineral liberation characteristics. The clustering approach can be used to significantly reduce the laboratory effort on liberation studies involving a great number of samples of different types of ore. Although developed using iron ore samples, the criterion's theoretical basis suggests its potential for adaptation to other types of ore.

Iron ore grade's impact on uniaxial compression behavior and acoustic emission characteristics

The mechanical properties of iron ore are influenced by various factors, including its grade, which consequently impacts stope stability and equipment efficiency in the mining process. In order to explore the influence and mechanism of grade on these properties, handheld XRF testing was conducted to determine the grade of iron ore samples ranging from 28% to 40%. Subsequently, the acoustic emission method was employed to acquire signals during the uniaxial compression tests. Additionally, scanning electron microscopy was utilized to examine the fracture surface, for performing a microscopic analysis of the influence mechanism of grade on the mechanical properties of iron ore. The results revealed that lower-grade iron ore exhibited larger transverse deformation, with a corresponding dominance of tensile failure. This observation aligned with the AF-RA value (Parameters of reaction crack type), which depicted a shift in the types of microcracks generated during the compression process from tensile cracks to shear cracks with the increasing grade. The content of gangue minerals diminishing as the grade increased. Consequently, the location of the cracks transitioned from the primary failure Through the gangue minerals to the primary microcracks in metallic minerals, resulting in a higher occurrence of acoustic emission events during the early loading stage and the development speed of microcracks accelerates during the loading process. The dominant frequency (Parameters of reaction crack size) of the acoustic emission signal increased from 150 kHz at a grade of 28% to 264 kHz at a grade of 40%, accompanied by a linear decrease in the proportion of low-frequency signals. The b value (indicator for quantifying the degree of damage) demonstrates a decrease with increasing grade. Overall, the content of metal minerals in the iron ore increased with the grade, resulting in polymerization. However, the influence of crack propagation on the overall strength of iron ore remained relatively minor. Macroscopically, the uniaxial compressive strength increased almost linearly with the iron ore grade.

Analysis of bioleaching characteristics and multi-element dissolution behavior of complex zinc ores

In order to recover low-grade complex zinc ore in a reasonable way, this study adopts bioleaching method to study it. The ore samples contain 1.52%, 2.03% and 14.4% zinc, respectively, which occurs in the form of sphalerite. Other major minerals include pyrite, galena, quartz and mica. The inoculation of the domesticated strain was basically free of adaptation period, and the cell concentration could be rapidly increased after a short decrease. The leaching extent of zinc increased continuously, while the leaching rate decreased gradually. After the bioleaching process, sliver, lead and iron were mainly present in the residue phase. X-ray diffraction spectroscopy analysis showed that sphalerite, galena and pyrite were dissolved, and the latter two further precipitated to produce PbSO4 and jarosite. In addition, the dissolution of calcium compounds can lead to the formation of gypsum precipitation. These precipitates covered the fresh ore surface may hinder the further bioleaching process. The Exponential model was used to simulate the bioleaching process, and it was found that the fit coefficients were all greater than 0.98, and a reasonable leaching cycle was further discussed. The results provide a good basis for the economic and environmentally friendly recovery of low-grade complex zinc ores.

The First Application of Laser-Induced Breakdown Spectroscopy: A Fast-Analytical Technique in Targeted Search for Elements in Geological Samples from Deep Boreholes in Latvia

Abstract Laser-induced breakdown spectroscopy (LIBS) provides a rapid, cost-effective, and extra-sensitive analysis of geological samples to make preliminary conclusions about the presence of valuable elements up to the trace levels in the ore. We present the first results of a highly sensitive qualitative analysis of the core samples of geological ore from two boreholes in Latvia (Staicele 1, from a depth range of 794–802 m, and Garsene (Subate) 2A, from a depth range of 1102–1103 m) using LIBS. Our measurements using this technique confirmed the high iron content and indicated traces of rare and high in-demand metals (such as Ti, V, Co, Sm, etc.) in the sample from Staicele, renewing interest in studying boreholes across Latvia. The presented pilot studies demonstrated effectiveness and unique possibility in performing a very sensitive and time-saving qualitative analysis of the composition of samples of ores from the old but still valuable borehole cores by using the LIBS method. We compare these measurements with other methods of sample analysis.

Computed Tomography of Scheelite Ore, Kara, Australia: Morphological Characterisation and Modal Mineralogy

Metal ores are mineralogically characterised to understand their genesis in order to allow informed decisions on mineral processing and to recognise likely environmental risks upon mining. However, standard mineralogical techniques generate only two-dimensional information at best, which in addition may be subject to sampling and stereological errors. By contrast, computed tomography (CT) is a non-destructive imaging technique that allows three-dimensional analysis of solid materials. In the present study, two ore types of the Kara Fe-W deposit (Australia) were characterised using CT to examine their mineral texture and modal mineralogy as well as scheelite distribution and ore grade (WO3). The results show that scheelite is primarily associated with hydrous phases (e.g., epidote, chlorite, amphibole) and occurs as massive or disseminated mineral as well as vein-fill at minor and trace concentrations. This study demonstrates that CT of scheelite ore enables accurate 3D texture visualisation (volume, grain size distribution) and yields valid quantitative data on modal mineralogy and WO3 grade of individual ore samples. Consequently, CT analysis of scheelite-bearing ore provides information relevant for ore genesis studies and comminution strategies for the possible recovery of scheelite as a by-product from metalliferous ores.

Insights into metal tolerance and resistance mechanisms in Trichoderma asperellum unveiled by de novo transcriptome analysis during bioleaching

This study investigates the genetic responses of the fungus Trichoderma asperellum (T. asperellum) during bioleaching of ore and tailing samples, comparing one-step, two-step, and spent media bioleaching processes. HPLC analysis quantified oxalic acid, citric acid, and propionic acids, with oxalic acid identified as the primary organic acid involved in metal bioleaching. Metal analysis revealed differences in recovery between ore and tailing samples and among bioleaching processes. The two-step bioleaching process yielded the highest zinc (>54%) and nickel (>60%) recovery in tailings and ore, respectively. Nickel's efficient recovery in ore bioleaching was attributed to the presence of manganese, while its precipitation as nickel oxalate in tailings hindered recovery. Additional metals such as Co, Mn, Mg, Cu, and As were also successfully recovered. Transcriptomic analyses showed significant upregulation of genes associated with biological processes and cellular components, particularly those related to cell membrane structure and function, indicating T. asperellum's adaptation to environmental stresses during metal bioleaching. These findings enhance our understanding of the diverse mechanisms influencing metal recovery rates in bioleaching processes.

Novel approach to locate micro-scale mineral regions of interest in real ores

The surface of minerals plays a pivotal role throughout the process of mineral beneficiation and utilization. Studies on surface properties, such as surface chemistries, of mineral phases of interest in real ores enable the selective separation of minerals, thereby enhancing the utilization of mineral resources. Nevertheless, obtaining specific mineral phases, especially for finely disseminated or poorly crystalized minerals, from real ores without altering their surface chemistries remains a challenge. The challenge also persists in investigating the same micro-scale mineral region in real ores using various surface characterization techniques, such as scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). This paper proposes a novel approach and procedures for locating micro-scale mineral regions of interest in real ores based on a three-dimensional coordinate system etched onto the ore surface using laser etching technology. A copper-nickel ore from Jinchuan, China, served as an illustrative example, with the finely disseminated chalcopyrite and pentlandite regions in the real ore sample being located and investigated using SEM and XPS. The approach presented in this study enables the in-situ detection of surface chemistries of specific mineral phase in real ores, ensuring the homogeneity and in-situ nature of the obtained surface chemistry data. This approach holds considerable promise, especially in the investigation of surface chemistries of minerals with fine dissemination and poor crystallization.

Atmospheric hydrochloric and nitric acid leaching of a limonite ore from the Wolo mine area, Southeast Sulawesi, Indonesia

The atmospheric acid leaching studies of a limonite ore sample from the Wolo mine area, Southeast Sulawesi, Indonesia, have been performed using hydrochloric acid (HCl) and nitric acid (HNO3). The objectives of these studies were to compare the leaching degree of metals (Ni, Co, Fe, and Al) and to analyze the dissolution behavior of minerals under different acid concentrations. Mineralogical characterization of the ore sample was conducted using optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction, whereas chemical composition was determined by X-ray fluorescence (XRF) spectrometry and atomic absorption spectroscopy (AAS), respectively. An atmospheric leaching test was done with the variables of acid concentration, leaching duration of 90 min, and leaching temperature of 100℃. Limonite ore samples contain goethite, gibbsite, talc, quartz, and lizardite. It was revealed that as much as 92.22% of Ni and 90.14% of Fe could be leached using 3 M HCl, whereas only 63.14% of Ni and 38.74% of Fe could be extracted from limonite ore using 3 M HNO3. The higher leaching degree of Fe in HCl indicates low selectivity with Ni, which might contaminate pregnant leach solution (PLS), leading to further complications in the purification process. Results of the leaching experiment show that goethite was more easily dissolved in HCl than in HNO3.

Experimental and rheological modelling on the stabilization of iron ore slurry using a biosurfactant extracted from Aloe barbadensis Miller

The pipeline transportation of iron ore slurry (IOS) is an eco-friendly alternate mode to transport the raw materials to longer distance and reduce the transportation network congestion problems. Proper selection of surfactant could modify mineral’s viscosity, dispersion and wetting characteristics effectively as may be desired, which may further be monitored. A surfactant alters surface characteristics after being adsorbed onto minerals by altering the interfacial behaviour. This work is first report of the influence of a biosurfactant sourced from Aloe barbadensis Miller on the rheological behaviour of a high-grade iron ore (IO) sample at 45–72% by mass slurry concentrations range. The observed rheological parameters confirmed the non-Newtonian flow behaviour of the slurry. The collected IO and dried IOS samples were subjected to UV-Vis, XRF, PSD, XRD, SEM and EDS analyses. Experimental rheological data at varying concentrations was tested on various models to ascertain the best-fit rheological model for IOS transport. The Bingham model was found to be the most suitable to model the rheology of IOS. Experimental rheological behaviour of IOS was found to be linear with the yield stress. The study shall help to ascertain the suitability of a biosurfactant to stabilise high grade iron ores for pipeline transportation.
 KEY WORDS: Iron ore slurry, Aloe barbadensis, Rheological measurements, Rheological modelling
 Bull. Chem. Soc. Ethiop. 2024, 38(3), 615-629.                                                              
 DOI: https://dx.doi.org/10.4314/bcse.v38i3.6                         

Principal component analysis of mineral and element composition of ores from the Bayan Obo Nb-Fe-REE deposit: Implication for mineralization process and ore classification

The Bayan Obo Nb-Fe-REE polymetallic deposit in northern China is the world’s largest light REE deposit. The deposit was formed through multiperiodic alteration and mineralization, and thus mineral species and assemblages are extremely complex. To date, there is still no consensus on the classification of ore types, and research on the paragenetic association of minerals is still inadequate. Eighty ore samples are divided into seven types according to altered minerals, including dolomite, iron oxide, aegirine, riebeckite, biotite, fluorite, and barite types. These samples were analyzed by a TESCAN Integrated Mineral Analyzer (TIMA) for their mineral and element composition. The data set was investigated by principal component analysis (PCA) to reveal the mineralization and alteration information and classify the ores.PCM1 to PCM3 and PCE1 to PCE3 represent the first three principal components for PCA results of minerals and elements, respectively. The results indicate that PCM1 may distinguish rare earth mineralization from barite and silicification alteration that is associated with the latest fluids. PCM2 can distinguish mineralization and alteration associated with Nb from those associated with REE. The combination of PCM2 and PCE1 indicates that the precipitation of REE may be closely related to fluorination and phosphate, while the combination of PCM2 and PCE3 indicates that the Nb mineralization may be more closely related to alteration of riebeckite and biotite, as well as to Ti-rich fluids. In addition, PCM3 distinguishes the Th mineralization and associated fluorination from other alteration and mineralization. Based on PCA results, the above seven ore types can be classified into three types: dolomite REE ore, Fe-REE-F ore, and Nb-rich ore, which provides a simplified and comprehensive classification for Bayan Obo ores. PCA-based approach combining geochemical and mineralogical data can quickly identify ore types, which is helpful in mineral exploration.

Monazite and zircon U[sbnd]Pb and muscovite 40Ar/39Ar geochronology constraints on the timing of magmatism and mineralization in the Huxingshan tungsten deposit, South China

The Huxingshan W deposit (0.21 Mt. WO3 @ 0.3 %) in northeastern Hunan province is located at the western margin of the Jiangnan tungsten belt (JNB), South China. It consists of a series of magma-derived scheelite-quartz-muscovite (SQM) veins in the F1 fault (which contains over 60 % of the W resource), beneath Niutitang Formation (Fm.) carbonate rocks, and above Yijiaqiao Fm. slate (sub-economic), distal from the concealed two-mica granite, which is thought to be responsible for the tungsten mineralization. In this study, we employ LA-ICP-MS zircon and monazite UPb, and muscovite 40Ar/39Ar dating to constrain the timing of magmatism and W mineralization at the Huxingshan deposit. Monazite and zircon dating yield coeval ages of 137.6 ± 0.5 Ma and 138.0 ± 0.5 Ma, respectively. Our muscovite 40Ar/39Ar dating yielded well plateau ages of 132.9 ± 0.6 Ma, 132.2 ± 0.6 Ma, 130.7 ± 0.5 Ma, and 129.7 ± 0.6 Ma for four representative SQM vein ore samples occurring in the Niutitang Fm. carbonate, F1 fault, and Yijiaqiao Fm. slate, indicating multiple pulses of ore-forming fluid infiltration at Huxingshan. Our age data demonstrate that the two-mica granite emplaced at ∼137.6 Ma, significantly earlier than the pulsed W mineralization at ca. 132.9–129.7 Ma. The lack of spatial and temporal association precludes any genetic link between them. Thus, we infer that the ore-forming fluids likely originated from undiscovered deep plutons and ascended through the F1 fault. Besides, our reliable ages coincide with the two periods of large-scale Mesozoic magmatism and W mineralization phases in the JNB, with the 137.6 Ma magmatism falling within the first phase (150–135 Ma), while the W mineralization (ca.132.9–129.7 Ma) falls within the second phase (130–125 Ma). Of which, the second phase, including the Huxingshan, Xianglushang, Dongping, and Jianfengpo deposits, are situated in the western JNB and show further potential in this region.

Study of the material composition of refractory gold-bearing ore from the Aktobe deposit

The study of the material composition of gold-bearing ores includes the determination of quantitative chemical and mineral composition, forms of noble metals, granulometric composition, and physical and mechanical properties to choose the direction for the development of an effective technology of their complex enrichment. This work is devoted to the study of the material composition of refractory gold-bearing ore of Aktobe deposit. It was determined that the content of gold is 1.55-1.6 g/t, the mass fraction of silver is 42-43 g/t, and the content of sulphur is low and is 1-1.1% respectively. Of non-ferrous metals, zinc 0.17%, and lead 0.15% are present in insignificant amounts, and the content of harmful impurities antimony and arsenic are insignificant and amounted to 0.01 and 0.05%. The ore sample has a relatively uncomplicated mineral composition: rock-forming minerals represented by quartz, potassium feldspar, calcite, and mica predominate significantly. Ore minerals are represented by pyrite up to 10 %, limonite up to 0.5 %, galena 0.15-0.2 %, sphalerite 0.17-0.2 % and gold. Physical and mechanical properties of the ore were determined. According to the category of crushability, the ore belongs to the category of medium hardness. According to Bond's method, the "index of network Wi" of ball milling was determined for the initial ore, which was 19.3 kW∙h/t∙μm0.5. Based on the obtained data on the study of material composition, further research will be directed to the study of gravity and flotation enrichment.

Research on the possibility of obtaining medium-carbon ferromanganese from the Djezdinskoe deposit

In this article, the results of laboratory studies on the smelting of medium-carbon ferromanganese using Djezdinskoe ores are presented. Kazakhstan has significant reserves of manganese ores represented by iron-manganese and carbonate-oxide ores. The manganese ores of the Djezdinskoe deposit are characterized by a relatively high manganese content (48%) and low iron content (2-5%). Sieve analysis was used to study the particle size distribution of the ore. Based on the results of the sieve analysis of ore samples obtained after sieving, a high manganese content (53.54%), low iron content (0.47%), and silicon dioxide content (2.25%) were identified. Laboratory experiments were conducted on smelting medium-carbon ferromanganese in the high-temperature Tamman furnace. According to the results of the laboratory experiments, it is recommended to use the size classes of -5.0 + 0.0 mm to obtain high-quality low-phosphorus silicon-manganese alloy and the size class of +5.0 to produce medium-carbon ferromanganese. The average chemical composition of the metal and slag is as follows: % Mn – 86 – 88; Si – 0.04 – 0.35; Fe – 1.78 – 2.0; P – 0.06 – 0.09; C – 1.5 – 2.0; MnO – 19-20; SiO2 – 13.94-14.5; CaO – 23.35 – 24.85; MgO – 13.25-14.0. Thus, an optimal technological scheme has been developed for the production of a wide range of manganese ferroalloys.

Prevention of Silica Gel Formation for Eudialyte Study Using New Digestion Reactor

This work includes a combined hydrometallurgical treatment of a eudialyte ore sample with a subsequent preparation of leaching residue using mechanical separation methods. Hydrometallurgical treatment contains dry digestion with sulphuric acid at room temperature and filtration of the obtained product. The objectives of adopting these procedures are to test a new digestion reactor in order to prevent silica gel formation from the eudialyte ore. The obtained results revealed that silica gel formation is prevented during dissolution with sulphuric acid. A high leaching efficiency of light rare earth elements (La, Ce, Nd, Y) was reached using the dry digestion process with sulphuric acid, where the starting molarity was 12 mol/L. After the filtration process, magnetic separation is studied as the main method to recover weakly magnetic minerals like amphiboles and pyroxenes from the leaching residue in the magnetic fraction and feldspars in the nonmagnetic fraction. A new combined research strategy was developed for the production of different concentrates such as the one bearing Zr, Hf, and Nb.

Studying Flotation of Gold Microdispersions with Carrier Minerals and Pulp Aeration with a Steam–Air Mixture

This work is aimed at obtaining new knowledge in the field of interactions of polydisperse hydrophobic surfaces in order to increase the extraction of mineral microdispersions via flotation. The effect of high velocity and the probability of aggregating fine particles with large ones are used to increase the extraction of finely dispersed gold in this work. Large particles act as carrier minerals, which are intentionally introduced into a pulp. The novelty of this work lies in the fact that a rougher concentrate is used as the carrier mineral. For this purpose, it is isolated from three parallel pulp streams by mixing the rougher concentrate, isolated from the first stream of raw materials, with an initial feed of the second stream; accordingly, the rougher concentrate of the second stream is mixed with the initial feed of the third stream, and the finished rougher concentrate is obtained. In this mode of extracting the rougher concentrate, the content of the extracted metal increases from stream to stream, which contributes to the growth in its content in the end product. Moreover, in order to supplement forces involved in the separation of minerals with surface forces of structural origin in the third flotation stream, the pulp is aerated for a short time (about 15%–25% of the total) with air bubbles filled with a heat carrier, i.e., hot water vapor. Within this accepted flotation method, the influence that the surface currents occurring in the wetting film have on its thinning and breakthrough kinetics is proposed to be in the form of a correction to a length of a liquid slip in the hydrophobic gap. The value of the correction is expressed as a fraction of the limiting thickness of the wetting film, determined by the condition of its thickness invariability when the streams are equal in an interphase gap: outflowing (due to an action of the downforce) and inflowing (Marangoni flows and a thermo-osmotic stream). Gold flotation experiments are performed on samples of gold-bearing ore obtained from two deposits with conditions that simulate a continuous process. Technological advantages of this developed scheme and a flotation mode of gold microdispersions are shown in comparison with the basic technology. The purpose of this work is to conduct comparative tests on the basic and developed technologies using samples of gold-bearing ore obtained from the Natalka and Olimpiada deposits. Through the use of the developed technology, an increase in gold extraction of 7.99% and in concentrate quality (from 5.09 to 100.3 g/t) is achieved when the yield of the concentrate decreases from 1.86 to 1.30%, which reduces the costs associated with its expensive metallurgical processing.

Speciation of the binary Cr(III)-citrate system in the leachate samples of phosphate ore

This report focuses on the determination of chromium chemical forms in the lixiviates of phosphate ore using speciation modelling with the MATLAB 7.7 Language. Citric acid has been used as aleaching agent for the extraction of chromium (III) from phosphate ore. A computational approach was used to determine the concentration of differentionic species present in the Cr(III)-citric acid system. The results show that the main aqueous species identified in the systemwere both free and complex ions. In addition, it was found that the concentration of total chromium in the leachate was dependent on the concentration of citric acid.On the other hand, the formation of different species and the evolution of their concentration led to an increase in the ionic strength of the solution. The ionic complex CrHCit+ showed the highest activity coefficientamong the different Cr (III) species. It was also observed that free ionic species (H3O+, H2Cit-, Cr3+) have a higher activity than chromium ionic complexes (CrH3Cit3+, CrH2Cit2+, CrHCit+).

Mitigating the influence of topographies on hyperspectral images for the sorting of iron ore based on variational mode decomposition and spectral property

Hyperspectral imaging (HSI) can be applied for the purpose of sorting iron ores with varying total iron (TFe) content. However, the surface topographies of iron ore can negatively impact its hyperspectral images, consequently affecting the sorting effectiveness for each individual piece of iron ore. To address this issue, this study conducted an experiment on hyperspectral image of the iron ores. Firstly, variational mode decomposition (VMD) was employed to decompose the spectra of iron ore into trend signals and peak-valley signals. The two signals were then used for the calculation of three spectral properties (baseline-shift level, steepness level, and amplitude level). To identify the critical property capable of distinguishing normal spectra and the topographies-affected, the difference of the three spectral properties between the topographies-affected and the normal spectra were analyzed. According to the analysis results, a VMD-based correction model (VMDC) was proposed, which aims to identify the topographies-affected spectra in an ore and then correct them to resemble the normal spectra. Finally, the coefficient of variation (CV) for the correction was assessed and a test was conducted for TFe content prediction and sorting of each piece of iron ore. There are three primary conclusions summarized as follows:1. The mean Jeffries–Matusita distance (JMD) of baseline-shift level, steepness level, and amplitude level between normal spectra and topographies-affected spectra were 1.889, 1.307, and 1.170, respectively. This implies that baseline-shift level can be regarded as a key property for distinguishing whether a spectrum is topographies-affected or not. 2. After correction, there was a noticeable improvement in the topographies-affected areas of the ore samples, and the topographies-affected spectra showed the consistence with the normal spectra. Upon examination, the mean CV for VMDC is 0.115, whereas the uncorrected data has a mean CV of 0.315, indicating a reduction in spectral variability after VMDC correction. The results demonstrate the effectiveness of VMDC in mitigating the impact of topographies. 3. In the TFe content prediction and sorting, VMDC consistently demonstrates the best performance, for example when using RF as the regressor, coefficient of determination (R2) and accuracy of Original Data-RF, MSC-RF and VMDC-RF were 84.3% and 0.894, 86.7% and 0.903, and 88.7% and 0.921. The evaluation results confirm that VMDC can improve iron ore sorting. Overall, the proposed method shows potential for practical applications in iron ore sorting.

Rapid Determination Of Uranium In Ore Samples By Online Extraction Coupled ICP-MS

Rapid Determination Of Uranium In Ore Samples By Online Extraction Coupled ICP-MS

Use of backscattering ultrasound parameters for iron ore varieties recognition

Purpose. Development of the method for recognizing the main mineral-technological varieties of iron ore in the deposits being developed by selecting an analytical model for the spectral characteristics of the received ultrasonic echo signals and quantitative assessment of their parameters. Methodology. The work uses methods for modeling the processes of propagation of ultrasonic waves in a randomly heterogeneous medium. The process of backscattering of ultrasound in mineral structures formed by inclusions of iron ore of various varieties and associated rock was considered. The estimated parameters of the spectral characteristics of the inversely scattered probing ultrasound pulse were studied. Findings. A method for recognizing the main mineral and technological varieties of iron ore of the deposit being developed, based on the parameters of the propagation of ultrasonic waves in the studied samples, was proposed. This is achieved by selecting an analytical model for the spectral characteristics of the received echo signals and quantifying their parameters. The amplitude of the echo signal and its spectral properties depends on the size and concentration of the scatterers, i.e., the structural and textural features of the iron ore sample under study. Taking into account these factors, the extracted parameters of the model were used to identify the main mineralogical and technological varieties of iron ore of the studied deposit. Originality. The proposed method for recognizing mineral-technological varieties of iron ore differs from the known ones in that the amplitude, central frequency, and bandwidth of the amplitude spectrum of the Gaussian parametric model of the measured echo signals are used as evaluation parameters. Practical value. The proposed scientific and technical solution allows for operational non-destructive control of the main mineralogical and technological types of iron ore in the process of its extraction and processing.