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Chemical looping combustion (CLC) has been validated as one of the most promising technologies for fossil fuel combustion, which can produce high-purity CO2 streams ready for capture and sequestration in power production. The selection of an appropriate oxygen carrier is one of the most important issues for the CLC process, and the reduction kinetics investigation of the oxygen carrier with fuel gas can provide the basis for CLC reactor design and simulation optimization. In this study, copper ore was chosen as an oxygen carrier, and the oxygen release property of copper ore under a nitrogen environment at various temperatures (1073–1193 K) was first investigated in a thermogravimetric analyzer (TGA). Subsequently, the reduction kinetics of copper ore with CO and H2 were evaluated by the TGA at temperatures ranging from 773 K to 1073 K, using a continuous stream of 5, 10, 15, 20, 25, and 30 vol. % of CO or H2 balanced by CO2 or N2. It was found that the reaction rates of these reactions accelerated with the increase in temperature and fuel gas concentration in inlet gas. Both the oxygen release process of copper ore and the reduction process of copper ore with reducing gases can be described by the unreacted shrinking core model (USCM). The reaction mechanism function for the oxygen-releasing and reduction process of copper ore oxygen carrier was varied. The activation energy of the oxygen-releasing process, reduction process with CO, and reduction process with H2 were calculated as 99.35, 5.08, and 4.28 kJ/mol, respectively. The pre-exponential factor ranged from 1.96 × 10−1 to 1.84 × 103. The reaction order depended on the fuel gas, which was 1 and 0.86, respectively, for reaction with CO and H2. [ABSTRACT FROM AUTHOR]

The present article emphasizes the influence of forest vegetation on improving the content of toxic elements from soil, increasing the content of micro and macro elements as well as correlating these variations with characteristics of forest vegetation from the studied areas—Moldova Nouă waste heaps, South-West Romania. The research involved comparing and observing the differences in the content of micro, macro, and toxic elements (Fe, Pb, Zn, and Cd) between the soil of waste heaps from Moldova Nouă from areas with forest vegetation and the content of these elements analyzed 31 years ago during the projection of afforestation works, when forest vegetation was missing. The differences were correlated with stand characteristics of forest vegetation. We observed a significant increase for Fe and a significant decrease for Zn and Cd. The influence of forest vegetation of the variation on the soil's chemical composition was studied for the chemical elements that previously showed significant differences (Fe, Zn, and Cd). The averages of the statistically significant differences for the concentration of each analyzed element (Fe, Zn, and Cd) were correlated with the characteristics of the stands from the studied sampling points. The variation in time for Fe, Zn, and Cd and actual content of P, Cu, Mg were correlated especially with the average height of trees. [ABSTRACT FROM AUTHOR]

Chemical looping combustion (CLC) has been validated as one of the most promising technologies for fossil fuel combustion, which can produce high-purity CO2 streams ready for capture and sequestration in power production. The selection of an appropriate oxygen carrier is one of the most important issues for the CLC process, and the reduction kinetics investigation of the oxygen carrier with fuel gas can provide the basis for CLC reactor design and simulation optimization. In this study, copper ore was chosen as an oxygen carrier, and the oxygen release property of copper ore under a nitrogen environment at various temperatures (1073–1193 K) was first investigated in a thermogravimetric analyzer (TGA). Subsequently, the reduction kinetics of copper ore with CO and H2 were evaluated by the TGA at temperatures ranging from 773 K to 1073 K, using a continuous stream of 5, 10, 15, 20, 25, and 30 vol. % of CO or H2 balanced by CO2 or N2. It was found that the reaction rates of these reactions accelerated with the increase in temperature and fuel gas concentration in inlet gas. Both the oxygen release process of copper ore and the reduction process of copper ore with reducing gases can be described by the unreacted shrinking core model (USCM). The reaction mechanism function for the oxygen-releasing and reduction process of copper ore oxygen carrier was varied. The activation energy of the oxygen-releasing process, reduction process with CO, and reduction process with H2 were calculated as 99.35, 5.08, and 4.28 kJ/mol, respectively. The pre-exponential factor ranged from 1.96 × 10−1 to 1.84 × 103. The reaction order depended on the fuel gas, which was 1 and 0.86, respectively, for reaction with CO and H2.

The present article emphasizes the influence of forest vegetation on improving the content of toxic elements from soil, increasing the content of micro and macro elements as well as correlating these variations with characteristics of forest vegetation from the studied areas—Moldova Nouă waste heaps, South-West Romania. The research involved comparing and observing the differences in the content of micro, macro, and toxic elements (Fe, Pb, Zn, and Cd) between the soil of waste heaps from Moldova Nouă from areas with forest vegetation and the content of these elements analyzed 31 years ago during the projection of afforestation works, when forest vegetation was missing. The differences were correlated with stand characteristics of forest vegetation. We observed a significant increase for Fe and a significant decrease for Zn and Cd. The influence of forest vegetation of the variation on the soil’s chemical composition was studied for the chemical elements that previously showed significant differences (Fe, Zn, and Cd). The averages of the statistically significant differences for the concentration of each analyzed element (Fe, Zn, and Cd) were correlated with the characteristics of the stands from the studied sampling points. The variation in time for Fe, Zn, and Cd and actual content of P, Cu, Mg were correlated especially with the average height of trees.

The optimization of recovery of copper from Akiri hematite-dominated copper ore using hydrometallurgy was investigated in this study. The Akiri copper ore deposit hosts a high-grade copper mineral from which copper metal can be extracted. However, the ore is dominated by gangue minerals that need to be mechanically reduced for efficient copper recovery. The purpose of this study is to optimize the extraction of the metal from hematite-dominated copper ore. The experiments that were carried out in the course of this study include crushing, pulverization, mineralogical and chemical characterizations of the sample and sulpheric acid leaching. Response surface methodology was used to optimize the system parameters namely;temperature, concentration of the leachant and contact time so that an efficient method will be developed for the extraction of copper. Chalcopyrite, covellite and cuprite are the copper minerals while the gangues minerals were quartz, mica, hematite, etc. on the characterization of the copper ore. The major oxides in the ore are hematite, copper oxide and silica and revealed that the ore contains 4.61% copper and 65.8% iron. Effect of three independent factors like concentration, temperature and contact time for copper extraction from the hematite-dominated copper ore was studied. Central composite design method was applied to the proposed quadratic model that connect the factors used for best copper extraction at the best process condition. The work shows that concentration of the acid was the best efficient factor for copper extraction compare to temperature and contact time. This may be as a result of high value of F-statistics for the concentration of the leachant, which effects to high level of copper extraction. Experimental and predicted values for weight loss from the copper ore were obtained as 39.10% and 39.03% at optimum conditions, respectively. The optimum conditions of 1.5M acid concentration, 90oC reaction temperature and 90minutes contact time were obtained and from which 6.64%Cu at recovery of 92.0% and 2.31%Fe was obtained without stirring. Also, the ore was subjected to leaching with stirring at 400rpm with the optimum conditions obtained to know the effect. The grade obtained was 7.84%Cu at recovery of 83.51% and iron content 5.47%. This shows that leaching without stirring is the best option against leaching with stirring to extract the copper and to reduce the iron and other gangues contents in the copper ore. The activation energies were estimated as 13.20kJ/mol and 22.67kJ/mol for liquid film diffusion and diffusion product layer respectively, the values indicate that the leaching rate is controlled by diffusion process. [ABSTRACT FROM AUTHOR]

The high-pressure grinding roll (HPGR) has been known to achieve a high mineral liberation with relatively low energy consumption. However, quantitative methods for evaluating the effect of HPGR grinding on the promotion of the mineral liberation of copper ores have not been fully established. This study aims to establish a quantitative evaluation of promoting the liberation ratio of copper minerals by HPGR grinding. We performed clack observation using the combination of the paint penetration method and the mineral liberation analyzer (MLA). Direct clack observation reveals that HPGR grinding can promote the formation of cracks in the product particles. The liberation ratio of copper minerals is related to the percentage of cracks in the product particles. Besides, the grinding tests using a laboratory ultra-small scale showed that the liberation ratio of copper minerals became larger than that of the ball milling alone. In all conditions where HPGR grinding was conducted before ball milling, the ball milling time became almost half that of the ball milling alone. The grinding kinetic constant of the HPGR milling product in ball milling is also determined. The grinding kinetic constants for 80% passing particle size in HPGR grinding products are larger than that in feed ores, and they are consistent with the trend of ball milling time. This might be because the HPGR milling causes cracks in the particles, which are more easily ground in the subsequent ball milling. Consequently, this study demonstrates that the ratio of clacks and the grinding kinetic constant in the ball milling process after HPGR milling can be used as an index to quantitatively evaluate the effect of HPGR milling on promoting the liberation of copper minerals.

The moisture of bulk material has a significant impact on the energetic efficiency of dry grinding, resultant particle size distribution and particle shape, and conditions of powder transport. This research aims to develop computer vision and thermovision techniques for the on-site estimation of moisture content in copper ore, for use, e.g., in dry grinding installations. The influence of particle size on the results of moisture estimation is also studied. The tested granular material was copper ore of particle size 0–2 mm and relative moisture content of 0.5–11%. Both vision and thermovision images were taken at standard and macro scales. The results suggest that median-intensity vision images monotonically reflect copper ore moisture in the range of about 0.5–5%. Suitable models were identified and cross-validated here. In contrary, thermograms should not be analyzed simply for their mean temperature but treated with computer vision processing algorithms. [ABSTRACT FROM AUTHOR]

Since the start-up of the Sossego copper concentrator, located in the Carajás Mineral Province in the southeast of Para State, Brazil, the low-grade ore (~0.34% Cu) has been stockpiled, as defined in the long-term mine plan, to be reclaimed at the end of the mine life. Given this imminent need to process around 40 Mt of this low-grade ore, questions have been raised related to the extent of oxidation that might have occurred in this stockpiled ore. In this context, a study was designed to characterize the stockpiled ore and assess the effect of the ore oxidation on its flotation response. A sampling campaign of the stockpiled ore was carried out to analyze the main variables that could influence the level of oxidation, and, consequently, copper recovery, such as stockpiling time, depth, and particle size. The results showed that there are two main factors negatively impacting the copper recovery of the low-grade stockpiled ore: the surface oxidation and the level of liberation of the copper mineral. Depth and period of stockpiling were not found to influence the level of oxidation, nor the flotation response. An empirical model was proposed for the copper recovery in the rougher stage, which resulted in a predicted value of 90.7%, which was lower than that for the fresh (and higher copper content) ore fed to the plant (93%). [ABSTRACT FROM AUTHOR]

Crosswell electromagnetic (EM) methods are widely used in subsurface geophysical prospecting because they can achieve more effective long-distance detection than single-well methods. However, a large-diameter borehole is required to increase the magnetic moment of the magnetic dipole source. For the long-distance detection of copper ores, which is usually performed in slim holes, we present a borehole-surface current-injection-based crosswell EM logging method. Considering the cost of deploying casing, we inject a low-frequency ac directly into the ground, and converging current is formed around low-resistance anomalies in the formation. Then, the distribution of the anomalies can be inferred by detecting the low-frequency alternating magnetic field of the converging current in the receiver well. Moreover, to further improve the detection performance, we design a placement scheme for the grounding electrode for multianomaly crosswell detection based on the Gauss–Newton inversion algorithm, where the EM responses for different grounding electrode locations are analyzed. Field experiments are conducted using two slim open holes spaced approximately 1000 m apart for the detection of two copper ores. Through the processing and interpretation of measured EM signals, the conductivity imaging results of the crosswell EM method indicate that the measured distribution of anomalies is consistent with prior knowledge obtained from numerous single-well loggings, demonstrating the feasibility of the proposed application for long-distance crosswell EM logging in slim open holes.

A simple procedure for the synthesis of magnetic hybrid nanoparticles (MHNP) was developed by combining multi-walled carbon nanotubes modified by microwave energy and magnetic iron oxide nanoparticles. MHNP were introduced as sorbents in a magnetic solid phase extraction methodology for the total Arsenic determination in copper ore samples. Arsenic is penalized contaminant element in copper ores. Arsenic was determined by electrothermal atomic absorption spectrometry with a reduced temperature program. Arsenic adsorption corresponded to 96 - 104%, at ug g−1 levels. After a variable screening stage using a Placket-Burman (PBD) experimental design, the developed methodology was optimized using a Box-Behnken experimental design. Based on the optimal working parameters, a detection limit of 30 ng L−1 was reached, with a relative standard deviation of 7.1% and a preconcentration factor (PF) of 50. The Certified Geochem Base Metal Reference Material Product Code GBM900-10 was analyzed for the validation stage.

LCA (Life Cycle Assessment) is a useful tool in decision-making for most businesses that opt for sustainability and offers the possibility to compare different products, processes, and value chain scenarios, both real and hypothetical. Coupled with S-ROI (Sustainable Return on Investment), the LCA has a great potential in using available data for existing mining sites in the North-East Region of Romania to assess the economic, social and environmental benefits of certain sustainability measures on a local and regional level. The article will explore this approach of combining the two methodologies: LCA (Life Cycle Assessment) and S-ROI (Sustainable Return on Investment), with necessary adjustments according to the characteristics of the local mining activities, to show key investment areas that can improve the value chain of copper exploitation and preparation in the mining perimeter Mănăila. The case of the copper mine in Mănăila offers a great opportunity to apply the current LICYMIN (Life Cycle of Mining) research and to use available Ecoinvent data for the copper ore by comparing the current value chain scenario with a proposed scenario that includes a different location for a mining ore preparation unit, closer to the quarry. The results will give an insight into the potential social and economic impact (the measure can translate into a higher local employment rate, better social stability, lower transportation costs, etc.) as well as the environmental impact (reduction of GHG emission, pollution, and energy efficiency) of the suggested changes.

Combining iron and copper ores can generate an oxygen carrier that has a synergic effect of high temperature resistance and high reactivity. In this work, typical cements available in the market were studied as binders to bind magnetite and chalcopyrite to develop a suitable oxygen carrier for chemical-looping combustion (CLC). A first selection step suggested that an aluminate cement, namely CA70, could favor the generation of oxygen carrier particles having good crushing strength, good particle yield, and high reactivity. The CA70-bonded oxygen carrier was then subjected to cyclic tests with CH4, CO, and H2 in reduction and in air oxidation at temperatures of 850, 900, and 950 °C with gas concentrations of 5, 10, 15, and 20% in a batch-fluidized bed reactor. The increase in temperature promoted the fuel conversion. At 950 °C, the conversions of CH4 and CO reached up to 80.4% and 99.2%, respectively. During more than 30 cycles, the oxygen carrier kept a similar reactivity to the fresh carrier and maintained its composition and physical properties. The oxygen transport capacity was maintained at 21–23%, and the phases were CuO, Fe2O3, Al2O3, and minor CaS. In the used sample, some grains were observed, but the morphology was not greatly changed. Agglomeration was absent during all the cycles, except for the deep reduction with H2. [ABSTRACT FROM AUTHOR]

This paper describes the adopted approach for increasing the capacity of an existing industrial grinding circuit by adapting the respective configuration to process the ore from a new mine. Accordingly, due to Sossego mine exhaustion, Vale S. A. decided to use the existing industrial facilities and infrastructure for processing the Cristalino ore deposit located in Para state, within the Brazilian Amazon. Considering the higher hardness of Cristalino ore compared to Sossego ore, a reduction in capacity in the existing SAG grinding circuit was anticipated. A comprehensive grinding pilot plant campaign was conducted with a characterization program including 98 Cristalino ore samples, as described throughout this paper. Sossego grinding circuit was also surveyed for mathematical modeling and simulations to assess such an estimative further. The mathematical model calibration for setting different circuit configurations and operating conditions to enhance the circuit's capacity was based on the combination of pilot plant results and ore characterization. Simulations indicated that a capacity increase of 12% would be achieved in the existing grinding circuit by further crushing 35% of SAG mill fresh feed. Such figures would represent yearly additions of 8.3 kt in copper and 250 kg in gold productions. [ABSTRACT FROM AUTHOR]

In recent years, studies have shown that bubble structure, which is affected by reagent types, dosages, and particle size, is closely related to flotation performance. In contrast to two-phase systems, there is very limited information regarding bubble size in three-phase systems. To this aim, we investigated the relationship between bubble size and flotation performance with two different copper ores. Firstly, the surface tension and bubble size measurements were carried out in two-phase systems with Methyl isobutyl carbinol, and Polypropylene glycol methyl ether. Then the bubble size measurements were performed in three-phase systems at laboratory and industrial scales. The results showed that surface tension decreased with higher frother amounts and higher pHs. Although remarkable decreases in bubble size were observed with increasing frother amount, a direct relationship between surface tension and bubble size was not observed. However, pH affected the behavior of the frother, resulting in smaller bubble sizes at pH 12 compared to pH 7. Similarly, the three-phase laboratory tests showed that higher amount of frother caused a reduction in the bubble size and the copper grade. Increasing the amount of collector also caused the bubble size and copper grade to decrease, but the frothers were more effective in bubble size reduction. Compared to the two-phase, in the three-phase study bubble size was notably bigger due to the presence of a collector and solid. In the plant scale, smaller bubble size and higher grade were obtained compared with the laboratory scale due to presence of cleaning circuit measurements. The froth phase properties were also affected by the ore types due to properties such as size and hydrophobicity of the various mineral species present. [Display omitted] [ABSTRACT FROM AUTHOR]

The global market has announced copper as a modern energy metal and finds its extensive utilization in the construction industry, electrical wiring, power transmission lines, alloying, anticorrosive coating, heat exchangers, refrigeration tubing, etc. Copper ore is primarily beneficiated from sulphide mineral deposits. Due to high-grade copper sulphide deposit exhaustion, the focus has now shifted towards recovery from different lean-grade oxide and mixed ore deposits. The present paper summarizes the utilization of copper as a clean energy mineral and its importance in the current renewable energy sector. Extensive research has been carried out on the flotation of copper sulphide ore as compared to copper oxide and mixed type ores. Besides flotation, other beneficiation techniques (selective flocculation and gravity separation) are also discussed in the present review. A few novel pretreatment methods are currently being studied for copper ore to intensify the separation for higher productivity. [ABSTRACT FROM AUTHOR]

Blasting and fracking of rock in mines exposes fresh rock surfaces to the local water and microbial communities. This may lead to leaching of metals from the rock by chemical or biological means and can cause acidification of the water system in the mine, i.e., acid rock drainage (ARD). Failure to prevent leakage of metal contaminated mine water may be harmful for the environment, especially to the local groundwater. In the Rudna mine, Poland, an in situ bioleaching pilot test at approximately 1 km depth was performed in the H2020 BIOMOre project (Grant Agreement #642456). After the leaching stage, different methods for irreversible inhibition of acidophilic iron oxidizing microorganisms used for reoxidation of reduced iron in the leaching solution were tested and were shown to be effective. However, the potential of the natural mine water microbial communities to cause leaching of copper or acidification of the mine waters has not been tested. In this study, we set up a microcosm experiment simulating the exposure of freshly fractionated Kupferschiefer sandstone or black schist to two different chloride-rich water types in the Rudna mine. The pH of the microcosms water was measured over time. At the end of an 18-week incubation, the bacterial community was examined by high throughput sequencing and qPCR, and the presence of copper tolerant heterotrophic bacteria was tested by cultivation. The dissolution of copper into the chloride rich microcosm water was measured. The pH in the microcosms did not decrease over the time of incubation. The sandstone increased the number of bacteria in the microcosms with one or over two orders of magnitude compared to the original water. The bacterial communities in the two tested mine waters were diverse and similar despite the difference in salinity. The bacterial diversity was high but changed in the less saline water during the incubation. There was a high content of sulphate reducing bacteria in the original mine waters and in the microcosms, and their number increased during the incubation. No acidophilic iron oxidizers were detected, but in the microcosms containing the less saline water low numbers of Cu tolerant bacteria were detected. Copper to a concentration of up to 939 mg L−1 was leached from the rock also in the microbe-free negative controls, which was up to 2.4 times that leached in the biotic microcosms, indicating that the leaching was also abiotic, not only caused by bacteria. [ABSTRACT FROM AUTHOR]

The paper includes the results of laboratory studies for the copper-bearing ore flotation with the use of a combined reagent. The combined flotation reagent was preliminarily passed through a UZDN-A1200T ultrasonic disperser before flotation to obtain a reagent microemulsion. The copper content in the concentrate was 21,5 % with extraction of 83,3 % in a closed cycle in the base mode. It was 21,8 % with an extraction of 88,3 % when a combined flotation reagent was used. There is an increase in copper extraction by 5 %. The combined reagent consumption is reduced by 15 % compared to the main technology.

The early rejection of gangue minerals, at coarse ore particles size (preconcentration), has been shown to be a viable option to cost reduction in many mineral processing applications. A promising technique being explored for efficient ore preconcentration is the Near InfraRed (NIR) spectroscopy. This paper attempts to validate the efficiency of near infrared preconcentration strategies, by comparing data of preconcentrated particles, when particles are scanned using near line scanner from different sides and angle of view. Three copper particles were selected from a batch of sixty preconcentrated samples, mineralogical and near infrared analysis were performed on the particles. Particles were then cut laterally (cross sectioned) and mineralogical and near infrared analysis repeated on the cut cross sectioned surface. Data of the whole samples and crosssectioned samples are compared. Results indicate that the depth attained by scanning (both with NIR and QEMSCANr) of original samples is representative of each sample scanned and sufficient for preconcentration. Also, except for the differences in particle size, correlation is almost 1:1, thus, validating the initial NIR preconcentration results as being promising. [ABSTRACT FROM AUTHOR]

This paper presents the results of an industrial testing of the phase of rough flotation of copper ore from the deposit "North revir" in the Copper Mine Majdanpek. The achieved technological parameters in the rough flotation process, the results of grain size analysis by size classes of on the tested products, as well as the recovery and content of copper by size classes in the products of rough flotation show that the process of rough flotation does not work satisfactorily.

The early rejection of gangue minerals, at coarse ore particles size (preconcentration), has been shown to be a viable option to cost reduction in many mineral processing applications. A promising technique being explored for efficient ore preconcentration is the Near InfraRed (NIR) spectroscopy. This paper attempts to validate the efficiency of near infrared preconcentration strategies, by comparing data of preconcentrated particles, when particles are scanned using near line scanner from different sides and angle of view. Three copper particles were selected from a batch of sixty preconcentrated samples, mineralogical and near infrared analysis were performed on the particles. Particles were then cut laterally (cross sectioned) and mineralogical and near infrared analysis repeated on the cut cross sectioned surface. Data of the whole samples and cross-sectioned samples are compared. Results indicate that the depth attained by scanning (both with NIR and QEMSCAN(R) of original samples is representative of each sample scanned and sufficient for preconcentration. Also, except for the differences in particle size, correlation is almost 1:1, thus, validating the initial NIR preconcentration results as being promising.

Since the start-up of the Sossego copper concentrator, located in the Carajás Mineral Province in the southeast of Para State, Brazil, the low-grade ore (~0.34% Cu) has been stockpiled, as defined in the long-term mine plan, to be reclaimed at the end of the mine life. Given this imminent need to process around 40 Mt of this low-grade ore, questions have been raised related to the extent of oxidation that might have occurred in this stockpiled ore. In this context, a study was designed to characterize the stockpiled ore and assess the effect of the ore oxidation on its flotation response. A sampling campaign of the stockpiled ore was carried out to analyze the main variables that could influence the level of oxidation, and, consequently, copper recovery, such as stockpiling time, depth, and particle size. The results showed that there are two main factors negatively impacting the copper recovery of the low-grade stockpiled ore: the surface oxidation and the level of liberation of the copper mineral. Depth and period of stockpiling were not found to influence the level of oxidation, nor the flotation response. An empirical model was proposed for the copper recovery in the rougher stage, which resulted in a predicted value of 90.7%, which was lower than that for the fresh (and higher copper content) ore fed to the plant (93%).

The moisture of bulk material has a significant impact on the energetic efficiency of dry grinding, resultant particle size distribution and particle shape, and conditions of powder transport. This research aims to develop computer vision and thermovision techniques for the on-site estimation of moisture content in copper ore, for use, e.g., in dry grinding installations. The influence of particle size on the results of moisture estimation is also studied. The tested granular material was copper ore of particle size 0–2 mm and relative moisture content of 0.5–11%. Both vision and thermovision images were taken at standard and macro scales. The results suggest that median-intensity vision images monotonically reflect copper ore moisture in the range of about 0.5–5%. Suitable models were identified and cross-validated here. In contrary, thermograms should not be analyzed simply for their mean temperature but treated with computer vision processing algorithms.

The verification efficiency and precision of copper ore grade has a great influence on copper ore mining. At present, the common method for the exploration of reserves often uses chemical analysis and identification, which have high costs, long cycles, and pollution risks but cannot realize the in situ determination of the copper grade. The existing scalar spectrometric techniques generally have limited accuracy. As a vector spectrum, polarization state information is sensitive to mineral particle distribution and composition, which is conducive to high-precision detection. Taking the visible-near infrared parallel polarization reflectance spectrum data and grade data of a copper mine in Xiaoyuan village, Huaining County, Anhui Province, China, as an example, the characteristics of the parallel polarization spectra of the copper mine were analyzed. The spectra were pretreated by first-order derivative transform and wavelet denoising, and the dimensions of wavelet denoising spectra, parallel polarization spectra, and first-order derivative spectra were also reduced by principal component analysis (PCA). Three, four, and eight principal components of the three types of spectra were selected as variables. Four machine learning models, the radial basis function (RBF), support vector machine (SVM), generalized regression neural network (GRNN), and partial least squares regression (PLSR), were selected to establish the PCA parallel polarization reflectance spectrum and copper grade prediction model. The accuracy of the model was evaluated by the determination coefficient (R2) and root mean square error (RMSE). The results show that, for parallel polarization spectra, first-order derivative spectra, and wavelet denoising spectra, the PCA-SVM model has better results, with R2 values of 0.911, 0.942, and 0.953 and RMSE values of 0.022, 0.019, and 0.017, respectively. This method can effectively reduce the redundancy of polarized hyperspectral data, has better model prediction ability, and provides a useful exploration for the grade analysis of hydrothermal copper deposits at meso-low temperatures.

The paper includes the results of laboratory studies for the copper-bearing ore flotation with the use of a combined reagent. The combined flotation reagent was preliminarily passed through a UZDN-A1200T ultrasonic disperser before flotation to obtain a reagent microemulsion. The copper content in the concentrate was 21,5 % with extraction of 83,3 % in a closed cycle in the base mode. It was 21,8 % with an extraction of 88,3 % when a combined flotation reagent was used. There is an increase in copper extraction by 5 %. The combined reagent consumption is reduced by 15 % compared to the main technology. [ABSTRACT FROM AUTHOR]

LCA (Life Cycle Assessment) is a useful tool in decision-making for most businesses that opt for sustainability and offers the possibility to compare different products, processes, and value chain scenarios, both real and hypothetical. Coupled with S-ROI (Sustainable Return on Investment), the LCA has a great potential in using available data for existing mining sites in the North-East Region of Romania to assess the economic, social and environmental benefits of certain sustainability measures on a local and regional level. The article will explore this approach of combining the two methodologies: LCA (Life Cycle Assessment) and S-ROI (Sustainable Return on Investment), with necessary adjustments according to the characteristics of the local mining activities, to show key investment areas that can improve the value chain of copper exploitation and preparation in the mining perimeter Mănăila. The case of the copper mine in Mănăila offers a great opportunity to apply the current LICYMIN (Life Cycle of Mining) research and to use available Ecoinvent data for the copper ore by comparing the current value chain scenario with a proposed scenario that includes a different location for a mining ore preparation unit, closer to the quarry. The results will give an insight into the potential social and economic impact (the measure can translate into a higher local employment rate, better social stability, lower transportation costs, etc.) as well as the environmental impact (reduction of GHG emission, pollution, and energy efficiency) of the suggested changes. [ABSTRACT FROM AUTHOR]

The foothills of the North-Western Kuznetsky Alatau are considered as the copper-ore base of the Tagar archaeological culture. The paper introduced some published data on copper deposits on the banks of the river Kia and the bordering area of the Kuznetsky Alatau. Map-marking revealed the geographical the connection between the Koghuh tectonic area, the Central-Martaiga structure-formaton area, and the Tagar archaeological sites. The research registered the known settlements on the Kemerovo region territory with signs of the bronze industry (copper-bronze artifacts, tools for ore crushing, slag) related to Tagar and transitional Tagar-Tashtik Epoch. The peculiarities of such sites demonstrated the localization of the bronze industry process in the some fortified and stable settlements. The comparison of geochemical admixtures revealed the differences of copper-ore origin at the developed stage of Tagar culture and the transitional Tagar-Tashtik stage. This can be explained by the difference in geography of the sites as related to the copper deposits of North-Western, Northern, and North-Eastern Kuznetsky Alatau foothills. The authors believe that the banks of the Kia and its left tributaries, the Koghuh and the Kundat, can reveal some ancient copper mining archaeological sites in the future.

Combining iron and copper ores can generate an oxygen carrier that has a synergic effect of high temperature resistance and high reactivity. In this work, typical cements available in the market were studied as binders to bind magnetite and chalcopyrite to develop a suitable oxygen carrier for chemical-looping combustion (CLC). A first selection step suggested that an aluminate cement, namely CA70, could favor the generation of oxygen carrier particles having good crushing strength, good particle yield, and high reactivity. The CA70-bonded oxygen carrier was then subjected to cyclic tests with CH4, CO, and H2 in reduction and in air oxidation at temperatures of 850, 900, and 950 °C with gas concentrations of 5, 10, 15, and 20% in a batch-fluidized bed reactor. The increase in temperature promoted the fuel conversion. At 950 °C, the conversions of CH4 and CO reached up to 80.4% and 99.2%, respectively. During more than 30 cycles, the oxygen carrier kept a similar reactivity to the fresh carrier and maintained its composition and physical properties. The oxygen transport capacity was maintained at 21–23%, and the phases were CuO, Fe2O3, Al2O3, and minor CaS. In the used sample, some grains were observed, but the morphology was not greatly changed. Agglomeration was absent during all the cycles, except for the deep reduction with H2.

This paper describes the adopted approach for increasing the capacity of an existing industrial grinding circuit by adapting the respective configuration to process the ore from a new mine. Accordingly, due to Sossego mine exhaustion, Vale S. A. decided to use the existing industrial facilities and infrastructure for processing the Cristalino ore deposit located in Para state, within the Brazilian Amazon. Considering the higher hardness of Cristalino ore compared to Sossego ore, a reduction in capacity in the existing SAG grinding circuit was anticipated. A comprehensive grinding pilot plant campaign was conducted with a characterization program including 98 Cristalino ore samples, as described throughout this paper. Sossego grinding circuit was also surveyed for mathematical modeling and simulations to assess such an estimative further. The mathematical model calibration for setting different circuit configurations and operating conditions to enhance the circuit’s capacity was based on the combination of pilot plant results and ore characterization. Simulations indicated that a capacity increase of 12% would be achieved in the existing grinding circuit by further crushing 35% of SAG mill fresh feed. Such figures would represent yearly additions of 8.3 kt in copper and 250 kg in gold productions.

Scientifi c objective of this work was elaboration of radiometric method for the development of hydrometallurgical process for recovery of Cu from the copper ore. A neutron activation analysis (NAA) was identifi ed as a very convenient tool for the process investigation. The samples of copper ore were activated in a nuclear reactor. The parameters of the neutron activation were calculated. Radioisotope 64Cu was selected as an optimal tracer, and it was used for the investigation of the leaching process. During the experiments, various processes applying leaching media such as sulphuric acid, nitric acid, and organic acids were investigated. The recovery of the metals using sulphuric acid was insuffi cient, around 10%. Investigated organic media also did not meet expectations. The best results were obtained in experiments with nitric acid. Up to 90% of Cu and other metals were extracted from the copper ore. Copper concentration calculations obtained by NAA were confi rmed by inductively coupled plasma mass spectrometry (ICP-MS) technique. Both techniques gave comparable results, but the advantage of the NAA is a possibility for easy online measurements without shutting down or disturbing the system.

The global market has announced copper as a modern energy metal and finds its extensive utilization in the construction industry, electrical wiring, power transmission lines, alloying, anticorrosive coating, heat exchangers, refrigeration tubing, etc. Copper ore is primarily beneficiated from sulphide mineral deposits. Due to high-grade copper sulphide deposit exhaustion, the focus has now shifted towards recovery from different lean-grade oxide and mixed ore deposits. The present paper summarizes the utilization of copper as a clean energy mineral and its importance in the current renewable energy sector. Extensive research has been carried out on the flotation of copper sulphide ore as compared to copper oxide and mixed type ores. Besides flotation, other beneficiation techniques (selective flocculation and gravity separation) are also discussed in the present review. A few novel pretreatment methods are currently being studied for copper ore to intensify the separation for higher productivity.

Blasting and fracking of rock in mines exposes fresh rock surfaces to the local water and microbial communities. This may lead to leaching of metals from the rock by chemical or biological means and can cause acidification of the water system in the mine, i.e., acid rock drainage (ARD). Failure to prevent leakage of metal contaminated mine water may be harmful for the environment, especially to the local groundwater. In the Rudna mine, Poland, an in situ bioleaching pilot test at approximately 1 km depth was performed in the H2020 BIOMOre project (Grant Agreement #642456). After the leaching stage, different methods for irreversible inhibition of acidophilic iron oxidizing microorganisms used for reoxidation of reduced iron in the leaching solution were tested and were shown to be effective. However, the potential of the natural mine water microbial communities to cause leaching of copper or acidification of the mine waters has not been tested. In this study, we set up a microcosm experiment simulating the exposure of freshly fractionated Kupferschiefer sandstone or black schist to two different chloride-rich water types in the Rudna mine. The pH of the microcosms water was measured over time. At the end of an 18-week incubation, the bacterial community was examined by high throughput sequencing and qPCR, and the presence of copper tolerant heterotrophic bacteria was tested by cultivation. The dissolution of copper into the chloride rich microcosm water was measured. The pH in the microcosms did not decrease over the time of incubation. The sandstone increased the number of bacteria in the microcosms with one or over two orders of magnitude compared to the original water. The bacterial communities in the two tested mine waters were diverse and similar despite the difference in salinity. The bacterial diversity was high but changed in the less saline water during the incubation. There was a high content of sulphate reducing bacteria in the original mine waters and in the microcosms, and their number increased during the incubation. No acidophilic iron oxidizers were detected, but in the microcosms containing the less saline water low numbers of Cu tolerant bacteria were detected. Copper to a concentration of up to 939 mg L−1 was leached from the rock also in the microbe-free negative controls, which was up to 2.4 times that leached in the biotic microcosms, indicating that the leaching was also abiotic, not only caused by bacteria.

The paper shows the preparation of the numerical models necessary for the simulation mapping of industrial-scale crushers of problematic material, such as copper ore with complex lithology. The crushers investigated in this work are located in the KGHM Polska Miedz S.A. copper ore processing plant. The complex ore consisting of sandstone, dolomite and shale is modeled using the Discrete Element Method (DEM) with Particle Replacement Model (PRM) that was chosen to simulate the crushing process. The article discusses the tests and calibration of material parameters and proceeds to test a breakage model in a laboratory-scale jaw crusher. The results are finally validated with the data from actual industrial-scale crushers and compared with the simulations. As an optimization option, the new shape of hammers is proposed and tested in a numerical environment. The performance of the newly designed hammers was examined using numerical methods. The numerical tests showed that the new design performed worse than the current solution. As a result, time and money were saved by avoiding industrial tests. In conclusion, the work shows how complex processes can be characterized in the numerical environment and used for further analysis.

In this project the aim is the characterization and mineralogical studies of ROM ore by the XRF-XRD Technique for identification of minerals under polarizes microscope the study of ore minerals like Chalcopyrite, Pyrite, Hematite, Mica, etc., has been identified, the studies show that about 5% are opaque minerals. Mineralogical studies show that the major gangue minerals are such as Siderite, Quartz and Pyrite. Pyrite could be observed in the forms of dark mineral in polished specimens that include 10% of mineral, by counting it. Liberation studies indicate that +75 microns is the optimum liberation size and thus, recommended for flotation unit of the Rangin Flez plant.

The paper presents a way of combining neural networks with evolutionary algorithms in order to find optimal parameters of the copper flotation enrichment process. The neural network was used in order to build a model describing the flotation process. The network learning was carried out with the use of samples from previous empirical measurements of the actual process. The model created in this way made it possible to find optimal parameters not only from among the measurement spaces, but also those that go beyond the measurements. Then, evolutionary algorithms were used in order to find optimal flotation parameters. The learned neural network previously described was used to calculate the criterion in the evolutionary algorithm. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cost-effective raw materials can be used to prepare high-performance oxygen carriers. • Extrusion-spheronization is capable of scaling up for industrially produced oxygen carriers. • RCu-10 M oxygen carriers show sufficient stability, reactivity, and sintering resistance. • Tonnage-scale prepared oxygen carriers perform well in an interconnected fluidized bed. • The raw material cost of the Fe-Cu bimetallic oxygen carrier is 0.27 $/kg. It is crucial for the preparation of the high-performance and low-cost oxygen carrier (OC) in an industrial-scaled application to lay the foundation for the commercialization of chemical looping combustion (CLC) technology. In this work, a bimetallic OC (RCu-10 M) is prepared in an industrial-scaled extruder coupling with roller, composited by the red mud (aluminum industrial waste), copper ore and montmorillonite as raw materials. First, a thermogravimetric analyzer (TGA) is used to carry out 100 redox cycles using H 2 as the reducing agent. RCu-10 M OC demonstrate remarkable redox stability and sintering-resistance across multiple cycles, and the oxygen donating capacity do not diminish as the number of cycles increases. The effects of temperatures and excess oxygen coefficients on the reactivities of RCu-10 M OC with Shenhua bituminous coal are then investigated by using a batch fluidized bed reactor. RCu-10 M OC maintains high combustion efficiency, exceeding 94.7 % at 950 °C, with an excess oxygen coefficient of 2.0. Finally, a lab-scaled interconnected fluidized bed reactor is applied to examine the realistic performance of RCu-10 M OC using CH 4 fuel. The results demonstrate that the RCu-10 M OC successfully operates for ca. 100 min of continuous time, and there is no de-fluidization occurrence, and the bed pressure decrease is stable during operation, indicating that the RCu-10 M OC exhibits good fluidization properties and had the potential to be used in large-scale fluidized bed reactors. Further characterization data reveal that the chemical composition of RCu-10 M OC is stable throughout multiple cycles, as indicated by the almost uniform distribution of elements. [ABSTRACT FROM AUTHOR]

The documentary publication presents the materials of the Prikaz Kazanskogo Dvorca which give an idea of copper smelting business development in the Kazan district in the second half of the 17th century. The information contained in them allows us to take a fresh look at the history of the copper industry in Tatarstan.

Egyptians probably drew their first supplies of copper as native metal and step by step from the abundant malachite stones found in south Sinai region and in the hills near Red Sea in the eastern desert. There was integrated between the mines of copper and the mines of turquoise in the literature studies of south Sinai, especially in wadi El-Maghara, Wadi El-Nasib, Wadi Kharag and serabit El-Khadim, so this study tries to clear this point and determine exactly the mines of copper and the mines of turquoise. The study aims to investigate the source zones for copper in south Sinai, Egypt during the pharaonic ages, to determine the extent of a manufacturing centre and its position and to know the systems of metallurgical works, fire places, furnaces, etc. To achieve that the study had two main aspects: first, a serious survey to investigate of the mines of south Sinai was a cured; several different mining features were randomly chosen for excavation such as open cisterns, plates and galleries, collected every small things and fine details of the mining technology used at these sites. Secondly: Careful investigations by a serial of different analytical techniques for Ore and slag samples from the selected mines have been applied; the obtained information can be married up and exploited to determine exactly the main activity for each site.

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.

Egyptians probably drew their first supplies of copper as native metal and step by step from the abundant malachite stones found in south Sinai region and in the hills near Red Sea in the eastern desert. There was integrated between the mines of copper and the mines of turquoise in the literature studies of south Sinai, especially in wadi El-Maghara, Wadi El-Nasib, Wadi Kharag and serabit El-Khadim, so this study tries to clear this point and determine exactly the mines of copper and the mines of turquoise. The study aims to investigate the source zones for copper in south Sinai, Egypt during the pharaonic ages, to determine the extent of a manufacturing centre and its position and to know the systems of metallurgical works, fire places, furnaces, etc. To achieve that the study had two main aspects: first, a serious survey to investigate of the mines of south Sinai was a cured; several different mining features were randomly chosen for excavation such as open cisterns, plates and galleries, collected every small things and fine details of the mining technology used at these sites. Secondly: Careful investigations by a serial of different analytical techniques for Ore and slag samples from the selected mines have been applied; the obtained information can be married up and exploited to determine exactly the main activity for each site. [ABSTRACT FROM AUTHOR]

Effective comminution of copper ore for further processing during flotation is still a challenge, both as a technological problem as well as for the high energy costs of such processing.A high-pressure water jet is one alternative method of preparing copper ore for final flotation, causing distinct enlargement of the surface of micronized particles, which could be profitable for copper production.As a consequence of such innovative processing, particles of copper ore become micronized, ensuring grain fractions directly useful for flotation at the exit of the pulverizing apparatus (the hydro-jetting mill).The paper presents some results of simulation as well as describing an analysis of the phenomena occurring inside the high-pressure water and abrasive-water jets of specific structures, elaborated in the aspect of developing hybrid jets of maximum erosive efficiency, potentially useful for effective pulverization.

The article is concerned with methods of ragging and grinding of copper ore. The proposed electric pulse technology is one of the energetically favorable methods of ragging and grinding of natural minerals and anthropogenic raw materials. This paper presents optimal parameters in processing of the product. The results obtained by grinding of copper ore using the offered technology may be used under industrial conditions in the future.

Copper is an important national resource, which is widely used in various sectors of the national economy. The traditional detection of copper content in copper ore has the disadvantages of being time-consuming and high cost. Due to the many drawbacks of traditional detection methods, this paper proposes a new method for detecting copper content in copper ore, that is, through the spectral information of copper ore content detection method. First of all, we use chemical methods to analyze the copper content in a batch of copper ores, and accurately obtain the copper content in those ores. Then we do spectrometric tests on this batch of copper ore, and get accurate spectral data of copper ore. Based on the data obtained, we propose a new two hidden layer extreme learning machine algorithm with variable hidden layer nodes and use the regularization standard to constrain the extreme learning machine. Finally, the prediction model of copper content in copper ore is established by using the algorithm. Experiments show that this method of detecting copper ore content using spectral information is completely feasible, and the algorithm proposed in this paper can detect the copper content in copper ores faster and more accurately.

The paper presents a way of combining neural networks with evolutionary algorithms in order to find optimal parameters of the copper flotation enrichment process. The neural network was used in order to build a model describing the flotation process. The network learning was carried out with the use of samples from previous empirical measurements of the actual process. The model created in this way made it possible to find optimal parameters not only from among the measurement spaces, but also those that go beyond the measurements. Then, evolutionary algorithms were used in order to find optimal flotation parameters. The learned neural network previously described was used to calculate the criterion in the evolutionary algorithm.

When underground mining of Ural copper deposits with a chamber mining system, an urgent scientific and practical task is to increase the productivity of loadingdelivery machines for the ore drawing from secondary chambers. The technogenic disturbance of the massif of such chambers in combination with the non-alternative use of a blasthole ring scheme of breaking leads to an increased output of oversized fractions. With an increase of oversized ore output, operating costs for the drawing and delivery of ore increase, tire wear, fuel and lubricants consumption increases. In this article, the possibility of reducing the oversize ore output in secondary chambers by using counter blasting of the breaking layers is considered. As a result of the research, the parameters of effective counter blasting with blasthole ring charges were established, namely, the distance between the working faces in the chamber, the angle of ore pieces meeting and the line of least resistance.