Secondary Copper Research Articles

Effect of Fe/SiO2 Ratio and Fe2O3 on the Viscosity and Slag Structure of Copper-Smelting Slags

Secondary copper smelting is an effective means of treating waste resources. During the smelting process, the viscous behavior of the smelting slags is essential for smooth operation. Therefore, the effects of Fe/SiO2 ratio and Fe2O3 contents on the viscous behavior of the FeO−Fe2O3−SiO2−8 wt%CaO−3 wt%MgO−3 wt%Al2O3 slag system were investigated. The slag viscosity and activation energy for viscous flow decrease with increasing Fe/SiO2 from 0.8 to 1.2, and increase as the Fe2O3 content increases from 4 wt% to 16 wt% at Fe/SiO2 ratio of 1.2. However, under the conditions of Fe/SiO2 of 0.8 and 1.0, the viscosity and activation energy for viscous flow show a minimum value at Fe2O3 content of 12 wt%. Fe2O3 exhibits amphoteric properties. In addition, the increase in Fe2O3 content raises the breaking temperature of the slag, while the Fe/SiO2 ratio has the opposite effect. Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy show that increases in Fe/SiO2 ratio lead to simplification of the silicate network structure, while increases in Fe2O3 content improves the formability of the network. This study provides theoretical support for the related research and application of secondary copper smelting.

Flotation separation mechanism for secondary copper sulfide minerals and pyrite using novel collector ethyl isobutyl xanthogenic acetate

Ethyl isobutyl xanthogenic acetate (EIBXAC) was used as a novel collector in the flotation of secondary copper sulfide minerals owing to its ability to separate copper and sulfur. The collectivity and selectivity mechanisms of this novel collector were investigated using single-mineral and artificial mixed-mineral tests, combined with adsorption tests, fourier transform infrared spectroscopy (FTIR) tests, and density functional theory (DFT) calculations. The results of the flotation indicated that EIBXAC had a better collecting effect than ammonium dibutyl dithiophosphate (ADD) on covellite and digenite, which had an insignificant effect on pyrite. The artificial mixed-mineral experiment indicated that EIBXAC could improve the grade of the copper concentrate while maintaining the same recovery, it had higher efficiency and selectivity. Based on the results of the adsorption and FTIR tests, the adsorption capacities of EIBXAC on the surfaces of covellite, digenite, and pyrite were quite different: Cu-S bonds were formed on covellite and digenite, and Fe-O bonds were formed on pyrite, which was also verified that EIBXAC was chemically adsorbed on the mineral surface. DFT calculations indicated that the adsorption capacity of EIBXAC for covellite and digenite was stronger than that of ADD, which had a weaker adsorption capacity for pyrite. This study can provide theoretical guidance for the application of EIBXAC.

Hydrometallurgical Treatment of Converter Dust from Secondary Copper Production: A Study of the Lead Cementation from Acetate Solution

The subject of interest in this study was lead cementation with zinc from solution after conventional agitate acidic leaching of converter dust from secondary copper production. The kinetics of lead cementation from an acid solution of lead acetate using zinc powder was studied. The optimal cementation conditions for removing lead from the solution were determined to have a stirring intensity of 300 rpm, a zinc particle size distribution <0.125–0.4> mm and an ambient temperature. Under these conditions, an almost 90% efficiency in removing lead from solution was achieved. The cementation precipitate contains Pb, and a certain amount of Cu. Lead is present in the cementation precipitate in the PbO, Pb5O8 and Pb(Cu2O2) phases. The solution after cementation was also refined from copper. The solution can be used for further processing in order to obtain a marketable Zn-based product. The resulting cementation precipitate can be further processed and modified to obtain a lead-based product. A kinetic study of the process of lead cementation from solution was also carried out. Based on experimental measurements, the value of apparent activation energy (Ea) which was found to be ~18.66 kJ·mol−1, indicates that this process is diffusion controlled in the temperature range 293–333 K.

Industrial Heap Bioleaching of Copper Sulfide Ore Started with Only Water Irrigation

Sulfuric acid solution containing ferric iron is the extractant for industrial heap bioleaching of copper sulfides. To start a heap bioleaching plant, sulfuric acid is usually added to the irrigation solution to maintain adequate acidity (pH 1.0–2.0) for copper dissolution. An industrial practice of heap bioleaching of secondary copper sulfide ore that began with only water irrigation without the addition of sulfuric acid was successfully implemented and introduced in this manuscript. The mineral composition and their behavior related to the production and consumption of sulfuric acid during the bioleaching in heaps was analyzed. This indicated the possibility of self-generating of sulfuric acid in heaps without exogenous addition. After proving by batches of laboratory tests, industrial measures were implemented to promote the sulfide mineral oxidation in heaps throughout the acidifying stages, from a pH of 7.0 to 1.0, thus sulfuric acid and iron was produced especially by pyrite oxidation. After acidifying of the heaps, adapted microbial consortium was inoculated and established in a leaching system. The launch of the bioleaching heap and finally the production expansion were realized without the addition of sulfuric acid, showing great efficiency under low operation costs.

Leaching Chalcocite in Chloride Media—A Review

Chalcocite is the most abundant secondary copper sulfide globally, with the highest copper content, and is easily treated by conventional hydrometallurgical processes, making it a very profitable mineral for extraction. Among the various leaching processes to treat chalcocite, chloride media show better results and have a greater industrial boom. Chalcocite dissolution is a two-stage process, the second being much slower than the first. During the second stage, in the first instance, it is possible to oxidize the covellite in a wide range of chloride concentrations or redox potentials (up to 75% extraction of Cu). Subsequently, CuS2 is formed, which is to be oxidized. It is necessary to work at high concentrations of chloride (>2.5 mol/L) and/or increase the temperature to reach a redox potential of over 650 mV, which in turn decreases the thickness of the elemental sulfur layer on the mineral surface, facilitating chloride ions to generate a better porosity of this. Finally, it is concluded that the most optimal way to extract copper from chalcocite is, during the first stage, to work with high concentrations of chloride (50–100 g/L) and low concentrations of sulfuric acid (0.5 mol/L) at a temperature environment, as other variables become irrelevant during this stage if the concentration of chloride ions in the system is high. While in the second stage, it is necessary to increase the temperature of the system (moderate temperatures) or incorporate a high concentration of some oxidizing agent to avoid the passivation of the mineral.

Determination of the mineral composition of copper ores by X-Ray methods

One of the most difficult tasks of the analytical control of copper ores is the determination of the mineral forms of copper. Currently, for this purpose, iodometric and atomic absorption methods are used with preliminary leaching of various mineral forms. The disadvantage of those methods is a rather complicated sample preparation procedure and significant time of analysis. The most universal method for determining the mineral composition of solid samples is the X-ray diffraction method. However, significant variations in the phase composition of copper ores, overlapping reflections of different phases, the presence of an amorphous phase and structural defects necessitate the development of special approaches. In this work, the presence of an amorphous phase is taken into account by direct calculation of the mass fractions of crystalline phases by the G-factor method. The total copper content is determined by the X-ray fluorescence method. Methodological approaches based on using only X-ray methods are proposed, which exclude the procedures of leaching and dissolution of samples and provide determination of primary and secondary copper sulfides using calibration characteristics (3 min), and gaining data on the complete phase composition at the stage of routine analysis (10 – 15 min) and for research purposes (15 – 20 min).

Serum intracellular adhesion molecule-1 and interleukin-8 as predictors of pulmonary impairment among workers in secondary copper smelters

Copper smelter workers are exposed to harmful chemical agents in dust and fumes which contain harmful metals such as copper and arsenic. These substances are known to be respiratory irritants. This study aimed at investigating the effect of occupational exposure to copper and arsenic on the respiratory system. A group of 75 male exposed workers, and 75 male administrative employees (control group) were recruited from a secondary copper smelting factory. Full history, complete clinical examination, ventilatory function parameters (FVC, FEV1, FVC/FEV1 and FEF), and chest X-ray were done for both groups. Serum levels of ICAM-1 and IL8 (as markers of epithelial injury) were measured by ELISA. Serum copper and arsenic were measured by atomic absorption spectrophotometer. The exposed group was associated with increased respiratory symptoms, higher serum copper, arsenic, and ICAM-1and Il-8 as compared to the control group. There was a significant decrease in ventilatory parameters among the exposed group: 58.7% of the exposed group had restrictive lung impairment, 40% had obstructive impairment. In the exposed group a positive correlation between serum copper, arsenic and serum ICAM and IL8 was found. While a negative correlation was observed between both serum ICAM, IL8 and ventilatory parameters among the exposed group. Moreover, 36% of the exposed group had radiological infiltrates on chest X.ray. Occupational exposure to copper and arsenic was associated with ventilatory and radiological impairment, with a corresponding increase in the serum level of ICAM-1 and IL8, which can be used as biomarkers for pulmonary impairment among copper smelter workers.

Integration of fine grinding and H2SO4 leach for the liberation, dissolution and redistribution of long-life radionuclides in copper flotation concentrate

The economically significant deposits – iron oxide-copper-gold (IOCG) usually contains elevated amount of naturally occurring radioactive material (NORM), which hinders the utilization of IOCG deposits and leads to the waste of resources on site due to the presence of these radionuclides. Herein, a new fine grinding – H2SO4 leach method was used to efficiently dissolve and liberate long-life radionuclides (238U, 230Th, 226Ra, 210Pb, 210Po) from uranium-bearing NORM that are finely disseminated in the major economical minerals. The fine grinding treatment reduced the average particle sizes, interrupted the mineral textures and partially dissolved uranium minerals, thereby liberating them onto the newly formed secondary copper phases. The following H2SO4 leach changed the chemical and phase compositions by dissolving non-copper elements where the locked 238U and 230Th were largely removed close to the safe activity (1 Bq/g) and 226Ra, 210Pb, 210Po were mobilized onto the copper mineral surfaces. For the first time, the quantitative correlations between radionuclide species and major mineral phases were built by QXRD and radionuclide analysis. Such quantification methodology of radionuclide deportment can be applied in the processing a broad range of NORM-bearing resources, providing a crucial guidance in radionuclide management for environmental and process engineers.

Handling trace elements in WEEE recycling through copper smelting-an experimental and thermodynamic study

Recycling of waste electrical and electronic equipment (WEEE) is attracting increasing attention, due to the presence of valuable metals and the risk of environmental emissions associated with WEEE disposal. In this study, the distributions of trace elements (Ag, Ni, Co, and Sn) between copper alloy and magnetite/wüstite-saturated iron silicate slags were investigated at 1200–1300 °C and PO2 of 10-10-10-6.5 atm, simulating the conditions of WEEE reprocessing through secondary copper smelting and converting. The high-temperature isothermal equilibration experiments were conducted in synthesized magnetite/wüstite crucibles under controlled CO-CO2 atmospheres followed by quenching in an ice-water mixture. The phase compositions and concentrations of the trace elements in copper alloy, magnetite/wüstite, and slag were determined by Electron Probe X-ray Microanalysis and Laser Ablation-High-Resolution Inductively Coupled Plasma-Mass Spectrometry. The distribution coefficients of all investigated trace elements between copper alloy and slag increased with decreasing oxygen partial pressure and increasing temperature. Ag distributed strongly into the copper alloy at all conditions, whereas Co mainly deported into the slag phase. Ni and Sn were concentrated in the alloy at lower PO2 and in the slag at higher PO2. Varying concentrations of Ni, Co, and Sn were also dissolved into the solid magnetite/wüstite phase.

Congener profiles and process distributions of polychlorinated biphenyls, polychlorinated naphthalenes and chlorinated polycyclic aromatic hydrocarbons from secondary copper smelting

Secondary copper smelting is an important industrial source of unintentionally produced persistent organic pollutants (UPOPs) emissions. Herein, field study on industrial-scale plants was conducted to clarify the levels and profiles of polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs) and chlorinated polycyclic aromatic hydrocarbons (> 3 rings, Cl-PAHs) from secondary copper smelting plants. The three UPOPs emission levels from the oxygen-enriched smelting furnace were higher than that from the anode furnace, which was attributed to the low-grade raw materials used. The toxic equivalent quantity concentrations of Cl-PAHs were 1.3–4.4 and 4.6–18.9 times higher than that of PCBs and PCNs, respectively. Thus, the emission control of Cl-PAHs in the secondary copper industry should be of concern. The chlorination degree of PCBs and PCNs was ~4 after the gas-cooling stage but was reduced to 1–2 in the stack outlet. This result indicated that the PCBs and PCNs congeners that were generated during the cooling stage were mainly higher-chlorinated. After purification by air pollution control devices (APCDs), the high-chlorinated congeners were removed simultaneously with the fly ash, whereas the low-chlorinated congeners may be regenerated and transferred into the stack gas due to possible memory effect within the APCDs.

PROCESSING OF INDUSTRIAL PRODUCTS WHEN DISPOSING OF COPPER ELECTRO-REFINING SOLUTIONS

At enterprises that process secondary copper raw materials, it is customary to extract copper from the spent electrolyte by electroextraction. After electroextraction, the solution is neutralized with lime milk to obtain a gypsum nickel-containing cake or evaporated with the release of a cake containing metal sulfates (Cu, Ni, Zn, Fe), which is sold as a commercial product. The search for effective technological solutions for the selective isolation of secondary non-ferrous metals during the regeneration and complete utilization of copper electrofining solutions is relevant. The paper presents studies of the processing of spent copper electrolyte from the processing of non-ferrous metal scrap at a copper smelter in Kazakhstan. For the processing of the spent electrolyte, a stage-by-stage neutralization was performed using zinc sublimates and potash. As a result of the first stage of neutralization with zinc sublimations to pH 4.7, a precipitate with a content of PbO 44.69 %; SnО2 16,36 %.was obtained. After processing the sediment with an alkaline solution, carbonization and melting at a temperature of 900 oC, metallic lead and tin-containing slag with a content of SnО2 of 16.36 % were obtained. As a result of the second stage of neutralization with potash to pH 7.1, a precipitate was obtained-with a CuO content of 76.45 %. After the third stage of neutralization with potash to pH 9.5, a precipitate with a content of NiO 27.63 % and ZnO 55.75 % was obtained. After treatment of the precipitate with a solution containing 100 g / dm3 KOH, a zinc-containing solution with a ZnO content of 225.0 g/dm3 and a precipitate were obtained, after calcination of which nickel oxide with a NiO content of 89.14 % was obtained.

Mineralization styles, alteration mineralogy, and sulfur isotope geochemistry of volcanogenic massive sulfide deposits in the Shadli Metavolcanics Belt, South Eastern Desert, Egypt: Metallogenic implications

Three distinct occurrences of Zn–Cu–Pb mineralization (Um Samiuki, Hilgit, and Maaqal) in Neoproterozoic island arcs of the Shadli Metavolcanics Belt, South Eastern Desert, Egypt, have been investigated in this study. The Shadli Metavolcanics Belt erupted in two magmatic cycles, with the Older Um Samiuki Metavolcanics group getting overlain by the Younger Hamamid Metavolcanics (YHM) group. The YHM group is characterized by two distinct cycles of volcanism. The studied deposits are mainly hosted by volcanic and volcaniclastic rocks that belong to the first cycle of the YHM group. The host-rock succession was interpreted to have been formed by back-arc extensional volcanism and was then deformed and metamorphosed to the lower greenschist facies. The relationship between the mineral occurrences and host rocks remains poorly constrained and controversial. We report new field observations, paragenetic data, mineral chemistry analyses, and in situ sulfur isotopes to characterize the sulfide mineralization and to gain insights into its genesis. Two mineralization styles have been identified in these deposits. The first style in the Um Samiuki deposit is expressed by two massive mineralized bodies that are mostly stratiform. It is distinguished by sphalerite, chalcopyrite, pyrite, galena, and Ag-bearing minerals; followed by bornite and covellite in decreasing abundance. Less abundant supergene phases include secondary copper minerals and iron oxyhydroxides. The hydrothermal alteration is characterized by sericitization, chloritization, epidotization, and silicification. The second style represents disseminated and vein-type sulfides mainly encountered in Hilgit and Maaqal occurrences. It is characterized by pyrite with minor sphalerite and chalcopyrite. The δ34SV-CDT values range from + 5.44‰ to + 9.08‰ with an average of + 8.11‰ ±1.1‰ (n = 18) for massive mineralized zones and from − 2.25‰ to + 3.78‰ with an average of + 1.06‰ ±2.3‰ (n = 8) for disseminated and vein sulfides. Such a variation in the sulfur isotope signatures may imply that both mineralization styles were derived from the thermochemical sulfate reduction (TSR) of seawater and leaching of basement lithologies in varying quantities, consistent with Volcanogenic Massive Sulfide (VMS) deposits of back-arc basins. The negative δ34SV-CDT values of some sulfides from the disseminated and vein mineralization may be seen as evidence for magmatic SO2 disproportionation. The studied VMS deposits display a close spatial and genetic association with submarine felsic volcanism of the YHM group, and their temporal distribution corresponds closely with the Mozambique Ocean closure stage of the Pan-African Orogeny.

Separation of arsenic and tin from Cu–As alloy based on phase transformation in a vacuum to form Cu–Fe–S compounds

Cu–As alloy is viewed as one kind of secondary copper resources. It is difficult to simultaneously recover copper and remove arsenic using conventional processes. To separate arsenic and tin from Cu–As alloy (mainly Cu3As), an innovative methodology that uses vacuum distillation in the presence of pyrite to form new phase is proposed herein. The constituents, phases and morphology of the sample before and after vacuum distillation were investigated by chemical analysis, X-ray diffraction (XRD) analysis and electron probe microanalysis (EPMA) to interpret separation performances and volatilization mechanisms of arsenic and tin. Chemical analysis results showed that it is difficult to separate arsenic from Cu-As alloy by direct vacuum distillation, but arsenic and tin were effectively separated after introducing pyrite. The effects of several factors, such as temperature, pyrite dosage and distillation time, on separation performances of arsenic and tin were examined. Volatilization ratios of copper, arsenic and tin reached 0.84%, 96.29% and 88.70%, respectively. Results of XRD analysis and EPMA revealed that arsenic had strong affinity to copper in Cu-As alloy, which inhibited free volatilization of arsenic. After introduction of pyrite, formation of copper sulfides, such as mainly Cu5.433Fe1.087S4, Cu1.96S and Cu9S5, destroyed the alloy structure, which made elemental arsenic volatilize. Excessive sulfur also interacted with elemental arsenic to form mainly As4S3 that is also easily volatilized. Nevertheless, tin was only separated in the form of SnS. It is a promising method to achieve cleaner utilization of Cu-As alloy and effective control of arsenic pollution.

A Multidimensional Evaluation Method for the Service Life of Scrapped Copper Wires

AbstractTo answer ever‐growing challenges in the copper industry, the recycling of secondary copper resources has aroused much interest. However, an evaluation method for the service life of scrapped copper wires is lacking to date. In this work, a data‐based, multicategorized solution is built to rationally assess evolution law of economic value with time flow for recycled copper‐cored wires, covering their one‐way full cycle including reproduction, storage and sale, and final utilization. Here, the results of reproduced cycles, product life, and service life are logically integrated to establish an inherent relation between engineering and sociology by computer science. Such work provides a multiangle perspective for the value evolution emerging in reproduction/application of waste resources. The basic method originating from the current research is expected to throw light on assessing similar scenes.

Recycling Technology Innovation as a Source of Competitive Advantage: The Sustainable and Circular Business Model of a Bicentennial Company

La Farga Yourcoppersolutions is a bicentennial Catalan company that manufactures semi-finished copper products. As copper is a 100% recyclable material, much of the sector’s production comes from secondary copper, scrap, not from mined copper. In the case of La Farga, not only a good part of its output comes from recycled copper, but it is also a world leader in copper-recycling technology. The objective of the paper is to describe La Farga’s business model from the point of view of sustainability and the circular economy. What have been the causes and effects of recycling on the business model? Regarding the methodology, the work follows the research strategy of the case study. Both qualitative and quantitative data were collected from a variety of primary and secondary sources. Economic, social and environmental sustainability of the firm was assessed through financial and non-financial indicators; value-added generation and distribution were calculated from accounting data; and the circular business model was analysed via a thematic analysis: its components, innovation, enablers and barriers. Results show that the presence of barriers forces the implementation of circularity to be gradual and to combine linear and circular models to maintain competitiveness.

The leaching behavior of copper and iron recovery from reduction roasting pyrite cinder

Pyrite cinder (PyC) is an iron-enriched solid waste material, which is an important iron resource for steel industry. However, the separation or extraction of iron minerals and heavy metals from PyC was ineffective, because of the fine disseminated granularity and the intergrowth between iron minerals and toxic heavy metals during high temperature roasting. In this paper, a novel method to extract copper and iron from the PyC by reduction roasting-leaching-magnetic separation was proposed. The effect of various parameters on the copper leaching behavior were studied, and the corresponding kinetics model was established. Under the optimized leaching conditions, the maximum copper leaching recovery of 82.18% was reached. A high-quality iron concentrate with Fe content of 65.58% and copper content of 0.17% was obtained subsequently from the leaching residuals through magnetic separation. It showed that the leaching process was controlled by mixed diffusion and chemical reaction, with a corresponding activation energy of 27.97 kJ/mol. The free copper oxide, combined copper oxide and secondary copper sulfide were extracted completely in H2SO4 solution. However, chalcopyrite as a form of primary copper sulfide dissolved partly. The leaching mechanism was confirmed by chemical phase and XPS analysis.

Enhanced process route to remove fluorine and uranium from copper concentrades by selective sulfuric acid leaching

The main Cu-bearing mineral in copper concentrates consumed in smelters around the world is chalcopyrite (CuFeS2). Minor participation in this consumption is copper concentrates containing secondary copper minerals, such as chalcocite (Cu2S) and bornite (Cu5FeS4). The main issues concerning these copper concentrates are the amount of impurities, such as, fluoride and uranium. These impurities cause a lot of problems for smelters owners, such as equipment corrosion, gas treatment necessity and radionuclides residues generation, leading them to impose restrictions to buy fluoride and uranium copper concentrates. This study proposes a selective atmospheric sulfuric acid leaching process route to extract the maximum of fluoride and uranium and a minimum of copper from two types of copper concentrates, one having chalcocite/bornite as main Cu-bearing minerals, named as chalcocite/bornite concentrate, and another with chalcopyrite as the main Cu-bearing mineral, named as chalcopyrite concentrate. The results show that it is possible to reduce significantly the amount of fluoride and uranium in both samples. These two samples required the addition of sulfuric acid until reaching a pH of (3.5 ± 0.2), which means consumption of 23 kg and 9 kg of H2SO4 97.5 wt% per ton of chalcocite/bornite concentrate or chalcopyrite concentrate, respectively. The addition of aluminum sulfate increases the fluoride extraction, whereas it did not raise the uranium extraction. Chalcocite/bornite concentrate showed a slow kinetic to have fluoride leached, whereas chalcopyrite concentrate presented a fast kinetic to have uranium leached. It was possible to extract 60% of fluoride and 35% of uranium from chalcocite/bornite concentrate and around 10% of fluoride and 60% of uranium from chalcopyrite concentrate. As expected, the copper leached from chalcocite/bornite concentrate was higher (~4.5% of total Cu) than from chalcopyrite concentrate (~0.3% of total Cu). Moreover, it was proposed a complete process route to reduce the amount of fluoride and uranium comprising of acid leaching, copper recovery from the liquor by cementation with powder Fe and liquor treatment by raising the pH up to 9.0 by addition of calcium hydroxide pulp.

A Case of Concurrent Molybdenosis, Secondary Copper, Cobalt and Selenium Deficiency in a Small Sheep Herd in Northern Germany.

Simple SummaryMineral deficiencies are very widespread among small ruminant herds throughout the world and play a big role in small ruminant herd health management. This paper describes the occurrence of a primary molybdenosis causing secondary copper deficiency, combined with ovine white liver disease (cobalt deficiency) and white muscle disease (selenium deficiency) in a group of pastured ram lambs in Northern Germany. To the authors’ knowledge, this is the first proven report of multiple trace element deficiencies in sheep in Germany for decades.To the author’s knowledge this paper describes the first proven report of a combined primary molybdenosis, secondary copper (Cu) deficiency, Ovine White Liver Disease—Cobalt (Co) deficiency, and selenium (Se) deficiency in a small pedigree herd of White Horned Heath sheep in Germany (8 ewes, 2 rams, 3 yearling ewes, 17 lambs) for decades. Clinical signs associated with these mineral deficiencies in a group of pastured ram lambs included emaciation, conjunctivitis, anaemia, growth retardation, discolouration of the wool and photodermatitis. Morbidities and mortalities arose in 4–6-month-old lambs despite intensive veterinary treatment in the summer of 2014 and 2015 (n = 13, 23% died). Se (3/5), Cu (4/7), and Co (3/3) deficiencies in combination with elevated values for Molybdenum (Mo, 2/2) were found. Hamburg is a large industrial city and an input of heavy metals from surrounding industries and coal-fired power stations in combination with a sandy, non-fertilised soil and monoculture grass species might offer a potential explanation for the severity of mineral deficiencies observed in this herd.

Profiles, spatial distributions and inventory of brominated dioxin and furan emissions from secondary nonferrous smelting industries in China

Nonferrous metallurgical processes are important sources of carcinogenic polybrominated dibenzo-p-dioxin and dibenzofuran (PBDD/Fs) that transport globally. Studies on the profiles, spatial distributions and inventory of PBDD/F emissions into the atmosphere from nonferrous metallurgical plants are needed for better source control. In this study, field investigations on PBDD/F emissions from typical nonferrous metallurgical plants were conducted to characterize the PBDD/F profiles and derive their emission factors. Based on the PBDD/F profiles, diagnostic ratios of PBDD/Fs for secondary copper, zinc and lead smelting were proposed for identifying the potential sources of PBDD/Fs in environment. The PBDD/F emission factors for the secondary copper, lead, and zinc smelting plants were 0.71, 1.65, and 1.54 μg toxic equivalents/t, respectively. The estimated annual input of PBDD/Fs into atmosphere by secondary nonferrous metallurgical plants in China was 212.4 g by mass and 3511.3 mg by toxic equivalents, which is of significance for further evolving a global inventory. The spatial distribution of PBDD/F emissions from nonferrous metallurgical plants in China was mapped. Larger amounts of PBDD/Fs were emitted in the southeastern coastal region and northern China than elsewhere in China.

Evaluation of econometric models of secondary refined copper supply

Copper is essential in attaining a sustainable development path due to its prominent role in the electromobility and renewable energy industries. In 2019 refined copper usage was 23.5 million tons, of which primary copper supplied 86.3%, and the remaining 13.7% was provided by secondary metal. In the future, copper recycling would increase significantly concerning primary copper supply to meet the goal of decreasing greenhouse gases emissions. Secondary copper production reduces energy consumption by 85% and greenhouse gas emissions by 65% compared to average primary sources.This study analyzes seven econometric models described in the literature that tried to explain the supply of secondary refined copper worldwide (SRC). Furthermore, this study assesses the forecasting capacity of these models in the short and long-term. Although the explanatory variables selected by previous researchers are theoretically supported, they failed to fully explain SRC. An empirical analysis for the period 1960–2017 confirmed that only two of the eight studied explanatory variables shown to be causal of SRC in the short-term. The re-estimation of the coefficients shows high instability when the number of variables or observations changed, making it difficult to analyze the future market and to assess public policies. Although the explanatory variables share the same long-term trend (cointegrated series), they do not properly forecast the future when evaluated using the Backcasting methodology.Based on these results, it is possible to improve the explanatory and predictive power of the analyzed models and reduce their average error.