Primary Copper Production Research Articles

Study of the Effect of Spinel Composition on Metallic Copper Losses in Slags

In both primary and secondary copper production, copper losses in slags are a decisive factor confining the process efficiency. An important cause for mechanical entrainment of metal droplets in slags is their attachment to solid spinel particles present in the slag phase, hindering sedimentation. To further optimize the production process, it is important to gain insights in the fundamental mechanisms governing this attachment. In the present study, the influence of the spinel composition on the attachment of copper droplets is investigated. First, the attachment is studied in an industrially relevant synthetic PbO–CaO–SiO2–Cu2O–Al2O3–FeO–ZnO slag system. Second, the wetting of copper on two spinel substrates (ZnFe2O4 and MgAl2O4) has been studied in the absence of a slag system, by sessile-drop experiments. Based on the results of both types of experiments, a clear influence of the spinel composition on the sticking behavior of copper droplets is noted. These observations might be transferred to industrial processes to adapt processing parameters to diminish copper losses in industrial slags.

Investigation of High-Temperature Slag/Copper/Spinel Interactions

An important cause for the mechanical entrainment of copper droplets in slags during primary and secondary copper production is their interaction with solid spinel particles, hindering the sedimentation of the copper droplets. In the present study, the interactions between the three phases involved (slag–Cu droplets–spinel solids) were investigated using an adapted sessile drop experiment, combined with detailed microstructural investigation of the interaction zone. An industrially relevant synthetic PbO-CaO-SiO2-Cu2O-Al2O3-FeO-ZnO slag system, a MgAl2O4 spinel particle, and pure copper were examined with electron microscopy after their brief interaction at 1523 K (1250 °C). Based on the experimental results, a mechanism depending on the interlinked dissolved Cu and oxygen contents within the slag is proposed to describe the origin of the phenomenon of sticking Cu alloy droplets. In addition, the oxygen potential gradient across the phases (i.e., liquid Cu, slag, and spinel) appears to affect the Cu entrainment, as deduced from a microstructural analysis.

Copper demand, supply, and associated energy use to 2050

Abstract To a set of well-regarded international scenarios (UNEP’s GEO-4), we have added consideration of the demand, supply, and energy implications related to copper production and use over the period 2010–2050. To our knowledge, these are the first comprehensive metal supply and demand scenarios to be developed. We find that copper demand increases by between 275 and 350% by 2050, depending on the scenario. The scenario with the highest prospective demand is not Market First (a “business as usual” vision), but Equitability First, a scenario of transition to a world of more equitable values and institutions. These copper demands exceed projected copper mineral resources by mid-century and thereafter. Energy demand for copper production also demonstrates strong increases, rising to as much as 2.4% of projected 2050 overall global energy demand. We investigate possible policy responses to these results, concluding that improving the efficiency of the copper cycle and encouraging the development of copper-free energy distribution on the demand side, and improving copper recycling rates on the supply side are the most promising of the possible options. Improving energy efficiency in primary copper production would lead to a reduction in the energy demand by 0.5% of projected 2050 overall global energy demand. In addition, encouraging the shift towards renewable technologies is important to minimize the impacts associated with copper production.

The effect of primary copper slag cooling rate on the copper valorization in the flotation process

Technological procedure of slow cooling slag from primary copper production is applied in the purpose of copper recovery in the level of 98.5% to blister. This technological procedure is divided into two phases, first slow cooling of slag on the air for 24 hours, and then accelerated cooling with water for 48 hours. Within the research following methods were used: calculation of nonstationary slag cooling, verification of the calculation using computer simulation of slag cooling in the software package COMSOL Multiphysics and experimental verification of simulation results. After testing of the experimentally gained samples of slowly cooled slag it was found that this technological procedure gives the best results in promoting growth or coagulation of dispersed particles of copper sulfide and copper in the slag, thereby increasing the utilization of the flotation process with a decrease of copper losses through very fine particles.

Identification and assessment of environmental burdens of Chinese copper production from a life cycle perspective

The environmental burdens of Chinese copper production have been identified and quantified in the context of typical technologies, materials supplies and environmental emissions by a life cycle approach. Primary and secondary copper production using copper ores and scraps, respectively, were analyzed in detail. The flash and bath smelting approaches and the recycling of copper scraps were selected as representative copper production processes. A quantitative analysis was also conducted to assess the influence of material transport distance in copper production. Life cycle assessment (LCA) results showed that resources depletion and human health contribute significantly to environmental burdens in Chinese copper production. In addition, the secondary copper production has dramatically lower environmental burdens than the primary production. There is no obvious distinction in overall environmental burdens in primary copper production by flash or bath smelting approach. However, resources depletion is lower and the damage to human health is higher for flash smelting approach. Ecosystem quality damage is slight for both approaches. Environmental burdens from the mining stage contribute most in all life cycle stages in primary copper production. In secondary copper production, the electrolytic refining stage dominates. Based on the life cycle assessment results, some suggestions for improving environmental performance were proposed to meet the sustainable development of Chinese copper industry.

The Blue Water Footprint of Primary Copper Production in Northern Chile

SummaryWater consumption related to the life cycle of metals is seldom reported, even though mines are often situated in very dry regions. In this study we quantified the life cycle consumption of groundwater and fresh surface water (blue water footprint [WFblue]) for the extraction and production of high‐grade copper refined from both a copper sulfide ore and a copper oxide ore in the Atacama Desert of northern Chile. Where possible, we used company‐specific data.The processes for extracting copper from the two types of ore are quite different from each other, and the WFblue of the sulfide ore refining process is 2.4 times higher than that of the oxide ore refining process (i.e., 96 cubic meters per metric ton [tonne] of copper versus 40 cubic meters per tonne of copper). Most of the water consumption (59% of WFblue) in the sulfide ore process occurred at the concentrator plant, via seepage, accumulation, and also by evaporation. In the oxide ore process, the main user of water is the heap‐leaching process, with 45% of WFblue. The crushing and agglomeration operations, electrowinning cells, and solution pools are also significant contributors to the total consumption of water in the oxide ore process. Most of the water consumed in the oxide ore process was lost to evaporation.The WFblue of the oxide ore process can be reduced by preventing water evaporation and using more sophisticated devices during irrigation of the leaching heaps. The WFblue of the sulfide ore refining process can be reduced by improving water recovery (i.e., reducing seepage, accumulation, and evaporation) from the tailings dam at the concentrator plant. Using seawater in the production of copper is also a promising option to reduce the WFblue by up to 62%.

Polychlorinated dibenzo p-dioxins and dibenzofurans emissions in a primary copper smelter in China

Metallurgical production is the largest polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) emission source in China. However, PCDD/F monitoring and research are rarely conducted on primary metallurgical production. In this study, a demonstration primary copper smelter in China was selected to investigate PCDD/F characteristics and control. Samples were collected from major PCDD/F release points in the smelter process (fly ashes and waste water sludge). Specific analysis of PCDD/F congeners was carried out using a high resolution gas chromatography/high resolution mass spectrometry method. The results showed that PCDD/Fs might be unintentionally produced in the primary copper smelter processes, with sample concentrations of 180–6110 pg/g dry wt; highly chlorinated PCDD/F homologues were predominant. The toxicity of all the samples was calculated to be 120 pg WHO TEQ/g, fly ashes from the refining process furnaces air pollution control device and sludge were hazardous waste with higher PCDD/F toxicity. Both precursor formation and de novo synthesis were found to contribute to PCDD/F formation in the smelter process. PCDD/F characteristics and formation were compared with reported secondary copper smelters. Life-cycle control of PCDD/F was proposed for retrofitting of this smelter and for similar plants in China's primary copper production sector, including control at the PCDD/F formation, removal and disposal stages.

Using sustainability reporting to assess the environmental footprint of copper mining

The energy, greenhouse gas (GHG) emissions and water intensity, or environmental footprints, of global primary copper production have been estimated. The primary data have been collected from the sustainability reports published by copper producing mines, operations and companies. The mines analysed in this paper are from Australia, Chile, Peru, Argentina, Laos, Papua New Guniea, South Africa, Turkey, Finland, the USA and Canada. The typical range of energy intensity was found to be 10–70 GJ/t Cu, with an average of 22.2 GJ/t Cu. The range of GHG emissions was 1–9 t CO2-e/t Cu, with an average of 2.6 t CO2-e/t Cu. The large variation exists largely due to the form of copper produced, ore grade, sources of fuel and electrical energy, and to a lesser extent the reporting methods and procedures used by the companies. The water footprint averages 70.4 kL/t Cu but can range from several kilolitres to up to 350 kL/t Cu. Variation in water intensity is generally due to inconsistencies in reporting method, the geographical location of the mining operations, limited economies of scale of production site, and the climate type (i.e. arid regions in Australia and Chile or temperate to sub-arctic climates in Canada or Finland). It is recommended that company sustainability reports should clearly specify fuel use by type for vehicles, heat or electrical energy, sources of electricity and their mixes (including GHG emissions factors), and the boundaries of the operation for meaningful use in life cycle assessment (LCA). Sustainability reports should be published at regular intervals so that improvements towards more sustainable performance can be measured, and an LCA of mining activities can be developed for primary copper production more readily. The paper provides a valuable insight into the strong value of sustainability reporting for an industrial sector such as copper mining and how such data can be linked to LCA studies.

Characterization and quantification of unintentional POP emissions from primary and secondary copper metallurgical processes in China

Field monitoring was conducted to update and develop unintentional persistent organic pollutant (unintentional POP) emission inventories for the copper metallurgy industry in China. In this study, emissions of six unintentional POPs comprised of polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/PCDF), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), hexachlorobenzene (HxCBz) and pentachlorobenzene (PeCBz) in stack gas and fly ash samples from primary and secondary copper smelters using different raw materials and technologies were measured and compared. Different concentrations, congener patterns and emission factors of unintentional POPs among four copper smelters were observed. Variations in unintentional POP emissions from several areas of a primary copper smelter were also investigated. The total emissions of unintentional POPs from primary and secondary copper production in 2010 in China were estimated respectively. These results provide a useful reference for the establishment of unintentional POP emission inventories and for policymakers to formulate control strategies to reduce unintentional POPs resulting from copper metallurgy.

Isotopic and technological variation in prehistoric Southeast Asian primary copper production

The ‘Southeast Asian Lead Isotope Project’ (SEALIP) is intended to provide reliable geochemical proxies for late prehistoric through early historic (2nd/1st millennium BCE and 1st millennium CE) local, regional, and inter-regional social interactions, in an archaeological arena lacking established ceramic typologies with which to cross modern national boundaries. We present lead isotope characterisations of the three currently known Southeast Asian prehistoric primary (mining/smelting) copper production centres: Phu Lon and the Khao Wong Prachan Valley in Thailand, and the recently discovered Xepon complex in Laos. Kernel Density Estimation shows that these production centres can be clearly distinguished isotopically, as such fulfilling the core tenet of the ‘Provenance Hypothesis’ ( Wilson and Pollard, 2001: 508) and permitting SEALIP to proceed as a research programme tracing regional copper/bronze/lead exchange and provenance patterning. In addition we provide a provisional technological reconstruction of copper smelting processes at Phu Lon to complement our more established understanding of the Khao Wong Prachan Valley. Combined lead isotope and technological datasets allow us to tentatively identify trends in the evolution of Southeast Asian metal technologies and of regional social perceptions of metal exchange.

Mapping Environmental Performance of International Raw Material Production Flows: a Comparative Case Study for the Copper Industry of Chile and Germany

World primary copper production is expected to increase due to growing demand. Reflecting the geographical divergence of copper deposits and demanding industries, copper is produced by various production paths, differing in regional and technological aspects and related environmental pressures. For the mitigation of environmental pressures related to global material flows and a more sustainable resource management, policy makers, producers and buyers require information on regional resource efficiencies and effects of the key processes within the global production chain. This study quantifies material flows of refined copper production and environmental pressures along the pyro‐ and hydrometallurgical paths for Chile and Germany. Inventories for involved unit processes are distinguished by region and most commonly applied technologies, including electric power supply. Different production paths are compared by environmental pressure indicators (primary energy requirements, total material requirements, wat...

Lixiviants for primary gold and/or copper production

These days, when a s k e d “ W h a t exactly does a metallurgical engineer do?” the answer can range anywhere from mineral processing to chemical processing to material science. The answer you give is usually dependant on what area of the world you are in, which industry you are currently employed in, and where and in what decade you attended college. Put three metallurgists in a room together and pose the question “What does a metallurgical engineer do?” and you may fi nd yourself in the midst of a disturbance similar to any discussion between a geologist, miner, and metallurgical engineer. It is the strength and broadranging skill-set of the metallurgical engineer that makes applying a defi nition diffi cult. When addressing aqueous processing, it is the same broad-ranging applicability of the universal solvent coupled with its varied hydraulic application that makes applying a constraining defi nition problematic. Ask, “What exactly is aqueous processing?” and the answer may come from a wide range of possibilities, again depending on what area of the world you are in, which industry currently employs you, and where and in what decade you attended college. When asked to represent the Aqueous Processing Committee in assisting with this issue of JOM, my hope was to provide a range of topics within the area of aqueous processing, thus providing the readership with material that may be of primary interest as well as new information. Having said that, the information provided does tend to center around primary gold and copper production, touching Lixiviants for Primary Gold and/or Copper Production

On the evolution of mathematical modelling of single-step flash smelting of copper concentrates

In the past few decades, a great deal of attention has been paid to the mathematical modelling of the metallurgical processes. The success of flash smelting process, documented by its continuously growing participation in the worldwide primary copper production volume, is a result of high intensity of heat and mass transfer processes occurring during smelting. This paper presents the evolution of mathematical models of the flash smelting process. The application of the model for the comparative analysis of the different burner systems in use showed that the single burner system would be recommended mainly due to the lower dusting, which is one of the main disadvantages of the single-step flash smelting process.

Long term energy-related environmental issues of copper production

Primary copper production is a major activity in the mining sector of several countries. However, it is highly energy-intensive and poses important environmental hazards. In the case of Chile, the world's largest copper producer (40% of world total), we examine its energy consumption and energy-related environmental implications over a time horizon of 25 years. Concerning the latter, we focus on greenhouse-gas (GHG) emissions, one of the most debated environmental issues. This paper follows-up our previous report in which the current situation was analyzed and a particular technical option for improving the energy efficiency and concurrently reducing GHG emissions was discussed. Estimated reference or base (BS) and mitigation (MS) scenarios are developed for the period ending in 2020. The former assesses the energy demand projected in accordance with production forecasts and specific energy consumption patterns (assuming that energy efficiency measures are adopted ‘spontaneously’) with their resultant GHG emissions, while the latter assumes induced actions intended to reduce emissions by adopting an aggressive policy of efficient energy use. For the year 2020, the main results are: (i) BS, 1214 t of CO 2/ton of refined copper content (49% lower than in 1994); (ii) MS, 1037 t of CO 2/t of refined copper content (56% lower than in 1994). CO 2 emissions have been estimated considering both fuel and electricity process requirements.

Energy and environmental implications of copper production

Primary copper production is a major activity in the mining sector. It is highly energy-intensive, ranking third in specific energy consumption (SEC) among the five major basic metals (aluminum, copper, iron, lead and zinc) and poses important environmental hazards. We examine the large discrepancy between theoretical (from thermodynamics) and actual (from empirical data) SECs and then describe relevant environmental issues, focusing on the most significant energy-related environmental impacts of primary copper production with emphasis on greenhouse-gas (GHG) emissions. An example of GHG energy-related abatement that concurrently improves energy use is presented.

Removal and recycling of copper from aqueous solutions using treated Indian barks

Removal of copper from aqueous solutions containing 100–1000 ppm, using different Indian bark species, was performed on laboratory scale. The percentage removal of metal ions depends on the solution pH, bark species and time. The efficiency of copper removal by the used raw barks increases with a rise of solution pH and reaches a maximum of about 65–78% around pH 4–5. However, the decontaminated aqueous solutions were colored due to the dissolution of soluble organic compounds contained in the raw bark. This increases the biological and chemical oxygen demand (BOD and COD) of the solutions as well as the total organic carbon content (TOC). For this reason, raw bark should be treated either by chemical or biological means. Such treatment will allow the extraction of the soluble organic compounds and increase the chelating capacity and efficiency of the treated bark. Depending on the pH value, the chelating efficiency of treated barks is about 1.2–2.2 times that of the raw ones. Moreover, the retention capacity of the Indian treated bark varies from about 42–51 mg/g of dry bark. It is equal to or higher than that of common European species. About 1.8 mols of H3O+ are released, by the treated barks, for every mol of chelated copper ions. Moreover, scanning electron microscopy (SEM) observations show uniform distribution of metal ions throughout the copper saturated bark. Infra red (IR) spectra suggest that the copper ions are chelated to hydroxyl and/or carboxyl functional groups of organic compounds contained in the treated bark. It seems that the interaction of the copper ions with the bark follows a cation exchange mechanism. This hypothesis is supported by elution experiments that allow recovery of about 99% of the contained copper. The retention capacity of the treated bark is almost constant after five cycles of chelation–elution, suggesting that the `life time cycle' is sufficiently long for continuous industrial application. The spent copper loaded barks can either be incinerated or pyrolysed. It generates solids containing either ≈80% of CuO or ≈14% of Cu°, respectively. Such materials can be used either in the secondary or primary copper production, thus offering a friendly environmental solution of effluents' treatment. The suggested process can be used as an alternative to the classical technologies for effluent decontamination. It is also efficient for polishing effluents treated by other methods.

Recent Trends in Copper In Situ Leaching

The recovery of copper by leaching techniques has been practiced for centuries. In the U:iited States at the present time approximately 25 percent of the primary copper production is derived frnm leaching activities. Most of this production results from massive dump and heap leaching activitie: associated with large open-pit mines. Historically a small portion of copper is produced from small scale in situ leaching operations treating low-grade rock left from earlier mining activities. In situ leaching technology because of its intrinsic advantages over conventional mining and milling is being considerec as a viable option for recovering copper from both oxide and sulfide deposits. This paper reviews the development of copper in situ leaching, and discusses both commercial and experimental projects. Hydrometallurgical extraction of copper by in situ leaching requires interfacing such technologies as solution chemistry, hydrology, geology, geochemistry, and rock mechanics. Both physical and chemical parame...

The economics of energy conservation policies: A study of US primary copper production

US oil and gas price regulation has made energy-saving investments less attractive than they otherwise might have been. The question thus arises: at what energy prices will conservation be attractive? This microeconomic study aims at answering this question for US primary copper firms. The costs and benefits of three major potential energy conserving processes are estimated. A profit-maximizing computer model is then used to simulate the behaviour of three leading US copper producers and their rates of adoption of the conservation measures. The costs associated with energy savings are calculated and the energy price changes necessary for the adoption of the measures are considered. It is concluded that, assuming 1974 prices for non-energy factors, energy prices need to be 110% greater than 1974 levels before energy-saving investment becomes attractive.