Smelting Of Copper Ores Research Articles

Effect of flue gas constituents on boiler tube failure of a captive power plant

Water leakage was reported from one of the superheater tubes of boiler during operation. The power plant is a part of copper ore smelting and refining industry. It was observed, that the leakage took place through cracked region of the tube, which was severely damaged due to chemical attack. Damage occurred due to reaction between flue gas and outer wall of super heater tube. Inefficient treatment of flue gas resulted in retention of metal particles, SO2 gas and particulate within the same in substantial concentration. When the same flue gas was used in boiler, SO2 reacted with tube surface at elevated temperature. The incident lead to wall thinning and deep pit formation over tube surface. Metal particles was fused, adhered to tube surface and triggered secondary cracking during operation. Gradual wall thinning, increment in pit size and crack propagation through thickness resulted in ultimate failure of tube material.

Microstructural Examinations of Copper Antimony Alloys

Abstract Among other materials, fahlores were used in the Bronze Age copper ore smelting process. These contain, apart from sulfur, arsenic and antimony. Therefore, these elements can be found in Bronze Age copper casting ingots or artifacts. In order to study the behavior of Sb more closely, two copper alloys containing 10 and 30 wt. % Sb were melted and subjected to a metallographic examination. On the one hand, microstructures with copper dendrites and homogeneous interdendritic areas primarily composed of intermetallic phase could be found. On the other hand, at higher Sb concentrations, first Cu3Sb precipitated which, in turn, transformed to Cu10Sb3 upon cooling. The crystals in these microstructures were characterized by numerous parallel cracks. No further phases were observed by XRD.

Copper production and supra-regional exchange networks – Cu-matte smelting in the Balkans between 2000 and 1500 BC

The Balkan Peninsula played a crucial role for the introduction of metallurgy during the Copper Age and numerous archaeometallurgical examinations have delivered highly interesting insights on this topic. However, there is a lack of systematic analytical research on copper ore smelting and metal exchange for the later Bronze Age. In this paper we focus on the first archaeometallurgical results of slags from the sites Ružana, Trnjane and Čoka Njica, Eastern Serbia, complimented by the discussion of XRF and lead isotope analyses carried out on 28 copper-based artefacts. Importantly, radiocarbon dating from these sites points to copper production already being undertaken at the end of the Early Bronze Age (19th–18th centuries BC), more than 500 years earlier than previously assumed. This enables us to investigate the flow of metal during the 1st half of the 2nd millennium BC. The analyses of the metallurgical slags indicate a copper matte smelting process in small open pit furnaces and the use of local sulfidic copper ore sources. The fact that these intensive smelting activities in Eastern Serbia can be paralleled with the early production hotspots in central Europe e.g. on the Hochkönig (Mitterberg mining areas) sheds new light on the development of copper based metallurgy in Europe. At the same time, the evidence from Eastern Serbia shows that this area was a source of raw material for copper and bronze alloys providing a regional and supra-regional perspective. Furthermore, our analyses revealed the remarkable result, that by the start of the Middle Bronze Age (ca. 1700 BC) copper from the Northern Italian mining areas in the Trentino region also reached the western and central Balkans.

Late Bronze Age Smelting and Processing Furnaces of the Eastern Variant of the Pakhomovskaya Culture in the Baraba Forest-Steppe

We describe smelting furnaces found in southwestern Siberia, at the Tartas-1 ritual site, representing the eastern variant of the Pakhomovskaya culture. This is so far the only known site where the ritual complex, which includes post holes, and utility and ritual pits, adjoins a special manufacturing area with furnaces for smelting copper ore and processing bronze. The pits, differing in form, depth, and size, belonged to a structure. Furnaces are of two types: deep ones, dug into virgin soil, and shallow ones with domes. The former were destined for smelting ore, and the latter for processing metal. The construction of both types is described in detail. The smelting furnaces are peculiar and have no direct parallels in the Late Bronze Age settlements and sanctuaries of southwestern Siberia, while being somewhat similar to smelting furnaces of the Early Iron Age Itkul culture of the Trans-Urals. Furnaces of the second type resemble those of the local Late Irmen culture. Apparently, in the Baraba forest-steppe, where no copper ore outcrops are available, the ritual complexes included furnaces destined for both smelting ore and processing metal. The bronze metallurgy in the region may have been introduced by immigrants practicing both copper ore smelting and metal processing.

Bronze age settlement and necropolis of Trnjane, near Bor - revision and new research results

In archaeological literature, the site of Trnjane, near Bor in eastern Serbia is known as an urn necropolis, with 43 discovered urn graves. The excavations in Trnjane took place between 1985 and 1987-1989, and continued in 1998. The investigations also included an excavation of a nearby settlement, but the results of this research were never published. In most of the previous studies, Trnjane was assigned to the Middle and Late Bronze Age, while the necropolis was often connected with the spread of the Urnfield Phenomena from Central Europe toward the Balkans. New investigations started in 2017 as cooperation between the Archaeological Institute in Belgrade and the Institute for Oriental and European Archaeology (OREA) of the Austrian Academy of Sciences shed new light on the chronology and cultural assignment of Trnjane and other similar surrounding sites in the region of eastern Serbia. The excavation of the settlement area in 2017 and 2018 yielded numerous finds indicating metallurgical activities connected with copper ore smelting (slag and ores), while pottery finds showed a typological resemblance with an Early and Middle Bronze Age repertoire. The radiocarbon dates from the settlement area and from urn graves of the neighbouring necropolis also point to a much earlier time than previously assumed. The new chronological determination of Trnjane raises a set of new questions, especially regarding the cultural connections between central Europe and the Balkans and transfers of copper ore smelting technology in the Bronze Age.

Development of a new controlled low strength filling material from the activation of copper slag: Influencing factors and mechanism analysis

During copper ore smelting process, large amount of copper slag is created, which has excellent use in variance ways. In the common case, copper slag were deposited on the surface without treatment, which inevitably caused serious environmental problems. To deal with the pollution created and better utilize copper slag, a new controlled low strength filling material (CLSFM) was proposed for the copper slag from a mine in Africa.The filling cost of using CLSFM is equivalent to that of cement, as well as the method is more ecological and conforms to the local government environment policy. In order to study the influencing factors of this material, orthogonal test method and data visualization were used in the experiment, which make it possible to observe the effect of multifactor composite action on copper slag and the optimum ratio. The experimental results show that mechanical activation and alkali excitation can effectively activate the copper slag. Microscopic analysis shows that the main hydration product of CLSFM, C–S–H, makes the copper slag cementitious, and improves its structural strength. • The impact of Mechanical activation and Chemical activation on the copper slag was investigated. • Orthogonal test, regression analysis and data visualization were used to optimize the ratio. • The microstructure and hydration products of copper slag after mechanical and chemical excitation were analyzed.

Influence of process parameters on separation performance of strategic elements by polymeric nanofiltration membranes

Employing nanofiltration, a separation of uncharged solutes, monovalent, and bivalent ions from multicomponent aqueous solutions is potentially feasible. Separation is strongly influenced by process parameters as well as the feed properties and membrane characteristics. The aqueous solution in this study includes strategic elements (Ge, Co, Mo, Re) in a wide range of concentrations and varying ionic species. The feed composition mirrors a bioleachate of a German flue dust resulting from copper ore smelting. In a number of cross-flow experiments, the separation performance of eight commercial polymeric nanofiltration membranes was evaluated and the influence of transmembrane pressure, flow velocity, flow regime, recovery, and ionic strength was investigated. It was observed that a high ionic strength (evoked by a high Zn concentration) affects Re retention negatively and decreases permeability. By increasing the transmembrane pressure, the separation selectivity towards Re is enhanced. An almost quantitative Re separation is realized with a cut-off below 200 Da (RO90, NE-90). The utilized NF99HF membrane shows the best results regarding permeability and separation selectivity towards Re, Ge, and Mo.

Le bois de l’Enfer à Saint-Sauveur-le-Vicomte (Manche, France) : un nouveau dépôt de lingots plano-convexes et quelques éléments de réflexion sur la présence d’indicateurs spatiaux au-dessus des dépôts métalliques

Le bois de l’Enfer à Saint-Sauveur-le-Vicomte (Manche, France) : un nouveau dépôt de lingots plano-convexes et quelques éléments de réflexion sur la présence d’indicateurs spatiaux au-dessus des dépôts métalliques

Variability of the copper isotopic composition in soil and grass affected by mining and smelting in Tsumeb, Namibia

The Tsumeb mining District (Namibia) is affected by prolonged exposure to multisource contamination related to the mining and smelting of copper ores. This study was performed to assess the extent of contamination of topsoil and grass shoots on the basis of the copper isotopic composition. Compared to an uncontaminated area (δ65Cusoil = −0.01 to +0.14‰; δ65Cugrass = −0.17 to +0.03‰), the soil and grass in the contaminated area are enriched in the heavy isotope (δ65Cusoil = +0.13 to +0.76‰ and δ65Cugrass = +0.15 to +0.64‰). The Δ65Cugrass-soil value exhibits small variations (+0.06 to −0.17) due to the variable degree of grass surface contamination, depending on the grass washing procedure used. The enrichment of soil and grass in the contaminated area in 65Cu reflects the Cu isotopic composition of old flotation tailings (δ65Cu = +0.95 to +1.1‰), slag (+0.11 to +0.55‰) and particles which originate from the smelting and flue gas cleaning processes (+0.15 to +0.49‰). The long history of mining and processing of copper ores in the Tsumeb area and the different isotopic composition of ore concentrates smelted in the local metallurgical plant do not allow assessment of whether the smelting process leads to isotope fractionation of copper. However, the isotopic composition of Cu in the sulfidic feed, slag and dust particles sampled over several hours showed that the dust collected from the dusthouse of the local smelter is isotopically lighter (δ65Cu = +0.15‰) relative to the isotopic composition of the charge (δ65Cu = +0.28 and +0.44‰). The results of this investigation demonstrate that the isotopic composition of Cu in soils and grasses can be used to assess the intensity of contamination in areas where Cu ores are mined and processed provided that the isotopic compositions of the ore processing products are different from the isotopic compositions of the uncontaminated soils and vegetation.

Characteristic and Source of Atmospheric PM10- and PM2.5-bound PAHs in a Typical Metallurgic City Near Yangtze River in China.

The characteristics of atmospheric PM10- and PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) were investigated in Tongling city, China. Results showed that the total concentrations of PM10- and PM2.5-bound PAHs exhibited distinct seasonal and spatial variability. The metallurgic sites showed the highest PAH concentrations, which is mainly attributed to the metallurgic activities (mainly copper ore smelting) and coal combustion as the smelting fuel. The rural area showed the lowest concentrations, but exhibited significant increase from summer to autumn. This seasonal fluctuation is mainly caused by the biomass burning at the sites in the harvest season. The diagnostic ratio indicated that the main PAHs sources were vehicle exhausts, coal combustion and biomass burning. The total BaP equivalent concentration (BAP-TEQ) was found to be maximum at DGS site in winter, whereas it was minimum at BGC site in summer. Risk assessment indicates that residential exposure to PAHs in the industrial area, especially in the winter season, may pose a greater inhalation cancer risk than people living in living area and rural area.

Strategic elements from leaching solutions by nanofiltration – Influence of pH on separation performance

Abstract Strategic elements are essential for industrialized countries and both, demand and prices are constantly increasing. The exploitation of so far unutilized polymetallic mining waste could ensure a reliable supply. Mining residues, like the investigated German flue dust deposit from copper ore smelting, represent a promising approach for metal extraction. By bioleaching, the sulfide bonded metals can be dissolved from the mineral phase. Downstream processes are required to separate the target elements from the obtained multicomponent leaching solution. One promising technology is nanofiltration (NF). Three polymeric NF membranes (NF99HF, UTC-60, NP010) were screened to investigate the separation performance of Co, Cu, Ge, Mo, Re, and Zn in a dead-end set-up, in particular the pH-dependent retention. The study shows that pH and thus, the formed ionic species have a major influence on retention and separation performance. Mainly based on size exclusion, a selective separation of Re seems feasible with the NF99HF and UTC-60 at pH 7. Under acidic conditions, a separation during concentrating cannot be realized in dead-end by NF because shearing forces and the build-up concentration as well as the electric field gradient forces the permeation of the solutes. However, if the recovery and ionic strength of the solution is set low, the selectivity can be increased even at pH 2.

Determination and Calculation of Components Cargo (Slag) During Smelting of Copper Ores

After smelting the copper ores in flame furnace crated matte that is smelting Cu2S and FeS. The amount of copper in Matte determined amount of Cu2S while rest is while FeS. In reallity matte contains less sulfur and other metals such as: PbS, ZnS, Fe3O4 and noble metals but their amount is small and does not affect the calculation. Processes of smelting in furnace and also in the converter is conditional on the fact that sulfur (S) is greater affinity to copper (Cu) than to iron (Fe). The percentage of copper in Matte depends on the amount of sulfur in cargo. Copper associated with assigned amount of sulfur and forms Cu2S while the rest non-oxidized sulfur forms FeS. It follows that, much more have sulfur much more will be formed with FeS with that reduced the amount of copper in Matte. The amount of sulfur to oxidize the whole amount of sulfur in cargo ranges from 13-30% and passes in the form of SO2 in gases. From the amount of iron in cargo an part passes Matte in form of FeS while the rest in slag in form of FeO. Losses of copper in slag are less than 0.9% of the amount of slag that with more precise definition of cargo and control of technological parameters of the process can be reduced.

Complementary use of X-ray methods to study ancient production remains and metals from Northern Portugal

Archaeological artefacts recovered at Castanheiro do Vento (Northern Portugal) were characterised by integrating macro and micro-energy dispersive X-ray fluorescence spectrometry (EDXRF) and scanning electron microscopy with X-ray microanalysis. The collection includes metallurgical remains (ceramic crucibles, a metallic nodule and a vitrified fragment) and metals (tools and ornaments) whose chronology spans from the Chalcolithic to the Roman Age. The study of production remains was able to identify distinct copper-based metallurgical operations including the smelting of copper ores, the melting of copper and tin and/or the melting of bronze scrap. Micro-EDXRF identified copper and arsenical copper tools as well as bronze and leaded bronze ornaments. The composition of tools (Cu with varying As contents: 0.46–3.6%) reveals an incipient technology, typical of the Chalcolithic till the Middle Bronze Age. On the contrary, ornaments are composed by different alloys – low tin bronze (4.8% Sn), high tin bronze (14.9% Sn) and high tin-leaded bronze (16.5% Sn and 2.4% Pb) − evidencing technological and economic choices that clearly indicate a late period such as the Roman Age. In conclusion, this multiproxy approach was able to study those ancient artefacts with a minimum impact on their archaeological and museological significance while providing important answers to the interpretation of the archaeological settlement and to better understand the metallurgical evolution in the Portuguese territory. Copyright © 2014 John Wiley & Sons, Ltd.

A multianalytical approach to study the Phoenician bronze technology in the Iberian Peninsula—A view from Quinta do Almaraz

Abstract Phoenician settlers were responsible for very important changes on the metallurgical practices used in the Iberian Peninsula during the first half of the 1st millennium BC. The study of copper-based artefacts from the Phoenician settlement of Quinta do Almaraz (Portugal) was used to characterise exogenous influences on local metallurgy. Micro-EDXRF analyses on cleaned metal surfaces identified copper, low-tin bronze (2.2 to 8.1 wt.% Sn) and leaded bronze artefacts (4.6 to 5.9 wt.% Pb). Additionally, significant impurities of iron were found (0.15 to 1.3 wt.% Fe) suggesting the smelting of copper ores under a strong reducing atmosphere. SEM-EDS and optical microscopy identified polygonal and nearly equiaxial α-copper grains with annealing twins and slip bands, which indicate comprehensive manufacturing procedures involving hammering and annealing operations. Vickers microhardness testing was utilised to assess the mechanical performance attained by ancient metallurgists. The microstructural features and microhardness values showed that a common approach was to workharden the artefact with a strong final hammering (discernible by high density of slip bands), although some examples also benefited from a highly skilful usage of the forging plus annealing cycles (uniform and very small grain size). Comparison with coeval collections from the southwestern Iberian Peninsula has established that the metals in the settlement of Quinta do Almaraz were produced by a different technology from the indigenous metallurgy.

EDXRF and micro-EDXRF studies of Late Bronze Age metallurgical productions from Canedotes (Portugal)

Metallurgical production in Central Portugal during the Late Bronze Age was primarily based on copper–tin alloys, despite influences from the Atlantic area where copper–tin–lead alloys are common. Metallic artefacts from archaeological site of Canedotes (Central Portugal) were analysed by EDXRF to establish the type of alloys present. Polished spots in selected artefacts were also analysed by micro-EDXRF to determine the major and minor elemental composition of the original alloys. The collection constitutes 18 copper–tin artefacts and one unalloyed copper artefact with tin and arsenic as minor constituents. Artefacts that require a thermomechanical finishing process, such as tools and weapons, seem to have improved control over the tin content. The composition of two buttons, one cramp and one metallic droplet suggest that some of the copper sources were rich in arsenic. Finally, the low iron content of the artefacts seems to agree well with the smelting of copper ores in crucible furnaces, a smelting process used in certain areas of the Iberian Peninsula until pre-Roman times.

An 8000-year history of landscape, climate, and copper exploitation in the Middle East: the Wadi Faynan and the Wadi Dana National Reserve in southern Jordan

Investigations of geomorphology, geoarchaeology, pollen, palynofacies, and charcoal indicate the comparative scales and significance of palaeoenvironmental changes throughout the Holocene at the junction between the hyper-arid hot Wadi 'Arabah desert and the front of the Mediterranean-belt Mountains of Edom in southern Jordan through a series of climatic changes and episodes of intense mining and smelting of copper ores. Early Holocene alluviation followed the impact of Neolithic grazers but climate drove fluvial geomorphic change in the Late Holocene, with a major arid episode corresponding chronologically with the ‘Little Ice Age’ causing widespread alluviation. The harvesting of wood for charcoal may have been sufficiently intense and widespread to affect the capacity of intensively harvested tree species to respond to a period of greater precipitation deduced for the Roman–Byzantine period – a property that affects both taphonomic and biogeographical bases for the interpretation of palynological evidence from arid-lands with substantial industrial histories. Studies of palynofacies have provided a record of human and climatic causes of soil erosion, and the changing intensity of the use of fire over time. The patterns of vegetational, climatic change and geomorphic changes are set out for this area for the last 8000 years.

The local and global dimensions of metalliferous pollution derived from a reconstruction of an eight thousand year record of copper smelting and mining at a desert-mountain frontier in southern Jordan

This paper establishes an eight thousand year history of anthropogenic metal pollution at one of the oldest, most important and longest sustained sites of the extraction and smelting of copper ores in the Old World: the Faynan Orefield in Jordan, which is located between the hyper-arid southern desert and the front of the wetter Mountains of Edom. The modern land surface is shown, in significant part, to be a complex palimpsest of archaeological sites, metal pollution of various ages and ore processing deposits. Quantitative and qualitative observations of the storage and cycling of heavy metals through the local natural and domestic systems have produced a body of information on processes with which the past has been interpreted. Heavy metal concentrations in semi-continuous sedimentary bodies indicate that over the last 1500 years, metals were removed by natural processes at a comparatively slow rate given the scale of the original anthropogenic metal burden: the proportions of lead with respect to copper have increased as the overall metal burden has been lowered. Distinctive anthropogenic metal-pollution signatures have been detected in ash- and charcoal-rich deposits that were discarded onto the banks of a perennial stream in the late Neolithic. At present, the nature of the human activities that might have produced these pollution signatures is unknown. Substantial metal pollution from industrial-scale smelting activity was present from the Early Bronze Age. The intensity of heavy metal pollution produced in Classical Times locally exceeded that recorded at major European copper smelting centres in the nineteenth century A.D. The pollution evidence indicates that intensive copper smelting at the immediate area took place until approximately the end of the Byzantine period; with the exception of one further minor episode of smelting radiocarbon dated to cal. BP 530–330. An observed partial, but perhaps significant, parallelism is also noted between this local record and the records of the metal burdens of the northern hemisphere determined at mire or ice-sheet sites at high-altitudes or high-latitudes. The paper discusses the extent to which this parallelism might be a geochemical indicator of the actual existence of “economic systems” of a geographical scope and scale to have both exercised substantial “pull” upon the resources of such isolated and difficult locations at the Wadi Faynan, and to have generated sufficient overall metal pollution to have materially altered the chemistry of the global atmosphere. The comparative absence of quantitative information upon the nature, spatial scale and impacts of human, industrial and natural processes affecting metal-pollution in other metal-rich arid lands provides a significant impediment to such approaches that seek to research “locally and think globally”.

Heteronuclear compounds of arsenic and antimony

Volatilization of secondary metals such as arsenic, antimony, and bismuth, during the smelting of copper ores, is important because of environmental and resource considerations. The Bureau of Mines, United States Department of the Interior, has been studying copper concentrate roasting in conjunction with the volatility of these minor constituents. Some unusual vaporization behavior initiated this supplemental paper which shows that when the mixed sulfides of arsenic and antimony are heated, the volatilization of arsenic is retarded and the volatilization of antimony increased. Mixed oxides of arsenic and antimony also exhibit exceptional volatilization behavior. These anomalous vaporization behaviors are attributed to the formation of heteronuclear compounds of arsenic and antimony, but the colligative properties of solutions may also be a factor.

Atmospheric sulphur: Natural and man-made sources

The principal processes by which sulphur compounds are emitted into the atmosphere are reviewed in the light of the most recent data. The main natural source of the atmospheric sulphur is biogenic activity, although considerable uncertainty still exists regarding both the nature and the amounts of the principal reduced sulphur compounds generated in this way. The combustion of coal and petroleum accounts for ca 90% of the total sulphur emitted by man, the only other large source being the smelting of copper ores. Comparisons are made between the man-made emissions calculated on a per unit area and a per capita basis for the whole Earth and for some industrialized countries. Estimates for 1976, made with the aid of emission factors, indicate that man's activities generate a total of 104 Tg Sa −1. This already represents over 40% of all atmospheric sulphur emissions and, if it continues to increase at the present rate, will exceed Nature's contribution well before the end of the present century.