Copper tailings reprocessing

in English Copper is widely used in the modern world. An excellent conductor of electricity, it is used in the electrical industry, in the construction industry because of its good corrosion resistance, and in the manufacture of heat exchangers in heating and cooling systems owing to its excellent thermal conductivity. Copper production has increased throughout the twentieth century, and this trend has continued over the last twenty years. The demand for copper is expected to increase significantly by the year 2030. Owing to the high prices of this metal and the lack of deposits, part of the demand can be met by extraction from copper-bearing tailings. In the past, owing to the lower level of technological development and lower copper prices, materials comparable in copper content to the copper ores mined today have ended up in tailings. Since these are already processed materials, the costs of mining, crushing and milling are largely eliminated, making them promising raw materials. The article presents the technological possibilities of reprocessing and also estimates the amount of copper that could be obtained worldwide in this way.

Supergene Copper and the Ancient Mining Landscapes of the Atacama Desert: Refining the Protocol for the Study of Archaeological Copper Minerals through the Case Study of Pukara de Turi

Northern Chile is home to the world’s largest copper ore deposits, which have been exploited for thousands of years by different groups, at varying scales and for different purposes. In this context, it is important to develop new protocols to characterise the mineralogical variability of archaeological copper ores. A comprehensive and representative methodology in the analysis of minerals, the application of non-destructive analytical techniques, and the combination of insights from geological, archaeological and local knowledge are key to developing a copper mineral repository of the Atacama Desert area. Geochemical analyses were applied to the study of 568 samples from the archaeological site Pukara de Turi, with different techniques such as micro-XRF, XRD, QEMSCAN, Raman spectroscopy and technological studies. This exhaustive analysis allowed for the recognition of two mineralogical associations: atacamite/brochantite (99%) and azurite/chrysocolla (1%). The study of various minerals allows data to be interpreted more reliably and to trace the likely geological sources of these minerals. The azurite/chrysocolla samples appear to belong to the same mineral association found in the Cerro Verde district, which is probably the source of these samples. The atacamite/brochantite samples appear to come from more than one geological source, including, but not limited to, Chuquicamata-Radomiro Tomic and El Abra-Conchi.

Brass products in the coronet excavated from an M2-numbered Sui-Tang-dynasty tomb situated in Kun Lun Company in Xi'an, Shaanxi

Ancient Chinese brass smelting technology has promoted the invention of zinc smelting, thus becoming an important part of the metallurgical history. However, the information concerning its origin and development is still controversial. In that regard, thorough analysis of composition and structure of the early brass is crucial for studying various stages of the ancient brass smelting technology history. This study aimed to investigate brass artifacts from Kunlun M2 tomb in Xi'an, Shaanxi, dating back during Sui to early Tang Dynasty (581–712 AD). The composition and metallographic characterization of the materials was performed using XRF, SEM–EDS and metallographic analysis. According to the results, brass was composed of 83 wt% of copper, 12 wt% of zinc, and 3 wt% of tin. Furthermore, its microstructure consisted of α-isometric single crystals with some slip lines and a few twinned grains. This indicated that brass was obtained by melting an appropriate mixture of zinc ores and copper ores at a temperature above 920 °C. Furthermore, brass support components were installed on the coronet after integral hot forging and partial cold shaping. Besides, the use of brass in the coronet was in conformity with the social hierarchy of that historical period, and also reflected the attention paid to the properties of materials.

The 2018–2019 excavation of the Xiwubi site in Jiangxian County, Shanxi

A series of excavations were conducted at the Xiwubi site during 2018–2019, yielding abundant copper metallurgy remains dating to the Erlitou and Erligang cultural periods. Archaeological features include remains of smelting furnaces, charcoal kilns, houses, and refuse pits. A variety of artifacts were retrieved, ranging from copper ores, fragments of smelting furnaces, crucibles, and slag to objects made of pottery, stone, and bone. It is the first copper metallurgy site found in the Zhongtiao Mountains in the vicinity of the heartland of the Xia and Shang dynasties. Characterized by early dates, large scale, and advanced specialization in copper metallurgy, the excavation of the Xiwubi site provides substantial materials for the study of mining and use of copper ore resources by the Xia and Shang dynasties, as well as interactions between copper metallurgy and the destiny of the royal courts.

Volcanogenic Deposits of Non-ferrous Metals in the Lesser Caucasus and Eastern Pontides

The paper presents brief characteristics of geological environments of ore deposit occurrences in Turkey, Georgia and Armenia. They can be attributed to Kuroko-type deposits, being distinguished by the character of ore accumulation. To the west, in Turkey, there are epigenetic and hydrothermal-sedimentary copper-zinc deposits that were formed in deep restricted basinal settings. An example of the latter is the Chayeli deposit.To the east, in the Caucasus, we have predominantly only epigenetic deposits. Besides, in the Bolnisi mining district (Georgia) there is the Madneuli deposit which represents an example of polyformational deposit. Here, within the restricted territory, have been concentrated:barite, barite-polymetallic, gold-bearing secondary quartzite, large-scale stockworks of copper ores. Judged by the 87Sr/86Sr ratios, some volcanites which are spatially associated with ores, might have been products of the “differentiation” of undepleted mantle, or other magmas that were generated in the lower part of the earth crust.In the Alaverdi ore district in Armenia, there are Jurassic volcanodepressions that host copper, copper-zinc and barite-sulfide ores. All the deposits of the Alaverdi district, porphyry copper including, contain economic reserves of ores.On the basis of available literature material and our own data, there has been created a mental-logical geological-genetic model of volcanogenic deposits.

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).

Value of Rapid Mineralogical Monitoring of Copper Ores

An essential operation in the mineral processing of copper ores into concentrates is blending, as it guarantees a constant feed for the flotation cells, increases metal recovery rate and reduces tailings. In this study, copper ores from Huelva province (Spain) were investigated by quantitative XRD (X-ray diffraction) methods to optimize blending and detect penalty minerals, which can affect flotation and concentrate quality. The Rietveld method in combination with cluster analysis, PLSR and more traditional chemical analysis provide a more complete and in-depth characterization of the ore and the whole process. The mineralogical monitoring can be fully automated to enable real-time decision making.