Ancient silver extraction in the Montevecchio mine basin (Sardinia, Italy): micro-chemical study of pyrometallurgical materials

Different pyrometallurgical materials such as slags, refractory materials and thermally treated lead ores likely related to smelting and extractive processes and chronologically related to Punic and Roman periods (IV–III BC) have been found at Bocche di Sciria and Conca e Mosu in the Montevecchio mine basin (south western Sardinia, Italy), where archaeological findings and classical authors locate extractive metallurgy activities since pre-Roman times. By means of the combined use of X-ray diffraction (XRD), scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectrometry (EDS), selected-area X-ray photoelectron spectroscopy (XPS) and optical microscopy (OM), micro-chemical and micro-structural investigations have been carried out in order to identify the nature of the pyrometallurgical materials, to decipher the processes carried out there and their technological steps and to determine the technological level of competence reached by the ancient metallurgists. The results confirm that the findings can be associated with smelting and extractive processes carried out close to the metal ore deposits first for the argentiferous lead production and, then, for the silver recovery via a cupellation process. Finally, the results disclose the high level of technological competence of the ancient metallurgists able to carry out complex high-temperature processes to treat the argentiferous lead ores and to recover low amounts of silver via high-temperature lead-selective oxidation.     

Phase analytical studies of industrial copper smelting slags. Part I: Silicate slags

The pyrometallurgical extraction of copper from sulfide ore concentrates is determined by the behaviour of the associated iron during smelting. Hence, ⁵⁷Fe Mössbauer spectroscopy is an attractive tool for studying the phases in silicate slags from German and Chilean smelting plants. Other methods used were ore microscopy, electron microprobe analysis, and X-ray powder diffraction.     

铜陵、南陵地区古铜矿冶遗址炉渣的科技研究

安徽铜陵、南陵地区铜矿资源丰富，古代矿冶遗址数量众多，最早可追溯至二里头文化时期。各遗址遍地分布的炉渣、炉壁等矿冶遗物，为研究中国早期的铜矿冶炼技术提供了大量的实物资料。本工作采用X射线衍射分析（XRD）、X射线荧光分析（XRF）和扫描电镜能谱分析（SEM-EDS）等多种技术手段，对安徽铜陵、南陵地区古铜矿冶遗址的炉渣样品进行检测分析，以了解该地区早期的铜矿冶炼技术。XRD分析结果显示，所检测炉渣样品的物相以铁橄榄石、辉石、钙铁辉石为主，伴有石英、方石英、磁铁矿等矿物，符合炼铜渣的物相特征。根据炉渣的SiO₂，CaO和Fe₂O₃的含量，可将51个炉渣样品分为三大类：Ⅰ类炉渣、Ⅱ类炉渣和Ⅲ类炉渣。其中，Ⅰ类炉渣钙、硅、铁含量较高，其CaO含量远高于Ⅱ类和Ⅲ类炉渣，为铁硅钙系。相较而言，Ⅱ类炉渣为高铁系，其Fe₂O₃含量明显高于Ⅰ类和Ⅲ类炉渣；Ⅲ类炉渣为高硅系，其SiO₂含量较高，钙、铁含量较低。所有炉渣样品的铁含量均高于普通熔炼渣，结合其物相分析结果，可推测全部炉渣为冶炼渣。Ⅰ类、Ⅱ类炉渣的Ca和Fe含量呈现很强的负相关性，且波动范围很大，显示二者的含量并非人工调控，更可能是来自矿石中的天然成分。据此可以推测，本地区的早期工匠可能尚未认识到含钙和含铁助熔剂的作用，没有掌握不同类型铜矿石的配矿技术。SEM-EDS的分析结果表明，炉渣中的金属颗粒夹杂以冰铜、红铜和砷铜为主，表明该地区同时存在红铜和砷铜的冶炼活动。不同品位的冰铜颗粒大多来自不同遗址，尚没有在同一遗址发现较多品位依次升高的冰铜颗粒，因而难以确认冰铜熔炼环节的存在，不能证明上述遗址是否已采用了“硫化铜矿-冰铜-铜”的冶炼技术。所发现的冰铜颗粒，可能是采用硫化铜矿死焙烧工艺或混合矿原料冶炼的结果。铜陵夏家墩遗址炉渣中砷铜颗粒的存在，表明该地区早至西周时期，很可能已掌握了采用共熔还原法冶炼砷铜的技术。相关研究结果，对探讨砷铜技术的起源和传播，以及中国早期冶金技术的发展和生产组织状况均具有重要意义。     

A model-independent description of dt and d3He systems near low-energy resonances

Very important information for the reconstruction of archaeometallurgical processes can be obtained from slags. The determination of the mineralogical and chemical composition of the major components has made it possible to derive the most important operative conditions of the ancient smelting processes. However, the loss of copper in the form of particles mechanically entrained in the slags is also of great interest because it can give us information about possible intermediates.Parts I and II have been published in Hyperfine Interactions 67 (1991) 473 and 70 (1992) 1005.     

The reconstruction of the first copper-smelting processes in Europe during the 4th and the 3rd millennium BC: where does the oxygen come from?

From the end of Chalcolithic times (end of the 4th millennium BC) up to the end of the Bronze Age (1st millenium BC), copper production increases dramatically in Western Europe. However, due to the scarcity of technology-related archaeological data, the technological background sustaining the transition to mass production modes remains poorly understood. The main archaeological clues concerning metal production stem from the metallurgical waste, namely copper slags. Those complex materials may be a genuine chemical footprint of the process. In particular, it may bring new insights on one main issue of the process reconstruction: the origin of the oxygen in the system. A new analytical methodology based on both mass-balance calculation and quantification of Fe³⁺ contents in copper slags (Mössbauer spectroscopy, electronic microprobe and Synchrotron μ-XANES at the Fe-K-edge) has been set up. This methodology enables us to distinguish between the solid and gaseous sources of oxygen in a broad range of working conditions, thus yielding new features for the understanding of the first smelting processes dealing with copper sulphides in Western Europe 4000 years ago.     

汤家墩遗址冶炼遗物的科技研究

采用X射线荧光仪、X射线衍射分析仪、扫描电子显微镜及激光剥蚀电感耦合等离子体质谱等现代检测手段对汤家墩遗址的炉壁、炉渣及炉渣中的金属颗粒进行分析,进而探讨汤家墩古铜冶炼技术。结果表明：汤家墩遗址的炉壁为冶炼炉炉壁,炉渣为还原渣;根据铜颗粒中As,Ag,Sb,Bi等微量元素的含量,可以计算出汤家墩遗址炼渣中的铜颗粒来自于硫化铜矿的概率高达87.87%以上,从而表明汤家墩是采用“硫化铜—铜”的冶铜工艺进行冶炼的早期青铜文化遗址。这一研究结果不仅有利于枞阳地区青铜文化遗产的深入研究,而且对于探究枞庐地区青铜冶铸技术的发展与演变具有非常重要的意义。     

Mössbauer study of ancient iron smelting slag in Japan

For an investigation of the ancient iron manufacturing technique, a reproducing experiment was carried out by archaeologists, where ancient type of iron smelting furnace was built and iron sand with high titanium contents was used as the raw material. During the operation of furnace, a large amount of slag flowed away from the furnace. In order to investigate the possibility for the estimation about the operative condition of furnace and the raw material, ⁵⁷Fe Mössbauer spectroscopy was applied for characterizing these slags and it was found that these slags mainly consisted of ferropseudobrookite (FeTi₂O₅).     

Thermodynamics applied to iron smelting techniques

Thermodynamics allows us to understand the chemical reactions occurring inside an experimental archaeometallurgical shaft furnace for iron smelting. The production of an iron bloom, with the so-called direct process, is described in a daily pyrometallurgical cycle. The experiences suggest that, as higher and better blown furnaces were built for improving the production, different reactions have been involved and a new material, pig iron, has been obtained     

Hematite from a mining area in the east border of Quadrilátero Ferrífero, Minas Gerais, Brazil

Iron oxides are dominant minerals in many geo-domains of economical interest, as iron ore mines. Knowing the main mineral transformation pathways is a fundamental step to plan prospecting new mineral deposits. This study aimed at contributing to a better understanding of the chemical and mineralogical processes related to the genesis and transformations of iron oxides involving hematite in an iron-ore mine of the east border of Quadrilátero Ferrífero, Minas Gerais, Brazil. Two representative geo-samples were analyzed with synchrotron radiation X-ray diffraction (XRD), ⁵⁷Fe Mössbauer spectroscopy, X-ray fluorescence and saturation magnetization (σ) measurements. The iron content varied from 65 to 69 mass% Fe. From XRD data, hematite is indeed the major mineral for all samples but characteristic reflections of goethite and magnetite also appear. For the magnetic sample, σ = 6.9 J T^???1 kg^???1. 298 K- and 110 K-Mössbauer data allow characterizing hematite in these iron-rich geo-materials.     

Mössbauer mineralogy on the Moon: The lunar regolith

A first-order requirement for spacecraft missions that land on solid planetary objects is instrumentation for mineralogical analyses. For purposes of providing diagnostic information about naturally-occurring materials, the element iron is particularly important because it is abundant and multivalent. Knowledge of the oxidation state of iron and its distribution among iron-bearing mineralogies tightly constrains the types of materials present and provides information about formation and modification (weathering) processes. Because Mössbauer spectroscopy is sensitive to both the valence of iron and its local chemical environment, the technique is unique in providing information about both the relative abundance of iron-bearing phases and oxidation state of the iron. The Mössbauer mineralogy of lunar regolith samples (primarily soils from the Apollo 16 and 17 missions to the Moon) were measured in the laboratory to demonstrate the strength of the technique for in-situ mineralogical exploration of the Moon. The regolith samples were modeled as mixtures of five iron-bearing phases: olivine, pyroxene, glass, ilmenite, and metal. Based on differences in relative proportions of iron associated with these phases, volcanic-ash regolith can be distinguished from impact-derived regolith, impact-derived soils of different geologic affinity (e.g., highlands and maria) can be distinguished on the basis of their constituent minerals, and soil maturity can be estimated. The total resonant absorption area of the Mössbauer spectrum can be used to estimate total FeO concentrations.     

The metallurgic furnaces at the Curamba Inca site (Peru): a study by Mössbauer spectroscopy and X-ray diffractometry

The Inca site at Curamba is located in the Province of Apurimac in the southern highlands of Peru where, according to some historians, several thousand furnaces used for ore smelting were found. For this work, four samples of burned soil were gathered from these furnaces and classified as Curamba1, Curamba2, Curamba3, and Curamba4, and studied using transmission Mössbauer spectroscopy (TMS) and X-ray diffractometry (XRD). The mineralogical composition of the samples was determined by XRD and the structural sites in the minerals occupied by iron cations were characterized by TMS. Moreover, an attempt was made to determine the maximum temperature reached in these furnaces using the refiring technique of the samples in an oxidizing environment and monitoring the structural modifications at the iron sites by changes in the Mössbauer hyperfine parameters. The TMS results of Curamba2 show that the maximum temperature reached in this furnace was about 900°C, in agreement with the mineralogical composition found by XRD. In the case of Curamba1 and Curamba4 the maximum temperature estimated was about 400°C.     

Spectroscopic analysis of the riboflavin—serum albumins interaction on silver nanoparticles

Metallic nanoparticles (NPs) supported on oxides thin films are commonly used as model catalysts for studies of heterogeneous catalysis. Several 4d and 5d metal NPs (for example, Pd, Pt and Au) grown on alumina, ceria and titania have shown strong metal support interaction (SMSI), for instance the encapsulation of the NPs by the oxide. The SMSI plays an important role in catalysis and is very dependent on the support oxide used. The present work investigates the growth mechanism and atomic structure of Rh NPs supported on epitaxial magnetite Fe₃O₄(111) ultrathin films prepared on Pd(111) using the Molecular Beam Epitaxy (MBE) technique. The iron oxide and the Rh NPs were characterized using X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction and photoelectron diffraction (PED). The combined XPS and PED results indicate that Rh NPs are metallic, cover approximately 20 % of the iron oxide surface and show height distribution ranging 3–5 ML (monolayers) with essentially a bulk fcc structure.     

The use of explosion in fabrication of new materials

Abstract

The energy of high explosives have been widely used for some time in improving characteristics of the existing materials as well as for creating new materials having good prospects for different technological applications. The two last decades witnessed especially remarkable results in this field. In this paper we shall give a concise review of explosive metal hardening and welding processes, explosive compaction of metalxnon-metal materials as well as of the equipment used in industrial applications of these and some other processes of explosive treatment of materials.     

Characterization of products emanating from conventional and microwave energy roasting of chalcopyrite (CuFeS2) concentrate

Chalcopyrite concentrate (83% CuFeS₂, 3% FeS₂ and 14% ZnS) which is a typical feed to the matte smelting process for copper extraction via pyro metallurgical route has been roasted with microwaves. Comparison of mineralogical phases obtained was made with the case of conventional roasting. Resulting calcines were characterised with Mössbauer spectroscopy and XRD. It was observed that complete oxidation (dead roasting) of the chalcopyrite was achieved after 10 min with microwaves while 20 min were required in the conventional route. The mineralogical phases found in the dead-roasted calcines produced from microwave roasting of this chalcopyrite concentrate were the hematite (Fe₂O₃), franklinite (ZnFe₂O₄), copper-rich ferrite (Cu_1?x Zn _x Fe₂O₄, x?≤?0.5), and copper ferrite (CuFe₂O₄). The findings of this work indicated that it was technologically feasible to oxidize the chalcopyrite with microwaves using a 2.45 GHz multimode applicator.     

X-ray fine structure study and bonding in some ferrites

Extended X-ray absorption fine structure (EXAFS) of the iron K edges in copper, cobalt, zinc and manganese ferrites is studied and the EXAFS parameter α of the Lytle, Sayers and Stern's theory is shown to be a measure of fractional covalency. The linear relationship between metal to oxygen (iron to oxygen) distance and the parameter α leads us to conclude that the copper ferrite is the most covalent among the four ferrites studied in the present investigation.     

Relation of X-ray photoelectron spectra with the magnetic properties of high-spin pivalic Mn<Superscript>II</Superscript> and Fe<Superscript>II</Superscript>

Trimethylacetate complexes of manganese and iron of identical structure have been studied by X-ray photoelectron spectroscopy. The increase in both spin-orbit splitting and difference in the binding energy of satellite and M 2p _3/2 line with an increase in magnetic moment is observed for the manganese complexes with oxygen and partially nitrogen environment of metal atoms. A reverse dependence is found for iron complexes. It is suggested that binuclear and hexanuclear manganese complexes show antiferromagnetic interactions, while similar iron complexes exhibit ferromagnetic interactions.     

A197Au and57Fe mössbauer study of the roasting of refractory gold ores

The transformation of chemically bound gold into metallic gold during industrial scale roasting of an arsenical gold ore concentrate from the Fairview Mine, Eastern Transvaal, has been studied quantitatively by¹⁹⁷Au Mössbauer spectroscopy. The iron compounds in the concentrate, mainly FeAsS and FeS₂ and their transformations during roasting have been studied by⁵⁷Fe Mössbauer spectroscopy. The bound gold is found to convert into the metal in parallel to the decomposition of FeAsS and the increase in cyanide leachability. this shows that the refractory character of the ore is caused by the chemical bonding of the gold rather than by the physical inclusion of small, discrete metallic particles in the matrix of FeAsS or FeS₂. The ratio of thef-factors of gold bound in the FeAsS component of a refractory ore and of metallic gold was determined to bef(Au:FeAsS)/f(Au)=1.48±0.09.     

Synthesis and magnetic properties of Cu-coated Fe composite nanoparticles

The Fe/Cu nanocomposites with iron as core and copper as shell have been successfully synthesized by a two-step reduction method. A spherical nanoparticle of γ-Fe was first fabricated by the reduction of ferrous chloride, and then the Fe particle was coated by nanocrystalline Cu through the reduction of copper sulfate. The thickness of copper shell has been tuned by varying the initial concentration of copper sulfate. The morphology, crystalline structure, chemical composition and magnetic properties of the products were investigated by using transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and vibrating sample magnetometer (VSM). It was found that the saturation magnetization (M_s) values of the Fe/Cu core–shell particles are varied owing to the different thickness of copper layer. Though the M_s value of the Fe/Cu nanocomposite is lower than that of pure iron nanoparticles, the higher M_s value (22.411 emu/g) of the Fe/Cu composites is also investigated. The result of the thermogravimetric analysis (TGA) showed the enhanced antioxidation capacity of the Fe/Cu nanocomposites. This kind of nanocomposites combined the excellent magnetism of iron and the electronic, thermal conductivity of copper, suggesting potential application as a novel electromagnetic material.     

Synthesis of new material compositions with special properties under impact-dynamic conditions

This study examines the problems of creating new structural forms under impact-dynamic influence of ionic metal beams on a surface in order to expand the functional properties of iron construction materials. We investigated potential applications under various extreme environmental conditions (corrosion and radiation resistance, thermal stability) to evaluate physical and chemical processes that give rise to new properties which are different from equilibrium conditions for synthesized iron-based composites that include surface alloy compositions. The synthesis of composites was carried out in a vacuum installation equipped with an electroarc evaporator. Double surface iron composite alloys were synthesized using microplasma technology. Penetration depth of the ions of group IV-VI metals into iron was estimated using Monte Carlo methods to model binary collisions. This estimation was consistent with the results of the local X-ray spectrum analysis. Nuclear gamma resonance and local X-ray spectrum analysis was used to assess transformation of the structure of the alloyed materials into new structural forms, changing their properties.     

Scanning tunneling microscopy and spectroscopy on iron-pnictides

Tremendous excitement has followed the recent discovery of superconductivity up to T_c = 56 K in iron–arsenic based materials (pnictides). This discovery breaks the monopoly on high-T_c superconductivity held by copper-oxides (cuprates) for over two decades and renews hope that high-T_c superconductivity may finally be theoretically understood and widely applied.Since scanning tunneling microscopy (STM) and spectroscopy (STS) have been key tools in the investigation and understanding of both conventional and unconventional superconductivity, these techniques are also applied to the pnictides. While the field is still in its early stages, several important achievements by STM and STS have been reported on the pnictides. In this paper, we will review their contribution towards an understanding of superconductivity in this new class of materials.