Archaeo-metallurgical studies of tuyeres and smelting slags found at Tharros (north-western Sardinia, Italy)

A large number of pyrometallurgical materials such as tuyeres, slags and refractory tools likely associated with metal extraction processes have been found at Tharros (north-western Sardinia, Italy) during archaeological excavations stratigraphically related to the Phoenician–Punic period (VI–III centuries BC). Micro-chemical, micro-structural and mineralogical studies have been carried out by means of the combined use of X-ray diffraction (XRD), selected-area X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) combined with energy-dispersive X-ray analysis (EDS) in order to identify pyrometallurgical processes and main relevant technological parameters. The results reveal that tuyeres, slags and refractory tools can be associated with an iron ore smelting process to extract the metal by slagging the unwanted by-products. Moreover, temperature and duration of the smelting process have been estimated through mineralogical studies and by a comparative analysis between the micro-chemical and structural features of thermally treated refractory materials and tuyeres. The results disclose the high level of technological competence of the ancient metallurgists able to carry out complex high-temperature processes to extract iron from ores by separating the metal from unwanted siliceous species.     

197Au Mössbauer study of gold ores,mattes, roaster products,and gold minerals

The chemical state of gold in gold ores, mattes and roaster products has been studied by¹⁹⁷Au Mössbauer spectroscopy. Gold minerals were studied in order to provide reference data for the ore spectra.⁵⁷Fe Mössbauer spectroscopy was used to monitor the iron compounds always present in gold ores and to follow their transformations caused by smelting and roasting.     

Influence of annealing treatment on microstructure and soft magnetic properties of Fe-B-P nanoparticles prepared by aqueous chemical reduction

During the recovery of base metals from the Bushveld Igneous Complex ores, South Africa, a two-stage process is used to ensure complete recovery of nickel from the ore. A nickel flash smelting furnace is initially used to obtain the valuable metal but the loss of nickel in the slag amounts to about 4 % and thus an electric slag-cleaning furnace has to be subsequently used to reduce the loss of the valuable metal to less than 0.5 % nickel oxide in the slag. The Fe^2?+?/Fe^3?+? ratio and mineralogy in the two different furnaces differ and can be used as a tool to determine the efficiency of the nickel recovered in the two-stage process. By means of XRD, SEM/EDS and Mössbauer spectroscopy the Fe^2?+?/Fe^3?+? ratio and the amount of magnetite was determined in each furnace, which was then used as an indicator of the effectiveness of the whole process.     

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。     

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。     

用国产熔融炉熔片X射线荧光光谱法分析铁精矿

研究试验了国产电加热式六头熔融炉对铁矿石熔样,建立了熔样条件与方法,经试验及生产应用,熔样效果好,精密度合乎要求.     

On the nature of iron-chromium oxides in stainless steel steelmaking slags

A number of slags from electric steelmaking production of AISI 420 and AISI 304 steels, were examined by Mössbauer spectroscopy. The slag samples were taken before and after oxygen blowing.The slag constitution showed the presence of a metallic part, MO mixed oxide and Fe-Cr spinel (Fe²⁺ Fe _x ³⁺ Cr_2–xO₄ x<1).     

Characterization of iron in airborne particulate matter

In this work soil samples, iron ore and airborne atmospheric particulate matter (PM) in the Metropolitan Region of Belo Horizonte (MRBH), State of Minas Gerais, Brazil, are investigated with the aim of identifying if the sources of the particulate matter are of natural origin, such as, resuspension of particles from soil, or due to anthropogenic origins from mining and processing of iron ore. Samples were characterized by powder X-ray diffraction, X-ray fluorescence and ⁵⁷Fe-Mössbauer spectroscopy. The results showed that soil samples studied are rich in quartz and have low contents of iron mainly iron oxide with low crystallinity. The samples of iron ore and PM have high concentration of iron, predominantly well crystallized hematite. ⁵⁷Fe-Mössbauer spectroscopy confirmed the presence of similar iron oxides in samples of PM and in the samples of iron ore, indicating the anthropogenic origin in the material present in atmosphere of the study area.     

Helium and Argon Isotope Abundances in Rocks of Lavozero Alkaline Massif

Abstract

He and Ar isotope abundances in alkaline rocks of the Lovozero layered ore-bearing complex are used to discuss the origin of hydrogen-hydrocarbon gases (HHG).

Three procedures to extract - crushing, milling and melting - and the chemical analysis of these gases have been described, and then the isotope analysis of the ratios of ³He/⁴He and ⁴⁰Ar/³⁶Ar is related. It is suggested, that (⁴He/⁴⁰Ar)_rad ratios and ⁴He concentrations decrease and ³He/⁴He increase with the distance from the ore zone, the former ratio being the most contrast indicator of ore mineralization. A direct correlation has been revealed between helium isotopic ratios and methane concentrations.

The results of measurements confirm the idea on the crustal origin of HHG.     

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.     

A high-temperature laser ion source for trace analysis and other applications

We report here on the development of a high-temperature laser ion source useful for trace analysis and other applications. It consists of a high temperature ionization chamber, three tunable dye lasers pumped by copper vapor lasers for stepwise resonant ionization and a Mattauch-Herzog mass spectrometer for the analysis of photo-ions. The principle of the laser ion source and its theoretical efficiency are discussed, where the efficiency of a laser ion source is the ratio of photo-ions extracted out to the number of atoms introduced into the cavity. Experimentally, an efficiency of 2×10^–3 has been achieved for technetium. The scheme of gated detection is described which is used for suppressing isobaric background of molybdenum. The possible improvements are briefly mentioned for achieving isotopic analysis of 10⁸ atoms of ^97,98Tc in the presence of 10¹⁵ atoms of molybdenum, as separated chemically from molybdenum ore. Such an analysis of technetium isotopes produced in molybdenite ore by a (v,e ^–) reaction, is expected to yield information about the solar neutrino flux.Permanent address: Bhabha Atomic Research Centre, Bombay 400085, India     

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).     

Mössbauer effect study of ferric arsenates from an abandoned gold mine

⁵⁷Fe Mössbauer measurements have been used to determine the iron phases resulting from weathering of arsenopyrite ore from an abandoned gold mine stockpile. The principal product is the basic ferric arsenate, pharmacosiderite, with smaller amounts of scorodite, ferrihydrite and goethite and some untransformed pyrite and clay minerals. The broadened low temperature spectra of pharmacosiderite suggest that the onset of magnetic ordering is hampered by disorder in the crystal structure.     

The self-absorption correction factors for 210Pb concentration in mining waste and influence on environmental radiation risk assessment

The radioactive lead isotope ²¹⁰Pb occurs in waste originating from metal smelting and refining industry, gas and oil extraction and sometimes from underground coal mines, which are deposited in natural environment very often. Radiation risk assessment requires accurate knowledge about the concentration of ²¹⁰Pb in such materials. Laboratory measurements seem to be the only reliable method applicable in environmental ²¹⁰Pb monitoring. One of the methods is gamma-ray spectrometry, which is a very fast and cost-effective method to determine ²¹⁰Pb concentration. On the other hand, the self-attenuation of gamma ray from ²¹⁰Pb (46.5 keV) in a sample is significant as it does not depend only on sample density but also on sample chemical composition (sample matrix). This phenomenon is responsible for the under-estimation of the ²¹⁰Pb activity concentration level often when gamma spectrometry is applied with no regard to relevant corrections. Finally, the corresponding radiation risk can be also improperly evaluated. Sixty samples of coal mining solid tailings (sediments created from underground mining water) were analysed. Slightly modified and adapted to the existing laboratory condition, a transmission method has been applied for the accurate measurement of ²¹⁰Pb concentration . The observed concentrations of ²¹⁰Pb range between 42.2?÷?11,700 Bq·kg^–1 of dry mass. Experimentally obtained correction factors related to a sample density and elemental composition range between 1.11 and 6.97. Neglecting this factor can cause a significant error or underestimations in radiological risk assessment. The obtained results have been used for environmental radiation risk assessment performed by use of the ERICA tool assuming exposure conditions typical for the final destination of such kind of waste.     

197AU,57Fe and121Sb Mössbauer study of gold minerals and ores

A survey of the¹⁹⁷Au Mössbauer spectra of naturally occurring gold species is given. Gold minerals have been studied as natural specimens or as synthetic analogues. Gold impurities have been identified in pyrites and arsenopyrites. An example of the use of¹²¹Sb, and⁵⁷Fe Mössbauer spectroscopy in characterizing gold-bearing ore minerals is given.     

Mössbauer spectrometry as a tool for mining industry: Application to an uranium-bearing mineralization of albitized granite

Mössbauer Spectrometry is a suitable method to characterize the evolution of the redox conditions during mineralization processes and may be used as a guide of prospection. An application to the prospection of uranium-bearing mineralization associated with an albitized granit located in the Bahia State in Brazil is presented. A calibration of the Mössbauer parameters is performed from a set of appropriate synthetic ferri-diopsides. On the natural samples, the ore deposition, observed by the decreasing of the Fe²⁺/Fe³⁺ ratio, is related to an increasing of the oxygen fugacity in the hydrothermal fluids.     

Application of 57Fe Mössbauer spectroscopy as a tool for mining exploration of bornite (Cu5FeS4) copper ore

Nuclear resonance methods, including Mössbauer spectroscopy,are considered as unique techniques suitable for remote on-line mineralogical analysis. The employment of these methods provides potentially significant commercial benefits for mining industry. As applied to copper sulfide ores, Mössbauer spectroscopy method is suitable for the analysis noted. Bornite (formally Cu₅FeS₄) is a significant part of copper ore and identification of its properties is important for economic exploitation of commercial copper ore deposits. A series of natural bornite samples was studied by ⁵⁷Fe Mössbauer spectroscopy. Two aspects were considered: reexamination of ⁵⁷Fe Mössbauer properties of natural bornite samples and their stability irrespective of origin and potential use of miniaturized Mössbauer spectrometers MIMOS II for in-situ bornite identification. The results obtained show a number of potential benefits of introducing the available portative Mössbauer equipment into the mining industry for express mineralogical analysis. In addition, results of some preliminary ^63,65Cu nuclear quadrupole resonance (NQR) studies of bornite are reported and their merits with Mössbauer techniques for bornite detection discussed.     

Mössbauer study of iron ore from El Hobo,Huila, Colombia

Iron ore from the El Hobo municipality located in the Huila department in Colombia (2^°35^′7^″N 75^°13^′27^″E) was studied by Mössbauer spectroscopy. The material was quite inhomogeneous, consisting of light brown and dark brown concretions of up to about a centimeter in size, and a sandy fraction. Mössbauer spectra at ambient temperature and at 4.2 K were taken of the two kinds of concretions and the sandy fraction. The concretions contain iron mainly as goethite with only a few percent of hematite. The sandy fraction contains goethite and hematite in roughly equal amounts and a minor fraction of divalent iron that splits magnetically at 4.2 K and may be an impure kind of siderite.     

Hyperfine structure of 57Fe in minerals from a manganese ore deposit

Investigations based on ⁵⁷Fe Mössbauer spectroscopy and powder X-ray diffraction report the existence of siderite in a manganese ore deposit in the city of Conselheiro Lafaiete, Minas Gerais, Brazil. Mössbauer parameters at 110 K indicated the isomorphous substitution of Fe^2?+? in siderite structure by other cations such as Ca^2?+? and Mg^2?+?, resulting in the distortion of siderite structure. The proposed mechanism suggests the formation of siderite and it is consistent with the process of carbonate formation in reducing environments.     

A suggested source of element 126

The isolation of macro amounts of pure element 126, whose observation has recently been reported, has important consequences for the discovery of elements from atomic number ～ 106 to 126 and their chemical, atomic and nuclear properties. It is suggested that the organic extractant commercially used to purify Ce from the rare earth mineral, bastnasite, should be used to concentrate element 126. This extractant which is recycled in the treatment of large amounts of the appropriate ore, is usually effective in the concentration of²⁴⁴Pu which should be chemically similar to element 126.