Microprobe Research Articles

Electrochemical chloride extraction from contaminated concrete structures using anodic nickel electrode

ABSTRACT An attempt was made, at the laboratory level, to apply new external anode of an electrochemical chloride extraction (ECE) system based on Ni chemical deposition on concrete specimen surface. The procedure relied on electroless bath chemical deposition to apply anodic electrode of nickel on concrete samples. The procedures and experimental conditions of the nickel deposition on the concrete were carefully addressed. The influence of Ni films characteristics, as external anode in ECE system, on the chloride electrochemical extraction (ECE) process was investigated. ECE performance in comparison with the use of traditional titanium mesh was investigated. Several analytical tools were applied to both characterise the obtained Ni films and to study the efficiency of ECE process. These include scanning electron microscopy (SEM) to explore the morphology of the nickel films and the electron probe micro analysis (EPMA) that was performed simultaneously with SIM to gain composition analysis of the samples. Finally, chloride ion selective electrode (ISE) analytical tool was applied to study the efficiency of ECE process.

Beam Scanning Controller for Proton-Beam Writing

A scanning control system of the ion beam of MeV energies has been developed for the nuclear scanning microprobe and proton-beam writing channel as a part of accelerator-analytical complex based on the Sokol electrostatic accelerator of the Institute of Applied Physics of the National Academy of Sciences of Ukraine. The system was put into operation to replace the obsolete one based on microcontrollers. The scanning control system is based on a National Instruments reconfigurable module with a Field Programmable Gate Array. The module operates in real time and is connected to a personal computer by a high-speed PCI-Express interface with data buffering. The system provides two main modes of operation: exposure of sample areas with a given profile and raster secondary electrons imaging of the sample or a calibration grid. Profile exposure is possible both in raster and functional scanning modes. Automatic calibration of the profile scale and scan raster is also implemented. Using of reconfigurable logic makes it possible to quickly adjust the system to the conditions of a particular experiment and the available equipment. The hardware capabilities of the scanning control system allows in the future to connect up to 4 spectrometric ADC for mapping the elemental composition of samples using Proton Induced X-ray Emission and Proton Backscattering. The first experiments on the irradiation of polymethylmethacrylate have been carried out; images of the obtained microstructures taken with a scanning electron microscope are shown. The aim of this work is to develop a control system for scanning a high-energy focused beam in proton beam writing technique to create small-sized structures for special purposes, as well as to demonstrate the efficiency of the developed system.

Alteration, uranium occurrence state, and enrichment mechanism of the Cretaceous Luohe Formation, southwestern Ordos Basin, western China

To ascertain the characteristics of mineral assemblages associated with uranium mineralization and enrichment mechanism of deep sandstone-type uranium deposits, drill-core logging, petrography and mineralogy, scanning electron microscopy (SEM), electronic probe micro analysis (EPMA), whole-rock analysis, X-ray diffraction (XRD) were used to identify the types, redox state of uranium minerals, and typical uranium-related mineral assemblages in the sandstone of the Cretaceous Luohe Formation, southwestern Ordos Basin. The results showed that the clastic grains in the gray and red uranium-bearing sandstone have undergone relatively strong alteration, while alteration of the clastic grains in the gray and red calcareous sandstone is relatively weak. The alteration minerals mainly include pyrite, anatase, kaolinite, chlorite, calcite, apatite, and feldspar. Uranium contents is highly consistent with S, P2O5, CaO, and FeO concentrations in the vertical direction and has a weak correlation with the total organic carbon. Uranium ores are mainly pitchblende and titanium-bearing uranium minerals. The Luohe Formation experienced transformation from a weak alkaline oxidation environment during the diagenetic stage to a weak acid reduction conditions in the early mineralization stage and then to a weak alkaline reduction environment in the middle–late mineralization stages. Typical alteration minerals associated with uranium ores include two types, which are formed in acid reduction and alkaline reduction redox stages, respectively. The alteration minerals related to acidic fluid process are pyrite, anatase, kaolinite, and apatite; those related to alkaline fluid mechanism consist of calcite and chlorite. Deep-seated uranium mineralization was formed by both acidic and alkaline reducing fluids, being dominated by acidic fluid conditions. In-depth investigation of the alteration and uranium ore minerals are of great scientific value to infer the fluid type of mineralization stage and reveal the enrichment mechanism of uranium deposits.

Mechanism of oil-lubrication of PEEK and its composites with steel counterparts

The rapid adoption of the advantageous PEEK and its composites paired with steel counterparts in many tribological applications has prompted intense research to investigate their tribological properties under lubrication. This study investigated the effect of oil-lubrication and proposed a mechanism of action. Compared to the dry conditions, oil-lubrication with poly-α-olefin (PAO) base oils reduced friction, regardless of the type of polymer materials. However, the wear behavior depended on the polymer type; it increased for neat PEEK and decreased for PEEK composites. Additionally, the viscosity of the lubricant oils influenced the polymer behavior in distinct ways. These differences in tribological performance under oil-lubrication were explained by two important factors, the polymer transfer films on steel counterparts determined by Electron Probe Micro Analysis (EPMA) and the hardness modification of the polymer surfaces investigated by nanoindentation measurements. These factors were also related to each other, especially for PEEK composites.

Formation of a new Wadsley-Roth phase during oxidation of Ti-Nb-Mo alloys

As-cast Ti-Nb-Mo alloys of 4 compositions with commensurate contents of Nb and Ti were obtained by arc-melting and tested for oxidation resistance at 700 °C. For an alloy with a high Mo content, weight loss was observed due to the evaporation of MoO 3 . In alloys enriched in Nb and Ti, a constant increase in mass was found, caused by the formation of an oxide layer. SEM studies of microstructure and electron probe micro analysis of obtained oxides were carried out. It was found by X-ray diffraction analysis that the oxides consist of a mixture of rutile (based on TiO 2 ) and a new phase Wadsley-Roth type of the composition Ti 2 Nb 7 MoO 25 ( a = 1.5689, c = 0.3795 nm).

Fabrication, Structure, and Thermal Properties of Mg-Cu Alloys as High Temperature PCM for Thermal Energy Storage.

This work studied the thermophysical properties of Mg-24%Cu, Mg-31%Cu, and Mg-45%Cu (wt.%) alloys to comprehensively consider the possibility of using them as thermal energy storage (TES) phase change materials (PCMs) used at high temperatures. The microstructure, phase composition, phase change temperatures, and enthalpy of these alloys were investigated by an electron probe micro analyzer (EPMA), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The XRD and EPMA results indicated that the binary eutectic phase composed of α-Mg and Mg2Cu exists in the microstructure of the prepared Mg–Cu series alloys. The microstructure of Mg-24%Cu and Mg-31%Cu is composed of α-Mg matrix and binary eutectic phases, and Mg-45%Cu is composed of primary Mg2Cu and binary eutectic phases. The number of eutectic phases is largest in Mg-31%Cu alloy. The DSC curves indicated that the onset melting temperature of Mg-24%Cu, Mg-31%Cu, and Mg-45%Cu alloys were 485, 486, and 485 °C, and the melting enthalpies were 152, 215, and 91 J/g. Thermal expansion and thermal conductivity were also determined, revealing that the Mg–Cu alloys had a low linear thermal expansion coefficient and high thermal conductivity with respect to increasing temperatures. In conclusion, the thermal properties demonstrated that the Mg–Cu alloys can be considered as a potential PCM for TES.

Petrochemical Features of Manganese Nodules in Madaka (Sheet 142) SE and Part of Kwana - Bala (Sheet 142) NE, Nigeria

Manganese nodule occurs in Madaka (Sheet 142) SE and part of Kwana - Bala (Sheet 142) NE, Nigeria. Four (4) samples of manganese nodules were analyzed petrochemical using X-ray diffractometry (XRD), reflected light microscopy, Electron probe micro analysis (EPMA), Atomic absorption spectrophotometer (AAS). XRD reveals sphalerite, manganates and ilmenite as major minerals in the nodules. Accessory minerals are siderite and rutile. Chemical study of the manganese nodules from Madaka and Kwana - Bala reveals that Mn-, Fe-, Co-, Ni-, and Cu-, minerals (including native elements and sulfides) commonly occur in the samples. Also, the results indicate that increased in Mn relative to the manganite content (10AO- plus 7AO), led to increase in Ni and Cu recovery. However, slightly greater amounts by weight of Ni and Cu were dissolved from the manganites than from Mn. This followed from the much higher Ni and Cu contents of manganites relative to Mn. The exploration for Ni and Cu from nodules on assay criterion was inadequate; the sphalerite Mn02 phase structure would also be a necessary criterion. It was suggested that nodules could be processed upon beneficiation for Ni and Cu contents for a future time relative to the original processing. It was thus proposed that Ni and Cu could be produced from manganese nodules in the study area.

Thin Film Barrier Layers with Increased Performance and Reduced Long-Term Degradation in SOFCs

Gadolinium-doped ceria (CGO) is placed between yttrium-stabilized zirconia (YSZ) electrolyte and strontium-based electrode as a barrier layer to avoid the formation of SrZrO3 insulating phase during solid oxide fuel cell operation. This phase is observed in as-fabricated state-of-the-art cells, which evidences cation inter-diffusion during the sintering process [1]. The impact of this element to the degradation of cells is still under study, in part due to the high complexity of long-term tests necessary for the appropriate understanding of the involved phenomena. Among the efforts for improving barrier layers, the use of vacuum techniques such as sputtering and Large Area Pulsed Laser Deposition (LA-PLD) have been explored, allowing the implementation of dense layers at lower processing temperature compared with traditional deposition techniques (i. e. screen printing). CGO barrier layer thin film deposition and annealing parameters were previously optimized in a leading to an important increase of power density compared to a state-of-the-art button cell at 750ºC using a dense layer of 2 µm. Remarkable results were also obtained when the PLD barrier layer was up-scaled to large area cells of 80 cm2 and tested in short-stack configuration for long-term operation [2].Here we present a thorough investigation of post mortem cells operated in short-stacks under realistic conditions during 15000h, comparing cells produced with state-of-the-art techniques with those produced by LA-PLD. At the light of the results, we provide tools for the improvement of the fabricated thin film layers, by finding the optimal combination between the protective role of the diffusion barrier layer, a good performance and the reduction of the PLD deposition time. Button cells with PLD barrier layer of 800 nm, 400 nm and 200 nm were fabricated and tested in SOFC mode at 750ºC. It is shown that the barrier layer thickness has no impact on the electrochemical performance and the durability which allows the use of thinner layers and a drastic reduction of the deposition time of the CGO barrier layer made by PLD.Summed to the increased performance, the durability of the layers is evaluated, subjecting the cell with the thinnest film to an aging process for 3,500 h. Post-mortem characterization of the barrier layers and interfaces was conducted by Scanning-electronic microscope and Electron Probe Micro Analysis with Wavelength Dispersive X-Ray (EPMA-WDX) to observe any microstructural changes as well as any changes in composition due to cation inter-diffusion.[1] Morales et al., Journal of Power Sources 344 (2017) 141-151.[2] Morales et al. ACS Applied Energy Materials 1 (2018) 1955-1964.

Mobilities of Ti and Fe in disordered TiFe-BCC assessed from new experimental data

Pure titanium has an HCP structure and lacks mechanical properties for many industrial purposes. The BCC phase of Ti is required to make alloys with increased strength compared to pure Ti. Iron is the most potent element for stabilising the BCC phase. However, the addition of Fe to Ti causes segregation issues during solidification, which can be avoided by diffusion-driven solid-state alloying. To predict the diffusion kinetics, the interaction mobility parameters of Ti and Fe in the disordered BCC phase of Ti are necessary. In this work, these parameters are optimised based on new experimental data from Ti-Fe diffusion couples produced by the Field Assisted Sintering Technology (FAST). Diffusion couples were held at 1173K and 1273K for one hour. High-resolution Fe concentration profiles are obtained from Electron Probe Micro Analyser (EPMA). Ternary mobility interaction parameters are assessed based on binary endmembers with a DICTRA sub-module, and results are compared to earlier assessments of mobilities of the disordered BCC TiFe system.

A computational experiment on deducing phase diagrams from spatial thermodynamic data using machine learning techniques

Derivation and discovery of physical dynamics inherent in big data is one of the most major purposes of machine learning (ML) in the field of modern natural science. In the materials science, phase diagrams are often called as “road maps” to perfectly understand the conditions for phase formation and/or transformation in any material system caused by the associated thermodynamics. In this paper, we report a numerical experiment investigating whether the underlying thermodynamics can be derived from the big data constructed of local spatial composition and phase distribution data along with the help of ML. The artificial data analysed have been created assuming a steel composition based on the calculation phase diagram (CALPHAD) thermodynamics combined with the order-statistics-based sampling model. The hypothetical procedures of data acquisition assumed in this numerical experiment are as follows; (i) obtaining local analysis data on the composition and phase distribution in the same observation area using instruments such as electron probe micro analyser (EPMA) and electron backscattering diffraction (EBSD), and (ii) training the classification model based on a ML algorithm with compositional data as input and the phase data as output. The accuracies of the reconstructed phase diagrams have been estimated for three ML algorithms, i.e. support vector machine (SVM), random forest, and multilayer perceptron (MLP). The phase diagrams predicted using SVM and MLP are found to be adequately consistent with those of the CALPHAD method. We have also investigated the regression performance of the continuous data involved in the CALPHAD thermodynamics, such as the phase fractions of body-centred cubic, face-centred cubic, and cementite phases. Compared with the ML algorithms, the CALPHAD method is found to show superior predictive performance since it is based on the sophisticated physical model.

Design of a TiAlON multilayer coating: Oxidation stability and deformation behavior

During the cutting of high-speed steel, thermal and mechanical loads occur. Thin hard coatings like TiAlN deposited by physical vapour deposition (PVD) are applied on the tool surface to prevent wear and oxidation. In the scope of this article, a multilayer coating concept was developed to improve the cutting performance of the tools. It consists of a Ti bond coat, a TiN/AlN nanolayer as an interlayer and an oxynitride TiAlON toplayer. The manuscript presents results of the investigation on the influence of the oxygen content in the reactive gas flow during an industrial direct current/high power pulsed magnetron sputtering hybrid process on the coating properties and on the oxidation stability. The reaction layer forming after the PVD process under ambient atmosphere on the surface of hard coatings has a thickness of a few nanometers. The chemical composition of the coatings and of the reaction layer were measured using electron probe micro analysis (EPMA) and X-ray photoelectron spectroscopy (XPS), respectively. At a high oxygen content of y(O / (O + N) = 85% the oxynitride TiAlON shows the presence of both, crystal and amorphous phases, as proven by transmission electron microscopy. As investigated by nanoindentation, indentation hardness, indentation modulus and resistance against plastic deformation decrease with increasing oxygen content in the coatings. When the oxygen content increases from y = 49% to y = 85%, the oxidation stability decreases. This might be caused by a decreased aluminum ratio of the reaction layer of x(Al / (Al + Ti) = 73% compared to x = 49%.

Effect of Total Pressure and Furnace Tube Material on the Oxidation of T22 in Humidified Air

Oxidation of the Fe-base alloy T22 in humid air at 500 °C was investigated. The samples were exposed for up to 1000 h at 1 bar and 20 bar. The influence of three furnace tube materials, alumina, ET45 and quartz glass, on the oxide scale morphology was investigated. Samples and their cross sections were examined using optical microscopy, scanning electron microscopy, electron probe micro analysis and Raman spectroscopy. Multilayered oxide scales consisting of hematite, magnetite and Fe–Cr spinel were found on all samples. However, the composition and morphology of the oxide scales depend on the furnace tube material and on the system pressure. The system pressure is assumed to change the reaction equilibria and adsorption rates. The tube material changed the initial gas composition by formation of volatile Cr species. This volatilization rate increased at higher system pressures.

Phase Change Material of Copper–Germanium Alloy as Solar Latent Heat Storage at High Temperatures

A copper–germanium alloy (Cu–Ge alloy) was examined as a phase change material, at temperatures exceeding 600°C, for latent heat storage in solar thermal applications. First, the thermo-physical properties of the Cu–Ge alloy were examined using differential scanning calorimetry, thermomechanical analysis, and laser flash analysis. Second, to evaluate the thermal response and reliability of the Cu–Ge alloy, the cyclic properties of thermal charge/discharge were examined under various thermal conditions. The alloys obtained after the tests were examined for their chemical compatibility with the stainless steel container using an electron probe micro analyzer. The elemental distribution of each Cu–Ge alloy was evaluated using cyclic performance tests. Finally, the chemical compatibility of the Cu–Ge alloy was evaluated using a high-temperature test with candidate materials of a phase change material container vessel [stainless steel (SUS310S), Inconel625, silicon carbide (SiC), and alumina (Al2O3)]. The Cu–Ge alloy exhibited significant potential as a latent heat storage material in next-generation solar thermal power plants because it demonstrates various advantages, including a superior storage capacity at a temperature of 644°C, temperature coherence to the phase diagram, a quick thermal response, satisfactory cyclic behavior of charge/discharge modes, a thermodynamically stable metallographic structure, and non-reactivity with container ceramic materials (SiC and Al2O3).

Diffusion in Copper/Cobalt Systems under High Magnetic Fields.

Comprehensive research on a high magnetic field’s effect on diffusion is lacking; hence, this study investigates the effect of the magnetization of such a field on diffusion using a copper/cobalt diffusion couple in the diamagnetic/ferromagnetic states, respectively. The diffusion couple was formed using explosive welding to avoid diffusion during manufacturing. The diffusion couple annealed within a temperature range of 1165–1265 K under a 0–6-T high magnetic field. The angle between the diffusion and magnetic field directions was set as 0° and then 180°. The penetration profiles of cobalt volume diffusion in the copper and grain-boundary diffusion of copper in cobalt were constructed using an electron probe micro analyzer. The high magnetic field increased the volume diffusivity of cobalt in copper, but had no evident effect on the grain-boundary diffusivity of copper in cobalt, irrespective of the magnetic field direction. An Arrhenius plot of the cobalt volume diffusivity in copper demonstrated that the applied high magnetic field enhanced diffusion by changing the frequency factor rather than the activation energy; this can be attributed to the increased diffusion entropy caused by changing the vacancy concentration, which resulted from the introduction of magnetization under a high magnetic field.

Radiocaesium accumulation capacity of epiphytic lichens and adjacent barks collected at the perimeter boundary site of the Fukushima Dai-ichi Nuclear Power Station.

We investigated the radiocaesium content of nine epiphytic foliose lichens species and the adjacent barks of Zelkova serrata (Ulmaceae, "Japanese elm") and Cerasus sp. (Rosaceae, "Cherry tree") at the boundary of the Fukushima Dai-ichi Nuclear Power Station six years after the accident in 2011. Caesium-137 activities per unit area (the 137Cs-inventory) were determined to compare radiocaesium retentions of lichens (65 specimens) and barks (44 specimens) under the same growth conditions. The 137Cs-inventory of lichens collected from Zelkova serrata and Cerasus sp. were respectively 7.9- and 3.8-times greater than the adjacent barks. Furthermore, we examined the radiocaesium distribution within these samples using autoradiography and on the surfaces with an electron probe micro analyzer (EPMA). Autoradiographic results showed strong local spotting and heterogeneous distributions of radioactivity in both the lichen and bark samples, although the intensities were lower in the barks. The electron microscopy analysis demonstrated that particulates with similar sizes and compositions were distributed on the surfaces of the samples. We therefore concluded that the lichens and barks could capture fine particles, including radiocaesium particles. In addition, radioactivity was distributed more towards the inwards of the lichen samples than the peripheries. This suggests that lichen can retain 137Cs that is chemically immobilised in particulates intracellularly, unlike bark.

Analysis of a Radioactive Corrosion Material Collected from Control Rod Drive Mechanism Housing of a PWR Using an EPMA

Radioactive corrosion product materials collected from the control rod drive mechanism (CRDM) housing in a pressurized water reactor (PWR, HANBIT-1 KNPP) were analyzed using an electron probe micro analyzer (EPMA). It is challenging to analyze the composition of radioactive corrosion products using an EPMA due to the rough surface shape and size, and even more so when the products are stacked in the form of small grains. The purpose of this study is to determine whether the corrosive products found inside the CRDM housing are stuck in contact with primary coolant or just oxide. In this study, not only was the surface condition of the samples very rough, but the samples that were quantitatively analyzed using a normal method had extremely low electrical conductivity using a normal method. We therefore tested a new semiquantitative analysis method using X-ray image mapping. In this technical note, we propose a method for collecting and analyzing corrosion products adsorbed in the CRDM. Reference papers on radioactive corrosion products collected from the CRDM could not be found. It is consequently difficult to argue that the method of collecting samples and performing the quantitative analysis suggested in this study is the best, but it can be said that it is an appropriate analysis method. Finally, the usefulness of the semiquantitative analysis is reviewed by verifying the analysis results of radioactive corrosion products collected from the CRDM housing in a PWR.

An evaluation of cleaning methods, preservation and specimen stages on trace elements in modern shallow marine ostracod shells of Sinocytheridea impressa and their implications as proxies

Trace elements of marine shells are important tools for reconstructing past ocean conditions, which are usually obtained through empirical calibrations with ocean parameters. For example, Mg/Ca ratios of ostracod shells have been linked to ocean temperature. However, some uncertainties usually arise from extraneous impacts, such as the selection of cleaning methods, specimen ontogenetic stage and shell preservation. Here, we present an evaluation of trace elements (Ca, Mg, Sr, Na, Al and Fe) in a shallow marine ostracod, Sinocytheridea impressa, and their potential utility as paleoceanographic proxies. We investigated single-shell variability of trace-element-to‑calcium ratios through Inductively Couple Plasma Mass Spectrometry (ICP-MS). In addition, the internal distribution of trace-elements was studied by Electron Probe Micro Analysis (EPMA) and Flow-Through Time-Resolved Analysis (FT-TRA). We conducted these analyses on ostracod specimens of different life stages and preservation conditions, subject to different cleaning methods, to resolve the suitability of this species as a new paleoenvironmental archive. Based on cleaning tests, we observe that clays stuck to the shells are the major contaminants in our specimens. We report an optimal cleaning procedure using sodium hypochlorite, which reduced the adherence of clays to the organism without significantly dissolving adult and juvenile calcite. We additionally find that the internal Mg distribution of S. impressa specimens is different for adults and the oldest stage of juveniles, namely A-1, with only the former having an enriched inner Mg layer. Therefore, precautions should be taken when combining life stages for trace-element analysis. While Sr and Mn are found to be mostly homogenous throughout all shells, the distribution of Na was found to be heterogeneous, which suggests that the incorporation of Na is controlled by a different mechanism than Mg, Sr and Mn. Finally, we report that transparent and opaque shells show similar Mg/Ca, Sr/Ca and Na/Ca ratios, unlike Mn/Ca and Fe/Ca, which suggests that opaque shells result from Mn- and Fe-enriched porewaters and Mn-enriched waters from the Pearl River. Our combined analysis suggests that Mg, Sr and Mn of adult S. impressa are incorporated into the carbonate matrix during calcification, and may therefore be suitable proxies of important environmental variables such as temperature and aqueous elemental concentrations.

Interfacial characteristics and residual welding stress distribution of K4750 and Hastelloy X dissimilar superalloys joints

Gas tungsten arc welding (GTAW) method was employed to join a newly developed cast superalloy K4750 with Hastelloy X by using K4750 and Hastelloy X filler metals (FMs), respectively. Thereby we obtained two kinds of interfaces namely K4750 base metal (BM) and Hastelloy X FM, and K4750 FM and Hastelloy X BM. The elemental distribution, interfacial characteristics, and the residual welding stress of the dissimilar joints were investigated by electron probe micro analyzer (EPMA), electron backscattered diffraction (EBSD), and section technique, respectively. The results showed that the elemental distribution across both interfaces were varied significantly. And the composition segregation regions were identified in both interfaces but the segregation extent was different. Epitaxial growth was clearly observed in both interfaces. The distribution of the residual welding stress across the joint exhibited that the highest tension stress area in both as-welded joints was located at the joint heat affected zone (HAZ). The residual welding stress in the joint with Hastelloy X FM was significantly relieved through post weld heat treatment (PWHT).

Beam optics in nuclear microprobe: A review

The beam optics in a nuclear microprobe is considered on the basis of quality criteria for focusing systems. In this consideration, empirical criteria with dominant chromatic or intrinsic spherical aberrations are used. In a more general criterion, where all aberrations can be taken into account, the maximum acceptance for a fixed beam spot size on the target is used. Another criterion, that is closest to an experiment, is based on the condition of the minimum spot size at a fixed beam current and takes into account the nonuniform distribution of ions in the phase volume. This review summarizes the studies of various types of quadrupole focusing systems and implies the need for further development of the nuclear microprobe by using aberration correctors and a compact system. The analysis of the influence of various aberrations on the resolution of a nuclear microprobe is conducted with special attention paid to the positioning aberrations in separated quadrupole probe-forming systems. It is demonstrated why integrated multiplets of quadrupole lenses are preferred in such systems. Methods to process experimental results for an adequate determination of the spot size on the target are considered.

Characterization of copper slag for beneficiation of iron and copper

Before disposal of any metallurgical waste to the environment, it is the responsibility of mining institutes to adhere to the permissible metal content limits. Base metals, especially iron and copper, have adverse effects of reducing the soil pH and excessive concentrations of these in the disposed waste may result in soil pollution and toxicity, with adverse effects on plant growth and animal health. Copper slag is a metallurgical waste that is disposed by way of stockpiling at designated dump sites within a mining site. The observed depletion of high-grade iron ores in Botswana and the environmental hazards associated with disposal of untreated metallurgical waste, presents an opportunity for research on secondary sources of iron and copper. Our characterization results show that this BCL copper slag is a good secondary source of base metals, especially iron and copper. These results reveal that the elemental proportion of iron was around 35.4%. Literature states that an iron grade that is considered viable for economic beneficiation should be at least 25% and this slag has an iron content above this limit, hence poses a serious environmental threat upon disposal. This article presents an investigation into the mineralogy of the copper slag at a plant situated in Selebi Phikwe, a town in the northern part of Botswana. Quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) quantified that no cobalt – sulphide was detected and strongly indicated that the cobalt within the sample occurs in solid solution in either the fayalite phase or glass phase. Spot analysis from electron probe micro – analyzer (EPMS) images indicated an unusually high content of copper compared to any other metal. We elucidate that, this was due to the inefficient processing techniques employed during operational years of the mine. The relative compositions of Co, Fe, Ni and Cu were 0.14%, 35.4%, 0.28% and 0.29% respectively. This analysis justifies our interest in considering this copper slag as a secondary source of iron for beneficiation purposes.