bluuebunny/crossref_metadata_2025 huggingface dataset:
3D-Computer Modelling of Contact Interaction between Spherical Indenter and Elastic-Plastic Body
Authors: Shimanovsky Alexandr O. , Abdulkader Mohammed H.
Published: December 2015

Computer simulation of contact interaction between a spherical indenter and soil surface was performed by the means of ANSYS software. It was assumed that the soil was deformed elastically-plastically in accordance with the model Drucker-Prager. It was carried out the analysis of the influence of the model base physical parameters on the stress-strain state of the contacting bodies. The comparison of the calculated by linear elastic model and Drucker-Prager model stresses values for the soil showed that for the case of the elastic-plastic model are three times less than for the case of the elastic model.
Embedded Systems via Using Microcontroller
Authors: Kelemen Michal , Prada Erik , Kelemenova Tatiana , Miková Lubica , Virgala Ivan , Lipták Tomáš
Published: December 2015

Paper deals with microcontrollers which are embedded inside the mechatronic products. Main purpose is to obtain intelligent behavior of products and adding of new functions to products. Paper shows steps to data capturing into microcontroller for data processing and using as feedback control of processes around the products.
Upgrade of the Drives Control for Omnidirectional Mobile Robot Odin
Authors: Krys Václav , Gala Matěj , Kot Tomáš , Mostýn Vladimír
Published: December 2015

This article describes the process of the development of trajectory accuracy testing and the course of modifications of an omnidirectional mobile robot Odin. It also chronologically presents connections between individual phases of developing its construction, electrical wiring, and control software. The first implemented prototype has presented a simple construction and drive control. This laid basis for designing the omnidirectional mobile robot Odin with an installed modular manipulator Schunk. Modifications in the drive control led to better results in the tests. In conclusion, the article describes and compares the acquired test results for various modes of chassis control.
Mobile Chassis on a Modular Principle
Authors: Konečný Zdeněk , Široký Petr , Krys Václav , Kot Tomáš
Published: December 2015

The article describes design of a drive module of a modular mobile chassis. This chassis was developed at the Department of Robotics, Faculty of Mechanical Engineering, VŠB-Technical University of Ostrava, as a part of the student grant competition “Research and development of modular robotic systems.” The article describes variants and the final mechanical construction of the drive module and also the structural analysis of this module according to the possible positioning in the whole modular system. The obtained results and possible ways of additional future development and modifications of the module are summarized in the conclusion.
Use of Linguistic Fuzzy-Logic Control for Mechatronic System Modelling and Control
Authors: Farana Radim , Walek Bogdan , Janošek Michal , Žáček Jaroslav
Published: December 2015

The article presents use of a linguistic fuzzy-logic control (LFLC) system for mechatronic system modelling and control. The presented applications were verified on real laboratory tasks in the Laboratory of Intelligent Systems at the University of Ostrava. The LFLC system was developed at the University of Ostrava, Institute for Research and Applications of Fuzzy Modeling. This technology enables users to describe the system behaviour and/or the control strategy as a set of fuzzy rules. Input and output variables scales are defined by contexts and their change allows using the same system description for systems with similar behaviour very easily.
Kinematic and Dynamic Analysis of Planar Mechanisms by Means of the Cosmos Motion Program
Authors: Vavro Ján , Vavro Ján , Kováčiková Petra , Bezdedová Radka
Published: December 2015

The paper presents a kinematic and dynamic analysis of a planar mechanism by means of the Cosmos Motion 2.85 program. Graphic dependence of kinematic and dynamic magnitudes of some points is given in dependence on the angle of rotation of the driving item and on the time.
Basics of Model Creation in Simulation Program Extend
Authors: Pekarčíková Miriam , Trebuňa Peter , Kliment Marek , Popovič Radko , Markovič Jaromír
Published: December 2015

Article deals with the possibilities of modelling and simulating in program Extend. It is a simple tool that allows you to model and carry out simulation of specified process to create a good precondition for decision-making. The development of simulation tools and their introduction into industrial practice is the now common practice, particularly in large enterprises. In these turbulent times it is only a matter of time before these virtual tools are commonly used in small businesses.
Program Tools for Residual Stress Evaluation by Ring-Core Method
Authors: Menda František , Šarga Patrik , Lipták Tomáš , Trebuňa František
Published: December 2015

Residual stress determination requirements of production and research users grow rapidly. Commercially available programs enable relatively quick residual stress evaluation with certain level of accuracy and with limited user access to used compliance matrices and calculations. However precise analyses require sensitive approach to compliance matrices determined for individual case e.g. for specific specimen dimensions. Therefore program tools for complex residual stress evaluation by Ring-Core method were developed using finite element analysis and Visual Basic scripts.
An Analysis of the Constructional Insufficiencies of Locking System Components Using the Salinger-Grydilov Method
Authors: Ivanka Ján , Navrátil Petr
Published: December 2015

This paper is focused on the detection of the level of destruction of a cylinder lock, opened using the Salinger-Grydilov (SG) method, and on measuring the resonance curve while striking a bump key as well as its influence on overcoming locks using SG method. It also presents an analysis and verification of the laboratory measurements of the level of destruction of a lock which was overcome using the SG method and its differentiation from a lock opened using the appropriate key. Further, attention is paid to measurements of the frequency of individual blows when using the SG method and its influence on overcoming cylinder locks.
Experimental and Numerical Analysis of the Damage Causes of Rail Traction Vehicles
Authors: Sivák Peter , Ostertag Oskar
Published: December 2015

This paper presents the results of the investigation of the causes of the occurrence and the influence of the dynamic effects in the couplers of the remotely controlled electric shunting locomotives and a set of fully loaded rail cars. These are typical rail-road sets, working at the logistic area of the central ore trans-shipment of large steelworks with heavy rail traffic. The stated effects lead to excessive deterioration of the supporting structure of the locomotives, axle gripping, drive mechanisms and braking systems. To achieve the desired goal, the methods and means of numerical and experimental modelling have been used. Based on the performed numerical and experimental analyses were then specified the recommended design and operational measures to prevent the failures mentioned above.
Extracting Load Research of Taper Interference Fit Made of Glass and Ceramics Parts Using a Servo Press
Authors: Lekomtsev Pavel , Božek Pavol , Romanov Alexander , Abramov Andrey , Abramov Ivan , Nikitin Yuri
Published: December 2015

Test results of axial shift of “technical ceramics - glass” parts in taper interference fit joint under axial loading are presented. The load-carrying capacity was tested under normal conditions; a servo press was used to load the test samples. The tested samples were assembled by thermal method.
Stress Analysis Performed by Photoelasticity and Digital Image Correlation
Authors: Pástor Miroslav , Hagara Martin , Kostka Ján
Published: December 2015

This paper deals with the use of classical experimental technique of photoelasticity as well as modern one – digital image correlation by stress analysis. Both mentioned methods were used to compare the corresponding stress fields obtained on a sample with stress concentrators loaded by bending. The paper contains the basic principle of photoelasticity, methodology of static analysis with polariscope and briefly describes the measurement with low-speed digital image correlation system. Taking into account that the used correlation system does not allow to evaluated stress fields, calculation and visualization of stress fields were realized in program Q-STRESS v.1.0 developed at the authors department.
Static Compression Tests of Concentrated Crystallized Carbon Dioxide
Authors: Górecki Jan , Malujda Ireneusz , Talaśka Krzysztof , Kukla Mateusz , Tarkowski Paweł
Published: December 2015

This paper presents the results of static compression tests of concentrated crystallized carbon dioxide. The test results obtained under this research describe the relationship between the compressive stress and strain allowing to estimate the proportionality ratio, limit stress and critical stress values. Special test methods were used due to low temperature of crystallized carbon dioxide (minus 78.5°C) and its sublimation under standard testing conditions. The results of the mechanical properties of agglomerated CO2 were compared with the mechanical properties of other known materials. This allowed us to derive assumptions, which can become the starting point of the process to build a mathematical model describing the dry ice compaction and granulation processes.
Application of the Simple Linear Regression Model in the Experiment
Authors: Ostertagová Eva , Ostertag Oskar , Sivák Peter
Published: December 2015

The paper presents the results of experiments and measurements of the stress of a pipeline located on a pipe bridge. The experiment was carried out by means of resistance strain gages for two modes, which were the stress changes upon pressure changes in the pipes and at the driving in of sheet pilings in the immediate vicinity of the pipeline. On the basis of measurements, the impact of these changes on the operational safety of the pipeline in the renovation process of old above ground and the realization of new underground pipeline solutions. Polynomial regression models were applied for the prediction and a statistical analysis of residuals was applied for the quality assessment of selected models.
Virtual Commissioning as a Part of Mechatronical System
Authors: Markovič Jaromír , Popovič Radko , Trebuňa Peter , Pekarčíková Miriam , Kliment Marek
Published: December 2015

The paper deals with the mechatronical system, that are necessary during the implementation of the production processes in the companies. Mechatronics systems is a relatively new approach to product design and development, merging the principles of electrical, mechanical, computer and industrial engineering. Examples include robots, photocopiers, PC disk drives, sensors, automotive equipment sucha s anti-lock braking systems and many others. This paper focuses on robots and their possibilities of commissioning to the real production processes.
Methodology for Tuning a Semi-Active Dynamic Vibration Absorber on a Passive Suspended Seat
Authors: Orečný Martin , Segľa Štefan , Huňady Róbert
Published: December 2015

The article deals about an application of two types of dynamic absorber applied on an operator’s seat. In the first case, the seat is suspended by passive elements. The passive dynamic absorber (DA) is composed from a viscous damper and a linear spring. In the second case, the semi-active damper is composed from a linear spring and a MR damper. The affectivity of the vibration reduction of the seat is observed. The parameters of the seat suspension with the passive DA were identified from multi-criterion optimization using genetic algorithms. The parameters of the semi-active DA were evaluated using information obtained from the passive DA.
Effect of Cu(II) on Bio-Scorodite Crystallization Using Acidianus brierleyi
Authors: Okibe Naoko , Morishita Shiori , Tanaka Masahito , Hirajima Tsuyoshi , Sasaki Keiko
Published: December 2015

The effect of different concentrations of Cu (II) on microbial scorodite (FeAsO4⋅2H2O) formation was investigated by using thermo-acidophilic iron-oxidizing archaeon, Acidianus brierleyi. In the presence of 8-16 mM Cu (II) microbial Fe (II) oxidation and cell growth was only marginal. Its As (III) oxidation ability was especially severely inhibited by the presence of Cu (II), consequently disabling scorodite formation. However, when scorodite seed crystals were fed, Ac. brierleyi readily oxidized Fe (II) and As (III) even in the presence of 8.0 mM Cu (II), forming crystalline scorodite within 24 days in shake flasks. All Cu (II) remained in the solution phase during scorodite crystallization, with or without the presence of seed crystals. Increasing the seed crystal concentration (from 0.015 to 0.15%) slightly improved the As immobilization (from 96 to 98%). This study demonstrated that scorodite can be crystallized from the model As (III)-bearing wastewater containing Cu (II).
Influence of Different Growth Conditions on the Composition of Extracellular Polymeric Substances of Acidithiobacillus ferrooxidans and Acidithiobacillus ferrivorans Species
Authors: Teubner Natascha Caroline , Bellenberg Sören , Vera Mario , Sand Wolfgang
Published: December 2015

Acidithiobacillus ferrooxidansandAcidithiobacillus ferrivoransare used in bioleaching to recover metals such as copper or gold from low-grade ores.At. ferrooxidansis one of the best studied bioleaching microorganisms.At. ferrivoransis known for its ability to leach ores at low temperature. Both microorganisms are involved in acid mine drainage (AMD) formation. The cells are embedded in extracellular polymeric substances (EPS), which play an important role in the attachment to metal-sulfide-surfaces and in catalysis of their dissolution. EPS amounts and compositions differ, depending on the energy source, as it was shown forAt. ferrooxidansR1. Recently,At. ferrooxidansstrains were reclassified into four different subgroups, which are considered to correspond to four different species. As well, a biofilm study, using three of these closely related iron-oxidizingAcidithiobacillusspecies, demonstrated differences regarding attachment to pyrite among them. Consequently, this study focuses on the investigation ofAt. ferrooxidansandAt. ferrivoransspecies and their EPS composition with regard to varying cultivation conditions. Also different energy sources like, elemental sulfur or pyrite were tested. EPS were extracted by the use of a cation exchange resin (DOWEX). Obtained EPS were analyzed for their total amount of proteins, extracellular DNA (eDNA) and carbohydrates.
Biofilm Formation and Extracellular Polymeric Substances (EPS) Analysis by New Isolates of Leptospirillum, Acidithiobacillus and Sulfobacillus from Armenia
Authors: Vardanyan Arevik K. , Vardanyan Narine S. , Markosyan Levon , Sand Wolfgang , Vera Mario , Zhang Rui Yong
Published: December 2015

Biofilm formation by new isolates, Leptospirillum sp. strain ZC, Acidithiobacillus sp. strain 61 and Sulfobacillus sp. strain 6 isolated from different biotopes of sulfide ores in Armenia on pyrite was studied by atomic force microscopy (AFM) combined with epifluorescence microscopy (EFM). It was revealed that all the tested species formed monolayer biofilms The results showed that in contrast to Acidithiobacillus sp. strain 61 and Sulfobacillus sp. strain 6, cells of Leptospirillum sp. strain ZC were often observed by clusters and aggregates.The composition of capsular and colloidal EPS formed by isolated Leptospirillum sp. strain ZC, Acidithiobacillus sp. strain 61 and Sulfobacillus sp. strain 6 was studied. It was revealed that the EPS of all three species grown on iron (II) mainly consisted of carbohydrates, proteins as well as uronic acids.
Influence of Oxidation-Reduction Potential on Bio-Oxidation of Olimpiada Flotation Concentrate with High Content of Pyrrhotite
Authors: Belyi Aleksandr , Drozdov Sergei , Teleutov Anatoliy , Solopova Natalia
Published: December 2015

The main sulphidic minerals, contained in the Olimpiada flotation concentrate, are pyrrhotite, arsenopyrite, pyrite and antimonite. Biooxidation of these minerals occurs in the following sequence: Pyrrhotite → Arsenopyrite → Pyrite → Antimonite. Oxidation of pyrrhotite requires acid consumption, oxidation of pyrite is followed by formation of sulphuric acid. The oxidation rate of pyrrhotite is higher and due to this, acid balance of the whole biooxidation process is shifted to the consuming side, and it is required to add acid to the process. The research work has demonstrated, that by regulating oxidation-reduction potential it is possible to reduce pyrrhotite oxidation rate and intensify pyrite oxidation rate; this allows to reduce consumption of sulphuric acid, reduce heating of the slurry inside the reactors and as a result maintain the stable process.
In Situ Characterization of Relevance of Surface Microstructure and Electrochemical Properties of Chalcopyrite to Adsorption of Acidianus manzaensis
Authors: Xia Jin Lan , Zhu Hong Rui , Wang Lei , Liu Hong Chang , Nie Zhen Yuan , Zhao Yi Dong , Ma Chen Yan , Hong Cai Hao , Zhen Xiang Jun
Published: December 2015

The in situ relevance of micro- structure and electrochemical properties of chalcopyrite to adsorption of thermoacidophilic bioleaching Archaea Acidianus manzaensis was studied. In this study, the electrochemical behavior of chalcopyrite was first investigated by cyclic voltammetry (CV) to get suitable initial reduction and oxidation potentials, at which electrochemical corrosions of chalcopyrite for several time were performed, respectively, to get specific surface micro-structures. The specific adsorption of A. manzaensis on the electrochemically corroded chalcopyrite surface was then comparatively studied. The changes of microstructure and chemical composition/speciation on the surface of chalcopyrite before and after electrochemical treatment and bio-adsorption was characterized by scanning electron microscopy/electron dispersive spectroscopy (SEM/EDS), and synchrotron radiation-based X-ray diffraction (SR-XRD) and Fe, Cu K-edge X-ray absorption near edge structure (XANES) spectroscopy. The results showed that the suitable initial oxidation and reduction of chalcopyrite electrode were at 0.67 V for 1h and -0.54 V for 10 min, respectively. After treated at 0.67V the surface of chalcopyrite became Cu-deficient with a composition of CuFe1.02S2.15, and bornite (Cu5FeS4) was detected. While after treated at -0.54V, the surface became Fe/S-deficient, with a composition of CuFe0.33S0.81, and a mass of chalcocite and some covellite were detected. Comparing to the original chalcopyrite, the adsorption capacity of A. manzaensis was increased on the surface of oxidation-treatment at 0.67 V, and decreased on the surface of reduction-treatment at -0.54 V. It clearly demonstrates the bornite-containing copper deficient chalcopyrite surface was more preferably adsorbed, whereas the chalcocite-containing Fe/S deficient chalcopyrite surface was less adsorbed by A. manzaensis, indicating the dependence of the specific adsorption of A. manzaensis upon the secondary minerals as well as Fe/S availability in the microstructure of chalcopyrite.
Iron Oxidation and Jarosite Precipitation in a Continuous Two-Stage 70°C Archaeal Bioreactor
Authors: Kaksonen Anna H. , Morris Christina , Wylie Jason , Li Jian , Usher Kayley , Hilario Felipe , du Plessis Chris
Published: December 2015

This study is the first demonstration of a continuous culture bio-catalysed iron oxidation and jarosite precipitation reactor using thermophilic archea, for use in hydrometallurgical process flow sheets. A two-stage continuous stirred tank reactor (CSTR) system comprised of two CSTRs, each with its own settler, was operated for biological iron oxidation and precipitation at 70°C. The two-stage design was to allow the growth of microorganisms that prefer various redox regimes. The bioreactors were inoculated with a mixed culture of extreme thermophilic iron oxidisers from genera Acidianus, Metallosphaera and Sulfolobus. The influent (pH 1.5) contained (g L-1) 15 Fe2+, 1.5 Cu, 1.5 Ni (all as sulfates), nutrients and trace elements. At a hydraulic retention time (HRT) of 6-7 h in each CSTR, the overall iron oxidation rate was 1.0±0.1 g L-1 h-1 and percent 97±2%. The pH values were 1.38±0.16 and 1.57±0.05, and redox potentials (Ag/AgCl reference) were474±47 mV and 575±1 mV, in CSTR1 and CSTR2, respectively. The percentages of influent Fe, Cu and Ni removed as precipitates from settlers were 52%, 0.46% and 0.03%, respectively. The precipitates were comprised of jarosite (100%), potassium jarosite being the dominant form (38-51%), followed by hydronium (30-35%), ammonium (13-18%) and sodium jarosites (6-9%). The precipitates had a sludge volume index of 5.8-19 mL g-1, indicating good settling properties facilitating easy removal through settling. The simultaneous and instantaneous addition of contaminants (g L-1: 2.0 Al, 0.05 As, 0.05 F, 0.2 Co, 5.0 Mg and 0.4 Mn), potentially contained in hydrometallurgical processing streams, into the influent decreased the iron oxidation (50% overall oxidation with HRT of 26-29 h in each CSTR) and jarosite content in precipitates (85-87%). In conclusion, the two-stage high-temperature CSTR system allowed iron oxidation and precipitation of the oxidised iron in the form of well settling jarosite with only minor loss of Cu and Ni via co-precipitation. However, the bioreactor performance was hampered by the introduction of other transition metals, fluoride and arsenic.
Optode-Based Oxygen Measurements in Bioleaching Reactors
Authors: Giebner Fabian , Eisen Sebastian , Schlömann Michael , Schopf Simone
Published: December 2015

Tank bioleaching promises high yields due to controllability of the leaching process. For that various parameters like pH, EH and pO2 have to be measured regularly. However, especially the measurement of oxygen is difficult to realise, since oxygen probes are very expensive and posses only a low durability. With optode measurements we propose an easy and less expensive, but still very accurate alternative. Since we were able to fix the optode sensor spot at the lower end of a glass tube, this system is applicable with various reactor designs and hence allows non-invasive in-situ oxygen measurements between each second and every hour.In order to show the principal applicability of this system inside a bioreactor, Escherichia coli was cultivated at a defined oxygen level. Both optode and oxygen probe showed similar concentration values. In the following, a cultivation of Acidithiobacillus ferrooxidans was performed in a 2 L bioreactor with different oxygen levels set by controlling the air flow. Again, both systems showed similar concentrations. This demonstrates the optode to be a reliable tool for oxygen measurements during the cultivation of iron-oxidisers in bioreactors. Furthermore, we performed leaching tests with fine grained residue from copper smelting in order to show the durability of the optode in terms of mechanical wearing and hence a suitable alternative to oxygen probes.
Development of a Strategy for Selective Metal Recovery from Pregnant Leach Solutions of Kupferschiefer Bioleaching
Authors: Hedrich Sabrina , Schippers Axel , Johnson D. Barrie
Published: December 2015

Pregnant leach solutions (PLS) resulting from bioleaching of copper concentrate from Kupferschiefer are characterized by low pH values and high concentrations of mainly ferric iron, copper, zinc and sulfate, as well as significant amounts of nickel and cobalt. In order to recover the valuable metals for further processing, a novel technique that promotes selective metal recovery and sulfate removal from acidic liquors, described in this study, is proposed.
Interactions between Chalcopyrite and Marmatite during Bioleaching Process
Authors: Zhao Hong Bo , Wang Jun , Zhang Yansheng , Qiu Guan Zhou
Published: December 2015

Chalcopyrite (CuFeS2) and marmatite [(Zn, Fe) S] are associated together most of the time in the raw ores and flotation concentrates. In this work, the interactions between chalcopyrite and marmatite during bioleaching by moderately thermophilic bacteria were investigated by electrochemical measurements and bioleaching experiments. In the initial stage of bioleaching of mixture of chalcopyrite and marmatite, the dissolution of marmatite was preferential, and was significantly accelerated with the addition of chalcopyrite because of the galvanic effect and catalytic effect of Cu2+ ions, while the dissolution of chalcopyrite was inhibited mainly due to the galvanic effect before the accomplishment of marmatite dissolution. Chalcopyrite dissolves fast when the dissolution of marmatite is finished, and small amount of marmatite cannot inhibit the final copper extraction of chalcopyrite if leaching time was long enough. Therefore, stepwise or selective bioleaching was feasible in processing mixture of chalcopyrite and marmatite to avoid complex flotation process in separating chalcopyrite and marmatite.
An In Situ Characterization for the Bioleaching Process of Natural Pyrite Using Electrochemical Noise Technique
Authors: Chen Guo Bao , Yang Hong Ying , Li Hai Jun
Published: December 2015

An in situ characterization has been carried out for several active systems (sulfuric acid, ferric iron, 9k medium and bioleaching solutions) to investigate the bioleaching process of natural pyrite using electrochemical noise (ECN) technique. Spectral noise impedance spectra obtained from power spectral density (PSD) plots for the different systems were compared. It has been observed that the bioleaching system obtained the lowest noise resistance Rsn 0.101MΩ. The reaction mechanism was proposed based on experimental data analysis. The bioleaching process of natural pyrite has been identified as the main function of bio-battery reactions, which distinguishes from the chemical oxidation reaction for the ferric ion and 9k solutions.
Evolution of Leaching Products on the Surface of Chalcopyrite by Mesophiles and Thermophiles Based on SR-XRD and XANES Spectroscopy
Authors: Liu Hong Chang , Xia Jin Lan , Nie Zhen Yuan , Zhu Hong Rui , Zhao Yi Dong , Ma Chen Yan , Zheng Lei
Published: December 2015

The bioleaching experiments of chalcopyrite were conducted with single and mixed mesophiles (30 °C) and moderate thermophiles (45 °C) and extreme thermophile (65 °C), respectively, and analyzed by synchrotron radiation (SR) based X-ray diffraction (XRD) and X-ray absorption near edge structure (XANES) spectroscopy. The results showed that the copper extraction of chalcopyrite could be significantly promoted by bioleaching microorganisms, and the promotion effects for both the mixed cultures grown at different temperature and the different cells grown at the same temperature were significantly different. The surface of chalcopyrite after bioleached by the mixed or sole cultures are serious corroded and became complicated. More S0 was found to form in the sole cultures of specific iron-oxidizing microorganism L. ferrooxidans and L. ferriphilum and sulfur-oxidizing microorganisms A. thiooxidans and A. caldus cultures. Jarosite and secondary minerals (chalcocite and covellite) were detected for the mixed cultures and sole cultures of iron/sulfur-oxidizing microorganisms. The evolution of chalcocite and covellite were just relevant to the potential of leaching solution, no matter which cultures were used, where chalcocite could be formed at Eh value less than 500 mV and then converted to covellite at Eh value ~550 mV.
Solution pH and Jarosite Management during Ferrous Iron Biooxidation in a Novel Packed-Column Bioreactor
Authors: Wanjiya Mwema , Chowdhury Faysol , Ojumu Tunde Victor
Published: December 2015

Jarosite formation is undesirable in bioleaching processes as it depletes the needed ferric reagent for the oxidation of most sulfide minerals. Although it creates kinetic barriers thereby retarding the leach rates of most minerals, jarosite serves as support for the attachment of bioleaching microbes, facilitating biooxidation rate. Microbial ferrous-oxidation by mesophilic microbe was studied in a recently reported novel packed-column bioreactor with a view to investigate the potential of using solution pH to manage jarosite accumulation in the bioreactor in addition to establishing a base case data for the bioreactor. Experiments were conducted in the bioreactor packed with glass balls (15mm diameter) at constant temperature of 38.6 °C, residence time of 18 hours, airflow rate of 20 mLs-1and pH values of 1.3, 1.5 and 1.7. The results showed that the amount of jarosite accumulation is proportional to the solution pH, and to the duration of operation of the bioreactor. Jarosite precipitation concentrations of 4.95, 5.89 and 7.08 gL-1were obtained after 10 days of continuous operation at solution pH values of 1.3, 1.5 and 1.7 respectively, while after 15 days the precipitations concentrations increased to 5.50, 7.90, 9.98 gL-1respectively. The results also showed that 33% and 52% precipitate reduction could be achieved by gradual decrease in the bioreactor solution pH to 1.5 and 1.3 after being continuously operated for 10 days at pH 1.7 respectively after an addition of 5 days. A maximum ferrous oxidation rate (), 6.85 mmol.L-1.h-1and the affinity kinetic constants (,), of 0.001 and 0.006 for Hansford and Monod models respectively. Although a directly relationship exist between jarosite formation and pH, the results of this study may be relevant in bioleach heaps or at least in column bioreactors to manage/control jarosite accumulation thereby improving the leach kinetics of mineral sulfides.
Systems Biology of Acidophile Biofilms for Efficient Metal Extraction
Authors: Christel Stephan , Dopson Mark , Vera Mario , Sand Wolfgang , Herold Malte , Wilmes Paul , Buetti-Dinh Antoine , Pivkin Igor , Trötschel Christian , Poetsch Ansgar , Nygren Jan , Kubista Mikael
Published: December 2015

This European Union ERASysApp funded study will investigate one of the major drawbacks of bioleaching of the copper containing mineral chalcopyrite, namely the long lag phase between construction and inoculation of bioleaching heaps and the release of dissolved metals. In practice, this lag phase can be up to three years and the long time period adds to the operating expenses of bioheaps for chalcopyrite dissolution. One of the major time determining factors in bioleaching heaps is suggested to be the speed of mineral colonization by the acidophilic microorganisms present. By applying confocal microscopy, metatranscriptomics, metaproteomics, bioinformatics, and computer modeling the authors aim to investigate the processes leading up to, and influencing the attachment of three moderately thermophilic sulfur-and/or iron-oxidizing model species: Acidithiobacilluscaldus, Leptospirillumferriphilum, and Sulfobacillusthermosulfidooxidans. Stirred tank reactors containing chalcopyrite concentrate will be inoculated with these species in various orders and proportions and the effects on the lag phase and rates of metal release will be compared. Meanwhile, confocal microscopy studies of cell attachment to chalcopyrite mineral particles, as well as metatranscriptomics and metaproteomics of the formed biofilms will further increase understanding of the attachment process and help develop a model thereof. By fulfilling our goal to decrease the length of the lag phase of chalcopyrite bioleaching heaps we hope to increase their economic feasibility and therefore, industrial interest in bioleaching as a sustainable technology.
A Study of Permeability and Diffusion at the Agglomerate-Scale in Heap (Bio)Leaching Systems
Authors: Govender Elaine , Kotsiopoulos Athanasios , Harrison Sue T.L.
Published: December 2015

Multiple mini-column reactors, loaded with identically constructed ore samples representing grab samples of a larger heap, were used to study the behaviour of solution tracers to elucidate solution diffusion, dispersion and transport. The tracers were either introduced to the ore bed as a pulse, included during agglomeration of the ore or introduced to the system by submerging the ore bed. These methods of tracer introduction allowed for the characterisation of flow interchange in unsteady state systems. The resulting concentration-time distribution curves were analysed to allow characterisation of flow dispersion and diffusion, which facilitates exchange between the fast flowing and largely stagnant liquid phases. Preliminary results support the presence of distinct stagnant and flowing regions within the agglomerated ore bed. Agglomeration with the tracer promotes increased retention on the ore; potentially enhancing microbial transport via increased solution exchange after the initial period of attachment.
Microstructure Evolution of Ore Particles during Bioleaching Based on X-Ray Micro-Computed Tomography Images
Authors: Yang Bao Hua , Wu Ai Xiang , Miao Xiu Xiu , Liu Hong Bing
Published: December 2015

Microstructure of ore particle has significant influence on the efficiency of bio-heap leaching, because it affects such processes as microscale fluid flow, mass diffusivity, bacteria growth, chemical reaction, etc. The micropores and microcracks in ore particles evolve continuously during bioleaching. To obtain crucial quantitative information on structural evolutions, non-destructive techniques become necessary. In this study, a cylindrical ore sample of 3mm diameter was scanned with X-ray micro-CT before and after bioleaching test. The ore sample is a kind of mixed ore that composed of oxide copper and sulfide copper. The CT scanner used is μCT225kvFCB. By using an in-house developed image analysis program based on MATLAB, 3D information about the total porosity, the pore size distribution, the pore connectivity, and the pore fractal dimension of the ore sample before and after bioleaching were calculated and analyzed. The results obtained in this study are promising for a better understanding of microstructure evolution mechanisms on ore particles during bioleaching. Results also show that 3-D image analysis is a powerful technique to characterize the morphological, structural and topological differences due to bioleaching.
Blue-Copper Proteins: Expression of Coding Genes from Sulfobacillus Spp. and Iron Oxidation in Column Bioleaching Tests
Authors: Acosta Mauricio , Galleguillos Pedro A. , Marín Sabrina , Chibwana Clement , Strauss Hannes , Demergasso Cecilia
Published: December 2015

In bioleaching, the chemiolithotrophic community plays an important role as oxidizers of sulfur compounds and ferrous iron. Ferrous iron oxiding microorganisms are key players in the process, as ferric iron is absolutely required to solubilize metal sulfide ores. Members of the Sulfobacillus genus (able to oxidize ferrous iron) were predominant (22 - 95%) in a chalcopyrite bioleaching columns test. In order to obtain new insight about the mechanism of iron oxidation in Sulfobacillus we investigated the presence and expression of genes potentially related to iron oxidation by Sulfobacillus, especially the group of the so-called blue-copper proteins rusticyanin (rus) and sulfocyanin (soxE) in the course of the experiment. The physicochemical parameters and the population dynamics were monitored periodically in the columns and the metatranscriptome was analyzed by using pyro-sequencing. The average temperature inside the column ranged from 22 to 57 °C and the Fe(II) oxidation rate at 45 °C varied between 8 and 42 mg L-1h-1 along 300 days of operation. The metatranscriptomic analysis reveals an over-expression of 9-13 folds of the putative rus and soxE genes in four strains of Sulfobacillus spp. when the Sulfobacillus proportion in the column was >80% and the Fe(II) oxidation rate measured at 45 °C reached 10 mg L-1h-1. Some cytochromes from the electron transport chain were also over-expressed, on a range of 7 - 10 folds under those operational conditions. These results support the hypothetical participation of blue-copper proteins in the iron oxidation pathway of Sulfobacilli. Culture assays and more specific expression analysis are necessary in order to confirm this hypothesis. In addition, we attempt to establish the relationship between rusticyanin and sulfocyanin genes and perform a protein sequence analysis that allows us to infer the actual function of these proteins in Sulfobacillus species.
Reductive Dissolution of Iron Oxides and Manganese Bioleaching by Acidiphilium cryptum JF-5
Authors: González Ernesto , González F. , Muñoz J.A. , Blázquez M. Luisa , Ballester Antonio
Published: December 2015

In the development of new processes to use the potential of iron reducing bacteria,Acidiphilium cryptum, the main bacteria involved in the reduction of Fe (III) compounds in acidic environments, could play an important biohydrometallurgical role. Thus, the bioleaching of hematite, goethite and a low-grade manganese ore was assayed, in vials and columns, using three different media; two of which included a ligand, oxalate, or a redox mediator, thionine.Although the presence ofA. cryptumwas essential for promoting the dissolution of both iron oxides and the bioleaching of manganese ore, the addition of oxalate to the media tripled and quadrupled the microbial dissolution of hematite and goethite, respectively. Oxalate also had a positive effect in assays performed in columns, however, the addition of thionine to the medium allowed to reach significant hematite dissolution.
Reductive Dissolution of Ferric Iron in Laterite Overburden Using Acidithiobacillus Spp. and Neutrophilic Iron-Reducing Consortia
Authors: Marrero Jeannette , Coto Orquidea , Schippers Axel
Published: December 2015

Cuba is considered as one of the top world producer of nickel and cobalt. The laterite ore containing nickel and cobalt is mined after first removing an overburden of a long strip of soil and rock. The laterite has a high content of iron oxide (63%), which has to be removed in order to recover the nickel and cobalt. This study reports on the kinetics of reductive dissolution of the Fe(III) from the overburden by two native neutrophilic iron-reducing consortia as well as Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. All of the organisms mobilized the ferric iron in the laterite by reducing it to Fe(II). The AeRD process using At. thiooxidans was far more efficient in extracting total iron than the AnRD process using At. ferrooxidans.
Primary Copper Ore Leaching by Leaching Solution Adjusted Oxidation-Reduction Potential in Column
Authors: Shinkawa Tatsuya , Kamiya Taro , Kojima Kazuhiro , Chida Tadashi
Published: December 2015

Copper ore is classified into three groups; primary copper sulfide, copper oxide and secondary copper sulfide. Leaching copper from primary copper sulfide, such as chalcopyrite, with sulfuric acid takes longer time than from copper oxide and secondary copper sulfide. As such, an oxidant is required to extract copper from chalcopyrite. In this study, column leaching tests were carried out using primary copper sulfide ores produced in an iron oxide copper gold (IOCG) deposit and rich in iron in coparison to porphyry copper ores. The columns of 10 cm diameter and 100 cm long had a double tube structure so that the column temperature can be kept at desired temperature by circulating warm water in the outer tube. The oxidation-reduction potential (ORP) of the leaching solutions were adjustedto 400, 450 and 500 mV vs Ag/AgCl. The column leaching test using just pH 2.0 sulfuric acid without adjustment of ORP at 45 °C got a copper recovery rate of 37 % in 400 days. On the other hand, with ORP adjusted leaching solutions of pH 2.0 sulfuric acid containing 500 mg/L Fe, the copper recovery rate reached up to 87 % in 400 days.In addition, it was necessary to keep the temperature above 45 oC to enhance copper leaching by ORP adjusted leaching solution. The result of the column leaching test at room temperature (around 30 °C) using ORP adjusted leaching solution shows that the recovery rate of copper is lower than the result at 45 °C. The ORP adjustment of leaching solution is effective for leaching copper from primary copper sulfide ore, however, the leaching temperature needs to be kept above 45 °C. As a result, it makes clear that copper leaching is enhanced by utilization of ORP adjusted leaching solutions and suggests that the solution ORP control is important to the application of bioleaching.
Bioprocess for Leaching of Copper Concentrate
Authors: Muravyov Maxim I. , Fomchenko Natalya V. , Kondrat'eva Tamara F.
Published: December 2015

A bioprocess for oxide-sulfide copper flotation concentrates has been proposed. It includes: i) chemical step – leaching with sulfuric acid solution and subsequent high temperature ferric leaching with microbially produced Fe3+-containing solution, and ii) biological step – bioregeneration of ferric iron along with additional biooxidation of the sulfide minerals using moderately thermophilic acidophilic microorganisms. The flotation copper concentrates contained 27.0–37.4% copper as sulfide (digenite, bornite, etc.) and oxide (malachite, azurite, tenorite, etc.) minerals. The acid leaching under batch conditions at 50°C and pH 1.2 during 22 hours led to 40.6% of copper recovery from the concentrate. Subsequent ferric leaching of the acid leach residue at 80°C, pulp density 9%, initial concentration of Fe3+ 30.7 g/L, and pH 1.2–1.3 during 7 hours increased the total copper recovery to 94.5%. Bioregeneration of the Fe3+ was conducted using moderately thermophilic microorganisms including bacteria of the genus Sulfobacillus at 40°C in the presence of 3% leach residue. The average ferrous iron biooxidation rate and total copper recovery within 2 days were 1.0 g/L∙h and 97%, respectively.Leaching of copper under semi-continuous conditions with bioregeneration of Fe3+ at 40°C was studied. It was found that copper recovery achieved 90% within 22 hours and the average oxidation rate of ferrous iron was up to 0.95 g/L·h.
Insights into the Active Carbon Fixation Pathways of a Microbial Community in a Chalcopyrite Bioleaching Column
Authors: Marín Sabrina , Acosta Mauricio , Galleguillos Pedro , Chibwana Clement , Strauss Hannes , Demergasso Cecilia
Published: December 2015

Recently, a preliminary model has been proposed for relating the microbial succession of bioleaching heaps with the activity of different CO2 fixation pathways. In order to confirm this hypothesis and to understand the impact of the carbon metabolism in the metallurgical performance, the expression levels of carbon fixation pathways were investigated in a chalcopyrite bioleaching column test by transcriptomic analysis. The community structure, the physicochemical conditions and the metallurgical parameters were also analyzed. Gene expression profiles obtained by microarrays confirmed the temporal distribution of microorganisms as a function of the temperature and the different pathways for CO2 fixation. These results revealed the impact of the different CO2 fixation pathways in the composition of the microbial assemblage as the bioleaching proceeds.
The Microbial Ecology of Moderately Thermophilic Mineral Leaching Reactors: The Effect of Solids Loading and Organic Carbon Supplementation on Reactor Performance
Authors: Dean Jonathan , van Hille Robert P. , Harrison Susan T.L.
Published: December 2015

Tank bioleaching of refractory sulphidic gold ores is well established, with potential to expand application to base metal concentrates. With increasing commercial tank bioleaching operations, understanding their microbial consortia is essential for process robustness. Recently, it has been shown that the consortia implicated in tank mineral bioleaching of gold-containing pyritic ores are dynamic, responding to the leaching environment. Factors driving the microbial dynamics of these consortia are under investigation, with emphasis also placed on determining the metabolic role of the key players in these consortia.
Here, the combined influence of solids loading and organic carbon availability on microbial community dynamics and performance has been studied in agitated, aerated slurry bioreactors at 45°C. The control (autotrophic) and experimental (organic carbon added) reactors performed comparably at low solids loadings (4%, 7% and 10%). At 20% solids loadings, higher ferric iron concentrations (31 g/L vs 25g/L) and sulphide oxidation (66% vs 45%) were observed in the experimental reactor over the control. Under operating conditions used, a shift from bacterially-dominated cultures with L.ferriphilum as major species towards increasing archaeal abundance was observed. Archaeal abundance was higher in the organic carbon supplemented reactor at all solids loadings. The increased microbial diversity with organic supplementation appears to contribute to increased community robustness and associated leaching with increasing stress.
Process Parameter Study of Ferric Production in an Immobilization Bioreactor
Authors: Li Yuan Yuan , Du Juan , Zhao Huan , Cao Jun Ya , Zhang Guang Ji , Yang Chao
Published: December 2015

Fe(III) from biooxidation can be used in different industrial processes, such as hydrometallurgy, treatment of acid mine drainage and removal of H2S from some industrial waste gases. Many researches showed that the immobilization of the iron-oxidizing cells is helpful to increase the Fe(II) oxidation rate. In this study, a moderate thermopileSulfobacillus sibiricu(S.s)is immobilized and the polyurethane foam is chose as the supporter. A reactor is established for testing the capability of the immobilized bacteria and the optimum reaction conditions are investigated. The experimental results show that under the conditions that the initial concentration of Fe(II) is 10 g/L, the dilution rate is 0.165/h and aeration rate is 300 L/h, the maximum oxidizing rate of Fe(II) can be reached.
Biopolymers as Encapsulating Agents for the Immobilization of Prussian Blue and Analogues for the Sorption of Cesium
Authors: Vincent Chloë , Barré Yves , Vincent Thierry , Guibal Eric
Published: December 2015

Prussian Blue (PB, iron hexacyanoferrate) is an efficient micron-sized sorbent that can be encapsulated in a biopolymer matrix (chitin) for the treatment of Cs (I)-bearing solutions. Different conditionings have been designed for the treatment of Cs-contaminated effluents (with natural Cs (I) solutions, and with 137Cs spiked solutions). The sorbents conditioned under the form of beads or discs can be used in columns while sponges can be used for the treatment of accidental discharge of effluents (contaminated water absorption by the sponge, metal ions sorption on the ion-exchanger, treated water removal by centrifugation, metal concentration in the composite material).
Biopolymer Encapsulation of PEI-Derivatives for Heavy Metal Sorption
Authors: Bertagnolli Caroline , Vincent Thierry , Guibal Eric
Published: December 2015

Composite materials have been synthesized by alginate or chitosan encapsulation of polyethylenimine (PEI) derivatives (obtained by glutaraldehyde grafting of histidine and carbon disulfide). Discrete or agglomerated PEI-derivative particles are immobilized in the macroporous network of biopolymer matrix (as shown by scanning electron microscopy and SEM-EDX analysis). The effect of pH and initial concentration on Zn (II) and Cu (II) sorption performance were analyzed. The incorporation of PEI-derivatives biopolymer matrix improves sorption performance in complex solutions (doped with CaCl2) compared to pristine biopolymer. Maximum sorption capacities range from 0.64 to 1 mmol L-1 for Zn (II) and from 1.13 to 1.67 mmol L-1 for Cu (II).