bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrogen Absorption and Desorption in Steel by Electrolytic Charging
Authors: Mertens Geert , Duprez Lode , De Cooman Bruno C. , Verhaege Marc
Published: March 2009

The presence of hydrogen in steel decreases its toughness and formability leading to
hydrogen embrittlement. To understand the failure mechanisms of steel due to the presence of
hydrogen, a profound insight in the hydrogen household of the steel is needed. This includes a study
of the solubility, the diffusion and the trapping of hydrogen. Next, the absorption and desorption
behavior during and after electrolytic charging must be well determined. This was investigated in
this research for steels with various types of traps, e.g. dislocations, microcracks, grain boundaries
and precipitates such as TiC and Ti4C2S2. The samples were cathodically charged at three different
current densities: 0.8mA/cm2; 8.3mA/cm2 and 62.5mA/cm2. It was noticed that the cathodic current
density used for hydrogen loading had a great influence on the results. Observation of the samples
by scanning electron microscopy (SEM) showed that at the highest current density major damage of
the surface had occurred. Hence it was decided to study more systematically the influence of
charging current density on the resulting surface aspect and on hydrogen absorption and desorption.
The hydrogen charging kinetics, maximum hydrogen solubility and hydrogen desorption behavior
have also been evaluated for the different current densities during charging.
Study of the Deformation Mechanisms of TWIP Steels (Fe-Mn-C) by X-Ray Diffraction
Authors: Collet J.L. , Bley Françoise , Deschamps Alexis , Scott Colin
Published: March 2009

The deformation mechanisms of an Fe-Mn-C TWIP steel have been investigated as
a function of deformation and deformation temperature, using synchrotron X-ray diffraction
at the European synchrotron radiation facility. Using the Warren theory, it is possible to reach
a good qualitative understanding of the deformation mechanisms. We have confirmed that the
deformation mechanisms shifted from the formation of martensite at very low temperature, to
twinning around room temperature and dislocations at higher temperatures. Although some
quantification of the density of crystalline defects can be reached using simple parameters
such as peak shift and broadening, the complexity of defects present in this material require
the development of more advanced data interpretation models. First results are shown, using
shift and broadening of the peak and fit of intensity by a pseudo-voigt function, as well as the
study of the asymptotic behavior of the intensity.
Use of Zirconium in Microalloyed Steels
Authors: Maia A.R.B. , Guinâncio C.R. , Germano R.L. , Rios Paulo Rangel , de S. Bott Ivani
Published: March 2009

In this work, three Zr microalloyed steels with different levels of Zr were compared with
plain C-Mn, Nb and Nb-Ti steels. Austenitic grain size was compared as a function of temperature for
these steels. A qualitative assessment of the potential of Zr to delay austenite recrystallization, was
also undertaken. Of course, the actual use of Zr depends on many considerations: cost, availability and
behavior during steel refining among others but this preliminary assessment was encouraging. It
showed that the addition of Zr was able to prevent grain growth at typical reheating temperatures,
around 1200oC. Also, Zr was able to delay austenite recrystallization.
Surface Modification of TiZr Alloy for Biomedical Application
Authors: Chen X.B. , Nouri A. , Hodgson Peter , Wen Cui E
Published: March 2009

Titanium and some of its alloys are widely used as load-bearing implant materials. In
particular, titanium-zirconium (Ti-Zr) alloys have a high potential for biomedical applications due to
the excellent biocompatibility of both Ti and Zr. Nevertheless, the surfaces of the Ti-Zr alloys need to
be modified to provide the implant material’s bioactivity. In the present study, an alkali-heat (AH)
treatment process followed by the soaking in simulated body fluid (SBF) was attempted for the
preparation of calcium phosphate (CaP) coatings on the surface of the TiZr alloy. Phase
transformation, surface morphology, and interfacial microstructure were investigated using scanning
electron microscope (SEM) with an energy-dispersive electron probe X-ray analyser (EDS). The
results indicate that the AH treatment produced a nano-porous bioactive sodium titanate / zirconate
hydrogel surface layer which induced the deposition of a Ca-P layer during soaking in the SBF. This
Ca-P layer on the TiZr alloy surface can be expected to bond to the surrounding bones directly after
implantation.
The Refinement of Grain Structure in a High-Purity α-Iron Base Alloy under Multiaxial Compression
Authors: Lim S.M. , El Wahabi Mohamed , Desrayaud Christophe , Montheillet Frank
Published: March 2009

Multiaxial compression (MAC) is a severe plastic deformation (SPD) method that allows
sequential uniaxial compression of prismatic samples to relatively large cumulative strains. The
technique involves a change in loading direction (x to y to z to x…) between successive
compression passes. A high-purity α-iron containing 60 mass ppm C was thus strained using passes
of ε ∼ 0.4 at room temperature (0.16 Tm) and 450 °C (0.40 Tm) to total ε ranging from 1.4 to 2.9.
Both optical and electron microscopy were used to characterise the deformed microstructures.
Fragmentation of the initial grain structure occurs mainly in the form of a dense, homogeneous
network of low angle boundaries (LAB) delimiting subgrains of about 1 3m. The original grains are
easily distinguishable and maintain a relatively equiaxed appearance even at larger strains. At room
temperature, high angle boundaries (HAB) are observed within some of the initial grains, and not
necessarily close to the grain boundaries. These HAB may be open or closed, and tend to align
themselves at approximately 45° to the orthogonal axes, suggesting the presence of microshear
bands and thus a heterogeneous deformation. Such bands of localised strain criss-cross as a result of
different slip systems being activated from one pass to another. When the temperature is increased
to 450 °C, grain boundary migration becomes significant owing to the lack of impurities that could
otherwise provide a pinning effect. The resultant subgrain structure is coarsened to about 4 3m.
Besides, the enhancement of recovery at higher temperatures also appears to discourage the
generation of HAB by dislocation accumulation processes.
Characteristic Investigation on Substructures of High Purity Al Rolled at Room Temperature
Authors: Liang Xun , Deng Yun Lai , Zhang Xin Ming , Zhang Yong
Published: March 2009

Micro-orientation data of a high purity Al rolled up to total thickness reduction of 80% at
room temperature were determined using SEM-EBSD technique, conceptions of describing
substructure information, such as subgrain misorientation (θcry), and average misorientation (θenv) of
circumjacent subgrains for a special subgrain, etc., were suggested and corresponding GCDP-OI soft
package was developed. It is found that the subgrains sizes increase rapidly from about 2 to 7 μm with
increasing misorientations from 1° to 15°, and the total number frequency of which is more than 95%.
However, taking into account local features of subgrais, whose sizes for Dcry/Denv > 1 are 2 times
larger than that for Dcry/Denv < 1 on the same misorientation levels below 20°, and the relationships
between misorientations and sizes are consistent with that if Dcry/Denv > 1, θcry/θenv > 1, vice versa.
Effect of Textures on the Nanomechanical Properties of Nanocrystalline Fe-50%Ni Foil
Authors: Kim Jong Kweon , Choi Shi Hoon , Park Yong Bum
Published: March 2009

The textures and nanomechanical properties of nanocrystalline Fe-50wt%Ni foil
fabricated by using an electroforming method were investigated. The as-deposited texture was
characterized by major <100>//ND and minor <111>//ND fibre components. Annealing of the
as-deposited specimen resulted in the texture change that the <111>//ND fibre texture developed
strongly with decreasing <100>//ND intensity. The elastic modulus and hardness were investigated
by nanoindentation test, and these experimental results were compared with the theoretical
predictions based on an elastic self-consistent (ESC) polycrystal model. Annealing led to an increase
in the elastic modulus and a strong decrease in the hardness. At the low ratio of indentation depth to
the specimen thickness, the theoretical predictions of the elastic modulus in the sample thickness
direction showed a good agreement with experimental results.
Real-Time PCR Quantification of Protein Expression in Skin Equivalent Monoculture and Coculture Model
Authors: Wang Tzu Wei , Wu Hsi Chin , Sun Jui Sheng , Lin Feng Huei
Published: March 2009

Three-dimensional gelatin-chondroitin 6 sulphate-hyanuronic acid biomatrix was used as
the scaffold to investigate the phenotypic and molecular expression in human keratinocytes (K) and
dermal fibroblasts (FB) in three different culture conditions in vitro. The cells were cultured in
either monolayer (K or FB only) or coculture (K&FB) model. The deposition of basement
membrane proteins secreted by these two kinds of cells was quantitatively characterized by
real-time PCR. In the results, dermal fibroblasts were shown to synthesize and deposit laminin 5,
type IV and type VII collagen, whereas keratinocytes produced integrin alpha 6 and beta 4 as well
as laminin 5 and collagen type IV, VII. Interestingly, the integrin beta 4 subunit was not expressed
either in keratinocytes or dermal fibroblasts monoculture but was seen in organotypic coculture
model in the early culture period. Furthermore, we found that the expression of those marker
compounds was reciprocally regulated when keratinocytes and dermal fibroblasts were cultured
together. These results indicated that keratinocyes and dermal fibroblasts worked together to
reconstruct dermal-epidermal basement membrane (BM) zone. In brief, our data provide the first
time in directly quantifying the expression of BM proteins by using real-time PCR, and also
demonstrate that BM proteins were regulated by cell-cell interaction.
Orientation Microscopy on Nanostructured Electrodeposited NiCo-Films
Authors: Bastos A. , Zaefferer Stefan , Raabe Dierk
Published: March 2009

A Co-20at%Ni polycrystal produced by electrodeposition was studied in its detail using
orientation microscopy. By analyzing the local crystallographic texture, grain morphology
and the grain boundary character on three distinct sections of the film, we have obtained a
complete understanding of its microstructure. The microstructure and grain morphology is
very complex, consisting of grains elongated in deposit direction, clusters of coarse and fine
grains and further very fine structures. The deposition parameters generate a strong
(1120)//ND texture and the columnar grain reveals inner orientation gradients along the
growth direction
Effect of Film Thickness on the Annealing Texture in Sputtered and Electroplated Cu Films
Authors: Lee Sang Hoon , Park No Jin , Field David P. , Besser Paul R.
Published: March 2009

For optimum fabrication and usage of Cu films, an understanding of the relationship
between processing and microstructure is required. The existence of twins is another significant
factor for texture development in Cu films. Texture character and strength in the Cu film is
dependent on the twin boundary development that is a function of processing conditions and film
thickness. In this study, determination of grain growth and texture in the sputtered and
electroplated Cu films during annealing was performed for films of 100, 480 and 850 nm in
thickness deposited on a Ta(25 nm)/Si wafer. The texture was measured by X-ray pole figure.
The effect of film thickness on the annealing texture in the sputtered and electroplated Cu films is
examined and discussed.
Study on Development of a Surface Build-Up Welding Using CH-90 Electrode to Replace Mn-Containing Rail Steel
Authors: Lee Bo Young , An Dae Hwan , Kim Jae Sung , Jin Hyung Kook , Ryu Duck Hee
Published: March 2009

Rail steel at crossing areas bears much higher loads over any other section of a regular
railway. Mn-containing casting steel is normally used for its high load-carrying capability and
reduced wear rate. However, since Mn-containing casting steel tends to have casting defects, the
cost of manufacturing defect-free Mn-containing casting steel becomes quite expensive. Therefore,
through the use of welding, this study investigates the possibility of resurfacing Mn-containing rail
steel using a CH-90 electrode as an alternative to completely replacing it.
In this study, a series of experimental build up weldings was made and their microstructures,
chemical compositions, work-hardening index and friction coefficients were investigated. The
results showed that both microstructures and chemical compositions from the build up weld section
were similar to that of Mn-containing casting steel, showing an austenitic microstructure with
approximately 13% Mn. The friction coefficients measured closely to one another as well (mu of
Mn-containing steel = 0.847 and mu of the resurfaced weld metal = 0.831). The work-hardening
index of the build up weld metal was 30% higher than that of Mn-containing casting steel. This
difference could be attributed to the residual stresses in the build up weld metal which indicates that
the hardening speed of the build up weld metal is faster than that of Mn-containing casting steel by
impact. Therefore, build up welding, using a Mn-alloyed steel electrode on rail steel, could be a safe
and economic alternative to the high cost of Mn-containing casting rail steel replacement.
Mechanism of Rock Slope Failure in Selected Quarries in Oyo State, Nigeria
Authors: Akande J.M. , Idris M.A.
Published: March 2009

Rock slope failure mechanisms were assessed in this study using KOPEC
and RCC quarries as case studies in Oyo state. Discontinuities such as joints and
bedding planes were obtained through face mapping and scanline survey of the
excavated slopes of the quarries. Stereographic projections of the discontinuities were
generated using ROCKPACK III and the stereonets analyzed in accordance with
Markland’s plane failure analysis. The results of the analyses show that there are
possibilities of plane failures in the south- east region of KOPEC quarry slope face and
south –west region of RCC quarry slope face. It is therefore recommended that
constant monitoring of the slope failure should be done and the slope angle should be
less than 700 and 600 for KOPEC quarry and RCC quarry respectively.
Evaluation of Kinematics and Ergonomic Studies of Groundnut Oil Extraction Methods
Authors: Maunde F.A. , Ali M.A. , El Okene A. , Iya S.A.
Published: March 2009

Comparative evaluation of kinematics and ergonomic studies of traditional and
motorized kneading methods for extraction of groundnut oil was conducted. Moisture and oil
contents of Samnut-10 used was found to be 7.3% and 43.6 % respectively. Subject’s energy
capacity per day was 0.548 kcal / day. The average throughput capacities of kneading 5.5kg
groundnut paste for traditional and motorized kneading methods were 0.56 kg / minute and 0.87 kg
/ minute respectively. Average weights of oil obtained and extraction efficiency for the said
quantity for the traditional and motorized kneader were: (1.6kg, 1.7 kg) and (82.4 %, 91.33 %)
respectively. At the oil forming stage, the drudgery of kneading in traditional method was
eliminated by the motorized kneader via the fingers attached to the shaft in the hopper.
Physical Characterization of Ukpor and Ahoko Clay Deposits for use as Industrial Raw Material
Authors: Eterigho E.J. , Olutoye M.A.
Published: March 2009

The physical properties of some Nigerian clays were studied in order to determine their
suitability for a variety of industrial applications. From the analysis, the specific gravity of Ukpor
and Ahoko clays were 1.89 and 2.26 respectively and the Plasticity Index 26.05% and 22.45%,
drying shrinkage was 18.90% and 8.2% and particle size distribution showed that the samples are
clays. The results show that the physical properties of the clays are within the specifications for
kaolin clays and are suitable for industrial uses.
Comparison between Pressure Drop Profile of a Horizontal Well as a Water Injector and as an Oil Producer in a Five-Spot Waterflood Pattern
Authors: Adewole E. Steve , Olafuyi O.A.
Published: March 2009

This paper compares the pressure drop profiles of both horizontal well producer and
injector in a 5spot waterflood pattern. Dimensionless pressure distributions for each pattern were
utilised. All computations were limited to conditions of unit mobility ratio; i.e., before water
breakthrough condition. Results show that a normal 5-spot flood pattern, with a horizontal well
producer, offers higher pressure drops, but early water breakthrough tendencies, than as an injector
for the same reservoir and wellbore conditions. An inverted pattern, under the same conditions,
produces clean oil for a longer time, before water breakthrough possibilities.
Heuristics for Minimizing Total Completion Time on Single Machine with Release Time
Authors: Oyetunji Elkanah , Oluleye Ayodeji Emmanuel
Published: March 2009

This paper focuses on the problem of scheduling n jobs with release dates on a single
machine in order to minimize the total completion time. Since the problem has been characterized
as strongly NP-hard, two heuristics (HR1 and AEO) were proposed for solving the problem in
polynomial time. The heuristics were compared with the best approximation algorithm for this
problem to date (Best-alpha). Experimental results show that AEO performed better than the Bestalpha
algorithm (selected from the literature) when the number of jobs (n) exceeds 5. This
observation should prove useful in the operational dispatch of jobs in industrial production settings
as well as the service sector.
Enterprise Modelling in Support of the Application of Lean Manufacturing in SMEs
Authors: Ajaefobi J.O. , Weston R.H.
Published: March 2009

Over more than two decades the authors and their research colleagues have investigated
different ways of using enterprise, simulation and workflow modelling techniques to structure and
support decision making during organisation design and change projects. This has involved
collaborative research with large and small scale manufacturing enterprises [1]. The investigations
have demonstrated and advanced the potential to use enterprise models that ‘externalise and share
knowledge about enterprise processes and systems’. By so doing, enhanced understanding of
enterprise structures, processes and resource systems can be obtained and used to improve the
interactions between system components so as to realise desired business performance and constrain
unwanted behaviours.
Performance Optimization of a Thrust-Vectoring Nozzle
Authors: Adavbiele A.S. , Salami L.A.
Published: March 2009

This study employed Computational Fluid Dynamics, CFD solution to configure the
entire shape of the nozzle. The problems arising from the initial geometrical shape obtained using
one-dimensional approach were highlighted. Then with a two-dimensional approach and coded
FORTRAN programs, the convergent portion was handled with time matching CFD while the
divergent portion was handled with space matching CFD. A post-processing results analysis shows
that the results are in agreement with that obtained with the analytical approach. This research has
demonstrated significant and tangible benefits of the use of CFD numerical experimentation to
optimize the shape of the nozzle. These benefits are not solely limited to performance
enhancements, but solution reliability and algorithm development.
Design of a Fixed Bed Adsorber Unit Using Microsoft Excel Spreadsheet
Authors: Ogbeide S.E. , Okieimen C.O. , Anyiador O. , Odukwe V.
Published: March 2009

The design of a fixed bed adsorption unit using adsorbent produced from locally available
palm kernel shell has been investigated using Microsoft Excel spreadsheet. Various mathematical
models were considered but the simpler and more convenient Wheeler-Robell model was adopted
in the design. The model was adopted in designing a template with Microsoft Excel Spreadsheet. A
Microsoft Excel Spreadsheet was developed for the design. The template was used to determine the
design parameters, such as length of column, diameter of bed, bed height and pressure drop across
the bed.
Versatile Work Holding Device for Hole Drilling in Small-Scale Production Workshops
Authors: Okoli John U. , Jinyemiema Tamuno K.
Published: March 2009

This devise addresses the inadequacies of providing a quick means of holding jobs of
irregular shapes such as are encountered in small scale fabrication workshops. The conventional
bench vise often does not provide the adequate grip for such shapes so that attachments in the form
of V blocks are usually provided to enhance the grip before drilling operations are carried out. This
versatile work holding device enables fabricators to perform drilling and other production operations
on a work piece. This device produced from mild steel plates uses the toggle principle to provide
rapid grip. Comparative tests on time span in the use of this device and the bench vice for job set up,
production operation and then disassembly showed that time is gained with use of the device.
Comparative Study of Biogas Production from Five Substrates
Authors: Ojolo S.J. , Dinrifo R.R. , Adesuyi K.B.
Published: March 2009

In this work, a comparative study of biogas production from poultry droppings, cattle
dung, kitchen waste, fruit waste and vegetable waste was done under the same operating conditions.
3kg of each waste was mixed with 9kg of water and loaded into the 5 constructed digesters. Biogas
production was measured using water displacement method for a period of 40 days and at an
average temperature of 30.5oC.
Results indicated that poultry droppings produced 0.0332dm3/day, cow dung produced
0.0238dm3/day, Kitchen waste produced 0.0080dm3/day, vegetable waste produced 0.0066dm3/day
and fruit waste with 0.0022dm3/day. It is concluded that poultry droppings produced more biogas
because it contains more nutrients and nitrogen compared with plant and other animal waste
Design, Fabrication and Performance Test of a Prototype Biogas Digester
Authors: Aisien F.A. , Akakasiaka U.F. , Otoibhi O.G. , Aisien E.T.
Published: March 2009

The search for alternative sources of energy from organic waste has been on in Nigeria.
This report focuses on a simple design, fabrication and performance test of a prototype biogas
digester. The volume of the digester was 340dm3 and that of the absorber/adsorber was 12.5dm3. The
digester was fabricated using mild and stainless steels, styrofoam, polythene sheets and other
materials. The digester can be moved about and agitated manually. In the performance test, 8.134L of
biogas was generated within 14 days of anaerobic digestion of palm oil mill effluent (POME). The
optimum pH and temperature for biogas production were 6.2 and 29oC respectively.
Software Development for the Water Sector
Authors: Taigbenu Akpofure E. , Ilemobade Adesola A.
Published: March 2009

The water sector in the last 20 years has undergone radical paradigm shifts arising
from the crisis of global proportions that have characterized the sector, prompting many
international fora, including the Dublin conference in January 1992. One of the responses from
academic institutions to this crisis is the development of computer-based predictive tools for
better and more accurate prediction of the variables that affect water use and management. In the
School of Civil and Environmental Engineering at the University of the Witwatersrand, attempts
have been made to develop software to aid planning, management, and decision making in the
water sector. Two of such software are Wadessy - a water distribution network design software,
and a groundwater flow modelling software GEMFLOW that is based on the Green element
method (GEM). Although their engines are quite robust and have been applied in field studies in
Botswana and Zimbabwe, and compare favourably with published models, their elegance in
terms of graphical user interface (GUI) is still rudimentary. The cost for their development has
been mainly in the training of postgraduate students who have assisted in their development.
Industry uptake has been very limited, which is one of the reasons why their GUIs are still
rudimentary. With greater investment into the development and marketing of these and many
other software, the potential exists to have “made-in-Africa” software with capabilities
comparable, if not better than, those developed in more advanced countries. This paper reports
on these software, compares these with similar initiatives in more advanced countries, and
discusses the challenges in development, funding, and uptake by industry. The experiences
described herein are most likely to be similar with other software development initiatives in sub-
Saharan Africa.
Solid-Liquid Separation Process: Modelling for Design and Development of Gravity Deep-Bed Filters for Water Treatment
Authors: Ekenta O.E. , Anyata B.U.
Published: March 2009

This work focuses on the conception and formulation of appropriate filtration models for
use by water treatment professionals for design, development and management of deep-bed (depth)
filters. Performance and optimization studies were carried out using data (turbidity, filtration rate,
head loss) acquired from pilot filter test runs. The curves developed from these studies were utilized
for the formulation of steady-state and hydro-dynamic models of depth filtration. An effluent
quality model was developed, relating depth of flow in filter bed with effluent turbidity. This model
was verified and validated. The depths obtained are in good agreement with standard values from
literature.
Investigation of the Normal Working Mode of the Nigerian 330-132 kV Network in View of Perspective Load Growth Forecast up to 10 years
Authors: Melodi Adegoke Oladipo
Published: March 2009

In this paper the normal regimes of the Nigerian 330-132 kV power grid at 2003-2005
year levels were analyzed. The load flow studies were also carried out at perspective load growth
forecast up to 10 years based on exponential trend using a program (Newton’s method). An analysis
of results shows that with existing available generation and maximum load estimate by the utility
there is a deficit which will persist if generation, commensurate with load growth, is not
immediately reinforced. The network lacks adequate reactive power sources to maintain permissible
bus voltages and the power transfer capability due to thermal constraints.
Discovering Potential Sites for Small Hydro Power (SHP) in Nigeria
Authors: Adejumobi I.A. , Esan A.A. , Okunuga A.B.
Published: March 2009

This paper is a survey and analytical work on the discovered potential hydropower sites
in Nigeria by the authors. Hydrological data of dams and rivers have been collected from various
locations in Nigeria. Mathematical model for energy conversion process to determine the plant
generating capacities of the identified sites were developed. A computer program in Q- Basic has
also been developed for fast analysis and accuracy. Simulations were done on the collected data.
From the obtained results, about thirty-two potential sites have been have discovered suitable to
generate between 16kW and 700kW electric power. Appropriate turbine types were suggested.
Biological Purification of Silicate Minerals
Authors: Štyriaková Iveta , Lovás Michal
Published: March 2009

Bioleaching is technology applicable to iron extraction from low-grade non-metallic raw materials. Bioleaching of quartz sands and feldspars involves the action of heterotrophic bacteria. Impurities include fine – grained limonite, goethite, hematite or mica were removed by the reductive dissolution of Fe3+ in linked with the silicate mineral destruction. Heterotrophic bacteria produced organic acids that are able to solubilize Fe oxide and silicates but require organic carbon as a source of energy. Molasses is a relatively inexpensive carbon source used for various industrial fermentations and contains also other nutrients that accounted for the enhancement of iron dissolution in this study. The admixture of pigments in molasses coloured the samples, but the discoloration could be removed by the addition of NaClO following the bioleaching step. The feasibility of the bioleaching treatment has to be tested specifically to each type of silicate raw materials. The Fe content in the quartz sands and feldspar samples by the biological leaching decreased as much as 60% and by subsequent using of electromagnetic separation of feldspars, the decrease of Fe content in 74% was achieved. However, the application of magnetic separation of quartz sands after bioleaching resulted in total iron removal of 93 % and in such combined way prepared product contained 0.024 % of Fe2O3. Achieved results on iron removal point to the fact that combination of leaching and magnetic separation enables to obtain product usable in glass and ceramic industry.
Monitoring of Hydrocarbon Gaseous Compounds formed During Bioleaching of Copper Sulphide Minerals with Mesophilic Microorganisms
Authors: Luca R. , Vargas T. , Escobar B. , Townley B.
Published: March 2009

An experimental campaign was conducted for monitoring the formation of hydrocarbon
gaseous compounds during bioleaching of copper sulphide ores with mesophilic microorganisms.
Three different mineral samples were used: a pyrite concentrate, a chalcopyrite concentrate and a
copper sulphide ore rock from El Teniente mine containing 1 % copper. Mineral samples were
bioleached in 250 ml shake flasks containing 100 ml of basal medium inoculated either with a pure
strain of Acidithiobacillus ferrooxidans or a natural bacteria consortium obtained from the acid
leaching of El Teniente ore in columns. Each sealed system shake flask was fed with a flow of
synthetic air and the exit stream was passed through a column containing an adsorbent material and
next through a water trap as to avoid back air contamination from the environment. Compounds
present in the adsorbent material after 90 days of bioleaching were analysed using a gas
chromatography mass spectrometry technique with a procedure that detects 162 different
hydrocarbon gaseous compounds (SGH). Results showed that the bacterial communities in copper
sulphide bioleaching results in the formation of some hydrocarbon gaseous compounds, mainly
various types of methyl benzene and branched alkanes. The formation of these organic compounds is
likely to be related to the presence of heterothrofic microorganisms present in the natural populations.
Kinetic Measurement of Biological Oxidation of Ferrous Iron at Low Ferric to Ferrous Ratios in a Controlled Potential Batch Reactor
Authors: Kazadi Thierry Kamunga , Petersen Jochen
Published: March 2009

Traditionally, the kinetics of microbial ferrous iron oxidation have been studied in continuous culture or in batch. Both methods have drawbacks: in continuous culture experiments have to be repeated at a number of dilution rates to cover the entire spectrum of ferrous to ferric ratios, which is time-consuming. Furthermore, experiments at very low ferric to ferrous ratios generally fail due to microbial wash-out at the high dilution rates needed to achieve these. In batch experiments, on the other hand, the prevalent ferric to ferrous ratio rapidly changes due to substrate depletion while the microbial population continually grows, making determination of specific momentary rates difficult. The present paper describes initial work with a novel device, the Redostat™, which allows careful electrochemical control of ferric to ferrous ratio in a batch reactor. A culture of Leptospirillum ferriphilum was grown at 35°C and 5 g/L total iron by maintaining the ferric to ferrous ratio at 0.17, 0.51 and 1.65 (corresponding to redox potentials of 419, 452 and 482 mV vs. Ag/AgCl), respectively. The correlation of data obtained from off-gas and current measurements was excellent, and fitted Monod kinetics with ferric inhibition. A hitherto unobserved effect indicates the onset of ferric iron inhibition at the low redox potentials employed here.
In-Lake Bioreactors for the Treatment of Acid Mine Water in Pit Lakes
Authors: Preuss Volker , Horn Martin , Koschorreck Matthias , Luther Günter , Wendt-Potthoff Katrin , Geller Walter
Published: March 2009

For the treatment of acid mine water an in-situ pilot plant with a self-sufficient energy
supply and remote data transmission was tested in acidic pit lake 111, a small lake in the Lusatian
mining district in Germany. In this paper the design of the enclosure-bioreactor in-lake system, the
mode of operation of a three-stage treatment process by the use of anaerobic fixed film reactors and
the results of treatment are shown.
Mine Waste Stabilization with Biosludge and Ca Carbonate Residues: Column Experiments
Authors: Herbert Roger B. , Höckert Linda , von Brömssen Mattias , Friis Helen , Jacks Gunnar
Published: March 2009

Column experiments investigated the stabilization of waste rock from Ljusnarsberg mine in Kopparberg, Sweden. In order to inhibit the generation of acidic leachate from the waste rock, biosludge and a Ca carbonate – rich residue from the paper industry were mixed with the sulfidic mine waste. The results of the column experiments indicate that the stabilization of the waste rock with the reactive amendments succeeded in maintaining a near – neutral pH in the waste rock leachate, compared to a pH 3 leachate from untreated waste rock. Copper and Zn concentrations in leachate from the untreated waste exceeded 100 mg/L, while these metals were detected at concentrations less than 0.1 and 1 mg/L, respectively, in the leachate from the treated wastes. This study indicates that the stabilization of acid – generating waste rock with biosludge and Ca carbonate residues is effective in preventing the generation of acid mine drainage; the treatment is expected to continue until the reactive amendments are exhausted.
Application Possibility of Bentonite and Zeolite in Bioremediation
Authors: Jablonovská Katarína , Štyriaková Iveta
Published: March 2009

This paper investigates Zn2+ and Cu2+ adsorption capability of bentonite and zeolite taken from the non-raw metallic deposits of Slovakia. Viable biomass of an Bacillus pumilus and Bacillus megaterium enhanced the efficiency of Zn2+ and Cu2+ adsorption from model solution. Initial concentration of Cu and Zn in model solutions initially containing 32.3 mg.Cu.L-1and 42.9 mg Zn.L-1 after six hours sorption and desorption at 25°C, it was observed that 1g bentonite whit bacteria inokulum was found to remove 0.195 mg Zn2+ and 0.17 mg Cu2+ from the solution and 1g zeolite was found to remove 0.088 Zn2+ and 0.051 Cu2+. The ability for Zn and Cu sorption was bentonite > zeolite. The adsorption of metal ions on bentonite and zeolite depends on pH. Between pH 4 and 6, the main mechanism is by ion exchange. In order to prevent contamination of subsoil and groundwater by leachates containing heavy metals, bentonite and zeolite are widely used as cost-effective treatments barriers. For this reason it is important to study the adsorption of metals by these materials.
Laboratory Investigations on the Interactions of Soil, Water and Microorganisms with Manganese
Authors: Lorenz Christian , Merten Dirk , Haferburg Götz , Büchel Georg
Published: March 2009

Column experiments were carried out using contaminated geosubstrates and previously isolated Streptomyces strains from the former uranium mining area Ronneburg (Germany) to study transfer processes of heavy metals including radionuclides. Preliminary tests with comparatively low heavy metal and radionuclide contaminated surface material showed strongly elevated Mn concentrations up to 1060 #g/l after passage through inoculated columns. In contrast, the eluates of non inoculated columns showed, after a “first flush”, low Mn concentrations around 30 #g/l. Poisoned control columns showed decreasing concentrations after the “first flush” (maximum Mn release of 540 #g/l). Highest manganese release from the inoculated, non poisoned columns corresponded with strongly decreasing redox potentials (+200 to -270 mV), which probably indicates microbially catalysed manganese release through reductive processes. One of the strains isolated from the column material was identified as a potentially heavy metal resistant strain of Cupriavidus metallidurans. It showed tolerance of up to 30 mM Mn (II), however no aerobic Mn (IV) reduction processes were indicated.
Chemical Stabilisation Combined with Phytostabilisation Applied to Mine Waste Contaminated Soils in Hungary
Authors: Feigl Viktória , Atkári Ágota , Anton Attila , Gruiz Katalin
Published: March 2009

Gyöngyösoroszi is an abandoned lead-zinc sulphide ore mining area in Hungary. The diffuse pollution sources of mining origin identified in the area and the residual pollution after removal of the point sources will be subjected to combined chemical- and phytostabilisation. To select the best chemical stabiliser laboratory scale experiments were performed in microcosms. The following chemical additives were tested in various concentrations: three different fly ashes, lignite, alginite, hydrated lime, raw phosphate, iron hydroxide wastes from drinking-water treatment, red mud and the mixture of selected ones. The stabilisation of toxic metals in the soil was monitored by an integrated methodology, which combined physico-chemical analysis with toxicity testing. Based on the chemical analytical and the bacterial and plant toxicity test results, one of the tested fly ash types was the most effective: the mobile Cd and Zn concentration decreased by 50–99% in the fly ash treated contaminated soil, the bacterial and plant toxicity decreased by 30-70%, and the bioaccumulated metal amount by 70%. The combination of lignite, alginite, lime and phosphate was also efficient.
The Catalytic Influence of Sulfolobus metallicus in the Bioleaching of Chalcopyrite: Role of Attached and Planktonic Population
Authors: Gautier V. , Escobar B. , Vargas T.
Published: March 2009

The catalytic influence of Sulfolobus metallicus in the bioleaching of pure chalcopyrite at
70° C and pH 1.5 was studied in shake flask experiments. In order to evaluate separately the
influence of planktonic and attached cells on the catalytic process, in some experiments the
microorganisms were prevented from reaching chalcopyrite surface by keeping them in a chamber
separated by a 0.1 Millipore membrane. Leaching, which was conducted with a -80 # + 120#
chalcopyrite sample, was characterized from monitoring Eh, pH, copper, ferrous and ferric ion
concentration in solution. In addition, the concentration of different sulphur species dissolved in
solution either in aerated-abiotic and aerobic - biotic conditions, was determined with HPLC.
Maximum copper dissolution was reached in experiments where all the microorganisms could
reach chalcopyrite. In experiments where microorganisms were maintained separated from the
sulphide, the population of microorganisms still increased. However, in this case copper dissolution
was only 50 % of the maximum reached when contact of microorganisms with chalcopyrite was
allowed, similar to that obtained in aerobic-abiotic conditions. On the other hand, in aerobic-abiotic
conditions there was formation of bisulfite (HSO3)-, bisulfate (HSO4)- and sulfate (SO4)2-, while in
leaching experiments where microorganisms could reach chalcopyrite the formation of thiosulfate
(S2O3)2- and sulfite (SO3)2- was additionally observed. It can be concluded that bioleaching of
chalcopyrite in the presence of Sulfolobus metallicus is the result of the cooperative action of
attached cells which catalize copper dissolution through formation of thiosulfate, sulfite and
bisulfite, and planktonic cells which further oxidize these intermediate compound to bi-sulfate and
sulfate.
Removal of Organically Bound Sulfur From Oil Shale by Iron(III)-Ion Generated-Regenerated from Pyrite by the Action of Acidithiobacillus ferrooxidans
Authors: Beškoski Vladimir P. , Milic Jelena , Mandic Boris , Takic Milos , Vrvić Miroslav M.
Published: March 2009

Oil shales are one of the alternative sources of hydrocarbon fuels (“synthetic petroleum”), characterized by the increased sulfur and nitrogen content which represent even greater ecological problem in use, compared to classical fuels. Acidithiobacillus ferrooxidans is capable of oxidizing pyrite to iron (III)-ion, providing a strong oxidation agent at low pH. We have used this oxidizing agent for oxidation of sulfur present in DBT as a substrate model to demonstrate its potential to oxidize organically bound sulfur in oil shales. An HCl-concentrate was used as the hydrocarbon matrix. Acidithiobacillus ferrooxidans is already recognized to oxidize the pyritic sulfur component, thereby potentially providing a complete sulfur removal system. By applying GC-MS we established that DBT transformation occurred by oxidation or elimination of sulfur. The products obtained are more soluble in water than parent compounds and this reduces concentration of organic sulfur.
Analysis of the Microbial Community in the Leachate Collected from an Experimental Bioleaching Column by Cloning and RFLP
Authors: Mutch L.A. , Watkin Elizabeth L.J. , Watling Helen R.
Published: March 2009

A culture independent molecular methodology was used to investigate the bacterial and archaeal microbial dynamics of leachate collected from a 60°C chalcopyrite bioleaching column inoculated with a known microbial consortium. A 16S rRNA gene clone library was constructed for both the bacterial and archaeal populations in the leachate from the column. PCR-RFLP analysis of these clone libraries indicate species dominance and generally low species diversity.
Microbial Diversity in an Iron Oxidation Tank of an AMD Treatment Plant at an Abandoned Sulphur Mine
Authors: Suto Koichi , Bacosa Hernando , Inoue Chihiro , Matsushima Eiji
Published: March 2009

This paper describes about microbial diversity in an iron oxidation tank of an AMD
treatment plant established at an abandoned sulphur mine in Japan. Since the mining operation was
stopped, this mine has produced strong acidic mine drainage, pH 1.8, including a high concentration
of ferrous iron, 301mg/L, and the flow rate was about 4m3/min. In 2006, a pilot scale microbial iron
oxidizing system was installed to remove total iron more easily from the AMD by oxidizing ferrous
iron to ferric iron. From the start of this pilot operation, microbial diversity in the iron oxidation
tank was investigated using a PCR-DGGE method for about two months. In the PCR, V3 region of
16S rRNA gene for Bacteria was amplified. The profiles of DGGE showed that there were three
dominant species in the iron oxidation tank through the experimental period. Number of bands on
DGGE profiles decreased with dates of sampling so that the microbial population became less
diverse because of the iron oxidizing operation. There was a wide variety of bacterial species of
even though conditions were strongly acidic.
High-Rate Fluidized-Bed Ferric Sulfate Generation for Hydrometallurgical Applications
Authors: Puhakka Jaakko A. , Kinnunen Päivi H.M. , van der Meer Tuomas , Özkaya Bestamin , Sahinkaya Erkan , Kaksonen Anna H. , Nurmi Pauliina
Published: March 2009

An overview is presented of a multi-year research effort on developing high-rate
fluidized-bed bioprocesses for ferric sulfate production to be used as a unit process in various
hydrometallurgical applications including indirect tank leaching of ore concentrates, regeneration
of heap leach liquors and control of iron containing acidic mine wastewater. Iron oxidation rates of
over 26 kg m-3 h-1 were achieved at hydraulic retention times of less than 1 h at 37 °C. Oxygen
supply became the rate-limiting factor even with 99.5% dioxygen aeration. Fe2+ oxidation
proceeded at pH below 1 even in the presence of 60 g Fe3+ L-1 allowing the regeneration of
concentrated ferric sulphate solutions required in indirect tank leaching of sulfidic ore concentrate
applications. Of several tested FBR carrier materials activated carbon was the most suitable based
on its availability, long-term durability and the achieved high iron oxidation rates. Jarosite
precipitates accumulating to the top of the inert carrier materials played an important role in the
FBR biomass retainment. For regeneration of synthetic and actual sulfidic ore heap leaching
liquors, a gravity settler was installed in the recycle line of the FBR. The system produced iron
precipitates with good settling characteristics and settling tank effluent with low turbidity and
suspended solids concentrations. These results revealed the potential of FBR process in both heap
leach liquor regeneration and controlling the iron containing waste streams. The PCR-DGGE-partial
seguencing of the 16S rRNA gene protocol revealed that the FBR culture at 25-37 °C remained
dominated by Leptospirillum ferriphilum over a range of operational conditions studied over the
years. A modeling approach for managing Fe3+ production by FBR in combination with heap
leaching was based on an artificial neural network-back propagation algorithm (ANN-HEAP) and
resulted in excellent match between the measured and the predicted concentrations. High-rate
fluidized-bed iron oxidation is amenable to regeneration of tank and heap leaching solutions as well
as controlling iron containing waste streams.
Isolation and Molecular Characterization of Sulfate Reducing Bacteria in a Brazilian Acid Mine Drainage
Authors: Rampinelli L.R. , Azevedo R.D. , Guerra-Sá R. , Teixeira Monica , Leão V.A.
Published: March 2009

Acid mine drainage (AMD) waters are highly acidic (pH < 4), contain high concentrations of sulfate and dissolved metals, and are very toxic to many living organisms. The development of technologies to treat sulfate contaminated wastewaters by using sulfate-reducing bacteria (SRB) has produced a cost-effective route to treat AMD. Notwithstanding, the SRB sensitivity to acid limits their use in AMD remediation. In the current study, acidophilic strains of SRB were isolated from an AMD followed by their molecular characterization. One SRB-culture was able to grow at pH 4.5 in Postgate C modified medium containing ethanol as carbon source, indicating that such bacterium has the potential for the bioremediation of acidic waters. Following, the strains were characterized by molecular biology techniques. The characterization was done by PCR amplification, cloning and sequencing of the genes coding for parts of the alpha and beta subunits of dissimilatory sulfite reductase (dsrAB) and hydrogenase (hyd), which encode key enzymes of the SRB energy metabolism. Phylogenetic analysis suggested a line of SRB descent from the delta-Proteobacteria among the strains identified as Desulfovibrio fructosovorans.
Sulfur Oxidation and Coupled Iron Reduction at Low Temperatures
Authors: Kupka Daniel , Dopson Mark , Tuovinen Olli H.
Published: March 2009

The purpose of this work was to characterize elemental sulfur oxidation by
a psychrotrophic Acidithiobacillus ferrooxidans culture that originated from an AMD-impacted
surface soil in a permafrost area in northern Siberia. In this work, the iron-oxidizing culture was
cultivated with elemental sulfur with and without Fe2+ or Fe3+ in flasks on a shaker to avoid oxygen
limitation.