bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Orientation and Temperature on the Mechanical Properties of Commercially Pure Titanium
Authors: Battaini Michael , Pereloma Elena V. , Davies Chris H.J.
Published: March 2009

This paper investigates the changes in deformation mechanisms of commercially pure
titanium over a range of temperatures for different orientations relative to the initial rolling texture.
Samples from grade 1 titanium plate were tested in plane strain compression (PSC). Extremes of
orientation relative to the predominant split basal texture were tested at temperatures from 25°C to
700°C. Specimens were subsequently examined using X-ray texture analysis and electron
back-scatter diffraction (EBSD). Changing the orientation resulted in substantial yield stress
anisotropy. This was found to be largely related to the orientation of the dominant texture relative to
the most favorable orientation for the easiest slip mode (prism slip), and significantly but to a lesser
extent on differences in twinning behaviour. The most important difference in twinning was the
operation of {1012} tensile twinning in c-axis tension and {1122} compression twinning in c-axis
extension. Calculations indicated that at low temperature both of these twinning modes accommodate
a significant amount of strain. Twinning was also found to be the most significant factor affecting
work hardening behaviour, with reorientation hardening occurring for some sample orientations. As
temperature was increased above ~350°C {1011} twinning became the dominant twinning mode, but
its contribution to the strain was not as large as the low temperature twinning modes, and the total
amount of twinning decreased with temperature. The decrease in twinning with increasing
temperature led to a reduction in the difference in work hardening behaviour. The quantitative
information gathered in the course of this work is discussed in the context of mechanical property
prediction.
Strain Path Effects on Titanium Alloy Timetal-834 under Hot Working Conditions
Authors: Blackmore M.L. , Wynne Bradley P. , Beynon John H. , Davies Peter S.
Published: March 2009

The effects of strain path reversal under hot working conditions on the microstructure
and crystallographic texture in the near-α titanium alloy Timetal-834 have been studied using high
resolution electron backscatter diffraction (EBSD). The main objective of the work was to
investigate the potential effect strain path may have on breaking up the well known clustering of
similarly orientated primary alphas grains in the alloy, which significantly reduces its low cycle
dwell fatigue lifetime. Deformation was carried out using forward torsion to an equivalent strain of
0.9 and forward/reverse torsion of two equal steps to produce a total strain of 0.9. The tests were
performed at a typical industrial forging condition of 990°C (~50% alpha, ~50% beta) at an
equivalent tensile strain rate of 2s-1. Investigation of the microstructure showed the primary alpha
grains to align with the direction of torsion for the forward test and return to an equiaxed shape on
strain reversal, though a significant numbers of deformation twins are formed and retained after the
full strain reversal. Analysis of the texture of the starting material showed the typically clustering
of primary alpha grains, which upon forward torsion and forward/reverse torsion did not break
down. This indicates that during a typical forging operation the clustering of similarly orientated
primary alpha grains inherited from the as-received billet will not be reduced. This suggests that
improved in-service performance of this alloy can only be achieved by reducing the clustering
upstream in the manufacture of the billet.
Impact of Augmented Reality (AR) in Civil Engineering
Authors: Kumaran G. Senthil , Santhi K.R. , Anand P.M.Rubesh
Published: March 2009

The ability to view constructions virtually before using the real resources to construct
them has been of main interest in civil engineering over a long period of time. This has been
achieved partially through virtual reality. Virtual Reality helps in visualizing the operations on
computer generated jobsites and to study the available alternate plans. Even though the latest
software in virtual reality helps us in designing and drawing the plans, the question of reality still
arises. The plans that are done in computer sometimes do not match with the real practical
applications. This shows that it is difficult to bring the experiences of practical world into the
computer. In order to overcome the gap between the real and virtual environments, this paper
highlights the use of Augmented Reality (AR) in all the areas of civil engineering instead of using
Virtual Reality. This paper describes the developing augmented reality technology and its various
application domains in civil engineering.
Bioleaching of a Rich-In-Carbonates Copper Ore at Alkaline pH
Authors: Groudeva V.I. , Krumova K. , Groudev Stoyan N.
Published: March 2009

A rich-in- carbonates copper ore was subjected to bioleaching under alkaline pH
conditions by means of different microorganisms or their metabolites. The ore contained 1.40%
copper, 1.94% sulphur, 3.25% iron and 20.3% carbonates, and had a pH of 8.6 and a highly positive
net neutralization potential (325 kg CaCO3/t). Copper was present mainly as different sulphide
minerals (bornite, covellite, chalcopyrite). The leaching was carried out by means of the shake-flask
technique at 32 oC using finely ground (minus 100 μm) ore. The following microorganisms were
used to leach the sample: ammonifying bacteria (related to the genera Bacillus, Acinetocater and
Vibrio); heterotrophic bacteria (Acetobacter and Pseudomonas) and fungi (Asperillus niger and
Penicillium chrysogenum) producing citric acid; heterotrophic bacteria (Micrococcus, Alcaligenes
and Bacillus) producing amino acids (mainly alanine); basophilic chemolithotrophic bacteria
(Thiobacillus thioparus, Hallothiobacillus neapolitanus, Starkeya novella; ”silicate bacteria”
(Bacillus circulans) producing organic acids and exopolysaccharides; bacteria possessing urease
enzymatic activity (Corynebacterium). The best results were achieved by means of a mixed culture
of urease-possessing bacteria, which under certain conditions was able to solubilize 64.4% of the
copper within 30 days of leaching.
Bioleaching of a High Iron Content Kaolin by Aspergillus niger: The Effects of Organic Acids Biosynthesis
Authors: Pazouki Mohammad , Hosseini M.R. , Ranjbar M. , Ghavipanjeh F.
Published: March 2009

In this work, bioleaching of iron from a kaolin sample was carried out using two different
strains of Aspergillus niger, and the effects of strain type, pulp density, and addition time of clay on
the iron removal were investigated using a full factorial design. It is concluded that strain type has
the most significant effect on the iron removal. Also, the highest removal extent was 42.8% that
was achieved by using the strain isolated from pistachio shell at the pulp density of 20 g/l, when the
clay was added at the beginning of the experiments.
The results showed that for the experiments in which the clay was added in the first day of
cultivation, the average organic acids concentration (citric acid: 5.6 g/l, and oxalic acid: 4.54 g/l)
were higher in comparison to those experiments in which the clay was added in the third day (citric
acid: 5.25 g/l, and oxalic acid: 2.87).
Optimization of Kaolin Bioleaching by Aspergillus niger
Authors: Ranjbar M. , Aghaie E. , Hosseini M.R. , Pazouki Mohammad , Ghavipanjeh F.
Published: March 2009

In this paper, a central composite design was applied to optimize the bioleaching of iron
from a kaolin sample containing 2.2% iron impurity by Aspergillus niger isolated from pistachio
shell. The strains were inoculated into 500 ml flasks containing 100 ml media consisted of (g/l):
sucrose 120; NH4NO3 0.45; KH2PO4 0.1; MgSO4.7H2O 0.3; FeSO4.7H2O 10-4; ZnSO4.7H2O 25×10-
5. The effects of initial pH, sugar and spore concentrations on iron removal extent were investigated.
The two-level factorial design points were pH 2 and 5, sugar conc. 70 g/l and 130 g/l, spore conc.
9×107 and 35×107 spores/l. Also, the increase of dissolved iron, oxalic acid concentration, changes
in pH value, and sugar concentration were registered. Consequently, after 10 days, the iron
concentration of the best condition reached to 179.3 ppm that means 38.8% of the total iron content
is removed. Furthermore, the data analysis showed that all the factors are significant, and the iron
removal extent increases by increasing the initial pH to 4.4, sucrose content to 93.8 g/l, and spore
concentration to 305.5 spores/μl, but further increase in each factor value has negative effect on the
response.
Sulfur Product Layer in Sphalerite Biooxidation: Evidences for a Mechanism of Formation
Authors: Zapata Dioni Mabel , Márquez M.A. , Ossa D.M.H.
Published: March 2009

The sphalerite-pyrite oxidation by Acidithiobacillus ferrooxidans was studied to analyze how the formation of the elemental sulfur layers occurs around sphalerite grains. Two possible mechanisms of formation have been raised. One mechanism corresponds to the formation of sulfur pseudomorphs where, both, iron and zinc have been leached of the sphalerite, whereas compound sulfur is oxidized, in situ, to elemental sulfur, leaving an unreacted core of sphalerite that remains in the center. Another mechanism consists in the dissolution of iron, zinc and sulfur presents. When the attack by Fe3+ as by H+ broken the S-metal bonds, sulfur is then oxidized to a series of sulfur intermediate compounds. These compounds in solution then are oxidized to elemental sulfur, which precipitates on sphalerite grains.
Bioleaching of a Mixed Copper Dust Emanating from Copper Smelters
Authors: Bakhtiari F. , Atashi H. , Zivdar M. , Seied Baghery S.A.
Published: March 2009

Bioleaching of the copper flue dust emanating from smelters at Sarcheshmeh Copper
Complex has been studied. At the present, the dust is sent back to the smelter, which reduces its
efficiency. In this study, a continuous system including a feed tank and two-stage aerated stirred
tank bioreactors was established. Mixed mesophile bacteria with different amounts of the dust
containing 35% of copper mainly in the form of sulfide minerals were used. The effects of pulp
densities, residence times and temperatures on the final copper recovery and redox potential were
experienced. Despite the copper concentrates bioleaching, the process of dust bio-treating was net
acid consuming. Lower pulp densities resulted in a stable redox potential in both reactors. However,
increasing the pulp density to 7%, was created an unstable redox potential in the first bioreactor
especially at lower temperatures. Final copper recoveries were calculated for pulp densities of 2%,
4% and 7%, were 91.8%, 90.3% and 87.6% with residence times of 2.7, 4 and 6 days respectively.
The promising results indicated that bioleaching is a feasible process that can be applied to copper
flue dusts.
Environmental Toxicity Testing in the Risk Assessment of a Metal Contaminated Abandoned Mining Site in Hungary
Authors: Gruiz Katalin , Vaszita E. , Siki Z.
Published: March 2009

A three tiered, iterative Environmental Risk Assessment methodology, including preliminary
Qualitative Risk Assessment, Quantitative Hazard Assessment and Site Specific Quantitative
Risk Assessment, was established to assess the environmental risk of point and diffuse pollution
of mining origin at catchment scale [1]. The model site was an abandoned Pb and Zn sulphide
ore mine in Gyöngyösoroszi, Toka-valley, NE Hungary [2]. The Integrated Risk Model considers
the sources identified by the GIS-based (Geographical Information System) pollution map, the
transport routes shown by the GIS-based flow accumulation model and the receptors of different
land uses in the catchment. The site-specific quantitative risk was characterised by the Soil Testing
Triad [3]. The three elements of the Triad are: physico-chemical analyses of the soil and the contaminants,
the biological characterisation and ecotoxicity testing of the contaminated soil, measuring
the response of single species in laboratory bioassays, the natural response of the soil microflora
and plants or the dynamic response of the whole soil in microcosms. The Triad approach strongly
supports the characterisation of the site specific risk as well as the selection and planning of the
suitable remediation option.
Development and Potential Application of a Method for the Prediction and Assessment of the Seepage Water Quality
Authors: Glombitza F. , Pinka J. , Kutschke S. , Janneck E. , Kahnt R.
Published: March 2009

Piles and dumps in mining sites of lignite and ore mines very often generate drainage water with a low pH value. Furthermore they are contaminated with heavy metals or radionuclides. A comprehensive sustainable remediation and / or a water treatment process requires an assessment of the water quality and the determination of the future development thereof. This, in turn, requires prediction of the microbial processes which are responsible for the release of heavy metals and radionuclides. The paper deals with the demonstration of a suitable method for the prediction of these reactions and water quality.
Accumulation of Heavy Metals in Anaerobic Sludge and its Disposal by Landspreading
Authors: Arora A. , Saxena S.
Published: March 2009

Sludge, a natural, uncalled for byproduct of aerobic/ anaerobic biological digestion of organic matter present in wastewaters, also known as biosolids, is a thick, black and viscous substance comprising of dead and degraded microbial cells that digested the influents. This dead microbial material, accumulates on the bottom of anaerobic lagoons/ reactors, is organic in nature and rich in plant nutrients such as nitrogen, phosphorus and essential trace elements. It must be removed periodically. Therefore, the objective is to use the sludge as a fertilizer on agricultural land. It is an environmentally acceptable and economical method of sludge disposal. The application of organic wastes to farmland has increased over the years as it contributes to the preservation of the environment and results in an improvement of chemical, biochemical and physical properties of soil, although there is an increased risk of soil and ground water being contaminated by pollutants. Sewage sludge may contain heavy metals whose presence in soil may reduce enzyme activities and affect microbial communities in soil. They accumulate in soil and are taken up by crop plants thus posing health hazard. The study was conducted to characterize anaerobic sludge and quantify the concentration of heavy metals in it, to determine the suitability of the sludge as fertilizer for crops. Physicochemical and biochemical analyses showed that anaerobic sludge produced at Upflow Anaerobic Sludge Blanket (UASB) sewage treatment plant at Faridabad (an industrial town), Haryana, India, contained total organic C 15.714 percent, total Kjeldahl N 0.795 percent, available P 8 3g g-1and heavy metals Zn 1500 3g g-1, Ni 226 3g g-1, Fe 3000 3g g-1 and high activity of enzymes like alkaline phosphatase and dehydrogenase in the sludge. These enzymes are important for soil fertility and nutrient cycling. The toxic heavy metals have been accumulated by bacteria from sewage waters. The ideal C/N ratio, P and enzyme activities show its suitability as fertilizer but presence of heavy metals is a matter of concern. Therefore its application as crop fertilizer or onto land has to be carefully managed.
Environmental Risk Management of an Abandoned Mining Site in Hungary
Authors: Gruiz Katalin , Vaszita E. , Siki Z. , Feigl Viktória
Published: March 2009

An Environmental Risk Management methodology was developed for the Toka catchment area, an abandoned base metal mining site in Gyöngyösoroszi, Hungary. The postmining activities on the Hungarian site require the management of both the point and diffuse sources. The mobile Cd and Zn content of the mine waste, soil and sediment transported by water pose the highest environmental risk in the area. The approach is „GIS based” (Geographical Information System) and „catchment scale”, using a three tiered, iterative Environmental Risk Assessment methodology. The model parameters of the metal transport were determined in leaching microcosms. The risk reduction concept aims at reducing the runoff water quantity and contamination by removal of the point sources and chemical & phytostabilisation of the residual and diffuse pollution. The planning of the field application was based on the results of the stabilisation microcosms.
Development of a Biotechnological Process for Reprocessing Flotation Tailings from Almalyk Mining and Metallurgical Complex, Rep. of Uzbekistan
Authors: Sagdieva M.G. , Borminskiy S.I. , Sanakulov K.S. , Vasilenok O.P.
Published: March 2009

Trial tests on biotechnology of flotation tailings processing from copper-concentrating factory at Almalyk Mining and Metallurgical Complex are carried out. Suitability of flotation tailings to processing by a method of heap bacterial leaching is experimentally determined. It is shown, that extraction of copper from flotation tailings makes 56 %, biooxidation of chalcopyrite makes more than 62 %, and pyrite - 87-92 %.
Development of a Novel Biological System for Removing Manganese from Contaminated Waters
Authors: Mariner Richard , Johnson D. Barrie , Hallberg Kevin B.
Published: March 2009

Soluble manganese (Mn(II)) can cause nuisance and occasionally toxicity problems, both in surface and ground waters and in domestic water supplies. Many mine drainage waters contain highly elevated concentrations (often >100 mg l-1). Current systems for remediating mine waters, although effective for other metals, are often inefficient at removing manganese. This paper describes the development of self-sustaining, low-cost bioreactors that can be used in situ for passive removal of manganese from mine waters and other contaminated water courses of pH >4. A prototype bioreactor, set-up using Mn(IV)-coated pebbles from a fresh-water stream, was tested over one year and shown to be effective in removing Mn(II) from 10 to <0.25 mg l-1. Two species of fungi and one bacterial species were isolated from this system as Mn(II)-oxidizers. The fungi were identified as belonging to the order Pleosporales (Ascomycetes), and one was related (98 % 18S rRNA gene sequence identity) to a known Mn(II)-oxidising fungus. The bacterial isolate was closely related to the α-proteobacterium, Bosea thiooxidans. T-RFLP analysis showed that one or both of the fungal isolates were the dominant eukaryotes in the bioreactor community.
Integrated System to Biological Solubilization and Precipitation of Heavy Metals
Authors: Cabrera G. , Gómez José Manuel , Cantero Domingo
Published: March 2009

The work consists on the study of a sulphur–oxidizing bacteria (At. thiooxidans) immobilisation over polyurethane foam and the integration of two continuous processes: the solubilization of heavy metals by acidic medium generated by sulphur-oxidizing bacteria and the subsequent precipitation of metals as sulphides with H2S biologically generated by sulphate-reducing bacteria (Desulfovibrio sp). At. thiooxidans was satisfactory immobilised over polyurethane foam and added to a column reactor. Acidic medium generated was added to a column with 50 g of an artificial contaminated sand (85 mg Cr(III), 20 mg Ni(II), 200 mg Zn(II)). The effluent of this step was collected in a reservoir tank, in which H2S from sulphate-reducing reactor was included to carry out the precipitation of metals. After 2.4 l of acid medium was passed through the column, it was observed that 14.6% of Cr(III), 26.7% of Ni(II) and 90.5% of Zn(II) were solubilized. The leachate was treated with 2.2 l of reducing medium, and 2.2% Cr(III),54% Ni(II) and 28% Zn(II) were precipitated.
Biohydrometallurgy – This Microbiologist´s Perspective
Authors: Brierley James A.
Published: March 2009

My perceptions of the biohydrometallurgical field span four decades and stem from being a professional microbiologist conducting academic research and research for process development and applications. My experiences have given me an appreciation for knowledge gained through fundamental research and the transfer of this knowledge to development of commercial scale applications of microbial processes. The symposia series for international activities in biohydrometallurgy has been a major factor in advancing knowledge and applications for microbial bioleach systems. The first international biohydrometallurgy meeting was held in Braunschweig, Germany in 1977. This was the predecessor for the International Biohydrometallurgy Symposia. As evident from the Symposia, advances in development and applications of biohydrometallurgy technologies follow an evolutionary, rather than revolutionary progression from demonstration of knowledge at the laboratory scale to engineering commercial plants.
Talvivaara Black Schist Bioheapleaching Demonstration Plant
Authors: Riekkola-Vanhanen Marja
Published: March 2009

Talvivaara complex multi-metal black schist deposit in Sotkamo, Finland, is the largest
known sulfide nickel deposit in Europe with 340 million ton of classified resources. The mine can
be operated for a minimum of 25 years with an annual nickel output of over 30 000 ton, which is
about 2,5 % of the global production of primary nickel. Significant amounts of zinc, copper and
cobalt can also be produced. In summer 2005, a 50 000 ton demonstration plant was constructed to
the mine site. A representative ore sample was mined, crushed to 80 % -8 mm, agglomerated and
built to a two-part heap (8 m high, 50m times 80 m). Irrigation of the heap was started in August
2005. The pilot heap was inoculated with indigenous bacteria collected from the site. The amount
of bacteria in the pregnant leaching solution has been in the range of 106 – 108 cells/ml. The
bacteria involved are mesophilic and thermophilic ones. The start-up of the solution flow resulted
soon in elevated temperatures of over 50 0C in the pregnant leaching solution. The rise is due to the
oxidation of the large quantity of pyrrhotite and pyrite in the ore. The elevated temperatures have
also been maintained over the boreal winter conditions. Metal recovery was started in November
2005. At the end of the year 2006 94 % of Ni, 83 % of Zn, 3 % of Cu and 14 % of Co have been
recovered. The demonstration plant is still running. The study has proven that Talvivaara black
schist ore is well suited for bioheapleaching. Building of the mine will start in spring 2007,
bioheapleaching in summer 2008 and the metal recovery plant in autumn 2008, if everything
proceeds according to the plans.
Enhancing Reductive Processes by Autochthonic Sulphate-Reducing Bacteria in Lignite Overburden Dumps
Authors: Simon A. , Hoth Nils , Dilbat M.
Published: March 2009

NA-processes can be enhanced for lignite overburden dumps, using dicarboxylic acid as
a feasible substrate for autochthonic sulphate reducing bacteria. Sulphate reduction with
simultaneous FeS/FeS2-precipitation occurs and immobilises SO4
2-, H+ and heavy metals connected
with a decrease of the acidity. The used LC-OCD, HP/LC, isotopic and other chemical analyses
substantiate sulphate reduction under technical enhanced conditions too.
Effect of LPS Removal on Electrophoretic Softness of Acidithiobacillus ferrooxidans Cells
Authors: Chandraprabha M.N. , Modak Jayant M. , Natarajan K.A.
Published: March 2009

Applicability of Ohshima’s soft-particle model to evaluate the surface potential of Acidithiobacillus ferrooxidans cells is discussed here. The electrokinetic properties were examined by electrophoretic mobility measurements and analyzed using the soft particle electrophoresis theory. As the ionic concentration increased, the mobility of the bacterial cells converged to nonzero values suggesting that the particles exhibited typical soft-particle characteristics. Also, cell surface potentials based on soft-particle theory were lower than those estimated using the conventional Smoluchowski theory. Effect of removal of LPS from the cell surface on surface softness and charge density are investigated and discussed.
Microbial Ecology of Leptospirillum spp. in Río Tinto, a Model of Interest to Biohydrometallurgy
Authors: García-Moyano A. , González-Toril E. , Moreno-Paz M. , Parro V. , Amils R.
Published: March 2009

Members of Leptospirillum genus have emerged not only as one of the most representative bacteria in the Río Tinto ecosystem, but also in other acidic environments (AMD), and in biohydrometallurgical operations. The main objective of this work was to study the role of chemolithoautotrophic bacteria of the genus Leptospirillum in the Río Tinto iron cycle (an extreme acidic environment, characterized by its constant low pH) to better understand and control industrial biohydrometallurgical processes. Different strains of Leptospirillum were isolated from the Río Tinto basin and physiologically and genetically characterized. Certain metabolic capabilities, such as pyrite leaching, iron oxidation and nitrogen fixation, were determined for each strain. Complementary molecular ecology techniques (FISH, CARD-FISH and cloning) were used to study the microbial diversity and the distribution of leptospirilli along the iron gradient in the different phases of Río Tinto: water column, anaerobic sediments and biofilms.
The Bioshale Project: Search for a Sustainable Way of Exploiting Black Shale Ores Using Biotechnology
Authors: D'Hugues P. , Grotowski A. , Luszczkiewicz A. , Sadowski Zygmunt , Farbiszewska T. , Sklodowska Aleksandra , Loukola-Ruskeeniemi K. , Langwaldt Jörg , Palma J. , Norris Paul R. , Glombitza F. , Groudev Stoyan N. , Pasava J. , Johnson D. Barrie
Published: March 2009

The Bioshale project, involving 13 partners throughout Europe, is co-funded by the
European Commission under the FP6 program. The main objective of this project (which started in
October 2004) is to identify and develop innovative biotechnological processes for ‘’eco-efficient’’
exploitation of metal-rich, black shale ores. Three extensive deposits have been selected for R&D
actions. These are: (i) a site (in Talvivaara, Finland) that, at the outset of the project, had not been
exploited; (ii) a deposit (in Lubin, Poland) that is currently being actively mined, and (iii) a third
site (in Mansfeld, Germany) where the ore had been actively mined in the past, but which is no
longer exploited. The black shale ores contain base (e.g. copper and nickel), precious (principally
silver) and PGM metals, but also high contents of organic matter that potentially handicap metal
recovery by conventional techniques.
The main technical aspects of the work plan can be summarized as: (i) evaluation of the geological
resources and selection of metal-bearing components; (ii) selection of biological consortia to be
tested; (iii) assessment of bioprocessing routes, including hydrometallurgical processing; (iv)
techno-economic evaluation of new processes from mining to metal recovery including social, and
(v) assessing the environmental impacts of biotechnological compared to conventional processing
of the ores. An overview of the main results obtained to date are presented, with special emphasis
on the development of bioleaching technologies for metal recovery that can be applied to multielement
concentrates and black shale ores.
Bacterial Oxidation of Elemental Sulfur: Changes in Oxidation Kinetics
Authors: Mandl Martin , Pokorna Blanka , Gavlasova Pavla
Published: March 2009

We investigated the oxidation of elemental sulfur in resting cells of Acidithiobacillus
ferrooxidans in order to optimize the substrate for sulfur oxidation and to explore oxidation
kinetics. We showed that although pH and temperature had no significant effect on the apparent
Michaelis constant, cell concentration increased it.
Mobilization of Silver, Gold, and Platinum from Solid Materials by HCN-Forming Microorganisms
Authors: Brandl Helmut , Lehmann Stefan , Faramarzi Mohammad A.
Published: March 2009

Cyanogenic Chromobacterium violaceum, Pseudomonas fluorescens, and P. plecoglossicida were able to mobilize silver, gold and platinum when grown in the presence of various metal-containing solids such as powdered platinum, platinum-containing automobile catalytic converters, powdered silver, or gold-containing electronic scrap. Five percent of silver was mobilized from powdered jewelry scrap as dicyanoargentate after one day, although 96% was mobilized when non-biological cyanide leaching was applied. Dicyanoargentate proved to inhibit growth at concentrations >20 mg/L. Gold was microbially solubilized from electronic scrap (shredded printed circuit boards). Maximum dicyanoaurate concentration corresponded to a 68.5% dissolution of the total gold added. Additionally, cyanide-complexed copper was detected during treatment of electronic scrap due to its high copper content of approximately 100 g/kg scrap. Small amounts of platinum were mobilized from pure platinum powder after 10 days. The process proved to be very slow. In summary, all findings demonstrate the potential of microbial mobilization of metals as cyanide complex from solid materials and represent a novel type of microbial metal mobilization which might find industrial application.
The Use of CARD-FISH to Evaluate the Quantitative Microbial Ecology Involved in the Continuous Bioleaching of a Cobaltiferrous Pyrite
Authors: Díaz E. , González-Toril E. , Joulian Catherine , Amils R.
Published: March 2009

Catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) is a powerful method with a growing number of applications in the quantitative evaluation of microbial populations of complex ecosystems. CARD-FISH is an improvement over traditional fluorescence in situ hybridization (FISH) especially suitable for aquatic habitats with small, slow growing, or starving bacteria, in which the signal intensities of hybridized cells is frequently below detection limits or lost in high fluorescence background of dense mineral matrixes. In this work we report the development of protocols and probes for the identification and quantification of the microorganisms involved in the continuous bioleaching of a cobaltiferrous concentrate using a four tank-leaching reactor operated by BRGM. After steady state was reached, samples were taken to identify and quantify the microorganisms present in the each of the tanks used in the process.
Development of a Tank Bioleaching Process for the Treatment of Complex Cu-Polymetallic Concentrates
Authors: Gericke Mariekie , Muller Heinrich H. , van Staden P.J. , Pinches A.
Published: March 2009

The focus of this paper is on the development of a bioleaching process for the treatment
of complex polymetallic concentrates, containing chalcopyrite, sphalerite, galena and silver, using a
moderately thermophilic culture operating around 45°C. Initial development R&D work and
subsequent research for process improvements carried out in bench-scale piloting facilities will be
discussed.
Characterization of New Iron Oxidizing Bacteria from an Acid Mine Water Treatment Plant
Authors: Hedrich Sabrina , Heinzel Elke , Seifert Jana , Hallberg Kevin B. , Johnson D. Barrie , Schlömann Michael
Published: March 2009

In the Lusatia area a pilot plant for the treatment of acidic mine waters by microbial iron
oxidation and a concomitant iron hydroxysulfate precipitation is operated.
Molecular based studies of acidic waters from this iron hydroxysulfate producing pilot plant
revealed the presence of 16S rRNA gene sequences from undescribed iron-oxidizing bacteria. Most
of these were related to autotrophic Betaproteobacteria (see Heinzel et al. IBS 2007, poster number
98).
For cultivating different iron-oxidizing bacteria water samples from this pilot plant were directly
plated on various solid media. Double-layer plates were used, with a heterotrophic Acidiphiliumstrain
in the underlayer, because of the high sensitivity of autotrophic bacteria towards organic
substances. The media contained different iron-substrates with and without organic carbon sources.
Colonies appeared at the latest after three weeks and they were encrusted with ferric iron. The
phylogeny of the isolated strains was determined and the physiological requirements, like
temperature, pH optima, preferred carbon source and iron concentrations, were analyzed. Many
isolates which were related to Acidithiobacillus ferrooxidans strains could be cultivated, as well as
an isolate related to the genus Thiomonas and one isolate related to a Ferribacter polymyxa species.
The Thiomonas-like isolate showed best growth in media containing tryptone soya broth, sodium
thiosulfate and ferrous sulfate at pH 2.5 and 30°C. The other Betaproteobacterium grew on ferrous
sulfate medium at pH 2.5 between 16 and 37°C. In liquid culture experiments the cells of both
isolates were attached to the iron minerals built in the medium. These physiological characteristics
of the isolates helped to vary parameters in the pilot plant to optimize the process of iron oxidation
and improved waste water remediation.
Elemental Sulfur Oxidation in Acidiphilium spp.
Authors: Rohwerder Thore , Janosch Claudia , Sand Wolfgang
Published: March 2009

The alpha-proteobacterial genus Acidiphilium consists of several acidophilic species,
generally known as a part of the mesophilc microbial flora of leaching biotopes. All of them can
grow chemoorganotrophically on carbon sources like sugars and many express additional
photosynthetic pigments. Thus far, only Ap. acidophilum is known to be capable of
chemolithotrophic growth on elemental sulfur oxidation. The oxidation potential of inorganic sulfur
species by the other strictly heterotrophic species has not yet been thoroughly investigated. Here,
we demonstrate the unequivocal evidence of inorganic sulfur compound oxidation by strains of Ap.
cryptum and other Acidiphilium species. Evolutionary and biochemical aspects of this new feature
among the heterotrophic Acidiphilium spp. are discussed. This finding will possibly help to solve
the long-standing question about the biochemical nature of elemental sulfur oxidation in mesophilic
leaching bacteria.
A Novel Hydrogenation and Hydrogenolysis Catalyst Using Palladized Biomass of Gram-negative and Gram-positive Bacteria
Authors: Creamer N.J. , Mikheenko I.P. , Deplanche K. , Yong P. , Wood J. , Pollmann K. , Selenska-Pobell S. , Macaskie Lynne E.
Published: March 2009

Palladized biomass of typical Gram negative bacteria (Desulfovibrio desulfuricans and Escherichia coli) is well documented as a potentially useful catalyst for reduction of metallic species such as Cr(VI). This bionanocatalyst can be sourced from Pd-waste and scrap leachates via biocrystallization. A major industrial application of precious metal catalysts is in hydrogenation and hydrogenolysis reactions whereby, respectively, H is added across unsaturated bonds and halogen substituents can be removed from aromatic rings. Gram positive bacteria have not been evaluated previously as potential supported Pd-bionanocatalysts. We compare the activity of ‘Bio-Pd(0)’ supported on the fundamentally different Gram negative (Desulfovibrio) and Gram positive (Bacillus) bacterial surfaces, and evaluate the activity of the two types of ‘Bio-Pd(0)‘ in a standard reference reaction, the hydrogenation of itaconic acid, against a commercially available catalyst (5% Pd on carbon). The results show that the bionanocatalysts have a similar activity to the commercial material and biomanufacturing from waste sources may be an economic alternative to conventional processing for catalyst production as precious metal prices continue to rise.
Waste Biomass Characterization and Metal-Biomass Interactions Study
Authors: Svecova Lenka , Kubal Martin , Guibal Eric
Published: March 2009

Our previous study has demonstrated that industrial waste biomasses of Penicillium
oxalicum var. Armeniaca and Tolypocladium sp., could be used for biosorption of Cd, Pb, Hg and
Cr(VI). The objective of the present study was to investigate the biosorption mechanisms, while
using FT-IR spectroscopy and SEM technique. SEM microscopic observations (coupled with EDX
analysis) confirmed the presence of the target metals on the biosorbents surface. Carboxyl groups
were identified by FT-IR spectra analysis on the surface of Tolypocladium sample, while the
alkaline treated Penicillium sample was characterized by the presence of amine groups. It was
proved that the metal biosorption slightly modified the FT-IR spectra, while the mentioned
functional groups were involved in the uptake mechanism (chelation on nitrogen containing groups
and ion exchange on carboxyl groups).
Waste Fungal Biomass for Mercury Biosorption – Column Studies
Authors: Svecova Lenka , Kubal Martin , Guibal Eric
Published: March 2009

Granulated Tolypocladium biomass (industrial waste) was tested as mercury biosorbent
in continuous mode (fixed bed column). Supplied material contained approx. 70% of fungal
biomass and 30% of inert material (diatomaceous earth). Prior to column experiments, batch
sorption was also performed. The results of batch experiments were compared to our previous
results obtained for powdered biomass (100% biomass material) and an important drop of sorption
capacity was observed. For column experiments, the bed height and flow rate were kept constant
and the influence of both initial mercury concentration and bead size was investigated. The Adams
Bohart, the Thomas and the Yoon and Nelson models were used for the characterization of
breakthrough curves.
Removal of Copper and Uranium from Contaminated Waters in Biosorption Columns
Authors: Steudel K. , Horak G. , Willscher Sabine , Pompe W. , Werner Peter
Published: March 2009

It was the aim of this work to investigate the sorption characteristics of the Biocer material that consists of cells of Bacillus sphaericus that are immobilised on a ceramic carrier material, performing column experiments with model waters and real mine drainage waters from a U remediation site in East Germany. In column experiments a nearly quantitative sorption of Cu2+ was performed from solutions of different Cu2+ concentrations and at different flow rates. The desorption of the Cu2+ in the columns was nearly quantitative in a very short time. The columns could be regenerated 16 times without a substantial loss of the sorption capacity of the material. In experiments with U using real drainage waters, a specific U sorption capacity of 2.34 mg/g was determined. By variation of the experimental parameters, the long-term stability and sorption properties of the Biocer columns can be substantially improved.
A Novel Fuel Cell Catalyst for Clean Energy Production Based on a Bionanocatalyst
Authors: Yong P. , Mikheenko I.P. , Macaskie Lynne E.
Published: March 2009

Nano-scale palladium was bio-manufactured via enzymatically-mediated deposition of Pd(II) from solution. The bio-accumulated metal palladium crystals were processed and applied onto carbon paper and tested as anodes in a proton exchange membrane (PEM) fuel cell for power production. Up to 85% and 31% of the maximum power generation was achieved by Bio-Pd catalysts made using two strains of bacteria, compared to commercial fuel cell grade Pt catalyst. Therefore, it is feasible to use bio-synthesized catalysts in fuel cells for electricity production.
Thermomechanical Processing of some Heavy Alloys from the System W-Ni-Fe through Rotary Forging
Authors: Mureşan Radu , Pavel Codruta , Salomie Dana
Published: March 2009

The goal of present work was to study the possibility to produce bars from heavy alloys
based tungsten through rotary forging. For the experiment there were selected two compositions
from the system W-Ni-Fe (90, respectively 93 %W/wt., Ni/Fe ratio = 7/3). From the two
compositions there were prepared samples by conventional route of liquid phase sintering, followed
by thermal treatment in a neutral atmosphere (N2, Ar) and by rotary forging with different reduction
degree.
The Study of Fatigue Behaviour at the Contact of some Sintered Materials from Powder Based on Iron
Authors: Brânduşan Liviu , Arghir George
Published: March 2009

The analysis of a large range of sintered parts shows the fact, they are strained at contact
fatigue, in most of the cases. The Hertzian pressure, at which materials in contact are subjected,
establishes the appearance of variable stress, which records a maximum at some depth under the
contact surface. In the case of sintered materials this stress variation conducts to a faster degradation
of strained surface than in the case of compact materials. This is because the stress variation
establishes a critical state at the level of stress concentrators, generated by pores, standing in
material structure, leading to formation of some cracks which may propagate at the level intergranular
necks, producing removal for some particles of material. The accomplished research on
sintered materials, having different chemical compositions, revealed the fact, at the beginning, that
the materials undergo a cold hardening, indicated by a hardness increasing, followed by some cracks
generating, accompanied by their extension and material removal. This process develops in the
same mode for all investigated materials, but with different intensity.
Mathematical Model of the Sintering Process of Iron-Copper Bearings
Authors: Teișanu Cristina , Gheorghe Stefan , Ciupitu Ion
Published: March 2009

The most important features of the self-lubricating bearings are the antifriction properties
such as friction coefficient and wear resistence and some mechanical properties such as hardness,
tensile strength and radial crushing strength. In order to improve these properties new antifriction
materials based on iron-copper powders with several additional components (tin, lead and
molybdenum disulphide) have been developed by PM techniques. To find the optimal relationship
between chemical compositions, antifriction and mechanical properties, in this paper a
mathematical model of the sintering process is developed, which highlighted the accordance of the
model with data by regression analysis. For the statistical processing of the experimental data the
VH5 hardness values of the studied materials were considered. The development of mathematical
model includes the enunciation of the model, the establishment of the performance function
(optimization) and the establishment of the model equations and verifying. The accordance of the
model with experimental data has been highlighted by regression analysis
On the Mechanical and Physical Properties of Recycled Polymer Matrix Composites Reinforced with Cooper Powder
Authors: Chifor Victoria , Orban Radu L. , Jumate Nicolae
Published: March 2009

The influence of cooper powder as reinforcing phase on the main mechanical and
physical properties of recycled polyethylene matrix composites has been investigated. The obtained
elastic modulus increases up to the upper adopted reinforcing level (∼10 [vol. %]), while elongation
and fracture energy decrease. The UTS values remain quite constant within the reinforcing content
interval. Electrical resistivity proved to depend, to a great extent, on the reinforcing particle
distribution inside the polymer matrix. It has a sudden drop when a continuous electrical conductive
path is formed at a critical volume fraction of metal particles. At a lower content, instead, it slowly
decreases as reinforcing powder content increases. Both the mechanical properties and values for
electrical resistivity are similar to those published for polymers obtained directly from monomers.
Researches on the Pressing and Foaming Conditions on the Main Properties of Al Foams
Authors: Canta Traian , Frunză Dan , Covaciu Manuela
Published: March 2009

The present paper presents experimental results on Al foam produced by powder
metallurgy method. Their lightweight property makes them attractive for the cores of structural
sandwich panel in products ranging from sport equipment to lightweight building panels. The
process of metallic foam manufacture as well as the testing methods used for the characterization of
their physical, mechanical and chemical properties will be exposed.
Microstructure Prediction in Aluminium Extrusion by Means of FEM Simulation
Authors: Donati Lorenzo , Tomesani Luca , Ceschini Lorella , Boromei Iuri
Published: March 2009

An original inverse extrusion test was developed in order to study the microstructural
evolution in the plastic deformation of 6060 and 6082 aluminium alloys. Sample billets were
extracted from commercial logs and subjected to plastic deformation in an inverse extrusion
process, particularly aimed at producing different strain and strain rate conditions at representative
positions within the billet section. Different experiments were performed at various temperatures
and strain rates. The particular thermo-mechanical history of each point in different experiments
was then reconstructed by FEM analysis. The cups were sectioned and the microstructure was
analysed at some representative locations, to relate it to the FEM simulation results.
Simulation of „Yalle Body” Profile Extrusion
Authors: Ghiban Nicolae
Published: March 2009

Present paper presents the results concerning the modeling process of extrusion of a
profile type “Yalle body”. COSMOS soft was used in order to simulate the extrusion process. 3D
model contains elements type SOLID, witch simulates the nonlinear behavior in the field of elasticplastic
domain. The constitutive equation of Iliusin and Dracker-Prager relation and Von Misses
criterion were used in simulation. The three dimensions model contains 1504 nods and 1750
elements in two different position of the die (optimum position and “out of optimum position”). For
both of die positions were presented variation of equivalent total stresses, tangential stresses in
different steps (1st step, critical step, and 20th step, by dividing the whole extrusion process in equal
steps).
The Mathematical Model of Abrasive Waterjet Milling Process
Authors: Ciupan Cornel , Pop A. , Morar Liviu
Published: March 2009

The paper presents the mathematical model of abrasive waterjet milling process. Based on analysis of existing models the authors realize a new mathematical model, considering some simplifying hypothesis. This model uses output data from model [1] and determines the advance speed, the consumption of the abrasive and the productivity of the process. To establish the productivity of the process and the advance speed we’ll use the “energy preservation” model. This model takes in account the material characteristics. The mathematical model has been solved numerical and the results have been interpreted.
Investigation of Acicular Ferrite Structure and Properties of C-Mn-Al-Ti-N Steels
Authors: Uzlov O. , Malchere A. , Bolshakov V.I. , Esnouf Claude
Published: March 2009

Low carbon-manganese wrought steels with addition of Ti-Al-N have been treated in
order to obtain acicular ferrite structure. The microstructure of fine acicular ferrite nucleated
intragranularly on Ti(C,N)+AlN and Ti(C,N)+AlN+MeS inclusions has showed high strength and
toughness at low temperatures.
Structural Morphology Transformations by Vacuum Oven Brazed Joints with Amorphous Alloys
Authors: Codrean Cosmin , Mitelea Ion , Şerban Viorel Aurel
Published: March 2009

Tapes of stainless steels were brazed inside a vacuum oven using amorphous or
quasi amorphous alloy based on Ni-Cr. By means of different investigation methods (optical
microscopy, X ray diffraction) there were emphasized the structural morphology transformations
inside brazed joints, revealing the role of process parameters on obtained structure.
Local Thermomechanical Treatment Regime for Friction Welded Joints from Dissimilar Nitrided-QT Steels
Authors: Mitelea Ion , Mosila A. , Radu B.
Published: March 2009

In this paper is revealed the structural transformations and diffusion processes that take
place as a result of the local thermo-mechanical treatment regimes specific to friction welding of
nitrided and not nitrided quenched and tempered steels. To obtain welded joints with good
mechanical properties it is necessary to remove the nitrided layer from the contact surfaces.