bluuebunny/crossref_metadata_2025 huggingface dataset:
Mould Machining of Structural Surface Based on Liquid-Solid Two Phase Abrasive Flow
Authors: Ji Shi Ming , Gong Bin , Yuan Qiao Ling , Pan Y. , Zhang Li
Published: September 2009

Mould manufacturing involves a large number of groove, slot, hole, prism, pyramid and narrow special-shaped surface called structural surface. Such particularity of these structural surface has caused restrict to the exposure between the grinding, polishing electrode tools and the covered processing surface. So General polishing machining can not be used for such precision surface processing. At present, In mould field, the requirement of the structural surface increasingly need high quality, For example, precision injection mould, not only the die face of the injection mould but the injection mould shoot also has high roughness demands. As the structural surface machining is difficult to use contact-machining tools (such as polishing or grinding), even if the manual operation is also very difficult (because manual operation also needs the auxiliary tools).So the precision processing of the mould structural surface has become an urgent unresolved problem. But now it still lack of intensive research. In order to solve the problem, we raise a new tool-free principle based on the liquid-solid two phase abrasive flow machining.
Surface Modification of Diamond to Improve Machining Properties of Ultraviolet-Curing Wire Saw
Authors: Peng Wei , Liu F.Q. , Yao C.Y.
Published: September 2009

The interfacial bonding strength between ultraviolet-curing resin and diamond is a key factor affecting tool properties in manufacturing of ultraviolet-curing wire saw. Therefore, in this paper, the application of surface-modified diamond coated metal was studied in ultraviolet-curing wire saw aim at retention problem of diamond in bond. Effects of surface-modified diamond were evaluated according to model of tensile test. Furthermore, retention mechanism of diamond was analyzed according to bond theory. The experimental results prove that the machining properties and service life of ultraviolet-curing wire saw can be improved by surface modification of diamond.
Lapping of WC-Co Cemented Carbide Ball by Eccentric Dual-Rotating V-Groove Lapping Mode
Authors: Yuan Ju Long , Tang K.F. , Wang Zhi Wei , Lv Bing Hai , He X.H.
Published: September 2009

To study the lapping process and sphere-shaping mechanism of WC-Co cemented carbide ball under eccentric dual-rotating (EDR) V-groove lapping mode, the research center designs EDR V-groove lapping machine. This paper analyses sphericity of WC-Co cemented carbide balls after the lapping. During the lapping process, the diameter variation is measured every one hour. The diameter of ball is usually reduced 0.05mm every hour, which is more than the dual rotating plates(DRP) lapping mode, and the experiment is totally done 9 hours, the error of sphericity can be controlled around 0.005mm in the last, so the EDR V-groove lapping mode is more suitable for lapping of the WC-Co cemented carbide ball in roughness and semi-finishing process. In order to compare the material removal rate between DRP lapping mode and EDR V-groove lapping mode, the balls are also lapped under DRP lapping mode.
Research of the Virtual Prototyping and Simulating on Ultra-Precision Double-Sided Planar Polishing Machine
Authors: Zhao Yan Wei , Du J.F. , Wen Si Wei , Gui Yuan Kun
Published: September 2009

Based on virtual prototyping technology, dynamic simulation of PE-1 type ultra-precision double-sided polishing machine and its technologic parameter optimization was studied. Through the simulation of virtual prototype, which was built in ADAMS, the polishing process was analyzed. Firstly, the simulation of polishing process shows that the ratio of rotation and revolution angular speed is inversely proportional to input speed ratio of planetary system. Secondly, the simulation of movement route shows that points along the same radius have similar route style considering the same input speed ratio of planetary system. Thirdly, the optimization of material removal non-uniformity shows that the higher speed makes for higher removal quality, the speed of solar gear and gear ring is opposite when the optimum value reached. At last, the maximum removal rate was achieved on the condition of same press and speed of plate, and corresponding solar gear speed and gear ring speed were gained.
Influences of End Surface Angle of Workpiece on Burr Formation in High Speed Machining
Authors: Shen Qin Xi , Wang Gui Cheng , Qu Hai Jun , Zhu Yun Ming
Published: September 2009

The end surface angle of workpece is one of key factors that affect burr sizes and shapes. In this paper, the burr formation process of different end surface angle is simulated with elastic plastic nonlinear element method based on ABAQUS. The influence of end surface angle of workpiece on burr formation processes in high-speed machining 2024 Aluminum alloy is analyzed. The influence of end surface angle on burr sizes and shapes is studied based on equivalent shear strain and negative shear angle. The results have investigated the mechanisms of burr formation fundamentally, which is the basis of burr minimization.
Research on Dynamic Optimization and Simulation of Camshaft Grinding Process
Authors: Deng Zhao Hui , Wang J. , Cao De Fang , Liu Wei , Wang Lu Lin
Published: September 2009

Camshaft is one of the key components of vehicle engines. In this paper, an independent optimization and simulation module for camshaft grinding was developed. First an optimization algorithm based on the least square method was proposed according to the constant linear velocity mathematical model of the camshaft. The algorithm can be used to smooth speed curves and improve machining efficiency and accuracy. Then the real time dynamic simulation of the camshaft grinding process was finished to perform the machining status according to the optimized motion path of the process system components.
Study on Parameters Optimization in Ultra-Precise Processing of Germanium Substrate
Authors: Lv Xun , Yuan Ju Long , Wang Yang Yu , Deng Qian Fa
Published: September 2009

To improve efficiency in ultra-precision lapping germanium (Ge) substrate, a new ultra-precise process technology is introduced in this paper. Two steps ultra-precise process were semi bonded abrasive lapping in rough machining, and CMP process in finish machining. A good surface quality workpiece was obtained in semi bonded abrasive lapping process efficiently. Several machining parameters were compared and applied. After CMP process, the mirror-like surface of Ge substrate was obtained.
Structural Design Method of High Speed Face Milling Cutter Based on Theory of Axiomatic Design
Authors: Jiang Bin , Zheng Min Li , Xu Wen Chao , Jiang L.
Published: September 2009

Using grey system theory in axiomatic design of high speed face milling cutter, the structural design method of cutter was investigated. The problem of parameter interaction and function coupling in axiomatic design of cutter was solved using the analysis method of grey cluster, and realized the reconstruction of design matrix and collaborative design planning. Results show that there is not design loop which exists in the development of high speed milling cutter, the effects of simplifying design process, shortening design cycle and improving collaborative design are validated in development of high speed face milling cutter. Results of experiments indicate that cutting vibration of high speed face milling cutter using structural design method is depressed, the cutters with higher safety and cutting stability, and their cutting performance have met the requirement of high speed milling.
Study on Module Encoding Method Oriented Product Configuration Design
Authors: Lu Cong Da , Chen X.H. , Jiang Shao Fei , Chai Guo Zhong
Published: September 2009

For the successful realization of product configuration design (PCD) in the condition of mass customization mode, the module encoding methods are studied. By analyzing the product structure model and the process of computer-aided PCD, all related information which is required for the module is decided. This paper proposes a scientific module encoding method suitable for PCD. It describes the geometric features of the modules, the interface relationships and the affiliations between modules. Further more, it introduces additional attribute codes used to evaluate product configuration. By this way the product information can be fully expressed in order to improve the efficiency of PCD.
Static Analysis for a Novel 6-(P-2P-S) Parallel Robot
Authors: Zhang D.F. , Gao Feng
Published: September 2009

A novel 6-(P-2P-S) parallel robot is put forward. With the characters of some movement decoupling on the orthogonal pose, the robot can be used as the macro manipulator of the macro/micro dual driven robots. The macro manipulator as a high-precision positioning device, it is significant for the practical application and drive train design to research statics. First, the force Jacobian matrix is deduced, which is related to the orientation parameters. Then based on the Jacobian matrix singular value decomposed characteristic, the static force transmission evaluation indicators Kf and Km are defined. Finally, considering structure constraints and parameters, the distribution of evaluation indicators in the orientation workspace is drawn, which provide the theoretical base for the design and applications of the robot. Because of the characters of simple structure, high carrying capacity, less motion inertia, good manufacturability, the 6-(P-2P-S) parallel macro manipulator has been designed.
Double-Workshop Plan Model of Mixed Chlor-Alkali Production Process
Authors: Dai Xin Hua , Wang Wan Liang , Zhao Yan Wei , Teng H.X.
Published: September 2009

Double-workshop mixed chlor-alkali planned model production process is a multi-level multi-product multi-constraint mixed batch planning problem production line model, taking into account the actual production of joint production of dual-workshop mode of production to determine the products and materials at various workshops, various Plan period on the production quantity, at the end of each period to meet the delivery needs of the type and quantity simultaneously, during the product implementation plan the goal of profit maximization. It uses particle swarm algorithm to reach the answer, indicating the feasibility of the method and effectiveness through examples of the calculation.
Dynamic Analysis and Simulation of Deployable Planar Truss Mechanism
Authors: Sun Yi , Shi G.K. , Shan J.H. , Dong Ming Feng
Published: September 2009

This document researches on the improved deployable planar truss mechanism design and builds an dynamic equation of the model based on Lagrange equation in the multi-body system dynamic theory. The dynamic model is established to simulate the motion of the system and calculate the force condition of members respectively by ADAMS. Finally, the significant references for the elasto-dynamic analysis and optimization design of the truss mechanism will be provided.
Multi-Motor Synchronization of Multi-Wire Saw Based on Model-Free Adaptive Control
Authors: Jiang Jin , Dai Y.X. , Zhang Y.B. , Tang R. , Xiong Wan Li
Published: September 2009

Aimed at the problem of multi-motor synchronization in multi-wire saw, Strategy based on model-free adaptive control (MFAC), which has some characteristics such as without accurate system model, without system identification and without complicated manual tuning, is produced. MFAC is based directly on pseudo-partial-derivatives (PPD) derived on-line from the input and output data of the system using a novel parameter estimation algorithm. It is suitable for multi-wire saw in such a complex system which is nonlinearity, strong interference and strong coupling. Overall design of multi-wire saw is analyzed. Control structure of multi-motor is given. Motion model of multi-motor synchronization is established. To speed of main motor for reference, supply spool motor and collect spool motor, which have similar dynamic characteristics with main motor, are adjusted adaptively to follow operation of main motor, and synchronization motion is ensured. The prototype experiments show that the method used is right and feasible.
Calculating the Maximum Throughput in the Context of Workflow Execution
Authors: Xie Yi
Published: September 2009

Workflow performance analysis is the basis of workflow evaluation and optimization. Maximum throughput is an important aspect of workflow performance. In this paper, a process analytic model for workflow execution is firstly presented. Then an algorithm is developed to identify the bottleneck activity and to calculate maximum throughput, which is a good preparation for the further analysis and optimization of workflow. Finally the simulation results show the accuracy of the proposed algorithm.
Development and Experimental Study of Multi-Axis Micro-EDM Machine Tool for Small-Hole Based on Linear Motor
Authors: Wang Zhen Long , Li Mao Sheng , Chi Guan Xin , Wang Yu Kui , Zhao Wan Sheng
Published: September 2009

A multi-axis micro-EDM machine tool for small hole is developed. It mainly includes marble base, precision servo and linear-motor platforms, RC pulse power supply, CCD microscope and so on. Superiority of linear motor used on the Z axis is analyzed. Primary experiments, in which small electrodes with different materials are used to machine 3mm thickness TC4, are carried out. Histograms of open-circuit voltage and capacitance to machining efficiency and electrode relative wear and small-hole samples are given. Influence rules of open-circuit voltage and capacitance to machining efficiency and electrode relative wear are analyzed according to experimental results.
Microbial Diversity by Substrate Utilization Profiles of Lignite Mines Samples of Gujarat, India
Authors: Patel M. , Tipre D.R. , Dave Shailesh R.
Published: September 2009

Microbial diversity studies of lignite mines of Rajpardi, Amod, Tadkeshwar and Panandhro, Gujarat, India, were carried out by substrate utilization-based, community-structure analysis. In Biologâ EcoPlates out of 31 different substrates, 1 to 28 substrates were metabolized. On the basis of these, similarity index and diversity indices were studied. From an extreme mine site Gram-positive, Gram-negative, fungi and yeasts were isolated and identified. One of the yeasts isolated is for the first time reported from a lignite mine ecosystem Apart from this auto- and heterotrophic iron oxidizers; sulphur oxidizers and sulphate reducers were also isolated. So, lignite mine ecosystems, inspite of the extreme environment showed rich microbial diversity.
Microbial Diversity in a Brazilian Acid Moderate Drainage and Experimental Nickel Bioleaching System
Authors: Alves L. , Bernardelli C. , Leão V.A. , Teixeira Monica , Donati Edgardo R.
Published: September 2009

The aim of this work was to determine the microbial diversity of the acid mine drainage (AMD) material collected at an abandoned pyrite mine in Ouro Preto, Brazil. AMD samples were compared to a nickel sulfide column bioleaching pregnant solution which was used as reference. Fluorescent in situ hybridization analyses (FISH) and Denaturing Gradient Gel Electrophoresis (DGGE) were used. FISH analysis was carried out using specific 16S rRNA probes. The extracted DNA was amplified using universal primers for bacterial 16S rRNA genes and analyzed by DGGE. Acidithiobacillus. ferrooxidans was not detected in AMD samples. However, the presence of Acidithiobacillus thiooxidans was confirmed. In other hand, in the bioleaching tanks samples studied, both bacteria species were detected. The non-identified DNA bands were cloned and sequenced for complete characterization.
Design and Use of Oligonucleotide Microarrays for Identification of Biomining Microorganisms
Authors: Ehrenfeld N. , Aravena Andres , Reyes-Jara A. , Barreto M. , Assar R. , Maass A. , Parada Valdecantos Pilar
Published: September 2009

Results from a high density microarray having 32,392 50-mer oligonucleotides, termed BMS2.1, were analyzed and used for the design of a new slide, called BMS 3.0, with 560 specific oligonucleotides manufactured in standard slides to be used in any open platform. Hybridizations of several samples, either known microorganisms or environmental samples, were performed. Automatic microarray analysis software was built in order to handle these data in a quick an efficient way. While oligonucleotides designed for microorganisms with known genome sequence showed a very good behavior, according to predicted design, variations were detected when different strains were hybridized, probably due to inadequate specificity of probes. Appropriate parameterization of the analysis software will improve prediction of presence for most of the microorganisms.
Nucleic Aacid Extraction from Biomining Microorganisms
Authors: Zammit Carla M. , Mutch L.A. , Watling Helen R. , Watkin Elizabeth L.J.
Published: September 2009

Various methods of nucleic acid (NA) extraction were investigated with the aim of developing a quantitative method of NA extraction from five representative strains of biomining microorganisms. The process of removing cells from mineral surfaces, lysing microorganisms, precipitating NA and purifying RNA were analysed. The success of each method was examined spectrophotometrically, by agarose gel electrophoresis and PCR or quantitative real time PCR (qPCR). The most important step was shown to be cellular lysis, which principally impacted on the quantity of NA extracted from each strain. The quantity and quality of extracted NA was highly dependent on the method of NA precipitation. This study resulted in the development of a NA extraction method that reliably and reproducibly extracted NA from five strains of biomining microorganisms.
Predicting the Function of Hypothetical Genes in Genomes of Bioleaching Microorganisms
Authors: Ossandón F.J. , Rivera G. , Lazo F. , Holmes David S.
Published: September 2009

A particularly challenging problem in genome annotation is to attribute function to genes annotated as “hypothetical, no known function”. These typically account for about 40% of all genes regardless of the genome. Some of these are “orphan” genes and are not found in any other genome. Some of these could encode species specific proteins and so are particularly interesting for evaluating novel metabolic potential and for understanding the evolution of genes and genomes. Several similarity and non-similarity bioinformatics tools exist that help predict function of hypotheticals, but none are able to suggest function for more than a few percent and the annotation of the others remains a formidable task. We have developed a bioinformatics tool called AlterORF (www.AlterORF.cl) that is able to identify alternate open reading frames (ORFs) embedded within annotated genes. Analysis of over 2 million genes in over 700 completely sequenced genomes reveals that alternate ORFs of substantial length (potentially encoding 70 amino acids or more) are surprisingly common, especially in G+C rich genomes. During our examination of these alternate ORFs, we uncovered hundreds of examples where the alternate ORF has a significant hit with databases of motifs and domains (e.g. CDD, Pfam) and where the actual annotated gene is described as hypothetical and has no database match. This strongly suggests that the annotated gene has been incorrectly identified and that the alternate ORF is the real gene. We describe the evaluation of the following genomes of bioleaching microorganisms and others that reside in similar ecological niches using AlterORF: Acidithiobacillus ferrooxidans (2 strains), Leptospirillum type II, Methylacidiphilum infernorum, Picrophilus torridus, Sulfolobus acidocaldarius, S. solfataricus, S. tokodaii, Thermodesulfovibrio yellowstonii, Thermoplasma acidophilum and T. volcanium. Examples of novel genes from these microorganisms and their suggested roles in metabolism will be described.
Some Physiological Properties of Three Novel Fe(II)- and Sulfur-Oxidizing Strains Affiliated to Alicyclobacillus
Authors: Jiang C.Y. , Guo Xu , You X.Y. , Liu Yan Yang , Liu S.J.
Published: September 2009

This study focused on the soils of sofataric region and acid mine drainage from a copper mine. Based on cultivation, 8 and 6 strains that grow on Fe(II) and sulfur compounds, respectively, were obtained from samples from these two environments. Analysis of 16S rRNA genes of the 14 strains indicated that they were affiliated to Acidithiobacillus, Alicyclobacillus, Sulfobacillus and Leptospirillum. Physiological and phylogenetic studies indicated that three strains (TC-34, TC-71 and ZJ-6) might represent three novel members of Alicyclobacillus. These strains showed 94.8-97.1% 16S rRNA gene identity to other species of Alicyclobacillus. Otherwise, strain TC-34, TC-71 and ZJ-6 showed a range of phenotypic characteristics that differentiated them from previously recognized Alicyclobacillus species, including the growth temperature, assimilation of carbon sources and production of acids from a range of compounds. Chemoautotrophic growth using Fe2+, elemental sulfur and tetrathionate as sole energy source was observed. Especially strain TC-71 was obligately dependent on Fe(II) for growth and quickly oxidized Fe2+. It is concluded that the Fe(II)-oxidizers are metabolically diverse and represent novel Alicyclobacillus species. These are proposed to take part in biogeochemical cycling of iron and sulfur in the solfataric region and could be relevant for biomining.
Interrelation between Cells and Extracellular Polymeric Substances (EPS) from Acidiphilium 3.2Sup(5) on Carbon Surfaces
Authors: Tapia Jaime M. , Muñoz J.A. , González F. , Blázquez M. Luisa , Ballester Antonio
Published: September 2009

The interrelation between cells and extracellular polymeric substances (EPS) from the acidophilic bacterium Acidiphilium 3.2Sup(5) was investigated on two different carbon surfaces (carbon fibre cloth and graphite rods). This bacterium was chosen due to its ability to directly transfer electrons to carbon surfaces in aerobic conditions, which makes its use especially attractive in microbial fuel cells (MFC). The characterization of the bacterial adhesion and interrelation with the EPS was carried out using a combination of scanning (SEM) and transmission (TEM) electron microscopy. The extraction of the EPS was performed using EDTA and their characterization accomplished by chemical analyses and FTIR spectroscopy. The cellular lysis provoked by the extraction of EPS was determined by the protein/carbohydrate ratio. Chemical analyses showed that the main components of the EPS were proteins and carbohydrates, whereas FTIR spectroscopy showed the presence of a great majority of carboxyl, hydroxyl and amino groups. The tendency of cells was to adhere to superficial carbon imperfections, which after certain time were covered by a matrix of EPS.
FISH Analysis of Bacterial Attachment to Copper Sulfides in Bioleaching Processes
Authors: Huergo J. , Bernardelli C. , Viera M. , Sand Wolfgang , Donati Edgardo R.
Published: September 2009

Bioleaching is the biological conversion of an insoluble metal compound into a water soluble form. In this process metal sulfides are oxidized to metal ions and sulfate by acidophilic microorganisms capable of oxidizing Fe2+ and/or sulfur-compounds. The metal solubilization from sulfide minerals is a chemical process which requires Fe3+ reduction. It is an environmentally friendly technique and an economical method for recovering metals that requires low investment and operation costs. In this work we studied the bioleaching of two kinds of acid-soluble copper sulfides, one easily leached by mesophilic bacteria (covellite), and the other one refractory to their activity (chalcopyrite), in acidic media with or without Fe2+ ions. We studied attached and planktonic populations of autotrophic bacteria, such as Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans in pure or mixed cultures. The influence of a heterotrophic microorganism, Acidiphilium cryptum, was also studied. Attachment was evaluated with fluorescence staining and FISH using four specific probes. L. ferrooxidans showed highest initial attachment in all cases. The presence of Ap. cryptum increased the cell attachment compared with the autotrophic pure cultures. It was possible to correlate experimental data with a mechanism of bacterial-metal sulfide oxidation, the polysulfide pathway for acid- soluble metal sulfides.
Imaging of Acidithiobacillus Ferrooxidans by AFM and Analysis of AFM Curves
Authors: Chandraprabha M.N. , Natarajan K.A.
Published: September 2009

The aim of the present investigation is to obtain tapping mode images of Acidithiobacillus ferrooxidans and interfacial forces between Acidithiobacillus ferrooxidans cells and silicon nitride tip of AFM. The effect of exposure of cells to toxic metal ions like arsenic on the morphology of the cells was investigated by the section analysis of the AFM images obtained. Effect of glutaraldehyde fixation on force curves is also analyzed.
Advances in Tank Bioleaching of Low-Grade Chalcopyrite Concentrates
Authors: Gericke Mariekie , Govender Y. , Pinches A.
Published: September 2009

The focus of this paper is on the treatment of low-grade chalcopyrite-pyrite containing concentrates. The bioleaching of chalcopyrite is a major challenge due to slow copper leach kinetics and poor copper extractions. Bioleaching tests were carried out in bench-scale piloting facilities, comprising fully controlled multi-stage continuously operated reactor systems using moderate thermophile and thermophile consortia under both uncontrolled and controlled redox potential conditions. Bioleaching operating conditions and control strategies have been identified, which have the potential to significantly increase the rate of Cu leaching and to reduce process costs by allowing control of the amount of pyrite oxidised.
Influence of CO2 and O2 Feeding Rates on the Continuous Bioleaching of a Chalcopyrite Concentrate Using Sulfolobus Metallicus
Authors: Cautivo D. , Gentina J.C.
Published: September 2009

Bioleaching of secondary sulfides is a technical and economical well established bioprocess. However in the case of bioleaching of primary sulfides, like chalcopyrite and enargite, still is necessary to improve the bioprocess kinetic. One alternative that has been proposed to overcome this situation is to use hyperthermophilic bioleaching microorganisms. Nevertheless, higher process temperatures modifies in a different extent operation parameters like CO2 and O2 transfer rates, both gases being essential to the bioprocess.
The aim of this work was to establish quantitatively, using a continuous bioreactor operating at steady state conditions, which gas limits the growth and activity of bioleaching microorganisms when air is used as source of both of them.
The experiments were run in a 3.3 L agitated continuous bioreactor operated at 70°C, pH 1.8 and 150 g/L of copper concentrate rich in chalcopyrite.
Operating at steady state condition with an aeration rate of 1.2 vvm, a copper solubilization volumetric productivity of 1.7 g(Cu2+)(L•day)-1 and a copper extraction of 55% were obtained. Enriching the inflow air with CO2 up to 5% (v/v) showed the maximum values of these indexes, increasing 34% the volumetric productivity of copper solubilization and reaching 74% of copper extraction.
On the opposite way, enriching air with oxygen or increasing the aeration rate did not bring about any change either of the volumetric productivity or the percentage of copper extraction.
The results allow concluding that the CO2 is the limiting nutrient for cell growth in the continuous bioleaching of a chalcopyrite concentrate using hyperthermophilic microorganisms.
Indirect Bioleaching and ZINCEXTM Process: A Profitable Marriage to Process Zinc Polymetallic Concentrates
Authors: Frías C. , Sánchez F. , Martín D. , Díaz G. , Sanguilinda S.
Published: September 2009

Indirect bioleaching is a biotechnology that presents important advantages when apply to bioprocessing of zinc and zinc polymetallic concentrates such as high metals recovery, fast kinetic of 4-5 hours to get full metals extraction, sulphur oxidation to elemental sulphur (avoiding sulphuric acid generation, while pyrite mineral remains untouched), and use of conventional reactors (aeration is not required) and normal process equipments.
On the other hand, the development of high-efficiency bioreactors for ferrous iron bio-oxidation based on flooded fixed-bed model has opened the way to succeed in the potential commercial application of this innovative bio-hydrometallurgical technology, being especially attractive to benefit zinc and lead bulk or polymetallic concentrates containing other valuable metals like silver. In addition, a great variety of concentrates is feasible to be processed, e.g. in the range of 15% to 60% Zn and Pb metals content.
That aim, within European Biomine project, for the first time in biohydrometallurgy field, indirect bioleaching technology applied on Zn/Pb polymetallic concentrates has been demonstrated in continuous in an integrated pilot plant at Tecnicas Reunidas’ (TR) R&D Centre in Madrid (Spain) producing electrolytic SHG zinc plates.
Overall zinc recovery in the integrated pilot facility after more than 300 operating hours has been above 95% thanks to the ability and good performance of the ZincexTM technology (solvent extraction and electrowinning), in which obtaining of SHG electrolytic zinc is fully guaranteed with high current efficiency (above 93%) and good deposit morphology.
In definitive, a profitable marriage between indirect bioleaching process and ZincexTM technology has been successfully demonstrated in TR facilities at pilot plant scale, and main results of such integrated pilot plant operation are presented in this paper.
Microbes in Waste Water Samples from Mining Environments
Authors: Xie Xue Hui , Xiao Sheng Mu , Liu Jian She
Published: September 2009

The composition of microbial communities in five acid mine water samples were studied, using culture-independent 16S rDNA based cloning and restriction fragment length polymorphism (RFLP) analysis. Phylogenetic analysis revealed that the bacteria in these five samples fell into 4 major groups: Proteobacteria, Nitrospira, Firmicutes and Bacteroidetes. Proteobacteria organisms such as A. ferrooxidans appeared in samples SX3, K1 and K2, but was scarce in samples SX1 and SX2; Nitrospira organisms Leptospirillum ferrooxidans, Leptospirillum ferriphilum and Leptospirillum group III, were prevalent in samples SX1, K1 and K2, but with fewer in samples SX2 and SX3. Archaea were only detected in samples K1 and K2 from the Tong shankou copper mine. Thermoplasma and Ferroplasma lineages were detected abundantly in these two samples. Meanwhile, the results of Principal Component Analysis (PCA) based on the percentages of OTUs and data of biogeochemical parameters, revealed that biogeochemical properties affected the diversity of microbial communities in mine water. The pH, temperature and different concentrations of elements such as S, Ni, Co and Cu seemed to be key factors resulting in the diverse distribution of microbes.
Low Temperature Sulfate Reduction for AMD Treatment
Authors: Nevatalo Laura M. , Auvinen Hannele , Bijmans Martijn F.M. , Kaksonen Anna H. , Lens Piet N.L. , Puhakka Jaakko A.
Published: September 2009

The amenability of sulfate reduction at low temperature for the treatment of acid mine drainage in arctic areas was investigated with three reactor experiments. The aim of these studies was to assess the potential and determine rates of sulfate reduction at 9oC with formic acid and hydrogen as electron donors. Three different bench-scale reactor configurations were tested: fluidized-bed reactor, membrane bioreactor and gas-lift bioreactor. The reactors were inoculated with a low temperature enrichment culture of sulfate-reducing bacteria. The temperature range of sulfate reduction was studied with a temperature gradient assay. The microbial community structure of the reactors was analyzed using polymerase chain reaction - denaturating gel gradient electrophoresis (PCR-DGGE) with universal 16S rRNA gene primers and SRB specific dsrB primers. The stable sulfate reduction rates at 9oC in all the reactors ranged from 0.6 to 1.4 g SO42- L-1 d-1. The temperature gradient assay supported also by the PCR-DGGE sequence profiling indicated that the low temperature enrichment was dominated by a psychrotolerant mesophilic Desulfomicrobium sp. having their maximal sulfide production rate at 31oC.
Recovery of Copper from Acid Mine Drainage by an Integrated Sulphate Reducing Process
Authors: Chen Bo Wei , Wen Jian Kang , Liu Xing Yu
Published: September 2009

An integrated sulfate reducing process was used to treat Acid Mine Drainage with high concentrations of Cu2+, Fe and SO42-. The water treatment system integrated a sulfidogenic UASB bioreactor with a precipitation reactor which was used to recover copper. Sodium lactate was used as energy source. The effective volume of the UASB reactor was 2 L and the hydraulic retention time was 12.57h. In the sulphate removal reactor, sulphate was removed from 21160 to 195 mg/L with a rate of 4427.8 mg/L/d. Cu2+ and Fe was removed by biologically generated S2- and OH- from 360 and 6520 to 0.049 mg/L and less than 10 mg/L respectively. The average COD, copper and iron removal rate was 2523.2, 15.21 and 274.98 mg/L/d separately. The effluent pH reached 6.0-7.0. The results showed potential usage of this bioreactor in treating Acid Mine Drainage.
Copper Biosorption and Bioprecipitation by Eichhornia spp. and Sulphate Reducing Bacteria
Authors: Dave Shailesh R. , Damani M.S. , Tipre D.R.
Published: September 2009

Eichhornia spp. biomass collected from Chandola lake, Ahmedabad, Gujarat,
India. Point of zero charge of the biomass was pH 7.3. Flask study showed pH 5 and 2 to 3 h
contact time as optimum conditions for copper sorption. In 24 h of contact time, as high as
85% of copper was removed from 100 ppm copper containing solution. In first 2 h of the
contact time the removal reached to 67.25%. Copper loading capacity of the biomass ranged
between 2.85 to 1.0 g per 100 g of biomass. Influence of pH, temperature, nickel and zinc
was studied by 24 factorial experiments. Under the experimental conditions pH and
interactions between pH-nickel, temperature-pH and temperature-pH-nickel-zinc were found
to be significant with 60 to 74.7% copper removal. As high as 95% of sorbed copper was
desorbed with 0.1 N HNO3. Langmuir and Freundlich isotherms were also studied. Reactor
study showed 90% overall copper removal from 25 L of copper containing waste and sulfatereducing
bacteria played a significant role. Treatment of actual waste also showed 61% of
copper removal. SEMquant element analysis showed presence of 12.39% w/w of copper in
the biomass exposed to the waste, where as only 0.0018% of copper was detected in
unexposed biomas
Effects of Different COD/Sulfate Ratios on the Growth of Metal Tolerant Sulfate Reducing Bacteria (SRB)
Authors: Barbosa L.P. , Bertolino S.M. , Freitas P.C. , Oliveira V.A. , Pina Pablo D. , Leão V.A. , Teixeira Monica
Published: September 2009

Sulfate reducing bacteria (SRB) can be used as an alternative biotechnology to promote passive treatment of industrial effluents. Treatment efficiency however depends on pH and metals content of the effluent and also on the quantity of organic matter available. As COD/sulfate ratio varies, sulfate consumption changes. It is commonly assumed that the ideal COD/sulfate ratio is around 0.67. The aim of this work was to optimize the growth and sulfate reduction capacity of mixed bacterial cultures. Samples were cultured using modified Postgate C medium. Metals (Cu, Mn and Ni) were added to the medium in order to study bacterial resistance. Maximum sulfate reducing (98%) was achieved for lactate containing medium, pH 7.0. However, with ethanol containing medium sulfate removal was of about 50%. Acetate production was observed in all cases. Results shown that lactate was more efficient than ethanol for sulfate biological reduction and pH neutralization.
Characterization of Oxidizing Activity of a Microbial Community in an Industrial Bioleaching Heap
Authors: Soto Pamela , Meneses Claudio , Contador Y. , Galleguillos Pedro A. , Demergasso Cecilia , Serón M.
Published: September 2009

In order to explore new options to optimize the low-grade copper ore bioleaching process, it is important to understand the kinetics of microbial oxidation at industrial level. This work studies the changes of iron and sulfur oxidation rates of microbial communities in solution from an industrial low grade copper bioleaching heap process at Escondida Mine in Chile. Pregnant leach solution (PLS) samples were analyzed periodically to determine physico-chemical parameters. The total numbers of the different microorganism species in industrial samples were determined by Real Time PCR. In addition, Most Probable Number assays (MPN) were performed for iron and sulfur oxidizing microorganisms. Kinetics incubation tests of PLS in the presence of iron or sulfur were performed to study the iron and sulfur oxidation, in total, 102 oxidation profile tests were obtained. Based on the oxidation profiles obtained, the tests were divided into four groups, labeled as fast, normal, stepped shape, and incomplete. The grouping system was established by considering oxidation time and rates, during the initial oxidation stages and accounted for any lag phase. A data mining technique, called decision trees was used to analyze the data and to generate rules that represented patterns in the data. Strong correlations were found between the predominant microorganisms and the behavior of the oxidation tests. Preliminary results indicate that the magnitude order of MPN of the iron oxidizing microorganisms is an important factor in the microbial oxidizing activity, followed by the predominant specie within the microbial population, PLS temperature and Eh.
Cadmium and Zinc Biosorption by Macrocystis Pyrifera: Changes in the Biomass
Authors: Plaza J. , Guibal Eric , Taulemesse J.M. , Viera M. , Donati Edgardo R.
Published: September 2009

Macrocystis pyrifera was used for the recovery of Zn2+ and Cd2+ from slightly acidic solutions (i.e., pH 4). Sorption isotherms were obtained from mono- and bi-component solutions. For the study of metal desorption, EDTA, HNO3 and Ca(NO3)2 were used as eluents. Metal release (Ca2+, Mg2+, K+ and Na+) was monitored in order to evaluate ion exchange mechanisms. After metal sorption/desorption steps the sorbent was characterized using SEM-EDAX analysis. SEM-EDAX analysis also allowed identifying the presence of elements such as Si, Al, Co, Ag, S, P, and Fe in the cell wall. Zinc desorption was almost complete when using 0.1 M nitric acid solution and the sorbent was not significantly damaged by the acidic treatment. Cadmium was completely removed from loaded sorbent when using EDTA, but at the expense of a partial degradation of the biomass as evidenced by the decrease in the intensity of the C and O peaks (SEM-EDAX).
Biotransformation of Metalloporphyrins by Microorganisms Isolated from Organic-Rich Metal-Bearing Black Shale
Authors: Matlakowska Renata , Sklodowska Aleksandra
Published: September 2009

Indigenous microorganisms isolated from organic-rich copper-bearing black shale from the Fore-Sudetic Monocline were able to transform naturally occurring metalloporphyrins in laboratory cultures. It was also demonstrated that these bacteria can utilize synthetic metalloporphyrins as the sole energy and carbon source. The first step in metalloporphyrin biotransformation was identified as the highly effective bioaccumulation of these compounds in bacterial cells. The ability of both living and dead cells to biosorb metalloporphyrins was also confirmed. Besides contributing to the important biogeochemical role of these microorganisms in the environment, their biotransformation activities are of potential use in the bioremediation of copper tailings as well as in the recovery of metals from organic-rich black shale ore, which is not possible using traditional hydrometallurgical procedures.
Pyrite Oxidation by Halotolerant, Thermotolerant Bacteria
Authors: Norris Paul R. , Nicolle James Le C. , Calvo-Bado L. , Angelatou V.
Published: September 2009

Thermotolerant “Thiobacillus prosperus”-like bacteria were enriched from warm, acidic sediments of the island of Milos in the Aegean Sea. Analysis of 16S rRNA gene sequences indicated at least two thermotolerant species, with at least one of them present in similar niches at Vulcano, Italy. Iron solubilization in a pyrite-enrichment culture at 47°C was most rapid in the presence of NaCl at 30 g.l 1. One of the novel species (strain M7) grew in pure culture on pyrite with NaCl at 50 g.l-1, but iron solubilization was most rapid with 20 g NaCl.l 1 at just below 50°C.
Assessment of Microbial Adhesion in Mixed Cultures to Sulfide Minerals Using CARD-FISH Techniques
Authors: Echeverría A. , Demergasso Cecilia
Published: September 2009

The adhesion of microorganisms to minerals is one of the least understood aspects of bioleaching processes. Mineral and microorganism type are determinant factors affecting the capacity of a microbial community to form biofilms in these processes. In this paper the adhesion capacity of different microorganisms to different copper sulfide minerals generally present in bioleaching processes was studied. The minerals, chalcosite, chalcopyrite and pyrite were used and the composition of the microbial population which adhered to the mineral surfaces was determined using the Catalyzed Reporter Deposition Fluorescent In Situ Hybridization (CARD-FISH) technique. This technique involves the fluorescent marking of the cells using specific DNA probes and their observation with a confocal microscope. Three probes were used against the microorganisms: Acidithiobacillus ferooxidans, Acidithiobacillus thiooxidans and Leptospirillum. Polished fragments of the three minerals were placed in a tube with a culture medium which was inoculated with cells from a mixed culture capable of growing at 25°C. The adhered microorganisms were counted with CARD-FISH and compared with the total count which was carried out with DAPI staining. The results show that microorganisms adhered indistinctly to pyrite and chalcopyrite but not chalcosite. It was also observed that in pyrite 60% of the adhered microorganisms were Acidithiobacillus thiooxidans, 35% Acidithiobacillus ferrooxidans, and 1 % Leptospirillum. The remaining 4% were unidentified microorganisms.
Enabling Low Temperature Copper Bonding with an Organic Monolayer
Authors: Fang Ang Xiao , Wei Jun , Zhong Chen , Cheong Wong Chee
Published: September 2009

Typically, copper material is used as a bonding material in MEMs devices for its excellent mechanical, electrical and hermetic properties. Direct copper bonding, however, requires high temperature (>300°C) to forge a bond due to the oxidative nature of copper. In this study, using an alternative approach based on an organic monolayer coating, we demonstrate metallurgical bonding between two copper surfaces under ambient condition at low bonding temperature below 140°C, while maintaining reliable mechanical joint integrity of 50MPa. This monolayer is believed to behave as a passivation layer, protecting the copper surface against oxidation under ambient conditions. In contrast to a bulk oxide layer, this layer can be easily displaced during mechanical deformation at the bonding interface.
Fabrication of a Microfluidic Device with Insulated Electrodes on Top and Bottom Sides of the Channel
Authors: Zhang Lu Jun , Bossche Andre
Published: September 2009

This paper presents a method to fabricate the microfluidic devices with insulated electrodes on top and bottom sides of the channel. To form the channel containing vertically opposing electrodes, two processed substrates were bonded together with an SU-8 intermediate layer sandwiched in between. An adhesive bonding technique, at wafer level, with accurate alignment was developed. Instead of using wafer bonder, the bonding was conducted on a hotplate, which relieves the requirement on the process equipment to a great extent.
A Novel Piezoelectric Valveless Micropump with an Integrated Diffuser/Nozzle Bulge Piece Design
Authors: Chan Tsung Hsing , Cheng Chiang Ho , Yang An Shik , Tseng Li Yu
Published: September 2009

The current paper endeavors to present the design, fabrication, and test of a novel valveless piezoelectrically actuated micropump. The proposed micropump mainly comprises a stainless-steel structured chamber with a piezoelectric (PZT) diaphragm as a driving source to propel liquid stream under actuation. During tests, the micropump, operating at the frequency of 250 Hz and the voltage of 160 Vpp, engendered a mean water flowrate up to 0.779 ml/min. In the analysis, the computational fluid dynamics (CFD) software ACE+® was utilized to examine the time-varying flow phenomenon in a full-scale PZT micropump throughout an actuation cycle. The computational approach adopted the transient three-dimensional conservation equations of mass and momentum with the moving boundary specified to represent the movement of the diaphragm. At the frequency ranging from 150 to 250 Hz, the vortex pairs were evidently formed and thereby caused a relatively high pressure drop near the diffuser outlet inside the micropump chamber. Numerical experiments were also carried out by varying the opening angle of the diffuser/nozzle module within the range of 8°－12°, the angle setting of 8° can provide the best performance in term of the maximum pumping flowrate achieved.
Novel Design and Fabrication of High Sensitivity MEMS Capacitive Sensor Array for Fingerprint Imaging
Authors: Damghanian Mitra , Majlis Burhanuddin Yeop
Published: September 2009

A novel MEMS capacitive pressure sensor array is designed and fabricated for fingerprint acquisition application. Based on analytical investigations and FEM analysis, the designed structure of pressure sensor cells assist from an aluminum clamped-clamped wide beam as the movable electrode of variant capacitor, instead of usual membrane structure. A rectangular base T-shape protrusion is also used on top of the deflecting electrode to concentrate pressure and increase the sensitivity. Proven by the real test of the fabricated sensor structure, this design has enhanced sensitivity and linearity of the device compared to all membrane based reported prototypes without crossing the dpi limits. Structural modifications have resulted in a simpler fabrication process as well.
UV-Visible Spectra Character of Larger Diameter of Gold Nanoparticles (AuNPs)
Authors: Zhu Shao Li , Zhang Jing Bo , Yue Lanry Yung Lin , Hartono Dany , Liu Ai Qun
Published: September 2009

The dependence of the optical properties of spherical gold nanoparticles (AuNPs) on particle size and wavelength were analyzed theoretically using Mie theory, where the complex refractive index of gold was corrected for the effect of a reduced mean free path of the conduction electrons in small particles. The simulation results indicated that larger diameter AuNPs have high sensitivity and the resolution compared to the small diameter AuNPs. Two different fabricated methods for synthesis larger diameter AuNPs have been proposed. One is the directly synthesis 50nm AuNPs, the other method is separated to two steps (prepared 13nm AuNPs seeds, then synthesis 50nm AuNPs). Comparing the UV-vis spectra and SEM image of the AuNPs synthesized by these two method, we find that the symmetry of the directly synthesis method is better than the other method. The experiment results show that the synthesis AuNPs are uniform. The major aim of this work is to provide a simple and fast method to synthesis larger diameter AuNPs and research the optical properties of the nanoparticles.