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By M. Jahazi, J. Gholipour

Design and manufacturing of parts using hydroforming process require knowledge about material behaviour and tribological effects during hydroforming. Lubrication is one of the key issues in successfully hydroform the tubes. A Ni-based super alloy tube with 50.8 mm (2 inches) outer diameter and 0.9 mm (0.035 inches) thickness is considered for this research to study the effect of lubricants on the formability of the tubes. Hydroforming of a hollow compressor blade is considered for this project. A combination of press forming and hydroforming is employed to produce the part. LS-DYNA, an explicit dynamic finite element code, is used to model the experiments. Different lubricants are modeled using different coefficient of friction in the model. Predicted results for strain distribution at a critical section of the tube are extracted for each case to evaluate the effect of different lubricants on the process.

Jan 1, 2006

By Y. Zedan

Cutting fluids play important roles during machining, including the reduction of friction and temperature. Using a cutting fluid, however, degrades the quality of the environment and increases machining costs. The aim of the present research work is to study the effect of cutting fluids and their interactions with cutting parameters on the quality of holes during the drilling of 6061-T6 aluminum alloys. The lubrication types and modes investigated are dry machining, flood lubricant machining and minimum quantity lubrication machining (MQL), while the part quality criteria include the surface finish, the dimensional accuracy, and burr forms and sizes. A scanning electron microscope (SEM) was used to investigate the formation of built-up edges (BUE) in the drill flutes as well as the surface texture of drilled holes. It was found that dry machining and MQL machining can produce parts having quality levels comparable to those obtained in wet machining, when using the optimal cutting conditions.

Jan 1, 2011

By Shu-cai Zhou

"To understand the solidification behavior of austenitic heat-resistant stainless steel (TP34 7) in rotary electromagnetic-field, the influence of electromagnetic stirring in mold (M-EMS) on solidification structure of TP34 7 heat resistant steel in a round billet continuous casting was investigated based on industrial experiments. The results indicate that the excellent billet solidification structure of TP34 7 heat resistant steel can be obtained with appropriate electromagnetic stirring parameters. The solidification structure of TP34 7 heat resistant steel can be remarkably refmed, central porosity and shrinkage cavity can be remarkably decreased and equiaxed grains zone widens was enlarged. The industrial trials verify that the stirring intensity of TP34 7 heat resistant austenitic stainless steel should be higher comparing with plain carbon steel. Due to a higher viscosity, rotating speed of molten stainless steel was 20-30% lower than that of molten carbon steel in the same magnetic flux density.IntroductionIn recent years, the development of ultra super critical (USC) plants is accelerated by the demands of environment protection and energy saving, and USC plants with steam temperature and pressure conditions in excess of 593°C and 24.lMPa respectively were constructed. To achieve the goal, it is important to develop new materials with excellent high temperature strength, superior resistance to oxidation and corrosion at high temperature. Besides, their cost must be low enough to meet the requirement of plants [ 1]. TP34 7H steel is promising austenitic heat-resistant steel, which is used as superheater/reheater tube material and is extensively used for high temperature components and fossil-fired power plants, and suitable to be used in USC boilers plant. This kind steel contains with about 0. 7%Nb and it keeps higher allowable stress and creep rupture strength than TP304 and TP321H [1-2]. TP347H has conventionally been produced by ingot casting followed by forging and rolling. Recently, in order to decrease the production cost, challenging trials to produce these types of alloys by a continuous casting (CC) process have been attempted. However, the solidification structure of austenitic stainless steel is one of the key issues that attract more attention. Due to the low thermal conductivity of TP347H heat resistant stainless steel (much smaller than that of plain carbon steel), pronounced defects during continuous casting of austenitic heat-resistant steel such as coarse columnar, center porosity and coarse bridging, greatly influence mechanical properties of fmished products.A widely used technique in metallurgy is the inductive drive of molten metals using rotational or traveling magnetic fields. Recently, rotary electromagnetic stirring (EMS) has been applied to reducing various defects and improving increase the solidification structure of the metals in the continuous casting of steel, Al-based alloys and Mg-based alloys [3-8]. Electromagnetic stirring of plain carbon and low alloy steel in the continuous casting bloom and slab is well established for improving the quality of cast products [9-11] and is widely used in industry. However, very few literatures on electromagnetic casting of heat resistant stainless steel have reported. In this work, an industrial plant trial was performed to clarify the effect ofM-EMS on the macroscopic quality ofTP347heat resistant steel billet, in which the regularity and mechanism of the influence of EMS on solidification casting billet were discussed."

Jan 1, 2014

By Jafar Safarian, Gabriella Tranell, Stine Espelien

Hydrometallurgical treatment of silicon is an effective process for the removal of metallic impurities for producing solar grade silicon feedstock. In the present research, the removal of impurities from silicon is studied through the addition of Mg into a commercial silicon, its solidi fication, and acid leaching. The effect of concentration of HCl, temperature and leaching duration on the removal of impurities are studied. It is shown that the impurities such as P, Fe, Al, Ti, Ca, …are effectively removed through the applied method and Mg improves the segregation and the removal of the impurities. Scanning electron microscopy examination of the samples indicates the disintegration and dissolution of Mg2Si phase in acid leaching which causes the chemical and physical removal of the impurities existing in the phases between the silicon grains. It is shown that the leaching process rate can be optimized through the control of the acid leaching conditions.

Mar 1, 2017

By Feng Xue, Mi Xujun, Peng Lijun, Yin Xiangqian, Liu Dongmei, Xie Haofeng, Huang Guojie, Yang Zhen

The Age-hardening Cu-Cr alloys are extensively used in integrated circuit lead frame, railway contact wire, resistance welding electrode and continuous casting mold copper plate, owing to having an excellent combination of high electrical or thermal conductivity and high strength. High temperature performance is very important during the service process. Effect of Magnesium and Zirconium on softening behavior of Cr-Cr alloy are investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). During the softening process in the Cu-Cr alloy, the recrystallization process, grain growth and Cr precipitates coarsening are observed. The addition of Mg or Zr to the Cu-Cr alloy, the resistance to elevated temperature can be significantly improved, owing to being restrained the growth of the precipitates by segregating along precipitates surface. INTRODUCTION Age-hardening Cu-Cr system alloys can be widely uesed in many fileds such as electrodes for spot welding (Hatakeyama et al., 2008; Cheng, Shen & Yu, 2013; Zhou et al., 2016; Chbihi, Sauvage & Blavette, 2012), intergrated circuit lead frame (Hatakeyama et al., 2008; Cheng, Shen & Yu, 2013; Zhou et al., 2016; Liu et al., 2006; Pang et al., Xia et al., 2012; Wang et al., 2009; Huang et al., 2003; Cheng, Yu & Shen, 2014; Zhang et al., 2016; Li et al., 2007) and railway contact wire (Cheng, Shen & Yu, 2013; Zhou et al., 2016; Chbihi, Sauvage & Blavette, 2012; Liu et al., 2006; Pang et al., Xia et al., 2012; Wang et al., 2009; Huang et al., 2003), because it has high strength, good electrical and thermal conductivity. The precipitation behavior of binary or ternary Cu-Cr alloys had been investigated by many researchers (Chbihi, Sauvage & Blavette, 2012; Peng et al., 2017; Batra et al., 2002). In addition, to obtain additional mechanical properties without much deterioration in electrical conductivity, trace addition of alloying elements like Zr, Ag, rare metals (Y and Ce) and Mg are added into Cu-Cr alloy. The addition Mg to Cu-Cr alloy accelerated the process of precipitates nucleation and restrained the growth of the precipitates by segregating along precipitates surface during aging, which enhanced the stability of the deformation microstructure and improved the mechanical properties of the alloy (Zhao et al., 2018). Additional zirconium in Cu-Cr alloy enhances the strength by the decrease in inter-precipitate spacing of Cr precipitates and the formation of Cu5Zr phase (Chihiro, Ryoichi & Kazue, 2008). Owing to the decrease in inter-precipitation spacing of Cr precipitates and to the Ag-atom-drag effect on dislocation motion, the addition of Ag can increase in strength, stress relaxation resistance and without much deterioration in electrical conductivity (Chihiro, Ryoichi & Kazue, 2008). The enhance in strength and electrical conductivity of the Cu-Cr-Zr alloy by adding Ce and Y elements are attributed to removing oxygen and sulfur from as-cast alloy (Li et al., 2006). However, the effect of Mg or Zr element on microstructure and properties of Cu-Cr alloy during the softening process are not clear. Therefore, Microstructure evolution and properties of a Cu-Cr systems alloy were investigated in detail by OM and TEM. The Relationship between microstructure and properties of Cu-Cr systems alloy was also discussed.

Jan 1, 2019

By Debbie Marshall

Nickel and cobalt in lateritic ores can be extracted by either a hydrometallurgical or a pyrometallurgical route. The high-iron limonitic fraction of a deposit is best processed' hydrometallurgically while the magnesium-rich transitional and saprolitic fractions are more suited for pyrometallurgical processing. During hydrometallurgical processing, it may be attractive, for economic reasons, to blend the limonitic component with transitional and saprolitic ores, which contain higher nickel levels. However, blending increases the concentration of magnesium in the feed, leading to increased acid demands. The decision on how much ore to process then becomes an economic one. Ore samples with different magnesium contents were prepared for the leach test program by blending limonitic and transitional ores. The ore samples were slurried in seawater and tested in the Falconbridge Hydrometallurgical Pilot Plant. As expected, acid consumption increased with increasing magnesium content of the ore. For target extractions of 95% nickel and 92% cobalt, the required residual free acid concentration increased from 30 g/L at 1.7% magnesium to 50 g/L at 2.7% magnesium. When the magnesium content was raised to 3.8% and 4.6% in subsequent pilot plant testing, the final free acid requirements did not increase beyond what was observed at 2.7% magnesium. Thus, the cut-off ore composition to maximize nickel units and minimize acid requirements is between 1.7- 2.7% magnesium. Keywords: high pressure acid leaching, laterites, magnesium

Jan 1, 2004

By Nam-Il Um

Bottom ash contains several ferrous materials (ferrous metals, Fe3O4, Fe2O3, FeS, etc.). In particular, ferrous metals contain heavy metal because Ni and Cr are chemically attracted to iron. Likewise, Cu is used to coat Ni and Cr metals as polish or to prevent corrosion. In this study, an Fe3O4-Fe2O3 double layer (similar to pure Fe) was found to have been formed in ferrous metal during air-annealing in an incinerator (1000°C). A strong thermal shock such as one that occurs during the water-cooling of bottom ash results in the breakdown of this oxidation layer, facilitating the degradation of ferrous metals and formation of corrosion products. Therefore, Fe-ion (heavy metal) oxides may be formed on ferrous metals and may be separated from bottom ash via magnetic separation. This study sought to investigate the separation ratio of heavy metals as magnetic separation and mineralogical formation of Fe-ion (heavy metal).

Jan 1, 2006

By J. Sugai

Formability of extruded round AZ31 magnesium alloy tubes with different manganese concentrations was evaluated by performing bending tests and measuring strain along the length of the tubes during the bending process. It was found that an increase in the manganese content from 0.3 % to 0.7% did not exert any significant effect on the values of yield stress, elongation, or compression to fracture. However the hardness tended to increase and the UTS decreased. The compressive ductility was significantly lower than tensile ductility for all manganese concentrations. Consequently, the formability of tubes decreased, causing cracks in areas where compression strain occurred during bending. It was also found that a larger strain occurred in the latter half of the region along the length of tube between the clamp-end and the tube-positioning block. Within this region, alloy tubes with higher manganese concentrations, 0.5 and 0.7 %, there was a clear strain peak within the strain profile, while for the 0.3 % Mn alloy, a more uniform strain profile was exhibited, indicating a more uniform deformation. This was confirmed by microstructural analysis of the specimens.

Jan 1, 2006

By C. C. Spencer

A CHARGE of 12,200 lb of scrap was used on all heats. The slag materials that were added to the furnace along with manganese ore were kept constant; that is, 230 lb Coxey sand was put on the banks at the slag line before each heat was charged, 35 lb limestone was added after the carbon boil. manganese ore was the only item varied in the four series described herein. I might add here that it is impractical for us to get the carbon clown in one boil, for the steel would come out through the doors and run over the floor. We take the carbon down in two vigorous boils.

Jan 1, 1947

By R. W. Smith

The flotation response and electrokinetic behavior of Chlorella vulgaris and Chlamydomonas sp . when using dodecylamine hydrochloride as collector were studied in the absence and presence of Pb(I1). Also, an electron microscopy study was made of the algae after Pb accumulation. The flotation behavior of the organisms after Pb accumulation appears at least partially related to the location of the abstracted Pb onto or into the organisms.

Jan 1, 1991

By M. Moats, I. E. Paschalidou, K. Awuah-Offei

Tellurium (Te) is a rare metalloid that is predominantly produced from the treatment of anode slimes formed during copper (Cu) electrolytic refining. The US Government lists Te as one of the 50 critical minerals, partly, because of its use in thin-film photovoltaic (PV) technology. Given policy initiatives to increase Te production, it is important to evaluate the life-cycle environmental impacts of Te recovery as a by-product of Cu processing. The literature contains a few specific life cycle assessment (LCA) studies of groups of metals that include Te without proper regard to impacts per life-cycle stage of Te production or the effect of allocation on the results. This study builds an LCA model of the production system of Te from anode slimes treatment to evaluate the effect of allocation on life-cycle impacts. We build life cycle inventories using data from the Ecoinvent v3.7.1 database, literature, and engineering calculations and allocate impacts in proportion to products’ mass and economic value. The results show that economic value-based allocation yields greater impacts than mass-based allocation indicating the significant effect of the allocation approach on life-cycle impact estimates.

Feb 1, 2023

Effect of Matching Relationship Between Bubble Size and Particle Size on Kaolinite Flotation

Sep 13, 2010

By Donna Post Guillen

"Cyclopentane, a flammable hydrocarbon, is being considered as a working fluid for waste heat recovery applications using Organic Rankine Cycles with Direct Evaporators. A postulated failure mode consisting of a pinhole leak in a heat exchanger tube raises safety concerns due to autoignition of the working fluid. Experiments were conducted to determine the ignition delay time (IDT) of cyclopentane using an Ignition Quality Test™ (IQT™) device. Two sets of experiments were conducted per ASTM D6890 (with exception to charge pressure and temperature) to determine ignition delay of the fuel at atmospheric pressure for standard air (-20.95% oxygen) and vitiated air (13.3% oxygen) at a temperature of 803 K. Operation of the IQT device at a much lower pressure (1 bar) than normal operation (21.4 bar) with a standard injector led to very rich conditions and wetting of the stainless steel chamber walls. Catalytic effects are postulated to produce the small IDTs observed. Experiments were repeated with a modified injector to prevent wall wetting, resulting in average IDTs that are substantially longer.IntroductionCyclopentane is being considered for use as a working fluid in a Direct Evaporator of an Organic Rankine Cycle (ORC). In this configuration, the heat exchanger is placed directly in the flow of the hot exhaust gas, rather than using a secondary heat transfer loop to isolate the flammable working fluid from the heat source. This configuration offers the advantages of approximately 15% lower cost and improved efficiency over a standard ORC. However, placing a heat exchanger operating with a flammable hydrocarbon in the hot exhaust gas stream presents potential safety risks. If a pinhole leak were to occur in the heat exchanger, working fluid could leak into the hot exhaust stream. Gas turbine exhaust is provided to the Direct Evaporator at a temperature of approximately 803 K, whereas the autoignition temperature of cyclopentane is 634 K (Gallant and Yaws, 1993). Autoignition of the working fluid has been identified as the key risk for this type of system.Autoignition occurs when sufficient self-heating by chemical reactions takes place to accelerate reaction rates to produce full-scale combustion. This is in contrast to forced ignition, in which an external source (e.g., spark) is employed to initiate the combustion process. For combustion to occur, the fuel to oxidizer concentration must be between the lower (lean) and upper (rich) flammable limits. The reaction rate depends on the species concentration of the fuel and oxidant, the local temperature and pressure. Ignition processes are comprised of steps that take a fmite amount of time. This latent period prior to the start of combustion is referred to as ignition delay time (IDT)."

Jan 1, 2012

By T. Guyaguler

An analytical technique using computer-based multiple-regression methods was employed to determine the relation between the dust-producing index and inherent rock properties of typical samples from a coal-producing area, one of the aims being to provide a preliminary predictive tool for practical use. The investigation demonstrated that factors varied in their influence under different conditions, the brittleness:toughness ratio and the hardness being the most significant inherent properties with hardness showing the highest positive correlation coefficient

Jun 13, 1905

By A. Jain

During sheet forming, metal experiences not only multi-axial load, it also undergoes strain path changes. For example, metal in the flange region may be drawn, may bend and unbend through a bead, before bending around a die radius, etc. Compression data were obtained from AZ31 sheet after pre-straining in compression along an orthogonal direction. The compression directions correspond to the sheet product (rolling-RD, transverse-TD, and normal-ND) directions. Three cases are examined: slip dominated deformation (ND) followed by twin dominated (RD or TD) deformation, twin dominated (RD or TD) followed by de-twinning (ND), and twin dominated (e.g. RD) followed by cross-twinning or secondary twinning (e.g. TD). Slip induced pre-straining simply hardens the material, while twin dominated pre-straining alters the texture allowing the material to either de-twin or re-twin upon changing the strain path. Polycrystal plasticity modeling has been used to predict qualitative features of the flow curves during strain path changes.

Jan 1, 2006

By H. Ito, T. Takasu

Effects of a mechnochemical treatment to oxide Ni ores have been investigated to enhance the extractive ratio of Ni from them in acid leaching process. High intensity grinding by a planetary boll mill showed strong effect to enhance the extractive ratio of Ni, for example , 10% of extractive ratio of Ni in sulfuric acid leaching(0.05mo1/1,at room temperature) increased to more than 90% with 60min. of planetary boll milling. Effects of additives(sulfur and some oxidants) on the mechnochemical treatment have also studied. Sulfur showed almost no effect to enhance the total Ni extractive ratio but increases the selectivity of Ni extraction. More than a half of Ni could be extracted by water when Ni ore was grinded at addition of Na2S207 in the milling treatment. Some effects of mechnocemical treatments to Ni ore are summarized in this paper.

Jan 1, 2005

By B. Hines

Grinding efficiency in a vertical stirred mill is affected by a wide range of process and mill configuration variables. Of these, the media fill, size, and intrinsic density have a significant effect on power draw and grinding performance. Media-related factors that influence grinding performance include, e.g.,a higher media filling providing additional particle breakage sites, or a lower bead density decreasing the running torque at a given media filling. It has been estimated that the grinding media can cause up to a 30% change in the specific energy required to grind. FLSmidth has generally recommended that the intrinsic density (specific gravity) of the grinding media be more than triple the slurry density. This density difference helps to ensure that sufficient stress intensity is generated in the mill to provide particle breakage. It also reduces the chance of media ?float? if there is a spike in either slurry density or slurry flow rate. The VXPmills have historically operated at slurry density values between 1.2 and 1.5 kg/L, which translates to nominal bead intrinsic density range between 3.6 and 4.5 kg/L. The current trend towards regrinding bulk flotation concentrates to even finer sizes, to improve recoveries of fine grained minerals, has provided motivation to consider closed-circuit operation of stirred media mills. The slurry density in this application is typically higher than in open-circuit operation due to the higher percent solids in cyclone underflows. An additional effect is that closed-circuit operation increases the potential for media float due to higher flow rates as slurry is recycled to the mill. The normal progression in extending the operating range of existing equipment is to carry out laboratory testing before pilot-scale and plant-scale trials. The results presented in this paper examine the media density to slurry density ratio and its effect on grinding performance.

Feb 23, 2014

By Shaik Jeelani, Mahesh Hosur, Esperidiana A. B. Moura, Rejane D. Campos, Emilia S. M. Seo, Kerry Kirwan, Francisco R. V. Díaz, Maria Sotenko

The use of natural fibers with polymeric resins has spread rapidly. In order to improve the mechanical properties of material, in this work, two variables were used: mercerization and electron beam irradiation. This paper describes the preparation and characterization of biocomposites that were prepared in two different routes using green high density polyethylene (HDPE) and Brazil nut pod fiber (BNPF): the first was to irradiate the composite with 150 kGy and the second was to irradiate the matrix with 15 kGy followed by composite preparation. In both cases mercerized and non-mercerized fibers were used. The irradiation process was carried out using a 1.5 MeV electron beam accelerator, at room temperature and in the presence of air. The material was characterized to evaluate the effect of treatment on mechanical properties of material.

Jan 1, 2015

By M. G. Eiselein, R. A. Smith, C. H. Sheerin

FMC Gold's Paradise Peak Mine was one of the top two producers of mercury metal in North America in 1988 and 1989. As a by-product, elemental mercury is produced from cyanide soluble mercury minerals, primarily to reduce the health risks incurred with the refining of precious metal precipitate containing elemental mercury and mercury amalgams. A discussion of the design, primarily the Merrill-Crowe units, and permitting for the safe production of mercury will be presented. Additionally, laboratory testwork to determine the effect of mercury on reagent requirements in the Merrill-Crowe process will be discussed.

Jan 1, 1990

By Lang Tao, Jun Wang, Wei Xiao, Wenqing Qin, Pan Cao, Guanzhou Qiu, Key Lab of Biohydrometallurgy of Ministry of Education, Central South University

"The effect of metal cations on the rutile flotation using styryl phosphoric acid (SPA) as the collector was investigated by micro-flotation test, bench scale flotation test, zeta-potential measurements and adsorption measurements. The micro-flotation results indicated that Fe (?) and Al (?) ions in low concentrations had obvious activation on the rutile flotation, and Pb (?) ions in low concentrations had smaller activation of rutile, but Fe (?), Al (?), Pb (?), Ca (?) and Mg (?) have strong inhibition of rutile flotation in high concentrations. The bench scale flotation results indicated ethylene diamine tetraacetic acid (EDTA), boracic acid, and sodium hexametaphospate can decrease the metal ions concentrations, and increase the recovery of rutile flotation. Adsorption measurements and zeta-potential measurements revealed that Fe (?), Al (?) and Pb (?) ions were adsorbed on the rutile surface, and had interaction with SPA. But when these ions concentration were over the largest adsorption capacity, residual metal ions could occur chemical reaction with SPA.INTRODUCTIONRutile is one of the favored minerals for production of titanium dioxide white pigment, primarily through the chloride manufacturing process (Stanaway 1994; Hou et al., 2013) However, the majority of rutile ores belong to refractory ores, while flotation is one of the most efficient methods to separate fine rutile from gangue (Dolbear et al., 1937). With the flotation development, many effective collectors were successfully applied in the oxide ore. Many reviews have indicated that organic phosphonic acid collectors showed good selectivity on oxide ores such as ilmenite and rutile (Bulatovic & Wyslouzil 1999; Liu & Peng 1999).It is inevitable that many types of metal cations are present in ore pulp. These metal cations significantly influence the flotation of minerals. Liu et al. (2015) showed that Ca2+ and Mg2+ could improve the floatability of spodumene at pH 12.5 and 10.0, respectively. The authors proposed that Ca2+ and Mg2+ ions readily form hydroxy complexes (CaOH(l) and MgOH(l)) and precipitates as (Ca(OH)2 and Mg(OH)2) in strongly alkaline solutions. Fan and Rowson (2000) investigated the effect of Pb(NO3)2 addition as an activator on ilmenite flotation and showed that it could improve ilmenite floatability. The addition of Pb(NO3)2 resulted in an increase of ilmenite zeta potential in both weakly alkaline and acidic aqueous solutions. Mehdilo, Irannajad, and Rezai (2015) studied three kinds of ilmenite of different origins and discovered that both Mg and V had a negative correlation with ilmenite flotation, while the Mn content seemed to correlate positively with flotation efficiency. A number of studies have also showed that Fe3+ can improve the floatability of ilmenite (Fan et al., 2009; Nuri, Mehdilo, & Irannajad, 2014)."

Jan 1, 2016