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By R. W. Charles

The Los Alamos National Laboratory, under the sponsorship of the U.S. Department of Energy; is involved with laboratory and field experiments to assist in development of the Hot Dry Rock concept of geothermal energy. The field program consists of experiments in which hot rock of low permeability is hydraulically fractured between two wellbores. Water is circulated from one well to the other through the fractured hot rock. Our field experiments are designed to test reservoir engineering parameters such as heat-extraction rates, water-loss rates, flow characteristics including impedance and buoyancy, seismic activity, and fluid chemistry. Laboratory experiments were designed to provide information on the mineral-water reactivity encountered during the field program. Two experimental circulation systems tested the rates of dissolution and alteration during dynamic flow. SOlubil ity of rock in agitated systems was studied. Moreover, pure minerals, samples of the granodiorite from the actual reservoir, and Tijeras Canyon granite have been reacted with distilled water and various solutions of NaCl, NaOH, and Na.CO.. The results of these experimental systems are compared to the observations made in field experiments done within the hot dry rock reservoir at a depth of approxi-mately 3 km where the initial rock temperature was 150 to 200°C.

Jan 1, 1981

By N. Pradhan, B. K. Mishra, B. D. Nayak, B. K. Mohapatra, R. K. Mohapatra

"Present study is about use of a group of Iron[Fe(III)] Reducing Bacteria (IRB) to convert the goethite (a-FeOOH) present in the original lateritic Nickel ore to magnetite under an anaerobic condition and subsequently release the bound Co(III) and Ni(II) through leaching. The lateritic Nickel ore contains 0.8% Ni, 0.049% Co, 1.92% Cr, 0.32% Mn and 50.2% Fe. An anaerobic dissimilatory Fe(III) reducing bacterial consortium capable of using acetate as carbon source (electron donor) and lateritic ore as terminal electron acceptor, changes the initial light brown color of the ore to dark brown. The change in color is due to the conversion of goethite to magnetite, which was confirmed by XRD. When the IRB treated sample was subjected to both bioleaching and acid leaching, it shows a greater recovery of Nickel and Cobalt values as compared to untreated original lateritic Ni ore. Further a magnetic separation method was used to separate the magnetic part of the treated lateritic ore and subjected to acid- and bio-leaching for better recovery of Nickel and Cobalt.IntroductionIt has been known that micro-organisms have the potential to reduce metals but more recent observations have shown that a diversity of specialist bacteria and archaea can use such activities to conserve energy for growth under anaerobic conditions [12]. Natural Fe(III) oxides are high in surface area and are reactive [1]. Fe (III) oxides adsorb a wide range of metal cations and anions by complexation to surface hydroxyl groups [17], and function as the primary redox buffering solid phase in many sediments and subsurface materials [5].Recently a number of bacteria have been isolated based on their ability to use metal ions, including Fe(III), as electron acceptor under anaerobic conditions. These are capable of producing energy by coupling the oxidation of organic compounds to reduction of Fe(III). Iron[Fe(III)]-Reducing Bacteria (IRB) have been isolated and identified from a wide variety of environments including freshwater and marine aquatic sediments and submerged soil [8]. The biogeochemical cycle of iron is linked to those of the trace metals, as many trace metals coassociate with Fe(III) oxides or reduced iron phases (e.g., magnetite, siderite, or iron sulfide). IRB can utilize Fe(III) oxides as terminal electron acceptors for respiration [18]; thereby reducing all or a fraction of the solid. The reductive portion of the iron biogeochemical cycle in non-phototropic environments (e.g., sediments and subsurface materials) is driven by the direct enzymatic reduction of Fe(III) oxides to Fe(II) by dissimilatory iron reducing bacteria [13,14]."

Jan 1, 2009

By A. H. Rhoades

The modern polarizing microscope with such accessories as cameras, infrared devices, reflectance and/or transmission photometers, indention hardness, and heating stage is used to characterize coal, coke, and other carbon forms. It allows characterization of coke by-products, such as tars and pitches and their insoluble residues. A useful product of the microscopic approach is the coal petrographic analysis which permits the prediction of coke strength carbonization pressure and volume change. Carbonization tests are expensive, time-consuming and require large amounts of coal. Tests on the coke show it to be strong or weak but give no indication of why. Petrographic analysis requires grams of coal and yields data that indicates why the coal produces coke of a given quality. Small samples from drill cores are sufficient for petrographic analysis. These data are also used to optimize blends for coke production. When coke-plant problems occur, ~he microscope can be used to check the coal blend proportions, as well as for weathered coal. Microscopy is useful in spore correlation work which may be a prerequisite to sound coal reserve estimates. Dispersed vitrinoid reflectance studies are used to determine the degree of organic metamorphism which serves to establish oil and gas deadlines. Tars and pitches are examined microscopically for the amount of normal solids as well as the size of undesirable carry-over solids resulting from pollution abatement practices in coke works. The microscope is also used to study coals for gasification and liquefaction.

Jan 1, 1981

By Taufiq Hidayat

Accurate description of complex phase equilibria provide the foundations for the improvement of non-ferrous pyrometallurgical smelting and recycling processes. Recent advances in microanalysis and experimental techniques enable accurate phase equilibria characterisation. Quantitative microanalytical techniques including Electron Probe X-ray Microanalysis and Laser Ablation ICP-MS enable the concentrations of major and minor elements present in different phases in samples to be accurately measured providing data that cannot be obtained using bulk chemical analysis techniques. High-temperature equilibration experiments coupled with the subsequent analysis of elementary reactions at micro- and macro-scales ensure the attainment of equilibrium conditions, and therefore, ensure true phase equilibria information is obtained. Examples of the application of the improved methodology on the investigation of phase equilibria of low-order and complex, multi-component gas/slag/matte/metal/solids Cu2O–PbO–ZnO–Al2O3–CaO–MgO– FeO–Fe2O3–SiO2–S systems and the distribution of minor element are provided. The experimental study is closely integrated with thermodynamic database development for the above system. Example of implementation of the research outcomes into industrial operations is demonstrated.

By Jerry D. St. Clair

A multidisciplinary team of scientists and engineers at Wont has been working to understand heavy metal contamination of DuPont process waste streams and technologies for abatement of these metals. As part of this effort, an extensive study was made of a specific waste stream of importance in DuPont's environmental commitment. This 200 gpm stream contains 5-5000 ppm of nickel plus a variety of inorganic and organic constituents. The chemical complexity of the waste rendered conventional. alkaline precipitation ineffective, and only through the simultaneous application of analytical characterization, fundamental chemical understanding, and process engineering did effective technical approaches emerge. In this instance, ion exchange, sulfide precipitation, and caustic digestion ultimately proved successful in reducing the nickel to below the 1 ppm target. The results of this study will be presented, along with key learnings about the process of solving heavy metal contamination problems.

Jan 1, 1994

By Gennady I. Gulyayev

A mathematical model of plastic deformation occurring in cold plug drawing of mother tubes with initial cross-sectional wall thickness variations (CSWTV) has been developed. The main provision of the model is that eccentricity em is of such value that projection of all forces acting upon the plug in the deformation zone along the axis perpendicular to the drawing axis equals to zero. Calculations have proven that with other conditions being equal increase in the die cone angle and the deformation cycle number reduces CSWTV. Theoretical findings were confirmed by practical results. Keywords: cold, drawing, plug, die cone, plastic deformation.

Jan 1, 2003

By O. Forsén

In the first part of this paper is studied the behaviour of small amounts of impurity elements? in the solidification of copper anodes. In the second part the dissolution of these impure anodes in sulphate based electrolysis is discussed. The first part is introduced with practical examples, the .model of solidification of impurities during the solidification of anode copper. According to this model the solidification structures of anode copper are strongly influenced by both thermodynamic and kinetic factors. Thermodynamics determine the microstructure of anode copper, but kinetics can alter the composition of melt to such that there is formed unequilibrium structures during the solidification, especially when the residual melt is solidified. The electrolysis experiments have clarified the behaviour of impuririties in the electrochemical dissolution in sulphate. Based copper electrolysis. In this study it is widely investigated to what extent any impurity elements or oxides will dissolve. In copper electrorefining. With the aid of the electrochemtcal experiments it was possible to fulfil quantitatively the qualitative results accomplished by microstructure studies.

Jan 1, 1985

By O. A. Ogunseitan

The contamination of aquatic ecosystems by mercury wastes is one of the most serious forms of environmental pollution associated with the metal mining and electrochemical industries. The transformation of inorganic mercury to alkylated species is a reversible bacterially-mediated process. The production of methylated mercury is of ?major public health and eco-toxicological concern because these forms of mercury are highly toxic ?and they bioaccumulate in aquatic organisms. We determined the response of the genetic determinants of mei:cury transrormation by Pseudomonas species (that predominate in contaminated soils and sediments), to the concentration and species? or available mercurfiations. By combining selective isolation and gene. ?probe techniques, the intrinsic genetic potential for mercury detoxification in a contaminated environment ?can be estimated. We determined that genetic units required for mericury volatilization (merA ?for mercuric reductase) are naturally amplified in response to mercury. Mercury-resistant bacteria that tolerate up to 100 ug Hg(Il)/ml of medium contain about 10 times more DNA fragments encoding merA than in unadapted bacteria. The exposure of bacteria to methylated.Hg (10 ug/ml lake water) produced increases (up to 10 times) in .genetic units, and higher levels of genetic expression (up to 50 times) per ml of lake water for the mercury reductase system, than on-induced lake water. The findings suggest that in environments where methylated Hg may accumulate as a result of bacterial activity, the reverse reaction which leads to the removal of mercury through volatilization from the system, may be achieved by inducing genetic ?amplification and expression of the mercuric reductase gene system.

Jan 1, 1991

By R. F. Hammen

Heavy metal contamination of water is a problem of immense national and international proportions. However, effective cleanup is complicated both by the toxicity and the low concentrations of metals in wastewater streams. Using high performance chelation chromatography, the solid phase extraction and purification of extremely dilute metals from water was highly effective. The process is based on selective displacement of metals from a chromatographic column containing a chelating resin. The resin is characterized by extremely efficient adsorption kinetics which allow rapid and complete removal of the metals.

Jan 1, 1993

By Arpad E. Torma

The identification and characterization of lithographic iron and sulfur oxidizing bacteria in the 1940' s. opened up new possibilities and challenges for the mining and metallurgical industries. These were exploited during the 1950's and' 1960's, when it was demonstrated' that mining wastes and complex unused mineral resources could be economically treated by bacterially assisted heap and dump leaching processes?. During the 1970's this technology grew into a more structured discipline called "biohydrometallurgy". In the l980's efforts were devoted to the identification of a variety of organisms involved in naturally occurring leaching processes. Further efforts dealt with the elucidation, of leaching mechanisms; the leach ability of nickel, coban, zinc, and precious metals; the desulfurization of coal; and diverse biosorpion phenomena. The application of genetic engineering techniques for the improvement of microbial performance was also initiated?. Current trends in biohydrometallurgy include improvement of many of the techniques noted above, as well as application of leaching. technolog.ies to. environmental remediation scenarios. These activities afford considerable opportunities for research in the 1990's. For example, bioremectiation of abandoned mining and processing sites requires development of new and economically viable technologies capable of removing low concentrations of toxic metals from high volumes of solid and/or liquid wastes.

Jan 1, 1991

By I. B. Scorzelli

The aim of this paper is to make a detailed mineralogical characterization of a typical brazilian xenotime and zircon from the Pitinga Mine using SEMIEDS techniques, On the other hand, superficial pretreatments with HCI, HN03 and HF were done to evaluate the modifications on surface compositions and the morphology of the particles for flotation purposes, The studies showed that both xenotime and zircon present very small inclusions of thorite; zircon is strongly metamictizated given rise to malacon. The HF pretreatment deeply affected the morphology of the particles as well as the surface properties in relation to flotation.

Jan 1, 1996

By François Larouche

Since their commercialization in the early 1990s, lithium-ion batteries (LIBs) have become ubiquitous for powering a myriad of portable electronics. Their usage now extends to the automotive industry and stationary energy storage market. With an average life of 6.2 years and the strong demand, the volume of spent LIBs has increased exponentially, making recycling mandatory. Currently, recycling/ recovery of spent LIBs is limited in comparison to all other types of batteries. The current processes focus mainly on the recovery of the most valuable metals such as cobalt and nickel, leaving lithium and phosphate in a low value end-product. It is necessary that new advanced recycling technologies are developed for the recovery of spent LIBs both from an economic and environmental perspective. In this paper, the current R&D status of LIBs recycling is reviewed with the emphasis placed on hydrometallurgical processing opportunities for Li-ion and Li-solid state batteries.

By Samson Adeosun, Sanmbo Balogun, David Esezobor

"Iron and steel making processes give rise to large amounts of usable and unusable materials, the latter generally being termed wastes. It is sometimes difficult to distinguish between re-usable by-products and wastes which cannot be sold or land-filled. Much depends on circumstances such as the local market for the material. This can itself vary from time to time with by-products which cannot be used or sold becoming wastes and vice versa. This paper defines the concept of “waste-free technology”, discusses its development in the steel industry and highlights the benefits of the technology to the manufacturing sector and the environment. The paper also articulates how the “waste-free” technology could be applied in the proposed Ajaokuta integrated steel plant in Nigeria.IntroductionIn the past, nature was considered an inexhaustible store. Its resources were consequently exploited and waste products therefrom were discarded. Today, attitudes have not changed appreciably even as raw materials cost rise by the year to pose a series of socio-economic problems, which, among others, may include the rational and optimum utilization of resources, environmental protection and reduction of waste formation. Consequently, industrialists now face unexpected regulatory pressure in areas of pollution prevention, waste minimization and hazardous waste disposal.Iron and steel making processes give rise to significant amounts of usable and un-usable materials, the latter generally being termed waste. It is sometimes difficult to distinguish between re-usable by-products and wastes which cannot be sold or land-filled. Much depends on circumstances such as the local market for the material. This can itself vary from time to time with by-products which cannot be used or sold becoming wastes and vice versa. In this paper, the term waste refers to those materials that are either irrationally utilized or, land-filled and part of the byproducts that are not utilized. It includes that part of used materials which is not incorporated into the products manufactured during a process stage and which in contrast to reuseable materials, is considered not suitable for any further use, owing to technical or economic factors. In general, these materials are inorganic and parts of them are either utilized or passed to the other processes; the other part should be disposed of using well-established waste disposal practices to avoid any environmental threat.Thus, creative methods must be developed to modify the manufacturing processes to reduce emissions and process wastes by fully utilizing all resources. One method of eliminating the negative effect of waste formation is the use of purification and cleaning structures (pollution control system, PCS). These are, however, quite expensive."

Jan 1, 2008

By Ragnhild E. Aune, Mark William Kennedy, Shahid Akhtar, Jon Arne Bakken

"To determine the heating rate of billets using ‘short coils’, an appropriate correction factor must be applied to the theoretical relationship. In 1945, Vaughan and Williamson published a semi-empirically modified Nagaoka coefficient applicable for moderate frequency induction heating processes (10 kHz). Recently it was demonstrated that the method of Vaughan and Williamson gives <10% error in the estimated power when heating aluminum billets at 50 Hz.In the present study, experiments have been conducted on aluminum billets in order to verify an empirical frequency corrected ‘short coil’ equation. Measurements of electrical conductivity (<± 0.5%), current (± 1%), heat (± 1-3%), and magnetic flux density (± 1-2%) have been performed. The results are compared with 1D analytical calculations, and 2D axial symmetric FEM modeling using COMSOL 4.2®. The frequency corrected equation has proven to provide accurate predictions of power (<4% error) within the frequency range 50 Hz to 500 kHz.IntroductionInduction heating is commonly applied to the re-heating of billets before forging or extrusion processes. The resistive heating produced by eddy currents in the solid or semi-solid work piece during this procedure, is driven by the time varying magnetic flux density in the air-gap between the work piece and the coil. The flux in the air-gap is created by the current flowing in the induction coil, i.e. the magneto-motive force. In Figure 1 it can be seen that the currents present in the work piece are concentrated in the outer ‘shell’, or the first electromagnetic penetration depth (dw), and flow in a direction which opposes the magnetic field produced by the induction coil."

Jan 1, 2012

By Deyou Yin, Kongfang Feng, Bo Wang, Jieyu Zhang, Xin Hong, Shaobo Zheng, Jinyin Xie

"The flow patterns and mixing characteristics in a water model of C-H2 smelting reduction furnace are experimentally studied in this paper. Water modeling is employed to investigate the features of gas jet stirring and the fluid flow patterns in the bath of a smelting reduction furnace during the top, bottom, and side combined blowing process. The influence of the gas flow rate for top, bottom and side nozzles, angle, submerged depth of each side nozzles and the height of the top nozzle has been examined. It showed that the gas flow rate of side nozzles and bottom nozzle had a key role on the fluid flow and mixing characteristics. The gas jet from the top nozzle could change the agitation and fluid flow pattern caused by the gas jets from the side nozzles in the bath.IntroductionFacing the current natural resources decrease and the environmental degradation, smelting reduction iron-making technique is believed to be the most representative at present. Mid last century, the concept of producing liquid iron or semi-steel directly from ore fines and inexpensive fuel was the subject of considerable pilot plant development activity. Among these projects, the direct smelting process, which is the reduction and melting of iron-bearing materials by carbon and other hydrocarbons in the vessel containing a molten bath, is the most popular one. A number of direct smelting processes have been developed around the world, e.g. COREX, DIOS, HIsmelt, AISI, ROMELT, etc.These studies put forward a new technology, which through bottom nozzle blowing rich hydrogen, top nozzle blowing rich oxygen and provide preheating ore and solvent, side nozzles blowing oxygen-coal to realize smelting reduction iron-making process. Owing to the metallurgy reactions always in high temperature, which is above 1600 °C, it is difficult to visualize the mixing behavior and measure the desired phenomena in the reduction vessel. With water modeling, the primary advantages are that it is relatively easy to observe and measure the flow phenomena in the bath."

Jan 1, 2011

By N. J. Themelis

The basic chemical, thermal and transport principles that underlie sulfide smelting of. copper, nickel and lead are reviewed. Two basic types of modern smelting processes are distinguished?: flash-smelting, where the predominant reactions occur between oxygen-bearing gas and concentrate particles dispersed therein; and bath-smelting where the concentrate is enveloped and reacted in a turbulent bath of matte, slag and gas. The controlling heat and mass transfer phenomena are discussed, and appropriate correlations are proposed.

Jan 1, 1983

By P. J. Uggowitzer, H. Kaufmann

"New Rheocasting is a novel route of semi-solid casting, in which the globular semi-solid precursor material is produced by controlled cooling of only slightly superheated melts in conventional steel crucibles. The resulting semi-solid slugs are placed into the sleeve of a vertical Squeeze Casting Machine and then filled into steel dies. Solidification occurs under hydraulic pressures up to 100 MPa Due to the reduced cost of precursor material, reduced investment cost and easier recycling, the New Rheocasting process offers cost reductions of up to 25% over conventional semi-solid casting · routes. The New Rheocast products are pore free, pressure tight, weldable and heat treatable castings.In the present work the New Rheocasting Process is introduced and the influence of heat treatment on mechanical properties of the New Rheocast alloy A356 is discussed.The alloy A356 is cast under ideal New Rheocasting conditions into a step die on an UBE HVSC 350 Squeeze Casting machine. As-east, TS and T6 heat treatment conditions with variations in solutionizing and aging time/temperature parameters are applied and the samples are tested by tensile testing. Alternatively, the same heat treatment conditions are applied to conventional Squeeze Casting parts and compared with New Rheocasting.Questions of potential cost savings due to modified heat treatment conditions are also addressed in this paper."

Jan 1, 2000

By Satu Jyrkönen

A single-particle laminar-flow technique was used to study oxidation of four synthetic nickel mattes, which were screened into three size fractions, Experimental conditions were: reaction gas from N2 - 21 to 75 vol-% O2; gas preheating temperatures ranging from 500 to I 100&apos;C. The four mattes were synthesized so that Ni/Cu ratios of I and 10 were obtained with high and low iron contents. Chemical analysis of the particles was used to determine the oxidation degree of the materials, and optical and scanning electron microscopy were used to detect their morphology, internal composition and structure. The best sulfur removal from the synthetic nickel mattes was achieved under the most oxidizing conditions with the finest size fraction. The matte with Ni/Cu = 1 and high iron content was found to be most reactive. The least reactive matte was with Ni/Cu = 10 and low iron content; the coarse fraction particles did not react at all under the conditions studied.

Jan 1, 1996

By José D. T. Capocchi

Viscosity of liquid lead, tin, and Pb-Sn alloys has been measured by the rotational viscometer method in the temperature range from 50 K above their respective liquidus temperature to 823 K. The results are accurate to within ±1.0 %. The variation of viscosity with temperature followed the Arrhenius-type equation µ = µo.exp(Q/RT). The composition dependence of the isothermal viscosity and the activation energy for viscous flow have not shown anomalous changes at the eutectic composition of the Pb-Sn system.

Jan 1, 2000

By André Laplante

The mineralogy of the Joe Mann mine differs from that of other deposits of the Chibougamau area that are exploited by Les Mines Camchib Inc.. It is characterized by very fine first generation gold and very coarse second generation electrurn. Successful milling required adjustments of the processing flowsheet, which includes gravity, flotation, and cyanidation. A study of coarse gold liberation in the gravity/grinding circuit is described. Modifications to the flotation circuit and the reconditioning of a small capacity cyanidation circuit are presented. As a result of the circuit modifications, gold recovery increased from 65 to 81% in flotation and cyanidation. Overall gold recovery increased from 77% to 88-89%. These improvements are mostly attibutable to the recovery of -10 urn gold, whose presence in the Joe Mann ore and original circuit tails had been identified by process mineralogy.

Jan 1, 1989