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By R. David Prengaman

During the past several years a new insoluble lead anode has been developed for copper electrowinning. The new anode consists of a rolled lead-calcium-tin alloy sheet attached to a slotted copper bus bar by a soldering process which produces a complete metallurgical bond between bar and sheet. The metallurgical bond greatly reduces the resistance between the bus bar and the lead sheet and the high conductivity does not deteriorate during the life of the anode. The rolled anode thins uniformly and does not suffer preferential grain boundary or internal corrosion commonly seen in cast anodes. The lead-calcium alloy containing a high tin content corrodes slowly because the rolling process produces a uniform, fine grained structure. The wrought product is very strong and ductile; and contains no internal defects, segregation, cracks, or pores which can reduce the life of the anode. Because the anodes corrode uniformly, a high percentage of the anode thickness can be utilized thus extending the life of the wrought anodes. The anode alloy composition which is stable only in wrought form, produces exceptional resistance to passivation during current interruptions. First introduced into liberator cells, the new electrowinning anodes have been specified as the anodes of choice for every new SX-EW tankhouse constructed in the last two years. This paper describes the new anode, its method of construction, service history, and how it differs from present copper electrowinning anodes.

Jan 1, 1987

By T. Asahina, M. Nakamura, M. Mabuchi, I. Shigematsu, M. Nakanishi, G. Yamauchi

"Commercial stainless steels (SUS304L and SUS430) were subjected to equal channel angular extrusion (ECAE) at room temperature to a total strain of 2.3 to 9.2. For each type of stainless steel, it was shown that the sample processed by ECAE showed higher room temperature strength than the as-quenched sample. This is probably due to the heavily worked structure. On the other hand, both strength and elongation of the ECAE processed SUS430 were increased by annealing at 773K. It is likely that higher strength is attributed to both the heavily worked structure and fine substructures. It is also likely that higher elongation is attributed to the fine substructures. It is concluded that ECAE is available for improving the room temperature strength of commercial stainless steels.INTRODUCTIONEqual channel angular extrusion ( ECAE ) is a technique that provides the repetitive deformation and allows to high intensity of deformation. With this procedure, a sample is pressed through a channel that has an equal cross section but bent at an angle of ?> [1-2]. Shear strain is introduced when a sample passes through the bending point of the channel. Repetitive processing is feasible because the cross-sectional dimension of a sample has no change during processing. To date, many reports have described that ECAE is available for the fabrication of fine-grained materials [3-14]. On the other hand, an ECAE processed sample can achieve high intensity of deformation through repetitive deformation. According to the equation given by Segal [ 2 ], a strain of about 1 is introduced in each pass through die if the angle ? is 90 deg.It is well known that high tensile strength can be achieved in metallic materials through work hardening [15]. It is also known that metallic materials with fine grain size show high strength [16]. Hence, it is expected that ECAE is available for strengthening method in metallic materials. In the present paper, we will report the mechanical properties of stainless steels processed by ECAE. As samples, SUS304L austenite stainless steel and SUS430 ferritic stainless steel were chosen. Each alloy has a single-phase structure (fee or bee) and shows no phase transformation, so that transformation strengthening cannot be applied. Hence, a heavy cold work such as ECAE may be effective for strengthening of this stainless steel. Annealing was conducted for the ECAE processed SUS430 to vary its microstructure. Then, the effect of annealing on the strength of the ECAE processed SUS430 was also investigated."

Jan 1, 2000

By Akita Ito, Sumio Kato, Mikio Sugai, Shinichi Nakata

"Spark Plasma Sintering (SPS) is a newly developed method for the sintering of metal and ceramic powders, and completes their densification at low temperature and in short period. The SiC powder was synthesized from diatomite and graphite or carbon black by heating at 1 450°C for 1 hr in an argon atmosphere. The synthesized SiC powder was heated at 1500-1800°C, 50 MPa for 15-18 min by SPS. The relative density of sintered SiC body increased with the rise in the temperature. The oxidation of the surface of the SiC particle and impurities in SiC from diatomite greatly influenced the sintering promotion of SPS.IntroductionThe SiC has high hardness because of the covalent bonding, and is also excellent in thermal and chemical stability. However, it is difficult to obtain a dense SiC sintered body by the combustion heating-method. Therefore, the dense SiC bodies have been made by the use of additives and I or the hot pressing (HP) method.In this study, the SiC powder was synthesized by using diatomite of natural products and graphite, and carbon black of reagent as raw materials, and the relationship between the properties of SiC powders prepared at various synthetic conditions and the density of sintered body by SPS was examined."

Jan 1, 2000

By Kazutaka Kunii

It is invariably certain that after punching for IC Leadframes, scrap metal were generated. These seraps were re-dissolved and in order to use as raw material for leadframes, it is necessary to remove the Ni plating. In this study a simple method was developed for the removal of Ni plating by surface oxidation of Ni plating. For this purpose a fundamental study was carried out on the oxidation behavior of Ni plating. Results showed that by controlling the oxidation condition, a considerably high rate of Ni could be removed.

Jan 1, 1996

By David J. Krichten

A method of retrofitting air-fuel burners with oxy-fuel capability overcomes the potential problems associated with oxygen combustion in aluminum melting furnaces. The retrofit burner uses the existing combustion air connection, burner housing, and burner tile and replaces the gas tube with an oxy-gas burner. Maintaining a portion of the air flow to the burner reduces the potential for localized overheating. Proper design of the burner reduces NOx emissions by moderating the flame temperature with furnace gas recirculation. Economic analysis of using oxygen shows the benefits are increased productivity and reduced overall unit cost of melting. In practice, the melt rate in rotary furnaces increases by up to 50% and by up to 35% in reverberatory furnaces. Oxygen utilization reduces total melting cost by 112-314 cents per pound of aluminum melted.

Jan 1, 1997

By Thomas Buenger

The Hamburg smelter of Norddeutsche Affinerie AG is situated near the city of Hamburg’s downtown and is therefore particularly subjected to fulfill environmental requirements according to the German legal regulations. Thus, investments related to increasing concentrate throughput are always linked to packages to enhance the emission status of the smelter. This connection between environmental protection and productivity enhancement should be explained by the example of the Peirce-Smith converter plant of the Hamburg smelter. Such outstanding investments can be demonstrated by the transition from scrap charging via boat from the front side to a fully automatic and completely sucked scrap charging system.

Jan 1, 2009

By R. Gampala

The consolidation of mom matrix composite monotapes occurs by the plastic (time independant) and creep deformation of monotape asperities. Past models of the process used seperate micromechanical analyses of the contact deformation by (rate independent) plasticity and power law creep (i.e steady state creep). These models are now used to simulate consolidation and to optimize/control consolidation process cycles so that the composite's microstructure is "steered" to, a user defined goal state. However, the models do not incorporate the sometimes dominant transient creep process and the instantaneous response of the plasticity mechanism causes finite discontinuities in the microstructure state vector field and therefore eliminates the possibility of using the powerful array of trajectory optimization schemes that all require continuous vector field for optimization and control. To overcome this problem, a inified creep/plasticity constitutive model that results in a continuous state vector field is used to rederive the contact deformation response during monotape consolidation. The contact blunting of a laterally constrained hemispherical asperity is first analyzed and its response represented by two coefficients; one relating the contact area to the blunting strain (C), the second, the mean contact pressure to the blunting rate (F).The C and F coefficients for this unified blunting problem are then obtained by finite element analysis, and detailed results presented for two composite matri-ces of topical interest (Ti-24A1-11Nb and Ti-6Al-4V).

Jan 1, 1996

By E. A. Werner, A. Pichler, A. Spalek, G. Reisner, P. Stiaszny

"Interstitial free (IF) sheet steels are used for complex shaped parts because of their excellent formability. If a deep drawn part is subjected· to a impact deformation at low temperature brittle fracture of the part may occur. This phenomenon\ is called secondary work embrittlement (SWE). One possibility to characterize this material/structural behavior is the drop-weight test. The result of .this .test is a temperature at and below which a crack can initiated in a deep drawn part under the investigated set of parameters. This paper addresses the influence of the preforming process on the sus- . . ceptibili.ty of IF steels to SWE.IntroductionInterstiiial:free (IF-) steels are frequently used in the automotive industry for complex· shaped p·arts because of their excellent deep drawability. The microstructure of the steel consists of a highly ductile ferritic matrix with embedded precipitates of nitrides and/or carbides. Brittle fracture can occur in deep drawn parts, if they are subjected to a high speed deformation at lo""w temperature. This phenomenon is called ~econdary Work gmbrittlement (SWE) [1-11]. Up to now there are no standardized testing procedures available to quantify the sensibility of IF-sheet steel to SWE. Neveitheless, a reasonable testing procedure which allows to quantify the tendency of a predeformed part to SWE is necessary for further material development. A commonly used test method is the drop-weight test performed at low temperatures. In such ·tests a cone-like drop weight expands a deep drawn cylindrical cup [l-3, 6, 8, 9, 11]. From this expansion experiment the temperature is determined at and below which a brittle crack can be initiated in the deep drawn cup under the investigated impact test parameters. The highest measured temperature at which a deep drawn cup fails by brittle fracture is called frack appearances !emperature (CAPT). The lower the value of the CAPT the lower is the sensibility of a deep drawn part of IF-sheet steel to SWE. This paper aims to clarify the role of the preforming process on the impact behavior of an IF steel. For this purpose a numerical analysis of the deep drawing process and cup expansion tests are conducted."

Jan 1, 2000

By Wen-Ming Chien, Vamsi Krishna Kamisetty, Amrita Mishra, Ivan Gantan, Prathyusha Mekala, Dhanesh Chandra

"The phase equilibrium and characterization studies by using high temperature X-ray diffraction (XRD) and differential scanning calorimetric (DSC) methods have been performed for binary organic thermal energy storage materials. The organic thermal energy storage materials undergo a solid-solid state phase transition before melting which stores large amounts of thermal energy. Two materials [tris(hydroxymethyl)aminomethane(TRIS) and 2-Amino-2-methyl-l, 3- propanediol(AMPL)] were used for this study. Binary samples of AMPL-TRIS were prepared to perform high temperature XRD characterization and DSC studies and the binary AMPL-TRIS phase diagram was developed. The high temperature solid-state phases of AMPL and TRIS were characterized as a disordered BCC structure. It was found there is virtually no solubility of TRIS in AMPL or vice versa below -75 °C. The maximum solubility of TRIS in AMPL is 11% TRIS at 75 °C. The eutectoid transformation was shown at 19%TRIS-81%AMPL composition and at a temperature of 75°C. Lattice expansion calculations on single phase of TRIS and AMPL have been performed.IntroductionThermal energy storage materials can store a large amount of heat due to the presence of thermal transitions from the orientationally ordered to disordered phases occurring before melting. These molecules (such as amine and alcohol derivatives of neopentane) can reorient as a whole about the central carbon atom to form orientationally disordered crystals (ODIC) and their spherical shape makes them reorient relatively easier. Thermal energy storage materials are becoming increasingly important as a renewable energy resource. These molecules undergo large changes in enthalpies at solid-solid transitions. The presence of these compounds with large enthalpy changes are identified as potential thermal energy materials and some of die applications are solar cell systems [1-3]. Binary mixtures have been found as a way to adjust the transition properties in addition to pure compounds [4]. Tris(hydroxyrnethyl)aminomethane (TRIS, C(CH2OH)3NH2) and AMPL, CH3C(CH2OH)2NH2) are two important thermal energy storage materials."

Jan 1, 2012

By David Goodman

The typical operating conditions in Solvent Extraction plants are presented. The various materials of construction used for solvent extraction equipment are reviewed and the history of their use presented. The properties of the materials in common use today, stainless steel, thermoplastics and fiber reinforced plastics, are compared together with cost data. The manufacturing and construction aspects of these materials are discussed.

Jan 1, 2003

By Thomas Gliick, Jianming Lu, David Dreisinger

"The recovery of manganese from the Boleo project of Baja Mining is via an acid oxidation and acid reduction process in seawater. Manganese as manganese dioxide is leached into solution as manganese sulphate with the addition of sulphur dioxide gas as a reductant and then precipitated as a manganese carbonate. The use of the manganese carbonate intermediate to produce electrolytic manganese metal (EMM) has been extensively studied. The manganese carbonate can be used in place of natural (MnC03) or reduced ores (MnO) of manganese as a feed to the EMM plant. Manganese carbonate can be dissolved in spent electrolyte from manganese plating, followed by purification using ammonium sulphide precipitation of minor elements and then electrowinning in a selenium free process. The results of small cell testing of manganese electrowinning are reported.IntroductionThe Boleo Project of Baja Mining is a greenfields development currently under construction approximately 5 km north of the town of Santa Rosalia, Baja California Sur, Mexico. The Boleo property is held by the Mexican company, Minera y Metalurgica del Boleo S.A. de C. V. (MMB). MMB is owned 70% by Baja Mining Corp. and 30% by a consortium of Korean companies consisting of KORES - Korea Resources Corporation, LS Nikko Copper, Hyundai Hysco, SK Networks and lljin Copper.The Boleo deposit has Measured and Indicated resources of264.7 million tonnes grading 1.50% copper equivalent (CuEq) & Inferred resources of 159.9 million tonnes grading 1.15% CuEq. The calculation of copper equivalent is based on a combination of metal prices and predicted metallurgical recoveries (Table I). The metallurgical recoveries have been confined by extensive bench and pilot plant testing. Proven and probable reserves are available at Boleo to provide for more than a 30 year mine life. Initially, 25 years of mine life and 23 years of process plant operation have been scheduled in the February 2010 Technical Report Update (www.sedar.com)"

Jan 1, 2012

By Hongmin Zhu, Guihua Wang, Xiangsheng Wang

"The anode process of carbon electrode in fluoride melt was studied by voltammetry and chronoamperometry. Anode gases were analyzed by gas chromatography on-line during controlled-potential electrolysis. Two peaks were observed on the cyclic voltammograms. According to the results of gas chromatography, the first peak was corresponded to the discharge of residual oxide ions, with the formation of CO and CO2. Discharge of fluoride ions occurred at 4.1 V vs. Li+/Li, and leading to the anode effect. With the occurrence of anode effect, small amount of CF4 was detected. As the potential reached 4.5 V, CF4 and C2F6 gas evolution occurred, and the current increased to form the second peak.1.IntroductionIn the primary production of Aluminum and some rare earth metals like neodymium, a departure from normal cell operation known as anode effect results in the generation of perfluorocarbons (PFCs), which have high global warming potentials [1]. Owing to the pressure of environmental protection, considerable research has been carried out to clarify the mechanism of anode effect and PFC generation of industry and laboratory cells in the aluminum electrolysis system [2-9]. The common result on PFC generation is that the PFCs are emitted from Hall-Heroult cells only when they are on anode effect. In this article, we selected LiF, the main electrolyte for the neodymium electrolysis [10-11], to perform further investigation on the underlying kinetics of PFC generation and the nature of the reactions at the electrode.2. ExperimentalAll experiments were carried out in an alumina tube reactor, which was filled with high purity helium atmosphere. Spectrographic graphite crucibles were used, which played the dual role of molten fluoride container and the counter electrode. Lithium fluoride was analytical grade. The experiments were carried out at 900 °C."

Jan 1, 2011

By Lijun Liu, Yingwei Li, Jianhua Liu, Jinhui Peng

"As essential equipment in the metallurgical industry, current air heat exchangers cannot meet the requirements of high temperature heat transfer. In this paper, an energy efficient air heat exchanger, based on accumulation of the heat generated by microwave absorbing materials, is presented according to heat transfer theory and principles of the microwave field. A tubular shaped heat exchanger was designed and built up through temperature-rising curve, and experimental research of microwave high-temperature air heat exchangers was carried out. It was found from experiments that the tubular shaped heat exchanger fabricated using material B could be used for high temperature heat transfer system, and equilibrium temperatures could reach up to 457—485?.IntroductionHeating or cooling of air by heat exchangers is commonly practiced in a wide range of industries including construction, chemical, machinery, textile, printing, and dyeing [1-3]. Generally such heating or cooling of air is achieved in pipe heat exchangers. There are several drawbacks for such heat exchangers, namely, (i) the limitation of temperature to which the pipes can be heated, (ii) tendency to oxidize at high temperature, and (iii) poor strength of metallic pipes at high temperature. These limitations do not allow pipe heat exchangers to be operated at high temperatures [4-6].Microwave heating of inert solids, which are stable at high temperature, is a possible solution to achieve high temperature of the medium in air heat exchangers. It is well-known that microwave heating is an efficient, clean, safe, easy-to-control heating method. Microwave heating utilizes the dielectric and magnetic properties of a material. When microwaves penetrate and spread into the dielectric material, electrons, ions, etc move in the internal electromagnetic field, while the elasticity of inertia and friction impede these movements. This results in a significant thermal effect, increasing the surface temperature rapidly [7-8]. This paper studies mainly design and experimental research of microwave high-temperature air heat exchanger."

Jan 1, 2011

By K. Knuutila

The behaviour of thiourea, animal glue and chloride ions in the electro¬lysis of copper has been investigated by various different electrochemical experiments, i.e. polarization curves with stationary copper electrodes, long-time galvanostatic electrolyses and Hull cell experiments. Polarization curves with stationary copper electrodes show that animal glue has a polarizative effect on the deposition potential. Small thiourea contents affect depolarizatively when high concentrations retard the copper deposition. The microstructures of the deposited copper after the long-time electrolyses show that animal glue favours a basis oriented deposition structure. With thiourea the field orientated structure was evident. It was also observed that the deposited structure depended much on the grain structure of the starter sheet. The chloride ion concentration has a drastic effect on. the crystal size of the deposited copper as it was found out in Hull cell tests. Chloride ions flattened the the crystals and the deposition became smoother when the chloride ions were added. The cathode copper quality is discussed according to the literature. Special attention is paid on the codeposition of thiourea and the origin of sulphur impurities in copper cathodes.

Jan 1, 1987

By S. P. Marsh, D. Banerjee

"Casting processes involve phenomena that occur on widely disparate length-scales. Simulation of macroscopic effects, such as heat transfer and convection, are generally addressed by solving the appropriate equations in discretized form on a finite-element mesh. Microscopic phenomena are described by micromodels that may be empirical or analytical in form. Coupling of phenomena in these two regimes is a critical issue in predicting microstructure and defect formation resulting from macroscopic process conditions. A formalism has been developed for expressing micromodels in a consistent manner using stereological parameters to quantify the geometric characteristics of the developing microstructure. This approach provides a robust and physically consistent method for coupling local micromodels with the macroscopic fields. The macroscopic state variables at each node serve as global constraints on the micromodels that are applied to a local unit volume. An outline of an equiaxed solidification model based on this approach is presented, along with preliminary simulation results. Coupling of convection and enthalpy effects between the micro and macro regimes is also discussed. IntroductionThe primary goal of casting simulations is to improve the reliability of cast parts while minimizing cost and development time. Effective simulations can speed up the mold design process and reduce the likelihood of defective parts by refining a particular casting process on a computer, reducing the dependence on cost- and time-intensive prototype castings. The challenge in developing effective simulations stems from the need to address physical processes that occur over a wide range of length-scales, from microscopic (atomic) and mesoscopic (microstructural) scales to macroscopic distances comparable to the size of the casting itself. Overviews of the various thermophysical phenomena and computational factors that are important in solidification modeling are provided in the literature by Rappaz [1] and Tseng et al. [2].Macroscopically, the solidification process is largely governed by the rate of heat flow from the alloy through the mold wall. Another important effect that occurs on the scale of the casting size is convective flow of the melt, which is driven by density-variations in the melt. Macroscopic calculations employ finite-element or finite-difference methods to solve the sets of equations that govern these effects, and the spatial resolution is determined by the grid spacings used for the calculations. Typical spatial resolutions are on the order of 10-2 to 10-3"" meters. This represents a compromise between the resolution required to simulate the continuum transport processes accurately, and the computational time required to model the entire solidification and cooling process."

Jan 1, 1994

By Riyad N. Ahmad-Bitar, Shadia J. Lkhmayies

"CdSi-xTex thin films were prepared by first producing CdS:In thin films by the spray pyrolysis (SP) technique and then annealing the films in the presence of Te vapor in nitrogen atmosphere. X-Ray diffraction (XRD) measurements showed that the films are polycrystalline with the wurtzite structure. Transmittance measurements were recorded at room temperature in the wavelength range 400-900 nm and used to deduce the absorbance. The first derivative of the absorbance was calculated and used to find the values of the bandgap energy, where more than one bandgap was obtained for each film. These results show that the films are inhomogeneous or the composition differs with location. The photoluminescence (PL) was recorded at T = 60 K and a deconvolution peak fit was performed for each spectrum. The results of the PL spectra are consistent with those obtained from the first derivative and confirm the inhomogeneity of the films.IntroductionPolycrystalline thin film CdS/CdTe solar cells are promising candidates for low cost and high efficiency photovoltaic applications. The CdS/CdTe interface plays an active role and a detailed knowledge of its properties is crucial for thorough understanding of the device. High efficiency devices have been obtained in spite of the large lattice mismatch (9. 7%) between hexagonal CdS and cubic CdTe. Interdiffusion at the CdS/CdTe interface is considered to affect the performance of the devices [1]. The formation of a mixed crystal or a graded layer at the interface causes a reduction in the lattice mismatch at the CdS/CdTe junction [2] and then a reduction in the number of interfacial states and recombination centers, thus enhancing the solar cell performance [3, 4].The objective of this work is to investigate the transmittance, photoluminescence (PL) and structure of CdSi-xTex thin films prepared by annealing the spray-deposited CdS:In thin films in the presence of tellurium vapor. X-ray diffraction (XRD) was used for exploring the structure. Transmittance is used to deduce the absorbance where its first derivative was used to find the bandgap energy which varies with composition. The evolution of the PL spectra as functions of tellurium concentration was evident and it confirmed the inhomogeneities of the films."

Jan 1, 2011

By Animesh Jha

Univariant diagrams are constructed for the reduction of nickel and cobalt oxide and sulphide minerals. The results from the carbothermic and hydrogen reduction of sulphide minerals are compared. The importance role of lime and calcium sulphate in controlling the emission of sulphurous- gases during reduction reaction is also explained. The mechanism of carbothermic reduction of nickel sulphide is explained by examining the sulphur exchange and reduction reactions. The phase equilibrium relationships that determine the formation of multicomponent liquid are characterised. Also the governing equilibria for inert atmosphere calcination- roasting of nickel and cobalt sulphide minerals are also described for the metallization of nickel and cobalt.

Jan 1, 1993

By L. J. Lutz

The U.S. Bureau of Mines has developed an electrorefining process to recover Ni, Co, Cr, and other metals from mixed and contaminated superalloy scrap. The superalloy scrap is cleaned then directly electrodeposited as a Ni -Co deposit. The process recovers approximately 90 pct of the Ni-Co available from the scrap as a 99t pct pure Ni-Co alloy. During electrorefining the electrolyte undergoes a purification process which results in Cr and other refractory metals reporting to the purification residue. Operating data is given for a 3-L compartmented electrolytic cell. Techniques for the removal of Fe, Cr, and trace impurities from the recycled electrolyte are outlined. The economics of a facility producing 15 mt/d of a Ni-Co alloy are also discussed.

Jan 1, 1993

By Edward P. Hagarty

The Hazardous and Solid Waste Amendments (HSWA) of 1984 added Subtitle I to the Resource Conservation and Recovery Act (RCRA), authorizing the Environmental Protection Agency (EPA) to develop and implement a new regulatory program for Underground Storage Tanks (USTs) containing petroleum and other regulated substances. Technical standards required for release detection, prevention, and correction as necessary to protect human health and the environment were promulgated as described in 53 Federal Register 37082 (September 23, 1988). Virginia State Regulations (VR 680- 13-02) and U.S. Army Regulations require that a Corrective Action Plan and a Site Clearance Report be prepared to explain the details of remediation of any contaminated media. Construction of new buildings is proposed in two different areas at Fort Myer in Arlington, Virginia, where USTs containing gasoline, diesel and heating oil were located. Tightness testing performed on these USTs in September 1991 indicated that some of the tanks were leaking. Many of the tanks were removed for permanent closure. Initial Abatement (excavation of contaminated soil) was &ed out immediately. A detailed Site Characterization Study which included Hydropunch", field screening using immunoassay, and pilot test - dual phase (water and soil gas) extraction was conducted. Environmental media were analyzed for volatiles, semi-volatiles and metals. A detailed risk analysis (RA) was performed to determine risk-based clean up levels for benzene, toluene, ethylbenzene, xylenes (BTEX); polycyclic aromatic hydrocarbons (PAHs); and methyl-tertiary butyl ether (MTBE). The RA also discussed the presence of lead in the soil. Before constructing any buildings in these contaminated areas, remediation must be conducted in accordance with the State, Federal and other applicable regulations. The remedial alternatives evaluated included Vapor Enhanced Groundwater Extraction, Soil Vacuum Extraction, Soil Washing, Soil Steaming, Active and Passive Ventilation SolidificationlStabilization, Vapor Barrier Construction, and Excavation with Off-site Disposal. This paper discusses: (a) delineation of soil contamination @) risk analysis (c) evaluation of remedial alternatives and selection of the most appropriate technology and (d) consideration of various regulatory issues.

Jan 1, 1994

By Walter E. Dean

Twenty six samples of carbonaceous gold ores and associated rocks from outcrop and mine localities in northcentral Nevada were analyzed for concentrations of major. minor, and trace elements, total sulfur, and organic carbon. Q-mode factor analysis was used to define six distinctive carbonate, organic, and detrital associations of elements, and to group samples based on these associations. The trace metals that have clearly enriched the organic-carbon-rich samples are V, Zn, Ni, Cu, Cr, and Mo, although few of the samples could be considered "metal-rich" when compared to other organic-carbon-rich black shales. Rock-Eval pyrolysis was used to evaluate thermal maturity and hydrocarbon yield of the samples. Unfortunately, most samples were too thermally altered to be suitable for routine organic geochemical characterization of organic matter. The 813C values of organic carbon in rocks from different deposits have a trimodal distribution, but there is no clear distinction between the three groups of deposits that can be related to age, thermal history, or depositional environment.

Jan 1, 1987