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By Hans Hein

In its early stage of copper solvent extraction development, SX plants were designed in a series configuration and gradually the copper industry reduced staging and trains for keeping capital investments reasonably low. At a later date of its development, series parallel configuration was applied in some copper SX plants, particularly for increasing copper production at low copper tenor in pregnant leach solution. A gap between series and series parallel configuration had been observed for years. Conventional SX plants in series configuration frequently do not have the flexibility for maintaining designed or expected production level, whenever copper concentrations in pregnant leach solutions are getting low, whereas series parallel flow schemes almost require to double SX feed flows for achieving optimum results. A combined SX configuration breaks the gap and its application potentials are explained.

Jan 1, 2003

By G. Azimi

Calcium sulphate precipitation, mainly as gypsum, during neutralization of acidic hydrometallurgical process solutions can lead to excessive scaling problems. In this work, a self-consistent fundamental chemical model is presented based on the OLI software platform. The model employs the new Mixed Solvent Electrolyte (MSE) activity coefficient model of OLI. A thermodynamic database has been developed and calibrated on experimental data from metal sulphate solutions. The model predicts very well the solubility of calcium sulphate within a wide temperature range and can be used to assess the scaling potential of a particular process stream composition. The effect of temperature, acidity, and divalent metal concentration on the solubility of calcium sulphate in multi-component process streams is also simulated and discussed.

Jan 1, 2006

By Jim Hardy, Tim McKnight

"The thermal mass flow controller, or MFC, has become an instrument of choice for the monitoring and controlling of process gas flow throughout the materials processing industry. In the semiconductor industry, these MFCs are used on over 70% of the processing tools. Reliability and accuracy are major concerns for the users of the MFCs. Calibration and characterization technologies for the development and implementation of mass flow devices are described. Sources of inaccuracy in process gas handling are described, and a model to correct for these inaccuracies is outlined. A gravimetric calibrator is described that allows flow sensors to be calibrated in corrosive, reactive gases to an accuracy of 0.3% of reading, at least an order of magnitude better than previously possible. All described capabilities are implemented in a Department of Energy User Facility which is available to industry and universities to test and develop gas flow sensors and controllers and evaluate their performance related to environmental effects, reliability, reproducibility, and accuracy.IntroductionMaterials processing is at the heart of semiconductor manufacturing. To make today's advanced integrated circuits, silicon wafers are subjected to over 200 process steps. Most of these steps involve processes such as etching, implanting, diffusion, annealing, deposition, and lithography (resist deposition and hardening). Often one or more process gases are used to complete the process step. To achieve the quality and performance required in the micro devices, accurate measurement and control of these gases is essential. The Oak Ridge National Laboratory (ORNL), in conjunction with the semiconductor industry, has been working to improve process gas measurement and control accuracy and reliability. Standardized test methods have been developed to characterize and benchmark the performance of mass flow controllers (MFCs), the method of choice for monitoring and controlling gas delivery. Testbeds have been designed and fabricated to produce repeatable and accurate data using these standards. Baseline testing was performed along with development of a unique mass flow instrument, the gravimetric calibrator."

Jan 1, 1997

By M. C. Ruiz

The leaching behavior of chalcopyrite concentrate in acidic CuC12-NaCI-O2 solutions was investigated. Experiments were conducted under continuos flow of oxygen at atmospheric pressures. The results indicated that among the variables temperature has the largest influence on the dissolution of chalcopyrite in this medium, and high copper extraction can only be obtained at temperatures near the boiling point of the solution. It was also found that the stirring speed did not influence appreciably the dissolution of chalcopyrite. An increase in the oxygen flow rate up to 0.1 1/min increased the copper extraction. The total chloride concentration affects the dissolution of chalcopyrite up to about 4 M. Copper extraction of 93 % was obtained in leaching chalcopyrite of size fraction -400 # Tyler at 105 OC in 2 hours.

Jan 1, 1997

By Yunnen Chen

In the present study, waste materials like pine sawdust and spent grains were investigated to assess their potential for removal of cobalt ion from water by the process of biosorption. The effects of solution pH, reaction time and initial concentration were studied in batch experiments. The removal efficiency of Co(? ) by spent grains was higher than that of pine sawdust. The initial removal was rapid and equilibrium was established in less than 90 min. Equilibrium data all agreed well with both Langmuir and Freundlich isotherm models for the two metal-biomass sorption processes. Good correlation coefficients were obtained for the pseudo second-order kinetic model. Pine sawdust and spent grains were shown to be promising biosorbents for Co(? ) removal from aqueous solutions.

Jan 1, 2010

Based on experimental and computer simulation results from our group, we report a systematic, atomic level analysis of carbon dissolution from carbonaceous materials in molten iron. Experimental results on graphite / Fe-C-S system were obtained using carbon dissolution studies, XRD and FESEM investigations and were supplemented with Monte Carlo simulations. Three basic mechanisms, namely carbon atom dissociation rate, interfacial phenomena and mass transfer in the melt were found to be responsible for the overall dissolution process. While mass transfer in the melt is governed by the concentration gradients, melt composition and temperature; impurities present in ash play a significant role in the interfacial phenomena. For less ordered forms of carbonaceous materials, carbon atom dissociation rate depends strongly on the degree of long-range order and is an important rate controlling mechanism in the overall dissolution process. A systematic comparison of dissolution rates for a variety of coal-chars, natural and synthetic graphites has been carried out in an attempt to identify rate-controlling mechanisms. The structure of the carbonaceous material appears to be an important underlying factor in the carbon dissolution process.

Jan 1, 2003

By J. W. Ahlrichs

In gold exploration and metallurgical testing, the role of the mineralogist is to assist in solving problems with regard to (a) sampling, (b) gold occurrences, and (c) petrologic classifications of host rocks. The presence of "coarse" gold as a sampling problem can be overcome by various methods, including "screen fire assays," screened analyses and special gravity techniques which may be used to determine distributions of "coarse" versus fine gold. Determinations of mineralogic associations of gold usually require special separation techniques, accompanied by fire-AA-mineralogic assays of the products. After accurate mineralogic analyses are obtained for various products, quantitative distributions of refractory gold associations can be calculated by the use of simultaneous equations. Petrologic classifications are required by the geologist for mapping and interpretation of the various rocks. After the petrology and mineralogic differences of the rock units are determined, x-ray diffraction analyses of analytical pulps can be used for lithologic logging of drill cores. XRD logging is an efficient method for correlating lithologic units and alteration trends throughout a gold prospect.

Jan 1, 1981

By P. M. Swash

The paper describes the use of mineralogical methods in the exploration and evaluation of primary diamond occurrences. The most common methods that are used include the systematic search for kimberlitic indicator minerals, surface textural study of the indicator minerals, (garnet, spinel, ilmenite and chrome diopside) and alluvial macrodiamond studies so as to understand their provenance and guide exploration towards diamondiferous targets. The mineral chemistry of the indicator is used to positively assess the origin of the mineral grains and is also pivotal in the determination of the diamond potential of a deposit. Petrography of the primary deposit is able to identify the body to be kimberlitic and is also a support to the mineral chemistry findings. Unambiguous proof of a prospects potential to contain macrodiamond is proven by the occurrence of microdiamonds in the residues from the rock. The presence of a sufficient number of microdiamonds in the rock is enough to determine a semiquantitative grade estimate and warrant further metallurgical evaluation so as to determine its actual macrodiamond content.

Jan 1, 1991

By Xue Wang, Callie Babbitt, Chelsea Bailey, Matt Ganter, Gabrielle Gaustad, Brian Landi

"Current trends, motivated by fossil fuel dependence and unprecedented greenhouse gas (GHG) emissions, show lithium-ion batteries (LIBs) emerging as a competitive energy storage technology due to higher power and energy densities compared to Pb-acid and Ni-metal hydride chemistries. These trends may be of concern, however, as environmental impacts are not well understood for either the LIB itself, or for the nanoparticles consumed or released during the battery's production, use, or end-of-life. This study combines economic modeling, dynamic material flow analysis, and fundamental material characterization methods in order to quantify some of the economic and environmental trade-offs for LIBs at their end-of-life. As expected, results show that as chemistries transition from Li-Co based cathodes to Li based Fe, Mn, and S cathodes, LIB recovery value correlates to the value of the raw materials used. These initial results aim to inform collection policies being proposed currently as well as enable future deployment of novel recycling techniques.IntroductionGlobal fossil fuel dependence and unprecedented GHG emissions have led to increasing attention on energy alternatives, for both electricity production and personal transportation. However, development of renewable energy systems is contingent on concurrent technological development of energy storage systems, primarily batteries used for power grid load-leveling, renewable energy storage, and hybrid and battery electric vehicles. In this sector, lithium-ion batteries (LIBs) are emerging as a competitive technology due to higher power and energy densities compared to lead-acid and nickelmetal hydride chemistries[!]. LIBs represent close to 20% of the total rechargeable battery market and 75% of the portable rechargeable battery market, which is the fastest growing segment of the rechargeable battery market, with a 20% global growth in 2008 [2].This surge in production ofLIBs indicates a looming waste problem; total waste from Li-ion batteries has likely grown substantially from the 500 metric tons estimated in 2003 [3]. Figure IA shows the substantial increase in world-wide lithium production that has occurred in the last several decades with batteries making up the largest share of applications (Figure lB). California and New York state legislators have attempted to proactively address this looming waste by issuing diposal bans on rechargeable batteries in their states[4, 5]. However, quantification of the costs involved in collection, transportation, and processing of these materials has not been examined in depth."

Jan 1, 2012

By J. A. Eisele

There is currently much interest in how extraction of gold and silver from ores with acidic thiourea solution compares with extraction using alkaline cyanide solution. Agitation leaching tests were performed by the Bureau of Mines on 14 precious metal ores using sodium cyanide (?NaCN) and thiourea [(NH2)2CS) as extractants. The objective was to compare the results of the two extractants. NaCN was used at a concentration of 2 g/L with and without H202 as an oxidant. (NH2)2CS was used at concentrations of 2 and 20 gjL, and the solution potential was controlled at 390 to 420 mV standard hydrogen electrode (Eh) with Fe2(S04)3. With both reagents a.t 2 g/L extractant levels, NaCN extracted more gold and silver than (NH2liCS from all of the ores. At 20 g/L (NH2)2CS compared with 2 g/L NaCN, (NH2)2CS extracted more gold than NaCN from two ores, the same amount from one ore, and more silver from one ore. NaCN extracted more gold than (NH2 )2CS from 10 ores and more silver from 4 ores.

Jan 1, 1989

Based on experimental and computer simulation results from our group, we report a systematic, atomic level analysis of carbon dissolution from carbonaceous materials in molten iron. Experimental results on graphite/Fe-C-S system were obtained using carbon dissolution studies, XRD and FESEM investigations and were supplemented with Monte Carlo simulations. Three basic mechanisms, namely carbon atom dissociation rate, interfacial phenomena and mass transfer in the melt were found to be responsible for the overall dissolution process. While mass transfer in the melt is governed by the concentration gradients, melt composition and temperature; impurities present in ash play a significant role in the interfacial phenomena. For less ordered forms of carbonaceous materials, carbon atom dissociation rate depends strongly on the degree of long-range order and is an important rate controlling mechanism in the overall dissolution process. A systematic comparison of dissolution rates for a variety of coal-chars, natural and synthetic graphites has been carried out in an attempt to identify rate-controlling mechanisms. The structure of the carbonaceous material appears to be an important underlying factor in the carbon dissolution process.

Jan 1, 2003

By H. Kandemir

An experimental study of the bacterial oxidation of naturally occurring high-purity sulphide minerals (FeS2, Fe1-xS, Cu5FeS4, ZnS) is presented using a mesophilic strain of T. ferrooxidans. As well as metal analyses and solution pH, partitioning of sulphide sulphur into elemental sulphur and sulphate has been monitored as a function of leach time. Partially oxidized sulphide substrates have been characterized, at regular time intervals, by X-ray diffraction methods and extracellular organic compounds reporting into leach solution .have been identified by thin layer -chromatography.

Jan 1, 1985

By Anne Kvithyld

Silicon solar cells, that convert the energy of sunlight into electric energy, are attractive sources of energy. In the production line wafers of solar cells are sliced from a multicrystaline ingot solidified unidirectionally. Recycling scrap from top and sides of such ingots is addressed. SiC and Si3N4 inclusions are a major problem. Scrap from Scan Wafer ASA is melted in a high vacuum furnace at around 1500ºC. The filters, from commercial producers, are C and SiC with 10, 20 and 30 ppi. Characterisation of inclusions before and after filtration, and in the filter itself, is performed by microscopy. Dissolution of silicon in acid and counting of the un-dissolved inclusions is also carried out. In the filter Si3N4 needles and SiC inclusions were identified. The amount of these inclusions in the filtered silicon is much less than in the input. In conclusion, filtration using SiC and C filters in vacuum system in argon atmosphere removes SiC and Si3N4 inclusions from solar cell scrap. Flow of metal through the filters is not a problem. These results are promising with scale-up to industrial application in mind.

Jan 1, 2006

By Niels Verbaan, Ralph Fitch, Charlotte Forstner, David Dreisinger

A process has been developed to extract gold, silver, indium, gallium, lead, copper, zinc, and other metals from a large resource using an oxidizing acid chloride heap leaching technology. The ore is crushed and/or ground to improve reactivity and then contacted with a solution containing NaCl-HCl-NaOCl. The value metals are leached into solution as chloro-complexes. The leachate is treated in a series of separation and recovery processes to produce separate saleable or disposable products. The paper will provide a summary of process development and application to a silver-indium ore from Bolivia. The possible application of the process to other ore types will be presented for discussion.

Jan 1, 2015

By Osamu Iida

In the Mitsubishi converting furnace (C-furnace), molten matte continuously undergoes intensive conversion into blister, and an excess amount of heat is generated, even after taking into account heat loss from the furnace, off-gas, and latent heat of melt. To absorb excess heat in C-furnace, recycled granulated converting slags (C-slag) were wastefully charged in the C-furnace. In contrast, supplementary coal is necessary to make up a shortage of reaction heat in Smelting furnace (S-furnace). To utilize the excess heat of the C-furnace effectively and accommodate the unbalance of heat utilization between S and C furnaces, three technological innovations had been carried out. ? Spent anode charging facilities in C-furnace was modified, in order to solve some spent anodes hitting and eroding the hearth bricks. ? Cubic pressed copper scrap charging facilities were installed in C-furnace. ? Facilities were newly installed in C-furnace to treat neutralized residue from the wastewater and dust treatment plants, previously treated in the smelting furnace. Above innovations led to the further effective utilization of heat, increase in production, and savings in energy costs.

Jan 1, 1999

By Tetsuro Ohashi, Tooru Matsumiya, Yoshio Abe

"The three-dimensional deformation of a continuously cast slab was modeled into two-dimensional deformation by developing the solidified shell of the slab. The developed solidified shell was divided into rectangular elements. The thermal strain produced as the slab is wi thdrawn over one roll spacing in the casting direction was calculated from the temperature change during that time and the increment of the geometrical unbending strain during the time was calculated from the change in the radius of curvature of the slab by assuming that the neutral axis of bending is located at the mid-thickness of the slab and that the transverse section of the slab is kept in a plane during unbending. These strains were imparted to each element as initial strains. The interaction between the elements and the overall deformation of the solidified shell were analyzed by the finite element method.The analysis was performed on a slab being cast on a machine of the circular arc type with progressive unbending. The following findings were obtained as a result. The effect of unbending is spread in the upstream and downstream directions of the slab by the shear deformation of the narrow and wide faces. As the shear deformation increases, the strain in the unbending zone decreases and the strain outside of the unbending zone increases. The effects of secondary cooling conditions, slab size, radius of caster circular arc section, compression casting, etc., were also analyzed. IntroductionTo develop a method for preventing the internal cracking of continuously cast slabs, it is important to acurately analyze the deformation of the slab and this subject has been extensively investigated. Many researchers, including the present authors, have analyzed slab bulging. (1)- (11) Analysis has also been made of thermal deformation that assumes importance in continuous casting of small-section blooms.(12)-(18) However, unbending deformation, an extremely important subject for continuous casters of the circular arc type, has not been fully analyzed."

Jan 1, 1986

By R. K. Hill

The Hidalgo Smelter successfully reduced operating costs by 25% compared to the previous two years through a focused holistic approach to development of its entire workforce. The first phase involved basic team training skills for natural work teams. The second phase provided leadership training via breakthrough education to 40 of the smelter leader-both hourly and salaried. The third phase stretched out the teams training to include rewards for performance that resulted in hourly teams converting to salaried status-part of a company wide initiative. The fourth phase saw 1998 become the "Year of Safe Cost Reduction" where 7 breakthrough projects focused on different areas of expenditure. Implementation of lean manufacturing as a tool for teams to truly get their arms around what they controlled, introduced accountability and responsibility for operating results at the team level. This will allow the release of experienced supervisors from this role, to a pool of technical expertise, where our future breakthroughs will be designed and implemented.

Jan 1, 1999

By Ray Y. Lin

This study explores the formation of sodium pyrosulfate in molten sodium sulfate resulting from dissolution of SO3 at temperatures between 1160 and 1250 K. Solubility of SO3 in Na2SO4 melts at temperatures between 1160 and 1250 K under gas mixtures of SO2, O2 and argon was investigated applying a thermogravemetric analysis (TGA) technique. The activity of Na2O in the melt was determined with a high temperature electrochemical cell (ECC). Results showed that the SO3 solubility in molten Na2SO4 increases with decreasing temperatures and increasing SO3 partial pressures. Enthalpy of SO3 dissolution in molten Na2SO4 was calculated to be -119 kJ/mol for infinite dilute solutions. Thermochemistry of Na2SO4-Na2S2O7 melts was analyzed based on information obtained from both TGA and ECC techniques. Detailed examinations of the earlier low temperature measurements in the Na2SO4-Na2S2O7 system along with data from this study reveal that the solution behavior between Na2SO4 and Na2S2O7 can be satisfactorily treated as regular with the interaction parameter, , being 2.7 kJ/mol. The phase diagram and the field of SO3 partial pressure has been generated with the thermodynamic calculation using a regular solution approach.

Jan 1, 2006

By Rodney L. Williamson

Optimal estimation theory has been applied to the problem of estimating process variables during vacuum arc remelting (V AR), a process widely used in the specialty metals industry to cast large ingots of segregation sensitive and/or reactive metal alloys. Four state variables were used to develop a simple state-space model of the V AR process: electrode gap (G), electrode mass (M), electrode position (X) and electrode melting rate (R). The optimal estimator consists of a Kalman filter that incorporates the model and uses electrode feed rate and measurement based estimates of G, M and X to produce optimal estimates of all four state variables. Simulations show that the filter provides estimates that have error variances between one and three orders-of-magnitude less than estimates based solely on measurements. Examples are presented that verify this for electrode gap, an extremely important control parameter for the process.

Jan 1, 2001

By J. R. Budden

The growth and oxidation characteristics of any bacterial culture are ultimately determined by the nature of the sample being treated. The most important parameters in the application of bio-oxidation are bacterial cell number, growth rates, oxygen uptake and rate of oxidation. Cells present in the solution of an established culture were counted directly using a microscope, related to a protein value, and then used to determine the total cell number (in solution and on the solids). Protein determination of total cells enabled the growth rates on slurry to be calculated. The cell number and culture growth is related to the iron and sulphide contents of the sample. To illustrate these considerations a moderately thermophilic culture was used to treat ore and concentrate samples obtained from Australian mines.

Jan 1, 1990