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By Pragna Bhakta

The use of microbes for sulfide oxidation was investigated as a potential treatment option for low-grade refractory gold ores at Newmont Mining Corporation. The resulting patented technology for heap biooxidation maximizes oxidation rate by distributing the microbial population on the ore before placement on a heap. This paper presents data on global oxidation rates based on oxygen uptake in a 50-kg column for sulfidic refractory ores from the Gold Quarry mine. The oxygen uptake data was converted to a global oxidation rate. The calculated global oxidation rate was used to determine heap cycling times for Newmont?s commercial heap biooxidation facility.

Jan 1, 2003

By John E. Litz

Metal-bearing flue dusts are produced by some ferrous and non-ferrous industries. Many dusts are being or can be treated for recovery of metal values. Operating and proposed flowsheets for the most common dusts are reviewed. Advantages, disadvantages, product marketability, and cost implications are discussed for each flowsheet.

Jan 1, 1992

By P. T. Velu, R. G. Reddy

"The use of emf measurements to derive classical thermochemical data has been in use for many years. The reaction associated with electrochemical process is harnessed in a galvanic cell and energy involved measured in terms of electromotive force. The property requirements of sensor electrodes used differ for various aqueous, molten salt and solid electrolyte systems. The electrodes for molten salt electrolytes need special care for construction. This paper describes the studies carried out using an Ag/ AgCI reference electrode. This electrode was used to measure the solubility of compounds in molten salt electrolytes. The results obtained using this electrode are in excellent agreement with the values from chemical analysis method.I. IntroductionThe technique of obtaining a metal from its oxides by electrolysis is more than a century old process now. In these processes, it has been well established that for halide electrolytes, only the dissolved oxides are available for the dissociation at the electrode to release the metal during electrolysis. Therefore, the solubility of metallic oxides in the molten salt electrolytes is an important parameter which determines the economical and technical viability of these processes. The widely used molten salts systems in halides are fluorides and chlorides. The fluoride electrolyte system is used in our present study.The viability of obtaining aluminum alloys by in-situ electrochemical processing has been outlined in our earlier publications[1-8]. Studies on the solubility of various alloying element compounds is a part of our ongoing research efforts for the direct production of Al-Li alloys. As mentioned above, the solubility of lithium oxide and lithium carbonate compounds in molten fluoride electrolyte system have studied using EMF technique. The change in potential of the molten electrolyte was measured by a working electrode against the reference electrode with the addition of lithium compound."

Jan 1, 1997

By Bing Li, Miao Shen, Qiang Wang, Yuqi Chen

Electrochemical methods including cyclic voltammograms, square wave voltammograms, chronopotentiometry are applied to characterize the reduction potentials of Na+ and Li+ ions in LiCl-KCl melts. According to theoretical calculation, the reduction potential for Na+ is slightly more negative than Li+ in NaCl-LiCl-KCl melts at 450℃. However, by electrochemical measurements, the reduction potential of Na+ is slightly more positive than Li+ in the above melt and the potential difference between Na+ and Li+ reaches 0.16-0.2V on an inert W electrode in 1.0-2.0 wt% NaCl-LiCl-KCl melts. An active Pb electrode is used to improve the removal rate of Na+ from LiCl-KCl melts. The reduction potentials for both Na+ ions and Li+ ions on a Pb electrode shift to more positive values and the reduction currents become larger. After 6h electrolysis on a Pb electrode at -3.0V, the practical removal efficiency of Na+ ions reaches 90.12% and the reduced products contain metallic Na and Li with a Na/Li mass ratio of 4.25/1.

Jan 1, 2015

By S. Motoiu

Data acquisition is widely used for controlling flash smelting furnaces. A Romanian smelter from which a large amount of data can be collected uses such a technique. A computer program was developed for interpretation of the data. Inputs to the program are the process data files. Abnormal data are identified using standard statistical techniques; they can be edited if necessary. The following methods can be used for the analysis: linear correlation (single or multiple), polynomial correlation or comparison of two average values. Time variation graphs and histograms can be displayed. The random balance method was used for determination of significant parameters influencing the process performance. Not all process parameters are recorded, and some of them are not even measured. The software can compute some of these parameters such as: air flow rate required and the oxygen content of the gas: exiting the reaction tower. The software was used for the interpretation of a large amount of process data. The analysis showed that the process did not operate properly at some times.

Jan 1, 1999

By Khosrow Nikkhah

Increasingly ion exchange systems are being included in design of hydrometallurgical plants for metal extraction or impurity removal. Because such systems operate sequentially and are based on resins that exchange one ion for another, store it temporarily and release it to a regenerating solution, the usual steady state heat and mass balancing tools and spreadsheets cannot be used to design them successfully. This paper outlines the role of dynamic simulation in design of ion exchange systems. Examples are given for use of dynamic simulation in design and investigation of equipment based on consideration of the effect of input criteria such as expected ion loading and elution profiles. The methodology for dynamic modeling using IDEAS in design of multi column ion exchange trains operating in parallel is presented. Results shown include the non-steady state distribution of extracted metal and limitations imposed on operating conditions. These conditions include proposed sequencing of columns for loading and elution cycles, loading, elution and recycle flow rates as well as size and choice of related ion exchange plant equipment.

Jan 1, 2003

By Derek J. Fray

The need for on-line sensors is outlined and it is demonstrated that the control of many processes is prevented by the availability of these devices. The use of solid electrolytes is described for the sensing of elements in molten pyrometallurgical phases. In the cases where there is no suitable electrolyte, the addition of a second phase of a compound containing both the element to be measured and the element whose ion is mobile in the electrolyte can be used. For the measurement of high concentrations of an element a method based on current measurement is proposed.

Jan 1, 1994

By David Forrest

In 1981, K. E. Drexler proposed using massively parallel nanomechanical systems to manufacture large atomically exact structures. As in macroscopic mechanical systems, they would contain components that serve traditional functions such as trusses for support, gears to transmit power, bearings for low-friction support of rotating surfaces, motors to supply torque, pipes and conveyor belts for material transport, and channels for coolant. Many of these components would only contain a few thousand atoms. Specific designs for these devices became available in the early 1990s, and a few working devices appeared in laboratories by the early 2000s. As advances continue, a thorough understanding of the operative transport phenomena will guide the intelligent design and construction of nanomechanical structures, devices, and systems. The familiar equations of continuum mechanics are generally inadequate to describe the flow of heat and mass in the proposed nanosystems. Boundary conditions often need to be described in terms of potential surfaces. Surfaces are not geometrically smooth, but periodic according to the locations of atomic nuclei. Friction occurs not due to the plastic deformation of asperities on mating surfaces, but to phenomena such as thermoelastic damping and phonon viscosity when atoms slide past each other. Electrostatic forces dominate over gravitational forces by orders of magnitude; there is no role here for natural convection. Structural components, no matter how stiff and strong, are in constant motion due to the thermal noise in the system. The fluids are described in terms of individual molecules in constant motion.

Jan 1, 2006

By Neale R. Neelameggham

"Ferrous and non-ferrous metal industries are used to handling several billion tons a year of ore bodies, fuel and fluxing agents by mineral processing techniques and varieties of extractive metallurgy ""Reduction"" processes. Metal industry know-how can be applied to meet the challenge of Reducing CO2 in the atmosphere. Processes for generating alloys of carbon and hydrogen by Reducing the CO2 and water mixture, [carbonated water or water vapor] called Soda, to easily stored fuels are normally endothermic. The processes are similar to generation of hydrogen alone from water which is also endothermic. But hydrogen is more difficult to store than compounds [or alloys] of carbon and hydrogen. This recycling of CO2 and water are possible by using other forms of energy by innovative carbon capture methods.Thermodynamic Diagrams developed for Soda [CO2 and H2O] - metal reactions provide hints for using low cost unused stored energy in un-recycled metallic waste for thermal conversion. Choices for conditions for the electrochemical approaches [using solar - wind - hydropower] are also discussed.INTRODUCTIONIn 2006, I was reading some of the arguments put forth by learned scientists on the benefits and lack of benefits of bio-fuels. I found that the arguments rose partly from the differing system boundaries that were chosen by one versus the other. Some part of the argument may have been based on political climate or atmosphere rather than the analytical science. This situation is seen when scientists discuss which came first - the chicken or the egg, the fuel or biological matter, the oxide or the element, and so on.Then I thought –[just like many of the learned persons participating in this symposium] that common fuels - regardless of them being simple hydrocarbons or oxygenated hydrocarbons or carbohydrates - can all be made from the respective oxides of carbon and hydrogen by simple chemical reductions efficiently carried out in an economical fashion. This is the systematic approach we take when designing a chemical or metallurgical process facility."

Jan 1, 2008

By Allan J. MacRae

A copper alloy to be used for coils in cast copper cooling blocks has been identified and samples prepared for metallurgical examination and destructive testing to compare with cast cooling blocks manufactured from copper and nickel-copper alloy pipes. The copper alloy allows for the formation of a metallurgical bond between the pipe and the cast copper during the casting process, which does not normally occur with pure copper or nickel-copper alloy pipes. The alloy's coefficient of thermal expansion is also much closer to that of pure copper compared with nickel-copper alloys, so there is less strain induced at the pipe-cast copper interface due to differential thermal expansion. It is expected that this new pipe coil alloy and associated casting techniques will allow for the production of cast copper cooling blocks that have greatly enhanced service life in high heat load applications compared to existing technologies.

Jan 1, 2002

By C. J. Newman

Prior to 1995, the smelting process at the Kennecott Utah Copper Corporation (KUCC) smelter consisted of Noranda reactors and Pierce-Smith converters. In the consideration of expansion opportunities, the existing process did not lend itself to a program geared towards processing the total output of KUCC mining and milling operations. During 1989 and 1990, a number of smelting options were evaluated. The final selection was the Outokumpu flash smelting process, coupled with the new Kennecott-Outokumpu flash converting technology. Facilities were designed and installed to process 1:0 million tonnes per year of copper concentrate, with the ability to expand to 1.2 million tonnes per year. Following the shutdown of the smelter facility utilizing the Noranda technology in May 1995, the flash smelting, furnace commenced operation in June with the flash converting furnace startup following a few weeks later. The smelter has achieved design production targets and environmental goals. Current operating rates are at or above design rates for concentrate and matte processing. Emissions are lower than the permit levels and equate to less than 3.5 kg of SO2 per tonne of copper. This paper outlines the design, construction, startup and the first two years of operation of the modernized KUCC smelter.

Jan 1, 1998

By Kaspar Tall, Dmitri Goljandin, Kristiina Vilsaar, Jaan Kers, Valdek Mikli, Lifeng Zhang, Riho Tarbe, Viktor Laurmaa, Mart Saarna, Priidu Peetsalu

In this paper, the mechanical milling of the Printed Circuit Boards (PCB) was carried out. First goal of the work was to examine the management of the WEEE, in particular the re-use of PCB. Firstly, recycling methods of PCBs were summarized. During the study mechanical separation methods (magnetic-, density- and air separaten), electrical, and chemical methods were examined. Secondly the optimal particle size for air-classification was determined. Several tests were carried out to find the most effective separation method for separation of different material groups from PCB scrap. The new air classification stand was developed for testing the separation of lightweight particles like tinfoil stripes and plastics. The test results showed sufficiently good separation of heavier Al and Cu. For milled materials characterization the SA, IA, laser diffraction analysis and SEM were used. The chemical composition of the PCB powders was studied by means of energy dispersive X-ray microanalysis (EDS).

Jan 1, 2011

By John O. Burckle

For years, the measurement of fugitive emissions from the primary copper converter has defied all attempts based on inferential measurements, It has been concluded by virtually all investigators that the only dependable tech¬nique to measure these emissions would be to completely enclose an operating converter to permit the capture and measurement of all emissions. However, complete enclosure with a metal hood is difficult; many of the most serious fugitive emissions result during periods when the converter must be attended with crane-operated equipment. This approach would require either opening of the enclosure to permit the entry of large items of equipment or completely new methods for charging and tapping converters' The installation of the air curtain hooding system at ASARCO's Tacoma smelter has permitted a quantitative approach to the direct measurement of the fugitive for the first time. In this program, the fugitives captured by the air curtain were measured at a downstream sampling point in the exhaust side of the air curtain system during the various portions of the converter cycle. Emission factors were established for sulfur dioxide, filterable particulate (method 5), inhalable particulate, and selected trace elements.

Jan 1, 1983

By Pradip

The selective adsorption of chemisorbing fatty acids at high temperatures together with the addition of soda ash and lignin sulfonate as depressants is the key to the industrial processing of bastnaesite ores. This paper presents the results of a fundamental investigation that indicate that alkyl hydroxamates can be an alternative collector for the beneficiation of bastnaesite ores that contain barite and calcite as the principal gangue minerals. The primary mechanism for providing sites for the chemisorption of hydroxamate on bastnaesite appears to be through dissolution of cations, formation of the respective hydroxo complexes and readsorption at the interface.

Jan 1, 1989

By William Petruk

An investigation was conducted to determine whether mineral liberation data obtained by one image analysis technique are the same as data obtained by another image analysis technique. The liberated vs non-liberated, volume % and weight % techniques for measuring mineral liberations by image analysis were tested. The results show significant differences between the values obtained by the different techniques. The lowest liberation values were obtained by the liberated vs non-liberated technique and highest by the weight % technique. It is interpreted that the weight % technique produces the most realistic results. The weight % technique also produces data that can define mineral associations for the unliberated grains. These include (1) mineral quantities in particles that contain different amounts of unliberated mineral, (2) mineral quantities in particles that have different size ranges, and (3) mineral quantities and degrees of liberation for specific minerals in particles of different size ranges.

Jan 1, 1996

By Valeriano Antonio Corbellini, Marilda Macagnan, Rosana de Cassia de Souza Schneider, Tiago Bjerk, Mariela de Souza Vieira

The great potential of Brazil for the agricultural production makes our country a generator of agro industrial residues. In this context, the solid-state fermentation appears as a technology that shows alternative ways for those residues, adding values to these raw materials, through the production of substances of industrial interest, besides reducing the possible environmental problems. The main objective of this study was to apply the bovine fat residue associated to the garden grass for the fungal lipase production. Initially, 75 microbial cultures were isolated from garden grass samples after incubation of the mixture with bovine fat. From these cultures were selected the filamentous fungi, whose lipase production abilities were evaluated. The isolation and the selection were accomplished by using a differential culture medium containing Tween 80 as inducer substrate of lipase production. The colonies with lipolytic potential were detected by the presence of white precipitation haloes on the agar. With agro industrial residues the best lipase producer fungus was identified as Penicillium sp in 6 days of solid state fermentation. The crude enzyme obtained was tested in transesterification process for the biodiesel production.

Jan 1, 2008

By John M. Rogers

Risk management has rapidly developed to become an integrated, holistic approach that now encompasses the main risk elements such as product quality control, occupational health and safety, security, environmental liability, social issues and related management information systems. Given the obvious economic benefits, a seamless blend of risk management components has become essential to allowing organisations to sustain a competitive advantage, and is also looked upon as an important attribute in organisational growth. Juxtaposed with this management philosophy is the global trend towards outsourcing, which has seen the emergence of independent, and specialist risk management organisations. The New Millennium will undoubtedly see a shift away from "in-house" risk management practices, and consequently, the selection of a suitable risk management partner - a major vehicle for improving shareholder value - will become an important strategic management decision.

Jan 1, 1999

By Reinhold G. Schulze

Thiourea is being applied as an industrial leaching agent for gold and silver only in a few cases. A GIP technique was developed which eliminates most of the obstacles against its use. Omission of an acid treatment and mild conditions for precious metals stripping from the loaded carbon simplifies process conditions in comparison to cyanide CIP technique. Examples are given.

Jan 1, 1989

By Rollie E. Dutton, David A. Stubbs

"A sensor has been developed and tested that is capable of emitting and receiving ultrasonic energy at temperatures exceeding 900°C and pressures above 150 MPa. The sensor works with standard ultrasonic pulser-receivers and has demonstrated the capability of measuring workpiece deformation during hot isostatic pressing (HIP). Details of the sensor design, performance, and coupling of the ultrasound to the workpiece are described. Ultrasonic data acquired by the sensor, in situ, during HIP runs and at elevated temperatures in air are presented.INTRODUCTIONHigh temperature structural components, such as structural castings for jet engines, nickel-base superalloy turbine blades, and ceramic and metal matrix composites made from powders are often densified by hot isostatic pressing (HIP). For powder consolidification, the HIP process involves sealing the powder (and reinforcing fibers for composites) within an evacuated ""Can"" made of a material that softens at high temperatures. A hydrostatic pressure is then applied by pressurizing the inside of the HIP vessel with argon gas (up to 140 MPa). The hydrostatic pressure densities the powder through the elimination of the porosity between the powder particles.This paper presents details of the development and preliminary testing of an ultrasonic displacement sensor that can be used to monitor materials processing, in situ, at temperatures and pressures significantly higher than current ultrasonic displacement sensors. The target processing environment for this sensor is that typically found in a hot isostatic pressure (HIP) vessel, i.e., temperatures exceeding 1000°C and pressures above 138 MP a."

Jan 1, 1997

By Markus A. Reuter, Antoinette van Schaik

"Product design engineers select from a wide range of materials and combine them into multimaterial product designs. These include various materials (metals and non-metals) which are complexly integrated (e.g. welded, glued, alloyed, layered). The recycling/recovery rate of consumer products are determined by the different materials and alloys used, but also by the particle size and multi-material particle composition after shredding (combination of materials due to design). Eco-design (for recycling) and Design for Recycling (DfR) can only be conducted if the interconnectivity of material/metal in various unliberated materials is accounted for and its effect on material and energy recovery can be linked back to design. This paper will discuss the basic principles of these DfR models and it is shown how these tools (i) are linked Computer Aided Design (CAD) and Life Cycle Assessment (LCA) software, (ii) affect conceptual design specifications of products, (iii) integrate the complex detail of the recycling system and recyclate quality and hence (iv) make recycling an integrated part of the product system. Furthermore, it is shown how these assessment tools and models can be applied for benchmarking of the recyclability and environmental damage created by the recycling of end-oflife consumer goods in order to e.g. (i) provide the (original) equipment manufacturer with knowledge and solutions to support product stewardship and Extended Producer Responsibility; (ii) create awareness of the consequences/benefits of design, products and recycling systems to manufacturer, designer, legislator, recycler etc.; and (iii) assist the consumer in their choice of consumer goods from an end-of-life point of view.IntroductionA first-principles basis is required in order to be able to simulate and predict the recycling/recovery behaviour of products facilitating Design for Recycling (DfR) and Eco- Design. This links recycling technology and the environmental consequences of recycling directly to product design."

Jan 1, 2008