Search Documents

By Merete Tangstad, Gabriella Tranell, Jeff Kline

"Raman spectroscopy as an instrumental technique for the determination of silicate structure is widely accepted. This method was utilized for analysis of structural modifications associated with the addition of network modifying species. Silicate melts are described by the extent of oxygen bridging. Therefore, understanding the effect different oxides have on modifying the silicate structure will provide valuable information regarding the removal of boron from silicon in slag refining processes. Samples ranging from CaO/SiO2 = 0.56-1.2 were evaluated with and without varying concentrations of B2O3. The addition of CaO to SiO2 revealed Q2 species constitute 45% of the Qn species and addition of B2O3 to the high concentration CaO system results in an increase in Q2 and a decrease in Q0 . The disappearance of the Raman band associated to the three-member ring in the low concentrated CaO system indicates boron addition and destruction of the ring.IntroductionExtensive studies on the structure of silicate systems have been performed using Raman spectroscopy with consensus on the Raman shift associated with different bridging oxygen units [1]. Most of these studies are motivated by the lack of a fundamental understanding of the processes involved in petrology. Due to this, an opportunity exists to build on the knowledge obtained from these studies and conduct more research on slag structures relevant to industrial applications, as these systems are often compositionally similar to magmatic melts. Raman spectroscopic studies of industrial slags will provide insight into the possible structural modifications necessary to enhance removal of impurity species from the metal phase to the slag phase."

Jan 1, 2012

By Valdeci Paula Alvarenga, Sergio Luiz Costa, Itavahn Alves da Silva, Filipe Bueno Carvalho, Varadarajan Seshadri, Carlos Antonio da Silva

Use of fluorspar in steel refining operations is one of the environmental concerns and as such reduced consumption of this material or substitution of the same is one of the objectives. Industrial runs were carried out at Aperam Steel making convertor unit (Timóteo, MG, Brazil) using recycled/briquetted slag for partial or complete substitution of fluorspar. Samples were collected from the metal bath and slag after oxygen blowing to assess dephosphorization with several combinations of recycled/briquetted slag and fluorspar. The results showed that partial substitution of fluorspar by BOF slag briquettes did not affect the efficiency of dephosphorization. In general average Phosphorus content was reduced to 0.010% in the case of partial substitution compared to 0.016% in the regular refining procedure with no substitution. This replacement also resulted in 40% reduction of the fluorspar consumption in the converter

Jan 1, 2015

By J. Kevin Cotchen

The results of "submerged arc" electric furnace processing of a variety of materials is discussed with respect to the process and products, including the characteristics of the products (e.g. TCLP or Toxicity Characteristics Leaching Procedure). The materials melted include slags and wastes containing various metal oxides including copper, tin, lead, zinc, chrome, nickel and other associated elements. The findings of these tests are compared to those reported in the literature for other operations treating similar "wastes".

Jan 1, 1992

By G. A. Irons, D. Colbert

Several electric arc furnace (EAF) shops have increased the zinc and lead grades of EAF dust by reinjecting it into their furnaces; however, the kinetics of this operation are poorly understood. To understand the kinetics, EAF dust was injected into 70 kg heats of iron or steel in an induction furnace. Supplemental additions of carbon and oxygen to overcome the heat load on the system were also investigated. In all cases, the dust was chemically transformed, and the zinc content increased from 16% Zn to 60 - 80% Zn. About 50% of the zinc in the EAF dust dissolved in the iron or steel. The zinc oxide in the dust is thought to be reduced by carbon and the zinc vapour subsequently dissolved in the iron. A kinetic model for the dissolution process is proposed, and the implications for EAF dust recycling are discussed.

Jan 1, 2000

By G. Lindkvist

Roasting of concentrates with high impurity levels is normally done in multiple- hearth furnaces where the concentrates are heated with oilfired burners in order to remove As, Sb and Bi before the final sulfide oxidation. Although it is a countercurrent heat exchange process it uses a lot of oil. In order to develop an energy saving, and from a working environmental point of view a less harmful process than the multiplehearth process, pilot-plant tests have been done in a two-stage fluidized bed for partial roasting. The test materials have been As-rich concentrates with 8-25 % As some 5b and Bi. The Cu-content was 0-28 %. The tests have been successful with <0.3 % As,in the calcine and with an elimination of 5b between 80 and 90 %. In order to achieve the proper conditions for good impurity removal, 1.e. right temperature,residence time and sulphur potential, the tests were performed in a special designed roaster. The roaster consists of two beds with the facilities for recirculation of calcine, preheating of the blast, and possibility to use oxygen enrichment. The construction makes it easy to control the reactions that generate the heat in the bed and reduce the amount of dust that passes through the cyclones. As two roasting steps are used, the possibility to obtain optimal conditions for impurity removal is improved and the calcine can either be smelted to a normal matte, or after being dead-roasted in the second stage, be leached in the normal way for gold extraction. The calcine was smelted with slag. The matte and the slag obtained had low quantities of impurities in the matte and a favourable distribution of impurities to the slag.

Jan 1, 1983

By Irshad A. Rana

In a modern copper smelter, the capital cost of a sulfuric acid plant constitutes the largest single cost item of the total investment. It is thus essential to properly size the acid plant in order to reduce its capital cost and enhance the economic viability of a new smelter project. Whereas the off-gas from a smelting furnace is continuous and generally uniform, the gas flow from the Peirce-Smith converters is intermittent with significant fluctuations. The converters off-gas volume is dependent upon a number of interrelating factors. The most significant factors are the matte feed grade, the system air infiltration, the converter&apos;s size and blowing rate, the maximum number of converters simultaneously blowing and the gas cooling system employed. The acid plant size, therefore, is heavily influenced by the converter off-gases. Several of these factors are discussed, and their impact in determining the acid plant size is explored.

Jan 1, 1993

By E. Daniel Baker

"The term ""oxide disseminated gold deposits"" refers to near surface, gold-bearing veins, faults, and shear zones that typically contain appreciable amounts of oxidized ore or gossanous material, resulting from oxidation of sulphides.The concept of oxide gold deposits underwent a dramatic change after the discovery of the Carlin gold mine in north-central Nevada in the early 1960's. Now the term implies large tonnage, low-grade bulk minable deposits that are processed by milling and/or heap leach methods.Oxide gold deposits may now be classified into two types: (1) primacy ores derived directly from the effects of hydrothermal alteration on host rocks, and (2) secondary oxide ores derived from the supergene oxidizing effects of circulating post-mineral meteoric waters on gold-bearing sulphides. Each type of deposit has unique diagnostic mineralogic and metallurgical characteristics that must be addressed to achieve successful exploration strategies and viable metallurgical exploitation.The author would like to thank the management of Newmont Metallurgical Services and Newmont Mining Company for allowing presentation of this paper. Thanks are due Sevkett Acar, Donald M. Hausen, Jerry R. Odekirk, and D. Erik Spiller for their critical review of the manuscript. Also, thanks are extended to all those cited and uncited whose hard work and dedication have led to the discovery and exploitation of near-surface oxide gold deposits. Our knowledge would be greatly limited without the dedication and research of many others."

Jan 1, 1997

By Thomas R. Wildeman

Experimental methods for studying vapors over solid minerals are reviewed and an especially developed method using atomic absorption is described. The method is used to study vapor pressures over Te. Ag, Au, Ag2Te, and AuTe2 from 250°C through 10S0oe. Vapor pressures observed and, concurrently. sintering properties are significantly altered by the form of the solid. The vapor pressures of the tellurium compounds reveal complex processes occurring on the surfaces of the solids. The data given also point out a method of recovering precious metals from their telluride minerals w

Jan 1, 1987

By Lawrence D. May, Harry Mudgett

"In the course of developing a new industrial process, information produced at the Research and Development (R&D) stage is critical to determining the technical and economic feasibility of the project. Understanding the fundamental operating parameters for each unit operation in a flowsheet typically comes from historical knowledge of similar systems or by technical development through a robust research program. This approach holds true for processes incorporating fluidized-bed technology. In this paper, the authors will present a practical approach for performing a research study that will allow a process owner to determine if the concept of using a fluidized-bed system can become a reality. Included are discussions of key steps required at each level of the R&D program, and the critical information required for advancing the project to the next stage.IntroductionThe conduct of a research and development program typically starts with a process owner identifying a new industrial need or modification to an existing operation. The owner can pursue this need through multiple routes, including initial in-house development, coordination through an engineering firm, contacting suppliers of key equipment envisioned for the process, or through direct contact with research and development organizations. Where and when the project is conducted is as variable as the number and types of owners who pursue them. Factors that can influence the decision of where to conduct a research program can include the type of process desired, the scale and scope of the project, the location of the project site relative to the R&D options, the experience, capability, and availability of the potential research sources, and the costs to conduct the program. Often, the owner may choose a combination of the available resources to achieve their objectives. In the end, the owner's choice should be based on a thorough understanding of their goals and objectives for the program, and a good understanding of how to measure success while achieving those objectives. Herein, the authors will describe the methods we have typically used to develop the information an owner needs to make an educated decision for investing in a new or modified process."

Jan 1, 2014

By G. Mawire

The extraction of scandium from its oxide with a task specific ionic liquid [Hbet][Tf2N] offers potential advantages of lower energy consumption, recycling of the extractant and reduced environmental impact compared to conventional methods. In this paper, the influence of reaction temperature, solid to liquid ratio and water to the ionic liquid ratio on the extraction of scandium from a synthetic scandium oxide (Sc2O3) system was studied. The influence of investigated parameters on leaching was very significant as approximately 98% scandium was extracted from its oxide after 72 h. Furthermore, the ionic liquid also selectively extracted 47% scandium after 48 h from a mixture of pure metal oxides containing oxides of tantalum, niobium, and scandium. The research demonstrated the potential of [Hbet][Tf2N] to selectively extract scandium from columbite processing tailings and other scandium bearing ores like Ixiolite, Heftetjernite and Tantalite which predominately contain tantalum and niobium.

By J. B. Winter

The present Inspiration Consolidated Copper Company Smelter/Acid Plant complex located near Miami, Arizona, was designed and built specifically to conform to the ambient air quality standards imposed by the Federal Clean Air Act of 1971. The present plant replaced a facility which had been in operation since 1915. The electric furnace, siphon converters and acid plant complex were commissioned in May, 1974 (1). At that time, the Plant was considered to be one of the most extensively monitored and instrumented facilities of its kind in the world. Several control areas were located in close proximity to the controlled process, in addition to so-called central control rooms in the Smelter and Acid Plant. The control rooms were staffed with officials below the foreman level. Instrumentation consisted of conventional analog devices, except for a computer used in monitoring ambient air environmental conditions and limited use of programmable logic controllers. The harsh service conditions prevalent in the plant rendered a significant portion of the instrumentation unreliable and, in many cases, inoperable. Failure of the facility to obtain the total sulfur collection for which it was designed was, in part, due to serious inadequacies in control system logic and sulfur recovery averaged 79% in the early years. After careful study of the smelting process, engineering hardware and high labor cost inherent in the organizational structure, management made a judgement decision to convert to centralized control of the process with high level supervision 24 hours per day. A distributed digital control system with supervisory arid data acquisition/information reporting computers was selected to satisfy the requirement of central control. Operations are now controlled and coordinated from a primary control room in the Smelter and a satellite control area in the Acid Plant.

Jan 1, 1983

By J. N. Hartley

Samples of ash from the May 18, 1980, eruption of Mt. St. Helens Were collected from several locations in eastern Washington and Montana. The optical microscope and the combined scanning electron microscope with energy dispersive x-ray microprobe were used to determine the composition and mineralogical characteristics of the samples. In addition, a quantitative image analyzer was used to examine the particle size distribution, and x-ray diffraction was used to identify major minerals. Both polished sections and ultra thin sections (less than 5 ~m in thickness) were prepared to study the mineralogical characteristics. The use of ultra thin sections provided access to microstructural detail. Mineralogically, the samples ranged from almost totally glassy to almost totally crystalline. Crystal-line samples were dominated by plagioclase feldspar (andesine) and ortho-pyroxene (hypersthene) with smaller amounts of titaniferous magnetite and hornblende. Nearly all the samples contained from less than 1 to 3 wt% free crystalline silica (quartz, trydimite, or cristobalite).

Jan 1, 1981

By Malti Goel

"Ferrous and Non-ferrous industry in India is undergoing a transition to meet the growing demand and a new thrust to Research & Development (R&D) is mounting. On one hand, to meet the target laid by the policy in the Iron and Steel sector of 110 million tones production by 2020; on the other, innovations taking place in light metal production technology; both have necessitated greater attention to development of industrial ecological framework. Industrial ecology provides a number of new challenges as well as opportunities for the industry. The development and growth in a particular industry should have a trend towards reduced energy consumption, reduced resource consumption, thereby reducing the cost of production. Technology management strategies will have a key role in achievement of these targets. The paper describes recent developments in technology management, importance of R&D and case studies on adoption of energy efficient & CO2 reduction technologies in metal industry in India. In the end suggestions for future are made.IntroductionInternational Energy Agency [1] has assessed that nearly one third of the World’s energy consumption and 36% of CO2 emissions are attributed to manufacturing industries. In case of ferrous and non-ferrous metals, the resource equality and product quality finally determine the energy share across the countries. In the overall, Iron & Steel industry accounts for about 19% of total industrial energy used. The saving potential for non-ferrous metals is estimated to be anywhere between 13 to 25 % of the energy consumed depending on the level of resource quality. The projections are that energy consumption worldwide in Industry sector would increase 1.8% per annum up to 2030 on average, and up to 2.5% in developing countries."

Jan 1, 2008

By P. Heald-Wetlaufer

Doubly polished sections (i.e., sections polished on both sides) allow insights into complex paragenetic relationships, the interpretation of which is essential to understanding ore-forming processes. Alternate viewing of these optically superior sections in transmitted and. reflected light facilitates the recognition and definition of growth zones in ore and gangue minerals and the interpretation of postdepositional changes, such as hydrothermal leaching and replacement. Many such observations would escape detection by conventional petrographic methods. Our procedure for preparing doubly polished sections has evolved during the past 20 years and incorporates many standard procedures. Studies from such diverse districts as Creede, Colorado, Hokuroku, Japan, and the Upper Mississippi Valley zinc-lead district, southwestern Wisconsin, demonstrate the value of observations from doubly polished sections in constructing genetic models. The advent of doubly polished sections represents a major advance in the study of ore deposits and they should be a standard tool in every ore petrology laboratory.

Jan 1, 1982

By A. D. Neuman, C. C. Davis, M. R. Lopez, A. C. Martinez, T. A. Nothwang, S. L. Voit

"One of the thrust areas for the Global Nuclear Energy Partnership (GNEP) program is the development of actinide bearing fuels for transmutation in a fast reactor. Mixed Oxide (MOX) fuel has an extensive fast reactor irradiation history and thus is being considered for use as a baseline composition from which minor actinides (MA) can be incorporated for use as a transmutation fuel. This study involves characterization of precursor powders and pellets to be inserted into the Advanced Test Reactor in Idaho. These pellets will have three compositions: one standard MOX composition, (U80Pu20)O1.98, and two compositions of MA-MOX with oxygen to metal ratios (O/M) of (U75Pu20Am3Np2)O1.98 and (U75Pu20Am3Np2)O1.95. The precursor powders, which consisted of, highly enriched uranium oxide, HEUO2, depleted uranium oxide, DUO2, neptunium oxide, NpO2, americium oxide, AmO2, and plutonium oxide, PuO2, were characterized using a field emission gun scanning electron microscope (FEG-SEM) for particle morphology, size, and size distribution prior to pellet production.IntroductionThe Global Nuclear Energy Partnership (GNEP) was created in order for “fuel-cycle supplier” nations to provide assured supplies of nuclear fuel to “fuel-cycle customer” nations. The customer nations would utilize the fuel for electricity generation and subsequently return it to the supplier nation after it is spent. This spent fuel would then be reprocessed by the supplier nation in order to recycle the actinide constituents, mainly uranium and plutonium, in advanced nuclear power reactors, and thus reducing waste volumes [1, 2]. Nuclear materials would also be strictly controlled through the International Atomic Energy Agency. One of the thrust areas for the GNEP program is the development of these actinide bearing fuels for transmutation in a fast reactor under the U.S. Advanced Fuel Cycle Initiative (AFCI) in order to transmute long-lived transuranic actinide isotopes into shorter-lived fission products [3]."

Jan 1, 2008

By Graham J. C. Carpenter, Marc Charest, Jason Lo

"The method of producing magnesium-based composites with silicon carbide (SiC) particulates embedded in the matrix of magnesium AZ9I D alloy by the squeeze-casting technique are described. This method involves the fabrication of a SiC particulate preform and the subsequent squeezing of molten magnesium into the preform. In this study, alumina, aluminum phosphate and a proprietary binder were used for the fabrication of SiC particulate preforms. The procedures employed in the fabrication of SiC! AZ9ID composites are presented, together with the results of characterization of the composites using optical and transmission electron microscopy. Special attention is given to the reaction products in the bulk alloy and at the interfaces between SiC particles and the AZ9ID matrix alloy.1. IntroductionInterfacial, microstructural and metallurgical characteristics play an important role in determining the mechanical properties of a composite. In theory, reinforcing magnesium with SiC particulates should provide an improvement in strength and modulus of the composite over the unreinforced counterpart. However, many factors resulting from the fabrication process can cause degradation rather than improvements to the mechanical properties. In particular, the interfacial characteristics are known to critically influence the properties of composites [1]. Before evaluating the mechanical properties of a composite, it is always useful to examine the microstructure, which is closely related to the mechanical behavior. This helps to reduce the labor-intensive steps of sample preparation for mechanical property evaluation, which can be particularly difficult as a result of the high hardness of composite materials, as well as providing a wealth of information on the microstructural and interfacial characteristics, particularly the reaction products caused by processing. This information is also pertinent in understanding the factors governing the mechanical properties of the composites.There are many factors which determine the nature of the interfacial characteristics of a SiClMg composites. Qualitative estimations of the interfacial bonding have been performed based on thermodynamics, electronic and electrostatic concepts. In addition, the kinetic conditions during the fabrication play an important role. From an interfacial energy standpoint, the driving force for the formation of a metal/ceramic interface is the decrease in free energy that occurs when intimate contact is established between metal and ceramic surfaces. The simple representation of the energy change per unit area of interface formed (~G) is given by Dupre equation [2]:"

Jan 1, 1996

By Niels Verbaan

NioCorp is developing the niobium/scandium/titanium Elk Creek carbonatite deposit. The probable reserve announced by the company in 2017 indicated significant niobium (0.79% Nb2O5), titanium (2.81% TiO2), and scandium (71 g/t), and is composed predominantly of calcite, dolomite, and ankerite. Niobium is mostly (80%) contained in pyrochlore with the balance in various Fe-Nb-Ti oxides, which also host most of the titanium. Scandium is primarily deported in dolomite, with lesser quantities in pyrochlore and biotite. The process flowsheet recovers separate niobium, titanium, and scandium products. Scandium is extracted from whole ore hydrochloric acid leach solutions using solvent extraction and is further refined through a re-leach and precipitation process. Scandium leach residues are treated in a sulphuric acid sulphation process to recover separate niobium and titanium precipitates as well as to solubilize the remaining scandium. Both hydrochloric acid and sulphuric acid reagents are recycled within the flowsheet. This paper will discuss key bench and pilot test results of the niobium extraction and recovery circuits and will present a conceptual flowsheet developed by the project team for NioCorp at SGS Minerals.

By Eleazar Salinas R., Miguel Perez L., J. Cesar Juarez T., Martin Reyes P., Eduardo Cerecedo S., Isauro Rivera L., Francisco Patino C., Juan Hernández A.

"A complete characterization of burrows from Mining district of Pachuca - Real del Monte, in Hidalgo state Mexico, was done. These kind of residues had not been formally characterized, founding an average chemical composition of 70.43 % wt. of Si02, 7.032 % wt. of Ah03, 2.69 % wt. of Fe20 3, 0.70 % wt. of Mn, 3.98 % wt. ofK20, 3.34 % wt. of CaO, 2.50 % wt. ofNa20, 1.01 % wt. of MgO, 0.26 % wt. of Ti02, 0.04 % wt. of Zn, 0.026 % wt. of Pb, 56 g/ton of Ag and 0.6 g/ton of Au; In the same way, the residues present as majority mineralogical phases the following: Quartz, Berlinite, Orthoclase, Feldspar, Anorthoclase and Calcite. By the other hand, joint with the big volume that present these residues and the chemical and mineralogical characteristics, these materials or sub - products can be used for production of ceramics, into mixes forming some materials for architecture (bricks, blocks, and tiles), refractory bricks, in the production of cement and to get some metallic values such as gold and silver involved in these residues.IntroductionActually the mining residues in Hidalgo State, Mexico are the result of more tan 500 years of mining, leading so a great volume of deposits, which we can classify in different types, among the most communes we have: Acid Mining Waters, Waters of solid transport and elements in the form of radicals, deposits of abandoned minerals without processing, and mining wastes of processed minerals known as burrows or dumps, being these the most abundant in the Hidalgo State [1-4].Form the metallurgical point of view, it is known that a characterization study if fundamental to find the viability of reuse of these kind of residues, leading so an additional use and the opportunity of get an alternative use into several industrial processes, due to its contents of oxides of silicon, iron, aluminum, calcium, sodium and potassium, principally, besides of its mineralogy and distribution of chemical elements into its primary and secondary phases [ 1-2, 5- 6]."

Jan 1, 2011

By Jaroslav Horskoý, Miroslav Raudenský, Bogdan Filipic, Božidar Sader

This paper describes main elements and practical use of the computational system for automated setting of optimized casting conditions in the continuous casting of steel. The system consists of the heat transfer model of the process, empirical metallurgical criteria, and optimization algorithm. The physical model of the, strand temperature distribution relies on the classical Bennon-Incropera mixture continuum formulation for the convective-diffusive heat transport. Fluid flow effects are considered through enhanced thermal conductivity of the liquid phase. The model is solved by the operator-splitting Crank-Nicolson finite volume version of the Voller-Swaminathan scheme. The solution procedure is coupled with the IDS solidification analysis package. Boundary conditions for the strand cooling rely on combination of the generic and plant-specific mold, spray, and roll heat transfer coefficients ' by coping the effects of the casting speed, casting temperature, casting powder, mold oscillation mode, steel grade, water or air-mist spray type, running water, trapped water on the rolls, and radiation. The caster safety and productivity and the quality of the strand are related to nine empirical metallurgical criteria. The criteria ensure the caster safety and economy as well limit the internal, longitudinal, and transversal surface cracking possibility. The problem of finding optimum casting parameter values is stated as a minimization problem based on the analytical form of the cooling criteria evaluated from the steady-state temperature distribution of the strand. To solve the optimization problem, a genetic algorithm is employed. The algorithm explores process parameters settings heuristically by applying the principles of biological evolution. It starts with a random set of solutions and iteratively improves them through selection and variation. Solutions are evaluated by running the heat transfer model of the process and extracting the values of the empirical metallurgical criteria.

Jan 1, 2000

By P. Maraboutis

Iron removal by precipitation as jarosite from Fe-Ni-Co sulfate solutions, (synthetic or real, resulting from laterites leaching) has been investigated. Precipitation was carried out at 95 C, and at an initial pH 1.6, which was either kept constant with CaCO3 or Li2CO3 additions, or left to drift with the evolution of the reaction to lower values. The precipitation of K-, NH4- and Na- jarosite was initially examined using synthetic solutions. In all cases, hydronium ions were incorporated into the precipitate as well. Residual iron in solution was lower (0.2-1 g/1) and equilibrium was achieved faster (within 4-8 h) when precipitating K¬jarosite at constant pH, using CaCO3 for neutralization. Nickel and cobalt losses were small. Na- jarosite precipitation was also studied from real solutions with high initial iron content, under constant pH=1.5, controlled with CaCO3 additions, and it was shown that low residual iron concentration in solution (0.3-0.5 g/1) can be achieved again, with relatively small nickel and cobalt losses. The thickening and filtration characteristics of the precipitates were excellent in all cases examined.

Jan 1, 1988