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By Frustino L. Prado

For more than a century, the AAC (ammonia I ammonium carbonate) process has been applied to the recovery of various metals. A variation of it, the Caron Process was first used in the early 1940's in Cuba for the extraction and recovery of nickel from laterites. The original Nicaro plant has been in continuous operation since then. Years later the Caron process was used again in Australia at the Greenvale (Yabulu) NickelICobalt plant, commissioned in 1974. Other projects (Sered, Niquelandia, Nonoc, Punta Gorda, Albania) as well as several studies have been carried out. The Caron Process is alive and still promising. Members of our organization have been working with AAC and the Caron Process since 1952. This paper will review current approaches and potential improvements (enhancement of recoveries of Ni and Co, reduced energy consumption and maintenance simplification). Keywords: Caron Process, Ammonia, Ammonium Carbonate, Laterites, Nickel, Cobalt

Jan 1, 2004

By Ing. R. Geutskens

Zinc-bearing dust from blast furnace gas-scrubbing operation is a well known environmental health problem in the iron and steel industry. Hoogovens IJmuiden (The Netherlands) developed processes to solve this problem. 90% of the zinc is concentrated in 25% of the dust (the fine particle fraction) by means of slurry-hydrocyclonage. The resulting fine particle fraction is treated in a pressure leaching process. Hydrochloric waste pickle liquors have been used as a leaching liquor. By creating optimal leaching conditions more than 98% of the zinc is brought into an acid' solution, whereas nearly all the iron remains in the residue. The zinc can be separated selectively from the solution. The residue can be reused in the blast furnace (via the sintering plant). In the article information is given about the research work and -results of the pressure leaching process as well as the possibilities of the process for solving comparible problems.

Jan 1, 1990

By Eiji Iwamura

"Two types of diamond-like carbon (DLC) films with different microstructures were prepared by unbalanced magnetron sputtering, and the tribological properties of the nanoscaled DLC multilayer coatings consisting of alternating layers of graphitelike and amorphous-like microstructures were examined. The DLC microstructure was characterized by certain features of graphite-like clusters, in that some of them had onion-like structures. The films filled with the clusters were obtained in a condition with an incidence of high influx of energetic electrons, and the other films without apparent cluster structures were formed in a condition with ion bombardment controlled by negative bias voltage applied to substrates. Stacking each film layer-by-layer, the nanoscaled multilayered coatings showed superior tribological properties to individual single-layered films due to the combination of properties induced by the difference of microstructures.IntroductionIn various tribologiql applications, it is necessary for diamond like carbon (DLC) coatings to have adequate adhesion, significant hardness and a concomitant low friction coefficient. A number of deposition techniques and coating structures have been proposed to achieve suitable DLC properties [1-3]. However it is still difficult to obtain a satisfactory level of combination of the properties particularly desirable for engineering applications.In this study, the features of unbalanced magnetron sputtering were demonstrated with the effect of ion and electron bombardment. Two types of microstructures , namely amorphous-like and graphite-like, were prepared by changing the condition of the charged particles bombardment during deposition. Using the difference of properties induced by the microstructures, nanoscaled DLC multilayered structures were examined in an attempt to improve tribological properties."

Jan 1, 2000

By Mark Tsirlin

Kinetics of the initial oxidation stages of diffusive silicide coatings on 8 molybdenum and niobium at 1100 - 1700 and under the pressure of 400 and 1330 Pa has been studied using methods of gravimetry and gas phase analysis of oxygen, as well as by SEK, XRD and EDMA methods. The first oxidation stage described by asymptotic equation in case of NbSi coating changed over to the stage described by parabolic equation. The asymptotic law was shown to depend on non - stationary conditions on the oxide layer boundaries. Interconnection between silicides and quartz structures, on the one hand, and peculiarities of oxidation kinetics, on the other, is [discussed. The possibility of estimation oxygen atom jump frequency in quartz and fractions of oxygen reacting with metal and with silicon proceeding from the analysis of the kinetic data was ascertained. Conditions of oxidation kine- tics transfer from asymptotic (or parabolic) stage to a non - protective "linear" stage, associated with volatile ~roduct formation, are also discussed.

Jan 1, 1995

By Ragnhild Aune

In fire refining of copper, the affinities of various impurity elements on dissolved oxygen is of great significance. Further, in the design of oxygen probes in liquid copper, the influence of solute interactions on the activity of oxygen need to be considered in order to evaluate the oxygen concentration in molten copper. The present paper presents a series of measurements of the activities of oxygen in liquid Cu-M-o alloys (where M stands for Mn, Zn, As, Se or Te) carried out by the present group employing the solid electrolyte galvanic cell technique. Extreme care was taken to control the oxygen potentials in the inert gas atmosphere, and to keep the oxygen levels very low in the molten metal. The oxygen content was determined by analysis of the samples taken out from the melt. The results obtained showed that Mn has a strong negative influence on the activity coefficient of oxygen in liquid copper. A similar, but less prominent effect was observed in the case of Zn. Arsenic had no influence on the activity of oxygen in Cu (liq.). Se and Te had slight negative effect on oxygen activities in copper at XO > 10-5, while at lower oxygen levels the interaction coefficients were found to be positive. The results obtained were compared with empirical models for the calculation of interaction coefficients available in literature.

Jan 1, 2003

By J. H. Meza V

La Caridad operated at only 65% of design capacity during the first five years of operation. After the first major shutdown and repairs to the furnace in mid- 1992, the smelter quickly reached 95% of design capacity. Converter operation is now more efficient; blowing times have decreased from about 1.7 to 1.2 min/ton of matte. Anode copper production is now 15000 tons/month. The increased efficiency provided by better coordination and scheduling ensures La Caridad's ability to operate at present and expanded production capacity while simultaneously meeting environmental control standards.

Jan 1, 1993

By Jorge Alberto Soares Tenório, Romano Espinosa, Felipe Fardin Grillo, José Roberto de Oliveira, Denise Crocce

"The aim of this work was evaluation of the recovery of Zn and Fe of the EAFD added to the hot metal in the form of briquette at temperature of 1500°C. The EAFD was agglomerated by cold briquetting and introduced in the hot metal. This study utilized a bench-scale equipment to melt, during this process to kept a flow rate of inert gas above the bath. Were collected periodically metal samples and the samples were analyzed for determination of the content of total silicon and carbon by chemical analysis. Zinc oxide, zinc ferrite and other oxides were reduced and were volatized and collected by a cleaning system of dust (baghouse) located on top of the oven. More than 98% of iron were recovered from EAFD during the test. It was possible to produce a dust containing about 68% zinc by means of adding of EAFD.IntroductionIn the first semester of 2010, steel production was about 706 million tons, 27.9 % more than in the first half of 2009. Not a significantly increase if 2010 data is compared with the first semester of 2007 (only 7.2 % higher), before the world’s economic crises. Steel production is divided into two main routes. The first one, and most used, is the Basic Oxygen Furnace Process (BOF process), which in 2008 accounted for approximately 67.1 % of steel production. The second route is carried out in the Electric Arc Furnace (EAF) that in 2008 represented 30.6 % [1 ].Electric arc furnace dust (EAFD) is a solid waste generated during the steel making process. It is classi?ed according to NBR 10004 as dangerous solid waste-class I, because the elements Pb e Cd leach in water exceeding the maximum limits permitted by the NBR 10004 [2 ]."

Jan 1, 2012

By Xiao Yang

Calcium oxide is one of the major fluxing agents used for steel refining. Because unreacted CaO remains in slag in most cases, discharged slag is difficult to be recycled smoothly. With the growth of environmental concerns, improving utilization efficiency of CaO is required to reduce the amount of discharged slag and energy consumption. The authors have reported a resource and energy-saving process by using multi-phase flux for dephosphorization. Reaction behavior of phosphorus in multi-phase CaO–FeOX–SiO2–P2O5 flux system was investigated. Formation mechanism of P2O5-rich phases was clarified at the interface between solid CaO or 2CaO, SiO2 and molten CaO–FeOx–SiO2–P2O5 slag. Phase relationship and thermodynamic properties of 2CaO, SiO2-3CaO, P2O5 solid solution were observed to confirm the condensation of P2O5 in solid phase. Based on these results, reduction of CaO consumption, discharged slag curtailment, and energy-saving effects in the novel refining process by using multi-phase flux were discussed.

By Mariane Costalonga de Aguiar, Carlos Mauricio Fontes Vieira, Sergio Neves Monteiro

"This work evaluates the effect of incorporation of an ornamental rock waste into an industrial clayey body used for roofing tiles fabrication. Formulations with 0, 10, 20 and 30 wt.% of waste were prepared by replacing the sand in the industrial clayey body. The plasticity of the formulations was determined by the Atterberg limits. Specimens were fabricated by 18 MPa press-molding and then fired from 850, 950 and 1050°C. The specimens were tested to determine the water absorption, linear shrinkage and three points bending flexural strength. The results indicated that the waste improves the extrusion performance of the clayey body by decreasing its plasticity. The use of the waste was beneficial to the water absorption and mechanical strength of the fired clayey ceramic at 1050°C.IntroductionOrnamental rock is a natural resource available in the municipal area of Santo Antonio de Padua and located 150 km from the city of Campos dos Goytacazes, northe of state of Rio de Janeiro, Brazil. Intense industrial activity related to ornamental stones, especially gneisses, is traditionally occurring in the region. After mining, the flagstone is submitted to sawing to obtain blocks and then, after a manual operation, the final products are small flagstones [1,2]. During the sawing operation, a sludge composed of water and fine particles of rock is generated. A monthly production of 1000 tons of ornamental rock waste is estimated to be produced at Santo Antonio de Padua. The final disposal of this waste has brought serious environmental problems. Since most industries do not have an adequate sludge treatment, the waste is contaminating the soil and underground waters as well as obstructing rivers and lakes.Ceramic bodies industrially fabricated in the municipal area of Campos dos Goytacazes, 280 km from the city of Rio de Janeiro, are still empirically elaborated using a mixture of local clays. These clays are predominantly kaolinitic mineral, associated with high plasticity. Due to the excessive plasticity of the ceramic bodies, it is common to have dimensional defects in the final products after the drying and firing processes. Moreover, the kaolinitic structure and the presence of aluminum hydroxide confer a refractory behavior to the local clays. This impairs sintering during the firing operation. In the case of clay ceramics for civil construction, this results in greater porosity associated with elevated values of water absorption [3,4]. To avoid this problem, it is necessary to reformulate the ceramic body composition. The addition of both non-plastic materials to reduce plasticity and fluxes to condition the refractoriness is a possible alternative."

Jan 1, 2011

Physical and chemical properties of the salt flux phase play a significant role in the recycling of UBC in Aluminum melting processes. Particularly knowledge of several properties such as salt vapor pressure, melting temperature, loss of aluminum, corrosion of refractories are useful for the process control decisions in order to attain a good quality of aluminum produced. A literature review and analysis of several salt flux systems for the selection of a flux for the Aluminum melter (low temperature natural gas bath melting) process were made. Based on these analysis two salt flux systems are recommended for further studies. These are NaCl?KCl?LiF system and NaF?LiF?KCl system with small amounts of other salt additives. Application of these fluxes to Al industrial processes are discussed.

Jan 1, 1996

By E. V. Verhoef

The proposed EU directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment promotes the substitution of lead in consumer electronics to reduce emissions from lead in the end of life phase. In this paper, the consequences of substituting lead in solders is assessed using the Eco-lndicator-99 method for the examples. The base metal production system is considered as an interconnected network modeled dynamically in Simulink 4 and Matlab 6 (Mathworks Inc 2000), where the recovery and production of metal components of the assessed product partially overlap. This approach requires global modeling of metal production processes and mass balances and resulting allocation choices. It also reveals the susceptibility of LeA scores to different choices in the modeling and data availability and uncertainty. Besides the comparison between lead-free and lead-containing solders, other side effects are revealed. Lead is carrier material for the recycling and production of many co-elements in the interconnected production and recovery system. Substitution may have adverse effects such as temporary shortages of other connected metals that are often not considered in normal LeA assessments, thus leading to erroneous results. The suggested approach provides directions for including these external effects and for further assessment of the environmental effects of substituting lead. This paper shows that in order to assess the environmental aspects of metallurgy, dynamic modeling of the total system is required based on the fundamental thermodynamics in each metallurgical reactor, the basis of this dynamic model. With this the true environmental impact of metallurgy can be explained. In the case of lead free solder, it is shown that the mining of substitutes has a very much larger impact.

Jan 1, 2003

By Francis Vanbellen

Umicore Precious Metals Refining operates an integrated precious metals smelting and refining plant in Hoboken, Belgium. Once a smelter and refiner of complex concentrates, the plant today?s feed consists exclusively of industrial and consumer recycled products, making it the world?s largest recycling facility for precious metals. Unlike the fairy tale of the Frog Prince, it took much more than a princess? kiss to successfully realize this makeover. A completely renewed plant has been built over the past decade. The most visible technological innovation was the commissioning of the Pb-Cu smelter. Its flexibility towards very different types of feed makes it perfectly suited as main entry to the Hoboken flow sheet. A new Cu-leaching & electro winning plant and precious metals refinery make up the Precious Metals Operations (PMO) whose targets are fast throughput and maximized yields for gold, silver and the platinum group metals. The Base Metals Operations (BMO), flexibly process the by-products from the PMO, valorizing ?impurities? like indium, tellurium, selenium and others. Off gas and waste water treatments ensure compliance with strict environmental standards. Precious metals recycling is an art that goes beyond mastering a unique flow sheet. Umicore Precious Metals Refining offers a complete recycling service, taking care of sampling and assaying, metals management and logistics. The quality of this integral service is recognized through the attribution of ISO certifications for our operational activities, sampling and the environmental care. And it?s an art that follows Michelangelo?s experience: ?Art is 5% of inspiration and 95% of transpiration.?

Jan 1, 2006

By Jim Sarvinis, Mark Berkley, David Clarry, Jason Berzansky

"Technologies developed to sequester CO2 or use CO2 for enhanced fossil fuel recovery are currently being utilized across the globe. Taxation regimes and CO2 credit trading are becoming drivers for a number of projects. Some mining companies have also identified ancillary opportunity to sequester CO2 in their by-products; recent work in the alumina industry is a prime example. In addition to process plant emissions, mining companies are becoming increasingly aware of their overall carbon footprint, including CO2 generated during the production of utility power. New power plant designs, in various stages of development, include CO2 separation and sequestration techniques. This paper summarizes the state-of-the-art for these technologies; including integrated gasification combined cycle (IGCC) power plants. A concept to use the gasification products as reductant in metallurgical processes is also described. The relevance of technology from power plant designs with post-combustion capture to the processing of off-gas generated in metallurgical facilities is also reviewed.IntroductionGlobalization and international economic growth have led to an increase in energy demand worldwide, and a corresponding increase in greenhouse gas (GHG) emissions. In 2005, 81% of global energy supply came from fossil fuels [1]; and while alternative energy technologies are emerging, it will require many decades to curb society’s fossil fuel dependence. Given the global concern of climate change and its scientific relationship with anthropogenic carbon dioxide (CO2), there is at present great interest in the development of techniques to reduce emissions of CO2. While most of these efforts are related to power generation and energy efficiency, the development of technologies for CO2 capture may offer opportunities in reducing emissions from industrial processes."

Jan 1, 2008

By Mônica Suede Santos Silva

This work describes characterization of the performance of the tundish of a six strand continuous casting unit of the Companhia Siderurgica Belgo Mineira, Joao Monlevade, Brazil using physical modeling. Permanent and transient conditions, due to ladle metal composition changes are considered. Pulse and step tracer addition techniques are employed to assess the control variables. For transient conditions the degree of inter-mixing and the minimum residence time are determined with a view to optimize the process especially during the grade changes of steel.

Jan 1, 2003

By Chonghe Li, Xionggang Lu, Wei Xiao, Xingli Zou, Weizhong Ding

The reduction degree and rate of the initial ilmenite concentrate and pre-oxidation samples by hydrogen were investigated by using thermogravimetric analysis system. H2-TPR was used to detected reduction properties of the pre-oxidation products which were oxidized at different temperatures. The phase transformations and micromorphology changes during pre-oxidation and hydrogen reduction were identified by XRD and SEM. The FeTiO3 was decomposed into TiO2 and Fe2O3 at the temperature below 900 oC. With the temperature rising, Fe2TiO5 was the only stable phase in high temperatures. The reduction of pre-oxidation ilmenite concentrate was faster than the natural sample, which was attributed to the micropores generated on the surface of ilmenite concentrate during oxidation. The main phases of the reduction product were metallic iron, ferrous pseuodbrookite.

Jan 1, 2014

By Harrison Cooper, Stephen Pack

"Data from samples taken during rotary air blast and reverse circulation drilling are crucial to properly assessing economics of mineral deposits in the case of exploratory work, and are equally critical in accurately delineating ore and waste in execution of mine operation plans. Past studies of sampling procedures, comparing results of conventional splitting to more precise extraction of representative samples, illustrate the significant degree of error frequently encountered. Economic impact of error in mine blast hole sampling work can be shown to result in theoretical losses valued at millions of dollars annually in operating large scale mining projects. Results of past drill sampling studies are reviewed.Drill sampling technique can be improved by collecting coarse and fine particles together and extracting samples for assay from the complete flow of rock and dust simultaneously. This can be accomplished with a collection unit attached to the drill stem through which all except a small proportion of extreme fines are retained. The bulk mass can be static sampled as flow takes place through the collector when size reduction is not required. Alternately, collected mass with fines and coarse intermingled can be processed for increased accuracy through size reduction to obtain proportional samples."

Jan 1, 1999

By Richard A. Leiby

The recycling of lead-acid batteries in the United States has become a challenge as to how to balance ever increasing environmental regulation and cost with efficient operations. East Penn's captive secondary lead smelter has developed into a recycling facility producing lead, polypropylene, sulfuric acid, ammonium bisulfite, and non-hazardous discard slag. The emphasis has been to design a facility to comply with environmental regulations, to eliminate wastes, and to produce products, while at the same time, continuing to supply the company's battery manufacturing raw material needs.

Jan 1, 1993

By Susanne Pignolet-Brandom

Reflected light microscopy, and scanning electron microscope energy dispersive spectroscopic analysis and backscatter electron images were used to determine if a "slick dross" with undesirable handling properties has an assemblage of phases distinct from normal dross. This study has found that in the normal dross the most abundant lead phases are lead sulfide and lead metal and the most common copper phases are copper-iron sulfide and copper sulfide. In the slick dross, the most abundant copper phase is copper-lead sulfide and the most common lead phases are copper-lead sulfide and lead sulfide. The resulting mineralogical information has provided additional insight into the causes of the handling problem and the reaction mechanism for the formation of normal and slick dross

Jan 1, 1988

By Chan. C. L., Zehr. R., M. M. Chen, J. Mazumder

"Two three-dimensional models of a surface tension gradient driven flow during laser surface heating are developed. The first model is based on a perturbation solution. The basic solution corresponds to the stationary axisynwnetric case and perturbation is based on a small scanning velocity. The advantage of seeking a perturbation solution, as it turns out, is that the three-dimensional flow is modeled by two sets of two-dimensional equations which are presumably much more tractable than the original three-dimensional equations. Numerical solutions are obtained and discussed. The second model is a full three-dimensional numerical solution of the Navier-Stokes equations, using a point-by-point partially vectorized iteration scheme. Surface shape is also determined in a self-consistent manner. The effect of the presence of convection on pool geometry, cooling rate and solute redistribution is presented and discussed.IntroductionThe existence of fluid flow and convection and their effects were first reported in the fifties (1,2). The role of convection in controlling pool geometry such as pool shape, undercut and ripples, and defects such as variable penetration, porosity and lack of fusion and weld properties such as weld homogeneity and bead formation is studied by a number of researchers and is reviewed by the authors in a recent paper (3).Recently, surface tension gradient driven flow has been identified as one of the forces responsible for convection within the molten pool (4,5). It is postulated that surface tension gradient driven flow is responsible for the surface ripple formation in the weld pool (6-8). Oreper, et al. (9) developed a two-dimensional convection model. Buoyancy, electromagnetic and surface tension gradient forces were considered. The formulation was based on a specified pool profile. It was found that the surface tension gradient is the dominant force in most cases. However, the solid-liquid interface is not known a priori. In fact, the solid-liquid interface, i.e. the pool shape, is a piece of information that the model should be able to predict. A two-dimensional transient self-consistent (i.e. the solid-liquid interface is solved as part of the solution] model for laser surface melted pool was first developed by Chan, Mazumder, and Chen (3)). This model predicted a non-uniform cooling rate, hence non-uniform microstructure. Depending on the Prandtl number (i.e. material) and surface tension number, the shape of the molten region as well as the cooling rate changes. It was also predicted that the recirculating velocity is of one or two order of magnitude higher than that of the scanning velocity. This model provides the detail of the flow field and heat transfer on a plane perpendicular to the scanning direction. However, the front-to-back motion and its effect on heat transfer also play important roles in the physical process, especially for the fact that the recirculating velocity is so much higher than the scanning velocity. Such a motion cannot be obtained from two-dimensional models."

Jan 1, 1986

By James C. Barker

Near Rainbow Mountain in the east-central Alaska Range an ultramafic complex forms a sill-like intrusion composed of dismembered bodies exposed along the south side of the Denali Fault and Broxson Gulch Thrust. The complex comprises dunite and peridotite with lesser gabbro, which together exhibit poorly defined, steeply-dipping compositional layering. The complex hosts four types of copper-nickel occurrences which have characteristic platinum-group elements (PGE), gold, and cobalt distributions. Three of the occurrence-types are considered to have formed as a result of primary mineral segregations which developed during intrusion of the complex. The fourth type of copper-nickel occurrence formed as a result of post-magmatic hydrothermal fluids at intrusive contacts. Scanning electron microscope examination indicates that PGE occur as micron-size telluride and arsenide minerals.

Jan 1, 1987