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By M. F. Hochella

Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis have been used to study the mode of occurrence and mineral associations of gold in partially oxidized high grade gold ore from the Carlin sediment-hosted deposit. Rounded.gold particles have been observed that range in size from 0.03 to 0.1 p.m (300 to 1000 A) in diameter. The gold is associated with maghemite h-Fep3l and a K-Al-Si-bearing phase that is suspected to be illite. Detailed descriptions of gold and its mineral associations in 'Carlin-type' gold deposits are critical not only to understanding the mechanism of fluid transport and precipitation of gold, but also to developing improved metallurgical techniques for the recovery of gold from refractory ore. Direct observation of gold in unoxidized ore is rare due to its relatively high degree of dissemination and low average bulk concentration which averages 9 ppm according to Radtke (1). Hausen and Kerr (2) observed 1 to 5 p.m grains of gold directly in oxidized ore but these microscopically visible particles account for only a small percentage of gold present in the ore. The samples used in this study were selected from individual beds of high grade, partially oxidized ore (4.55 oz/ton or 156 ppm gold) that were collected in the Main pit of the Carlin mine. The samples were collected from several thinly laminated carbonate micrite beds within the top 50 meters of the Roberts Mountains Formation. The carbonate micrite has been altered by hydrothermal fluids to a calcite-absent, moderately silicified rock referred to as alteration zone #3 by Bakken and Einaudi (3). Based on petrographic and SEM studies, the samples contain carbonaceous matter, and both pyrite and iron oxide pseudomorphs after pyrite. The oxidation of pyrite may be a pro-duct of deep weathering, in which case limited remobilization of gold may have occurred. TEM sections of the rock were prepared by first embedding small chips in low viscosity epoxy. The epoxy blocks were cut with a Reichert Ultracut E ultramicrotome, producing thin sections less than 0.1 p.m thick. The sections were examined with a Phil-lips 400ST TEM at 120 keV in both imaging and selected area diffraction modes. Native golci*was easily detected in TEM bright field images due to the large electron density contrast between gold and all other phases that are present (Figs. 1 and 2), Gold was positively identified with high spatial resolution EDX analysis in the transmission electron microscope, although selected area diffraction of individual grains was not successful EDX analyses of the platy and massive minerals immediately surrounding the gold particles typically indicate the presence of Si, AI, K, and Fe, However, the d-spacings derived from selected area diffraction of these polycrystalline masses (as, for example, in Fig. 2) give an exact match for maghemite. As a result, there is no diffraction information to identify the K-AI-Si-bearing phase(s). The lack of a diffraction pattern could be due to either electron beam damage or to a poorly crystalline phase(s).

Jan 1, 1987

By Patrick R. Taylor

Keywords: Thermal Plasma, Electroreduction, Electrolysis, Transition metals, Waste treatment, Molten oxides, Chromium oxide. An innovative process to treat transition metal oxide waste materials from diverse sources is presented. This technology involves using reverse-polarity DC plasma driven electrolysis in molten oxides. The process results in the recovery of the transition metal and other heavy metals from waste. By-products generated throughout the processing was converted to environmentally acceptable slag. The significance of this technology is that the treatment of the waste is accomplished in one step which in turn lowers the cost of remediation. Moreover, this process uses high temperature properties of thermal plasmas, which makes it possible to use molten oxides instead of halides as electrolytes. Chromium was successfully reduced from chromium oxide through the plasma driven electro-reduction process. It was shown that the selection of the appropriate ionic conducting oxides was critical for the formation of a slag that would enhance the reduction of chromium oxide.

Jan 1, 2004

By A. Patti, S. Reutzel, D. M. Herlach, L. Ratke, I. Egry

Cu-Co shows a metastable miscibility gap in the region of the undercooled melt. Undercooling of the melt below the binodal leads to separation of the melt into a Co-rich LI-phase and a Curich L2-phase. Experimentally, undercooling into the metastable miscibility gap is realised by means of electromagnetic levitation (EML), processing in drop tube (DT) and by melt flux embedding. As undercooling is large in these experiments, the velocity of the solidification front is high and the microstructure is frozen in instantaneously. Samples have been undercooled and solidified in the TEMPUS-facility (container less electromagnetic processing under weightlessness) during parabolic flight under reduced gravity conditions. Microstructures of solidified samples have been analysed and compared to those processed under gravitational conditions. The influence of convection on phase growth is much lower in reduced gravity. The microstructure shows spherical droplets of the minority phase, statistically dispersed in the majority phase.

Jan 1, 2004

By Tuula Mäkinen

One of the latest applications of the Outokumpu Flash Smelting Technology is the direct smelting ,of nickel concentrates to metallised low-iron nickel mattes. Compared to the conventional nickel smelting, the new DON process needs a lower number of smelting vessels resulting in considerable economic and environmental benefits. Fundamentals of smelting nickel concentrates in one stage to low-iron mattes are presented. Properties of nickel. smelting slags with an emphasis of the slag fluidity at high MgO-levels are also discussed. Conditions prevailing in DON mattes at high oxidation degrees are presented as well as their influence on the behaviour of such mattes in the settler and on tapping the furnace. Distributions of elements in the direct smelting are presented and compared with the conventional process. A further comparison is made with pilot-plant data and the industrial scale.

Jan 1, 1998

By Achilles J. B. Dutra, Carlos M. Juarez

"The use of thiourea as a gold leaching reagent has been extensively studied by many researchers, and it has proved to be promising for some cases as refractory ores. Otherwise, the recovery of gold from these solutions did not receive so much attention. In this paper the electrowinning of gold in acidic thiourea solutions was studied by voltarnmetry and chronopotentiometry. An adsorption step was detected prior to Au(I) reduction and the diffusion coefficients at 25°C for Au-TU complex and FD were found to be 1.00 x 10.5 cm2 S-I and 1.98 x 10-5 cm2 S-I respectively. At -0.350 V (SCE) a passivation probably due to TU adsorption was observed. For higher overpotentials hydrogen evolution was the main reaction.IntroductionThe use of acidic thiourea solutions for the extraction of gold and silver has shown to be a promising alternative to the traditional process of cyanidation, specially for certain refractory ores (1-3) and electronic scrap (4). In some cases, the industrial scale was reached (1,5). The thiourea leaching of precious metals presents advantages over cyanidation, as faster kinetics, lower toxicity and lower sensibility to base metals; however the costs due to high thiourea consumption impairs its use.The majority of the publications on thiourea processing of gold is on leaching. Many are review papers (5-7). Recently, the adsorption and desorption of the gold-thiourea complex on activated carbon and ion exchange resins have been studied (8-11).Little research has been done on the electrowinning of gold from acidic thiourea solutions, most of it has been carried on the seventies and beginning of the eighties in the former USSR (12-17) and concerned the eletrolytic extraction of gold in tridimensional cathode cells.The present paper concerns the cathodic behavior of the gold-thiourea complex in the presence of formamidine disulfide in order to provide information on the electrowinning of gold from solutions obtained directly from leaching or from an elution process."

Jan 1, 1997

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 Kimiaki Utsunomiya, Yasumasa Hattori, Yoshiaki Mori, Toyokazu Okubo

"The effect of various operating conditions on splashing behavior in a Peirce-Smith converter has been investigated with a 1/5.7 scale cold model. Dynamic similarity between the model and a commercial converter was attained by setting the modified Froude number in the model experiments in· the range for normal converter operation. It is known that for a given modified Froude number the dimensionless penetration length of gas into the liquid phase increases as the liquid density decreases. Moreover, penetration· length has a large effect on splashing behavior. Therefore, a heavy liquid, a mixture of water and lead concentrate was used as the liquid phase. It was concluded that the amount of splash dramatically decreases with a reduction in the buoyancy energy per, unit liquid mass and an increase in the horizontal distance between the tuyere tip and the edge of the mouth.IntroductionSubmerged gas injection is widely used in practice in ferrous and nonferrous pyrometallurgical operations to achieve large gas-liquid contact areas and good agitation of liquid for rapid chemical reaction. The common application in ·nonferrous industry is the Peirce-Smith converter with multi-tuyere for copper and nickel matte converting. This process has been used for over 100 years because of its effectiveness in mixing of the molten bath, as well as its merits of the engineering simplicity. However, the mechanisms which · determine the blowing performance is poorly understood, and the design and operating conditions of the Peirce-Smith converter varies widely from plant to plant, such as by diameter, length, mouth angle, tuyere position and level of molten matte. Smelters have continuously made an effort to increase converter productivity, implying maximum tuyere blowing rate. Above a certain critical blowing rate, splash of molten matte from the converter mouth becomes unacceptable because of dangerous ejection and accretion buildup around the converter mouth, which results in interference with effective hood sealing. In fact, a 1993 converter survey[!] reported that splash was a major limiting factor for blowing rate and 54% of responding plants from around the world regard it as a limiting condition[2]. In order to increase tuyere blowing rate a study of the effect of various operating conditions on splashing behavior is expected."

Jan 1, 2000

By Kuniaki Murase, Tetsuji Hirato, Koji Nitta, Yasuhiro Awakura

"The redox behavior of copper species in an ""ammonium imide"" room temperature molten salt was examined in order to clarify the applicability of the salt to the electroplating media of various metals. Trimethyl-n-hexylammonium bis(trifluoromethanesulfonyl)- amide (TMHA-Tf2N), having an electrochemical window of 5.6 V (50 °C), and corresponding copper(II) salt were synthesized. In TMHA-Tf2N media monovalent copper ion, Cu(I), was stable and Cu metal was oxidized, or corroded, in the presence of Cu(II) species. Cathodic electrodeposition of copper metal and anodic dissolution of it were, thus, one-electron reaction and their current efficiencies were almost 100%.IntroductionElectrodeposition of metals from aqueous solutions is an important soft process for manufacturing thin-film materials, surface finishing, and extractive metallurgy. However, the electrodeposition of base metals, such as zinc, chromium, and nickel, from aqueous media inevitably accompanies hydrogen evolution, which lowers the cathodic current efficiency of metal deposition. Since the electrodeposition of aluminium, titanium, and rare earths from aqueous media is actually impossible due to their largely negative redox potentials, nonaqueous media such as aprotic organic solvent and high-temperature molten salts have been employed for the electrodeposition of these metals. Room temperature molten salts (RTMS),1, 2) or room temperature ionic liquids, have also been developed as a promising electrolytes for the electrodeposition of base metals. In this field, chloroaluminates of alkylpyridinium or alkylimidazolium cation have been well investigated for aluminium3) or alluminium-alloy4-5) electroplating media. On the other hand, in order to avoid high hygroscopicity arising from the use of aluminium chloride, attempts have been made to combine the alkylimidazolium cations with fluorine-containing hydrophobic anions, e.g. BF4-,6) CF3SO3- (TfO-),7) (CF3SO2)2N- (Tf2N-),8) and H(HF)n-ions,9) and investigated for electrodeposition media.'°) Recently, a new series of RTMS consisting of tetraalkylammonium cations and Tf2N- anion, sometimes abbreviated as TFSI- anion, was found independently by MacFarlane et al.11, 12) and Matsumoto et al. 13) This type of RTMS, which is commonly named ""ammoniumimide"" salt, has a wide electrochemical window of ca. 5 V and, thus, the RTMS seems to be suited for practical application as a solvent for the electrodeposition process. In this paper, we report the electrochemical behavior of copper species in an ammoniumimide RTMS, trimethyl-n-hexylammonium bis(trifluoromethanesulfonyl)amide (TMHA-Tf2N)."

Jan 1, 2000

By W. Kunda

A laboratory study was carried out on the treatment of sulphidic copper concentrates in aqueous chloride systems under elevated temperatures and oxygen overpressure. Exploratory tests showed that chalcopyriteoxidizes with various chloride salts to form, depending upon the pH of the system, soluble copper chloride or insoluble copper oxychloride salts; the copper can then readily be recovered from the solution or residues respectively. During the leaching, iron was oxidized to iron oxide and remained in the leach residue while the bulk of the sulphide sulphur was oxidized to the elemental form with a minor portion oxidized further to sulphate. The presence of metal chloride salts in the system increased the oxidation rates of chalcopyrite and depressed the solubilization of iron in the system. A systematic oxidation leach study carried out in (1) ammonium chloride and (2) sodium chloride systems showed that the former system required little or no HC1 addition while the latter required 2 mol of HC1 per mol of dissolved copper (plus zinc). The copper was recovered from the cuprous or cupric chloride leach solutions by cementation with iron. Extractions of 99% copper and zinc, 97% silver, and negligible iron were obtained. Sulphur was oxidized to the elemental or sulphate form; the relative proportions of the total sulphur were 60 and 30% for system (1) and 80 and 10% for system (2). A flowsheet for a conceptual process with minimal reagent requirements was proposed.

Jan 1, 1976

By Aiyuan Ma, Tu Hu, Chenyu Sun, Yonggang Zuo, Hongying Xia, Jinhui Peng, Libo Zhang, Yongguang Luo

"In this study, the adsorption characteristics of tannin acid in aqueous solution were investigated using regenerated activated carbon (AC), with the aim to remove the tannin acid organic matter from the solution after zinc hydrometallurgy and Ge precipitation. Results showed the temperature has little effect on the adsorption ability (q.) of the regenerated activated carbon. The experimental equilibrium data were tested for the Langmuir and Freundlich isotherms. The adsorption equilibrium was better described by the Langmuir isotherm (R2 > 0.99). Pseudo first- and second-order kinetic models were used for describing kinetic data. It was determined that the kinetics of tannin acid removal was well fitted by second-order reaction.IntroductionGermanium recovery is a complex processes [1]. Hydrometallurgical processes are favoured and these are based on the precipitation of germanium as hydroxide or sulphide or alternately with tannic acid [2]. However, in the germanium recovery process, too much tannin is consumed by the germanium-tannins complexation process, and results in a high content of tannic acid remaining in solution, which is harmful to the valuable metal recovery [3]."

Jan 1, 2014

By Kazuhiro Asai

Hitachi Refinery of Nippon Mining & Metals Co., Ltd. installed a reverberatory type recycling fumace in 1978 in order to treat the industrial wastes which contain metal elements such as copper, gold and silver. Pyrite and industrial waste materials such as galvanizing sludge, hydroxide slime and dust are smelted. Sulfidized copper, iron and precious metals are transformed into matte and other metallic elements are oxidized into slag This copper matte is transported to Saganoseki smelter and copper and precious metals in the matte are recovered. Recently it is difficult to obtain pyrite economically because of the decrease of pyrite production. Therefore, a new treating process of the liquid waste has been investigated at Hitachi Refinery. In this process, the sulfide or sulfate from the liquid waste are smelted as a source of sulfur.

Jan 1, 1997

By Hideki Minoura

"Two novel electrochemical techniques for the preparation of highly crystallized CdS film have been presented. One is cathodization of a conductive substrate in an acidic chemical bath containing cadmium salt and thioacetamide, where electroreduction of proton at small current densities induces a growth of highly crystallized CdS thin films, whose growth is not disturbed by the reactions in the solution phase. The other technique is electoreduction of aqueous Cd2+— SCN complex. An advantage of this technique lies in no formation of solid particles in the bulk, of the bath.IntroductionIn recent years much attention has been paid to materials preparation by solution processing because of its advantages in lowering the cost as well as the stress to the environment, as compared to the conventional gas phase techniques which unavoidably require high temperature and/or vacuum. We have been trying to explore novel techniques for preparing functionalized compound semiconductors by aqueous solution process. Semiconductors which we have been mainly focusing on are CdS and ZnO, which are important semiconductors finding applications in various devices. In the present paper, some of the techniques that we have recently established for the preparation of highly crystallized CdS will be presented.Methods of the CdS film processing in solution phase (wet process), which have been reported so far can be divided into two major groups; one is chemical bath deposition (CBD) in alkaline solution containing Cd2+ and thiourea 1)4) and the other is electrodeposition (ED) in acidic solution containing Cd2+ and thiosulfate ions - 5)-8) or organic solutions containing dissolved sulfur 9)-11)."

Jan 1, 2000

By P. G. Comba

Many gold producing states are requiring rinsing of spent heaps to render the leached ore compatible with the environment and are placing restrictions on effluent pa, cyanide, and metals concentrations. Parameters which may affect efficient rinsing of heaps have been investigated by the U.S. Bureau of Mines in laboratory column studies. Rinse profiles for cyanide, metals, and pH as a function of the volume of water passed through the spent ore are presented. Fresh water rinsing of spent ore in columns showed that rinsing of cyanide was not affected by the rinse solution application rate. Interrupted rinsing with a rest period between applications reduced the volume of water required to meet effluent cyanide concentrations. chemical oxidation of the effluent with recycle of the rinse solutions reduced effluent cyanide concentrations and the volume of waste solution generated. Water rinsing was not successful in reducing the alkalinity of the cement agglomerated ore. A dilute acid solution had to be applied after cyanide removal to reduce effluent pa levels to specified limits.

Jan 1, 1992

By E. T. White, Dean Ilievski

"Mathematical modelling of the precipitation process requires that the kinetics of crystal growth, nucleation and agglomeration be known. This paper reviews the current state of knowledge on these precipitation sub-processes (ie. growth, nucleation and agglomeration) and describes a number of experimental techniques for estimating their kinetics. The experimental methods used to generate the precipitation data and the data analysis techniques used to extract the kinetics information from the data are discussed separately. There is no universal ""best"" technique for determining the kinetics. However, studies on multi-crystal systems are more reliable for modelling purposes than are single crystal studies. The selection of a technique will depend on which sub-processes are present. A problem with all kinetics studies is that there is generally a large uncertainty in the estimated kinetic parameters. This stems from the scatter in the experimental data being further propagated by the mathematical techniques used to extract the kinetic parameters.IntroductionCrystallisation operations, including precipitation, are widely used in a number of hydrometallurgical processes to recover a desired component or to remove an undesired impurity. The goals of industrial precipitation processes are to maximise the recovery while maintaining product quality (generally product crystal size distribution, purity and morphology and product handling properties). Knowledge of the precipitation mechanisms and kinetics is invaluable for designing new precipitators or for improving existing units. The mechanistic and kinetic information is generally incorporated into mathematical precipitator models, which are then used for process design and optimisation."

Jan 1, 1996

By Michel Boisvert

Noranda Metallurgy is presently completing construction of the new Noranda Converter (NCV) at its Home Smelter in Rouyn-Noranda. This capital investment of CDN$56M is the continuation of the Emissions and SO2 Reduction Program that was initiated in the late 1980s with the acid plant for Reactor off-gas treatment. The Patented Noranda Converter was developed and pilot tested at the Home Smelter in the early 1990s. The project will replace the Peirce-Smith Converters and enable sulphur fixation to be 'increased from 70% to over 90% by 2002 with an accompanying reduction of dust emissions to the atmosphere. The construction site is an extension of the present Noranda Reactor area. A number of existing facilities including the acid plant and process air supply were used to minimize the capital cost of the project. This paper provides a brief history of the Noranda converting process, the Home Smelter Emissions and SO2 Reduction Program, ,project implementation and construction, a description of the different facilities, and preparation of human resources for start-up.

Jan 1, 1998

By Makoto Ohlsuka

The ternary Ni2MnGa intermetallic compound is an intelligent material which has both a ferromagnetic property and a shape memory effect (SME). The use of the shape memory alloy films for an actuator of micro-machines is very attractive because of its large recovery force. The purpose of the present study is to investigate the effects of fabrication conditions and to clarify the relationships between these properties and fabrication conditions of the Ni-Mn-Ga films. The Ni-Mn-Ga films with a thickness of nearly 5 um were deposited with a radio-frequency magnetron sputtering apparatus using a Ni50Mn25Ga25 or Ni52Mn24Ga24 target. They were heat-treated at various temperatures between 873 and 1273 K for homogenization and ordering and then cooled in a furnace. The composition of the films depended on the sputtering power. The as-deposited films were crystalline and had columnar grains. After the heat treatment the grains widened and the grain boundary became indistinct with the increasing heat treatment temperature. The martensitic transformation temperature of the heat-treated films increased with increasing nickel content. Furthermore the effect of plastic deformation and constraint aging on SME is also investigated. After plastic deformation, the two-way SME was shown through the martensitie transformation and its reversion, The intensity of X-ray diffraction peaks from stress-induced martensitie phase was found. The constraint-aged films also showed the two-way 3ME by thermal cycling.

Jan 1, 2003

By Yuanbo Zhang, Mingjun Rao, Guanghui Li, Chongzhong Ouyang, Shuhui Zhang

Oolitic hematite ore with high-phosphorus content is currently recognized as one of the most refractory iron ore resources in the world. The high-phosphorus content and unique structure of the oolitic hematite ore make it difficult to be beneficiated. The process of direct reduction followed by magnetic separation has significance to the utilization of oolitic hematite ore, and sodium salts can improve the dephosphorization. However, the behavior of phosphorus during reduction roasting, and the intensified dephosphorization mechanism of sodium salts are not clear. In this study, by using chemical analysis, chemical phase analysis, XRD analysis, optical microscopy, and scanning electron microscopy analyses, the behavior of phosphorus during reduction roasting of high-phosphorus content oolitic hematite ore and the effect of sodium salts on behavior of phosphorus were studied.

Jan 1, 2015

By Makoto Ohtsuka

The ternary Ni2MnGa intermetallic compound is an intelligent material which has both a ferromagnetic property and a shape memory effect (SMB), The use of the shape memory alloy films for an actuator of micro-machines is very attractive because of its large recovery force, The purpose of the present study is to investigate the effects of fabrication conditions and to clarify the relationships between these properties and fabrication conditions of the Ni-Mn-Ga films, The Ni-Mn-Ga films with a thickness of nearly 5 um were deposited with a radio-frequency magnetron sputtering apparatus using a NisoMn2sGa25 or Nis2Mn24Ga24 target. They were heat-treated at various temperatures between 873 and 1273 K for homogenization and ordering and then cooled in a furnace, The composition of the films depended on the sputtering power. The as-deposited films were crystalline and had columnar grains, After the heat treatment the grains widened and the grain boundary became indistinct with the increasing heat treatment temperature, The martcnsitie transformation temperature of the heat-treated films increased with increasing nickel content. Furthermore the effect of plastic deformation and constraint aging on SME is also investigated, After plastic deformation, the two-way SME was shown through the martensitie transformation and its reversion, The intensity of X-ray diffraction peaks from stress-induced martensitie phase was found, The constraint-aged films also showed the two-way 5MB by thermal cycling,

Jan 1, 2003

By M. J. Soria-Aguilar, F. R. Carrillo-Pedroza, S. Preciado-Nuñez

"Dust originated from the Iron Blast Furnace (BF) and the Basic Oxygen Furnace (BOF) containing alkalis and zinc are not completely recycled because due affects the process efficiency. These types of dust represents an economical lost as a consequence of values contents of iron and carbon. Several processes in aqueous media have been developed to treat the steelmaking dust. This work presents a laboratory study for reduce zinc and alkali containing in BF and BOF dust, using different acid and alkaline solutions and oxidants as ozone. The results obtained show that the elimination of zinc and alkalis can vary from 5 % to 80 % depending on the treatment conditions (the solution, the oxidant and the temperature). The dust obtained from this treatment can to be recycling to the steelmaking processes to recovery iron and carbon values.IntroductionEach one of the steel making industry processes generate several sub-products and residues containing useful units of iron, carbon and other elements that are or could be recycled to the productive process. Some of those sub products are the dust from the gas cleaning system of the blast furnace and the dust from BOF reductive process; such dusts are sent to the sedimentary lagoons. The dust represent a lost of 2 % of the total iron and coal mineral’s content feed to the process.The typical iron, carbon and zinc content of the blast furnace dust is approximately 40, 24 and 0.3 % and the content of the BOF dust are 50, 15 and 0.9 % weight respectively, with physics - chemical characteristics that became them susceptible to be agglomerated and feed to the blast furnace. But the high content of zinc does not allow recycling it into the process. At the blast furnace the presence of zinc propitiate the formation of film in the furnace wall; these elements are vaporized in the low section of the cube of the furnace and they are dragged by the gases to the top and condensed again at the cube. Part of these condensed materials strongly adheres to the furnace cover harming it and reducing the empty space of that section, causing eventually a severe perturbation of the ascendant gas flux [1]."

Jan 1, 2008

By J. D. Law

The presence of long-lived radionuclides presents a challenge to the management of radioactive wastes. Separation of the radionuclides from the waste solutions has the potential of significantly decreasing the costs associated with the immobilization and disposal of the waste by minimizing waste volumes. Several solvent extraction processes have been developed at the Idaho National Engineering and Environmental Laboratory for the separation of transuranic elements (TRUs), 90 Sr, and/or 137 Cs from acidic radioactive waste solutions. The TRUEX and POR processes for the separation of TRUs, the SREX process for the separation of 90Sr, the cobalt dicarbollide process for the separation of 137Cs and and a universal solvent extraction process for the simultaneous separation of TRUs, 90Sr, and 137Cs have all been developed in centrifugal contactors using actual liquid radioactive waste solutions and simulated dissolved calcine waste solution. In addition, the behavior of metals with each of the solvent extraction processes was evaluated. This article summarizes the most recent results of the each of the flowsheet demonstrations and provides Information on the centrifugal contactor equipment used for the testing.

Jan 1, 1999