Search Documents

By Niko Hellstén

To capture efficiently the valuable trace metals from nickel slag using electric furnace, it is important to study their distributions between the slag and metallic phases in the furnace. It is impossible to calculate accurately these distributions without experimental measurements. Therefore, in this work, selected trace metal distributions and phase equilibria between K2O containing iron-silicate slags and a metallic Ni-Fe-Cu alloy in nickel slag cleaning furnace conditions were studied. The experimental method developed and applied during the work, involved a modified quenching technique that included equilibration of the samples in semi-sealed quartz ampoules in an inert atmosphere and metallic Fe saturation. The use of the semi-sealed quartz ampoule prevents the escape of volatile elements from the sample during equilibration. Chemical compositions of the phases and the trace elements were analysed by EPMA. From the measured compositions, the trace metal distribution coefficients between the molten Ni-Fe-Cu alloy and slag were calculated.

By U. Lauwers

The influence of different waste materials in sinter blends on the quality and mineralogical composition of a sinter is described. As a result of partial preservation of the original textures of waste materials in the final product the degree of assimilation of the original material in the sinter product can be ascertained. Recycling of waste materials such as dolo char , arc-furnace slag, scrap fmes, mill scale and BOF-mud via the sintering process a saving on costs of raw materials such as flux and fuels, and a reduction on pollution can be achieved. A comparison of a typical sinter with a sinter produced through the utilization of waste materials showed a distinct correlation between certain types of waste material and some metallurgical properties. Dolochar in a sinter blend acts as part of the fuel and flux that are normally added to a sinter mix. Generally dolochar improves the quality of the sinter and decreases the consumption of coke. Other waste materials adversely influence the quality of the sinter. The glass and calcium ferrite content of a sinter when dolochar is used in the blend is similar to that of a sinter produced with only coke as a fuel in the sinter mix. The glass content is lower and the calcium ferrite content is higher, in a sinter produced from dolo char in the blend compared to a sinter produced with additions of other waste materials. Changes in the mineralogical composition are related directly to the metallurgical properties of the sinter product.

Jan 1, 1991

By N. Tsuchida

Sumitomo Metal Mining Co. Ltd. (SMMC) is currently developing the flowsheet to treat stockpiled limonite, a type of laterite ore, at Rio Tuba on southern Palawan Island, Philippines. The new plant will be commissioned at the end of 2004. Rio Tuba Nickel Mining Corporation (RTNMC) has been mining saprolite since 1977, and the limonite ore located above the saprolite ore body has been stockpiled separately according to nickel and magnesium content. Ore from these stockpiles will be blended and used for the operation. The annual production of nickel will be 10,000 metric tons for the next twenty years. The proposed process consists of ore preparation, high pressure acid leach (HPAL), counter- current decantation wash, impurity removal and sulfide precipitation. Precipitated mixed sulfide will be processed to electrolytic nickel by the Matte Chlorine Leach Electrowinning (MCLE) process at Niihama, Japan. SMMC has established new technologies during the process development, such as zinc removal and sulfide precipitation. Applying this technology, preferential removal of zinc can be achieved by hydrogen sulfide gas with negligible loss of nickel. Precipitation of nickel by hydrogen sulfide gas is carried out at low temperature. Slow kinetics is selected for control of the particle size of the precipitated mixed sulfide. Keywords: HPAL, Zinc Removal, MS Production

Jan 1, 2004

By J. V. Atwood

The U.S. Bureau of Mines has developed a novel Double Membrane Electrolytic Cell (DMEC) that exhibits unique features for recycling contaminated metals and metal alloys. The DMEC incorporates two anionic ion exchange membranes, separating anodic and cathodic regions of the cell. The ion exchange membranes prevent significant transport of unwanted cationic impurities to the catholyte from the impure anolyte while the anion/cation balance in cell compartments is maintained through the free movement of anions between compartments. The membrane barrier makes it possible to electro refine highly contaminated materials or to electrowin from solution while utilizing alternate anode reactions. Sinceanolyte and catholyte cross contamination has been eliminated, premium cathode products are produced. The DMEC has been tested at bench, pilot, and commercial scales. Configuration of the DMEC, cell operation, scale, up efforts, and significant design factors are discussed. Two separate recycling investigations utilizing DMEC technology are presented. The first investigation examines recovery of high purity cobalt and nickel from severely contaminated super aIloy scrap. The second involves? upgrading contaminated cobalt in the U.S. Government's National Defense Stockpile. Capital and operating costs for both potential applications are presented.

Jan 1, 1995

By George Oprea, Tom Troczynski, Joe A. Rigby, Waiman Lo

The refractory lining of the tuyere line in Peirce Smith converters have usually much shorter life in service than the rest of the lining, above or below it. There are already recognized chemical, thermal and mechanical factors which contribute to the wear of the lining. Our study presents the experimental results on microstructural changes occurring on these tuyere line bricks in a nickelcopper converter. The experimental bricks, after use at the tuyere line, were investigated using SEM/EDS and XRD techniques, to identify the mineralogical changes due to interactions with the nickel-copper matte or fayalite type slag at the process temperatures. The microstructural changes were correlated with physical and mechanical properties of the brick before and after use and a wear mechanism was suggested. Although the matte does not theoretically react with the mineralogical components of the brick, a partial oxidation of the Ni-Cu sulphides was identified using a line analysis by SEM/EDS in the densified layer at the hot face, which allows for mineralogical changes at the matte-refractory interfaces, with a high probability of microcrack formation due to the thermal cycling during use. These microcracks were also identified to open through inter-granular fractures parallel to the hot face, which appeared to be the main cause of lost lining during use. The reactions between the fayalite slag and refractory brick could eventually play a role in chemical dissolution of the brick only in the superficial layer at the hot face, as no slag components were identified deep into the brick.

Jan 1, 2009

By J. L. Johnson

Remediation of small-arms firing ranges is being investigated by the Naval Civil Engineering Laboratory and the U.S. Bureau of Mines. Scheduled closures of military installations, as well as the management of active ranges, require the development of methodologies for heavy metals removal to prevent their entering the surrounding environment. The impact berms contain high concentrations of metals, and the soil and vegetation surrounding the berms were found to have slightly elevated levels. The heavy metals characterized are in the form of whole bullets, a wide size distribution of free fragments, smeared lead on the surface of the soil grains, and very finely attached particles. Gravity beneficiation can remove liberated metal contamination effectively. Weak acetic acid leaching shows promise in lowering the final metal contamination to allow the soil to pass the Environmental Protection Agency's (EPA) Toxicity Characteristic Leaching Procedure (TCLP) criteria.

Jan 1, 1991

By I. Iwasaki

Platinum group elements (PGE) are often found in arsenide and sulfarsenide minerals as inclusions in copper-nickel bearing gabbroic rocks. Major losses of platinum in flotation have been attributed to the poor recoveries of the arsenic minerals. Flotation characteristics of a synthetic nickel arsenide and arsenopyrite were studied through rest potential and oxidation rate determinations, surface analyses, and micro-and batch-flotation tests. The use of nitrogen during grinding and flotation together with copper activation improved the PGE recoveries from Duluth Complex ores. The flotation behaviors of the sulfarsenide minerals are still unresolved. The role that electrochemical interactions play among arsenides, sulfarsenides, sulfides and grinding media on their f10atabilities is discussed.

Jan 1, 1988

By R. M. Taylor

Lime addition to acid mine drainage (AMD) leads to precipitation, predominantly of metal hydroxides and calcium sulfate, and is the benchmark for remediation by precipitation. Geo2 Limited of Melbourne, Australia has developed and patented a novel alternative precipitation scheme based on the formation of mixed valency, M(I1)-M(III), hydroxide sulfate salts. When the composition of AMD is appropriate, the Green Precipitate Process provides a useful and more effective alternative to conventional liming. The characteristics and utility of the Green Precipitate Process are described in terms of the underlying chemistry, and a case study where the Green Precipitate process outperforms conventional liming. A mobile pilot pipe reactor rig which was built by Geo2 to demonstrate the process, and used successfully in both Australia and the United States, is described.

Jan 1, 1998

By T. T. Chen

Kidd Creek continuously-cast copper anodes are characterized by high levels of Se, Pb and Ag; the anode slimes constituents and their morphologies are controlled by both the anode composition and the casting process. Hollow Cu2Se spheroids and tube-like structures, enveloping Cu-Pb-As oxide and/or Cu2O, are present in the as-cast copper. During electrolysis, the selenides are liberated from the copper and accumulate in the slimes layer; the Cu2O and Cu-Pb-As oxide react rapidly with the electrolyte to form soluble species and PbSO4. Silver, which is present mostly as a solid solution in the anode copper, is also liberated during electrolysis and reacts with the Cu2Se to form (Cu,Ag)2Se. The ultimate composition of the selenides in the slimes layer depends mostly on the Ag and Se contents, but various other elements, including Au and Te, are also structurally incorporated. Although the selenides are the major Ag carrier, metallic silver also is present. A thin layer of Cu2O crystals sometimes forms at the copper surface, and may affect anode passivation. Copper sulphate is a common constituent and serves to agglomerate the slimes. Copper sulphate is present on both passivated and non-passivated anodes, but that observed on the passivated metal is present as a thick compact layer. Copper powder is associated with CuSO4.5H2O only on passivated surfaces.

Jan 1, 1987

By J. T. I. Poijärvi

Outokumpu Harjavalta Metals Oy operates copper and nickel smelters, three sulphuric acid plants and nickel refinery at Harjavalta and copper refinery and precious metal plant at Pori. The by-products of these plants are presented in this paper. The by-products of the smelters include products from slag cleaning of flash smelting furnaces and converters, flue dusts and smelter off-gases. Weak acid and sludges from cleaning of smelter off-gases and acids are the by-products of the acid plants. The by-products out of the copper refinery are crystallized metal sulphates and sludges from electrolyte purification, on which a co-production process of the copper tankhouse is based. The main by-products of the precious metals plant are products from anode slime treatment and platinum metal group concentrates in the recovery of precious metals. Sludges from nickel matte leaching and precipitates from solution purification are the by-products of the nickel refinery. The formation, treatment and processing as well as the research work done for the utilization instead of dumping of the by-products in the production of copper and nickel will also be discussed in this paper.

Jan 1, 1995

By Daniel K. Kim

The charge for the copper refinery is a mixture of anodes produced at San Manuel from BHP source concentrate and copper purchased from external sources. Control of unwanted impurities in the tankhouse - is very important and beneficial. Currently available removal/recovery technologies were reviewed for the control of bismuth and antimony levels in the electrolyte. Recent studies have focused on solvent extraction (SX) technology and generated successful results for the removal and subsequent recovery of bismuth and antimony. The SX system employs the reagent, ACORGA SBX-50, in conjunction with a patented high chloride stripping system. The latter enables recycle of the eluant, avoiding the high costs associated with conventional systems, such as regeneration of resin. Concerns over potential transfer of organics and chloride ion to the electrolyte were readily addressed, solved and demonstrated using conventional, established technology. This paper describes the benefits of electrolyte purification, the flexibility afforded by the SX system, the operational practices necessary for maintaining adequate control of bismuth and antimony impurities in the electrorefining environment and possibilities for future development /exploitation of the Zeneca SX system at the San Manuel refinery.

Jan 1, 1998

By Andrew Case

The Port Nickel facility in Braithwaite, Louisiana, is known for pioneering hydrometallurgical processes for the 'separation and recovery of nickel, cobalt and copper. Ten years ago, in 1985, a new CRI-MET process for the recovery of molybdenum, vanadium, nickel, cobalt and alumina from spent catalysts was developed and implemented. Spent- catalysts from the petroleum industry consietute the majority of feed. These are not only a valuable-source of metals, but due to EPA regulations are frequently classified as hazardous under RCRA. Molybdenum and vanadium are selectively leached in an oxidative hydrothermal step. Alumina is then extracted in a caustic digestive leach. The unique technology produces four primary commercial products l molybdenum trioxide, vanadium oxide, aluminum trihydrate and nickel-cobalt concentrate. This paper discusses the process, modifications. during ten years of operation, and the relationship of these modifications to the future of the catalyst recycling business.

Jan 1, 1995

By M. A. Kader, M. A. Islam, P. J. Hazell, M. Saadatfar, J. P. Escobedo, A. D. Brown

The present study investigates the dynamic deformation mechanisms of closed-cell aluminium foams during low velocity drop weight impact with experimental analyses and finite element (FE) simulation.The evolution of foam collapse was explored with FE simulation using ABAQUS/Explicit. X-ray computed tomography (XRT) based geometry was reconstructed to understand the actual microstructural changes during impact. The experimenta lstress-strain response was compared with FE simulation with reasonably good agreement observed between FE prediction and experimental data. A vertical cross-sectional XRT slice was analysed at different strains from FE simulation to understand the pore collapse mechanisms.

Mar 1, 2017

By Mark H. Hashiguchi

Examination of tensile bar surfaces shortly after destructive testing was conducted to search for clues that would aid in optimization of mechanical properties, especially tensile strength, yield strength and elongation to fracture. Cu-Ni-Si-Cr alloy bars in the as-cast, forged, rolled and extruded conditions were examined. Low ductility bars (<4% Elongation) showed dramatically different features than the fracture surfaces of high strength - high ductility bars (7 to 10% Elongation). Analysis of the fracture surfaces at 15X to 2000X and use of Energy-Dispersive X-Ray Spectroscopy (EDS) identified Ni-Si and Ni-Si-Cr precipitates of varying sizes and morphologies. Thermo-mechanical processing techniques to control the size and distribution of these precipitates show promise in improving the properties and performance of this alloy system and appear to correlate with improvements in the fracture surface morphology.

Jan 1, 2008

By T. Wang, R. G. Reddy, D. Mantha

"A new eutectic LiN03-NaN03-KN03-KN02 quaternary molten salt system was calculated using thermodynamic modeling. The eutectic temperature was predicted to be 100°C. The melting point and heat capacity of the salt eutectic composition were determined using DSC. The experimentally determined melting point is in excellent agreement with the predicted value. The melting point is more than 124°C lower than that of the KN03-NaN03 solar salt. The density of the molten salt was experimentally determined as function of temperature. Using the density, heat capacity and the melting point, thermal energy storage density and gravimetric storage density of the quaternary molten salt were calculated and compared with that of solar salt. The larger storage density value of this molten salt indicates that this salt has a better energy storage capacity for solar power generation systems.IntroductionMolten salts have been used as thermal energy storage media for solar energy applications. Nitrates are being used in the solar energy applications for their low melting point, low unit cost, high heat capacity, high thermal stability, negligible vapor pressure and high energy storage density [l]. Solar salt (NaN03/KN03: 60/40) is the most popular thermal energy storage medium which is currently being used with the freezing point of 221 ·c [2]; another ternary system HITEC® which contains NaN03, KN03 and NaN02 has freezing point of 141°C [3]. Newer nitrate salt mixtures are being studied and projected as potential candidates for thermal energy storage (TES) and heat transfer (HT) applications. Based on these favorable features, molten salt can work directly as the energy storage medium below 500°C [l]. Development and synthesis of newer molten salt mixtures with freezing point lower than those currently used for thermal energy storage applications is necessary for sustained utilization of solar energy. The approach to develop lower freezing point molten salt mixtures is by the prediction of new eutectic mixtures and also by the development of new nitrate compounds."

Jan 1, 2012

By Derek J. Fray

Electric arc furnace dusts, especially those containing zinc ferrite, are notoriously difficult to process to give valuable products and non-toxic residues. The ideal process would remove and recover the toxic non-ferrous metals as pure metals, of commercial value, and non-toxic residue which can be used as a raw material in the steel industry. From an examination of the thermodynamics of the oxides and chlorides of the various elements in the dust, it is apparent that the chlorides of the toxic non-ferrous elements are more stable than the oxides while the reverse applies to the ferrous elements. This offers the opportunity for a complete separation of the zinc, lead and cadmium from the iron oxide. Results are presented for the chlorination of electric arc furnace dusts under oxidising conditions and the subsequent treatment of the chlorides to recover the pure metals and chlorine which can be recycled back to the reactor.

Jan 1, 1994

By Axel Hoppe

Although Tantalum is not usually regarded as a precious metal, its pricing structure is very similar to that of Silver. Different from precious metals, Tantalum has only industrial applications and its use is about 1000 metric tons per year. The intrinsic value of Tantalum already in .the past was a driving force for its recycling. Based on these facts the Tantalum industry world-wide is approaching the closed-loop concept of its recycling. A detailed material flow of Tantalum processing as well as recovery of residues and used products will be discussed.

Jan 1, 1995

By Geza Kisvarsanyi

Ore deposits composed of enargite, tennantite, gold, and pyrite have been mined in volcanic rocks of Oligocene age (35 m.y.) at Recsk, Hungary. Vertical and horizontal zoning of the alunitic-argillic alteration and of the ore minerals led to the concept of an intrusive heat source at depth. Subse-quent drilling disclosed a series of ore deposits in a zoned pattern in and around a stock, separated by a barren gap of 1000 meters from the shallow ore. The ore system is in a intracaldera horst-graben structure, formed by collapse and intrusion in a microplate subduction. volcanic-arc tectonic environment.

Jan 1, 1987

By T. R. A. Davey

The technologies of lead, zinc and tin extraction have made varying degrees of progress over the past twenty years. Producers of all metals have faced increasing demands for reduction of pollution and environmental degradation, and the level of public concern is rising rather than abating. New processing techniques must therefore be not only economically feasible, but politically acceptable, even when the demands of "conservationists" and ?environmentalists? are unreasonable. A new generation of processing techniques has come into being, which do not rely on an expensive sintering stage, nor use metallurgical coke, which is difficult to make without serious pollution. They utilise intense reactors, conveying materials from one stage to the next preferably within an enclosed space, obviating fume emissions, and avoiding heat losses as far as possible. The acceptability of the new techniques? is increased if lowgrade or complex materials can be treated, along with a variety of returns and wastes. In addition, a good selling and servicing organisation seems to be as important as good process technology in determining the spread of the new processes. In the field of pyrometallurgical refining the need is for more general application of several recently developed techniques rather than a search for alternatives to the existing process technologies. However, there is a need for fundamental work investigating the phenomenon of oxygen anode overvoltage in the electrolytic zinc process, in order to make progress in the further reduction of energy consumption. There is also scope for further development and application of vacuum distillation to up-grade thermally produced zinc. This paper presents a personal view of processes which should be developed to overcome existing problems, as we approach the turn of the century,

Jan 1, 1990

By Richard A. Shulkosky

The American Iron and Steel Institute (AlSO, in conjunction with the U.S. Department of Energy (DOE) jointly funded the development of a mechanical properties model for Hot Strip Mills. INTEG process group, inc. validated an enhanced version of the model under a project funded by the AlSI/DOE Technology Roadmap Program (fRP). The Hot Strip Mill Model (HSMM) version 6.0 allows users to easily set-up their mill configuration, simulate a rolling mill schedule and calibrate the model for a variety of grades of steel. Starting from reheat furnace drop out, the model simulates roughing mill stands (reversing and continuous), heat retention equipment (coil box and covers), finishing mill stands (tandem and Steckel mills), the run out table and the mill exit area. The HSMM uses a series of physical models to calculate both the thermo-mechanical and the microstructure evolution of steel being processed in a hot mill to predict its final mechanical properties. The enhanced HSMM was validated using a multitude of samples from several steel companies. Excellent agreement was obtained for tensile strength. The supporting steel companies have utilized the model for a variety of practical applications. Keywords: Process Modeling, Microstructure Evolution, Mechanical Properties

Jan 1, 2003