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By K. O. Fagerlund

Theoretically and experimentally determined copper matte settling rate in iron silicate slag has been discussed. Separation and settling rate measurements of sand, homogenised slag and 25%Cu concentrate, 63%Cu industrial, and 71%Cu synthetic copper mattes were carried out by mixing crushed slag and matte samples with silica sand in an alumina crucible and melting at 1300-1350°C. Two different types of slag compositions were employed, with Fe/SiO2-ratio 1.4 and 1.7. The separation rate was followed by taking samples from the .melt. As expected, the settling rate of copper matte in fayalite slag depended on the slag composition, where the increasing silica decreased the matte settling rate. Microanalysis of solidified slags showed that the rate of separation of low grade matte was low compared with high grade matte and the presence of a very small size fraction of matte droplets in slag remained unsettled in stagnant fluid. The production of sulfur dioxide gas inside the molten bath was found to be possible up to a certain iron sulfide content in the matte. Also, copper matte settling rates in industrial furnaces have been discussed.

Jan 1, 1999

By Sne?ana Devi

Mineralogy is a significant scientific discipline, essential in establishing the nature and the character of raw materials, regardless of whether they are monomineral or polymineral. Mineralogical characterization is very important, because its results give valuable information on features and nature of examined materials. Information's on mineralogical nature of mineral raw materials influence directly the quality assessment of a raw material, and thus the possibility of its use. The possibility of use of mineralogy in different industrial branches confirms constant activity of this scientific discipline. By use of methods within mineralogical analysis (optical microscopy, x-ray diffraction and others) data on mineral raw materials can be obtained as support in mineral raw materials quality assessment. Short description of results of mineralogical analysis of some mineral materials (granodiorite, dolomites, clay, refractory materials, slags and casting powders) in this paper shows the importance of its support to quality assessment and determine the possibilities of their use.

Jan 1, 2009

By Chai Li-yuan

The anodic behavior of AZ31 magnesium alloy in NaOH alkaline solution was investigated in this paper. The effects of anodizing parameters, such as applied current density, concentration of NaOH and temperature of the solution on the formation, structure and surface morphology of the anodic films were also studied. The formation of the anodic film was analyzed by analyzing the anodic polarization curves, the potential-time curves and XRD, SEM graphs of samples obtained at different anodizing time. The results of corrosion resistance tests, XRD and SEM observation showed that the temperature greatly affected the formation and anti-corrosion property of the anodic film, but the concentration of NaOH not. The film with best anti-corrosion resistance was obtained at applied current density of 10mA/cm2, 353k in 1mol/l NaOH solution.

Jan 1, 2006

By Ryosuke O. Suzuki

A combined process of electrolysis of CaO in the molten CaCl2 and of calciothermic reduction, so-called OS process, was applied to prepare metallic vanadium directly from V2O3. The fine metallic powder containing 1860 mass ppm oxygen was obtained using 0.5mol%CaO-CaCl2 melt for 10.8 ks at 1173 K. The oxygen level did not decrease further even when twice electricity was applied. Because the metallic vanadium could be electrochemically deoxidized to the level of 10 ppm oxygen from 1.48 %, the large amount of by-product, CaO, due to reduction and the large surface area of the fine particles are the reasons of high oxygen content in the reduced powder.

Jan 1, 2006

By E. J. Peuraniemi

Recently commissioned Kennecott-Outokumpu flash converting was developed to replace the approved but environmentally outdated Peirce-Smith -converting to satisfy the globally tightening emission regulations. In the present study, dust formation and reaction mechanisms of two copper mattes with different experimental parameters were studied in lean suspension conditions. Both mattes had very high copper content of approximately 75 wt% and low iron content of 4.5 wt% and 1.2 wt% Fe. A laboratory scale, vertical laminar-flow furnace with a low feeding rate was used to simulate the phenomena taking place in the reaction shaft of a flash converter. Experimental conditions included temperature of 1300 °C with reaction gas oxygen contents of 20 vol%, 50 vol%, and 75 vol%. In the experiments, sieved particle fractions were fed to the furnace and sampled after short reaction time intervals by quenching them into a water film. Collected particles were analysed chemically for their main elements to define their removal rates. Also, optical and scanning electron microscopy with EDS-analyser were applied to determine phenomena occurring during reactions. Kinetics of oxidation as well as ignition of particles are discussed. Changes in particle morphology, size, and composition are reviewed to describe dust formation and reaction mechanisms.

Jan 1, 1999

Four slag types covering the range of Fe-Ca-Si-O compositions and two iron blast furnace slags were melted at 1300 °C and doped with 1% of arsenic, antimony, cadmium, zinc and chromium. The melts were either slow cooled or quenched and the solidified slags were leached according to TCLP procedures. The morphology of the solidified slags was characterised using XRD, optical and electron microprobe techniques. Theoretical considerations showed that the capacity of the molten slag to hold the above toxic elements depended upon slag basicity and this was confirmed in practice. The experiments showed that the leaching of the toxic elements was a function of surface area and the phases present, both of which were affected by the mode of cooling. Iron silicate slags produced in nonferrous smelting operations and blast furnace slag from ferrous smelting operations both show promise of being suitable media for immobilising low levels of toxic elements and complying with current regulatory requirements.

Jan 1, 1994

By G. Cifuentes

When the applied current is interrupted in a copper electrowinning plant, and then is back in operation, the lead anodes tend to corrode. In order to decrease the corrosion, the damage protective ("back up") anodic currents are applied during the period of interruption. The current work aims to establish the effect of the concentrations of sulphuric acid, copper and cobalt on the anode corrosion, to quantify the effect of various anodic protection levels on the anode corrosion and to propose a method to select the appropriate protective current density value.

Jan 1, 1999

By H. Masuda

The lijima Zinc Refinery started operation in 1972, and has today an annual capacity of 200,000t-Zn. The hematite process was employed for the first time and the ideal of waste-free refinery has been pursued for 30 years. In recent years, however, only half of the hematite produced would be sold to the cement industry and hence a reduction of arsenic level has been necessary in order to sell the entire amount produced. The arsenic cementation process with zinc powder, developed through a long time laboratory research was found among some options as the best for the hematite process. The construction work started in 2000 and the facility was put into operation in 2001, As a result in the same year all hematite were sold to the cement industry. The outline of this project, present operations and technical issue are reported in this paper.

Jan 1, 2003

By C. Lupi

Zinc chloride electrowinning presents difficulties in obtaining smooth, compact and dendrite free deposits with a high current efficiency due to the presence of undesirable metal ions. However, it is hard to define a level of impurities tolerable in zinc deposition, and despite a lot of research in this field, the reaction mechanisms of the undesired metal ions are still not clearly understood. In this study, the influence of Fe, Cd, Co, Ni and Cu additions were investigated, as well as their synergic effect on the zinc electrodeposition process from chloride electrolytes and on the obtained deposit morphology. The tests were all performed in presence of TBACl which reduces the harmful effect of such impurities on the zinc reduction.

Jan 1, 2003

By Bruce R. Conard

Consideration of environmental and human health issues in metallurgy is growing rapidly. While not all metallurgists need to have detailed expertise in environmental and health questions, they should be aware of the challenges the metals industry faces, be able to interact with colleagues in other sciences and contribute to sound metal resource management. Hydrometallurgists occupy a unique position among metallurgists because of their knowledge of the behaviour of metals in aqueous systems, which are of fundamental importance in understanding environmental chemistry and human toxicology. As a result, hydrometallurgists should more frequently and passionately lend their expertise in assessing environmental and health risks of metals and in helping to develop effective global guidelines, regulations and process and product stewardship strategies, thereby enabling metals to continue their beneficial service to society.

Jan 1, 2003

By Somayeh Dashti, Ehsan Vahidi, Fereshteh Rashchi

"The main goals in zinc electrowinning process are decreasing of power consumption and increasing of current efficiency. In this study, the electrowinning of zinc in the presence of different additives in electrolyte were established and Arabic Gum, Gelatine, sodium lauryl sulphate and l-hexyl-3-methylimidazolium hydrogen sulfate in the five levels using Taguchi method was examined. In our previous researches, using orthogonal array, effect of zinc electrowinning parameters such as anode type, current density, sulphuric acid concentration, temperature and zinc ion concentration was studied and the optimized conditions for zinc electrowinning was obtained. Anode composition: Pb-Ag 0.5%-Sn2%-Sb1%, current density (A/m2):500, acid concentration (g/1):165, temperature: 60°C, zinc ion concentration (g/1):70. The main goals in zinc electrowinning process are decreasing of power consumption and increasing of current efficiency. ln this research, the effect of four additives: Gum Arabic, Gelatine, sodium lauryl sulphate and an organic material in the four levels with Taguchi method was examined. ln fact the effect of electrolyte environment and determining the best electrolyte under the optimized conditions is the main aim of this study.IntroductionDue to its low cost and abundance, zinc is widely used in the production of brass, galvanized steel, sacrificed anodes and primary and secondary batteries [I]. Some 80% of world primary zinc production is derived via roast-leach-electrowinning processes [2-4]. In the electrowinning process to both improve final product quality and current efficiency the leachate should be purified [5].To produce zinc a current method is to extractit from acidic zinc sulphate solutions by electrolysis with aluminum cathodes and insoluble lead-based anodes [6]. Though the electrolytic processing of zinc has been performed for many years, there are still current efficiency problems in the cathodic process. These low efficiencies (88- 93%) have a serious impact on the costs associated with the energy consumption. On the other hand, these low efficiencies increase energy consumption and decrease the quality of the surface morphology [7- 8]."

Jan 1, 2012

By Richard D. Hagni

The United States is dependent upon foreign sources for more than 93% of its bauxite and alumina supply. Domestic production of bauxite, which comes from Alabama, Georgia and Arkansas, is limited to those bauxite ores containing less than about l ½ % iron. Bauxites with higher iron contents are generally not utilized because they cause problems in bauxite calcining and especially because they produce undesirable brick discoloration and cracking. In order to improve beneficiation and expand the utilization of high-iron or ferruginous bauxites, a mineralogical and textural study has been conducted on selected samples from the Eufaula, Alabama, bauxite district. Reflected light microscopic, petrographic, and X-ray techniques have shown that a variety of iron minerals are present, including hematite, goethite, lepidocrosite, siderite, pyrite, marcasite, and ilmenite. Although the iron minerals may be locally concentrated into concretions and pisolites, most occur as very fine grains that are disseminated and show a variety of intergrowths. Mineralogical and textural observations indicate that the fine-grained iron mineral grains may be amenable to high gradient magnetic separation.

Jan 1, 1981

By G. Cifuentes

It's know that the cathodic purity and the electrolyte treatment is affect for the solid present in the electrolyte. Anodic slimes properties (f.e.: chemical composition, crystalline composition, sedimentation) was studied in copper electrorefining, this properties were modify through by anodic composition and current density. In this paper will be present only the preliminary anodic slimes relationship at different lead anodic composition. The anodic material was doped during the poured process with lead at different composition. It's confirm the apparition of the (Bindheimitte) SMbz07. The specific gravity of this specie is approximately 7.3 - 7.5, with this values is biggest the probability of sedimentation and smaller the slimes not sedimentabel.

Jan 1, 1999

By C. Sui

A common objective in many Cu/Zn concentrators is to reduce the loss of Zn to the Cu-concentrate. One suspected source of the problem is accidental activation of sphalerite by heavy metal ions such as lead. One method of quantifying surface metal ion concentration is extraction with ethylene-diamine-tetra-acetate (EDTA). This was used to survey Cu-rougher flotation at three Cu/Zn concentrators: Les Mines Selbaie, Falconbridge's Kidd Creek division, and Hudson Bay Mining and Smelting Although all have less than 0.2% galena in the ore, Pb ions proved an abundant extractable metal. From a laboratory study a model of surface coverage of lead species generated by an ore was combined with an estimate of surface concentration of lead required to activate sphalerite to explore the possibility of accidental activation. Ores with Pb-grade as low as 0.1% can produce sufficient Pb to be a potential problem.

Jan 1, 1999

By William Petruk

An investigation was conducted to determine types of particles that tend to be recovered in concentrates by mineral beneficiation. It was found that, in concentrates of the same grade the proportion of desired mineral occurring as apparently liberated grains varies widely. In contrast the proportion is nearly constant when the grains considered are apparently liberated grains plus unliberated grains in particles composed largely of the desired mineral. It was also found that the types of particles which tend to be recovered in concentrates are dependent upon the concentrate grade. Hence it is much more important to determine the characteristics of recoverable particles and to measure the percentage of mineral that occurs in recoverable particles. than to measure the percentage of totally liberated mineral. A relationship between concentrate grade and type of particle that tends to be recovered in concentrates was established.

Jan 1, 1989

By Brian G. Thomas, Quan Yuan, Rajneesh Chaudhary, Rui Liu, Sana Mahmood

"A particle-entrapment model based on local force balances has been developed, implemented into computational models of turbulent fluid flow, and applied to simulate the entrapment of slag inclusions and bubbles during the continuous casting of steel slabs. Turbulent flow of molten steel is computed in the nozzle and mold using transient CFD models. Next, the transport and capture of over 30,000 particles are simulated using a Lagrangian approach. Particles touching the dendritic interface may be pushed away, dragged away by the transverse flow, or captured into the solidifying shell according to the results of a local balance of ten different forces. This criterion was validated by reproducing experimental results in two different systems. Finally, the model is applied to predict the entrapment distributions of different sized particles in a typical slab caster. Although more large particles are safely removed than small ones, the capture rate as defects is still high.IntroductionSurface defects such as slivers and blisters are often caused by captured inclusion clusters, slag, bubbles, and other particles. During continuous casting, jets of molten steel from the submerged entry nozzle (SEN) ports carry bubbles and inclusion particles into the mold cavity from upstream processing, as shown in Figure 1 [1]. In addition, droplets of liquid mold slag may become entrained into the flowing steel due to fluid flow problems, via several different mechanisms [2]. Figure 2 shows some typical inclusion particles [3] that can be entrapped from the flowing liquid into the solidifying steel shell to form defects in continuous-cast product.Liquid steel flow in the continuous casting mold has been modeled extensively. Reynolds Average Navier-Stokes (RANS and URANS) approaches are based on accurate computation of the ensemble-averaged velocity field. Particle transport can be tracked using a Lagrangian approach, introducing an extra model, such as ""random walk"" to generate realistic motion of every particle. Large Eddy Simulation (LES) models can accurately calculate both the transient evolving flow field and Lagrangian particle motion [4, 5] of this turbulent process."

Jan 1, 2012

By Gunther Schimmel

Ag exudation in four different alloys (Ag-Cd, Ag-Sn, Ag-Sn-In and Ag-Zn) is characterized. The amount of exuded material is correlated with the volume increase due to oxide formation in dependence of the alloy concentration and different densities of the oxide and matrix phases. It is shown that all four alloys show similar amounts of volume increases, but different amounts of exuded material. It is concluded that internal stresses due to the volume increase cannot be the dominant driving force for Ag exudation. A gradient in the chemical potential of Ag that originates from the O concentration gradient inherent to internal oxidation is suggested as driving force. The exudation behavior is thus governed by the variation of the activity of Ag in the Ag fcc phase in the Ag-Me-O system that differs between the alloying systems.

Jan 1, 2010

By T. A. Venugopalan

The 'Hall-Heroult' Process of reduction of Alumina to Aluminium has remainded basically the same for over 100 years, but the technology has been undergoing drastic changes with respect to selection of materials for Cathode and Anode, and also energy consumption. The latest generation pots have a working life of about 1800-2000 days normally. After the failure of the pots, the Cathode Lining is dug out and disposed of on land. Since the lining contains objectional materials causing pollution, various processes have been tried for re-processing of this waste. However, most of the processes have been unsuccessful from the techno-economic point of view. At Hindalco a new chemical process for converting the fluorine values of the dug out material to Cryolite was developed in 1988 and a" one ton per day Cryolite production plant has been operating since 1989. This process is especially applicable where the integrated Alumina and Smelter Plants exist side by side. The experience in operating this Plant is discussed in detail in the paper.

Jan 1, 1992

By M. E. Ramos Rada

Mexicana de Cobre, which is part of Grupo Mexico, carried out studies for the construction of a copper refinery in the La Caridad Metallurgical Complex located in Nacozari, in the state of Sonora, Mexico. After the studies were concluded, the decision was made to construct a 180,000 t/y refinery using the state of the art permanent cathode Kidd Process. The basic engineering was developed by Fluor Daniel and the detail engineering and the construction were carried out in record time by the Mexican company Bufete Industrial. During the construction phase, Grupo Mexico decided to expand the refinery, and actions were taken to increase its capacity by an additional 120,000 t/y; the final result was a refinery capable of producing 300,000 tonnes of grade A cathode per year. Construction began in January 1996, and the operation of the first stage began on July 1, 1997. The operation of the second stage commenced on January 7, 1998. The capacity of the first stage was reached in November, 1997 and the total capacity of the refinery was achieved in May, 1998. This presentation describes the process and equipment installed in the refinery, the steps leading to the start-up, the operation and the results obtained during the first two years, the handling of anodes with high impurity contents, and the problems confronted and the way they have been solved. It also includes personnel productivity, the control parameters and the most relevant data on the operation of the process.

Jan 1, 1999

By Brian Cochran, C. Edward Eckert

"EXECUTIVE SUMMARYINTRODUCTIONThe commercial incentives for using molten aluminum in casting operations are numerous and substantial. Although these incentives apply broadly to both shape castings (foundry) operations and wrought alloy production, the merit of a particular motive is indeed downstream processing sensitive. Melting cost reduction is a universal incentive that impacts on essentially all aluminum products. At a natural gas burner cost of $4.50 per therm, for example, the reverberatory furnace energy cost is at least $0.01 per pound of aluminum melted, exclusive of melt loss, fixed costs, and other expenses. The Aluminum Statistical Review' cited 3.188 million metric tons of secondary aluminum that was recovered by the industry in 1995. This represents a re-melt energy cost of over $70 million. Other incentives to use molten secondary aluminum include throughput enhancement, metal chemistry assurances, environmental considerations, and the avoidance of an in-house scrap processing operation.A traditional disincentive to use molten secondary aluminum is metal quality. If a particular secondary processing operation was successful in achieving and preserving an acceptable metal quality level prior to shipment, the subsequent metal transfer and ladle delivery events would frequently obviate these efforts. For example, a metal superheat on the order of several hundred degrees is required for an unheated transfer ladle to travel 3 to 4 hours to a customer location. The rate of the y-alumina formation reaction approximately doubles for every 120°F increase in temperature, therefore, the effect of excess superheat on melt loss and metal quality is considerable. Linear oxidation reactions, such as magnesia formation in magnesium containing alloys, are influenced to an even greater extent by temperature.The typical quality detractor events are:"

Jan 1, 2000