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By M. Jortikka

The smelting process of the old reverberatory furnace including its capacity has been improved over the years in different ways eg. with oxy-fuel burners, parallel reactors with the reverb or with various modifications of the reverb furnace itself. The future reverb modifications with old concepts are difficult or impossible as the increased copper losses in slag call for separate slag treatment and particularly the process modifications do not solve the environmental issues but instead mean unavoidable high capital and operating costs in gas cleaning and sulphur recovery. During the last decades improvement in process performance and increase in capacity of copper flash smelters has been achieved easily by substituting the pre-heated process air by highly oxygen enriched air. The flash furnaces of today, however, are inherently designed to operate with high oxygen enrichment. Further process improvement with a view to production costs and capacity increase as well as to the more stringent environmental requirements is possible with even higher oxygen enrichment. This, apart from the advantages it generates, requires improvements in and careful design of the feed system, concentrate burner, furnace cooling and the off-gas line as well as adaption of the flash converting instead of the conventional Peirce-Smith converters. A logical answer even for the revamping of the reverb smelters in the future is the total replacement of the reverb furnaces with flash smelting together with flash converting. This paper discusses the possibilities for future process improvements of the existing flash smelters taking into account the process concepts, equipment modifications and capital aspects not forgetting the environmental issues. The revamping of the PASAR smelter in Philippines is introduced as an example of a recent success story.

Jan 1, 1994

By William K. Connor, O&apos

The U.S. Bureau of Mines (USBM), in cooperation with the American Society of Mechanical Engineers (ASME), conducted over 200 hours of melting tests to vitrify residues from five municipal waste combustion facilities. Combined residues (grate residue and f1yash) from three municipal waste combustors, a waste water treatment sludge combustor, and flyash from a refuse-derived-fuel (RDF) boiler, were sequentially melted in a I-metric-ton (mt) water-cooled-wall electric arc furnace. Each of the residues underwent magnetic separation, screen size analysis, and bulk chemical analysis prior to melting. The furnace products were examined by optical and electron microscopy and by X-ray diffraction. Bulk chemical analyses were acquired for the metal, fume, and vitrified furnace products. The material balance for the furnace operation indicates that from 69 to 86 pct of the feed reported to the vitrified furnace product, which had leaching potentials well below the EPA limit for each metal, as determined by the EPA TCLP. The electric arc melting furnace currently is being utilized in a cooperative research project between the USBM and the Idaho National Engineering 'Laboratory (INEL) for melting tests on simulated low-level radioactive wastes,

Jan 1, 1991

By John M. Gaines

Lead concentrates from the Viburnum Trend in the Southeast Missouri Lead district are sintered prior to smelting to bind the particles together homogenize the feed, and reduce the sulfur content. Good sinter forms competent masses about 4 to 6 inches across, that hal!e about 15% porosity and good mechanical strength to withstand transport and the weight of the overlying load in the smelter. Bad sinter has poor mechanical strength and forms fine fragments that retard the circulation of reducing gases in the furnace and lengthen the time required for reduction. The productivity of the lead smelter depends on good sinter feed. Because some lead sinter plants produce bad sinter about 20% of the time, this applied mineralogy study has been undertaken to determine the mineralogical and microtextural differences between good and bad sinter. A reflected light microscopic study of 130 polished sections has shown that good and bad sinters differ distinctly in their mineralogy, tex1ure. and character of, porosity. Good sinter consists of hardystonite, franklinite. lead-zinc-bearing magnesium-calcium silicate, lead silicate matrix, and large crystals of calcium-magnesium-iron silicate, together with minor amounts of lead oxides, lead-zinc silicate, metallic lead, specular hematite, magnetite, lead-iron-bearing zincite and zinc-Iead-magnesium-bearing wustite in a tightly intergrown mesh of crystals and with an evenly distributed porosity of 15% to 20%. Electron microprobe analyses show that the principal phases contain lead (or zinc): hardystonite (4-20% Pb) franklinite (2-14% Pb) and lead silicate matrix (65-74% Pb). Bad sinter differs from good sinter in the greater abundance of lead silicate matrix, galena metallic lead, and lead oxides and the lesser abundance of hardystonite, franklinite and calcium-magnesium-iron silicate. Bad Sinter is characterized by a lack of an intimate intergrowth of the constituent phases. Its porosity is much lower commonly 0 to 5% and those pores are concentrated in local areas rather than distributed evenly throughout the sinter.

Jan 1, 1991

By E. G. Noble

The potential for using heterotrophic microorganisms to solubilize manganese from low-grade domestic ores is being assessed at the Reno Research. center, U.S. Bureau of Mines. More than 90 pct of the manganese has been extracted from a variety of oxide ores in shake-flask tests using molasses as a source of .. nutrients for the microorganisms. It has also been demonstrated that high recoveries of manganese can be obtained from a domestic wad ore using column bioleaching. 'l'he isolation and identification of organisms responsible for manganese extraction is discussed, as are the mechanisms responsible for manganese solubilization.

Jan 1, 1991

By Caisa Samuelsson, Taishi Matsushita, Hannes Holmgren, Sina Mostaghel

"Rönnskär Smelter of Boliden Mineral AB, Sweden, is a large end-processor of secondary raw materials and waste, including electronic scrap. Electronic scrap may introduce various impurities to the smelter's flow-sheet, among which alumina is a common and significant one. This article summarizes the results of an ongoing research at Luleä University of Technology, Sweden, to study the influences of alumina on different properties of slag from the zinc fuming process at Rönnskär smelter. A combination of different experimental techniques and thermodynamic calculations have been used to investigate properties such as density, surface tension, effective thermal diffusivity, viscosity, and melting/leaching behaviors. Results show that the addition of alumina to this slag increases the degree of polymerization of the melt, and physical properties vary correspondingly. Mineralogy of the semi-rapidly solidified samples is also changed due to alumina addition. A correlation between mineralogy and leaching behavior can be observed.IntroductionBoliden's Rönnskär Smelter is a base- and precious-metals producer located in north of Sweden. Its main products are copper, zinc clinker, lead, gold, and silver. Sulphuric acid, liquid sulphuric dioxide and iron sand (granulated slag) are some of its main by-products. In order to optimize the overall outcome of the process, different refining units are integrated in the smelter's flow-sheet (Figure 1). Copper concentrates and fluxing materials (mainly silica sand) are charged to the process. The produced matte is sent to the converter and the generated slag is charged to the fuming furnace, where it is treated by reducing gases to produce zinc clinker. The converter's slag is charged to the electric furnace, while the fumed slag is tapped into the settling furnace for further cleaning, where matte, slag and speiss (residual metals) are separated. The matte from the settling furnace is also sent to the converters; its speiss is sold to external customers; and its slag is water granulated and sold as construction material, which is known as iron sand."

Jan 1, 2012

By Harald Laux, Stein Tore Johansen

The plunging jet in tapping of steel from converters or electric arc furnaces entrains gas into the steel bath contained in a ladle. Gas entrainment rate and the effect of the gas on the flow pattern in the ladle are studied by means of Computational Fluid Dynamics CFD. The work focuses on the mathematical modeling. Two numerical methods, one for free-surface flows and one for dispersed multiphase flow are combined. A transport equation for the average bubble diameter that incorporates the effect of coalescence and breakup is presented. Results from computations for one ladle and tapping configuration are shown. Our findings indicate that the gas entrainment rate is affected by the material properties of the liquid in the sense that the material properties determine the shape of the jet. Moreover, bubble sizes in the range of two-orders of magnitude are predicted in the ladle. The dispersed diameter model seems to work well. It showed the expected response to material parameters and the turbulent field. However, the presented analysis is just a first step that was limited due to certain simplifications. In order to obtain better insight in the tapping process improvements of the analysis seem necessary.

Jan 1, 1999

By Andrew L. Puwis

Methodologies were presented for computing the thermal gradient associated with single crystal solidification in macroscopic computer modeling. The. heat transfer, and solidification of a shaped investment casting model were simulated using properties from three different alloys. Following the simulation of solidification, the resultant thermal gradients (G) and rates of solidification (R) from representative points were extracted in various ways and compared: It was discovered that alloy properties have a strong influence on the computed thermal gradient and rate of solidification for the three methods investigated. Data also showed that the computed gradient for each model was very different depending on the temperature range used to compute these values.

Jan 1, 1994

By Andreas Siegmund

During the decade of the nineties the conventional method of primary lead smelting (sinter machine/blast furnace) was successfully challenged by the introduction of novel direct and continuous smelting processes. In combination with a significant shift in market structure, as well as more stringent government regulations these modem technological innovations like the QSL, Kivcet, and Isa/Ausmelt processes became more than major competitors. They have proven to be economically and environmentally viable. The intensification of the metallurgical reaction by applying oxygen enriched or pure oxygen bath or flash smelting principles resulted in cost savings and a higher flexibility with respect to raw materials and additives usage. By synchronizing individual auxiliary plant sections with the smelting process a virtually waste-free production and low-emission mode of operation with nearly optimum energy exploitation is achieved. The primary lead industry will gradually substitute the sinter -blast furnace operation with novel high-energy efficient technologies in the new millennium.

Jan 1, 2003

By Mariana H. Staia

The present communication reports the results obtained by applying different concentration methods, at laboratory level, to the black sands from Estado Bolivar, Venezuela, with the aim of obtaining an adequate ilmenitic concentrate for the subsequent chlorination process. Sizing analysis was performed and plasma emission spectroscopy method was used to determine the chemical composition. It was found that from the two hydrogravimetric methods used, the Humphrey spirals is much more effective than Wilfley tables, leading to a 85% recovery. The most convenient particle size group for these concentration methods was the one corresponding to ASTM 40-140 mesh. When magnetic concentration was applied to the concentrate, obtained as a product from Humphrey spiral, a recovery of ilmenite more than 90% was obtained in the first step. It has been shown that the ore would respond to the separation techniques employed, giving individual minerals: ilmenite, zircon and silica as concentration products.

Jan 1, 1995

By H. P. Wang, E. M. Perry

"Analytical solutions for investigating the solidification of casting problems with initial superheat and natural boundary conditions have been derived using an integral method. There are two moving interfaces in the solution field, one for the phase change line and the other for the superheat line. Two coupled nonlinear differential equations, representing two moving layers, were calculated by the Runge-Kutta numerical integration scheme. The solutions are in terms of six dimensionless parameters: phase change number, two Biot numbers for interfaces, diffusivity ratio, and dimensionless superheat temperature and time. Parametric studies on these parameters have been conducted to provide generic information about this phase change problem. This analytical information is extremely useful for validating numerical solutions. A simplified I-D finite element model was constructed for the purpose of comparison. The excellent agreement between the analytical and finite element solutions has proven that they are mutually validated.This validated finite element modeling tool was then used for modeling an investment casting process of a super-alloy with a simple geometry: a two-step plate. The nonlinear latent heat release, a common property of alloy materials, was approximated by several piecewise linear segments. The transient temperature response of this 2-D finite element solution, including a metal/mold gap resistance, shows excellent agreement with experimental data.This fundamental work provides a solid basis for further work on the development of a process modeling tool for the complex investment casting process.IntroductionAt present, the investment casting process is used in a variety of industries. In the aircraft engine industry, in particular, investment casting is used to produce parts ranging from turbine blades to engine frames. Because a large single casting can replace many component parts that require machining, fabrication, and assembly, this one-piece casting approach becomes a very cost-effective manufacturing process.The main constraint in using this process for mass production is the long design-to-production lead time. The standard rigging design is still an art, based on the experience of casting experts, rather than on scientific methods. Many trials are often required before making a sound final casting. In order to .reduce the number of expensive casting trials, the development of computer-aided tooling technology is needed.The fundamental physics describing this manufacturing process can be simply described. They reduce to a solid/liquid phase change problem, with two parts - first, the thermal balance of the initial superheat temperature of the molten metal and the preheat temperature of the ceramic shell through heat conduction, and second, the energy release from the mold surface to the ambient by radiation."

Jan 1, 1986

By Shengqi Chen

The reduction smelting of nickel laterites produces slag, consisting principally of the chemical components MgO, "FeO", SiO2, and A12O3, and ferro-nickel alloy. Despite the fact that the phase equilibria for the ternary MgO-"FeO"-SiO2 up to 1500°C is well established limited experimental data are available in the MgO-"FeO"-SiO2-Al2O3 system, which is relevant to commercial operation of the process. A methodology has been developed for the experimental investigation of the liquidus temperatures for the multi-component system MgO-"FeO"-SiO2-Al2O3-Cr2O3 in equilibrium with metallic iron. Experiments have been carried out using high temperature equilibration, quenching, followed by electron probe X-ray microanalysis (EPMA). Liquidus temperatures have been determined in the silica primary phase field in the composition ranges directly relevant to the Cerro Matoso S.A. ferro-nickel smelting slag. Liquidus isotherms have been determined for temperatures between 1450 to 1600°C. The study enables the liquidus to be described for a range of MgO/FeO ratios. It was found that liquidus temperatures in the silica primary phase field decrease significantly with the addition of AI2O3. Keywords: Liquidus temperature, ferro-nickel, pyrometallurgy, smelting

Jan 1, 2004

By Donna Guillen, Matthew Lehar, Sebastian Freund, Jennifer Jackson, Helge Klockow

"Research and development is currently underway to design an Organic Rankine Cycle (ORC) system with the evaporator placed directly in the hot exhaust stream produced by a gas turbine (GT). ORCs can be used to generate electricity from heat that would otherwise be wasted, thus producing carbon-free energy. In conventional ORC configurations, an intermediate oil loop is used to separate the hot gas from the flammable working fluid. The goal of this research effort is to improve cycle efficiency and cost by eliminating the pumps, heat exchangers and all other added cost and complexity of the additional heat transfer loop by developing an evaporator that resides in the waste heat stream. Direct evaporation – although simpler and less expensive to implement than indirect evaporation of the working fluid – has historically been avoided due to a number of technical challenges imposed by the limitations of the working fluid. The high temperature of the hot exhaust gas may cause decomposition of the organic working fluid and safety is a major concern due to the high flammability of some of these working fluids. The research team has addressed these challenges and developed a new direct evaporator design that can reduce the ORC system cost by up to 15%, enabling the rapid adoption of ORCs for waste heat recovery. The ORC system is intended to integrate with the GT either as a retrofit or to be marketed as a single package, thus maintaining the manufacturer’s warranty.IntroductionWaste heat from turbines and engines used in industrial applications along with waste heat from industrial processes are exceptionally abundant sources of energy. If even a fraction of this waste heat could be economically converted to useful electricity, it would have a tangible and very positive impact on the economic health, energy consumption, and carbon emissions in the U.S. manufacturing sector. Land-based gas turbines are used in a broad range of applications to produce both shaft and electrical power. Most commonly known for generating electricity either as peaking units or as base load units, they are also used to directly drive pumps, compressors or other machinery requiring shaft power. Simple cycle gas turbines have the advantage of a short startup time relative to coal-fired and nuclear units, however, they incur a significant penalty on their efficiency. Large frame gas turbines usually are combined with bottoming steam-based Rankine cycles to increase the overall efficiency of the system and thereby improve their cost performance. Small-frame gas turbines with exhaust temperatures around 500°C could in principle benefit from steam bottoming cycles, but rarely use them in practice because of the high capital cost of the steam system. Particularly for base load small frame gas turbines, akin to those used in pipeline applications, an increase in efficiency is highly desirable."

Jan 1, 2011

By Pandey H. D.

The paper describes a fluidised bed ion exchange method for simultaneous removal of phenols and cyanide from the effluent. Use of an eluant enables regeneration of the resin in the continuous operation mode. The breakthrough experiments conducted both on the laboratory scale and on a pilot plant scale have shown that while the level of phenol can be brought down from 462 ppm to about 6 ppm, the free cyanide is almost totally removed. An examination of data indicates that the method can serve the twin objectives of pollution control and phenolic compounds recovery.

Jan 1, 1992

By Kota Nakashima

Residues from titanium smelting tend to contain scandium. The scandiumis discarded because no suitable process exists for its recovery from the residue. Valuable-metal recovery from discharged residue is critical for environmental conservation and to achieve a sustainable society. Since 2015, JXNippon Mining&Metals has been developing a process for scandium recovery from the residue of a titaniumsmelting process. The process consists of the following steps: scandium concentrating by classification or neutralization, selective scandium leaching, impurity removal by neutralization, solvent extraction of scandium by using D2EHPA, purification, and roasting. We optimized the above steps to achieve an effective process to obtain scandium oxide (Sc2O3). In this paper, we introduce results from the bench-scale test of the scandium recovery flowsheet developed by JX Nippon Mining & Metals.

By Hong-ying Xia, Bao-bao Wang, Jin-hui Peng, Bing-guo Liu, Li-bo Zhang, Zhi-qiang Li

Based on optimization using response surface methodology designed by Box- Behnken, to study the interaction of wet industrial salt with moisture drying temperature (50-90 ); duration (10-50s); and the weight of the materials (20-60g). The results show that: the experimental parameter conforms to the quadratic equation model to influence the moisture content and the dehydration speed., in analyzing the significance and the interaction of various factors, the optimum by the Design Expert software conditions for drying with microwave radiation include temperature of 90 , duration of 10s, and sample mass of 26g. Verified by experiment, the moisture content after drying is less than 0.25% and the dehydration rate reached 1.37g/min, between the predicted value and the actual value confirmed good fitting degree.

Jan 1, 2015

By S. Goto, S. Yamashita, K. Hata

"The average consumption of zinc dust for purification of zinc leaching solution is more than 25 kg per tonne of electrolytic zinc. Authors proposed to remove impurities in zinc leaching solution by electrolysis instead of cementation by zinc dust. The effects of copper and arsenic on electrodeposition of cobalt in zinc sulfate solution were examined fundamentally using a potentiostat. It is observed that cobalt is easily deposited on a cathode at potentials under -480mV with arsenic. Mesh cathodes of stainless steel and lead anodes were used in a small electrolytic cell and the electrolyte was circulated through 'the electrodes during the electrolysis. The effect of electrolyte circulating rate , pH, cell temperature, current density, and concentration of copper and arsenious ions on removal of cobalt were studied. Removal of Cd and Ni are also examined.IntroductionCobalt is difficult to remove from a zinc leaching solution by a simple cementation reaction using zinc dust. However, it is easily precipitated by zinc dust with co-addition of arsenious or stibinous oxide and copper ion in practical operations(I), (2), (3). The consumption of zinc dust for purification is 16-152 kg per tonne of electrolytic zinc and 65% of this zinc dust consumption is used for cobalt purification. The average retention time for purification of cobalt is 4.5 hours (1). A more economical process for purification is desired instead of zinc dust. The mechanism of this acceleration effect of copper and arsenious oxide on removal of cobalt are explained by the authorsas follows; a galvanic cell is formed between zinc dust and copper which is precipitated firstly, and cobalt is reduced on copper as Co-As alloy by this galvanic current(2). This assumption was confirmed in experiments using a galvanic cell with a membrane( 4). The following galvanic reactions occur between zinc dust and copper precipitate; on copper cathode,2H+ + 2e -= Hz(g)2Coz+ + 2HAs02 + 6H ++ 10e -= 2CoAs + 4HzOand on zinc anode,Zn = Zn = 2+ 2e –This galvanic current becomes almost zero in a zinc sulfate solution which includes only cobalt and no arsenious oxide, and cobalt is weakly deposited on a copper cathode. Cobalt deposition requiers a high degree of cathodic polarization. However, the galvanic current flows almost constantly in an electrolyte, which includes arsenious oxide, and the cathode potential is kept at about -500mV. Cobalt is precipitated as Co-As on the cathode.The authors assumed that cobalt may be removed by electrolysis at a very low current density instead of zinc dust and the following experiments were carried out. In the first part of this paper, the fundamental experiments using a potentiostat on the behaviour of cobalt in zinc sulfate solution are described. In the second part, the results of the electrolysis are reported. Cobalt is removed by a new type of an electrolytic cell, which was desigoed to <Iccelerate the rate of deposition of cobalt. The removal of cadmium and nickel in a solution which includes cobalt and arsenic are also examined."

Jan 1, 1997

By A. Mukhopadhyay

Gas stirring, simultaneous arcing, chemical additions are some basic steps in the secondary steel making. From tap to team however, there are enough uncertainties and several in-situ decision making required to match the fmal composition and temperature in the given amount of processing time. Currently available control algorithms rely on overall material and heat balance coupled with a self-learning regression based tuning of model constants. In this paper we demonstrate the capabilities of Computational Fluid Dynamics (CFD) in modeling and analyzing the thermo-chemical aspects of secondary Steelmaking. These models take advantage of scientific and engineering advances in computational tools and provide almost real time speed of analysis. This can be a very effective tool for operator training, process debugging and improvement as well as new innovations. Keywords: Argon purging, Secondary steelmaking, Arcing, Ladle Furnace, Process Control.

Jan 1, 2003

By Hemraj Dangi, S. Murali, Bhisham Yadav, Mohini Saxena, P. Asokan

"Demonstration studies were carried on the use of fly ash as soil modifier and supplier of micronutrients to improve the agricultural productivity based on the process optimised at lab scale at Advanced Materials & Processes Research Institute, Bhopal. The field trials were conducted in Uttar Pradesh (North India) Orissa (South Eastern India) and Madhya Pradesh (Central India) under different soil and crop conditions. 100-650 tonnes of fly ash per hectare were applied depending upon the soil and fly ash characteristics. Both short and long term studies on impact of fly ash on soil and food quality were conducted. With the fly ash application, the edible yield of tomato, cabbage, potato, wheat, pea, onion, paddy, sunflower, maize etc., were increased from 12 - 46% as compared to the control soil where no fly ash was used. The crop response to various elements mainly heavy metals grown in soil and fly ash applied soil was found comparable to that of control, which are within the permissible limits and meet the food quality standards. The results of impact of fly ash on biotic and abiotic properties of soil, along with the quantity and quality of agricultural produces generated under pilot scale demonstrations in three different parts of India are discussed in this paper. The outcome of this work could act as guiding force for confidence building and to maximise the use of fly ash, generated from thermal power plants worldwide as one of the major mineral waste for agriculture purposes.IntroductionThe advantages of application of fly ash in terms of improvement of soil properties and crop yields have been published by various researchers in India and abroad. Attention is also given about the possible negative and beneficial impact of pond ash in agriculture due to presence of heavy elements, radioactive nuclides and plant nutrients in fly ash. It is evident from the analysis of Indian fly ash that the presence of heavy elements and radionuclides levels are comparable with normal soil. The positive impact that has been reported is with regard to germination, yield and crop growth. The significant impacts are: long term effect of heavy and toxic elements content of fly ash on soil and up take of these elements by plant. Pilot scale demonstration studies have been completed with varying soil crop-combination under different agro-climatic conditions showed considerable improvement in the productivity of cereals, oil seeds and vegetables."

Jan 1, 2008

By I. Gaballah

Jarosite contains up to 15 % of heavy metal compounds &apos;HMC&apos;. The current waste disposal methods will not be allowed in the near future due to new environmental regulations and pollution risks. For these reasons, thermal treatments of raw or decomposed jarosite, in controlled atmospheres, were investigated. The aim of these treatments is to decontaminate the jarosite and/ or to recover the HMC for recycling. According to physico-chemical characteristics of the samples, the thermal treatments in controlled atmospheres N2, CO+N2 and C12+air lead to the extraction rate that vary from 93 to 98 %. Heavy metal compounds were separated by cooling the gaseous phase. The treatments&apos; residue was almost free from HMC. Between 700 "C and 800 "C, the chlorinating treatment was successful of eliminating more than 97 % of HMC contained in four different samples.

Jan 1, 1999

By F. -Z. Ji

Carbon injection into metallurgical slag is important in electric arc furnace (EAF) steelmaking for foamy slag practices and in nonferrous slag cleaning operations. The current publication presents kinetic data for coal injection into EAF slag to understand the interaction between injected carbon and metallurgical slag. Coal particles were injected into EAF slag and the kinetics were followed by gas and slag analysis. The results were analyzed, in terms of fundamental rate equations for each possible reaction step, as a function of temperature and slag composition.

Jan 1, 2003