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By Alexandra Anderson

A computational fluid dynamic (CFD) model has been developed using ANSYS Fluent 17.0 to help identify areas of high wear within the refractory lining of a secondary lead reverberatory furnace. Once a base case simulation was validated using data from an operational furnace, areas of potentially high refractory wear were determined through the calculation of the temperature and velocity distributions within the furnace and on the hot face of the refractory lining. The CFD model was used to assess whether the predicted areas of high refractory wear could be minimized through changes burden geometry. The results showed that shape of the burden geometry greatly affected the overall flow patterns and heat transfer within the furnace.

By Rajesh S. Ransing

An intelligent tool has been developed to analyse the quality of diecast components. The influence of both design and process parameters has been studied in great detail. The tool, based on expert systems related technologies, can identify the causes for the defective castings manufactured. Design related causes such as gate position; gate area, runner design etc. as well as process related causes such as cycle time, cavity filling time and melt temperature are suggested by analysing the data on defective castings for a manufacturing campaign. This intelligent analysis is useful for both design as well as production engineers in the decision making process. All the causes for the occurrence of defects are classified into two categories. The firs category is the 'rootcauses' i.e. the causes which are related to the actual process, material and design parameters and which can be directly monitored. The second category is more abstract in nature and is classified as `metacauses'. These capture the scientific rationale implicit in the cause and defect relationships. This knowledge on causes and defects is represented in the form of a structured graph rather than by a set of rules, which, coupled with forward reasoning and heuristic search techniques results in an elegant and efficient approach. Uncertainties and the degree of relationship among causes and defects are represented by a fuzzy probabilistic model.

Jan 1, 1994

By C. G. Anderson

Throughout the world, there are many orebodies or materials which have significant value but also contain arsenic. As regulations on the transport, exposure, disposition and emission of arsenic have become more stringent; it has become increasingly more difficult to derive the values from these resources. This paper will outline the fundamentals of alkaline sulfide hydrometallurgy and its successful application to arsenic bearing ores, concentrates and materials.

Jan 1, 2005

Most of the world's zinc metal is produced via the roast- leach-electrowinning (RLE) process. The process is well established, but most of the sulphur in the sphalerite concentrates reports in the acid, which has to be stored and/or sold. There are significant incentives to develop a simpler process with much reduced acid generation. Ferric ion is a well known oxidant for most sulphides, in particular sphalerite, and it converts the sulphide to elemental sulphur. Based on stoichiometry, however, the amount of ferric ion needed to achieve acceptable zinc extractions is prohibitive for downstream zinc recovery from the leach solutions. The process suggested here makes use of less-than-stoichiometric ferric sulphate additions because the ferric ion is regenerated by sparging SO2/O2 mixtures. This regeneration can be effected in-situ in the leach vessel or outside the leach vessel. An example of the application of this new process is presented for a Canadian sphalerite concentrate assaying 60% Zn. The effects of temperature, ferric concentration and ferric ion regeneration are presented. Options to recover zinc from the leach solution are also briefly discussed.

Jan 1, 2000

By G. Upadhya

Considerable success has been achieved recently in modeling microstructural evolution during solidification of castings bthrough the coupling of macroscopic heat transfer with microscopic solidification kinetics models. However, a complete model for simulation of solidification in complex shaped castings involves: (i) the description of fluid flow, during and after mold filling, coupled with (ii) heat transfer to the mold and surroundings by use of a macro model, followed by (iii) a description of subsequent solidification of liquid metal by use of a micro model for solidification of the alloy under consideration. This paper describes the coupling of solidification kinetics model to a 3D, transient, fully coupled fluid flow and heat transfer model. Coupling between the macremicro models is achieved by using the latent heat method. Micro models for the eutectics of gray, white and ductile iron are discussed. This coupled code has been used for predicting the thermal history and microstructural data for shaped castings. Various applications of the model, including prediction of shrinkage defects, grain density contours, and graylwhite transition region in the casting, are presented for a relatively complex casting geometry.

Jan 1, 1992

By Jafar Safarian

Bauxite is the main raw material used for the production of alumina (Al2O3) through the well-known commercial Bayer process. This process has significant challenges such as limitation in using low-grade bauxites as they contain significant amounts of impurities such as Fe, Si, Ti. The Bayer process residue, which is known as red mud, is also a global environmental challenge due to huge amount of this low value residue production. An alternative sustainable process with high potential to solve these problems and produce valuable and consumable by-products is a pyrometallurgical-hydrometallurgical process in which the low-grade bauxite ore is treated through a smelting-reduction process, yielding iron alloys and a calcium-aluminate slag. Alumina is then produced from the slag by hydrometallurgical treatment. In the present work, the reduction of pellets produced from different bauxite ores by hydrogen is studied and it is shown that complete iron oxides reduction is possible. Further smelting and smelting-aluminothermic reduction of the reduced pellets show that iron and silicon ferroalloys can be produced, in addition to a proper slag for alumina extraction.

By M. R. Barkhudarov

Semi-solid metal can be formed into useful products of near net shape and high quality. Use of this method has been limited, however, because of the difficulty of working with metal in the semi-solid state, which has strong shear rate, temperature and time-dependent properties. In this paper we describe a thixotropic model and apply it to the problem of small metal droplets impacting on a flat plate.

Jan 1, 1997

By Jeong-Hwan Kim

The liquid-liquid reactive process (solution process) is often adopted as a synthetic method for precipitated calcium carbonate (PCC) in laboratory studies for its simplicity in operation or ease in controlling process variables. Still, PCC are produced commercially by passing carbon dioxide through a milk of lime, i.e., by a gas-liquid reacting method (carbonation process). Few studies on the carbonation process have been conducted, since the process variables are interrelated and difficult to control compared to the solution process. In this study, both carbonation and solution processes were employed to study the polymorphs of calcium carbonate and growth rate of PCC crystals. The effects of the characteristics of limestone ores as a raw material in the synthetic system of PCC on the synthetic characteristics of PCC were also investigated. To control the nucleation rate in the synthetic systems, the shape factor was considered most important. Single-phase aragonite PCC could be synthesized under a variety of controlled experimental conditions such as ionic strength, solution composition, concentrations of additive ions, and temperature.

Jan 1, 2006

By C. Gasparrini

Mineralogy may be applied to the selection of appropriate separation techniques, as well as to assist in the evaluation of problems causing loss of metals and other economically important elements during plant processing. Mineralogic studies may thus help develop techniques to optimize metal recoveries. The present paper describes how such factors as the minerals in which the elements of interest are concentrated, their chemistry, the chemistry of the associated minerals, grain size and textural associations with other minerals in the ore, may affect decisions on separation techniques for the recovery of economic elements. A number of case studies are described in which the mineralogical observation of ore samples has revealed the cause of problems experienced in the extraction of select precious and base metals, or has been decisive in the choice of appropriate techniques for recovery.

Jan 1, 1981

By Jae-Chun Lee, Jinki Jeong, Manis Kumar Jha, Divika Gupta, Pankaj Kumar Choubey

Rare metal indium (In) is mostly used as electroluminescent material in liquid crystal displays (LCD) monitors. Present paper describes leaching studies for the recovery of In from waste LCD monitors in presence of different other impurities. The leaching studies showed that more than 85% of In was leached out using 20% sulfuric acid at 60oC in mixing time 30 min at fixed pulp density 25 g/L. The solution could be purified using SX/IX and from the pure solution metal/ salt could be produced by evaporation, precipitation, electrolysis, crystallization processes.

Jan 1, 2014

By Toshio Kurikami, Koichi Yamazaki

"Toho Zinc Co., Ltd Chigirishima Refinery has the production capacity of electrolytic lead for 95000t/y by sintering- blast furnace electrolytic process. Lead raw materials are lead concentrates, spent batteries and dusts that contain lead from other companies, and these are handled by existing smelting process. There are many circulation materials in the process, because the system has been constructed with improving the recovery rate and protecting the environment. This report describes material balance in each process, distribution of the lead and various components, and it examines present state of the processing. In addition, we report the result that we have tried to improve the work environment.IntroductionThe Chigirishima Refinery of the Toho Zinc Co., Ltd. is located in Chigirishima, an island 4km off the coast of Takehara-city, Hiroshima, Japan. The Chigirishima Refinery began lead smelting operations in 1951.The Chigirishima Refinery adopted the sintering-blast furnace-electrolytic process and has an electrolytic lead production capacity of 95,000 tons/year. The existing smelting process handles raw materials from lead concentrates, spent batteries, and lead-bearing dust from other companies. This system was constructed with the intentions of improving material recovery ratios and protecting the environment; therefore, there are many materials recirculating throughout the smelting process. This report describes the material balance in each process and the distribution ciflead and various components, and it examines the present state of processing. In addition, we report the results of our attempts to improve the work environment."

Jan 1, 2000

By David Bequette, Ray D. Peterson, Cynthia K. Belt

"With a need to cut production costs in the metals industry, cost savings from energy efficiency improvements are critical. Opportunities can be found by reviewing furnace systems and practices so that the melting and holding processes operate at the highest energy efficiency. Many of the changes can be implemented with a minimum of expense or capital investment. This paper will review several low cost methods to optimize energy efficiency on reverberatory melting or holding furnaces. These five methods (furnace utilization, idle procedures, fire rate, controls, furnace pressure) will be explained and information given to implement these changes. Included are several rules-of-thumb and benchmarks for aluminum reverb furnaces.IntroductionEnergy can be a significant portion of the total manufacturing costs for metals and materials manufacturing involving thermal processing such as heat treating, melting, and high temperature processing. Natural gas prices have dramatically varied over the last few years. While no one can foresee the future, prices are expected to increase from the current low prices. More recently, emphasis is being put on the reduction of greenhouse gases with the potential of additional costs to industry.One of the first steps in an energy management program is to measure the energy usage of the process [1]. The results are typically understood in relation to the mass melted in kWh / mT [BTU / lb]. For the purposes of this paper, furnace energy efficiency is calculated over a month or even a year and thus includes hold times. This efficiency is typically different from the values quoted by furnace manufacturers. Those values are for limited short term tests at highutilization.Once you know the performance for your furnaces, these should be compared to industry benchmarks. For aluminum melt furnaces with cold air burner systems, a benchmark value or goal is 1800-2000 BTU/lb [1160-1290 kWh/mt], though some of the best have reached 1600 BTU/lb [1030 kWh/mt]. Furnaces with regenerative burners can attain 1100-1200 BTU/lb [710- 775 kWh/mt]. There are some designs of multi-chamber furnaces or oxygen furnaces that have improved on these numbers, perhaps as low as 950 BTU/lb [615 kWh/mt]. Typically, as the degree of sophistication and energy efficiency of the furnace increases, so does the cost."

Jan 1, 2010

By Toshihide Ito, Jie Liu, Takashi Nishiyama

"Human society evolved from an agricultural to industrial and, subsequently, to a service society. As the resource requirements for each stage of this development differ, trends of metal and energy consumption are related to shifts in society. The increase pattern of supplemental energy is similar to that of mineral production throughout the world. Low positive and stable long-term increasing occurred before 1950, whereas they increased quickly after 1950, especially between 1950 and 1973. A substantial decline in· the growth of energy and mineral production began in 1973 and lasted until the early 1980s. Production of energy resources has recently begun to increase again at a high growth rate in the world. Observing the consumption trends of energy and key metals, it is clarified that increasing patterns can be thought in three stages.IntroductionHuman society evolved from an agricultural to industrial and, subsequently, to a service society. As the resource requirements for each stage of this development differ, trends of metal and energy consumption are related to shifts in society [1-3]. Humphreys [4] described that both the non-ferrous metal consumption and the construction material consumption showed a similar trend dropping markedly in the UK over the period 1960-1992. On the other hand, per GDP (Gross Domestic Product) consumption, that is, the intensity of use of construction materials has declined sharply over the past 30 years, more so than the intensity of metal use in the USA [5]. Nishiyama [6] observed that increase pattern of supplemental energy is similar to that of mineral production throughout the world."

Jan 1, 2000

By Preben Ingerslev

Control of the reheating of ingots is based either on surface temperature measurements using optical pyrometers or on furnace set points and reheat time determined empirically. This paper presents a real-time mathematical heat flow model, named BESTT, which calculates the temperature distribution in an ingot cross section when reheated or cooled. The model runs on a 486 PC in less than one minute for a variety of ingot cross sectional shapes such as circular, square and with some considerations octagonal and heavy-cornered square. Initial temperatures can either be uniform or nonuniform while accounting for temperature dependent thermophysical properties. The model was developed and verified using 718 alloy ingots in box type furnaces. When integrated with on-line pyrometric measurements, BESTT can provide for improved feed back in the reheating control loop. The use of BESlT will assist in reducing energy costs, and improving product quality and consistency. EPD Congress 1994 Edited by C. Warren The Minerals, Metals k Materials Sodety, 1993

Jan 1, 1994

By Marco Olper

The CX-EW technology, developed by B.U.S Engitec, is improved introducing besides the battery paste electrowinning, the direct electrorefining of metallic lead (grids and poles) obtained from CX breakers. This new concept of electrorefming the antimonial lead scrap is aimed to the production of 99.99 lead and of slimes with high antimony content, avoiding gaseous emissions in melting lead scrap, and expensive and pollutant thermic refining operations. In this way, practically all lead content in the battery is available as 99.99 lead, hence with a wider market for the lead recyclers. This paper will describe the tests performed on a pilot plant scale with special reference to the relatively low energy consumption of the process.

Jan 1, 1993

"Hematite pellets were electro-deoxidized to iron in molten sodium hydroxide to produce iron containing about 10-wt % oxygen. The anodic reaction was the evolution of oxygen on an inert nickel anode. Before the electrochemical reaction, there is a reaction between sodium hydroxide and ferric oxide to form sodium ferrite and, in order to compensate for the reduction in sodium oxide content, 1 wt % sodium oxide is added to the melt. In a laboratory cell, the cell voltage was 1.7 V with a current density of 5000 A m-2, a current efficiency of 90% and an energy consumption of 2.8 kWh kg-1.Introduction The iron and steel industry contributes about 2.3 bn tonnes/annum of the carbon dioxide to the atmosphere, which is about 10% of the total, and some believe that, in order to prevent a catastrophic rise in the earth’s temperature, carbon dioxide emissions must be reduced by 50% come 2050. However, by 2050, it is likely that the iron and steel industry would have grown significantly so that the production may have risen to 2 or 3 bn tonnes/year so in order to meet the 50 % reduction on today’s figure, the carbon dioxide may have to be reduced to 25% or less, which is a very demanding requirement. There are probably three ways of reducing the carbon dioxide output:1. By capture and sequestration, but this may be technically very demanding.2. Reduction using hydrogen in place of carbon."

Jan 1, 2009

By Vinay Kumar, Jae-Chun Lee, Rakesh Kumar, Manis Kumar Jha, Archana Kumari, Pankaj Choubey

Present work is a part of developing novel recycling technique for waste printed circuit boards (PCBs) i.e. the liberation of metals from PCBs by organic swelling followed by the treatment of resin to remove/ recover hazardous soldering materials. In order to recover the hazardous metallic constituent lead from the liberated resin, initially the leaching studies were made using fresh solder containing 63.9% Pb and remaining tin. Experimental results obtained in different conditions viz. time, temperature and acidity showed -97.20% of lead dissolution with 6M HNO3 at solid to liquid (S:L) ratio 1:10 (g/mL) and temperature 90°C in 75 minutes. The result of the studies validated with crushed PCBs shows that almost total lead and tin was leached out with 6M HNO3 and 6M HC1 respectively at S:L ratio 1:10 (g/mL) and temperature 90°C within 50 minutes. The results will be useful for the treatment and safe disposal of PCBs resin.

Jan 1, 2011

By Joachim Lemke

The stainless steel sheets of permanent cathodes at Norddeutsche Affinerie (NA) were damaged by corrosion after nearly 11 years in operation. The necessary raising of the strength for stripping the copper had increased the deformation of the stainless steel blades. Current efficiency declined. After investigating the possibilities, like buying new cathodes or treating the steel surface, i.e. by sliding, a repair process was developed whereby the stainless steel sheet was exchanged. Special laser technology for cutting used blades und welding new stainless steel sheets underneath the used hanger bar was applied because the energy input into steel is the lowest of all welding methods. The new stainless steel sheet was welded with the rolling line in a horizontal direction. The achieved flatness of the repaired cathode blades amounted to less than 4mm per meter. During 11 months NA repaired nearly 36,000 permanent cathodes and put them back into operation. Repair costs were much lower than the costs of buying new ones and current efficiency increased again to more than 96% with a current density of 340 A/m².

Jan 1, 2006

By Muhlis Nezihi Saridede, Burak Birol

"The scraps of high quality steels generally contain expensive alloying elements such as chromium, vanadium, nickel, etc. These scraps are melted in an induction or an electric arc furnace and refined in ESR (Electroslag Remelting) purification process. A significant amount of alloying elements are lost during these processes. In order to avoid these losses, scraps can be utilized directly in ESR by skipping the melting step. In this study, 316L stainless steel scraps were refined in ESR with selected synthetic slags. The products were analyzed by optic emission spectrometry and the effects of slag compositions on the alloying element losses were examined. According to the analysis of the scrap and the products, generally chromium, nickel and manganese losses were encountered. It was determined that the alloying element losses has no connection with electrical conductivity. The slag containing CaF2, Al2O3, and FeO gives the optimum Cr and Ni losses.IntroductionElectroslag remelting (ESR), which is the consumable electrode refining process, finds a wide range of utilization for the production of high quality, low inclusion alloys. This process is based on melting a consumable electrode under a molten synthetic slag containing CaF2, Al2O3, CaO etc. The synthetic slag provides the chemical refining and insulation of molten metal from air which leads to a higher purity and an inclusion-free product. [ 1,2] A schematic diagram of ESR system is shown in Figure 1."

Jan 1, 2011

By Stefan Mutz

In Germany the automobile recycling is regulated by law. Current legislation requires that by the year 2015, eighty five w.-t. % of the components from used cars ill be materially recycled. Whilst for 10 w.-t. % of the materials a thermal utilization is certified, there are still some concrete questions that remain unanswered regarding the usability of single fractions. The recent innovative approaches to the concepts of used cars dismantling do not alter the fact that the majority of the materials of used cars still have to pass over the shredder and the connected processing aggregates. The status of the so called SLF (Shredder light fraction) which is about 25 w.-t. % w.-t. in used cars, has not been satisfactorily clarified. Furthermore questions still remain regarding the separation of the NMSF (nonmagnetic metal shredder fraction) which has to be separated in the single metallic fractions like stainless tell, copper, brass, zinc, etc. Attempts of optimization can be found. This paper analyses some of the difficulties being encountered by the automobile recycling industry in Germany, before reviewing some of the innovative approaches that the industry has introduced. Finally the paper goes on to describe the potential of automatic picking. Examples of a series of tests, utilizing this technology, in which a variety of products from a range of shredders were isolated are described in detail. This new technology provides a range of applications to the automobile recycling industry.

Jan 1, 2002