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By R. Rajiv Srivastava

Brine leaching of a TSL processed zinc-plant residue (ZPR), containing 83.3% anglesite, has been investigated for lead recovery. A prior treatment of ZPR in acid solution did not show any significant effect of acid concentration in zinc dissolution. The study reveals that the solubility limits of PbCl2 is as an important factor with respect to the brine concentration and pulp density in lixiviant. The dissociated sulfate ions hinder the formation of PbCl2 on prolong leaching (above 60 min), while exhibiting the reverse solubility of lead as PbSO4. A 3-step leaching process could yield >92% leaching efficiency when the parameters were maintained as: 10% pulp density in a 250 g/L NaCl solution, 80 °C temperature, and 60 min time. This leaves the insoluble ferrite, sulfides and oxy-sulfates of zinc and lead in the final residue as revealed by the XRD characterization.

By R. C. Chaturvedi, S. B. Padwal

"Padwal and Chaturvedi have developed the model based on M-K theory, considering Hosford's yield criterion and critical thickness strain criterion"" to predict the sheet metal forming limits under simple (constant) strain ratio paths. This analysis has been extended in this paper to predict the sheet metal forming limits under complex strain paths. The effects of exponent ""a"" in Hosford's yield criterion and strain paths on the forming limits under complex strain paths are studied using this analysis. The predictions of the present analysis are compared, both for simple and complex strain paths, with experimental results of Ishigaki for A.K. steel and also with the predictions of Rao and Chaturvedi's model. The quantitative analysis of the error in predicting the forming limits has also been carried out using a method suggested by the authors earlier.1. INTRODUCTIONThe constant strain ratio condition has been assumed in the theories developed for prediction of forming limit diagrams (FLO). In actual forming operation, this condition is seldom satisfied. Even in the case of simple single stage press formed components, the strain path becomes curved and non-linear. In the case of pressings with complex shapes, or multiple stages of forming, the changes in strain path are more pronounced and even abrupt.Experimental study of the forming limits, under two stage strain paths, by Ishigaki [1], has shown that the forming limits are path dependent. It has been observed that the forming limits lower than that under simple strain paths, may be obtained under certain strain paths (when the first stage strain path is either equibiaxial tension or uniaxial tension, followed by the second stage strain path as plane strain). Rasmussen's work [2J, on the theoretical study of forming limits under curvilinear strains paths, has shown that a large drop in formability can result from very small changes in strain path. Thus if a deformation process gives rise to failures due to plastic instability, the failure is not necessarily due to insufficient formability of the material. In such cases, FLOs based on constant strain ratio path should not be used directly in predicting the success or failure of the forming operation. Thus the knowledge of forming limits under complex strain paths is of great importance to the interpretation of press-shop problems."

Jan 1, 1994

By Andrew B. Suttie

The lead-acid battery recycling industry was seriously affected during the 1980s by increasing environmental protection costs and poor lead prices. The process is now being repeated in the 1990s causing further difficulties, for recyclers. In Europe, many lead-acid battery recycling plants use rotary furnaces. The Darley Dale smelter, redeveloped between 1984-87, uses only rotary furnaces. A review of options for this plant has been completed and 'concluded in favour of further investment to exploit more fully the benefits of rotary furnace technology.

Jan 1, 1995

By Sang-Su Lee

This paper shows the application of the porous plug system in the Mitsubishi continuous copper smelting and converting process. This system has already been adopted and utilized in the steel industry to enhance productivity. Recently, some copper smelters have adopted this system but the results have not been satisfactory. The porous plug system was installed at the anode furnace in December 2001 to reduce the oxidation time and decrease the oil consumption. A good effect was that the nitrogen stirring of the melt through porous plugs improved the melt heat transfer. As the result of the enhancing heat transfer the oil consumption and the build-up inside the furnace were actually decreased. But until now the oxidation time has not been sufficiently reduced. In the future, further research and tests are needed in order to increase the productivity and save costs.

Jan 1, 2003

By G. Brooks, J. Naser, M. A. Sattar

CFD models have been developed and numerical simulations have been carried out to predict the formation of foam in oxygen steelmaking. Foam was considered as a separate phase comprising a mixture of gas and liquid. Bubble break up and coalescence models have also been incorporated in a CFD model to predict the number density of individual bubble classes. A population balance equation was used to track the number density of each bubble class. Decarburization with heat generation from chemical reactions was integrated in the process. User subroutines were written in FORTRAN to incorporate the foam formation, the bubble break up and coalescence rate and decarburisation in the main program. The model predicted the foam height, bubble number density, velocity of phases, decarburization, and turbulence. The result from the model has been compared with available data from literature and found to be in reasonable agreement with the experimental and plant data.

Jan 1, 2014

By Carla Lupi, Alessandro Pescetelli

"Spent lead battery recycling still shows few weak points in the achievement of a 100% recycling of different waste matters and by- products arising from the recycling process. Some of said problems are dealing with aqueous streams outgoing the recycling plant, and more particularly, a) the waste waters discarded from the breaking and separation unit, b) purification of the spent electrolyte drained from waste batteries and upgrade to a quality compatible with full re-use by the batteries’ manufacturers, c) purification of the mother liquors discarded in the sodium sulfate crystallization process so to produce a salt of commercial grade. All of the above listed problems have been satisfactorily overcome applying an electrochemical process that, through different process conditions and parameters, is able to remove the harmful impurities that hinder the successful commercialization of such by products, or, at least, that can avoid heavy and expensive treatment plant and operation.IntroductionAlmost 100% of commercial lead and lead alloys produced by secondary lead plants is recycled to the new lead accumulators manufacture. The other by-products and residues produced through the lead recycling process may be classified into two groups:a) matters reusable in the new accumulators production processb) matters produced as a result of various reagents and additives used in the recycling process, to be sold to different market sectorsQuality and saleability of by-products are significant points for the economics of the secondary lead plant operation, because, if said by-products are not saleable, they are just wastes, so offsetting potential revenues, and, at the same time, adding a heavy burden to operating cost, like disposal cost [1]. When looking at a typical, modern lead scrap batteries recovery cycle, it is quite evident that we are still rather far from dealing with a waste-less technology (fig.1).The group a) includes 3 by-products produced through the breaking process: among those matters the polypropylene only usually reaches a standard quality suitable for sale to lead manufacturing sector or to other sectors as well. The other two by-products, electrolyte and separators, do not still reach, through a viable and effective regeneration process, a quality standard sufficient for their re-use in the lead batteries sector ."

Jan 1, 2008

By Henrlk Gripenberg

To solve the environmental and financial problems of the traditional Rotary Salt Furnace process, a new salt-free method for aluminum dross and scrap melting, ALUREC, has been developed by AGA and its partners, Hoogovens Aluminium and MAN GHH. AGA and Hoogovens Aluminium developed the main process concept and jointly carried out trials on pilot plant scale. Owing to excellent results" the partners decided to jointly erect a commercial scale test plant. The order for the design and erection of the furnace went to MAN GHH. The three companies designed the test plant and began operation in the spring of 1994. The results have been excellent and the process is expected to be a technical and commercial success.

Jan 1, 1995

By William Bourcier

Geothermal Brines are a significant potential source of valuable minerals and metals. These brines are water that is heated by the natural heat flow from the depths of the earth. Hotter brines, typically with temperatures greater than 120°C, are used to generate electricity. Lower temperature brines are directly used to supply thermal energy to applications such as agriculture, aquaculture and process/domestic heat. The geothermal waters have had intimate and lengthy contact with the layers of the earth?s crust that they flow through, resulting in dissolution of minerals and metals from the rocks, and solution into the hot water. These aqueous solutions can be processed to recover minerals and metals. Some potential products include silica, zinc and lithium, along with other materials. Recovery of minerals and metals from geothermal brines can be viewed as ?solution mining by nature?, followed by application of known or new hydrometallurgical techniques for isolation and purification. This paper discusses the opportunities, the processes, the challenges, the current status, the economics and the potential for recovery of minerals and metals from geothermal brines.

Jan 1, 2006

By L. Béjar-Gómez

The aim of this research work is to study and characterize precipitates in structural microalloyed steel by transmission electron microscopy and analysis by high resolution (HRTEM). Microalloyed steel with titanium was produced by casting in an electrical induction oven of 25 Kg. capacity. Carbon content in steel was less than 0.1 % and titanium content of 0.04%. Steel was processed thermomechanically; reheated to 1250ºC and hot rolled on a laboratory mill to a 13.0 mm thick plate with a finish rolling temperature of 900ºC and thickness reduction of 80%. Analysis by High Resolution Transmission Electron Microscopy (HRTEM) identified precipitates in the steel; type and morphology. Energy Dispersive Spectroscopy (EDS) analysis was applied to obtain the chemical composition of precipitates and the matrix. STEM-EDS analysis was also applied to obtain the element profile of precipitates. The results showed the presence of carbonitride precipitates of titanium, Ti (CN), with a circular morphology and size of 10 nm and less.

Jan 1, 2006

By Roberto Parada

In a long term program for the optimization of the Outokumpu Flash Smelting Furnace at Chagres Smelter many different subprograms are being developed. One of them is the design and application of a sampling method that can allow the direct diagnostic of the quality of the copper concentrates combustion. We present in this paper the evolution of the sampling devices used in a ten months of continuous sampling campaigns and an example for the sulfur elimination and magnetite formation in the flame from 60 cm to 100 cm under the burner. These type of information combined with the appropriate mathematical modeling of the combustion must propose some considerations to correct the classic criteria in the preparation of the charge for the smelting of copper concentrates based only on the mass and energy balance from the chemical and mineralogy composition of the concentrates.

Jan 1, 2006

By L. Béjar-Gómez

The aim of this research work is to study and characterize the precipitates in structural microalloyed steel by transmission electron microscopy and analysis by low resolution. Microalloyed steel with niobium was produced by casting in an electrical induction oven of 25 Kg capacity. Carbon content in steel was less than 0.1 % and 0.036% of niobium. Steel was processed thermomechanically; reheated to 1250 °C and hot rolled on a laboratory mill to a 13.0 mm thick plate with a finish rolling temperature of 900ºC and a thickness reduction of 80% . This work shows what precipitates are present in steel, the type of precipitates and their morphology. Analysis by transmission electron microscopy of low resolution was applied to obtain the chemical analysis of precipitates and the matrix. Spectroscopy of dispersive energy (STEM - EDS) was applied to obtain the element profile of precipitates. Particles of precipitates of NbC were found; with cubic morphology and size from 70 to 130 nm, circular morphology and size from 10 to 70 nm, polygonal morphology and size from 10 to 80 nm.

Jan 1, 2006

By William C. Spindler

Five industrial installations of large lead-acid battery energy storage systems in operation in the United States, West Germany and the 'Republic of South Africa will be described. One example is for a deep mine shaft in which air ventilation and personnel evacuation require the highest reliability for emergency power. The battery system is designed for additional cost-effective benefits of peak load lopping and reactive power control. Commercially available lead-acid batteries of the following types are in use1 traction, truck, submarine, high power, and gel. Electrode grids of both the calcium and antimony alloy types are used. Applications include deep and shallow cycling as well as float and intermittent use. The advantages of sealed lead-acid batteries in UPS (uninterruptible power source) systems are well established throughout the world, and such system suppliers could readily develop markets for industrial emergency and peak power lead-acid storage battery installations.

Jan 1, 1990

By P. M. Swash

This paper reviews the application of some mineralogical techniques in the evaluation of the Uitkomst Ni-Cu deposit, South Africa. The low grade of the ore necessitates detailed and representative characterisation in order to establish the prospects viability. The relevant mineralogical information is generated by using optical microscopy, magnetic and heavy liquid . separations, XRD. SEM and EMPA. Methods used are briefly reviewed. The cost savings and metallurgical understanding that is provided by the mineralogical work is described especially with regard to milling, flotation and the presence of by-products (PGMs and chromite).

Jan 1, 1991

By Manabu lshimaru

Solid-liquid interfaces as well as defect formation processes during crystallization of melted silicon (Si) have been examined by using molecular-dynamics (MD) simulations. The ordinary Langevin equation employing the Tersoff interatomic potential was used for the calculation of the atomic trajectories. A solid-melt interface has a tendency to form {]] I} microfacets during the crystal growth in the [001] direction, while it is essentially flat during the (Ill) crystallization. Because of the difference of the interfacial structures, the structures of grown-in defects and defect evolution depend strongly on the growth direction. We discuss defect structures and their formation processes within the context of our results as well as previous experimental observations.

Jan 1, 2001

By A. Navarra

Within conventional copper and nickel-copper sulfide smelters, ladles of molten matte are fed into converters. These converters blast oxygen-enriched air into the matte, thereby eliminating iron and sulfur. The converting reactions are exothermic and, indeed, the converter heat balance is often a limiting consideration on the smelter throughput. If a portion of the matte were fed in solidified (granulated) form, this would support higher oxygen enrichment, and lower volumes of converter offgas, allowing higher throughput. This approach is not applied in conventional smelters, partly because of the copious amounts of water that must be evaporated in typical granulators, as in the Kennecott-Outotec process. The current paper recalls a waterless matte granulator that had been pioneered in the 1990’s, and is applicable to conventional smelters. A mathematical formulation is presented that can be used in the context of simulation-based optimization, to estimate the size and impact of waterless matte granulation.

By W. B. Carter, A. T. Hunt, G. W. Book

"Combustion Chemical Vapor Deposition (CCVDSM ), an open air, flame assisted CVD process, is under development. The CCVD process produces non-line-of-sight, epitaxial deposition. Materials deposited include YBa2Cu3Ox' Y2BaCuOx, BaTiO3, Y2FesOI2, ZrO2, yttria stabilized ZrO2 (YSZ), partially (yttria) stabilized ZrO2 (PSZ), and amorphous silica. Two modifications of the CCVD process are being studied. Liquid fuel CCVD deposition, involves the combustion of an organic solvent that contains dissolved reagents carrying the desired coating cations. Gaseous fuel CCVD deposition uses a flammable gas as fuel. A non-flammable solution containing dissolved reagents is either aspirated into the flame or mixed with the fuel gas as an aerosol prior to its combustion. Substrates to be coated are held near the flames' ends.IntroductionThin films and coatings can be deposited using a wide variety of techniques including chemical vapor deposition (CVD). CVD is ""a materials synthesis process whereby constituents of the vapor phase react chemically near or on a substrate surface to form a solid product.""lIn conventional CVD processing, gases carrying coating constituents flow into a reaction vessel where deposition occurs onto a heated substrate. The deposition process is often conducted at reduced pressure. Both cold and hot wall reaction chambers are used. Heat can be provided by a resistance furnace, rf induction, or high-intensity radiation lamps. Plasma, microwave, photo, laser, RF, and electron-enhanced CVD processes have been developed. The necessity of using a reaction vessel limits the substrate size and affects coating economics. Although most CVD depositions are performed as batch processes, continuous deposition can be accomplished with the use of appropriate hardware.The chemical vapor deposition of thin, dense oxide films has been accomplished in the open atmosphere with a flame assisted process. The process is called combustion chemical vapor deposition (CCVDSM).2 Two modifications of the CCVD process have been developed. The liquid fuel CCVD process involves the combustion of an organic solvent in which reagents (containing the coating cations) are dissolved. The gaseous fuel CCVD process uses a flammable gas as fuel. In this modification, a non-flammable solution containing dissolved reagents is either aspirated into the flame or mixed with the fuel gas as an aerosol of small droplets prior to its combustion. Substrates to be coated are held near the flames' ends."

Jan 1, 1994

By S. Katz, V. Stanek, K. L. Moore, E. D. Larsen, D. E. Clark, P. E. King

"Cupola melting is a complex physical and chemical process having a number of nonlinearities which make conventional process control difficult. In addition, sensors for both inputs and outputs of interest to the foundry operator are often difficult or impractical to apply in a production situation. The present work is an effort to control the process using both intelligent and conventional control techniques as appropriate. Neural networks are used as an inverse process model in a cascade, feedforward controller in conjunction with a finite difference model of the cupola. A separate implementation of the neural net serves as a stand-alone visualization tool; it can operate on a laptop computer and is a useful tool for the cupola operator. IntroductionThe goal of the present work is to develop a controller to improve the efficiency of cupola melting. Although cupola melting as a process has a long history, automatic control has been elusive because the process has been poorly understood. The purpose of this four-year program, which has been underway for about six months, is to develop a controller for the cupola process using intelligent and conventional control methods.The Cupola ProcessThe cupola furnace [1,2] is one of the oldest processes for making cast iron, and is still the dominant method. It takes the form of a water-cooled vertical cylinder, as large as 4 m in diameter and 20 m tall. The charge consists of scrap metal, alloying ingredients, limestone, and coke, which serves as fuel; it is composed by weight and fed through doors near the top of the cupola. Air, usually heated and often enriched with oxygen, is blown in near the bottom through tuyeres extending a short distance into the interior of the cupola. As the coke is consumed, the charge drops and melts. A continuous flow of iron emerges from the bottom of the furnace, at rates as high as 100 tons per hour, and. is transferred to casting lines in the foundry. The exhaust gases are drawn from the top of the cupola, where they are processed to meet pollution standards."

Jan 1, 1994

By C. L. Lin

Multiphase, irregularly-shaped randomly-oriented PARGEN particles were grown to determine the breakage/liberation characteristics of such locked particles. The simulated locked particles were randomly broken to establish the liberation characteristics of the broken fragments. The progeny size distributions are consistent with Gilvarry's volume and surface flaw model for single particle breakage. The extent of liberation of both continuous and dispersed phases can be described from the conservation of interfacial area. In this regard the data can be normalized and liberation described for a wide range of dispersed phase grades and dispersion densities.

Jan 1, 1988

By P. D. Nolan

Smelters operating under pollution control orders have become increasingly dependent upon the reliable operation of sulphuric acid plants and no factor affects the long term reliability of those plants more than efficient gas cleaning. The sources and characteristics of contaminants in smelter of fgases and the conventional approaches to removing these contaminants to accepted levels are discussed. New technology is described which offers advantages of lower capital cost, lower operating cost and reduced space requirements over the conventional approaches. This new technology has been developed by LAB s.a. and is licensed for metallurgical gas applications by Chemetics International Company.

Jan 1, 1983

By Sumantra Mandal

The hot deformed microstructure of the 15Cr-15Ni-2.2Mo-Ti modified austenitic stainless steel (commonly known as alloy D9) was investigated employing electron backscatter diffraction (EBSD). Hot compression tests were conducted in a Gleeble thermo-mechanical simulator at temperatures of 1173K-1373K (in steps of 100K) with a strain rate of 10 and 100 s-1 to different strains. Various kinds of deformation patterns were observed inside the deformed grains. These were inferred as the development of geometrically necessary boundaries or formation of parallel set of micro-bands. Recrystallized grains were partitioned from the deformed grains employing grain orientation spread approach. Extent of dynamic recrystallization (DRX) was found to be minimal at 1173K. DRX was predominantly found to happen at and above 1273K which increases with increase in strain. DRX nucleation and development mechanisms were discussed with respect to bulging of the parent grains and sub-grain rotation. Special emphasize is given on the role of annealing twins on DRX nucleation and subsequent expansion.

Jan 1, 2009