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By N. D. Schupp

The Doe Run Company's Herculaneum, Missouri lead smelter has existed in continuous operation since 1892. Throughout the history of the plant extensive developments have been made to improve throughput, increase productivity, decrease operational costs and improve technology, while remaining an environmentally responsible producer of high quality primary lead in the international market. This paper provides an overview of the Herculaneum smelter, focusing on the most recent configuration of the operations. The paper includes discussion on all the aspects of primary lead production at the Herculaneum smelter.

Jan 1, 2000

By David S. Holmes

An overview of existing biological technologies for the recovery of copper and uranium is presented. Engineering and biological challenges and opportunities in these areas. are discussed. New opportunities for the biooxidation of refractory gold ore are described. Techniques for the development of new strains of microorganisms. for commercial metal recovery applications are discussed with special reference to the genetic manipulation for bacterial strain improvement.

Jan 1, 1991

By James P. Bennett

EAF slag chemistry and its control have been recognized as important in producing quality steel at a low price for a number of decades. EAF steel producers make lime and dolomite additions to furnaces, controlling the CIS ratios and sulfur pickup from the steel. Existing phase diagram data at 1600°C for CaO, MgO, FeO, SiO2, and Al2O3 was used to write a computer model optimizing slag chemistry for slag foaming and reduced refractory wear. The model, its development, and its use in an industrial steelmaking environment will be discussed along with how the model can improve energy efficiency. The importance of EAF mass balance to account for critical materials like Si in scrap and refractory wear using the model will also be emphasized.

Jan 1, 2003

By Chen-Ming Kuo, Esher Hsu

"Under the 4-in-1 recycling system, Taiwan producers and importers who using packaging containers have responsibility to pay the recycling fees for recycling the waste packaging containers they produced or imported; while the collectors/recycling plants who collect/sort/recover waste packaging containers receive subsidy for conducting recycling. A reasonable pricing for recycling charge and subsidy is a way for sustainability of the recycling. The objective of this study is to provide an amending mechanism for product charge and recycling subsidy in response to the social economic changes. This study employs a regression analysis and cost adjusting model to link the factors used for calculating product charge and recycling subsidy on recycling waste packaging containers with socio-economic indicators, raw material prices, wholesale prices, and secondary material prices. Study results provide estimated models to EPA in Taiwan for amending product charge and recycling subsidy in response to the social economic changes.IntroductionUnder ""4-in-1"" recycling system in Taiwan, waste packaging containers are officially announced to be recycled. The waste packaging containers announced to be recycled include iron cans, aluminum cans, glass bottles, plastic containers, paper containers, aluminum foiled paper packs. In order to compensate the recycling system, EPA charges associated manufacturers and importers for recycling fee and subsidies recyclers to create the economic incentive for raising recycling performance. Basically, the budget for subsidy recyclers is from the recycling charge. That means if we want to increase recycling efficiency by increasing subsidy to recyclers then the manufacturers and importers have to pay more for reaching financial balance of recycling foundation. The benefit of recyclers and fee payers are always conflicted. The recycling charge and subsidy is thus argued by fee payers and subsidy receivers all the time. A reasonable pricing for recycling charge and subsidy is the only way to keep the recycling system sustainable. Moreover, a suitable mechanism has to be changed along with the changing social economic condition. The recycling performances and effectiveness of this recycling system is also highly dependent on the pricing mechanism. This study intends to provide an amending mechanism for product charge and recycling subsidy in response to the social economic change. Related previous studies about recycling system in Taiwan with its performance include Hsu and Kuo (2002, 2005), Bor, Chien, and Hsu (2004) and Hsu (1999). Hsu and Kuo [1] estimated total production values of recycling and evaluated the performance of recycling performance based upon the estimated production values."

Jan 1, 2011

By M. T. Thomas

Sufficient development of the X-Ray Photoelectron Spectroscopy (XPS), the Auger Electron Spectroscopy (AES), and the Secondary Ion Mass pectroscopy (SIMS) has made these instruments ideal for solving problems related to mineral processing -particularly gold ore processing. XPS can determine both the surface composition and chemistry of ores and tailings, and the various phases within either of them. AES can also determine surface composition with the further advantage of having greater spatial resolution so the surface chemistry associated with specific minerals in the ore can be identified. This identification helps to clarify why some minerals pass through a chemical process unaffected, while others can be successfully treated. SIMS has an elemental sensitivity from one to four orders of magnitude greater than XPS or AES which makes it useful for detecting the presence of some elements in very low concentration (parts per million).

Jan 1, 1981

By N. J. Tannyan

Laboratory bath smelting tests were conducted to determine the feasibility of smelting nickel- copper concentrate directly to a low iron matte in one step. Concentrate, air/oxygen and a silica flux were fed to a matte-slag bath kept in MgO crucibles at I 300°C. Various oxygen enrichments and smelting rates were used to maintain 0.5 to 2 wt% iron in the product matte. The slag losses are comparable to those obtained under similar industrial conditions. Due to the highly oxidizing conditions required to produce mattes with low iron contents, it is not recommended to target iron contents below about 2% in the matte. The specific bath smelting rates were equal to or higher than those in various industrial bath smelting processes.

Jan 1, 2003

By S. Seetharaman

A mathematical model has been developed to evaluate the viscosities of melts at high temperatures. The viscous flow in liquid is described by the equation, {n = Aexp(AG*/RT)} based on the absolute reaction rate theory. The Gibbs energy of activation,{ AG* } is considered to be a function of the temperature as well as the composition of the melt. The model has been applied successfully to various metallic and slag systems from unary to quaternary. On the basis of this model, a relationship has been suggested to relate the Gibbs activation energy of viscosity to the Gibbs energy of mixing in binary metallic melts. The viscosities predicted from available thermodynamic data in the case of a number of binary metallic systems using this correlation show satisfactory agreement with the reported experimental values.

Jan 1, 1994

By P. M. Prasad

The last two decades have witnessed the emergence of numerous hydrometallurgical and direct processing techniques for the extraction of some metals from pocketed/lean/complex sulfide ore deposits. A new approach with some inherent technological merits, investigated in recent years, is the lime-enhanced reduction of metal sulfides. Thermodynamic aspects relevant to the lime-enhanced reduction of metal sulfides by H2,C0 and C are discussed. A survey of the researches on the basic features of and factors influencing the lime-scavenged reduction of selected sulfides and sulfide concentrates reveals that lime tremendously enhances the sulfide reduction rates (up to 100 times) and drastically reduces the sulfur emission into off-gas to negligible levels. Further successful practice of lime-enhanced reduction requires only a moderate temperature of reduction (characteristic of each sul¬fide) and, in the case of gaseous reduction, relatively low gas flow rates. Relevant kinetic aspects of the concerned reactions that have a bearing on process development and its understanding are also briefly discussed. A conceptual scheme of general applicability for the processing of sulfide concentrates by the lime-enhanced reduction technique consists of three main steps: (0 lime-enhanced reduction by a suitable reagent (e,g., H,2, CO, gasified coal, water gas), (ii) separation of the product metal from the dry slag (CaS + unused CO) by mechanical separation, magnetic/gravity concentration or flotation and (iii) melting and refining by standard procedures. This novel approach, which is patently less complex, is expected to employ basically simpler flow sheets at comparatively lower operational temperatures and aid in pollution abatement. Potential for developing such a route for the small scale extraction of metals like copper, molybdenum and antimony is indicated. Possibility of utilizing this technique for the production of fibers/ filaments of some metals is also outlined.

Jan 1, 1983

By F. F. Aplan, G. Simkovich

"A review is given of the effects of solid state point imperfections upon a number of mineral benefication processes and a metal extraction process. It has been found in numerous flotation studies that small amounts of aliovalent impurities (dopants) in binary compounds may show major effects upon flotation behavior. Both semiconducting and ionic conducting compounds are affected. These effects are also seen in hydrometallurgical studies as well as in electrostatic operations. Additionally, de-copperization of lead melts appears to be strongly influenced by similar defects. It is hypothesized that the effects observed in these studies are present in actual operations and should be considered in designing processes. A few speculations concerning future efforts are advanced. IntroductionImperfections [point (e.g., vacancies, interstials, quasi-free electrons, electron holes, impurity ions), line (e.g., dislocations), two dimensional (e.g., grain boundaries) and three dimensional (e.g., 2nd phases) defects] are generally present in solid materials and these imperfections may, and often do, have important effects upon a variety of properties and processes. In general, one may, in most cases, attain elimination of three dimensional defects by a separation process of one type or another (e.g., gravity, electrostatic, magnetic, flotation, hydrometallurgical etc.,). Thus, this type of defect has rarely been investigated in a systematic fashion. Two dimensional defects are always present in non-single crystal materials but have also escaped systematic studies in processes primarily because the control of such defects is not easily attained. Line defects are non-equilibrium entities which are present in ill-defined quantities so that they present a variable that cannot be easily controlled although through careful systematic experiments one can attain some reproducible relations pertaining to this type of defect.Contrary to the lack of studies concerned with the effects of 1, 2 and 3 dimensional types of defects there has been some activity concerned with point defects and their effects upon a number of mineral/metallurgical processes, especially flotation processes. Thus, this article will present a review primarily of point defects in relation to their effects upon flotation although other processes and defects will also be mentioned."

Jan 1, 1988

By David G. Dixon

Although the kinetics of leaching processes are of paramount importance in the design and analysis of nearly all hydrometallurgical flowsheets, these concepts remain poorly understood and, as a result, are only rarely applied to mass and heat balance models. In this second of two papers, we demonstrate how simple yet powerful models of leaching kinetics and other rate processes may be added to mass and heat balance models, and apply these concepts using a spreadsheet model of a simplified pyrite autoclaving flowsheet. In particular, we focus on the interpretation and scale-up of batch leaching data, and on simple means for modeling other phenomena commonly associated with leaching, such as reagent depletion, gas-liquid mixing, and the precipitation of oxides and basic salts.

Jan 1, 2002

By J. J. Kim

In a study of buildup in a green-feed reverberatory furnace, it was determined that approximately half of the crucible area has a moderate buildup of 25 in. or less, and that the area extending 45 f t from the burner end of the furnace has only a slight buildup. The false bottom, averaging 6 in. in thickness, was found to cover the entire crucible area. The stratification of Cr2O3, A12O3, and SiO2 occurs throughout the slag layer; this phenomenon is the principal reason for the formation of the false bottom in the green-feed reverberatory furnace. The false bottom is caused primarily by the settling of FeO*(A1,Cr),03 aggregates, which are derived mainly from returned converter slag. The false bottom can be transformed to a solid permanent buildup in the furnace, particularly when the matte is completely withdrawn. From the material balance of Al2O3 and Cr2O3 around the furnace, It is estimated that the average rate of aluminum chromite accumulation is approximately 0.3 ton per day or less.

Jan 1, 1976

By Du Sichen, S. Seetharaman, A. Jakobsson

"In the Present paper, the principles of oxygen potential measurements have been discussed along with the design details for oxygen sensors that are used in copper industry. A description of some of commercial probes is presented along with their salient features. The application of these sensors in flash smelting, converter and casting sections of copper production are discussed along with their implications on process optimization.I. IntroductionThe high temperature galvanic cells have come into prominence on account of their numerous applications in both fundamental as well as applied measurements. Since the inception of the oxygen-ion conducting electrolytes like ZrOrCaO·by Kiukkola and Wagner [1], the oxygen concentration cells have been extensively used in laboratories as well as in industries. In metal-production technology, these cells have been used to monitor the oxygen potentials in metallic, slag as well as gas phases and also to control and styr metallurgical processes. The pioneer among the various industrial users of such cells is the copper industry. To-day, high temperature solid electrolyte cells involving oxygen ion conducting electrolytes have become an integral part of copper pyro-refining and continuous casting. In the present paper some of the applications according to the industrial processes are described including the developments that are going on in the European scene."

Jan 1, 1997

By Alicia E. Ares

316 L Stainless Steel samples were solidified directionally under conditions which produced the columnar to equiaxed transition. The position of the transition was located in each sample and the distance from the bottom of the ingot was measured. During solidification the distribution of temperatures were measured by means of thermocouples located strategically. From the measured temperatures the following parameters were derived; the local temperature gradient, the cooling rate and the velocities of the liquid and solidus fronts. Comparing the location of the transition and the values of these parameters it was found that the temperature gradient reaches negative values of as low as -13.44 "C/cm, and velocities of the fronts of around 0.1 cm/s. Also, a supercooling of 5.81°C were measured which was associated with the supercooling for the nucleation and growth of the equiaxed grains ahead of the columnar front. In addition the primary and secondary dendritic spacing was measured in both regions. The spacing was compared with the predictions from available models. The results are presented and discussed in the frame of the results obtained for other alloys

Jan 1, 2002

By D. F. Suarez

Spontaneous nodulation leading to growth of well developed glossy spheroids (generally hemispheres) of up to 0.06 cm width in 120 min has been observed during copper electrodeposition with certain levels of glue, thiourea and C1-. Thiourea alone can produce spontaneous nodulation but addition of glue and/or Cl- is required for rapid and sustained growth. In most cases once the glossy nodules develop they consume the majority of the copper deposited; thus, the specific current densities (and hence copper electrodeposition rates) on the glossy nodules are about an order of magnitude or, more greater than on the adjacent planar surfaces. The texture of the adjaoent planar surfaces is not glossy in appearance but is well faceted showing the usual deposition grain structure for such additives. Cathode potentials when spontaneous nodulation occurs are about TOO my more negative than with usual copper electroplating. This fact associated with evidence of extremely high levels of cathode surface passivation based on cyclic voltammograms indicates that the conditions which lead to spontaneous nodulation result from a very tightly adsorbed additive surface film. This film breaks down in specific points initiating the glossy nodules which then grow at extremely rapid rates. Current density is also important in spontaneous nodulation. At equal deposition times a current density of 21.5 mA/cm produced much larger glossy nodules than at 48 mA/cm2. The surface concentration of the glossy nodules was much greater in the latter case, however. The role of current density is still not well understood. The role of it as well as the relative roles of the three additives, thiourea, glue and Cl- in spontaneous nodulation is presented. Preliminary results and some possible correlations of these to help explain spontaneous nodulation are presented. It is believed that tankhouse upsets where cathode nodulation occurs may be related to this phenomenon.

Jan 1, 1987

By C. Kathryn Sole

The close proximity of cobalt and nickel on the Periodic Table and their frequent occurrence together in nature means that their separation in primary hydrometallurgical flowsheets is not only often necessary, but requires the use of innovative chemistry to achieve high selectivity. Today, increasingly stringent demands for the high-purity cobalt and nickel salts required for battery applications in consumer electronics, electric vehicles, and solar applications are again challenging the state of the art. The evolution of cobalt–nickel separations is traced from the basic precipitation technologies employed in 1960s, through commissioning of the first cobalt solvent-extraction plant in South Africa in 1974, to the commercialisation of organophosphinic-acid extractants (which provided a step-change improvement in selectivity) and their eventual widespread use in the 1980s and ’90s. This was followed later by their sulphur analogue, which enabled different possibilities for laterite processing in the new millennium. Separations in chloride media, which take advantage of the different speciation chemistries, and nickel extraction by oximes in ammoniacal systems are also discussed. More recently, chelating and solvent-impregnated resins have added further dimensions to the possibilities for flowsheet design and enabled higher purity products to be attained from both primary and secondary sources. Selected case studies and flowsheets are described.

By S. I. Sobol

Completeness of cobalt recovery from slag requires decomposition of maggemite and non - ferrous metal desorption with polymerized silicon-acid. Cobalt losses are reduced in leaching tai1s up to 200 g/t of iron.

Jan 1, 1993

By N. A. Barcza

DC plasma-arc technology using a hollow graphite electrode (cathode) has been successfully implemented in the primary metallurgical industry in South Africa up to the 30 MW scale. Mintek has applied its expertise base, established over the past fifteen years, to testing the treatment of metallurgical wastes such as carbon- and stainless-steel plant dusts, lead- and zinc-containing slags, and residues from the base-metal industry. Favourable results have been achieved, and disposable products were produced. The evaluation of numerous wastes indicates that recovery of zinc as metal gives the best economic return from these sources. Direct recovery via a splash condenser or electrolytic zinc extraction from fume are the two preferred alternatives under review. In both instances dehalogenation is an important issue, but can be achieved by suitable treatment processes. The Enviroplas technology provides a flexible, commercially viable approach to the treatment of a wide variety of wastes. Mintek, together with its associate Pyromet CC, are installing a plasma- arc pilot-plant facility with both an ISP lead-splash condenser of about 5 t/d condensed zinc capacity and a combustion chamber to burn zinc vapour to zinc oxide. This will demonstrate the suitability of the Enviroplas technology for treating specific metallurgical wastes, so that customized industrial plants can be engineered based on large-scale testwork.

Jan 1, 1994

By Mingchun Lu, Yunjin Yan

"This paper describes a new type of bell-less top installed on two relined blast furnaces at Tianjin Iron Works and another new-built at Echeng Steel Works in China. A compact installation was presented for existing furnace top innovation with the least reformation of existing top structure. A water cooling and sealing gearbox used for driving the chute discards completely the traditional idea about necessity of continuous supply of cooling gas for the gearbox. A multiring spreader and its dozens of selectable charging patterns enables an operator to achieve optimal burden distribution easily under the condition of a minimum investment of control equipment. Some useful conclusions have been made through a small-size model and a full-scale model tests. The excellent characteristics and the superiority of the new top have been fully proved at both works.IntroductionIt is known that there are some advantages with the bell-less top of a blast furnace: suitable for furnace to operate at high top pressure, capable of realizing optimal burden distribution, less investment and maintenance costs, etc. But why do most of blast furnaces in the world still remain using conventional bell top. One of the concerns is that current bell-less tops still have some shortcomings:1) The height of a current bell-less top might be lower than three or four-bell top or two-bell plus valve seal top, but still much higher than an ordinary two-bell top.2) The gearbox for driving the rotating chute is positioned onto the lip of the furnace. It is subject to attack by crude hot bf gas. Continuously pumping cooling gas (pressurized nitrogen or clean bf gas) into the gearbox is indispensable to withstand such a harsh working environment. Therefore, a plant furnished with blower8 and its ancillaries has to be built, It involves a large sum of investment and much expense in its annual running costs.3) Although the current bell-less charging device as a means of controlling burden distribution possesses a wide range of freedom, it is difficult to realize optimal burden distribution. There are some large blast furnaces realized better burden distribution, but sophisticated control means is indispensable so that the investment of control means is much higher."

Jan 1, 2000

By Jorge Alberto Soares Tenório, Viviane Tavares de Moraes, Denise Crocce Romano Espinosa, Franco Alves Lavacchini Ramunno

"The traditional process for recovery of metals from waste electric and electronic equipment (WEEE) usually involves pyrometallurgical processing. However, the application of this technology to processing waste printed circuit boards (WPCBs) might lead to the formation of dioxins and furans, due to thermal degradation of flame-retardants and polymeric resins present in the board substrate. Therefore, this paper proposes a hydrometallurgical route for the recovery of copper. The acid leaching behavior of copper has been investigated at three different temperatures (25°C, 50°C and 75°C) with and without the addition of an oxidizing agent (hydrogen peroxide - H202). The dissolution kinetics for acid copper leaching was calculated based on chemical analysis by ICP-OES (Inductively Coupled Plasma - Optical Emission Spectroscopy). At 50°C with 1 mol/L H2S04 added 10 mL H202 (30%) each half hour under pulp density of 1 g I 10 mL, 100% of copper was extracted after 3 hours. The dissolution kinetics of copper with H2SO4-H2O 2 followed 1 - (1 - X)113 =Ket, i.e. chemically controlled reaction model.IntroductionThe information regarding the generation of waste electric and electronic equipment (WEEE) are still difficult to obtain because the estimates should take into consideration the historical production and sale of various products and the rate at which they reach the end of their life cycle, whose duration depends on the behavior of consumers [1]. Thus, the estimated overall WEEE generation varies between 25 and 50 million tons each year, which corresponds to more than 5% of all municipal waste generated [2], and this amount will increase at a rate of 3 to 5% per year, approximately three times faster than other individual types of waste [3].Printed circuit boards (PCBs) are essential parts of electric and electronic equipment (EEE), being found in virtually all electronic products, as well as in weapons systems [4]. A PCB is a basic component, which consists of a board where copper tracks are deposited. While the board behaves as an electrical insulator, the tracks connect electrically the various components attached to the board [ 5]. In addition to glass fibers, paper and resins, the PCBs contain significant amounts of metals, such as copper, iron, nickel, lead, stain, silver, gold and palladium [6]. In general, the weight fraction of metal is around 28% and the remainder of the boards is composed of plastic (19%), bromine (as flame retardant - 4%) and ceramic material (49%) [7]."

Jan 1, 2014

By J. H. Meza V

La Caridad operated at only 65% of design capacity during the first five years of operation. After the first major shutdown and repairs to the furnace in mid- 1992, the smelter quickly reached 95% of design capacity. Converter operation is now more efficient; blowing times have decreased from about 1.7 to 1.2 min/ton of matte. Anode copper production is now 15000 tons/month. The increased efficiency provided by better coordination and scheduling ensures La Caridad's ability to operate at present and expanded production capacity while simultaneously meeting environmental control standards.

Jan 1, 1993