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By M. -L. Metsärinta, J. Nyberg, A. Roine

The Kokkola roasting plant uses more than 20 different zinc concentrates every year. During recent years there has been an increase in the variation in concentrate quality; in particular, the amount of fine-grained and low-grade concentrates has increased. Therefore, a great deal of development work has been carried out to improve the operational flexibility, online availability, production capacity and calcine quality of the roasting plant. This work consisted of a heat and material balance model of the roasting based on HSC Chemistry software, a new water admixture system for the concentrate feed, a new oxygen feed system for the process air line, improved cooling of the furnace and boiler and improved operational practices, dust removal and concentrate mixing. These new process control tools and other improvements, as well as some test results, will be described in this paper. The oxygen feed may be used to improve production capacity and to decrease the sulfide content of the calcine. The water feed may be used with fine concentrates to decrease both dust carry-over and the temperature in the top part of the furnace. Improved cooling of the furnace and boiler helps to increase production capacity.

Jan 1, 2000

By Georgette Smits

The gun-sprayed refractory lining of electrothermal furnaces used for the manufacture of carbon disulphide from liquid sulphur and charcoal at between 800 and l000°C are severely attacked during the process. A mineralogical study of samples of eroded refractory material disclosed that carbon disulphide had penetrated the lining, causing the precipitation of sulphides and carbon, and the decomposition of mullite, a major constituent of the lining, to corundum and amorphous silica. Calcium, iron, titanium, and chromium are undesirable cations in a refractory that is used in furnaces for the production of carbon disulphide, since they react readily with this substance. A series of tests, in which samples were exposed to different amounts of carbon disulphide for various residence times and at different temperatures, was carried out with eight types of aluminosilicate-based castable and brick refractory materials, to compare their resistance to attack by carbon disulphide. Mineralogical investigation of the test cores showed that castable refractory materials are unsuitable for this type of process because of the presence of calcium aluminates and other impurities in the cement. Of all the refractories that were tested, a mullite brick of low porosity, containing a minimum amount of impurities, appeared to be the most suitable for use in this type of operation.

Jan 1, 1989

By T. T. Chen, J. E. Dutrizac

Noranda Inc., CEZinc presently employs a cement-stabilization (jarofix) process to stabilize its jarosite residues for direct disposal. In this process, Portland cement partly decomposes Na-jarosite to form Ca6Fe2(SC>4)3(OH)i2.nH20, ferric hydroxide and sodium sulphate which further reacts to form gypsum; approximately one-third of the Na-jarosite reacts in the current commercial product. The cured jarofix products also contain minor amounts of various Ca-Al-Fe silicate-sulphate-hydrate phases and traces of calcite. Together with gypsum and a Ca-Fe sulphate phase, these species bond the various particles together, imparting mechanical strength and reducing the permeability. Water-soluble Zn and Mg are stabilized in the Ca-Al-Fe silicate-sulphate-hydrate phases. The freshly cured products usually contain small amounts of moisture and traces of residual Portland cement, which provides additional alkalinity for the neutralization of any residual acid species. Jarofix products stored for more than six years in the laboratory, after curing, are usually dry and exhibit the same micro-textures as those of the freshly cured products. However, the stored products are depleted in the Ca6Fe2(S04)3(OH)i2.nH20 and Portland cement phases, and are enriched in gypsum and calcite which reflects the highly alkaline environment of the jarofix products. The aged products also have increased amounts of the Ca-Al-Fe silicate-sulphate-hydrate phases which have elevated Zn and Mg contents. This implies a further immobilization of residual water-soluble Zn and Mg during stora

Jan 1, 2000

By H. Virtanen

Outokumpu copper refining operations have a long history of expansions and application of new technologies. Outokumpu is a name known around the world for technological excellence in the field of base metals, and part of the policy of operations is continuous investment and investigation in new technologies. The results of this hard work sometimes are immediate and sometimes take years. The work done during the last years at the Outokumpu Harjavalta Metals copper refinery, together with a sister technology group Outokumpu Wenmec, has started to bear fruit in terms of the following radical developments and advances that are and will be applied to assure Outokumpu's position as the technology leader and a low cost and safe producer. Some of the developments discussed include the new anode and cathode design, mechanised electrode handling, cell design incorporating features facilitating full automation, automated short circuit detection and removal, automated on line anode slime removal, and high efficiency and intensity refining.

Jan 1, 1999

By Ying Mao, Zhancheng Guo, Long Ma, Huiqing Tang

"A new 2D computational fluid dynamic (CFD) model was developed for the gaseous reduction of iron ore fines in an innovative reactor-multilayer moving-fluidized bed. The solution of the proposed model was performed by integration of FLUENT and PHOENICS. Numerical results of cold state were compared with the experimental data and the agreement between them was good. A hot case-gaseous reduction of iron ore fines using syngas with this reactor was simulated using the present CFD mode. Results indicate that under the given simulation conditions, total pressure drop is 90 Pa less than that under cold state though the gas supply rate is increased about 4m3 under hot state. Gas temperature decreases from 1073 K at the bottom to 500 K at the top, Utilization efficiency of the gas reduction potential is about 27 %. For ore fines reduction, the final reduction fraction could reach 0. 70 and solid temperature 900 K.IntroductionWith the development of coal gasification technology, various coals could be converted to Syngas with air or steam. Therefore gaseous reduction of iron ore fmes becomes an acceptable alternative process for iron making besides blast furnace route[!] and moreover it still has some advantages in processing low grade iron ore fines[2]. Gaseous reduction using fluidized bed technologies is the most competitive in all direct reduction iron-making processes up to now. It has the advantage that ore fines can be directly charged to the process without prior treatment while its disadvantages are particle agglomeration and high gas/solid ratio[3]. To avoid these advantages, a new reactor, multilayer moving-fluidized bed reactor has been developed for carrying out the gaseous reduction. Hydrodynamic behaviors of gas and fines in the reactor were studied and the results were satisfying[4]. However, due to its unique structure of the multilayer moving-fluidized bed and unique gas-solid flow pattern, models of multiphase flow as IPSA, DPM and Eulerian Model could not give a satisfying solution. The current paper is developed a new CFD model and a new solution approach for simulation of the reactive gas-solid flow in the multilayer moving-fluidized bed for its optimization, design improvement and future scale-up."

Jan 1, 2013

The copper concentrate market is becoming increasingly unstable. In the early 1990s large concentrate stocks were built up and the glut was cleared only after treatment charges rose so sharply that 'non-traditional' custom smelter capacity, such as in Kazakhstan, could be employed, By 1994 the market had shifted and Western smelters were unable to secure enough concentrates to operate full out. The reason for these sharp swings in the market balance is that virtllally all the recent mine development has been non-integrated. With different companies developing new mine . and smelter capacity, it is inevitable that the pace of expansion in the two sectors will not be coordinated. For many years the Japanese smelters were the major buyers from the new mm-integrated mines. However, Japanese smelter capacity is unlikely to increase appreciably in the future and this stabilizing influence will be very difficult to replace. This paper will examine the likely concentrate/smelter balance over the next five years and will forecast the likely direction of? treatment charges. It will also touch on the critical variables in assessing the viability of new greenfield custom smelter capacity, such as proximity to concentrate sources, by-product sulfuric acid prices and, most importantly, tariff protection.

Jan 1, 1995

By J. Boltano

This paper discusses the study, design and implementation of the new gas handling system for the Caletones Smelter of Codelco-Chile. A discussion on design conditions for a future Sulphuric Acid Plant using Teniente Converter gases is also included. The old system which started to be modified in 1985 and relied on natural draft and used balloon flues, resulted in a limited gas handling capacity for operation under future process conditions. This system also caused excessive fugitive gases in the smelter working areas. The new system permits handling of process gases from the higher capacity Teniente Converters Installed in 1987-1989 improving the gas handling of the reverberatory furnaces and Peirce-Smith converters as well as the environmental conditions of the smelter. This system utilises improved converter gas hoods, evaporative cooling and electrostatic precipitators gas cleaning, and is based on natural draft.

Jan 1, 1992

By Robert H. Hsu

Palladium finely dispersed in a substrate of kieselguhr, Pd/k for short, has been successfully used for hydrogen storage, separation and pumping for a number of years at the Savannah River Site (SRS). Recently SRS has developed a new pd/k flow through bed (FTB) prototype for separating hydrogen from other gases and simultaneously storing the hydrogen on palladium. The FTB uses single-pass liquid nitrogen cooling during hydrogen absorption/separation/storage and electrical heating for desorption/unloading of hydrogen. Fourteen absorption-desorption or loading/unloading cycles using hydrogen have been conducted with the new FTB prototype. Test results show that all design performance objectives have been successfully achieved: recover 295% of hydrogen gas from feed gas, produce 99.9% hydrogen product gas and < 5% hydrogen in discharge gas. This paper will discuss characteristics of the palladium-coated kieselguhr or diatomaceous earth, design and operation of the FTB, and results of performance tests such as separation efficiency, hydrogen storage capacity and system heat transfer characteristics.

Jan 1, 2002

By Hong Yong Sohn

A thermodynamic and experimental investigation has been performed to develop a new process for converting sulfur dioxide to elemental sulfur by a cyclic process. The most promising new process is a cyclic reaction scheme involving calcium sulfide and calcium sulfate. In this process, the reaction between sulfur dioxide and calcium sulfide produces elemental sulfur vapor and solid calcium sulfate. The latter is reduced by a suitable reductant such as hydrogen to regenerate calcium sulfide. &apos;Experimental results showed that up to 60 % of calcium sulfide powder was converted to calcium sulfate in 10 min at 1153 K under a sulfur dioxide partial pressure of 25.8 kPa. More than 95 % of nickel-catalyzed calcium sulfate powder was converted to calcium sulfide in 20 min at 1123 K under a hydrogen partial pressure of 86.1 kPa, water vapor being the only gaseous product. Sulfur dioxide-containing streams from certain new sulfide smelting plants contain much higher partial pressures of SO2. The rate of the first reaction is expected to be accordingly higher than in the test conditions reported in this paper.

Jan 1, 2002

By D. Nozadze

A new method of isothermal electro-contact diffusion welding of layered composites under pressure is offered. The scheme is developed and laboratory installation is created on which preproduction models of the layered composite of steel and aluminum is produced. A new method of electro-contact hot deformation is proposed for realization of diffusion welding by pressure of stratified blanks providing high-temperature isothermal process. In this case a rolling process or composite pressing is meshed with simultaneous electric current transmission in deformation center. Considering that a resistance of transient layer far exceeds the resistances of composite components, the heat release takes place intensively just in this layer. As the surfaces are approached over a distance of inter-atomic forces, the energy of boundary atoms easily reaches the energy threshold of capture with a formation of qualitatively new metallic bond. Proposed method, providing isothermal process in deformation center, excludes a necessity of previous preparation and prevention of surfaces. In this case strength of layer connection may approximate or exceed strength limit of cladding layer.

Jan 1, 2006

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 Yuhua Pan

Generic mathematical models have been developed for simulating heat transfer in two types of slag resistance heating electric furnaces for sulphide smelting: i) six-electrode-in-line rectangular furnaces and ii) three-electrode circular furnaces. The models are based on three-dimensional steady-state heat transfer of conduction, convection and radiation. Solidification of liquid slag into solid slag by water-cooling units, for use as freeze lining of furnace walls, is also considered in the models. The developed models are capable of providing predictions with reasonable accuracy for electric furnaces on 1) temperatures in slag, matte, cooling water, freeze lining and other solid regions as well as temperatures at various fluid/solid interfaces, 2) freeze lining thickness, 3) furnace smelting rate and 4) furnace heat loss rate. These computer models are built into executable application programs that are very efficient, with execution time less than one second, and can be easily portable to most computing platforms. This paper describes, as an example, the modelling results on heat transfer in six-electrode furnaces. The major modelling results show that in six-electrode furnaces uniform electric power inputs to the electrodes likely lead to low temperature regions close to slag and matte tapping ends of the furnaces, and the power input and the formation of air gaps between freeze lining and cooling units have significant influences on the thickness of freeze lining maintained by the cooling units.

Jan 1, 2006

By C. J. N. Buisman

THIOPAQ technology developed and marketed by PAQUES Bio Systems in Balk, Netherlands, has been successfully used at commercial scale at the Budelco zinc refinery in the Netherlands for the treatment of contaminated groundwater since 1992. In essence, THIOPAQ technology consists of two biological process steps in series: sulfate reduction to hydrogen sulfide (anaerobic) and sulfide oxidation to elemental sulfur (aerobic). The biogenic sulfide produced can be employed for the chemical precipitation of metals in solution either inside the anaerobic reactor or in a separate vessel. Since the solubilities of most metal sulfides are much lower than of their respective hydroxides, considerably lower effluent metal concentrations can be achieved with THIOPAQ systems than in neutralization processes which immobilize metals predominantly by hydrolytic precipitation. In recent years, PAQUES has made significant advances in the design and operation of aerobic and anaerobic bioreactors for metal-sulfur systems. Moreover, the company has increased its technology portfolio to allow the development of more process oriented applications of THIOPAQ technology. A new PAQUES designed plant at Budelco treating sulfatecontaining proceswaters will be started up in 1999. The sulfate reduction is accomplished in a 500 m3 reactor in which hydrogen is used as electron donor. The endproduct, ZnS, is used for Zn and H2S04 production.

Jan 1, 1999

By Klaus Gamweger

"This paper introduces an innovative solution to open and close the tap hole of different furnace types in the copper industry with a slide gate system. Two plates with defined drilled holes are slid against each other, which enables effective starting and stopping of the copper flow as well as throttling. Typically, the copper is poured via a tap hole into a launder system by rotating the furnace into an appropriate position. Control of the casting rate is also performed in this manner. Or, in case of stationary furnaces the tap hole is opened by oxygen lancing and closed manually with a clay- or copper-cone. These procedures show a lot of disadvantages including splashing, oxygen pick-up, and energy losses as well as a severe danger for the working staff. All these problems can be overcome with an appropriate slide gate system.IntroductionThe control of the casting rate of a copper anode furnace usually is performed by rotating the furnace into an appropriate position. This implies that the taping starts with the tap hole at a very high position. Copper splashing and an uncontrolled oxygen pick up are - with several more disadvantages - the consequences. RHI AG has developed an innovative solution for copper applications to open and close the tap hole with a slide gate system which allows also an accurate control of the flow rate. By using this system it is possible to start the casting procedure with the tap hole at the deepest position, directly above the launder. This paper presents this new slide gate system in detail and shows the advantages in production and safety issues."

Jan 1, 2012

By Yasumasa Hattori

An extensive study including fluid dynamic calculations, cold model tests, pilot plant tests as well as measurements in a commercial flash furnace was carried out in order to develop a new Sumitomo flash smelting concentrate burner. The pressure measurements in the commercial burner indicated that the premixing of the concentrate and reaction air in a burner was insufficient. Pilot plant tests showed that enhancement of the premixing of the concentrate and reaction air is very effective for improving the burner performance. Using the additional pressure drop of the reaction air as an indicator of the premixing, a new type Sumitomo premixed concentrate burner was developed.

Jan 1, 2003

By J. Boitano

This paper discusses the study, design and implementation of the new gas handling system for the Caletones Smelter of Cbdelco..Chile. A discussion on design conditions for a Mure Sulphuric Acid Plant using Teniente Converter.gases.is also included. The old system which started to be modified in 1985 and relied on natural draft and used balloon flues, resulted in a limited .gas handling capacity for operation under Mure process conditions. This system also caused excessive fugitive gases in the smelter working areas. The new system permits handling of process gases from the higher capacity Teniente converters installed in 1987-1989 Improving the gas handling of the reverberatory furnaces and Peirce-Smith converters as well as the environmental conditions of the smelter. This system utilises improved converter gas hoods, evaporative cooling and electrostatic precipitators gas cleaning, and is based on natural draft.

Jan 1, 1992

By Ledjane Barreto, Tulio Flávio Accioly de Lima e Moura, Wilson Acchar, Antonio Carlos Silva da Costal

"Clays are common ingredients in pharmaceutical products both as exclplents and active substances. Clay minerals are naturally cationic exchangers and they may undergo ion exchange with basic drugs in solution. Smectites, and montmorillonite have been studied due their high cation exchange capacity as compared to other silicates. Recently a patented study reports the use of attapulgite as the encapsulating agents both for the protecting the active substance and modulating release into the body. Some clays such as kaolinite, smectites, talc, etc are also used as dermatological protectors. Sepiolite and smectites have the ability to form complexes with organic compounds with absorb ultra-violet radiation, enabling them to be used in sun screens with protection factors. The objective of this work is to characterize the attapulgite in order to study the potential use of this clay material in the human health.IntroductionSince the begimling of time, nature has served humanity as a source of various raw materials. Among these, clays such as kaolinite and ilitte are common ingredients in the tile production. Recently, special clay materials have been investigated in order to identifY new potential uses of these class of materials. Clay materials are natural raw material and have excellent properties such as low toxicity, good biocompatibility, making them a good material to be used in biological applications. Attapulgite (paligorskite) and sepiolite is so called special clays. These special clay materials are very sin1ilar and have a great potential to be used in some technological areas due their special catalytic, sorptive and colloidal-rheological properties [1-8]. Recently some works have reported the use of these special clays materials for many applications such as drug delivery, wound dressing, oil absorbent, pesticides, fertilizers [9-12]. Brazil has a significant reserve of attapulgite located in Piaui state, making the study of the potential of this mineral in special areas, very attractive. Attapulgite is classified a fibrous alluminous silicate material and shows the presence of micro pores and channels, fine particle size and high surface area making this material a good candidate alternative material to be used in many industrial applications [6,8,9,11,12]. The objective of this work is to characterize the physical and microstructure of attapulgite."

Jan 1, 2012

By G. Hanko, A. Lebleu, M. Sibony, J. Lecadet

The New Jersey distillation process is today the most important pyrometallurgical method for the production of zinc of very high purity. The flexibility of the pyrometallurgical zinc production process, especially its ability for recycling, makes it competitive, although it is energy intensive. A deeper knowledge of the New Jersey process is necessary to further increase its technical performance by ensuring its global safety. A project, integrated in the European research program EUREKA, has been started in order to define the process chemistry of distillation. Experimental measurements have been carried out with a column at the laboratory scale, and the results, linked with industrial measurements, support the development of a model based on material and thermal balances. The first conclusions indicate that the key parameters for process optimization are the column geometry and the distribution of the thermal losses.

Jan 1, 2000

By S. Suda

Hydrogen storage materials have been investigated for more than 30 years, particularly on metal hydrides. These materials are, however, considered today impractical because of their poor hydrogen capacity measured by mass density and their poor surface properties and characteristics against impurities. Recent R&D activities have been located in new categories of materials such as complex hydrides and chemical hydrides. Among these materials, NaAlH4 (one of alanates), Li-based complex hydride, and NaBH4 (SBH: sodium borohydride) are 3 major candidates as hydrogen storage materials. In the presentation, SBH as a non-reversible on-site but recyclable off-site is described in view of its practical availability as the source of H- (protide) applied for a new type of fuel cell named Direct Borohydride Fuel Cell (DBFC) and H2 (hydrogen) for Proton Exchange Membrane Fuel Cell (PEMFC).

Jan 1, 2006

By Helmut Attlfellner

The selection of the best process for the oxygen generator for a metallurgical process requires the determination of all aspects which impact the economics of this facility. Concepts and features of modern air separation plants will be presented based on installed facilities for various metallurgical processes. The special features of advanced automation&apos; of oxygen generators with load following and optimization of power consumption, automatic restart and unattended remote controlled operation will be investigated.

Jan 1, 1992