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By C. E. Hunt

Since the turn of the century, copper-nickel sulphide ores have been processed at the Sudbury, Ontario operations of INCO Limited, currently the largest integrated mining, milling, smelting and refining complex in the free world. Through the years operational, ecomomic, social and legislative changes have dictated the need for research and development directed at mitigating the impact of existing operations on the surrounding natural environment and also the reclamation of areas affected by earlier mining activities. Approximately one hundred years of mining history and the current annual processing of some 12 million tons of ore presents significant challenges with respect to waste disposal, liquid effluent treatment and land reclamation, particularly in light of rapidly evolving environmental regulations' and controls within the Province of Ontario.

Jan 1, 1992

By Akram Salah Eddine Belaidi, Lakhdar Azzouz, Benchaa Benabed

"The dunes sand is a material of a large availability in Algeria. This material is practically unexploited. The introduction of this material as a new element in the construction can be more relieve the domain of building, and contribute to the development of the southern regions of Algeria, which are very rich in this material. The main objective of our work is to exploit a largely available material in the Algerian south which is the dunes sand, as a material of construction in the region of Laghouat.In this study, first we investigated the effect of the curing environment and the nature of the sand on the mechanical properties of the mortar, such as; flexural and compressive strengths. Then after, we studied the durability of the mortar under cycles of wettingdrying and the chemical attack of sodium sulfate (Na2SO4 5%).According to the results, we note that the mortar of the sand mixes (river sand plus dunes sand) present the best mechanical performances under different environment of curing. In addition result of durability studies put forward that the mortar of the sand mixes is more resistant to the sulfates attack."

Jan 1, 2008

By Valeriano Antonio Corbellini, Marilda Macagnan, Rosana de Cassia de Souza Schneider, Tiago Bjerk, Mariela de Souza Vieira

The great potential of Brazil for the agricultural production makes our country a generator of agro industrial residues. In this context, the solid-state fermentation appears as a technology that shows alternative ways for those residues, adding values to these raw materials, through the production of substances of industrial interest, besides reducing the possible environmental problems. The main objective of this study was to apply the bovine fat residue associated to the garden grass for the fungal lipase production. Initially, 75 microbial cultures were isolated from garden grass samples after incubation of the mixture with bovine fat. From these cultures were selected the filamentous fungi, whose lipase production abilities were evaluated. The isolation and the selection were accomplished by using a differential culture medium containing Tween 80 as inducer substrate of lipase production. The colonies with lipolytic potential were detected by the presence of white precipitation haloes on the agar. With agro industrial residues the best lipase producer fungus was identified as Penicillium sp in 6 days of solid state fermentation. The crude enzyme obtained was tested in transesterification process for the biodiesel production.

Jan 1, 2008

By Kerri-Ann Hue, Kerry Hasapidis, Ken Babcock, Patrick O'Hagan

"Metallic nanoparticles exhibit properties that are significantly different from individual atoms or bulk materials. Their applications are diverse and have varying uses in areas such as cancer treatment, biochemical sensors, nanoelectronics, and drug delivery. For each application extensive characterization must be performed in order to probe the unique properties of these nanoparticles. In this study, ultra-high resolution mass sensors consisting of MEMs-fabricated, suspended microchannel resonators (SMRs) were used to determine the size and concentration of metallic nanoparticles. With femtogram (10- 15 g) mass resolution, ultra-high resolution mass sensors can weigh individual particles suspended in fluid, and so measure their mass, density, and size. Particle size analysis with these sensors provides excellent accuracy and resolution compared to mature technologies such as light scattering. This technique also provides quantitative information via the ability count particles.IntroductionThe unique electronic, chemical, and optical properties associated with nanoparticles vary with their size, shape, and composition[ 1-4]. These properties are attributed to increased surface area and nanosized mean free path of electrons to the particle surface. Nanoparticle colloidal solutions have been prepared and are commercially available. In recent years, noble metals such as gold, copper, and silver have been extensively researched[5-7]. In order to tailor the optical, electronic, and electrical properties of nanoparticles, size and shape must be controlled. For many applications a monodisperse colloidal solution is ideal. Methods of size characterization include Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), and Electrophoretic Mobility Measurements to name a few[6, 8]. Although TEM can provide shape and size distributions, sample preparation requires that samples be dried on a metal grid and cannot be analyzed in solution. DLS uses curve fitting algorithms that while useful for determining mean particle diameters are not ideal for polydisperse colloidal solutions. New technologies are therefore needed to accurately determine the particle size distributions of metallic nanoparticles."

Jan 1, 2011

By Santhanam Ramesh

"The shell (exoskeleton) waste of shellfish such as shrimps and crabs is the raw material in the extraction of chitosan, a polymer. Chitosan has several medicinal values such as reduction in cholesterol, urea and creatine in the blood. It is estimated that about 40000 tonnes of chitosan may be obtained from all chitin yielding invertebrate sources of India and a foreign exchange of 600 million US$ could be earned annually. Awareness has to be created among sea food processors to put up plants to convert shellfish wastes into chitosan. Similarly pharmaceutical industries may use chitosan in the development of new drugs. Types of training and awareness programmes to be organized for entrepreneurs, sea food processors and pharamacists are discussed in this paper.IntroductionIndia earns annually foreign exchange to the tune of 0.8 million US$ by exporting processed marine crustacean shellfish resources such as shrimps, crabs and lobsters (Figure 1) through 300 sea food processing industries. At present, only a small quantity of shell wastes (exoskeleton) generated from the above is utilized as an ingredient in fish feeds and hence much of the wastes are disposed off either as land fill or by direct dumping in sea. These wastes containing primarily chitin could be the major raw material for the production of a proteinaceous byproduct viz. chitosan, a highly valued pharmaceutically important source"

Jan 1, 2008

By Patrick R. Taylor

Iron phosphate glasses are promising host matrices for vitrifying actinide rich nuclear wastes materials because of their high solubility of actinide oxides, high chemical durability, and relatively low melting temperatures. An iron phosphate waste form was developed at the University of Missouri-Rolla. The structure and property of the waste form were well characterized by materials techniques. However, to scale the process and advance it to commercial viability, it is necessary to understand the processing parameters, such as the partitioning of waste elements and the viscosity as a function of temperature. Viscosity of 40 Fe203 - 60 P205 mole % iron phosphate melts (prepared with phosphorous pentoxide and ferric oxide) at 1000-1200 C was measured by the rotating-spindle method. It was discovered that this fluid has non-Newtonian behavior. Experiments were performed to study flow properties following the Standard Test methods for Rheological Properties of Non-Newtonian Materials by Rotational (Brookfield) Viscometer (ASTM D 2196-86). Samples prepared using ammonium phosphate and ferric oxide showed Newtonian behavior and the temperature dependence of the viscosity was studied over the range of 1000 to 1200 degrees C. The difference in flow behavior between the two fluids was analyzed in terms of preparation conditions and variation in the final composition and phases. The partitioning behavior of waste elements in the iron phosphate glass was studied by melting in a high temperature furnace and JCP analysis. The experimental results show that the solubility of Ce and Sr in phosphate glasses is significantly higher than the solubility associated with borosilicate glasses. This strengthens the conclusion that iron phosphate may be a viable alternative to borosilicate glass for immobilization of high heavy-metal-content wastes and actinide rich wastes.

Jan 1, 2002

By Guozhu Ye, Eric’ Burstrom

"Despite of numerous solutions for recovery of zinc from EAF dust have been suggested and tested in laboratory scale over the last three decades, Waelz kiln process is still the most dominating process for treatment of EAF dust. Few of the proposed alternative methods have gone beyond the laboratory tests. This paper will give you insights to some of the concepts that have been pilot tested at MEFOS. The innovative aspects of these concepts will be shown and the major results will be highlighted. These include the following concepts: - Production of a crude zinc oxide product with low halide content for zinc electrowinning using a DC furnace with hollow electrode- Production of a bypass filter dust containing more than 50%ZnO by injection of EAF dust to the electric arc furnace during refining combined with a bypass filter system- Elimination of zinc ferrite by CaO treatment for electrowinning with EZINEX process - Selective reduction of iron oxide in zinc ferrite for simultaneous recovery of ZnO andmetallic ironIntroductionRecovery of zinc from EAF dust is dominated by the Waelz process since EAF dust has been classified as hazardous waste by EPA in the early 1980´s. A large number of alternative processes have been suggested and tested without commercial success due to two major reasons [1]:- High content of chlorine and fluorine for the pyrometallurgical alternatives- High content of ZnOFe2O3 for the hydrometallurgical processesMany innovative concepts for treatment of EAF dust for zinc recovery have been pilot tested at MEFOS in the past 20 years. This paper will review some of the concepts focusing on the two problems mentioned above."

Jan 1, 2008

By Qionghua Zhou, Wei Liu

"Nanocrystalline silver bulk material with average grain size of 20.3 nm was prepared by warmvacuum- compaction method. The as-prepared nanocrystalline silver was characterized by X-ray diffraction (XRD), differential scanning calarmeutry analysis (DSC), thermogravimetric analysis (TG), and 6157 type Electrometer test, respectivily. The experimental results show that the average grain size and microstrain of the nanocrystalline silver are 20.3 nm and 0.088%. The melting point and melting enthalpy are 1228.7 Kand 82.34 Jig, which are lower than that of coarse-grained silver by 6 Kand 22.6 Jig, respectively. The electrical resistivity of nanocrystlline silver increases with higher temperature when the range of temperature is between 233K and 293K. The electrical resistivity at 293 K is 1.475xlO -7 Q·m, which is higher than that of coarsegrained silver by a factor of 9.IntroductionN anocrystaline ( nc) materials or nano structured ( ns) materials are three-dimensional (3 D) bulk materials with average grain size typically smaller than 100 nm. Ne materials have been of great interest for their unique properties, such as superior tensile strength [1-2], high microhardness [3- 4], superplasticity [5-6], magnetically quasi-isotropic [7-8] , and so on, making them one of the most promising nano-scale materials with wide applications. Ne materials with average grain size of 5-10 nm were firstly fabricated by Gleiter et al. [9] in 1980s, using inert gas condensation (IGC) method. Unfortunately, the large surface to volume ratio creates a high surface energy component in the total free energy of the system and results in a metastable state in the materials. Therefore, due to the signfica nt disordered grain boundary regions, nanomaterials are thermally unstable and are subjected to a strong driving force for grain growth. The grain growth even occurred at room temperature [10].The conflict or deviation of measured date, e.g. strength, microhardness, thermal stability, partly due to the grain boundary ratio or the distribution of grain size, and partly derived from imperfections such as voids and microcracks while earlier processing techniques are known to result in incomplete dens:fication [11-12]. Therefore, the higher quality samples produced in subsequently years still show such a general trend."

Jan 1, 2011

By M. J. Collins

Pressure leaching of zinc sulphide concentrates has been practiced commercially for nearly two decades. The process, which includes direct leaching of concentrate with spent electrolyte in an autoclave, has been commercialized at four separate locations to date. In pilot studies carried out in the Dynatec lab in Fort Saskatchewan, dozens of additional zinc concentrates have been shown to be amenable to pressure leaching. This paper highlights recent improvements in zinc pressure leaching that have been identified through process development studies, and how the experience gained in these studies has been utilized in the development of a new copper pressure leach process.

Jan 1, 2000

By Maribel L- Saucedo-Muñoz, Toshiyuki Hashida, Victor M. Lopez-Hirata, Shin-Ichi Komazaki

"Small-punch tests were conducted at 4, 77 and 293 K on three types of austenitic stainless steels JNl, JJl and JK2, which were solution treated, water-quenched and then aged at 923, 973, 1023 and 1073 K for 5 h. Small-punch test energy was employed for the evaluation of the aginginduced embrittlement behavior in these materials. Fracture surface of small punch test specimen for the solution treated steels exhibited a ductile fracture, showing the highest SP test energy values. The presence of intergranular brittle fracture was observed in aged specimens. Smallpunch test energy decreased significantly as the aging process progressed. The highest and lowest decrease in small-punch test energy with aging temperature occurred in JNl and JK2 steels, respectively. The decrease in small-punch test energy showed to examine appropriately the aging-induced embrittlement in these materials. The difference in aging-induced embrittlement behavior for these steels was explained based on the volume fraction of intergranular precipitates in aged samples.IntroductionA high level combination of strength and toughness is required for cryogenic structural materials used in the superconducting magnets of fusion nuclear reactor. This requirement is beyond the capability of conventional austenitic stainless steels [1]. The Japan Atomic Energy Research Institute (JAERI) developed new cryogenic JNl, JJl and JK2 austenitic stainless steels. The structure of superconducting magnets is supposed to be constructed by welding thick plates of this kind of steels. Thus, most of the components are exposed to thermal cycles. The slow cooling may cause microstructure changes in both the base material and weld zone. These changes may also decrease the fracture toughness of these materials at cryogenic temperatures. Therefore, it is important to study the effect of thermal aging on fracture toughness behavior for these steels. Konosu et al. [2] carried out a study of the effect of thermal aging on the mechanical properties for JNl steel using tension and fatigue tests. Kwon et al. [3] evaluated the deterioration in fracture toughness at cryogenic temperatures for the isothermally aged JNl steel by means of the Small-Punch (SP) test. No other reports were found about the cryogenic fracture toughness behavior for this kind of steels. To evaluate the cryogenic fracture behavior, the elastic-plastic Jrc value is a good alternative [4,5]; nevertheless, the standard required specimen size makes it difficult to be used for the fracture toughness evaluation in small zones."

Jan 1, 2011

By E. R. Vance, D. R. M. Brew

"Historically, Ordinary Portland cement has been the preferred medium to immobilise arsenic. However, arsenic in cement gives rise to calcium-arsenic phases and their known decomposition to calcium carbonate and arsenic trioxide via atmospheric carbonation raises serious questions about the long-term suitability of cement for arsenic immobilisation. Alternative matrices such as low-temperature ceramics (LTCs) potentially offer superior resistance towards carbonation owing to the absence of calcium. Consequently, the potential for arsenic immobilisation using LTCs has been investigated. Both AsIII and AsV have been incorporated and samples assessed according to a standard leaching protocol. AsIII persists in the porewater of alkali-bonded LTCs as sodium arsenite rendering them unsuitable for immobilisation. Thermal treatment of these LTCs to consolidate the microstructure and reduce open porosity resulted in sodium-rich cryptocrystalline matrices that leached arsenic and sodium readily. The omission of sodium in acid-bonded LTC formulations resulted in leach data that were close to the target value of 5 µg/ml in Toxicity Characterisation Leaching Protocol tests.IntroductionArsenic is a carcinogenic substance and its adverse effects of on humans, flora and fauna have been well documented [1-5]. As a consequence, many papers have been written on the prospective handling of arsenic-bearing waste. These can largely be divided into: (a) cleanup of arsenic-contaminated water using bacteria, precipitation, and/or UV irradiation to generate arsenic-rich sludges for subsequent immobilisation; (b) cleanup of arsenic-contaminated soil via chemical extraction for immobilisation of the As concentrate; and (c) immobilisation of industrial waste contaminated with As."

Jan 1, 2008

By José Sancho, Julia Ayala, Purificación García, Begoña Fernández

"Electrofilter dust, a residue generated in the last stage of the Bayer process in the hydroxide aluminum calcination, was characterized to evaluate the alumina that was potentially extractable with sulfuric acid. The process studied aims to produce aluminum sulfate for water coagulant uses, taking advantage of the residues that accumulate in large quantities in the proximity of plants with difficult recycling for storage. Acid leaching is carried out at different concentrations of sulfuric acid, at different temperatures, pulp densities, and times, to dissolve gibbsite and transition aluminas. The result is an aluminum sulfate solution without iron and with commercial specifications.IntroductionElectrofilter dust is a residue generated in the last stage of the Bayer Process [1] in the hydroxide aluminium calcination. The residue is a mixture of alumina and hydrates which have not completed their calcination process.Electrofilter dust, composed by alpha alumina, gibbsite and transition aluminas [2] can be leached in an acid medium by putting most of the aluminium in solution; the remaining residue should be mainly andisolved alpha alumina. In many hydrometallurgical processes, sulphuric acid has been selected as the cheapest and the most effective leachant [3,4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]The aim of this study is to determine the effect of temperature, acid concentration and pulp density on the sulphuric acid leaching of electrofilter fines for aluminium dissolution, in order to produce aluminium sulphate for water coagulant uses. This will provide a commercial product and at the same time eliminate the environmental problem created as a result of the storage of large quantities of electrofilter fines in the vicinity of the Bayer plant."

Jan 1, 2008

By Hiroshi Ono

"By newly developed ICP method, trace amounts of As(III), As(V) .,Sb(III) and Sb(V) were precisely determined within accuracy of sub ng/ml. As(III) and Sb(III) were separated from As(V) and Sb(V) by extracting into ·xylene as diethyldithiocarbamate complexes using diethylammonium diethyldithiocarbamate (DDDC), and then back-extracted into nitric acid for a quantitative determiruition by ICP-AES equipped with hydridegeneration system The recoveries of As(III) and Sb(III) were satisfactory throughout the extraction with 0.04mol/l DDDC in xylene from lmol/l hydrochloric acid solution and the back-extraction with 7 mol/l nitric acid. As(V) and Sb(V) were reduced to As(III) and Sb(III) by ascorbic acid and potassium iodide, and their quantities were determined as mentioned above. The detection limits were found to be 0.58ng/ml for As(III), 0.63ng/ml for Sb(III) using 50ml of a sample. The proposed method was applied to analysis of the real sample.Introduction In drain, arsenic(AS) concentration is prescribed below 0.lmg/l, so As must be removed. As is existed at .the form of As(III) or As(V) in solution. For t1Jeir difference of chemic;µ property, it is not easy to remove As in solution. So it is an urgent necessity to develop for determining concentration of As(III) and As(V). Antimony( Sb) has resemblance .chemical property to As. So Sb was experimented the same as As.The separation and determination of As(III) and As(V) have been carried out using several methods, such as ICP after copreclpitating separation, HPLC, direct hydride generation atomic absorption. However these methods have some problems. One of main problems is that HPLC and direct hydride generation atomic absorption methods are influenced by coexisting elements."

Jan 1, 2000

By B. Q. Li, S. P. Song

"This paper describes an on-going research on developing coupled boundary element and finite element algorithms for the solution of thermal and electrodynamic problems relating to materials processing. The coupled methods are uniquely suitable for field problems involving composite regions, in which detailed information on field distributions within one particular region is of more interest and yet the solution can be obtained only if the effects of other regions are all considered. Problems of this type include heat transfer in multiple regions and also magnetic induction involving an infinite boundary. The hybrid boundary and finite element formulation, algorithm development and the applications are discussed. Two examples are given to demonstrate the capability and accuracy of the coupled algorithm for heat transfer problems. Various treatments of corner discontinuity are discussed. It is found that the double flux treatment is an ideal choice amongst those tested as it is easy to implement and also gives the most accurate solution. 1. INTRODUCTIONElectrodynamic and transport problems occur frequently in materials processing systems. Accurate solution of these problems is of great importance not only for our fundamental understanding of physical principles governing these phenomena in the processing systems but also for optimization of the existing processes as well as development of new processes. For this purpose, many numerical algorithms have been developed. These computational schemes in general can be classified into three categories, that is, the finite element and finite difference schemes and the boundary element scheme. The former two are domain based numerical algorithms while the latter the boundary-based algorithm.The finite element method, which is based on the variational calculus, is a very useful and yet popular engineering numerical method for boundary value problems defined over irregular boundaries. The use of the method requires the discretization of the entire domain. It can be applied to solve both linear and nonlinear problems, but is particularly powerful for nonlinear problems that involve the field variables defined within the computational domain. On the other hand, the boundary element method, with its root in the Green's function method, is very efficient for linear boundary value problems or nonlinear problems that involve field variables only along the boundaries. The primary advantage of the boundary element method lies in the fact that only the boundaries of the computational domain need to be discretized, and hence the dimension of the problem is reduced by one, compared with the finite element method."

Jan 1, 1994

By Nobuyuki Masuda

In Japan, the municipal solid waste, which amounts to 50 million tons, is generated every year and most of it is incinerated. The fly ash from the municipal waste incineration (the primary fly ash) contains heavy metals, such as lead and zinc, etc., and dioxins. In case of melting, the fly ash from the process (the secondary fly ash) contains high concentration of heavy metals (e.g., Zn; 1-20%, Pb, 1-10%). Metal Mining Agency of Japan launched a four-year project in 1999 to establish the integrated technologies to recover the valuable metals from, and to decontaminate, the primary and secondary fly-ashes in the practical scale by utilizing the existing metallurgical processes and facilities, along with the energy saving. The segregation, flotation and chemical treatment are applied to the treatment of the primary fly ash. The secondary fly ash is treated with MY (Mitsui-type blast furnace) Process after the chlorine removal to recover the heavy metals in the ash, In this paper, the segregation and flotation process for primary fly ash and MF process for secondary fly ash are explained. The main results of experiments done from 1999 to the mid of 2001 to design the pilot plants and to optimize the operating conditions are described. The main results of the experiments are as follows: - The segregation reaction of Cu was confirmed by the experiment on the treatment condition of 800 and 900`C with adding oil cokes and water to the primary fly ash, and 99.98% (toxicity equivalent) of the dioxins were decomposed by the treatment. - Washing tests of secondary fly ash to feed MF resulted that more than 70% of chloride were removed, but still lower than expected, and agglomeration tests were successful by the results of the sufficient strength of briquettes produced though a little more binder for the agglomeration is required than usual operation. - Smelting experiment by downsized MF showed that valuable metals, such as zinc and lead, are recoverable in the furnace dust. Recovery ratios, Zn: 58% and 67%, Pb: 74% and 83%, are accomplished.

Jan 1, 2002

By John B. Dale

A primary objective of copper mining, smelting and refining operations is the cost- effective, efficient, and environmentally-acceptable control of the level of various metal ions throughout the processing and effluent treatment flowsheets. Effective ionic control maximizes product and by-product quality, allows for broad flexibility in sourcing impurity laden ores, minimizes capital and operating costs, and can achieve zero discharge operations. In order to meet increasingly stringent cost, environmental and product quality requirements, separation technologies are needed that can selectively remove and recover deleterious or valuable ions. Ideally, the subsequently obtained salts or metals can be recycled in the process, disposed of in an environmentally acceptable manner, or sold as valuable by-products. The use of MRT, a highly selective separations technology, has been demonstrated to be a cost effective, efficient, and environmentally- sound treatment for a wide range of cations and anions that are commonly found in copper electrorefining and electrowinning circuits, as well as in environmental treatment operations. These include heavy and transition metals, precious metals, halides and alkali/alkaline earths. This paper will review a number of areas of interest including: recovery and refining of platinum group metals from copper anode slimes, recovery of copper from acid mine drainage streams, extraction of Bi, Sb and C1 from copper electrorefining and electrowinning circuits.

Jan 1, 1999

By KNona C. Liddell

"Many metal recovery processes involve heterogeneous reactions in porous media accompanied by fluid flow and mass transfer. Modeling such systems is difficult because of the number of rate processes involved and is complicated even further by effects due to the structure of the porous medium. Data on even bulk properties of the medium are often severely limited or unavailable. For many such systems, a cell model may provide an attractive alternative to models based on transport mechanisms in a differential volume. A cell model requires less input data and is computationally efficient. Identical residence time distributions can be obtained with models of both types, and both allow conversion and concentration profiles and histories to be calculated. The formulation and properties of cell models for metals recovery are described in detail.INTRODUCTIONSubsurface mineral leaching, metal ion recovery and environmental remediation are significant modeling challenges. They involve one-, two-, or three-dimensional reactive flow in multi reaction open systems. Dissolution, adsorption, and ion exchange occur at reactive mineral surfaces, and these heterogeneous reactions are accompanied by acid-base, complexation, and redox reactions in the solution phase.Two approaches have been taken to reactive flow problems in geologic media: mixing cell and transport models. Mixing cell models, the subject of this review, are based on a network of connected cells, each with a specified number of input and output streams. Mixing cells are assumed to have no internal solute concentration gradients, that is, each cell behaves like a well-stirred tank. Gradients are represented by step changes between connected cells; this results in a model that is spatially discretized at the outset. Different methods of discretizing the model equations are considered more fully below. Although this is not strictly necessary, it has usually been assumed in subsurface flow applications that all cells in the network have the same volume and identical initial properties."

Jan 1, 1996

By Milance Mitovski, Milorad Cirkovic, Vlastimir Trujic, Dragana Živkovic

"In this article, it is analysed the possibilitis and the effects utility waste energy of process sulfuric acid production in the existing technical-technological conditions. The utility second process energy, reduction the fuels consumption, reduction environment pollution and its effects are shown, too. High heat quantity is produced as the result of exothermal reactions in the production process of sulfuric acid in Bor. A part of this heat is sufficient for the process development, and significant part of this heat presents low-temperature heat energy that is irretrievable lost. Investigations were carried out based on production of 485 t of monohydrate/day of sulfuric acid. By recovery of this heat quantity for heating purposes, about 20.000 – 25.000 t of coal/year would be saved, what would significantly improve the power efficiency of the smelter copper production. IntroductionTechnological process of copper production in RTB BOR (Serbia) produces a significant quantities of high temperature secondary (waste) heat energy that is uncontrolled “lost” in the vicinity. Secondary heat energy is produced in pyrometallurgical copper production in quantity of 1,621 kWth/kg of dry concentrate or existing heat (that presents a difference of heat at furnace outlet and heat at temperature over temperature of dew point of sulphuric acid gases) in quantity of 1,315 kWth/kg of dry concentrate. For designed capacity of Copper Smelter in Bor, the existing heat power of secondary energy is 92,111 MWt, what is an equivalent to the power of steam-turbo plant where the Rankine-Clausius heating cycle is done, and that is 28,334 MWe."

Jan 1, 2008

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 Richard Jack De Klerk

The standard industrial method of arsenic removal from acidic aqueous processing effluents involves coprecipitation of arsenic with ferric iron (Fe/As>3) by lime neutralization in continuous circuits. To better understand current industrial practice, continuous circuit coprecipitation experiments were performed to identify industrially relevant process parameters and co-ion solutes that contribute to improved arsenic removal and retention. The coprecipitated solids were subjected to accelerated ageing at 20°, 40° & 70°C and arsenic behavior was monitored and modeled. Staging and the presence of calcium ions were found to have the most significant impact on arsenic retention. In this paper the techniques used and major results obtained are discussed.

Jan 1, 2008