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By S-L. Jämsä-Jounela

Fault diagnosis systems have attracted growing interest in a number of engineering fields. The number of applications has increased and successful results have been widely reported. The fault diagnosis system presented in this paper is integrated, and it monitors the states of the process and performs fault detection and diagnosis on the process equipment. The monitoring of process states is carried out by means of Kohonen Self-Organising Maps that is a powerful tool in visualisation and analysis of high dimensional data in engineering applications. This paper presents the results of SOM analysis carried out on the Outokumpu flash smelting process. The subsystems analyzed in more detail are the condition of the concentrate burner, the condition of the gas line on the basis of the pressure distribution in the process and the cooling water circulation of the waste heat boiler, and the condition of the furnace and furnace equipment on the basis of the temperature distribution in the furnace and gas line. Keywords: Fault diagnosis, Process monitoring, Kohonen Self-Organising Maps, flash smelting

Jan 1, 2001

By Wantae Kim, Jaechun Lee, Tatsuya Oki, Sungbaek Cho, Sangbae Kim

"Effect of attrition scrubbing on the recovery of platinum group metals(PGMs) from automotive catalytic converter was discussed. The attrition scrubbing as comminution and separation process was effective for the recovery of the catalyst layer, ?-alumina, from ceramic supporting matrix, cordierite, by physical impact and shearing action between particles in the scrubbing vessel. The catalyst layer was dislodged from the surface of the supporting matrix into fine particles less than 45µm by attrition scrubbing. The production of fine fraction less than 45µm increased as the residence time for attrition scrubbing increased. The fine fraction obtained at the residence time of 40min contained 19.25% CeO2, 1.93% ZrO2 and 418.8ppp PGMs. The recovery of ?-alumina in the fine fraction increased as the residence time increased. Simultaneously, the recoveries of CeO2, ZrO2 and PGMs increased and reached up to 82.9% CeO2, 78.7% ZrO2 and 78.9% PGMs at the attrition scrubbing time of 40min. The production of the fine fraction and recovery of ?- alumina increased when the solid concentration and initial feed size increased.IntroductionThe automobile catalytic converters contain appreciable amount of PGMs. Currently several million tons of used catalytic converters are disposed annually worldwide, each containing about 0.5-1g of platinum and 1-2g of all PGMs1). The recovery technologies of PGMs from spent catalytic converters have been thoroughly reviewed by numerous researchers since last decades. Two types of methods, wet and dry processes, have been commercially operated. In the wet process, the PGMs on the spent catalytic converters were dissolved mostly in the form of chlorocomplex, MCl6 2-, by contacting with aqueous solutions. Subsequently the resulting solutions are treated to concentrate and the precious metal ions are reduced by introducing metals such as Al, Fe and Zn in the concentrated system2). In the dry process, the spent catalytic converters are melted, in some case with CaO, at an elevated temperature to produce a low viscous slag. The PGMs in the melt are separated by allowing them to adsorb on Fe or Cu having high specific gravity7). Although highly pure precious metals could be obtainable, the recovery technologies of PGMs currently operated seem not to be cost-effective since PGMs embedded in these types of catalytic converters are present in very small quantities."

Jan 1, 2008

By Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By Anette Mueller, Thomas Schnellert, Sérgio C. Angulo

"The use of automatically sorting technique, to separate gypsum components from recycled material of processed construction and demolition waste (C&DW), is motivated by environmental and economical aspects. Only if the gypsum can be separated the aggregates can fulfill the environmental requirements and also the structural characteristics according to the standards. Furthermore, the separation of red brick can also improve the quality of the aggregates.This paper aims at analyzing the separation of gypsum components and red brick by using the color sorting technique. The impacts on the composition and the envelope density of recycled aggregates are described. Depending on the gypsum content the application of two processing stages (rougher-cleaner) can be necessary to produce aggregates with sufficiently low gypsum content. Additionally, the separation of red brick and concrete is successful. So, the color sorting may be a promising technique to upgrade the quality of mixed C&DW aggregates.IntroductionConstruction and demolition waste (C&DW) is a mixture of different materials. Such mixtures can be used only in low grade applications. If the material is used as certified material for road construction or as aggregate in concrete the concrete particles must be separated from the other building materials. This paper aims at analyzing the separation of gypsum components and red brick by optical sorting. The needed stages of sorting for getting a product quality according to the German Standards are deduced.Gypsum is a building material that is increasingly used for interior works in Germany like it is shown in figure 1 [1]. At present the content of gypsum in C&DW is estimated at about 1 %. Assessments on the basis of material streams of gypsum and concrete and their life spans show that higher gypsum contents of about 3 % must be expected in future [2]. Also in other countries the use of gypsum has grown considerably in the last decades. From the characterization of C&DW available in some cities in Brazil, 4 to 15 % of total amount of C&DW that may arrive at the recycling plant to be processed is excessively contaminated by gypsum. In one of these cities, the average content of gypsum in the C&DW before processing was as high as 2.1 % [3]."

Jan 1, 2008

By Sun Ying, Zhang Jing, Li Qiuju

A new process of enrichment Cu in molten copper slag under electric field is presented in this article. The experiments were carried out in the laboratory on a kilogram scale. The mobility of copper slag was improved by the technique of carbon reduction. The effects of temperature, electric field strength and intermittent feeding speed were investigated on Cu migration. The results showed that the best experimental conditions were the temperature at 1523K, electric field strength was 1.5V•cm-1 and feeding rates was 15 g•(10min)-1. The copper content of the slag decreased below 0.6wt%. The process was compared to the traditional electric furnace process of slag cleaning, there was reduced the energy consumption and heat loss, and also harmful gas emissions such as SO2 and CO2, accompanied by improved the efficiency of slag cleaning.

Jan 1, 2016

By J. W. Lyman

Nickel-metal hydride (Ni-MH) battery electrodes have been developed as a substitute for cadmium-containing negative electrodes. Use of Ni-MH electrodes offers enhanced electrochemical properties in many instances as well as reduced environmental toxicity. Rechargeable batteries using Ni-MH electrodes are also strong candidates for electric vehicles. During the production and secondary reclamation of these battery types, recycling procedures will be needed to prevent environmental impact caused by these wastes as well as to recover the value inherent in the scrap. The U.S. Bureau of Mines (USBM) is investigating hydrometallurgical technology that separates and recovers purified metallic components from Ni-MH battery scrap of two types, AB, and AB,. An investigation of acid dissolution and metal recovery techniques has determined several processing alternatives that may be used to promote the successful recycling of much of the battery fabrication scrap and eventual secondary scrap. Although recovery techniques have been identified in principal, their applicability to mixed battery waste stream and economic attractiveness remain to be demonstrated.

Jan 1, 1995

By Xirneng Zhu

The electrochemical behavior of Pittsburgh and Illinois coal pyrite in basic and neutral borate/sulfate solutions was investigated. In the transpassive region, aggressive oxidation of pyrite occurred. The reaction products in this region were Fe(III) oxide, sulfate ion and partially oxidized sulfur intermediates. The formation of sulfur and polysulfides was identified by in-situ Raman spectroscopy. The growth kinetics of the reaction product film, resulting from transpassive oxidation of coal pyrites, were studied using chronoamperometry measurement with both stationary and rotating disk electrodes. The reaction rate was well correlated by a paralinear rate equation. The effects of electrode rotation speed, solution pH and temperature were examined. The kinetics were compared to those for mineral pyrite.

Jan 1, 1994

By Juan Patricio Ibáñez

Separation of arsenic and copper from Cu-As-H2S04 electrolytes by electrodialysis has been investigated at room temperature. The effects of current density and pH were studied. An arsenic-free copper solution was obtained for all the tested conditions. The transport efficiency for copper ions was found to be higher than 98% after 3 hours' test. Transport of arsenic and copper through the ion exchange membranes was increased by increasing pH and current density. Solution pH was found to be a key parameter for the separation process, since it controls the speciation of the ions to be transported and the formation of unwanted precipitates which reduce the global efficiency of the electrodialysis process. The main conclusion is that electrodialysis is a promising technique to be used in separating and/or concentrating ions of interest in copper electrometallurgy.

Jan 1, 2003

By Alex Luyima, Honglan Shi, Lifeng Zhang, Yongqing Jiang

"Leaching process has been suggested to recover most metals from waste PWBs. In this study, the leaching behavior of most metals present in waste PWBs is evaluated before and thermal treatment. Different leaching acids: hydrochloric acid (HCl), nitric acid (HNO3) and aqua regia are compared. The effects of acid concentration, particle size of sample, leaching time and temperature are examined. Results revealed that most metals are present in small particle size and sequential leaching of PWBs with a combination of HCl acid and aqua regia is capable of dissolving most of the metals content of PWBs. Leaching of thermally treated PWBs produced the highest leaching percentages for similar leaching conditions.IntroductionApproximately 20–50 million tonnes of electronic waste (e-waste) is produced globally per year. Waste Electrical and Electronic Equipment (WEEE) or E-waste is one of the fastest growing waste streams in the world. In developed countries, it equals 1% of total solid waste on an average [1]. The growing stockpile of used and obsolete consumer electronics has been called the “largest toxic waste problem of the 21st century [2]. Printed wiring boards (PWBs) is an essential part of almost all WEEE, and accounts approximately 3% of all WEEE by weight [3]. PWBs are a platform upon which microelectronic components are mounted. PWBs contain metals (~40 wt. %), ceramics (~30 wt. %) and plastics (~30 wt. %) [4]. The metallic part includes; Cu, Pb, Zn, Fe, Cd, Be, Cr, Au, Pt, Pd, Ag, etc. The plastic part of the PWBs is mostly epoxy resins. These plastic resins also contain very toxic halogenated flame retardants (HFRs) [5]."

Jan 1, 2012

By Caisa Samuelsson

Experimental studies in laboratory-scale equipment have been carried out to study the vaporisation from dust generated during the copper converting process. In the present work the vaporisation of Zn, Pb, As, Sb, and Bi from a dust collected in the electrostatic precipitator after the copper converter were studied. The results show that Pb, Bi and As were vaporised to a high degree from the dust at a temperature above 900°C in a gas containing N2, SO2 and a small amount of H2. The vaporisation was high for these elements also in a gas containing N2, SO2 and 02 at temperatures above 1120°C. In an earlier study, thermodynamic calculations showed that it is possible to selectively condense metals at high temperature' in a gas atmosphere generated during a copper converting process. The present study was carried out to verify the thermodynamic model. The results indicate that it should be possible for a selective condensation of Zn at high temperature. The temperature required for a selective condensation of Zn is dependent upon the gas atmosphere, e.g., the oxygen potential.

Jan 1, 1998

By I. G. L. Sinclair

The Selbaie deposit is located in northern Quebec. It is comprised of three distinct, but genetically related, Cu-Zn-Ag ore bodies which also contain economically significant amounts of Au. The deposits are Archean in age and volcanogenic in origin. At Selbaie, ore microscopy has been employed to aid in planning of ore beneficiation methods and to monitor the ongoing performance of the concentrator. Examples of both types of study are described. Early in the life of the mine, excessive amounts of Zn appearing were found to be appearing in the Cu concentrate. Microscopic examination of concentrates showed that this was being caused by the presence of coatings of supergene chalcocite on sphalerite grains. Fine coatings of supergene galena and chalcopyrite were also observed on some sphalerite grains. The presence of Ag and Au in the ores makes an important contribution to the revenue of the mine. The various modes of occurrence and mineralogical relationship of these two metals are described and discussed. Monitoring of the ongoing concentrating process at selbaie is done by qua-litative and quantitative examination of products collected at various points along the circuit. Causes of such problems as excessive loss of metals to the tailings or inefficient recovery of individual metals, can often be identified and possible solutions proposed.

Jan 1, 1989

By Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By Giulio R. Altoé, Sergio N. Monteiro, Ygor M. Moraes, Rômulo L. Loyola, Frederico M. Margem, Gabriel O. Glória

The tensile properties of DGEBA/TETA epoxy matrix composites reinforced with different amounts of PALF fibers were evaluated. Composites reinforced with up to 30% in volume of long, continuous and aligned PALF fibers were tested in an Instron machine at room temperature. The fracture was analyzed by SEM. This one revealed a weak fiber/matrix interface, which could be responsible for the performance of some properties. The results showed significant changes in the mechanical properties with the amount of PALF fibers.

Jan 1, 2015

By H. Y. Sohn, M. K. McCarter, Bradley C. Paul

"A computer model was constructed for bacterial leaching of the major sulfides found in porphyry deposits, including bornite, chalcocite, chalcopyrite, covellite, cubanite, enargite, native copper, pyrite, and pyrrhotite. The model incorporates equations for the sulfide minerals dispersed in the rock matrix. Leaching occurs by reactions with ferric ion diffusing into the rock fragment: Ferrous ion is resenerated to ferric with oxygen by bacteria at a temperature dependent rate. The model keeps track of the net acid generated, oxygen consumed by the bacterial oxidation of ferrous ion, heat generated, jarosite and hematite precipitated, and copper leached. The model was used to predict the rate of copper recovery, heat generation and oxygen demand for a variety of run-of-mine sized porphyry ores. These results were used in the design of a ventilation system and the economic analysis of a modified in situ extraction method that may be cost competitive with conventional copper production involving open pit mining.IntroductionA study was undertaken at the University of Utah to evaluate the technological and economic feasibility of mining copper by a method referred to as Flood Drain Leach Cell (FDLC) mining. Cells 60 by 75 meters in plan and 70 meters in height are created throughout the ore body by a modified Vertical Retreat Mining technique that includes the removal of 25% swell material. The swell material is leached in finger dumps on the surface while the cells underground are bulkheaded, flooded, drained, and artificially aerated to promote bacterial ferric sulfate leaching. Solutions are cycled through several cells to reach pregnant grade of 1 gram copper per liter of solution. These solutions are then fed to an underground solvent extraction plant and then a surface electrowinning tankhouse."

Jan 1, 1988

By E. T. White, Dean Ilievski

"The population balance is one of the basic relations for analysing particulate mineral processing operations. It is an exact relation. The principles of the population balance are reviewed and applications in the minerals industry discussed.IntroductionMathematical modelling has proved to be a very successful approach for improving the design and performance of mineral processes, particularly since the availability of computers to handle the complexity usually necessary to give a useful model.Mineral processes almost invariably involve particles, as either solid fragments, liquid drops or bubbles. Process performance usually is highly dependent on the behaviour of these particles. In modelling particle behaviour, the basic relation to be used is the population balance. This paper discusses the role of the population balance and the range of its applications in minerals processing.The Population BalanceThe population balance was developed for demographic studies, ego predicting the change in the population (numbers) of, say, school children between one census and the next. The first sustained application to the processing industries appears in the 1960s for crystallization. However it was recognised almost immediately that it had application to all particulate processing."

Jan 1, 1996

By Du Sichen, S. Seetharaman, Wei Liu

"The viscosities of two-phase mixtures are of great importance in the modelling of the fluid flow in metallurgical processes. For example, in steel making and refining, the intimate mixing of metal droplets in the slag phase requires a consideration of the effective viscosities for the mixture. The present work was aimed at an understanding the phenomena underlying the viscous flow in a two-phase mixture with widely differing viscosities.Emulsions of silicone oils of known viscosities (345mPa.S and 1010mPa.S at 293K) with small amounts of water evenly distributed in the same were prepared by subjecting the mixture to uniform stirring using a magnetic stirrer. The viscosities of these emulsions were measured at constant temperature by rotating cylinder method using Brookfield Digital Rheometer. The uniformity of the preparation of the emulsions was confirmed by the reproducibility of the results. Th7 measured viscosities were generally found to be independent of the torque under the experimental conditions so that the two-phase mixture could be considered as a Newtonian liquid. The variation of viscosities with temperature and the effect of addition of a surface-active substance were also studied in this work.The measured viscosities were found to be· higher than those of both pure water and silicone oil. The experimental viscosities were found to increase with increasing concentration of water. The influence of surface tension on the viscosities was examined by adding surfaceactive agent to the mixtures. The result is discussed and compared with theoretical models developed by Einstein, Taylor and Oldroyd."

Jan 1, 2000

By Thomas M. Harris

Cation exchange is not sufficiently selective to be used for the removal of heavy metal ions from a general industrial wastewater. However, if the metals can be converted to polyvalent anions through complexation, they may be removed both selectively and efficiently by anion exchange. This approach, referred to as chelation-assisted anion exchange (CAAE), has been examined using industrial wastewater samples contaminated with Ni2+ and Cr3+. For this particular application, the Ni2+ is complexed with 8-hydroxyquinoline-5-sulfonic acid, and the Cr3+ with sulfosalicylic acid. Removal efficiencies and adsorption isotherms for both the complexants and the complexes were determined in batch-mode tests.

Jan 1, 1994

By Bing Li, Miao Shen, Qiang Wang, Yuqi Chen

Electrochemical methods including cyclic voltammograms, square wave voltammograms, chronopotentiometry are applied to characterize the reduction potentials of Na+ and Li+ ions in LiCl-KCl melts. According to theoretical calculation, the reduction potential for Na+ is slightly more negative than Li+ in NaCl-LiCl-KCl melts at 450℃. However, by electrochemical measurements, the reduction potential of Na+ is slightly more positive than Li+ in the above melt and the potential difference between Na+ and Li+ reaches 0.16-0.2V on an inert W electrode in 1.0-2.0 wt% NaCl-LiCl-KCl melts. An active Pb electrode is used to improve the removal rate of Na+ from LiCl-KCl melts. The reduction potentials for both Na+ ions and Li+ ions on a Pb electrode shift to more positive values and the reduction currents become larger. After 6h electrolysis on a Pb electrode at -3.0V, the practical removal efficiency of Na+ ions reaches 90.12% and the reduced products contain metallic Na and Li with a Na/Li mass ratio of 4.25/1.

Jan 1, 2015