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By I. Gaballah

High and low grade concentrates of tantalum and niobium oxides were obtained by leaching a medium grade tin slag. Chlorination and carbochlorinalion of these concentrates were studied between 200 and 1000 "C. Chlorination or carbochlorination of the low grade concentrate led, at 1000 OC, to the extraction of about 95 % of the tantalum and niobium oxides. However, the tantalum and niobium chlorinated compounds were contaminated by iron and manganese chlorides. Complete extraction of the niobium and tantalum pentoxide was achieved during the carbochlorination of the high grade concentrate at 300 and 500 "C, respectively. While chlorination of this concentrate at 1000 "C, allowed to the volatilization of about 60 and 80 % of Ta205 and Nb205. In both cases, condensates were composed of almost pure tantalum and niobium chlorinated compounds. The results demonstrate the advantages of the lixivialion based on the "pseudo- structure" of the raw tin slag to obtain the high grade concentrate. The conclusions of this work suggest that the carbochlorination of the high grade concentrate is an efficient process for the extraction of refractory elements from tin slag.

Jan 1, 1993

By R. D. Brittain

In order to analyze and control the transport of harmful trace-element impurities in various smelting processes, it is necessary to have fundamental information about the chemical thermodynamic properties of the pertinent condensed and vapor phases. This paper describes recent thermodynamic studies of the gaseous arsenic sulfides and of the activity of arsenic in a copper-iron sulfide matte phase. These studies were carried out by high temperature mass spectrometry and by effusion vaporization techniques, which permitted clear identification of the molecular species involved, a decided advantage in such complex systems. The nature of the results obtained and comparisons with previous interpretations will be described.

Jan 1, 1983

By Oscar Restrepo, Juan C. Nino, Henry A. Colorado

New and extraordinary physical-chemical properties of materials at nanoscale open up new applications for the building and infrastructure industry such as structural reinforcements, electronic properties and energy harvesting. Therefore the issues and risks associated with the manufacturing of nanomaterials are now of big concern due to the large volumes and typical processing involved in this industry. This paper presents a discussion and selected applications of nanotechnology in the construction and building materials: from metals and alloys, clay and minerals, ceramics, cement and concrete, asphalt, wood and composites, to finishing systems and some of the most used characterization techniques. Besides the progress in some areas, nanotechnology is just emerging in this field, with many challenges and opportunities, problems unsolved and business opportunities. A discussion regarding the potential health issues and risks of using nanomaterials for workers and the potential environment effects is included as well. New images and diagrams are presented and discussed.

Mar 1, 2018

By Yuanbo Zhang

Keywords: Complex Iron Ores, Roasting, Tin, Zinc, Pellets, Comprehensive Recovery. The complex iron ores containing tin, zinc are typical refractory ores. Large reserves of the ores are found in China and have not been utilized efficiently so far. A new process of tin and zinc recovery and pellet preparation from iron concentrate containing tin and zinc by controlled atmosphere roasting is developed in this investigation. The results of 2573 N/P compression strength of product pellets, the 91.49% and 82.22% volatilization of tin and zinc respectively, are achieved for a concentrate containing 0.39% tin and 0.28% zinc. The strength and chemical compositions of the pellets meet the requirement of blast furnace ironmaking. Volatilization mechanism of tin and zinc are investigated. Thermodynamic study shows that the reduction balance curves of SnO2(s) and SnO(g) are proximate in the presence of carbon, and the standard formation free enthalpy of FeO and SnO2 is also approachable. Therefore, it is difficult to realize the complete volatilization of tin in the form of SnO(g) by selective reduction. But SnO2(s) and SnO(g) will form SnCl4(g) or SnCl2(g) in the presence of chlorides and can be easily volatilized from the ores.

Jan 1, 2005

By Florian Kongoli

Non-ferrous smelting slags .can contain magnesia, which substantially increases the liquidus temperature. One option to counter this increase is to flux with calcia. In this work, experimental liquidus measurements including new measurements on industrial slags have been compared with a FACT-based thermodynamic model, which predicts the liquidus surface of multi-component iron silicate smelting slags containing both magnesia and calcia. The predictions, which agree well with experimental results, are summarized in both isothermal and non-isothermal diagrams to give a quantitative description of the liquidus surface.

Jan 1, 1998

By Victor Stancovski, Uday Pal, Stephen C. Britten

"An in situ electrochemical technique for measuring the concentrations of easily dissociable oxides in slags at temperatures between 1200-1600°C is being developed. The technique utilizes a partially-stabilized-zirconia solid electrolyte (PSZ), which conducts oxygen ions, to separate a reference-gas compartment from the slag of interest. Three types of measurements are currently under investigation which yield different information concerning the slag phase and hence will be combined into a single amperometric device for monitoring the properties of easily dissociable slags.Type I utilizes an open-circuit-voltage measurement between the reference gas and the slag phase. Type II utilizes a potentiostat to apply a direct current potential step or sweep between the inner and outer compartments of the electrolyte, driving oxygen ions from the slag into a reference gas. With the use of open-circuit-reference electrodes, the resulting current-potential profile reveals the dissociation potential and concentration profile of dissociable oxides such as those of iron, manganese, and chromium. Information on the transport properties of the cations can also be generated from these measurements. Type III utilizes a potentiostat with reference electrodes to carefully electrolyze a known volume of slag by removing large quantities of oxygen ions from the slag to the reference gas. The coulombs of charge removed at different applied potentials can be used as a direct indication of the concentration of each dissociable oxide species present within the slag."

Jan 1, 1997

By A. Dutta, B. Devulapalli, A. Mukhopadhyay, E. W. Grald

"Computational Fluid Dynamics (CFO) has matured over the past two decades as an analysis tool for conducting virtual experiments with significant time and cost savings. It complements and reduces physical testing. CFO has penetrated the diverse materials industry in much the same way as Computer Aided Design (CAD) did more than a decade ago. As the basic numerical algorithms used in CFO have steadily improved, so have the reliability, consistency and user-friendliness improved significantly, too. Other recent trends have also contributed to the rapid growth and widespread adoption of CFO. In this presentation, CFO applications from several materials processing industries will be presented using case studies. Emphasis will be on metals, glass and semiconductor applications.IntroductionThe term materials processing covers a diverse array of industrial applications and products today. From the continuous casting of steel, to the deposition of semiconductor materials atom by atom, to the extrusion of molten polymers, materials processing applications span an incredible range of length scale, process times, pressures, temperatures and velocities. The properties of the materials themselves, in terms of density, viscosity, thermal conductivity, etc., can be complex functions of temperature, shear rate, chemical composition and time. And the processing equipment may be very complicated in geometric shape.Computational fluid dynamics (CFD), the technique of solving the governing equations of fluid motion and other related phenomena using a computer, has enjoyed widespread and rapid growth, which started in the aerospace and automotive industries. More recently, CFD has also been successfully applied to a great many materials processing problems, in spite of the challenges described in the previous paragraph. The reasons for the growing usage of CFD in materials processing are many. Using CFD to test design options and reduce the number of physical prototypes can decrease the time and cost associated with new product and process development. CFD gives insight and provides detailed predictions of operating conditions in lieu of difficult, intrusive and often expensive experimental methods. CFD can be used as an aid to scale-up processes from lab or pilot scale to full production. Troubleshooting the performance of existing equipment is often carried out with the help of CFD. Determining how an existing piece of process equipment will operate under new conditions, or with new input ,materials, is also a common task for CFD."

Jan 1, 2004

Two pilot-plant investigations were conducted in which strong-base resins were compared with activated carbon for the extraction of gold cyanide from leached pulp from the Golden Jubilee Mine. The results show that gold can be recovered with carbon, but that the extraction efficiency is poor, probably because high concentrations of humic and fulvic acids are. present m the pulp. .However the extraction of gold cyamde from this material with strong-base resins JS very effo:1ent, and the overall efficiency of extraction is better with resin than with carbon, even when the concentration of resin is one-third that of carbon, and the flowrate of resin is one-third that of carbon. The results of the pilot-plant campaign reported in this paper led to the conversion of the Golden Jubilee plant from carbon-in-pulp to resin-in-pulp in February 1988.

Jan 1, 1989

By Ari JokiIaakso

Three different sulphidic raw materials were treated in a laboratory scale laminar flow fur-nace simulating suspension smelting conditions. The materials were a pure chalcopyrite concentrate, a high-antimony concentrate (tetrahedritic), and crushed copper mattes. The gas preheating temperatures were 500 -1 100°C ana the atmospheres ranged from N2 to N2 -75 % O2, Two particle size fractions were used for the concentrates with x = 20 -38 um and x = 62 -74 um, and three for the granulated copper mattes with x < 37 um, x = 62 -88 um, and x = 125 -177 um. Scanning electron microscopy combined with energy dispersive analysis and backscattered electron analysis was used for determining the morphology and the mineralogy of the reacted particles. Fragmentation of the particles were observed in all materials during the flash oxidation, the conditions depending on the iron and sulphur content and the original particle size fraction of the material. The melting and/or reaction stages of the particles in different conditions were studied from powder samples. Polished sections were examined in order to follow the development of porosity and the mineralogy of the particles.

Jan 1, 1989

By Rajesh K. Mishra

The person in charge of Environmental Affairs in a small business has many higher priority projects (such as making money to meet the employee? payroll etc.) than filling out and filing the regulatory forms. It is but. natural to think that these affairs can be managed? by playing ignorant until audited by the regulatory -state and federal agencies. Truth is to. the contrary; generally, it is too late by then. The fines and legal costs even for failing to file the regulatory forms could deliver a serious blow to the financial well-being of a small business. Forms and reports under SARA Title III are not hard to complete., but they are time consuming. In this paper we will discuss the information and data compilation procedures, simplification of some legal terminology into simple technical language, and tips that help in filling out the forms?. Some actual case &apos;histories of EPA fines will also be reviewed.

Jan 1, 1992

By Versiane Albis Leão

This work aims at the selection of an appropriate eluant for cyanide recycling using ion exchange resins. Based on a literature review as well as on experimental results, the elution of resins loaded with copper and minor amounts of iron and nickel is discussed. The resins Imac HP 555s, Amberlite IRA 900 (Rohm&Hass) and Purolite A860S (Purolite Co) were eluted using either NaCI, zinc and nickel cyanides, hydrochloric acid, sulfuric acid or acid thiourea solutions. The results indicate that saline solutions are effective only with polyacrylic resins (Purolite A860S), failing to desorb the metals, specially the nickel cyanocomplex, loaded on polystyrene-based resins. Cyanide solutions of both zinc and nickel are capable of eluting over 90% of the loaded metals. In contact with pure acid&apos; solutions, iron precipitates onto the resin beads, as Cu(II) ferrous cyanideCu2Fe(CN)6.xH20. Thiourea is able to elute all the three metal cyanocomplexes owing to the increased solubility of copper cyanocomplexes in the presence of this complexing agent. The results demonstrate that a universal eluant is not available and the selection of the most appropriate resin-elution procedure should be based on the specific features of the system under consideration

Jan 1, 1998

By William Petruk

The mineralogy of the primary and oxidized ores from the Malanjkhand porphyry copper deposit in India was studied to determine ore characteristics that affect metallurgy, and to assess applicable processes for recovering the copper. Three mineral assemblages were found. One occurs in primary ore, another in moderately oxidized ore, and a thir:d in intensely oxidized ore. Chalcopyrite, the main mineral in the primary ore, is relatively coarse-grained, with grain size increasing as the ore grade increases. High chalcopyrite liberations should be achieved at a relatively coarse grind, and good chalcopyrite recoveries should be obtained. The chalcopyrite, however, tarnishes readily and oXidizes to chalcocite in a relatively short time (several months). The presence of both the tarnished chalcopyrite and chalcocite may affect chalcopyrite flotation and reduce copper recoveries, The moderately oxidized ore occurs in an oxidized cap immediately above the primary ore, and stockpiled primary ore alters quickly to a moderately oxidized ore. Chalcocite is a major copper-bearing mineral in moderately OXidized ore. The concentrator processing this ore should be capable of handling a chalcocite-rich ore. The intensely OXidized ore contains a wide variety of acid-soluble copper-bearing minerals. Leaching may be required to recover the copper from them.

Jan 1, 1987

By W. L. Dalmijn

Glass recycling in the Netherlands &apos;has grown fr.om 10.000 to 300.000 tonnes per annum. The various advantages and problems of the glass cycle with reference to the state of the art in the Netherlands is given. Special attention is given to new technologies for the automated sorting of cullet with detection systems. In Western Europe the recycling of glass has, become a success story. Because of this, the percentage of ,glass cullet used in ,glass furnaces has increased. To meet the quality demands of the glass industry, automated sorting for the removal of stones, non-ferrous metals and other impurities ,had to be developed and incorporated in glass recycling plants. ;In Holland, Germany and other countries, the amount of glass collected has reached a level that colour-sorting becomes necessary to avoid market saturation with mixed cullet. Recently, two systems for colour-sorting have been developed and tested for the separation of bottles and culletin the size .range of 20 -50 mm. With the increased capacity of the new glass recycling plants, 120,000 -200,000 tpy, the quality systems have also to be improved and automated. These quality control systems are based on tile automated sorting technology developed earlier. for the glass recycling plants. The data obtained are automatically processed and printed. The sampling system and its relation to the theory of Gy will be described. Results of both developments in glass, recycling plants will be described.

Jan 1, 1995

By Veena Sahajwalla

The cupola furnace is a coke-fueled shaft furnace used as a primary melting unit in iron foundries. Control of chemical composition of the iron tapped from the cupola is a key factor in productivity and quality control. In an effort to develop a control model for the cupola, a fundamental approach based on physical and chemical principles has been taken to describe the melting process. The behavior of oxidation of the solid charge in the stack of the cupola has been studied. Sulfidation of the charge materials by sulfur-bearing components released to the furnace gases from the coke has been described. Carburization of metal droplets of iron and of steel in separate molten streams has been characterized. Finally, reactions with alloying elements in the hearth (well) of the furnace have been defined. These reactions have been described in a computer-implemented model developed to predict the composition of the iron tapped from the cupola. The model has utilized the thermodynamics and kinetics of the oxidation, sulfidation, and carburization reactions, including temperature and physical aspects, in the various zones of the melting unit. The model predictions have been compared favorably with operating results.

Jan 1, 1992

By Gernot Schenker

With the shut-down in the mid-1970s of the last shaft furnaces in the Harz Smelter Plant the long tradition of the Primary Lead Smelter in Oker came to an end. A continuation of the concern was nevertheless possible as a result of the timely commencement with the development and construction of lead production from secondary raw materials. Then as today, the most essential secondary raw material is lead accumulator scrap with over 80 % of the raw material pallet. Already in the 1960?s a method of reclamation lead battery scrap was developed and successfully carr.ied out by Preussag. In 1983 this process was fundamentally modified, also for environmental protection reasons within the framework of a rehabilitation programme of the existing plant. Today Metaleurop&apos;s HarzMetall GmbH in Oker is equipped with a modern secondary lead smelter which includes all environmental protection installations required by law. Besides processing battery scrap, the. smelter is in a position to process a ?multitude of other lead bearing residues in an economically useful way, whose waste disposal would otherwise be impossible due to the ever-increasing environmental protection laws or only be achieved at great expense.

Jan 1, 1990

By Wilson Acchar

The accelerated growth of urbanization processes and current environmental concerns brought to light the existing enormous quantity of construction and demolition waste (C&DW). Considering the frequent lack of adequate landfill areas available for the disposal of these materials, their use in the manufacture of ceramic products has been attracting a growing interest from researchers and is becoming common practice, with the consequent relief in public administration concerns for the C&DW appropriate management. This work describes the study of clay-based products added with C&DW collected directly from the construction industry. Samples containing up to 50 wt.% C&DW were uniaxially pressed and sintered in air in an electric furnace (950-1150 °C, 1 hour). Sintered test pieces were characterized by X-ray diffraction, apparent density, open porosity and flexural strength. The results showed that up to 50 wt.% C&DW can be added to the clay material, with no degradation in the final product properties.

Jan 1, 2009

By He De-wen

The municipal solid waste is a by-product of the daily life of urban residents. The quantity and ingredients of municipal solid waste has exceeded the current management and disposal ability, which has done a great harm to municipal environment and sanitation quality and threatened people?s health. On the basic of analysis on the amounts and main elements of municipal solid waste of Changsha City, the sanitation landfill, incineration, composting, reclamation and utilization technology of household waste were compared specifically in this paper. Based on the concrete conditions of Changsha City, the paper has proposed a disposal proposal combined with reclamation and landfill of municipal solid waste of Changsha City, and the environmental benefit, social benefit and economical benefit of the prepared processing routes were also analyzed in the paper.

Jan 1, 2009

By A. G. Merma

In this work, the electrocoagulation technique was studied in order to treat chemically stabilized concentrated oil-water emulsions. This study was mainly focused on the effects of operating parameters such as initial pH, current density, reaction time, electrode distance and inlet concentration on the separation of oil as measured by the chemical oxygen demand -1(COD) method. The synthetic emulsion was prepared from Shell - Talpa 30 oil (3g.L-1) and sodium dodecyl sulfate (1.0 g.L), having a Zeta potential around -70 mv at pH 8.7. The process was carried out in an electrocoagulation cell with a set of four parallel monopolar electrodes. This set consisted of two aluminum plate anodes and two 316L stainless steel plate cathodes. Kinetic curves showed that the electrocoagulation process exhibits three phases: (1) an initial phase, where the COD did not decrease because the solution had not reached the minimum amount of dissolved aluminum required to cause the break-up of the emulsion, (2) a reactive phase during which COD decreased due to possible agglomeration of the precipitates and (3) a steady-state phase where the COD did not change. The results showed that the period to reach the reactive phase decreased as the current density increased and the pH values decreased.

Jan 1, 2009

By Arthur E. Morris

Fifty years ago when Professor Yazawa began his career, the field of process simulation and modeling was in its infancy. Since then, tremendous progress has been made in our ability to model metal production flowsheets from mine to refined metal. This progress has come about by parallel developments in basic understanding of process chemistry and in computational techniques. This paper will review the progress made in process understanding and modeling in lead, zinc, and copper metallurgy from its inception to the present, and the role of Professor Yazawa&apos;s work in furthering this progress. Specific examples wi1\ be given for the sintering of lead concentrates, slag fuming, zinc concentrate roasting, flash smelting of copper, and pyro-extraction of zinc. Factors limiting further progress will be described.

Jan 1, 2003

By Z. R. Llanos

This paper presents a review of industrial and experimental processes for the recovery of molybdenum, vanadium, nickel, cobalt and aluminum from spent hydrotreating or hydrodesulfurization catalysts. Numerous processes have been developed in a laboratory and pilot scale. However, worldwide, there are only four well established commercial facilities currently in operation. The installed capacity of these facilities exceeds the availability of spent catalysts and may be sufficient to assimilate future increases of spent catalysts. Despite liability risks; significant quantities of spent catalysts are still being landfilled. Changing regulations that may affect the future handling and disposal of spent catalysts are also reviewed.

Jan 1, 1995