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By M. Rockandel

"Universal Dynamics Ltd. of Vancouver, Canada has developed, patented and commercialized the ""REMERC"" process for the treatment of mercury contaminated sludges and soils. Mercury is extracted into an acidified and oxidizing, sodium chloride brine solution. REMERC was initially developed to treat mercury contaminated EPA listed wastes (K106) generated by the chlor-alkali industry. More recent work has expanded the capability;' of REMERC to include remediation of mercury contaminated sites, equipment and building materials.In the process mercury is currently recovered from solution by cementation on iron powder in an agitated reactor. The process recovers high purity elemental mercury (99.9% purity). Cementation typically recovers about 90-95% of the mercury in 30 minutes. Higher recovery is not necessary because of the recirculation of the leach solution. When treating highly contaminated chloralkali wastes (5-13% mercury content), REMERC will reduce the mercury laden solutions from 400-1,000 mg/L mercury to 50-100 mg/L. In the treatment of less concentrated wastes «1,000 mg/kg mercury) such as those encountered in site remediation, the treated solutions will generally contain 10-20 mg/L mercury. Cementation while being simple and able to achieve the required recovery has the. undesirable properties of; requiring a solid-liquid separation and adding iron to solution which must be precipitated, ultimately increasing the weight of residue to landfill. .The potential advantages of electrolysis were recognized early in the development of REMERC. Mercury electrolysis is well known in gold and chloralkali processing. Initial testwork utilized a liquid mercury cathode and a coated titanium anode both common to chloralkali producers. The mercury cathode appeared susceptible to polarization and solution impurities significantly affected performance. Agitation of the mercury pool improved performance but it was still not possible to achieve the reduction objectives. Current efficiencies were low, near 10%, and it was apparent that a relatively large cathode pool would be required to limit the current density. A number of electrode combinations with and without a membrane were then tested in a vertical electrode' configuration but the desired performance was not obtained."

Jan 1, 1997

By Mark Samonds

"Manufacturing processes which involve liquid to solid and solid state transformations in metals encompass a wide variety of physical phenomena. The past twenty years have seen a steady evolution in the complexity and scope of numerical models of these processes, beginning with thermal analyses without phase change. Recently, a few software packages have become available which have true multi-physics capabilities. This permits the treatment of thermal, fluids, stress, electromagnetic, chemical reaction and microstructure development aspects altogether in a fully coupled simulation. This paper will consider various aspects of these types of models.Coupled thermal and fluid flow analyses of continuous castings have been around for fifteen years. Coupled thermal and free surface fluid flow simulations of shape castings have been available for ten years, including view factor radiation models for investment castings. Only recently, however, have fully coupled thermal, fluid, and stress analyses become practical. This implies the reverse coupling of the mechanical deformations to the solution of the energy and momentum equations through modification to the interface heat transfer coefficients and the fluid domain geometry. This has been implemented with a combined eulerian-lagrangian finite element method. Appropriate mechanical constitutive models will also be discussed.Many types of defects need to be predicted in casting processes. Those related to stress include hot tearing, hot cracking, part distortion, and thermal fatigue in dies. Macroporosity, microporosity, and microsegregation are determined by the solidification behavior and microstructure development in a casting. In particular, microporosity is influenced by dissolved gases, the morphology of the mushy zone, the liquid to solid density change, and the local pressure conditions. Macrosegregation is caused by the partitioning of solutes during. solidification and subsequent thermo-solutal convection. An additional transport equation is required for each solute that is being tracked. Computational thermodynamics is being incorporated into these types of analyses to determine transformation temperatures, partition coefficients, densities, and enthalpies. In combination, the microstructure and microporosity models can frequently predict a variety of mechanical models, such as yield strength, tensile strength, and elongation."

Jan 1, 2001

By Toshiyuki Hiranami, Keizou Uematsu

"AbstractionSpray freeze drying method was proposed to fabricate ·ceramic: powder granules for high performance ceramics. Obtained granules and their green compact were characterized by SEM and immersion liquid technique. Granules have a spherical shape of about l 00 µ m in diameter, ·and no binder segregation was found with the immersion liquid technique. The granule had sufficient strength for usual handling, while the strength was much lower than that of granules prepared by conventional spray-drying. Unlike the conventional green compacts, granule interfaces were not observed in the green body made with the spray-freeze dried granules.IntroductionIt was well kn9wn that spray-dried granules have binder segregation layer on their surfaces. The trace of this segregation layer survives in the later processes i.e. compaction and firing, and behaves as fracture origins in the sintered bodies. The origin of this problem is solvent drying process from slurry droplet surface in spray drying system. As alternative method we propose a freeze drying process for granule preparation, in which solvent is remove by sublimation though the process, binder segregation can be prevent.In this study, we applied spray freeze drying method to fabricate alumina powder granule, and characterized the obtained granules, and their green compacts and sintered bodies.Experimental procedure.Alumina powders and additives aqueous solution were mixed for 24 hours using a ball mill to· prepare the slurry for spray freeze drying. .The solid loading of the slurry was 30vo1%. Deflocculant (PAA-NH4 type) was added 0.5mass%, and the binder (PVA). 1.0, 2.0 or 3.0mass% of alumina. Obtained slurries were sprayed into liquid nitrogen to make frozen granules. The granules were freeze dried.For the characterization of the granules, immersion, liquid technique observation and single granule strength test were carried out. Strength of individual granule wa5 measured using micro compression testing machine (MCTM, SHIMADZU). Granule strength was calculated from following equation."

Jan 1, 2000

Off-gas cleaning from metallurgical plants requires? in many cases very low dust contents which are difficult to achieve with conventional scrubbers, even with high energy input. Lur.gi has developed a scrubber which improves the separation of the fine dust by electrical charge prior to. the scrubbing zone. An Electrostatic Scrubber has been successfully installed for the off-gas cleaning from slag' granulation after a waelzkiln achieving less than 1 mg/m3 in the clean gas.

Jan 1, 1992

By Yuuki Hagio, Hiroyuki Tobo, Michihiro Kuwayama, Yasutaka Ta

"Reduction of CO2 emission is necessary to remedy global warming, however, promising approaches of CO2 separation require a large amount of energy. Molten slag, which is generated as by-product of steel production, has high temperature, but its energy has not been harnessed. To recover the thermal energy from the slag and to apply to separation of CO2 are economical and environmental conscious ways. We propose a new heat recovery system, in which, molten slag is solidified continuously on water-cooled roll and the solidified slag plates are charged into counter-current heat recovery equipment. In laboratory scale experiments, heat recovery ratio of more than 30% was acchived by controlling the thickness of slag.IntroductionThe steel industry in Japan has been working on the projects of ""Environmentally Harmonized Steelmaking Process Technology Development (COURSE50)"". COURSE50 aims at developing technologies to reduce CO2 emissions by approximately 30%. One of the main technologies is to capture and recover CO2 from blast furnace gas using chemical absorbents to regenerate CO2-laden chemical absorbents by separating CO2 from the absorbents. As one of the solutions, JFE Steel Corporation has been developing sensible heat recovery process from steelmaking slag. It is effective to recover and use unutilized high temperature waste heat within a steel plant as the thermal energy required."

Jan 1, 2012

By Nozomu Uchida, Uematsu Keizo, Daisuke Shouji

"Grain orientated microstructure was developed for the improvement of ceramic characteristics. Novel polarized light microscopy was developed to examine the grain orientation quantitatively. The degree of grain orientation was estimated from the retardation determined with a Berek compensator. The method was essential to determine a minor grain orientation, which could not be analyzed by means of conventional X-ray measurements. The data were favorably related to ceramics characteristics. The comparis of the ceramics with various degree of orientation was very important to explain the change of ceramic characteristics with processing.IntroductionMicrostructure with grain orientation has a high potential for greatly improving characteristics of ceramic. However, there has been strong restriction on processing and material for developing this structure. It has been crucial to apply forming methods involving high shear such as injection molding1). Grains must have an elongated shape.In recent years, much attention has been paid on the effect of high magnetic field on diamagnetic materials2)3)4), Many ceramic materials are known to be diamagnetic. High magnetic field has a high potential to orient grains. The principal driving force for grain orientation is the magnetic anisotropy of material, which is generated by non-cubic crystal symmetr5). This method of grain orientation is not restricted by grain shape, and can be applied to all materials having non-cubic crystal structure.This study uses alumina as raw materials, and produces alumina ceramics with orientated grain in high magnetic field (10T). Alumina has a magnetic anisotropy due to hexagonal crystal structure. The degree of grain orientation in the green and sintered bodies will be examined and their relevance to magnetic field will be discussed."

Jan 1, 2000

By Irina V. Sokol

Alloyed steel chips and swarf formed during metal processing are looked upon as additional raw material In metallurgycal production. The manuscript presents some new methods for steel waste chips and swarf cleaning. One of them Is swarf and steel chips cleaning In ethylene tetrachloride with ultrasonic assistance and following, solvent regeneration. Thermal cleaning of waste chips and swarf provides exit gas products utilization. Catalyst Influence of metal surface on the process of thermal decomposition of liquid hydrocarbons during cleaning process has been studied. It has been our experience that the efficiency of metal waste cleaning technique depends on the storage time of the swarf. Waste chips and swarf cleaning procedures presented in the manuscript have been proved economically advantageous and environmentally appropriate.

Jan 1, 1995

By James M. Lockwood

"Eureka Technology has developed and patented a technology for the recycling of EAFD. Through this process all constituents of the material become salable commodities or are returned to the steel making process. In transforming the EAFD ""waste"" stream into a ""process"" stream the Steelmaker eliminates potential liabilities and the uncertain future of current processes while further reinforcing its role as a recycler. This is a cost-effective and energy efficient technology that combines hydrometallurgic and electrolytic processes resulting in the recovery of salable metals. For instance, unlike pyrometallurgic processes, zinc is recovered in metallic form and no elements are volatilized. This on-site operation also eliminates expensive transportation costs. In summary this technology reduces the cost of dealing with EAFD by recycling material currently being landfilled.IntroductionWorld crude steel production reached a new record level in 2007 - 1.34 billion tons of which 31% was produced by EAF steel makers [1]. This resulted in the generation of over 6 million tons of EAFD. This steel byproduct contains significant amounts of lead, cadmium and other hazardous metals. In the United States the Environmental Protection Agency (EPA) has designated EAFD a hazardous waste (EPA waste code K061). With over 50% of steel production in the US coming from EAF steel making this byproduct represents the single largest source of solid hazardous waste generated."

Jan 1, 2008

By T. J. White

A synthetic Mineral Immobilization Technology (SMITE) has been developed for stabilizing municipal and hazardous waste incinerator ash. Tailored additives are introduced to the ash in a' first stage that pre-stabilizes all the toxic metal components in non-volatile forms. and in a second pyrometallurgical stage, these are converted to insoluble mineral analogues. It has been found that a combination of apatitie. spinal, anhydrite and monazite can immobilize all the ash components at high waste loading and high density. Typically the stabilized products contain in excess of 50 wt% ash and have densities of 2.5- 3.0 g.cc-1. Toxicity Characteristic Leach Procedure (TCLP) testing has demonstrated that the products well satisfy regulatory requirements. The cost of production and disposal of SMITE waste forms in 2-5 less expensive than. convential methods of solidification/stabilization. This paper will describe the principles of SMITE design for ash stabilization, outline the fabrication procedure, and present comprehensive microstructural and chemical data to validate waste form performance.

Jan 1, 1996

By LeRoy C. Prichard

The scrap based steel producers in the United States generate an estimated 650,000 tons of electric arc furnace (EAF) dust annually which is classified as hazardous waste, K061. These scrap based producers commonly referred to as mini-mills represented 39% of the steel produced in 1994. Based upon the EAF plants being installed or planned today, it is a reasonable projection to anticipate 50% of the steel produced in the United States will be by EAF's. Using a straight line projection of percent of steel produced to tonnage of EAF dust generated, this will result in 833,000 tons of dust being generated upon the completion of these new EAF producing plants, presumably by the year 2000. Because the United States is a capitalistic economy, a steel producer is in business to make a profit therefore dust management becomes a very important variable in the cost of making steel. An EAF mini-mill dust management program must consider at least three components. First the handling of the dust must be in accordance with the law; i.e., the Environmental Protection Agency rules and state and local municipalities guidelines governing K061. Second, it must be an economical solution that allows a company to manage its dust processing costs, a component of its total steel production costs while producing steel at a profit. Third, the dust management program should be one that is environmentally responsible; viz., the program should reclaim or recycle the dust constituents, as feedstock materials or saleable products. The first component, obedience of the law seems to be a relatively straight forward, common sense objective; however, as nearly every mini-mill operation will testify it has been a area of changing laws with confusing variations when it comes to K061. Even more frustrating is the fact that obedience or compliance today does not mean that the company will be considered law abiding in the future.The liabilities associated with

Jan 1, 1995

By Z. Zhang, Zongshu Zou, Nan Wang

"Thermodynamic calculation is applied to make an investigation on the equilibrium phase relations and liquids of CaO-SiO2-Al2O3-FeOx system for different temperatures. The calculated results with FactSage6.1 show that the effect of temperature on the the equilibrium phase relations and liquidus of CaO-SiO2-Al2O3-FeOx system and its sub-systems is appreciable. The liquid phase regions enlarge with increasing temperature from 1573K to 1873K, while the primary phase fields reduce distinctly.IntroductionThe main oxide components of vitrified bottom ash slag are CaO, Al2O3, SiO2, Fe2O3, MgO, and Na2O, accounting for more than 90% of the bottom ash by weight[1]. During slag processing, the knowledge of thermodynamic properties and liquidus temperature in the related slag systems is highly required [2, 3], which is not yet available. Through literature survey [4-6], it is clear that the systematic information on the concerned complex slag system is scarce. So far the engineers in the field have to make assumptions of the thermodynamic properties of the simplified oxide system, without taking into consideration the interactions of the different oxide components, which hinders the development of the slag valorization and utilization. In order to provide thermodynamic properties for the application of the vitrified bottom ash, the six-component oxide system (CaO-MgO-Al2O3-SiO2-FeOx-Na2O) is highly required. A preliminary phase diagram of the CaO-MgO-Al2O3-SiO2-FeOx-Na2O system can be obtained from extrapolation of the thermodynamic functions of constituent subsystems such as CaO-SiO2-FeOx-MgO, CaO-SiO2-FeOx-Al2O3, CaO-SiO2-Na2O-MgO and CaO-SiO2-Na2O-Al2O3. In this work, the equilibrium phase relation and liquidus of CaO-SiO2-FeOx-Al2O3 system, one subsystem of the concerned complex slag system, are calculated and the effect of temperature is also discussed."

Jan 1, 2012

By Vadim J. Jabotinski

This paper describes several areas of application for electron beam processing of materials. The technology and use of electron beam systems in gas phase synthesis reactions are described. Gas phase reactions may be used to generate ultra- fine metal or ceramic powder that are very pure and crystalline. Among the examples presented are: the generation of nanometer sized metal powders and the gas phase synthesis of silicon carbide for silica and methane. The experimental system is described and future theoretical and experimental objectives are identified.

Jan 1, 1998

By Pedro Morales

At present the Codelco´s smelter & refinery business have growing complexities, concentrates with lower copper grades, higher impurities contents, and environmental restrictions which have lead to refocus the Codelco business, not only by considering the isolated developments for each of the Codelco´s Smelt & Ref complexes, but also as an integrated corporative complex scheme which improve the economy of scale, optimize the synergies, and include new technologies for higher productivity and lower operational costs. Accordingly, for the 2008-2012 period, Codelco have prepared a Development Plan integrated to the smelters and refineries business units that improve its single potentialities of and include the advances for the Teniente Converter [1] and Continuous Converting [2] Technologies, and also include the concept of uncoupling the smelting process from the converting process allowing a higher operational flexibility, and a better control of its contaminants. Thus, processing the white metal generated in the Teniente Converter unit of the smelter A into the smelter B has comparative advantages. These changes in the business concept allow an overall increment of the smelting capacity by processing only white metal as a final product through a very marginal investment in this way the total or partial conversion of the white metal into blister copper is eliminated allowing to use the available gas capture-treating capacity, and available acid plants for increase smelting capacity as well.

Jan 1, 2006

By J. C. Agarwal

Most metals are produced from minerals containing one or more of the desired metals, some contaminating metals, silicate, oxides, carbonates, and sulfides. Therefore, in the production of metals, there is generally a gaseous effluent in pyrometallurgical processes and a liquid effluent in hydrometallurgical processes. There are also solid residues such as waste ore, tailings, dust, and slag, created by the metal recovery processes. There are two important distinctions between the effluents and the residues: I. Effluents ? gases and liquids ? affect the neighboring environment for miles from the point of emission, while residues affect only the soil on which they are stored or dumped. 2. The environmental and economic effects of effluents are known and felt essentially immediately. By contrast, the environmental effects of the residues may not be known for a long time. For these reasons, the economic impact and the potential corrective actions required are very different for effluents and residues.

Jan 1, 1992

By Halvor Dalaker, Alain Marc Ferber, Thor Anders Aarhaug, Pål Tetlie

Off-gas monitoring of experimental reactors give little information about intermediate reaction products and reflect chemical equilibria at reduced gas temperatures. A reactor design with optical access was designed and tested in order to be able to qualify and quantify gaseous species from their emission spectra. By use of a sequence of sapphire, UV fused silica and IR transparent sapphire and CaF2 windows and lenses optical access to a hot, maximum 1800 °C, reaction zone was gained. A cooled area behind the reaction zone was used as a background in order to avoid signal saturation from reactor walls. In addition to molecular emission spectra, atomic emission lines are used to characterize stable gas constituents and radicals. The setup has been designed for the study of methane dehydrogenation experiments in order to investigate the carbon activity of reduction of oxide with methane, but has also been used to monitor gaseous silicon suboxide.

Jan 1, 2015

By Ronald K. Riddle

The processing of lateritic ores in rotary drying and preheating/pre-reduction systems has historically been plagued by problems associated with significant dust generation. These problems include handling issues, kiln capacity limitations, negative impacts on furnace stability, a reduction in nickel recovery and higher operating costs. The dust is formed in the rotary devices during heating and tumbling due to the following three mechanisms: (I) mechanical dccrepitation of the ore as a result of tumbling and attrition, (2) thermal decrepitation during rapid vaporization of internal free and bound water, and the (3) loss of free moisture which functions as a binder. This paper investigates the causes of dust formation, provides methods to reduce dust carryover from the rotary devices, and finally offers methods to recover the dust in the existing pyrometallurgical process. Keywords: Laterite, Drying, Rotary, Dust

Jan 1, 2004

By Claude Lorenson

"The Spyrometer™ imaging pyrometer brings new dimension of imaging capabilities to temperature measurement technology by combining a high temperature video camera with scanning optical pyrometry. This gives the operators the ability to observe process conditions while measuring the temperature of virtually any object or region in the field of view. Since the lens tube of the camera can be air or water cooled, it is possible to see inside furnaces giving a very good view of many different types of metallurgical processes. Specific benefits in process knowledge and maintenance tasks for furnaces in different types of metal industries are discussed.1-Principles of Imaging PyrometryLens tube, camera and processorImaging pyrometry is the combination of video imaging and computer-driven pyrometry that measures the temperature of certain zones (selected by the operator) within the image viewed on the monitor screen. To obtain a detailed image of the metallurgical process under observance, it is necessary to place the optical objective of the camera close to the process. The Spyrometer™ (which is Quadtek's tradename for its imaging pyrometer) objective is housed in a lens tube that is cooled and permits insertion inside the vessel of interest. The length of the lens tube is chosen on the basis of making sure that the tip of the tube is just beyond the refractories lining the inside of the furnace. In most pyrometallurgical processes, we have found that the most reliable system set-up uses a water cooled shroud to cool the lens tube optics. A sapphire window provides maximum protection from the environment. Even in the case of the water cooled version, there is an air purge for the lens that keeps the objective clean and protects against hot metal splashes."

Jan 1, 1997

By Tom Marttila

During the last few years, when a new tankhouse or a major modernization has been planned, automatic or semiautomatic crane and grab systems have at least been considered. It seems that in the future tankhouse managers for new, modernized and even old tankhouses will be looking for a proven and reliable system for automatically moving and positioning electrode loads in the tankhouse and in storage areas. In this paper, we will describe the Wenmec solution for automatic electrode handling. The advantages of automatic handling and very accurate electrode positioning will be discussed, and the way Wenmec has solved the problems in mechanical construction and in automatic, accurate and reliable positioning will be presented.

Jan 1, 1990

By Yoshihiko Maeda

It is said that the 21st century will be an era of the remedy of the global environment. In order to reserve natural resources for the future and to avoid the dispersion of heavy metals after usage and to avoid pollution problems, it is extremely important to recycle heavy metals as much as possible by reasonable recovery procedures. The nonferrous metal industry is expected to play a important role in the recycling of heavy metals that are originally their products. From the depressed metal price experienced in Japan in 1980'h due to the sudden change in current exchange rate between US dollar and Japanese yen, one of major nonferrous metal company, Dowa Mining, has diversified its business area not only to the so-called down stream, but also to the environmental business including metal recycling, industrial waste treatment and soil remediation by utilizing technologis and facilities once used or still used for mining and smelting of copper, zinc, lead and precious metals. In this paper some of these applications will be presented.

Jan 1, 2003

By John Pilling

The concept of microstructure, its evolution through materials processing and its effect on the properties of the material is, perhaps, the foundation upon which the science of materials is built. PHAUST, a computer aided learning program, attempts to provide instruction in establishing the relationships between phase diagrams, thermal processing and microstructure. Using phase diagrams derived from a database or created by the user, the evolution of microstructure during processing is quantified using the lever rule and/or the Scheil equation and tracked through a doubly linked list (a form of binary tree). Microstructures, in the form of full colour cartoons are then drawn using the quantitative and logical information contained within the linked list using bitmapped templates and logigal operators such as NOT. AND, OR and XOR, giving the student a view of the structure as it would be seen under the optical microscope. The software provides complete diagnostics of student answers, locates errors and misconceptions as well as providing tutoring towards the correct solution method and answer.

Jan 1, 1991