Search Documents

By Rainer Köster, Tobias Wagner, Markus Delay, Fritz Hartmann Frimmel, Wolfgang Ferstl, Wolfgang Höll

"The mobilization of contaminants from industrial residues like ashes from municipal solid waste incinerators in case of leaching is investigated world wide. In classical leach tests only soluble species are considered. In addition the geochemical behaviour of residues has to be completed by assessing the mobilization via colloidal particles. This transport is well known from natural aquatic systems. Quantification of aquatic colloids is associated with considerable difficulties, because they are often found in low concentrations and in a size distribution where small particles with diameters below 0.1 µm predominate. In the past years, the Laser-induced Breakdown Detection (LIBD) has been developed as a novel sensitive method for quantifying colloids. Column leaching experiments with directly coupled LIBD were used to quantify the release of heavy metals and colloids out of bottom ashes. Some typical colloid bound heavy metal concentrations in the leachate are in some cases exceeding the limits defined by German authorities. The LIBD with a flow-through cell allowed to assign absolute values to colloid size and concentration."

Jan 1, 2008

By Srinath Viswanathan, Zhijing Zhang, Ramana G. Reddy

"The viscosity measurements were carried out on melts of 380 aluminum alloy containing 20 volume % SiC particulates under various shear rates at different temperatures using a Brookfield viscometer. Results showed that viscosities of the melts increased with decreasing temperature and decreased with increasing shear rate. These results were compared with those of 356 alloy and it was found that the temperature had a more significant effect on viscosity of 356 alloy than that of 380 alloy containing SiC particulates. Based on the present experimental data an empirical viscosity model, which considers the effects of both solid fractions in the melt and shear rate, is proposed.IntroductionDiscontinuously reinforced metal matrix composites materials (MMCs) such as aluminum alloy containing SiC particulates have considerable potential for applications in the automotive industry because of their superior stiffness, higher specific mechanical properties, better dimensional stability and strength retention at elevated temperatures when compared to their monolithic counterparts. They have a great advantage in the specificity of their properties, meaning that specific materials can be engineered for specific applications. With such freedom of design, materials engineers have to accumulate a very large database of mechanical properties. Among these properties, the viscosity of alloy slurries is very important for producing, casting and forming process of metal matrix composites materials because viscosity has a decisive influence on fluid flow. The understanding of the rheological behavior of alloy slurries is necessary for these materials to become economic reality. Therefore, a study was carried out to measure the viscosities of 380 aluminum alloy containing 20 volume % SiC particulates under various shear rates and temperatures. In addition, a viscosity model representing the primary features of the alloy slurries was developed."

Jan 1, 1999

By E. S. Geskin

"This paper is concerned with the construction of a formal technique for the selection of a metallurgical technology. Exergy consumption is used as the criterion of process efficiency. Different items of the exergy balance are considered and techniques for the reduction of exergy consumption are determined. The selected techniques of exergy saving enable us to identify processes which should be used at different stages of steelmaking. The combination of the selected processes enables us to suggest a technology for conversion of iron ore into steel products. The selection of this technology narrows the range of further search of metallurgical processes. The paper shows that qualitative thermodynamic analysis can be used as the first step in the design of metallurgical processes. IntroductionThe existing processes for making, shaping and treating of steel enable us to convert the available iron bearing ores into marketable steel products. However, the energy cost of metal production is much higher than thermodynamically required, while the metal properties are much lower than thermodynamically available. Increasing cost and declining availability of energy and raw meterials make the creation of new steelmaking technologies imperative. In recent years, the number of novel processes for the making, refining, and shaping of steel have been suggested and tested. Some found a practical application. However, the tested technologies make up a small portion of the physically available routes for the conversion of iron ore into a marketable product. It is also not evident that the optimal routes have been tested and that the selected technologies are the best among those tested.Although the development of new metallurgical technologies must be based on the experimental and practical information, the number of the alternative routes for the making, shaping and treating of steel, as well as the cost of examining each single route, make necessary the use of analytical techniques for the evaluation of the possible ways of process development."

Jan 1, 1988

By P. Meyers, F. DeSilva, L. Gottlieb

A number of tests looking at lead removal using ion exchange resins of various types from various aqueous streams have been undertaken. The tests focused on strong acid cation (SAC) and weak acid cation 0N AC) resins. It was found that the mechanism of lead removal is partly by lead filtration rather than solely by ion exchange in a large portion of the applications studied. This is not surprising since lead carbonate is essentially insoluble and almost all water supplies contain at least some carbonate alkalinity. Regeneration of lead from exhausted resins containing significant amounts of lead may not be practical in some cases because of the large chemical and waste volumes involved. Since lead, .·along with many other very insoluble metals, is often present as a suspended solid rather than in ionic form, ion exchange is probably not always the best technology for bulk lead removal.

Jan 1, 2000

By Melissa L. Trapani

The removal of molten products from metallurgical furnaces is one of the most hazardous and labour intensive processes in a non-ferrous smelter. The proximity of operators to the molten metal and slag during tapping and the oxygen lancing that facilitates the flow have led to many reported injuries on tapping floors. In most cases, tapholes are opened and closed periodically leading to extreme thermal cycling in the tapping assembly. As a consequence, refractory wear rates are high and unpredictable in the taphole. This paper provides a review of the current state of taphole development, and gives a methodology that is now being applied to gain a better understanding of the taphole region to allow design improvements.

Jan 1, 2002

By John A. Gisby

Phase equilibria for multi-component systems can be calculated reliably from critically assessed thermodynamic data for sub-systems using software packages like MTDATA, developed by the National Physical Laboratory, UK (NPL). Models and data resulting from an ongoing Mineral Industry Research Organisation (MIRO) project make such calculations possible for the complex systems encountered during sulphide smelting, involving interactions between matte, slag, metal, and gas phases. Predictive calculations can be made that are directly relevant to industrial processes, covering composition and temperature ranges beyond the scope of hard- copy phase diagram compilations, allowing the feasibility of more economic and environmentally sound routes to be explored, better choice of materials to be made, and pilot plant studies to ,be directed more efficiently. Current applications include the selection of suitable fluxing practices in copper and nickel smelting, analysing the operation of the Kennecott copper smelter, optimising the recovery of precious metals and investigating refractory wear.

Jan 1, 2002

By Henrlk Gripenberg

To solve the environmental and financial problems of the traditional Rotary Salt Furnace process, a new salt-free method for aluminum dross and scrap melting, ALUREC, has been developed by AGA and its partners, Hoogovens Aluminium and MAN GHH. AGA and Hoogovens Aluminium developed the main process concept and jointly carried out trials on pilot plant scale. Owing to excellent results" the partners decided to jointly erect a commercial scale test plant. The order for the design and erection of the furnace went to MAN GHH. The three companies designed the test plant and began operation in the spring of 1994. The results have been excellent and the process is expected to be a technical and commercial success.

Jan 1, 1995

By Frustino L. Prado

For more than a century, the AAC (ammonia I ammonium carbonate) process has been applied to the recovery of various metals. A variation of it, the Caron Process was first used in the early 1940's in Cuba for the extraction and recovery of nickel from laterites. The original Nicaro plant has been in continuous operation since then. Years later the Caron process was used again in Australia at the Greenvale (Yabulu) NickelICobalt plant, commissioned in 1974. Other projects (Sered, Niquelandia, Nonoc, Punta Gorda, Albania) as well as several studies have been carried out. The Caron Process is alive and still promising. Members of our organization have been working with AAC and the Caron Process since 1952. This paper will review current approaches and potential improvements (enhancement of recoveries of Ni and Co, reduced energy consumption and maintenance simplification). Keywords: Caron Process, Ammonia, Ammonium Carbonate, Laterites, Nickel, Cobalt

Jan 1, 2004

By Yun Li

In 1999 Yunnan Copper Corporation (YCC) decided to modernise their copper smelter and change the existing sinter plant I electric furnace process to a combination of ISASMEL T and electric slag cleaning furnace. The main aim of the project was to improve the environmental performance and decrease the energy consumption. Generally the project has been successful, partly attributable to the selection of a reliable and fully demonstrated technology. The design capacity for the ISASMEL T furnace is 600,000 tonnes of dry copper concentrate per year. The furnace has been running smoothly since heat up in May 2002. YCC expended considerable effort in the preparation for plant operation. An extensive training program for key YCC personnel at the Mount Isa Copper Smelter improved their understanding of the process significantly and ensured successful hand-over of the technology. This paper describes the project history and summarizes initial operating results.

Jan 1, 2003

By Ilona Johnson

United States metals and non-metallic minerals manufacturing consume about 5,000 trillion Btu annually. Various studies estimate that as much as 20 to 50 percent of this energy is lost as excess or waste heat. Recovery of waste heat can conserve energy, reduce operating costs, and lower environmental emissions. It would be valuable to quantify recoverable waste heat sources and identify the barriers that hinder its recovery. This paper provides an overview of waste heat losses specific to high temperature processes in primary metals and minerals manufacturing. It summarizes findings from a broader study conducted for the Department of Energy Industrial Technologies Program; the study evaluates energy losses, recovery practices and opportunities, and R & D needs for waste heat technology development.

Jan 1, 2008

By Donald R. Sadoway

Fused salt electrolysis is used extensively in the primary extraction of metals (electrowinning), in the refining of metals (electrorefining), and in the formation of coatings (electroplating). In the case of rare earths, fused salt electrolysis competes with nonelectrochemical processes to make the same products. However, fused salt electrolysis has the potential to produce these metals in a variety of technologically useful forms: thin films and epitaxial layers, powders, and a variety of nonequilibrium structures. The theory and practice of fused salt electrolysis as it applies to the extraction, refining and plating of rare earth metals are described. The potential of fused salt electrolysis to synthesize advanced materials containing the rare earth elements is assessed.

Jan 1, 1989

By Kim Fagerlund

A novel apparatus for studying refractory infiltration and dissolution/degradation under a temperature gradient was developed. To supersede conventional isothermal refractory testing, a new temperature gradient technique, based on a crucible equipped with a cooling element, has been developed to provide practical information on the penetration and dissolution of refractory materials under cooled conditions. This technique was adopted and applied to several refractory-slag systems. Commercially available magnesia chrome refractory bricks against a copper-containing calcium ferrite type of slag were tested and compared using both a conventional crucible test and the new temperature gradient method. The experiments were conducted at 1300-1420°C under a controlled atmosphere of nitrogen or air. It was noticed that the type of porosity has a significant effect on infiltration of magnesia chrome refractories. Furthemore, the copper-containing calcium ferrite slag caused a severe slag attack and refractory failure in some cases, due to its fluidity and corrosive nature.

Jan 1, 2002

By Y. Waseda, S. V. Gnyloskurenko

"Present paper reviews the various processes for making of metallic foams. These methods are classified in accordance with the state of initial metals - liquid, powdered and ionized. Liquid metal can be foamed by direct inputting of gas into melt, using gas releasing foaming agents or producing supersaturated metal-gas solutions. This group also includes methods creating voids in the melt. Powder route is based on using powdered matrix metal with foamable precursor materials. Finally Deposition techniques allows making highly porous metallic structures using ionized metal.Experimental study presented shows importance of wettability in bubble formation at gas blowing into melt simulation liquid (water) through holes. Good wettability of injection holes by water ensures formation of bubbles with smaller sizes that effect to the final foam structure.IntroductionOne of the objectives of future production technology is to make of lightweight constructional materials while achieving improved property and good economy as well.The most perspective lightweight materials are cellular or foamed materials that are Wide8pread. in nature and have a growing interest in industry and everyday life.Even metals and metallic alloys can be produced as cellular solids or metal foams beside of the traditional engineering materials such as polymers, ceramics or glass. Recent developments in metal foams, especially aluminium, have produced a new class of lightweight materials."

Jan 1, 2000

By T. S. Piwonka

Modeling the solidification of shaped castings has progressed beyond the initial problem of determining the correct heat and fluid flow relationships which describe the solidifying castings. Today the challenge is to describe second order effects which determine the ultimate quality of the casting. The challenges to the modeling community posed by the needs of today's foundries for models that work are discussed, with some examples of current modeling problems.

Jan 1, 1992

By Roland Kammel

In combination with various physical and chemical methods also electrochemical techniques are most frequently used to improve the recovery of metals from aqueous dilute process streams or effluents e.g. in electroplating, metal finishing, mining and metallurgical plants. To insure cathodic metal recoveries with favorable current efficiency and high throughputs per unit of cell volume seve¬ral types of electrolysis cells have been developed comprising extended electrode surface areas and/or intensive electrolyte. agitation. The practical experiences with these units indicate especially for the electrolytic recovery of metals whose values are high, that the treatment cost permits profitable operations with relativly short payback periods for the units. Anodic reactions can be utilized for the removal of undesired anion contents or buildups of impurities. Appropriate combinations of these recovery methods are used to improve the versatility and the overall economy. Industrial applications reveal their potentional as addidtive techniques for existing processes to reduce the metal content of effluents to values that meet the guide lines of environmental legislation whereas integrated in-operation recovery methods are nowadays increasingly introduced to approach nearly close-loop operations.

Jan 1, 1992

By H. Masuda

The lijima Zinc Refinery started operation in 1972, and has today an annual capacity of 200,000t-Zn. The hematite process was employed for the first time and the ideal of waste-free refinery has been pursued for 30 years. In recent years, however, only half of the hematite produced would be sold to the cement industry and hence a reduction of arsenic level has been necessary in order to sell the entire amount produced. The arsenic cementation process with zinc powder, developed through a long time laboratory research was found among some options as the best for the hematite process. The construction work started in 2000 and the facility was put into operation in 2001, As a result in the same year all hematite were sold to the cement industry. The outline of this project, present operations and technical issue are reported in this paper.

Jan 1, 2003

By Joseph C. Milbourne

The selection of a suitable nitrate removal process depends on a variety of site-specific chemical and environmental issues. The dominant technologies for nitrate removal include biological denitrification and continuous countercurrent ion exchange. The decision to apply either of these technologies, or both together, depends on the nature of the waste water to be treated. Factors that affect the selection of the biological system include the feed composition and feed temperature. Ion exchange nitrate removal systems are less sensitive to the feed composition but require disposal or destruction of the concentrated pregnant eluate. The paper discusses Tetra's continuous countercurrent ion exchange technology (CCIXTM) and fixed film biological reactor, Denite°. The treatment of the ion exchange pregnant eluant is also discussed.

Jan 1, 1994

By Patricio F. Mendez

This paper presents a formalism to automate portions of the traditional scaling procedure. This formalism, called here Order of Magnitude Scaling (OMS), captures essential components of the governing equations into a set of matrices and arrays amenable to computer implementation using standard linear algebra tools. This approach is valid and specially useful for large systems of multicoupled equations. The matrix approach proposed enables one to automate operations such as normalization, dominant balance, obtention of characteristic values, and check for self-consistency. Also, automation permits an exhaustive exploration of all possible balances and the discovery of unsuspected scaling laws. As an example, OMS is applied to the analysis of the viscous boundary layer with no external pressure gradient. The obtained scaling laws for boundary layer thickness and transverse velocity are the same as those obtained with traditional scaling, and in addition, a meaningful estimation for pressure variations within the boundary layer is obtained; this last estimation is typically not addressed in the manual analysis.

Jan 1, 2006

By Robert R. Beebe

On the night of August 1'9-20, 1995, seepage was seen at the toe of the Omai tailings dam in Guyana. The mill was immediately shut down, and within two hours the flow, then mostly water, was diverted into an inactive mining pit nearby. At about the same time a second more serious break occurred at a point where water and solids could flow directly into the Omai River. By the time Ii coffer dam could be completed in the early morning of August 24, some 4.2 million cubic meters of tailings water and solids had escaped from the dam, of which nearly2.9 million cubic meters had reached the Omai River. This paper outlines some initial Process considerations and operational decisions which might have contributed to the dam's failure, describes how the Government of Guyana and the operator, Omai Gold Mines Limited, cooperated in dealing with immediate problems and shows how the Government set about investigating the accident. In particular, the paper details the work of a Process Review Committee comprising Guyanese and foreign experts convened to assess the gold processing and effluent management systems at Omai, and to recommend actions where appropriate.

Jan 1, 1998

By N. L. Piret, E. N. Mounsey

Ausmelt technology is successfully used to process primary and secondary materials to produce lead in large-scale commercial operations and to meet stringent environmental standards. The development and commercial data covering these applications and the results with respect to metallurgical, cost and environmental performance are reviewed in commercial operations. A new smelter is scheduled for commissioning in 2000 at Korea Zinc's Onsan site to process lead fume and other secondary materials to produce 50,000 tonnes per annum of lead bullion. The unique features of Ausmelt technology also allow for the efficient processing of polymetallic concentrates and secondary materials, particularly copper and lead, through the effective separation of these elements into metal, slag and fume species. This capability has been successfully demonstrated at a commercial scale and the results and implications for the industry are discussed.

Jan 1, 2000