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By Yutaka Shiraishi

Two methods were developed to measure the viscosity of the slag from the glassy to the liquid states in an ascending temperature process. The first method employs rotating parallel plates within which is placed a solid cylindrical sample in line with a sphere. The second method uses a tube which is pushed into a sample held in a rotating crucible. Both methods were tested using standard glasses, including boron trioxide and NBS standard glass #711. The main difference between these two methods is in sample preparation. Comparative measurements between two methods were performed using a sodium boro-disilicate glass containing 5%mol of alumina. The results showed good agreement in the mid-range of glassy viscosities, 105 to to7 Pa.s. In the liquid state, there were no significant differences between the two methods.

Jan 1, 2003

By S. C. Sharma, M. Krishna, N. Sanmukha

"The oxidation behavior of an aluminium composite with 0, 2, 4, and 6% by weight of hematite at 200 to 500 °C has been investigated. Within the experimental temperature ranges a parabolic weight gain was observed. The, weight gain as a function of oxidation time becomes linear after an initial period on oxidation formation, an oxide scale was found whose morphology depends on temperature, cooling rate and sub-scale formation at the interface between the matrix and reinforcement. The presence of hematite particulate reinforcement has very little effect on the oxidation behavior. The interface oxidization rate was found to be higher than that of other regions. The, oxidation products were either metallic oxides or ceramic oxides. The exposure time of specimens to oxidation was 1000 minutes at various temperatures. In the present work key principles of alloy oxidation were discussed. Also the paper emphasizes various reactions taking ' place and the activation energies involved in the oxidation reactions.IntroductionMetal matrix composites (MMCs) reinforced with ceramic particulate, whiskers, or fibers have received increasing attention due to their potentially high fracture toughness and strength 1-5. Particle reinforced Aluminium MMCs find potential application in several thermal environment, especially in the automobile engine parts, space applications, such as drive shafts, cylinders, pistons, and brake rotors6.With the exception of gold, no metal or alloy is stable at room temperature, they tend to form their respective oxides. Most of the metals in the solid or liquid state are morphologically unstable when exposed to air at higher temperatures. An investigation relating to the temperature profiles of the piston area in a diesel engine has shown that the temperature can reach as high as 500¬800 K in certain regions of the piston. As the piston and cylinder areas are exposed to high temperature environment, the MMCs should have sufficient stability on both mechanical and chemical strength (oxidation). Oxidation occurs at grain boundaries in alloys and at the interface of the particulate and matrix in MMCs, which usually enhances intergranular fracture, resulting in premature failure and severe brittleness 8-10. Therefore for high-temperature applications, it is essential to have a thorough understanding of the oxidation behavior of aluminium MMCs."

Jan 1, 2000

By M. C. Esposito

Seven pyrite samples purified from coal sources and one ore source pyrite (for comparative purposes) have been characterized by chemical and mineralogical analyses, inherent floatability, apparent specific gravity, surface area, semiconductor type, optical anisotropy, dissolution and oxidation rate. The data clearly demonstrate that pyrites from various coal sources differ not only from ore pyrite but from each other as well.

Jan 1, 1987

By Antti Roine

HSC Chemistry is a widely-used therniochemical tool in the chemical and metallurgical industries and in universities. The main reasons for it's popularity is the easy user interface and the large integrated thermochemical database. This paper summarizes the main properties of the new HSC Chemistry version 3.0, and gives a short review of the new features: Some metallurgical applications with the new features are also presented. HSC Chemistry 3:0 contains seven calculation modules and a thermochemical database with more than 11 ,000 chemical compounds. The new spreadsheet type table editor gives more control to the user, the new graphics routines have fewer limitations and more formatting properties. The capability and speed of calculation routines have also been improved.

Jan 1, 1998

By J. Huisman

With the introduction of ever-stricter environmental operating guidelines, capital expenditure restrictions and operational budget cutbacks, the biological method of SO2 removal becomes more and more attractive. Biological treatment of dilute flue gases is a more cost effective technology in comparison to conventional sodium hydroxide scrubbing. Although the investment costs for sodium hydroxide scrubbing is lower, the operational costs are significantly higher. In addition, the end product of the biological installation is sulfur instead of sodium sulfate; and no further wastewater treatment of the bleed from the biological installation is required since heavy metals are removed simultaneously. Another option for the treatment of SO2 containing gas at a sulfuric acid plant is the production of extra sulfuric acid of the discharged SO2 by applying an additional converter. Comparing biological treatment with this option shows much lower investment costs for the biological installation. Sulfur is produced which can be converted to sulfuric acid, so the bio-route will be more cost-effective than an additional converter. In principle, the biotechnological gas cleaning system is an integration of an absorber with a wastewater treatment facility. In the absorber, the SO2 containing gas is brought into contact with the washing water. The effluent absorber liquid contains a mixture of sulfite and sulfate that is converted into elemental sulfur. This conversion takes place in an integrated system; first, the sulfite/sulfate mixture is converted anaerobically into sulfide; secondly, the sulfide is converted aerobically into elemental sulfur. Subsequently the sulfur is separated and the water is returned to the absorber. Due to the buffer capacity of the washing water, removal efficiencies over 98% are possible. In addition to SO2 removal, it is possible to convert for example other bleeds streams such as scrubber acid or weak acid to sulfur in the same SO2 installation. Recent evaluations concluded that biological desulphurization of flue gases is not only economically attractive in comparison to convention sodium hydroxide scrubbing but also in comparison to gypsum producing systems and even seawater scrubbers. This paper describes the technological and economical viability of biological flue gas desulphurization.

Jan 1, 2005

By Rodney T. Jones

DC arc furnaces were first used industrially for the reductive smelting of chromite fines to produce ferrochromium thirty years ago. Since then, they have been used for a variety of applications, including the smelting of ilmenite to produce titania slag and pig iron, the recovery of cobalt from non-ferrous smelter slags, and the smelting of nickel laterite ores to produce ferronickel. The power of these furnaces has increased from 12 MW to 72 MW for ferrochromium, and to 80 MW for ferronickel. The largest of these furnaces requires two electrodes to carry sufficient current to generate this much power. A review is presented of various DC arc furnaces in use, along with a discussion of the likely ways in which furnace power might be increased further in the future.

Jan 1, 2014

By Mark Jolly

"Over the last ten years or so many man hours have been dedicated to developing methods for simulating shape casting processes. The majority of the methods developed have been devised by a combination of computer, mathematics and materials specialists often with limited knowledge of foundries and foundrymen. As a result of this it would appear that although there are many software packages for the foundryman to use there still exist fundamental misunderstandings as to their usefulness and suitability within the foundry.The paper aims to identify how well current software packages perform. The relationships between physical phenomena, practical defects and software capabilities are presented. Some discussion of the use of criteria functions is also presented. Finally issues arising from the postprocessing of results are discussed as the presentation of the results to the lay-person in simulation techniques is possibly one of the most important aspects in influencing the adoption of this type of software in the foundry community."

Jan 1, 1999

By Peter Bauer, Klaus Gamweger

"Gas purging systems are well established in nonferrous metallurgy at multiple steps during metal production, including melting, converting, alloying, and metal cleaning. Since the kinetics of all of these stages are positively influenced by using gas purging systems the overall process benefits are substantial. In the aluminum industry, inert or reaction gases are blown into the melt using porous plugs to achieve improved metal grades, higher productivity, and more efficient energy utilization. To enable the most effective application of the process gases a complete package, termed AL KIN, was developed by RHI that includes porous plugs, refractory expertise, gas supply technology, and gas control equipment. This paper discusses the technological and economic advantages of this system and the specific benefits of fuel reduction, production time savings, decreased process gas consumption, and improved refractory service life and maintenance are illustrated using an aluminum slug plant in Austria.IntroductionIn addition to high quality production, increasing productivity is the main goal in many aluminum cast houses to maintain or even strengthen their market position. The Neuman Aluminium Group, based in Austria, North America, and based in Austria, North America, and China, is the largest slugproducer for tubes, cans, and automotive parts worldwide. Recently, a comprehensive improvement program was initiated at the Neuman Aluminium Austria slug plant in Marktl - the main factory and technological centre of the group. The principal goal of the optimization project was to increase the productivity of the strip-casting production. The investment included a gas purging system, ingot preheating equipment, a new insulated launder system, and optimized melting cycles. However, the introduction of the gas purging system was pivotal to the project and has accounted for approximately 50% of the benefits achieved. This paper describes the AL KIN gas purging technology and details the process benefits resulting from the improvements at Neuman Aluminium Austria."

Jan 1, 2009

By R. W. Bartlett

A two step process for treating platinum group metal flotation concentrates Is described while experimental results. The process was designed to be simple and Inexpensive While yielding a high recovery and fast turnaround. Ii consists of electric furnace smelting of concentrate to remove gangue and produce a homogeneous sulfide matte containing all of the base metals and platinum group metals. Sulfide oxidation Is minimized during smelting to avoid Installing an acid plant In the second step, matte Is pressure-leached with oxygen In an acid sulfate system to dissolve Iron, nickel, ?and copper while leaving a residue highly concentrated In precious metals, and typically about 1% of the flotation concentrate mass, A batch process with oxygen titration against the base metal composition of the feed Is used to control the end point of the leach. Sulfides must be eliminated while minimizing the precipitation of hydrolysis products. The leach residue can be smelled to bullion to facilitate sampling accuracy.

Jan 1, 1989

By Don Eby

The application of electric arc furnace smelting of lead, antimony, and tin bearing slag from a reverberatory furnace will be discussed. The selection procedure for the 4.0 MVA electric arc furnace in Indianapolis, Indiana is presented. The design criteria for the transformer, electrodes, refractories and associated equipment is presented. The operation of the furnace including chaJ:9ing, bullion tapping, slag tapping, ventilation, slag composition, metal recoveries, and toxic leach results of thra.1 away slag are discussed. Flow charts and the equipment specifications are given.

Jan 1, 1990

By Lauri Holappa

Copper converting is mostly performed in Peirce-Smith converters. The process is still very similar to the original one developed in the early 20th century. It is a batch process in a horizontal cylindrical reactor with air blowing via tuyeres along the length of the reactor side. The Peirce-Smith converter has its roots in Bessemer's inventions in the 1850's as he tested both horizontal and vertical vessels for steel converting. However, for steel making a vertical pear-shaped converter with air bottom-blowing was established. In the course of time, there was a distinct necessity for oxygen usage instead of air due to harmful effects of nitrogen to steel properties and its cooling effect. In-bath blowing of oxygen did not succeed, however, and top-blown oxygen converter with oxygen lance (LD or BOF) was first developed in he 1950's and emerged rapidly to a dominating position. Somewhat later oxygen bottom-blowing via special shrouded tuyeres was developed (OBM or Q-BOP) but has attained only fractional share. Bottom-blowing technique had, however, impact on the current combined blown converters which adopted the benefits of both top and bottom blowing. In copper converting Peirce-Smith type converters have kept their position until today although new processes have been introduced and at least few of them seem to be emerging. In one respect copper converting has a clear leading position i.e. in the progress of continuous converting processes (Mitsubishi, Ausmelt). These processes utilise top-blowing lances instead of in-bath blowing tuyeres. A different principle for continuous converting is flash converting by Kennecott Outokumpu, which makes smelting and converting independent of each others. Solid ground matte is used as a feed for flash converting in a reactor shaft similar to Outokumpu matte flash smelting. A comparable process has been presented by Inco too. The paper discusses principal physico-chemical and process technical similarities and differences in copper and steel converting. Although these processes are metallurgically quite different it seems that during the modem history of ferrous and non-ferrous metallurgy, starting from the 1850's, the exchange of knowledge between these disciplines has been quite intensive. In long-term perspective, many similarities in the development can be found but also divergences due to different ambient circumstances.

Jan 1, 2003

By Sang-Su Lee

This paper shows the application of the porous plug system in the Mitsubishi continuous copper smelting and converting process. This system has already been adopted and utilized in the steel industry to enhance productivity. Recently, some copper smelters have adopted this system but the results have not been satisfactory. The porous plug system was installed at the anode furnace in December 2001 to reduce the oxidation time and decrease the oil consumption. A good effect was that the nitrogen stirring of the melt through porous plugs improved the melt heat transfer. As the result of the enhancing heat transfer the oil consumption and the build-up inside the furnace were actually decreased. But until now the oxidation time has not been sufficiently reduced. In the future, further research and tests are needed in order to increase the productivity and save costs.

Jan 1, 2003

By Malti Goel

"The cost-effective capture of carbon dioxide (CO2) from the point sources for its reduction the atmosphere offers many challenges in materials science. Novel CO2 capturing approaches using chemical, physical and biological methods are in the research stage and are aimed to minimize the cost. Appropriate materials development , which can withstand required temperature or pressure as the case may be for CO2 emanating from coal gas or industrial waste gases form the minimum condition. Other requirements are reclyclability of material and cost of separation. Nano-material composites can be more effective in selective capture of CO2 and can offer solutions for large-scale separation process. Nano-porous material catalysis can enhance the reaction rate of CO2 with other chemicals and thus help in capture of CO2 and convert it into value added products. This paper reviews recent industrial scale developments. In the Indian context, R&D priority areas in CO2 capture process development with a focus on energy industry are presented.IntroductionScience of Climate Change is growing at an enormous pace. With the ultimate goal of stabilization of greenhouse gases in the atmosphere, new scientific approaches are being researched worldwide. A shift in policies from low carbon and no carbon energy sources to fossil fuel sources with capture of carbon and its permanent storage is taking place. The process of carbon capture is both energy and materials intensive and the cost of power generation may increase up to 40% when carbon capture and storage (CCS) technology is implemented. Development of cost effective R&D technology therefore remains the greatest challenge before the scientific community."

Jan 1, 2009

By Theodore Ineich

The “BIOMOre” project aims to prove the technical feasibility of indirect in situ bioleaching of sulfide minerals contained in a deep underground deposit, by bringing together the disciplines required to make a success. The underground location in Poland was provided by project partner KGHM inside an operating copper mine. Key components of this project were the design and construction of a pilot plant, and its operation in an underground environment. This project also included a ∼250 t (100 m3) fragmented rock reactor hydraulically connected to the pilot plant. The pilot plant consisted of several tanks and pumps, a fluidised bed ferric iron generating bioreactor containing immobilised acidophilic iron oxidation biomass, and all the required instrumentation and utilities. Before the bioleaching phase could start, the rock reactor had to be flushed continuously firstly with water to remove chloride salts that are corrosive and also harmful for the bacteria used in the bioreactor, and secondly, with sulfuric acid solution to react with the carbonates present in the ore matrix. This paper summarizes the design, construction, commissioning, and operation of the pilot plant.

By C. Kathryn Sole

The close proximity of cobalt and nickel on the Periodic Table and their frequent occurrence together in nature means that their separation in primary hydrometallurgical flowsheets is not only often necessary, but requires the use of innovative chemistry to achieve high selectivity. Today, increasingly stringent demands for the high-purity cobalt and nickel salts required for battery applications in consumer electronics, electric vehicles, and solar applications are again challenging the state of the art. The evolution of cobalt–nickel separations is traced from the basic precipitation technologies employed in 1960s, through commissioning of the first cobalt solvent-extraction plant in South Africa in 1974, to the commercialisation of organophosphinic-acid extractants (which provided a step-change improvement in selectivity) and their eventual widespread use in the 1980s and ’90s. This was followed later by their sulphur analogue, which enabled different possibilities for laterite processing in the new millennium. Separations in chloride media, which take advantage of the different speciation chemistries, and nickel extraction by oximes in ammoniacal systems are also discussed. More recently, chelating and solvent-impregnated resins have added further dimensions to the possibilities for flowsheet design and enabled higher purity products to be attained from both primary and secondary sources. Selected case studies and flowsheets are described.

By James J. Komadina, Robert R. Beebe

"Heap leaching of gold ores has enjoyed wide acceptance in the arid and semi-arid regions of the western U.S., Australia and South America. There are areas, however, where cold weather or excessive precipitation can limit the usefulness of heap leaching. Even in Nevada difficulties can be encountered which call for special operating procedures.The paper discusses the general climatological limitations and some of the techniques used to extend heap leaching into colder conditions. A case history of the Cripple Creek and Victor Gold Mining Company operation in Colorado examines 'valley-fill"" technology as an ideal cold-climate solution, where topographical conditions permit.AcknowledgementsThe authors gratefully acknowledge the management of Independence Mining Company for their permission to present this paper. The contributions of Golder Associates; Pikes Peak Mining Company Environmental Affairs Department staff, and the Colorado Department of Mines and Geology were all invaluable in successfully concluding this project.BackgroundWhen heap leaching of oxidized gold ores was introduced in the rnid-1970s it was aimed at large tonnages of low-grade material which could not, in general, be developed via conventional milling. Normally, the reasons for this were economic rather than technical: capital and operating costs for milling were simply too high. At first, grade was almost the only criterion, but deposits too small to justify milling were also potential targets for heap leaching.Renewed interest in gold was centered in the western United States and Australia, where exploration for milling-grade deposits had never really died. When heap leaching came along, it was in these areas that the first developments took place. Coincidentally, these same areas were favorable for heap leaching: climates were temperate for most of the year and competing land uses were limited. Even so, in the western United States in particular, winter temperatures were low enough to complicate operations. Precipitation was less a problem, although heavy snowfalls could periodically interfere as well."

Jan 1, 1997

By Godwin J. Igwe

For soil remediation technology to be effective, a thorough understanding of the interactions between a targeted contaminant and the soil matrix is crucial. Proper selection of remediation technology, based on understanding the bonding/binding characteristics of the soil and contaminant, can often result in significant remediation cost savings. Contaminated soil cleanup is complicated by both the physical nature of the soil formation and the behavior of contaminants introduced into the formation. Contaminants can exist in the subsurface in different phase attached to the soil surfaces, dissolved in the ground water, or occupying pore spaces as a separate gaseous or liquid phase. Contaminants properties and how they exist in the subsurface influence their toxicity, mobility and treatability with different remediation technologies A soil characterization study was performed to provide information for remediation technology selection for an inorganic lead contaminated soil. The soil pH, TCLP analysis, thermogravimetric analysis, the soluble anions and cations present, equilibrium leaching tests, analysis by x-ray fluorescence, sequential extractions and speciation analysis using scanning electron microscopy, were all used. Results provided many insights into contaminant behavior in the soil, indicating ultimately whether soil washing or solidification/ stabilization remediation technologies were applicable.

Jan 1, 1994

By D. A. Salinas G., A. H. Castillejos E.

Pachuca tanks are commonly used in the hydrometallurgical industry to carry out leaching operations. The fluidynamic characteristics of the liquid phase, resulting from the injection of gas into the draft tube, are important to achieve the complete suspension of the mineral particles and has a decisive influence in the mass transfer processes occurring in this reactor. This study investigated the effect of different design and operating characteristics on the liquid velocity field. using a laboratory-scale Pachuca tank. The transparent model was filled with water, and air was injected through the bottom in the absence of mineral particles. The liquid velocities over the whole reactor were measured under several experimental conditions using particle image velocimetry (PIV). This technique allowed to obtain a very detailed picture of the liquid motion even in the draft tube, as long as bubbles were absent from the measured field of view. The experiments have shown that the liquid velocities increase with increasing the draft tube to tank diameters ratio, the distance from the conical bottom to the draft tube entrance, or the gas superficial velocity. On the other hand, an increase in the water level with respect to the draft tube outlet caused a decrease. A mathematical model, which used the no-slip model, to calculate the variation of axial effective density along the two-phase region, was found to predict liquid velocity fields which agree very satisfactory with the experimental results obtained under all the conditions studied.

Jan 1, 1999

By M. Fujikawa, S. Goto, M. Nishikawa

"The semi-pilot scale plant for injection smelting of zinc calcine was operated under the committee of Joint Research Organization of Injection Metallurgy. The capacity of the plant is 10 ton metallic zinc per day. The plant was designed by the resul ts of basic and bench scale tests of the capacity of 1 ton metallic zinc per day which was published at ""Zinc '85"". The equipments of the plants, operational conditions, results of the operation such as recovery of zinc in injection furnace and condenser, combustion rate of powdered coke and consumption of energy in this process are presented in this paper. The results of the study of the feasibility of the commercial plant of 100,000 ton zinc per year by the injection smelting are also discussed in the paper. IntroductionThe research committee of new smelting process of zinc by injection was established in 1981 under the finantial support of Mining Promoting Foundation of Japan. Six zinc producing companies joined in this organization. The price of zinc was very low at that time and the energy cost, especially, cost of electric power in Japan was extremely high. Invention of a new economical process for zinc extraction had been stronglydesired. The author proposed a injection smelting of zinc as a economical process in energy saving after a calculation of thermodynamical equilibrium and heat balance(1 )(2).The research committee has been studying the injection process since 1981. The small basic experiment by using a crucible furnace was carried out from October 1981 to March 1983 and the reaction of reduction of calcine by injection smelting was ascertained (2). Vaporizatipon of zinc and behaviours of impurities were examined. After the basic experiment, the bench scale test with the production capacity of zinc of 1 ton per day was carried on from November 1983 to October 1984.The bench scale tests were carried out to obtain the proper design of feeding devices of calcines and coke into a furnace and also to obtain fundamental data for enlargement of this smelting process(3,4). The recovery of metallic zinc in this small equipments was about 50% and main loss of zinc was formation of dross in the condenser."

Jan 1, 1988

The effect of change in slag composition upon metal losses to the slag and the relationship between slag composition and slag matte separation was investigated at 1400°C. The synthetic slags containing CaO, MgO, SiO2,, A1,0, and FeO were similar to those employed in the electric furnace smelting of sulphide Cu-Ni concentrates containing PGM (Precious Group Metals) from the Merensky Reef of South Africa. The matte with a grade of 9.3% Cu and 16.0% Ni was a typical electric furnace product. The results indicated that the Cu and Ni solubility in the slag increases with the increase of the basicity ratio and CaO and MgO contents of the slag. At constant CaO/MgO ratios the rise in basicity decreases the metal losses. When FeO and SiO2 contents of the slag are kept constant, the substitution of MgO with CaO decreases the metal losses. The relationship between slag composition and matte-slag separation was found to depend primarily on the basicity ratio and the FeO content of the slag. The net effect comes from a strong interaction of the two in such a way that increasing basicity and decreasing FeO contents deteriorate the clean separation of the two phases.

Jan 1, 1994