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By Benjamin Vidales

Copper in concentrations above 0.5 weight percent in iron and steel causes hot shortness. This tendency is intensified in the presence of dissolved tin above 0.05 weight percent in the alloy. The understanding of the mechanism of removal of copper from molten iron and steel is of industrial importance. In this investigation, we present the experimental results of the removal of copper from molten iron using sulphide flux in the temperature range 1000°-1500°C. The solution thermodynamic properties of binary sulphide melts have been estimated by using the relevant phase diagrams and the behaviour of copper sulphide in these melts is discussed. The kinetics and thermodynamics of the removal reaction are also explained and, the experimental results are also reported showing the equilibrium distribution of copper and sulphur in molten iron.

Jan 1, 1995

By Moenster J. A., M. J. Sankovitch

Doe Run's Buick Smelter was converted from a primary lead smelter to a secondary lead smelter in 1991. The recycling facility was designed to produce 60,000 tons of refined lead per year from 110,000 tons of spent starting-lighting-ignition (SLI) batteries and 10,000 tons of lead contained in drosses and scrap. Since commissioning, Buick's refined lead output has steadily increased to exceed 120,000 tons for 1999. The production gains have been the result of continuous process improvements, empowerment of the workforee, and development of additional scrap lead streams. The production gains were accomplished while setting industry standards for employee safety, reducing plant environmental emissions and employee blood leads, achieving ISO 9002 certification, and expanding product lines to meet customer requirements. This paper highlights Buick's major accomplishments through the 1990's.

Jan 1, 2000

By Marcela Morvová, Mário Janda, Morva Imrich

"The possibilities of greenhouse gas mitigation using various methods are brought out. The special case of utilization of mixture of CO2 with other greenhouse gases in a synergetic way inside non-thermal plasma based system is described in detail.Measurements on pilot system comprising pyrolysis chamber as alternative energy system (production of hydrogen and liquid tar) were made for various biomass and waste as the input material. The exhaust from this system was treated with non-thermal plasma gap suitable for up to 650Nm3/hour of exhaust gas flow. Condensable portion of exhaust is liquefied in distillation unit; produced hydrogen is stored on-line inside nano sized carbon of our own production.The CO2 removal efficiency varies depending on exhaust composition between 45 to 98%. Other oxides as CO, NOx, SOx and several hydrocarbons and VOC are also removed. The main product connected with CO2 removal is a solid powder of proteinoid nature. There exist strong probability, that precursor of the origin of life on the Earth from primary atmosphere were formed in the similar way as it is present in the electric discharge system used. Our system is equipped with on-line as well as ex-post analysis of all forms of products. We have also developed a system for recuperation of all forms of produced heat. It is stored inside as latent heat of waxes.IntroductionNatural greenhouse effect on the Earth is caused mainly by water vapour with the average absolute concentration about 4%. Other gases able to absorb long-wave radiation and thus this causing greenhouse effect are CO2, CH4, N2O, halocarbons and as precursors ozone and NOX. Some of them we produce and introduce into atmosphere in large quantities during production of energy and in transport. This factor leads to permanent increase of average temperature of air, sea and oceans, so called global warming.Nowadays large amount of data exists showing that the temperature of Earth in the last 150 years has been continually increasing. It represents about 03°C per ten years and the most of climatologist believe, that the increased concentration of greenhouse gases in the atmosphere is responsible for this effect.The most important greenhouse gas is carbon dioxide CO2. Majority of CO2 emissions comes from electric power stations working with fossil fuels, cars and industry. Burning of fossil fuels contribute up to 80% to world wide anthropogenetic emissions of CO2."

Jan 1, 2010

By Merete Tangstad, Ragnar Tronstad

Ferromanganese production in electrical furnaces is quite an old process. However, as the furnaces are getting bigger, the requirements of cost, yield, product quality, emissions and security are raised. With the increased expectations, the fundamental knowledge must follow. Within the last 25 years there has been a great effort both in the industry as well as the academic environment to push the limits of this process. This article will show some examples of improvements within fundamental data, reaction mechanisms and emissions over this time period.

Jan 1, 2014

By M. Jennings

In 1987, Echo Bay discovered a major silver/gold ore body at their McCoy property in Nevada, and quickly made a decision to build a 5000 tpd mill which was expanded during the design to 7500 tpd. Since the ore reserves consisted of cyanide leachable oxide as well as sulfide, the plant flow sheet involved an oxide leach, a gravity circuit, and lead sulfide and a pyrite sulfide recovery by flotation. The paper describes the process development, equipment selection, plant design and the startup of the oxide treatment.

Jan 1, 1990

By Munyaradzi Kwatara, Ron Schonewille, Edgar Peek, Juzer Tayabally

"The potential recovery of nickel from a South-American saprolitic laterite ore using the segregation roasting technique was investigated. The ore was heated to temperatures that ranged between 900 and 1 000°C in a rotary kiln. In all the tests, the laterite ore was first mixed with a predetermined amount of calcium chloride and either coal or coke. By varying the temperature, calcium chloride and reductant in the different tests, a preliminary set of optimal conditions was established for the specific laterite ore that was tested. A combination of chemical analysis and electron-probe-micro-analysis (EPMA) were used to determine and evaluate the effectiveness of segregation roasting on the recovery of nickel. The present paper describes the test procedure and the results that were obtained.IntroductionIt is known that laterite ore resources account for an estimated 72% of the world's nickel resources, with sulfide sources accounting for the remaining 28%. Yet sulfide resources account for 58% of the world's primary nickel production while laterite resources account for the remaining 42% [I]. There are numerous reasons for this discrepancy, but the most important one is the mineralogical and compositional complexity that is associated with laterite ore deposits. For example, this complexity currently offers only limited opportunities for upgrading, thereby creating capital intensive whole ore processing facilities. It then follows logically that the identification and application of a low-cost processing option for the treatment of laterites could potentially open up an opportunity for exploiting these vast untapped laterite resources.To this end, a preliminary screening investigation was initiated by Xstrata Process Support to evaluate the potential application of the so-called (nickel) segregation process as a unit operation that could potentially be integrated into a laterite processing flow sheet. Laboratory bench tests were performed on this segregation process and this paper details some of the findings from this preliminary investigation."

Jan 1, 2011

By Richard D. Hagni

Reflected light microscopy is routinely applied to the study of ore minerals and textures in polished sections prepared from a wide variety of ore specimens. With the increasing interest in environmental problems, the important role of the reflected light microscope in the precise phase identifications and the determination of the textural relationships between those phases needs to be recognized. Among other environmental applications, the microscope has been applied to the recognition of lead smelter particles from remote collect sites in Missouri and those particles have been compared to dust particles from specific localities at the nearby lead sinter plant and lead blast furnace. Dust from a secondary copper refinery has been studied for its mineralogy. Soils in the vicinity of a Missouri lead smelter have been studied for their mineralogy in preparation to the clean up of those soils. Electric arc furnace (EAF) dusts, recently classified as hazardous waste by the EPA, have been examined for their mineralogy and textural intergrowth in order to better evaluate proposed metallurgical treatment procedures to render the dust non-hazardous. The initial products from experimental metallurgical treatment of EAF dusts also have been studied to aid in determining the effectiveness of those treatment procedures. Refractory gold sulfides that have been roasted in the presence of lime to retain environmental objectionable sulfur and arsenic while recovering the gold have been studied by RLM to determine their mineralogy, porosity, and permeability for cyanide leach solutions. These case histories illustrate the applicability of ore microscopy to the study of problems related to environmental concerns.

Jan 1, 1995

By N. Can

Kinetics and mechanism of the chemical interactions between Si3N4 and TiC were investigated by isothermally reacting samples under nitrogen and argon atmospheres at temperatures between 1600°C and 1700°C? The initial composition of the powder compact contained 20, 30 and 40 volume per cent TiC? Kinetic analysis were performed by measuring mass losses and composition of the titanium carbonitride (TiC1-xNx) at predetermined time intervals? It was found that in the Si3N4-TiC system the degree and rate of the reactions increased with increasing temperature and content of TiC in both nitrogen and argon atmospheres? Si3N4 in the presence of TiC was stable in nitrogen atmosphere and the reactions were confined to Si3N4/TiC and TiC/N2 interfaces? At both interfaces interchange reaction occurs by simultaneous diffusion of nitrogen towards the centre of the particle and desoprtion of carbon in the opposite direction resulting in formation of titanium carbonitrides with various compositions? Reaction products under nitrogen atmosphere were B-SiC, TiCl1-xNx and N2? The maximum "x" value in TiC1-xNx was found to be 0?67 under nitrogen atmosphere? Si3N4 was found to be unstable in argon atmosphere in the presence of TiC and dissociated into liquid silicon and nitrogen gas within approximately four hours of reaction time, depending on temperature? The reaction mechanism in the initial stages of the interaction between Si3N4 and TiC under argon atmosphere proceeds similar to reactions under nitrogen atmosphere? However, considerable amount of Si3N4 dissociates within the first half hour? Liquid silicon aggressively attack both TiC1-xNx and unreacted or partially reacted TiC particles through cracks and pores and diffuses into interier part of the particle forming liquid solutions? After this stage, reactions under argon atmosphere proceeded according to Si-Ti-C ternary system?

Jan 1, 1999

By William J. Pardee, Michael A. Shaff

"Deeper materials science knowledge from mathematical models and in situ material property sensors will be exploited in next generation factory process controllers to improve productivity and quality. These intelligent control systems will accelerate productivity growth and materials science application through the ease with which they can be modified to accept new materials knowledge and sensors. Carbonization of resin matrix carbon fiber composites, specifically, is a violent solid state chemical reaction with large stresses due to gas pressure, matrix shrinkage, and differences in thermal expansion. The matrix strength falls sharply, then rises again during the process. At least two competing reaction paths are important; the first cleaves methylene bonds, reduces toughness, density and stiffness; the second reforms those bonds, ultimately resulting in aromatic ring condensation that increases density, strength, and modulus. Since these reactions have different temperature dependencies, one can expect to shift the process towards the second path by changing the heating rate, but that change must be accomplished without producing macroscopic interlaminar crack growth. To accomplish this, we employ gas sensors to infer matrix chemical state and acoustic emission to identify microstructural changes and to recognize brittle fracture. The latter does not prevent delamination, but is important in testing models for the causes of delamination and in improving the processing cycle. This paper describes a control strategy to accelerate the process while still lowering the risk of failure.IntroductionDeeper materials science knowledge from mathematical models and in situ material property sensors will be exploited in next generation factory process controllers to improve productivity and quality. These intelligent control systems will be more easily modified to accept new materials knowledge and sensors, thus accelerating productivity growth. Such a control strategy for carbonization control is described below.Carbon-carbon composites are time consuming and costly to manufacture. Processing methods have been developed empirically and are usually very conservative because the process often fails when any change is made. Apparently minor changes in materials or geometry can produce failures that are difficult to diagnose and correct. We will describe below several essentially unavoidable sources of variability. These are best dealt with by applying materials science to adapt (i.e., closed loop control on materials properties) the process in real time to reduce the effect of unavoidable model idealizations, material variability and environmental noise. The most critical issue in control of the carbonization process control is avoiding catastrophic delamination. The strategy developed below makes use of a priori materials knowledge and real time sensors to accelerate the now very slow process without destroying the material, and without requiring unreasonable resources to determine the statistical properties of the material."

Jan 1, 1988

By Georgette Smits

The gun-sprayed refractory lining of electrothermal furnaces used for the manufacture of carbon disulphide from liquid sulphur and charcoal at between 800 and l000°C are severely attacked during the process. A mineralogical study of samples of eroded refractory material disclosed that carbon disulphide had penetrated the lining, causing the precipitation of sulphides and carbon, and the decomposition of mullite, a major constituent of the lining, to corundum and amorphous silica. Calcium, iron, titanium, and chromium are undesirable cations in a refractory that is used in furnaces for the production of carbon disulphide, since they react readily with this substance. A series of tests, in which samples were exposed to different amounts of carbon disulphide for various residence times and at different temperatures, was carried out with eight types of aluminosilicate-based castable and brick refractory materials, to compare their resistance to attack by carbon disulphide. Mineralogical investigation of the test cores showed that castable refractory materials are unsuitable for this type of process because of the presence of calcium aluminates and other impurities in the cement. Of all the refractories that were tested, a mullite brick of low porosity, containing a minimum amount of impurities, appeared to be the most suitable for use in this type of operation.

Jan 1, 1989

By Garry W. Warren

The brass foundry industry produces a significant amount of waste sand containing Cu, Zn and Pb which is often classified as a hazardous waste due to Pb content. The potential application of a hydrometallurgical process to treat the sand by extracting metal values and thus detoxifying the material has been investigated. The process involves leaching of metal values followed by cementation. The emphasis of this investigation was on the leaching step, although some preliminary cementation experiments have been performed. In order for any alternative treatment scheme to be successful, the smaller size fractions of the sand must be addressed. Experiments have been performed on five individual size fractions using various lixiviants HCI, acetic acid and HCI/NaCI. Cu extraction was found to be slower than either Zn or Pb. Results obtained in this investigation indicate that copper is present in two forms, an oxide form which dissolves rapidly and is insensitive to the level of oxygen, and a less soluble form, probably metallic which dissolves more slowly and requires an oxidizing agent. The presence or absence of oxygen had no influence on the rate of Zn dissolution indicating that zinc is present mostly in oxide form. Toxicity Characteristic Leaching Procedure (TCLP) tests showed that residues could be produced which meet the toxicity limit for lead. Preliminary cementation experiments have also demonstrated the feasibility of Cu and Pb recovery.

Jan 1, 1991

By Jerome Feinman, Sven O. Santen

"The principles involved in the generation and application of plasma energy are reviewed briefly and the major developments in commercial and semi-commercial primary metal and alloy production are described and discussed in broad outline, with emphasis on present performance and future potential. New concepts in the application of plasma energy in primary operations are described with emphasis on the expected advantages over conventional technology and the problems that have to be solved to enable effective implementation.IntroductionThe use of plasma energy in industrial processes is generally considered to have started in 1905 with the operation of the Birkeland process for nitrogen fixation for fertilizer production. Although it seems logical to apply plasma energy to metallurgical processes, which also usually require considerable energy at high temperature levels, serious development work along these lines did not begin until the early 1970's. The reasons for this hiatus are associated in part with recognized difficulties in applying plasma energy in processes involving tonnage quantities of solids in severe industrial environments and the delicate nature of the earlier plasma generators. Another, and perhaps overriding factor, is the fairly steady improvement in efficiency and economy of most primary metal producing processes by conventional developments and modifications through the 1950's and 60's. Examples of these evolutionary changes include burden preparation and fuel injection in blast furnace applications and prereduction treatments in ferroalloy operations. By the end of the 1970's most primary metal producing processes had been optimized close to the limit, at least in terms of those operations that were able and willing to implement the developed improvements. In this context, plasma energy offered the possibility to achieve further significant improvements in primary operations where conventional means were exhausted."

Jan 1, 1988

By Ted H. Eyde

Natural Zeolites are a less expensive and in certain applications a superior alternative to organic ion exchange resins. Mining and metallurgical waste streams are difficult to treat because the effluents which contain potentially valuable heavy metals such as copper, lead, and silver are often highly acidic and contain significant quantities of suspended solids. Under rigorous operational conditions, certain natural zeolites can remove the metals, which if desired can be recovered by either elution or conventional smelting techniques. There are significant differences in cation exchange rate, selectivity and capacity as well as resistance to either high or low pH, blocking cations and tolerance to elevated or depressed temperature and pressure not only between different zeolite minerals but between the same mineral from different deposits. Applying natural zeolites to the treatment of mining and metallurgical waste streams depends on matching the specific zeolite to the effluent by characterization of the zeolite minerals.

Jan 1, 1993

By Daniel C. McLean

Extraction data for Cu, Zn and Fe were obtained from 4.5" and 10" columns using massive sulfide ore and natural acid mine water. The purpose was to determine if recycling of solution through the column would produce leach liquors of 4 g/l Cu and Zn at extraction rates of 1 g/l per pass at typical flow rates of 0.002 to 0.006 gpm/sq.ft. Test results exceeded expectations. Cu and Zn concentrations of 4 g/l were obtrained within 4 to 6 cycles. Concentrations greater than 6 g/l Cu and 8 g/l Zn were reached within 10 cycles. Concentrations of greater than 40 g/l of Fe and free sulfuric acid were obtained with no decrease in biological activity being observed. No reagents were used.

Jan 1, 1995

By John J. Mahoney, George P. Demopoulos, Matthew T. Bohan

In recent times processing of arsenic-laden complex ores and heightened awareness of the detrimental health effects of arsenic has put an increasing burden on metallurgical operations to remove arsenic from processes for disposal in an environmentally stable form. At present, arsenic is removed and prepared for storage by precipitation of insoluble secondary arsenic-bearing minerals. It has been suggested that Ca(II)-Fe(III)-As(V) phases resembling the natural mineral yukonite, under certain conditions, may have a role in controlling arsenic pore water concentrations in arsenical waste storage facilities. In this study, a previous synthesis method of yukonite (Ca3Fe5(AsO4)4(OH)9⋅4H2O) is revisited and new solubility/stability data is presented based on a modified method.

Jan 1, 2014

By Wolfgang Steffes-Tun

Pyrite ore concentrate from the Meggen mine (FRG) , which contains about 0 300 400 ppm thallium, is roasted in a fluid bed furnace at 1000 -1100 C to form sulfur dioxide and ash consisting mainly of hematite. Subsequently, the sulfur dioxide is separated from the ash or dust during several steps while cooling to about 250oC. The pyrite ash fractions show decreasing grain size down to 5 pm, a pH-decrease down to 2,4 and a marked enrichment of arsenic and thallium by a factor of 12. In the final fraction, the hot electroprecipitator dust of the dump (EGR), minute crystals of thallium-containing jarosite can be detected by analytical transmission electorn microscopy (TEM). Under oxidizing, acid conditions, jarosite may be a possible "reservoir mineral" for immobilizing thallium.

Jan 1, 1989

By Goren Lindkvist

Elkem has a small industrial scale. Muti-Purpose furnace at the MEFOS Metallurgical Research Facility in Lulea, Sweden. The furnace is 2 meters in diameter with installed power of 4.8 MVA, equipped with oil coiled freeze lining, gas tight electrode seals and feed chutes and a slag flow control for continuous tapping. During tests in June, 1991, the furnace was continuously operated on a high silica slag at loads from 1.5 to 4,0 MW. The slag was then charges to a low silica, high iron and lime composition. Steel plant dust was added, smelted and reduced. The slag was made more ceramic by adding alumobrick and alumina. Data from the start-up and initial operating phase of the, Elkem EAF dust plant at Laclede Steel will also reviewed.

Jan 1, 1992

By S. J. Hogan, T. William

"By the year 2000, the steel industry, not only in the United States but in the rest of the world, will undergo significant changes. On the other hand, there will be a number of areas in which change will be minimal.The current capacity of the industry worldwide is approximately 800-810 million metric tons. This may grow to some extent, as Third World countries install capacity. However, much of it will be neutralized as the industrialized countries shrink their current capacities.There will be several breakthroughs in terms of technology, some of which deal with the production of iron outside of the blast furnace. However, these processes will not be far enough advanced by that time to replace the blast furnace, rather they will supplement it.In terms of steelmaking and the subsequent rolling process, there should be a number of basic improvements. The strip mills will roll sheets with a very slight variance in gauge, which will give the customers a better product for automatic stamping machines. Ordinary carbon steel, in a number of instances, will be replaced by high-strength, low-alloy steel, which will reduce the tonnage necessary for present-day applications, such as construction.The corporate organization will be significantly changed as joint ventures and mergers will reduce the number of companies, as well as facilities in operation. This will enable the industry to reduce its capital investment and improve operating costs, so that it will be able more effectively to compete with other materials, such as plastics, cement, aluminum, etc."

Jan 1, 1988

By A. Siegmund, Gerhard Martin

The recycling of metal containing scrap is a common practice in the industry and has a long tradition. . In rec~nt years, this philosophy has been transferred to organic materials, in particular to thermoplastic polymers. BSB . Recycling GmbH, a company with a long experience in the treatment and recovery of lead from battery scrap,· had recognized this exploitation at an early stage and challenged it by a consequent continuation of the idea to recycle materials other than metals without degradation and maintaining the quality. These efforts resulted in an economic and environmentally acceptable solution producing high quality polypropylene compounds at BSB beside lead and lead alloys from battery scrap. The raw material fair the production of polypropylene compounds is shredded plastics from the separated casings of spent lead-acid batteries. The production of polypropylene with specific physical and mechanical properties is carried out by the accurate dosing of organic as well as inorganic additives. The result of the procedure is a novel product group "Seculene PP", a registered trademark of BSB Recycling GrnbH.

Jan 1, 2000

By Edgar E. Vidal, Keith Smith, James A. Yurko

Beryllium, like many other reactive metals, is extracted from a halide (generally BeF2) using magnesiothermic reduction, also known as the Kroll process. The beryllium is produced in a molten state, which when solidified resemble "pebbles". Although beryllium is used in limited quantities compared to other metals (< 100 Mt/annual), it is a critical material for the nuclear, defense/aerospace, and large science markets because of its unique nuclear and mechanical properties. Beryllium processing has unique environmental, health, and safety concerns which must be handled appropriately in the 21st century from a worker and environmental safety perspective, and must be designed with this first in mind. In 2011, Materion began operations of its new Kroll plant – informally known as the “Pebbles Plant” - in Elmore, Ohio. The plant was majority funded by a U.S. Department of Defense Production Act (DPA) Title III grant, which is a unique government/industry partnership program to, "create assured, affordable, and commercially viable production capabilities and capacities for items essential for national defense." After a twelve year hiatus from primary beryllium production, Materion has reentered its extraction business and has relearned how to make pebbles. The purpose of this presentation is to give an overview on beryllium extraction and discuss some of the unique aspects of building and operating a safe beryllium facility during the production scale-up phase.

Jan 1, 2015