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By Carlos Antonio da Silva

Steel refining reactors based on chemical heating are being used as an alternative to ladle furnaces, They show a high degree of flexibility in respect to heating rate in addition to carrying out refining reactions such as de-S, inclusion removal, alloying etc. IR-UT and CAS-OB are examples of such reactors. Their performance is dependent upon geometrical characteristics as well as operational conditions which determine the flow field inside the vessel. A physical model of the IR-UT process of the Companhia Siderúrgica de Tubarão, steel plant located in Serra, Espirito Santo, Brazil, was developed to assess the features of the flow field and its influence on the metallurgical behavior. Results of the physical model were used to optimize the process parameters in the industrial unit.

Jan 1, 2003

By Aline Maria dos Santos Teixeira, Francisco Manoel dos Santos Garrido, Joao Alves Sampaio, Marta Eloisa Medeiros

"Rocks for crops is a natural practice for soils fertilization which consists on adding rocks to the soil while water decomposes the rock, through chemical weathering, and gradually releases nutrients to the soil solution. This practice can be considered an alternative to the low production of potassium fertilizers in Brazil. In this context, the phonolite rock was characterized in order to evaluate its application as an alternative source of nutrients to the Brazilian agriculture. The phonolite studied is an igneous, volcanic rock with alkaline character that is chemically composed of a high grade of potassium due to the presence of feldspar minerals. In order to quantify the minerals present in the sample, characterization was carried out using several techniques such as X-ray diffraction, X-ray fluorescence and scanning electron microscopy.IntroductionBrazilian soils are generally acidic and nutrient poor due to the tropical climate in which high temperatures and intense rainfall favor a rapid decomposition of the rocks that from the soil. And as agriculture is one of the main bases of the country's economy, large amounts of fertilizer are used to make the soil productive.Although Brazil has large reserves of potassium, the demand for potash fertilizer is higher than the national supply, which makes the country dependent on fertilizer imports, especially in the form of potassium chloride. Thus, we must look for economic alternatives to traditional fertilizer [1].Stonemeal is a natural practice for soil fertilization that consists in adding basic or ultrabasic rocks to the soil so that water, through chemical weathering, decomposes the rock while it gradually releases nutrients."

Jan 1, 2011

By Jim Sarvinis, Rory Hynes, Elizabet Cruz, Kerry McKenna, Maytinee Vatanakul

"Energy efficiency improvements achieved using heat recovery processes offer benefits to both the business case and environmental impact of metallurgical facilities. Global demand drives the development of lower and lower grade ore bodies. This trend results in higher energy intensity and consequently increased waste heat. Waste heat boilers and Organic Rankine Cycle (ORC) processes are becoming cost competitive methods of utilizing this waste heat.This study analyzes heat recovery from available sources to produce power using, • High grade: waste heat boiler and steam turbine generator. This system will produce electricity, and/or process steam.• Low grade: ORC to produce electricity. The cycle is well adapted to low- moderate temperature heat sources.Processes used in metallurgical plants, such as hot exhaust streams, cooling and condensers could benefit from application of these systems.The study demonstrates:• The energy and cost saving potential of waste heat recovery technologies,• The environmental benefit.IntroductionIn recent decades, process intensification has resulted in increased productivity from unit operations such as kilns, fluidized bed reactors and smelting furnaces and decreased unit operating costs. In the coming decades, the industry’s challenge will be to continue this trend while at the same time decreasing the consumption of fossil fuels and further reducing the environmental impact of its processes.The U.S. Department of Energy reports that available waste heat sources in industry, which is approximately seven quadrillion BTU (~7,400 PJ/y), exceeds the current production of all renewable power sources combined. In Canada there are about 2,300 PJ/y of available waste heat, with the pulp and paper, metallurgy, chemical/petrochemical and oil refining industries the main players. Natural Resources Canada (NRCan)9 has estimated that about 25% of that heat could be recoverable using existing technologies, which in turn, represents a reduction of 27 Mt/y of Green House Gas (GHG) emissions, plus considerable water savings due to lower water cooling requirements and less fossil fuel consumption."

Jan 1, 2011

By R. J. Batterham

This paper sets the scene for the Australian-Asian Pacific Course and Conference on Pyrometallurgy for complex materials and wastes. The relentless presence of competitiveness is rehearsed as the source of the current trends towards continuous improvement and benchmarking. While this might be expected to lead to more spending on pyrometallurgy, the opposite appears to be the case. The paper examines the reasons and suggests that we face an increasing challenge for selective developments that can lead to sustainable competitive advantage - both in mineral and in waste processing.

Jan 1, 1994

By S. Mattlgod

Self-assembled monolayers on mesoporous supports (SAMMS) have been developed for the removal of heavy metals and some transition metals. The thiol functional groups were assembled on the internal and external surfaces of mesoporous silica with a uniform pore size of about 55 A. The mesoporous supports provide high surface area (>900 m2/g) needed for high metal loading in chemical separation. Self-assembled monolayers of organic molecules bond to the ceramic substrate with prescribed densities, and with terminal functional groups for excellent molecular selectivity. The unique characteristics include: (1) High metal absorption capacity, up to 3.2 mmol/g of SAMMS. (2) Fast Hg-binding kinetics (reducing mercury concentration from 0.5 ppm to 0.5 ppb in less than 5 minutes). (3) High selectivity in the presence of a range of cations, anions, and organic species. (4) Applicability in both aqueous and non-aqueous solvents. (5) Flexibility in surface chemistry. The materials can be designed to adsorb heavy metals, transitional metals, and radionuclides. (6) Chemical stability, and potential for regeneration or waste storage. This paper discusses the results on mercury adsorption.

Jan 1, 1999

By Mark William Kennedy

"Electric furnaces containing high quantities of slag are applied in many areas of pyrometallurgy, often for smelting or slag cleaning. A variety of ratios or rules of thumb have been employed in the industry for the dimensioning of these vessels, in most cases with no clear technical basis.In this paper, several design guidelines are presented (electrode size, spacing, vessel dimensions, energy intensity, etc.) as an attempt to provide some technical basis for optimal dimensioning.Furnace heat generation is related to side wall copper cooler heat losses, in an attempt to establish a methodical design strategy particularly for minimum electrode to wall spacing for modern furnaces with cooled linings.Issues regarding the true nature of heat production in a slag furnace are discussed with regards to the possible impact on accurate modeling and design.IntroductionSlag furnaces have passed through a number of design 'generations' characterized by increasing energy intensities, improved electrode technologies and advancing development in their physical structure or 'furnace integrity' as shown in Table I f 1]. A 3rd generation furnace using ultra-high-power (UHP) graphite electrodes is shown in Figure 1, as a generic example of the types of physical structures present in modern slag furnace designs [1]."

Jan 1, 2012

By Wu Liu

A modified falling ball technique for measuring the viscosity of liquids is described. It consists of recording the weight vs. time of a crucible holding the liquid of unknown viscosity, as a solid ball, or liquid drop, is let to fall through the liquid. This method does not require measurements at constant terminal velocity, as the conventional falling ball technique. Also, measurements do not depend on visual observation, which is not possible in opaque liquids or containers. The effect of process parameters on the utility of this method and its potential application to liquid systems of metallurgical interest were analyzed theoretically. The paper also com- pares the gravimetric method to the conventional falling ball technique for measuring viscosity.

Jan 1, 1992

By Wei Yu, Tiejun Chun, Jian Pan, Deqing Zhu

In this paper, the technology of producing fluxed pellets by using hydrated lime as binder instead of bentonite was carried out. Green balls with 0.8% bentonite and others with 2% hydrated lime were obtained under the same conditions of 1.5% coke, 1.45 basicity and balling at 8.5% moisture for 13 min in disc pelletizer. The properties of two types green balls were as follows: drop numbers of 4.8 to 5.0 times/0.5m, compressive strength of 19.7 to 24.2 N/pellet and thermal shock temperature of 280 to 385?, respectively. Comparing with bentonite as binder, the compressive strength of fired pellets with hydrated lime is elevated by 13.8% and climbs up to 3113 N/pellet under the following conditions: preheating at 1050? for 10 min and firing at 1300? for 15 min. The hydrated lime also improves the metallurgical performance of fired pellets. The reduction index was enhanced from 68.6% to 70.6%, RDI+3.15 increased from 90.1% to 98.8% and reduction swelling index dropped from 22.4% to 7.4%, respectively. Therefore, hydrated lime can not only replace bentonite as binder to enhance the firing behaviors of green balls, but also effectively improve the metallurgical performance of fluxed pellets which can be used as high quality feed for blast furnace.

Jan 1, 2011

By R. Harris

Blister copper melts of 800 g to 1000 g containing less than 1 wt % S and up to 3 wt % Ni were desulfurized at 1523 K in air or by a pure oxygen jet blown at 75,500 and 1000 cm3/min, from 1 cm above the melt. Rates of desulfurization and oxygen pickup were measured and visible surface phenomena were photographed and videotaped. It was observed that SO2 was evolved from Cu-S melts in a manner reminiscent of the effervescence seen in carbonated drinks. The effervescence lasted up to 20 minutes and resulted in the ejection of material up to a height 50 cm above the melt surface. Sporadic discharge of large bubbles was also observed in a Ni containing melt top-blown with oxygen at 1000 cm3/min. The Cu-S melts top-blown with oxygen experienced faster sulfur elimination as compared to stagnant melts exposed to air and experienced only a single period of turbulent SO2 evolution, which occurred almost immediately after oxygen injection commenced. The Cu-S melts exposed to air experienced multiple episodes of effervescence. The stagnant blister copper melt containing nickel did not exhibit effervescent behaviour and experienced a lower rate of sulfur elimination compared to Cu-S melts tested under similar conditions. The present article examines the role of surface phenomena in determining the observed behaviour.

Jan 1, 1999

By Edwin Adoyi Ali, Zainab Shehu Aliyu, Adele Dzikwi Garkida, Muhammad Dauda

Feldspar from Matari, Nigeria was analyzed using SEM, XRD and XRF techniques for microstructural analysis, mineral phase analysis and chemical composition analysis respectively. Qualitative and quantitative XRD analyses revealed the presence of microcline 59.6%, albite 34.7% and quartz 5.71%. The XRF results showed that the feldspar contains 67.32% SiO2, 17.54% Al2O3, 11.33% K2O, 2.75% Na2O, 0.12% CaO, 0.01% MgO, 0.02% MnO2, 0.10% Fe2O3, 0.00% Ti2O, etc and 0.14% LOI. SEM/EDX analysis shows the presence of microcline feldspar as the dominant phase, exhibiting lamellar twinning. The XRD has also revealed that potash has the highest peak, indicating its high concentration. The 0.10% Fe2O3 present is within the permissible level (0.1-0.3%) for glass making and also within the potash feldspar specifications (0.17%). The Matari feldspar is a microcline type, rich in potash, alumina and silica, enabling it meet the standard specifications for alumino-silicate glass.

Jan 1, 2015

By G. A. Irons, D. Guo

"The average spout height and width produced by bottom gas injection in a water model of a steel ladle were measured with an image processing technique. It was revealed that the spout height could be described by a Gaussian curve. A combined SIMPLE -VOF model was developed to simulate the liquid surface and flow. The results showed that, though the model produced reasonable velocity distributions and free surface positions, the spout height due to the dynamic head of the rising liquid was substantially lower than observed, indicating that the bubble dynamics at the bath surface play an important role in spout height.IntroductionDue to the enormous importance of gas injection and stirring in metallurgical processes, there have been numerous publications on water and numerical modeling of such vessels. The free surface of the bath has received considerably less attention, despite its importance. At the free surface there are often important chemical phenomena occurring that require a good understanding of the fluid flow; these would include reoxidation of steel, metal splash and fume formation. Furthermore, to understand the details of slag-metal interactions such as slag entrainment, metal losses to slag and the transport phenomena associated with refining reactions, it is necessary to understand the plume and spout interactions first.There have been few experimental studies of the free surface of liquid in gas-injected ladles [1- 3], and even fewer on numerical modeling. Brimacombe and co-workers [1] studied the gas void fraction in the spout region, using a double-tip electrical resistance probe. This sensor cannot distinguish between gas in bubbles about to break and gas in the freeboard. Thus, it is a matter of judgement as to the position of the free surface. Schwerdtfeger and co-workers [2] used a single probe configuration with a wire and a counter electrode in the liquid, so that the height of the continuous liquid phase was unambiguously determined. Irons and co-workers [3] measured the spout height by ultrasonic and electrical capacitance techniques. These techniques were as reliable as the resistance techniques, but were restricted to low flow rates."

Jan 1, 2001

By D. K. Panda

The behavior of single drops with gas evolution at the interface is of interest because this is one of the important reactions that occur in oxygen steelmaking vessels, where a large amount of iron-carbon drops are dispersed in an oxidizing slag. The carbon dissolved in these drops, reacts with the slag to form CO, which is evolved as a gaseous phase. A room- temperature model was used to study the nature of this type of reaction including the effect of various factors such as viscosity and the presence of surface active impurities. Experiments were done for reacting drops over a wide size range to observe various regimes of behavior. Large single drops were levitated in a counter current flow to produce a sufficiently long residence time to allow the study of the various stages in the reaction. The emphasis of this work was to obtain photographic evidence of a high quality to describe all possible modes of behavior, and so a lot of effort was given to developing and perfecting experimental techniques.

Jan 1, 1994

By J. Schmidl

In non-ferrous metallurgy the service life of refractory materials typically ranges from several weeks up to three years or more and is strongly dependent on operating conditions. To support our customers with the most viable refractory solution for their needs RHI Magnesita follows a structured approach of thermo-chemical calculations, experimental evaluation from lab scale up to industrial field tests and post-mortem analysis of used refractory materials. This paper will give an overview of the RHI Magnesita refractory selection process and the most recent developments of the experimental setup for the so called HF-IF test. This is a dynamic corrosion test that allows to determine fundamental properties of different refractory material types under process conditions subjected with respective customers process materials. The HF-IF experimental procedure is an excellent tool to simulate refractory wear in industrial processes, diminishing risks associated with plant trials and support decision making to choose the optimal refractory solution for the customer.

By Entov Vladimir M., Gilmer R. Burgos, Andreas N. Alexandrou

"Processing of metal alloys in their mushy state represents a new trend in metal processing. As part of this process, known also as thixocasting, a specially prepared slurry at a temperature in the mushy region is injected into a die. Parts produced using this technology offer better mechanical properties than those produced by casting, and comparable to those of forged alloys.In thixocasting, semisolid slurries are highly concentrated suspensions of rounded rosette-like crystals in eutectic liquid. The mechanical behavior of the slurry is determined by the structure and properties of the skeleton formed by the alpha phase particles. The skeleton structure is almost never at equilibrium, and its evolution is, governed by a number of kinetic phenomena of different c11'aracteristic time-scales. Therefore, the skeleton structure depends on the mechanical and thermal history of the material. As a result of these kinetic processes, the rheological properties of the material, such as effective viscosity and yield stress, decrease with structure breakdown, and increase with its development. In the present investigation, the behavior of semisolid slurries during processing is modeled using the conservation equations, and a Herschel-Bulkley fluid model. The rheological parameters are assumed to be functions of the solid volume fraction, and of a structural parameter that changes with processing history. The evolution of the structural parameter is described by a first order kinetic differential equation that relates the rate of build-up and break-down of the solid"

Jan 1, 2000

By Vanessa M. Torres

Cia. Vale do Rio Doce is currently developing Niquel do Vermelho Project. The laterite deposit is located at Carajas Mineral Province at less than 15 km from Sossego Copper Project, scheduled for start-up in 2004. The available infrastructure, includes paved roads, large capacity railroad and port complex owned by CVRD, power supply and good quality water. The project was evaluated in the past for ferronickel production. In the late 1990s, CVRD switched its attention to investigating the usage of pressure acid leaching. The combination of good metallurgical behaviour for pressure acid leach (PAL) process route with reasonable mineable grades, and existing infrastructure justified the start of engineering studies in 2002. The project approach at the engineering phase is based on the dual objective of minimizing risks while maximizing project profitability and value. CVRD is currently completing the Niquel do Vermelho prefeasibility study. This paper outlines the main outcomes of the study and future perspectives for the project.

Jan 1, 2004

By Peter Stiaszny, Andrej Samoilov, Yuri Titovets, Gottfried Hribernig, Nikolai Zolotorevskii

"The model has been developed to simultaneously predict both transformation product portions and mean ferrite grain size from the same common · principles as a result of the austenite decomposition during any cooling path of dual phase steels. The transformation products considered are polygonal ferrite, pearlite, bainite and martensite. The model is based on the classical equations of nucleation-growth theory and also contains some empirical parameters. The chemical driving forces for nucleation and composition of elements at the phase interfaces are derived by computation thermodynamics. The empirical parameters related to the model were determined on the basis of a series of austenite transformation dilatometric curves and grain size measurements for continuous and interrupted cooling of several steel types. The model is aimed to predict phase transformation in the complex cooling conditions of the run-out table of the hot strip mill at YOEST-ALPINE STAHL LINZ GmbH as a part of the computer aided system for prediction and on-line controlling of the mechanical properties of hot-rolled strip.IntroductionThe term ""dual phase steels"" is used to refer to a steel consisting essentially of a dispersion of martensite in a fine-grained ferrite matrix. These steels are of increasing technological interest since they provide a better combination of strength and ductility than any other conventional steel sheet material. The strength is important because it offers an opportunity to produce lighter components, while good ductility is needed to permit easy forming of components. It is generally recognized that martensite plays an important role in determining the strength level of dual phase steels. A full understanding of the role played by the phases in determining such characteristics requires investigating in more detail how to optimize the martensite level of such steels, while maintaining good ductility remains the subject of continued research in the industry."

Jan 1, 2000

By M. Demuth, B. Holleis, M. Potesser, D. Spoljaric

"In 2005, Messer Group established a technology competence centre for metallurgy in Gumpoldskirchen (Austria), with the aim to develop oxygen burners which satisfy today's and upcoming standards of legislation as well as customer requirements. With the assistance of the Development Sponsorship Fund (FFF) of Austria, cooperation with the University of Leoben was agreed on. With the long term experience of the Gas-Warme-Institut ""GWI"" in Essen (Germany) and the University of Leoben, different new burners have been developed.The efficiency of industrial combustion processes can be increased in two ways (which can be seen in Figure 1 ), either by preheating the fuel and combustion air or by adding oxygen. Due to the high 79 % Nz ballast in air combustion, only low flame temperatures can be reached. This results in high heat loss in the exhaust gas, caused by the low combustion efficiency. Oxygen can be introduced into the combustion chamber using different techniques:• Oxygen fuel burners• Direct oxygen injection into the fuel air flame• Underlaying of the fuel air flame• Enrichment of the combustion airIn Figure 2, the theoretical flame temperature for the stoichiometrical combustion of natural gas is plotted as a function of oxygen enrichment. Therefore, it can be concluded that even low enrichment values produce higher flame temperatures and result in higher combustion efficiency."

Jan 1, 2012

By J. T. Stanley

The identification of crystal phases and crystal chemistry can be critical to understanding the mechanisms of waste material interaction with native soils. Understanding these mechanisms can suggest correct methods for remediation and treatment. A program is outlined and examples are given of the development of effective techniques for rapid phase identification of environmental samples using electron microscopy. The program concentrates on the development of integrated object oriented software to aid rapid searching of online databases and rapid simulation of potential crystal diffraction patterns. Examples come from dried sludge taken from a former hard-chrome plating facility.

Jan 1, 1993

By K. Fukushima, K. Baba, H. Kurokawa, M. Yamagiwa

"The Toyo smelter has expanded its anode production capacity from 126,500 to 239,000 t/year by introducing technical oxygen into blast air for flash and converter furnaces and improving smelting facilities. Significant efforts were made in the expansion not to increase the number of workers, which mean development of some automation systems for the copper converters and anode casting wheel. The efforts have resulted in the above-mentioned increase in productivity and a saving of production cost as well as a decrease in the number of workers for the anode casting operation.IntroductionThe Toyo smelter has been performing a highly stable and pollution free operation since its commencement in 1971 (1). Its distinctive features are the on-line control by process computer (2) and the high productivity without trouble. But owing to the so-called oil crisis in 1979, we were faced with a sharp increase in production cost. To decrease the production cost, some measures for saving of energy were planned and carried out, such as conversion from oil to coal in a flash furnace (3), the heat recovery from converter slag and the introduction of technical oxygen in blast air with the intention of energy saving as much as possible.The first increase in production capacity and some savings of production cost were attained in 1982 by the introduction of technical oxygen in blast air for the flash furnace without major modification of the furnace as shown in Table I. The capacity of an oxygen plant is 7,800 Nm3/H as 90% O2 . Part of oxygen from the plant is also supplied to tuyeres of copper converters through an oxygen holding tank with a volume of 830 m3 at 7 kg/cm2-G."

Jan 1, 1989

By Stanko Nikolic

One of the keys to success in process development is incremental scale-up, allowing for potential problems to be identified and rectified. The ISASMELT™top submerged lance (TSL) process was developed to maturity using this method by Mount Isa Mines, now owned by Glencore. Commercialization only occurred once the process had been proven on each scale and as a result the ISASMELT™ technology now operates successfully around the world. An important parameter in the evolution of the technology has been the furnace campaign life. The initial commercial scale furnaces had minimal water-cooling. Although this led to shorter campaign lives, an extended development program resulted in the achievement of four-year campaign lives, without any water cooling. In tandem to the refractory designs Glencore Technology, supplier of the TSL technology, has progressed cooled copper lining designs for application to both the ISASMELT™ and ISACONVERT™ furnaces allowing for ultimate flexibility in the lining choice. This allows each ISASMELT™ operating site to minimize their overall life-cycle costs by balancing their campaign life with lining costs, energy inputs, and other shutdown requirements.