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By K. Narayan Prabhu, W. D. Griffiths

"Heat transfer during the unidirectional solidification of a cast iron alloy against cast iron chills was investigated using an inverse modelling approach. Chills of thickness 100 mm and 10 mm were used, to simulate gravity die cruiting conditions and the use of chills in sand moulds. In both cases transient heat transfer, measured by the interfacial heat flux and heat transfer coeffieient; declined from initially high values in the first few seconds of solidification, to values about an order of magnitude lower which persisted for the remainder of the experiments. In the case of the thin chill it became saturated with heat until it was no longer in a position to extract further heat from ·the casting. These results were interpreted by studying the resistance to heat transfer from the casting offered by the ·casting-chill interface and the chill itself for example, the thermal resistance of the casting-chill interface can be influenced by the deformation of their respective surfaces and their subsequent relationship.IntroductionDie casting cast iron offers several advantages such as energy savings, higher mould yield, and better surface quality over the sand casting process1 • The process is· environmentally' friendly because of the elimination of the sand. However the design and construction of metallic moulds is expensive and a faulty die design may result in a defective casting: A simulation based process design of die castings would enable die designers and solidification modellings to try better designs of dies on the computer and arrive at a cost effective solution more quickly. This has numerous benefits for the die caster, as he would be able to produce sound castings with very short lead times.The success of a solidification model to predict accurately the thermal history and the location of hot, spots inside a solidifying casting depends to a large extent on the heat transfer data prescribed at the metal/mould interface. Many measurements of the heat transfer coeffident (or the heat flux) between a solidifying aluminum alloy and a chill have shown that the heat transfer coefficient is a function of most of the variables of the casting process2 - 8. However heat transfer studies during the solidification of ferrous alloys are rather limited. The high temperatures involved suggest that the contribution due to radiation heat transfer cannot be neglected."

Jan 1, 2000

By María Eugenia Castro, Silvia Galasso, Jorge Duca, Claudia Osuna, Ernesto Esparza

"We present a procedure for treatment of non-active solutions equivalent to the solutions obtained from dissolution of ionic exchange resins used in purification of a nuclear reactor primary cooling system containing Co, Ni, Cs and its isotropic varieties as main radioactivity source. Finally it is immobilized into a ferritic matrix by calcination which avoids its future leaching into environment.In order to achieve the objective of this treatment, a bivalent and a trivalent iron salt is added to the solution. Then, either a base or an acid is added, depending on the initial pH of the treated solution, with a Cs precipitating additive in order to reduce Co and Cs by precipitation, flocculation and adsorption. Controlling the amount of precipitating reactives it is possible to modify the activity/volume rate becoming a medium into a low radioactivity waste.The leaching test result applied over the ferritic sample is lower than the minimum limit established by law. Therefore, it can be kept safely in a interim storage."

Jan 1, 2008

By K. J. Martchek

"This introductory presentation will highlight recent efforts to quantify the positive value of recycling metals such as aluminum, magnesium, lead, zinc, nickel and copper in relation to the three pillars of ""sustainable development"" - environmental protection, economic development and improve social consequences.This presentation will provide an overview of life cycle assessment profiles increasingly being utilized by customers, regulators and environmental advocacy groups to holistically evaluate the environmental performance of materials and products. The environmental profiles of prodi.lcts containing recycled metal will be presented based on rules established by the International Organization for Standardization (ISO).Significant to the life cycle profile of metal products is recent confirmation. that recycling has the potential to reduce materials production energy consumption by 95% for aluminum, 80""/o for magnesium and lead, 75% for zinc, and 70% for copper. Furthermore, . ""metals are eminently and repeatedly recyclable, while maintaining all their properties (1 ). "" Their durability relative to many hydrocarbon based materials enhance .their life cycle performance. However, the persistence of metals when dispersed into our natural environmental makes recovery and recycling particularly important Overall, when considering life cycle effects, recycling is critical to a sustainable future for metal products.Finally, regional and international regulations will be highlighted which will effect the efficient recovery and recycle of metals and their overall contribution to environinental protection, economic development and the enhancement of society."

Jan 1, 2000

By Kenneth N. Han

Thermodynamic and kinetic aspects of nickel and cobalt leaching from metals. minerals and ores in various media have been reviewed and discussed in this paper. A kinetic model developed to delineate the leaching mechanisms for these metals has been discussed in view of experimental observations. The current review also includes the dissolution behavior of nickel and cobalt from various minerals such as oxides, sulrides. ocean floor manganese nodules, and laterites. A particular emphasis has been extended to similarities and differences of the dissolution behavior of these two metals in various media. The leaching of nickel as well as cobalt metal in acidic solutions and arnmoniacal solutions exhibits in most part mass transfer controlling. although at some pH's, chemical controlling or mixed controlling mechanisms seem to prevail. The leaching of nickel and cobalt from oxides in acids and ammoniacal solutions. on the other hand, can be described best by chemical controlling mechanisms.

Jan 1, 1993

By Zdzislaw Miczkowski

At KGHM Polska Miedz S.A, a direct flash smelting process is used for smelting of chalcocite concentrate for the production of blister copper. The paper presents a model of complex oxidation process of single concentrate grains smelted at KGHM. The description covers main chemical reactions, phenomena of heat and mass exchange inside the grains and between a grain and the surrounding space. In the model, two zones describing the course of process inside the grain were distinguished: ? The first one, which moves faster towards the centre of a grain, both organic and carbonate carbon are freed, The process takes place without the presence of oxygen and results in an increase of the temperature in the core of the particle. ?The second zone moves slower into the grain and the rate of the movement is determined by the presence of oxygen, In that zone the sulphur is eliminated and the oxidation of the organic compounds vapours moving from deeper layers of a grain takes place. Based on the results of laboratory tests, the coefficients that describe the oxygen transportation into the grain and decide the progress in the chemical reaction were determined, The paper contains the results of model calculations for single grains reacting in environment of various content of oxygen as well as the results of model calculations for the laboratory reactor system.

Jan 1, 2003

By S. B. Johnson

Keywords: Spray, Aluminum, Simulation A stochastic, droplet-resolved model has been developed to describe the behavior of a binary aluminum alloy spray during the spray-rolling process. In this process, a molten aluminum alloy is atomized and the resulting spray is deposited on the rolls of a twin-roll caster to produce aluminum strip. The one-way coupled spray model allows the prediction of spray characteristics such as enthalpy and solid fraction, and their distribution between the nozzle and the deposition surface. This paper outlines the model development and compares the predicted spray dynamics to PDI measurements performed in a controlled configuration. Predicted and measured droplet velocity and size distributions are presented for two points along the spray centerline along with predicted spray averaged specific enthalpy and solid fraction curves.

Jan 1, 2005

By Demaerel. J. P.

Arsenic plays a major role during electroreflning of copper. Both the arsenic content in the anode and the arsenic concentration of the electrolyte have, in conjunction with other impurities such as lead, antimony, bismuth and oxygen, a direct influence on the quality of the cathode. The mechanisms are currently slime. inclusion and precipitation of insoluble compounds in the bulk of the electrolyte. Arsenic has also been reported to have a depassivating effect on the anode. An influence on the anode slime adhesion has also been found. A literature survey is given and these data are compared with and completed by our own results based on lab and pilot scale experiments as well as on Olen tank.house practice.

Jan 1, 1987

By Markus A. Reuter, Robert Matusewicz

"Consumer products are a complex man-made mixture of sometimes in excess of 50 elements. In order to recover these complex mixtures of elements either as metals, compounds or energy requires versatile technology in physical separation but also smelting and energy recovery. This paper explores this by referring to the innovative application of Top Submerged Lance (TSL) technology and associated theoretical and environmental aspects to process (recycle) post consumer materials and industrial intermediate products and residues. A diversity of applications has been tested in Ausmelt’s pilot plant in Dandenong and many have gone to commercial scale globally. This paper reviews the varied applications ranging from e-waste recycling, lead and NiCd battery recycling, metals recovery from slags, zinc leach residue processing, electric arc furnace (EAF) dust, Municipal Waste Incinerator bottom ash processing, carbon containing residues such as retort ashes and spent pot liner from the aluminium production process as well as use of the technology for materials such as automotive shredder residue (ASR) and plastics. Introduction The modern resource cycle is a link between primary production of metals linked to the recycling of post-consumer goods. The sometimes complex combinations of materials and metals in consumer products such as televisions depicted by Figure 1, does require a range of technology to recover materials, metals and energy for reuse and/or recycling in an economically feasible as well as environmentally friendly manner."

Jan 1, 2008

By J. Pesl, U. Kemey, F. Sauert

"The CONTOP® smelting cyclone is a water-cooled, upright, high-intensity smelting reactor. The technology for the reactor was initially developed and brought into industrial-scale operation in the area of non-ferrous metallurgy. The two largest smelting cyclones were built with a capacity of 32 tons per hour of copper concentrate mix.The newest industrial CONTOP® plant treats up to five tons per hour of zinc-bearing residues including EAF dust. The highly concentrated zinc-lead oxide produced is sold to the zinc industry. The slag fulfills the leaching criteria and is used in waterway construction. The heat transferred to the cyclone cooling system and the off-gas boiler produces steam from which power is generated in a turbine.V AI has erected a new CONTOP® demonstration plant at MEFOS, Lulea, Sweden. A zinc volatilization rate of 90% was achieved during hot commissioning with Swedish EAF dust.Treatment costs in the range of 85 to 100 EUR per ton were estimated in a feasibility study on the treatment of 73,000 and 57 ,000 tons EAF dust for a group of steelmaking mills in Southern Europe."

Jan 1, 2000

By Olga Karabelchtchikova

Keywords: Multipass grinding, Residual stress, Retained austenite, X-ray diffraction The study investigated residual stresses behaviors and their superposition effect in D2 dies for thread-rolling applications. A nested factorial experiment was applied to test hypotheses that the residual stresses profiles change due to combination of heat treatment and multipass grinding operations, and that certain patterns can be derived due to the memory relationship between pre-existing and final residual stresses distributions. The amount of the retained austenite along with residual stresses in variation with depth was measured using x-ray diffraction technique. Statistical analyses indicate that the proposed hypotheses hold. Residual stresses distributions as well as tensile peak location were found to be significantly influenced by the treatment parameters used. Unique characteristic patterns in the residual stresses profiles were observed due to multipass grinding technique across all experimental conditions. This finding suggested a plausible memory relationship between the cutting passes, and the causes of the foregoing results are further proposed and discussed.

Jan 1, 2005

By Robert E. Brown

Magnesium recycling has been used to recover both new scrap and old scrap. It was used extensively in Germany during WWII to expand the magnesium supply. There were a large number of magnesium recyclers in the US who got their start smelting old scrap, old airplanes and old waste dumps from the WWII build up. As the world magnesium industry dwindled, only a few companies were left that did magnesium recycling as a primary business. The sand foundries tended to recycle of their production scrap in their melting furnaces. Even the original die casters tended to put scrap directly back into melting furnaces at the die casting machines. As high purity alloys were developed and the use of die castings in automotive work increased, the tendency was to let the magnesium recyclers convert the scrap back to high quality ingot. Automotive use has grown because of the low density of magnesium. This property is the one of the biggest problems to overcome in shipping scrap. Gates and runners from die casting are very irregular shapes and it is very hard to load a truck with enough material to get a low shipping cost per pound. Recent new equipment companies have developed magnesium equipment that is specifically designed to recycle, refine and cast secondary magnesium metal. These melt cells are supplied as integrated units to magnesium casting sites. The cost and effectiveness of this approach will be discussed.

Jan 1, 2000

By Jukka Tuominen

The history of making blister copper in an Outokumpu Flash Smelting Furnace dates back to the late 1960?s, when Outokumpu first piloted the Outokumpu Direct Blister (ODB) process. The first commercial scale applications have been in use at Glogow, Poland, since 1978 and at Olympic Dam, Australia, since 1988. These applications utilize special concentrates, which are low in iron, and thus the formation of slag is also low. In 1995 the same principle was applied to smelting copper matte into blister copper in industrial scale at Kennecott Utah Copper. This application, the Kennecott-Outokumpu Flash Converting process, will celebrate its 10th anniversary of commercial scale operation this year. This paper outlines the development in efficiency and flexibility of Blister Flash Smelting processes compared to other smelting and converting options. The focus is on the economical aspects i.e. on the total feasibility of both greenfield investment projects and revamping of existing smelters.

Jan 1, 2005

By Chen Song

Keywords: Mixed extractant, Copper, Cobalt, Nickel, Synergistic effect During separation process of copper and cobalt from nickel sulphate solution, the effects of constitutions and compositions of mixed extractant D2EHPA and PC88-A or Cyanex 272, has been studied. In one step extraction cycle, the following results are obtained:[Ni]/[Co]>4000 and [Ni]/[Cu]>40000 in nickel sulphate solution, [Co]/[Ni]>1000 and [Co]/[Cu]>30000 in cobalt chlorinate solution, [Cu]/[Ni]>10000 and [Cu]/[Co]>200 in copper sulphate solution. It was elucidated that the above-mentioned synergistic mixtures can effectively separate cobalt and copper from nickel sulphate acid solution and achieve a greater synergistic effect.

Jan 1, 2005

By Hideharu Fukunaga, Jin Pan

"The recognition of Metal Matrix Composites (MMCs) as a means of providing high specific strength, high specific stiffness, excellent wear resistance, low thermal expansion and improved high temperature properties has led to a number of new processing, not previously used for plastic and ceramic matrix composites. As a primary fabricating process, the liquid methods are the major ones, which are reviewed briefly from the view of processing terminology. One of them, squeeze casting process is the most traditional and well-developed, because it is rapid, versatile and near-net shape production of materials. Two of new squeeze casting processes are presented to offer the hardness· controlled MMC and the· functionally graded MMCs as well as a newly developed whisker preform.I .IntroductionA large number of liquid processes and techniques including semi-solid liquid process are proposed. The most primitive process is ''pressure infiltration casting” of liquid metal into the fiber preform. It is called as follows depending on pressure and its source squeeze casting (1-4) by hydraulic ram, gas pressure infiltration casting (5, 6), vacuum infiltration, centrifugal casting (7), Lorentz-force-driven infiltration (8). The pressurizing on the liquid metal requests a large and stiff equipment, so pressureless infiltration technique has been developed using K2ZrF6 flux (9,10) while the mechanical properties are not high enough, and using H2 gas with Mg alloying element called pressureless infiltration casting (11-13), spontaneous infiltration process (14) and PRIMEX (15). In those processes, no severe reaction occurred between the reinforcement and matrix molten metal. In early l 990's, the reactive processing with pressure or without pressure, in which one material is totally transformed into another of the required shape, eq. assisted oxidation, has been developed, called reaction squeeze casting (16,17), DIMOX (18) reactive infiltration casting (19,20), and in-situ process (21,22). Die casting of SiCp/Al alloy (23,24) and thixocasting of SiCp/Mg alloy (25) are also applied to produce the machine component of MMCs."

Jan 1, 2000

By Neng-Wen Yu, Shau-Jun Zhu, Ji-He Wei

The desulfurization process by powder injection and blowing in the RH refining of molten steel and its mechanism have been considered and analyzed. Based on the two-resistance mass transfer theory and the mass balance of sulfur in the system, a kinetic model for the process has been developed. The related parameters of the model, including the mass transfer coefficients and the effective amount of powder in the molten steel being treated for desulfurization, have been more reasonably determined. Modeling and predictions of the process of injecting and blowing the lime-based powder flux under assumed operating modes with the different initial contents of sulfur and amounts of powder injected and blown in a RH degasser of 300 t capacity have been carried out using the model. The relevant circulation rate of the liquid steel and the powder injection and blowing rate were taken to be 100 t/min and 150 kg/min, respectively. The initial contents of sulfur in the liquid steel to be treated and the amounts of powder injection and blowing were respectively assumed to be 0.007, 0.006, 0.005, 0.004, 0.003, 0.002 mass-% and 10, 8, 6, 5, 4, 3 kg/t-steel. The total treatment time for desulfurization under each mode was set up at 24 min, equivalent to eight circulation cycles of the liquid steel to be treated. The results indicated that the predictions made with this model are in good agreement with some data of the industrial experiments and practice. Injecting and blowing the lime-based powder flux with the composition of 85 mass-% lime (CaO) + 15 mass-% fluorspar (CaF2) of 3-5 kg/t-steel, it is possible to decrease the sulfur content in the molten steel to ultralow level below (5-10)x10·4 mass-% from (60-80)x 10·4 mass-%. The total treatment time needed will appropriately be 12-20 min. Intensifying the powder injection and blowing operation and increasing the circulation rate of the liquid steel may effectively' raise the rate of the process in RH refining. The model may be expected to offer some useful information and a reliable basis for determining the reasonable process parameters and help in optimizing the technology of desulfurization by powder injection and blowing in the RH refining of molten steel.

Jan 1, 2000

By J. R. Donald

For processing copper, continuous converting has been successfully employed in a variety of locations, but for nickel, there has yet to be a successful commercial implementation of continuous converting technology. At Inco?s Copper Cliff smelter, there are specific requirements for the production of Bessemer matte relating to downstream processing that makes continuous converting for nickel mattes even more challenging. The nickel carbonyl refineries require very low iron levels in the matte, and the sulphur deficiency must be carefully controlled such that the appropriate quantity of PGM-rich metallics are produced from matte separation. The present paper outlines continuous converter technologies that have been implemented in copper, and evaluates their potential for nickel converting. The challenges of producing a Bessemer matte to the required specifications are discussed. The economic and environmental driving forces, and the challenges of justifying a novel technology in place of productive existing equipment, are discussed.

Jan 1, 2005

By Anja Pfennig, Axel Kranzmann, Phillip Zastrow

"Properties of pipe steels for CCS technology require resistance against the geothermal corrosive environment (heat, pressure, salinity of the aquifer, CO2-partial pressure). To predict the reliability of two different injection pipe steels with 13% chromium and 0.46% carbon (1.4034, X46Cr13) as well as 0.20% carbon (1.4021, X20Cr13) steel coupons were heat treated by comparable routines prior to long term corrosion experiment (60°C, 100 bar, artificial brine close to a CCS-site in the Northern German Basin, Germany). In general higher carbon content exhibits better corrosion resistance with respect to corrosion rate, amount of pits and maximum intrusion depth in the case of local corrosion. At 100 bar hardened steels with martensitic microstructure have the lowest corrosion rates with an average of 0.003 mm/a after 2000 h exposure time. At ambient pressure normalized steels show the lowest corrosion rates, indicating that the corrosion is driven by grain boundaries.IntroductionEngineering a geological on-shore saline aquifer CCS-site (CCS Carbon Capture and Storage [1-3]) corrosion of injection pipe steels may become an issue when emission gasses, e.g. from combustion processes of power plants, are compressed into deep geological layers [4-8]. Typically 42CrMo4 (1.7225, AISI 4140) is used for casing, and for injection pipe the steel X46Cr13 (1.4034, AISI 420 C) or X20Cr13 (1.4021, AISI 420 J) is used. Saline formations are the most favorable storage sites in Germany [9], because of their large potential storage volume and their common occurrence. Leakage of CO2 back into the atmosphere may be a problem in saline aquifer storage, especially around the water level within the borehole. Carbon dioxide corrosion may cause failure of pipelines and wells as known from the oil and gas industry [4,6,10,11, 12].From thermal energy production it is known, that the CO2-corrosion is sensitively dependent on alloy composition, contamination of alloy and media, environmental conditions like temperature, CO2 partial pressure, flow conditions and protective corrosion scales [6-8,13- 20]. Considering different environments, aquifer waters and pressures, the analyzed temperature regime between 40 °C to 60 °C is a critical temperature region well known for corrosion processes as shown by Pfennig et al. [21-23] and various other authors [10,24-28] (figure 1). Here a maximum around 4.7 mm/year was found for the pit intrusion depth of 13% Cr steel X46Cr13. Still this may be predicted by the rather conservative Norsok-Model used in the oil and gas industry to calculate surface corrosion rates of carbon steels [29]."

Jan 1, 2014

By Juliana Gutiérrez-Paredes

Keywords: Slag, chromium oxide, recovery, stainless steel Experimental and theoretical work was performed to estimate the effect of slag basicity and amount of reducing agents on the reduction of chromium oxide from the slag which interacted with molten steel at 1600°C. The slag system contained CaO, MgO, SiO2, CaF2 and Cr2O3 together with Fe-alloys (Fe-Si and Fe-Si-Mg). The CaF2 and MgO contents in the slags were 10 mass % each; Cr2O3 was 25%. The amount of the ferroalloys ranged from 12.5 to 50 g per 100 g of slag. The (CaO+MgO)/SiO2 ratio was held at 1 and 2. The Cr yield was determined using both Fe-alloys as reducing agents. Some estimations were made to determine the theoretical effect of temperature, slag basicity, (CaO+MgO)/SiO2, and amount of reducing agents in the slag on the chromium recovery. The FACT (Facility for the Analysis of Chemical Thermodynamics) computational package is used to determine the equilibrium between the slag and molten steel.

Jan 1, 2005

By B. L. Chulu

In the carbothermic reduction of lead sulfate to produce lead, the inclusion of soda ash (Na,CO,) in the charge provides for the control of sulfur dioxide in the effluent gas. An important mechanism in the process appears to be the carbothermic reduction of the sodium carbonate whereby sodium gas and carbon monoxide are produced. These intermediates then participate in the reduction of the lead sulfate to produce lead metal and stable sulfur species in the molten slag phase. In addition, there is some evidence that the presence of lead metal in the charge may also serve to increase the lead recovery in the process. These aspects were investigated by conducting laboratory-scale smelting tests with small charges (;3g), at 1173°K(9000C). Recovery did not exceed 74w% and the role of incipient lead metal in the charge could not be clearly assessed.

Jan 1, 1993

By Gregor Kücher

Lack of basic knowledge on the semi-direct recycling methods for hard metals hinders the application on an industrial scale. However, advantages like reduced expenses and lower environmental impact draw interest at future potentials. Consequently, this report aims to offer insight into the influence of varying bulky hard metal substrates during their lixiviation in acidic media with an oxidant. The statistical software Modde 11 assisted in the development of a design of experiments (DOE) for evaluation of the impact of average grain size, binder and tantalum carbide (TaC) content on the leaching characteristics. The other experimental parameters were constant. Among them were temperature, solution concentration and quantity, duration and substrate surface exposed to liquid volume. Eventually, prediction plots and factors of the computed model equation describe the effects of varying substrate qualities on leached binder metal and selectivity.