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By B. R. Westphal

The Integral Fast Reactor (IFR) concept being developed by Argonne National Laboratory is based on the pyrometallurgical processing of spent nuclear metallic fuel with subsequent fabrication into new reactor fuel by an injection casting process. During fabrication, a dilute scrap stream containing uranium alloy fines and broken quartz (Vycor) molds is produced. Waste characterization of this stream, developed by using present operating data and chemical analysis, was used to evaluate different uranium recovery methods and possible process variations for the return of the recovered metal. Two methods, comminution with size separation and electrostatic separation, have been tested and can successfully recover over 94% of the metal. Recycling the recovered metal to the injection casting process was evaluated for the different economic and process impacts. The physical waste parameters and the important separation process variables are discussed relative to their effects on the viability of recycling the material. A discussion of the criteria that is being used to establish the acceptable operating limits is also presented.

Jan 1, 1992

By Cang Daqiang, Bai Hao, Li Ning, Liu Xueting, Lu Xin, Zhao Lihua, Li Hongxu, Wei Wei

"Based on the principle of carbon balance, a model was built to calculate C02 emissions of each process and correspondingly the total course of production in iron and steel making. The data from a typical integrated steelworks in China was applied in the model. The results show that the BF and coking process account for the most emissions. Generally, C02 emissions in integrated steelworks depend on three factors, resources utilization efficiency, energy utilization efficiency and energy consumption structure, which were considered in an equation in this paper. Especially, General Emission Factor (GEF) was proposed to assess the relationship between C02 emissions and energy consumption. The results show that, higher GEF will result in more C02 emissions with the same energy consumption and in iron and steel making, the optimization of energy structure and development of eco-industrial park both have significant benefit on the carbon reduction.IntroductionThe Global Warming resulting from the increase of Greenhouse Gases (GHGs), especially C02, in the atmosphere has become the main reason of global climate change, and the carbon reduction is one of the most important ways for the sustainable development [1]. The iron and steel making is a manufacturing industry based on iron-coal high temperature chemical process, in which plenty of C02 is emitted. According to the data from IPCC (Intergovernmental Panel on Climate Change) in 2001, iron and steel making emitted about 650 million tons ofC02 every year, which is the fourth largest industry of the fossil energy consumption [2]. According to the data from EEA (European Enviromnent Agency) in 2006, iron and steel making is the largest source ofC02 emissions, which accounted for about 18% of the total C02 emissions in European manufacturing industry [3].It is estimated that the application of various well developed energy-saving technology, such as Coke Dry Quenching (CDQ), Top Pressure Recovery Turbine (TRT) and Coal Moisture Control (CMC), can make the C02 emissions reduced by 0.5%-3% in iron and steel making, and the further C02 emissions reduction can be achieved if more new energy saving technology is applied, such as sintering plant heat recovery, electricity generation with steam generated from converter and the various by-products gas and the hydrogen making process from COG[4,5]. In addition, the application of membrane separation technology is well expected in iron and steel making [6]. For example, the application of C02 Capture and Storage (CCS) in blast furnace combined with the Pure Oxygen Top Gas Recycled BF (TGRBF) technology can reduce the C02 ennss10ns greatly by about 50%-60% [4].That is, as a kind of C02 end-treatment technology, CCS applied with other technology of C02 recovery would be more meaningful. Actually, reduction of the C02 emissions by changing the structure of energy consumption and raw materials with new process of iron and steel making, such as direct reduction process or smelting reduction process [4,7,8], is the trend of ferrous metallurgical engineering, which is regarded as a kind of source-treatment technology. In this sense, source-treatment technology is more pivotal for the solution of carbon reduction in the future than the current popular energy saving technology. Hence, it is necessary to build the C02 emissions model based on the iron and steel making process and evaluate the relationship between the energy saving and C02 emission reduction."

Jan 1, 2012

By E. Fregeau-Wu

The mineralogy and grain size distribution of phases in a steelmaking slag and experimental products from the heating of the slag under various conditions were determined to explore the possibility of recycling of the iron and manganese to the blast furnace. The steelmaking slags consisted of three major phases: dicalcium silicate, dicalcium ferrite, and Mg-Mn-wustite. Most of the phosphorus was contained in the dicalcium silicate and to lesser extent in the dicalcium ferrite. Due to the fine grain size of the dicalcium silicate, grinding and magnetic separation required pretreatment to increase the grain size and hence the liberation. Experiments on a steelmaking slag were conducted by heating the slag to 1633-1748°K( and slow-cooling in an inert atmosphere at various rates with or without the addition of fluorspar (CaF2) as a flux. Grain size distribution analyses of the starting material and the slow-cooled products were performed using the SEM-IPP area scan method and the QEM*SEM linear scan method. Comparable and reproducible results were obtained on the same sample using both methods. A size versus volume percent plot showed the increased grain growth most effectively. Examples of the grain size distributions obtained were used to show that a higher soaking temperature prior to slow-cooling, a slower cooling rate, and the addition of fluorspar to the slag promoted grain growth.

Jan 1, 1989

Carbon injection into metallurgical slag is important in electric arc furnace (EAF) steelmaking for foamy slag practices and in nonferrous slag cleaning operations. The current publication presents kinetic data for coal injection into EAF slag to understand the interaction between injected carbon and metallurgical slag. Coal particles were injected into EAF slag and the kinetics were followed by gas and slag analysis. The results were analyzed, in terms of fundamental rate equations for each possible reaction step, as a function of temperature and slag composition.

Jan 1, 2003

By Jonkion M. Font

Due to the known disadvantages of the use of iron silicate slag in the nickel converting stage, i.e., high metal losses, high magnetite content, and low fixation of impurities in the slag, the development of the new proposed "ferrous calcium silicate slag" for smelting and converting processes of nickel is very promising. Hence, considering the successful experimental results of using CaO base slag for the nickel smelting process, a study based on a detailed comparison for the phase equilibrium, and the minor elements distribution between the Ni3S2-FeS matte with either FeOx-CaO or FeOX-Si02 base slag was investigated. The main results are summarized as: no difference in the nickel losses between both slags was found at high nickel content in the matte, and the fractional distribution analysis for arsenic and antimony pointed out their preferential fixation in the calcium ferrite slag rather than in the iron silicate slag. Considering the energy and pollution issues, the technical feasibility of using calcium ferrite slag in a converting process of the Bessemer matte will have a prominent future for the nickel industry.

Jan 1, 2003

By Ari I. Kogut

Impurity minerals in fluorspar ores and concentrates from a deposit in Southern Africa have been studied by reflected light, transmitted light, and cathodoluminescence microscopy. The principal impurities are quartz, calcite, aegirine, apatite, ankerite, magnetite, goethite, and synchysite [Ca(La,Ce,Nd)(C03l2Fj. Cathodoluminescence microscopy was found to be very useful in studying the character of the fluorite and especially for recognizing the presence of apatite and calcite impurities. Fluorite exhibits blue, calcite shows yellow, and apatite has white, light purple, and pink cathodoluminescence. The cathodoluminescent character of apatite varies with its geological environment and position in the orebody. The results of this microscopic study show that phosphorus present in flUorite concentrates occurs principally in binary locked apatite-fluorite particles. Successive fluorite cleaner concentrates contain progressively smaller amounts of locked apatite-fluorite particles. Free apatite has been effectively partitioned to the final tailings.

Jan 1, 1995

By Adolfo Pillihuaman Zambrano

Fe-Cr-C production is a very high electrical energy consuming process. Decrease up to 10% of this electrical energy is expected when self-reducing agglomerates are used. This research aims to understand how the synergetic effects are when stronger reductant, like Fe-Si, is substituted for coke in self reducing pellets. Brazilian chromites containing 41.2%Cr2O3 were mixed with petroleum coke and agglomerated with cement as the binder. Small amounts of 1%, 2% and 4% of Fe-75%Si were substituted for the equivalent petroleum coke, and pure silica plus hydrated lime were added for adjusting the slag composition. The mixture was pelletized, dried and submitted at 1773K up to complete the reactions. The results showed that the reduction reactions were 1.4 and 2 times faster with 1% and 2%Fe-Si addition, respectively, than with no addition. The microscopic analysis showed that it was formed a liquid phase, but the pellet did not collapse what indicates that the coalescence of the metallic phase depends on the dissolution of the pre-reduced particles of the chromites into slag.

Jan 1, 2008

By John R. FitzPatrick

The separation and purification of uranium from either nitric acid or hydrochloric acid media tan be accomplished by using either solvent extraction or ion-exchange. Over the past two years at Los Alamos, emerging programs are focused on recapturing the expertise required to do limited, small-quantity processing of enriched uranium. During this period of time, we have been investigating ion-exchange as a method for extraction/purification of uranium from acidic media. In addition, waste stream polishing is associated with this effort in order to achieve more complete removal of the uranium prior to recycle of the acid. Extraction chromatography has been demonstrated' to further polish the uranium from both nitric and hydrochloric acid media thus allowing for a more complete recovery of the actinide material and creation of less waste during the processing steps. We will discuss contact experiments for evaluation of eleven different resins for uranium removal from nitric acid, the evaluation (again by contact experiments) of uranium elution from the ion-exchange media by various chemicals, and small-scale experiments for the removal of 235U from nitric acid. Larger-scale (100-gram) flow experiments using depleted uranium, were done after the small-scale evaluation Of the selected resin. A discussion is also included concerning the shortcomings of the contact experiments and how the flow experiments were modified in order to overcome these problems. We will also discuss the application of ion-exchange for some specific process needs at Los Alamos Contact experiments were used to evaluate some commercially available solvent-impregnated resins in addition to evaluation of several resins of this type synthesized in our laboratory. These experiments' involved both nitric and hydrochloric acid media. The data from these experiments will be used to determine the column size and' amount of resin required to polish the waste stream produced by the ion-exchange process described above. Small-scale flow experiments will be described and data given on the mass balances achieved using this two step process. Future work for evaluation of new ion-exchange and solvent-impregnated resins as well as the search for new eluants will be discussed. Other future experiments for both processes, including large-scale experiments, will be discussed in detail.

Jan 1, 1996

By Mark Jolly, Xiaojun Dai

"Foundry engineers in the traditional foundry usually regard the quality of casting component as the most important issue and leave the energy saving or energy efficiency as the subsidiary one. This frequently causes disproportionate energy consumption as a result of the inefficient casting processes used and increases the production costs. This paper presents the novel CRIMSON aluminium casting process and compares its facility and melting process with traditional melt furnaces and aluminium alloy melting process. A real example is investigated to demonstrate quantitatively how the traditional foundry wastes energy and what the improvement of energy efficiency can be achieved using the new CRIMSON method. The results of this investigation will help the foundry engineer recognize the importance of energy saving and demonstrate how to use this new technology to reduce production costs and carbon footprint without decreasing the quality of the cast component.IntroductionAluminium melting in metal casting industry is an energy intensive process where it is estimated that the energy consumption is in the order of 1,700 ~ 4,700 kWh tonne-1 in using crucible and natural gas [1]. Different countries may use different energy resources for aluminium melting: in US the main energy resources are natural gas, electricity and coke [2] and in UK most of the foundry use electricity, gas and oil as energy resources [3]. Due to the pressure of rising energy price and the strict environment law, it is anticipated that under the right socioeconomic conditions, the efficiency optimisation of industrial process can be an important step toward increased industrial sustainability [4]. In metal casting industry the energy efficiency of a casting facility depends largely on the efficiency of its melting and heat treating performance. In association with the two performances, over 60 % of the total process energy costs are represented in a typical casting facility [5] where there are huge opportunities for metal casting industry to adopt the best energy practices for potential energy saving. How to ameliorate the current processes for increasing energy efficiency will have a vital effect on reducing the production costs and increasing the competitiveness. For instance, by implementing some state of the art technologies such as the CRIMSON method in aluminium alloy casting will make use of such opportunities."

Jan 1, 2011

By A. González

Arsenic is one of the main contaminants present in Chilean copper concentrates and its abatement represents a challenge for the process metallurgy, particularly under the strong environmental requirements in the global community. The possibility to form ferric arsenate directly from a gas phase by means of a heterogeneous reaction between an arsenic gas bearing and iron oxide was studied at laboratory scale. A thermodynamical analysis for the system Fe-As-O-S has been initially made, in order to obtain the stability conditions for the ferric arsenate or other FexAs2O2 type compounds. Experiments were made using an hematite sample suspended in a thermogravimetric device. AS4O6 gas generated from solid AS203 that was passed through the iron oxide sample and its instantaneous weight change was recorded directly. A kinetic study for the AS4O6 volatilization was made to control the gas composition. A chemical control between 300 and 600°C with an apparent activation energy of around 14 Kcal/mol As2O3 was determined. The samples after the reactions were chemically and XRD analysed. Arsenates detected corresponds to complex compounds. Results shows a dependence on temperature and oxygen content in the gas phase. The kinetics for iron arsenates formation is slow, reaching an arsenic capture of 6% after 80 minutes of reaction when an oxygen content of 50% is fed continuously at 800°C and 3,56% As in the gas. Experiences made at the same temperature but under higher oxygen content in a closed reactor, allowed arsenic capture close to 60%. For higher temperatures the capture is considerably lower.

Jan 1, 2003

By George Oprea, Tom Troczynski, Joe A. Rigby, Waiman Lo

The refractory lining of the tuyere line in Peirce Smith converters have usually much shorter life in service than the rest of the lining, above or below it. There are already recognized chemical, thermal and mechanical factors which contribute to the wear of the lining. Our study presents the experimental results on microstructural changes occurring on these tuyere line bricks in a nickelcopper converter. The experimental bricks, after use at the tuyere line, were investigated using SEM/EDS and XRD techniques, to identify the mineralogical changes due to interactions with the nickel-copper matte or fayalite type slag at the process temperatures. The microstructural changes were correlated with physical and mechanical properties of the brick before and after use and a wear mechanism was suggested. Although the matte does not theoretically react with the mineralogical components of the brick, a partial oxidation of the Ni-Cu sulphides was identified using a line analysis by SEM/EDS in the densified layer at the hot face, which allows for mineralogical changes at the matte-refractory interfaces, with a high probability of microcrack formation due to the thermal cycling during use. These microcracks were also identified to open through inter-granular fractures parallel to the hot face, which appeared to be the main cause of lost lining during use. The reactions between the fayalite slag and refractory brick could eventually play a role in chemical dissolution of the brick only in the superficial layer at the hot face, as no slag components were identified deep into the brick.

Jan 1, 2009

By Krishna Parameswaran

This paper discusses sustainability considerations in primary copper smelting using selected examples of practices at ASARCO LLC, an integrated U.S. primary copper producer. Using the classic Brundtland Commission definition of sustainable development, i.e., “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper discusses how copper mining and smelting practices can be made sustainable. The examples used to illustrate sustainability considerations include: (1) adoption of flash smelting; (2) emission reduction and process improvement associated with anode refining of blister copper and the converter retrofit project, and (3) preliminary research findings on alkali treatment of copper smelting slags and copper mine tailings.

By Isabela Leao Amaral da Silva, Felipe Perisse Duarte Lopes, Alice Barreto Bevitori, Sergio Neves Monteiro

"Jute fibers have in the past decades being investigated as possible reinforcement of polymer composites. However, information is still needed on the fiber interaction with a polymeric matrix for a complete evaluation of the capacity of load transference inside the composite. The present work investigated the interaction of jute fibers with polyester matrix by means of the critical length assessment through pullout tests. Tensile tests of polyester sockets embedded with different fiber lengths allowed the critical length to be determined and then the interface shear stress to be calculated. A relatively low interfacial strength was found, which indicates a weak adhesion between the ramie fiber and the polyester matrix. The SEM analysis of pulled out fibers corroborates this result.Introduction Natural fiber, mainly those lignocellulosic extracted from plants, have, in the past few decades, attracted the attention not only of scientists but also of industrial technologists of our society interested in their engineering applications. As it is well known, uses of natural fiber in clothes carpets, baskets, ropes and low cost construction roofing has existed from the beginning of our civilization. Today environmental and energy saving issues are motivating research works on new uses of lignocellulosic fibers in polymer composites [1-6]. Moreover, industrial application of lignocellulosic fiber composites are already in technological sectors such the automobile industry, packing and civil construction [7-9].In addition to environmental, economical and social benefits, some lignocellulosic fibers present specific properties that are comparable to those of other synthetic fiber used for polymer composite reinforcement. For instance, the specific strength (GPa.cm3/g) of curaua (1.31), sisal (0.92) and ramie (0.93) fibers, from results obtained with very thin diameters [10] are relatively closer to that of glass fiber E (1.33). Therefore, in principle, it would be technically justified to replace glass fiber, which is more expensive, toxic and represents a problem to the environment [ll], by a strong lignocellulosic fiber. However, serious drawbacks such non-uniform dimensions and heterogeneous properties [6] as well as the tendency to form aggregates during processing and incompatibility with a hydrophobic polymer matrix, reduce the potential of lignocellulosic fiber to be used as composite reinforcement [1-6]. In particular, a low interfacial strength causes a weak adhesion between the hydrophilic fiber and the polymer matrix."

Jan 1, 2011

By K. R. Robilliard

The Peru based tin mining company, Minsur S.A., commissioned Ausmelt Limited to design, supervise construction and commission a tin smelter and refinery for production of refined tin metal. The plant is located 240km south of Lima, near Pisco, Peru and is operated by Funsur S.A., the wholly owned subsidiary of Minsur S.A.. Selection of the Ausmelt Technology followed a series of crucible scale test work and pilot plant trials conducted at Ausmelt's facility in Dandenong, Australia and two feasibility studies undertaken by Ausmelt in 1991 and 1993. Ausrnelt began the plant design in 1994 with the construction phase following in 1995. Commissioning of the plant commenced early in 1996 with a target throughput of 30,000 tonnes per annum of concentrates. In mid 1998 oxygen enrichment of the Ausmelt lance air was introduced to expand the capacity to the throughput of 40,000 tonnes per annum of concentrates. The process route involves the use of an Ausmelt furnace for primary concentrate smelting, followed by a conventional tin pyro-refining circuit to produce high grade tin suitable for sale. Further work continues between Ausmelt and Funsur to investigate the use of an alternative, more economical, fuel source and the installation of a second Ausmelt furnace. The paper reviews the project to date with details of ongoing operations and developments at the Minsur Tin Smelter.

Jan 1, 2000

By Jorge Gibson, P. Chris Pistorius, Megha Jampani

Increased utilization of natural gas in blast furnace ironmaking can decrease both the cost and the carbon intensity of ironmaking, given current US natural gas prices. In this paper, three ways to utilize natural gas are compared: tuyère injection, prereduction of iron ore, and shaft injection. The basis for comparison includes coke replacement ratios, carbon intensity and furnace productivity. These were calculated using relevant mass and energy balances, a blast furnace productivity correlation based on the bosh gas flow rate, and measured and modeled prereduction kinetics. Of the natural gas utilization methods, prereduction has the highest effective coke replacement ratio (and hence the largest advantage in raw material cost), but is likely to have the highest capital requirement.

Mar 1, 2017

By W. K. Connor, O&apos

The Bureau of Mines has conducted beneficiation, carbothermic reduction, and leaching tests of Mn oxide ores as part of its evaluation of the Mn and Co resources of the West- Central Arkansas District. The major Mn oxides in the ore include cryptomelane, psilomelane, pyrolusite, and lithiophorite. Cobalt is contained within the Mn oxides. Nonbeneficiated ore was reduced at 800' C with coal and leached in ammonium sulfate and ammonium carbonate leach liquors. Ore concentrates were calcined at 600" C prior to reduction under the same conditions as the raw ore. Head analyses reported up to 21 ptt Mn and 0.11 pct Co. Extractions of 70 to 90 pct Mn and 40 to 60 pct Co were achieved.

Jan 1, 1992

By F. -Z. Ji

Carbon injection into metallurgical slag is important in electric arc furnace (EAF) steelmaking for foamy slag practices and in nonferrous slag cleaning operations. The current publication presents kinetic data for coal injection into EAF slag to understand the interaction between injected carbon and metallurgical slag. Coal particles were injected into EAF slag and the kinetics were followed by gas and slag analysis. The results were analyzed, in terms of fundamental rate equations for each possible reaction step, as a function of temperature and slag composition.

Jan 1, 2003

By K. Noda

Tamano Smelter of Hibi Kyodo Smelting Co., Ltd. started its operation adopting the Flash Smelting Furnace with Furnace Electrodes (FSFE). Thereafter, it developed a coke combustion technology based on C() concentration control, which made possible a low cost and high productivity operation without using electrodes. However, increase of treated concentrates and upgrading of matte grade for production expansion started to cause difficulties in operation control with then existing operation control system. This paper outlines recent improvements for stable operation of the Tamano Type Flash Smelting Furnace (T-FSF), such as computer aided operation guide system.

Jan 1, 2001

By Sebastião Ribeiro, Leonardo Carneiro Sardinha, Alline Sardinha Cordeiro Morais, Carlos Maurício Fontes Vieira, Sergio Neves Monteiro

The glass tube of spent fluorescent lamps is contaminated with mercury, which might be a serious hazard in the case of conventional recycling by melting with other glasses. A possible solution could be its incorporation into a clay body to fabricate common fired ceramics such as bricks and tiles. The objective of this work is to characterize a type of fluorescent lamp glass waste to be incorporated into a clayey ceramic. The characterization was performed in terms of wettability tests to evaluate the interaction between the surface of the clayey ceramic and glass waste as a function of the firing temperature. The results showed that the contact angle decreased with increasing temperature, reaching a value of 79°, at a temperature of 1100°C, but not sufficient to completely wet the ceramic. However, compatible chemical composition and reduction of porosity by the flow of soft glass waste between the clay particles favor the consolidation of the ceramics structure above 900°C.

Jan 1, 2015

By J. R. Donald

Electric arc furnace (EAF) dust, which can be considered as a by-product of the steel recycling process, contains significant quantities of recoverable zinc and iron, as well as hazardous elements such as cadmium, lead and chromium, which can be leached by ground water. The zinc in the EAF dust is found almost entirely in the form of either zinc oxide or zinc ferrite, the latter accounting for 20 to 50 percent of the total zinc. It is important that an efficient process be developed which renders the dust inert, while reclaiming the valuable metals to off-set processing costs. During the conventional carbothermic reduction processes, iron is formed, and this iron can participate in the reduction of the zinc oxide in zinc ferrite. In the present work, the reduction of the zinc oxide in zinc ferrite by iron according to the following reaction: ZnO-Fe2O3(s,s) + 2 Fe(s) = Zn(g) + 4 FeO(s) was studied in an argon atmosphere using a thennogravimetric technique. First, a thermodynamic analysis was performed using the F*A*C*T computational system. Then, the effects of briquette aspect ratio (lid), temperature, zinc ferrite particle size, amount of iron added, as well as additions such as lime, sodium chloride, and calcium fluoride were investigated. It was found that, initially, the reaction was chemically controlled with an activation energy of 178.1 kJ/mol. Then, after a product layer had formed on the outer surface of the briquette, the reaction was restricted by the diffusion of zinc gas away from the reaction interface. The parabolic rate law was fitted to the experimental data, and the parabolic rate constant was found to be: = -6.2275 + 0.0054 T (K)

Jan 1, 1995