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By Maria Salazar-Villalpando, Todd H. Gardner

"Efficient utilization of CO2 can help to decrease global warming. Methane reforming using carbon dioxide has been of interest for many years, but recently that interest has experienced a rapid increase for both environmental and commercial reasons. The use of CO2 provides a source of clean oxygen, which eliminates the need for costly oxygen separation plants. The product of dry reforming is useful syn-gas, which can be used to generate electrical power in a SOFC or in the production of synthetic fuels (hydrocarbons and alcohols). Hexaaluminate catalysts prepared at NETL may represent a product that can be utilized for the conversion of CO2 to syn-gas. In this work, transition metals dispersed in barium hexaaluminate have shown to be promising new catalysts for dry methane reforming. In this investigation, a series of BaNixAl12-yO19-d catalysts with varying Ni content were prepared by co-precipitation followed by calcination at 1400°C. CO2 reduction by dry methane reforming was carried out to determine catalyst performance as a function of temperature and carbon formation was also quantified after the reforming tests. Results of catalysts characterization, dispersion and surface area, were correlated to catalytic performance.IntroductionEfficient utilization of CO2 can help to decrease global warming. Methane reforming using carbon dioxide has been of interest for many years, but recently that interest has experienced a rapid increase for both environmental and commercial reasons. The use of CO2 provides a source of clean oxygen, which eliminates the need for costly oxygen separation plants. The product of dry reforming is useful syn-gas, which can be used to generate electrical power in a SOFC or in the production of synthetic fuels (hydrocarbons and alcohols). The dry reforming reaction has been known for a long time. Recent publications have reported studies over several catalysts. For example, the CO2 reforming of CH4 over mesoporous nanocrystalline zirconium powders (ZrO2–3%M2Ox; M: Ce, La and K) at 700ºC have shown methane conversion up to 60% (1). Similarly, the effect of Ni content (1–12 wt%) on the surface and catalytic behavior of bimetallic PtNi catalysts supported on ZSM-5 for reforming of methane with CO2 has been studied and report shows a maximum conversion of 16% and catalyst deactivation was observed during the first hour of time on stream (2). In another report, (3) Ni/a-Al2O3 catalyst was tested for syn-gas generation at 750ºC. The maximum methane conversion was 25%."

Jan 1, 2008

By R. W. Lawrence

A high rate biological reduction technology has been developed to provide low cost hydrogen sulphide for various uses in water treatment and metallurgical processes. Commercial operations produce sulphide safely at a fraction of the cost of chemical sulphide. The biologically produced H2S is used for treatment of acid wastewater and selective metal recovery whereby metals present in wastewater streams are recovered in high grade metal sulphide concentrates that are sold to smelters. The combination of biological H2S production and selective metal recovery is currently marketed under the process name BioSulphide-Thiopaq. The process can be applied on a stand-alone basis or in conjunction with a conventional lime water treatment. Process advantages include: reduced lime treatment costs, reduced volume of waste sludge free of toxic metals leading to reduced long term environmental liabilities, selective recovery of metals and, in some cases, net profit from water treatment achieved through the sale of metal concentrates. Three case studies are presented to provide examples water treatment and metal recovery: the Caribou Mine, New Brunswick; the Phelps Dodge Bisbee operations, Arizona; and Falconbridge?s Raglan nickel mine in Quebec. A fourth case study is presented to highlight environmental control for treatment of ARD in the Leadville mining district of Colorado. Process flowsheets, capital and operating costs are presented for the four case studies

Jan 1, 2003

By M. Arenas

A corrosion study of a bonded NdFeB permanent magnet materials alloyed with titanium carbide additions has been undertaken. The materials were produced by rapid solidification by melt spinning. Commercial epoxy was used as a bonding medium. The corrosion results were compared with those of a near stoichometric unalloyed NdFeB. Anodic polarization and potentiostatic techniques in 0.9 M Na2SO4 solutions were used to characterize corrosion behavior. It was found that the addition of 6 a10 Tic resulted in superior corrosion resistance, as indicated by lower corrosion currents and less iron dissolution at fixed potential.

Jan 1, 1997

By John K. Wright

The segregation process involves heating oxide-type ores with a halide salt in the presence of a solid reductant. By a complex series of cyclic vapour-phase reactions, the desired metal is extracted from its original position in the ore and segregated to the vicinity of the reductant. In this form it is then amenable to concentration by physical methods. In this work the segregation behaviour or eight different nickel laterite ores has been examined using a laboratory rotary kiln. It was found that the silicate (serpentine) ores responded better to the segregation conditions used than did the limonitic ores. An examination of the segregated metal particles showed that they consisted of ferro-nickel. The concentration of nickel in the metallics was sensitive to the ore types and the segregation roasting conditions.

Jan 1, 1994

By Nirlane Cristiane Silva, Leonardo Gonçalves Pedroti, Ana Augusta Passos Rezende, Anna Paula Sartori, Benício Costa Ribeiro, Andreiva Lauren Vital do Carmo, Wellington Emílio Hilarino Fernandes

The final disposal of sludge from recycled paper mill effluent treatment plants is costly and demands large areas for landfilling. Environmentally sound alternative uses of the sludge, enabling economic valoration of this material appear to be advantageous to industry and to the environment. This paper evaluates the feasibility of the incorporation of paper mill sludge in manufacturing of ceramic bodies. The combination of different proportions of weak clay, strong clay and sludge from recycled paper effluent treatment plant for the production of ceramic bodies was determined by using the Network Simplex method planning of mixtures. Samples were prepared and burnt in oven at temperatures of 750, 850 and 950 °C. Physical, mechanical and environmental tests were carried out, in addition to chemical, microscopic and thermic analysis. The results demonstrated that the flexion resistance increased with the increase in temperature, while the absorption decreased at higher temperatures. The mixture design is efficient combining sludge addition at small fractions with large amount of clay, which demonstrate the viability of sludge incorporation for ceramic bodies manufacture, since the desired characteristics are observed.

Mar 1, 2017

By F. Kongoli

Nonferrous and ferrous smelting industries have recently faced the unavoidable necessity of changing and/or improving the smelting technologies as a result of the use of new raw materials which are becoming available from different geographical areas. These new feed materials usually contain different ore composition and higher level of minor components, which adversely affect the smelting process. Due to the problems encountered in several processes as a result of this feed diversification some work has been undertaken in order to make uniform the feed and avoid later surprises in the smelting process. However this has proven to be very difficult and sometimes almost impossible. In this work a more viable approach is undertaken to deal with this problem. It consists of controlling not the cause of the problem i.e. the feed composition but instead the results of this feed change, i.e. the end-point of smelting technologies. It is shown that this approach, when carried out through advances physicochemical modeling and simulation tools is not only easier and less costly but it also helps the control optimization and automation of the smelting processes. Several examples are given and future work is underlined.

Jan 1, 2003

By Thomas Buenger

The Hamburg smelter of Norddeutsche Affinerie AG is situated near the city of Hamburg’s downtown and is therefore particularly subjected to fulfill environmental requirements according to the German legal regulations. Thus, investments related to increasing concentrate throughput are always linked to packages to enhance the emission status of the smelter. This connection between environmental protection and productivity enhancement should be explained by the example of the Peirce-Smith converter plant of the Hamburg smelter. Such outstanding investments can be demonstrated by the transition from scrap charging via boat from the front side to a fully automatic and completely sucked scrap charging system.

Jan 1, 2009

By Karl-Heinz Daum

Outokumpu Lurgi Metallurgie GmbH, Oberursel, Germany ? give saleable by-products, ? not interfere with smelter performance, ? treat all gas streams simultaneously, and ? comply with environmental regulations. The latest developments in sulphuric acid plant design are presented.

Jan 1, 2002

By Ernt. W. D.

A membrane based mixed extractant process was developed for selective removal of copper from waste acidic cupric chloride etchant solutions found in printed wire board manufacturing. The process uses a mixture of Adogen 381 (tri-isooctylamine), MOC®-45 (ketoxime) and MOC® 55TD (aldoxime) in a kerosene diluent. The mixed extractants recover the copper from a hydrochloric acid medium and transfers it to a sulfuric acid medium. The process also utilizes unique wetted membranes to separate the aqueous and organic phases. The driving force for these membranes is not pressure but the difference in surface tension between the two phases. By using these membranes, complete phase separation results. There is no physical entrainment contamination as found in conventional systems. The only cross contamination is the solubility concentration of one phase in the other. This however is less than 10 mg/l.

Jan 1, 1998

By Tarasankar DebRoy

Professor Robertson’s recognized research on metallurgical thermodynamics and kinetics for over 40 years facilitated the emergence of rigorous quantitative understanding of many complex metallurgical processes. The author had the opportunity to work with Professor Robertson on liquid metals in the 1970s. This paper is intended to review the advances in the quantitative understanding of welding processes and weld metal attributes in recent decades. Over this period, phenomenological models have been developed to better understand and control various welding processes and the structure and properties of welded materials. Numerical models and animations of melting, solidification and the evolution of micro and macro-structural features will be presented to critically examine their impact on the practice of welding and the underlying science.

Jan 1, 2014

By Ronald C. Askin

Dredging is a common method of remediating ponds containing contaminated wastes. However, dewatering of the dredged solids is usually not well integrated with the dredging phase. As a result, overall project efficiency can be poor. Specifically, since dredges deliver material in a widely varying slurry form and since dewatering presses require the delivered material to be uniform, union of the two systems often results in inconsistent operation of the overall process. In an effort to enhance overall dredging and dewatering process production rates as well as minimize the return of suspended solids in the decant water, a new process was developed to provide a consistent dredged sludge for delivery to the press. This paper discusses modifications made to a conventional dredging and dewatering process to improve production rates and dewatering capabilities. These modifications are applicable to any project where efficient solids dewatering is required and where returning decant water must be visually free of suspended solids.

Jan 1, 1996

By Ken-ichi Machida

"Surface modification of R-Fe-N intermetallic compounds was made to improve their magnetic property and nitrogenabsorbing ability, arid high-performance resin-bonded magnets and nitrogen storage materials were developed: Surface coating for Sm2Fe11Nx by the zinc metal produced via photodecomposition of Zn(C2Hs)2 was effective to avoid the further oxidation in the molding process of the fine powders for bonded magnets and the resulting (BH)max values were improved to -186 kJm-3. Meanwhile, R2Fe17 as the mother compounds for RzFe11Nx was highly active for decomposition of NH3 molecule and subsequent nitrogen absorption as metal nitrides. Furthermore, even inert Nz molecule was dissociated on them by impregnating Ru metal and the resulting nitrogen atoms were absorbed in the crystal lattice of R2Fe17. These results demonstrated that the nitrogen storage system was established by cycling the nitrogenation and hydrogenation of RzFe11/R2Fe11Nx materials.IntroductionProcessing for rare earth metals and intermetallic compounds requires well-controlled conditions in order to avoid the oxygen contamination involved in it due to their high reactivity, as causes the serious damage for materials such as magnets, metal hydride for hydrogen storage, and so on. Rare earth-iron intermetallic compounds, R2Fe17, provide the corresponding metal nitrides (R2Fe11Nx) by heating in N2 or a mixed gas stream ofNH3-H2 [l] and, among them, Sm2Fe11N3 has been particularly noted as one of the promising materials for high-performance permanent magnets such as bonded ones [2- 6]. Usually, the nitrogenation for Sm2Fe17 is made in Nz, but it needs the much more hard conditions of reaction pressure (-10 MPa), temperature (-550°C) and time (-72 h) than the nitrogenation in the NH3-H2 mixture [l]. In the latter case, a significant amount of nitrogen can be interstitial introduced in· the R2Fe17 crystal lattice (x=-7) under the more moderate conditions than in N2 (at 0.1 MPa and -450°C for -3 h) [3-6] and then, in a similar manner as metal hydride systems [7], the excess nitrogen in RzFe1 7Nx (x>3) is reversibly desorbed by heating at a temperature around 500°C in Ar to form the RzFe11N3 compounds. This behavior of nitrogen absorption and desorption has a close relation to the sites for nitrogen in the crystal lattices."

Jan 1, 2000

By Bogidar Mihaylov

A laboratory study was conducted on continuous precipitation of copper, cadmium, mercury and arsenic using thiourea, thioacetamide, sodium sulfide and ammonium sulfide as precipitating agents. Depending on the experimental conditions the metals precipitate with the sulfide donors at different orders and rates. These differences were employed as a basis of several techniques for continuous separation of copper and arsenic, cadmium and arsenic, mercury and copper, and copper, mercury and arsenic. The separation of the metals from industrial waste solutions was also studied. The precipitates obtained were inspected using x-ray diffraction, scanning electron microscope, atomic absorption spectrometer and plasma particle counter.

Jan 1, 1992

By Roberto Parra

The wear and corrosion phenomena in the furnace lining of the ferrous and non ferrous pyrometallurgical processes are complex problems where chemical, interfacial and mechanical phenomena are presents. The characteristics of the processes determine the conditions to which these materials are submitted, where the thermal conditions reached during the operation is one of the most important parameter. Assuming that all the degradation phenomena are thermal activated, the rate of the different steps of the wear mechanism will depend on the thermal field in the lining. In view to apply the independent physicochemical knowledge of degradation mechanisms to the analysis and design of furnace lining the methodology of the Nodal Wear Model (NWM) was done. It combines the mathematical modelling of the heat transfer in the lining with the physicochemical control equation for the wear-corrosion phenomena. The NWM has been applied to different examples: theoretical analysis, laboratory scale test and industrial applications. We present in this paper the theoretical background of the model and two examples of applications: the sole of an electric furnace and the earth of a blast furnace.

Jan 1, 2006

By H. Roberts, C. Hassall

The opening years of the new millennium will be characterised by the closure of many lead and zinc mines because of reserve depletion. However, weak commodity prices through the second half of the 1990s have slowed project evaluation and have made it difficult to raise finances for the development of new mines required to replace lost output and to meet increasing demand for metal in the future. Growth of lead and zinc demand will be determined by the pace of global economic activity, especially in the emerging economies. How rapidly demand grows will have a key bearing on the possible shortfall in mine output and the response of prices to the implied tightening of metal supplies early in the new millennium. These issues are the focus of a discussion of the critical lead and zinc supply developments which will unfold post 2000, taking into account project lead times and the role that recycled metal plays in meeting market demand.

Jan 1, 2000

By P. Lussiez

Precipitates consisting of amorphous ferrihydrite and crystalline goethite have been prepared by aging hydrolyzed Fe (III) solutions at room temperature. The precipitates have been characterized by x-ray diffraction and differential thermal analysis. The amorphous ferrihydrite transforms to goethite with time. The ferrihydrite to goethite transformation is affected by the presence of small amounts of copper or nickel coprecipitated with the iron. .The addition of copper decreases the amount of goethite at a given aging time and increases the amount of coprecipitate which is initially dissolved in sulfuric acid, but it does not seem to affect the dissolution of the crystalline part'. It is proposed that adsorption of copper hydroxo species on goethite nuclei delays the ferrihydrite to goethite transformation. The effect of nickel is less dramatic than that of copper. Apparently a portion of the added nickel is adsorbed on the goethite crystallite surface rather than incorporated into the goethite lattice.

Jan 1, 1981

By Neil E. Izatt

The use of Molecular Recognition Technology (MRT), a selective separations technology using specifically designed ligands, has been established as an effective process for removal of metal ions found in many hydrometallurgical, chemical, and wastewater streams. The MRT process has been proven to be highly efficient and effective for indium extraction and recovery from zinc acid leach, electrolyte, chemical process and waste streams. A high percentage of the indium is recovered in a solid product format. MRT has also proven effective for germanium extraction and recovery from similar feed streams. This paper provides the indium and germanium metal recovery flow sheets and analytical results of the metal load and recovery steps.

Jan 1, 2006

By Moto Goto

PT Smelting, located in Gresik, East Java, is the first copper smelter and refinery in Indonesia. Since the first charging concentrate in December 1998, many equipment troubles have been systematically eliminated, and the present operation is smooth and has accomplished the design capacity of 200,000 tonnes per year of LME, grade-A copper cathode. This paper describes troubles and countermeasures, which were experienced until now.

Jan 1, 2002

By Merete Tangstad, Lars Klemet Jakobsson

"Slag refining is a promising refining method for boron removal from silicon as a part of a metallurgical route for production of silicon for solar cells. There is, however, limited data on the distribution of impurity elements between silicon and different types of slags. In the present study, the distribution of boron and calcium between silicon and slag were determined at 1600 °C for calcium silicate slags with a CaO/SiC>2 ratio between 0.65 and 1.3. An almost horizontal linear trend was found for the distribution of boron between silicon and slag, and the borate capacity was found to follow the relationln(CB0, ) = 30.8 + 2.96-V (1)where V\s the CaO/SiCh mass ratio within the range of the experiments.IntroductionSolar grade silicon feedstock contributes significantly to the total cost and energy required to make crystalline silicon solar cells. A less expensive and less energy requiring method of solar grade silicon production is therefore needed in order to make crystalline silicon solar cells more viable as an energy source. Silicon is an abundant element and the manufacturing cost of solar grade silicon is therefore mainly determined by costs related to purification of metallurgical grade silicon. The Siemens process is the most common process today, but it is an expensive and highly energy requiring process that gives silicon with a higher purity than is needed for crystalline silicon solar cells. A cheaper and less energy requiring method for production of solar grade silicon can either be achieved by modifying the Siemens process or by using a new production method. Purification of metallurgical grade silicon through a metallurgical route is a promising method that is already in use industrially. It has however proven to be hard to lower the boron content to 0.3 mg/kg or less, which is the requirement for most p-type crystalline silicon solar cell manufacturers. Slag refining is seen as one of the most promising approaches that can be used to bring down the boron content to the required level, but there is not much data on how boron is distributed between silicon and binary calcium silicate slags [1-4]. The distribution of boron between silicon and calcium silicate slags at 1600 °C has been studied in this work, and the obtained data has been used to calculate the borate capacity of binary calcium silicate slags."

Jan 1, 2012

By J. E. Sallee

An experimental study has been conducted on the level of arsenic contamination in samples of zinc oxide when the zinc oxide is contacted with gas mixtures containing As4O6(g). This contamination has been determined as a function of A4O6 saturation pressure, temperature, zinc oxide sample surface area, impurities, and oxygen level in the gas mixture. The results indicated a rather clean separation can be achieved between condensed zinc oxide and gaseous arsenic oxide as long as attention is given to temperature control, and the final zinc oxide surface area. For a 300°C operation temperature and an AqOg saturation pressure of 0.38 TORR (or 0.05% As406 by volume), the contamination level is expected to be approximately 100 ppm. This suggests that arsenical dusts can be treated in the HRD flame reactor process and a reasonable purity zinc oxideproduct produced. The results also show no evidence of zinc arsenite or zinc arsenate formation.

Jan 1, 1994