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By Cynthia Belt

"Energy management is critical to aluminum processing given the high energy requirements of melting and processing aluminum. Energy costs have always been a high percentage of the total production costs within this industry. Energy management at many plants relied on better technology that many times required high capital. As carbon management has grown in importance and project payback becomes more critical, a larger view of a plant's process is required. This paper looks at the energy requirement due to current typical practices in overall product recovery, metal loss, utilization, and technology to understand potential methods of reducing overall energy within a plant and within the aluminum processing industry.IntroductionFor many companies that process aluminum, energy is a major portion of their costs that can surpass the cost oflabor. Aluminum processing can include secondary processing of scrap and prime aluminum into sows and/or molten aluminum or casting aluminum by various methods such as direct chill, continuous casting, low or high pressure casting, mold casting, and extrusions. In the case of this paper, we are considering only plants that include the melting process as a portion of their process. The process of melting aluminum takes energy. In most cases, the aluminum must then be heat treated one or more times. Post processing of the aluminum includes rolling mills used for making sheet, extrusion lines, and machining such as saw cuts, drilling, or surface finishes that all take additional energy.While these high energy costs directly affect the profits of the company, energy management within the metals industry is still not widespread. A co=on misconception is that the solution to high energy costs is high cost capital equipment. While state-of-the-art equipment can certainly improve energy efficiency, it is not the only solution. To obtain a truly energy efficient plant, several directions needs to be addressed through an energy management thought process with a wider scope. Impact on potential savings is possible through: product recovery, metal loss, utilization, and new technologies. An understanding of the potential costs and savings from these means is important. Several of these methods provide low cost approaches to saving energy.The background data used in this paper is not a random sample within aluminum processing but yearly averages from various plants in different aluminum processing industries. As is normal in this industry, the plants have been under different corporate management over the years with different strategies for energy management. This data is not meant to be accurate for the entire industry but to suggest areas for energy efficiency work."

Jan 1, 2012

By D. J. Senor

Closed chamber incineration (CCI) is a novel technique by which irradiated nuclear graphite may be destroyed without the risk of radioactive cation release into the environment. The process utilizes an enclosed combustion chamber coupled with molten carbonate fuel cells (MCFCs). The transport of cations is intrinsically suppressed by the MCFCs, such that only the combustion gases are conducted through for release to the environment. An example CCI design was developed which had as its goal the destruction of graphite fuel elements from the Fort St. Vrain reactor (FSVR). By employing CCI, the volume of high level waste from the FSVR will be reduced by approximately 87 percent. Additionally, the incineration process will convert the Sic coating on the FSVR fuel particles to SiO2, thus creating a form potentially suitable for direct incorporation in a vitrification process stream. The design is compact, efficient, and makes use of currently available technology.

Jan 1, 1994

By Batric Pesic

Adsorption of gold on activated carbon from gold bromide solutions was examined as a function of pH, particle size, carbon amount, initial gold bromide concentration, bromine concentration, temperature, and various cations and anions. pH did not have any effect below pH=6. Above pH=6, pH had dramatically negative effect. The adsorption results satisfied a first reaction order model. The reaction rate constant was proportional to the inverse of carbon particle radius. It was also proportional to the amount of carbon, and independent of initial gold concentration. Temperature had a very little effect at pH=l. At pH=8, the activation energy was a function of the extent of a reaction, increasing with the extent of a reaction. Cu, Fe, Ca, Mg, and Na cations and sulfate, chloride and bromide anions did not have any effect on gold adsorption. Bromine had a very negative effect on gold uptake.

Jan 1, 1991

Mineralogical and metallurgical scoping testwork were carried out to investigate the production of separate, marketable gold and platinum concentrates. The study utilized a flotation concentrate assaying approximately 5 wt% gold and 5 grams per tonne platinum. The gold-platinum mineralization was recovered from a placer deposit. Optical microscopy and scanning electron microscopy with energy dispersive x-ray analysis identified gold as zoned Au- Ag and Au-Ag-Cu alloys. Platinum primarily occurred as weakly zoned, variably magnetic Pt- Pd-Fe alloys. A combination of gravity and magnetic separations resulted in a gold concentrate grading 86.9 wt% Au (and 9.lwt% Ag) and a separate platinum concentrate grading 400 g/t Pt with recoveries of 94.5% and 96.7%, respectively. Magnetohydrostatic separation (MHS) using the Magstream 200 Separator indicated promising results.

Jan 1, 1994

By Richard S. Kunter

Artech Recovery Systems, Inc has developed a low pressure and temperature? leach process called the "Cashman Process" to extract metals from arsenical flue dusts and residues and fix the arsenic in an environmentally stable form as ferric arsenate (scorodite). The process was pilot tested at Hazen Research in an integrated plant including continuous recycle from August 1989 to October 1989 during which several tons of flue dust were processed. Based on this pilot program, the process was deemed technically feasible and produced commercially salable products. Residues from this pilot program were subjected to a long-term stability test jointly designed by PTI environmental services and the USEPA. The process, its versatility, and the nature of the products is discussed in some detail.

Jan 1, 1992

By Bora Derin, Sertac Yazici, M. Seref Sonmez

"In this study, the recycling conditions of waste liquor obtained after the production of tungsten boride powder from calcium tungstate by self-propagating high temperature synthesis (SHS) and the following hydrochloric acid leaching were investigated in detail. Environmentally unfriendly and extremely acidic (pH~ -0.3) liquor consisting of calcium, magnesium, and boron ions was treated with 1 M sodium carbonate solution to precipitate magnesium carbonate and calcium carbonate phases. The obtained amorphous precipitates were heated up to the temperature of 400°C for re-crystallization. As a result, MgO, CaC03 and CaMg(C03)z phases were obtained, while sodium, boron, chlorine ions were remain in the solution. The present study is still in progress.IntroductionSelf-propagating high temperature synthesis (SHS) is one of the techniques used in the production of a variety of advanced ceramics, inter-metallic, organic and inorganic compounds, oxygen free single crystals, and polymers [ 1, 2]. The reaction becomes selfsustaining and propagates in the reactant mixture, after initiation in SHS process. SHS products may contain the mixture of several unwanted compounds and elements. Therefore following acidic leaching process may be needed to purify the target product. In the previous study, calcium tungstate (Ca W04), magnesium (Mg) and boric acid (B20 3) mixture were reacted to produce tungsten boride powder by SHS process according to the Reaction 1. Then, magnesium and calcium containing byproducts (i.e. MgO, Mg3B206 and Ca3B206) found in the SHS product were leached out by using concentrated hydrochloric acid (HCl) solution to obtain pure tungsten boride powder [3].Ca W04 + 0.5B203 + 4.5Mg = WB + 4.5Mg0 + Cao (1)After the leaching, filtrate solution consisting of different amounts of magnesium, calcium, and boron requires additional treatment for the environmentally acceptable disposal.Several works were carried out about magnesium precipitation conditions and kinetics from brines. Rabadzhieva et al. investigated the precipitation of Mg(OH)z from brines by using NaOH as well as caustic soda [ 4]. Turek ve Gnot investigated the precipitation efficiency of Mg(OH)z for the temperature range between 10-40°C, while the reaction was kinetically experimented by Alamdiri et al [5, 6]. Homogeneous precipitation of nesquehonite (MgC03.3H20) by the reaction of MgCli with (NH4)2C03 in supersaturated solutions and factors that influence the precipitation of MgC03.3H20, such as reaction temperature, initial concentration, stirring speed, titration speed, equilibration time, have been studied by Wang et al [7]. The precipitation of Mg(OH)z by calcium hydroxide from aqueous solutions was studied by Baird et al. [8]. Stratful et al. focused on conditions influencing the precipitation of magnesium ammonium phosphate from wastewaters [9]. 1031"

Jan 1, 2011

By Lev Levin, Sergei Lesokhin

"The formation of titanium carbide during hot filament assisted carburizing of NiTi alloy was investigated. Phase content and morphology of the diffusion zone were examined by X-ray diffraction, X-ray microanalysis, SEM, and Auger electron spectroscopy. The growth of stable and adherent TiC film was observed. A non-planarity of interphase boundary was noticed. The applicability of the chemical diffusion approach to the analysis of the experimentally observed interface instability is discussed. A criterion, taking into account the influence of growth stresses on the stability of the flat interface, is developed by means of linear perturbation analysis.Introduction.Equiatomic intermetallic NiTi belongs to a class of materials exhibiting the shape-memory effect. The unusual property of this compound promotes its application in many fields, from aerospace technologies to medicine. The relatively high ductility ofNiTi also permits its use as a matrix material in metal-ceramic composites. The objective of this work was to investigate the possible incorporation of a ceramic material (titanium carbide) into NiTi by gas carburizing.Free energy calculations indicate the potential to obtain TiC by carburizing Ni-Ti binary phases. The main obstacle to such a process is the high affinity of titanium to oxygen. At moderate temperatures the formation of TiC is preferable to titanium oxidation only if the partial pressure of oxygen is extremely low [1]. This problem was overcome in this work by the use of hot filament assisted gas carburizing. Due to chemical reactions occurring near the hot filament, the gas mixture, initially consisting of methane and molecular hydrogen, was enriched by atomic hydrogen [2], drastically decreasing the content of free oxygen in the carburizing atmosphere.The second part of this article concerns the theoretical analysis of reasons that lead to the development of the experimentally observed morphology of the diffusion zone. In particular, the influence of the growth stresses on the morphology of an interphase boundary is investigated."

Jan 1, 1996

Reduction of titania and ilmenite ores by Cf4-H2-Ar gas mixture was investigated in a laboratory fixed bed reactor. Titania was reduced to titanium oxycarbide in the temperature range of 12OO-1500°C. At 1400-15000C, the extent of reduction of titania to titanium oxycarbide achieved more than 85% in 90 min. Optimum conditions for titanium oxycarbide synthesis by reduction of titania include temperature in the range of 1300-1450°C, methane content 8 vol% and hydrogen content above 35 vol%. Ilmenite ore was reduced by Cf4-HrAr gas mixture to metallic iron and titanium oxycarbide. Metallic iron catalyzed methane cracking and solid carbon deposition. Titanium oxycarbide formed at temperatures as low as 950°C. The optimum temperature for reduction of ilmenite is 1200°C and the optimum methane content is 8 vol%. Increase in hydrogen content increased both rate and extent of reduction. With 5 vol% CH4-75 vol% Hr20 vol% Ar gas mixture, the reduction of ilmenite completed in 60 min. Reduction of titanium oxides to oxycarbide with following chlorination may be an efficient alternative technology for processing of titanium minerals.

Jan 1, 2001

By H. Kohno

The Onahama No.3 tankhouse started commercial operation in early 1973, with the capacity of 8,500 metric tons per month. When the No.3 tankhouse was constructed, the starter sheet stripping section was rebuilt at the No.2 tankhouse and electrolyte purification section was expanded. The previous AIME paper in 1976 described the design principles of the No.3 tankhouse and its layout, This paper describes the starter sheet stripping machine in the No.2 tankhouse and the electrodes handling system in the No.3 tankhouse and all these equipments were developed for the operation of the No.3 tankhouse. A Hazelette continuous casting machine was also introduced in order to cast thin anodes with accurate shape. Owing to the adoption of thin anodes, gold, silver and copper inventory is reduced by 40%. Jumbo tanks and newly developed mechanical equipments were adopted and no work on cells during pulling up operation was achieved. Using thin anodes with accurate shape, inspection work was completely abolished while maintaining high current efficiency and high cathode quality. Labor cost was reduced by 70% and only six operaters can produce? 8,500 metric tons of cathodes per month. The same new electrolysis process is appreciated and has been used as a newly built independent tankhouse by Kidd Creek Mines Ltd., in Canada in 1981 with excellent results

Jan 1, 1987

By Sne?ana Devi

Mineralogy is a significant scientific discipline, essential in establishing the nature and the character of raw materials, regardless of whether they are monomineral or polymineral. Mineralogical characterization is very important, because its results give valuable information on features and nature of examined materials. Information's on mineralogical nature of mineral raw materials influence directly the quality assessment of a raw material, and thus the possibility of its use. The possibility of use of mineralogy in different industrial branches confirms constant activity of this scientific discipline. By use of methods within mineralogical analysis (optical microscopy, x-ray diffraction and others) data on mineral raw materials can be obtained as support in mineral raw materials quality assessment. Short description of results of mineralogical analysis of some mineral materials (granodiorite, dolomites, clay, refractory materials, slags and casting powders) in this paper shows the importance of its support to quality assessment and determine the possibilities of their use.

Jan 1, 2009

By Dao Su, Ganghua Fu, Xuling Chen, Yufeng Guo, Min Gan, Tao Jiang, Xiaohui Fan

"The sinter quantity and quality of limonite in the magnetite and hematite sintering models were studied and compared. For the sintering of magnetite, the results showed that the increase of limonite improved the permeability of sinter mixture, increased the sinter quantity and quality. The sinter strength and productivity were decreased when the proportion of limonite exceeded 50%. The appropriate proportion of limonite was 40%-50%. For the sintering of hematite, the sinter quantity and quality were first maintained at the same level thereafter declined, more obviously when the proportion of limonite exceeded 40%. The amount of calcium ferrite increased whose shape changed from acicular to leaflike and block gradually with the proportion of limonite increased from 0% to 80%.IntroductionWith the fierce competition of domestic and overseas iron markets in the twenty-first century, cheap ores such as limonite are used to be sintering raw materials to cut the costs of sinter and pig iron for steel making, and boosts the competitiveness of steel companies [1, 2]. In addition, as the reserve volume of hematite of high grade is reducing year by year, the usage amount of limonite in sintering are expanding in major domestic and international sintering plant [3, 4]. Sintering can be divided into two types, majoring in concentrates and fine ores, according to the different types of raw materials. The sintering characteristics of limonite in the two types above have been studied and compared in this paper, which makes a significant sense for the research of limonite sintering properties and guidance of ore proportioning in sintering plants."

Jan 1, 2012

By M. H. Erten

Most of the fourteen workable coal seams in the State of Missouri have high ash and sulfur levels and need beneficiation in order to meet customer and Environmental Protection Agency requirements. If proper ash and sulfur removal methods can be designed, more Missouri coals will be mined and used within the state. One of the main objectives of this research is to investigate the possibility of removal of sulfur of Missouri coals by conventional beneficiation methods.

Jan 1, 1982

By J. J. Kim

In a study of buildup in a green-feed reverberatory furnace, it was determined that approximately half of the crucible area has a moderate buildup of 25 in. or less, and that the area extending 45 f t from the burner end of the furnace has only a slight buildup. The false bottom, averaging 6 in. in thickness, was found to cover the entire crucible area. The stratification of Cr2O3, A12O3, and SiO2 occurs throughout the slag layer; this phenomenon is the principal reason for the formation of the false bottom in the green-feed reverberatory furnace. The false bottom is caused primarily by the settling of FeO*(A1,Cr),03 aggregates, which are derived mainly from returned converter slag. The false bottom can be transformed to a solid permanent buildup in the furnace, particularly when the matte is completely withdrawn. From the material balance of Al2O3 and Cr2O3 around the furnace, It is estimated that the average rate of aluminum chromite accumulation is approximately 0.3 ton per day or less.

Jan 1, 1976

By Vincent Canaguier

Methane is increasingly considered as a promising reductant for metal oxides, including chromite. To assess the possibilities of such reduction route, the gas-solid reactions between Ar–CH4–H2 gas mixtures and synthetic chromites are studied between 950 and 1050 °C. The influence of Mg and Al additions on the reduction-caburization of (Fe,Mg)(Cr,Al)2O4 solid solution is investigated thermodynamically, structurally and kinetically. The product phases are examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). The reaction rate is derived from real-time exhaust gas measurements and post-reaction product analyses such as oxygen analysis. Kinetic models are proposed based on the product phase morphologies and confronted with the empirical data.

By Juan Patricio Ibáñez

Separation of arsenic and copper from Cu-As-H2S04 electrolytes by electrodialysis has been investigated at room temperature. The effects of current density and pH were studied. An arsenic-free copper solution was obtained for all the tested conditions. The transport efficiency for copper ions was found to be higher than 98% after 3 hours' test. Transport of arsenic and copper through the ion exchange membranes was increased by increasing pH and current density. Solution pH was found to be a key parameter for the separation process, since it controls the speciation of the ions to be transported and the formation of unwanted precipitates which reduce the global efficiency of the electrodialysis process. The main conclusion is that electrodialysis is a promising technique to be used in separating and/or concentrating ions of interest in copper electrometallurgy.

Jan 1, 2003

By Gerardo H. Achurra

During the last years, the Caletones Smelter, like others copper smelters in the world, has evolved from the conventional, inefficient, pollutant and expensive technologies, to modern, environmentally friendly and efficient ones. For this reason' as well as to improve its competitive position this Smelter shut down the reverberatory furnace, started up two big acid plants and has developed some pyrometallurgical technologies. The main facilities of the Caletones Smelting and Converting Process, in the present and the future, are the Teniente Converters, the reactors with a high operational availability that have reached concentrate top process capacities near to 2,400 tpd. These reactors operate in most of Chilean smelters as well as in other smelters in the world such as in Zambia, Peru and Mexico. Since 2000, the Caletones Smelting and Converting Process, has been adapted in two Teniente Converters, four Slag Cleaning Furnaces and four Pierce -Smith Converters. These facilities, together with the operation of two Fluidized Bed Dryers and two Oxygen Plants have allowed to reach concentrate smelting capacities and copper productions of 1,250 ktpy and 380 kfipy, respectively. Associated to EI Teniente Division Expansion Plan, Caletones Smelter, in the first stage, will increase its capacity to 1,440 ktpy in 2004. In the long term, Caletones has different options, such as the processing of 1,600 to 2,000 ktpy of concentrate, producing anodes, white metal or a mixture of them. These options are connected with CODELCO's Smelters & Refineries Strategic Plan, including Mejillones Project. The main challenges of Caletones Smelter are associated to the development and the consolidation of the Continuous and Environmental Friendly Processes, automation and control of different processes and to the improvement of its leadership between other Copper Smelters in the world.

Jan 1, 2003

By Hong N. Vu, Jitka Jandova

"Gypsum and limestone methods were examined in this study to process zinnwaldite wastes originating from dressing Sn-W ores mined in the Czech Republic. These wastes containing 0.20-0.30% Li and 0.10-0.20% Rb were subjected to magnetic separation to obtain a zinnwaldite concentrate with 1.36% Li and 0.94% Rb. It was observed that processing of the zinnwaldite concentrate with gypsum resulted in almost 96% recovery of Li into aqueous liquors, whilst rubidium extraction was only 25%. At the same time, it is possible to extract almost 92% Li and Rb from the identical zinnwaldite concentrate if the concentrate is processed by limestone method. Lithium carbonate, a final product of both methods was recovered from the refined sulphate solution using K2CO3 as a precipitation agent and/or from unrefined hydroxide solution using gaseous CO2. In the continuation of this study, rubidium will be separated from carbonate solutions after Li2CO3 precipitation as RbAl(SO4)2, an intermediate for Rb2CO3 production. IntroductionLithium is used as an alloying constituent in lightweight alloys, as a heat transfer medium in nuclear reactors and as a component in primary and secondary batteries. With the development of a new generation of electric vehicles, the lithium demand will dramatically grow. Lithium chemicals find extensive application in many industrial branches such as metallurgical, glass, ceramic and pharmaceutical industries. Rubidium compounds are predominantly used in psychiatry and medicine, in magneto-optic modulators, solid-state lasers, phosphors and components of electrolytes for fuel cells. The four most important lithium minerals are amblygonite, spodumene, petalite, and lepidolite. Spodumene LiAlSi2O6 (6.0-7.5% Li2O) and petalite LiAlSi4O10 (3.5-4.5% Li2O) belong to aluminosilcate minerals. Lepidolite (Li.Al)3(Al.Si)4O10(F.OH)2 (3.30-7.74% Li2O), lithium mica, is the most important representative of the mica minerals, a subgroup of the aluminosilicates. It frequently contains 3–5% Rb2O and eventually caesium. Zinnwaldite, which has the general formula K(Li.Al.Fe)3(Al.Si)4O10(F.OH)2 (2-5% Li2O), is regarded as a variety of lepidolite with a high iron content. Commercial amblygonite is a complex phosphate (Li.Na)Al(F.OH)PO4 (up to 9.88% Li2O), however, its deposits have not been commercially exploited because of their small size. Natural brines with a high lithium chloride content are important in the industrial production of lithium [l]"

Jan 1, 2008

By F. D. S. Marquis

An investigation of the mechanisms of formation of two types of porosity-primary and secondary-their characterization, evolution during processing, and effects on the mechanical behavior (fracture, fatigue, and failure) of 7X50 and 2X24 alloys has been conducted. The mechanisms of formation of three forms of primary or cast porosity were investigated, and each form was characterized: (a) macroscopic shrinkage porosity-MSP); (b) microscopic interdendritic porosity (MIP); and (c) hydrogen gas porosity (HGP) or primary hydrogen porosity (PHP). The mechanisms of formation of four forms of secondary or thermal/thermomechanical porosity were investigated, and each form of porosity was characterized: (a) high temperature oxidation (HTO). internal hydrogen precipitation (IHP), or secondary hydrogen precipitation (SHP); (b) preheating blistering porosity (PBP); (c) eutectic melting porosity (EMP);and, (d) dissolution micro void formation (DMF). The evolution and interactions of the primary and secondary types of porosity (w.ith special emphasis on PHP and SHP) during industrial and laboratory processing and their effects on the fracture and failure behavior of both types of alloys (with special focus on fatigue crack initiation and propagation) were investigated.

Jan 1, 1996

By J. E. Dutrizac

A mineralogical study of a weak acid leach residue from the Clarksville zinc plant of Savage Zinc Inc. was carried out. The study focused on Pb and Cd as these elements most significantly impact on the environmentally acceptable disposal of the residue. The residue consists of major amounts of bassanite, zinc ferrite and various Zn-Pb-Fe-Cd silicate species. Also present are lesser quantities of PbSO4, sphalerite, Fe2O3 quartz, Mn-Pb-Fe oxides, SrS04, (Pb,Sr)SO4 iron gel-silica gel, jarosite and Ti oxide. The principal Cd carriers are the zinc ferrite, which contains up to 9.00% Cd and likely accounts for -45% of the total Cd content of the residue, and the various silicate species which contain up to 6.97% Cd and account for about 45 % of the total Cd. The sphalerite is a minor Cd carrier containing an average of 0.35 % Cd and accounting for -5 % of the total Cd; the other carriers contribute only trace amounts to the total Cd content. The major Pb carriers are PbS04, Pb-bearing silicates and Mn-Pb-Fe oxides. Minor proportions of the total 1.09% Pb content of the residue are carried by SrS04 and (pb,Sr)S04' Trace Ph carriers include the iron gel-silica gel, Fe-Zn-AI oxide and bassanite. The residue after the toxicity characteristic leaching procedure (TCLP) is mineralogically very similar to the initial weak acid leach residue; the amounts of calcium sulphate are approximately the same in the two products. The principal Cd and Pb carriers are also the same as those noted in the initial residue, except that some dissolution and reprecipitation of Pb-Sr sulphate takes place. That the residue fails the TCLP test is likely a consequence of the superficial dissolution of Pb and Cd from species such as PbS04 or Zn-Pb-Fe-Cd silicate.

Jan 1, 1995

By Guy Deschênes

Thiourea solutions can be used as leach liquors to treat gold ores or slimes. It is also efficient to elute resins or strip solvents that were loaded in cyanides solutions. The hydrogen pressure reduction is a practical step to recover gold and silver from leach solutions, and strips and eluates without any destruction of thiourea. It is a critical point because these processes have to consider the recycling of the liquors to be irore economical. The effect of temperature, pressure, acidity, compotation of the solution and the nature of catalysts on pressure reduction by hydrogen were investigated. An electranetallurgical study was? carried out to investigate the mechanism. The composition of the products was studied by different analytical methods. The process shows a good selectivity to precipitate gold and silver in a thiourea solution containing iron and copper. Gold and silver concentrations can be decreased to 0.2 ppm and 0.1 ppm at respectively 70 KPa H2 and 28°C. No decomposition of thiourea was evident during the tests. Metals such as nickel powder or platinum activate the reaction and improve the reduction.

Jan 1, 1989