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By Won C. Park

Experiments showed changes in the mineral content of dolomitic oil shale at temperatures and exposure times which bracket conditions encountered during in situ retorting. Laboratory results correlate with cores from a spent in situ retort at Occidental's Logan Wash test site at Garfield County, Colorado. Dolomite, CaMg(CO3)2, decomposes rapidly to form periclase, MgO, calcite, CaCO3, and CO . Both calcite and periclase are intermediate products that can be stabilized by CO atmosphere at lower temperatures, while steam accelerates the formation 2 of silicates. The decarbonation of calcite appears to involve a direct reaction with both quartz and periclase in forming these silicates. Decarbonation preceeds the formation of akermanite, Ca2 MgSi 207, and diopside, CaMgSi 206, within several hours of heating and is followed by the nucleation of forsterite Mg2SiO4, and monticellite, CaMgSiO4. Under in situ retorting conditions, akermanite and diposide are the major minerals above 800°C. Equilibrium is not attained within 200-300 hours. In situ retorting temperatures above 800°C for extended periods of time should reduce potential ground water leaching by the formation of silicate minerals. These silicates are less soluble than free lime, magnesium or alkali oxides. There is a corresponding decrease in the natural pH of these silicates from approximately 12 down to 7.5 to 9:

Jan 1, 1981

By W. M. Cross

Bubble attachment time measurements for the rare-earth phosphate minerals monazite and xenotime were made as a function of oleate concentration, sodium fluoride addition, and temperature. Results indicate that the rare-earth phosphates behave similarly to other phosphate minerals, notably collophanlte and fluorapatite, which have been studied previously. The addition of sodium fluoride yielded a modest decrease in bubble attachment time with fluoride additions below the apparent fluoride surface precipitation point, while at fluoride additions greater than the apparent precipitation point a significant decrease in attachment time occurs. Increasing the temperature or the system gave a slight decrease in bubble attachment time in the absence or sodium fluoride. With sodium fluoride addition and below the apparent fluoride surface precipitation point, an increase in temperature actually increased the attachment time. For sodium fluoride additions above the apparent fluoride surface precipitation point, a temperature increase significantly decreased the attachment time.

Jan 1, 1989

By H. Ikeda

The new Onahama N0.3 tankhouse was put into operation early in 1973. This new tankhouse, which has a capacity of 90,000 metric ton cathode per year, is distinct in many important respects from conventional tankhouses. The major objectives in design were to simplify the construction and ope- ration for reduction of the costs for labor, interest and depreciation and also to reduce the copper inventory in the tankhouse by the use of conti- nuously-cast anodes. As a result, the investment cost was decreased by approximately 30% and the inventory cost by approximately 600, while the production per unit area of the tankhouse was increased by 80 - 100% as compared with the existing conventional-type tankhouses at Onahama. By abolition of cell inspection and maximum mechanization of materials handling the labor cost was decreased by as much as 80%. On the other hand, the new system has some disadvantages, such as increase in anode scrap ratio and increased cost of anode casting. The No.3 tankhouse system is, however, still at its starting point, while conventional methods have been continuously improved over the past years of operation. It is expected that the innovational ideas behind this system will serve as bases for a more efficient electrolytic refining system in future.

Jan 1, 1976

By Cem Colakoglu

In this study, nickel containing iron alloys were produced by carbothermal reduction of lateritic nickel ores obtained from Manisa - Caldag region of Turkiye in order to investigate the reaction mechanism of nickel and cobalt. In the experiments, the lateritic ore containing 1.58 wt.% Ni and 0.12 wt.% Co was calcined in a semi-pilot scale rotary furnace at 1100°C for 1 hour. Then, a mixture of calcined ore and metallurgical coke was reacted in sintered alumina crucibles using a graphite resistance tube furnace at different time (0- 60 min) and temperature (1500-1600°C).

Jan 1, 2009

By Sergio N. Monteiro

Jute fiber reinforced polymer composites are among the most investigated and applied natural composites. In this past decade the mechanical properties of these composites has been assessed for various types of test conditions. However, the reported results correspond mainly to short-cut jute fiber composites, which do not present the highest mechanical strength as compared to continuous fibers of the same kind. In order to complement these results, the present work evaluated the mechanical behavior, by means of flexural tests, of polyester matrix composites reinforced with continuous jute fibers. Bend tests were conducted in standard specimens with up to 40% of jute. Fracture analysis by SEM displayed the rupture mechanisms. The results showed an improvement in some flexural properties with incorporation of jute fiber. However, a low fiber/matrix interfacial stress was responsible for limitation in the values attained by some properties.

Jan 1, 2010

By E. I. Gedgagov, A. V. Tarasov, V. M. Paretsky, A. D. Besser

"Hydrometallurgical technology and equipment have been developed in the Gintsvetmet Institute (Moscow, Russia) for processing of rhenium-containing alloys waste to produce commercial- grade metal products with recovery of all valuable components. The technology is based on waste treatment with hydrofluoric acid with subsequent decomposition with nitric acid at pH = 1 to 1.5 to ensure maximum degree of rhenium conversion to the liquid phase of pulp. Some experimental lots of ammonium rhenate and ammonium molybdate were produced at a pilot plant. The following main techno-economic performance values have been achieved when processing grinding residues (balance-based tests were conducted with a lot of SP-2 alloy waste) to produce ammonium rhenate of high purity, as well as tantalum-niobium, nickel-cobalt and tungsten-molybdenum concentrates: rhenium recovery of 92.3% into a commercial product from grinding waste; production cost of 170-210 US Dollars per 1 kg of rhenium in commercial-grade ammonium perrhenate taking into account its recovery; tantalum and niobium recovery of 75- 77% into bulk concentrate; nickel and cobalt recovery of 88-89% into a mixed concentrate; tungsten and molybdenum recovery of 88% to 91% into concentrate. Introduction During the recent years the use of rhenium has been increasing at a fast pace worldwide [1]. The growing prices for this refractory metal are an essential factor encouraging collection and processing of rhenium-containing wastes. Double-component waste, such as molybdenum- rhenium or tungsten-rhenium alloys can be readily decomposed and the process of rhenium recovery does not cause, therefore, any difficulties. The main separation of metals takes place at the stage of waste digestion with acid, because molybdenum and especially tungsten remain in precipitate in the form of hydrated oxides and rhenium reports in the liquid phase, from which it can be easily extracted by solid ion-exchange or solvent extraction techniques. However, most of rhenium is contained in super-alloy waste [2]. Such waste has different contents of valuable components, such as tantalum, niobium, molybdenum, tungsten, cobalt, nickel, chromium and other metals. The basis of all such super-alloy waste is nickel. Refractory metals in the super- alloy composition are in the form of metallized target-oriented eutectics, and due to this reason hydrometallurgical decomposition of such alloys is a difficult technological task."

Jan 1, 2008

By S. Djaroudib

Keywords: iron recovery, hematite, hydrolysis, polyvinylpyridine The precipitation of hematite (Fe2O3) from ferric chloride media at ambient pressure and at temperatures below 100°C was studied as part of a program to recover a marketable iron product form metallurgical processing streams and effluents. Hematite was formed in preference to ferric oxyhydroxides (e.g. ß-FeO?OH) by controlling the precipitation conditions, especially by adding Fe2O3 seeds. The extent of the hydrolysis reaction was found to depend primarily on temperature and on the free-acid concentration. As to the latter, the controlled addition of an adsorbent of free acid, in our case the anionic resin polyvinylpyridine (PVP), was shown to allow for the nearly complete removal of iron as readily filterable Fe2O3. The hematite product typically contains = 63% Fe and = 1.5% Cl, and its composition does not change appreciably upon repeated cycling using regenerated PVP.

Jan 1, 2005

By Hongyang Cao

The iron constituents selectively separated from the modified copper slags by magnetic separation and flotation.were studied. The results of magnetic separation for modified copper smelting slags show that the grinding size, current intensity and dispersant agent had great influence on grade, and recovery ratio of TFe in preparation concentrate; The results of flotation for magnetic concentrate show that the positive flotation of sodium oleate negatively upgrade the grade of magnetic concentrate, but the reverse flotation of lauryl amine and soluble starch are effective. The grade of TFe can reach 54% and the recovery ratio can reach about 90% in magnetic concentrate, when the grinding size is 45.8µm and the current intensity is 2.5A. The optimal effect is obtained by using lauryl amine as collector and soluble starch as depressant to reverse flotate magnetic concentrate, and the grade of TFe is upgraded 2.37%.

Jan 1, 2009

By Frank R. Field, Randolph E. Kirchain, Elisa Alonso

"There are a number of environmental incentives for increasing recycling, including the reduction of waste, energy and resource use. Recycling can also be advantageous for manufacturing firms in both the short and long term. Secondary material can substitute for primary material, potentially dampening primary material price increases and reducing the pressure for greater primary extraction. This paper examines the potential for and dynamics of recycling for the case of platinum using a dynamic, behavioral simulation model of the primary and secondary markets. Since the secondary supply of platinum depends on a supply chain separate from primary extraction, recycling can diversify the risks of primary supply instabilities. Over time, recycling can cut primary consumption, reduce overall costs to firms, and possibly reduce the impact of price fluctuations upon firms.IntroductionThe benefits of recycling, from the perspective of the environment, are many, and the environmental benefits of increased recycling are considered a step towards increased sustainability [1, 2]. Life cycle assessments indicate that obtaining materials from secondary sources generally requires less energy and has fewer environmental impacts than extraction and refining of primary materials [3]. Analyses of materials flows show that, in addition to landfill volume reduction, recycling reduces primary material consumption, affecting long term materials scarcity [4, 5].The benefits of recycling are not limited to the environmental. Firms can benefit from the lower energy costs of recycling, especially that of metals whose primary extraction and refining are particularly energy-intensive (e.g., aluminum). The routine participation by firms in secondary materials markets (e.g., www.recycle.net) shows that this advantage has not gone unnoticed.Recycling can also benefit firms whose costs can be significantly affected by changes in material prices resulting from material shortages and material scarcity, with potentially permanent effects upon firms [6-8]. This paper focuses on the impact of recycling in the face of platinum scarcity for supply chain downstream firms."

Jan 1, 2008

By Fumito Tanaka

The Mitsubishi Process is the sole pyrometallurgical process for the continuous production of blister copper from copper concentrates. Continuous converting originates from the application of the proven technology of a lime-ferrite slag (CaO-FeOX-Cu2O) on the Converting Furnace (C-furnace). Recent improvements on the C-furnace operation have included increasing the processing of recycled materials and the investigation of alternative fluxing agents. However, some minor oxides adversely affect C-furnace operation, with respect to magnetite behavior of the slag, with the most significant impact having been observed with the silica content of the slag. This paper will quantify the impact of silica on the lime-based slag, and discusses the controls that have been identified to sustain continuous converting operation.

Jan 1, 2005

By G. N. Shannon

Keywords: inclusions, slag, modeling, interfacial energy, capillary force, particle flotation, particle separation A previously introduced model of inclusions separating across a steel-slag interface, developed by Nakajima/Okamura and Bouris/Bergeles, is expanded to include different inclusions shapes (octahedral and plate-like, besides spherical) as well as comparison between model ladle-, tundish-, and mold-slags. Investigation of the relation of these shapes with the interfacial capillary force ? which arises due to the dynamic interfacial energy during separation ? has shown that the force has a significant effect on whether the inclusion separates rapidly or settles at the interface. For the slags considered, the most significant physical property is found to be viscosity, which resulted in fast separation times for inclusions in the mold and ladle slags, relative to the more viscous tundish slag. Particle dissolution (using experimental data) is included in separation modeling.

Jan 1, 2005

By Tang Chaoho

Laboratory research on the reducing and matte smelting of Jamesonite concentrate has been carried out. The influence of the process conditions such as the smelting temperature, the amount of pyrite cinder (the agent of fixed sulfur) and the amount of additives on the smelting process have been studied. Under the optimum condition the direct recovery ratios of antimony and lead are 83.26% and 68.50% respectively. The ratio of fixed sulfur is 98.97% but more than 15% lead and 30% silver remained in the ferrous matte. The key problem to be solved of this new process is how economical and effective is the recovery of silver and lead in ferrous matte.

Jan 1, 2003

By Tang Chaoho

Laboratory research on the reducing and matte smelting of Jamesonite concentrate has been carried out. The influence of the process conditions such as the smelting temperature, the amount of pyrite cinder (the agent of fixed sulfur) and the amount of additives on the smelting process have been studied. Under the optimum condition the direct recovery ratios of antimony and lead are 83.26% and 68.50% respectively. The ratio of fixed sulfur is 98.97% but more than 15% lead and 30% silver remained in the ferrous matte. The key problem to be solved of this new process is how economical and effective is the recovery of silver and lead in ferrous matte.

Jan 1, 2003

By H. Antrekowitsch

The decreasing quality of the input materials in copper recycling leads to a higher content of impurities in the anode copper. An improvement of the pyrometallurgical refining process is therefore necessary to produce high quality anodes for the copper refining electrolysis. The behaviour of the most important accompanying elements (e.g. nickel, tin, lead, zinc etc.) at different reaction conditions has to be investigated in order to improve the metal/slag reactions as well as the vaporisation by selective oxidation in the anode furnace. Therefore the thermodynamic conditions like reaction order and the activity coefficients at the copper refining process have to be known for the optimisation of this technique. Additionally the interaction between different elements has been investigated as a function of the temperature, the content of the elements and the slag composition especially for nickel. These investigations were done at the Christian Doppler Laboratory for Secondary Metallurgy of Nonferrous Metals.

Jan 1, 2005

Conventional ferronickel smelting has five main steps: Drying, calcination, prereduction, smelting and refining. In the scope of the current work, smelting experiments were conducted using Sivrihisar laterite ores (1.26% Ni) of Turkey. The ore samples previously subjected to drying, calcination and prereduction stages were smelted in alumina crucibles in a laboratoryscale horizontal tube furnace under argon atmosphere. Smelting experiments were performed at 1500, 1550 and 1600 oC. The amount of excess coal used in prereduction step was another variable. Sivrihisar laterite ore is a limonitic one with low MgO composition. Therefore, MgO was added to the smelting charge as a flux. The effects of experimental variables on metal Ni content and slag composition were investigated.

Jan 1, 2012

By W. J. Mitchell

During the months of April and May 1992, the Phelps Dodge Hidalgo smelter underwent a major turnaround. This was the third such turnaround in the life of the facility which was commissioned in 1976. During the third furnace campaign, the smelter processed 5.2 million tons of concentrate producing 2.6 billion pounds of anode copper over a 7.5 year period. The critical path on the fifty-nine (59) day turnaround schedule was the reconstruction of the Outokumpo flash furnace which integrated some modifications with standard rebuild practices. Modifications included incorporation of horizontal cooling jackets throughout the furnace settler as well as the installation of castable refractory in the reaction and uptake shafts.

Jan 1, 1993

By D. C. Lynch

While a sizable amount of data exist as to the activity and distribution of minor elements between matte and metal, there has been no unifying theory presented delineating the form of dissolution of these elements in molten sulfides. In order to alleviate that deficiency the literature concerning the behavior of As, Sb, Bi and Pb in mattes is reviewed. Models present in the literature, regarding the thermochemical behavior of minor elements, are tested, and new models are presented and evaluated using thermodynamic theory. The results of those analyses are used to predict optimum conditions for the volatilization of minor elements. The dearth of data on the behavior of minor elements in nickel mattes requires that this review focus on copper- iron mattes. An effort is made, however, to utilize basic knowledge regarding nickel sulfides and the interaction of nickel with the minor elements to predict the behavior of those elements in nickel-copper and nickel-iron mattes.

Jan 1, 1993

By Kunihiko Takahashi, Gjergj Dodbiba, Hisayoshi Umeda, Toyohisa Fujita

"An increasing number of mobile phones is increasing the number of the discarded mobile phones. Many efforts are thus being made to collect and recycle these devices. This paper is a short introduction of the recycling system of precious metals from the discarded mobile phone, currently available in Japan. Moreover, an attempt has been made to compare the energy recovery and the mechanical recycling of plastic wastes from the discarded mobile phone. The assessment has been carried out in the context of the life cycle assessment methodology (LCA). The environmental impact of each option was assessed by calculating the following impact indicators: depletion of abiotic resources (ADP), and global warming potential (GWP). 1. Introduction In 2003, the demand for mobile phones was increased since the camera was included in a mobile phone and the 3rd generation of mobile phones was introduced. In turn, the number of discarded mobile phone is rising sharply. Generally speaking, all the metallic parts of mobile phones can be recovered and recycled by using smelting and purification techniques. The recycled materials are then used to fabricate other new products."

Jan 1, 2008

By V. J. Ramirez, A. M. E. Noguez, M. J. Navarrete, B. G. Salas, N. T. Robert

"The close die forging stress in truncated conical cavities is evaluated with dimensional analysis. Five dimensionless groups are proposed from the process variables in order to simplify the forging stress determination. These groups are experimentally related and graphically expressed. This methodology can be used to predict the actual forging stress in industrial close die forgingThe use of the dimensionless groups allow to comprise more cases than the presented here, provided similar geometries and operational conditions.Introduction.Closed die forging is essentially a plastic deformation inside a two piece mold (forging die) with the inverted shape of the actual forging geometry. This plastic deformation will always be the result of a compressive stress. There are theoretical models which include complex calculations for the analytical determination of stresses (1, 2, 3, 4). Results of these calculations are approximate, requiring generally ulterior tests to obtain the true operational conditions(5).In this paper, it is presented a simplified approach to the actual compression stress needed in the forging. A well known tool in engineering: the Buckingham's Pi theorem in conjunction with dimensionless groups and a working piece scale model is used. Dimensional analysis will give the dimensionless terms needed to experiment with a selected scale model geometry to make the stress determination. The results presented demonstrate the reliability of this methodology."

Jan 1, 1997

By Rainer Schmid-Fetzer

"Isothermal solidification can be used to form strong bonds at low temperature which remain solid at much higher temperatures. The exploitation of this principally known technique for new high temperature processing steps and applications in electronic assemblies is the aim of this study. Three basically different variants of this bonding process are given. A comprehensive metallurgical screening is performed and the feasibility of binary material systems is given on a quantitative scale. Very attractive systems are spotted that have never been studied before. Detailed examples for the realization of bonding with complex ternary and multilayer systems are given. A highly innovative example is the chip stack or wafer to wafer bonding of unmetallized Si or SiC at 250°C. The proposed bond remains stable above the melting point of Si and enables entirely new semiconductor manufacturing steps. An improved die bonding process was proposed and verified experimentally.1. IntroductionIsothermal solidification can be applied to form strong bonds at relatively low temperature which remain solid at higher temperatures. The general principle of this type of joining processes is illustrated in Fig. 1. An interlayer of a low melting component, Lo, is provided as a foil or a thin film coating between the high melting joint components, Hi. The assembly is heated under moderate pressure to the bonding temperature, T 8 , and a liquid filler forms, either because the melting point of Lo is exceeded or due to a eutectic reaction between Lo and Hi. This molten filler initiates a rapid interdiffusion or reaction diffusion between Lo and Hi and the subsequent approach to an equilibrium state results in isothermal solidification. The solid phases formed at T 8 in the joint region exhibit a remelt temperature above T8 •"

Jan 1, 1996