Search Documents

By Byung-Su Kim

The recovery of elemental sulfur from sulfur dioxide has important implications for coal- burning power plants and nonferrous metal smelters. The thermodynamic analyses showed calcium sulfide to be suitable for recovering elemental sulfur from sulfur dioxide. At the temperatures of 1023 to 1153 K under the sulfur dioxide partial pressures of 5.0 - 60.1 kPa, elemental sulfur from sulfur dioxide was recovered by its reaction with calcium sulfide. The kinetics of this reaction were measured at the same conditions using a thermogravimetric analysis technique. This reaction scheme would be attractive if the coproduct calcium sulfate can be reduced to regenerate calcium sulfide. This is the topic of another paper. At 1073 K under the sulfur dioxide partial pressure of 25.8 kPa, 48 % of the original calcium sulfide was converted to calcium sulfate in an hour. Under the same conditions, 55 % of the regenerated calcium sulfide were converted to calcium sulfate in an hour even after third regeneration.

Jan 1, 1999

By Lin Li, Xiang Li, Yifang Zheng, Jilai Xue, Jun Zhu

"Al drops and gas bubbles in the anode-cathode space of aluminum electrolysis cell are of great importance for cell operation improvement in metal loss, current efficiency and energy consumption. A direct observation on the Al drop, gas bubble and ultrasound was carried out through a see-through cell. The Al drop immersed into the cryolitic melt was found moving up and down irregularly in the anode-cathode space without electrolysis, which was then completely dissolved into the melt. During electrolysis, the Al drop came to the anode area and reacted with the gas bubbles generated on the anode. Under ultrasound, the gas bubbles were removed from the anode surface while the Al drop was kept on the side of anode. The observed phenomena were useful for technology improvement in reducing the anode-cathode distance or lowering the energy consumption in aluminum electrolysis.IntroductionDuring aluminum electrolysis, aluminum metal drop and anodic gas bubble are in close contact each other within the anode-cathode space, and the interaction between them can produce significant impact on metal loss, current efficiency and energy consumption. The motions of the Al drop and the gas bubble are also related to the dissolution of aluminum metal into cryolitic melt and the cell voltage drop due to the bubble layer covering the anode surface.A number of studies have been carried out using different types of see-through cells, where the dissolving process of metal Al into cryolitic melts (metal fog) in the anode-cathode space was directly observed and photographed [1, 2]. With the similar method, some direct observations on the anodic bubble behaviors with and without ultrasound were performed during aluminum electrolysis [3-6]. However, to our best knowledge, there is no published work on direct observation on the behavior of Al drops and anodic gas bubbles staying together within the same anode-cathode space, as well as the motion and interaction of them in cryolite-alumina melts."

Jan 1, 2011

By Yafei Xiong, Yue Wang, Guotao Xu, Shuzhong Li, Huaiyuan Li

"The composition, properties and structure of taphole clay with high strength and friendly surrounding used in a new blast furnace with 3800 M3 volume was studied. The developed taphole clay had been applied in the blast furnace for four months, pouring times were 11-13 every day, flowing rate of hot iron was 7.5 t/min and the consumption of taphole clay was 0.49Kg per ton iron, which can make the new blast furnace attach the designed production quickly and decrease the cost of hot iron. The taphole clay is easy to be opened in the channel of hot iron which can be remained in stable shape under the corrosion of slag or hot iron, and it dose not produce poisonous smoke in yellow or dark color in the use process. The development of new taphole clay is useful to improve the work surrounding of the blast furnace.IntroductionIn the iron-making process, the taphole clay's function is filling up the taphole and protecting the formation as well as the growth of the clay in the blast furnace, maintaining the enough taphole depth; simultaneously it is easily to open a hole and knock out the clay. The taphole clay has a good performance of molten slag and hot iron resistance. The traditional taphole clay uses coal tar or carbolineum as a binder, and the performance of taphole clay is good, but it has the black and yellow poisonous smoke, which is harmful for work condition. Through the investigation on the binder's composition and poisonous performance of taphole clay, the environmental taphole clay is developed by some foreign companies, which is named the third generation product with benzene is less than 300ppm, and it has been used in European steel companies. This application of the taphole clay with high strength and environment-friendly using in 3800m3 blast furnace is introduced and the performance is discussed and analyzed in this paper."

Jan 1, 2012

By John A. Herbst

Plantwide control of mineral processing operations has long been sought for its potential benefits. These benefits include minute-to-minute optimization, reacting to disturbances in ore characteristics and equipment status as they happen and the coordination of all unit operations in pursuit of the highest performance level. However several difficult challenges have kept us from fully realizing those benefits. One of these challenges has been to provide fairly complete quantitative descriptions of Unit operations to account for critical interactions within and 'between unit operations. In some cases we understand the physics and chemistry very well and can incorporate that 'knowledge into phenomenological models. In other cases our knowledge is incomplete, so we must rely on other forms of knowledge such as fuzzy logic or neural nets. Another challenge to be met has been to simultaneously compute a large number of manipulated variables. In the past this challenge was met by optimizing only unit-by-unit, rather than on a global basis to significantly reduce the number of variables. In this paper, a procedure that globally optimizes one or two important variables is outlined. This procedure comes much closer to true plantwide optimizing control while remaining computationally feasible. Finally, another major challenge is to choose a meaningful global objective that can be calculated With the models and can be effectively optimized. Financial goals seems to be the objectives of choice. This paper discusses recent progress In overcoming the challenges and illustrates a promising approach which is being pursued at :Mexicana de Cobre's 'La Caridad copper ore concentrator. At M de C, advanced ,control strategies have been 'installed one at a time in the crushing, grinding and flotation sections. During this period, the throughput of La Caridad, Mexico's largest copper concentrator, 'increased from 76;000 tpd to 90,000 tpd. Plantwide integration is expected' to gain an additional 3% improvement in profitability.

Jan 1, 1996

By John A. Herbst, William T. Pate

"Plantwide control of mineral processing operations has long been sought for its potential benefits. These benefits include minute-to-minute optimization, reacting to disturbances in ore characteristics and equipment status as they happen, and the coordination of all unit operations in pursuit of the highest performance level. However, several difficult challenges have kept us from fully realizing those benefits. One of these challenges has been to provide fairly complete quantitative descriptions of unit operations to account for critical interactions within and between unit operations. In some cases we understand the physics and chemistry very well and can incorporate that knowledge into phenomenological models. In other cases our knowledge is incomplete, so we must rely on other forms of knowledge such as fuzzy logic or neural nets. Another challenge to be met has been to simultaneously compute a large number of manipulated variables. In the past this challenge was met by optimizing only unit-by-unit, rather than on a global basis to significaritly reduce the number of variables. In this paper, a procedure that globally optimizes one or two important variables is outlined. This procedure comes much closer to true plantwide optimizing control while remaining computationally feasible. Finally, another major challenge is to choose a meaningful global objective that can be calculated with the models and can be effectively optimized. Financial goals seems to be the objectives of choice.This paper discusses recent progress in overcoming the challenges and illustrates a promising approach which is being pursued at Mexicana de Cobre's La Caridad copper ore concentrator. At M de C, advanced control strategies have been installed one at a time in the crushing, grinding and flotation sections. During this period, the throughput of La Caridad, Mexico's largest copper concentrator, increased from 76,000 tpd to 90,000 tpd. Plantwide integration is expected to gain an additional 3% improvement in profitability."

Jan 1, 1996

By W. K. Tolley

The U.S. Bureau of Mines (USBM) is currently investigating improved technology for mineral flotation. A variable often neglected in flotation control is redox potential. The use of redox control is illustrated by the separation of molybdenite from chalcopyrite. Laboratory testing showed that redox potential had a greater effect on product quality than collector addition. A significant need in froth flotation is greater reliability of the sensors used in measuring and controlling redox potential in mineral slurries. The USBM has developed an automated method for removing scale and reconditioning gold redox-sensing electrodes. Fouled electrodes are anodically polarized to 1.2 V versus the AglAgCI reference potential to remove scale. The electrodes then are conditioned by a brief potentiodynamic treatment to re-establish electrochemical equilibrium. In laboratory tests, this technique removed calcarious deposits from gold electrodes and reconditioned them for useful service in approximately 10 min. In plant practice, this technique would obviate the need for plant operators to manually polish electrodes, and also should result in greater reliability in redox measurements. Inexpensive, automated equipment to condition electrodes in a plant setting is described.

Jan 1, 1995

By V. P. Bystrov

Vanyukov process has been developed and investigated in Russia over the last 25 years. It has been established that various kind of material could be treated in Vanyukov process. The results of the pilot plant trials as well as industrial experience are presented in this paper.

Jan 1, 1993

By D. M. Jones

Dust generation data have been obtained from 19 industrial Outokumpu flash furnaces. Statistical analyses of the data have been carried out and the most significant factors affecting dust generation evaluated. The results indicate that dust production may most effectively be minimized by: 1) Minimizing the distance between the molten slag and the furnace roof 2) Optimizing burner design and combustion parameters.

Jan 1, 1996

By Ivan Imris

The iron production has generated many tonnes of very fine residues with high concentration of iron. In addition, during the recycling of galvanised steel scrap in the steel making processes the zinc and lead are largely concentrated in the dust. These kinds of dusts are usually dumped beside the metallurgical plants and cause environmental problems. Therefore the metal recovery from the metallurgical residues has become a major interest not only from the viewpoint of metals recycling but mainly from the viewpoint of environmental land protection. The thermodynamic analyses and laboratory experiments suggested that the metals could be recovered from metallurgical wastes by reduction roasting and by plasma smelting processes. The iron rich pellets with very high metallization may be obtained from metallurgical wastes by the reduction roasting and the inert slag and pig iron could be produced by plasma smelting processes. In both cases the iron rich products are suitable for the steel production. During the reduction roasting or plasma smelting the high volatile zinc and lead metals were removed and enriched as a secondary dust, Zn-Pb concentrate, which is suitable for processing in zinc and lead smelters. Suggested processes are commercially feasible and environmentally friendly without any solid or liquid waste.

Jan 1, 2003

By Michael L. Sorokin

The various methods of converter slag cleaning operation are analysed from the thermodynamk point of view: cleaning using coal, cleaning using combustion products of natural gas and cleaning in presence of matte. All calculations were done, applying the developing computer procedure based on the free energy minimisation algorithm. Three-suffix Margules equations were used to calculate thermodynamic properties of melts; The calculations resulted in recommendations for the practical appliance.

Jan 1, 1995

By Y. Maeda

Kosaka Smelter is a copper smelter located at the nothern part of Japan? and has been treating. complex sulfide concentrates using flash smelting technology for a long time. The flash smelting technology has an advantage in the point of controllability of matte grade and heat balance in the reaction shaft. But the disadvantage of this process, is that the dust generation ratio is high compared with other smelting process such as injection smelting technology. This reason why is that the flash smelting process is the oxidation process for the fine sulfide concentrates applying flash reaction in the oxygen enriched stream In addition of this disadvantage, the sulfide concentrates contains much volatile impurities is resulted the dust; eneration ratio more. This paper outlines the recent improvement of the flash reaction in the furnace and the behavior of impurities in Kosaka Smelter.

Jan 1, 1998

By Kevin L. Gering

A detection method and apparatus have been developed to perform real-time measurement of aqueous free cyanide, C-. A laboratory prototype can measure cyanide ranging from 5 micrograms ,per liter to 100 milligrams per ?liter for analysis times as short as 2 minutes per measurement. Sample size per measurement is typically only a few mI, thus? minimizing the waste volume produced from spent samples. The basis for this detection device is a quantifiable, stable affinity between the electrode material and free cyanide in the sample; The electrode exhibits piezoelectric behavior, allowing it to be used as a microbalance. This technology 'has experienced two generations of laboratory prototypes, and has been thoroughly tested to determine the operational sensitivity toward process variables such as pH, competing reactions, etc. The speed and ,accuracy of this method make it superior to conventional wet chemistry methods used for quantifying cyanide levels in water. A device based on this technology could be useful in areas involving process monitoring and environmental compliance, .particularly in the cyanide-based leach mining industry. Interest for this detector has been shown by the gold mining industry and others. Patent application is in progress.

Jan 1, 1998

By James T. Skoch

With the ongoing pressure on the secondary aluminum business to limit the amount of waste generated from processing aluminum dross, it becomes very advantageous to preprocess the dross to reduce waste. The advantage of preprocessing is that it significantly reduces the oxides and salt cake generated when melted. Various products can be produced from the oxides for the steel industry. The following paper will demonstrate that removal of oxide fines before melting will result in large volumes of material not being landfilled. We will show that the end result of this technology is to significantly reduce the amount of salt cake sent to a landfill while maximizing the recyclability of the aluminum dross.

Jan 1, 1995

By H. Y. Sohn, S. PalDey

"Fine particles of nickel aluminides and Ni4Mo were synthesized by reducing mixtures of, respectively, A1Cl3 + NiC12 and NiC12 + MoC12 vapors with hydrogen. Though thermodynamically favorable, the coreduction of NiC12 and A1Cl3 by H2 to form Ni3Al did not readily happen experimentally. The addition of a small amount of aluminum vapor was needed to initiate the coreduction reaction. The product particles as observed by TEM were very fine but usually agglomerated. The electron diffraction pattern of particles identified NiAl and NiA13 along with Ni3Al and metallic Ni. The content of Ni3Al was maximized at 52 mol% at 1050°C under the partial pressures ofH2, A1Cl3, and NiC12 at 57, 1.4, and 0.5 kPa, respectively. When a mixture of NiC12 + MoC15 was reduced by hydrogen, Ni4Mo particles with some Ni or Mo particles were obtained, the maximum content of Ni4Mo obtained being 93 mol % . The particle size was in the range of 100 to 200 nm. An Ni4Mo coating of 700 nm thickness on an Ni substrate was also prepared.IntroductionThe search for new high-temperature structural materials has stimulated much research on intermetallic compounds. Nickel aluminides have low densities, relatively high melting points, and good high-temperature strength properties. They show an increase, rather than a decrease, in yield strength with increasing temperature (1). Ni4Mo is also of interest as a high-temperature structural material. The major shortcomings of these intermetallics are their inherent brittleness at room temperature when they are in polycrystalline form. For much the same reason, the conventional casting of intermetallics is difficult. Ingot metallurgy and powder metallurgy are two other processing techniques. The first technique is quite energy consuming. In powder metallurgy, the powders of metals and alloys are consolidated in near net shape and then subjected to secondary processing. It would, therefore, be advantageous if intermetallic compounds can be produced in fine powder form from inexpensive raw materials, using less energy."

Jan 1, 1998

By Hiroshi Tabuchi, Akihiko Takahashi

"High strength aluminum matrix composites were prepared and studied using as reinforcement newly developed nearly mono-dispersed a-alumina single crystal particles each of which has a regular polyhedral shape. The composites were formed by centrifugal casting using aluminum casting alloys (Al-Si and Al-Cu-Mg) as the matrices, followed by heat treatment. The volume fraction of the alumina particles was as high as 60%. The same matrix composites reinforced by conventional crushed fused alumina particles were similarly prepared as the reference. The bending strength and tensile strength of the Al-Cu-Mg matrix composites reinforced by the novel alumina particles of 10 µm in average diameter are as high as 1020 MPa and 560 MPa, respectively, which are higher than those of the conventional alumina composites. Furthermore, the bending strength of the novel alumina composites degraded less than that of the conventional alumina composites after thermal fatigue tests. The number of cracks in the matrix seemed to influence the thermal fatigue property because many cracks were observed in the conventional alumina composites, whereas only a few cracks were observed in the novel alumina composites. This was confirmed by SEM observation of the sample composites before and after the thermal fatigue tests.IntroductionAluminum matrix composites strengthened by dispersed reinforcements are of interest for various applications due to their improved properties, such as high specific strength and stiffness, wear resistance, etc .. A large number of investigations have been made concerning fabrication processes and properties of these composites. With regard to the fabrication processes, powder metallurgy has been well-known as a solid phase process, and recently many liquid phase processes such as a compocasting, a squeeze casting, the Lanxide process, and the Osprey process have been studied and developed.(1)"

Jan 1, 1998

By V. M. Lsoitko

Statistical methods of technological mineralogy are used to model processing flowsheets in order to improve ore dressing efficiencies. The procedure involves determining geological and mineralogical characteristics of ores, classifying ore types and metallurgical procedures, and developing computer programs to interpret essential mineralogical parameters from on-stream analysis data. The on-stream analysis data include magnetism, radioactivity, luminescence and assays. The data are interpreted by computer and appropriate adjustments are made automatically in the plant.

Jan 1, 1989

By Elliot Schwartz, Julian Szekely

"In this paper we describe an experiment that was recently performed on the IML-2 Space Shuttle mission in which the thermophysical properties of molten metals were measured using electromagnetic levitation. In the planning of these experiments calculations had to be performed to predict the levitation and stirring forces, heating rates, sample deformation, and internal flows within the sample. These predictive calculations were essential for both the planning of the experiments and for the re-planning of experimental runs during the actual Space Shuttle mission.Introduction""Materials Processing in the Computer Age"" involves the use of mathematical modeling to obtain a quantitative understanding of the phenomena that govern materials processing operations. Microgravity, or space shuttle experimentation represents a specific case in point here; the very high cost of the space shuttle flights, the very limited flight opportunities that are available, and the tight resources aboard a shuttle clearly mandate that these experiments be very precisely planned and that all possible opportunities for mathematical modeling be fully exploited.The purpose of this paper is to present the results of calculations performed for the planning of a space shuttle experiment involving electromagnetic levitation and wherever possible present a comparison of the computational predictions with both experimental measurements and asymptotic analyses. Finally we shall seek to discuss the practical implications of both the computational methodologies and the potential experimental findings."

Jan 1, 1994

By M. B. Mesina

Mechanical separation systems are widely used nowadays for scrap metal processing, but they have natural limitations in product quality. The quality of the final product is considerably improved when sensors are used in the separation process. This paper describes new methods using sensors for scrap metal sorting and quality control. An example is the electromagnetic sensor, which uses the electrical and magnetic properties of materials to distinguish between different non-ferrous metals. The measurement results of two prototypes are reported. The benefits and the possibility to integrate such systems into practical applications regarding the processing of secondary raw materials are also described.

Jan 1, 2003

By K. S. Izbakhanov

The Chimkent Lead Plant was constructed in 1934 and since that time has undergone many revisions. In 1975 the slag fuming operation was changed from pulverized coal to natural gas fuel. In 1981 the slag fuming furnace water jacket system was converted to evaporative cooling with high pressure steam production. The impact of these changes and the method of their application are described.

Jan 1, 1990

By C. Palacios

The Plant, which was started up in April 1970, was originally designed for a capacity of 40.000 ton of cathodes per annum, using 12 sections, containing 408 cells. Since then the addition of another 8 sections containing 280 cells and using the Reverse Current System has made possible the increased output of 109.000 ton. The quality of the cathodes produced is excellent. The extension of the Electrolytic Refinery, by the introduction of the Reverse Current System, has been a great success and no problem has arisen in the new equipment or in the modifications carried out in the plant. The operation of the plant has improved due to better control procedures.

Jan 1, 1976