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By M. G. Basavaraj, S. Sarkar, G. S. Gupta, P. D. Patil

"Previous experimental study on raceway size hysteresis on two-dimensional cold model showed that the inter-particle and wall-particle friction had a very large effect on the raceway size. Existing literature correlations for raceway size ignore the frictional effects. It has also been shown in the present study that their applicability to the ironmaking blast furnace is questionable. To take into account the effect of friction on the raceway size a stress analysis has been done for the raceway region. Two-dimensional fluid flow equations under turbulent conditions have been developed and solved computationally in order to get the pressure forces. The frictional forces were obtained in terms of stresses. To predict the raceway size a force balance was done for the raceway zone considering the pressure force, the frictional force and the bed weight. The resulting equations from the force balance are able to describe the raceway hysteresis phenomena reasonably well along with the raceway size. A two dimensional experimental set up has been fabricated in order to validate the computer predictions. Predicted values agree well with the experimental values.IntroductionWhen a high velocity blast of air is introduced into a packed bed through a tuyere, a cavity is formed in front of the tuyere. This cavity, formed in the iron-making blast furnace, is called the raceway. Coke tumbles down and bums in this raceway, generating heat and reducing gases for the iron-making process. The raceway is responsible for producing most of the reducing gasses in the blast furnace. In addition, the size and shape of the raceway determines the movement of solids within the blast furnace, the distribution of gases and liquids (slag and metal), setting the location where the primary chemical reactions occur and the temperature profile in the lower part of the blast furnace.Due to the importance of the raceway, many investigators l - 6 have studied it and have predicted the raceway size using the empirical correlations based on experimental (hot & cold) and mathematical models. A number of correlations have been reported in the literature to predict the raceway size by various investigators3 - 6 which are different to each other. Each of the correlations shows a different dependence of raceway diameter (DR) on bed height, particle size, solid density, bed voidage and blast velocity. None of the correlations includes the effect of solid stresses on the raceway size and shape. The magnitude of these stresses will depend on the bulk solids properties (internal angle of friction, wall angle of friction) and the bed dimensions."

Jan 1, 2001

By Donna L. Bodine

The ability of oxidized Upper Freeport bituminous coal to adsorb Cu2+, Cd2+ and Mn(VII) from very dilute aqueous solutions has been studied. Low-rank coal is known to adsorb heavy metal ions from dilute, aqueous solutions, probably by ion exchange and/or chelation by acidic functional groups on the coal surface. However, it would be advantageous to use higher rank coals for water treatment. Coal samples were oxidized thermally or by 30% H202 to increase the surface concentration of phenolic and carboxylic groups, then portions were shaken with Cu2+ and Cd2+ solutions. Acidic KMnO4 was also used to oxidize coal, with concurrent sorption of the resulting Mn(IV) and Mn(ll). The effect of oxidation treatment, metal ion concentration, and solution pH on metal uptake kinetics was investigated. Potential applications for treating effluents, especially those containing oxidizing ions, are discussed, along with possible flowsheet options.

Jan 1, 1995

By David E. Hardt

"One of the critical variables to be controlled during arc welding is the size or geometry of the weld pool. The measurement of pool geometry has become an increasingly important problem with the advance of welding automation and control, and this paper addresses that problem. The basic concept of pool size estimation via measurement of pool dynamics is presented. The theory underlying this concept is discussed and is followed by a review of the current work in this area. It is concluded that pool dynamics can be characterized by natural frequencies of oscillation, for stationary welds, and that these can be measured by appropriate signal processing performed on the arc voltage. However, it appears that only full penetration welds show a strong correlation between weld size and natural frequency. Also, the extension of these results to the realistic case of moving welds has yet to be considered in detail. Nonetheless, this method of in-process measurement for real-time weld process control is still quite attractive where applicable since it can be accomplished simply by modifying the arc current schedule and by signal processing of the arc voltage.INTRODUCTUIONThe study of welding process control has been dominated by research into methods of in processing sensing of the weld pool geometry. While it has been shown feasible to measure the topside pool geometry using video methods [1,2], the penetration or backside bead width have remained elusive quantities. This is particularly true if a topside sensor location is required.The concept of using weld pool motion as a pool geometry sensing method was proposed by Hardt et al. [3] and later demonstrated by Hardt and Zacksenhouse [5] and Richardson and Renwick [6]. The concept is based on the fluid dynamics of a pool constrained by a solid container and by significant surface tension forces (i.e. a small shallow pool, not a ""pond"" or ""lake""). Such a pool, if subjected to external forces, will exhibit a surface motion is a function of that force, the properties of the fluid, the surface tension, and the shape of the container. Thus, if this motion can be excited and measured, and the relationship to the pool geometry determined, a means of sensing pool shape will exist."

Jan 1, 1986

By Katsuyoshi Tatenuma

"In order to mitigate the effect of global warming by preventing the accumulation of atmospheric CO2, a permanent fixation method of surplus CO2 as an insoluble mineral onto the sea bottom is proposed. As the proposed reduction method of atmospheric CO2, the concrete concept of this method is to form an insoluble carbonate mineral (CaCO3) by direct electrolysis of the seawater; Ca2++2HCO3 -+OH- ? ?CaCO3(insoluble)+CO3 2- (soluble)+H++H2O <not as coral reef reaction>, are directly disposed of itself onto the sea bottom. By this treatment, a concentration of carbonate is reduced in the section of superficial seawater, and therefore the absorption capacity of atmospheric CO2 increases depending upon the shift of chemical carbon equilibrium between the mass of superficial seawater and the atmosphere. As no additives are required, or no secondary waste are produced, the proposed method assuming as green-orientated, has possibility to resolve fundamentally the problem of global warming in a green orientate manner.IntroductionRecently, the amount of atmospheric CO2 has been exponentially increasing and it is a main greenhouse effect gas causing the global warming [1, 2]. The concentration of atmospheric CO2 has increased more than 30% (370ppm in 2001) during only last two centuries, therefore approximately 750 Gton-C of CO2 currently exist in the atmosphere, in which 180 Gton-C of CO2 are accounted for the increment during two centuries [1, 3, 4]. In order to avoid the progressive increase of CO2 global abundance, 3 Gton-C of the incrementing amount per year [4], have to be removed annually from the atmosphere."

Jan 1, 2008

By Robert E. (Bob) Brown

Magnesium was discovered by Davy in 1808. The production processes as they exist are not economically competitive with aluminum The electrolytic magnesium process is divided into two steps; one to make the MgCh feed and the other to apply large amounts of electric current to dissociate the feed into magnesium (450 g) and chlorine (1200 g). The production of fuJIy anhydrous, pure cell feed is a major problem Recently, there has been a growth of thermal processes, mainly the Pidgeon silicothermic production process using FeSi to reduce dolomite in horizontal retorts. Pechiney has a large vertical electrical furnace process that also uses FeSi to reduce calcined dolomite in a molten bath containing alumina. Work is proceeding to develop new or modified processes that will greatly improve magnesium production. The present methods and the research and R&D will be reviewed in this paper.

Jan 1, 2001

By K. J. Murphy, A. R. Smith, A. P. Odorski

"The need for large quantities of oxygen for use in metallurgical processes was a major driving force in the commercialization of tonnage air separation plants. Oxygen, nitrogen and argon impact the quality, energy efficiency and environmental aspects of metals production. Cryogenic air separation processes have been used to supply most industrial requirements, however, newer technologies are available or under development to meet the needs of today's and tomorrow's metallurgical processes. This paper reviews the technical features and state of development of adsorption, chemical, cryogenic and membrane technologies. The technologies are compared in terms of plant size, oxygen purity and pressure, nitrogen and argon co-production, product use pattern and back-up requirements. Computer control systems are described that optimize operation over varying load patterns and ambient conditions; substantially lowering energy consumption. IntroductionOxygen production totalled 390 billion cubic feet in 1987. Although current production is lower than the peak of 455 billion cubic feet reached in 1979, oxygen remains the fifth leading chemical product manufactured in the u.s. (1) Metals manufacturing and fabrication accounts for sixty percent of the oxygen consumed in the u.s. Oxygen use in the steel industry consists of air enrichment for conversion of iron ore, purification of the iron in basic oxygen or other furnaces, and for cutting and welding the finished steel product. Nonferrous ores are smelted in oxygen enriched atmospheres to reduce energy consumption and increase capture of sulfur compounds to meet environmental requirements. In the future oxygen usage is expected to become even more important in metals production as energy costs increase, environmental standards become more stringent, and as new coal based processes become commercialized. Oxygen usage per ton of metal in the new direct reduction processes can be up to ten times higher than traditional steel making."

Jan 1, 1988

By D. L. Yopps

Platinum-group metal (PGM) flotation .. concentrate from the Stillwater Complex, MT, was subjected to biooxidation using Thiobacillus ferrooxidans in an effort to break down the sulfide minerals and liberate the ? associated PGM&apos;s for subsequent chemical leaching. Bacterial treatment oxidized up to 94 pct of the sulfide present, destroyed the PGM-bearing pentlandite [ (Ni,Fe),9Ss) mineralization, and dissolved most of the nickel in the concentrate. Results showed that increased sulfide oxidation during the biological stage led to improved PGH recovery in the subsequent. chemical leaching stage. cyanidation at 80° c proved to be the best chemical leachant tested. It removed 7.6 pct of the palladium, 94 pct of the rhodium, 97 pct of the gold, but only 34 pct of the platinum from the biooxidized concentrate.

Jan 1, 1991

By Atsushi Shibayama

The aim of this research was to develop a copper recovery process from mine tailings (0.34%Cu) using flotation followed by high-pressure oxidative leaching (HPOL) and solvent extraction. The results of HPOL using the concentrate of mine tailings obtained by flotation under the optimal conditions of the previous study shown that an efficient copper dissolution of 94.4% was achieved in an H2O media, while the copper concentration of PLS reached to be 2.9 g/L. The solvent extraction of PLS obtained from the optimal HPOL showed that 91.3% copper was recovered in stripped solution under the determined optimum conditions, in which the copper concentration achieved to be 44.8 g/L. Finally, a proposed copper recovery process from the concentrate of mine tailings was developed by combination of HPOL and solvent extraction, while a total copper recovery of 86% was achieved.

By W. K. Collins

Engineered Scavenger Compounds (ESCs), developed by the U.S. Bureau of Mines, are a novel class of compounds that can selectively recover a desired element from a solid or molten alloy. Lithium titanate (Li2Ti3O7 or L&apos;20-3T&apos;02) is being used as an ESC to recover lithium (Li) from Aluminum-Lithium (Al-Li) alloys. X-ray diffraction measurements have shown that lithium titanate undergoes a phase change from an orthorhombic structure to a hexagonal structure. This change is due to the incorporation of Li in the matrix of the material and the effect of temperature. Although both are metastable, the hexagonal phase that forms during the scavenging of Li from Al-Li alloys appears to be the more stable phase. Recovering Li from the ESC by electrodeposition does not cause the structure to revert to the orthorhombic phase. Both the orthorhombic and the hexagonal structures of Li2Ti3O7 have similar scavenging capacities for Li. This paper proposes a new mechanism for the phase transformation.

Jan 1, 1993

By Varadajan Seshadri

Keywords: torpedo car, kinetics, physical modeling A 1:6 torpedo car physical model was built to assess the optimum refining conditions for pig iron desulfurization in the torpedo car considering the industrial parameters used in the steel plant CSBM (Companhia Siderurgica Belgo-Mineira, João Monlevade, MG, Brazil). The refining practice in this plant is through injection of a CaO-CaF2-Mg powder in the pig iron melt. Similarity between the model and prototype were established through Froude and turbulent Reynolds criteria. Mixing times were evaluated by pulse tracer addition and the kinetics of metal/slag interactions were assessed from experiments investigating iodine transfer from kerosene to water. The influence of parameters such as level of metal, gas flow rate, lance penetration, lance orientation were also evaluated.

Jan 1, 2005

By P Ridgeway, D Xie, M A. Somerville, S Jahanshahi, H Rogers, J G. Mathieson, Y Pan, N Haque, P Zulli, T E. Norgate, L Lu, A Deev

In 2006 the Australian steel industry and CSIRO initiated an R&D program to reduce the industry’s net greenhouse emission by at least 50%. Given that most of the CO2 emissions in steel production occur during the reduction of iron ore to hot metal through use of coal and coke, a key focus of this program has been to substitute these with renewable carbon (charcoal) sourced from sustainable sources such as plantations of biomass species. Another key component of the program has been to recover the waste heat from molten slags and produce a by-product that could be substituted for Portland cement. This paper provides an overview of the low-emission Integrated Steelmaking Process, progress made over the past seven years and the program’s future direction which includes proposed demonstrations of the technologies developed including large scale piloting and full scale plant trials.

Jan 1, 2014

By Wenbo Luo, Kang Liu, Jilai Xue

"Coal fly-ash(CFA) from thermal power plants is rich in Al2O3, which has great potential as an alternative resource for alumina production. In this work, Alz03 contained in the coal fly-ash was extracted using an acid sintering-leaching process. This process was enhanced by aid of power ultrasound during the leaching. The recovery rate of Al2O3 was increased with ultrasound, compared with the similar process without ultrasound under the identical operation conditions. Leaching temperature can be lowered by about 10-l5°C and the processing time reduced by about 50%. The process kinetics were investigated in details for a better understanding of the fundamentals on the effects of power ultrasound. The obtained results demonstrate the potential application in reducing processing energy and increasing production rate.Introduction Coal fly ash is a typical solid waste generated from coal combustion in thermal power station. Vast amount of CF A accumulation lead to serious environmental problems such as air and water pollution, cropland occupation, radioactive contamination, etc. However, CFA is rich in Al2O3 and SiO2 content, so that it has a potential use as recourses for alumina and silica production [1]. Aluminum industry, especially in China, has made a rapid expansion in recent years accompanying with a large amount of bauxite consumption, resulting a urgent demand to develop secondary alumina resources like CF A to maintain a sustainable development of aluminum industry that faces grim challenge [2].Acid leaching is an efficient technology to use in alumina extraction from CF A. Since the particle of CF A is not naturally existed mineral but was formed in molten state at high temperature, the internal Al-O-Si bonds are so strong to separate alumina from the ash particle. Because of this reason, the direct acid leaching [3-6] operated at ambient temperature has low extraction efficiency, approximate 30% to 40%, which is attributed to self inhibition effect from CaS04 generated by reaction between CaO and H2S04 [7-8]. High pressure leaching can efficiently decompose mullite to release A12O 3 content in the fly ash particles, but this requires autoclave material having strong acid corrosion resistance, high temperature (100°C-300°C) and pressure (1.0MPa-2.SMPa) resistance while its operating security is low and its acid consumption is large [9]. Concentrated acid boil process is conducted at near acid boiling point (200 °C - 300 °C) in 4 mouth flask wrapped by electric heating jacket with high mass ratio of acid and ash to achieve high Al203 recovery rate from CFA. Its disadvantages are similar to the high pressure leaching technology except no-pressure, and also the operating solution at nearly boiling point acid may easily spill and splash with additional acid loss and potential safety hazard [10]."

Jan 1, 2014

By N. L. Piret

In copper smelting minimization of solid waste generation is receiving increased attention with more stringent environmental legislation and lower disposal space availability. Copper smelting slags generally being valorizable, solid waste generation is attributed to the presence in the feed of unvalorizable impurities which do not report to the slag and to the unavoidable formation of contaminated dilute acid solutions which need neutralization. As to unvalorizable impurities, solid waste minimization is achieved by rejecting them in the highest possible concentration. Dilute acid is mainly due to the formation of SO3 in the smelter gases and to the discard of decopperized bleed-off electrolyte. Its generation is substantially lowered by preventing SO3 formation, by converting the dilute acid to a valorizable product, e.g., by thermal decomposition for H2S04 recovery or by precipitation as chemical gypsum, and by suitable treatment of the bleed-off electrolyte for impurity removal. Industrial processes are evaluated and alternatives are discussed.

Jan 1, 1994

By Jilai Xue, Jun Zhu, Baisong Li

"TiB2-C/C Function Gradient Materials (FGM) is used in cathode materials to improve aluminum wettability and melt penetration in aluminum electrolysis. In this investigation, FGM was tested for use as part of the cathode materials, where a 10 mm thick TiB2-rich layer was on the top as an Al-wettable surface, the TiB2-C layers in the middle as a gradient layer and the carbon on the bottom as a base. Electrical resistances ofFGM were determined in the temperature range of25- 9600C in argon atmosphere. The results show that the present of TiB2-C gradient layer can reduce the open porosity and the electrical resistance of the cathodes materials at elevated temperatures. The cathode samples after aluminum electrolysis usually demonstrates an increase in electrical resistance, but the application of FGM layer can compensate such an increase for certain extend due to less variation in porosity and lower the level of melts penetration.IntroductionCarbon is still used for aluminum reduction cathodes dominantly, but it has a poor wetting properties by liquid aluminum and the anode-cathode distance has to be kept about 4-5cm with an additional 1.3-2.0 V voltage drop [l]. TiB2 has better wettability by liquid aluminum with higher electrical conductivity and stronger chemical resistance to the electrolyte attack. And the wettability ofTiB2-C composites cathode on liquid aluminum can be also improved, while liquid aluminum can completely wet the cathode surface ifTiB2 content exceeds 27% [2-4]. However, during the process of TiB2-C composites cathodes preparation and aluminum electrolysis, the deformation by temperature variation or sodium penetration are great disparity between TiB2 and carbon due to their physical properties difference. This will accelerate the cathodes cracking and deterioration."

Jan 1, 2013

By Wenbo Luo, Kang Liu, Fusheng Mao, Jilai Xue, Jun Zhu, Chunlei Yang

Extracting alumina from coal fly ash (CFA) is of great interest for both environmental protection and recycling valuable alumina content. In this study, ultrasonic aided leaching process as an effective method was investigated to enhance extracting Al2O3 from CFA via concentrated sulfuric acid sintering. The influence of ultrasonic power and processing time were tested under the conditions as the same as those without ultrasound. It is found that the alumina extraction rate can reach 90.5 % with ultrasound assistance, while the ultrasonic treatment can reduce almost 15 ~ 30 min in leaching time and 5 ~ 10 oC in leaching temperature than those without ultrasonic operation at the same Al2O3 extraction rate. In addition, the ultrasonic can reduce calcium content by 6 ~ 8 % dissolved into the leaching liquid. SEM analysis also shows that the residue particle size with ultrasound is smaller than that without ultrasonic treatment.

Jan 1, 2015

By Herbert H. Kellogg

A model of the ISF is described. which reproduces with accuracy the "normal" operation of three industrial furnaces. The model, written in Fortran, is based on detailed heat and material balances, and the concept that the ascending gases reach equilibrium with zinc oxide and with the water-gas shift reaction. "Solution loss" of carbon in the lower shaft, and partial reoxidation of zinc vapor in the upper shaft are also essential features. For prediction of furnace behavior under altered operating conditions (blast rate, temperature, moisture content, oxygen enrichment, or injection of oil or coal through the tuyeres) the model modifies the heat loss, temperature of slag and bullion, amount of reoxidation in the upper shaft and the condenser efficiency to reflect the altered operating parameters. Model predictions for such operating conditions are in reasonable agreement with plant experience.

Jan 1, 1990

By R. W. Smith

Living and killed organisms, particularly microorganisms, and extracellular products derived from the organisms are increasingly finding use in minerals engineering. Goals include both enhancement of mineral processing/11.ydrometallurgica,l operations and remediation of mineral industry wastes. Some of the applications, such as biologically assisted leaching of ?sulfide ores and bioxidation of refractory gold ores, are well established commercial ?processes used around the world. Others, such as the use. of organisms for the removal of heavy metal ions from dilute aqueous streams, are nearing commercial application. Many other uses of microorganisms and. their derivatives are potentially possible. These include use of microorganisms in flocculation or flotation of minerals., remediation of organics potentially discharged from mineral engineering operations, degradation of cyanide, the recovery of bitumen from heavy oil reservoirs and tar sands and the solubilisation of lignites and low rank coals. In order to fully exploit these many possible uses of organisms and their derivatives, extensive fundamental .and .applied research work exploring the fundamentals, potential and practicality of the various possible uses of microorganisms in mineral engineering should be vigorously pursued. ?

Jan 1, 1991

By Alessandro Navarra, Joël P. T. Kapusta

"The converting cost modeling software introduced by Ng et al. in 2005 [1] has been extended to consider the reprocessing of reverts and copper scrap. The original model evaluated the operational costs of a Peirce-Smith converter; algebraic relationships had been implemented with arrays (to represent matrices, vectors and scalar ratios). The new software brings flexibility to the underlying thermochemical balances, by using linked-lists instead of arrays. It is now possible to consider the blending of several feeds, including reverts and scrap.The software computes the length of the converting cycle from the Fe and S content of the charge together with the blowing rate; the times required for other operations (charging, skimming and idle time) are also accounted for. The costs of consumables such as flux, fuel, oxygen or compressed air are all evaluated. Downtime, labor, and materials for converter lining repairs are also considered. The software is easily extended to examine the costs of alternative operating strategies or injection technologies such as sonic single pipe injection and sonic shrouded injection. The potential cost benefits of alternative operating procedures and technologies are discussed through example calculations."

Jan 1, 2009

By A. A. Bustos

A model was developed to simulate the blow-by-blow operation of the converting process. From the weights, compositions and temperatures of all converter feeds the model calculates the composition and tonnage of both converter matte and slag as well as bath temperature at the end of each blow. The development of the model and its application to the converter aisle operation are described. There is good agreement between model predictions and observed results. At the present time the model is being used to investigate different converting schemes and their effect on pay metal recoveries, slag chemistry and temperature of the bath. Future work involves the use of the simulation model as a process control tool for the converting operation.

Jan 1, 1988

By René Winand

A new process was studied at large laboratory scale at Université Libre de Bruxelles, under contract with Metallurgie Hoboken-Overpelt. A two cathodes (1m long ; 0.2 m high) channel cell was used at 2000 A/m2, with an electrolyte flow rate up to 1.8 m/sec. The main results may be summarized as follows : cathodes are electro¬refined grade in analysis ; metallographic structure and surface roughness are kept under control up to 1.3 cm (one side deposits) ; silver in cathode is controlled by CI and Br ions in solution ; organics must be used at very low concentrations (in the range of 0.1 mg/1, with a consumption of about 0.01 mg/lh).

Jan 1, 1987