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By B. C. F1intoff, R. G. Bradburn, E. Groiss

"The concentrator at Brenda Mines Ltd. treats a copper - molybdenum porphyry ore with current head grades of 0.185% Cu and 0.036% Mo. The consistently low head grades provided the driving force to explore methods of improving plant productivity. Computer based process control was recognized as one means of addressing this objective. Over the period from 1974 to 1982 a control system evolved which now extends to every area of the mill. Control strategies are built on elements of classical, modern and rudimentary expert control. In addition, the control system has often served as a catalyst for other technological developments. The economic returns associated with the system are very significant and it has played an important role in the mine's survival in times of poor metal markets. This paper presents an overview of the computer control system at Brenda.PreambleOne can scarcely avoid picking up a trade magazine or newspaper today without seeing some reference to technology and its potential impact on North American business. _A recurring theme is the need to apply technology to raise our standard of plant automation in the manufacturing and process industries. The general thesis of these articles has been concisely captured in the mutually exclusive set:AUTOMATE or EMIGRATE or EVAPORATEProcess control is one form of automation that has been successfully exploited by various sectors of these industries. In minerals and metal processing the wide scale adoption of process control technology has, until recently, been largely limited to a few companies - most of whom have a history in the area dating back to the early 1970’s. However, there is definitely an increased and much broader interest in process control as a technology which can improve performance, productivity and profit.The economic hardships that were visited on the mining industry in the early 1980's are not easily forgotten. It is the authors' conviction that the mining industry must move to implement proven technology, in particular process control, in order to be well postured for the next (inevitable) down cycle.In pursuing the technical and trade literature, one can discover a number of example of the successful utilization of process control systems in mining and related applications. In the text which follows, the authors describe the process control efforts undertaken in the Brenda Mines Ltd. concentrator."

Jan 1, 1989

By M. S. Lee

A cold model study on the effects of various operating conditions on the dispersed-phase holdup in a liquid-liquid emulsion generated by bottom gas injection has been performed using water and kerosene. Dimensional analysis was used to correlate the holdup with the operating conditions and the sampling locations. The holdup increased with gas velocity, and decreased with axial and radial distances. The radial distribution of holdup follows a Gaussian function. The holdup increased with increasing ratio of the heavy phase to light phase volumes and decreased with the total height of the heavy phase. The combined effects of various operating conditions can be represented by the Froude number. The variation of the holdup within the plume was correlated by a single equation involving a set of dimensionless numbers.

Jan 1, 1995

By Yongyong Gong, Qijie Zhai, Zhichen Zhang, Qixin Li, Zhishuai Xu

"Microstructure of semisolid slurry of Al-4.5wt.%Cu alloy was investigated with pulse magnetooscillation (PMO) treatment, the results showed that the PMO treatment can refine the crystal structures of Al-4.5wt.%Cu alloy significantly. The discharging frequency of PMO had a great effect on the solidified structure transformation of semisolid slurry of Al-4.5wt. %Cu alloy, and the primary a-Al particles become much finer and rounder with an increase of discharging frequency. However, over a certain discharging frequency, the grains of primary a-Al become coarse.IntroductionOver the last decade, a lot of attentions have been paid on metal rheoforming process [1-4], since it has higher mechanical properties of formed components, strength to weight ratio and age hardenablity. Nevertheless, semi-solid forming is always performed at high solid fractions (40%-60%), so it has the limitation of viscosity, a tends to be difficult to pour semisolid slurry into the hole of the shot sleeve. Therefore, a series of novel semi-solid slurry preparation methods and rheoforming techniques have been invented, such as, semisolid vibration treatment [5], rheocasting [6], pulsed magnetic field process [7], annulus electromagnetic stirring [8], via ultrasonic vibration process [9], equal channel angular extrusion (ECAE) process [l0] and straininduced melt activation (SIMA) process [11].The electromagnetic field is characterized by its effective grain refinement, green, convenient manipulation and without contamination of melt. The mechanisms of dendrite was fragmentation by electromagnetic field have also been largely proposed [12-14]. The broken dendrite arms then undergo a coarsening process to provide the globular structures and obtain much finer and rounder a-Al particles. When compared with other external electromagnetic techniques, Pulse Magneto-Oscillation (PMO) has obtained more fuvors, owing to narrower pulse width and much lower energy consumption. Furthermore, the PMO treatment can reach finer grains with shorter time treatment [16, 17]. This work aims to study the effects of different discharging frequency ofPMO treatment on the microstructure transition of the semisolid slurry of Al-4.5 wt.%Cu alloy."

Jan 1, 2014

By K. C. Mills, P. N. Quested, A. P. Day, R. F. Brooks

"Methods have been developed to measure the physical properties of molten materials relevant to the fluid flow in high temperature processes. Data for the densities, viscosities and surface tensions of Al-, Ni- and Fe-based alloys are compared with (i) values for the pure metals and (ii) estimated values obtained from models making use of chemical composition of the alloy. Experimental values for metallurgical slags are also given and compared with estimated values.1 IntroductionPhysical property data has proved very useful in improving process control and product quality. For instance, in the continuous casting of steel the viscosity (TJ) of the mould flux is important since it determines (i) the optimum casting conditions, nVc = 2.5±1 dPas (m min-1) where V c is the casting speed and (ii) the level of slag entrapment (which leads to inclusions) in the metal. Thus data for properties like viscosity are exceedingly useful in understanding the process and the problems encountered and the causes of defects and problems.Another interesting development which has helped to increase our knowledge of processes and improve process control and product quality is the development of mathematical models of the fluid and heat flow in the process. These models have been developed to the stage where one of the prime requirements is for good physical property data for the industrial materials involved. Recently, Oxley [1] has shown that the use of reliable, experimental, property values for the commercial alloy in a commercial software package produced a significant improvement in the prediction of casting defects. Thus reliable property data are required for liquid metals but also for (i) liquid slags since many processes involve the use of a slag to refine and protect the metal or to lubricate the mould and (ii) refractories, sand and investment moulds."

Jan 1, 1999

By Lztok Peruš, Goran Kugler, Matevz Fazarinc, Milan Tercel

"Hot deformability of M42 tool steel additionally alloyed with cobalt and molybdenum was investigated. Hot-compression tests were carried out in the temperature range 850 °C -1200 °C, at strain rates range 0.001--6s-l up to strain of0.9. Field-emission scanning electron microscope and optical microscopy were used for characterization of microstructure of deformed samples, which revealed a very complex precipitation of carbides that strongly depends on the soaking temperature, the soaking time, the stress state, the deformation temperature as well as on the strain rate. Gathered data was used to calculate the processing parameters such as process maps, apparent activation energies and strain hardening exponents. For better understanding of thermodynamical properties of the studied steel a simultaneous thermal analysis was conducted. Furthermore the analysis of phase equilibrium was calculated using Thermo-Cale software. On the basis of these studies the optimal soaking temperature and process windows were determined.IntroductionHot workability ofledeburitic tool steels is important economic factor. This means that for each tool steel individuallysafe range of hot working parameters should be revealed. Publications in the literature with regard to the hot workability of tool steels are rare and therefore more information from this research area is desired.The relatively low hot workability of ledeburitic tool steels, i.e. steels in which the solidification is completed by a eutectic transformation of the residual interdendritic liquid to austenite and various alloy carbides (ledeburitic carbides), is usually characterized by the production of surface and internal cracks during the hot deformation."

Jan 1, 2013

By Denise C. R. Espinosa

The amount of secondary batteries are increasing about 15% by year. Among these batteries, it can be highlighted the NiCd ones, due to their high consumption. In Brazil, the consumption of NiCd batteries grown quickly in the last 5 years, due to the dissemination of cellular telephones and other electronic devices. The first step of a process to recycle spent NiCd batteries is the pretreatment through unit operations of mining treatment. The aim of this work is to define a physical pretreatment to conditioning the waste to a pyrornetallurgical recycling process of spent NiCd batteries used in cellular telephones. Batteries were disassembled by hand to release the different components. The studied batteries are basically composed (by weight) of: 78% nucleus, 18% plastic case and 2% circuits. The grinding of the batteries was performed by knife mill and also by hammer mill. After grinding the material was screened and submitted to a magnetic separator.

Jan 1, 2001

By Philip Nash, Jie Zhou, Joshua Blackketter

"Large ingots tend to have internal defects such as shrinkage cavities and porosities, which have to be closed during the cogging stage to ensure sound internal quality of forged parts. In this work, finite element methods were used to simulate open die forging passes, with varying parameters that affect the void closure behavior profoundly. Numerical models ware constructed in ABAQUS, DEFORM and FORGE using data taken from footage of the forging process and material mechanical data obtained from the Gleeble compression tests. Forging variables such as pass rotation, reduction per pass, and feed ratio were studied with intense attention paid on the special properties of H13 steel, so that this study can be applied to solve real world problem.IntroductionCenterline defect closure is a frequently studied but still challenging topic in open die forging industry. In practice, open die forging is employed as an effective hot forming process to make desired shape of metal products as well as to ensure center consolidation of internal defects which result from the casting process. Nowadays, remarkable large forgings have been more and more required to meet industries demand. However, the increase in ingot size has tended to result in considerable macrosegregations and shrinkage cavities or voids, which need to be worked thoroughly during the forging process; but the size of the products and limitations of manufacturing capacity, such as the press load, make it difficult to achieve adequate local deformation to close those defects. Therefore, choosing optimal forging parameters under given work condition to ensure good internal quality of forged products is critically important."

Jan 1, 2012

By WenCai Li, Yong Ren, Shuai Niu, Xin Hong

"Temperature measurement is very important in metal smelting process. Many devices are used to realize non-contact temperature measurements. Compared to conventional thermocouple, infrared temperature measurement has it's unique advantages. However, using an infrared temperature measurement at the top of the furnace can not obtain the desired optical signal because of disturbance from slag layer, high-temperature gases and other effects. A real time thermometry system with dual-wavelength radiation was presented to get optical signal emitted from molten metal through bottom-blowing nozzle. Taking into account the advantages and disadvantages of bottom-blowing devices, a MHP (Multiple Hole Plug) bottom-blowing device was used, through which the optical signal was transferred to the infrared thermometer by use of optical fiber. After conversion and analysis in real-time, the result was displayed and recorded in computer. After calibration, it could be a good predictor of temperature trend in a metallurgical process. IntroductionAt the refining stage of steelmaking, in order to achieve predetermined chemical composition and temperature, high-temperature molten steel is refined in a furnace such as converter. Because the refining process involved with chemical components and reaction velocities in the furnace rely on the temperature of steel, it is necessary to know the temperature accurately in real time during the process. And temperature measurement is also helpful for the end-point judgment. The temperature in the refining process changes quickly, for instance, in a converter, 300t molten steel is processed in only about half an hour.At present, traditional way of temperature measurement is using a thermocouple probe mounted on a lifter called a sub-lance. The thermocouple is immersed in molten steel and its temperature is measured during the short period until the thermocouple is fused. Accurate and reliable temperature can be obtained by this method, but in consideration of the discontinuous measurement and the costs, missing the end-point temperature may sometimes occur.According to the above background, a method in which a temperature-sensing element such as a thermocouple is immersed directly in molten steel is not suitable for the continuous temperature measurement because materials having such stability are not available. Therefore, radiation thermometry is promising. There have been some reports on radiation thermometry through an observation nozzle through the bottom or side of a refining furnace [1, 2]."

Jan 1, 2014

By Anil Saigal, Jr. Fuller, Said Jahanmir

"All-ceramic crowns, including glass-infiltrated spinel composites, are coming into widespread use because of their superior aesthetics and chemical inertness. This study investigates the residual stresses that are developed in these composites as a result of cool down from the glass-infiltration temperature to room temperature due to slight mismatch in the coefficients of thermal expansion and its effect on the mechanical behavior of these composites. Two-dimensional finite element simulations were performed using an object oriented finite element program OOF. The OOF program is a combination of two programs. The first program, PPM200F, is designed to read an image file such as a micrograph. The individual pixels that constitute the micrograph may be collected into groups and their material properties assigned. PPM200F is then used to create the finite element model/mesh that OOF then reads. The average residual stresses are found to be tensile in the spinel matrix and compressive in the infiltrated-glass. There is large variation in residual stresses and strains from location to location with presence of locations at which the glass is under tensile stress. The crack initiation and initial propagation in glass-spinel composites is at the glass-spinel interface in both the glass and the spinel. The presence of residual stresses can lead to lower crack initiation stresses and degrade the mechanical properties of the composites.IntroductionGlass-infiltrated spinel ceramics are in clinical use as core materials in all-ceramic crowns and as inlays and onlays (1-3). Advantages of ceramic composites include near net-shape forming with high strength in the infiltrated state. Besides, spinel is quite translucent and may potentially be used without a veneer. However, these ceramic composites are subject to damage accumulation from repeat oral contact loading and often fail after a few years of use (4). This paper examines the residual stresses that are developed in these composites, after cooldown from the glass infiltration temperature to room temperature, due to the slight mismatch in the coefficients of the thermal expansion of the two phases."

Jan 1, 2001

By J. Huot

It has been shown that magnesium-based metal hydrides such as Mg2Ni could be synthesized by high energy mechanical alloying. This process creates a nanocrystalline alloy that has enhanced hydrogen sorption properties due to the high density of defects and grain boundaries. Unfortunately, this process also requires a long synthesis time (up to 100 hours in some cases). In order lo reduce processing time and cost of synthesis, we have investigated the effect of milling at elevated temperature under an inert atmosphere. Milling at high temperature improves interdiffusion of the elements and reduces the number of structural defects such as vacancies, dislocations and internal strain. It was found that by milling elemental powders at 200°C. a complete synthesis of Mg2Ni could be achieved in 8 hours. This synthesis time is roughly an order of magnitude lower than that of the process conducted at room temperature. The hydrogen sorption kinetics and capacity of this material are comparable to Mg2Ni synthesized at room temperature.

Jan 1, 2002

By Helena Byrdziak

KGHM Polska Miedz SA, in existence since nineteen seventies, operates three underground mines and three smelters with total production of over 400 000 mtpy of electrolytic copper. Its impact on the environment, very serious in the past, has been gradually reduced. While in general emissions into the air and water have been brought under control, attention recently has shifted to the disposal of wastes and residues. The main streams of wastes are flotation tailings, slags and dust captured from the dedusting systems. Much effort has already been expended and is still being spent to utilize this waste for by-products production or to dispose of it within the process by recycling. The most effective measures taken up thus far, as well as present activities directed at tailings disposal, are presented.

Jan 1, 1997

By Hongmin Zhu, Kai Huang, Shuqiang Jiao

"Garlic peel was used as the raw material to synthesize the biosorbent for the selective recovery of precious metals from the acid chloride solution. Garlic peel is rich in carboxyl-, amino- and thiol-groups, has the potential of exhibiting high affinity to Au(III) when appropriate chemical modification process was employed. Here in the present study, the biosorbent was prepared by cross-linking garlic peel particles with concentrated sulfuric acid. Adsorption tests for mixing different metal ions such as Au(III), Fe(III), Cu(II), Ni(II) and Zn(II) from various concentrations of hydrochloric acid media indicated that Au(III) was selectively adsorbed on the cross-linked garlic peel gel over the other coexisting base metal ions investigated. The crosslinking mechanism and selective adsorption of Au(III) were also investigated briefly.IntroductionPrecious metals are quite popularly applied in the modern industries such as jewelry, electronics and electrical devices, catalysts in chemical industry, etc. While their high values, limited deposit and quite large demand in industry makes its recovery from the industrial wastes, typically e-wastes, quite necessary. Actually, many techniques have been developed to recycle and recover the precious metals from various industrial wastes effectively in last decades, but the cleaning and ecofriendly processes are still seriously scarce [1]. Taking into account of the typical recovery processes using cyanide lixiviant in the alkaline media, or aqua regia, followed by the further recovery process using activated carbon adsorption or cementation with zinc, iron or aluminum plate or powder, though they both are quite effective recovery processes, if considering the special requirements on safety and ecofriendliness for the modern hydrometallurgical processes, various improved or novel extraction processes are greatly demanded [2]. Recently, the biosorption technology applied to the recover precious metals in the hydrometallurgical process has become a concern [3,4]. Inoue’s research group made great progress in the recovery of precious metals such as gold, palladium and platinum from the e-wastes such as spent mobile phone by using biosorption from the hydrochloric acid media [5,6]. This new hydrometallurgical process exhibits the prominent advantages of being cost-effective for its short process, easy operation and near-zero emission. In the above recycling process for e-wastes treatment, the preparation of biosorbents is the key and backbone of the whole recovery process. For this purpose, they developed a series of suitable sorbents for precious metals recovery by using the tanning-based or cellulose-based biomass such as persimmon peel, grape peel, orange juicing residue, waste cotton, waste paper through the crosslinking process with concentrated sulfuric acid and relative chemical modification processes [7-10]. In the present study, we also applied this technique to prepare the biosorbent of precious metal uptaking by using garlic peels as the raw materials, and investigated the adsorption properties of such-obtained gel in the hydrochloric acid media."

Jan 1, 2012

By F. K. Letowski

Leaching in froth is a particular case of a three phase (liquid-solid-gaseous) process which combines flotation with leaching by using a reactive gaseous reagent as a flotation carrier and a leaching solution as the reactive liquid medium to fonn the foam (froth) in' which the solid particles are suspended. Some physico-chemical and engineering aspects of leaching in froth are discussed and illustrated by its application for cleaning the mineral graphite. Leaching of the graphite concentrate containing 4L4% of the elemental carbon and 3.16% of the sulphidic 'sulphur was canied out in the froth fonned by: (a) a concentrated chloride solution, with a small addition of nitric acid, in the foam state; (b) a mixture of gaseous O2, NO., and H20 encapsulated in the foam; and (c) notable particles of graphite suspended in the foam. The laboratory experiments werecanied out in a "flotation column"-type reactor ala temperature from 80 to !08°C and under total pressure of 100 to 200kPa. In the 3-stage leaching-flotation process, the non-flotable fraction of particles was separated three times from the notable fraction. The concentration of carbon and elemental sulphur in the final flotable fraction was 96% C and 0.38% S respectively. The expected advantages and possible application in hydrometallurgy are suggested.

Jan 1, 1995

By Jeffrey L. Zelms

Environmental issues and how they are addressed -- or not addressed -- by the lead industry in the 1990s will determine the eventual fate of lead mining in both the U.S. and worldwide. Clearly, governmental regulation throughout the West will become harsher. Equally clearly, the industry has? failed to educate the public regarding lead. Instead of public support for a critical mineral, we face widespread public ignorance and paranoia. If we can demonstrate the public interest benefits of the industry, the 1990s will be a decade of continuing growth -- not dynamic growth, certainly, but growth at least comparable to the world economy. If, however, we fail to demonstrate the industry's public interest benefits, the 1990s could mark the beginning of the end of our business.

Jan 1, 1990

By C. Lupi

In 1996 the Italian Agency for Environmental Protection (ANPA) has initiated a study of the environmental impact of the industrial sector of steel produced by Electric Arc Furnace (EAF). Within the framework of this study a hydrometallurgical process to treat EAF dusts was considered and developed. The paper describes the zinc and lead recovery from fumes coming from carbon steel production. The zinc extraction consists in acidic leaching followed by SX-EW steps. The leaching sludge containing lead sulfates was treated to obtain pure lead salt and inert solid residue. The whole process, that minimizes effluents by recycling the main liquid streams, has been developed to obtain marketable products. The solid waste, containing spinels, was subjected to elution tests in order to verify its compatibility with environmental regulation. The process, that has been set-up and tested in the laboratories of the University of Rome, will be transferred and studied on a pilot plant in order to assess its industrial and economical feasibility.

Jan 1, 1999

By R. A. Masumura, C. S. Pande, D. Agassi

"Grain size has a different effects on the critical current density (Jc) of high and low transition temperature (Tc) superconductors. In high Tc superconductors, the critical current density Jc across grain boundaries depends sensitively on the misorientation 8. It was pointed out by Pande that this dependence is directly related to dislocation structure of the grain boundaries i.e., it is due to dislocation cores and stresses. These ideas are developed further in this paper leading to a relation between Jc and 8. The analytical result is compared with the experimental results on bicrystals and used to explain the difference in behavior between high and low Tc superconductors.IntroductionThe grain size distribution and its evolution with time and temperature is important in determining the properties of high and low transition temperature (T c) superconductors. The distribution is a convenient function to characterize the processing of a high Tc material during sintering. For example, it is known that the maximum density of ceramic materials is obtained when the grain growth is reduced but grain boundaries are still mobile. For practical superconductors, the processing parameters are selected to achieve optimum properties: highest possible T c and maximum critical current (Jc). In terms of an average grain size, the requirements for optimum T c and Jc are sometime in conflict. In A15 type superconductors and even in NbTi, larger Jc have been measured in smaller rather than larger grain sized material. Conversely, in a high Tc materials like YBa2Cu307, higher Jc have been found in larger grain sized or single crystal specimens.Extended defects such as grain boundaries in low T c superconductors can be effective pinning agents for magnetic flux lines, thereby increasing the transport critical current density of these materials [1]. On the other hand, the transport critical currents in polycrystals of high Tc superconductors such as YBa2Cu307 is found to be relatively small (much smaller than those in single crystals of the same material) [2]. It is now known that grain boundaries in high Tc polycrystals can in many cases form ""weak links"" reducing the critical current density across them. This phenomenon can be studied more precisely by experiments on bicrystals, where there is only one grain boundary. It is found that the critical current density is quite sensitive to the misorientation angle of the bicrystal [3,4]. Although the original experiments were conducted on YBa2Cu307, other Tc superconductors have been shown to give the same result [5]."

Jan 1, 1994

By John Fallavollita

Conventional gas atomization produces powders that vary widely in size distributions and microstructures, thus making it very costly to produce powders tailor made in a narrow size distribution and microstructure. Furthermore, it is difficult to determine the relationships between atomizer operating conditions and resulting powder characteristics. The Impulse Atomization Process (IAP) was developed at the Advanced Materials and Processing Laboratory to produce powders with narrow size distributions. Powders produced by the IAP were reproducible and their sizes could be easily controlled by adjusting experimental conditions. Characteristics of Zn, Sn-Pb, AI-Cu, and Cu powders will be described to illustrate the flexibility of the process to tailor-make powders.

Jan 1, 1994

By A. von Röpenack

A forecast of the consequences of our techniques and goods produced, at least a technical assessment will be demanded from us as an industry. The hydrometallurgical winning of zinc is therefore at a crossroads. New processes promise not only better economics, better maintenance of resources and simpler operation, but also more harmony with nature. Pressure leaching promises to eliminate roasting and thus one complete process step. The hematite process solves a difficult and always costly iron problem. HOA opens a possible road to a totally new ,generation of electrolysis. Zinc has a long tradition behind it. Its? importance is as great as ever-. There is still room for new production developments. In my estimation there are good chances for successful new techniques? which will benefit our whole industry. Zinc is a modern and forward-looking metal.

Jan 1, 1990

By Dariusz Kopyci ski, Józef Dorula

The study proves that by introducing the iron powder and disintegrated steel scrap to low-sulphur cast iron still before the inoculation carried out with a conventional graphitising inoculant, the mechanical properties similar to those obtained during the inoculation treatment carried out on cast iron with the recommended high sulphur content are achieved. The said operation increases the number of crystallisation nuclei for dendrites of the primary austenite. In this case, the iron particles act as substrates for the nucleation of primary austenite, due to a similar crystallographic behaviour of the regular face centred cubic lattice The more numerous are the dendrites of primary austenite, the less free space is available in the interdendritic spaces for the formation of graphite eutectic grains, which makes the structure more refined (more eutectic grains) and the mechanical properties higher.

Jan 1, 2016

By Cui Wang, Bing Dai, Haibin Zuo, Jianliang Zhang

The damage mechanism of ductile cast iron cooling stave applied to No.4 blast furnace of Guofeng steel was analyzed through damage investigation in details, the damage causes: hightemperature gas flow erosion, wear of burden, high-temperature ablation, carburizing damage, improper operation on blast furnace, etc. were given out both in macroscopic and microscopic views. It can be obtained from metallographic diagrams that the diameter of graphite nodules increases, the number per unit area reduces, and roundness declines, successively, from cold to hot surface, which are not conducive to stave longevity. In summary, the material for staves manufacture should be better in comprehensive mechanical properties to prolong the service life, thus making blast furnace long campaign.

Jan 1, 2015