Search Documents

THE twenty-first birthday of the Rocky Mountain Club will be celebrated on April 11 by the Last Round-up; for, as announced at the annual meet-ing of the American Institute of Mining Engineers in February, the Club and the Institute have voted to con-solidate and formal approval by the court alone re-mains to be secured. The Rocky Mountain Club was organized some years since "to create and maintain good fellowship between the Rocky Mountain members and to further the in-terests of the Rocky Mountain States." From the first, mining men dominated it, as was natural in view of the prominence of mining in the Rocky Mountain region. A series of brilliant annual dinners were held and a site purchased for a clubhouse. A fund was raised to provide a home for the Club. Just as success was as-sured the war came and the members of the Club con-sidered it would be unpatriotic to spend money for such purpose at that time. In a spirit of patriotism the Club funds were devoted to war purposes, especially the Commission for Relief in Belgium and the caring for soldiers going to and returning from the front. So much of the money was used that at the end of the war the project for a clubhouse was out of the question with-out raising a new fund, and since 1923, the Club has been inactive. There is now in its treasury a substan-tial sum. The assets are for the most part the result of contributions made by W. B. Thompson, John Hays Hammond, and Edward H. Clark, all members of the Institute and all of whom wished to see these funds applied in a manner to leave some lasting memorial of the spirit which animated the founders and at the same time perform some useful function in the development of the region in which the Club's interest centered. It was thought that this could best be done through affilia-tion of the Club with the Institute and both organiza-tions have voted for the merger. The Club members not already in the Institute are to have the privilege of a special Rocky Mountain life membership, and the property of the Club is to be used to endow a Rocky Mountain Club fund to be used for purposes in accord with those of both the Institute and the Club and with especial reference to benefiting the Rocky Mountain region.

Jan 4, 1928

By N. I. Jayaraman

Dust scrubbers on continuous miners are steadily gaining in popularity. Recent Bureau of Mines research on scrubbers is reviewed, with emphasis on the following areas: * Development of a new type of water-powered scrubber which can be retrofitted to existing miners. * Comparison of scrubber effectiveness with blowing and exhaust line ventilation. * Improving the quartz dust collection of flooded-bed' panels.

Jan 1, 1989

The common approach of designing blasts on a trial and error basis is quickly coming to an end. When utilizing the full scale blast environment, trial and error can quickly become cost prohibitive and leaves much to be desired in terms of true blast diagnostics. In these situations testing is usually only continued until a perceived improvement is achieved and when the gross undesirables in blast results are removed. This does does not preclude, however, that further improvements of up to 100% or more can not be obtained.

Jan 1, 1991

By Hugh P. Tiemann

The desirability of employing the centigrade scale for the measurement of temperatures is becoming more and more recognized in this country, particularly in view of the fact that this scale is used almost exclusively in technical papers and publications—exclusively in those published in French or German. There are, however, a large number of factories and laboratories which still employ the Fahrenheit scale. It therefore frequently becomes necessary to convert one into the other and the accompanying chart (Fig. I) has been found very convenient for this purpose. The formulas for conversion follow: (1) °F. = 9o /5+ 32 (2) oC = 5 (oF - 32 ) (1) 100° C X 9 900/5 =180 .'. 180 + 32 = 212° F. 5 (2) 5 (212° F - 32) = 5 X 180 =100o C 9 9

Jan 1, 1916

By K. Purazrang, P. Sh. Naseri, P. Abachi

In present work, the comparative measurement of aluminum alloys' resistance to the unstable fracture was provided. Besides, the rupture mechanisms of high strength 7075 and 7050 aluminum alloys were investigated. The specimens were used as solution treated, quenched and aged condition. The elastic-plastic behavior of specimens was determined by carrying out tensile test on cylindrical specimens. The small sized specimen with 6.35 mm thickness and V-notched radius less than 60 µm was used for evaluation of damage properties, in accordance with ASTM B871-96 standard test method. All tear specimens were machined in L-T orientation. The mechanical tests were conducted at RT on an universal Instron machine under cross head speed of 0.1 mm/min. The results of mechanical tests made the evaluation of tear strength to 0.2 % tensile yield strength ratio, as a measure of notch toughness, available. The comparison of specimens' resistance to crack propagation and unstable fracture due to the presence of crack-like strain concentrator was provided using tear test data. The microstructure of specimens was studied under optical microscopy. The rupture micro-mechanisms were analyzed by examination of specimens fracture surfaces using SEM. The microstructure examination indicated almost equiaxed grains on the transverse directions and elongated grains on rolling direction. Moreover, intermetallic particles were evident at microstructure. Considering the SEM fractographs, it seems that the intermetallic particles act as void nucleation and damage initiation sites. However, the damage mechanism of tensile specimens and severely notched specimens, especially near the notched root differs due to stress and strain states.

Jan 1, 2006

According to the classification of water conservation mining in shallow coal seams in China, when the ratio of the impermeable layer thickness to the mining height is less than 18, the mining belongs to the category of special water conservation, and the strip backfilling mining method is employed. This study is based on the geological conditions in northern Shaanxi. By analyzing the stability of the impermeable layer, the stability criterion of the impermeable layer was developed. The study also investigated the compositions and properties of the backfilling materials. The results show that reasonable subsidence of the impermeable layer is allowed during mining under the basic precondition (upward cracks and downward cracks are not connected).

Jan 7, 2020

By Alexander Garcia

Roof and rib falls are the basic ground control hazards associated with underground roadways during development, stand up and, if applicable, retreat. Falls of ground can happen following the deterioration of supports or rock conditions over time, and particularly as a consequence of continuing rock deformation and/ or failure to install adequate support. Once developed, the risk of a failure is increased due to the effects of time as well as to front abutment stresses through retreat mining. The measurement of strata displacement using monitoring equipment is a form of ground control risk assessment. These monitoring systems are active, or ?live?, in a sense that risk is assessed real-time. However, there are circumstances in which falls of ground can occur without the prior recording of excessive movement. In addition, monitoring equipment is typically placed at set intervals, and strata conditions could vary between these points. Consequently, a visual assessment of other factors contributing to the risk of a fall should be made in order to complete a ground control risk assessment. Such surveys are usually one-off, thus capturing roadway conditions at one particular point in time. Ongoing deterioration is not documented through such one-time surveys, and there is a requirement for real-time or live assessment where a system is in place so that observation data can be updated on an ongoing basis, and a useful summary of prevailing roadway states produced on demand. To address the shortfalls of one-time assessments, a ?live? computerbased quantitative ground control risk assessment process has been developed. It combines visual observations processed in a quantitative manner with existing monitoring data into an interpretable output which indicates zones of roadway where there is an increased risk of a fall of ground from the roof or sides, so that remedial action can be carried out to mitigate that risk. Through improved procedures, it is now possible to generate a ground control risk assessment for each roadway, and one which can be updated frequently. This paper aims to outline and describe the assessment process.

Jan 1, 2012

Dunn has written an excellent paper providing a wealth of advice on what is often the most costly consumable in the mineral processing plant. As he pointed out, grinding media selection and quality control can play a major role in successful plant operation. Owing to the economic importance of this topic, there are some important factors related to media sizing that I believe merit further comment. Dunn made reference to a slightly simplified version of the Azzaroni (1981) equation and pointed out its successful use for the Henderson SAG and Climax ball mills. Although both formulas are empirically based on successful plant experience, a notable discrepancy between them is that Bond has factored the work index by the ore specific gravity. This is invariably so, as the Bond work index is derived from the mass grindability (in grams per revolution) measured in a test mill with a fixed volume of solids load (Bond, 1961). A material having the same structural integrity but double the density of another will have double the grindability and just over half the work index. Thus, for the general case, specific gravity should be incorporated into any media sizing formulation that uses work index as the criterion for resistance to breakage.

Jan 1, 1990

By E. J. Bruderlin

A metallurgical process to be economically successful must be carried on under proper conditions of control and equipment. The question of equipment is always of primary importance. In the distillation process for the recovery of zinc by retorting, the retort is the all-important piece of equipment. Each retort in a working blóck must function as a separate unit. Over-all block efficiency is the result of the ability of the individual retort to withstand the severe conditions of operation for a maximum period of time. Therefore retort manufacture has been an ever present problem with the operator of a zinc-retorting plant. During recent years the zinc-plant operator has been faced with rapid changes in the character of the ores and concentrates. Operating costs have increased as a result of the introduction of the flotation process and the amount of flotation concentrates to be handled. To counteract increasing costs, the operator has found it necessary continually to attempt heavier loading of retorts, until a 45 to 50-lb. charge per cubic foot of retort space has become common practice. Heavy loading has brought about severe firing conditions, which, in turn, have emphasized the necessity for further improving the quality of the retort. Increasing percentages of detrimental impurities in the retort charges have also added to the operator's difficulties. Amarillo Silicon Carbide Retorts At the Amarillo plant of the American Smelting and Refining Co. a retort made of a suitable plastic clay grogged with silicon carbide has been found to best meet the present-day requirements. Retorts of this kind have been in use at Amarillo for 8 years and have shown an average furnace life of approximately 175 calendar days. The Amarillo retort is cylindrical in shape and after burning is approximately 83/4 in, inside diameter by 60 in. over-all length. The wall thickness is 136 in., except for the butt of the retort, which is approximately 2½ in. thick. The retort mud has a shrinkage of 3 per cent, or approximately % in. per foot. The silicon carbide retort after being properly dried weighs about 211 lb. When the retort is fired and ready to go into use the weight decreases to approximately 203 lb.

Jan 1, 1937

By J. G. Bensley, K. S. Detheridge

"Many plants use computers for process control and most have computerized Management Information Systems but few have been able to have these systems interact with one another. Developing this system interaction is not a one-step process but requires careful planning and implementation. This paper describes two projects that were implemented to provide the bridge between the process control and management information systems of Cominco Limited. Both projects include the replacement of essentially process control systems installed in the late 1960s. These original systems provided an enhanced level of control in the form of Direct Digital Control (via computer/manual analogue control stations) and a management reporting capability of process data. The experience gained from the use of these systems over a period of fifteen years formed a basis for the evaluation and planning for the new systems. The new systems were commissioned in 1985 and 1986 and operating and further developments leading to a totally integrated process information and control system are underway. INTRODUCTIONThe concept of hierarchical control involves a control structure consisting of a number of defined levels. Each level performs a defined function with information consolidated and combined as it moves up through the hierarchical structure. The commonly accepted structure of a hierarchical control system echoes the structure of the plant which is being controlled. Referring to Figure 1:Level 0 - Sensors and ActuatorsSensors and actuators, such as thermocouples and flow control valves, interface directly to the process and are generally connected directly to the controllers or multiplexers at Level I.Level 1 - Regulatory ControlThis level provides basic PID control (proportional/integral/ derivative) typically using microprocessor based controllers and programmable controllers for digital control of motors and machines. Systems at this levelare usually segregated by plant unit, e.g, crushing, flotation, drying. Control is concentrated on achieving optimum conditions for a particular feed rate."

Jan 1, 1989

By S M. C Verryn

The amount of raw material used in the production of cement can be reduced by partially supplementing it by pozzolanic waste material without changing its properties negatively. This paper discusses results of an investigation using slag from the Pt industry, from the production of steel using Midrex processes as well as fly ashes from different coal power plants in South Africa. These are blended in a 20 per cent slag or fly ash to 80 per cent cement ratio. The properties of the mixtures depend on the phase composition, chemistry, grain size and the sources of the materials. The results are promising, but show variable behaviour depending on slag and cement composition. Compressive strength tests as well have heat flow curves showing the hydration behaviour, indicating that 20 per cent addition of slag or fly ash to ordinary Portland cement is viable. There is a large potential to use slag in cement mixtures and this study can be used to develop cements that will positively influence CO2 emissions and help to reduce large slag and fly ash stockpiles.

Jan 1, 2008

By S. Mamonov, V. ?shikhin

"The purpose of work was the significant increase of copper recovery from slag at a concentrating plant. Analysis of study of slag phase composition showed the perspective of a slow slag cooling method due to its recrystallization and transition of primary copper minerals to secondary.Copper content in base slag varied between 0.71 and 0.96%. The study of a degree of copper minerals release of the slowly cooled slag in comparison with a yielding slag showed that in a flotation size grade –0.071 mm of yielding slag the weight ratio of released copper minerals grains is 58.95% against 86.73% in samples of slowly cooled slag. The process flotation sheet consists of three main, one control and two cleaner flotation operations with aftergrinding of middling products. A reagent mode was differed from a factory one by decreasing the slurry pH from 11–12 to 8–9. This paper shows research results of the slurry alkalinity impact on technological indexes of beneficiation (flotation).Industrial testing of a resulted batch of slowly cooled slag at “SUMZ” concentrating plant showed the efficiency of such processing: copper recovery to a copper concentrate increased by 15–19%.INTRODUCTIONIntensive development of mining and metallurgy industries within a 250-year period in the Ural region led to forming of approximately 315 man-made mineral formations at the territory of the Sverdlovsk region. The region contain over 32.5 billion tons of barren rocks and out of balance ores, over 1.5 billion tons of tailings, over 115 million tons of slimes, and over 100 million tons of metallurgical slag (Demin et al., 2000). Latters, at average, contain 407 thousand tons of copper, 2519 thousand tons of zinc, 7 tons of gold, and 150 tons of silver (Rudoy et al., 2011). Wastes generated in mining processing and metallurgical sector of economy contain not only thousands tons of copper and zinc, but cause significant damage to the environment where they are located. The reduction of negative impact of anthropogenic wastes on the environment as well as the storage volume reduction of valuable metals from dump slags is possible by improving the efficiency of the melting and further flotation of slags formed during this process."

Jan 1, 2016

By E. Lee Cameron

Summary Records of the past show that the first mineral production in what is now the Province of Manitoba consisted of salt, obtained about the year 1800 by the evaporation of brine. Also at an early time in our history, the Ordovician limestone at St. Andrews Locks, East Selkirk, and other localities was quarried for use as building scone in the construction of forts and fur trading posts. Both salt and building stone are still produced in Manitoba, although not from the original sources. In addition, there is now a substantial production of a variety of other industrial minerals and their products such as lime, crushed stone, gypsum, peat moss, and bentonite. The annual dollar value of production of the industrial mineral industry in Manitoba is today greater than at any time in our past and is derived from a greater variety of products. At the present time, exclusive of the various gravel pits operated by the Provincial Department of Public Works, twenty companies operating thirty-four separate pits, quarries, or mines are producing industrial mineral raw materials in Manitoba. This paper attempts to outline the development of the industry from its start about 1800 to the present, giving general information on the various materials produced. Some suggestions regarding the possibilities of establishing new industries based on other raw materials are given at the end of the paper.

Jan 1, 1949

By Mark L. Bricker

The Jim Bridger Coal Mine, operated by Bridger Coal Co., is located in Sweetwater County, WY about 56 km (35 miles) northeast of Rock Springs. Bridger Coal is a joint ven¬ture between Nerco Coal Corp, the operator, and Idaho Energy Resources Co. The permit boundary encompasses more than 81 km'- (20,000 acres) on the western side of the Continental Divide. Since the mine began opera¬tions in 1974, it has produced about 82 Mt (90 million st) of coal while moving about 344 hm3 (450 million cu yd) of virgin earth. Annual production averages 4.5 Mt to 6.4 Mt (5 million to 7 million st) of run-of-mine coal. Coal is consumed on-site by the Jim Bridger Power Plant, a 2000-MW generating station. Electricity is transmitted to the Pacific Northwest power grid that includes Oregon, Idaho and northern California. Geology The mine is located on the northeast flank of the Rock Springs uplift. This is a broad, asymmetrical anticlinal feature about 97 km (60 miles) long and 56 km (35 miles) wide with a north-trending axis. This uplift separates the Green River Basin to the west and the Great Divide and Washakie Basins to the east. Precambrian rocks on the apex of the uplift are estimated to be 5200 m (17,000 ft) above the Precambrian rocks in the Green River and Washakie Basins. Normal faults with generally less than 30-m (100-ft) vertical displacement cut through the uplift. The dip of strata on the flanks is generally between 3° and 15°.

Jan 1, 1991

By H. Son

The three-dimensional (3D) reconstruction of as-built industrial plant models plays an important role in revamping planning, maintenance planning, and preparation for dismantling during the lifecycle of industrial plants. Recently, the 3D reconstruction of existing industrial plants was conducted using laserscan data to make surveying processes more efficient. However, the current 3D reconstruction process from laser-scan data is still limited due to the need for significant human assistance. Although a great deal of effort has been made to efficiently reconstruct 3D as-built industrial plant models, the presence of objects?such as equipment, pipelines, and valves of different sizes and shapes?in existing industrial plants significantly increases the complexity of laser-scan data and makes automating the reconstruction process more challenging in practice. The purpose of this study is to propose a knowledge-based approach for the 3D reconstruction of as-built industrial plant models from unstructured laser-scan data. First, pipelines were extracted from laser-scan data based on surface curvature information and knowledge about pipelines' sizes from existing piping and instrumentation diagrams (P&ID). Once entire pipelines were extracted, they were modeled based on skeleton features. Then, the remaining objects were clustered and grouped separately via the region grouping process. Afterward, clustered objects were retrieved and modeled based on global feature-based matching from the 3D database. Finally, the resulting model was checked to ensure that it was well-reconstructed according to the information regarding the relationships among objects abstracted from the existing P&ID. The preliminary results on actual industrial plants show that integrating knowledge into the reconstruction steps played an important role in the proposed approach and that this approach obtained accurate as-built industrial plant models from unstructured laser-scan data. The proposed approach could be successfully utilized to assist in many applications during the lifecycle of industrial plants.

Aug 1, 2013

By J. Ouellet

The authors participated in a study for a new mine shaft in Saskatchewan?s Athabasca Basin where ground freezing is desired to reduce water inflows. Constraints were imposed on the design in terms of permissible water leakage (less than 10 m3 / hour) inside the shaft. Since the shaft goes through highly permeable formations, water control measures had to be incorporated into the design. Ground freezing was selected as the most reliable and proven method for the sinking and a hydrostatic liner design was implemented. While exploring various technological options available for providing a fully hydrostatic liner, the authors came up with a new design concept that offers a more cost effective solution while meeting all the design constraints. The new liner concept is a composite design using concrete and a sprayed-on membrane system. A proof of concept program comprising laboratory testing and field testing was successfully implemented. This paper presents the innovative liner design, as well as the adapted sinking methodology, developed for this type of project. The new concept offers a new cost effective high performance hydrostatic mine shaft liner comparing favorably with traditional methods. RESUME: Les auteurs ont réalisé une étude pour un nouveau puits de mine dans le Bassin de l?Athabasca en Saskatchewan. Des limites sévères sont imposées sur le design en terme de volume d?infiltration d?eau acceptable (moins de 10 m3 / heure). Comme ce puits de mine traverse des formations très perméables la congélation des terrains a été sélectionnée, une méthode éprouvée et fiable. Un design hydrostatique a été choisi pour le revêtement du puits. Dans le processus de design, les différentes technologies disponibles ont été étudiées. Les auteurs ont développé un nouveau concept de revêtement composite offrant un rapport performance/prix plus avantageux que les technologies conventionnelles. Le nouveau design proposé est composé de béton et d?une membrane projetée. Un programme expérimental a été réalisé pour démontrer la faisabilité du concept. Cet article présente le nouveau concept ainsi que la méthodologie de fonçage de puits adaptée. Ce concept innovateur offre un revêtement hydrostatique performant à un cout avantageux par rapport aux techniques de construction utilisées jusqu'à maintenant.

Jun 1, 2012

By W. R. Hibbard

The increased strength of a polycrystal-line metallic aggregate compared with that of its individual crystals generally has been associated with complex stress distributions at the grain boundaries resulting from atomic irregularity between grains. This disregistry, together with the necessity for adjacent crystals to deform compatibly regardless of the single crystal crystallo-graphic strain mechanism, complicates this mechanism so as to increase the metal's resistance to deformation. Although Taylor1 has shown from purely mechanical considerations the requirement for at least five active slip systems to absorb the complexities during the homogeneous deformation of polycrystalline face-centered cubic metals, experimental studies by Barrett and Levenson2 indicate that this is feasible only in a qualitative sense because of deviations from homogeneous deformation. Seitz and Read in their review3 state: " Unfortunately . . . present knowledge of the grain boundary influence is not sufficient to complement the work in single crystals and provide us with a good foundation for treating polycrystals." The purpose of this investigation was to attempt to clarify the gap between single crystals and crystalline aggregates by an analysis of the effects of dcformational stresses. Some of the results were described by C. H. Mathewson in his 1943 Campbell Memorial Lecture.zl Previous Investigations Since the performance of single crystals deformed under pure stresses has been relatively thoroughly investigated, the most significant researches are concerned primarily with deviations from single crystal behavior of large grained specimens. Qualitative grain boundary effects involving the observed amount of slip werc reported by Carpenter and Elam5 in 1921. Individual crystals in a two or three grained aluminum specimen deformed by tension acted in the normal manner described by Taylor and Elarn4 except for marked modifications at the grain boundaries. There the power to withstand deformation was considerably increased, leaving a ridge on the specimen where decreased slip occurred, often noticeable yi in. from the boundary. Adcock,6 Yamaguchi,' Seumel, Hirstg and others have also reported this phenomenon as a qualitative trend. Yet attempts by O'Neill'o and Ljunggrenll to measure a difference in hardness at grain boundaries in undeformed specimens were unsuccessful. Miller12 measured quantitatively the reduction in slip near the boundary between the single crystal and polycrystalline areas of zinc specimens. These effects consisted of two parts: I. Next to the polycrystalline interface thc distribution of stresses was so altered

Jan 1, 1949

By James Anstey

BHP Billiton?s Cannington facility is a mining and minerals processing plant near Mt. Isa in Central Queensland, Australia, producing silver, lead and zinc. Mine ore is processed in a concentrator, which consists of grinding, flotation, thickening and filtration. Grinding is carried out in a fully autogenous (AG) mill. The mill operates in closed circuit with a pebble crusher. Throughput is approximately 380 tph. Cyclone overflow from the grinding circuit is fed into a flotation circuit for the recovery of lead, zinc and silver. Two concentrates are produced (lead and zinc), which are then thickened and filtered. The filtered concentrate is transported by road to a rail receiving station. From here the concentrate is railed to port in Townsville for shipment to the smelter. Matrikon and Engineers at BHP Billiton?s Cannington Mine have used ProcessACT to develop a flexible, nonlinear dynamic simulator for the grinding circuit to further enhance process understanding, as well to investigate various optimization strategies. An online charge volume estimator was also developed for the AG mill to aid in the understanding of overload conditions, which for the previous two months had been the primary contributor to downtime. The models were developed using a combination of first-principles modeling along with input-output dynamic responses. Examples of models used include: Morrell ?C? model for power and charge shoulder/toe angle prediction; Whiten?s mixing model for breakage and hold-up; Nageswararao cyclone model for predicting cut size; slurry recovery and water recovery. The composite model simulates system dynamics starting from the stockpile reclaim system and finishing at the feed for the flotation process. The objective was to provide a tool that assisted Cannington in understanding their Grinding Circuit and allowed them to develop and evaluate circuit optimization strategies. BHP Billiton Cannington Mine is now considering development of a Grinding Circuit Optimizer utilizing the models developed for the simulator.

Apr 1, 2005

By J. Szekely, J. W. Evans

A formulation is given for radiant heat loss from the surface of molten steel held in a ladle and numerical solutions are presented for the resultant integrodif-ferential equations. The results are shown on plots of the net rate of heat loss against time, with the geometlry, emissivities, thermal properties of the walls, and Preheat as parameters. It was found that the rate of the vadiant heat loss from the exposed metal surface was comparable to the conductive losses from the Portion of the metal in direct contact with the walls. The radiant heat loss was markedly affected by the geometry and by the thermal properties of the walls the net radiant heat loss from the steel could be drastically reduced by providing a top cover and also by the provision of preheat. The results of this work are thought to be relevant to heat loss calculatious concerned with vacuum degassing and with operatzons in which molten metals are held in ladles. WhEN molten steel is held or transferred in ladles heat losses inevitably occur. The accurate assessment of these heat losses is of importance in process design considerations, as the temperature of the metal may have to meet rigid specifications in certain stages of the processing sequence. As shown in Fig. 1, the principal mechanisms responsible for heat loss are: i) Conduction into the walls and ii) Thermal radation from the top metal surface (possibly augmented by natural convection) The conductive heat loss may be readily calculated as much information is available in the literature on both the general theory1'' and on its particular applications to ladle heat loss calculations. Evaluation of the radiant component of the heat loss is less straight-forward. In two recent papers it has been shown that the presence of a slag layer 2 to 3 in. thick would prevent any significant heat loss for periods up to an hour,5'" however, should bare metal be exposed, constituting the radiant surface, substantial heat losses could occur. This latter case is of considerable practical interest in various degassing operations and in the vacuum processing of certain specialty steels, where the top surface of the metal is not covered by a protective slag layer. Under these conditions a substantial radiant flux is emitted by the top metal surface; part of this flux leaves the system, part of it falls in the ladle walls. The radiant flux incident on the ladle walls is in part absorbed and conducted away, and in part reflected and re radiated. The purpose of the paper is to present a general formulation of the problem, the resultant solution of which should enable computation of the net radiant heat loss from the metal surface. The principal variables, the effect of which will be investigated, include initial metal temperature, geometry, thermal and radiative properties of the wall, and various modes of preheat. FORMULATION Consider a cylindrical enclosure, shown in Fig. 2, with a diameter D, height H, and wall thickness W, the cover at the top of the cylinder having a wall thickness L. If the temperature of the base (representing the top surface of the metal) is kept constant, say, Tb, the problem is to calculate the net rate of heat loss from the base as a function of time, geometry, the initial temperature distribution, and the thermal properties of the system. As customary, the formulation will consist of the mathematical statement of the conservation of thermal energy within the system.

Jan 1, 1970

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006