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By R. W. Gurry, L. S. Darken

The solubility of cementite in austenite is computed by thermodynamic methods from the observed solubility of graphite. It is found that the solubility of cementite is greater than that of graphite in the entire austenite temperature range. Thus the prior discrepancy between this portion of the phase diagram and the observed metastability of cementite is partially resolved. FOR several years it has been apparent that a serious discrepancy exists in certain observations pertaining to the Fe-C system. Direct experimental data indicate: 1-That the curve representing the solubility of graphite in austenite'" crosses that for cementite4 at about 945°C as shown in Fig. 1. 2— That graphite and austenite saturated therewith are stable1 relative to cementite at all temperatures between the eutectoid, about 723°C, and the eutectic, about 1153°C. These observations are mutually incompatible in view of a well-known consequence of the second law of thermodynamics, namely, that the stable phase (presumably graphite at all temperatures) has a lower solubility than the metastable phase (presumably cementite). Hence either 1 or 2 above must be in error; either the measured solubility of graphite or of cementite, or the observation as to the stability of graphite, is in error. Our present purposes are: 1—To collate the available data on cementite and prepare a table of HO — HO° and of (Fa— HO°)/T. This tabular method seems the best and most convenient way to represent the heat and free energy of formation. 2—To determine whether the measured solubilities of cementite and graphite in austenite are in accord with the above table and the measured thermodynamic properties of austenite, in order to resolve, if possible, the existing paradox of these two solubilities. Enthalpy of Cementite The enthalpy of cementite at 273 °K, H279 — HOcem, was computed by integration of the low temperature heat capacity as measured by Seltz, McDonald, and Wells" 68" to 298 °K) and as given by the Debye functions recommended by them (0" to 68°K); the result is included in Table I. At higher temperature HCem — H,,"" is given by Kelley who used the data of Naeser7 (298" to 1037°K) and of Umino8,9 (273° to 1923°K). We have recalculated Hcem — H273 cem from the data of UminoO in the following way. In the equilibrated alloy at temperature the weight fraction of cementite Pct c -Pct cr is PctC -PctCr designated f(C), and the

Jan 1, 1952

By K. Terhaar

The objective was to determine operating protocols for a lead and silver column flotation cleaner, being considered for installation at Sunshine Mining & Refining Co.'s Kellogg mill in Northern Idaho. In this column, tetrahedrite and galena were floated, and pyrite and other gangue minerals, including siderite and silica, were depressed. The procedure was to develop a dynamic simulation using a linear transfer function approach. The transfer function related cause and effect variables such as the influence of collector and depressant dosages on recovery and grades. Bench-scale flotation tests followed by pilot column testing provided the data used to develop a linear transfer function. The transfer function was derived using a spreadsheet. This model was applied to simulate how the flotation column could be made to respond to disturbances in feed grade. The results were that xanthate, zinc sulfate, and sodium cyanide were found to be suitable controls for grade and recovery. Simulations showed the best sequence of manipulations of these reagents, and these sequences were useful for future operator training. The conclusion was that linear transfer functions were able to simulate lead and silver recovery, develop scenarios for operator training, and provide a foundation for future on-line control.

Jan 1, 1999

In spite of the tremendous amount of research conducted in the last few decades. no single blasting theory has been developed and accepted that adequately explains the mechanisms of rock breakage in all blasting conditions and material types. Given specific test environments, conditions and assumptions, individual researchers have contributed valuable information and insight as inputs into blasting theories, although a simple "plug-in" type formula for predicting optimum fragmentation, muck pile geometry and casting distance, is still largely unresolved. There is as yet, no consistent and widely applicable theory of blasting, but only a number of limited and disconnected theories; many of which are empirical in nature and based on ideal blasting conditions. Blasting theories have been formulated and based on pure speculation, years of blasting experience on a trial-and-error approach, laboratory testing, field investigation, and mathematical and physical models adapted from other disciplines of science.

Jan 1, 1988

By Donna L. Boreck

In an effort to increase recovery in thick and closely spaced coal seams, the Bureau of Hines, U.S. Department of the Interior, is studying the feasibility of introducing three mining methods-high-face longwall, multi-slice longwall, and longwall caving-in western coal operations. Geology plays a significant role in determining the success of such methods. Some of the factors that will affect development are as follows: (1) thickness and three-dimensional configuration of the seam, (2) cleats, joints, and fractures in the coal and roof rock, (3) roof composition and variability, and (4) coal quality and changes in quality within the seam. Through geologic mapping, the presence of many of these factors is predictable prior to development.

Jan 1, 1987

High-type research metallurgist with approximately following qualifications: American, 30 to 45 years old. Mind-Analytical. Education-college graduate. Practical shop experience-not less than 5 years. Metallurgical experience in steel making-at least 5 years. Chemical experience-should have some chemical training. Research ability -should be the type of man who is interested in new developments or research work. No. 337. Engineer with some underground, experience who is physically able to spend a large portion of his time underground, to act as general efficiency engineer. He will have cost keeping on special work, charge of contracts, labor distribution, etc. No. 338. The services of a man experienced in flotation and familiar with the Callow apparatus are required for a short engagement in South America. No. 339. A position as surveyor and draftsman for mines in Mexico is open. Opportunity for advancement. Climate pleasant and healthful. Knowledge of Spanish required. No. 340. The Bureau of Construction and Repair, Navy Department, Washington; D. C., is in need of a few draftsmen of experience for work in connection with the development of industrial yards and shops of the Navy, under the cognizance of the Shore Establishment Division of the Bureau of Construction and Repair. Training in one of the following courses would be considered a requisite qualification:

Jan 9, 1918

By O. Martinsson

The Kiruna area is an important mining province in northern Sweden, which is dominated by Fe- and Cu-Au deposits. Economically most important for the region, are the apatite iron ores with an annual production of c. 43 M ton of crude Fe-ore and a total production of more than 2000 M ton of ore the last 100 years. The apatite iron ores in the Kiruna area are dominated by either Magnetite or Haematite and contain varying amounts of apatite giving them a content of Fe and P, which varies between 30-70 % and 0.05-5 %, respectively. A typical geochemical feature of the ores is the strong enrichment of REE that is caused by a high content of REE in apatite and the occurrence of Allanite and Monazite containing 22.4 and 69.8 wt% REO, respectively. At Kiirunavaara, the content of REE in apatite varies between 0.07 to 1.57 wt% REO with a dominance for the light rare earths. The variation in REE-content of apatite depending on textural and paragenetic aspects is not known but apatite grains may display a strong LREE-depletion due to hydrothermal alteration. Monazite occurs as rod-shaped or tabular inclusions in apatite and is suggested, to have formed in response to hydrothermal alteration of apatite after the emplacement of the ore. Inclusions are mainly found in the central part of apatite grains occurring in veins and schliren, while they are rare in apatite occurring disseminated in the ore. Monazite also occurs as larger grains outside apatite and together with Allanite is found in texturally and paragenetically different settings within the ore. These occurrences of REE-minerals may largely be a product of LREE mobilized by alteration of apatite after the emplacement of the ore. However, REE-minerals including Allanite and Monazite might also have formed directly from late magmatic fluids. Keywords: apatite, monazite, allanite, ree, kiirunavaara, iron ore of kiruna type, mineral chemistry

Sep 1, 2012

By Arnold M. Lansche

DOMESTIC OUTPUT of white arsenic, As2O3, was derived entirely as a byproduct of smelting arsenic-containing copper ores by The Anaconda Company at Anaconda, Mont., and American Smelting and Refining Company at Tacoma, Wash. Arsenic metal was not produced. Consumption, and Uses.-Most of the white arsenic produced in 1964 was consumed in manufacturing lead and calcium arsenate insecticides. In the 12 year period since 1951 the production of lead arsenate insecticide has varied between 7,800 tons and 4,900 tons, indicating that lead arsenate has maintained its position in competition with organic insecticides.

Jan 1, 1965

By D. Duvris

The main objective of this work was to quantitatively investigate exhaust emission levels relative to maintenance (service) intervals during the operation of diesel-powered equipment at an underground bauxite mine in Greece. Such emissions depend on a great number of parameters, including the type of engine (technology) and its tuning, the type of work performed (as related to the engine workload), the suggested maintenance intervals, the altitude, the temperature and humidity of the atmosphere in the underground mine, the properties of the fuel and the operator's training and experience levels. The necessary ventilation quantities were calculated based on exhaust gas-concentration measurements and site-specific relationships between pollutants and adjusted air-quality indices. Diagrams comparing the necessary and recommended airflow for several equipment groups, featuring two engine types and different maintenance intervals, are presented.

Jan 1, 2000

By H. Evans, L. A. Hunt

In the pellet-producing industry it is sometimes claimed that "The pellets are made in the concentrator," or that "The key to good pellets is in the balling operation." However, one claim is generally agreed on: If you can put in, on, and through the indurating furnace a good green ball of Proper size and adequate strength to withstand the handling, load, dehydration, and thermal shock until it is properly heat-hardened, you will have the pellet product you desire-that is, a "competent" green ball. The strength requirements that enable a competent green ball to withstand the environment of the indurating furnace are usually less restrictive than those for transporting the green ball from its source of production to the furnace. Experience has shown that different types of material may have different balling characteristics which may impose limitations on the quality of the green ball that can easily be produced under normal conditions. Therefore, if a specific material will produce a green ball that meets the physical requirements for competency in the furnace, but not for handling or transportation, various practices must be instituted to overcome this deficiency. In other words, if a normal handling system is too rigorous for the green balls that can be produced under standard conditions, then "handling with care" should be tried.

Jan 5, 1967

By R. F. Hochstein, A. J. Neale, B. C. Flintoff

"Process control technology holds very significant potential benefits for many mineral and coal processing plants. The impact can be expected in terms of performance improvements (e.g. increased throughput, better quality control, higher availability), through reduced operating costs (e.g. lower reagent consumptions, manpower reductions) and in the form of intangibles (e.g. reduced vulnerability to manpower turnover, increased productivity in the user group). However, the installation of a process control system will represent considerable capital expenditure and will generate an operating cost. No management team would approve the funding for such a project without some reasonable measure(s) of the profitability of a proposed system. This paper describes a methodology for addressing the justification problem. Of particular interest is the approach to quantifying performance improvements, frequently found to be the predominant benefit of process control.INTROPUCTIONProcess control has become widely recognized as an essential component of any processing operation. It has direct impact on productivity, process efficiency and product marketability. The reported pay backs associated with successful installations underscore this observation. As a consequence, many operators who have little in the way of process automation are looking to initiate control projects, while those who currently enjoy some level of automation are looking to upgrade existing control systems (= process + instrumentation + hardware + software + operators + support). While the emphasis here would appear to be on retrofit process control projects, new plants, or those currently in the design stage, will usually find themselves in one of these categories shortly after startup 1."

Jan 1, 1990

By D. R. Mitchell

MEETING for the thirteenth time in New York as part of the five-ring circus known as the Annual Meeting A.I.M.E., the Coal Division experienced a wartime boom in attendance. Technical sessions were crowded and whereas 65 seats were set up for the annual luncheon meeting of the Division over 100 members showed up, many of whom had to be fed elsewhere. Possibly the Coal Division should adopt "13" as its lucky number. Discussions at technical sessions, formal and informal, were lively. Those papers containing material directly concerned with the war, or containing information that might be usable for war industries, were enthusiastically received. Some criticism was made in regard to the present method of handling discussions and it was suggested that better success would be had in getting discussions in the record by the use of hired reporters. This is being considered by the executive committee of the Coal Division.

Jan 1, 1943

Develop technology that can reduce the dust exposure of a mine worker at the tailgate end of the longwall face by providing him with a clean split of air. Approach Use the jet spray air mover (JSAM) developed under a Bureau of Mines contract (refer to Technology News No. 117 for details on the development), to clean a small portion of the face air and to discharge the clean air behind a brattice partition. How It Works At most longwalls, air flows along the face from head-to-tail. Most of the airborne respirable dust generated along the face during mining is transported to the tailgate with the airflow. Any miner required to work at the tailgate is exposed to this dust. The only practical means of removing airborne respirable dust is with a scrubber. Simplicity and size made the JSAM the best choice for cleaning a portion of the tailgate air. The scrubber has no moving parts and is operated by water at low flow rates (<10 gpm) and fairly high pressures (250-500 psig). Many longwalls have sufficient water systems to supply the JSAM with adequate water pressures and flow rates. Also, the JSAM&apos;s size (4&apos;x 2&apos;x 1&apos;) allows it to be hung on one of the tailgate&apos;s shields or at some other convenient location. A clean split can be maintained at the tailgate by discharging the cleaned air behind a brattice partition at the work area. This should effectively seal off the clean air from the dusty air and provide the tailgate worker with a less dusty work environment.

Jan 1, 1983

By Brian Flintoff

SCOTT COULTER: Our second speaker today is Brian Flintoff. Brian graduated from the University of Alberta in 1973 with a master&apos;s of science degree and worked as a project metallurgist at Brenda Mines until 1977. He returned to the University of Alberta in late 1977 to work on his Ph.D. and later joined the faculty of engineering in 1980, leaving in 1988 to rejoin Brenda in the newly formed process technology division. In 1998 he left Svedala-Brenda to take a position with Simons International&apos;s newly formed enterprise development services group. His topic today is "People: Reduce, Reuse, and Recycle." INTRODUCTION BRIAN FLINTOFF: Historically, the mining industry has relied on the people within a corporation to get things done. The culture of most companies was one of a slow but sure development of people, processes, equipment, and technology. Many of the larger companies supported in-house engineering and research organizations. However, the metal market pressures of the 1980s and the emergence of the global economy in the late &apos;80s and early &apos;90s put enormous financial pressures on the industry. As the old adage says, "necessity is the mother of invention," and the mining industry, like many others, has undergone a transformation. A cornerstone element of the transformation was the downsizing (or right-sizing) that was calculated to "trim the fat" from the capital and operating budgets. The goal was and is to find the highest sustainable operating profit.&apos; While I&apos;m sure one can find examples of losers (e.g., those who can be classified as suffering from corporate anorexia or institutional Alzheimer&apos;s) in such business reengineering efforts, there is little doubt that, on the whole, the transformation has been successful. The reality that now faces mill management is "How to do more with less?" At the risk of oversimplifying, one can look at this on two levels:

Jan 1, 1998

By Xinli Wang, Matthew Andriese, Jiann-Yang Hwang, Zhiwei Peng, Byoung-Gon Kim

"The microwave reflection loss (RL) of ferric oxide is studied in the temperature range from 297 to approximately 1400 Kat frequencies of 915 and 2450 MHz. It is shown that the maximum microwave absorption with RL of -38.46 and -35.97 dB can be obtained for ferric oxide having thicknesses of 0.03 and 0.01 m at 915 and 2450 MHz, respectively. The maximum absorption peak with RL below -10 dB is in a 250 K temperature range from 723 to 973 Kat 915 MHz, which shifts to the range between 823 and 1073 K at 2450 MHz. This migration is in good agreement with the variation of the dielectric loss tangent of ferric oxide.IntroductionMicrowave irradiation has distinguishing characteristics such as volumetric and selective heating compared with conventional methods, leading to extremely broad applications in materials heating and processing [1-5].The efficiency of microwave heating was found to be dependent on various factors, such as microwave power [6], frequency [7,8], radiation time [8], applicator geometry [8], sample microwave absorption properties and position as well as dimension [9-11 ], etc. Among these parameters, sample dimension plays an important role but is usually neglected by researchers in microwave processing of materials. In fact, although numerous studies have been directed toward the utilization of microwave energy to assist materials heating and processing, few reports were released on the effect of sample dimension [12,13].This is because all aforementioned factors influencing microwave heating generally exert interactive effects to each other during the heating process, making clarification of the effect of sample dimension difficult. Therefore, it is necessary to propose a parameter or concept for quantifying the effect of absorber dimension on microwave heating, increasing heating efficiency."

Jan 1, 2013

By A. M. Keenan, R. H. Carpenter

Geologic faults have always been a plague to the mining industry, and have often reduced a mining venture from a profitable to a marginal operation, and even at times have forced companies to liquidation or bankruptcy. The use of geology as an economic tool in coal mining is not generally recognized, particularly in coal deposits which are horizontal or essentially flat-lying, in which faulting might not be prevalent. However in pitching coal seams, the existence of faults is considered an inherent challenge, as the inclination of the seam or seams per se, is a product of geologic disturbance. The problems of faults are a constant challenge to the management of the Thompson Creek Coal and Coke Corp. in their operations in Pitkin County, Colorado, where high grade medium volatile coking coal is mined. The background for this paper has been provided by the experiences of these operations, in overcoming the effects of faults in mining, and resolving the fault structures. The properties of the Thompson Creek Coal and Coke Corp. are located in central Colorado, 13 miles southwest of Carbondale, Colorado, a tow] on the main highway between Glenwood Springs and Aspen, Fig. 1. The elevation at the mine portals is approximately 8000 feet: there is a relief of some 2.000 feet to the adjacent ridges rising away from the [nine portals. &apos;The entire present production of these properties totaling 180.000 tons of clean coal per year is trucked to the railhead at Carbondale, Colorado, from whence it is shipped to the Geneva Steel Plant at Provo, Utah. The properties were initially opened in September 1952. A total of 125 men are currently employed with the production conting from the Number 1 and 3 Mines, and development workings of the Number 2 and 5 Mines respectively. While the No. 2 Vine was opened in 1953 prior to No, 3 Mine, the encountering of faults without sufficient development work accomplished to sustain production, necessitated the diversion of manpower to the other [nines for economic considerations. GEOLOGY &apos;1-he productive coal seams occur in the Mesaverde formation of Late Cretaceous age which outcrop along the eastern edge of the Piance Creek Basin from the Grand Hogback, a part of the southwestern flank of the White River Uplift north of Glenwood Springs, southward through the &apos;Thompson Creek area and the

Jan 1, 1961

By P. James

Blue Planet Strategies (BPS) focuses on improved resource utilization and targets converting wastes into resources. New BPS capability (DEMET) wrings extra value from mining and processing wastes by enabling new production from waste and residual sources. This powerful platform technology provides considerable processing flexibility and enables various new economical treatment options to extract key metals from low level and process byproduct stream sources normally left as waste by traditional processing methods.[1]

Feb 23, 2014

By P. R. Jones

"The paper describes the CDN$400 million expansion at Hudson Bay Mining and Smelting Co., Limited’s operations. The company has continuously produced copper and zinc at the Flin Flon metallurgical plant since 1930. The paper details the company’s operational turnaround since 1995 and “The 777 Project” which includes two new mines, expansion and modification of the concentrators, expansion of the zinc pressure leach plant, a new zinc electrolytic cellhouse and modifications to the copper smelter gas handling system to reduce ground level gas emissions. IntroductionHudson Bay Mining and Smelting Co., Limited (HBMS) was incorporated in 1927 to mine and process the world-class Flin Flon copper and zinc orebody. Ore concentration and metallurgical facilities were constructed in Flin Flon. The metallurgical complex capability is currently 89 000 tonnes of copper metal and 98 000 tonnes of zinc metal from both HBMS and purchased concentrates.Flin Flon, with a population of 7000, is in Manitoba and partly in the province of Saskatchewan. The location is isolated with Winnipeg 800 km to the south and Saskatoon 500 km southwest.Today, three underground mines feed the Flin Flon concentrator, one feeds the Ruttan concentrator at Leaf Rapids, 200 km to the north of Flin Flon, and Chisel North mine feeds the Snow Lake concentrator (Fig. 1).The Flin Flon volcanic massive sulphide proximal and distal orebodies are within the Flin Flon greenstone belt which stretches from the west of Flin Flon to the east of Snow Lake, a distance of 250 km. The belt is approximately 100 km wide before disappearing below the paleozoic cover to the south."

Jan 1, 2001

By Steven A. Fechner

The U.S, Bureau of Mines is conducting a four-year (1987-1990) study to assess the mineral resources and mineral development potential of the Valdez Creek Mining District in southcentral Alaska. This study is part of the Bureau&apos;s ongoing statewide mining district evaluation program. This report summarizes the Bureau&apos;s site specific evaluations of two areas (Tyone and Peters Creek) of the district that were investigated to determine the bedrock sources of gold and PCM in the alluvial gravel of both areas. In the Tyone Creek area, grains of gold (up to 0.0212 oz/yd3) and platinum group minerals (PCM) were recovered from alluvium and weathered conglomerate of the Jurassic Naknek Formation and Tertiary age using placer sampling techniques, Platinum and palladium were detected in the heavy mineral concentrates recovered from placer sampling the alluvium, and Naknek Formation and Tertiary conglomerates. In the Peters Creek area, grains of gold (up to 0.014 oz/yd3) were recovered from the alluvium and Tertiary Sterling Formation conglomerate. The Bureau&apos;s evaluations indicated that drainage basins containing conglomerate are the most favorable targets for placer gold and PGM exploration; and Tertiary conglomerate represents a high volume, low grade gold resource.

Jan 1, 2011

By Michael Perch, Charles C. Russell

Nearly 75 per cent of the total coke production in the United States in 1940 was consumed in blast furnaces. In 1939 the percentage was 69.9, and in 1938 it was 61.3. To produce a net ton of pig iron 1757 lb. of coke was required in 1940 and 1760 lb. in 1939. These figures indicate how dependent the production of pig iron is upon the production of coke. The rate of iron production is in some measure influenced by the physical and chemical characteristics of the coke. Blast-furnace operators believe that the physical properties of coke profoundly influence the operation of the furnace. Although it is true that coke of a wide variety of physical properties is used in American blast furnaces, the periodic fluctuation of these properties is one of the causes of irregularity of blast-furnace operation. The purpose of this paper is to present a broad picture of the physical properties of by-product coke that are generally considered to be important by coke-oven and blast-furnace operators. Effects of the kind of coal used, the preparation of the coal, the rate of coking, and other factors will be considered. Of all these variables, the kind of coal used is by far the most important. In this discussion use will be made of the method of coal classification by rank&apos; standardized by the American Society for Testing Materials. Although this method of classification has been an American stand¬ard for several years, it has not been given the attention it deserves, especially in connection with the selection of coal for production of coke. Despite the fact that many producers of blast-furnace coke are limited to some particular source or sources of coal, a good understanding of the principles involved in setting up the standard method of classification may lead to a better appreciation of the causes of changes in coke characteristics. Furthermore, where it is necessary to select new coals as a substitute for the original supply, this method of classification can be of great assistance. The data presented have been gathered from many sources, but no attempt has been made to cover the vast literature. Instead, some of the more important data have been selected to show how coals and their carbonization affect some of the physical properties of coke. It must be emphasized that generalizations concerning the behavior of coking coals are presented and that individual coals may vary widely from the specific behavior depicted. Nevertheless, it is believed that the data illustrate certain typical behaviors. Neither was it possible to cover completely all the factors involved; for example, the macroscopic constituents of coal are believed to have important effects on the physical properties of coke, but since there is little information available for such study, and since vitrain, clarain, and durain are neither

Jan 1, 1944

By J. A. Bowers

THIS investigation of the effect of bottom shape and life on slag volume was carried out in two Lectromelt top-charge furnaces whose rated capacity is 1000 lb per hour. Unfortunately, just as the work [ ] was started, our steel tonnage was reduced approximately one half, therefore we did not accumulate enough data from which to draw any definite conclusions. Furthermore, the life of the linings in these furnaces was greatly decreased by intermittent operation, which was a further handicap in making a study of this kind. The weight of the heats from which the data were taken varied 1200 lb but all the information was corrected to the standard weight charge for these furnaces of 4500 lb. Almost all the heats were plain carbon; a few contained a small percentage of added copper.

Jan 1, 1947