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Correlation of Air Recovery with Thin Film and Froth Stability in Flotation

Sep 13, 2010

By E. R. Phelps

A determination of feasibility of a new surface mining project requires a study in orderly fashion through the procedures outlined in Section 2 and the previous two chapters of this section. The information and data collected as described in Chapters 3.1 and 3.2 must be correlated, and the many variables that affect the venture must be reviewed. This review will furnish the mining engineer with the information required to make a preliminary evaluation of estimated profit in the venture. It is at this time that management must make yet another decision whether to drop or continue the project. 3.3-1. Maps. For the purpose of collecting, outlining, and correlating a large portion of the data required for a surface mining feasibility study, maps are essential. A map to a mining engineer is like a sheet of music to a musician, or a blueprint to a designer. It provides a pictorial method of presenting mining information not only for practical application in estimating and planning, but also for demonstration of physical relationships to those charged with decision-making responsibilities. GENERAL AREA MAP. The first step in the process of graphic information assembly is the preparation of a "small scale" general area map. Such a map may cover a mining district, a market area, a watershed area or district, or the whole or a section of a geologic feature such as an iron formation or coal seam. An example of such a general area map is shown in Fig. 3.3-la which outlines the various coal mining areas in the vicinity of a proposed "mine-mouth" power station, the Liddell Power Station Project. If Quadrangle Maps of the United States Geological Survey, or their equivalent, are available for an area, a common and very effective technique is to superimpose mining data on these maps, either directly or by means of transparent overlays. Valuable topographic information

Jan 1, 1968

By Earl R. Hoskins, James E. Russell

The electrical resistivity of rocks has been studied quite extensively, in particular, the effects of temperature and confining pressure on resistivity. References 1 through 6 at the end of this chapter pertain to electrical resistivity of rock and contain further references on the same topic. The present study is motivated by an interest in determining the in-situ properties of rock as well as the stress state of the rock and how these quantities are changing with time. Most of the previous work on the electrical resistivity of rocks has been directed toward saturated rocks at relatively high confining pressures and temperatures. The present study was oriented towards air-dry surface rock that might occur in mine pillars. The mean stress and temperature under such conditions are comparatively low. It has been demonstrated that the resistivity of rock is highly dependent upon the porosity. In fact, for saturated rocks, a relationship referred to as Archie's law has been established between porosity and electrical resistivity. In the case of saturated rock, the property that is actually being measured is the resistivity of the solid/fluid system. Since the resistivity of the fluid alone is usually much lower than that of the dry rock, it is understandable that the resistivity of a saturated rock is in general several orders of magnitude lower than the resistivity of a relatively dry rocli. For dry rock, it seems reasonable that the electrical resistivity should increase as microcracks open within the material. Since microcracks open as material is stressed closer and closer to its failure point, it appears that there should be a correlation between electrical resistivity

Jan 1, 1970

W. 0. HOTCHKISS,* Madison, Wis.-When we began to do geological field work in the Lake Superior region, we found a correlation in existence, and, as youngsters, accepted all that as settled. Both Mr. Allen and I, since that time, have seen a great many things that were not apparent nor visible to Van Hise, and those who worked with him; we realize now that the correlation was not final and that much remains to be determined concerning geology of the Lake Superior region. My attitude on this matter is that we should not publish an amended correlation as a final thing. We should avoid, in every way possible, foreclosing the minds of those who follow us in working in the geology of this region. As a matter of fact, no correlation can be final at present, because facts and data are accumulating so rapidly that every classification must be immediately modified to fit further observation. Consequently, my attitude in this matter would be, instead of saying that the iron formations of the Lake Superior region are all Middle Huronian, to say that there may be three Huronians-or four or five- we do not know. I believe it is better policy to hold to our present correlation. I do not believe there is any economic benefit to the mining man or the geologist working on problems relating to explorations for iron ore, that cannot be just as well solved by maintaining our present correlation, with a. wholesome idea of our lack of knowledge and the necessity for further detailed work. Then, if any new horizons are discovered in any particular range, the minds of the investigators will not be foreclosed because some one has said that all the iron formation is in the Middle so that there is no use looking elsewhere for it. There is use looking elsewhere, in many cases, as the ore deposits become exhausted.

Jan 1, 1920

By A. Wahab Khair, W. M. Devilder

"This paper presents an analysis of fragment size distribution and characteristics of fracture surface in coal cutting using a rotary coal cutting simulator. Coal cutting by a drum type continuous miner was simulated in the laboratory. A series of tests along both the face and butt cleat direction of coal under different operating and in-situ conditions were performed. In each experiment the cut surface was photographed microscopically and the coal cuttings were collected and sized. Data were used to show how and to what extent various parameters effect size distribution of the coal cutting and how this correlates with the characteristics of the fracture surface. This study resulted in establishing a number of distinct correlations between the size distribution and fracture surface. These correlations were primarily based on the degree of interaction between adjacent bits and the amount of bit-coal interaction taking place on the cutting path. Some of the major results of this study are as follows:Zones of bit-coal interactions proved vital toward understanding the effect the conical bit has on the fragmentation process. This in turn led to the identification of areas which are responsible for the production of fines and generation of respirable dust.The various parameters employed in the coal cutting experiments which showed a strong effect on the coal fragment size distribution were: bit type, bit spacing, depth of cut, in-situ stresses, and cleat orientation. Bit angle and cutting head velocity exhibited the least effect and no correlation was established.From this study it is obvious that the key to achieving efficient coal fragmentation is to limit the degree of bit-coal interaction that takes place throughout the bit path while causing maximum interaction between adjacent bits. Accomplishing this not only increases the percentage of large fragments produced but limits the amount of secondary crushing that takes place in the bit path thus resulting in decreasing fines and consequently, the amount of respirable dust generated.Over 2,000 continuous mining machines (introduced in the 1950's) equipped with conical bits or point attach bits account for well over half of the United States' production from underground coal mines. Today, competition in the coal industry has increased, due mainly to coal market conditions and legal restrictions, thus placing an emphasis upon increasing production, efficiency and health/safety of the workers. Mine operators are always interested in finding the most efficient performance of continuous mining machinery to produce the largest amount of size of coal at the lowest cost. An increase of fine material sent to the cleaning plant can seriously overload the plant to the extent that plant efficiencies deteriorate significantly (1). Also, the difficulty and expense of cleaning very small particles often cannot be done economically and thus, thousands of tons of coal are sent to the refuse pile because of costly or ineffective cleaning facilities. It has been said, ""the efficient extraction of coal or rock implies breakage into a size range that contains a minimum quantity of very small sizes"" (2). All known fragmentation theories concur that more fragmentation requires more energy (3). So, the importance of reducing fines is already evident from an outlook upon efficiency.Now, let's consider another view point., duet generation."

Jun 1, 1988

By A. F. Buddington

INTRODUCTION EVER since a genetic connection between many ore deposits and magmas began to be widely recognized, some two-score years ago, there has been much discussion of the complex and intricate problem of the genetic association of specific kinds of mineralization with specific kinds of igneous rocks. General discussions of the latter problem and pertinent data have been given by S. F. Emmons, Kemp, Lindgren, Niggli, Rastall, Spurr, Vogt, and others. In this paper no attempt is made to deal with mineral deposits genetically associated with volcanic rocks, but only with those presumed to be related to exposed intrusive masses. The writer is indebted to E. S. Bastin, F. F. Grout, Edward Sampson, and to the members of the committee in charge of the preparation of the volume, for a critical reading of the manuscript and many worth-while suggestions.

Jan 1, 1933

By Henry Rawdon

ANY laboratory corrosion test, as judged from the practical point of view, is valuable only to the extent that it foretells what will, in all probability, occur in service. Such a test is most properly to be considered as a "pilot test, " that is, a test which indicates the direction along which action may be expected to occur rather than as a truly quantitative test which would be expected to tell just how and to what extent the action would proceed. It is generally recognized that laboratory corrosion tests should be chosen with particular reference to the character of service expected for any particular type of metal, so far as it can be foreseen. Even when this requirement has been fulfilled, however, the question whether the actual service behavior of the material is in accordance and general agreement with predictions based upon such laboratory tests is always a pertinent one. The information available in the technical literature bearing on the correlation between the service behavior of metals from the corrosion standpoint, and the results obtained with the same metals in laboratory corrosion tests is very meager, indeed. The results which have been obtained in weather-exposure tests of sheet duralumin which form the body of this discussion are presented here for their bearing on this particular phase of the problem of the corrosion resistance of duralumin. Although the exposure tests described have not been completed, in the sense that all of the tests, in the series initially laid down, have been accomplished, still the general trend shown by the results is so clear that a number of definite conclusions at this stage (subject, of course, to possible modification in the light of later results) are believed to be warranted. The tests reported upon here form one phase of the much broader study of this subject which has been under way for several years in which the National Advisory Committee for Aeronautics, the Bureau of Aeronautics of the Navy Department, the Army Air Corps and the Bureau of Standards have cooperated. Without the very helpful cooperation of the manufacturers in furnishing the

Jan 1, 1929

By A. A. Afshari, D. G. Frazer, C. F. Stanley

"INTRODUCTIONThe primary function of the lung, i.e. gas exchange, occurs in peripheral units termed alveoli• Diagnosis of lung dysfunction ls therefore dependent on techniques to evaluate the status of the peripheral airways. Since these airways and alveoli are very small, it is difficult to determine directly how they function or how the function is changing due to disease. Yet this unde1·standing is critical to the design of instrumentation to detect early changes in lung function due to disease.An interesting hypothesis describing one aspect of small airway function has been proposed by Frazer (1) as gas trapping due to the formation of menisci in the airways. An additional study (2) proposes that the breaking and possibly the formation of these menisci could generate lung sounds, i.e. crackles. These lung sounds were recorded by placing a microphone at the trachea of an excised rat lung. The lung was degassed and then inflated and deflated. At points along the path of inflation, lung sounds were recorded. However, determination of the origin of the sounds was not attempted due to the difficulties induced by contacting the lung st1rface with a microphone.The purpose of this paper is to describe a non-contacting, whole field technique to monitor and describe the movements of the lung surface during inflation - deflation cycles.HOLOGRAPHIC INTERFEROMETRYHolographic interferometry is a full field, non-contacting and non-destructive technique that measures deformations of an object with a sensitivity in the order of the wavelength of light. A laser beam is split, with one beam reflected from an object and the other used as a reference beam. Both beams combine to produce a hologram of the object on a photographic plate. The process utilizes the concepts of interference, i.e. the two wave amplitudes will add at the points where the difference in optical path lengths over the exposure period is zero or a whole number of wavelengths and will subtract at other points."

Jan 1, 1989

By Kain Petterson, P D. Katsabanis

Blast fragmentation, determined using image analysis was correlated to drill monitoring parameters in an open pit operation. Average fragment size and 80% passing size showed strong correlation with specific energy of drilling as well as with torque, while the same passing sizes did not correlate well with the rate of penetration. It was also determined that the uniformity of fragmentation decreases with the specific energy of drilling. Thus drilling monitoring parameters appear to be valuable in determining the blastability of the rock mass, enabling adjustment of blast loading to respond to changing conditions in the rock mass.

Jan 1, 2013

By Ian Buterbaugh, Calvin Lo, Tomoko Sano, Brendan Koch, James Catalano, Timothy Walter

In this research, two grades of alumina, one at nominally 85% composition and the other at 99.5% were characterized. Microstructural and phase characterization was conducted using Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X-ray Diffraction, and micro-computed X-ray tomography. It was determined that the Knoop hardness values were influenced by the porosity in the 85% composition. Quasi-static compressive tests and high strain rate compression experiments were conducted to determine the influence of the microstructure to the compressive properties. It was observed that the overall compressive strengths increased with strain rate. Although the Knoop hardness values were much lower in the 85% alumina due to the porosity, the compressive strength at both quasi-static and dynamic strain rates were not significantl lower than those of the 99.5% composition.

Mar 1, 2018

By E. J. Peterson

Oil shale retorting induces mineral and chemical reactions to occur on the macroscopic and microscopic levels in the kerogen-bearing marlstone. The nature and extent of the reactions is dependent upon process variables such as maximum temperature, time at temperature, atmosphere, and raw shale composition. This report describes the investigation of the mineral, chemical, and trace element release properties of spent shales retrieved from an experimental in situ retort at Occidental Oil Shale, Inc. 's Logan Wash site in Garfield County, Colorado. Correlation between mineralogy of the spent materials and the mobility of major, minor, and trace elements are indicated, and relationships with important process parameters are discussed. The progress .of carbonate decomposition reactions and silicat ion reactions is indicative of the processing conditions experienced by the shale materials and influences the mobility of major, minor, and trace elements when the solids are contacted by water. Shale minerals that are exposed to the extreme conditions reached in underground retorting form high temperature product phases including akermanite-gehlenite and diopside-augite solid solutions, kalsilite, monticellite, and forsterite. The persistence of relatively thermally stable phases, such as quartz, orthoclase, and albite provide insight into the extremes of processing conditions experienced by the spent shales. Leachate compositions suggest that several trace elements, including vanadium, boron, fluoride, and arsenic are not rendered immobile by the formation of the high-temperature silicate produce phase akermanite-gehlenite.

Jan 1, 1981

By D. J. A. Chambers, J. M. Wempen, K. D. Koper, M. K. McCarter, K. L. Pankow

"The EarthScope Transportable Array (TA) of broadband seismometers (www.usarray.org) was deployed across southwest Wyoming from November 2007 through May 2009. During this time period the Array Network Facility (ANF, anf.ucsd.edu) detected and located a total of six seismic events near the trona-mining district. This lack of seismicity is atypical compared to coal mines employing similar mining methods. In this study, eighteen months of continuous seismic data from several nearby TA stations are reexamined using conventional and correlation-based methods to detect seismic events. Waveform cluster analysis and epicentral locations are used to discriminate between mining induced seismicity (MIS) and seismic energy generated from surface blasts at nearby coal mines. The locations and magnitudes of the 143 newly detected MIS events are compared to regional subsidence as measured by Differential Interferometric Synthetic Aperture Radar (DInSAR). INTRODUCTION An abundance of natural resources and a favorable political climate have made southwest Wyoming home to multiple large mining operations. Among these operations are five underground trona mines located approximately 50 km west of Rock Springs, Wyoming. The trona mines employ room and pillar, longwall, and solution mining methods over an area roughly 900 km2, and produce a sizable portion of the world’s soda ash (Brown 1995). Historically, in the Rock Springs mining district, several relatively large magnitude seismic events have occurred. These events are thought to have been related to mining activity and have caused notable subsidence (Case 1997). The largest event in the region recorded by seismometers, ML 5.1, has been confirmed as the 1995 Solvay Trona Mine collapse (Pechmann et al. 1995). In addition, blasting at surface coal mines near Rock Springs produces significant amounts of seismicity; approximately 50% of all daytime seismic events in the Mountain time zone from 2007 to 2009 locate near an active surface mine in this region (Astiz et al. 2014). Much of the current research related to surface subsidence and induced seismicity focuses on wastewater impoundment (Ellsworth 2013) and hydraulic fracturing. The observable seismicity in geological injection environments is widely variable and McGarr (2014) has argued that, in such environments, the maximum amount of seismic energy that can be released is proportional to the injected volumes. Like injection environments, in extraction (mining) environments seismicity is highly variable depending on many geological and operational variables (Boltz et al. 2012; Carnec and Delacourt 2000; Fritschen 2010; Iannacchione et al. 2005; Sen 2013) and does not always correlate well spatially with subsidence, a surface expression of extraction at depth."

Jan 1, 2015

By J. S. Bryner

INTRODUCTION IN the study of metallographic specimens in the electron microscope, there is need for a method of locating the same field in both the light microscope and the electron microscope. This need arises chiefly from the fact that in the electron microscope the magnification and degree of resolution are so much higher, and the field so much smaller than in the light microscope that it is often difficult, if not impossible, to identify positively what is being observed. The difficulty is increased by the fact that, because a transparent film replica of the metal surface must be used in the electron microscope, micro-constituents can be identified not by their color but only by their texture and contours. For these reasons it is desirable to obtain a series of photographs showing the same field in both microscopes in order that the appearance of common microstructures and micro-constituents in the electron microscope may be identified and catalogued for future reference. The need for a method of locating the same field in both microscopes arises also when it becomes desirable to enlarge in the electron microscope for more detailed study a particular interesting structure observed in the light microscope. Using the standard polystyrene-silica1,2 replica technique, in which the silica film replica is fished from the ethyl bromide on a 1/3 in. diam 200-mesh specimen screen, the possibilities of locating a particular area on the film in the electron microscope are rather remote. The desired structure may be obscured by the wires of the specimen screen or unrecognizable at the high magnification. A solution to the problem would be provided if a specially designed specimen screen, containing an opening which could be absolutely identified and quickly located in the electron microscope, could be fastened to the silica film replica in such a position that the desired field on the specimen would be located at the identifiable opening in the specimen screen. The design for such a specimen screen, a method for producing it, and a technique for fastening it to the silica film replica are described below. DESCRIPTION OF METHOD The Specimen Screen A simple design for a specimen screen containing an opening easy to identify and locate in the electron microscope is one with two lines of openings at right angles in the form of a cross. Such a screen is shown in Fig I. The opening at the center of the cross is identified easily and can be located quickly in the light microscope and in the objective image of the electron microscope. The specially designed specimen screens for this work were produced in quantity by electroforming. On both sides of a polished strip of copper 1 X 3 X 1/8 in., twenty patterns of the cross of openings were punched with a diamond point micro-hardness tester, using a load of magnitude

Jan 1, 1948

By R. L. Grayson, S. S. Peng

"Research has been conducted during the past year on a study to correlate respirable coal mine dust characteristics with worker positions and coal seams. The first characteristic of respirable coal mine dust which has been addressed in the correlation study is respirable dust mass concentration. In fulfillment of this objective, two mines operating in different coal seams have been selected for respirable dust mass sampling on both longwall panels and continuous mining sections. At present, sampling has been completed on the longwall panel operating in the first mine, and one half of the planned sampling has been accomplished on the continuous mining section.The first mine sampled is operating in the Pittsburgh coal seam. The average mining height is approximately 78"" with an average of 8"" of bottom shale being mined. The mine is primarily a longwall mine, and continuous mining machines are used to support the longwall.Figure 1 shows the layout of the longwall panel which was sampled. Intake air is coursed via the track heading up to the headgate area. The air splits at the headgate. Approximately 20,000-30,000 cubic feet of air per minute (CFM) is used to ventilate the longwall face and about 5,000-10,000 CFM is routed down the belt entry. Substantial leakage across the gob was noted during the sampling period. An average of 1800 CFM per 100 feet of face leaked through the shields into the gob from #1 shield to #112 shield. A substantial amount of leakage also occurred between the #1 shield and the solid rib of the headgate development panel. The path of the air used to ventilate the panel is shown with arrows in Figure 1. Direction of air flow was opposite to the coal moving direction on the armored face conveyor.A double-drum ranging shearer is used on the face to cut a 30-inch web of coal. Normal practice is to cut from the tailgate to headgate with the leading drum raised and the tail drum lowered for cutting bottom. After reaching the headgate, the shearer is reversed and both drums are lowered for a clean-up pass. The last 40 feet of face on the tailgate is cut on the clean-up pass.The shearer is equipped with 2 banks of 4 water sprays each and 2 large sprays on the headgate end and 1 bank of 4 sprays on the tailgate end. Additionally, sprays are located above bits on the cutting drums. Actual cutting speed was approximately 14-18 feet per minute, depending on conditions.The cross sectional area for air flow on the face was approximately 60 square feet before a pass was mined and 80 square feet after a pass was mined but before the shields were advanced. The cross sectional area at the shearer was about 35 square feet.The condition of both the tailgate and headgate of the panel was good with no signs of significant roof problems. The roof conditions along the face during the sampling period were variable. At times, as much as 3 feet of drawslate fell from the roof for a span of as much as 40 shields. Generally, however, relatively local areas of falling roof were encoun-tered, usually limited to a 10-20 shield span when appearing.Ten days were spent gathering respirable dust samples on the longwall panel. Mine Safety Appliance (MSA) sampling units equipped with 10-mm nylon cyclones, pre-weighed MSA PVC filters, and constant-flow DuPont pumps were used to obtain thesamples. The pumps were calibrated at a 2 liters-per-minute flow rate. The 10-mm cyclone was selected for classifying total dust into the desired respirable fraction in order to obtain ""legally defined"" respirable dust samples for detailed physical characterization."

Jan 1, 1988

By A. G. Pasamehmetoglu, N. Bolukbasi, O. Koncagul

A study has been undertaken to establish the relationships between the O&K wedge test cutting resistances and the geotechnical parameters of rock materials in the context of bucket-wheel excavator operation. Prediction equations were formed to estimate the cutting resistance from the geotechnical parameters by multiple regression analysis. The cone indentor index, uniaxial compressive strength and Shore hardness parameters have been found to be the most significant predictors

Sep 1, 1991

By J. R. Johanson

In recent years the procedures for functionally designing bulk storage bins and hoppers have evolved from qualitative guess and try methods to a quantative method based on theory and tests of the bulk solid to be stored. This quantative method, developed and implemented by Dr.'s A. W. Jenike and J. R. Johanson as with any new design, must prove its effectiveness and validity in the actual operation of the finished equipment. How accurate are the theoretical predictions? Is it possible to extrapolate from bench size tests on a small ample of the bulk solid to the full scale bin design? Can the theoretical designs be economically translated into working hardware? In this paper the answers to these questions are discussed in light of actual bin operations.

Jan 1, 1968

By David Oyler

Sonic travel time logging of exploration boreholes is routinely used in Australia to obtain estimates of coal mine roof rock strength. Because sonic velocity logs are relatively inexpensive and easy to obtain during exploration, the technique has provided Australian underground coal mines with an abundance of strength data for use in all aspects of ground control design. However, the technique depends upon reliable correlations between the unconfined compressive strength (UCS) and the sonic velocity. This paper describes research recently conducted by the National Institute for Occupational Safety and Health (NIOSH) aimed at developing a correlation for use by the U.S. mining industry. At three coreholes in Illinois, Pennsylvania, and southern West Virginia, sonic velocity logs were compared with point load tests for a broad range of coal measure rock types. For the entire data set, the relationship between UCS and sonic travel time is expressed by the following equation, where UCS is in psi and t is the travel time of the P-wave in microsec/ft. UCS = 468,000 x e-0.054t (1) The r-squared value for this equation is 0.87, indicating that a strong correlation between sonic travel time and UCS can be achieved with this technique. The paper also addresses the steps that are necessary to ensure that high-quality sonic logs are obtained for use in estimating UCS.

Jan 1, 2008

By R. Altindag

In rock cutting mechanics, the effects of the rock and coal brittleness on the efficiency of cutting bits are examined by many researchers. There is no universally accepted brittleness concept as a measure of cutting efficiency. The effect of the brittleness on rock cutting has not been completely explained. The aim of this study is to correlate the relationships between Specific Energy (SE) and brittleness concepts. The applicability of various brittleness measurement methods for rock cutting efficiency has been investigated. In this study, the raw data derived from previous experimental studies were used, and the relationships between SE and brittleness concepts were investigated. The two previously used brittleness concepts, which are named as B1 (the ratio of compressive strength to tensile strength) and B2 (the ratio of compressive strength minus tensile strength to compressive strength plus tensile strength), and a new introduced brittleness concept named B3 (the area under line in relation to compressive strength and tensile strength) were evaluated in this study. The relations among these brittleness concepts for rock cutting efficiency were established using regression analysis. There is no correlation found between the SE values and the brittleness of B1and B2values. But, the SE is strongly correlated with the brittleness of B3. It was seen that the suggested brittleness of B3concept could be used as an indicator in rock cutting efficiency analysis.

Jan 1, 2003

By Leah L. Naugle, H. G. Landau, H. H. Lowry

EVIDENCE has been accumulating in recent years, in part from the work of the Coal Research Laboratory, that coals belong to a family of natural polymers and that even in complex reactions the differences between coals are quantitative and not qualitative. This point of view leads to the expectation that if a series of coals were subjected to a closely controlled set of experimental conditions the results obtained should be related to the chemical analyses of the individual coals. The data accumulated over the past 10 years by the Bureau of Mines in its "Survey of Coke-, Gas-, and By-Product-Making Properties of American Coals," in what has come to be recognized as the Bureau of Mines-American Gas Association (BM-AGA) carbonization assay test,1-12 offer an unusual opportunity to check this conclusion. The present paper reports an analysis of the data on the first go coals and coal blends-including coals numbered I to 55b, inclusive -which have been carbonized according to a standard procedure at intervals of 100°C. from 500° to 1100° in either or both 13 or I8-in. cylindrical retorts." In Table I are given the name of the seam from which the sample was obtained, the analytical data used, and the reference to the original publication of the Bureau of Mines. The coals range in fixed carbon from 46.2 to 79.0 per cent, in volatile matter from 15.4 to 41.3 per cent, in ash; from 2.1 to 15.9 per cent, in moisture from o.8 to 19.7 per cent, and in total sulphur from 0.40 to 4.44 per cent; therefore the entire gamut of bituminous coals is represented. The petrographic nature of the individual coals is not considered in the following analysis, although both "normal" bright coals and splint coals are included in the samples studied. For information on the petrography of the coals and for further information characterizing the coals the original papers should be consulted. Although the coals that are included extend over the whole range of bituminous coals, they do not cover this range entirely adequately. In particular, only 13 of the go coals have moisture contents greater than 3 per cent. This concentration at low moisture values means that the effect of moisture, which is an important factor, cannot be determined with as much certainty as would be desirable. All the coals were not tested at every temperature and in both retort sizes. Only the first 30 coals were tested at 1100°, and only about 50 at the other temperatures, except at 900°, where nearly all of them were included. In the accompanying tables the actual number of observations entering into each correlation is given. In this study equations are given for calculating analyses, yields, and properties of coke and by-products from the coal analyses. To decide whether these equations are satisfactory it is necessary to know the accuracy with which these quantities were measured in the assay tests.

Jan 1, 1941

By Roy J. Helfinstine

One of the most urgent needs in the field of coal combustion is the ability to predict the performance of a coal from knowledge gained from small-scale tests. Numerous types of analyses and tests are conducted on coal, including the proximate and ultimate analyses, heating value, varieties of sulphur, ash analysis, ash fusion temperatures, free swelling index, petrographic analysis, and Gieseler plasticity. The Illinois Geological Survey has made an intensive study of the value of these tests for judging the performance characteristics of the coal as actually utilized. To date, three reports 1 2 3 have been is- sued, and another is being prepared. The present paper briefly summarizes some of the results found in the studies.

Jan 1, 1949