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CONTENTS PAGE SOUTHWARD, GLENN B.-Coal Mining by the V System. Discussed by Glenn B. Southward, Howard N. Eavenson, Edward B. Raiguel, Thomas de Venny, J.. J. Rutledge, Graham Bright 1 ARMS, RAY W.-Dry Cleaning of Coal. Discussed by Ray W. Arms, S. A. Taylor, Howard N. Eavenson, W. R. Crane, F. F. Jorgenson, G. R. Delamater. 6 EAVENSON, HOWARD N.-Data About Labor Employed in Various Bituminous Coal Mines. Discussed by Howard N. Eavenson, George H. Ashley, E. A. Holbrook, S. A. Taylor, R. V. Norris 14 Coal Mining by the V System Discussion of the paper of GLENN B. SOUTHWARD presented at the New York Meeting, February, 1924, and issued as Paper No. 1300-C, with MINING AND METALLURGY, February, 1924. MEMBER.-How do you pay your men for loading? GLENN B. SOUTHWARD.-Everything is on time basis. MEMBER.-How many men do you have loading across one of the diagonal faces? GLENN B. SOUTHWARD.-From four to five, depending on the length of the face. Our loaders are so arranged that each will give about twenty-five tons per loader a day. MEMBER.-How much timber do you use? GLENN B. SOUTHWARD.-A little more than will be used in room-and-pillar work, but not a great deal more. We have not attempted to recover much of our timber. MEMBER.-IS the mine union or non-union? GLENN B. SOUTHWARD.-Non-union. HOWARD N. EAVENSON, Pittsburgh, Pa.-I went .through that mine some weeks ago, and think that the author has been very conservative in his statements about the amount of loadings, etc. EDWARD B. RAIGUEL, Huntington, W. Va. (written discussion).¬Page 7 shows 60 men employed in day and night shifts, inside the mine, producing 750 tons per day. Let us reduce these figures to a man-hour basis, for comparison with Mr. Eavenson's figures on West Virginia mines, as follows:

Jan 6, 1924

By Jun-Yan Chen

Ground control problems in sublevel caving become evident as the rock pressure increases with depth. Recently, a finite element analysis of the stability problem of the sublevel caving method was completed by the author. This paper summarizes the results of stress analysis in sublevel extraction drifts under different field stress conditions by using linear elastic and nonlinear elastic-plastic finite element modeling techniques. A critical stress concentration will occur in the uppermost sublevel drifts beneath the caved area or blasted ore area. During the blasting and drawing cycle, a tensile and shear failure condition could develop in the center extraction drift when it would be mined last. Under a high horizontal stress field condition, almost all tensile stress in the back of the extraction drifts will be eliminated and only slight yield can be seen in the floor of the extraction drifts. Compared to the cases under the stress field where vertical stress is the dominant factor, the total yielding zone will be greatly reduced because of an in- creasing horizontal stress field with depth. However, it is predicted that the center of each ore column side will experience excessive shear stress that probably will result in ore failure. The two major conclusions drawn from this study to improve the overall stability of sublevel caving are: (1) the drift width must be carefully controlled and an appropriate stoping sequence selected; and (2) the sublevel caving method can be used in deep min

Jan 1, 1983

By J. A. Herbst

During the last decade it has been established that conventional mineral-processing control strategies based on classical control theory result in significant increases in plant throughput and operating-cost savings. It has, however, also been recognized that conventional strategies have important limitations for complex multivariable mineral-processing systems. These limitations center around the fact that single-input/single- output control linkings often result in highly undesirable interactions between controllers. During the last few years new and promising approaches to solving this problem have emerged. These approaches are based on the use of on-line dynamic models to make predictions which are useful for control decision-making. This paper presents a brief summary of the state-of-the-art for mineral-processing control in 1984. This summary is followed by a review of recent developments in model-based control strategies including those in optimal control, self- tuning regulators and decoupling control. Expected trends for the future in the control of mineral-processing operations are discussed.

Jan 1, 1984

By John J. Secretary Egan

The present list of problems relating to the physical chemistry of steelmaking has been prepared by the Committee on the Physical Chemistry of Steelmaking, from answers to a questionnaire submitted to a number of metallurgists engaged in both industrial and educational work throughout the United States. The purpose of the project is to make available to research laboratories a list of problems, all reduced to their simplest terms, the solution of which would aid in creating a better understanding of the steelmaking process. It is not intended to restrict the problems to practical steelmaking. The list also includes the study of the properties, and their correlation, as well as the physical and chemical reactions, of all substances that occur or that may be in any way associated with steelmaking operations, such as metallic substances, refractories, nonmetallic inclusions, and the constituents of slags. Many of the problems can be carried out in university or other research laboratories. Others may be most successfully attacked by cooperation of the research men with the operating personnel. It is the Committee's earnest wish that this cooperation be fostered. It is requested that investigators who are working on any of the problems listed and who anticipate future publication of their results, notify the Secretary of the Committee that such investigation is in progress. Suggested additions to the present list are also requested. The Committee is undertaking to act as a clearing house for information regarding the topics in this field that are being actually studied. Interested persons are invited to correspond with the Secretary. I. Data involved in the state of equilibrium for the various systems (laboratory work, almost entirely). A. Specific heats, heats of formation, entropies and free energies of various PURE ELEMENTS OR COMPOUNDS; ALSO CERTAIN TYPICAL SLAGS AND REFRACTORIES I. Determination of specific heats and entropies of oxides, sulphides, nitrides, etc, over a wide temperature range. 2. Determination of free energies of oxides, sulphides, nitrides, etc., over a wide temperature range. 3. Determination of the heats of formation of the oxides, sulphides, nitrides, etc. 4. Determination of the thermodynamic properties of the more important mineral-ogical constituents of the basic open-hearth slags such as calcium silicates, calcium phosphates, calcium ferrites, manganese silicates, FeO and Fe2O3. 5. Determination of the specific heats of open-hearth slags, including liquid silicates, if possible.

Jan 1, 1941

THE paper on "Specific Efficiency of the Blast Furnace" by Richard Franchot, which was pub-lished in the September issue of MINING AND METALLURGY, was presented for discussion at the Pitts-burgh meeting. The session opened with a discussion among S. P. Kinney, Mr. Franchot, and J. N. Reese as to the methods and results in sampling for cyanides in the blast furnace. This is covered in detail in writ-ten discussion below. T. T. Read objected to the use of the term specific efficiency as likely to be confusing. The blast furnace has to perform the function of reducing Fe, 03 to Fe as well as that of fusing the metal and, since the reduc-tion of Fe, 0? involves a CO equilibrium, it seems mis-leading to calculate efficiency on the basis of burning the , all carbon to CO? since it is not possible. Mr. Franchot replied that he used the term in the sense defined by Richards in his "Metallurgical Calculations;" but a subsequent search failed to reveal the term in Richards, who says (page 245, 1st edition): The practical conclusion is that a blast furnace generates in itself not much over 40 per cent of the calorific power of the fuel used, and rejects nearly 60 per cent; by using part of the waste gases to heat the blast, however, some of this rejected heat, to an amount representing net 5 to 10 per cent of the calorific power of the fuel used, is returned to and injected bodily into the furnace, thus rendering available for the purpose of running the furnace about 50 per cent of the calorific power of the fuel as a maximum. The efficiency with which the furnace applies this 50 per cent usefully to the objects of the reducing and smelting is another question for investigation.

Jan 2, 1927

By C. Norman Cochran, James L. Brandt

ALTHOUGH gas in aluminum and its effect on aluminum products have been the subject of a number of papers, not many quantitative determinations of the hydrogen content of solid aluminum and its alloys have been recorded in the literature. For solid aluminum samples, four investigators have reported hydrogen contents which appear reasonable compared with the hydrogen solubility of 0.7 ml per 100 g, STP, in molten aluminum at 660°C established by Ransley and Neufeld' and verified by Opie and Grant' and Ransley and Talbot. Sloman," who used a vacuum fusion procedure, reported the hydrogen content of some high purity aluminum as 0.66 ml per 100 g, STP. Griffith and Mallett, employing the tin fusion method, reported the internal hydrogen content of six different aluminum alloys as ranging from less than 0.1 ml per 100 g, STP, for 1100 alloy to 0.7 ml per 100 g, STP, for 4043 alloy (previously 43S, a 5 pct Si alloy). Eborall and Ransley," using a solid extraction of the gases at 600°C, reported hydrogen contents ranging from 0.1 ml per 100 g, STP, to 1 ml per 100 g, STP. Ransley and Talbot reported that several thousand analyses on 99.2 pct and higher purity aluminum as well as Duralumin type alloys indicated hydrogen contents ranging from 0.1 ml per 100 g, STP, to 0.5 ml per 100 g, STP.

Jan 1, 1957

By N. A. Gokcen, John Chipman

D. C. Hilty (Union Carbide and Carbon Research Laboratories, Niagara Falls, N. Y.)—This paper is a very nicely detailed analysis of a difficult problem. I would like to point out that the results that Mr. Crafts and I published a few years ago had no reference to activity, or anything else of a similar nature; our results were strictly empirical. It is quite gratifying that we now have a case where results involving activity coefficients and results derived from direct observations on actual steel melts are practically identical. When two different laboratories, working from two entirely different approaches, come out with results in such good agreement in their major significance, that is an achievement. It is something that was not possible 15 or 20 years ago. There is one question I would like to ask Dr. Chip-man. It has to do with a very minor point of disagreement in these results. When we reported the kink in the Si-O solubility curve I think you may recall that it came at the different temperature levels at about the order of 0.015 to 0.03 pct 0 and 0.03 to 0.07 pct Si—we also pointed out that we had difficulty in obtaining data at that level, although we finally did get some. I note in going through the data for the present paper, that there are no samples in those particular silicon and oxygen ranges. I wonder if that was purely accidental or was there a reason for it. D. E. Babcock (Republic Steel Corp., Youngstown, Ohio)—Mr. Hilty, do you have any explanation for that discrepancy between Dr. Chipman's curve and your own Mr. Hilty—Our explanation for it at that time was that for some reason our system probably was not in true equilibrium with SiO, that is, in equilibrium with the silica crucible at that level. We did observe, however, that that was the level at which both the metal and the slag became saturated with SiO,. On the average, in studying inclusion formation in small ingots permitted to solidify normally from the molten state, we observed pure silica inclusions at silicon contents over about 0.05 pct and FeO type inclusions at silicon

Jan 1, 1953

By C Gunther

The classification here used is one of convenience only; it is not intended to include all known types of ore deposits. The characteristic features of the several well-marked types of primary mineralizations are described without reference to the ultimate source of their metals. The minerals of many deposits of obscure origin were probably introduced through fissures that are now healed, or are due to the migration of metals from such deposits. It is not within the scope of this book to enter into a general discussion of the genesis of ore deposits but, in view of the progress being made in our comprehension of the conditions under which ore deposits were formed, mention should be made of recent work. J. E. Spurr's two volumes, "The Ore Magmas," are recommended as crystallizing the views of those who are inclined to ascribe the origin of most ore deposits to a differential precipitation from magmatic rock masses and to the migration and precipitation of the viscous, liquid or gaseous exhalations from those masses. He has especially emphasized the role

Jan 1, 1932

NORTH AMERICA Number Members Alaska 31 Canada 302 Mexico 175 Newfoundland 3 United States Alabama 52 Arizona 131 Arkansas 9 California 723 Colorado 184 Connecticut 98 Delaware 19 District of Columbia 133 Florida 16 Georgia 6 Idaho 61 Illinois 241 Indiana 57 Iowa 7 Kansas 32 Kentucky 33

Jan 1, 1932

By Charles A. Ashburner

VERY little is known of the economical value of the cod-bells of the State of Texas. The first authentic statement in regard to their occurrence is that contained in the reports of the United States Exploratians for the Pacific Railroad, near the 32d parallel of latitude, published in 1863-55. Professor William P. Biake reports, "that a number of seams of bituininorls coal, varying in thickness from two to four feet, have been opened along the Brazos River, in Young County, about one hundred and fifty miles west of Fort Worth." Dr: Shurunrd also states, " that the claracteristic fossil fornis of the Carbeiferaas Era have been found with this coal, and considers the age of the formation established. Foesils obtained from the carboniteroas limestone remove all doubt of the age of these deposits."† In the spring of 1879, I was called upon by some Eastern capitalisets to make an examination of the Brazos coal-field, in order to obtain the thickness, extent., and value of the coal which could be mined and be'made merchantable fir stearn, heating, and metallurgical purposes. The demand for coal in this section of the country is great, and a fuel which in our Eastern markets might be considered of inferior quality, would here find a ready sale. It must be remernbered that the market value of a coal does not depen'd upon its absoltite purity, but upon its actual value in heat units which it is capable of prodwing. A poor coal which can be cheaply milled near the consuper, is infinitely more remunerative to a mining company than a superior coal whose cost to the consumer is greatly increased by high mining charges and railroad freights. The value of the Texan coals does not depend upon their purity but upon their low first cost and nearness to a market. A glance at a geological map of the United States, will show that the Brazos coal-field is the extreme southwestern extension of what may be called the Missourian, Fourth or Western, bituminous coal

Jan 1, 1881

By Myrick N. Bolles

The concentration of gold and silver in mattes low in copper, and the subsequent separation and recovery of either or both of these metals, is a question the satisfactory solution of which has long vexed metallurgists. It covers a broad and important department of metallurgical science and brings in its train a series of attendant problems continuing from the initial operations of concentration to the final recovery of " values."

Jan 1, 1905

By G. E. Pellissier, C. W. Mason

Tin has long been cited as offering a classic example of polymorphism, second in repute only to the allotropy of sulphul.. The notorious "tin disease," which Cohenl has studied so exhaustively in terms of the enantiotropic transformation of tetragonal white P tin to cubic gray a tin, has apparently encouraged the expectation that one or more additional polymorphic modifications might exist. The search for confirnmntion of this idea has, as might be anticipated, led to the accumulation of a body of miscellaneous evidence, much of which would probably never have been sought, or taken seriously even by its discoverers, but fur previous assumptions. The ball apparently was started rolling iii 1880 by Trechmann,2 who reported a new modification of tin (7 tin), which was brittle and found in "hard head," a highly arsenical, slaggy material produced in a certain stage of tin smelting. A mixture of two kinds of crystals was obtained from a Cornish tin furnace, and those thought to be 7 tin were studied crystallographically. The results indicated that these crystals were rhombic and of different density from the tetragonal tin prepared electrolytically by Miller. Their analysis was given as 98.7 per cent Sn, 1.3 per cent Fe, and traces of As, Sb, Bi and S. In 1881 von Foullon4 obtained similar crystals from a Bohemian tin furnace. Headden5 examined crystals similar to those of Trechmann and von Foullon and reported them to be monoclinic, but of analysis corresponding to stannous sulphide. Later, Stevanovic,~ by goniometric measurements, proved that these crystals of SnS were really rhombic. Groth7 pictures and describes both "rhombic tin" (Fig. 9, vol. 1) ant1 stannous sulphide (Fig. 84, vol. 1); their faces and angles correspond within the accuracy of measurement. Spencers in 1921 examined the above evidence critically; lie lound similar crystals from Cornish tin furnaces, proved them to be SnS, and even was able to analyze some of Trechmann's original specimens, finding high sulphur content. (Apparently Trechmann's analysis had been based on :L second lot of crystals, not described crystallographically.)

Jan 1, 1939

By D. T. MacRoberts

This paper embodies the results of theoretical studies concerning gas reservoirs, especially the effect of drilling programs of various intensities upon pressure depletion and ultimate recoveries. The primary objective has been to determine the net quantity of recoverable gas that could be obtained as a result of each additional well, in comparison with the gas . that might be secured from a single well ideally placed with respect to both acreage and geological structure. No method is yet known whereby the relative merits of intensive and sparse drilling can be compared experimentally; a reservoir must either be drilled closely or developed with wide spacing, but both programs cannot be conducted simultaneously. Hence, the analytical method seems to be the only approach to the problem. While the present state of our theoretical knowledge does not offer a precise solution to the problem of gas flow in sand bodies, it takes such appropriate cognizance of the limitations of the methods used as to restrict any answer obtained to the realm of engineering accuracy. In solving the problem for the average gas field, it was found that practically the same answers resulted as to pressure distribution, regardless of the size of the drainage radius, even though the latter was assumed to vary from a few feet as a minimum to that of the entire reservoir as a maximum. Such limits represent extreme possibilities; therefore, the practical conditions that are associated with normal development programs, in which wells are placed in the center of tracts varying in size from 40 to 640 acres, will of necessity result in less extreme variations than those indicated in the tables accompanying this paper. Stated more concisely, the amount of gas unrecovered at abandonment (of the particular field used for illustrative purposes) will lie somewhere between 4.6 and 6 per cent of the total original content, no matter how intensively the field is drilled. Gas reservoirs may be divided into two general types, those in which the energy is intrinsic, and those of which the energy is extrinsic. † The first type contains energy in the form of a compressed gas, which expands

Jan 1, 1938

By William J. Douglas, Jack T. Urie, Randall D. Metz

Production and financial planning for a new underground mine requires the coordination of equipment and coal reserves in a manner which assures that resources are utilized efficiently in achieving the target mine production. It is necessary to establish the productions which are attainable at the section level during different mining operations (advance, retreat, development) and under different mining conditions (roof, seam height, resource quality). It is also necessary to identify the interactions between production plans and ventilation equipment So that operations can be carried out without disruptions caused by inadequate ventilation. A set of computer models has been applied in planning a number of new coal, oil shale, and phosphate mines. A critical path production model, CPMINE, was used to determine face production levels for different cut sequences and seam heights, taking into account machine performance characteristics and operational availabilities under these varying conditions. The results formed a production data base for use in the mine sequencing model, MPLAN. This model processes each of the segments of a user-defined mine sequence network (strategy tree) taking into account the equipment available for mining operations and the previously determined production scheme devised by the mining engineer. Mine ventilation was analyzed with an expanded version of the Penn State MVS Ventilation model to determine fan and ventilation shaft requirements for supporting alternative production strategies. The MCOM mine cost analysis model has been applied to evaluate the economic performance of mining alternatives. The results of these studies were used to make decisions relating to equipment selection and acquisition schedules for both room-and-pillar and longwall mining systems. The approach and procedures which were used during these studies are described.

Jan 1, 1983

Jan 6, 1976

By H. J. Rahilly

MINE FIRES, in the Butte District, have been a source of trouble and expense for the past thirty years, for while the actual fire area in most of the mines has been comparatively small, the handling of the gas has generally been a much larger problem than the actual putting out of the fire. The chief causes of these fires have been: Defective electrical equipment, incendiarism or carelessness, and spontaneous combustion. While fires from the first two causes have been numerous, they have generally been discovered and extinguished before they became very serious. Spontaneous combustion has been the cause of most of the large fires. Sufficient heat has been generated by ground movement, high rock temperatures, and decomposition to set fire to inflammable materials (tarred ropes, canvas, dry timber, manure, and hay) left in the gobs some years ago. Also, the heat resulting from the oxidation of the fine broken sulfide ore is sometimes sufficient to set fire to the timbers. In 1906, a fire was discovered on the 1100-ft. level of the Minnie Healy mine about 400 ft. (122 m.) west of the Minnie Healy shaft, which presumably originated, in one of the upper levels, from spontaneous combustion. The fire was walled off by concrete bulkheads and a pillar of ground 100 ft. (30 m.) thick was left below and mining resumed underneath. During subsequent operations, this pillar became cracked and broken and the fire passed into the new workings. It travelled downward and spread rapidly until, in 1917, it had become necessary to wall off portions of the Tramway, Leonard, and West Colusa mines on the 1300, 1400, 1500, 1600, 1800, 1900, and 2000-ft. levels, and the top of the 2200-ft. raises were sealed. The fire area now consists roughly of a block 1000 by 1200 ft. and from the 600-ft. to the 2200-ft. level. This block is composed largely of a series of parallel northwest-southeast nearly vertical veins and stringers that form a large orebody, with no well-defined walls but badly fractured and faulted, and known locally as "Horsetail Ore." These veins, or orebodies, are mined by the square-set or the rill method.

Jan 2, 1922

By C. D. Broadbent

INTRODUCTION The slope stability research plan at Kennecott was developed to serve the specific needs of large, open pit mines; primarily those developed in faulted and highly-fractured intrusive deposits. The program emphasis is on applied research; being defined in this case as research into the engineering mechanics of discontinuous rock and into the related rock property survey and slope design techniques. The program has been developed in phases, with each phase organized to explore more thoroughly the most significant findings of previous work and to improve on techniques found to be applicable. The current work is based on principles developed early in the program and that show promise of having engineering and economic value. A brief summary of the conceptual principles of the program is given to put our current work in context. This is followed by a review of the two cooperative programs done with the U. S. Bureau of Mines. Most recent work is described and interpreted in terms of practical slope design. Although failure-free slopes are a desirable goal, it is recognized that some failures will occur when overall slope designs approach a calculated safety factor of one. A discussion of failure control research is therefore offered. BACKGROUND In 1965 Kennecott management specified that a slope stability technology must be used to achieve optimum development of ore resources. The subject was carefully explored and by 1960 it had been established that there was no technology readily applicable to open pit slope design. Therefore, in 1962, Kennecott Copper Corporation and the U. S. Bureau of Mines agreed upon a cooperative research program having the objective of developing a mine slope stability science. One of the first decisions made by the cooperating groups was that the research must be conducted primarily in the field and not in the unrealistic environments of a laboratory. Accordingly, the Kimbley Pit, an abandoned mine once operated by Kennecott's Nevada Mines Division in Nevada, was selected for the full-scale research. Fortunately, there was near-universal agreement on the basic stability parameters and thus on the areas to be investigated. These parameters were acknowledged to be: (1) anisotropy (generally due to faults or joints), (2) stress, and (3) water; in that order of importance.

Jan 1, 1972

Jan 1, 1961

By H. J. Struth

In these trying times of proration and low oil prices, it is decidedly necessary for all branches of the petroleum industry to accord full recognition to the economic phenomena that contribute to its varying state of welfare. Perhaps no other single factor has a more important bearing upon the general oil situation than the supply and demand of gasoline. Year after year, the records have shown that the degree of prosperity or depression accompanying the industry's developments has been to a large extent influenced by the degree of balance maintamed between the supply and demand of gasoline. More and more it is being realized within the industry that equilibrium between the supply and demand of gasoline forms the basic structure of crude and product market values and, consequently, the deciding factor in the financial results of the industry as a whole. The influence of the gasoline situation upon the market and financial structure of the petroleum industry was effectively demonstrated during 1930, when excess accumulation of gasoline undermined not only the refined oil market but the crude market as well. In fact, it was a top-heavy gasoline situation that defeated the realization of benefits that might have accrued from an otherwise favorable statistical position in the producing branch of the industry. Indicative of this is the fact that crude oil production was curtailed to the extent of 98,323,000 bbl. last year, while refinery runs to stills were maintained at an excessive rate until late in the year, creating an excess gasoline production of 6,663,000 bbl. above actual requirements. Nevertheless, the movement to curtail refinery operations during the closing months of the year prevented a far worse situation, although it came too late to turn the ebbing momentum of the general oil market. Despite the severe depression of the market values that accompanied 1930 developments, it can be said that the results attained during the closing months of the year, in the direction of production control, marked a decisive turn in the industry's economic affairs. In fact, a review of the oil situation from every angle points definitely to a better general understanding and recognition of the workings of the economic law of supply and demand. As a result, the year closed with crude production in

Jan 1, 1931

By F. E. Bash

About three years ago, the writer presented a paper1 on the rate of heating and cooling of a 24-in. round ingot. The present paper deals with work done on larger ingots at the plant of the Allis Chalmers Mfg. Co., Milwaukee, Wis., in August, 1919. Sufficient data on ingots of all sizes were desired to enable one to calculate in advance the rate at which any ingot could be raised to a forging temperature without injury to the steel, determining also the temperature gradient between different sections of the ingot and the length of time necessary to heat to the center. This has now been experimentally determined for 24-in. and 45-in. ignots by the writer and for a 18-in. cube by E. F. Law.2 J. F. Harper has also made tests on heat-treating temperatures on 30-in, ingots; which data are included in this paper. No attempt is made here to work out a formula for the heat penetration of steel, for too many factors are involved concerning which we have not sufficient information, as for instance, the specific heat of steel up to 2300' F. It is hoped that eventually a set of formulas will be developed so that one may calculate maximum allowable temperature differences within an ingot for any particular kind of steel and the rate of absorption of heat and temperature gradient within the ingot for a definite temperature head. EXPEEIMENTAL INGOT The ingot tested was 45 in. in diameter, having been forged into the shape shown in Fig. 1 from 54 in. diameter. Seven -in. holes were

Jan 1, 1923