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By W. G. Pariseau

A two-dimensional finite element program has been modified and extended to account for some of the rock mechanics complexities associated with single entry development of longwall coal mine panels. Program capability includes arbitrary assignment of element properties without regard to element ordering, anisotropic elastic, plastic and brittle rock properties that may be time dependent (aging), arbitrary mining sequences and provision for the effects of artificial support on the adjacent strata. Failure is according to an extended von Mises criterion that may be linear or quadratic in form; flow rules are obtained from the yield function taken as the plastic potential, but brittle behavior is treated as a discontinuous process of material properties change with deformation. In either case the extent of failure is calculated from the external boundary conditions. Application of the program to essentially two-dimensional problems resulted in lose agreement between calculated displacements and field measurements in the double entry system. Bleeder entries were stable in one locality and not in another. Artificial support had little influence on stability.

Jan 1, 1978

By T. Binnert Haites

INTRODUCTION NUMEROUS examples of troubled zones, interfering with the normal development of coal seams, have been cited in the literature. From a geological point of view they can be subdivided into structural and sedimentary troubles. Of the latter type, wash-outs are usually the most bothersome. Some years ago, A. A. Thiadens and the author arrived at the conclusion that they represent fossil river-beds. A method of predicting the course of these rivers was developed, which has been successfully applied in the Netherlands coal measures, and more recently by P. Stassen in some of the Belgian coalfields and by the author in the Sydney coalfield. The Sydney coalfield has long .drawn the attention of geologists, and three main periods of systematic geological research may be distinguished. The first period, 1872-1900, is covered by the studies of Ch. Robb and H. Fletcher (32, 10-13) (1). Their detailed sections of the cliffs have lost nothing in value, and are frequently consulted today.

Jan 1, 1951

By Anton Gronningsater

MR. J. R. GORDON: The authors are to be congratulated for their excellent papers on Copper-Nickel Matte Converting. Mr. Drummond's paper contains the results of a thorough and exhaustive study of a series of converter charges. Mr. Gronningsater has presented convincing arguments in favour of his claim that the converter has been neglected as a smelting machine for ore. Some of us may not be inclined to agree with his conclusions. Converting, like most metallurgical operations, is a compromise between an ideal and a practical operation. If it were possible for one to neglect entirely the matter of converter linings, I believe we would all agree that the proper flux for matte in a converter would be pure quartz. Under such ideal conditions, one would, if proper temperature were maintained, make the smallest quantity of slag containing a minimum of magnetite. Converter slags are notorious for their high metal content and must always be subjected to a further cleaning treatment before being discarded. For that reason, the tonnage of converter slag produced should be minimized. If norite is used as a converter flux, then the tonnage of converter slag would be greatly increased if the silica content is maintained at 27 per cent or higher. I cannot agree with Mr. Gronningsater's suggestion that, in con¬sidering a converter flux, the sum of the silica, alumina, alkaline-earths, and alkalis should be considered as being of value. The alkalis and alkaline-earth contents of the flux will replace iron in the silicates formed and tend to increase the viscosity of the slags. However, if the converter is to be used as a smelting machine, it will be necessary to drop the silica content of the converter slag in order to avoid production of excessive slag tonnages.

Jan 1, 1942

By W. W. Fowkes

The Federal Bureau of Mines examined a low-temperature tar obtained from a small-scale commercial unit for carbonizing North Dakota lignite for products that might be important to the economic processing of the tar. Tie tar may be divided into three distinct parts: (1) Tar acids, 45 volume-percent; (2) tar bases, 1 volume percent; and (3) neutral compounds, 54 volume-percent. It has a boiling range of approximately 150° to 380° C. (the decomposition temperature) and yields 18 weight-percent as hard pitch. The tar distillate up to 365° C. may be separated as: (1) Tar acids, 48 volume-percent; (2) tar bases, 1 volume-percent; and (3) hydrocarbons, 51 volume-percent. The tar-acid distillate, boiling to approximately 265° C., was characterized in some detail; the neutral fractions and the tar bases were less thoroughly examined. In general, as might be expected of a primary low-temperature tar, the lower boiling fractions are less in quantity compared with the usual high-temperature tar. The homologous series of each major class appears to be rather complete, although some components are present in very small amounts. The tar is quite unstable thermally, and might be more conveniently processed by extraction methods rather than by distillation procedures. The neutral fraction of the tar is highly aromatic, and might be considered as base stock for the production of liquid fuels.

Jan 1, 1961

By S. K. Kawatra

It is common in coal-cleaning operations to produce a fine waste stream which contains a considerable amount of coal, but which is not economical to recover both because it is mixed with large amounts of difficult-to-remove clay slimes, and because the fines are often heavily oxidized. Conventional froth flotation machines cannot produce an acceptable product from such material in a single stage of flotation, and even flotation columns often have difficulty cleaning this type of feed. A new type of flotation column was designed specifically to deal with these problems, and was installed and tested in a coal-cleaning plant in Ohio. The feed coal contained 39.8% ash as fine clay, and 2.83% total sulfur, and was 80% passing 176 micrometers. The coal was a thickener product which had oxidized for some time, and was very difficult to float. However, using the new column it was possible to recover up to 85% of the calorific value in a product containing less than 11% ash, and up to 60% of the calorific value in a product of less that 8% ash. The bulk of the pyritic sulfur was rejected from the coal as well. Multistage flotation tests showed that the flotation column was able, in a single stage, to produce the best froth flotation product that it was possible to recover from this coal.

Jan 1, 1994

By Keith K. Griffiths

Computers are a valuable tool to the aggregate industry and should not be overlooked. The selection of proper mechanical components is necessary. Merely the addition of a computer to operate a mechanical system will not guarantee that the system will work. Material delivery by rail or truck for stock-piling and intra-plant material transfer can be accurately supervised by automation with simplified controls for the layman to use. There are mechanical problems that occur in material blending and load-out systems when such a system is automated. Such things as material flow, bridging, stockpiling methods, overloading of equipment and safety must be considered. How these problems can be overcome by proper selection of compatible mechanical and computer equipment will be discussed. Also, there are many individual material circuits in a plant that can be computerized at a nominal cost. This type of computer installation will not necessarily result in increased production, but it will produce greater efficiency in manpower. These small computers, binary counters, memory circuits and other devices and their application to the aggregate industry will also be presented. A careful evaluation of the mechanical and computer inter-relationship by someone understanding both "Rocks and Electronics" is essential to proper handling of material by computers. Computers for the mining industry may be either digital or analog computers. Unless the computer is to control some type of chemical process, such as a cement plant, the, analog computer is not required and the digital computer' will be quite adequate and less expensive.

Jan 1, 1967

By H. Marquis

This paper is concerned with an analysis of a number of failures of large-size, hypervelocity light gas gun chambers and barrels. A brief description of the light gas gun principle and of the various types of guns is first given. The failures and the investigations carried out are then described in detail, with the failures divided into two groups. The first group comprises those failures caused by certain conditions to which the guns may be submitted, and includes, for example, severe local heating of the bore surface causing hardening and cracking of the steel. These conditions were accidental and steps were taken to prevent them. The remaining failures were due to faults in the material or in the heat-treatment, manufacturing or assembling procedures. Specific problems, such as hydrogen embrittlement, and the use of high strength gun barrels above their ductile-brittle transition temperature by preheating prior to firing, are briefly considered. Some interesting observations are also presented on the use of surface markings, and angles of fracture of large fragments, as an

Jan 1, 1962

By Yasuhiro Konishi

Hydrolytic stripping is the process in which metal ions are simultaneously stripped from a loaded cation-exchange solvent extractant and precipitated as oxides or hydroxides. Hydrolytic stripping is usually effected by contacting the loaded organic phase with water at elevated temperatures. The possibility of using hydrolytic stripping to prepare ceramic powders with controlled size and morphology is now being evaluated for different systems, using carboxylic acid extractants. As part of this work, mathematical models were developed to describe the kinetics of nucleation and growth of nickel ferrite particles. This paper describes the development of the models, along with estimation of key parameters appearing in the rate equations from experimental data.

Jan 1, 1990

By Jesús Guerra, Edgard Atencia, Edwin Cereceda

En la actualidad la minería se sitúa en un escenario donde se tiene recursos con menor contenido de ley, sumado a la actual coyuntura del país con la desaceleración económica y la inflación. Frente a ello es de vital importancia buscar oportunidades de mejora que permitan que sea rentable el minado mediante la optimización del proceso con el objetivo de reducir el costo operativo. En particular la mediana minería aporta con una producción de Cu del 12.5% del total nacional, lo que se traduce en 304,828 Ton finas /año de Cu.

Sep 29, 2023

By Vinod K. Sikka, René Cooper

"Cohoes, New York 12047 Intermetallics are an attractive class of advanced materials. The aluminide intermetallics offer advantages including: (1) lower density, (2) oxidation resistance, (3) carburization resistance, and (4) interesting mechanical properties because of their ordered crystal structure. Even though the attractive properties of the aluminides and other intermetallics have been known for nearly four decades, their practical applications have not been developed for two reasons: (1) the poor ductility (in some cases, both ambient and high temperatures) and (2) the lack of processability into meaningful components. Recent advances such as ductilization of Ni3Al by small additions of boron and the knowledge that environmental effects are the major cause of poor ductility in Fe3Al and FeAl systems have brought the intelmetallics into the forefront of research and their commercial applications. This paper has described a method for melting Ni3AI-based alloys that successfully utilize the exotherrn for the formation of NiAl from the elemental materials. The reaction-synthesis method has also been utilized for the production of NiAI and NiAI-based alloy powders from the elemental powders. The reaction-synthesized powders of NiAI and NiAI-based alloys were consolidated by hot extrusion and evaluated for tensile properties over a temperature range from room temperature to 1050ºC. The powder-processing conditions have been found to have more influence on the ductile-to-brittle transition temperature of NiAI than the powder-production method.IntroductionIntermetallics are an attractive class of advanced materials [1-11]. The alum in ide interrnetallics offer advantages including: (1) lower density, (2) oxidation resistance, (3) carburization resistance, and (4) interesting mechanical properties because of their ordered crystal structure. Even though the attractive properties of the aluminides and other interrnetallics have been known for nearly four decades, their practical applications have not been developed for two reasons: (I) the poor ductility (in some cases, both ambient and high temperatures) and (2) the lack of processability into meaningful components. Recent advances such as ductilization of Ni3Al by small additions of boron and the knowledge that environmental effects are the major cause of poor ductility in Fe3Al and FeAl systems have brought the intermetallics into the forefront of research and their commercial applications. The paper will briefly review the processing techniques being pursued for the commercial applications of Ni3Al-based intermetallics. The major emphasis of the paper will deal with synthesis of Ni3Al and NiAI intelmetallics."

Jan 1, 1994

By Leslie S. Weldon

THE Lake Shore mine has been developed by two vertical shafts, with level intervals at 200 feet to the 2200 level and at 125 feet below this horizon. A main cross-cut joins the two shafts on all levels to the bottom of No. 3 shaft, and opening into these cross-cuts are the ore passes and sand passes, which are completed from surface To the 4450 level. In the west part of the mine, additional connections have been made between No. 1 and No. 2 veins, through which the major part of the ore from No. 2 vein west is routed to drifts in No. 1 vein. With the lesser amount of stoping on No. 1 vein, this arrangement permits better haulage to be maintained. The ore passes are driven at 50 degrees from the ends of short cross-cuts off the main ones and are broken through to the levels above at the mouths of the short cross-cuts, to allow for dumping on each level. The passes are controlled at each level by ball-and-chain gates and deliver to crushers and thence to loading pockets, shown in Figure 1. That system is quite flexible in that it is possible to by-pass the crushers at any station and load from either shaft at a number of different pockets. The sand passes are driven from the main cross-cuts at the same inclination as, and parallel to, the ore passes. Each is equipped with a chute and dump hole, so that waste or sand fill may be loaded or dumped at each level. A transfer door, hinged on the bottom, is installed opposite the chute for by-passing fill from one level to the next, and in the closed position protects the opening at the top of the pass. The dump hole situated beside the transfer door is protected by a grizzly with 10-inch spaces. Waste rock may be withdrawn from the system through No. 3 shaft loading pocket at the 2950 level to a waste bin on surface. Levels are developed by drifts in No. 1 and No. 2 veins for their entire lengths. Subsidiary breaks are followed at a later date, when full information has been obtained by exploration, and a considerable amount of development by sub-drifts is carried out in the upper part of the mine, particularly in more or less erratic sections of No. 1 vein.

Jan 1, 1936

By Arthur L. Crawford, R. E. Head, Fred E. Thackwell, A. Lee Christensen

"The data in this report are the result of a detailed, microscopic study of composite samples of mill products collected over a 14 day period. The samples were collected and assembled under the direction of W. R. Lindsay, superintendent of the Anyox plant, and are fairly representative of the heads, middlings, tailings, and products peculiar to the scheme of concentration practiced at Anyox in 1930.The work was done in the Cooperative Microscopic Laboratory at Salt Lake City, Utah. This laboratory was equipped by the mine and mill operators of the Salt Lake Valley and functioned under a cooperative agreement between the United States Bureau of Mines the University of Utah. This is the fourth of a series of papers 6/ dealing with a microscopic study of mill products."

Oct 1, 1935

By D. Bienstock

A high-B.t.u, gas can be synthesized by the catalytic methanation of a mixture of 2.5 to 3 parts of hydrogen to 1 part of carbon monoxide, obtained in the gasification of coal, using a steel catalyst followed by Raney nickel in a hot-gas-recycle system. Conversion of 99 percent of the H2+CO yields a fuel gas with a heating value of 983 to 1130 B.t.u. per cubic foot containing 78 to 96 percent methane, no carbon monoxide, and very small amounts of unsaturated hydrocarbons. With the steel catalyst alone, conversions were 85 to 90 percent, giving a fuel gas of 810 to 868 B.t.u, per cubic foot, or 847 to 975 B.t.u. on a C02-free basis. INTRODUCTION In 1948 the U.S, marketed production of natural gas was 5.15 trillion cubic feet; by 1958 it had reached 11.0 trillion cubic feet, a rate of growth of 8 percent annually. 4 5 Although demand is expected to increase less rapidly, by 1966 it may reach 16 trillion cubic feet, based on an estimated 4.7 percent annual increase.6

Jan 1, 1961

By W. Dingley, G. R. Hoey

"AbstractWear of six types of grinding balls was compared with and without corrosion inhibition in grinding Ni-Cu sulphide and hematite ores in laboratory ball mills. Forged steel balls (Rc 60 to 65) and three types of white cast iron balls (Rc 50 to 65) were susceptible to corrosive wear and two types of stainless steel balls [AISI Type 440C (Rc 65) and AISI Type 302 is; 35)] were relatively immune. The relative wear rates of the five types of hard balls (Rc 50 to 65) were dependent on the corrosivity of the ore. Ranking of the hard balls with respect to wear resistance was consistent for the sulphide and hematite ores in the presence of corrosion inhibition, whereas their ranking was different for the two ores in the absence of inhibition.The electrochemical potential of the grinding balls was measured during grinding and was found to be a useful measurement for assessing the susceptibility of an alloy to corrosive wear. Reduction of ball wear for forged steel and white cast irons with corrosion inhibition was concomitant with a shift of ball potential to less active values. Ball potentials in the presence of inhibition were indicative of non-corroding metal surfaces.IntroductionA PREVIOUS STUDY by the authors (1) showed that corrosion inhibitors - sodium nitrite, sodium chromate and sodium metasilicate - reduced wear of forged steel grinding balls by up to 49% in grinding Ni-Cu sulphide ore. Although the mechanism of wear reduction was not elucidated, it was concluded that corrosion must play a significant role in the wear of grinding media. Remark and Wick (2) of Battelle Pacific Northwest Laboratories have also evaluated corrosion inhibitors for the reduction of metal wear using abrasive and n on- abrasive te sting procedures. Their research was sponsored by 16 companies throughout the world. Preliminary results indicated that anodic inhibitors prevent from one-fourth to one-half of the loss due to corrosion."

Jan 1, 1977

By B. W. Stunkard

Hibbing Taconite Company is located by the cities of Hibbing and chisholm near the center of the Mesabi Range, approximately 169 km (105 miles) from the Canadian Border. The plant site is equidistant from these two communities, about 6.4 km (4 miles) from each. A 169 km (105 mile) railroad connects us with the port of Superior, Wisconsin, where the pellet production is loaded into lake carriers for lower lakes destinations. Immediately to the south of the mine area is the world famous Hull- Rust-Mahoning Mine which produced more than 700 000 000 million tons of red ore between the years 1893 and 1973.

Jan 1, 1979

By W. K. Tolley

The Bureau of Mines is testing super critical fluids as solvents to selectively extract valuable components from complex matrices. Materials recovered during supercritical fluid extraction are often highly purified. Using laboratory apparatus designed specifically for supercritical fluid research, Bureau re-searchers have measured the solubility of titanium tetrachloride (TiCI4) in supercritical, liquid, and gaseous carbon dioxide (C02), CO2, a commonly used supercritical fluid, is inert, inexpensive, and nontoxic. Supercritical CO2 formed a single phase with TiCl4 at 45° C and 1,500 psig. When the solution was heated at constant pressure beyond 55° C, TiCl4 precipitated from the fluid. Results showed that TiCl4 solubility in supercritical CO2 is not controlled by the vapor pressure of the solute.

Jan 1, 1989

By Li Shibo, C. Halls

The compositions of olivine, pyroxene and chromite from the Proterozoic ultramafic complex are analagous to those of cumulate ultramafic rocks of tholeiitic origin, suggesting that the parent magma may have been tholeiitic rather than komatiitic. The complex contains economically significant Ni-Cu sulphide mineralisation. The high sulphide/silicate ratio is best explained in terms of the segregation of sulphides from a large volume of magma, of which all but the ultramafic cumulate fraction has since been eroded. Platinum-group minerals that have been identified include sperrylite, moncheite, native platinum, froodite, merenskyite, michenerite and Pd-rich pentlandite lamellae exsolved from pyrrhotite. They are characteristically found in close association with chalcopyrite, either along the contacts between hydrosilicate and sulphide grains or in cracks within pentlandite and chalcopyrite, which may also be intergrown with galena. Crystallisation from a Cu-rich residual magmatic liquid also enriched in Pt, Pd, As, Sb, Bi, Te, Zn and Pb is postulated.

Jan 12, 1993

By E. M. Tignor

As a part of the program of promoting the conservation and efficient utilization of petroleum, studies are being made by engineers of the Bureau of Mines on secondary oil-recovery projects throughout the United States. In furthering that aim, engineering data concerning the reservoirs, methods of stimulating the production of oil, and other pertinent facts are collected, studied, and subsequently published so that others may profit by the experience gained. This report presents the results of a study made by engineers of the Franklin, Pa., office of the Bureau of Mines of secondary oil-recovery operations in the Boggs field, Spencer district, Roane County, W. Va., whore natural gas is injected into the reservoir to stimulate the production of oil from a so-called stripper field. The Boggs field, like most others in the Appalachian region, is one in which the major part of the natural energy that caused oil to flow through the reservoir to the producing wells during the primary stage of oil production has been dissipated. For all practical purposes, most of the oil produced in the Appalachian region at the present time can be considered to be from stripper fields. Consequently, secondary recovery methods are being used extensively in the oil-producing areas of New York, Pennsylvania, West Virginia, Ohio, and Kentucky for recovering some of the oil that was not produced by primary production methods.

Jan 1, 1949

By A. Hultgren, G. Phragmén

Page Outline of Progress of Knowledge and Theories about Gas Evolution in Steel Ingots. and Its Influence on Crystallization and Segregation................ 134 Object of Present Investigation........................................... 148 Theoretical Discussion of Process of Solidification........................... 149 Gas Given Off from Rimming Steel during Solidification................... 149 Equilibrium Diagram of the Iron-carbon-oxygen Alloys................... 151 Solidification of Pure Iron-carbon-oxygen Alloys.......................... 157 Solidification when Carbon Monoxide Is Given Off at Constant Pressure... 157 Solidification when Gas Evolution Is Suppressed....................... 158 Schematic Application on Solidification of Rimming-steel Ingots.......... 159 Influence of Manganese, Sulphur and Phosphorus......................... 160 Experimental work..................................................... 162 Liquid Steel and the Mold Gas......................................... 162 Ingots Investigated and Methods Used.................................. 165 Ingot structure....................................................... 174 Structure of Rim Zone.............................................. 174 Structure of Core................................................... 181 Structures Obtained under Special Conditions of Freezing................ 182 Distribution of Metalloids............................................. 187 Other Observations Made............................................. 192 General Discussion of Solidification Process................................. 195 Condition of Liquid Steel before Casting................................. 195 Rimming Period...................................................... 202 Composition of Rim Zone............................................. 225 Freezing after Top Is Closed........................................... 228 Slag Inclusions and Ingot Scum........................................ 234 Reaction between Gas in Blowholes and Surrounding Solid Steel during Cooling 235 Summary.............................................................. 237 Appendix—Preparation and Etching of Ingot Sections....................... 238 References............................................................. 239 In 1934, Jernkontoret (The Swedish Ironmasters' Association) appointed a committee for the study of the structure of rimming-steel ingots and the various phenomena associated with their solidification. The members of the committee, including those who have joined it later, have been: I. Bohm, B. D. Enlund, B. Kalling, M. Tigerschiöld, S. Wohlfahrt and the authors. The present paper‡ is a somewhat

Jan 1, 1939

By G. Phragmén, A. Hultgren

Page Outline of Progress of Knowledge and Theories about Gas Evolution in Steel Ingots. and Its Influence on Crystallization and Segregation................ 134 Object of Present Investigation........................................... 148 Theoretical Discussion of Process of Solidification........................... 149 Gas Given Off from Rimming Steel during Solidification................... 149 Equilibrium Diagram of the Iron-carbon-oxygen Alloys................... 151 Solidification of Pure Iron-carbon-oxygen Alloys.......................... 157 Solidification when Carbon Monoxide Is Given Off at Constant Pressure... 157 Solidification when Gas Evolution Is Suppressed....................... 158 Schematic Application on Solidification of Rimming-steel Ingots.......... 159 Influence of Manganese, Sulphur and Phosphorus......................... 160 Experimental work..................................................... 162 Liquid Steel and the Mold Gas......................................... 162 Ingots Investigated and Methods Used.................................. 165 Ingot structure....................................................... 174 Structure of Rim Zone.............................................. 174 Structure of Core................................................... 181 Structures Obtained under Special Conditions of Freezing................ 182 Distribution of Metalloids............................................. 187 Other Observations Made............................................. 192 General Discussion of Solidification Process................................. 195 Condition of Liquid Steel before Casting................................. 195 Rimming Period...................................................... 202 Composition of Rim Zone............................................. 225 Freezing after Top Is Closed........................................... 228 Slag Inclusions and Ingot Scum........................................ 234 Reaction between Gas in Blowholes and Surrounding Solid Steel during Cooling 235 Summary.............................................................. 237 Appendix—Preparation and Etching of Ingot Sections....................... 238 References............................................................. 239 In 1934, Jernkontoret (The Swedish Ironmasters' Association) appointed a committee for the study of the structure of rimming-steel ingots and the various phenomena associated with their solidification. The members of the committee, including those who have joined it later, have been: I. Bohm, B. D. Enlund, B. Kalling, M. Tigerschiöld, S. Wohlfahrt and the authors. The present paper‡ is a somewhat

Jan 1, 1939