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By Michael J. Peacock

The Powhatan No. 4 Mine is located in southeastern Ohio along the Ohio River in Monroe County. The mine produces approximately 3.2 million tons of steam coal annually from the Pittsburgh No. 8 seam. The Pittsburgh No. 8 seam in this area dips to the southeast in varying amounts from 10-feet to 40-feet per mile. The seam is made up of a main bench coal (4' to 5f' ) containing several thin and variable partings and a rider ("roof") coal (0" to 18") which is separated from the main bench by a parting (0" to 18") that is reasonably consistent in occurrence and position. Strata overlying the seam varies from a bedded to nonbedded calcareous mudstone-claystone (6' to 12') in the north and east regions of the mine to a sandstone (Pittsburgh Sandstone C10' to 40'1 in the south and west regions. The Redstone Limestone (10' to 18' ) overlying the mudstone-claystone in the north and east thins and rises toward the area of sandstone deposition in the south and west. From its opening in April of 1971 until late 1981, primary roof support in the long-1 ived entries at Quarto Mining Company's Powhatan No. 4 Mine had been achieved with 8-foot and 10-foot. 518-inch mechanical roof bolts using a Single expansion shell. These bolts were installed so that the expansion shell achieved a competent anchorage in the limestone. However, as the mine developed westward, the limestone began to trend upward becoming inaccessible as an anchorage medium at the 8-foot and 10-foot horizons. Anchorage achieved in the underlying mudstone-claystone strata was failure-prone due to weathering (after exposure to air and moisture) and inconsistencies in the anchorage horizon, leading to an increase in the incidence of reportable roof falls at the mine. Responding to the threat to safety and productivity posed by the increase in roof falls. Mine Management through its Safety and Engineering Departments, sought solutions to the problem. In seeking a solution to the problem, the safest and en engineering groups examined the reportable roof falls to determine the cause of those failures. Their examination pinpointed two items which were found to be a common link in the majority of those falls; namely, anchor integrity and geologic trends. Analysis of the roof falls indicated that due to effects of air and moisture on the anchoraae zones in the mudstones and clay- itones, the integrity of the anchorage over time could not be maintained. Geologic trends noted included the upward trend of the -main limestone as mining progressed westward, inconsistencies in the amount of roof coal and draw slate in the immediate mine roof and increasing evidence of heavily slickensided immediate mine roof. In the absence of the protective barrier provided by the roof coal, the immediate strata and particularly the draw slate, is susceptible to deterioration due to the weathering effects of air and moisture and thus is prone to "eat out" around the roof bolts and cause roof falls. The presence of heavily slickensided roof creates a need for increased contact surface such as that provided by plank and header blocks to aid in holding up the roof and tends to make the behavior of such roof very unpredictable. Having determined the causes of the roof falls. Mine Management began to identify the kind of roof support which would best solve these problems, while at the same time providing the mine with a safe, cost effective and efficient roof support system. This paper will provide an analysis of how this decision was reached, the background that was researched to aid in forming the decision, the considerations that played key roles in the formulation of the plan, the mechanics of following through and implementing the new roof support system, and an assessment of the resultant gains in safety, productivity and improved costs derived from the implementation of the new roof support system.

Jan 1, 1986

By Mokka Rao, Arturo Valles, Jose Rodríguez

"This paper shows a mathematical model based on finite elements, applied to bottom poured shell ingots of C.V.G. Sidor Plant. The model was used as a strategy to determine the thermal effects that are produced when solidification conditions are modified without interfering with the production process. The modification consisted of placing a thermal insulator on top of mould.The results obtained by the model indicated that the solidification time increases with insulator on base of the mould. With these results a significant number of casts were run with and without insulator. Latter by means of a metallurgical analysis it was determinated that the ingots cast with insulator reduce the level of non-metallic inclusions and the presence of internal blistering in seamless pipes.IntroductionThe process of fabrication of seamless pipes in SIDOR involves various steps of processing, such as heating the ingots, fabrication of the prelaminated, fabrication of the bored pipe, lamination of the pipe by passing through the pellegrine mill, heating the pipe in a walking bean furnace and final calibration through a calibrator mill. The material utilized for producing these pipes is provided entirely from a electrical arc furnace and casted ingots, especifically, from the superintendence of bottom pouring.The process of bottom pouring consists of positioning twelve moulds of diameters 415, 480 or 505 mm over a plate of grey cast iron in which exists a system of communicating vessels. The ingots are distributed around a central duct from which the steel flows down and filling gradually, each one of the moulds (Fig. 1)."

Jan 1, 1997

In the estimation of recoverable resources, geostatistical techniques such as Multiple Indicator Kriging require a change of support correction to derive theoretical recoveries based on an assumed level of mining selectivity. The change of support models most widely used in practice entail model based generalized corrections either on a global or local basis. Examples include the affine and indirect lognormal methods. Change of support corrections derived empirically through short-scale conditional simulation realizations often show notable differences compared with theoretical corrections determined using model variogram parameters. The existing changes of support models are reviewed and an alternative method is proposed.

Jan 1, 1999

"The cleanliness and system evidenced in the accompanying photographs of the West Steward change-house will appeal to all mine operators. This design is the most efficient in use at Butte. It is the standard which will probably be used in Butte in all future construction and is the result of a long period of investigation and experimenting. It is important that such a structure be as nearly fire-proof as possible, because of the frequent fires originating within the lockers from matches, etc., in the men's clothes. The concrete floors permit the thorough washing of the building whenever necessary.The lockers are roomy and well ventilated. They are constructed of sheet steel and are warmed from below by steam pipes."

Jan 1, 1913

The scheme of rehabilitation of surface plant commenced in 1936, included the provision of improved and more hygienic changing and bathing facilities for the employees.At that time the Thompson's Shaft section of the British Mine was being prepared for a resumption of operations, and it was decided to repair and re-equip the existing building. Thus any new scheme adopted could be given a thorough trial, and the proved arrangement used as a basis for the contemplated new main changehouse on the North Section.Investigations were carried out to determine the most suitable arrangement for the Thompson's Shaft changehouse, to provide for a total of 120 men, with particular regard to the internal fittings and fixtures. Also, as the mining conditions were such that a large proportion of clothes worn underground by miners, etc., were wet by the end of the shift, the problem of drying these clothes in the availaole time from a man coming off shift to his commencing again some sixteen hours later was one of the most important to be dealt with.The changehouses in use on the North mine section of the lease were provided with racks around the walls for the men to hang their street clothes on, and a section was partitioned off to house the mine clothes and their drying facilities. The actual drying was carried out by means of hanging the wet clothes over racks between which ran pipe coils heated by means of hot water circulated from the hot water boiler supplying the showers.This method had proved to be far from satisfactory for several reasons, the main objections being:-

Jan 1, 1940

By R. A. Wagstaff

SINCE the time of the early Egyptians, the use of copper has been a boon to the life of most of the civilized world. Its use has been varied; in many connections, the art by which it attained its greatest usefulness has been lost. In this paper an endeavor will be made to take into consideration some of the many changes that have occurred during the last 40 years of copper-smelting operations. During that period the copper blast furnace has been almost forced out of existence by new methods of ore concentration-first, gravity concentration, and then flotation. These new methods of concentration introduced many new factors into the metallurgy of copper. The product was wet, it was fine and it was high grade. To overcome all these factors many changes have been necessary throughout the smelting agenda. New equipment has been necessary for transportation, unloading, sampling, bedding and moisturing in all smelting plants, especially the custom smelter. During the early days of "flotation," little was known about filtering or the use of an alkaline circuit; often the concentrate going to the smelter contained 20 to 25 per cent moisture. It is easy to imagine the difficulty arising with a product of this nature when it had to be shoveled by hand labor. To meet these conditions, mechanical unloading and sampling devices were soon developed. In many instances such good progress was made that actual costs for handling this unfavorable product were lower than those formerly incurred on the old product. Today most sampling of copper ores and concentrates is being done by mechanical sampling, pipe or augur sampling, or shovel sampling. Where concentrates are uniform in metal content, a great many of the plants now use pipe or augur sampling. For spotty ores, the old shovel sample with cone and quartering during the final stages is still in use. Where big tonnages are handled, mechanical sampling of concentrates is being done, with satisfactory results. To curtail slow and tedious cutting and mixing procedure, mechanical mixing boxes, splitters and cutters are used to cut down labor costs. MILLING As crude ores become scarcer, the use of milling operations increases. The few crude ores that are still smelted are used as fluxing types. To use these ores finer grinding has been found advantageous. This has made for better bedding and fluxing conditions, which in turn makes for faster smelting, lower fuel consumption and better metal recovery. The degree of fineness is more or less determined by the nature of the product. Most plants have set a standard of through ¾ -in. mesh screen for roaster- reverberatory smelting and through ¾ in. mesh screen for converter fluxes. For some refractory ores; even finer grinding has been found to be advantageous for good reverberatory smelting.

Jan 1, 1944

By A. K. Bakshi

Slurry rheology affects autogenous grinding performance by changing the rock's breakage characteristics. In this study pilot scale batch autogenous grinding was carried out to observe the effect of viscosity on the breakage characteristics of the rocks (the media), and on the overall specific energy consumption. Clay/fines content, and temperature of the initial charge, were varied to alter the viscosity of the slurry. Results showed that at higher slurry viscosity, rocks became more difficult to break, resulting in an overall increase in the specific energy consumption of the mill. Also, it was observed that viscosity had a significant effect on the amount of critical size material present in the grinding circuit, where the critical size material is the material which is too large to be effectively ground in the mill, and too fine to act as grinding media.

Jan 1, 1996

By A. Konya

"INTRODUCTION Underground Mining and Construction projects face several challenges unique to the underground environment compared to the surface environment. The goals of an effective blasting program are the development of a blast pattern that minimizes cost, maximizes face advance, and provides the desired fragmentation and face profile. In addition to these , mines must consider the very real operational problems that occur such as drill deviation, ground vibration, and deadpressing or sympathetic detonation of explosives. These operation problems lead to increased costs and decreased production in the mine, hurting the bottom line. Combined with these problems, underground blasts can be difficult to monitor and evaluate due to tight spaces, dust during the blast obscuring video, and the need to evacuate the immediate area with no clear line of sight to observe performance. This creates an environment which most mines know that blasting can be improved in their underground operations, yet most are hesitant to change due to fears of the shot freezing, misfires occurring, and questions about how to achieve a proper design. The explosive companies and shot service providers also offer limited assistance or knowledge in the underground blasting realm, unlike with surface blasting, leaving many underground operations in the dark. It is for these reasons that most underground operations are operating decades behind the current technologies and incurring significant costs, both real and hidden, from there blasting operations. This paper discusses philosophical changes to designs that need to be made for effective design and modifications of underground blast patterns to prevent deadpressing and precompression of modern explosive products (Konya, Konya, & Worsey, Modern Blasting Method Selection, 2017). While numerous different methods of underground heading development exist, there are two types that are used in a majority of mines around the world, these are the burn cut and the V-cut. The burn cut is a parallel cut that has holes that go straight into the face and are primarily used in smaller opening (due to ability to pull deep rounds with smaller room widths) and metal mines (helps in ore dilution and greater fragmentation). The V-Cut is a cut that uses angled drilling towards the center of the face (in the traditional method) and is primarily used in underground aggregate operations due to its cheap cost but larger fragmentation sizes and greater throw of the muckpile. This paper will discuss these two forms of cuts specifically with the understanding that modifications to these can be applied to other parallel and angled underground heading techniques. BURN CUT The burn cut is one of the older forms of underground blasting, where a part of the blast (burn) of a shot is heavily loaded with additional empty (relief) holes with the goal of smashing (aka burn) and pushing/blowing all the material in the burn out to provide relief for subsequent blastholes. The relief holes in the burn cut provide a parallel relief for the holes that are firing to break too creating a second plane of relief, however these are extremely small and can cause many problems if a design is improper."

Jan 1, 2018

Data released by the Commerce Department's Bureau of Economic Analysis show continued gradual change in the real GNP's rate of growth in 1984, which has eased from an annual growth rate of 10.1 percent in the first quarter lo 7.1 percent in the second quarter, and then to 2.7 percent in the third quarter. The automobile industry strike in the last half of September had only a small effect, estimated at less than a 0.1 percentage point reduction in the growth rate. Among the components that comprise the GNP, personal consumption and fixed investment grew at lower real rates in the third quarter than in the second quarter, while net exports decreased. Personal consumption expenditures increased $0.4 billion in the third quarter, compared with an increase of $20.1 billion in the second quarter. Nonresidential fixed investment increased $3.9 billion in the third quarter, compared with $9.6 billion in the second quarter. The other component of fixed investment--residential investment--increased from $60.8 billion in the second quarter to $61.2 billion in the third quarter. Real net exports of goods and services decreased $1 1.3 billion in the third quarter, compared with a $3.1 billion decrease in the second quarter. Although exports increased from an annual rate of $144.7 billion to $150.2 billion, imports increased much more, from an annual rate of $1 56.2. billion to $172.8 billion (table 1).

Jan 1, 1984

By A. K. Verma

This paper provides a brief overview of evolution of deformations, stresses, and pore pressures due to different excavation stages during construction of an URL. Excavation of a rockmass develops a damage zone of finite width around the excavated zone which is associated with changes in permeability and which affects the fluid flow mechanism. In this study, a coupled hydromechanical (HM) analysis has been conducted for a water saturated porous rock mass which has been created by sequential excavation and backfill of vertical disposal pit of an URL. For this purpose, an Atomic Energy of Canada Limited?s in-floor concept for a deep geologic repository suitable for Indian conditions has been used. Changes in rock deformations, stresses, strains and mechanically induced pore pressure in an undrained condition, during excavation, as well as those caused by mechanically induced rock deformations after backfill of the disposal pit, have been modeled. A three-dimensional finite difference tool FLAC3D has been used for the analysis.

Jun 1, 2012

By E. L. Oliver

IN OFFERING a few comments and suggestions on trends in mining practice, and the methods and tools of tomorrow's mining, perhaps it will be appropriate to start with the subject of education. Charles Kettering, one of the best-known scientists and experimentalists in the automotive industry once said, in effect, that tech- 111ca1 schools have to be carefid not to teach a lot of hard and fast rules that may have been true once, but aren't so any more, or won't be presently. Possibly the mining school of the future will concern itself less with what has happened and more with what is going to happen. It will be built about or around problems. Such a school will be judged, not by the number of its students but by the quality of its improvements. To such a school the industry will send for men to solve particular problems. The industry will doubtless at some time sup- port such a school financially though a lot of hard work will be required to organize miners to undertake such financing, primarily because the mining industry, other than that concerned with iron and steel, is too loosely knit. Each company tends to its own knitting too closely for its own good. Wouldn't it be splendid if the mining industry would finance a "problem school" as suggested by Mr. Kettering and others.

Jan 1, 1939

By G. A. Van Wielingen

"The conditioning of natural gas to meet contract pipeline specifications involves in the majority of cases in Western Canada, the appropriation of substantial capital expenditures for treating and processing installations. It is therefore of vital importance to the owners and producers of natural gas to arrive at an appreciation of the economics pertaining to the production and surface handling of their gas reserves at the earliest possible stage of field development. The treating and processing of natural gas often results in considerable changes in composition and related physical characteristics between the wellhead and the point of delivery of the saleable gas. This paper presents a general outline of engineering calculations which can be applied in the pre-determination of the effects that surface handling of gas will have on the composition and physical characteristics of sale-able gas. Emphasis has been placed on the calculation of hydrocarbon dew-points, heating values and shrinkages prevailing at the various stages in the surface handling of natural gas. It is believed that advance information indicating the approximate ranges of these physical properties will facilitate process selection and will provide a basis for the estimation of capital and operating costs of process installations."

Jan 1, 1960

By David W. Wisecarver

Kennecott Copper Corporation and the U. S. Bureau of Mines cooperated in a full-scale slope stability research project at the Kimbley Pit near Ely, Nevada. The west wall of the Kimbley Pit was mined from an over-all slope angle of 45° to an over-all slope angle of 57° and the pit was deepened nearly 50 feet. Mining was begun February 10, 1966, and completed October 30, 1966. Approximately 2.55 million tons of ore and waste were mined. The project was designed and carried out to learn more about the behavior of a pit wall as its slope angle is steepened and to obtain a possible insight into engineering parameters for use in design of future slopes. Data from this project are presented as obtained from (1) instruments installed in two adits for deformation and displacement measurements, (2) a subsidence network installed on the surface above the steepened wall, (3) pre- and post-mining observations of stress in rock, (4) sonic-velocity measurements, and (5) seismic and microseismic investigations. Changes occurred in measured quantities as the slope was steepened but stopped when mining was completed. Agreement was noted between the measured changes and predicted changes obtained from calculations using the finite element technique. Subsidence surveys and microseismic studies show the steepened pit wall to be stable.

Jan 1, 1968

By J. Suarez Condezo, E. Herrera Alarcon

The Ilo Smelter Modernization Project will require treating the slag from the Peirce Smith converters in Slag Cleaning Furnaces using pig iron technology. Currently the slags from the converters show variable magnetite contents. The copper contained in this slag is recovered in Reverberatory Furnaces, where the smelting rate was improved due to the high silica content of the converter slag. Preliminary industrial tests where developed to clean the slag from converters using pig iron. The results showed that the magnetite content has a significant influence in this process. This work describes the actions that are being implemented in the converter operation to control the magnetite content in the slag in order to maintain the high copper recovery of the smelter when the new facilities are commissioned. This task will demand a strong control of both the slag chemistry and converter practices in order to get the copper recovery considered as the design criteria (~97.4%).

Jan 1, 2007

By Bryan Wilson

Background ?Nickel Rim South Mine started production ramp-up in Q2, 2009. ?The main dewatering pumps were put into use in August 2009. ?3 Feluwa?multisafe?positive displacement pumps ?1700m single lift pumping ?Reliability has been an issue due to the amount of slimes and fibers (from shotcrete) at the pumps. ?Critiqued internal dewatering system to solve some issues we were having with our sumps Findings 1.Much of the final dewatering system was not in place. a)Temporary pain. Difficult to say something is not working when the system was not yet in place as per design. b)Not enough capacity to handle slimes within the system. 2.Need to address issues with the final design: a)Ongoing costs: The end design has operating costs of $2.5 million b)Scoops in Sumps: The end design relies on scoops to be used for cleaning the sumps c)Slimes Recovery: The system mixes 3 different products in the sumps along with the fibers d)Pump repair costs: The existing Tsurumi pumps are too light duty for our slimes

Nov 1, 2011

By G. G. Rogers, A. Vna Der Linde, N. B. Strydom, W. H. Van Der Walt

Changes in the level of serum vitamin C in mineworkers by N. B. STRYDOM, M.Se., Ph.D. (Illinois) (Fellow), G. G. ROGERS, M.Se. (Pta) (Visitor), W. H. VAN DER WALT, B.Se. (Poteh.) (Visitor), and A. VAN DER LlNDE, B.Se. (O.F.S.) (Visitor) The levels of serum vitamin C in the blood of mineworkers were determined on the first and fifth days of the normal heat-acclimatization period (i.e., before and after exposure to heat) and again after I, 2, and 4 months of underground employment. Supplementary vitamin C was administered to the men during the heat-acclimatization period. Six groups of 20 men featured in the study and, except for one of the two 4-month groups, all the values were obtained after a full shift of underground work. It was found that adequate levels of serum vitamin C were maintained during the heat-acclimatization period, and the 250 mg of vitamin C given daily to each man must therefore be regarded as sufficient. The serum vitamin C decreased significantly with time of exposure to underground conditions, showing that the vitamin C utilized during heat stress is more than that provided in the men's diet. At the end of 4 months, not a single subject had more than 0,4 mg of serum vitamin C per 100 ml, most of them having only 0,3 mg per 100 ml; 90 per cent of the men had had more than 0,4 mg per 100 ml during the acclimatization period. It is therefore recommended that the mineworkers' diets should be supplemented with 100 to 200 mg of vitamin C per man per day.

Jan 5, 1977

By Dorothy Walters

As an increase in the number of producers alters fact ors affecting supply, long-term prospects in traditional markets for many minerals weaken. At the same time, conflicts between national and international objectives undermine existing competitive elements in mineral markets and Canadian costs escalate. Such changes may dramatically alter the environment in which the mining industry operates.

Jan 1, 1979

By AIME AIME

The following changes of address of members have been received at the Secretary's office during the period of Jan. 1 to Mar. 15, 1907. This list therefore supplements the annual list of members corrected to Jan. 1, 1907, and brings it up to the date of Mar. 15, 1907. The names of members who have accepted election during January and February, 1907 (new members), are printed in italics. The large number of changes of address since Jan. 1, 1907, shows the importance of publishing these changes as frequently as possible, and the Bi-Monthly Bulletin has been selected as the means to present this information to the members of the Institute. By a simple method of cutting out these names and addresses and pasting them directly over the corresponding names in the annual list of members, the record can be kept practically up to date, and the value of the list correspondingly increased. For this purpose the changes of address have been printed only on one side of the page. The names of new members, being in italics, are readily distinguished from the others, and can be pasted in approximate alphabetical order on the margins of the pages.

Mar 1, 1907

By John Hays, Hammond

IT is both a pleasure and an honor to be a guest of the Institute and I thank you, Mr. President and fellow-members, for giving. me the opportunity of meeting you this evening. My esteemed friend, President Smith, has requested me to do a bit of "reminiscing" as to the earlier years of my career as a mining engineer, which has now covered a period of fifty years. Let me reassure you by promising that my narrative will not include all the experiences I have had over that long period. You will, I trust, pardon what might seem egotistical but I do not see how a personal narrative could well be otherwise.

Jan 1, 1928

By H. R. Manouchehri

"In all electrical beneficiation methods, the difference in electro-physical properties of the contributed mineral particles, essentially frictional charge, electrical conductivity and dielectric constant properties are exploited to achieve separation. The composition of the raw material determines what kind of either corona charging, conductive induction, or triboelectric separation method should be employed. The process is versatile and is influenced by different parameters related to mineral characteristics, surrounding ambient conditions and electrical and mechanical attributions of the separating device. Electrical separation is surface based beneficiation method which is mainly affected by the surface and surface changes of the minerals. Therefore, it is essential to understand how the electrophysical properties of the minerals can be changed/modified. During electrical/electrostatic separation process, both charge magnitude and its polarity that developed on the particles and therefore, their electrical beneficiation potential is essentially defined by surface phenomena. Therefore, it is essential to understand how the main electro-physical parameters can be changed/modified with applied surface treatment/pretreatment methods to promote separation. Surface treatment of minerals is carried out by different means, including chemical conditioning, irradiation, thermal treatment, etc. This paper discusses and analyze the electrical separation process, electrophysical properties of the minerals with special focus on the effect of surface pretreatment/treatment methods to affect electrical beneficiation potential of the minerals. The surface treatment methods vary in a wide range from simple surface cleaning to more complicated chemical conditioning and doping. The knowledge of the solid-state physics and chemistry leads to improve the beneficiation potential of different mineral systems by choosing suitable treatment method(s). Despite the complexity and multiplicity of the charging mechanisms, difficulties in separating fines it seems to be beneficial make our attempts to further investigate and develop the process as dry, low cost beneficiation process, especially nowadays when environmental concerns, as well as energy and water consumptions are main concerns for mining industry."

Jan 1, 2018