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By H. S. Auvil

[Coals of low-volatile rank cannot be coked without admixing large proportions of high-volatile coal in the usual type of byproduct-coke oven, because they expand excessively and exert side thrust, which ruins the oven walls. Some medium-volatile coals also give trouble. Since high-rank coals produce a strong, blocky coke, it is desirable to have the rank as high as practicable, particularly in the manufacture of foundry coke. Accordingly, it has become the practice to mix or blend high-volatile shrinking, coals with as much low-volatile coal as possible and still have a mixture that will not deform the walls or cause difficulty in pushing the coke. Occasionally, the safe limit of low-volatile coal has been exceeded and ovens have been damaged. It is desirable, therefore, to rave a reliable method of determining the expanding tendencies of mixtures before they are charged into the ovens. Furthermore, coal charges somewhat in its properties as mining progresses, and therefore, mixtures found to be safe at one time may cease to be so subsequently, particularly if nearly the maximum allowable percentage of low-volatile coal is being used.]

Jan 1, 1938

By Robert J. Timko

Because of leakage through and around permanent stoppings in underground mines, more air must be forced into a mine than would otherwise be required for ventilation. As power costs increase, costs resulting from air leakage add increasingly to the operating costs of mining. The Bureau of Mines evaluated four different stopping construction techniques based on the ideas that (1) airtightness could be enhanced by brushing rather than troweling on mortar sealant and that (2) modified mortars (mortars containing glass fibers and other additives for increased strength and adhesion) would improve sealing performance. Air leakage tests comparing conventional to modified stoppings were done when the stoppings were built, after 6 months, after 1 yr, and following simple maintenance. It was found that stoppings can be built and maintained better if-- The area where a stopping is to be built is properly prepared. Stoppings are constructed using the techniques devised by the Bureau. Stoppings are periodically examined for leaks. Stoppings found to be leaking, especially at the perimeters, are resealed.

Jan 1, 1983

By Dan Brown

Improvements in construction equipment and techniques in recent years have made possible the use of drilled shaft foundations in diameters and lengths not previously considered practical or feasible. Many highway bridge and other structures are now routinely founded on drilled shafts which -are 8 to 12 feet in diameter and extending over 200 feet in depth below grade. There are unique challenges associated with constructing such large and deep cast-In-place foundations and engineers should be aware of the special needs associated with site investigation, construction specifications, material requirements, and quality assurance. This paper outlines a number of special considerations for these foundations, along with strategies that may be employed to improve the reliability and quality of large drilled shaft foundations.

May 11, 2007

By E. S. Malloch

THE Great War forced the peoples of the world to recognize the importance of the wise development and use of the world's natural resources. Not the least, and perhaps the most, important, is the world's fuel supply- solid, liquid, and gaseous. Without fuel our civilization would be impossible, and mankind would of necessity have to congregate in the torrid zones of the earth's surface for at least six months of every year. Of the three classes of fuels the solid ones are the most plentiful, as well as being the most widely distributed, since few countries are entirely devoid of solid fuels of one kind or another. Until a hundred years ago wood was the fuel most generally used in this country, but since then coal has supplanted wood as a fuel in all its uses, except in the outlying districts and among the farming communities. For many years the supply of coal was thought to be unlimited, but as years went by more thought and study were given to the world's coal resources, until today not only are the limits known, but in one instance at least their depletion is predicted to be almost within the age of living men, unless more provident methods are put into practice for their winning and utilization.

Jan 1, 1928

By K. Cole, D. Mesa, P. Brito-Parada, M. R. van Heerden

Turbulence in mechanical flotation cells, achieved via an impeller, plays a key role in keeping particles in suspension, dispersing air bubbles, and promoting particle-bubble collision. However, studying the hydrodynamics of a flotation cell is not a simple task, due to the complex nature of flotation systems which are opaque, turbulent, multiphase and polydisperse in terms of particle and bubble sizes. In this paper we study the impact of impeller design modifications on the hydrodynamics of a continuously overflowing bench-scale flotation tank. To this end, two different impeller designs, with and without a stator, were assessed using Positron Emission Particle Tracking (PEPT). This allowed the authors to determine, for the first time, the effect of an impeller design on the behaviour of both hydrophobic and hydrophilic particle tracers. It was experimentally observed that the use of a stator modifies the hydrodynamics within the flotation cell, distorting the lower mixing loop that is characteristic of axial impellers. The role of the stator in dissipating turbulence results in reduced particle velocities outside of the impeller-stator region. These results have important implications for flotation cell design and are discussed in the context of the impact that different designs have on particle movement, flotation hydrodynamics and, ultimately, flotation performance. The data set generated is also extremely valuable for modelling and validation purposes. Keywords: Flotation, flotation tank, impeller design, rotor, stator, PEPT, hydrodynamics

Jan 1, 2020

By I M. Platten, S C. Dominy

The Clogau St DavidÆs gold mine has a recorded production of around 81 000 oz Au and it is the largest mine in the Dolgellau gold-belt and BritainÆs most prolific historical producer. The original mine was first worked for copper, however; in 1854, gold was found in waste material from the St DavidÆs section. In recent times the mine has operated intermittently between 1983 - 2007. The principal black shale-hosted gold-bearing reef (Main Reef) can be traced for about 3 km, striking approximately NE-SW and dipping steeply between 60¦ - 90¦ SE. The reef system pinches and swells, changes strike and splits into a number of smaller branches. Reef width is variable, ranging from over 6 m to a few cm and in places reducing to small irregular blobs. The reef is internally complex and composed of swarms of narrow (1 - 300 mm) subparallel veins separated by country rock sheets. The gold-bearing veins within the reef package are discontinuous; though generally possess bonanza grades running 10s - 100s oz/t Au. It has historically been shown that some gold-rich vein segments can grade up to 300 oz/t Au. The predictability of the gold-rich segments is poor, but has been shown to be related to presence of the Clogau (black shale) Formation, and/or the mechanical interactions of the reef with greenstone sills, reef branching and splitting and/or cross-fractures to form ore shoots. The mine is currently being re-evaluated as a potential small-scale selective operation.CITATION:Dominy, S C and Platten, I M, 2012. Geology, mineralisation and potential of the Clogau St DavidÆs mine, Dolgellau gold-belt, Gwynedd, Wales, in Proceedings Narrow Vein Mining 2012 , pp 101-120 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

By Lars A. Bergstrom

High-voltage direct -current transmission is a relatively new technology. The successful development and operation of AC/DC converters, capable of handling large power blocks, have made HVDC transmission generally accepted by utility engineer s and planners around the world. HVDC technology still has significant development potential and, as a result, it is expected that equipment costs will escalate at a substantially slower rate than those of conventional AC equipment. This development will also result in still more compact terminal stations. This paper reviews two modern HVDC installations. In Zaire in Africa. a 1700-km overhead DC line rated at 500 kv, will supply power to the copper mining district in the Shaba region. Another HVDC link connects Norway and Denmark through a submarine cable rated at 250 kv. This is the longest HVDC cable in the world, 127 km, and the water depth , maximum 530 m, is also much greater than for any previous similar cable. The reasons for selecting HVDC are discussed, and the design and layouts are presented.

Jan 1, 1978

By W. L. EGY, GEORGES. RICE, L. M. JONES, J. K. CLEMENT

This report has been prepared, not only for the purpose of recording the results of the first series of coal-dust tests conducted in the experimental mine of the Bureau of Mines, but also to place before the mining public a description of the mine and an account of the objects sought in its establishment. Soon after the organization of the technologic branch of the United States Geological Survey, J. A. Holmes, then chief of the branch, concluded that for the solution of various problems relating to the causes and prevention of mine explosions it would be best to carry on large-scale tests in a mine rather than in a surface gallery. The idea of utilizing the underground passage of a mine for making explosion experiments did not at' first meet with general approval among investigators in this country or abroad. Many thought a mine passage was not a proper place in which scientific tests could be conducted, as great difficulty in controlling conditions was expected. However, after all arguments for and against such an investigation had been carefully considered, plans for opening an experimental mine were definitely adopted by the Bureau of Mines in 1910, and an allotment of funds was made to carry out the project. The first endeavor was to find an existing mine suitable for the purpose, but the mines offered by owners were either worked out, were wet, had poor roofs, or presented complications of various kinds, so that it was finally decided to open a mine if a site could be obtained having natural conditions that would fill the various requirements. A most desirable location was found on property of the Pittsburgh Coal Co., near Bruceton, Pa. The president of this company, Mr. W. K. Field, the general manager, Mr. G. W. Schluederberg, and the chief engineer, Mr. E. J. Taylor, rendered every possible service in

Jan 1, 1913

By Eric Lindquist, John Compagnone, Gabriel Carvajal

"Condon-Johnson & Associates, Inc. (CJA) with the assistance of design consultant, Brierley Associates, designed and installed a water tight shoring system utilizing several ground improvement techniques jointly. Prior to the installation of the shoring system, a test program consisting of the installation and testing of 7 jet grout columns; 1 soil mix panel; 7 soil anchors and 3 tie downs was performed to verify design assumptions. State-of-the-art quality control measures were employed throughout the project.The shoring system consisted of:•,Deep Soil Mixing (DSM) wall utilizing triple axis tooling to install overlapping columns along the perimeter of the proposed excavation to a treatment depth of 54 feet.•,Installation of steel piles in DSM to provide rigidity to the wall.•,Installation of a jet grout bottom seal, installed from surface to a depth of 58 feet below existing grade.•,Installation of 153 soil anchors, 1-1/4” diameter and 47’-6” length, to tie the jet grout bottom seal to the native soil below to resist hydrostatic uplift, installed from existing grade to a depth of 91 feet.•,Installation of walers and pipe struts for internal bracing•,Installation and stressing of 117 tie downs, 1” diameter and 16 ft length, to tie the pump station mat slab to the jet grout bottom seal, installed from inside the excavated pit.Subsurface conditions at the site consist of uncontrolled fill materials to a depth of 20 feet comprised of sandy silt and clayey sand. The native soils underlying the fill generally consist of soft and compressible lean clay and silt with varying amounts of sands to a depth ranging from approximately 44 to 54 feet below ground surface, which in turn are underlain by dense to very dense silty sand. The groundwater elevation at the site is approximately 8 feet below ground surface.This paper covers the design aspects, construction, and quality control measures undertaken by the geotechnical contractor, with supporting figures.INTRODUCTIONThe owner, County Sanitation District No. 2 of Los Angeles County, designed upgrades to their existing Long Beach Main Pumping Plant Facility. The upgrades consist of a new pump station that includes a reinforced concrete below-grade wet well and dry well, a two-story operations building, two 78-inch diameter pipe inlets, two 42-inch diameter discharge pipelines connecting the existing manifold, two pipe junction structures, two insert-type junction structures, and electrical transformers. This paper focuses on the excavation shoring for the new pump station. The original shoring design concept for the pump station excavation illustrated on the contract plans consisted of pressed in sheet piles, a jet grouted bottom seal with soil anchors, 2 levels of internal bracing, and tie-down anchors to resist hydraulic uplift forces on the buried pump station."

Jan 1, 2017

By G. M. Brown, B. J. Ebacher, W. G. Koellner

Introduction There is a continual economic push to increase the productivity of mobile material handling equipment used in open pit mines. This includes the largest electrical machines: excavators (draglines and shovels) and haul trucks (Figure 1). Existing DC drive systems used on this type of equipment are a mature technology. They have no further economic potential to accommodate larger equipment be-cause of the high maintenance costs and the trade-off between power, speed and space limitations of their DC traction mo-tors. In recent years the large-scale introduction of AC drives in the rail transportation sector1,and the availability of poworful GTO and IGBT modules have led to the devolopment of compact, powerful, an drugged AC inverter drives specifically adapted to the mining market2,3. The major advantage of AC drives stems from the squirrel cage induction motor which eliminates the DC commutator. This leads directly to higher speed, increased power density, higher reliability, greater efficiency and lower maintenance of the traction motors. In the context of excavators and haul trucks, additional benofits driving the move to AC are (i) increased production rate due to higher machine speed, and power density, (ii) increased reliability and lower cost inverters using 3.3 kV IGBT's, (iii) active front-end (AFE) technology that improves compatibility with the mine power grid and an proved dynamic response,(iv) intelligent converter design that provides increased fault tolerance, (v) contextual maintenance software that facilitates trouble-shooting, and (vi) remote diagnostic capabilities. This paper describes how these and other features of AC drives lead to higher productivity in mining shovels, draglines, and haul trucks. Minimize the cost per ton of material moved The overall goal that drives design and sales of excavators and haul trucks is the constant requirement to reduce the cost per ton of material moved. Whether this involves blasting, loading trucks, or hauling material to the crusher or waste dump, equipment that reduces the cost per ton of material moved contributes to a more profitable operation. An accurate determination of the true cost per ton to move material must consider every aspect of the equipment and the circumstances under which it is used. Procurement and capital costs, fuel, operating, and maintenance costs over the useful life, and eventually the cost of scrapping should all be taken into account to determine the real cost per ton of moving material. We will focus on two broad areas that relate to the equipment itself; factors influencing the amount of material moved (Table I) and factors influencing the cost of material moved (Table II). Emphasis will be given to those elements in the tables that most influence the productivity of excavators and haul trucks due to the application of AC drive technology. Maximize the amount of material moved Maximize production rate he production rate refers to the quantity of material that can be loaded or moved per hour. This generally involves larger, faster, and more powerful equipment that operates more reliably to minimize down-time. AC motors Figure 2 compares the hoist motor speed-torque response of two 77 t (85 short ton) shovels, one AC the other DC. The absence of commutation limits on the AC motors enables the AC shovel to operate with a greater area under the speed-torque curve, resulting in faster lowering speeds and reduced times for the swing to return to the pit. This is especially important for short swing angles where the operator may have to wait for the dipper to lower. Reducing the cycle time by 6 to 8 seconds at the shovel translates into an increase in shovel production of about 20%. Larger equipment The bucket capacity of excavators has increased approximately 100-fold over the last century. Figure 3

Sep 1, 2001

By Paul M. Tyler, Amy B. CLINTON

The four elements fluorine (F), chlorine (C1), bromine (Br), and iodine (I) form the most intimate family in the entire system of elements and are grouped under the name "halogens" or salt formers (by derivation from the Greek). The first member of this family, fluorine, is the most chemically active element known; and fluorspar, and to a less extent cryolite, the chief sources of fluorine, are important commercial minerals. Fluorine occurs in nature chiefly in combination with sodium as common salt, but it also appears in other natural compounds in sea water, salt-well brines, and bedded deposits. In addition to common salt, various compounds containing chlorine (chlorides) have long been consumed by industry on a large scale, and within the last two decades that element itself has come rapidly into prominence as one of the leading industrial chemicals. Bromine and iodine, the two retaining members of the family, are less abundant in nature and less readily isolated and in consequence of their relatively high price have found few industrial uses, being consumed chiefly in medicine and in photography. Bromine, however, is now entering the industrial field to a considerable extent, due to the rapidly growing use of ethylene dibromide in anti-knock compounds for gasoline. The present paper is devoted to bromine and iodine, but in order to compre- hend the physical and chemical characteristics of these two elements (and hence their potential economic significance) it is convenient to consider them as members of the family series to which they belong. The family relationship of the halogens is illustrated by the following:4 (1) The similarity in the chemical and physical properties of the elements and their corresponding compounds is such that the prop- erties of any one member of the family can be said to summarize or rather to typify the properties of all the other members, although fluorine diverges a little in some of its properties. (2) The gradual transition of chemical and physical properties is such that if the elementa are arranged in order F, Cl, Br, I the variation in any particular property in passing from fluorine to iodine nearly always proceeds in the same order, and that is the order of their atomic weight. Taxing almost any property and comparing its magnitude in passing from the element fluorine to iodine, or from the fluorides to the iodides, a similar graiation will be observed. Thus, take the melting point of the cadmium, calcium, barium, sodium, or potassium salts, in degrees.

Nov 1, 1930

By Verya Nasri, James Sullivan, Alex Varas

"INTRODUCTION Many major cities in the United States have a combined storm water and sanitary sewer network. Regular rainfall overwhelms the system capacity and results in millions of cubic meters of untreated sewage being dumped into local waterways. One legally mandated solution includes several kilometers of large diameter shallow or deep rock or soil tunnels, a pump station as well as associated collection sewers, diversion structures and drop shafts. In this paper, the basis for design of different system elements including the drop shafts and pump station is explained in detail. Common construction methods used for different type of shafts including tangential vortex and baffle plunge, and also pump station alternatives comprising cavern or various shaft configurations are discussed. DIFFERENT TYPES OF PUMP STATIONS The dewatering pump station serves as the heart of any deep CSO tunnel system and is critical to the goal of reducing CSOs by providing a controlled release of the stored tunnel volume to the wastewater treatment plant. As the major mechanical component of the project, the station will require the greatest attention by operations and maintenance staff. Designing a durable and easily operated pump station requires addressing some major challenges, including the following: • Longevity – equipment, materials of construction, and station environment • Controlling odors • Safety for operators and maintenance personnel • Easy access to equipment • Protection from hydraulic surges Location. Owners face a fundamental decision relative to the location of the pump station, which will affect how these challenges are addressed. The pump station can be built within the tunnel launch shaft or within its own dedicated shaft. This decision is driven by cost and schedule. Use of the tunnel launch shaft may provide owners cost saving opportunities by not having to construct a separate pump station shaft. However, this will likely extend the pump station construction as much as two years until the tunneling has been completed. Furthermore, delays to the tunneling operation would delay the pump station construction work, potentially leading to delay claims. For this reason, it has been more common to utilize a separate pump station shaft on recent CSO tunnel projects (Nasri et al. 2015)."

Jan 1, 2016

By A. M. Cummings

Each mining district presents different problems as to the methods of ore extraction cad underground support, which are dependent upon the type of the ore deposit and the character of the inclosing rock. Mining costs, however, depend largely aeon the efficiency with which the methods employed underground are [applie] as well as upon the selection of the method best adapted to the physical conditions. The purpose of this paper is to present to the operator in other districts a detailed description of ho mining method used ins results obtained in tie exploitation of the bedded magnetite deposits of the Mineville district. The town of Mineville is situated in the Adirondacks, five miles west of Port Henry on Lake Champlain.

Jan 1, 1928

By Martin McKinnon, Guy Reed, Russell Frith

"It is arguable that the development of reinforcing roof bolting systems has largely stagnated in recent times, primarily due to the prevailing industry view that few, if any, further improvements can be made to what currently exists. However, this paper contends that reinforcing roof bolting systems can be further refined by considering both the specific manner by which horizontally bedded roof strata loses its natural self-supporting ability and the specific means by which reinforcing roof bolts act to promote or retain this natural self-supporting ability. The Australian coal industry insists on minimising bolt-hole diameter to maximise load transfer and on targeting full-encapsulation by any means necessary. This has led to a significant, albeit unintended, consequence in terms of overall roof bolting effectiveness, namely increased resin pressures during bolt installation and the associated potential for opening bedding planes that may have, otherwise, remained closed during the bolt installation process. Given that the natural self-supporting ability of roof strata is strongly linked to whether bedding planes are open or closed, logically, minimising resin pressures should be a significant benefit. This paper focuses primarily on three key issues that relate directly to the function of the roof bolting system itself: (i) the importance of proper resin mixing in the context of maximising load transfer strength and stiffness, (ii) the importance of minimising resin pressures developed during bolt installation, and (iii) the importance of maximising the effectiveness of the available bolt pre-tension. All mine operators should be invested in improving the individual effectiveness of each installed roof bolt, even by relatively small incremental amounts, so this is an important topic for discussion within the mining community."

Jan 1, 2017

By William H. Shockley

THERE was an, extensive mining and industrial exploitation of Russia, about 20 years ago, by Belgian, French and British capitalists; but the results were discouraging. It is said that the Belgian and French public together lost approximately $400,000,000, chiefly in the coal and iron industry of southern Russia. This loss is largely accounted for by the fact that most of the companies were formed, as usual in " boom " times, to sell stock; and that thorough investigations were not made. In 1906, renewed interest was taken in Russian mines, especially in those of gold and copper, and a considerable literature is growing on this subject; but as yet I have seen no account of one of the large Russian mining estates. The following notes on such property, where the conditions are so different from those in the mining regions of the United States, should be of interest This inadequate and probably somewhat inaccurate account is made up, partly from my own notes made on the ground, in the summers of 1904 and 1905, and partly from a volume on the geology and resources of the estate issued several years ago, containing surface-and mine-maps, and from a pamphlet published in 1904, giving a general account of the condition and prospects of the property. This pamphlet includes a report made by Arthur L. Pearse, a member of this Institute, in 1899. Both these books are in Russian, and were prepared by the Bogoslovsk Mining Co., which owns and operates the property. Articles in many other languages have appeared dealing with various matters connected with the estate; but I know of no other general account of it. In numerous books and articles on the Urals and Siberia, however, localities are described in which somewhat similar conditions prevail. Recent papers by

Mar 1, 1908

By Donald C. Myntti

INTRODUCTION A major segment in a successful heavy equipment maintenance and repair program is the provision of well-laid out and well-equipped shop and service facilities The facilities described here will be those required for a large, high tonnage hard rock open pit mine utilizing rotary drills, shovels, haulage trucks, support equipment, and service trucks. The term support equipment covers the equipment required to support the drill, shovel, and truck operations, these are crawler tractors, road graders, front-end loaders, water trucks, rollers, rubber-tired tractors, etc. Service trucks are the automotive type consisting of rubber-tired over-the- road equipment. The primary structures generally involved in the total maintenance effort are as follows. (1) the main shop with an attached warehouse (the structure could also house the tire and lube shops plus the equipment cleaning stalls), (2) a service station with bulk petroleum product storage tanks, (3) a heating plant, (4) a security station (lf this is a corporate requirement), (5) operating department and employee assembly buildings, and (6) an electrical substation. Under certain conditions, many of these facilities with the exception of the substation could be combined In one or several structures. This arrangement could have a great advantage especially in areas where the heating of the structures is extremely critical.

Jan 1, 1979

By Michael Bourassa, Sonja Felderhof, Normand Champigny, Steve Vaughan

Introduction -Comparison of International Reporting Standards (Sonja) -Legal and Due Diligence Requirements for Reporting (Steve) -Flexibility to Recognize International Reporting Standards (Michael) -Obligation of SRO’s to Discipline (Michael) -Impact of Sarbanes Oxley on Reporting (Normand)

Jan 1, 2003

By T. T. Read, T. L. Joseph, F. H. Royster

In a preliminary study of the beneficiation of iron ores conducted by the Bureau of Mines, one of the authors (T. T. Read) found it necessary to ascertain, if possible, how much effect a decrease in the silica content of an iron ore has upon the cost of making pig iron from the ore. In the beneficiation of iron ores the most important impurity to be removed is usually silica, and the amount that can be expended on a beneficiation process to reduce the silica content of the ore is obviously determined by the amount of increase in the value of the ore after beneficiation. The price that can actually be obtained for a beneficiated ore is, of course, a matter of negotiation between the seller and the buyer, but since the relative value of different grades of iron ore must be chiefly based upon the cost of making pig iron from them, an approximation as to the effect which decrease in the silica content of ore has upon the cost of snaking pig iron is an important guide in estimating what probable average gain will result from subjecting an ore to a beneficiation process. A search of the literature failed to reveal any detailed statement on this important topic, but fortunately the data are at hand to permit making an approximate calculation of the probable effect. For the purpose of the calculation assume three iron ores with the following composition (natural):

Jan 1, 1924

By Raymond B. Ladoo

In order to obtain comprehensive and authentic information on fluorspar mining in the western States , the writer, together with and at the request of representatives of some of the largest fluorspar producers of the Illinois - Kentucky district , spent the month of April , 1922 , in examining all we stem fluorspar deposits ( of which record was available ) believed to be of possible commercial importance .

May 1, 1923

By M. E. Coleman, G. Money

Pneumatic Conveying and Process Injection Technologies have been implemented in the metals markets for the last 40 years and have considerably improved the productivity and the performance of many processes. There have been many steps forward in handling technology and this paper seeks to consider those now offered by Clyde Materials Handling who as an established customer-driven solutions provider has turned its attention to supporting the Metals Market. Clyde seeks to utilise its knowledge, expertise and technologies to transform the production processes of its customers, who operate in the ferrous and non-ferrous metals industries.

Jan 1, 2008