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By Jean Wehbe, Daniel C. Brahana

"The new Mercedes-Benz Stadium (MBS), home of the Atlanta Falcons, is part of a new era of stadium construction in the U.S. These new-age stadiums are larger and have more amenities than their predecessors. Many of the MBS’s features, including its innovative retractable roof, result in extraordinary structural loads. The roof structure is supported by a series of mega columns that bear on eight large caps, six of which are supported by drilled piers. Each of the pier caps contains between 8 and 16 drilled piers that bear in the underlying bedrock. The design pier diameters are 6 and 6.5 ft (1.8 m and 1.9 m). Augercast piles were used to support two of the mega column caps. Drilled piers, augercast piles, aggregate piers and spread footings were used to support the more lightly loaded portions of the structure.The focus of this article is the construction aspects of the drilled pier foundations. Initially, a fairly extensive drilled pier load test program was performed. Load testing included a Statnamic compression test, two Osterberg Cell tests and two lateral tests. Production pier installation included over 3,800 linear ft (1,158.2 m) of earth excavation and over 1,350 linear ft (411.4 m) of hard rock excavation. The piers contain more than 6,600 cu yd (4,587.3 cu m) of concrete and 1,100 tons (998 tonnes) of reinforcing steel. Drilled pier installation took about 4.5 months. ABE Enterprises was the specialty foundation subcontractor and Bauer-Pileco was the equipment provider.Site and Subsurface ConditionsThe project site is in downtown Atlanta and was originally occupied by residential buildings. A portion of the site was later developed as a rail yard, and other areas contained light manufacturing, warehouses and other relatively light structures. For the past 15 to 20 years the site had been used for surface parking.Beneath a surficial layer of manmade fill, soil test borings at the site generally encountered residual soil, partially weathered rock and the parent bedrock. The bedrock at the site is highly variable, both in elevation and in hardness/quality. The depth to rock is reasonably uniform within the western two-thirds of the site at about 20 to 50 ft (6 to 15.2 m), with a few exceptions. In the eastern third of the site, the rock drops off dramatically to the north and east. In one mega column cap, there was almost 80 ft (24.3 m) in elevation difference. In two borings in the cap that were 20 ft (6.1 m) apart, the top of rock varied in elevation by 34 ft (10.3 m)"

Jan 1, 2016

By D. Robert Weir, Verner B. Sefton

The reduction roast-ammonium carbonate leach-hydrogen reduction process for laterites has been under development by Sherritt Gordon for the past 20 years. The process can treat high iron or low iron laterites, with some process modification, and gives extractions of 88-93% Ni or 82-88% Ni, respectively. Five campaigns on a 1 tonne per day Pilot Plant and four campaigns on a 35 t/d Demonstration Plant have been carried out on laterite from three different deposits, and many other laterites have been investigated in the laboratory. The Marinduque Surigao Nickel Refinery in the Philippines was designed on the basis of this work. The process comprises roasting to selectively reduce the nickel and cobalt in the laterite, leaching the calcine in ammonium carbonate to dissolve the metals, recovery of cobalt by precipitation of a mixed metal sulphide, concentration of nickel from the carbonate solution by basic nickel carbonate precipitation and recovery of high purity nickel by hydrogen reduction of nickel from ammonium sulphate solution. Ion exchange has been developed as an alternative to BNC and for recovery of trace nickel from BNC barren liquor. Details of the development of some of the process steps through the laboratory to commercial plant are discussed. The process metallurgy has been confirmed in the commercial plant.

Jan 1, 1979

By Lois G. Schwarz

I did a project (Sungai Piah) as a consultant to your firm in Malaysia, where we were faced with a similar situation as sketched out in your question. The following is what we did for the grouting of the primary holes, which were both located upstream of the plug as well as downstream: We used a hydrophobic MDI based semi-rigid polyurethane prepolymer in the first phase of the grouting operation when grouting under water flow conditions. Then in the second phase and also for the contact grouting we used a two component water compatible polyurethane elastomer. And then for deeper formation grouting, when all the water flow had been stemmed in the vicinity of the plug, we used a regular (balanced stable) cement based grout. So it may not exactly answer your question, but we first used hydrophobic grout because it is very efficient to grout a formation through which water flows. We didn't stop all the leaks day-lighting downstream of the plug or all water running through the formation near the plug, but the flow of water through the rock formation adjacent to the plug was reduced by 99.9%, after completing the urethane grouting. This facilitated the placement of cement based suspension grouts without wash-out.

Feb 10, 2003

By M. O. Serbousek

The load-transfer mechanics of fully grouted roof bolts in coal mines have been investigated in laboratory and analytical studies. The purpose of this Bureau of Mines research is to increase understanding and better interpret data from routine field pull tests and to develop a numerical model of a grouted bolt that can be used in a global computer model of a mine roof. Analytical studies using closed-form solutions and finite-element techniques were compared to experimental results. Laboratory work includes variation of bolt length, hole diameter, and grouL type. Pull tests were pel'fol·med on 4-, 2-, and I-ft bolts in holes of 1-and I-3IB-in diameters. Both polyester resin and inorganic grouts were used as the anchorage medium. Strain gauges were installed on the bolts at several locations to observe the rate of load transfer from the bolt through the grout to the rock mass when a force was applied at the bolt end using standard jack pull testing procedures and equipment. The average anchorage length of 4-and 2-ft bolts was 22 in. Grout type and hole size variations did not produce a significant effect on the rate of load transfer from the bolt to the rock.

Jan 1, 1987

By R. G. Knickerbocker, C. T. Baroch, A. W. HACKWOOD

The difficulties inherent in the production of alumina by the formation of potassium alum and its subsequent thermal dehydration and decomposition have been overcome , to a large extent , in a process developed at the Boulder City Station of the Bureau of Mines . This process is applicable to the reserves of alunite known to occur in several Western States and , possibly , to certain clay and low-grade bauxite deposits known to exist in this country . The operations sequence of the process is shown in the flow sheet (fig . 1) . Only those steps included within the heavy line are considered in this report . Four different procedures for dehydration of alum were investigated ; ( 1 ) Spray drying , ( 2 ) rotary - kiln drying , ( 3 ) dry grinding in a thermal ball mill , and ( 4 ) dehydration in the vertical- column flash dehydrator . Based upon fuel requirements and other practical considerations , the vertical- column dehydrator , or some modification of its operating principle , offers the botter possibility for commercial use .

Feb 1, 1946

By K. Muchima, C. Siame, L. Little, B. Kaputula, Q. Mclennan

"The variability of copper mineralization at Kansanshi mine significantly affects the efficiencies of the processes used to recover copper. Quantifying this variability is therefore essential for monitoring and optimizing the performance of the concentrator, which comprises three different flotation circuits (sulphide, mixed, and oxide) and an atmospheric leach circuit. Onsite automated scanning electron microscopy with energy-dispersive X-ray spectrometry (Auto-SEM-EDS) is used to analyse routine weekly composite samples for each circuit, providing detailed analyses of bulk mineralogy, copper deportment to different minerals, mineral liberation, and associations. Weekly mineralogical trends are used to assess changes in process performance, and characterization of the copper losses has inspired a number of projects to target the specific particle types responsible for the main losses. In this paper we describe the relationship between mineralogy and plant performance at Kansanshi, and discus IntroductionKansanshi is a copper and gold mine located in the Northwestern Province of Zambia, with an annual production in the region of 250 000 t of copper and 160 000 ounces of gold. Ore mined from the epigenetic vein-hosted deposit is classified into three ore types based on the extent of oxidation and supergene enrichment. Sulphide, oxide, and mixed ore are fed to separate mineral processing circuits tailored for recovery of the dominant copper minerals in each. After comminution to a target grind size of 80% passing 150 µm, each ore type is subjected to flotation to recover the copper sulphide minerals (chalcopyrite, bornite, chalcocite, covellite). The oxide float tails and a large proportion of the mixed float tails are then treated by atmospheric leaching to extract copper from the remaining copper-hosting minerals, which include cuprite, malachite, chrysocolla, and delafossite. Some native copper is recovered by flotation and some of it is recovered by leaching. A small portion of the combined concentrate from all circuits is subjected to high-pressure leaching and the rest is sent to the smelter. Sulphuric acid produced during smelting is used for the atmospheric leach."

Nov 1, 2018

This appendix contains the list of equipment, their corresponding number and their specifications with the quotations from the vendors/ manufacturers who can supply this equipment. The listings are arranged by process plant areas.

Jan 1, 1979

By T. E. Swigart, C. E. Beecher

The Federal Government, as the largest lessor of oil and gas lands in the United States, is vitally interested in the conservation of those resources. This manual has been prepared at the direction of the Secretary of the Interior to call the attention of lessees of public oil and gas lands to the most common oil and gas field wastes and the best methods of preventing them; to outline the policies of the Interior Department on field operations; and to give information as to how the "Operating Regulations" of the department will be interpreted by the Bureau of Mines. The oil industry has progressed steadily. Present operating methods are much more efficient-and less wasteful-than those of a few years ago; moreover, the art of producing oil and gas is continually advancing. Public interest requires that improved methods, which will result in obtaining the greatest possible amounts of oil and gas from the natural deposits, shall be developed and used. Part I of this manual points out types of oil and gas wastes and suggests, in detail or by reference, the most practical and effective methods in current practice for stopping these wastes. Throughout Part I the department's operating policy is given, with interpretations of the "Operating Regulations" for enforcing every practical measure of conservation. Part II comprises the revised "Operating Regula-tions" which supersede all previous regulations and will govern future operations on public lands; it will be found in the pocket in the back cover of this bulletin.

Jan 1, 1923

By D. J. MacDonald

As part of a U.S. Bureau of Mines program seeking improvements to the Bayer process, a typical Jamaican bauxite was heated at temperatures up to 500° C in hydrogen, and its leachability under Bayer process conditions was measured and properties of its leached residue were observed. The objectives were to find ways to decrease the amount of organic carbon in bauxite or in leach liquor derived from it without impairing its leachability, and to improve the leached residue's filterability. Techniques employed included heating bauxite under pressure in an autoclave with hydrogen, and in flowing hydrogen at ambient pressure in a tube furnace. Leaching tests were done with a 600-mL stirred reactor. In some of the leaching tests, ferrous sulfate (FeS04) was introduced before leaching to produce a partially magnetic product. Results showed that exposure to hydrogen at temperatures from 160° to 360° C progressively diminished the bauxite's content of organic carbon and decreased the ratio of organic carbon to aluminum in leach liquor, an improvement that would allow a process using hydrogen-treated bauxite to be operated at a smaller recycle ratio, thereby consuming less energy and allowing greater throughput for a plant of given capacity. The bauxite's leachability was not impaired by high-temperature pretreatments, except at temperatures higher than 280° C. Pretreatments in hydrogen produced black, partially reduced bauxite which upon leaching gave a residue that was attracted to a magnetic field and was amenable to separation from green liquor by a magnetic filtration method.

Jan 1, 2010

By Joshua Cole, Joshua Sovechles, Christian Cardoso, Guillermo Bermudez, Martta Hirsi, Joshua Dettamanti, Rabia Abbasi

The implementation of technological advancements in flotation is key to optimize performance in mining operations. Consequently, flotation cell’s performance is highly dependent on the effectiveness of the mixing mechanism. A more efficient flotation mixing mechanism is likely to improve metallurgical performance and optimize energy consumption, which is the motivation for Metso’s journey to develop the latest iteration of FloatForce®. Looking to test the new design at plant scale, Metso approached the Kennecott Copperton concentrator, which is continuously looking for different venues to improve metallurgical performance. In this context, a test campaign was conducted to implement this new flotation mixing mechanism in their rougher circuit during 2024. The industrial trial consisted of several sampling campaigns assessing different operational parameters for comparison purposes around a 300m3 flotation cell. The effect of the new flotation mixing mechanism on the cell’s power draw was also studied. The results of this trial at Kennecott are presented in this paper. Overall new flotation mixing mechanism, FloatForce+ was seen to perform as well as the original FloatForce.

Feb 1, 2025

By B. D. Pandey, D. Bagchi, Premchand

During the separation and recovery of metals from the ammoniacal leach liquor of Indian Ocean nodules by solvent extraction-electrowinning (SX-EW) in close-loop operation, the copper electrolyte containing ~40g/L Cu, 20 g/L Ni and 180 g/L sulphuric acid is bled-off to control the impurities. The recovery of copper and nickel as powders has been examined from the copper bleed solution following partial decopperisation, crystallization of mixed sulphate of the two metals and aqueous hydrogen reduction. From the dissolved sulphate solution containing 17.68 g/L Cu, 18.83 g/L Ni and 0.03 g/L Fe, the copper powder was precipitated at initial hydrogen pressure of 26 bar in an autoclave in 90 min at 140 °C. The residual copper from the spent solution was removed as sulphide and nickel powder was then recovered (99%) in two stages from a solution of pH 4.5 at 40 bar pressure and 190 °C. However, 98% nickel recovery in one stage was achieved when hydrogen reduction was carried out from an ammoniacal solution in the pH range 9-11. Copper and nickel powders were produced from the bleed solution with acceptable purity and specifications suitable for P/M applications.

Jan 1, 2004

By A. Ignatieff

This is the second review of developments in coal mining engineering (see C.I.M .M. Transactions, Vol. LI, 1948, pp. 262- 264) and covers the period from October, 1948, to January, 1950. Mechanization The period under review was characterized by the intensive development of appliances providing for complete mechanization of coal-face operations. A variety of machines are being evolved or have already been placed on the market which embody the principle of 'continuous mining'. This trend can be observed in all coal producing countries. In the United States, two continuous mining machines have been developed for entry and room application and by the end of 1 949 were being used in a number of mines. These are the Joy Continuous Miner in which the coal is ripped from the face by means of multiple cutter chains, and the Jeffrey Colmol employing cutters on rotating arms for chipping the coal from the face. The Joy machine is made in tw6l models, 34-in. and 48-in. high and designed for a range of seam thicknesses from 3-ft. -t-in. to 4-ft. 6-in. and from 4-ft. 6-in. to 8ft., respectively. Some experience has been gained with this machine and accounts of its performance are already appearing in the technical literature. The Jeffrey-Colmol has a more limited range of working height. The first model, 38-in. high, was designed for seams about 4 feet in thick11ess but more recently the 28-in. low model has been placed on the market for seams 2-ft. 6-in, to 3-ft. 4-in. in thickness. Conventional mobile loading machines of the gathering-arm type are continuing to yield high production under suitable conditions, and improvements or modifications of the basic principle are embodied in new machines as, for example, the Jeffrey mobile (conveyor) loader with extensible (gathering-arm) head developed for conveyor mining.

Jan 1, 1950

By Darin Cotton, Tim Burgess, Tim Martin

"As the leading US supplier of roof control drills, J. H. Fletcher and Company® has encountered an extensive set of roof strata challenges and has overcome various drilling issues by varying machine parameters and working with customers and tool manufacturers to develop solutions. Every mine wants to drill and install roof bolts as fast as possible with maximum safety at the lowest possible installation cost for their conditions. In most circumstances, the intuitive method of higher speeds and pressures can actually have a detrimental effect on the roof drill safety and performance.This paper will outline recent tests carried out at several different coal mines in the Eastern United States. The tests focused on optimizing the drilling parameters of feed pressure, feed rate, rotation speed, and drill torque.The drill feed, rotation speed, and rotation torque, as well as the type of bit selected, have a definite impact on the performance of the roof drill including drilling speed, safety, and tool life. The drilling process can be improved while also improving operator safety and reducing bolt installation costs by maintaining the appropriate roof drill settings for the specific strata conditions.The advantages of improving the drilling process includes increased bit life, increased drill steel life, reduced hanging drill steels, reduced clogging of the vacuum system, decreased whipping drill steel potential, reduced noise generation, and increased cutting size which reduces fine dust generation and dust collection system servicing.INTRODUCTIONIn recent times, the economic pressures that coal producers are facing have created an increased emphasis on controlling operating costs. Several coal operators have pointed out their dissatisfaction with low bit life, and there is a renewed interest in improving tool life and machine performance as part of an overall cost control strategy. Operators are looking for ways to reduce tooling cost, maintenance costs, and drill downtime without decreasing drill performance. This renewed interest in reducing operating costs, along with the ongoing desire to improve safety, created a perfect environment to take a fresh look at the existing fleet of machines to see what could be accomplished. The goal was to take a practical approach to reviewing machine parameters to determine what changes could be made. The emphasis was on changes that would be feasible to roll out to an entire fleet of machines in a short period of time with minimal capital expenditure. The thought process was that significant improvements could be made by simply tuning up the machine parameters to provide a more efficient and safer bolting process."

Jan 1, 2015

By Bill S. Taylor

Dutch State Mines [D.S.M] introduced the Heavy Medium Cyclone into the United States for cleaning fine coal about three decades ago. Since that time the general industry practice has been to deslime the raw coal at 28 Mesh (0. 59mm) size. The plus 28M material is fed to the Heavy Medium Cyclone for cleaning, and the 28M x 0 fraction is processed by other means (e. g. flotation or hydrocyclones). This approach recognized that 28M was the smallest size particle that could be easily rinsed on vibratory screens without excessive loss of magnetite, and without blinding of sieve bend and vibratory screen decks. Another reason for the 28M de-sliming was to avoid excessive contamination of the media with non-magnetic coal, shale, or clay fines. The most undesirable of these contaminants is the sub-micron size clay particles (2) that greatly increase the viscosity of the media and reduce the numerical maximum level that the media specific gravity can obtain due to the lower specific gravity of clay with respect to magnetite. The higher the fugitive clay content, the more severe the preceding problems become. During the last 30 years, many conventional Heavy Medium Cyclone Plants have been built throughout the world. In the United States, the initial cyclone plants were confined to the production of high quality metallurgical coal where lower gravities of separation were required than could be obtained from the conventional hydraulic or air separation processes. In recent years a large and ever-increasing number of preparation plants producing steam coal have started utilizing Heavy Medium Cyclone technology due to the environmental pressures being encountered to produce low sulphur coal. Due to the inherent characteristic of many coals of having a lower pyritic sulphur content at lower specific gravity fractions, many applications and markets are appearing for separating steam coals at much lower specific gravities than have been historically normal in the United States. Therefore. Heavy Medium Cyclones are being utilized to a much greater degree in this field, due to the flexibility of low separating gravity ability coupled with high efficiency when high percentage of near gravity material is present.

Jan 1, 1978

By A. Policard

The question, of the pathogenesis of pneumokoniosis is very important not only from the social and economic points of view but also from the purely biological. The study of the pathogenesis of the disease leads to fascinating problems of cytology and cytochemistry. Two problems present themselves for examination from an analytical and critical point of view: 1. The first reactions of the alveolar walls to inhaled dusts. 2. The precise nature of the action of mineral dusts.

Jan 1, 1947

By R. Hurman Eric

The electrode in a slag-resistance electric furnace is the central factor in the design and operation of the furnace by its role of conveying the smelting power, i.e. heat needed for the operation. The control parameters are the size and positioning in the slag bath which are defined by slag resistivity, furnace resistance, cell constant and power input sequence all of which are closely interrelated. The flow of heat generated by the electrode current determines the energy distributions and thus the furnace dimensions. Heat flow models concerning vertical, horizontal and combined two-dimensional flows are discussed. All these considerations are based on the experimentally determined slag properties such as its resistivity.

Jan 1, 1995

Bendigo Mining operates a 600 000 t/a comminution, gravity, flotation and leaching processing plant for the recovery of gold from their Kangaroo Flat Operation, in the Bendigo goldfields. The free gold and gold bearing sulfi des present are typically coarse grained and hence are highly amenable to gravity recovery. Plant operating data is consistently showing that over 78 per cent of the feed gold is recovered in a circuit, consisting of inline pressure jigs, inline spinners followed by free gold tabling and intensive leaching of tabling tails. The circuit receives coarse crushed product from high pressure grinding rolls and the grinding mill discharge, which allows material to be re-circulated through the gravity process until the particles are small enough to enter the flotation circuit. A plant audit was completed on 26 November 2009 designed to give an indication of the overall operational characteristics of the gravity circuit including single pass efficiencies of associated equipment. The techniques, results and challenges of such a survey are discussed.

Aug 1, 2010

By G. ALBORNOZ, S. Utili, A. AGOSTI, C. VALDERRAMA, R. PELL, N. Morales

The steepness of the slopes of an open pit mine has a substantial influence on the financial return of the mine. The paper proposes a novel design methodology where overall steeper pitwalls are employed without compromising the safety of the mine. In current design practice pitwall profiles are often planar in crosssection and the profile in between ramps especially tend to be planar and defined by a constant inter-ramp angle. Sometimes rock layers exhibiting different strengths require the inclination of the profile to vary with depth, but the inclination across each layer is usually constant. Here instead, a new geotechnical software, OptimalSlope, is employed to determine optimal pitwall profiles of depth varying inclination. OptimalSlope seeks the solution of a mathematical optimization problem where the overall steepness of the pitwall, from crest to toe, is maximized for an assigned lithology, geotechnical properties and Factor of Safety (FoS). Bench geometries (bench height, face inclination, minimum berm width) are imposed in the optimization as constraints which bind the maximum local inclination of the sought optimal profile together with any other constraints such as geological discontinuities that may influence slope failure. The obtained optimal profiles are always steeper than their planar counterparts (i.e. the planar profiles exhibiting the same FoS) up to 8 degrees depending on rock type and severity of constraints on local inclinations. The design of a copper mine is first carried out employing planar pitwalls, secondly adopting the optimal pitwall profiles determined by OptimalSlope. The adoption of optimal slope profiles leads to a 34% higher net present value and reductions of carbon footprint and energy consumption of 0.17 Mt CO2 eq and 82.5 million MJ respectively due to a 15% reduction of rockwaste volume.

Mar 2, 2022

By R. L. Grayson

Evidence has accumulated indicating that cultural change toward safer workplace behaviors is beginning to occur systematically in the coal industry. Through a range of programmatic mining company successes, enforcement and litigative actions, economic responses to competition, and integrated efforts by federal and state agencies, a broader participation of safety and training professionals is being achieved to address prioritized workplace problems at mines. Small steps in workplace-related improvements have been realized already, but the trends in industry safety statistics, coupled with focused programmatic initiatives, indicate that more definitive and systematic steps are occurring to improve safe behavior in the workplace routinely.

Jan 1, 1996

This volume constitutes the final report for the Rescue Subsystem portion of the Coal Mine Rescue and Survival System program conducted by the Westinghouse Electric Corporation under contract to the United States Bureau of Mines (Contract Number H0101262 dated Jung 17, 1970). The program was directed by the Special Systems Department of the Westinghouse, Baltimore, Maryland facility. The basic objectives of the CMRSS program were to develop and test hardware to determine the efficacy of a variety of coal mine rescue and survival concepts and techniques. These concepts were drawn from two major- sources: the Request for Proposal from the Bureau of Mines and the final report on the Mine Rescue and Survival Study conducted by the National Academy of Engineering (NAE).

Jan 1, 1971