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By AIME AIME

N EARLY 1300 members and guests crowded the halls of the Engineering Societies Building during the winter meeting of the Institute just closed, and more than 600 attended the banquet. In variety of program, quality of papers, interest in discussion, and brilliance of social features, the meeting maintained the high reputation of the past. Nothing elaborate in the way of excursions was attempted, experience having proved that February weather in New York is much too uncertain to warrant extensive field trips. A sight-seeing journey up the Hudson to the Bear Mountain bridge was, however, made despite the snows of the week before and the week after. The annual business meeting, while attended by a minority of the members in the building, was marked by the display of keen interest in the work and called out several interesting discussions. The excellent reports of the committees that had organized their work and directed it along definite lines, emphasized the need of funds with which to support assistants or Fellows who shall correlate and put to the highest use the facilities of the Institute in research along technical lines. This thought was developed at the banquet by the retiring president, J. V. W. Reynders, and it is expected that the Directors will take early steps to collect a fund for this purpose. The number of the individual sessions was too great and the papers and discussions too numerous to permit mention here of all the features of inter- est. A general review only follows. The papers and detailed discussions will be printed and sent to members as promptly as possible.

Jan 1, 1926

At Pasminco Mining's South concentrator. which was commissioned in 1952. an expansion. modernisation and efficiency improvement program commenced in 1986 with a coarse ore stockpile and grinding circuit expansion. the replacement of small flotation cells and the upgrading of reagent mixing and metering equipment. The program continued with the installation of a TDC 3000 based process control system (1988) and concentrate thickeners (1990). By mid-1991 a further grinding expansion and the installation of zinc flotation feed regrind ball mills and zinc recleaner column cells will be complete. leaving the use of ceramic disc fillers and development of process control strategies as probably the remaining major avenues for improved process efficiency at present.

Jan 1, 1991

By John Mould, Gordon Chen, Michael Oakland, William McElwee

"This paper will discuss the design analysis of sheet pile cofferdams for static and dynamic blast loads. Following construction of the new Willis Avenue Bridge across the East River between Brooklyn and Manhattan, in-river piers No. 9 and No. 10 from the former bridge were demolished, partially by explosive charges. The blast at Pier 10 was conducted first and though the demolition charge was relatively small, it gave confidence that the sheeting could be designed to resist the blast load. This paper primarily summarizes our analysis and performance of a sheet pile cofferdam at Pier 9 used to withstand the larger blast loads, contain the blast debris, and allow excavation of the pier below the existing river bed mudline. The program NLFlex was used to predict stresses and deformations of the cofferdams under dynamic blast loads, using simplified equations to estimate the underwater blast pressures. Specifically, the analysis focused on the stresses in the struts, waler beam, sheet pile interlocks and connection of the sheeting to the waler beam. Design included allowing plastic deformations and limited rupture of the sheet pile interlocks under the blast loading. Comparisons are made between stresses assessed by the dynamic finite element modeling and empirical relationships used within the industry. The performance of the system after the actual blast is discussed as well as details of the performance of welded vs. bolted connections within the system. IntroductionThe Willis Avenue Bridge is one of the major access ways from the Bronx into Manhattan. The location is shown on Figure 1. The original bridge constructed in 1901 was a swing bridge over the East River. The bridge was in disrepair and outdated with regards to its ability to handle the flow of traffic resulting in numerousaccidents.In 2007, Kiewit Constructors Inc./Weeks Marine, Inc., A Joint Venture was selected to construct a replacement bridge. The $612 million project included construction of a new bridge just to the south of the original bridge. The most notable aspect of the construction was floating and lifting the new 350 ft. long swing span in place as a single piece. However, another significant challenge was using blasting to demolish two of the abandoned piers which were within the East River. The blast would be near existing structures in both Manhattan and Brooklyn and would be within 30 ft. of the new bridge."

Jan 1, 2017

By Fabio Mielli

The mining industry is a multifaceted industry with special characteristics that make efficient and intelligent operations uniquely challenging, and subsequently call for distinctive and tailored solutions. Not only does mining call for processes that are complicated and energy intensive, but complex material movements and an intricate logistical chain add to the industry?s obstacles in achieving sustainability and performance. This article explores three major challenges and the resulting issues currently being faced in the industry, as well as potential solutions to these impediments by use of energy management, automation and control strategies.

Jan 1, 2011

By Bernard Hertlein, Chia K. Tan

"The move to LRFD methods for structural design by AASHTO, ACI, AISC , ASCE, and the FHWA has been a major change for the American construction industry. The deep foundations industry has arguably been placed most at risk by this situation, because of the need for, and the difficulty of providing, reliable quality assurance.LRFD is attractive for both the owner and the engineer because it promises cost reductions, but the assumption underlying LRFD is often overlooked - that the acceptable margin of safety can be rationally reduced, thus saving costs, provided that all the factors involved are closely controlled. This means that both the quality of the materials and the quality of the construction work must be closely monitored, and held to an acceptable standard.This paper describes the type of comprehensive quality management program that is needed in deep foundation construction projects based on LRFD. Case histories are used to illustrate the importance of both adequate inspection and reliable testing to a comprehensive quality management program.IntroductionOver the last thirty years, the major organizations that set standards and practice policies for the American construction industry, such as the American Association of State Highway and Transportation officials (AASHTO), the American Concrete Institute (ACI) , The American Institute for Steel Construction (AISC), the American Society of Civil Engineers (ASCE), and the Federal Highway Administration (FHWA), have embraced Load and Resistance Factor Design (LRFD) as an alternative to, and in some cases, a complete replacement for, Allowable Stress Design (ASD). AASHTO first published a new set of LRFD-based design guidelines for bridges in 1996, with several revisions in 1997, 1998, and 1999 (AASHTO, 1996). The 1996 AASHTO Bridge Design Code was the first in the United States that required foundations to be designed using LRFD procedures. LRFD has a clear advantage over conventional ASD where variability in material strength, bias in design methodology, and degree of construction quality can be rationally accounted for to achieve an acceptable level of risk."

Jan 1, 2005

By D. W. Blaylock

1. The Lower Freeport and Lower Kittanning beds are the most important beds in Clearfield County, Pa., from the standpoint of production. The Lower Kittanning bed has the largest remaining recoverable reserves of any of the beds in the county. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and 1,800 short tons per acre-foot of coal in place, are estimated at 1,909 million short tons as of January 1, 1953. Of this total, 1,177 million short tons is in beds 28 inches and more thick. Areas in some beds were omitted from the estimate because available data relative to the bed characteristics are too meager to make an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.

Jan 1, 1955

By Derrin A. Auerswald, Jacolien P. Wyethe, Nanne M. \/egter

Base and precious metal refineries often produce effluent solution and slurry streams containing between 50 mg/L and several grams per liter of base metals. Metals have historically been precipitated from these streams with lime to produce effluent streams at pH values between 8 and 9. This effluent treatment process generally does not remove alkali and alkali-earth metals or halides efficiently and with more stringent environmental legislation, more sophisticated effluent treatment plants must be considered which could for example incorporate sulphate removal with ultra-filtration, or the SavminTM process, followed by reverse osmosis for the removal of halides. The flowrates of effluents are often high and if base metals can be recovered before neutralization, the revenue generated from this stream can reduce the cost to produce clean water significantly, and in the case where high concentrations are disposed of, result in a profitable operation. As an add-on to an existing the plant the recovered metal is upgraded and recycled to the plant, but the production of a saleable metal can also be considered. Technology selection for metal recovery depends on the composition and flowrate of the effluent, but could incorporate resin-in¬pulp or other ion-exchange technology; precipitation as sulphides, hydroxides or carbonates; or solvent extraction. This paper describes, as a case study, the technology selection process and uses data from Zincor. Zincor is a division of Exxaro Base Metals (Pty) Limited, a subsidiary of Exxaro Resources Limited.

Jan 1, 2011

This Bureau of Mines publication presents five papers given at a Technology Transfer Seminar on Metal Mine Fire Protection Research. Several seminars are held each year to bring the latest results of Bureau conducted and sponsored research to the attention of the mining industry as quickly as possible.

Jan 1, 1977

By M. A. Mekicha, M. B. de Rooij, C. Pelletier, D. T. A. Matthews

One of the main factors that reduce strip cleanliness are iron fines, which are formed due to the abrasive interactions of the roll surface and the strip in the roll bite during cold rolling. They can cause a problem in fouling of the cold rolling mill as well as downstream processes. It has been repeatedly observed that chrome plating the work roll improves strip cleanliness. In the present work, scratch tests and reciprocating sliding tests were carried out under lubricated conditions to explore the influence of chrome plating on iron fines formation. Scratch tests were conducted to study the influence of chrome plating on iron fines formation at single asperity scale due to its intrinsic property. Reciprocating sliding tests were performed to study the influence of chrome plating a rough surface on iron fines formation, taking into account the initial roughness. The scratches made using chrome plated pins showed lower friction, generated less iron fines and exhibited lower material transfer. Reciprocating sliding tests done using the uncoated pins showed galling at different sliding distances depending on the roughness of the pin. On the contrary, reciprocating sliding tests with the chrome plated pins exhibited no galling irrespective of the roughness.

Oct 1, 2019

By A. Visnapuu

The Bureau of Mines has upgraded high-iron domestic chromite concentrates by a carbonyl process. The upgraded chromite concentrates show as much as 10 wt pct higher Cr203 content and up to a threefold in-crease in the Cr:Fe ratio, compared with the starting concentrates. The high-iron chromites were first reduced to convert the iron oxides to the metal, and then treated with CO at elevated pressures and low temperatures to convert part of the metallic iron fraction to iron pentacarbonyl. Carbonylation was accelerated by the addition of H2S in small quantities. The iron pentacarbonyl was extricated from the con-centrate in the pressure reactor during carbonylation by a CO sweep through a pressure-reducing valve and passed through a decomposer at atmospheric pressure to convert it back to iron metal and CO. CO pres-sure, temperature, promoter trends, and other factors enhancing iron pentacarbonyl formation are presented.

Jan 1, 1985

By Edward W. Parker

Note.—The material from which this paper has been prepared was collected tor the U. S. Geological Suvey Bulletin, No. 316, Contributions to Economic Geology, 1906, and appears also, though in somewhat more extended form without illustrations, in that publication. Although the briquetting of coals and lignites has been carried on for many years in Europe, and has reached a particularly high state of development in France, Belgium, and Germany, it has made comparatively little progress in the United States. The causes for the backwardness of the United States in this regard are several, and first among them has been the abundant supply of cheap raw fuel with which the manufactured article has to compete. With our millions of acres of coal-productive territory, from which the product can in moat cases be cheaply extracted, it has appeared in many districts more economical to waste the slack or culm, which constitutes a considerable percentage of the product, than to attempt to save it at the additional expense required for briquetting. It is for this reason that the view in all sections -of the anthracite-region of Pennsylvania is marred by the unsightly culm-banks which encumber the ground, and that in some of the bituminous-districts one sees huge piles of unmarketable slack allowed to burn up in order to get rid of them. When the coal is of a coking quality, or when the slack can be used for steaming-purposes, these losses are not sustained, but many thousands of tons of what might be converted into usable fuel have been wasted every year simply because of the increased expense involved in its preparation.

Jan 1, 1908

By A. A. Wessels, D. P. Allison

"Mine hoists are built to handle a certain nameplate capacity; they are specified and designed according to the required duty. However, as production capacity increases in other parts of an operation, the hoist capacity can become the critical constraint. Such a situation occurred at Lundin Mining’s Neves-Corvo operation. This paper examines how each component of the existing hoisting system was examined and optimized. Through a combination of engineering study and hoist simulations, the annual hoisting capacity was improved by 24% through increases in payload capacity and available hoisting time combined with a reduction in cycle time, while no changes were made to the hoist motor, drum or headframe. The additional payload capacity was achieved by reducing the mass of the hoist ropes and skips, and improving load monitoring systems. The cycle time was reduced through the shortening of the creep distances and increased availability through the installation of a shaft collar safety platform, alternative guide rope bushes, and superior liners for both the skips and underground measuring flasks. Enhanced cooling of the hoist electrical system was also incorporated to increase hoist availability by reducing downtime during hot summer months. The changes will increase the capacity from the current 4.5 mega tonnes per annum (Mtpa) to a planned 5.6 Mtpa and are being implemented over a 2-year period whilst maintaining the mine production during the upgrade work. INTRODUCTION Neves-Corvo Mine Neves-Corvo is primarily a copper and zinc mine producing copper, zinc and lead concentrates. The operation is owned and operated by Somincor, the Portuguese subsidiary of Lundin Mining. Located in the Alentejo district of southern Portugal, the operation is situated approximately 15 km southeast of the town of Castro Verde, where summer temperatures can reach as high as 45ºC, and approximately 220 km southeast of Lisbon. The principal means of mine access is via a ramp from surface, with the vertical shaft used to hoist ore and waste from the 700 m level, while conveyors descend from the 700 m level to transport ore and waste up from the deeper levels of the mine. The mine is highly mechanized and several different stoping methods are employed, with the most significant being bench-and-fill and drift-and-fill. The Neves-Corvo mine currently exploits five orebodies: Neves, Corvo, Graça, Zambujal and Lombador for copper and zinc-lead ores which are processed in one of two plants. All the orebodies are currently exploited over their full elevation with the exception of Lombador which is only mined down to the 220 m level, approximately the top 50% of the orebody, known as Lombador Phase 1."

Jan 1, 2019

By B. J. Arnold, F. F. Aplan

Prior laboratory work has demonstrated that much of the fine ash forming minerals entering a flotation froth are there as a result of water carryover- from the bulk contents of the flotation cell (Arnold and Aplan, 1986a). Using a bank of four 8.5 m3 (300 cu ft) Wemco flotation cells cleaning a well-liberated Lower Kittanning seam coal, test results show that the sulfur and ash content of the froth is directly related to the water content of the froth (or inversely related to the percent solids in the froth). Reagent changes that result in a watery froth produce a higher ash content in the froth. A direct comparison of laboratory and plant results show that the standard laboratory flotation test produces a product higher in sulfur and ash than that produced in the plant. Caution should be exercised when extrapolating laboratory test results to the plant situation. A method of estimating coal flotation product quality in the plant based on laboratory tests is given.

Jan 1, 1991

By Brianna Eiter, Max Barham, Tim Bauerle

Fatigue-related risk is a persistent safety concern for the mining industry. However, fatigue and sleepiness are often treated interchangeably, which can lead to confusion and potentially less effective reduction of safety risk. To provide clarity, we present an overview of similarities and differences between work-related fatigue risk and sleepiness including definitions, theories, measurements, and mitigation strategies. As a supplement, a summative visual model which highlights these similarities and differences is presented. Expanding industry knowledge in this area will assist safety professionals in crafting more targeted risk management practices appropriate for work-related fatigue risk, sleepiness, or both.

Dec 19, 2023

By J. S. Contreras, E. Córdova, I. Gottreux, A. Anani, A. Ferrada

Cave mining is an underground mass mining technique. The largest projects, which are known as ‘super caves’, produce hundreds of thousands of tons of ore per day, which involves large footprints with considerable column height, and have a life of mine of over 20-40 years. These operations are typically located deep, under high stresses and in competent rock masses, making initiation and propagation of the caving process harder to manage. These challenges must be confronted by optimizing the fragmentation of the orebody to achieve smaller size blocks that will result in consistent caving and improved flow of the ore from the drawpoints. To achieve better performance from the drawpoints, preconditioning is applied to fragment and damage the material required to cave. We present a proposed design for preconditioning in underground mines, considering the challenges that these large-scale mines are already facing, based on a comprehensive analysis of current design parameters, case studies, and sensitivity analyses using numerical models.

Feb 2, 2021

By M. D. Flavel

My paper relates to bond's third theory of comminution and suggests work be used as a basis for designing crushing and screening plants, this will give more accuracy than existing methods, As stated in the abstract, this paper is only a synopsis of my official paper, many of the questions that might arise in this brief address will be answered by referring to the detail i n the main paper $ Because of the limited time available and the fact that many people here do not need to study the aspects of crushing and screening in depth, i will highlight-those sections of the paper which show how major capital, operating and energy cost savings can be achieved in the process, I will develop the theme in the following manner, Firstly, pointing out, why a new approach is needed to the fundamentals of crushing and screening, Secondly, by setting forth some theory to describe what we are trying to accomplish, Thirdly, by looking at important factors which need to be observed in designing plants and applying machines to comply with this theory, Lastly, i will put forth some ideas on how we might develop this theory to make the industry more efficient, At the outset, i have to say my approach to this process is entirely new, for those used to applying machines and designing plants on existing criteria, they will find this theory easier

Jan 1, 1977

By Pat McCarran

WHEN this Government was founded, the framers of the Constitution wrote into that instrument a provision that Congress should "coin money and fix the value thereof;" and the Constitution prohibits making anything but "gold and silver" lawful money. So silver is written into our basic law. Shortly after President Washington took office in 1789 the Congress passed the first Mint Act, setting up the U. S. Mint. In that Act, signed by President Washington on April 2, 1792, the weight of the American dollar was fixed, and it was provided how much silver should be contained in a silver dollar and how much gold should be contained in a gold dollar. It was decided that 371 1/4 grains of pure silver was to be the standard dollar of America. That standard with respect to the pure silver content of the dollar has never changed.

Jan 1, 1947

By B. Eiter, M. Barham, T. Bauerle

Fatigue-related risk is a persistent safety concern for the mining industry. However, fatigue and sleepiness are often treated interchangeably, which can lead to confusion and potentially less effective reduction of safety risk. To provide clarity, we present an overview of similarities and differences between work-related fatigue risk and sleepiness including definitions, theories, measurements, and mitigation strategies. As a supplement, a summative visual model which highlights these similarities and differences is presented. Expanding industry knowledge in this area will assist safety professionals in crafting more targeted risk management practices appropriate for work-related fatigue risk, sleepiness, or both.

Feb 1, 2023

By Bernard P, Lhoumaud E, Gunzburger Y, Conin M, De Santis F, Kinscher J

Seismic repeaters are commonly observed in natural fault zones dominated by slow aseismic motion. The corresponding seismic signal, characterized by highly similar wave forms, is usually interpreted as the repeating ruptures of locked asperities on fault planes (“patches of higher roughness”), loaded by a-seismically slipping areas (“creeping areas”) (Chen & Lapusta 2009; Bourouis & Bernard 2007). Only very few occurrences of seismic repeaters have been reported in underground mines, where these phenomena are rather unexpected since the stress state and the seismic wave propagation continuously evolve with the advancing excavation front (Kinscher et al., 2020). A recent study based on a local seismic network installed in the underground mine of Garpenberg, Sweden, has shown that seismic repeaters and multiplets represent the main part of the total released seismic energy (magnitude of seismic events: -2 < M <1, on moment magnitude scale), with some seismic families being active during several months to years. It is suggested that repeaters are linked to aseismic slip on pre-existing talc-filled fractures, induced by the excavation, and loading of asperities. These results imply that part of redistribution of stresses in the mine is due to aseismic slip, which might explain the observed distant and delayed seismicity.

Apr 26, 2022

By Rafael Colás

Computer visualization can be employed in industry as an aid to the understanding of the complex interactions between variables encountered in production. The examples of ingot casting of rimming steel and that of hot rolling of low carbon steel strip are presented. Both processes are mathematically modeled, and their results are presented in a graphical way. Such models have been proven to be an asset in quality improvements and increase of productivity as the personnel involved get a better understanding of their job.

Jan 1, 1993