Search Documents

By L. Don Leet

Abstract Earthborne vibrations from blasting and other sources, including rock bursts, can now be recorded effectively. The nature and magnitude of vibrations from various sources have been investigated and certain applications of the knowledge thus gained have been made. Vibrations from blasting have been measured on special equipment over a range from an electric blasting cap at a few feet, through the largest quarry shot in history to date ( 1,-362,985 lb.), to the first atomic bomb, in uew Mexico on July 16th, 1945. Laws relating amount of explosive to amount of vibration at different distances have been developed and tested. Special studies have been made of the effects of vibrations on buildings, particularly from the standpoint of possible structural damage. Recorded vibrations are used to study the effects of modern short-period delay shooting. It ?has been found that short-period delay firing is extremely effective in reducing vibrations under the right conditions, but with certain limitations. In quarry shooting, there appears to be a minimum number of holes below which vibrations are not appreciably reduced by short-period delay firing. In several instances this minimum has been near 7. Vibrations in the ground from rock bursts and the effects of mining in stresesd ground have been studied both underground and on the surface in a search for a rock burst warning system. Introduction Earthborne vibrations from blasting and other sources, including rock bursts, can now be recorded effectively. Analyses of blasting records have been yielding increasing funds of information of practical as well as theoretical interest. The nature and magnitude of the vibrations have been investigated with special reference to their effects on structures.

Jan 1, 1951

Perform laboratory tests to measure the vibration attenuation characteristics of off-road vehicle operator seats for various types of seat suspensions, cushions, and seat adjustment settings. Background A study was conducted by the U.S. Bureau of Mines to determine the probability of whole-body vibration (WBV) exposure for a large class of off-road machinery operating in surface coal mines. The study determined that mere than 40 pct of off-road equipment operators were exposed to WBV exceeding the standard fatigue-decreased-proficiency (FDP) level defined by the International Standards Organization in its guideline ISO standard 2631. The tire-terrain interaction of a moving vehicle generates vibrations that are transmitted through the ve¬hicle suspension, cab mounting, and seat. The final point of transmission of vehicle vibration to the operator is through the scat. A seat that provides good vibration isolation and allows good vehicle control is of prime importance to operator safety and health.

Jan 1, 1993

By Vibration Research Group, Natasha K. Lee Shee, Tammy R. Eger, James P. Dickey, Paul-Émile Boileau, Lana M. Trick, Michele L. Oliver

Introduction Industrial exposure to whole-body vibration is associated with injury and discomfort. Certain industries, notably mining, construction, and forestry, involve complex 6 degrees of freedom vibration. Laboratory-based studies of vibration are essential for controlled and systematic evaluation of the human responses to vibration2. The purpose of this pilot study was to evaluate whether the duration of the vibration exposure, and rest between vibrations, significantly influence the subjective ratings of comfort during laboratory-based studies of vibration. Methods Subjects: The cumulative vibration dose was calculated, and was below the health guidance caution zone recommended by International standards3. The experimental procedures were approved by the University of Guelph Research Ethics Board. Ten adult subjects participated in this pilot experiment. All subjects completed the entire experimental paradigm; no subjects complained of pain during or after the experiment. Experimental Design: The experiment consisted of four blocks of vibration exposures; either 15 or 20 seconds of vibration (1 df:Z axis, 3 df:XY plane, 3df:YZ plane, or 6 df) alternating with either 5 or 10 seconds rest. The order of presentation of the four blocks was randomized. Each of the blocks was composed of 37 individual sinusoidal vibration exposures in randomized sequence. This abstract focused on ten identical trials, (6.3 Hz vertical vibration, 0.55 m/s2 RMS) interspersed within each block, in order to assess whether the subjects’ comfort ratings systematically varied between the 15 or 20 vibration exposures, the 5 or 10 second rest between vibrations, or within each block. The experiment involved 43 minutes of vibration within the 62 minute experiment. Vibration Apparatus: A commercial parallel robotic platform was used to apply the specific vibration exposures (R2000, Parallel Robotics Systems Corporation, Hampton, New Hampshire). The subjects sat on a passenger seat from a 1992 Honda Accord that was rigidly mounted to the robotic platform (Figure 1). This robotic system performed the specific vibration exposures operating under closed-loop displacement control. A custom-written Matlab program automated the testing sequence.

Jan 6, 2006

By Paul McAnuff, Alastair Grogan

In Canada, the only vibration regulations which apply across the entire country are intended to protect fish spawning areas. The Provinces and Territories regulate mines and quarries, and are responsible for setting vibration and airblast regulations. Some Provinces have set specific regulations, while others leave these restrictions to the mines inspectors who can set limits on a case by case basis. For the most part, it is left to individual municipalities to regulate blast vibrations and airblast from other blasting activities, which differ from jurisdiction to jurisdiction, and in some cases are not enforced. Blasters working in different jurisdictions have to be aware of the applicable regulations for the area they are working.

Jan 1, 2005

By S. Doombos

To convert the railway-bridge across the Oude Maas between Dordrecht and Zwijndrecht into a vertical lifting bridge, a drastic adaptation of the existing piers is necessary. Extra piles have to be placed quite close to the present piers to bear the extra weight of lift-towers and bridge-sections. This article describes the special technology applied to drive steel tubular piles l800 mm. in diameter and 36 m. in length vibration-free into position. At the same time a method of pile-point-reinforcement has been applied to minimize the settlements.

Jan 1, 1989

By Goran Lande, Bernt Larsson, Dennis Clark

The effects of vibrations on close surroundings has been studied in Europe and the United States extensively in the past three to four years due to the ever increasing demands of environmental control. Therefore, "routine measurements" or "standard vibration consulting services" are being carried out by numerous firms with widely different qualifications.

Jan 1, 1983

By L. A. Vaisberg, E. V. Shishkin, S. V. Kazakov

"This research is targeted at finding solution to the problem of reduction of specific energy consumption during disintegration of solid materials with the help of machines, operating in a quasiresonant mode. The objective of the research is the development of an energy-saving method of disintegration of supestrong rock and by-products on the basis of vibrational units with two movable crushing elements, operating in a rigorous synchronous-antiphase mode without stringent kinematic links. In the course of investigations a mathematical analysis of the dynamics of vibrational units was performed to determine required mechanical parameters, allowing for adjustment of the machine actuating elements to high-frequency synchronous-antiphase oscillations in the quasiresonant frequency range. As a result of performed pilot tests, the reliability of desktop studies was confirmed and the dependency of process parameters on the machine regulated parameters in the quasiresonant frequency range was identified. The analysis of obtained data showed that during machine operation with cone-shaped crushing elements in the quasiresonant frequency range, the yield of the high-quality finished product (WFA grits of -3+1 mm grain size class) in one pass reaches 35%, whereas the form of the particles corresponds to the grain form with sharp edge. The quasiresonant operation mode of the vibrational unit with two freely suspended crushing elements (without stringent kinematic links) provided substantial reduction of energy intensity during crushing down to 0.16 kWh/t, which shows reduction of power consumption for crushing by more than 15% compared to conventional equipment.INTRODUCTION The most common and energy-consuming processes in the mining industry are the crushing and grinding of various solid materials. Such large energy costs are due to the fact that the capabilities of the existing crushing and grinding machines are based on traditional methods of destruction, and are limited by their kinematic features, which do not allow to reduce the energy intensity of processes, to lower the irreversible loss of useful components, to improve the quality of marketable products. In connection with the foregoing, the task of energy costs reducing for disintegration is one of the most important issues in the enrichment of both minerals and processing of man-made raw materials. The solution of this problem is possible only through the creation of a fundamentally new highly efficient technique and technology for processing raw materials [1, 2]. It seems that the greatest prospects in this respect are the vibration methods of disintegration, in particular, the vibratory cone crusher based on a two-mass system without rigid kinematic connections between the crushing bodies, with vertical vibrations of the working bodies. In this machine, the principle of rational material destruction is realized – crushing without re-grinding [3-5]."

Jan 1, 2018

By B. Culkin

The production of fine particle products within the mineral processing industry is a very important market segment. Many of these products are processed in an aqueous state and must ultimately be dewatered. This entails processes which are very energy and capital intensive. The introduction of membrane based dewatering systems has offered great promise in the area of energy saving and operating costs. Unfortunately, membrane separators have not yet had the ability to handle high solids. New Logic introduces a system which can concentrate a low solids stream to a high solids sludge in a one pass, very energy efficient system.

Jan 1, 1993

By K. Rainer Massarsch

"Part 2 of 2 (Continued from Summer 2004 edition) By K. Rainer Massarsch, Geo Engineering AB, Stockholm, SwedenVibrations, which are caused by the installation of piles in dry or permeable soils, can cause settlements. The magnitude of settlements depends on several factors, such as soil type and stratification, ground water conditions (degree of saturation), pile type and method of pile installation (driving energy). A method of settlement prediction due to construction-induced vibrations has been presented by Massarsch (2000). However, in many cases, an engineering assessment must be made at an early stage of a project. The following simplified procedure can be used to estimate settlements in a homogeneous sand deposit adjacent to a single pile, Fig. 5. This approach is based on extensive experience from soil compaction projects. It is assumed that intense densification due to pile penetration occurs within a zone corresponding to three pile diameters. The volume reduction resulting from the propagating vibrations will cause settlements in a cone with an inclination 2V:1H, with the tip at a depth of 6 pile diameters. Thus the settlement trough will extend a distance of 3D+L/2 from the centre of the pile, with maximum settlements at the centre of the pile. Maximum settlements, Smaxand average settlements, Smax can be estimated using the following relationship, choosing an appropriate a value of the soil compression factor, from Table 2.The driving energy depends on the method of pile installation, soil stratification and the pile type. The displacement volume of the installed pile has been neglected. The simplified method is applicable for estimating settlements at the perimeter of a pile group. It should be noted that settlements also occur outside the assumed cone, but these are often negligible. The effect of incompressible layers should be taken into account by adjusting the effective pile length."

Jan 1, 2004

By K. Rainer Massarsch

"Part 1 of 2 By K. Rainer Massarsch, Geo Engineering AB, Stockholm, SwedenINTRODUCTIONConstruction activities, such as driving of piles and sheet piles, soil compaction or excavation generate noise and vibrations. In populated areas these can have a negative impact on the environment, disturb inhabitants and, under unfavorable conditions, cause damage to buildings and installations. This condition is aggravated by the growing public awareness of environmental issues and the increasing use of vibration-sensitive electronic equipment and machinery in industry. In many countries, environmental regulations are enforced more stringently and limit or even prohibit the use of impact or vibratory hammers. This development has restricted the use of cost-effective foundation methods, such as driven and vibrated piles and sheet piles.Vibration problems are gaining importance in many European countries and extensive research has been performed during the past decade, especially with respect to traffic vibrations (Massarsch, 2004). Significant progress has been made owing to the availability of high-quality field measurements and an improved theoretical understanding of how vibrations are generated and transmitted through soil layers. These findings can also be applied to vibration problems associated with construction activities. However, this information is not yet appreciated by the geotechnical profession and even less by the construction industry.This paper discusses the effects of ground vibrations on the surrounding soil and on buildings, with particular emphasis on the different mechanisms of damage that may occur. Guidance is given on the elements which should be taken into account in an assessment of risks associated with piling projects. A simplified method is proposed for assessing the risk of settlements or strength loss in soil deposits. Limiting vibration levels are presented, based on the Swedish standard, which can be used to assess the risk of damage to buildings. Aconcept to predict ground vibrations caused by pile driving and the mechanisms which control the propagation of ground vibrations, will be presented in the second part of this paper."

Jan 1, 2004

By David Siskind

The authors studied small seismic exploration blasts for vibration characteristics and effects on structures in Mexico. Obtained were 267 three-component recordings of ground vibrations and structure responses from 62 test blasts at six single-story masonry structures. Charges were 4.55 kg (10 lb) of Vibrogel expolsive at depths of 20 and 30 meters. Initial blasts were 240 meters distant and proceeded towards the structures to as close as 5 meters. All blasts were in soil media in two basic types of terrain, low saturated areas and upland dry areas. Structural inspections were before, during, and after the test blasts.

Jan 1, 2002

By John L. White

Vibratory driver/extractors do more than drive and extract sheet piles. I would say more than sixty percent (60%) of the time, vibratory pile driver/extractors are engaged in work that has nothing to do with sheet piles. This is the main reason I refer to this tool as a "driver/extractor", and omit the word "pile". I have spent the last twenty years applying the technology of the vibratory driver/ extractor to all areas of foundation construction. As you will see, the only limits are humankind's ingenuity.

Jan 1, 1997

By M. Bilal Khan

Thermal stress relief by means of a typical heat treatment cycle (660oC for one hr) is compared with the one achieved through vibratory stress relief at resonant and multiple resonant frequencies for the D-406 HSLA material. Our analysis of the data is based on the microhardness profiles measured for the entire length of scales, namely, base metal, heat affected zone (HAZ) and the weld bead itself. The profiles obtained using the two techniques mimic each other, for an equivalent 70% stress relief level. The data are further qualified by impact testing wherein the zone of interest is projected in the retention groove to provide impact by the pendulum striker in the Charpy mode. Higher equivalent energy absorption in the treated specimens confirms the efficacy of the vibratory method. The present work rectifies earlier anomaly where heat treatment has been reported at 310oC for the same material.

Jan 1, 2009

"This paper describes some of the methods and equipment used for fine milling of minerals, and gives particular attention to the Vibro Energy system.In addition, the paper describes a specific application in the gold mining industry. This is the 200 tpd plant built by Anglo American Corporation at the President Brand Mine in South Africa in 1985, now a division of Freegold. This plant treats a gold bearing pyrite flotation concentrate which is finely ground to 15 microns prior to cyanidation and carbon-in-pulp (CIP). l .0 INTRODUCTIONFree milling gold ores are those that yield acceptable dissolution and recovery of the gold following grinding to what can be described as normal fineness, frequently between 50% and 90% passing 74 microns.Increasingly, gold metallurgists are faced with ores that are refractory. The traditiona1 treatment route for refractory gal d ores and concentrates has been by roasting, but for environmental reasons this is becoming less acceptable, or in some areas of the world, totally unacceptable. New methods of treating refractory gold ores are being developed and applied in practice. These new methods include pressure and biological oxidation. Higher gold liberation can also be attained by increasing the fineness of grind, although with conventional systems there are economic limits to this.In flowsheet development and test programs on new deposits, a standard procedure is to establish the relationship between the grind and subsequent go 1 d extraction. The normal situation is that gold extraction increases as the ore, or concentrate, is ground finer. Typically, this relationship is as shown in Fig. l, where the incremental additional extraction is very small once an optimum, or economic, grind has been achieved. This generally app1ies whether the material is free milling or refractory. The limits to grinding are set by the type of equipment which is commonly in use, usually ball mills. These mills have the obvious advantage of high capacity, however, they are increasingly inefficient as finer grinds are required. In general, ball mills are used to reduce ore to some agreed percentage passing 74, or possibly 53 microns."

Jan 1, 1988

By Ramanathan C, Prasad P. V. S. R

The most critical challenge for any large size storage structures to be constructed on soft compressible soils is bearing capacity and consolidation settlements. Consolidation is the time dependent phenomena, as expulsion of water from soil voids on application of external load will take longer period. It is mainly influenced by soil consistency, permeability, thickness of compressible stratum and presence of free draining layers. This study deals with the foundation solution of a large size Mounded Storage Vessel (MSV) to be constructed on thick compressible stratum whose loading intensity is around 155 kPa and the estimated settlements are greater than 400 mm. Hence, the foundation solution using vibro stone columns is adopted as an effective technique to address the challenges of excess settlements and inadequate bearing capacity. Further to keep settlements within the permissible limit of 50 mm, preloading technique with 60% of actual loading intensity will be utilized. The consolidation analysis of stone column reinforced foundations is carried based on the method given by Han and Ye (2001). The quality of the stone columns is ensured by real time quality control measures and the performance of the stone columns shall be ensured by vertical load tests. Ground settlements was closely monitored with proper instrumentations and the actual degree of consolidation has been verified by Asaoka’s (1978) method.

Sep 1, 2022

By Hamid-Reza Manouchehri

Mining & Sustainability? A Paradox?! ? Production: gradually or exponentially increasing (giant mining) ? Ore Grades: gradually declining, ? Open Cut Mining: now widespread, likely to be sustained in the future though the long-term is hard to predict as new mineral deposits are likely to be deeper ? Waste Rock / Overburden: increasing rapidly, likely to be sustained in the future and closely linked to open cut mining, especially for coal and base metals ? Economic Resources: commonly increasing but some remain stable or gradually declining, future is linked closely to exploration, technology and economics; Increasing population, changing life style and technology development, ultimately result in sustainability in mining industry to hang in the balance and continue.

May 1, 2013

By Graeme McWhirter

This paper discusses the Installation of a Vibwall for the Cardiff Bay Barrage Project Wales, UK, by Kvaerner Cementation Foundations. Only the second use of the technique in the UK the wall was successfully placed to a depth in excess of 20 metres, in unique and challenging conditions. The installation of the Vibwall was a technical success, but not a financial one. The use of the technique was at its "limits" and this paper recommends some of the controls essential in the carrying out of such work in the future.

Jan 1, 2000

By E. A. Nesbitt

THE important permanent-magnet alloys 15 years ago contained carbon and depended upon it for their permanent- magnet properties. In recent years great, advances have been made in a number of new alloys substantially free of carbon. These include Remalloy,l an alloy of iron, cobalt, and molybdenum, the various iron- nickel-aluminum alloys of the Mishima2 type, and the more recent Alnico V3 in which the best properties are developed by heat-treating in a magnetic field. The Mishima and the Alnico types of alloys are very brittle and after casting must be ground to size. This article describes a permanent-magnet material4 that can be machined as cast, and when handled with some care can be .rolled to thin sheet and drawn to fine wire. Optimum magnetic properties are developed by a simple heat- treatment, and at this time the ductility A of the alloy disappears. If the cast alloy is heat-treated without cold-working the magnetic energy product is about 1.0 X 106. This material is called Vicalloy I (pronounced vicalloy, V for vanadium, I for iron, and C for cobalt). When the alloy is first hot-worked and then considerably reduced in area by cold-swaging, drawing or grooved rolling, it is found that after heat-treatment the magnetic energy product measured in the direction of previous extension can be increased to 2.0 to 3.5 X l06. These higher values have been obtained only after reductions in area of 75 to 95 per cent, and since the material hardens considerably during working, the reduction ordinarily can be accomplished only in fine wires, although larger sizes can be reduced by the use of powerful machinery. When the material has been cold- worked in such a manner as to improve its energy product substantially, it is called Vicalloy II. Commercial use of Vicalloy has been made in the recording of speech. Tape 0.002 by 0.050 in. has been found superior in quality to all others tried, and is now used in the Western Electric Mirrorphone In a variety of forms Vicalloy I or II is useful in many laboratory instruments, and in experiments in which the sizes and shapes required cannot be obtained with the other more brittle permanent-magnet materials. In 1936, during a study of other age- hardening magnetic systems, it occurred to the author that some of the iron-cobalt-vanadium alloys might be suitable for permanent magnets. The proportions of iron, cobalt, and vanadium were varied and a range of alloys of particular interest was found, as shown by the indicated area in Fig. I. The limits of this range of com- position are 30 to 52 per cent iron, 36 to 62 per cent cobalt, and 4 to 16 per cent vanadium. The compositions indicated by points outside this area were also tested. PREPARATION AND PROPERTIES OF VICALLY I The alloys were usually cast in graphite molds into bars ¾ in. in diameter and

Jan 1, 1946

Mr GEPP said: "He proposed at the outset to draw attention to figures dealing with the population of the countries adjacent to Australia for the purpose of comparison with the population of the Commonwealth. He would deal more particularly with the areas of land surrounding the Pacific and Indian Oceans. Korea and Japan had a population of 18,000,000 ; China, 437,000,000 ; Persia, 9,000,000 ; Arabia, 5,000,000; South Africa, 129,000,000; Madagascar, 3,500,000 ; India, 251,000,000; Siam, Indo-China, and so forth, 16,225,000; Federated Malay States, 3,225,000; and, very significantly, Java, only four and three quarter days from Fremantle, over 50,000,000. From the map displayed an idea of the comparative areas of the countries mentioned and Australia could be gained. It was rather amazing that Australia, with its great potentialities, had only about 5,150,000 people. New Guinea had over 750,000 people; Hawaii, a mere speck, 250,000; New Zealand, 1,300,000; North America, 130,000,000; Central America, over 15,500,000; and South America, over 65,000,000. Colombo was only six days from Fremantle, and it was only nine days from Capetown to Albany, and eight days from Albany to Hobart. Proceeding, Mr. Gepp said "It was in 1911 and 1912 that I had the good fortune to spend nearly twelve months in Europe, and during the course of my work in England and Germany to have the oppprtunity of studying both the economical and political systems in some detail... I was in Berlin at the time of the visit of Lord Haldane, when an effort was made by the British Government to arrive at some under...

Jan 1, 1923

By Brad Thrall, Howard Bradley, Michael Samuels

"LOCATIONViceroy Minerals Corporation owns and operates the Brewery Creek heap leach gold mine located approximately 55 kilometers northeast of Dawson City, Yukon Canada. Dawson was home of the Klondike Gold Rush 100 years ago. Upon startup in November 1996, the Brewery Creek Mine was the northernmost operating heap leach gold mine in North America and one of the most northern in the world. Located at 64"" 02' latitude, the mine is less than 300 km south of the Arctic Circle. Access to the mine is available at Kilometer 14 of the Dempster Highway, linking Inuvik, NWT and the Klondike Highway, 40 kilometers east of Dawson City. The immediate vicinity is the only part of Canada not glaciated in the Wisconsin advance, which has resulted in an oxide ore deposit due to approximately 80,000 years of weathering - an area unique in Canada.DESCRIPTION OF OPERATIONSIn order to utilize heap-leaching technology successhlly in an extreme northern climate, a number of design features were incorporated into the process flow sheet to operate on a year round uninterrupted basis. Winter temperature may dip below minus 50 ""C, demanding an approach to mining and leaching that is different from heap-leach operations in more temperate climates. Because of the severe winter temperatures, the mine operates approximately 2 10 days per year, while the leaching process is continuous on a year round basis. Run of mine ore (ROM) is placed on the heap beginning in mid April until late October. Overall gold recovery is projected to be 78% over a 325 day leaching cycle with annual production levels of 2.3 million tonnes of ore placed on the pad, with an average of 75,000 ounces of gold recovered per year. The recovery process utilizes conventional sodium cyanide leaching, carbon adsorption, high pressure stripping, thermal reactivation and acid washing, and on-site smelting.HISTORYFollowing a comprehensive governmental and public review of the proposed project, a Class A Yukon Water license was issued in August, 1995. Construction started in 1995 and leaching commenced in October 1996.A Socio-Economic Accord with the Tron Dek Hwech'in First Nations provides for employment, contract, and scholarship opportunities for First Nations citizens."

Jan 1, 1999