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By Malcolm Ross

Asbestos crystallizes within rock formations undergoing intense deformation characterized by folding, faulting, shearing, and dilation. Some of these conditions have prevailed during formation of the taconite iron ore deposits in the eastern Mesabi Iron Range of Minnesota. This range includes the Peter Mitchell Taconite Mine at Babbitt, Minnesota. The mine pit is over 8 miles long, up to 1 mile wide. Fifty three samples were collected from 30 sites within areas of the pit where faulting, shearing and folding occur and where fibrous minerals might occur. Eight samples from seven collecting sites contain significant amounts of ferroactinolite amphibole that is partially to completely altered to fibrous ferroactinolite. Two samples from two other sites contain ferroactinolite degraded to ropy masses of fibers consisting mostly of ferrian sepiolite as defined by X-ray diffraction and TEM and SEM X-ray spectral analysis. Samples from five other sites contain unaltered amphiboles, however some of these samples also contain a very small number of fiber bundles composed of mixtures of grunerite, ferroactinolite, and ferrian sepiolite. It is proposed that the alteration of the amphiboles was caused by reaction with water-rich acidic fluids that moved through the mine faults and shear zones. The fibrous amphiboles and ferrian sepiolite collected at the Peter Mitchell Mine composes a tiny fraction of one percent of the total rock mass of this taconite deposit; an even a smaller amount of these mineral fragments enter the ambient air during mining and milling. These fibrous minerals thus do not present a significant health hazard to the miners nor to those non-occupationally exposed. No asbestos of any type was found in the mine pit. © 2007 Elsevier Inc. All rights reserved. Keywords: Taconite; Asbestos; Amphibole; Reserve mining; Tailings; Mesabi iron range; Mineral fibers

Jan 1, 2007

By M. D. Lackey

The "Art" of Big Hole Drilling has been in a continual state of evolution at the Nevada Test Site since the start of underground testing in 1961. Emplacement holes for nuclear devices are still being drilled by the rotary drilling process, but almost all the hardware and systems have undergone many changes during the intervening years. The current design of bits, cutters, and other big hole drilling hardware results from contributions of manufacturers and Test Site personnel. The dual string, air lift, reverse circulation system was developed at the Test Site. Necessity was really the Mother of this invention, but this circulation system is worthy of consideration under almost any condition. Drill rigs for Big Hole drilling are usually adaptations of large Oil Well drill rigs with minor modifications required to handle the big bits and drilling assemblies. Steel remains the favorite shaft lining material, but a lot of thought is being given to concrete linings, especially precast concrete.

Jan 1, 1983

By C. B. Manula

Bituminous coal mining in the United States is currently experiencing a period of rapid growth which began in the early 1960's. Future demands are conservatively predicted to rise to 700 million tons by 1980 and to anywhere between 1 to 3 billion tons by the turn of the century. This means a continuous expansion of coal production by a factor of at least two can be expected before the end of the century. Over the last few years, production from underground mining has decreased; yet it is about 50% of the total coal output. In the absence of any discovery of near surface coal deposits, and even after conceding that some deeper deposits can be surface mined with changes in technology it can be reasonably assumed that coal production from underground will continue to play an important part in solving the energy crisis.

Jan 1, 1975

By John E. Leitch

The cost of corrosion as measured by such cost components as the renovation or replacement of coated steel, or the use of expensive coating systems on steel, is considerable. Extrapolating from figures for the USA would place the overall cost of corrosion for South Africa as a figure of the order of magnitude of something over 1% of the GNP. This is a sizeable amount, of which costs associated with atmospheric corrosion would be a significant proportion. The corrosivity of an atmosphere can be defined as the ability of the atmosphere to cause corrosion in a given metal or alloy (International Standards Organization [1]). The ISO Standard 9223 specifies the key factors in the atmospheric corrosion of metals and alloys, and defines categories of corrosivity on the basis of these factors. Prior to the publication of that ISO standard, Callaghan published the results of his twenty-year exposure programme and his excellent corrosivity map of Southern Africa [2]. The present author published updates of the corrosivity map in 1999 [3] and again in 2003 [4]. The summary of the individual areas of corrosivity around Southern Africa was published in the latter paper, and is reproduced here as the following TABLE 1. Of significance in TABLE 1 are the numerous regions of very high corrosivity (C5 or beyond), particularly the rural West Coast shoreline, the North East Coast (KZN) shoreline, and the coastal cities Cape Town, Durban and Richards Bay. The corrosivity map as published is obviously based on much extrapolation as only a small number of points have been measured. During the past three years further measurements have been made, mostly however at the same sites in order to give greater reliability and to monitor long-term trends with changes in pollution. These two aspects are incorporated in this update. There has become available a greater amount of air pollution data for centres in South Africa than was the case some years ago. In this present paper the pollution data are used to extrapolate the corrosivity over areas where little or no direct corrosivity measurement has been made. This methodology is described in ISO 9223.

Jan 1, 2006

By C. W. Davis

This paper is the second of a series of progress reports on a study, of the hydrometallurgy of manganese which is being conducted in an endeavor to make possible utilization of the large deposits of low-grade domestic manganese ores that occur in several States. There are at least four processes in which a knowledge of the action of SO2 gas on manganese oxides at elevated temperatures may prove of value. One ,of these involves dissolution of manganese from ores. The Bureau of Mines has investigated the hydrometallurgy of manganese by a process in which SO2 gas, a waste product at many smelters, is passed into water to form a solvent for manganese. Although Several manganese minerals acre readily dissolved, rhodochrosite (MnCO3) was attacked but superficially.§. Recent experiments have shown that a roast at 650 to 900°C converts the manganese of rhodochrosite to a form that is quickly dissolved by a weak SO2 solution. Introduction of smelter gases containing as much as 5 per cent SO2 during such a roast would not add much to the cost of the operation and might result in the formation of considerable water-soluble manganese sulphate.

Jan 1, 1930

By C. W. Davis

This paper is the second of a series of progress reports on a study of the hydrometallurgy of manganese which is being, conducted in an endeavor to make possible utilization-of the large deposits of low-grade domestic manganese ores that occur in several States. There are at least four processes in which a knowledge of the action of S02 gas on manganese oxides at elevated temperatures may prove of value.

Jan 1, 1930

By P. B. Leavenworth

Development in the Upper Texas Gulf Coast during 1945 resulted in the discovery of 23 new fields; one Miocene, eight Frio, three Cockfield-Yegua and eleven along the Wilcox trend. The Wilcox trend appears to he the most active at this time. Producing depths of the new Wilcox discoveries range from 2050 to 10,050 ft. Drilling along the Frio trend has been, for the greater part, projected to the deeper downdip sands. Eighteen of the new discoveries are classified as oil or condensate and five are gas discoveries.

Jan 1, 1946

By R. Adsero

The analysis of equipment trends in AUSIMM?s Revision of Monograph 19; Australasian Mining and Metallurgy Operating Practices (AMMOP) in the paper by Dight et al (in press) raised some interesting and in parts disturbing trends in the Open Cut Mining Industry. According to the US Bureau of Labour Statistics the US mining and petroleum industries? productivity is down by 12% since 2004 while the Australian Bureau of Statistics shows the productivity of the Australian mining industry is down by 34% since 2001. In terms of open cut equipment median output for draglines is down by 15% since 2003; electric rope shovels are down by 41% since 2003; hydraulic excavators are down by 39% since 2008; front end loaders are down by 39% since 2007 and trucks are down by 41% since 2006. Clearly the boom has not been good for the efficiency of the mines. During this same time, best practice (defined as the average of the top 10% by annual output per unit of input) has declined but not by as much as the median (eg. shovels down by 8%, excavators down by 19% and FEL?s down by 5%). This paper will build on the analysis of AMMOP to understand the differences occurring between median and best practice and identify the factors contributing to the decline in performance. As the industry enters a period of potentially lower prices for commodities and reduced margins pressure will be brought to bear on mine sites to start moving more with the equipment they have. An understanding of where efficiency has been lost will be a key component in that. The information contained in AMMOP, and the subsequent analysis of that information in papers such as this one will be crucial to reversing the decline in open cut equipment performance.

Feb 27, 2013

By Peter Metcalfe

"Wireless communication in the mineral processing environment is not as simple as it is in the home or office environment. The correct design of a wireless network in the mineral processing environment can offer a more flexible and lower cost installation than the transitional fiber networks. However with the flexibility of a wireless solution, also comes some limitations. By reviewing the plant requirements along with weighting the wireless benefits and limitations it is possible to design a network that combines the robustness of a wired solution with the mobility of a wireless solution. This paper addresses some wireless design considerations and it looks at some real life examples in the following areas: •,Meshed wireless network for high levels of redundancy •,Wireless instruments (such as HART, Modbus and others) •,Portable devices for mobile operators •,Network monitoring for plant personnel (it’s no longer just for IT people) INTRODUCTION Typical networks used in the mineral processing environment consist of a fiber network infrastructure with industrial switches used to connect the network devices. These fiber networks can be redundant or put into a ring topologies to offer a higher level of availability. Fiber networks have the benefits of: •,Immunity to noise from power and grounding issues •,Ability to span long distances (2km for multimode fiber and 20km for single mode fiber) •,Maintainable “off-the-shelf” technology Fiber networks however have some drawbacks, such as: •,Relativity high initial installation cost for cable trays, poles, trenches and pulling and termination of cable. •,Fixed geographic topology, adding future fiber drops may be challenging and expensive. •,Mobile users are not considered. Integrating a wireless network with a fiber network can offer the best of two worlds, a reliable high speed backbone for mission critical activities and a wireless network for remote applications and mobile users."

Jan 1, 2014

By M. England

Test equipment has been developed to record automatically both the displacement of the pile head and the load applied during a conventional maintained load pile test. Some systems also have, in addition, been fitted with the facility for maintaining the applied load, as set by the operator, at very constant levels. The advantages are both commercial and technical, but a well trained operator has to be in attendance to control the test. Since typical test specifications in the UK require more than 19 hours to complete, it became inevitable that at least one equipment operator remained on site to expedite the test for its duration. Although electronic measurement and data logging of load tests may be more safe than previous direct observation of dial gauges. A single person remaining on a construction site alone is not to be recommended, even if they are just supervising the test. Further development of the testing system produced equipment which will perform the entire test specification as required without operator intervention. To achieve this, full automation is employed. The patented method particularly addresses the safety requirements and by using additional sensors, detects any uncharacteristic behaviour of the pile under test or of the reaction system and the equipment takes appropriate action in a controlled and safe manner. The quality of test data returned from these automated systems is a key element when analysing pile behaviour with models such as CEMSOLVE? and TIMESETTM. These analysis methods often indicate ground disturbance resulting from installation technique and have allowed pile design to be optimised using actual field data rather than theoretical considerations alone. An additional feature is remote access, this allows the data recorded to be transferred and the progress of the test to be viewed from practically any location. This permits experts to view the data 'live' and allows rapid diagnosis of any problems with the expected pile behaviour.

Jan 1, 2002

By Barbara H. Scott Smith

"During the last two decades lamproites have joined kimberlites as the only two known primary sources of economic quantities of diamonds. This paper contrasts the petrography, primary and xenocrystic mineralogy and pipe geology of these petrogenetically separate rock types. The petrographic discrimination of kimberlites and lamproites from each other, as well as other rock types found during diamond prospecting, is discussed. Kimberlites and lamproites can be classified texturally and mineralogically. Such classifications highlight the differences between, and among, lamproites and kimberlites. The implications of these differences for diamond exploration programs are discussed, with particular emphasis on the application of petrography. IntroductionKimberlite was the term coined in the late 19th century to describe the host rock of diamond at the type locality, Kimberley, South Africa (Lewis, 1887, 1888). Innumerable kimberlites are now known worldwide; some of them contain economic quantities of diamond (e.g. South Africa, Botswana and Russia) while many are barren. Jennings (1989) suggests that less than 3% of the known kimberlites can be considered to be commercial. Kimberlite was thought to be the only important primary source of diamond for approximately a century. Until the late 1970s, lamproites were thought to be only academic curiosities. Some workers (e.g. Wade and Prider, 1940), however, did comment on certain similarities between lamproites and kimberlites and, hence, inferred a potential for lamproites to carry diamonds.The term lamproite was introduced by Niggli (1923) for leucite-bearing rocks from southeast Spain and Wyoming which had some unusual geochemical characteristics. Wade and Prider (1940) used the term lamproite (as defined by Troger, 1935) to embrace rock types found in the West Kimberley area of Western Australia. All the lamproites described by Wade and Prider (1940) form distinct topographic features. Subsequently in the late 1970s, additional pipes, which have little or no relief, were discovered in the same area, but only as the result of a major diamond exploration program (Atkinson et al., 1984; Jaques et al., 1984, 1986). Some of these bodies are diamondiferous. In 1979, the Argyle pipe was discovered in the East Kimberley area which, in terms of grade, is the richest known primary diamond deposit in the world with some parts of the body having grades greater than 500 carats/100 tonnes (Madigan, 1983; Boxer et al., 1989). All the initial new discoveries in Western Australia resulted from classic stream sampling for ""kimberlite indicator minerals"" (Atkinson, 1989)."

Jan 1, 1992

By James J. Cahill

Contractor's working in an urban environment face a multitude of working conditions. There is no typical "Downtown" job site. From afar we just see the skyline, or up close a specific building. This, of course, does not give us a clue as to the site conditions the foundation contractor faced in doing his work. The open, downtown building site is still available on some projects, but they are becoming rare as our cities are becoming more developed. A typical site today might include any one or several of the following problems: A. Deep pit with no ramp access B. Multi-type known or unknown obstructions C. Height limitations D. Load restrictions E. Existing adjacent building founded on shallow foundation F. Existing foundations G. Existing tunnels, utilities or subways

Jan 1, 1991

By T. J. Snell

Bolnore Village in Haywards Heath, Sussex, England, is a large development covering 8 to 10 hectares and expected to provide 1500 homes in five phases to assist in the continuing demand for new homes in the London area. Part of the development required housing on a relatively shallow slope found to have deep seated failure planes which are fairly prevalent in this part of Sussex. Locally the slope angle was around 20 degrees but more typically the gradient was 6 to 7 degrees. There were significant concerns about slope stability and bearing capacity due to pre-existing shear surfaces and the complex geotechnical profile. There was some evidence of instability in the form of residual shear surfaces and tension cracks. The development required terracing the site with retaining structures up to 5 meters in height, formation of access roads and foundations of new houses. The developer Crest Nicholson adopted a collaborative approach with consulting engineers Powell Tolner and specialist geotechnical contractor Keller Ground Engineering. The solution consisted of a novel combination of contiguous bored piling, ground anchors, and both block work and timbacrib retaining walls to ensure the geotechnical issues were adequately addressed within the time and cost constraints set by the team. The paper describes the geotechnics of the problem together with the design, practical implementation, and site progress achieved

Jan 1, 2006

By D. R. Spears

As part of its mission to develop technology to assure a continuing supply of minerals, the US Bureau of Mines has investigated the flocculation of a Stillwater, MT, chromite ore. The ore was flocculated at different solids contents and at different stirring speeds to determine the importance and effect of hydrodynamic factors. In acidic and basic pH, the chromite ore was flocculated with high molecular weight polyacrylamides differing in the degree of hydrolysis. Polyacrylamides were found to bind to chromite ore particles through hydrogen bonding. The anionicity of the polymer and the pH affected the degree of polymer-particle interaction, which in turn affected polymer conformation at the surface. A polymer conformation with many loops and tails was used to explain high flocculation efficiency. It was found that such a conformation could compensate for poor hydrodynamic conditions.

Jan 1, 1992

By Victor C. Bryan

"One of the more challenging issues facing operators of U.S. mines and quarries is blasting in an environmentally acceptable way. It is quite important that industry management understand and apply guidance, discipline, and control in the exercise of blasting operations. This presentation is a discussion of problems related to that environment away from the blasthole that may or may not be adversely affected by blasting and the steps management may consider in resolving resultant problems. In any case, one of the main concerns that will continuously be brought up is thatmanagement procedures inherent to good blasting is a uxporate responsibility of the mine or quarry business entity; and can not be delegated to the explosive manufacturer or supplier. This management attitude, based on education, training, and the comprehension that the process of production begins with drilling and blasting and consumes a significant amount of overall production costs."

Jan 1, 1995

By Mohamed A. Younis, Paul J. Headland, Paul H. Madsen, Vojtech Gall

INTRODUCTION A 100 ft long, 20 ft high and 18 ft wide NATM tunnel was excavated through grouted clean sands beneath a busy city street, including a variety of existing utility lines. The new tunnel associated with a hospital expansion will serve as a pedestrian tunnel connecting a parking structure with a new hospital facility. Tunnel construction started on December 15, 2005 when drilling for the grouting program started and was completed on May 26, 2006 when the tunnel final lining was completed. The tunnel was constructed by Kiewit Construction Company as a tunnel subcontractor to The Christman Company who is constructing the hospital facility for Spectrum Health in Grand Rapids, Michigan. URS was the project designer. GallZeidler Consultants, LLC were the contractor’s NATM consultant. PROJECT DESCRIPTION The Michigan Street Pedestrian Tunnel is a component of the Michigan Street Development located along the north side of Michigan Street NE between Coit Avenue NE and North Division Avenue in the downtown area of the Grand Rapids, Michigan. The Michigan Street Development includes a parking deck and four new towers to be constructed over the proposed parking deck. The tower planned furthest east is being developed by Spectrum Health as the Lemmen-Holton Cancer Pavillion. The purpose of the pedestrian tunnel is to connect the proposed Lemmen-Holton Cancer Pavillion with the future Spectrum building to be located on the south side of Michigan Street NE. The southern end of the tunnel was constructed with a bulkhead until the future Spectrum building is constructed at which time interconnection will be required. The tunnel site plan and profile are shown in Figure 1, Site Plan, and Figure 2, Tunnel Profile. Several challenges were faced during the design and construction of the Michigan Street Pedestrian Tunnel. These challenges included compressed design and construction schedule, maintenance of traffic and protection of old underground utilities. The tunnel was being constructed as part of the Michigan Street Development and coordination with other concurrent construction activities was required. The tunnel was constructed within a specified window of time to allow other associated construction activities to take place without compromising the overall project schedule. The design started in June 2005 and construction was completed by June 2006.

Jan 1, 2007

By G. Récoché, A. Chamaret, M. O’Connor

Building indicators that respond to all stakeholders' needs is a time-consuming and complex exercise, with certain questions still unsolved. The aim of the current three-year research project, carried out in partnership between BRGM’s Mineral Resources Division and C3ED, is to propose a top-down / bottom-up indicators building methodology that combines conception and coordination methods and a participative approach. The tool-design phase is based partly on a comparative analysis of existing international initiatives according to different criteria (objective, observation scale, framework, etc.). The study of two African mining projects will provide the opportunity to confront the conceptual aspects with reality in the field. Careful consideration of the participants’ suggestions will result in a set of indicators that can be easily understood and adopted by all stakeholders. The final objective is to measure the impact of a mining site on a local, regional and national sustainable development frame, throughout the full life cycle of a mine.

Jan 1, 2005

By D. A. Donato

It is often necessary for a mining company to extract coal from a seam underlying a previously mined coal seam. The impact of the overlying mine workings on the stress distribution within the underlying mine workings is very difficult to assess without the use of numerical modeling techniques. This paper demonstrates the usefulness of applying numerical modeling to evaluate alternate startup-room locations for a longwall panel considering the effects of multiple seam interaction. MULSIMIPC, a code adapted by the former U. S. Bureau of Mines, was used to compare stress patterns in two proposed startup-room locations. These model results were not only compared to each other, but also to results from a model with no overlying mine workings to provide baseline criteria for evaluation of the two proposed startup-room locations. The numerical modeling study was successful in providing useful information to the coal company and the regulatory agency (MSHA), resulting in a mine design that was both safe and efficient, and prevented the sterilization of a large volume of coal reserves.

Jan 1, 1996

By D M. Frantois-Bongarton

"A few situations are first reviewed where practical shortcuts lead to acceptable solutions where none seemed to be possible. These include: The solving of many complex sampling optimisation problems with the simple approach of the worst case policy (WCP). A simple approach to single-stage sampling problems will be mentioned at continuation. In the plants, minimising the impact of border effects in incorrect samplers, so that the resulting samples are approximately correct and acceptable in practice because the bias risk attached to them is controlled. Examples are given, as well as practical tools and a general methodology.Finally, some sources of undue conservatism are reviewed with general recommendations aiming at eliminating them.CITATION:Frantois-Bongarton, D M, 2012. Practical considerations and shortcuts in sampling, in Proceedings Sampling 2012, pp 171-174 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 21, 2012

By J. H. Bain, D. C. Haigh, L. C. Parsons

Jan 1, 1964