Search Documents

By Thomas D. Barkand

Investigation of several serious hoisting accidents identified machine brake failure as the most common cause. The recent revelation of this potential hazard has prompted regulatory authorities to require an additional, independent, emergency braking system. As a result of this initiative, a new generation of braking systems have been developed and applied to mine elevators. This paper will discuss the design and testing of an electrical dynamic brake, pneumatic rope brake, and traction sheave brake. The effect of compound braking on hoisting systems equipped with multiple brakes will also be addressed.

Jan 1, 1992

By Michael A. Trevits

Mine fires can be especially perilous because toxic products can quickly spread well beyond the fire zone thereby exposing all underground miners to dangerous and deadly conditions. Since November 1998, there have been six major underground coal mine fires or explosions in the United States (Willow Creek (twice), Sanborn Creek, Loveridge No. 22, West Elk and the Jim Walter Resources No. 5 Mine). In each case, the entire mine or specific areas of the mine had to be sealed due to the build-up of dangerous gases and the fear of uncontrolled spread of the fire. Effective placement of mine seals can deprive a mine fire of oxygen and is often followed by water flooding or injection of inert gas into the affected area. When access to the fire zone is impossible because of safety reasons, airtight mine seals can be constructed, in the area of the fire, remotely from the surface through vertical boreholes. Remotely constructed mine seals are commonly made from cementitious material. Since these mine seals are typically erected blindly, it is difficult to determine if mine roof-to-floor and rib-to-rib closure has been obtained. This paper provides a review of the available materials and technology used to remotely construct mine seals through vertical boreholes.

Jan 1, 2002

By Bernard K. Asdell

Georgia, a state seldom considered to be an important mineral producer, has one surprising feature-it is the nation's largest producer of kaolin. Kaolin is a highly important raw material in the paper, rubber, ceramic whiteware, paint and chemical industries. In 1965, more than 2.7 million tons of kaolin were produced in this state, a 150,000-ton increase over the preceding year, and production continues to climb. Strictly defined, the term "kaolin" applies to a group of hydrous aluminum silicates in which kaolinite is the predominant mineral. Kaolinite is inherently white, non-abrasive, chemically inert, and of a very fine particle size, ranging from sub-micron to 40-microns equivalent spherical diameter. An electron-micrograph of kaolinite is shown in Fig. 1. The particles finer than about 2 microns are thin, elongated plates, hexagonal in outline. The larger particles, coarser than 2 microns, are predominantly vermicular in outline with a foliated structure. Table I shows a typical chemical analysis of commercial, wet-processed kaolin compared to pure kaolinite.

Jan 11, 1967

By C. S. Herzig

Some time ago, in Mexico, our signal-bells in a 700-foot shaft caused us considerable annoyance by continually getting out of order, each time so delaying our hoisting operations that we naturally desired to remedy this evil. There were two mays open: either to patch up the old bell, which was of the ordinary pattern, every time it failed to work, or else to devise some new arrangement.. On consultation with our foreman we designed a signal-device which, during the number of months I watched its operation, worked satisfactorily, without once getting out of order. We sought to produce a simple device, in which no greater pull on the lever would be necessary from one level than from another; to counterbalance independently the weight of the pendant bell-rope, so that there would be no direct weight on the working-parts of the bell itself, and likewise to arrange it so as to necessitate only a light pull on the lever in signaling; and, finally, to make some sort of trip-arrangement, so that whenever the signaling-lever underground passed through a certain arc the signal would be given in the engine-room. By this means we wished to obviate the ill effects of sudden heavy pulls and rough usage in general, such as all signaling

Jan 1, 1901

In 1965, Peter Flawn author of the famous text-book on Mineral Resources (1966) published a paper in Economic Geology with the delightful title `Who took the `Economic' out of Economic Geology?'. He opened this most interesting article with the following paragraph:If one were called upon to cite an example of a fish out-of-water he could hardly pick a better one than a recent graduate of geology of an America university who is suddenly faced with the responsibility of evaluating or appraising a mineral property. And I venture to say that the 'ftsh' with a doctorate - even in economic geology - is not much better equipped than one holding a lesser degree. The new graduate with a major in economic geology probably knows the significance of the various sulphur isotopes, he surely knows a great deal about the chemistry of the ore forming fluids and he recites with ease the arguments which prove deposits are epigenetic rather than syngenetic. However he is a rare bird indeed if he knows anything about the economics of the mineral industry. The truth is that geologists who are engaged in evaluation work are largely self taught. I ask my more distinguished and experienced colleagues - `Has it always been this way? Who took the `economic' out of economic geology?

Jan 1, 1993

By B. C. Flintoff

In general, process control systems in solid-solid separation have not evolved to the same level as in flotation circuit control. Perhaps one of the more significant contributing factors in this regard is the lack of suitable on-line analytical instrumentation. In spite of the obstacles, some interesting work has been done. This paper presents a review of current industrial control strategies in ore sorting, dense media separation, gravity separation and electrical and magnetic separation.

Jan 1, 1986

By J. A. Brierley, C. L. Brierley

The history, current applications and future of biotechnical developments in the metals' extraction industry are reviewed. Bioleaching of copper minerals continues to be the most significant application. Uranium bioleaching was successfully demonstrated at industrial scale. Developments are now being made in biooxidative pretreatment of refractory gold concentrates, ores and low-grade materials. Advancements are forthcoming in water and solid mine waste bioreclamation, including metals' biosorption, wetland treatment of acid mine drainage, and biodegradation of cyanide in spent, heap-leach operations. Better understanding of the types and functions of microorganisms involved in metal interactions could advance genetic engineering applications in bioleaching and bioreclamation.

Jan 1, 1993

By B. Denby, R. Hollands, S. Cooper

Augmented Reality (AR) is a technology that can be used to mix computer-generated images of data with views of the real world. The University of Nottingham is developing AR technology in a major research project which can be used to assist mining companies in visualising complex mine data whilst out in the field. The technology comprises of integrated GPS surveying technology and electronic orientation devices to provide location and viewing information, video capture via digital camera and portable computing hardware to overlay 3D models on views of the real world. The paper describes the concepts of the technology in some detail and concentrates on the possible applications of this in the surface mining and exploration industries.

Jan 1, 2002

Australia is the dominant iron ore supplier to the Asian market, a position that began to emerge with the development of the Pilbara in the 1960s. Iron ore is now one of AustraliaÆs main commodity exports and is likely to remain so well into the future. The annual price negotiations are the focus of widespread comment and speculation by financial analysts, journalists and mining professionals. Much is written on the subject, but how much is understood? What is the process all about and what can mine managers learn from understanding the pricing mechanism? Every one of the major regional iron ore markets has its own characteristics. The focus here is Australian supply specifically to Asia, far and away the biggest and fastest-growing of these regional markets. The core of the paper reviews and explains the key elements and procedures that contribute to pricing iron ore in Asia, a market that has long been dominated by the Japanese steel mills (JSMs) and that is now feeling the full force generated by the rapid industrialisation of China. First, however, it is important to understand how this market has evolved over the past 40 years, and the key relationships that have shaped and continue to shape the iron ore price. A description of the essential technical and commercial factors follows. Each area is explained in some detail to provide an overall demonstration of the linkages and the importance of understanding the various influences on the pricing process.

Jan 1, 2006

By K. C. Jordi

Many systems which are modelled mathematically result in a model where the relationships between some or all of the parameters are found to be non-linear. These systems are usually complicated further by a desire to make the system achieve multiple and often conflicting objectives or goals simultaneously. Rozwadowski (1970) developed a model to describe the total discounted net profit of a mine as a function of the amount of ore developed and of the grade of the amount of ore mined. Dynamic programming was used to determine the policy which gave the maximum net present value. In this paper it is shown that the relationships between the variables can be approximated by piecewise linear functions. This is amenable to solution by an algorithm based on the simplex algorithm of linear programming. The goals of maximizing the net present value, the total net profit and the total gold output are incorporated simultaneously into a goal programming formulation of the system. The resulting model is characterized by a large number of disconnected constraints. These are decomposed into several smaller problems and the problem solved. The solution is examined to discover the sensitivity of the system to changes in certain parameters. In particular the interaction between the three goals is analysed to determine whether there is conflict between any of the goals and, if so, what the trade-offs between the conflicting goals are.

Jan 1, 1979

By Browning E. J

The application of conventional dust control systems in British Coal mines has considerably reduced the incidence of pneumoconiosis. A number of new techniques have been developed involving extraction close to the cutting heads of mining machines which will be capable of controlling airborne dust with the greater intensity of production necessary in the present economic climate.

Jan 1, 1988

By R. H. Thorpe

Longwall working in Britain developed to overcome problems arising from depth of seams causing roof and ventilation difficulties. This system became very widespread particularly in the thicker seams, where faces of up to one mile in length were not uncommon. In the thinner sections, in order to remain competitive, the longwall undercutting machine was developed. Following the development of the coal cutter, every other aspect of the face operation was examined and mechanized as it became a bottleneck to output and efficiency. The face system itself was modified and workings concentrated with the same objectives.

Jan 1, 1977

By F. C. Nicolli, J. P. Barbosa, P. S. M. Soares, A. V. Estevez

INTRODUCTION Spent household dry cell batteries are frequently disposed of with metropolitan wastestream (MSW) in landfills where they can leak due to handling or aging. Frequent rain and sun cycles, especially in tropical environments, coupled to the action of leachate, dissolve their metal constituents which will eventually reach rivers, lakes and underground water. It is well known that some of these metals are fundamental to sustain life and that is why living organisms concentrate them through their metabolism, but it has been also recognized that beyond specific limits they can definitely be deleterious to the environment. In other words, high concentration of heavy metals are proven to cause chronic or acute diseases and toxic reactions, by acting on mammals' kidneys, liver and nervous system. In addition, some metals frequently used in household batteries, as mercury and cadmium, are said to be carcinogenic (Landis et al. 1995, Silva et al. 1988). Occasionally, plants to treat MSW are coupled to compost production. Household batteries present in MSW can be dragged into these plants, contaminating their products and eventually reaching vegetables making them not proper to consume by people and animals. Alternatively, batteries are also conveyed to incinerators and burned, throwing into the atmosphere volatile species. These can either act as contaminants as toxic vapor species or be delivered by winds and scavenged by rains contaminating soils and water far away from their source. In conclusion, despite the treatment applied to MSW, one can say that battery residues are potentially environmentally hazardous. The careful assessment of the environmental impact caused by residues of household batteries it is not an easy task and it can be referred as a multivariable problem. First, many different household batteries are produced by industry and the potential environmental hazard associated to their disposal depends primarily on the type of battery and manufacturer's technology. These characteristics will dictate how resistant the battery case is to handling and the

Jan 1, 1998

By Rafael Tadeu Pinto e Moura, Giorgio De Tomi, Jacopo Seccatore

This paper describes a research and development project in an open-cast mine with the goal to achieve an average P80 of 300 mm (11,8”) in the run-of-mine (ROM) product without altering the existing budget. The project included several variables in the blast design that were not previously taken into account, such as the orientation of natural joint sets in the rock mass, specific energy of the explosive and firing sequence. The new blast design method considered the directions of natural joint sets and determined the drilling pattern and the firing sequence accordingly to favor the movement of the blasted rock along its preferential direction, to reduce its confinement. At the end of the project, it was achieved an average P80 of 304 mm (12”) in the ROM, 50% lower than the one at the beginning of the project. The final blast of the project showed a reduction of 3% of the drill and blast cost, employing the same powder factor and the same drill pattern size used at the beginning of the project. The results achieved show how rock fragmentation is related to variables that are not contemplated in the most common fragmentation models: the firing sequence and the direction of movement in the blast.

Jan 1, 2015

By D. Nikols, G. Caraghiaur, P. C. Roxburgh

"IntroductionThe Highvale Mine is located 70 km west of Edmonton , Alberta on the south side of Lake Wabamun. It has been developed by TransAlta Utilities Corporation as a captive mine to supply fuel to two genera ting power plant s. The mine is owned by TransAlta and operated under contract by Manalta Coal. Within the mine permit area, TransAlta own s the right to mine 80% of the recoverable surface mineable coal.The planning process starts with the annually produced 25-year energy forecast which is provided by the Electric Utility Planning Council (EUPC). A 1983 forecast predicts an average annual increase in energy requirements of 4% over the next 25 years. Put another way, the requirement will double before the end of the century. A lar ge part of the base load generation of the Province of Alberta is provided by th e plants fueled from Highvale Mine. The Highvale Mine is therefore expected to maintain a high output over a long period of time.Mine PlanningMine planning is an ongoing, interative process that draws from many sources. All levels of planning draw from the same sources but du e to the different processes and objectives of each planning class, the degree of influence may differ. The planner becomes then a coordinator bringing together data and excerpts from several disciplines in groups. Generally, there are four classes of mining plan s; these are all used at the Highvale Mine (Table I)."

Jan 1, 1986

By G. Tamaro

The World Financial Center is situated on a 60,000 square meter site at Battery Park City at the southern tip of Manhattan Island. The foundations for the buildings and the related infrastructure posed difficult design and construction problems since the site was filled land in the Hudson (North) River. Foundation construction was made difficult by both the geology and the existence of two railroad tunnels which passed under the site. The soils at the site were unsuitable to support construction of heavy structures, and as a result, all of the foundations had to be carried down to bedrock, or the glacial till over rock. Two buildings were supported on piling and special battered caissons which provided lateral support against wind loading. The other two buildings were supported directly on rock, requiring excavation to depths of 19 meters (63 feet) below grade.

Jan 1, 1989

By G. Poropat, A. R. Guest, H. P. Grobler

At the De Beers Consolidates Mines operations it is common practices to perform Geotechnical mapping of the newly exposed faces in the waste and ore rock. The purpose of Geotechnical mapping is to quantify the in-situ fracturing of a rockmass that in turn is required during the planning and application of a mining method. Whether it is to determine slope angles, caveability, impact of blasting or support requirements. This mapping involved a cumbersome and time consuming procedure that requires individual examination and description of the natural inherent fractures exposed by mining. During highwall mapping in an open pit this can be a safety concern due to the duration of time spent below a highwall. The advantages gained through the recent introduction and application of SiroVision® allows safer mapping, an increase in statistical fracture population, archiving of rock faces and the more accurate reflection of the true mapping. This paper aims to describe in detail the application of the recently developed SiroVision®, photogrammetry software, to replace conventional face mapping. A De Beers Consolidated Mines, il est pratique courante de faire une cartographie géotechnique des tailles récemment exposées dans le rocher stérile ou minerai. Le but de la cartographie géotechnique est de quantifier la fracturation in-situ d’une masse rocheuse, qui sera nécessaire lors de la planification et application d’une méthode minière, que ce soit pour déterminer les angles des galeries inclinées, les possibilités de foudroyage, l’impact du dynamitage, ou les besoins en supports. Cette cartographie nécessitait une procédure longue et compliquée qui demande l’examen individuel et la description des fractures naturelles propres exposées par l’opération de mine. Pendant la cartographie de parois dans une exploitation à ciel ouvert, cette opération peut être dangereuse à cause du temps passé sous la paroi. Récemment, le lancement et application de Siro Vision apportent l’avantage d’une cartographie plus sûre, une augmentation des statistiques de population de fracture, l’archivage des tailles de roches, et le reflet plus précis de la cartographie. Le but de l’étude présente est de décrire en détail l’application du développement récent de Siro Vision, logiciel de photogrammétrie, pour remplacer la cartographie de taille conventionnelle. Bei den De Beers Consolidates Mines Operationen ist es gängige Praxis geotechnische Aufzeichungen des Taub- und Erzgesteins neu geöffneter Abbaustellen zu erstellen. Zweck dieser geotechnischen Aufzeichnungen ist die vor-Ort-Quantifizierung des Bruches der Gesteinsmasse, welche im Gegenzug während der Planung und der Anwendung einer Abbaumethode erforderlich ist, sei es um einen Neigungswinkel festzustellen, Abbaubarkeit, Auswirkung von Sprengungen oder Anforderungen an Unterstützungen. Die Aufzeichnungen waren mit umständlichen und zeitaufwendigen Prozeduren verbunden, die eine individuelle Prüfung und Beschreibung der durch den Abbau freigelegten natürlichen inhärenten Brüche, verlangten. Dies kann auf Grund des Zeitraumes der unterhalb einer Flözoberschicht verbringt wird zu einer Frage der Sicherheit werden wenn die Aufzeichnung einer Flözoberschicht im Tagbau erfolgt. Die Vorteile auf Grund der jüngst erfolgten Einführung und Anwendung der SiroVision® gestatten sichereres Aufzeichen, eine Zunahme in der statistischen Menge an Gesteinsbrüchen und eine akkuratere Reflektion der tatsächlichen Aufzeichnungen. Diese Arbeit hat zum Ziel im Detail die Anwendung der kürzlich entwickelten SiroVision®, eine photogrammetrische Software, die die konventionelle Abbauortaufzeichnung ersetzen soll zu beschreiben.

Jan 1, 2003

By Leon C. Botham

?? Review of Requirements ?? Components of Modeling ?? Water Management ?? Tailings Management ?? Primarily a water management problem ?? Solids relatively easily contained ?? Process flows and runoff a continuous stream over life of mine ?? Need to allow this to safely happen over wide range of conditions

May 1, 2008

By B. K. Miller, George E. Moore

THE Missouri fire clays are here divided into plastic and semiplastic clays occurring as widespread bedded deposits in east central Missouri and flint and diaspore clays occurring as isolated "sink-hole" deposits in the north central Ozark region. Visual inspection was the first method used in clay prospecting. Thin overburden, hard sandstone "rimrocks," and the occurrence of diaspore float made this method particularly applicable in the flint and diaspore fields. The first drilling tool used was a hand auger. One man can drill 25 to 50 ft. per day at a cost of about 35 cents per foot. Holes can be drilled to a depth of 150 feet. Spud drills are often used where the over burden is hard. This drill uses a slotted earth socket bit. A two-man crew can drill about 100 ft. per day at a cost of about 35 cents per foot. Mechanically powered auger drills have been used extensively in wildcat drilling in the past few years. This type of drill furnishes a continuous set of cuttings. The practical depth limit with this drill is 50 to 60 ft. Two men can drill 300 ft. per day at a cost of about 20 cents per foot. Core drilling is used mainly to prove a known clay deposit. A two-man crew with a No. 22 Sullivan drill can drill about 30 to 40 ft. per day in soft clay, at a cost of about $1.25 per foot.

Jan 1, 1947

By Jim Cook

Arsenal Football Club required the development of a new home stadium in north London, subsequently named the Emirates Stadium. The proposed development comprised a 60,000 seat stadium, with associated facilities and a sports training centre. Described are the foundation solutions and piling construction techniques used, which take into consideration the potential impacts on existing above and below ground railway infrastructure and underground water structures. Methods used by the piling contractor to improve aspects associated with health, safety and quality are also described.

Jan 1, 2008