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By B. Dias, P. C. Schutte

Work-related musculoskeletal disorders (WMSDs) affect the wellbeing of workers and result in poor quality work, lower work performance and decreased motivation. In contrast to ‘occupational’ diseases where there is a direct cause-and-effect relationship between hazard and disease (e.g., asbestos and asbestosis, lead and lead poisoning), ‘work-related’ diseases are multifactorial, where the work environment and the type of work that is performed contribute significantly to musculoskeletal disorders. WMSD is the term used to describe disorders and diseases of the musculoskeletal system (i.e. muscles, joints, ligaments, tendons and nerves). WMSDs are by definition a work-related phenomenon. The literature shows inarguably that certain jobs and certain work-related factors are associated with a significant risk of contracting a WMSD. It is assumed that repeated movements and postures, static work, continuous loading of the tissue structures or lack of recovery time, trigger or cause a pathological process that then manifests itself as a WMSD. This paper looks at the prevalence of the WMSD condition at three mines in South Africa: a coal, a gold and a platinum mine. Predisposing factors that include work factors, presentation of symptoms and psychological factors will be discussed in the paper.

Jan 1, 2003

By Howard L. Hartman

Introduction The federal government's declining role in funding research has created a critical dollar gap for university departments of mining engineering. Industry, too, is affected by the drought. Research is lagging. Hardpressed universities are going to the private sector for funding. Mining companies should not shower universities with philanthropy, but a research partnership should be contracted on a pay-as-you-go basis. A model exists at The University of Alabama (albeit not in mining) that could be adopted by the mining industry. An equal partnership arrangement between a university and an industry for conducting research is proposed. The concept is not that a corporation sponsors and a university performs the research. Nor does it call for educational contributions or giveaways from industry. Rather, the corporation and the educational institution enter into a cooperative research endeavor, a full and equal partnership. Both parties contribute and both share the benefits. A key to the relationship is that it has a single objective: it must generate profits or reduce costs for the company. Working Model Recent literature is replete with examples of proposals for joint research endeavors, involving both contracts and grants, between industry and universities (Bronwell, 1971; Bugliarello, 1978; Branscomb, 1981; Sanford and Holland, 1982). They are all good proposals and offer something to both parties. They are, however, not widely supported. Few have received a favorable nod from the US mining industry. Though it may be logical, for example, to remake the American Mining Congress (or some new consortium) in the mold of umbrella-type industry organizations to fund cooperative research with mining institutions, such proposals have never flown. What model, then, will work? First, look for a model that has worked in industry in general. Second, seek to apply it to mining specifically. There is a model project that satisfies the first of those criteria. It is a project complicated by a third party, in addition to a corporation and a university. In January 1983, the "Factory of the Future Project" was initiated between The University of Alabama (UA) and General Motors Corp. (GM). The United Auto Workers (UAW) is a third party to the agreement. The factory was GM's Rochester Products Division manufacturing plant in Tuscaloosa, AL, also home of UA's main campus (Fig. 1). Saving a Plant The agreement came about at the initiative of GM and the UAW. Faced with having to close the plant because of excessive production costs, company and union officials proposed to the university that an applied research facility be established at the plant. The university would operate the laboratory, dedicated to $470,000 a year cost reductions for the company. The school would lease the 5.1 km2 (55,000 sq ft) space for $470,000 a year for three years. Any savings effected by the university's research effort would be credited toward to the rent. GM said the small factory, which made replacement carburetors

Jan 9, 1984

By D. J. Leidel

The offshore production of oil and gas resources has been active in the Gulf of Mexico since Kerr- McGee drilled the first commercial well out of the sight of land in 1947. Since then, approximately 60% of the offshore oil/gas production structures used globally have been erected in the GOM to support the production of energy resources’. The shallow, shelf and shelf edge waters of the Gulf of Mexico have reached or are rapidly approaching production maturity, requiring that the fixed structures used to support energy production be removed or otherwise disposed of by suitable means. The use of energetic materials has been determined to be a safe, efficient and cost effective technology to remove fixed offshore structures whose service life has been exceeded.

Jan 1, 2002

By E. S. Leaver

THE purpose of this paper is to describe, in a general way, gold-dredg-ing operations in California, with particular reference to unusual features, including types of deposits and recent attempts to improve the recovery of the gold.

Jan 1, 1937

By Mingmei Zhu, Lang Hu, Yu Wang, Hongpo Wang, Congjing Zhang

Magnetic field has a great effect on the crystallization behavior of mold flux and properties of the flux film between mold and strand, on which the surface quality of strand was deeply depended in continuous casting process. Therefore, studying the change law of the crystallization properties of mold flux in magnetic field is of great significant. In the present work, based on intensity of the applied magnetic field with the range from 0mT to 60mT, the crystallization ratio, crystal size and mineralogical phases of the flux film were discussed. The results show that crystallization ratio increases with the increasing magnetic field intensity, and the crystal size becomes bigger at the same time. The magnetic field promotes the crystallization ratio and growth speed of the crystallized grains of mold flux. However, magnetic field doesn’t change types of the mineralogical phases.

Jan 1, 2015

By Cooper R. J

The essential features of the zinc concentrate roasting installation at the Risdon Works by the Electrolytic Zinc Company of Australasia Ltd. are given.The problem of maintenance of ignition in down-draught zinc concentrate flash roasters is discussed, and a solution offered.A successful and economical method of using by-product oxygen for raising the roasting efficiency of hearth roasters is described. Three methods of utilizing oxygen for the same purpose in flash roasting are detailed, and their relative merit, considered.INTRODUCTIONThe zinc sulphide concentrate used at the Risdon Works is roasted autogenously for removal of sulphur in two hearth roasters, and four flash roasters. The hearth roasters are of modified Skinner type with eleven hearths. They were designed, and are used, for roasting mixtures of relatively low sulphide content. Their design and operation have been described elsewhere (Forster, 1949).The flash roasters are down-draughted furnaces with cross-section and rabbling equipment based on the hearth roaster design, and the process is similar to that developed by the Consolidated Mining and Smelting Company of Canada Ltd. (Cominco) at Trail, B.C. (Stimmel, Hannay, and McBean, 1936).These furnaces are 20 ft. in diameter. They have three drying hearths through which hot gas is drawn from the combustion chamber by the burner fan. The combustion chamber is 2'1 ft. high above the collecting hearth (27 ft. in No. 4 unit), and the discharge hearth below it is 6 ft. high, so that a large gas offtake is possible. Four rabble arms for each hearth are carried on a central column. Dried, ground concentrate, and the air for roasting it, are fed to a burner...

Jan 1, 1958

By F. C. Turin, K. M. Cornelius

1. INTRODUCTION Underground mining in the USA has undergone significant change in the past 20 years. Two key elements have been increased mechanization and a more educated work force in spite of these changes, many jobs continue to be labor-intensive and repetitive in nature. They entail tasks that, performed over time, can take a toll on the soft tissues and joints. The problem may be compounded by an aging mining workforce. In 1996 the mean age of the coal mining work force was 45 years and the median total years of experience was 20 (NMA 1998). As a person ages, the body resilience to chronic wear and. tear is reduced, which may cause a worker to pay an increasingly higher health price for performing the same task. Mining companies, like many others, are becoming more aware of cumulative effects to the worker as reports of these types of injuries rise. . Conducting a job analysis is an important step when considering a job redesign or modification to reduce worker cumulative trauma exposure. A basic approach to job analysis is to examine the types of aches and pains reported, the tasks performed, and work site conditions. The US Bureau of Mines (USBM) conducted an evaluation of roof-bolting tasks performed at an underground coal mine concerned about early warning signs of cumulative trauma. This evaluation will comprise the primary focus of this chapter. The approach used for the roof-bolting race study may be applicable to other work environments. 2. FUNDAMENTALS OF CUMULATIVE TRAUMA EXPOSURE Musculoskeletal injury is a term used to describe a wide range of soft tissue disorders that affect the nerves, tendons and muscles. Common examples include lower back pain, tendinitis and carpal tunnel syndrome. The majority of these injuries are not the result of sudden mishaps, but usually develop gradually from repeated wear and tear. Symptoms may not appear immediately, but can take weeks, months or even years. Symptoms may result from many types of activities, performed at work or at home, and it is often difficult to attribute there to a single event. In fact, it is more common to identify factors that may have contributed to the development of the condition. The terms repetitive strain injuries or cumulative trauma disorders (CTD) have been commonly used to refer to disorders that have occurred due to work-related activities. Three main risk factors contribute to CTD: force, repetition and awkward postures. Any one or combination of these may contribute to the development of CTD. Therefore, the design of equipment in conjunction with the required tasks should be evaluated when attempting to reduce these risk factors. Examining the layout of the work area to help identify tasks which may contribute to cumulative trauma is necessary. The following list (Putz-Anderson 1988), describes ergonomics concerns that, overall, should be minimized at the work area: • Crowding or cramping the worker: a work area layout may unnecessarily constrain movements of the worker. • Twisting or turning: placement of tools and materials may require the worker to twist the spine to fulfill the requirements of the job. • Repeated reaching motions: the layout of the work area may require the worker to lean to reach and grasp the necessary tools and controls. • Misalignment of body parts: the arrangement of the work area may require the worker to frequently have one shoulder higher than the other or have the neck or spine bent to one side. While many of these concerns are a function of equipment design and environmental conditions, making workers aware of these issues may help them to adapt their work habits to reduce risk of injury. Additionally, this information is useful when conducting an ergonomic evaluation of a work area and associated tasks. 3. UNDERGROUND MINING ENVIRONMENT The underground mining environment is a unique challenge. It is more difficult to develop controls for an underground mine site as compared with a factory setting where equipment and facilities can be more easily designed to reduce worker force, posture and repetitive exposures. In an underground mine, workers are required to perform labor-intensive tasks that often cannot be avoided due to environment constraints. The dynamic nature of the environment does not allow easy implementation of mechanical assists to reduce force exposure. Many of the tasks performed by workers are repetitive. Restrictive work areas due to low ceiling height, low lighting levels and large pieces of equipment cause workers to perform these tasks in postures that are not desirable. Designers of underground mining equipment can control how a machine will function, but not the environment in which it will be used, Hazards in an underground mine cannot be completely removed by redesigning the system. There are many hazards and information sources that must be continually monitored by workers including their position in relation to large pieces of mobile equipment and unpredictable geological anomalies. Thus, immediate dangers may take priority over awareness of ergonomic considerations while performing a job. 4. CASE STUDY OF UNDERGROUND ROOF BOLTING 4.1. Roof Bolting and Cumulative Trauma Exposure In an underground coalmine, after an area is mined it is necessary to support the roof to keep it from collapsing. Since 1950, the primary method for supporting the mine roof has been installation of roof bolts. Long bolts installed into the roof compress the layers of strata achieving a uniformly distributed support anchorage. Roof bolts, typically 6-8 feet long, are installed by workers using large roof-bolting machines. There are different types of machines

To explain in any depth the industrial relations of Broken Hill I believe that it is necessary to trace some of the many happenings that created the present industrial climate. While appreciating that our relations with the local industry are relatively good, it must be pointed out that to preserve and improve this present situation a duty is owed to everyone connected with the industry (workers, share- holders, etc.) by management and unions to see that just and reasonable agreements are found for any disputes. If the companies ever take the local position for granted it would soon die, killed by someone who may get some short term benefit, but who would lose something of incalculable worth in the long run. Similar- ly if the unions were to adopt some of the "wild cat" methods adopted in other parts of

Jan 1, 1975

By T. Y. Yan

A method has been developed to remove calcite from the leaching circuit in the uranium in situ leaching system. The process involves injecting the leachate and a pH control agent tangentially into an inverted cone reactor containing calcite seed catalyst. The leachate can be treated at high throughput to obtain clear effluent containing 5 ppm or lower Ca. Both lime and ammonia are effective pH control agents and consumed according to stoichiometry.

Jan 1, 1983

By F. Touboul, M. Thiercelin, K. BenNaceur

Introduction The need to develop accurate predictive hydraulic fracturing simulators arises from the consideration of vertical containment for the fracture. Fracture height growth from a pay zone into adjacent layers has been shown (see Cleary [I]) to depend on three sets of parameters for the different strata: - elastic properties, - closure stress variations, and, -fracturing fluid leak off, and poro-elastic stresses. Qualitative analysis of the effects of these parameters has been reported in the literature. The first effects were described by Van Eekelen, using simple elasticity considerations [2]. The effect of stress variations was described numerically by Simonson and a1. [3] and experimentally by Thiercelin [4]. Effects of back stresses induced by fluid invasion on fracture propagation were considered by Cleary [5]. In order to couple these effects, a numerical code al- lowing the simulation of three dimensional growth of a hydraulically induced fracture has been developed with the ability of representing the effects of heterogeneities on fracture lateral and vertical extension. The model is based on a new variational formulation of the boundary integral representation of three-dimensional elasticity. The fluid flow and elasticity equations are solved using a moving mesh representation which offers enough flexibility to enable the simulation of any closure stress distribution. Simpler models representing fracture height growth (P3DH models) have been developed [6] [7] that approximate the fracture by a series of one dimensional segments, and the limitation of such approaches is examined in this paper. 1 Description of the model 1.1 Fracture Geometry Hydraulic fracturing simulations involve the coupling of solutions to elastic deformations, fluid flow in the fracture, and fluid leak off into the formation. Since the use of direct solution techniques (i,e,,3D finite elements) is prohibitive, the method used in this study is baaed on a boundary integral representation of the 3D elasticity equations. 1.2 3D Models The classical representation of the problem of a fracture in an infinite medium by boundary integrals is [8]: [ ] where u is the unknown displacement field, r n is the traction operator, I? is the fracture surface, and K is the Kelvin tensor of fundamental solutions to the elasticity operator. Using the notation: [ ] for the displacement discontinuity (or fracture width), one can attempt to solve the boundary integral relation using surface integrals (91 or the displacement discontinuity technique, first introduced by Crouch [lo], and extended to three-dimensional problems [Ill. However, numerical problems arise since the Kelvin tensor has a singularity in

Jan 1, 1986

By J. P. Dovel

Having been requested to prepare a paper referring especially to my patents as applied to blast furnaces, I shall confine my discussion to those improvements and inventions pertaining directly to the blast furnace itself, omitting a number of patents pertaining to blast furnace operations. I spent the early part of my life in the construction of blast furnaces, from rivet-heating to drafting and designing, much of the work relating to repairs and rebuilding. Later, as I became more interested in maintenance and operation of a group of blast furnaces, one fact especially made a lasting impression on me; namely, that a very expensive piece of equipment was very short lived, and the expense of replacement, relining, etc., in many instances consumed most of the profits made while in actual operation. As far back as 1910, I began to lay plans to build with a view to permanency and not merely for a blast, the common expression at that time, which really meant only one or two years in southern practice. Since we did not then blow so hard most failures occurred in the bosh and hearth. The failure of either generally meant a complete new lining, as the inwall did not look good enough to last another blast. At that time we were using two types of hearth, one of heavy steel plate protected by well and sprays on the outside, and one of heavy cast iron, made in sections and bound together with wrought-iron bands. The former type proved dangerous, for if the iron should come through, as it frequently did, it would cut away the steel plate, quickly turning large quantities of molten iron into the water, causing a severe explosion and costly repairs. The cast-iron type gave trouble also by the iron finding its way through the joints between the sections, which was not so serious, since the iron would not cut a way the heavy cast-iron sections very quickly, and generally caused only small damage, and repairs were easily made. Both types have been improved; the former by the introduction of cast-iron water-cooled plates, placed on the inside of the steel jacket. This has proved to be very good construction, but has no real claim to permanency. As the cast-iron plates cannot be replaced from the outside, the operator must assume that some time, at no late date, he must replace them from the inside, which will mean a blowing out of the furnace. The heavy cast-iron hearth has been improved by making the

By Jan M. Mutmansky, David R. Kalasky

Computer simulation continues to be one of the most successful analytical applications of computers in the mining and mineral processing industries throughout the world. Through simulation, managers and engineers can explore the impact of new technologies, equipment designs, plans and operating strategies to improve their operations. It is not uncommon for a single simulation application to provide a quick payback of analysis expenses (within weeks or months) yielding long-term financial and operational dividends. The paper will present a summary of the types of software systems that are available for use on PCs and other computer systems. Support software for curve fitting, statistical analysis, and optimization of simulation models will also be presented. Methods of leveraging simulation efforts through networking and coupling of software systems will be discussed. Finally, the trends in simulation in the mineral industries will be analyzed. Areas of strength and weakness of simulation will be discussed along with the usefulness of commercial general-purpose and custom-writ- ten simulation packages. The future possibilities for simulation in the mineral industries will be outlined and predictions on trends for the future will be presented.

Jan 1, 1996

By W. Spencer Hutchinson

THE outstanding engineering accomplishment of the last three decades has been the development and application of more and cheaper power and its use instead of the labor of men and animals. Substitution of power for manual labor has taken effect on every hand in the United States. With the aid of energy mechanically available to his hand, one man does the work that only a few years ago required two, three or even a greater number of laborers. The results in respect to the favorable economic effects are well known; namely, increased production, higher wages and lower costs. On the other hand, the vast social effects, both good and bad, have been none the less important, even if less understood and only casually regarded. The chief sources of energy today are the mineral fuels, coal and petroleum. In the United States they yield more than 90 per cent of the total energy demand. Thirty years ago the proportion of energy supplied by the mineral fuels was likewise above 90 per cent, but the division according to origin was very different. These relations. are shown for the years 1900, 1930 and 1950 in Table 1.

Jan 1, 1933

By K. R. Y. Simha

Successful explosive gas well stimulation requires a thorough understanding of explosively driven cracks under confining in-situ stresses. In a previous paper (Simha, et a1 1983) the problem of explosively driven cracks was experimentally investigated to reveal the features of crack propagation. It was observed that the explosively driven crack propagation is the result of two different but overlapping phases. The first phase involving the initiation and early time crack propagation is entirely governed by the explosively generated stress transients. The rapidly decaying stress transients then lead to the second phase of crack propagation largely controlled by the in-situ stresses. The purpose of this paper is to more fully understand the characteristics of the first phase concerning the initiation and early time propagation of explosively driven cracks. Experiments are conducted with plastic models under biaxial compression and the dynamic event is observed with a high speed multiple spark gap camera of the Cranz-Schardin type. The experimental observations are utilized to propose analytical models of crack initiation under explosive loading to aid in the design of multiple fracturing necessary for successful application of modern well stimulation techniques.

Jan 1, 1984

By H. O. Harju

In July 1968, P.T. Inco Indonesia was granted a Contract of Work to explore and develop the nickel laterite resources on the southeastern peninsula of the island of Sulawesi. Since 1970, exploration has centred on the deposits at Soroako as the site for initial project development. This paper describes the exploration methods used to evaluate these rather unique laterite deposits, the geology of which is described in the first section of this volume.

Jan 1, 1979

By Sarah Guzzelli, Enrigue Munaretti, Anneliese Botelho, Jair Koppe

Drill and Blast (D & B) is one of the main operations in the mining production cycle, which aims to fragment rock according to a pre-defined plan for proper loading, haulage and processing specifications. In this sense, data from a Brazilian iron ore mine was analyzed, given emphasis on blasthole length, subdrilling and stemming. The D & B report, including mining data such as number of blastholes, length, and diameter and stemming aspects, was analyzed in order to be able to compare these results with the blast design. The study showed significant differences between the designed blasting pattern and that one obtained by the operation. As a consequence, problems such as inadequate fragmentation, incorrect size distribution and loss of energy, were identified. For example, when stemming has a different length than it should have, noise and flyrock can occur, including inadequate fragmentation and vibration in both situations. Therefore, a comparison between the usual D & B procedures and recommended D & B design based on literature reveals the most important deviations and their consequences. The study intends to identify solutions for simple problems, improving D & B operations and safety practices.

Jan 1, 2014

By G. T. Lineberry, B. R. Yama

Artificial intelligence research has produced several tools for commercial application. Some of the techniques that are widely used today include neural networks, fuzzy logic and expert systems. Artificial neural networks (ANNs) are excellent predictive, pattern recognition and data analysis tools. In the mining industry, ANN techniques are being used commercially for real-time process-control applications. Modeling of spatial data, ore-reserve estimation, tunnel design, long wall-stability prediction and geologic roof classification are additional applications in which neural networks have been applied successfully. In this study, a standard back propagation algorithm was used to train a series of neural networks for a real-world predictive task. After training and optimizing the neural network architecture, the performance of the network is measured on an independent validation set. Results indicate a mean error of less than 1 % between the actual and predicted values. A neural network model was developed for learning the spatial continuity of a mineral field and, consequently, for predicting sulfur values for given coordinates. The neural network not only performed satisfactorily, but in some cases performed even better than the kriging model.

Jan 1, 2000

By John Griffen

The modern anthracite breaker or washery uses almost exclusively a wet method of preparation, which requires, roughly, 1 gal. of water per minute per ton of production per day. The entire anthracite industry uses about 320,000 gal. per min. of water for this purpose or 800,000 tons of water per day. As this water leaves the breakers, it contains fine solids—coal, slate, pyrite, and clay—and is then called silt or slush; as slush is the term most commonly used, it will be employed throughout this paper. The solid content of the slush will be referred to as solids. In the earlier days of anthracite mining, little coal was washed, less crushing was employed, and virgin coal was mined exclusively. As a result, the slush problem was not acute because of the relatively small quantity and the coarseness of the solids. Such slush as was produced could usually be easily impounded and retained or could be discharged into streams without any appreciable pollution being apparent. The character of the fine waste from the breakers changed materially as its quantity increased until now about 40,000 tons of slush solids are produced daily. Second mining and robbing operations materially increased the quantity of fine solids delivered to the breaker in the mine car. The demand for chestnut, stove and egg sizes, to the exclusion of grate, steamboat, and lump sizes, requires finer crushing of the mine-run coal with a consequent increase of fine solids in slush. The use of rice and barley sizes removed a considerable tonnage of coarser solids from the slush but left great quantities of fine solids difficult to retain completely, and to store, and long considered of no possible fuel value. Despite the efforts of the coal operators, the slush solids have found their way into the streams causing, in some cases, serious pollution. The Water Supply Commission of Pennsylvania published, in 1916, a report on Culm in the Streams of the Anthracite Region,' from which the following is taken: About 40,000,000,000 gal. of water carrying 10,000,000 tons of fine culm are discharged into the water-courses direct, flushed into the mines, or disposed of by various means on the surface. The extent to which the very small sizes of anthracite have been deposited in the rivers draining the coal fields is made evident by the fact that over a quarter of a million tons are recovered annually from the river beds by coal-washing operations.

Jan 1, 1922

By Alejandro Rosario, Ricardo González

The restrictions imposed by the Brazilian environmental legislation regarding natural caves lead to a block of substantial amount of mineral reserves. Mining activities can released caves, as long as the company ensures that the activities will not cause any damage to them, requiring profound and time-consuming studies. Since the use of explosives in the mine are potential sources of some damage to any structures, it leads to a deep need for controlling the rock blasting activities. In this context, the maximum charge per delay used in operations close to cave regions must follow some internal blasting assumptions that have been developed during specific tests and mining activities. By the seed wave technique, it is possible to determine the behavior of a seismic wave, which travels through a rock mass and it is generated by blasting a known explosive charge. This technique has proved to be an effective tool because it is able to accurately include the physical characteristics of the rock and different lithologies. This paper discusses about modelling blasting induced vibrations in order to improve caves protection, which surround the mining operations.

Jan 1, 2019

Selection of mining methods, stope dimensions and stoping sequences is usually based on comparisons with other similar orebodies or rocktypes. Rock mechanics principles assist the process, which can be further improved by application of rock mechanics' models - in particular, computer based stress analysis techniques. These models vary in capabilities and potential application but, basically, can be subdivided into techniques which only model the surface of excavations, and those which model the total volume to be analysed. To address the wide range of geometries, stoping methods and sequences, and geomechanical environments at Mount Isa Mines, a number of models have been developed. By presenting examples of their actual and potential application it is demonstrated that appropriate use of these techniques will assist in the determination of mining parameters and improve ore recovery. Examples presented cover sequencing in tabular and massive orebodies, location of shafts and shaft pillars, and backfill and hanging-wall stability. It is concluded that surface techniques are more appropriate for regional analyses and volume techniques are more suited to analyses of detailed, local geometry. Colour computer graphics should be an integral part of data preparation, and results interpretation and Presentation.

Jan 1, 1986