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By Vishnu S. Gupta

A modular computer program APEX (AMAX Process Evaluation Executive), has been developed at AMAX Extractive R&D, Golden, Colorado to facilitate rapid simulation of steady state material and energy balances of existing and/or proposed metallurgical process flowsheets. Currently, APEX is being used for the design, analysis, and evaluation of several of AMAX?s Nickel, Molybdenumand Tungsten processes. A unique feature of APEX is that it allows specifications of flow rates and compositions for different solid size fractions in addition to aqueous organic and gaseous phases. Thus, a metallurgical process which may involve crushing, grinding, flotation, leaching, washing, solvent extraction, precitation and refining operations can be simulated in a single computer run using APEX. APEX requires two input data files. The first is a process data file which includes physical and thermodynamic properties of the various chemical components of interest. This data file is unique to the process under study and does not require changes for alterations in the process flowsheet. The second data file is specific to a simulation case and includes descriptions of the flowsheet, various feed streams and the process equipment's operating conditions. In addition to temperature, pressure and percent solids, calculated information for each stream includes weight and volumetric flow rates, chemical compositions, specific gravities and enthalpies of solid, liquid and gas phases. For each process equipment in the flowsheet, APEX prints its operating conditions and detailed information about the streams that enter and leave the unit. Models of several general unit operations are preprogrammed in APEX. Also, the modular design of APEX permits quick and easy additions of simulation models which are specific to new and/or unique process operations. To study process stability and optimization, APEX permits several cases of a flow-sheet to be run together. Three simulations of the Moa Bay Nickel process have been excluded to illustrate the ease and flexibility of using the APEX system.

Jan 1, 1980

By Antonio Nieto

According to the analysis of surface powered haulage accidents involving off-highway haul trucks in openpit mining, the U.S. Mine Safety and Health Administration (MSHA), reported 1,300 fatal accidents from 1990 to 2005. Of these, 163 were considered off-highway truck haulage accidents, and at least 23 involved collisions of an off-highway truck with a neighboring vehicle or a worker on foot (Nieto and Dagdelen, 2006). In general, an average of 18 nonfatal accidents and three fatal accidents occurred in openpit mining per year when equipment backed over the edge of an embankment, stockpile or dump point (Fessak, et al., 2003). The specific problems that need to be solved can be determined by carefully studying the accidents involving haulage trucks (Marrara, et al., 2004). Solutions to haulage truck safety must consider the human factors affecting each task even when engineering solutions seem most appropriate. In surface haulage, human performance becomes a critical issue because of the unusual demand the vehicle?s places on their human operators: ? Roadways and working areas change frequently in mining operations. ? The sheer mass of mining equipment such as trucks requires control inputs (e.g., braking) far in advance of the desired action. ? Rough roads, loading and unloading impacts can subject the driver to dangerous shocks and vibration. ? Visibility is sharply curtailed by the bulk of the vehicle generating large blind spots. All of the above issues can be attributed partially to the lack of visibility (Pyles et al., 2003). Driver visibility and communications are key issues to reduce mining truck accidents. Analysis of fatalities and injuries involving mining equipment demonstrates the need to develop new intervention and control strategies to mitigate the risks associated with mining equipment operation. Ongoing development of these and other new strategies is required to achieve a reduction of injury in the mining industry

Jan 2, 2010

By E. A. Twichell

An entirely new concept in the effective utilization of magnetic, energy has resulted in a major break-through in the design of magnetic separation equipment. One of the first applications of this concept has resulted in the development of a Permanent Magnetic Wet Drum Separator with strength .and operating characteristics equal to Electro Wet Drum Separators. Prior to this development when strength and adjustability were required, electro wet drums were specified even with all their drawbacks. The electros, by nature, are subject to coil failure or burnout, over-heating and loss of strength, high power consumption and generally high maintenance. Now the high strength and the adjustability, formerly the exclusive property of electros, has been engineered into permanent wet drum separators. These units combine maximum field strength in the separation zone with strength adjustment to suit changing conditions. Adjustment can be effected while the drum is in operation without stopping either the feed or the drum.

Jan 1, 1967

By G. Perkins

The development of the mineral industry of Jamaica has been guided by an unwritten policy which has nevertheless been reflected in various pieces of mining legislation and by case-by-case approvals of incentive packages for non-bauxite minerals. An effort has now been made to bring together in one minerals policy document, all the policy elements that have guided our laws and actions thus far and to upgrade the final version to meet the challenges of the next century. In this regard, industrial minerals will be placed on a more equal footing with bauxite, especially in terms of investment incentives.

Jan 1, 1998

By P. M. Krishna

An example illustrates the use of ASTM Standard E901-82, Classification System for Uranium Resources. The example demonstrates the dynamic nature of the process of classification and attests to the necessity of addressing both the aggregate needs of broad-scale resource planning and the specific needs of individual property evaluation. Problems that ,remain in fixing the classification of a given uranium resource include the uncertainty in estimating the quantity of undiscovered resources and resolving the differences that may exist in deciding when the drill-hole spacing is adequate to determine the tonnage and grade of discovered resources.

Jan 1, 1983

By Hassan El-Shall, Rosana M. Macedo Borges, Ponisseril Somasundaran, Regis Stana, José Renato B. Lima, Patrick Zhang

The phosphate fertilizer industry is a large activity in Brazil because the soil has a phosphorous deficiency. The phosphoric acid that is produced is extensively used in the production of fertilizer. It is produced by reacting phosphate carbonaceous rock with sulfuric acid, generating phosphogypsum as a by-product. In 1991, there were about 29 million tons of phosphogypsum stored in Brazil. This has increased to an estimated 280 million tons in 2001. While the phosphogypsum is used in the cement industry and also in agriculture, the quantity used is much less than the production rate, and the stockpiles are still increasing. The radioactivity of this waste may not allow its continued use as a construction material and some other uses. However, Brazilian phosphogypsum contains a smaller quantity of radioactive materials than is reported for phosphate rocks from other countries. One important reason is the geological origin of the Brazilian apatite. All the large deposits being currently mined are igneous, not sedimentary, as is the majority of the phosphate rock produced around the world. An extensive study is being conducted to characterize the phosphogypsum generated in two production facilities in Sao Paulo state to develop safe uses for this waste and determine the environmental impact caused by the present method of phosphogypsum disposal.

Jan 1, 2002

By F. Rosenblum, P. Cancilla

The manual moisture determination methods employed today by mineral processing plants falls short in providing timely information required for automatic control. The costs associated with transporting and handling concentrates still represent a major portion of the overall treatment price. When considering the cash flow of a mining operation, that is governed by both the smelter contract, with moisture penalties and the quantity and quality of the concentrates shipped, an efficient method of on-line moisture content would be a welcome tool. A novel on-line determination system for ore concentrate moisture content would replace the normally tedious classic manual procedure. Since the introduction of microelectronic¬based control systems, operators have strived to reduce the treatment costs to the minimum therefore a representative and timely determination of on-line moisture content becomes vital for control set points and timely feedback. Reliable sensors have long been on the "wish list" of mineral processors since the problem has always been that you can only control what you can measure. Today, the task of moisture determination is still done in the classical technique of loss in weight utilizing uncontrolled procedures. These same methods were introduced in the earliest base metal concentrators. Generally, it is acceptable to have ore concentrate moisture content vary within a range of 7 to 9%. Many times, delays in manually achieving reliable feedback on the moisture content results in the moisture varying from 5 to 12% before corrective actions can be made. This paper first reviews the traditional and widely available methods for determining moisture content in granular materials by applying physical principals and properties to measure moisture content. All methods are in some form affected when employed on mineral ore concentrates. This paper describes a unique and promising on-line moisture sensor in two mineral processing applications, which not only automates the tedious tasks but also results in reliable moisture feedback that can be used in the optimization of the de-watering process equipment such as pressure or vacuum filters and fuel-fired driers. Finally, two measurement applications will be presented to indicate the usefulness and to summarize the measurement requirements for the proposed method of employing drag force and mechanical properties of the material itself to determine the moisture content.

Jan 1, 2002

By Wallace W. Roepke, Richard C. Olson

To adequately attack the longwall dust problem, the US Bureau of Mines funded a contract to define dust sources on a longwall mine face area. The study examined the shearer during sumping, cutting, and tramming, the conveyor, and the roof supports. Tests showed the shearer to be the major dust source. Introduction Long-term illnesses place a heavy burden on miners, the mining industry, and taxpayers. Black lung payments to more than 400,000 miners and their survivors exceeded $9 billion between 1970 and 1980. They are continuing at a rate of $1 billion per year. Recent MSHA data indicate more than 50% of the longwall faces are still out of compliance with the 2 mg/m3 (0.00007 oz per cu ft) respirable dust regulation. Allowable dust limits are often further reduced owing to the presence of silica dust. This substantially increases the problem's severity. Research in the 1970s showed that by modifying the mining method through changing drum-type mining machines from high rpm shallow cutting to slow rpm deep cutting, both specific dust and energy could be reduced (Black et al., 1978; Ludlow and Wilson, 1982; Roepke, Lindroth, and Myren, 1976). The coal mining industry is using more longwall equipment to economically obtain high productivity. This high production rate, however, makes it difficult for longwalls to meet the legal dust standard. Research is showing how both these concerns may be addressed at the mining face. Results reported here explain the relationship of various major elements of the longwall system to dust generation on the longwall face. This paper is based on work completed by Foster-Miller Associates Inc. Objectives were to differentiate dust sources on the longwall face and to quantify dust levels for various elements of the shearer drum. The work was accomplished in two phases. Jonathon Ludlow, project engineer for FMA, developed and performed the necessary testing (Ludlow and Marshall, 1983). Bradley, Hadden, and Weston (1983) have done evaluations on British coal mines that produced similar results to those reported here. They found causative rela¬tionships between haulage speed, production, depth cut, drum speed, and dust generation. They also found that roof support movement increased the dustiness, whereas this work indicated that support movement had only a minor effect on total dust exposure. Both of these results are valid when the variation of mining conditions is analyzed. British mines are deeper than US mines. Therefore, roof rocks and coal are more fragmented than in the shallower US mines. Other reasons for the dust differences include the weaker shales found in Britain and the variation of roof support equipment designs between the UK and the US. Four mines in this report had rock roofs and, thus, would be less dusty. The fifth longwall mine had a coal roof, but the large cross-sectional area and high air velocity minimized dust exposure. Mines and Equipment Five underground longwall mine sites were tested (Fig. 1). All were using double-ended ranging-drum shearers (derds) with some variations in equipment. The mines and equipment details are shown in Table 1. No modification of mining equipment or operating cycles was made during the first phase of testing. The mining process observed followed the normal mine operating procedures. Three GCA RAM-1 respirable dust monitors and two vortex anemometers with cycle notations on portable tape recorders were used in each face area. The start and end of each cycle segment were recorded. Dust monitors record the dust levels once every 10 seconds, thus providing a relatively continuous real time indication of change in

Jan 8, 1984

By Edward R. Borcherdt

When one considers the advancements made during the 25 years prior to the late fifties, and compares these advances with the progress made in the past decade, the comparison is indeed startling. It was not until 1935 that trucks began to replace rail as a major hauling facility, Initially, the haulage capacity of end dump trucks was limited to 18 or 20 tons. "Straight stick" transmissions were utilized and the available horsepower was minimal. In the early forties single planetary axle 25 ton trucks were introduced, and shortly thereafter those were followed by 35 ton tandem axle units.

Jan 1, 1967

By Raul A. Deju

This paper shows how one can relate the chemical reactions between water and a silicate bed to the equations of flow. First the reaction mechanism is studied both theoretically and experimentally. Once the reaction mechanism is established, the equations of flow are solved and a solution (under physically reasonable side conditions) is obtained. Experiments to substantiate the solution are also presented.

Jan 1, 1969

By P. R. ZETTWOOG

HISTORICAL BACKGROUND A program in France to develop personal [a] dosimeters has been initiated 1974. The patent on which is based the present device was obtained in 1972 * . From 1972 to 1974, the possibilities of applying certain ionograph track detectors to the spectrodosimetry of radon daughters was explored. The first prototype were produced in 1974. It took four years (from 1974 to 1978) to produce an autonomous dosimeter whose components has a sufficient life span, especially for the turbine motor unit. Qualification in the laboratory was obtained in 1977. In 1978 it was obtained in the mine for technology (autonomy of 12 hours and a life span of more than one year) and in 1980 for monitoring. 300 dosimeters have been tested in underground mines all together. Indispensable peripheral equipment were also developed from 1976 to 1980 : calibration devices, equipment to prepare and develop the films, read out systems. The concept of an "Integrated System of Individual Dosimetry" (ISID) based on a personal [a] dosimeter measuring exposure to radon daughters, thoron daughters, ore dust and external irradiation doses was proposed at the end of 1980. Since January 1st 1981, ISID is used on a routine basis in some french mines, situated in remote area, and appears to be very competitive with the ambiant dosimetry. The latest version of the dosimeter is produced in mass series since June 1981 and should equip all french mines in 1982. DESCRIPTION OF THE INSTRUMENTATION DEVELOPMENT OF THE DOSIMETER MEASURING HEAD The measuring head is based on the use of ionographic film to detect a tracks. In fact, the measuring head is a spectrodosimeter which measures separately over the period of exposure: - the potential [a] energy inhaled due to the decay of Po 218, Po 214, and Po 212 ; - the number of Rn 222 atoms inhaled ; - the inhaled total [a] activity of the five long-lived emitters present in the ore dust. The contribution to the total inhalable potential [a] energy of these various radionuclidesin a typical underground mine is studied in Appendix I. The measuring head described in detail in Appendix II, is able to satisfy all the implications made in the ICRP recommendations. Appendix III deals with the use of this measuring head in the cases where the equilibrium factor is lower than 0.1. This situation occur in open-pit mines where account must be taken of the Rn 222 contribution, which is no longer negligible in relation to that of its daughters. CURRENT DOSIMETER PERFORMANCES Table I shows the characteristics of the latest dosimeter. Appendix IV should be consulted concerning qualification of the dosimeter in the laboratory and in mines, technological development which finally produced the [a] dosimeter and its peripheral equipment, and technical presentation of the ISID (Integrated System of Individual Dosimetry) based on the concept of a multirisk personal dosimeter. Data on the installation and operating costs of such a dosimeter, which would seem to be competitive, are also given in this Appendix. ADVANTAGES OF PERSONAL DOSIMETRY AS COMPARED TO AREA MONITORING The results of the first eight months of experiments carried out under real conditions in an underground mine site are given in detail in reference 8. Area monitoring : The monthly exposure per worker to inhaled Rn 222 was determined from the knowledge of time spent in various areas of the mine and for the different mining operations, as well as from numerous and systematic sampling of the Rn 222 concentration in all work places. Personal dosimetry : The exposure to potential energy from radon daughters was measured by an [a] dosimeter developed by the CEA and worn by each of the 160 miners during eight months. In this way 160 x 8 pairs of monthly individual exposure values have been obtained which can be statistically studied. This test was decisive for us because it proved that the [a] dosimeter was technically sound (very few defects over one year for 160 dosimeters) and especially that personal monitoring devices were superior to area monitoring devices. The following conclusions can be drawn 1. The exposure distribution obtained by personal dosimetry is log-normal. This is true for the results on the whole as well as for groups of results relating to certain explanatory variables. See fig. la, 1b, 1c. 2. The exposure distribution obtained by area monitoring does not correspond to any type of distribution. If the results of personal monitoring are taken as a reference, area monitoring tends to underestimate the high exposures and overestimate the low exposures.See fig. 2. 3. [a]-energy exposures are underestimated when calculated from radon exposures and the equilibrium factor found in the considered mines. This is due to episodes or to zones of high radon concentrations not registered

Jan 1, 1981

By K. Oraee

A comprehensive, harmonic and sustainable development has always been a real concern of state policy makers. To reach such development, regional planning is an approach which is widely applied. This paper deals with policies adopted by a given country with rich mineral deposits, in order to accomplish a mining growth as well as economic development in relatively poor regions. In this regards, first, some worldwide experiences belonging to China, with large scale mining operations and Nigeria with a small scale mining industry, are studied. The mining industry in Iran is then considered as a case study. The study continues by categorizing and prioritizing Iranian regions based on their mining potential and the degree of development, using statistical analysis and Taxonomy and AHP techniques. Results obtained serve to provide recommendations as to where capital investments in the mining industry would produce highest returns. The approach used, together with the practical policies suggested in this paper, can be used to adapt appropriate strategies for mining development in a way that contributes to regional development and a more effective income distribution.

Jan 1, 2012

By Bond. F. C.

Introduction Although autogenous grinding applications date back to the early years of mineral processing when tumbling-type mills were first used, there has been a renewed interest in this type of grinding over the past few decades. A review of the historical aspects of autogenous grinding is provided which follows the development of the various types of mills and processes. Wet and dry grinding operations using either autogenous or semiautogenous mills, including the Aerofall mill, are described. Em¬phasis has been placed on the test work required to evaluate the feasibility of using autogenous or semiautogenous grinding for a spe¬cific application. The factors which must be considered to establish the appropriate design criteria for these types of grinding circuits are discussed in detail. Successful application of these grinding circuits results from a thorough test program, a careful analysis of the test results, and a practical engineering approach to the design of the process flowsheet and milling equipment. Certain pebble milling applications, where the pebbles consist of the ore or rock itself, can be classified as autogenous pebble mill grinding, or better known as ore-pebble mill grinding. In the generic sense, pebble milling includes those grinding operations using a tum¬bling mill in which the grinding media consists of various types of pebbles, either ore or other pebbles, instead of metal balls. Conse¬quently, this subject is covered separately in Chapter 5, Pebble Mills. Operating data from many of the installations located throughout the world are included in this chapter. Our appreciation is extended to those companies who contributed this important information. History of Autogenous Grinding F. C. BOND Autogenous grinding, the grinding of ore by itself rather than by special metallic or nonmetallic grinding bodies distinct from the ore, has an old and honorable place in the art of mineral processing. It antedates the use of the rod mill and is only a few years younger than the development of the continuously fed rotating tumbling mill in which it is accomplished. Its history71, 72 is inextricably bound up with that of gold mining. Every important early development of autogenous grinding took place on ores of gold, except in one case of silver ore. In common with many other features of modern mineral processing, autogenous grinding would have been greatly retarded if the winning of gold had been so small a part of mining in the past as it is today. Gold unlocked the secrets of rock-on-rock grinding. In years past gold ores were crushed in stamp batteries and then flowed over copper plates covered with mercury which amalgamated the gold. The McArthur Forrest cyanide process for the dissolution of gold in a dilute alkaline cyanide solution appeared in 1890. With finer grinding it recovered more gold than could be won by amalgama¬tion alone. The first response was to stamp in cyanide solution and finer mesh screens guarding the stamp discharge. However, the fine screens greatly restricted the tonnage stamped, and they wore out rapidly. Rotating tumbling mills70, 73 were the obvious choice to grind the coarse product from stamps. Many of these were Gates tube mills; more than 1,000 of these were sold between 1907 and 1913. They were made in 6, 51h, and 5 ft diam, with lengths of 20 and 22 ft. The 5 x 22-ft size was the most popular. The term tube mill did not refer to the mill shape, but included all tumbling mills using grinding pebbles. The flint or chert rocks found along the coasts of Denmark and Normandy are probably the most durable and resistant to abrasive and tumbling wear of any on earth. They were much used in the early tube mills. The early linings were all silex or Danish flint blocks, cemented into place with portland cement. Local hard stones or cast iron blocks were also used later. The cast iron liners carried lifters and were not bolted to the shell, but were held in a tight circle against it by steel wedges hammered home between them. The first ribbed metal liners designed to hold grinding pebbles pounded into them by the mill action were developed at El Oro, Mexico, about 1905. These and the Forbes, Komata, and Tonopah types, as well as the Osborne type developed in South Africa within about five years, were very successful in reducing liner wear. They sometimes lasted two years or more, and equalled or exceeded the life of silex lining at a lower cost. Some of the types were patented. The pioneer name recorded in the history of autogenous grinding is that of Kenneth L. Graham. In 1907 at the Geldenhuis Deep Ltd. mine near Johannesburg, he ran a comparative test on two tube mills. One mill used pieces of the common gold ore, or banket, and the other used the customary imported Danish pebbles as grinding media. He published the first account of autogenous grinding.'' In a test lasting 81 days the ore pebbles showed a definite saving over the Danish pebbles. Graham's historic paper also describes the invention of B. Chew of the Crown Deep Mines of the first trammel to be attached to a grinding mill discharge. The first known account of autogenous grind¬ing printed outside of South Africa was the description of the Graham test in Mining and Scientific Press's The use of grate- vs. overflow¬discharge was also described at this time." The news of this successful test appears to have had immediate effect, for by the end of 1908 the number of tube mills on the Rand had increased from 72 to 120.76 Presumably, most of these mills were now using autogenous grinding. The ore was principally a hard conglomerate of quartz peb¬bles cemented by silica, and was eminently suitable for use as a grind¬ing media. It is unfortunate that in South Africa the new autogenous process continued to be called by its old name of pebble milling, since the name does not distinguish between grinding with ore and grinding with extraneous pebbles. For increased clarity the former is called rock pebble milling. The first historical stage in the development was what is now designated as secondary autogenous grinding, or rock pebble milling. It consists of grinding a feed all passing 'A in. or finer with ore pebbles about 2 to 4 in. in diameter. The next stage to develop was that now called intermediate autogenous grinding, where larger amounts of larger pebbles about 5 in. in size were used to grind ore which had been crushed to about rod mill feed size or somewhat finer. It was developed on the Rand and in other places where coarse stamp screens were used to increase mill tonnage. In many cases the early secondary and intermediate autogenous mills have now been replaced by conventional ball mills and rod mill-ball mill circuits, with the object of further increasing grinding capacity. The third stage to develop is designated as wet primary autogenous grinding, in which run-of-mine ore or a primary crusher product is all fed to the autogenous mill together. It developed many years later indepen¬dently in the United States and in South Africa. The fourth and most recent stage is that of dry primary autogenous grinding, which developed in the United States and Canada. All four stages originated in gold mining. The first use of commercial autogenous grinding outside of the Rand apparently took place five years later in 1912 at the Santa Gertrudis gold mine at Pachuca, 55 miles northeast of Mexico City. This was followed closely by an installation at Goldfields, Nevada, in 1914-1915. The first name associated with autogenous grinding

Jan 1, 1985

By W. Petruk

Imaging is a fundamental requirement when characterizing minerals, ores and related products. Images are used for presentation, texture analysis, characterization, image analysis, identification, etc. The image mode that is utilized is dependent upon the application, mineral properties and available instruments. Different instruments produce images that display different features; in order of increasing complexity they are: hand specimens, a non-polarizing microscope, polarizing optical microscope, scanning electron microscope (SEM), low vacuum SEM, microprobe, secondary ion mass spectrometer, staining, cathodoluminescence, tomography and others. Image analysis uses images produced with either an optical microscope or a SEM, but the SEM images are superior in this application.

Jan 1, 2001

By David M. Parkes

Geology is frequently complicated, hence only more regular deposits are mined. Coal is generally thick, often steeply pitching and usually soft or well-cleated. Due to competition from open-pit mines, only two underground mines are operating, McIntyre and B.C. Coal. Several other mines are being planned, the method being evenly divided between hydraulic, longwall, and room and pillar. McIntyre mines in the flat part of their formation (up to 20 degrees) uses continuous miners and shuttle cars in the 3m and 6m seams. This company is considering a retreating longwall face. B.C. Coal operates a hydraulic mine in a 16m thick seam dipping at 10 to 55 degrees with a productivity of about 20 tonnes per manshift.

Jan 1, 1982

By Mark A. Koestel

Cobalt-sulfide mineralization can he found in potentially economic quantities where permeable, basal Cambrian formations "pinchout" against Precambrian pal eotopographi c highs. These environments are common around the Saint Francois Mountains of southeastern Missouri and they share many similarities with the geologic environments of Zambia and Zaire in South Africa. Exploration for this type of deposit involves test drilling targets identified by trend analysis from past drilling, geophysics, geochemistry and a comprehensisve study of regional geology and isopach maps. Innovative ideas, new exploration concepts and insoluble residue geochemical methods may provide the necessary "edge" needed to complement basic geologic understanding leading to ore discovery.

Jan 1, 1987

The ability to optimise a concentrator from mill feed to final products requires a simulator which integrates comminution, classification and separation modelling. In order to model this range of processes, such a simulator must handle a variety of information about the ore. The AMIRA P9 project has developed a whole-of-concentrator simulation capability which brings together a texture-based model of mineral liberation, quantitative X-ray micro-tomography analysis to measure the inputs required by this model, and a multi-component simulator software framework. In the context of this approach, the term ?multi-component? implies the ability of the simulation to handle many particle properties simultaneously; for example size, composition, density, floatability etc. The simulation software framework provides the means to manage the flow of data around a circuit flowsheet, allowing each process model to access the information relevant to that particular model. A case study based on plant data from a gold-bearing pyrite concentrator is used to demonstrate the capabilities of the multi-component approach in simulating circuits which contain comminution and separation processes.

Feb 27, 2013

By Lei Fu

In the wake of the collapse of the ceiling panels in the I-90 section of the Central Artery/Tunnel (CA/T) Project in 2006, the long term performance of tunnels became the focus of the tunneling industry. At the time of the accident, the tunnel had been open to traffic for about 10 years. This paper will discuss design methods and considerations to improve the long term performance and durability of a tunnel. The major problems found during the inspection of several tunnels will also be presented and the causes for these problems will be discussed.

Jan 1, 2008

By William J. Wiehagen

The training of mining personnel is a large and continuing activity for the mineral industries. Although safety and skills training has long been recognized as an essential element for reducing injuries and improving productivity, the research literature lacks definitive reports documenting the specific value of such training. The training literature presents a variety of testimonials as to the "benefits of training," but lacks data that specifically tie that training to the performance of the worker.

Jan 1, 1983

By Heinz C. Dittmar

The phenomenon of radioactivity has been known since the turn of the last century. Scientists of many nations, intrigued by the strange effects of radioactivity, have engaged in research to probe the heretofore presumed, but largely unknown world of atomic structures and subatomic- particles. A theory evolved of splitting the atom, thus providing insight into the structure of matter and opening the way to possibly create new materials. Many years of effort culminated in the first chain reaction in 1942. The beginning of the atomic age was drastically demonstrated by the flash of the large scale chain reaction of the first atom bomb. It was actual proof of the incredible energies contained in matter.

Jan 1, 1966