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By John A. Herbst, Kuang Y. Lee

Coarse particle size measurement is essential for the automatic control of a size reduction process like crushing or SAG milling in order to achieve optimal process performance. However, the on-line size measurement of coarse material is not easily obtained due to the problems of material handling and sample statistics. A technique based on advanced image analysis and quantitative stereology has been successfully developed and tested in a pilot scale setting. The chord length distribution of coarse particles on a moving conveyor was measured with an image analyzer and then transformed to the mesh size distribution with a stereological model and a special numerical method. Some test results as well as the technique's industrial suitability and limitations of this method are also discussed.

Jan 1, 1992

By E. J. Rogans, W. N. Cartner

Carbon technology has largely superseded filtration plants as the more acceptable gold recovery technology. This has, over the last two decades, provided a tremendous driving force for the development of new equipment. One of the main focus areas of this technological development is the development of effi­cient interstage screening systems. Several variations of exter­nal and internal screens are available, with the more recent shift away from air cleaned units to mechanically swept units. This paper discusses the development of one such mechanically swept interstage screen and how the development led to the suc­cessful implementation of a carousel type of CIP operation. The first generation Pump-cell emerged as a consequence of the success achieved with the mechanically swept NKM screen, The idea was to modify the screen to incorporate the functions of pumping, screening and agitation in a single drive unit, the screen generating sufficient lift for interstage slurry flow so that all contactors would be at the same level. This sys­tem was further incorporated as a high intensity modular CIP contactor, i.e. low slurry residence times combined with high carbon concentrations. A discussion on the kinetic gold adsorp­tion theory and its manipulation in the design of the pump-cell concept is discussed in a paper published in a previous Randol Conference< 1), Testwork carried out at Vaal Reefs proved the concept of the Pump-cell on a pilot plant scale<2), which resulted in the building in 1990 of the first large Pump-cell plant at West Witwatersrand Gold Mine designed to treat 340m3 of pulp per hour and , even though the plant operated successfully with respect to gold recovery performance, a few problems were experienced with the basic engineering design(3),

Jan 1, 1996

By T. E. Walsh

Introduction I will address two important alternative energy resources, solar and geothermal, with emphasis on their potential application in electric power generation. As a result of this presentation, I hope to leave you with a realistic view of the principal technology options that are being developed or that are available. Solar Types of Collection In terrestrial solar applications, the biggest challenge is to find ways of collecting the sun’s relatively low intensity energy so it can be converted economically to useful thermal or electric energy. Fig. 1 shows that there are both natural and technological ways of collecting solar energy. In nature we find that solar energy aids in the production of biological growth, rainfall, and wind, all of which can, in one form or another, be put to use in the production of heat or electric power. The sun’s rays also are collected and stored naturally in the form of heat in the upper layers of the ocean which can be put to use in the production of electric energy by means of ocean thermal energy conversion (OTEC) approaches. On the technological side, the sun’s rays can be intercepted by materials that directly absorb and convert its energy to low-grade heat, or by mirrors or lenses that focus the rays onto a material to produce high-temperature heat. The higher temperature systems can be used to drive efficient heat engines in the production of electricityy. The sun’s rays also can be collected on photosensitive materials, in either a direct or concentrated form to generate DC electricity directly. The systems I will discuss employ all of these means of collection and conversion, excluding biological and hydroelectric. The former is too ex

Jan 1, 1980

By T. E. Walsh

I will address two important alternative energy resources, solar and geothermal, with emphasis on their potential application in electric power generation. As a result of this presentation, I hope to leave you with a realistic view of the principal technology options that are being developed or that are available. Solar Types of Collection In terrestrial solar applications, the biggest challenge is to find ways of collecting the sun’s relatively low intensity energy so it can be converted economically to useful thermal or electric energy. Fig. 1 shows that there are both natural and technological ways of collecting solar energy. In nature we find that solar energy aids in the production of biological growth, rainfall, and wind, all of which can, in one form or another, be put to use in the production of heat or electric power. The sun’s rays also are collected and stored naturally in the form of heat in the upper layers of the ocean which can be put to use in the production of electric energy by means of ocean thermal energy conversion (OTEC) approaches. On the technological side, the sun’s rays can be intercepted by materials that directly absorb and convert its energy to low-grade heat, or by mirrors or lenses that focus the rays onto a material to produce high-temperature heat. The higher temperature systems can be used to drive efficient heat engines in the production of electricityy. The sun’s rays also can be collected on photosensitive materials, in either a direct or concentrated form to generate DC electricity directly. The systems I will discuss employ all of these means of collection and conversion, excluding biological and hydroelectric. The former is too exi

Jan 9, 1980

By Michael Chender

Introduction Clearly, many problems confront the minerals industry today. Yet, at the same time, there is too much energy spent bemoaning the negative effects of difficult economic circumstances, low metals prices, and adverse government policies. These are factors that cannot be altered by individual mineral company reactions. In fact, as we look to the future, the only thing we can be certain of is that we will continue to be faced with uncertainty. Thus, an area that demands close scrutiny and that can significantly affect a company&apos;s performance in the future is the posture it adopts to deal with uncertainty. This paper looks at how strategies are developing to deal with this issue. It also examines some of the implications that implementing such strategies have for the role of the individual explorationist. Elements of strategy Whether mineral company strategies are based on diversifying or retrenching, on emphasizing primary production or downstream integration, there seems to be increasing agreement that in the current environment strategies must have several features. They need to be information-based - developed out of access to timely and complete data and analysis about proposed directions and competitor activity, rather than simply following a current fashion. They need to be flexible - adaptable in light of changes in the marketplace and an unpredictable industry. And they need to be cost-efficient - making the most of limited resources. Whether a company is looking for gold financing opportunities, acquiring polymetallic prospects, or doing grassroots exploration for diamonds, these three elements are increasingly essential. They not only allow the company to pursue its current goals most expeditiously, but also open it to hearing and using feedback in the most constructive way. The company can then improve or change strategy as it proceeds. And it can be best positioned to take advantage of opportunities as they arise. These elements of strategy place great emphasis on the skills of the individual. The need for critical intelligence and the reduced amount of capital available to manage are making it more obvious that exploration is a "people" business. This is in accordance with a general trend in many sectors of industrialized economies, reflecting the widely discussed shift from smokestack to information-based industries. Increasing the odds There is a direct connection between successfully implementing the approaches to strategy discussed above and encouraging and improving the quality of work of the individual explorationist. To illustrate the importance of this, some commonly quoted figures on the odds of discovery success can be used. These figures are arbitrary but illustrative. Assume that one out of 100 exploration prospects actually turns out to be a promising ore body, and that one out of 1000 becomes a mine. Based on our research, chances are the most of those

Jan 1, 1986

By Paul D. Tomlingson

Part one of this two-part series covers conceptualizing and developing a maintenance information system. It explains what information is necessary to manage such a system. Next month, part two will discuss using this type of system with administrative information, including error and absentee reports as well as open work files. Introduction There is no doubt that quality, timely, and accurate information can make a solid contribution to maintenance cost reduction objectives. Yet, despite obvious benefits, methods being used to acquire information systems are proving costly, frustrating, and often unsuccessful. Those needing the information are disappointed. Mine managers, hoping to reduce costs with quality information, are instead seeing no system, no savings, and massive spending on information endeavors of questionable benefit. Options Any software vendor will happily sell you his program. Numerous mining organizations, having "gone to the cleaners" themselves, will gladly make their programs available to help cover huge trial and error development costs. Any package can only be a generalization. Any program bought from some other organization must undergo numerous modifications to make it work properly. In the process the initial cost is doubled. Many mining maintenance organizations do not know how to go about the task of conceptualizing, developing, installing, and effectively using a maintenance management information system. Consequently, many have hedged their primary responsibility of specifying what information they want, how they will get it, and how they will use it effectively. Into this void have jumped many who claim they can help. But some may not understand the special information needs of maintenance in the mining industry. By default, the whole scene of maintenance information systems has become confused and in need of clarification. A Starting Point Four broad phases are used to organize the steps by which maintenance acquires an effective maintenance management information system and initiates its use. Conceptualization is an identification of needs, factors that influence development, and an assessment of support for the system. Development is a plan of action for bringing the conceptualized information system to life. Consideration is given to the practical aspects of collecting field data, processing it, and converting it into useful information. Implementation consists of those actions by which the newly developed system is integrated into the organization and put in the hands of its personnel so that its value can be derived. Use addresses the means by which personnel use the information to accomplish maintenance improvement objectives. These phases are preceded by establishing the need for the information system. They are followed by a requirement to measure its success (Fig. 1). Conceptualizing the Information System Responsibilities - The information system user must acquire the system best suited for its use. A step-by-step process is essential to avoid many serious problems than can easily occur. The most important step is to clearly identify its objectives and lay out a course of action to achieve those objectives. The major reason for the failure to achieve information objectives is not carrying out this responsibility. Maintenance cannot delegate the task to data processing. It can obtain technical assistance but it must retain responsibility. Nor can maintenance purchase

Jan 7, 1985

By Steve Kral

The mining industry in northern Ontario is known mostly for its huge nickel deposits. Inco’s and Falconbridge’s nickel mines in the Sudbury Basin are the best known. And with nickel prices being what they are, interest in the region continues. And how. Inco and Falconbridge want to merge. Teck Cominco wants Inco, but without Falconbridge. Xstrata made a hostile bid for Falconbridge, which Falconbridge rejected. And, in June, Phelps Dodge trumped them all when it made an approximately US$40-billion friendly offer for Inco and Falconbridge in a two-part deal.

Jan 1, 2006

By George J. Allen, Laura A. Allen

Introduction This section of the text presents a general review of the different types of concentrate marketing contracts. Too often the marketing strategy is ignored in the design phase of the project and the producer is left to the mercy of the buyer. Many items such as concentrate grade, impurity levels and moisture content of the concentrate my enhance, or severely restrict the producers ability to make a profit it. Close attention should be paid to the design of the concentrator which can improve the quality of the concentrates, thus the ability to increase the rider of potential buyers can be enhanced. Difficult at best, is the position of the miner who only has one outlet available for its production. Obviously, the trade offs must be evaluated. For example, concentrate grade vs recovery and grind/filtering capacity vs moisture of the concentrate all must be weighted against freight cost to a potential buyer. In addition, the above considerations must be weighed against the capital cost to the miner. This chapter is intended to highlight important articles that are included in short and long term agreements and to give a new miner/producer some insight into hat my or my not add value to the product. Unless the miner sells the product directly to a consumer such as a gold, or silver producer, or to a large enough operation that has a totally intergrated system to make a finished product, most miners are forced to sell to buyers who ultimately will refine and market the product. Types of Contract Agreements There are many types of contract agreements just as there are colors in the rainbow, however, most contracts fall into three basic categories. (1) Smelter Schedules: Designed for the small producer, the odd lot of concentrate, smelter flux and precious metal ore. Albeit custom smelters are becoming fever by the day, because of pollution control requirements and financial difficulties, most remaining custom smelters have a smelter schedule. A smelter schedule is a posted list of charges and conditions that the smelter will buy material from a seller. Smelter schedules exist for copper, lead, zinc, silver and gold (Handbook for Small Mining Enterprises, Montana Bureau of Mines). (2) Short Term Custom Contracts: Large mine producers frequently use Short Term Contracts where the seller has the buyer frame a contract that is tailored to the sellers’ production. The short term contract my be as long as one year. A spot sale qualifes as a

Jan 1, 1986

By B. E. Zeigler

This bi-product from a nickel smelter has been manufactured over the last 30 years for the abrasive and roofing industries. This paper discusses a new development for this material a foundry aggregate used for molding sand in both ferrous and non ferrous casting industries. Test data, marketing strategies, manufacturing, and case studies will be presented from the first concept, to current production, marketing and the end use of this product.

Jan 1, 1999

By I. S. Parrish

Locating and defining an ore body with minerals or metals that can be recovered at a profit is the objective of minerals exploration. Direct exploration involves examining and sampling rocks either in outcrop, underground exposure, drill core, or cuttings. Indirect exploration infers the measurement of some physical, chemical, or biological factor that reflects the possible presence of the metal or mineral of interest, or a structure that may act to collect, concentrate, or otherwise favor the presence of the desired commodity. Included here are all forms of geophysical, geochemical, or geotech-nical prospecting. In recent years, indirect exploration has given rise to an impressive number of specialists and a variety of techniques. Less impressive is the success rate or productivity of the modern explorationist. Exploration Productivity Losing Ground Judging from the low number of mine openings or mine discoveries in recent years, the exploration industry is not as productive as it once was. Many will take umbrage at this judgment, but a review of the literature will support this statement. In Canada, from 1951 through 1960, there was an average of 5.6 discoveries a year. From 1961 through 1976 there were only four a year. This nearly 30% reduction occurred despite a massive increase in exploration funding. From 1950 to 1955, the Canadian mining industry spent $5 million (1975 dollars) for each minable deposit found. During the period 1970 to 1975, the cost was $25 million for each one found. The industry was spending five times as much and finding 30% less than a generation earlier. This is not indicative of a productive endeavor. The loss in productivity is even more apparent to explorationists who wander the western US, and are awed by the thoroughness and discovery rate of those early prospectors who explored from 1850-1920. The "old-timers" missed very little. They used pans and crude chemical tests in place of plasma or X-ray fluorescent assay techniques. But, they found ore bodies that led to mines. Today, the best prospecting areas are pockmarked by the hand dug pits, trenches, and shafts left by our predecessors. The success or productivity of the old-timers may be attributed to any or all of several factors. Granted, they were looking at virgin ground and at deposits that in many places were exposed. The factor most critical is, however, that they employed direct exploration methods. They walked over areas of interest, traversed swamps and mountains, and followed "colors" in stream gravels to their source. They also chipped rocks, dug pits, trenched along structures, and followed the "leads." Many of today&apos;s explorationists, on the other hand, adopt a more sophisticated approach. A geologic model is conjured up so the exploration team "knows" models, but the model should be applied at a later stage in the exploration effort. J. D. Ridge has written an excellent article on the role and timing of models. Geologists should collect and assemble data, facts, and observations and fit these into a model and not conceive a model and seek data to prove their vision. Further, many exploration managers are adept and talented at devising exploration programs. They can program and use modern exploration techniques and tools. They can apply these and their modeling capacity to assemble a glittering array of targets. It would appear that in all too many instances, creating targets has been equated with and is considered being productive. As noted, finding ore bodies is being productive in exploration. Creating targets may or may not lead to ore bodies. As an end result, locating targets is not productive exploration. How then does one foster productivity in exploration? Some suggestions are to increase the use of direct methods, follow the methods and philosophies of old-timers, look at more rocks, do more field work, use foot traverses, and do more drilling. It may be argued that this is what the old-timers have done and we would then be hoping to find

Jan 11, 1983

By T. Reed Scollon

Major interrelated factors to be considered in assessing the impact of air pollution control regulations on coal are: (I) the fuel and fuel-related limitations of such regulations; (2) the rate of adoption and areal scope of the regulations; and (3) the availability of fuels and fuel-burning equipment to meet the requirements. A growing number of regulations contain provisions limiting the emissions of sulfur oxides or the sulfur content of fuels or both. With few exceptions, these limitations have not yet become fully effective in those areas which have already adopted regulations, and pertinent details of future regulations or legislation for most other areas are unknown at this time. Sufficient information is not avail- able to determine the availability of low-sulfur fuels at various demand and price levels, and large-scale commercial feasibility of sulfur-oxides removal processes and equipment is believed to be some years away. Accordingly, with the many uncertainties and unknowns, it is possible at best to make only a rough assessment of the impact of such regulations or legislation on coal.

Jan 1, 1969

By Herschel H. Potter

While preparing this paper, I soon realized I had a problem in defining what injuries should be classified as "personal." Admittedly, in some cases, falls of persons, sprains and strains, pulling and pushing injuries, and back injuries may have been caused by the individual. But, I believe the number of injuries directly attributed to an individual&apos;s carelessness is relatively small in comparison to the total number of injuries in those categories. For discussion purposes, the injuries most often considered to be personal, that is, caused by individuals are those classified as back injuries. My paper will be devoted to back injuries because this category represents the greatest number of injuries occurring in coal mining. A man&apos;s best friends are his wife, his back, and his dog. The back, however, has a reputation of not being as faithful as his other two friends.1 "Industrial back injury is one of the major occupational health problems plaguing industry to- day. According to national surveys, back injury accounts for more lost time than any other occupational injury and costs companies thousands of dollars in compensation, medical fees and over- time pay."2 A study conducted by USA Today found that back ailments afflict an estimated 75 million Americans, have totally disabled about 2.5 million adults, lead to as many as 200,000 required surgeries each year, are a leading cause of absenteeism and disability, are the second leading cause of hospitalization, are responsible for 18 million doctor visits a year and cost about 93 million work-days annually. The cost to industry is estimated at $14 billion a year.3 During the past 30 years, a great deal of accident prevention education has been directed toward the reduction of back injuries. However, this effort has not produced any great change in the incidence of the injury. Back injuries should be of the utmost concern to everyone here today. I don&apos;t need to tell you what the incidence rate is for back injuries, nor will I use any statistics to inform you of the incidence rate for the coal mine industry or any specific mine. It is only important to know that the number of back injuries is excessive. Back in- juries resulting from lifting have been and continue to be one of the most constant and undiminishing problems in the occupational environment. The fact is, we use our backs to per- form work that the back was not designed to do. Historically, manual materials handling related accidents have consistently accounted for the largest percentage of all industrial accidents. In fact, over 25 percent of all industrial accidents are related to handling of materials.4 In underground coal mining operations, material handling accidents account for even larger percentage of lost time injuries. In 1983, for example, they accounted for 34 percent of all lost time injuries and 32.6 percent of all non-lost time injuries. 5 I want to use one example of a task that will illustrate what I have just said: the building of a concrete block stopping. Each solid concrete block will weigh from 60 to 70 pounds. To build a stop- ping 6 feet high and 20 feet wide will take approximately 80 blocks. On the average, these 80 blocks will be handled at least four times from loading into the conveyance for transportation to being placed while constructing the stopping. This generally requires repetitive lifting from ground level. The next three slides demonstrate the lifts

Jan 1, 1986

By James Sheridan

Risk can generally be defined as the possibility or chance of a loss corresponding to uncertainty. Analysis is the process for examining the components and relationships of a complex system in order to determine the impacts of its variables. Risk analysis is therefore a course of action taken to analyze multiple variables of a system that is subject to speculative outcome. When risk analysis is applied to mine development, it becomes the means for assessing and measuring those parameters that contribute to economic viability. Mining can be a risky business. It is composed of an assortment of factors that contribute to its financial outcome. Of these factors, the most consequential output is the net present value (NPV). Applying risk analysis in mine development can identify those factors having the most significant impacts and applying limits to those impacts. Mathematical computer modeling using Monte Carlo techniques is available and can be customized to suit specific mine development ventures. Essentially, those parameters that are not fixed values can have input variability. Rationally deduced engineering estimates should be the basis for determining the initial values applied as inputs in the models. Risk analysis therefore provides the user a means to identify, rationalize and assess the risks in mine development in an informed, calculated, and unbiased format for making economic decisions.

Jan 1, 2002

By Stone. Jon P.

INTRODUCTION Countries that are currently developing their mineral potential have unique information systems requirements to support these activities. The mining laws usually grant the State considerable authority over the process. In many instances, the mining laws give a government agency the responsibility for granting and controlling exploration permits and development concessions. This is the case in Costa Rica. The Direcion of Geologia, Minas, y Hidrocarburos (DGMH) of the Ministerio de Industria, Energia y Minas (MIEM) is responsible for the management and operation of the National Mining Register. This paper describes the results of two studies of the information system requirements to support the National Mining Registry as well as those supporting some of the other function of the DGMH. The first of the studies reviewed the situation before the installation of computer equipment. The second study evaluated the installed systems. BACKGROUND Historical Perspective Mining in Costa Rica is at present a relatively minor part of the economy. It consists primarily of industrial minerals and gold production. Gold production is largely by small-scale miners and may be more substantial than reported. There is considerable interest on the part of the Government in both having a better understanding of the existing mining industry and promoting future development. Mining law was first provided by the Ordinanza de Mineral (of 1830). This was replaced by the first Mining Code of 1953. Apparently, one of the first problems caused by the 1953 law was the granting of concessions which were not worked. A 1968 agreement with ALCOA also resulted in political conflict. The Government worked on a new Mining Code for many years and in 1982 the current Mining Code was enacted. Draft implementing regulations were prepared in April 1984. Mining Code of 1982 The Mining Code of 1982 addresses most aspects of mining in Costa Rica including the declaration that all mineral resources are to be the property of the State. The State may grant exploration permits and exploitation permits. The exploitation of hydrocarbons, radioactive minerals and certain water resources was reserved to the state. The DGMH was given authority to settle placer claim disputes, maintain a registry of exploration permits, and exploitation concessions. and generally supervise mining activity. Towards this, the Mining Code of 1982 includes rather detailed requirements for the processing of application for permits and concessions. Mining Code Application Requirements The following briefly describes the requirements to give the reader a feeling for the complexity of the process. Currently, over 1,000 active applications, exploration permits and exploitation concessions are being monitored under the process. The number remains relatively consistent in that the number of new applications is usually about the same as the applications that are put aside. The time and date of the filing must be certified by the DGMH. The application must include all the information specified in the Mining Code. If incomplete, DGMH must notify the applicant of the deficiencies or omissions and direct that the applicant correct the deficiencies or omissions within 8 business days (a single 30 business-day extension is allowable). If the applicant does not respond as directed, the application is deemed as not having been filed and the pertinent information is placed in the files. The DGMH must reject the application outright and direct it be placed in the files in the following cases: (a). If the new application covers the area of a previous permit or concession, either being processed or already granted.

Jan 1, 1987

By J. Simmons, P. Ziemkiewicz

Acid-Base Accounting (ABA) is an analytical procedure that provides values to help assess the acid-producing and acid-neutralizing potential of overburden rocks prior to coal mining and other large-scale excavations. This procedure was developed by West Virginia University scientists during the 1960s. After the passage of laws requiring an assessment of surface mining on water quality, ABA became a preferred method to predict post-mining water quality,and permitting decisions for surface mines are largely based on thevalues determined by ABA. In order to predict the post-mining water quality, the amount of acid-producing rock is compared to the amount of acid-neutralizing rock, and a prediction of the water quality at the site (whether acid or alkaline) is obtained. We gathered geologic and geographic data for 56 mined sites in West Virginia, which allowed us to estimate total overburden amounts, and values for maximum potential acidity (MPA), neutralization potential (NP), net neutralization potential (NNP), and NP/MPA ratios for each site based on ABA. These values were correlated to post-mining water quality from springs or seeps on the mined property. Overburden mass was determined by three methods, with the method used by Pennsylvania researchers showing the most accurate results to actual overburden mass. A poor relationship existed between MPA and post-mining water quality, NP was intermediate, and NNP and the NP/MPA ratio showed the best prediction accuracy. In this study, NNP and the NP/MPA ratio gave identical water quality prediction results. Therefore using NP/MPA ratios, values were separated into categories: <1 should produce acid drainage, between 1 and 2 can produce either acid or alkaline water conditions, and >2 should produce alkaline water. On our 56 surface mined sites, NP/MPA ratios varied from 0.1 to 31, and six sites (11%) did not fit the expected pattern using this category approach. Two of eight sites with ratios <1 did not produce acid drainage as predicted (the drainage was neutral), and four of 40 sites with a ratio >2 produced acid drainage when they should not have. These latter four sites were either mined very slowly, had non-representative ABA data, received water from an adjacent underground mine, or had a surface mining practice that degraded the water. In general, an NP/MPA ratio of <1 produced acid or neutral drainage sites, between 1 and 2 produced mostly alkaline drainage sites, while NP/MPA ratios of >2 produced alkaline drainage with a few exceptions. ABA is a good tool to assess overburden quality before surface mining and to predict post-mining drainage quality after mining. The interpretation from ABA values was correct in 50 out of 52 cases (96%), excluding the four anomalous sites, which had acid water for reasons other than overburden quality.

Jan 1, 2003

By Stephen E. Kesler

Carbonaceous sedimentary rocks are abundant in the upper part of the caldera or maar that hosts the Puebio Viejo Au-Ag district, and much of the Moore sulfide zone is in these rocks. These rocks are thinly layered and contain scattered plant remains and variable amounts of volcaniclastic debris and pyrite. The carbonaceous matter in the sediments yields no X-ray diffraction pattern and is not graphite. It has C/N ratios of 4 to 10, and &13C values of about -25 per mil, which indicate that it is dominantly of marine organic origin and partly degraded. Atomic S/C ratios in the unmineralized part of the carbonaceous rocks have a median of about 1.2, much higher than most similar unmineralized rocks, reflecting not only the abundance of pyrite in the sediments, but also the fact that the organic material contains several percent sulfur. Extracts from the organic material indicate that it is thermally mature and that it reacted with the hydrothermal solutions. Atomic S/C ratios in the mineralized carbonaceous rocks are generally higher than those in unmineralized carbonaceous rocks, ranging to values of 5 and more. These differences indicate that significant amounts of carbon were consumed by the reduction of sulfate and metal chloride complexes in the mineralizing fluids as they passed through the carbonaceous sediments. Direct reaction between organic material and ferrous chloride-bearing, acid-sulfate hydrothermal solutions probably caused continuous deposition of pyrite during this period. Intermittent deposition of gold from chloride complexes by the same reaction was probably facilitated by boiling or C02 effervescence.

Jan 1, 2013

By R. M. Guymon, D. D. Lauriski

Safety management can best be described as how each company deals with the control of hazards (human or mechanical) to reduce costly accidents and employee injury caused by accidents. Properly used, effective safety management can mean the difference between being a highly productive, cost-efficient operation or one that "walks the fence," that is less productive with higher product costs. At Utah Power & Light Co&apos;s mining division, effective safety management has been used as tool to achieve this difference and remains as the number one priority to maintaining that difference.

Jan 1, 1990

By W. C. Yates

Lack of visibility from large, open-pit haulage truck cabs has become a serious safety problem. Anaconda conducted a research program to develop a low cost system to alert haulage truck operators to small vehicles present in blind areas. Several systems were developed and tested. As open-pit haulage truck size has increased, so has the size of the blind areas. Mine utility vehicles, pickup trucks, and cars are concealed within these blind areas and become safety hazards. Figure 1 shows the typical blind areas of a 136 t (150-ton) haulage truck. The areas of greatest concern are at the rear center and front right corner of the truck. In these "no visibility" areas many small vehicles have been crushed by large haulage trucks at various mine sites. In most instances, the occupants escaped the vehicle before it was destroyed. But injuries and death have occurred. In most cases, the accidents were attributed to negligence or carelessness by the small vehicle driver. The limited visibility problem still exists, though, and a solution is needed. Initial Solution The usual plane mirror on the driver&apos;s side and the convex mirror on the right front of the haulage truck allow only limited rear visibility. The typical, right side convex mirror is generally small and difficult to locate at a glance. This convex mirror also presents an image that distorts distance perception. These mirrors are of¬ten broken and immediate replacement not demanded or made. The US Bureau of Mines, in a contract with M.B. Associates, San Ramon, CA, developed an improved visibility system. It consisted of a larger, left view mirror and unique, blind area viewer. The large 230 x 690 mm (9 x 27 in.) left mirror has a small convex spot mirror near the bottom. The entire unit can be quickly replaced if broken. The large size provides a full view of driver orientation features such as the rear tire and the top of the load bed. The right 300 x 410 mm (12 x 16 in.) mirror has a convex surface and is quite rugged. The 510 mm (20 in.) spherical radius presents the operator with some distance distortion, but objects in its view are easily seen. The "blind area viewer" consists of a modified fresnel lens that allows the driver to "look around the corner." Installation of three of these lenses on the front of each haulage truck is rec¬ommended for adequate blind area coverage. This system significantly increases an operator&apos;s field of view and allows viewing of objects within about 3 m (9.8 ft of the truck. Many open-pit mines are nor mounting on smaller vehicles a long whip with a flag and lamp or both. This increases vehicle visibility to haulage truck operators. The whip is permanently attached to the mine vehicle. It can also be magnetically attached to transient vehicles. The whip system. though, is inadequate for visibility in the critical rear and right front blind areas. Alternate Solutions All of these visibility aids as¬sume an attentive driver. In addi¬tion, areas such as the rear blinc, area are not covered. Based on the inadequacy of existing visibility systems, Anaconda made a com mitment to further the truck de¬tection technology. The best ap¬proach was considered to be ar active system. It would notify the haulage truck operator that an en¬croaching vehicle is present. Sev¬eral systems were considered, in¬cluding ultrasonics and elec¬tromagnetics. For the ultrasonic system, com mercial and in-house design were looked at. Designing an( building transducers with the spe cific beam shape to match the haulage truck blind spots re¬quired a major technological breakthrough. False alarms ap¬peared difficult to prevent en¬tirely. They were caused by pass¬ing, trailing, or leading vehicles a., well as nonthreatening objects. As a result of these problems, the ul¬trasonic technique was not pur sued. An alternative, an electro

Jan 7, 1982

By C. T. Wallace

Evans Industries, Inc., a management coal consultant and company was assigned to evaluate National Steel Company&apos;s coal properties in Knott and Floyd Counties, Kentucky. The results of evaluation showed large reserves of good quality, high volatile metallurgical coal contained in the Elkhorn coal beds and resulted in the formation of Beaver Creek Consolidated Coal Company. Based on results of the exploration and feasibility work, the decision was to install a coal nine, preparation plant and related facilities having a production capacity of one&apos; and three quarter million tons per year with Evans Industries acting as Beaver Creek&apos;s management company. The recoverable tonnage assigned to the Stinson Mine is approximately forty-five million tons. This paper discusses the general arrangement of storage, conveying, loading, refuse disposal facilities and the flow sheet of the preparation plant developed by engineers of Heyl & Patterson, Inc., and Evans Industries, Inc., with emphasis on practical flexibility, sulfur reduction in all circuits, and high product yield with the minimum amount of selective mining, Three and one-half miles of railroad have been built by the Chesepeake & Ohio Railroad to service this mine.

Jan 1, 1970

By A. K. Majumder

Particle motion in fluids is a subject of considerable practical importance to engineers working in fields such as hydraulics, river mechanics, chemical engineering and mineral processing. Many mathematical models have been proposed to predict the terminal settling velocities of particles in a fluid medium. The selection of an appropriate mathematical model has, therefore, become a challenging task for practicing engineers. This paper reports on an attempt to identify some of the useful models found in the literature for predicting particle-settling velocities in a fluid under free- and hindered-settling conditions. From this study, it was concluded that there is no well-accepted model validated by experimental data available for predicting particle hindered-settling velocities in a suspension of polydisperse and polydens particles. Collective efforts should, therefore, be made towards developing a hindered-settling model, as this is an absolute prerequisite for many model structures in mineral processing and other engineering disciplines.

Jan 1, 2007