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By R. H. Snow

Although industrial size reduction methods have an energy efficiency of only about 1 percent, methods of size reduction have not changed much for many years. One reason for slow progress has been the oversimple viewpoint that a single law should exist to relate size reduction to energy input. Modern simulation methods decompose the grinding process into a grinding rate function (selection function) and a breakage function. The breakage function is difficult to measure, and it usually requires tracers if it is determined from milling experiments. Prediction of breakage functions from basic principles is one objective of this paper. In this study we focus attention not on the gross energy input to the experiment, but on the spatial distribution of stress energy within the particle. We are led to this viewpoint by experimental observations of a few previous investigators (Bergstrom2, Rumpf3, Axelson4) and our own observations. Oka and Hiramatsu recently used their calculations of stress within particles for prediction of breakage, but again they tried to correlate the size of the fragments with the total stress energy, rather than the approach we propose. We assume that the stress energy is stored in the interior of the particle as the load is increased, until the particle breaks. We assume that each element of the particle breaks into fragments of a mean size that depends on the locally-stored stress energy. The size distribution of fragments is the computed from maps of the stress-

Jan 1, 1972

By N. Edmonson

Introduction An examination of statistics for the world phosphate fertilizer industry since 1980 reveals that there is an increasing tendency for fertilizer-manufacturing activity to concentrate in the areas of phosphate-rock mining. The economic justification for this resource-oriented strategy is clear. The choice between shipping phosphate rock, a comparatively low-value product, and shipping a more valuable finished fertilizer product will always, as long as cost considerations control the decision, be resolved in favor of the latter. The historical existence of substantial phosphate fertilizer-manufacturing capacity, which is oriented toward fertilizer-consuming activities and dependent on imported phosphate rock, shows that narrow cost considerations have not always determined the industry's location. One is entitled to ask what conditions have changed to precipitate the observed relocations, and how permanent are these changes. These questions are the subject of this investigation. Recent trends in world phosphate trade Since 1980, the changing pattern of world trade in phosphate materials reflects an increased interest in manufacturing phosphate fertilizer in rock-producing areas. This is shown by the decline in the total tonnage of phosphate rock being traded worldwide compared to world consumption of phosphate fertilizers (Fig. 1). This relative decline has continued since 1984, which is a longer period of time than could be explained by temporary cyclical market factors. Other evidence corroborates this conclusion. The world's phosphate-rock production is relatively concentrated geographically. In 1992, the top ten producing countries accounted for 92% of world production. Figure 2 shows that the share of world fertilizer production in the top ten rock producers has increased. Yet, further evidence of the direction of trade changes can be had by looking at the pattern of the world's sulfur trade. The first step in the manufacture of any of the widely used phosphate fertilizer products is the acidulation of phosphate rock with sulfuric acid. In most instances, phosphate fertilizer producers have found it economical to produce their own sulfuric acid by burning elemental sulfur, and such operations account for over 60% of all sulfur consumption in the world. 1 Therefore, a concentration of phosphate fertilizer production in rock-producing countries should produce a similar concentration of sulfur imports in the same countries. Figure 3 suggests that there has been a tendency since 1989 for sulfur exports to go increasingly to the rockproducing countries. World phosphate-location strategy is not limited to the alternatives of shipping rock and shipping finished fertilizers. A third alternative consists of producing phosphoric acid, the principal phosphate fertilizer intermediate, at the rock deposit, and then exporting it to market-oriented ammonium phosphate plants. This arrangement offers the importing country the advantages of shipping a more concentrated product while retaining the economic multiplier benefits of a domestic high-analysis fertilizer industry. India, and several other countries, imports merchant-grade phosphoric acid to use as input for the domestic value-added fertilizer industries. For various reasons, the trade in phosphoric acid has never quite lived up to the promise suggested by the foregoing discussion. Figure 4 shows no growth in this trade in the last ten years, either in absolute terms or in relation to the world's consumption of phosphoric acid. Most of the decline in the trade in phosphorous in rock form has been replaced with trade in finished fertilizers. The trade in superphosphoric acid was a growth activity in the late 1970s with the growth in US exports to the USSR, and this trade survived the Carter-era embargoes of US-Soviet trade. However, no additional sizable markets for superphosphoric acid developed, and other suppliers sought out the Soviet market. The problem with superphosphoric acid is that the cost of its incremental concentration is as great as the savings from shipping the more concentrated product. The Soviet market was a special case. The political breakup of the Soviet Union disrupted the superphosphoric acid trade after 1991 and led to a shutdown of the US export capacity.

Jan 1, 1996

By Cliff G. Paton, Sheldon B. Bland, Roger E. Melley

This paper looks at four critical lubricants used in the conveyor systems of the northern Albertan oil sand facility. The requirements for the lubricants used in the electric motors and gear boxes of the drive systems, the pulley bearing and the idler bearings are discussed in terms of the applications and the environment. A number of developments that have occurred in recent years are presented. Data from the field and from custom designed testing in the laboratory are used to support the role of simulation testing in problem solving in this area of technology.

Jan 1, 1996

By Virgil L. Barr

National income originating compared to physical production for an enterprise or an industry reflects its ability to strengthen the national economy. For a single industrial sector or for an industry this comparison can be useful to reflect changes that may occur in this ability to contribute because of changing supply-demand-income-investment equilibria. A favorable relationship can be postulated by specified economic incentive, and the accompanying technologic input required can be shown. The new index proposes the use of the Federal Reserve Board indexes of production divided by the constant dollar income originating in the petroleum industry which reflects increases or decreases in performance. When compared with other mineral industries and with, total industry, an approximation of relative strength is evident. By constructing three different hypothetical conditions for future petroleum imports, assuming a constant excess capacity requirement for domestic production, and providing an estimate for future domestic demand for petroleum, the impact on the performance index can be shown. Thus, a strong position for the petroleum and natural gas industry can be stated. If this is done, it becomes evident that because of restrictions on cost-price relationships, a drilling program that would provide enough domestic oil to meet demand may not be practicable. By difference, the amount of improvement in methods of production and processing through technologic advancements can be stated explicitly.

Jan 1, 1960

By M. E. Breitrick

Newmont Gold operates the Carlin East underground, one of four underground gold mines the company operates in northeastern Nevada. Carlin East began full production in early 1995. The mine's current rate is 900 t/d (1,000 stpd), producing about 4.6 t/a (150,000 oz/year). About 125 hourly and salaried personnel are employed at the project for its estimated six-year mine life. Two mining methods are currently used at the Carlin East Mine. Longhole stoping with cemented backfill accounts for 70% of the total mine production. Conventional underhand drift and cemented fill accounts for the balance of the daily tonnage. In December 1996. Newmont purchased an AC-Eickhoff ET-210 roadheader. The machine went into service in mid-June 1997. It is used in longhole Stope topcut development and cut-and-fill production at a rate of 225 t/d (250 stpd)

Jan 1, 1998

By Donald R. Simon

Money... not many subjects are as personal or as emotional. Hessiod said it well in 700 B.C. "Money is life to us wretched mortals". Are you getting paid enough? Does your company reward its top people? Does coal or copper pay more? Production or engineering? How is the synfuels industry going to influence mining salaries? Do high salaries attract and retain the best people? Do modern compensation systems ensure fairness or destroy entrepreneurial spirit? With our tax system and high standard of living why are we so salary conscious? Salary is not only important for what it can purchase but it is also a yardstick, measuring how well we are doing. We all need money to pay the bills and maintain our standard-of-living, but once we reach a certain point the psychological ramifications become more important than the purely practical side. Even necessary payments like the mortgage and the car are a function of our egos. Are our choices of cars and homes based on simple transportation and shelter?

Jan 1, 1980

By Edward Thomas

Yucca Mountain Overview The U.S. Department of Energy?s Yucca Mountain Project is a geologic repository project designed to receive, handle, package, transport, and emplace spent nuclear fuel and high level radioactive waste. The planned repository would be located in Yucca Mountain on the western edge of the Nevada Test Site, about 90 miles northwest of Las Vegas, Nevada, and would include both surface and subsurface areas. Yucca Mountain rock formations consist of successive layers of volcanic rocks (called tuffs) approximately 14 to 11.5 million years old, formed by eruptions of volcanic calderas to the north. With the volcanic rock the potential for methane emission is not an issue and the subsurface repository is a non-gassy (methane) classification. This paper will provide a summary of the development ventilation system design that provides fresh air for subsurface construction activities, and the emplacement ventilation system design that removes heat generated by the waste packages. The subsurface layout, illustrated in Figure 1, contains 108 emplacement drifts, one Performance Confirmation(PC) observation drift, nine intake/exhaust shafts, and three access ramps. The existing Yucca Mountain facilities, shown in bold lines in Figure 1, include a 7.8 km long, 7.62 m (25 ft) diameter U shaped tunnel that is formed by the North and South Ramps at both ends of the Exploratory Studies Facility (ESF) drift and a 1.5 km long, 5.0 m (16.4 ft) diameter Enhanced Characterization of the Repository Block drift (ECRB) that were constructed from 1994 through 1998. These drifts were used for site characterization activities and have been incorporated into the subsurface repository configuration. The unexcavated perimeter access main and exhaust main drifts are typically 7.62 m (25 ft) diameter TBM excavations and the emplacement drifts are 5.5 m (18 ft) diameter TBM excavations. The turnouts leading into the emplacement drifts are to be excavated by either mechanical, or drill and blast methods and serve as the launch chambers for the emplacement drift TBM excavations.

By L. Eros, R. H. King

The US Bureau of Mines has funded several research and development projects in computerized mine monitoring and control. Hardware and software components have been sufficiently developed so that mine operators have been provided with an efficient means to comply with federal regulations and increase mine safety. Several cost benefits have been realized as well, particularly with increased conveyor belt haulage availability. Western Fuels-Utah Inc. approached the Bureau to assist in planning, installing, and evaluating a computerized mine monitoring and control system because of the agency's research experience in this area. The installation was planned for Western Fuel's Deserado mine, located in Rangely, CO. Since a large, complex, underground mine producing about 2.4 Mt/a (2.7 million stpy) of coal was projected, the company anticipated significant benefits in safety and efficiency through a computerized monitoring and control system. A major part of the cooperative program was to document and evaluate the system design, installation, and operation. This will assist others to adequately design, specify, install, and operate future systems. Mine description The Deserado mine plan and layout have important impacts on the monitoring system requirements. Long range plans are to produce 2.4 Mt (2.7 million st) of clean coal annually from two longwall sections and four continuous sections. Presently, two continuous miner sections operate under 213 m (700 ft) of overburden in the 2.3 to 2.5 m (7.5 to 8.5 ft) thick D seam to develop main, submain, and panel entries have developed for a longwall. These began operation in December 1986. Belt conveyors haul the coal from the mining sections to a 1.4-m (54-in.) belt located in the upper compartment of the slope. The lower compartment contains a hoist for men and material transport. From the slope, the coal moves to two 9 kt (10,000 st) raw coal storage silos, then to a 680-t/h (750-stph) preparation plant. After cleaning, a 5.5-km (3.5-mile) overland conveyor carries the coal to a clean coal slot storage and rail load-out facility. An electric locomotive then transports the coal to the Bonanza Power Plant in Utah. Allen-Bradley monitoring and control hardware and software controls the preparation plant, with two PLC-3 programmable controllers and a Process Control Industries D-1200 color graphics interface. The system operator uses three "smart" color video display units and an alarm printer for hard copy records. Originally, it also monitored and controlled the conveyors from the bottom of the slope to the top of the raw coal silos, the preparation plant, the overland conveyors, the main mine ventilation fan, and the hoist. Some of these features, though, were later transferred to the mine system.

Jan 2, 1988

By Robert L. Grayson

In small coal mining operations, little is done in controlling supply and material inventories and optimizing total inventory costs. Material Requirements Planning (MRP) is an efficient material control system which time-phases net material requirements based upon production plans, bills of material data, and inventory status records. Inventory levels and total inventory costs are optimized using a lot sizing technique in placing time-phased purchase orders. The MRP system has been applied in large manufacturing firms utilizing mainframe computers, but it can be adapted to micro-computers for inventory control. This paper presents an application designed to assist the coal mine manager in optimizing inventory costs.

Jan 1, 1985

By P. Roghanchi

The Rock Mass Rating (RMR) system is an internationally recognized classification system that can be used for preliminary ground control design. The RMR system assigns quantifiable values to predefined classified parameters of a rock mass. Assigning a single value rather than a range to each parameter is a source of uncertainty, however, assigning a single value can be useful for further studies related to RMR ratings. Fuzzy systems are being used in an increasing number of application areas where linguistic rules are used to describe the system. In past decades, fuzzy systems have been successfully used in geotechnical and mining engineering problems to cope with uncertain data as well as with vagueness. In such scenarios, linguistic rules and rating-based classification of rock masses have always been questionable. The objective of this study is to apply fuzzy set theory to the RMR classification system. The fuzzy system proposed in this study is specified for weak and very weak rock masses (RMR<50) based on data collected from Nevada gold mines where 68% of RMR data is in the ?poor? and ?very poor? classes. In this approach, a Mamdani fuzzy algorithm has been constructed to evaluate basic RMR89 rating for the ?wet condition.? Comparison between basic RMR89 and fuzzy RMR shows the fuzzy RMR system is valid to predict RMR from the discrete rating of each input parameter.

Feb 27, 2013

By A. M. Whiting

Competition for coal producers and their primary customers has constantly increased during recent years. The effects of the Clean Air Act Amendments of 1990 on the electric utility industry, coupled with the normal complexities of coal production, quality control, transportation and contracting techniques have spurred both buyers and sellers to increase their level of sophistication. This paper will review the basic aspects of the U.S. coal business and explore the commercial approaches which have proven to be most successful.

Jan 1, 1994

By J. Gentry

Chemical grouting has been successfully used for over forty years to control the movement of groundwater in a wide variety of applications including tunnels, subway systems, sanitary sewers, mines and construction projects. This paper illustrates the versatility of chemical grouts by reviewing three projects where chemical grout was utilized to address some very difficult water control challenges. The featured product is acrylamide which can be used alone or in conjunction with other types of grout such as cementitious products. Acrylamide grout is injected as a two component product that will react and form an impermeable gel when the components combine. There are notable differences between the acrylamide based products and cementitious products. The most notable and significant difference is that acrylamide is a true solution grout that contains no particulates and has a viscosity of 1-2cps. This feature enables the acrylamide grout to penetrate very small geological features that other grouts could not penetrate and to seal small cracks and fissures where groundwater seepage is occurring. The product also has an adjustable gel set time from a few seconds to several hours which enables the operator to determine the product travel before it forms a gel. When properly applied the product has a half-life in the soil of 362 years (per testing by the US Department of Energy).

Feb 27, 2013

By D. G. Kotlyar

Oxidized sulfide minerals, commonly formed by weathering, increasingly are becoming important resources as primary sulfide deposits are depleted. Oxidation, in general, reduces selectivity and recovery in flotation. The objective of this research was to determine the mechanisms of oxidation and collector adsorption in sulfide systems as a step towards developing improved technologies for beneficiation of oxidized sulfides. Data from microcell flotation tests are combined with electrochemical and spectrophotometric measurements. The adsorption of ethyl xanthate (EX) on oxidized sulfides was characterized using AC impedance techniques and correlated to flotation response. The floatability of chalcocite, chalcopyrite and pyrite was dependent on the extent of oxidation. Oxidation for 1?) d at 65? C inhibited flotation of chalcocite, and chalcopyrite even after the addition of a large amount (1 x 10&apos;) M) of collector. Heavily oxidized (27 d) chalcocite remained unfloatable. However, longer oxidation of pyrite and chalcopyrite restored the floatability. Oxidation resulted in an electrically resistive, nonporous surface layer.

Jan 1, 1993

By William F. Eichfeld, Robert J. Wenzel

INTRODUCTION The phrase "subsidence control planning" can refer to the use of specific mining methods and-specialized techniques to control subsidence events or it can refer to planning for subsidence by predicting its magnitude and timing and further planning mitigation strategies. In the first case the objective is actually subsidence prevention while in the second it is a design procedure that seeks to maximize the use of both surface and subsurface resources. Neither technology is well developed at this point. The purpose of this presentation is to briefly outline the Department of Energy&apos;s Subsidence Program. This program is, in general, bases on the premise that subsidence control technology, by any definition, can be accomplished only through a thorough and rigorous understanding of subsidence phenomena. This understanding must come from many well planned and executed studies of stress redistribution and strata deformation as they occur during mining activities. There is presently considerable incentive to improve our subsidence engineering capabilities due to the desire for increased coal utilization with acceptable environmental impact. Considerable research in this area is being sponsored by federal and state governmental agencies, universities, and the coal industry. Federal sponsorship has been borne by the Department of Energy, the Bureau of Mines, the Office of Surface Mining and the U.S. Geological Survey for the most part. These agencies have carried out basic research in their laboratories and have contracted with other organizations for additional work. At this time most of the available resources are directed toward contract research, especially in DOE. It is the DOE research plan which will be addressed here.

Jan 1, 1982

By Z. Kokesz

The following paper presents the results of geostatistical studies of the selected hard-coal deposits in Poland. Geostatistical methods were applied mainly to the characterization of variability structure of the coal seams thicknesses as well as sulphur and ash contents in the coals. Results imply that the accuracy of coal reserves estimations can be improved if kriging method is applied. Kriging allows predicting more precisely the values of such parameters as thickness and sulphuring content.

Jan 1, 1993

By Brett P. Spigarelli

"To meet the growing need for CO2 capture and storage technology, Michigan Technological University is studying CO2 capture using alkali-based solvents. The objective of the present study was to find a way to increase the absorption rate of CO2 into an alkali solution without reducing the absorption capacity of the solution. One approach to increasing absorption rate is to use a surfactant to chemically alter the gas bubble size. The surfactant chosen for the study was a neutral-charge polypropylene glycol methyl ether (PPGME) with a molecular weight of 200. Experiments were conducted to study the absorption rate of CO2 at varying surfactant concentrations. Results showed that as the concentration of PPGME increased in solution, the absorption rate also increased. The CO2 absorption rate increased from 3.45 x 10-3 mol/min CO2 at 0g/L PPGME to 3.92 x 10-3 mol/min CO2 at 0.48 g/L PPGME. This amounted to a 14% increase in the CO2 absorption rate with no decrease in the absorption capacity of the solution. IntroductionChemical absorption using an amine solvent is currently the most mature carbon capture and storage technology available. Amines are advantageous in that they have a fast CO2 absorption rate, which leads to a high CO2 removal efficiency. However, amine absorption has some considerable drawbacks, such as high energy requirements, high equipment corrosion rates, amine degradation in the presence of oxygen, high waste generation and a large increase in plant footprint if new equipment is constructed (Herzog and Golomb, 2004; D’Alessandro et al., 2010). Due to these drawbacks, Michigan Technological University (MTU) is studying CO2 absorption using alkali-based solvents, which address the above disadvantages of amine solvents."

Jan 1, 2015

By John A. Shuster

Case histories are reported for several soft ground shafts ranging from 6&apos; to 40&apos; in diameter and 50&apos; to 230&apos; in overburden depth for which ground freezing was employed to provide temporary ground support and groundwater control during shaft sinking through the overburden. Cases reported emphasize dealing with difficult site and ground conditions such as working within existing buildings, through very soft, running and bouldery soils, in the presence of substantial lateral groundwater flows, and into salt dome deposits requiring special considerations. Construction procedures, schedule, and relative costs are discussed for each case.

Jan 1, 1985

By F. Calizaya

This paper explains and discusses a computer program developed to determine the ventilation design parameters for complex auxiliary ventilation systems such as those found in the construction of long excavations with multiple headings. The program is based on the principle of partitioning the system into segments of finite length, and formulating and solving the resulting networks recursively. The application of the program is illustrated by the detailed solution of an auxiliary ventilation system proposed for the Exploratory Studies Facility (ESF) at the Yucca Mountain project, Nevada.

Jan 1, 1994

By F. D. Huntley

Raw materials used by the Flat Glass Industry are known in the Industrial Minerals geology sector as Specialty Products. These pro- ducts must meet specification limits usually not the same for all glass manufacturers. Evolving new glass compositions will require mineral concentrates of consistent purity being produced within economic limits that will assure market viability of the resulting glass product. The amount of success the Flat Glass Industry will achieve by developing and maintaining domestic production centers will be determined by many economic factors which affect the costs of doing business. Technological developments by mineral processors must continue in order to achieve more efficient production of high quality glassmaking raw materials.

Jan 1, 1986

By Pasi Latva-Pukkila

Underground rock drilling has gone through intense development during the last 25 years. Mechanization and hydraulics have greatly increased the efficiency of drilling and improved the environment of the drill operator. As the total economy has become more and more important, the development has resulted in greater overall economy in drilling. The latest evolution step is computerization of drilling equipment. Computerization has been applied to tunnelling jumbos, long- hole drilling rigs and bolting rigs. With today&apos;s technology computerization is the natural way to increase capacity and productivity of the drilling process. However, it is still impractical to implement total "robotic" drilling. In computerized drilling the operator&apos;s role continues to be vital in controlling the drilling process and in analyzing the effect of individual parameters on the whole excavation process. Today this is called "CAD" - Computer Aided Drilling.

Jan 1, 1989