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By P. L. Padgett, J. C. Hower

Five coals blended at a Midwestern United States power station were subjected to detailed analysis of their Hardgrove grindability. The coals, representing four distinct coal beds, are a low-sulfur, high-volatile A bituminous Upper Elkhorn No. 3 coal (Pike County, Kentucky); a medium-sulfur, high-volatile A bituminous Pittsburgh coal (southwestern Pennsylvania); a low-sulfur, subbituminous coal from the northern Powder River Basin (Montana); and two low-sulfur, subbituminous Wyodak coals from two different mines located in the eastern Powder River Basin (Campbell County, Wyoming). All samples that were processed in the Hardgrove grindability tests were also analyzed for their maceral and microlithotype content. The high-vitrinite Pittsburgh coal and the relatively petrographically complex Upper Elkhorn No. 3 coal exhibited different grindability behavior. The petrographic compositions of the Pittsburgh raw feed, the 16 x 30-mesh fraction (HG! test fraction) and the -30-mesh fraction (HGI test reject) are similar, suggesting that the HGI test fraction typifies the whole feed. The eastern Kentucky test sample is not as representative of the whole feed, with the HGI test fraction having lower vitrinite amounts than the rejected -30-mesh fraction. The Powder River Basin coals are high in vitrinite content and show behavior similar to the Pittsburgh coal.

Jan 1, 1998

By J. Alvarez, S. H. Castro

The feasibility of chalcopyrite-pyrite separation in the flotation of a chalcopyritic copper ore, at reduced surface tensions regulated by methanol, was investigated. It was found that with methanol dosages from 0.5% to 1.5% v/ v, the chalcopyrite might be effectively separated from the pyrite, without use of other flotation reagents and pH regulators. However, under this simple condition, the chalcopyrite recovery was only around 50%, recommending the use of other reagents to reinforce the collector action. Low dosages of different collectors were tested, including SF-323 (Shell Float), S-6588 and S-7251 (Cytec), and S-701 (Molycop). Very promising results were obtained with low dosages of the collector S-701 and 1% v/v of methanol in the pulp, which evaluated against a reference test, gave similar copper recovery, higher Mo recovery and higher depression of pyrite. Consequently, this is an alternative process which does not require the use of lime to depress pyrite.

Jan 1, 1995

By Frank W. Reinrniller

Mill ball charging systems have undergone little change during the past two decades. Most operations utilize a locomotive/ball car combination to load and haul charges from the ball storage bin to the mill charging boxes or, alternatively, transport charges to the charging boxes by means of a ball bucket handled by bridge crane. This paper describes a new concept in ball handling systems that is in operation at the Island Copper Concentrator of Utah Mines, Ltd. at Port Hardy, B.C. This system employs a narrow belt conveyor to convey a weighed charge to each of nine belt unloading stations at the mills. In operation, the system has proved to be practicable, trouble-free and economical of operating labor.

Jan 1, 1977

By K. A. Natarajan, M. K. Yelloji Rao

The effect of galvanic interactions among sulfide minerals such as chalcopyrite, galena, and sphalerite in the presence and absence of a grinding ball material on the flotation recovery of chalcopyrite has been studied. X-ray photoelectron spectroscopy (ESCA) studies were carried out to identify the reaction products on the sulfide minerals after different apes of galvanic interactions. Galvanic contact with active minerals such as galena and sphalerite, either alone or together, significantly affected the floatability of chalcopyrite mineral, such an effect being more severely felt in the additional presence of a grinding medium as well as oxygen. Surface analysis studies revealed the presence of oxyhydroxide species of iron on all the sulfide mineral samples which were in prior contact with the grinding medium. The formation of such oxyhydroxide species of iron was found to be dependant on the relative electrochemical activity of the mineral. Probable electrochemical reaction mechanisms are discussed.

Jan 1, 1990

By R. J. Beckman

This paper traces the history of mica mining in Alabama from 1870-1970. The decline of sheet mica production is noted and emphasis is placed on the more recent activity of scrap mica production and the development of the U. S. Gypsum Co. mica properties in Randolph County, Prospecting for weathered pegmatites of sufficient size to warrant development is a continuing challenge since most deposits are too small and all exhibit varying characteristics as to size, shape, and weathering. Quantity and quality of muscovite mica in the pegmatites is of utmost importance and its recovery during processing of the ore is described.

Jan 1, 1970

By O. A. Bascur

An expert process operation advisor system can increase plant efficiency, even in a complex, natural environment where not all elements of the production process can be measured directly. This system, develaped and tested in a Frasch process sulphur mine, monitors key process variables with extended qualitative pattern processing and provides on-line advise to the operators of sulphur production wells. An expert system framework captured common sense rules generated from years of experience obtained in the operation of a sulphur well monitoring system. The existent operating procedures were enhanced by process analysis using a qualitative modeling approach which provided extended rules for on-line classification of a well operational status and an expert alarm system. The methodology for development and implementation of the process advisor is presented in this report. Qualitative process modeling, statistical process control and heuristics were incorpomted into the process advisor resulting in a more efficient use of heat, an extended well operational life and the resulting cost savings. The computer process advisor also allowed the operator to concentrate his attention on the weak wells or wells in trouble. A process management system improved plant operation by automatically storing well data into a commercial database for operator validation. The enhanced relational data base system provided valuable and timely information for planning and decision making. The synergistic combination of on-line process analysis tools, expert control systems and database technology is shown to facilitate the flow of materials, energy and infomation in a modern plant.

Jan 1, 1990

By Philip L. Hageman, Paul H. Briggs

An important tool for use in the geochemical assessment of abandoned mine-waste piles is a leach procedure that can easily be done in the field and used for on-site screening of historic mine-waste material. We have developed a simple field leach test that is an effective indicator of waste pile geochemistry and can be used in order to establish the relative geochemical fingerprint for a given pile. This simple procedure also provides indication of the potential chemical composition of run-off from the weathered surface of these piles. As part of developing the technique, a comparative study was carried out on eight mine-waste composite samples from different deposit types. Splits of all eight composites were leached using the field leach test procedure and a modified version of EPA Method 1312 (SPLP). We found that the field leach test consistently provides relative indication of leachate geochemical trends comparable to leachate data derived from the more regulated, time consuming and laborious EPA Method 13 12 (SPLP).

Jan 1, 2000

By J. Mastoris

The determination of the surface area that may be impacted by underground mining is an important consideration in subsidence engineering. A number of parameters have been utilized to identify this influence area, most notably the angles of draw and break. This paper discusses the implications of selecting an appropriate "damage angle" for defining a potential damage area due to mining, within which surface structures may be impacted. Furthermore, the influence of both mining and geological factors (i.e., mining width, depth and overburden lithology) on this angle is examined using the Surface Deformation Prediction System (SDPS) software. Finally, recommendations are given for applying these concepts in subsidence control.

Jan 1, 1995

By E. B. Kroeger, Y. P. Chugh

The goal of this project is to develop, demonstrate, and document the beneficial use applications of a ponded F-fly ash as a road subbase material for the 2.1-mile Meredosia Industry Access Truck Route in Meredosia, Illinois. Approximately 60,000 to 70,000 cubic yards of ponded fly ash are proposed for use on this project without negative environmental impacts to surface water or groundwater. The County Highway Truck Route will consist of a 24-foot wide road built on a 0 to 7-foot thick compacted F-fly ash subbase. Laboratory testing indicates this fly ash will serve adequately as a road subbase, conforming to IDOT standard specifications. The economic considerations of using the Meredosia F-fly ash will also be developed so that a detailed cost-benefit analysis can be prepared for this project and for future projects. This project represents a two-year cooperative development and demonstration effort among the Office of Coal Development and Marketing (OCDM) of the Illinois Department of Commerce and Community Affairs (IDCCA), Southern Illinois University (SIU), Morgan County Highway Department (MCHD), Illinois Department of Transportation (IDOT), AmerenCIPS, and the Morgan County Regional Planning Commission. It is anticipated that monitoring activities will continue for a period of three (3) years after the completion of this project. The MCHD and IDOT will oversee all construction activities and long-term performance evaluation studies. Successful demonstration of large-volume beneficial use applications of F-fly ash at this site will significantly reduce management costs for power plants burning Illinois Coal. Furthermore, it will encourage similar utilization strategies at other sites in the State of Illinois.

Jan 1, 2002

By Wu Chao, Wang Pinglong, Meng Tingrang

This paper discusses the research results of sulphide ore properties with respects on self-heating and the assessment techniques on mine spontaneous combustion for several mines of sulphide ores in China. A group of experimental devices for testing the chemical behaviour of sulphide minerals, the geological structures, the rate of oxygen absorption, the initial self-heating temperature, and the ignition point of ore samples, etc. are also described in detail. These methods have been proved to be effective by several sulphide mines which all have the history of spontaneous combustion of sulphide ores. INTRODUCTION A fire disaster from the spontaneous combustion of sulphide ores in a mine can produce large quantities of toxic gases and heat to pollute the working environment, lead to large economic losses and loss of human life, and even compell the mine to be closed. Some mines of copper, lead, zinc, tin and iron in China are of high content of sulphur. It is of great importance to evaluate the potential of spontaneous combustion of sulphide ores before beginning to design and mine the ore deposits. At present, the mechanism of spontaneous combustion accepted commonly is that sulphide ores undergo slow oxidation on exposure to moisture air at ambient temperature, with the evolution of heat, gases and moisture. The heat generated, if not dissipated, gives rise to an increase in the temperature of the sulphide ores. As the temperature of the sulphide ores rises, the rate of oxidation increases. If this is allowed to proceed unchecked it can eventually result in the ignition of the sulphide ores. For pyrite (FeS2), it reacts with oxygen and water according to the following equations.

Jan 1, 1993

By Peter McKenna

A mineral rights holding can ultimately only be turned to account by the profitable mining of ore on that property. The evaluation of South African gold mineral rights properties must therefore be carried out by assuming that they have potential to form part or all of a future gold mine. Such analysis involves the simulation of many of the estimation procedures that are normally carried out in a full feasibility study of a new mining venture but using far less data. This paper describes in detail the evaluation procedures that may be applied to an individual property and then indicates how these techniques can be applied to a whole mineral rights portfolio.

Jan 1, 1989

By William J. Wasko

Maintenance of mining equipment has become so complex and important from a cost and product ion standpoint that the organization must be set up in an engineering fashion to be successful. Production costs are greatly affected by proper maintenance. Tonnages can only be met when operating time is at its maximum and breakdown time is at its minimum. Last, but equally important, large capital expenditures must be protected and improved The effectiveness of the maintenance program will, in many respects, be a direct, result of the effort put torch in developing the overall program. Once the need of maintenance is realized, the next step is to determine what the organization should be and what it should accomplish. Follow through is then most vital. Preventing machine breakdowns and reducing maintenance costs are the primary goals of all maintenance organizations. Good preventive maintenance, a system for inspecting equipment and a complete record of inspections will help attain these goals.

Jan 1, 1966

By D. Lynn, D. Arthur

Infrastructures continue to age and drinking water supplies are becoming scarce in the San Fernando Valley of Los Angeles, California. Frontier-Kemper Constructors, Inc. (FKCI) was engaged by the Los Angeles Department of Water and Power (LADWP) to complete the River Supply Conduit Improvement Upper Reach—Unit 7 Project (RSC7). Two tunnel sections were bored using a 2.64 meter diameter Microtunnel Boring Machine (MTBM) and a 4.12 meter diameter Earth Pressure Balance Tunnel Boring Machine (EPBTBM) to excavate approximately 3,733 meters (3.7 km) of tunnels through highly abrasive late-Pleistocene-age Quaternary alluvial deposits (Old Alluvium) and Holocene age Young Alluvium deposits above the water table. This paper discusses the challenges encountered managing the TBM’s equipment degradation, use of soil conditioners, cutterhead wear, torque and advance rates while maintaining the necessary face-pressures and parameters to limit over excavation and ground settlement.

Jun 13, 2021

By Bruce F. Bohor

Silica sand has been mined in Illinois from the St. Peter Sandstone since the turn of the century, especially in the area around Ottawa on the Illinois River in the north-central part of the state. Production of this sand, consumed mainly by the glass and foundry industries but also sought after for many other uses, has grown with the economy, and last year's output in Illinois exceeded 4,000,000 tons. Such an important commodity was given the early attention of the Illinois State Geological Survey, and a very complete report was issued in 1928, authored by J. E. Lamar. The mining and processing of the sand has changed very little during the intervening 40 years, so that much of Lamar's data and descriptions are applicable today. More recently, the stratigraphy of the St. Peter Sandstone in north-central Illinois has become better known from the work of Willman and Payne (1942). The present authors have borrowed generously from Lamar's publication, and we wish to acknowledge the contribution of both of these studies to our work.

Jan 1, 1969

By G. T. Adel, W. Z. Choi

A model describing size reduction and mineral liberation during grinding has been extended to include multiple classes of composite particles. The majority of the model parameters have been directly determined using computerized image processing equipment to analyze the products from batch grinding tests. A coarse-grained sphalerite ore from Tennessee, representing a nearly ideal binary mixture of sphulerite and dolomite, has been used to experimentally validate the model for the case of dry batch grinding. In all cases, excellent agreement has been observed between the model predictions and the experimental results.

Jan 1, 1988

By Q. Feng

Study has been carried out to apply fly ash as a high strength, water-resistant precast construction material through geopolymerization. Experiment results show that the working conditions such as water content, the concentration of NaOH, curing temperature and curing time, significantly affect the mechanical property of geopolymer matrix. Through optimization, an above 100 MPa compressive strength has been achieved with the geopolymerization products. Water soaking tests show that the geopolymerization product has a very high water resistance without losing noticeable compressive strength even after a one month soaking time. To elucidate the geopolymerization mechanism, microscopic techniques such as SEM/EDS and XRD are also applied to investigate the microstructure, the elemental and phase composition of geopolymerization products. The findings of the present work provide a novel method to apply fly ash as a high strength water-resistant precast construction material. INTRODUCTION Geopolymerization is a process of obtaining a polymeric structure from aluminosilicate by dissolving aluminosilicate sources in a strong alkali (NaOH) solution and condensation of free [SiO4] and [AlO4] tetrahedral units (Davidovits, 1985 and 1988; Duxson et al, 2005; Xu et al, 2000, 2002). After being cured at an elevated temperature for a specific time, the geopolymerization product shows a greatly increased compressive strength. Therefore, the product can be used as construction material such as bricks and road pavement. It provides a very promising method to apply aluminosilicate sources such as fly ash as a construction material for a sustainable development. Fly ash is a main industrial waste which needs to be carefully impounded because of its potential impact on environment. Many efforts have been tried to utilize fly ash as construction materials substituting Portland cement because of the following reasons. First, fly ash is a silica/alumina rich aluminosilicate source, which makes the specific material an ideal source for the geopolymerization process. Secondly, the particle size of fly ash is usually very small (< 50 microns) and it saves a lot of energy consumed during the production process of cement for grinding. Thirdly, fly ash is an ideal source for geopolymerization because it is reactive to alkali even at a mild temperature. In the past twenty years, many studies have been carried out on the geopolymerization of fly ash to a make construction material. However, there are some disadvantages associated with the conventional methods of treating fly ash (Palomo et al, 1999; Perera et al, 2007; Temuujin, et al, 2009; Hanjitsuwan et al, 2014). First, in most of the proposed geopolymerization methods, a salient amount of sodium silicate has to be added. It therefore makes it complex whether the achieved mechanical strength of geopolymerization products is due to a real geopolymerization process between fly ash and alkali or just largely the solidification of metal silicate in air at an elevated temperature. Secondly, the authors have noticed that when the geopolymerization product is soaked in water, the solution pH increases sharply and the products will lose its compressive strength gradually in water. Thirdly, the compressive strength of the geopolymerization product as reported is usually less than 50 MPa.

Jan 1, 2019

By Steven J. Schatzel

A study was made of frictional ignitions in the underground coal mining industry from 1980 to 1992. The population of frictional ignitions was correlated to a variety of potential contributing factors including the mined coalbed, geographic location, mine production, methane gas emissions, and the type of mining equipment in use. The number of frictional ignitions reported in 1991 and 1992 surpassed the annual totals in all previous years included in the study. Most frictional ignitions occur during cutting operations at a coal face by a continuous miner. The average coal production of mines experiencing frictional ignitions is greater than the average of all underground coal mines throughout the survey period. Methane drainage may have produced a drop in the ratio of gas emissions to coal production (E/P) in mines experiencing frictional ignitions.

Jan 1, 1995

By Jerry M. Whiting, Landy A. Stinnett

The subject of this paper is broad and complex. Secondly, it is near and dear to the authors&apos; hearts. Therefore, it doesn&apos;t seem possible to deal with every aspect of it in less space than a good size textbook. Also, if we dealt with all of the basics of feasibility studies and report preparation, we would cover a lot of material available in the literature, and would have to minimize our editorial comments. In view of these limiting realities, we have chosen to discuss selected facets of the subject, and to provide several comments which stem from our personal experiences during the past 20 years. "Think Ahead" hen someone is undergoing training to command a large ship, the following short phrase is engraved in his memory: "Think Ahead." The reason is simple enough. A battleship, aircraft carrier or oil tanker cannot change directions quickly, and if one waits to a what the other ship is going to do, there may be twisted metal and bodies scattered all over the ocean floor. The commanding officer has to use radar, forward rind aft lookouts, experience, common sense, intuition, weather forecasts, and everything else available to him to avoid trouble. Remember the USS Stark, and the fate of its captain? The fact the Stark was hit by a "friendly" missile didn&apos;t lessen the damage. How about running into a mine? Is it an excuse that no one thought about the possibility of a minefield ahead of the ship? The point is, relative to feasibility studies, that its prospective authors, and especially the commander of the efforts required to create it, must "think ahead" from the moment of their association with 4 mining activity. They must

Jan 1, 1987

By P. W. Erickson

Development of the Twin Buttes mine entailed the largest known preproduction stripping job in the history of mining. It linked earthmovers and conveyor belts in a new approach to development of a pit that may reach, or even exceed, dimensions of 1 x 1-1/2 miles at the surface and go as deep as 1800 feet. The orebody to be stripped was covered by an average of 460 feet of alluvial gravels, which presented an initial stripping job of great magnitude. The initial pit layout and the original time schedule established early in 1965 called for the excavation and disposal of about 250,000,000 tons of alluvial overburden before the end of 1969. Allowing about a year for equipment delivery, this schedule left four years to do the job averaging about 62-1/2 million tons per year. In 1964 when The Anaconda Company undertook the development of Twin Buttes, it was recognized that special planning was necessary for the disposal of waste material and tailings. Environ- mental control was a prime consideration and is particularly sensitive in the Twin Buttes area due to the proximity to residential developments. Disposal of the 250,000,000 tons of alluvium, as well as future rock and tailing waste material, presented a problem which Anaconda engineers resolved by designing a plan to spread out much of the alluvium over an extended area, including a massive 11- 1/2 mile dike system which will impound mill tailing in three basins. The tailing will be impounded behind these-dikes to avoid wind exposure and blowing. The dikes also serve as a

Jan 1, 1974

By Fred N. Kissell

Work done by Foster-Miller Associates under a Bureau of Mines research contract has developed methods to increase significantly the amount of fresh air that reaches the front of a continuous-mining machine. The emphasis was on removing methane build- ups that occur at the cutterhead. Using a full-scale plywood mockup of a coal mine working face area, the study showed that in many instances only about 20 pct of the fresh air heading towards an exhaust brattice or tubing actually gets to within 1 ft (0.3m) of the face. The key to providing more air at the face is to enhance and move forward the natural airflow pattern. This change in the natural airflow pattern can be accomplished by taking advantage of the air-moving abilities of the conventional water spray. It was discovered that if all the water sprays on the machine were realigned, then ventilation efficiencies of 70 pct or more were achieved regularly. This meant that if 9,000 cfm (4.2 m3/s) was entering the brattice, at least 6,300 cfm (3.0 m3/s) of this was reaching to within 1 ft (0.3m) of the face. This water spray realignment consists of placing a few nozzles on the side of the machine opposite the curtain and also tilting the front sprays slightly towards the curtain side. Recently, two underground tests and two additional independent laboratory tests of the water "Spray Fan" have been completed. In general, they have confirmed the performance of the Spray Fan system, but they also have provided useful information as to its difficulties and limitations.

Jan 1, 1980