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By James E. Lawver

At the present time, the Florida phosphate industry is experiencing one of the worst marked slumps in its one hundred year history. Recent agriculture over-production has caused low grain prices such that the net income of U.S. farmers is expected to drop to its lowest level since the 1932 depression. The farmers' low income, along with high interest rates that preclude them from borrowing to purchase fertilizer, make the immediate U.S. phosphate market outlook bleek at best. The export outlook is also pessimistic due to world recession and the U.S. dollar's high exchange rate. In June, 26% of the phosphate industry's workers were laid off for an indefinite period of time. Despite the immediate painful slump, the long-term outlook for the industry looks good. Florida has enormous reserves and will continue to produce a third of the world's phosphate supply simply by making changes in the present system of mining, beneficiation, waste disposal and land reclamation.

Jan 1, 1983

By Lorraine B. Burgin

The extensive lead time to develop most Arizona copper deposits commenced with initial production efforts before the turn of the century, when the first attempts were made to recover gold and silver and later copper from the high-grade vein deposits of the territory. Each of these discoveries, prospects, and early operations had its own lead time and life cycle as economic production was attempted. Because prices of the metals fluctuated and the higher grade material was depleted, economics forced operations to close and companies to fail. Renewed interest in the property because of improved conditions, different interpretation of the geologic structure, or new promotional ability frequently resulted in the formation of yet another company to finance the exploration and, hopefully, the development of the property. This cycle of renewed activity and subsequent abandonment was and is common, accounting for many lead times and for the long period of time from the initial location of claims to large-scale production. In order to gain a perspective on the lead-time interval necessary to achieve development of a large-scale operation, the histories of several major Arizona mines were examined, rather than a simple listing of discovery and production dates of many mines to arrive at a statistical average. The Miami, Castle Dome, Copper Cities, San Manuel, and Twin Buttes properties were studied, and as much data as possible obtained on the Pinto Valley, Esperanza, Sierrita, Pima, and Mineral Park-Ithaca Peak properties.

Jan 1, 1974

By M. Saunders Macdonald

A number of open pit gold mines in Nevada extract ore from areas below natural groundwater elevations, necessitating dewatering and some method of disposal of the extracted water. These open pits extend well below the water table, with associated dewatering volumes greater than 10,000 gpm. Some mines, with large volumes of dewatering water to manage, have constructed re-infiltration basins to re-introduce dewatering water to the groundwater system some distance from the pits. This paper presents an overview of the state of the art of re-infiltration projects, including the permit process for such projects in Nevada, and the necessary engineering considerations.

Jan 1, 1996

By M. Heger, V. Lund, P. Mongeon, D. Bogunovic, V. Kecojevic

The U.S. coal mining industry consumes a significant amount of energy, primarily diesel fuel and electricity. The continuous global increase in energy demand, high energy prices and environmental issues related to carbon dioxide emission represent a substantial challenge for the mining industry. This paper presents the result of research on development of an integrated data environment system for analysis of energy consumption in a surface coal mine. A case study on an operating surface coal mine is carried out to demonstrate the practical application of the developed system. The research work presented here may be used by mining professionals to help provide the answers to the crucial questions of when, where and how much energy is being used. This developed system represents a framework for efficient management of energy consumption.

Jan 1, 2009

By T. P. Meloy

The packed column flotation cell is an awesome separation device. Virtually unknown and untested, the packed column flotation cell is one of the ten most important developments in mineral processing of the 21st century. Though experimental and industrial data is limited, it is clear that the packed column flotation cell is two to three orders of magnitude better than the conventional flotation cell and one to one and a half orders of magnitude better than the open column flotation cell. With the modern packing taking up less than one percent of the packed column, column blocking does not occur. For a packed column operating 24 hours a day, 365 days a year, the estimated mean time between failures (MTBF) is one hundred thousand hours or roughly twelve years. With no moving parts, lower maintenance costs, lower power consumption and inherent operating stability, the packed column is a powerful separating machine. Because there is little meaningful data for comparing the packed column to the conventional flotation cell and the open column flotation cell, much of the material presented in this paper are guesstimates. They are disinterested guesstimate made by the authors after extensive theoretical work and reviewing the known facts. In the authors' opinion, no available data contradicts the guesstimate. The authors expect that there may be errors as large as three hundred percent. Even three hundred percent errors will not change the conclusions of this paper. The packed column flotation cell is a formidable separating device. To understand the problems of comparing the three types of flotation cells, consider the fact that the three cells may have different modes of separation. One of the authors, Meloy, believes that in the conventional cell, the primary particle separation takes place in the liquor with secondary separation taking place in the froth, while for open column flotation, all the separation takes place in the froth. However, he believes that in the packed column a large part of the separation may take place on the walls of the packing. If this is true, not only is the method of modeling each type of cell different, but the method of particle selection in the cell is different. This means that one type of cell may be better at differentiating between two different types of particles. There is a growing body of literature on open and packed column flotation. Suggested reading: (Clarke et al; Hucko et al; Li; Smith & Warren; and Yang).

Jan 1, 1994

By A. Haghighat

A risk analysis on mine fires for all U.S. underground coal mines from 2000–2012 was completed to identify locations that have a high risk for fire incidents. The data for this analysis was extracted from the Mine Safety and Health Administration’s (MSHA) mine fire accident reports database. After identifying fire incidents from this database, a risk matrix was developed for underground locations that showed a significant propensity for fire incidents. This matrix associates the hazards and risks with the severity and frequency of their consequences at each location. These significant mine areas will be the concentration of future studies in fire behavior, suppression techniques, and simulation methodologies. INTRODUCTION Fires in underground mines pose significant hazards to personnel because of inherent restrictions to movement and limitations to egress routes. Despite improvements, mine fires remain serious hazards in underground coal mine. In order to better mitigate the risks from fire hazards in the modern underground mining environment, a better understanding of where fire events occur must be gained. The following paper presents an investigation on the number of fatal and non-fatal incidents in underground coal mines fires from 2000 to 2012. Three phases of risk assessment (i.e., risk identification, estimation, and evaluation) were applied to the recorded fire events from the MSHA incident database that occurred during this time period. Using this process, a fire hazard was first defined. This definition was then used to identify any incidents that had occurred as a result of the defined hazards. The seriousness of the injuries and damages were finally quantified for each incident though an estimate of severity and frequency and then aggregated according to underground location (ISO, 1999; Van Duijne, 2008). Using this approach, locations prone to incidents resulting from fire hazards were first identified. The risk for the occurrence a fire incident in general was then estimated for each of the identified locations. The results of this assessment will be used to improve fire simulation techniques for the identified, high risk underground locations. RISK IDENTIFICATION A risk for this assessment was defined as any single occurrence of a fire initiated by the ignition of gas, dust, or electricity. Each recorded occurrence of such an event in the MSHA incident database was counted as a single fire incident. Both non-fatal incidents that were reportable but did not result in a fatality and fatal incidents that fell into the aforementioned criteria were counted. Incidents in the MSHA database that were already classified as “generic” were not considered. The remaining incidents were then totaled and aggregated according to the underground location in which they occurred. In previous studies, a number of locations, which are listed in Table 1, were highlighted as high fire hazard areas (McDonald et al, 1980; Pomroy et al, 1995; De Rosa, 2004). These locations were used to group the fire incidents extracted from the MSHA incident database. The compiled numbers of non-fatal and fatal underground coal fire incidents from 2000 to 2012 are displayed in Table 1.

Jan 1, 2019

By Yuting Xue, Khaled Mohamed

The failure of coal ribs is a major hazard in underground coal mines. Researchers from the National Institute for Occupational Safety and Health (NIOSH) have been working on the development of an engineering-based rib control method. A user-friendly standalone application, called Design of Rib Support (DORS), is being developed to ease the calculations of rib support. DORS can estimate the Primary Rib Support Density (PRSD, ton/ft2) for development loading. However, it still needs to take account of another key factor, bolt length, in rib support design. The bolt length can be estimated from the rib fracture depth, and this study focuses on the coal rib fracture depth analysis with numerical modeling and artificial neural network. A total of 331 FLAC3D simulations with different mining scenarios and rib conditions were conducted for this study. Machine learning was then used to predict coal rib fracture depth under different conditions. Based on the numerical simulations, the parameters for mining scenarios and rib conditions were collected as features for machine learning, and coal rib fracture depths were collected as the target to predict. Good data correlation (r-square) was obtained with the use of an artificial neural network. The

By J. J. Moore

Combustion synthesis, or self-propagating high-temperature synthesis (SHS), reaction systems are discussed with respect to thermodynamics and kinetics. In particular, the effect of the process parameters, e.g. particle size, [All] ignition and combustion temperatures, on these self-sustaining reactions is discussed. Combustion theory is used to investigate the effect of the overall actuation energy of the SHS reaction on the combustion front propagation rate and in obtaining a clearer understanding of the transition from stable to unstable propagation. Finally, examples of the application of combustion synthesis to advanced materials processes are made, in particular the synthesis of Ni-Ti-X intermetallic shape memory alloys, TiC-AI2O3 and ZrB2-AI203 ceramic composite materials.

Jan 1, 1992

By K. C. Kocsis

Underground ventilation systems, which require electricity to operate the fans and fossil fuel for heating in winter, can account for a significant portion of the energy consumption of mines. Recent studies have shown that the ventilation system in deep and highly mechanized metal mines could be responsible for 40 to 60 percent of their overall energy consumption. Presently, underground ventilation systems are designed for peak air volume requirements, which usually occur well into a future stage of the mines’ operating life. As a result, during their early operating stages, the intake air volume of the mines could be well in excess of their true air volume needs. Such ventilation systems could be considered as uneconomic, and to remain competitive the ventilation design needs to improve while the mines are trying to reduce energy consumption and their carbon footprints. This paper introduces a new mine ventilation design method where an underground base-metal mine’s ventilation system is designed by integrating discrete-event mining process simulation (DES) with mine ventilation modeling techniques. Furthermore, based upon the output data generated by means of discrete-event mining process simulations, the air volume requirement for the operating life of the mine is determined for “traditional” versus “activity-based” ventilation requirements. The output data generated through ventilation simulations are then used to quantify the economic and environmental benefits of an activity-based ventilation delivery system.

Jan 1, 2018

By William J. Wiehagen

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

Jan 1, 1983

By Wilfred Walker

Much is known of the geography of the Alpine orogeny because it has now ended and all geosynclines are in their terminal, cordilleran form. The principle of sea floor spreading, continental drift, and mantle cells has gained general acceptance, but the number and position of the cells, even during the Alpine orogeny, is controversial. The oceanographers have demonstrated the uprises and in this paper it is suggested that downflows are marked by island arcs in the oceans and geosynclines (now cordillera) in the continents, for a total of about a dozen cells. Major mineral deposits associated-with the Alpine downflows are porphyry copper, molybdenum, nickel, chrome, lead-zinc-silver, gold, mercury, tungsten, and tin. Amore precise environment is known for some of these metals, for example, nickel, chrome, and mercury in flysch (which flanks mantle downturns), Ten major orogenies have taken place from 3500 m.y. to the present, Their re¬construction and metallogenesis is the subject of a continuing study.

Jan 1, 1971

By C. L. Karr, D. L. Meredith, D. A. Stanley

The U.S. Bureau of Mines is currently investigating ways to combine the learning capabilities of genetic algorithms with the process control capabilities of fuzzy logic. Fuzzy logic has been successfully used for controlling a number of physical systems. However, the selection of acceptable fuzzy membership functions has generally been a subjective decision. In this paper, high-performance fuzzy membership functions are learned using a genetic algorithm, a search technique based on the mechanics of natural genetics. The membership functions learned by the genetic algorithm provide for a more efficient fuzzy logic controller than the membership functions selected by the authors for the liquid level system considered. The approach to developing genetic algorithm-based fuzzy logic controllers is demonstrated on a liquid level controller.

Jan 1, 1990

By D. Marsh

The feasibility study for the Grasberg Block Cave mine, finalized in May 2008, indicated a production capacity of 160,000 tonnes per day. A rail haulage system was an integral part of the mine design. This paper describes the simulation process used in optimizing the design and discusses the key factors and variables that impact the capacity of the system. The final recommendations for the haulage level layout and associated equipment are also included.

Jan 1, 2010

Gold cyanide equilibrium adsorption isotherms in the loading range typical of operating carbon-in-pulp/carbon-in-leach plants have been established and the effect of various cations and the presence of copper cyanide species quantified. It was found that the equilibrium loading of gold was enhanced by the presence of sodium or calcium, with calcium having an order of magnitude stronger effect. The presence of copper has an adverse effect on the equilibrium loading of gold. A unified model was developed to predict the effect of sodium and calcium concentrations in solution and the competitive carbon adsorption of copper on the equilibrium loading of gold on carbon. A satisfactory agreement between the measured gold equilibrium loadings and the model results was obtained over a wide range of solution conditions.

Jan 1, 2010

By A. E. Petersen

The United States Bureau of Mines conducted research on high-intensity magnetic separation methods for upgrading tantalum concentrates from Alabama. Process flow sheets were studied to maximize tin removal and minimize tantalum loss. Using laboratory-scale equipment, concentrates were produced which contained over 65% combined Ta2O5-Nb2O5. Up to 78% of the tin was recovered as a byproduct, containing about 70% SnO2. Only 1 to 5% of the tantalum reported with the tin byproduct. The producer subsequently incorporated high-intensity magnetic separation into its process flow sheet to provide concentrates for the National Defense Stockpile.

Jan 1, 1993

By Andrew Torok

Activated bleaching clays, so called because of their ability to remove color bodies from bleach fats and oils, are produced from clays of bentonitic origin. Activation is achieved by subjecting these clays to physical or chemical alteration to increase selective sorption capacities (1) . The future of activated bleaching clays depends upon the ability of producers to recognize the new areas of applications which are arising, and their skill in developing sophisticated active clays to meet new and stringent requirements. The major portion of activated bentonites are produced for decolorization of oils. New techniques of activation will improve these clays for broader spectrum use. General properties expected to result from present activation methods are: 1. Modification of hydrophobic-hydrophilic properties and increased available surface area in non-aqueous systems, thereby improving sorption capacity and ability to remove color bodies from oils. The following additional properties will be expected from future activated clays: 2. High purity of the active clay with interfering impurities totally removed. 3. Increased selective sorption capacity in aqueous systems. 4. Selective chemical reactivity, such as oxidation or hydrolysis. This property is required for removing

Jan 1, 1971

By A Pettersson

LKAB owns and operates two of the largest underground mines in the world in Northern Sweden. In Malmberget, with a production capacity of about 30,000 t/day of iron ore, the current main 815 m haulage level is rapidly approaching the end of Its life and plans are being made for its replacement on the 1000 m level. Due to the separation of the orebodies, trucks have been chosen for transporting the ore from the orepasses to the crushers. The trucks currently in use have a capacity of 120 tons. To increase the efficiency of the loaded haul, the new main level will have a favorable slope from the drawpoint locations to the crushers. From the new level the crushed ore will be transported by conveyor to the 815 m level for hoisting to the surface. The paper discusses the planned mining and transportation system.

Jan 1, 1998

By Frederick McNeill, John Harper, Mahmood Khwaja, Shawn Lavoie, Timothy Cloughert, David Polcari

City of Manchester, NH, is implementing a 20-year plan to control and significantly reduce overflow of its sewer system. The long-term control plan had called for large scale box culvert installation through downtown Manchester. The City and the project team evaluated, and eventually selected, tunneling as an alternative to mitigate construction related impacts for open trench approach. This paper provides an overview of the alternative evaluation process; discusses the development of the preliminary design for the 12,000 feet long, 12-ft internal diameter tunnel, including plan and profile selection, subsurface conditions, drop shafts and the anticipated packaging of the separation areas.

Dec 1, 2022

By Ossi V. I. Hintikka

There are several limestone deposits around the Lohja area in southern Finland. Raw material for cement rock is mined from some of them. The formations are geologically complicated, and therefore selective mining is used whenever possible. One of these mines is the Tytyri underground limestone mine, which is divided into two parts; Törmä and Solhem. In addition to the selective mining system hand sorting or picking must be used at the Tytyri mine to improve the overall grade of the blended limestone. Some means were needed in order to improve the quality and to increase the feed rate by the elimination of hand sorting. Sorting machines were considered and eventually a Sortex 811MW was pilot plant tested at the Ojamo mine near Tytyri. This machine now continues to be used on production.

Jan 1, 1971

By Bruce Hern

The last 10 years have seen a dramatic increase in the requirements for product coal quality control. This has led to electric utility sulfur scrubbing, metallurgical blast furnace optimization and coal producer blend and yield optimization. To achieve this improved level of control, coal producers are designing facilities that emphasize new technology. New facilities will be designed and existing facilities will be retrofitted with state-of-the-art technology to meet quality control standards that are dictated by the market. The first step in designing for process control requires the identification of those parameters to be controlled and the upsets that can cause variances in the final shipped product quality. The most common parameters that require control are the surface moisture (%), ash (%), pyritic sulfur (%) and gross calorific value (Btu). Total moisture is that moisture that exists on the surface of the particle and is inherent in the particle itself. For the purposes of control, the total moisture is monitored, while surface moisture is controlled. Ash is the inorganic residue remaining after all other constituents are burned away at 75O°C( 1382°F)(ASTM, 1992). Sulfur is the amount of total sulfur that exists either as pyrite (FeS2), inorganic sulfate (FeS04), or organic sulfates (C4H4S) (Leonard, 1979). Currently, pyrite is controlled and total sulfur is monitored. The gross calorific value is the amount of heat produced when a unit quantity of coal is ignited under specified conditions. In this case, a l-g (0.03-oz.) sample of coal is ignited in an isoperibol waterbath and the temperature rise of the water bath is observed. The moisture and ash-free (MAF) Btu is relatively constant for a given seam, resulting in the whole calorific value being a function of the moisture and ash levels (Leonard, 1979).

Jan 1, 1994