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By B. R. Utz

The goal of the DOE Coal Preparation Program is to provide industry with the scientific and engineering knowledge base to produce economically competitive and environmentally acceptable clean coal products for both existing and new markets. The DOE/PETC in-house program continues to conduct fundamental, exploratory, and applied research in the areas of physical, chemical, and microbial coal beneficiation to assist in meeting these goals and objectives. The Coal Preparation Division now has a new Coal Preparation Process Research Facility that allows continuous bench-scale testing of emerging coal cleaning technologies and ancillary coal preparation equipment at feed rates up to 1,250 kilograms (1.25 tons) per hour. Bench-scale and laboratory-scale research projects at PETC cover areas such as 1) the use of micronized-magnetite for fine-coal, 2) heavy-media cycloning, 3) fine coal reconstitution, 4) development and testing of coal preparation process flowsheet simulators, 5) dry coal beneficiation using electrostatic methods, 6) tracer methods to determine the efficiency of density-based separations, 7) selective oxidation of organic sulfur, and 8) microbial removal of pyrite and organic sulfur from coal. This paper will discuss several of these research areas.

Jan 1, 1993

By D. W. Park

Longwall mining is considered the most efficient underground coal mining technique in terms of coal extraction ratio, production rate, and safety standards. Due to the increasing demand for higher coal production, wider panel and faster face movement have become the recent trends. Thus, longwall mining can create unexpected threats such as roof falls, excessive face convergence, shield damage and numerous maintenance problems causing sudden interruption of coal production and serious safety hazards. A recent study at the University of Alabama is dedicated to develop LoSCoMS (Longwall Strata Control and Maintenance System) which integrates real-time shield monitoring, data presentation, analysis, forecasting, and warning modules. The main objectives of this system is to provide the stability and maintenance information, at every minute, such as high load, low setting pressure, leg leakage, etc., analysis of various mining and geological parameters to determine past and present roof characteristics and forecasting of loading patterns for the following mining cycles, next periodic weighting, etc. Using this unique system, mine operating personnel are well aware of past, present and future roof loading patterns at the longwall face, and thus, proper safety measures can be taken ahead of time.

Jan 1, 1997

By R. J. Caine

Like most major firms engaged in project management, Dravo Corporation faces a constant challenge to keep its management systems in tune with the ever-increasing demands imposed by larger and more complex projects. This paper suggests that one of the key elements in meeting this challenge is more effective organization of project data. It reveals some of the details of a program at Dravo's Minerals 6 Metals Division which seeks, through better organization of project data, to improve Dravo's capabilities in estimating, cost control, scheduling, performance reporting and material control. In particular, this paper discusses ideas Dravo is developing for improved job numbering, codes of accounts, requisition and purchase order numbering, inventory cataloging, and employee/badge numbering.

Jan 1, 1980

By A. L. Crandell

The Cortez Mining District has had a long history of mining activity dating back to 1862 as previously reported (1) (2). More recently Cortez Gold Mines (i) has operated a cyanide leach, counter current decantation (CCD) recovery gold mill from January 1969 to February 1976. This type of plant has been standard in the U.S. for treating higher grade finely disseminated gold in Carlin type ores. The mill was initially operated from 1969 to 1973 at 1520 tonnes per day on oxidized ore from the Cortez ore body. Starting in 1973, the mill was operated at 2050 tonnes per day on softer, less oxidized, high clay ore from Gold Acres which is located 13 kilometers to the west of the Cortez installation. In February of 1976 the oxidized portion of the ore body at Gold Acres was depleted and the mill ceased operation. Successful heap leaching of the lower grade portion of the ores was practiced at both Cortez and Gold Acres to supplement the milling operations. Much valuable experience was gained in the operation of these two heap leaching programs and is well described in an earlier publication (3). Releaching of the ore heaps at Gold Acres and Cortez was continued with a limited crew from 1976 to 1979.

Jan 1, 1986

By D. W. Frommer

In continuing its long range studies of methods of treating low-grade iron ores, the Bureau of Mines has developed a new selective flocculation, desliming, and flotation procedure that enables effective beneficiation of the finely disseminated ferruginous jaspers of the Marquette range, Mich. The process, developed on a bench scale and later confirmed in the 800-lb/hr pilot plant, comprises dispersion, selective flocculation, desliming to reject fine silica and clay, and flotation of silica from the remainder of minus 400-mesh pulps. Pilot plant flotation of two Marquette range ores, using the selective flocculation procedure on feeds containing 36 percent Fe, yielded iron recoveries of about 84 percent in concentrates containing 65 to 66 percent Fe and 4 to 5 percent silica. These results were metallurgically superior to those obtained when selective flocculation was not used. Also operating characteristics were better, and reagent costs were lower.

Jan 1, 1964

By Brij M. Moudgil

Separation of dolomite from apatite, because of nonselective adsorption, cannot be achieved by conventional froth flotation technique. Results obtained in the present study also indicate, that this can be attributed to the depletion of the collector molecules due to complexation with the calcium and magnesium ions, dissolved from the two minerals. However, it has been established in this investigation that conditioning the material at pH 10, followed by reconditioning, without any additional collector, at pH 4, results in selective flotation of dolomite from the mixture. The recovery of apatite, in the proposed reconditioning process, is much higher than with the conventional conditioning under similar pH conditions. The mechanisms involved in the conventional conditioning, and the reconditioning process are presented.

Jan 1, 1983

By D. R. Forshey

Although the United States has the world's largest coal reserves, most of those reserves will require underground mining. Unless underground injury and fatality rates are reduced, the number of disabling injuries and accidental deaths will grow as coal production increases. The Bureau's Mining Research Program, designed to reduce the exposure of workers to hazards while improving productivity, is described. Major program thrusts are 1) re- moving the hazards or removing miners from the areas in which hazards exist, 2) developing ways to improve management decisions and mining skills so as to reduce the incidence of situations requiring human involvement in hazardous, emergency, or corrective tasks, and 3) improving, or at least maintaining, productivity so that both the tangible (dollar) and intangible (human) costs are reduced. In these ways, projected demands for coal can be met using resources without an increase in human suffering.

Jan 1, 1987

The objective of this paper is, firstly, to summarize several field developments utilizing the art of hydraulic fracturing as it has been extended into various mining applications. Secondly, to summarize the understanding of the hydraulic fracturing processes; and lastly to discuss researchable areas and possible future applications. Hydraulic fracturing was developed as a method of stimulating production of oil from oil producing formations. The primary paper by Clark (1) in 1949, describes the process of placing a hydrostatic pressure of sufficient strength on the producing formation of an oil well that the rock apparently cracked, and then, on allowing the well to flow back, a higher rate of recovery of oil was enjoyed. The interpretation of the process mechanism was that the formation rock was cracked to a considerable distance from the well bore, increasing the drainage area; thus, the productivity of the well was measurably improved. Figure 1 is illustrative of this process. This development was of major significance to the oil producing community and considerable research and development ensued. Improvements in method, engineering development of equipment, and research to ascertain the optimum application of fracturing practice led to a highly sophisticated, but specialized technology. The Production Research Division, Continental Oil Company, vigorously pursued research in this area in the 1950's with a resulting number of process improve¬ments. The research group, published a significant number of technical papers on these various researches. One of the developments was the process aimed at controlled orientation of the fractures, either in the vertical (2) or horizontal (3) orientation.

Jan 1, 1969

By John E. Bailey

The advent of Nuclear Energy has caused a phenomenal growth in the uranium mining industry. To keep abreast of this surge the mining industry has located many ore bodies, determined the best types of mining adaptable to this particular type of ore and developed a highly specialized type of operation. But, has the mining industry gone far enough in the planning? Has ?built-in? safety been included in the efficient methods of operation? Preplanning safety in the mining industry, as in all industries, takes engineering and ingenuity combined with the experience and cooperation of all concerned. A system of mining can be planned on a map and it will look good. However, when the actual mining takes place, conditions may be such that deviations from the original plans may be required because of excessive water faults or other conditions encountered. With safety we may also be required to change, to conform to the characteristics of a particular operation. People in the mining industry are well aware that loose back has killed miners each year. This condition occurred in practically all types of mines. The condition is not new to us. It is also known that explosives, haulage, machinery and conditions common to all types of mining have taken a heavy toll of human life in mining. In addition to these hazards in the uranium mines, the hazard of radon is also present, Radon is a radioactive gas liberated from ores containing radium. This gas is released into the active workings by the blasting or breaking up of the ore. Sometimes it is caused by radium contaminated water seepage from abandoned workings or from the ore body itself. Until the action of this gas on the human was known, many miners were affected. Un- less adequate precuations are taken to protect the people in these mines,, they may be exposed to this hazard, Health researchers made a study of this substance to determine how it would affect the health of the men, They also studied men who had worked in previous years, in mines known to have contained radioactive materials. All of this research contributed to the present knowledge of radon and its daughter products. It is not flammable nor explosive, but, if allowed to enter the body through the respiratory organs it can cause serious damage. Mines have been operated in the past and are still being operated, which were known to contain explosive and noxious gases, indicating that this problem can be controlled. Several states have instituted laws that make it mandatory to provide adequate ventilation and use of monitoring devices to limit radon and its daughter products to a maximum of 300 micro-microcuries per liter of air. This is considered a safe limit for sustained periods of human exposure. While the findings of research do not prove conclusively that the inhalation of excessive radon or its daugher products cause lung cancer, indications point to this as a possibility, particularly radium A and radium C1 of the daughter products. The threshold limits set by law in most uranium producing states are believed to be safe. In a few years, when tests and data now in the process of collection by interested state officials and laboratories is complete, these limits may be found to be ready for revision. Studies such as these take time. At present, the limits that are used are based upon estimates. The permissible limits of exposure to radon and daughter products include a large safety factor. It is considered that a good supply of fresh air delivered to the working places, adequate dust control, the sealing of unused or abandoned workings, the removal of mine water which is generally contaminated and a safe waiting period after blasting, will hold to a minimum the dangers from this source. There are, of course, problems accompanying each of these procedures. For example, the ventilating of untimbered raises and bringing fresh, uncontaminated air to the working places may be a problem. However, a good mining man can solve these problems as they apply in each particular operation. From the information available at the present time, the daughter products containing polonium and emitting alpha radiation, may be a health hazard. Fortunately, the half life of most of the daughter products is short, however, radium D has a half life of 22 years and presents a problem of contamination in the storage of old tailings. So we can see that failure to comply with the accepted good mining practices may have harmful effects on the health of miners. It is gratifying to note the interest in this potential hazard by the officials in the uranium ore producing states, who are making extensive studies and keeping records of the men who work in this type of mining. This all provide information necessary for preplanning safety. By contrast, little has been accomplished to control the injuries and deaths from some other factors connected with most underground mining operations. I would like to discuss briefly one of the hazards which take an annual toll in our underground mines, this is falls of back and walls. This problem or hazard is present, and will be

Jan 1, 1958

The Longwall Strata Control and Maintenance System (LoSCoMS) is designed to monitor shield pressures in real-time from longwall faces and to provide on-line information related to underground strata behavior and longwall mining operation. The information includes shield pressure data with statistical analysis of setting, developing and final pressures, prediction of shield pressures for the following shift or day, etc. and maintenance data on the shields. The LoSCoMS has been installed and tested at Shoal Creek Mine operated by Drummond Company, Inc. The system is providing valuable information to mine operators for better understanding of underground behaviors. As a result, it has become an effective tool for minimizing ground control hazards and reducing out of seam material.

Jan 1, 1997

By Leonard Bronitsky

The construction mineral aggregates industry--the largest industry on a tonnage basis--is threatened with large shortages in the near future. Ironically, these common minerals which include sand, gravel, and stone are among the most plentiful in the earth's crust. However, as these minerals are low in value and used in large volumes, they are extremely sensitive to transport cost, e.g., a haul of 20 miles doubled the delivered cost of mineral aggregates. Consequently, these minerals must be located close to points of demand to have economic usefulness. But the development of new deposits is virtually impossible near many urban areas for legal, sociological and economic reasons. The spector of unfinished urban transport systems, curtailed residential construction, and a general deterioration of the physical urban plant, looms as a direct consequent of future mineral aggregate shortages in the U. S. metropolitan areas. The shortages of mineral aggregates in the Greater New York Metropolitan Area (G.N.Y.M.A.) are prototypical of the shortages faced by the U. S. Metropolitan areas. This paper presents an economic analysis of the consequences of not considering the broad aspects of conservation economics as a major component of resource management. The needless annual cost for the G.N.Y.M.A. is shown to be $30 million.

Jan 1, 1974

By Robert A. Westin

Polychlorinated biphenyls (PCBs) are a group of chlorinated chemicals that were used in many different fire resistant hydraulic fluids, heat transfer fluids, and in electrical equipment as dielectric liquids. PCBs were manufactured primarily by Monsanto Chemical Company under the tradename Aroclor, and were used by many different electrical equipment manufacturers. PCBs are noted chiefly for their extreme chemical inertness. This resulted in exceptional fire resistance and long life in applications involving exposure to high temperatures and intense electrical fields. This combination of properties resulted in PCBs being widely used in electrical equipment used in mines, including transformers, capacitors, and some electric motors. PCBs were also used as working fluids in some heat transfer and hydraulic sys terns. The same chemical resistance that gave PCBs long life in industrial applications give PCBs essantially eternal life when they are released into the environment. PCBs are not highly toxic in the sense that exposure does not cause immediate health problems. However, PCBs accumulate in the human body and neither degrade nor are eliminated from the body, and long-term exposure to PCBs can result in changes in liver function which may increase susceptibility to the carcinogenic effects of other chemicals. PCBs also accumulate in the food chain; the concentration of PCBs in fresh water fish may be several hundred thousand times as high as in the water the fish are taken from.

Jan 1, 1981

By C. K. C. K. Gupta

The rare earths in elemental form are required for a variety of scientific and technological purposes. They are not easily obtained in this form, due to the great chemical stability of the rare-earth compounds and the strong tendency of elemental metals to react with everything they come in to contact with, especially at high temperatures. Beginning in the 1950s, when sufficient quantities of separated rare earths became available, as the result of intense research and development, three processing routes were developed to accomplish the preparation of all 16 naturally occurring rare-earth elements. They are chemical reduction of the halide intermediates, the oxides and electrochemical reduction of chlorides and oxide-fluoride mixtures. Not all the processes are effective with all the rare earths. In spite of the celebrated similarity of trivalent rare earths, the physical properties of individual rare-earth elements are sufficiently different that a variety of techniques are required for their preparation. The development of reduction processes for the rare-earth metals are covered in this paper, with focus on the oxide reduction routes. The strong reliance of effective reduction processes on the fundamental science of reduction reactions is highlighted.

By M. F. Corcoran

Rapid advances have been made in the past few years in the application of automatic controls and instrumentation to iron ore pelletizing plants. Present practice in applying instrumentation and control to the Grate-Kiln system of iron ore pelletizing is described. Major control points and loops are tabulated. Future trends in the application of digital control including computer data logging systems are described.

Jan 1, 1965

By L. Frost

The establishment of a retreat system of longwall mining in this submarine coal field has been under study for many years and, although in special cases there have been limited local applications of this method of mining, there has been no attempt until quite recently to establish a uniform system of longwall retreating' in this area (see Figure 1) Where retreat walls were established, it was strictly as a result of physical, rather than economic conditions. In some of the operations- of the Corporation, where the coal was liable to spontaneous combustion- or the area subject to bumps as in No. 2 Mine of the Cumberland Railway and Coal Company in Springhills the recovery of the coal on a retreat system was more or less a necessity.

Jan 1, 1964

By C. D. Harrison

This paper presents the results of 18 high-G centrifuge tests performed at the Electric Power Research Institute's Coal Cleaning Test Facility in January 1985. These tests, using -28 mesh (0.6mm) froth flotation product, show that the high-G, solid-bowl centrifuge can produce clean-coal moistures of less than 12 percent at solids recovery rates exceeding 98 percent. The high-G centrifuge achieved these low moistures by applying centrifugal forces up to 2,000 times gravity. Because these forces are two to three times the forces used in a screen-bowl centrifuge, the high-G centrifuge can use a solid bowl and still produce a low-moisture product. The solid bowl captures ultrafines that would pass through a screen bowl, and thus obtains higher recovery rates than a screen-bowl centrifuge.

Jan 1, 1985

By Fred T. Towne

Recent developments in fine grinding by the means of mechanical impaction are the result of continuing improvements in modern machine construction. This is especially true when related to the bearings and mechanically operated parts of impact mills. These improvements allow manufacturers to increase the speeds of the impacting members Most of the more common forms of size reductions, such as percussion, pressure, friction and sectioning, or cutting were at one time accomplished by human hands. These actions were transferred to machinery. Originally of limited application, their use widened as industrial materials and construction became more sophisticated.

Jan 1, 1965

By M. A. Alan

The Bellavista Gold Deposit lies 75 Kms north west of San Jose, the capital of Costa Rica, Central America and 3 Kms north east of Miramar, in the Province of Puntarenas. The total road distance from San Jose to the deposit is 120 Kms all paved road except for a 2.5 Km graded, gravel road on the property (Figure 1). Infrastructure services in the Miramar-Puntarenas area are well developed with electrical power distribution, a modern port facility and community services being available. The deposit lies on the south west flank of the Tilaran Mountain Range between an elevation of 550 and 800 meters above sea level. The local topography is steep, originally covered with pre-montaine, tropical wet forest vegetation which has been largely destroyed due to clearing for cattle grazing. The annual rainfall is approximately 2,950 mms, 90% of which occurs between May and October.

Jan 1, 1992

By Mehmet Guney

[The Atlantis-II-Deep is a hydrothermal mineralization located along the median valley of the Red Sea at a water depth of about 2200 m. Extensive exploration of the metal-rich brine deep revealed a potentially mineable deposit on economic interest consisting of oxides, silicates and sulphides with considerable concentrations of zinc, copper, cadmium and silver. Geostatistics was applied to assess the most likely in-situ vague of the metal potential for economical exploitation. Semi-variograms were constructed to characterize the structure of the regionalized distribution of the geological parameters. Volume grades and thicknesses were determined by the kriging technique, avoiding systematically biased high or low grades, and then block .tonnages were computed. The estimation variances, distribution of errors and histograms of observed and kriged values in each grid Mock were also produced.]

Jan 1, 1983

By John C. Ruckmick

Elemental sulfur deposits generally can be classified as either volcanogenic or biogenic. The latter can be divided into biosyngenetic and bioepigenetic deposits. Essentially all economically important sulfur deposits are bioepigenetic replacements of anhydrite or gypsum in basins containing evaporites and hydrocarbons. Anaerobic bacteria utilize the oxygen of sulfate ions to oxidize hydrocarbons to C02 and reduce the sulfate to H2S. Sulfur deposits are formed by concomitant and subsequent oxidation of the H2S. These bacterial systems can operate on enormous scales, producing deposits containing over 200 million tons of elemental sulfur. There are no known "old" sulfur deposits; almost all known deposits are younger than Miocene and most are still actively forming today. Therefore, it is probable that, with burial and time, sulfur deposits are converted to sulfide deposits. Perhaps more important, bacterial oxidation of hydrocarbons and resultant production and trapping of large quantities of H2S appears to be the logical explanation for the location of many important metal sulfide deposits such as the Mississippi Valley type lead and zinc deposits.

Jan 1, 2013