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By Franklin D. Cooper

The value of nonfuel mineral raw materials produced in the United States in 1978 was $20 billion. In 1979, total value increased to an estimated $24 billion, up 20% from 1978. Of the principal metallic ores produced in 1979, about half showed increased quantitative output and all showed increased value per ton compared with that of 1978. Most nonmetallic commodities showed increases in quantitative output and in average value per ton. Because of its decreasing share of the world market, the domestic mineral industry's concerns were the increasing costs of capital, labor, and energy; withdrawals of public lands from mining; and the increasing cost of environmental regulations that tended to deter or delay investment in the Nation's capacity for producing essential minerals.

Jan 1, 1980

By Richard F. Hewlett

This report describes a comparison of methods for computing grade and tonnage of ore, leach, and waste material for a mined-out portion of the Silver Bell Oxide porphyry copper deposit, and these computed values are compared with the actual tonnage of these classes of material produced during mining operations. Comparisons with production records have been made by using both exploration drill-hole assays and development blast-hole assays. The polygonal method is the most accurate for this deposit, because it more closely represents the lateral mineral distribution in the deposit. This is demonstrated by plots of the total-copper assay distributions of the development blast-hole assays for a specific bench. The investigation also shows that the smaller vertical assay interval (based on a 5-foot vertical churn-drill-hole sample) yields a more accurate estimate of both grade and tonnage than the 40-foot composite assay interval (based on the average of eight 5-foot assay values). This can be attributed to the fact that selective mining within a bench can separate out much of the waste and leach material that is included as ore in the 40-foot composite assay computations.

Jan 1, 1970

By B. P. Martinez

This report presents the results of a research and development program in recovering waste-rolling oils conducted by the Bethlehem Steel Co., before 1954 at its Sparrows Point plant, Sparrow Point, Md., with the cooperation of the Bureau of Mines, U. S. Department of the Interior, College Park, Md. The objective of the program was twofold: First, to recover oil for reuse in the plant; and second, to stop pollution, by oil, of the stream and harbor areas in the immediate vicinity of the plant. The sequence of the investigations was laboratory and pilot plant studies on sedimentation, simple aeration, and flotation for the separation of oil and water; and construction of a production unit using standard flotation equipment. This work was only preliminary for the Bethlehem Steel Co. and it has continued research on this problem. Recent progress indicates that new, improved processes will soon replace the flotation units described in this report. The first efforts to separate oil and water by simple sedimentation were unsuccessful. To establish the cause of this failure, microscope examinations and measurements were made on cold-reduction rolling mill cooling-water effluents containing oil in suspension. It was discovered that an average oil globule, held in suspension, was only 0.001 inch in diameter and would not coagulate with other globules for normal sedimentation at room temperature. The next step in the sequence of studies was to coagulate the oil suspension by simple aeration with air under slight pressure. The aeration methods studied were effective in removing up to 68 percent of the total oil but were approaching flotation in principle. The final investigation of the series was flotation of the oil in conventional laboratory-size flotation cells. The small-bubble method, without reagents, floated up to 89 percent of the total oil held in suspension and was the process selected for pilot-plant development.

Jan 1, 1959

In This Chapter [Ventilation: dilution and displacement Water sprays: wetting and airborne capture Water additives: foam and wetting agents Dust collectors: filtration efficiency and inlet capture efficiency Reducing the generation of dust for cutting, drilling, blasting, crushing, and conveying] [This chapter will give you a general perspective on what works or doesn’t work. The chapter will also help if your dust control problem doesn’t fit any of the circumstances described in later chapters. ] This chapter describes the three major control methods used to reduce airborne dust in tunnels and underground mines: ventilation, water, and dust collectors. It also describes methods to reduce the generation of dust, so less has to be removed from the mine air. The ventilation methods provide the best use of air in the vicinity of workers and in the vicinity of dust sources. In this sense, the methods described are local ventilation methods. Most of the emphasis is on so-called displacement ventilation because it is the most effective dust control technique available. The section on water sprays outlines the dual role of sprays—wetting and airborne capture—and describes why wetting is more important. It also corrects some of the misconceptions about spray effectiveness and describes circumstances where sprays can actually increase the dust exposure of workers. The section on dust collectors outlines the circumstances under which dust collectors can be expected to function effectively. It also describes some common design and maintenance problems. The final section describes how to reduce the amount of dust that gets into the air in the first place, since once the dust is airborne it is always harder to control.

Jan 6, 2003

By Ivette E. Torres

The series summarizing the prices of the major nonferrous metals on the stock exchanges of the United States and the United Kingdom (London Metal Exchange) has been continued this year in tables 22 and 23. Time constraints have prohibited preparation of other price information that has appeared in this study in previous years. Users are urged to consult the 1993 U. S. Bureau of Mines publication Metal Prices in the United States through 1992, which gives an analysis of historical price series and trends, or the 1993 edition of Mineral Commodity Summaries for current U.S. prices on non fuel commodities, and to utilize U.S. Department of Energy sources for information on fuel material costs.

Jan 1, 1994

This chapter summarizes data on crude mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Included also are tables that show the principal mineral commodities exported from and imported into the United States, and that compare world and U.S. mineral production. Except for the mineral fuel commodities, the detailed data from which these tables were derived are contained in the individual commodity chapters of volume I and in the State chapters of volume II of this edition of the Minerals Yearbook. In October 1977, responsibility for the collection of data on mineral fuels-coal, petroleum, natural gas, and natural gas liquids-was transferred to the newly created Department of Energy. Although chapters covering these commodities will no longer appear in Volume I of the Minerals Yearbook, quantity and value data have been included in most of these summary tables to maintain statistical consistency in State and national value of overall crude mineral output. This shift in responsibility has also resulted in changes to the composition of the "Nonmetals? and "Mineral Fuels" groups in table 1 and table 2. The commodities-asphalt and related bitumens (natural), carbon dioxide (natural), helium, and peat-have been removed from the ?Mineral Fuels" group, and are now included under the "Nonmetals" group. There has been no change in the components of the "Metals" group.

Jan 1, 1981

Validate the premise that there is measurable seismic activity associated with abandoned mint lands and that this activity can be used to determine stability of the abandoned mine openings, failure cycle of these openings, and susceptibility of the area to surface subsidence. Approach The U.S. Bureau of Mines conducted field investigations at two geologically contrasting sites, Colorado Springs, CO, and the Allegheny Portage Railroad Historical Site near Cresson, PA, to demonstrate that developing monitoring technology can be applied to any site. An array of seven geophones (velocity-measuring sensors) were strategically located to encompass an area at each site where failure in the underground mine openings could be expected, based on historical, geological, and engineering information. How It Works Bureau research has effectively demonstrated that stress changes within a rock mass can stimulate the development of cracks and fractures, resulting in the release of strain energy that generates seismic waves. These seismic waves, traveling outward from their source, can be detected, and the point of origin can be located in three-dimensional space. Furthermore, these seismic signals contain information that defines the source mechanism and the conditions between the source and the receiving sensor.

Jan 1, 1992

Provide reasonably priced, reliable fire protection for large walking draglines. Approach Fire hazards on large draglines were analyzed, then appropriate automatic fire sensing and suppression systems developed and in-mine tested. How It Works Five fire hazard areas identified for special attention are: electrical control room, high voltage transformer enclosures, circuit breaker rooms, collector ring/roller path area, and the automatic lubrication rooms. Automatic fire sensing and suppression systems were separately designed for each area. The design of each system was tailored to the hazards and equipment protected. Spot thermal sensing and Halon 1301 suppression were specified for the electrical

Jan 1, 1981

By R. F. Abernethy

The work discussed in this report was done by the Bureau of Mines to develop a method for determining trace amounts of fluorine in coal. Samples of coal mixed with calcium oxide as a fixative agent for fluorine were ashed at 600° C and the residue was fused with sodium carbonate. The melt was dissolved in phosphoric and sulfuric acids and distilled to separate the fluorine) which was determined in the distillate by a SPADNS-zirconium spectrophotometric method. Fluorine determinations of 83 commercial coals ranged from 0,001 to 0.019 percent.

Jan 1, 1967

Detect fires in or near mine shafts, isolate smoke filled areas, and remotely extinguish fire. Approach A system (of sensors, automatic alarms, an aboveground control console, remotely operated ventilation doors, and sprinklers) has been built from off the-shelf components, and fire, tested in two mines. How It Works The system uses three different kinds of sensors that can detect the heat or smoke of a fire and automatically actuate alarms. When the alarm sounds in the control center on the surface, water sprays in the mine shaft and shaft station areas can be remotely turned on to deluge both the inside and the outside of the mine shaft's wooden support structure. To protect miners from toxic fumes, smoke control doors can be closed or opened, either remotely from the control center or directly by miners using the manual or electrical actuators at the door locations. Man doors built into each ventilation door allow persons to pass without opening the main door.

Jan 1, 1977

By Terry J. Close

The Gates of the Mountains Wilderness study area is underlain by intrusive and sedimentary rocks, mainly limestone. No limestone has been produced from the study area; suitable material is more readily available elsewhere. Small amounts of gold, sapphires, and corundum were produced from a placer deposit along the banks of the Missouri River. The remaining gravel contains low mineral values. Other alluvial deposits along the Missouri River and Beaver Creek contain no identified economic resources other than sand and gravel. Some deposits could provide suitable construction material for local use.

Jan 1, 1984

By Christopher Mark, Robert J. Tuchman

This proceedings volume contains papers presented at technology transfer seminars sponsored by the National Institute for Occupational Safety and Health (NIOSH) on New Technology for Ground Control in Retreat Mining. The seminars were conducted at five locations: Uniontown, PA (March 26, 1997), Norton, VA (April 8, 1997), Pikeville, KY (April 10, 1997), Charleston, WV (April 17, 1997), and Evansville, IN (April 22, 1997). The papers presented here describe several new, highly practical technologies developed by the NIOSH Pittsburgh and Spokane Research Centers3 to improve safety during pillar retreat operations. Two central issues are addressed: pillar design and mobile roof supports (MRS's). Proper pillar sizing is essential for safe pillar extraction. The Analysis of Retreat Mining Pillar Stability (ARMPS) program and its large data base of actual mining case histories are presented. LAMODEL, a second computer program, can be used for analysis of multiple-seam and other complex mining situations. Other papers address pillar design to avoid massive pillar collapses and the proper role of coal strength testing. MRS's have greatly improved safety where they are used for pillar line support. We studied the application of MRS's at 20 mines throughout the Eastern United States. Conclusions regarding the most effective section layouts, cut sequences, and support placements are reported. Field and laboratory tests of MRS's are also described.

Jan 1, 1997

To cool hot working environments in deep mines more efficiently, while substantially reducing the maintenance required by presently used cooling coil heat exchangers. Approach A mine's chilled water supply cools fresh air enroute to hot working areas, in an improved, direct-mixing heat exchanger. How It Works Warm, fresh ventilation air traveling through the mine's ventilation tubing enters the lower portion of the cooler heat exchanger through a large round opening designed to accept the ventilation duct. This air flow is turned upward and evenly distributed by egg-crate lattice and pair guide vans at the bottom of the cooler. On the diagram, warm air enters at the bottom left. As the air moves upward through the cooler, it passes through a plastic or wire mesh pad which is arranged so that it offers the most resistance to upward airflow immediately above the cooler inlet: this more or less equalizes the upward air flow along the length of the cooler. The air next moves through the cold water sprays, and then through a wire-mesh demister pad before exiting from the cooler at the top right. Cooling of the air is accomplished in several stages. As the incoming air passes through the lower plastic or wire mesh pad, it is exposed to water flowing downward through the pad to the water sump. This is water that has fallen from the sprays or dripped from the upper wire-mesh mist eliminator. This water is slightly warmer than the spray water since it has already done some cooling,

Jan 1, 1981

Provide an accurate, reliable means for determining when a sealed mine or mine section can be safely reopened after a fire. Approach The Bureau of Mines performed a research investigation that resulted in the development of a mathematical formula for deriving a quantity, called RATIO, which can be used to define when a sealed mine or mine section has returned to safe recovery conditions after a fire. Research Results There were two major results from this Bureau research. Over a period of several years, the Bureau of Mines conducted six experiments at its Bruceton Experimental Mine in Pennsylvania. The experiments involved sealing the mine after several tons of piled coal had been allowed to burn continuously for 2 to 3 days. Although gas data obtained during the experiments revealed nothing significant, measured smoke particle levels were found to correlate with the stages of combustion and temperatures of the smoldering coal pile. Moreover, it was found that no smoke particles are produced when high-temperature smoldering exists deep within the mass of the coal pile since the smoke particles are filtered by the coal surrounding the hot region. Smoke is emitted into the mine atmosphere only if combustion is occurring near exposed surfaces. As suggested by these findings, any decision to recover a sealed mine area based primarily upon the absence of smoke particles is not a wise derision.

Jan 1, 1988

By M. Kanefsky, A. Q. K. Rajput

Two channel polarity coincidence and polarity difference statistics are analyzed. The signal, common to both channels, consists of sinusoidal bursts where the exact frequency of the signal is nearly known, but other parameters such as amplitude, phase, and pulse starting time are unknown. The noise inputs are dependent, narrow band, Markov processes. It is shown that the performance depends not only on the signal uncertainties but on the precise shape of the cross-correlation functions between the noise inputs. By using two polarity difference statistics in addition to the polarity coincidence statistic, it is shown that the decrease in performance, as well as the cost of hard limiting due to correlated inputs, can be made small.

Jan 11, 1981

By H. E. Powell

A series of alkyl-dithiocarbamic acid amine salts was prepared and tested as collector for slimed lead minerals contained in the waste material from a commercial lead ore concentrator. The reagents, members of a homologous series differing only in the number of alkyl radicals in their structure, were prepared by reacting stoichiometric amounts of primary amines and carbon disulfide in a cold alcohol solution. Subsequent purification was by recrystallization from absolute ethyl alcohol solution. Evaluation was through froth flotation of a mill tailing containing 0.2 percent lead. Results show that maximum recovery (38 percent) was obtained with the reagent containing 8 alkyl radicals, but that maximum rougher concentrate grade (4.8 percent) was obtained with the reagents of intermediate number of radicals.

Jan 1, 1962

To develop a reliable, remotely-controlled, mobile roof support to eliminate the need to set posts, cribs, or props while extracting coal pillars. Approach The primary danger during pillar extraction is premature caving of the mine roof. The roof must cave predictably and dependably to ensure the safety of miners. Support during retreat mining is usually obtained by setting posts, cribs, props, roof bolts, or a combination of these devices. These are set manually by miners in the working area. To help minimize the danger to mine workers and to equipment posed by premature falls, the Bureau of Mines developed the mobile roof support (MRS) system to secure the roof during pillar extraction. How It Works The Mobile Roof Support (MRS) is eight-feet-wide, ten-feet-long and five-feet-high, with twelve inches of ground clearance. It is ruggedly built and exerts less than 20 psi ground pressure. The MRS is powered by a 40-hp, 460-v AC permissible motor. The reversible, variable tram speed is 80 ft/min on a 20-percent grade. It is tire-mounted, has a trailing cable, and is remotely controlled either by a radio or a tether communication cable. The machine carries four 50-ton jacks which serve as props for working heights from seven to fifteen feet. Two jacks are chassis-mounted and two are on swing arms. Each jack has a cap which distributes the roof load to three paints. The swing jacks form a breaker row to stop falling roof and prevent caving Into the work area. One jack has a visual load indicator and a second is wired to the machine lighting system. Blinking lights indicate when the preset loading is being exceeded. In the case of excessive loads, an ability to remotely jettison either or both swing jacks has been incorporated into the system to permit removal of the MRS while the roof is still supported.

Jan 1, 1985

By William P. Diamond

A 3-inch pilot hole was directionally drilled to intercept the Freeport coalbed horizon horizontally at Mather, Pa., as part of a Bureau of Mines degasification project. The original concept was to continue the horizontal drilling into the coalbed, after the initial intercept, with a total of three horizontal holes eventually being completed. However, the erratic thickness (0.0 to 4.3 feet) of the Freeport coalbed at Mather was not sufficient to support the horizontal drilling degasification technique, and the site was abandoned after six attempts to locate adequate continuous coal thicknesses. The drilling of coreholes in the immediate vicinity of proposed well paths to evaluate coal thickness is essential prior to future slant hole operations. Although mechanical failures of the new directional drilling equipment, mud pump and rig breakdowns, directional control problems, and exploratory horizontal drilling in the Freeport horizon more than doubled the anticipated cost of the pilot hole, continuing improvements in directional drilling equipment and techniques should significantly reduce the time and costs of future drilling operations.

Jan 1, 1977

By Abrasive Materials

Table 1.-Salient abrasive statistics in the United States [ ]

Jan 1, 1967

By Walter W. Fisher

A kinetic investigation of copper cementation in a revolving drum was undertaken by the Bureau of Mines to explore the effects of a porous copper deposit attached to the iron surface and a fluidized slurry of copper particles surrounding the iron precipitant. The rate of cementation was found to be significantly enhanced by the increased cathodic areas provided by a porous copper deposit or the presence of a fluidized bed of copper particles contacting the iron precipitant. The cementation rate was found to be retarded by increased ionic strength, low pH, and the presence of oxygen. The cementation reaction was first order with respect to precipitant surface area. Copper cementation on iron is visualized to occur by two basic mechanisms. Precipitation may occur through a series of shorted electrochemical cells, whereby cupric ion precipitates on a growing cathodic copper deposit, or, deposition may occur via a fluidized cathode of copper particles contacting the ion precipitant.

Jan 1, 1976