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By Donald R. Corson

The effects of adding varying amounts of type I portland cement to hydraulic backfill are described. Six different fill materials, each with three cement contents, were tested to determine which fill properties have the most significant effect on cemented strength. Two strength prediction equations, based on the physical and mineralogical properties of the fills, were formulated, and these accounted for 96 and 99 percent of the variability of the data. Results of both unconfined compression and triaxial tests of cemented fills are given, and the effects of moist curing and fill densification on the 7-day strength are discussed. Permeability test data are given, and the decreased permeability due to cement content and curing time is shown graphically. A discussion of the limited evaluation of other potential stabilization additives (expansive cement, fly ash, sodium silicate, gypsum, and asphalt) is included in an appendix.

Jan 1, 1970

By J. Mitchell Linnet

Bureau of Mines personnel examined mines, prospects, and mineralized areas to determine the mineral resources and potential of deposits in the Bucks Lake and Chips Creek RARE II areas in Plumas and Butte Counties, California. These areas lie along the west slope of the Sierra Nevada on opposite sides of the North Fork Feather River and encompass an area of 62,800 acres (25,400 ha). Metasedimentary and metavolcanic rocks of the Pennsylvanian Calaveras Formation are intruded by plutons of Mesozoic age. Mineral; of economic iterest are in quartz veins in metasediments close to these plutons; they are principally gold and silver with minor amounts of copper, lead, and zinc minerals. Molybdenum, copper, silver, and tungsten minerals occur in tactite along metasedimentary-granitic rock contacts. In both areas, auriferous Tertiary channel gravels have been extensively developed. Asbestos occurs in ultramafic rocks in both areas, and a limestone deposit was explored in the Chips Creek area. Gold is the principal economic mineral in the Bucks Lake RARE II area. The Shenandoah Mine (fig. 1, no. 19) contains 7,500 tons (6,800 t) of indicated and inferred subeconomic gold resources in sulfide-bearing, silicified metamorphic rocks of the Calaveras Formation (table 1). Similar rocks have yielded gold at the Edman and Megowen Mines, adjacent to the area. A high potential exists for additional lode resources in the area around the Shenandoah Mine. Callahan Mining Corporation personnel believe a multi-million ton disseminated gold deposit underlies the property.

Jan 1, 1983

By H. M. Cooper

Many analysts have had difficulty in obtaining accurate and consistent determinations of the volatile matter in low-temperature coke when the usual standard method for coal was followed. The tendency is toward too-high results, due to mechanical losses which are extremely difficult to avoid or control. With cokes there also may be an error due to excessive oxidation of the fixed carbon. Much of the earlier experimental work on the volatile-matter determination in coal, such as that of Parr,5 Fieldner and Davis,6 and others, 7 has been on the effect of time, temperatures, shape and size of crucibles, method of applying heat, and type of furnace, all of which data has evolved the present A.S. T. M.8 standard method for volatile matter in coal and coke. It is not the purpose of this investigation to deal directly with the above phases of the procedure, but rather to study some of the factors affecting she results in those types of fuel which give erroneous results due to mechanical losses.

Jan 1, 1932

By S. H. Ash

For several years considerable activity has been devoted to economic and social factors affecting California metal-mining operations as they relate to accidents and their cost. The reason for this intense interest is that accidents cost this industry annually over $1100,000 in industrial insurance premiums for mines insured by insurance carriers only; during 1924-32, inclusive, they amounted to $3,616,9115. There are several reasons for this high cost, the most important of w rich are the consistently .high frequency and severity rates of injuries occurring in the industry. Coordination of effort, appreciation of a mutual problem, and widespread education are essential if accidents and their cost are to be reduced.

Jan 1, 1935

By Noel N. Moebs

The U.S. Bureau of Mines is conducting research on many topics relating to the mineral resources of the United States. This is done to ensure an adequate supply of minerals essential to a viable domestic industry and a sound economy. The United States is almost totally dependent on foreign supplies for a number of minerals such as chromium, niobium, tantalum, and manganese for which there is no available substitute, while many other minerals such as titanium are abundantly distributed throughout the earth but seldom occur in adequate concentrations or useful forms. This report describes an example of a small but high-grade occurrence of titanium are in Nelson County, VA. This occurrence could be exploited under favorable economic conditions with new mining technology such as borehole slurry mining. The report demonstrates that the dikes at titanium ore, a mixture of ilmenite and apatite locally termed nelsonite, can be detected and traced along strike using magnetometer traverses. This information will aid in the selection of appropriate slurry borehole mining test sites in the area.

Jan 1, 1993

By Joseph T. Singewald

The term "titaniferous magnetite" is used to designate those magnetic ores of iron that carry more than 2 or 3 per cent of titanium. Large and easily workable deposits of these ores occur in different parts of the world, and have attracted attention for many years. Under present furnace practice, however, the smelting of these ores is both difficult and expensive, and for that reason they are not accepted by furnaces, so that the deposits are practically worthless. The problem of finding a feasible method of utilizing these ores has naturally been attractive, and numerous attempts have been made to solve it. Experiments to that end embrace two lines of investigation. The one that has been the more frequently tried is the elimination of the titanium from the ores, so as to make possible their smelting in the usual way. The other is the devising of a method of smelting by which titaniferous ores may be reduced as economically as are non-titaniferous ores. The former method involves a physical process, the latter a chemical process.

Jan 1, 1913

Determine the advantages and operational limitations of water-let-assisted cutting used with mining equipment. Approach The Bureau of Mines con-ducted a research study to evaluate water-Jet-assisted cutting both in the laboratory and in underground mines. Earlier research on water-jet-assist was limited to laboratory studies where bit speeds and penetration depths were very low and large cutting force reductions were reported. For the past years, research by the Bureau of Mines and others has been concerned with the application of water-jet-assisted cutting under more realistic mining conditions. Study Results Water-jet-assisted cutting employs a mechanical cut-ting bit combined with a moderate to high-pressure water jet directed just in front of the bit tip to assist in the cutting process. Recent Bureau findings show that the addition of the water jet to the cutting bit can improve cutting in harder materials, significantly reduce respirable dust and bit wear, and increase product size. Some of these findings are presented as follows.

Jan 1, 1987

By Richard L. Ash

Introduction The blasting capabilities of commercial explosives are often rated according to their loading densities and detonation velocities. Both the density and velocity are relatively easily measured, the values of which can be used for determining the approximate detonation pressure developed by an explosive during any given set of blasting conditions (1-5). Knowledge of the actual rate of detonation attained at all points along a charger's length also is considered to give a good indication of how well the explosive is functioning. Many factors affect the density and velocity and have been thoroughly discussed by various authors (4, 6-12). For recording velocities several methods are available, but the resistance-wire, or probe, continuously recording technique has the distinct advantage of providing a record of the complete progress of an explosive reaction from the time it first initiates. Figure 1 is a copy of a typical record obtained by the procedure with certain significant information indicated. The theory and applications of the method are extensively covered in the literature so need not be reviewed for this report (13-18). Only the specific equipment and procedure employed for this investigation are presented.

Jan 1, 1973

By Mandeep Singh

The smelting of lead ores has been carried out in southeast Missouri for centuries, and modern smelting practices have generated a variety of waste products. Lead blast furnace slag is one such product, which typically contains 10% zinc, 25% iron and 2% lead. This slag has often been stockpiled on the producing smelter site and accumulations have now reached several million tonnes. It is possible that in the near future these slags will be classified by the federal Environmental Protection Agency as hazardous, and therefore there is considerable interest in possible treatment processes to render the slags non-hazardous by removing the offending metallic elements. To ensure that the overall slag processing costs are kept to a minimum, it is imperative that lead and zinc be recovered in a form suitable for sale or further processing. There are two generic routes for processing blast furnace slags and they involve hydro-metallurgical or pyrometallurgical techniques. With hydrometallurgy, the slags would be leached directly and the metal values recovered from purified leach solution(s) by electrowinning. One problem with processes of this type is that the zinc and lead grades of the slags are low and the iron content is high, and thus the economics of metal production are often not favorable. For pyrometallurgical processing (1), it has been shown that the slags can be fumed to produce an oxide dust containing all the lead and zinc, and representing only a fraction of the weight of the initial slag. The oxide dust may then be processed hydrometallurgical to recover zinc and lead.

Jan 1, 1992

By Wilbur I. Duvall

This report presents experimental data on crater formation in four rock types. From an analysis of these data a general theory of rock breakage by explosives is deduced. This theory accounts for most of the rock breakage and other phenomena that occur when a concentrated charge is detonated in a drill hole near a free surface. From instrumented crater tests and high-speed motion pictures of the explosions, various experimental checks on the deduced theory of rock breakage are made. The general mechanism of rock breakage by explosives as described in this report is outlined briefly below. The detonation of the explosive charge creates a high gas pressure in the charge hole, which in turn generates a compressive strain pulse in the surrounding rock. This compressive strain pulse travels outward in all directions from the charge hole. Near the charge hole the amplitude of this strain pulse is sufficient to cause crushing of the rock. However, as the strain pulse travels outward its amplitude decays rapidly until no further crushing of the rock is possible. The compressive strain pulse continues to travel outward until it is reflected by a free surface. Upon reflection the compressive strain pulse becomes a tensile strain pulse. As the strength of rock in tension is much less than in compression, the reflected tensile strain pulse is able to break the rock in tension, progressing from the free surface back toward the shot point. In other words, the rock is pulled apart, not pushed apart.

Jan 1, 1957

Phase I of U.S. Bureau of Mines contract H01220S3, "Improved Sensors and Fire Control Systems for Mining Equipment, II was an investigative effort involving study of the fire problem and preliminary design of a fire protection system. Overall contract objectives included three basic efforts: * Identify problems * Develop a design * Demonstrate a system The first two efforts were conducted during the period June through November, 1972. Phase II will involve testing of system components; construction and testing of a mockup; and demonstration of the system on a truck to prove its effectiveness under actual operational and environmental conditions.

Jan 1, 1972

By Anthony E. Szczuka

The purpose of this design note is to document the data that has been received from manufacturers, coal companies, training centers, government agencies, etc., that pertains to the completion of the Concept Feasibility Study For Training Equipment Designed to Improve Coal Productivity. Revision A documents additional data that has been received. ACKNOWLEDGEMENTS We wish to express our appreciation to the companies, mines, government agencies, unions, and contractor agencies listed herein that furnished the documented data. In most cases, it was furnished willingly and free of charge. In the few cases where the data was purchased, MDEC IRAD funds were used.

Jan 1, 1976

By Ivor Hawkes

This report describes the results of a study to evaluate new design concepts for percussive rock drills that will result in quieter machines. It is shown that by incorporating such features as an efficient muffler, a plenum chamber integral with the machine body, and shroud tubes around the drill rods, etc., noise levels are reduced from about 114 dBA to about 95 dBA with very little change in drilling performance.

Jan 1, 1977

By Yoginder P. Chugh

This study has appraised available deeper soil loosening equipment in the 1-4 ft. depth range, in the U.S. and abroad which has potential for Illinois prime farm-land reclamation. The appraisal was based on written and/or oral contacts with equipment manufacturers, reclamation experts, and visiting with selected equipment manufacturers. The results indicate that several manufacturers in the U.S., West Germany, and England market static and vibratory deeper soil loosening equipment which may have potential for application in Illinois. The pertinent information concerning each equipment with potential is presented in this report.

Jan 1, 1983

By Jon G. Bredeson

A survey of electromagnetic noise reports was performed and a summary of the results are given. Industrial concerns were surveyed for techniques to minimize the effects of electromagnetic noise and are presented. The common types of communication links used in mines today are presented. A mathematical development was presented which determines the probability of bit errors versus distance for various types of communication links designed for in mine use. The probability of undetected errors for the protocols of the communication links is given together with burst error detection.

Jan 1, 1981

By William C. Cooley

A technical and economic study was made of the feasibility of establishing an underground hydraulic coal mine in the Wilkeson-Carbonado coal field approximately 25 miles southeast of Tacoma, Washington. The deposit contains reserves of more than 200 million tons of generally high quality metallurgical coal. It is located in nine seams of minable thickness in a complex, folded and tectonically disturbed set of anticlines and synclines. Typical dip angles are up to 60°, with minable seam thicknesses of 6 to 17 feet. A mine plan was made for a 2 million TPY mine (clean) using two shafts to access the deposit to a depth of 2500 ft. The mining method uses monitor jets to break coal by sublevel retreat mining, fluming to a sump and pumping the minus 0.25 inch coal to the surface and to a preparation plant. The plus 0.25 inch coal is hoisted by skip. Cleaned met coal would be shipped by rail for export. A middlings product would be sold as thermal coal. Assuming a coal price of $48 per short ton (FOB the mine) for the met coal and $35 for the middlings, the return on investment is estimated at 20% after taxes. The many uncertainties about the geological conditions and the specific mine design parameters make the economic analysis and conclusions somewhat tentative. A second mine could also be developed in the eastern section of the reserves to produce 1 million TPY of clean coal and is expected to have similar economics. Recommendations are made for a Test Mine and a Pilot Mine leading to a production mine.

Jan 1, 1983

By Lon A. Williams

This report, authorized under Contract Number H0220065, Amendment Number Six, documents the results of an investigation of lighting system modifications and designs for working place illumination in high and low coal entries of underground coal mines. The portable and machine mounted system designs, both modified and prototype, represent a continuation of work performed under Contract Number H0111403, Amendment Number One. See the Final Technical Report dated May 26, 1972 for detailed information concerning this prior Contract. All modified and prototype systems met the performance requirements of Bureau of Mines Specification 2G, as proved by test. In addition, the systems met the requirement for illumination, as specified in the Contract and in the proposed standards which were generated in response to Public Law 91-173.

Jan 1, 1976

By H. E. Powell

A laboratory investigation was conducted by the Bureau of Mines to study the magnetic characteristics and to measure the magnetic susceptibility of the mineral siderite. All susceptibility measurements were made by the method of Gouy on powdered samples and at room temperature. Specific susceptibilities of samples from 15 different locations, domestic and foreign, were determined. Values ranged from 66 to 103 (10-6) cgs electromagnetic units. The relation of susceptibility to mineral composition is discussed in this report. The specific susceptibilities of 76 minerals are tabulated in an appendix.

Jan 1, 1963

By Loren R. Anderson

Traditionally, an evaluation of the safety of slopes has been based on computing a safety factor against failure. In computing the safety factor, the geometry of the slope, the soil parameters and the pore pressures are treated as deterministic quantities even though they are known to be random variables. A pseudo-three-dimensional probabilistic slope stability model has been developed that treats shear strength as a random variable. The model uses the probability of a slope failure as an assessment of slope reliability. The model can accommodate zoned embankments of soil in which the strength is described by the Mohr-Coulomb strength envelope. Autocorrelation functions are used to describe the spatial correlation of the strength parameters, c and tan ø. Model error can also be included in the analysis. The model has been applied to an existing tailings dam and to several hypothetical examples. These examples are presented to illustrate the influence of the choice of the soil strength variability parameters on the probability of failure. The results show that the critical failure surface based on the minimum safety factor is not necessarily the failure surface that will yield the maximum probability of failure. The analysis of the tailings dam shows that variance reduction can be large and that the model error is the dominant source of uncertainty for the embankment analyzed.

Jan 1, 1982

By Alvin Kaufman

To aid industry and Government in planning water developments the Bureau of Mines in 1963 canvassed mineral producers to determine water use in 1962. Water use by the mineral industry comprises only 2 percent of the water withdrawn by industry as a whole. The major water-using mineral industries are natural gas processing, phosphate rock, sand and gravel, and iron ore. Analysis indicated the following conclusions: 1. Total water use and new water intake is dependent on the quantity of material processed and the process water requirements of the particular industry or commodity. 2. Recirculation is dependent on the processing requirements of a particular commodity, the manner in which the water is used, cooling and condensing requirements in certain large industries, the quality of new water intake, and the need to treat new and discharged water. 3. Consumed water is dependent on the quantity of water recirculated, the temperature and humidity in the area, and the proportion of water used for cooling and condensing. 4. A threefold increase in water use by the mineral industry by 1985 is forecast

Jan 1, 1966