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Conventional logging tools such as density, neutron, and acoustic have ranges of investigation of tens of centimeters. The borehole gravimeter, however, has a range up to hundreds of meters. For example, from the center of a cylindrical orebody 0.22 g/cm3 denser than its surroundings, one can detect the boundary of the orebody at a radius as large as five times its height. More complex structures can be investigated with computer programs. We can predict the usefulness of proposed gravity surveys, or decide which suggested structure is most likely to have caused the results of existing surveys.

Jan 1, 1985

By Ignacio Salazar

Somebody sure gave me the wrong title. I can talk much more freely about the impact of the anti-nuclear movement on the DRILLING industry in New Mexico. In a word, it is being "clobbered." It doesn't seem like very long ago that my brothers and I were busy trying to find enough new equipment (and trying to talk bankers into lending us enough money) to keep up with drilling work we could get. Seemed like no matter how hard we worked, and how much money we borrowed, we were always one step behind where we wanted to be. We had so many holes to drill that all our crews were working three shifts a day, and over several states. The nation needed energy, and we were ready to help supply it. Exploration and development drilling jobs were all going full-blast. We had trouble keeping up with them. With luck, we figured we'd be able to get all our equipment out of hock before all the necessary uranium mines were developed.

Jan 1, 1979

By Richard E. Thill

Backfilling of mine voids is used to prevent or control the effects of subsidence on surface structures. The pumped-slurry, blind-backfilling process has been particularly successful for stabilizing ground over abandoned and inaccessible underground coal mines. Using this newer technology, vast quantities of backfill material can be distributed over wide areas in underground openings from a small number of injection boreholes. The rapid and successful development of this backfilling method, however, has outstripped technology for monitoring and controlling backfill placement. Surface or borehole remote sensing methods are needed to determine where fill material is being distributed underground and how effectively the material is packed in the voids. In search for improvements in backfill monitoring and control technology, potential remote geophysical sensing, process monitoring, and tracer methods were evaluated to select candidate systems for monitoring backfill placement under the constraints imposed by the injection process and the surface and subsurface conditions. ' A multiple objective ranking matrix, based on theoretical considerations as well as pragmatic experience with systems working in related or similar conditions, was used to narrow down potential methods to several most-favored candidates. Two of the candidates were field tested under actual operating conditions at a backfilling site in the Wilkes-Barre-Scranton region of northeastern Pennsylvania. Although process and acoustic emission monitoring indicated promise for improving existing backfill monitoring technology, more extensive testing under different conditions at various sites is required to establish the validity and utility of these methods. Results indicate that no single method is adequate in itself for backfill monitoring, and that a successful system will require the Integration of several methodologies.

Jan 1, 1982

By Richard W. Patton

With the advent of the Clean Air Act and the installation of flue gas desulfurization (FGD) equipment (scrubbers) on coal fired power plants, the management of solid wastes has taken on added importance. Aside from the large amounts of fly ash and bottom ash usually generated, large quantities of liquids in the form of scrubber sludge are also produced. These wastes must be disposed of within the constraints of land and water quality regulations. This paper describes the practices adopted by the electric utility industry in denting with this problem, including methods of generation and treatment, quantities and characteristics of the materials, and transportation and disposal practices. The paper also briefly describes final product characteristics and several applications for commercial utilization and land reclamation.

Jan 1, 1983

By P. Legast

Serpentinite minerals are available in large quantities from asbestos mining activity. The granular or fibrous serpentite, at temperatures greater than 700°C, will recrystalize into olivine, forsterite and enstatite. These minerals have been used and studied for decades and are environmentally safe. The thermal process changes the composition and properties of the original mineral. Therefore, the substitution of the original mineral cannot simply be made and the applications for these new synthetic minerals need to be redeveloped. The two original mineral forms allow a wide range of new synthetic raw materials which can be adjusted to specific applications or custom needs.

Jan 1, 1993

By John D. Smith

This paper describes how a knowledge of inherent rock characteristics can aid the mining engineer in his design of a mining method for a massive domelike structure. The paper shows how the pertinent rock characteristics were measured and analyzed and how the data obtained was used for design purposes. This analysis was conducted in 1964 in a producing salt dome, since that time, mine management has tried certain of the recommendations for mine design changes. The results of such changes are presented.

Jan 1, 1968

By John A. Patterson

There are certain data handling techniques used by statisticans that can help one to calculate the size of an orebody and to develop some of the relationships between size, cutoff grade, average grade, mining cost, and profit. Knowing the relationships amongst these factors can help determine the most desirable operating conditions. A statistical technique that we will use is data grouping. This allows us to work with relatively few groups instead of many samples, If we were able to segregate the ore in an orebody into grade groups, add the amounts in each group, and plot the sums as a curve, we would get something like Figure 1. A smooth curve develops when the grade classes are small enough, otherwise a "stair step? histogram results. The area under the curve, being the sum of the tonnages in all of the grade classes, is proportional to the total number of tons in the orebody. If we take the data of a distribution such as Figure 1 and add the tonnages above a specific grade we have in effect a cutoff grade

Jan 1, 1958

By Norman A. Nadel

Those of us who have directed our efforts toward the construction of tunnels have long maintained that tunnel construction is more closely an art than it is a science. We have spent time underground with hard-bitten, tobacco chewing shift bosses and superintendents who have made seat-of-the-pants decisions at the face which have been based upon their long experience underground coupled with uncanny intuition. The courage and skill of these men in the performance of their art is legendary. Without question, they have constituted the backbone of the tunnel construction industry. But just as John Henry, the steel driving man, despite his stout heart and dedication to his task, was supplanted by the steam drill, I fear that our tunnel stiff, at least as we have known him, will become an endangered if not extinct species. The reason for this is clearly that tunnel construction is slowly but inexorably making the transition from being an art into being a science, and more and more its performance is requiring the services of scientists as opposed to artists. The tunneling art has been undergoing change for many years, and yet until recently the changes have not been basic. We have improved the way we do the same old things. For example, John Henry would be flabbergasted if he saw the rock drills we use today. He would not have engaged in the legendary drilling contest with one of our modern drills, He would have simply conceded defeat.

Jan 1, 1970

By Patricia Curtis Petty

Thirty years ago, the appearance of a female mining engineer, geologist or miner in a company, union or mine environment would have been unthought of, unwelcomed and violently opposed. Twenty years ago, the intellectual perception of the news that women were interested in becoming mining engineers, geologists and miners had been accepted by the industry-but no one wanted to be the first to hire one of these exotic creatures. Ten years ago, those who had been most vehemently opposed to the philosophical idea of women working in these areas were faced with competent, productive engineers, geologists and miners-who only incidentally happened to be women-and began hiring them. Historically, of course, one can always find the isolated individual who worked in these areas-the first female graduate of the Colorado School of Mines with a mining engineering degree graduated in 1903-but the concept of woman as professional engineer was very slow in arriving in the United States. The few who worked as miners generally worked in small family enterprises, such as some of the coal mines in both Eastern and Western United States. Others accompanied husbands or sons into wilderness areas searching for gold and other precious metals.

Jan 1, 1984

By Gordon B. French

The Occidental Oil Shale mining and retorting system for the production of shale oil has many advantages over the conventional underground mine and surface retort systems. For example only a portion of the oil shale is mined and transported to the outside, where it blends with the existing shale talus found on most of the slopes in the immediate area. The retorted spent shale is retained underground so that it does not become a surface disposal problem. The process consumes only minor amounts of water which is produced in adequate amounts in the retorting to fulfill all mining operations needs without outside supplies. Noise and dust levels are kept to a minimum with most of the facilities located underground. The exception being the generating stations and facilities as required to monitor air and water qualities, and last but not least, more than four times as much oil is pro¬duced from a given acre than from conventional surface processing. With the increased thicknesses as available on the government monopoly area this number could be increased by a substantial amount.

Jan 1, 1975

By L. G. Wilson

In our comparison of California and Turkish colemanites, we should first place the discussion in context. In order to exclude technical considerations, which are not germane to this paper, we must make the manifest and basic observation that if colemanite were not acceptable for the production of glass products it would not be used, and we would not be interested in this comparison at all. Suffice it to say that the colemanites, being calcium borates, provide a necessary flux in glass manu¬facture, together with the requisite degree of physical strength and chemical durability which can be achieved only by the use in glass of a. flux substanti¬ally free from alkali; so the sodium borates are automatically excluded from the production of textile fibers. Thus we have today under consideration only California colemanite, Turkish cole mite, and, because it provides a degree of competition to both, ABA, or anhy¬drous boric acid, which, although it is a refined intermediate and of much higher cost, it is also of a much higher degree of purity, and its characteristics can easily be modified to produce a desired end product, so we must include it in any consideration of high quality borates. [Calcim Borate Pentahydrate] Colemanite is a [calcium pentahydrate,] with the formula Ca2B6011.5H20. It has a theoretical B203 content of 50.8%.

Jan 1, 1973

By Arthur S. Maynard

There was a tendency several years ago for the average coal producer to more or less sit back satisfied with the big utility and metallurgical mar¬kets with long term contracts, not realizing, or possibly not evaluating correctly the importance of the growing industrial market Even the companies which were producing coal for the industrial market were primarily interested in the larger industrial customer, not fully realizing that a large percent of the industrial coal sold was to plants using less than 15,000 tons per year. As a result, possibly, the greatest inroad made by competitive fuel was made in this group. The situation mentioned previously cannot be blamed entirely on the fact that the coal markets were not evaluated in their proper perspective. Some of the responsibility would have to be due to the situation that existed during the last war' and the period immediately following, when most of the coal was put to markets of higher realization, leaving the relatively small -industrial user-to get his fuel wherever he could. This usually would mean coal from some 'gopher hole" with fluxuating quality and supply. Therefore, it was not uncommon for some industrial customers to go to competitive fuels as soon as equipment and fuel were available. Fortunately, before this situation got completely out of control, the coal producers, realizing the seriousness of the problem, made available, usually through their sales department, combustion engineers and other specialists, to help the industrial user with his problems; The engineers usually found several problems, old equipment, use of incorrect size con¬sist, ash and fusion coals, lack of automation, fly ash and dust problems which increased cost and jeopardized the customer's relations with his employees and the public.

Jan 1, 1959

By J. Harrison Daniel

More stringent dust standards, because of quartz in coal, have become a major compliance problem for the coal industry. Reducing quartz levels has become the major focus of the Bureau of Mines dust control research program. Results to date have identified hath the sources of quartz and prospective control technology. Control techniques are being developed for both room-and-pillar and longwall mining underground operations. Techniques include changes in face ventilation, mining cycle modifications, and better roof bolting dust control.

Jan 1, 1985

By X. Cheng

A series of batch flotation tests was performed on chalcopyrite-quartzite, pyrrhotite-quartzite, and on chalcopyrite-pyrrhotite-quartzite mixtures. Pulp potential measurements in the flotation tests of single sulfide minerals indicated that each sulfide mineral had its own optimum potential range for flotation. When these results were used to select the potential ranges for the separation of the two minerals from their mixture, their flotation responses changed and the selectivity of separation was adversely affected. A possible mechanism involving surface alteration through galvanic interaction is discussed. A method to improve the selectivity of flotation separation was proposed.

Jan 1, 1992

By Wilbur J. Morin

Construction of Flaming Gorge Dam in northeastern Utah necessitated the construction of a new state highway, Utah-260, to provide access to the dam and the town of Dutch John. A 550-foot arch structure was designed to span Cart Creek, about one mile southwest of the dam. The rock exposed at the site is highly fractured quartzitic sandstone with interbedded shale of the Precambrian Uinta Mountain Group. Eight exploratory holes were drilled, four in each abutment area, to determine rock types, the extent of fracturing at depth and rock strength. Drill cores in the west abutment revealed blocks of quartzitic sandstone loosened by the weathering and partial removal of underlying shale beds. The rock in the east abutment area was found to be highly fractured to depths of 70 feet and as far east as 50 feet from the footing locations. Selected core sections were tested for unconfined compressive strength but the values were not considered-representative of the in-situ fractured rock. To prevent movement along or, perpendicular to open fractures, four drilled-in columns were provided at the base of each footing. These extended 50, feet beyond the base of the footing, along the bearing and inclination of the thrust reaction.

Jan 1, 1963

By D. S. Choi

Coal is expected to become an increasingly important source of energy in the future. Coal production has already increased from about 650 million tons in 2975 to about 875 million tons in 1984 (Wilkinson, 1985). The declining trend of labor productivity in the early seventies was a source of concern for Consolidation Coal Company (Consol). To improve productivity, a gradual change from room-and-pillar mining to longwall mining has been taking place within Consol. Consol produces 45 million tons of coal annually with about 70 percent of the production coming from underground mines. Consol introduced longwall mining in the early seventies and currently operates about 20 longwall faces. The longwall faces are in mines in the Appalachian region in the States of West Virginia, Pennsylvania, and Ohio. The successful operation of longwall faces has contributed to a recovery of productivity and to an improvement of mine safety.

Jan 1, 1985

By M. F. Vancas

The San Manuel oxide ore reserve ranges in depth from being exposed on the surface to lying 1000 ft. beneath a conglomerate layer all of which is confined in the subsidence zone of an active sulfide block caving operation. Present day recovery of the oxide copper values is either by open pit mining-dump leaching, or in-situ leaching of the oxide ore using dilute sulfuric acid solutions and solvent extraction/electrowinning processing of the pregnant leach solutions. Future plans are for continuation of leaching with expansion of reserves and increased processing rates. The state of the mining industry and copper in particular has not been good for a number of years. All of the producers that are still operating have made major adjustments in order to remain competitive. Magma Copper Co. is no exception.

Jan 1, 1987

By C. W. Overton

The operations of Bethlehem Copper are situated in the south-central interior of British Colombia at an elevation of 4900 feet above sea level. Main road and rail transportation systems pass through Ashcroft in the Thompson Valley, which is 28 miles by road from the minesite. The operation was the first low-grade open-pit porphyry copper mine in British Colombia. The minerals are chiefly chalcopyrite and bornite, while the rock is principally feldspar and quartz. In the outer fringes of the orebodies sane pyrite is present. Average grade of mill feed is 0.55% copper.

Jan 1, 1973

By Lawrence M. Lenahan

Cleveland's Southwest Interceptor Contracts No. 3 and No. 4 are continuations of Contract No. 1 addressed at the 1987 RETC with geology, equipment, and methods that differ greatly. The two contracts consist of 791 m (4.22 miles) of 3.5 m (11.5 ft) tunnel lined to 2.9 m (9.5 ft), nine access shafts, six drop shafts, and six collection structures. The excavation drive was completed by the use of a 1970 vintage Robbins TBM hybrid for this particular job through the use of both new and old technology. All other excavations were successfully accomplished through drill and blast method in tight residential areas. Concrete lining and connections were completed nine months after holing through.

Jan 1, 1989

By Thomas M. Turner

Open pit mining, always a demanding task, faces two relatively new problems today: 1. Availability of equipment. Moderate to large draglines can take as long as 6 years from date of contract to date of operation. 2. Environmental restrictions. Strip mining in the minds of environmentalists compares unfavorably on the scale of social desirability to the activities of Jack the Ripper and Attila the Hun. Specifically, lowering of the water table to allow strip mining in the dry is being looked upon with increasing disfavor. The modern dredge offers relief in both problem areas. Delivery on a major dredge might run 18-24 months rather than 60; and lowering of the water table is precluded, thus minimizing environmental objections. In addition, a lower first cost and potentially increased efficiency may offer real advantages to the miner who is forced away from his traditional mining methods. This talk is dedicated to acquainting the miner with dredge types, advantages, and limitations.

Jan 1, 1975