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Acid soluble calcium is depleted in drainage sediments from hydrothermal alteration centres in the Coromandel Peninsula. The routine analysis of acid-soluble calcium on drainage samples is an economical and effective technique for outlining hydrothermal alteration centres in volcanic terrains.

Jan 1, 1979

By D. E. Pickett, J. A. Roland Faucher

"INTRODUCTIONMineral processing is undergoing growth and change at a rapid rate. The modern flotation process was discovered only in the mid-twenties, and uranium leaching in the mid-fifties. The growth of individual unit equipment size is also a recent development and is perhaps most dramatically illustrated by the increase in size and connected horsepower in grinding mills. It is also apparent in much of the equipment used in mining operations.These technical and mechanical developments have influenced the design of plants but not to the expected degree.Many metallurgists believed until recently that grinding an ore in the absence of steel results in a loEs of selectivity in the flotation. However results reported by Thornton (1), Fahlstrom (2), Canmet (3 & 4) have shown on the contrary better selectivity and improved recovery at a lower operating cost. According to the Aitik (2) plant results, the net difference in cost plus tailing value in favour of the two-stage autogeneous grinding circuit is in the order of 40 cents per ton of ore milled. Even a greater difference was indicated by the results obtained by Canmet on a sample supplied by Mattagami Lake Mines Ltd.Yet how many plants are taking advantage of these findings and how many plants are being converted. How much more improvement of the results would have been obtained if these tests had incorporated optimization of classification efficiency? By nature the mining industry and the mineral processors are conservative, and tend to emphasize the possible penalties for an unsuccessful innovation out of proportion to the potential rewards even for a significant improvement."

Jan 1, 1979

This Bureau of Mines report concerns two subjects important in the application of electric power in mining systems. Electrical transients and their suppression are discussed, and several considerations are explored with regard to the use of explosionproof or other electrical enclosures.

Jan 1, 1979

By P. Lafleur

All indications point to a growing market for thermal coal in Japan as part of the country's current energy policy formulation process. The Ministry of International Trade and Industry forecasts imports of 16 million tons a year in 1985 and 40 million tons in 1990-a twenty-fold and forty-fold increase over the present level. This potential reflects Japan's over-all serious and increasing concern for security of energy supplies and its resultant need to seek alternative sources. Nuclear power will be the main alternative source, but, because it is expected that its development will be slow, imported thermal coal will assume greater importance. Canada, with large resources of all types of coal, could fill a portion of this market. Thermal coal could come from specific thermal coal developments or from metallurgical coal mines, which usually produce a certain amount of coal not amenable to coking, but suitable for power purposes. However, penetration of this Japanese market by Canadian thermal coal will depend on the resolution of a number of problems. On the demand side, siting, environmental aspects, the need for a coal unloading and trans-shipment centre, and the added cost of installing coal-fired stations could be major constraints. Although Canada has ample high-quality resources, any new development tied to the Japanese market will require improvement in prices to cover the high costs associated with transportation, the construction of new mines and the provision of new infrastructure.

Jan 1, 1979

By William J. Karwoski

To improve rock-burst control in deep vein mining, a field demonstration has been carried out by the Bureau of Mines to test a new rock-burst control concept--rock preconditioning in advance of mining. The procedure is to fracture the major rock-burst-prone zone during the development of each level before production mining. This allows initial mining to begin in a preconditioned zone and later mining from the level below to end in a prefractured or preconditioned pillar zone that is relatively burst-free. This full-scale field demonstration was carried out On the 7700 level of the Hecla Mining Co.'s Star-Morning mine. An expected burst-prone zone along the main vein between 7 and 10 crosscuts, some 250 feet long by 40 feet above and below the level, was preconditioned by blasting a fanlike ring of drilled holes from each crosscut. The drill holes, up to 100 feet long and 4 inches in diameter, were loaded with high explosives and shot. About 4,550 feet of drilling and 9,000 pounds of explosives were involved in the effort. Comparison of preshot and postshot data from monitoring instrumentation indicated that the blasting did fracture the rock in the planned zone and did result in an immediate stress decrease and softening of rock. The field data compared favorably with predicted results from a finite-element computer model simulation of the destressing. Based on observations made during mining and on the data from the Hecla rock-burst monitoring system, there is no doubt that this preconditioning in advance of mining demonstration resulted in much-improved rock-burst control during first-floor mining. It was also concluded that preconditioning the vein was more effective than preconditioning the wall rock.

Jan 1, 1979

By Lamont G

The significance of blasthole stemming in determining blasting efficiency has been extensively studied for small diameter holes using gelignite explosives. Recent developments in blasting technology with the use of large diameter holes and low cost blasting agents have not included studies of the effectiveness of different types of stemming materials. A review of previous measurement techniques and the relevance of these earlier results to present stemming practice is presented in this paper. A survey of operating mines in Australia provided information for this analysis. The value of stemming in reducing blast noise and improving blasting efficiency is generally accepted but the use of bulk-loaded explosives in underground operations has resulted in the practice of eliminating the use of stemming material.In surface operations drill cuttings are used for stemming on the basis of availability rather than efficiency in providing resistance to movement. The development of laboratory testing techniques, based on noise level and borehole pressure measurements, to evaluate the relative efficiency of different types of stemming materials is described. The results of an extensive series of tests with ANFO explosive showed similar trends tothose obtained from earlier published results with gelignite type explosives. Conclusive quantitative results on the relative effectiveness of different stemming materials will require minor modifications to the existingequipment. Observations and the results of pressure measurements indicated the presence of shock wave effects which caused the ejection of the top section of the stemming column when using coarsely fragmented material.

Jan 1, 1979

By James Wm. White

Calculation of consistent steady-state mass balances in operating metallurgical plants and pilot plants is of interest for many reasons. In general, enough data can - and should - be collected to overdefine the system, i.e., permit calculation of nonmeasured quantities via more than one path. In such cases, resulting steady-state metallurgical mass balances rarely close due to sampling, analysis and/ or instrument error. Indeed, determination of a valid calculational sequence for complicated process flowsheets with multiple recycle streams can prove quite difficult. Here we present and discuss a method that has proven useful in analysis of numerous grinding circuit flowsheets of varying-degrees of complexity our technique requires only a consistent process flowsheet with appropriate associated data and arbitrary numbering of streams and equipments. Process topology and user data are decoded to yield a set of "search" or base variables and a set of "calculated" variables in solids, water, particle size and splitter parameter space. This procedure greatly speeds subsequent actual mass balance adjustment calculations since perturing certain variables (e.g., a solids value) does not require recalculation of other variables (e.g., the water balance). Finally, internal search and calculated variables are back converted to User units and used in a Sum-of-Squares criterion. Global minimization of this performance functional then yields a consistent mass balance in a least, squares sense. Weighting factors of choice can be used. Examples illustrate application of these methods.

Jan 1, 1979

This Bureau of Mines report describes research on methods of assuring the continued safety of mine electrical power distribution circuits through reliability and quality assessment of the protective devices, innovative inspection techniques for these devices and the circuits themselves, novel applications of trolley line circuit breakers, and computer modeling of distribution systems to determine the proper ratings for cables, power sources, and circuit protective elements. Battery charger safety is included.

Jan 1, 1979

This Bureau of Mines report is devoted to descriptions of investigations pertaining to underground mine trailing cables, their handling, splicing, and the use of couplers.

Jan 1, 1979

By William S. Sanner

A demonstrated reserve base (DRB) of bituminous coal suitable for cokemaking has been estimated based on the latest published information on U.S. coal reserves. Bureau of Mines analyses of raw coalbed samples were used to classify the coals as low-, medium-, and high-volatile bituminous and grade them as premium, marginal, and latent coking coals. Coal rank was used as the basis for identifying coking coals, and ash and sulfur content were used to determine coking coal grade. The demonstrated reserve base of coking coal for the entire United States is 162.67 billion tons. However, only 18.96 billion tons are premium (metallurgical) grade, and between 80 and 99 percent occurs in the Eastern States. The demonstrated reserve base of marginal-grade coking coal is 31.3 billion tons; more than half the marginal reserve base is in the Eastern States, and most of the medium- and low-volatile marginal coals are in the Eastern States. The Eastern and Midwestern States contain most of the latent-grade DRB of 112.4 billion tons; most (106.6 billion tons) is high-volatile coal, and 98 percent of the medium- and low-volatile latent coals occur in the Eastern States. Based on the worst assumption, which assumes that only premium-grade coals are used for cokemaking, the DRB for high-volatile coal would suffice for 127 years, the medium-volatile coal for 80 years, and the low-volatile coal for 83 years.

Jan 1, 1979

By Robert A. Westin

Polychlorinated Biphenyls (PCBs) have been widely used as fire resistant dielectri coolants in electrical equipment used in mining applications, including transformers capacitors, electric motors, and electromagnets. In addition, PCBs have been used in hydraulic fluids and heat transfer fluids, and are present in many oil filled transformers. The Environmental Protection Agency recently banned the manufacture of PCBs and equipment using PCBs, and imposed strict requirements on the continued use and disposal of existing PCB equipment. This manual discusses the EPA requirements, suggest ways to decrease the risks resulting from continued use of PCB equipment, and surveys the non-PCB equipment that is available as replacements for the PCB electrical equipment presently used in mines.

Jan 1, 1979

By J. E. Rourke, O&apos

This report incorporates a review of available dewatering technology and an evaluation of its relevance to surface coal mines in the Interior Province of the United States. Guidelines for the selection, design and construction of dewatering systems are included. On the basis of documented experience, candidate dewatering systems were selected and evaluated with respect to their anticipated impact on the environment and mine operations. Included in the discussion is a summary of laws and regulations which can impact on dewatering operations. Following this discussion, geologic and hydrogeologic conditions within the Interior Province are described and potential dewatering problems at surface coal mines are identified. Model mines are developed which exhibit the most difficult dewatering problems identified, and it is demonstrated how available technology can be utilized to deal with these problems. Dewatering of coarse-grained, high permeability terrace deposits might be economically feasible today. Low permeability, saturated glacial tills or lake deposits appear to be significantly outside present economic feasibility for dewatering.

Jan 1, 1979

The United States is being invaded... by foreign capital: marks, francs, pounds, yen, lire, riyals, you name it: On almost any given day the Wall Street Journal will contain a new report on a department store, newspaper, bank, hotel, agricultural land, supermarket chain, et a1 being bought into by overseas investment. Xenophobic reaction to this revised national condition has begun to set in. Several farming states have and are introducing legislation to monitor foreign land buying. In Congress a mandatory reporting requirement for foreign purchasing is currently under study. In a relatively short period the country has reverted from world leader- ship in overseas acquisition and involvement to become itself one of the prime investment opportunities in existence. Interestingly enough, one of the industries where this changed status has become most apparent and pronounced is within that small/regional/segmented/low value-to-weight bulk commodity enterprise ranked as the backbone of the nation's construction activity. U.S. cement making is not only undergoing internationalization in its ownership, but also in its product, equipment, and engineering expertise.

Jan 1, 1979

By John C. Brower

Bolivia is nor a major gold producer but has produced continuously since pre Inca times. Production reached a peak in 1964 of about 4,000,000 grams and is currently about 1,000,000 grams. Production is mainly from the Tipuani River valley north of La Paz and is derived from Pleistocene basin fill: the Cangalli conglomerate and overlying terraces. Abandoned Pleistocene lake terraces south of La Paz in the Oruro area are another source of gold whose potential have not been realized. In both the Tipuani and Oruro areas, primitive hand methods are the principal means of production, with the exception of a single modern dredge. In spite of a long history of production, probably very little of the gold potential has been mined.

Jan 1, 1979

By A. E. Ketler

This report describes a variety of coal mine lighting projects which were funded by the Bureau of Mines in order to obtain underground lighting experience in support of new lighting requirements for underground coal mines. Low coal and high coal, narrow and wide entries, conventional and continuous mining, ac and dc power, bituminous and anthracite, and machine mounting and area lighting were some of the variables covered in this program. Also evaluated was the OCENCO fluorescent caplamp.

Jan 1, 1979

The Bureau of Mines is responsible for a broad spectrum of programs for meeting the diverse and changing mineral resource needs of the Nation. These programs are managed by the Director and two Deputy Directors, who formulate general policy and program direction from the Washington, D.C., headquarters. A senior advisory staff, consisting of the Chief Staff Officer, Chief Scientist, and Chief Mining Engineer, provides advice and consultation to the Director on a wide range of scientific and technical matters and acts on behalf of the Director to maintain liaisons with other government agencies, mineral industries, and professional societies. Bureau program activities are classified into two major functions: (1) Developing new and improved technology that will make the production and processing of minerals more efficient, safer and more healthful for mineral workers and the public, and more compatible with a quality environment.

Jan 1, 1979

By John W. Sweeney

Florida is usually thought of as a vacation State, not a mining State, yet Florida has been the leading producer of phosphate rock in the United States for 85 consecutive years and in 1978 supplied over 80 percent of the national output and over 30 percent of the world's output. It is estimated that the Central and South Florida phosphates contain 412,800 short tons (374,000 metric tons) of U308, that 115,000 short tons (104,000 metric tons) of U308 will be contained in the wet-process phosphoric" acid procsssed in the United States through the year 2000, and that 54,000 short tons (49,000 metric tons) of U308 will be available from Florida. In 1978, two companies in Florida and one in Louisiana went on-stream recovering uranium oxide from wet-process phosphoric acid and three others started construction of U308 extraction facilities. These six companies will have the capacity to recover 2,137 short tons (1,900 metric tons) of U308 annually in 1980, which will account for about 15 percent of our domestic requirements.

Jan 1, 1979

By Koehler Stout

Many hydraulic backfills are deposited at low density and provide less than optimum support strength to stope walls. This laboratory study shove that fill strength can be considerably increased. Placement methods used to increase the fill strength were the head, vibratory, cementation, double-planed (dblplod), and combinations of these methods. An experimental facility van designed to study the placement cathode and resultant strengths of the fills. Physical property tests made on the fills included laboratory penetration and vane shear plus several supplementary tests, such as grain size distribution and relative density. Test results were compared to fills planed by conventional methods and to those results reported by other investigators. When compared to fills placed by conventional methods, the penetration modulus was increased by 4.3 tines when the uncemented-vibrated-head concept was used and 71 times when the cemented-vibrated-head-dblplod concept was used. Apparently, hydraulically fill strength can be substantially increased. Conceptual mining plans are also included on suggested ways of placing and using high-modulus backfills.

Jan 1, 1979

By Robert A. Harrow

This report documents the results of the development and installation of an illumination system for an underground coal mine Shortwall Mining Section. Also presented are the techniques used for the above ground test and evaluation of the lighting system prior to installation underground which resulted in the issuance of a Statement of Test and Evaluation (STE) from the Mine Safety and Health Administration, Technical Support, Beckley, West Virginia.

Jan 1, 1979

By Ronald W. Stingelin

The geology of the roof of the Pittsburgh coal bed was studied and mapped in nine contiguous counties containing the bulk of the remaining reserves of this coal bed in the northern Appalachian Coal Basin. Drill core records from Belmont and Monroe counties, Ohio, Washington and Greene counties Pennsylvania, and Ohio, Marshall, Wetzel, Monongalia, and Marion counties, West Virginia provided the data for twelve computer generated regional geologic variable maps. Four of these geologic variables (overburden thickness, vertical distance to the rider coal, lithology at the five foot horizon above the roof of the mineable Pittsburgh seam, and the number of lithologic changes within the 30 foot interval above the roof of the mineable Pittsburgh seam) were used to estimate the risk of potential roof falls by a methological scheme developed during this study. A hazard zone risk map was developed showing a generalized regional trend of increasing risk from west to east across the basin. Mapping of individual geologic variables and mapping of hazard risk can be done at any scale. The accuracy of the mapping is primarily dependent on the density of the drill core records. Geologic feature maps and the hazard risk map contained in this report are reduced (1 :500,000 scale) versions of the larger scale (1 :62,500) maps prepared for the Bureau of Mines as map folios.

Jan 1, 1979