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By M. J. Pazuchanics

This U.S. Bureau of Mines report presents results from an ongoing investigation of the use of adaptive signal discriminating methods to distinguish between cutting coal and cutting mine rock. Bit-cutting forces and tool vibration were measured in the laboratory as a linear-cutting apparatus (LCA) made constant-depth cuts in coal, sandstone, and shale test specimens. A portion of the collected data has been analyzed and some preliminary results are given here. The influence of data bandwidth, data window size, number of signal features, and voting among classifiers on classification performance are noted. Results to date, based on ideal-cutting conditions and simple geologic materials, indicate that of the four classifiers tested there appears to be no single best classifier. Usually, classification accuracy showed slight improvement as the number of features considered for classification increased. The highest classification accuracies were achieved when voting was conducted among classifiers followed by voting among force components.

Jan 1, 1991

A SELF-RESPECTING miner doesn't wash the cuttin's off his hard hat until he quits his job but, on the other hand, he keeps his lamp clean and a "spot" focus on the work at hand; the former habit is a matter of pride and the latter serves for efficient operation. During 1949, the mining engineer got all the "wet raises" for the problem of cutting costs to meet the drop of metal prices and keeping research work up to schedule when strikes tied up his work were his headaches. We note, not without admiration, that he hasn't washed the muck off his hat in token of surrender but, on the contrary, his light shines bright on the job to be done as can be seen in the following pages. Few people have any conception of how much ore and rock have to be mined and how much sorting it takes to cull a pound of copper from a 1 % ore body. These people would be even more startled to picture the problems faced by the engineer in mining and extracting, profitably, .2 oz of gold from a ton of ore as is done at some of our lode mines. Strikers have sometimes kept our researchers from their pilot plants and research laboratories, but the end of the year shows progress in making ore out of taconite and ferruginous sandstone, with a pilot plant in operation at Aurora, Minn., and plans for one near Birmingham. Unfortunately, it looks as though the mining engineer will have to make John Doe secure in mineral resources in spite of himself. Coal for steel, power, and to warm our homes is still economically possible, in spite of Mr. Lewis, through development of mechanized tools for mining. During the year, the use of continuous mining machines has extended, transport systems are being adopted to keep the ore flowing from the face to the tune of 40 tons per man-shift. Experiments in the gasification of coal are going forward in several places and may eventually extend our fuel reserves by the addition of coal seams now too lean for mining. Liquid fuel from coal, oil shale, or natural gas will become economic when oil consumption exceeds our supply; but, at less than 30 cents a ton direct cost for mining oil shale, the engineer is almost making it competitive under present market conditions. In this age of specialists, the mining engineer is still holding his own as a broad-gauge man. As a matter of fact, he is emerging from a stage of semispecialization as a coal, nonmetallics, or metal mining man to the realization that, with mechanization, mining is fundamentally materials handling whether it is fluorspar, coal, or copper ore. From the coal business come rubber-tired mechanical loaders to the iron mines of Birmingham. Shuttle cars are also finding application in the lead mines of the Tri-State. Open-pit methods are universal. Belt conveyors, trucks, Diesels, and mobile, jumbomounted drills are finding application in all types of mining. In preparation, such methods as flotation,- heavy density, electrical, and centrifugal are finding application in coal, nonmetallics, and metals. These concepts have been recognized by the mining engineer who has kept himself informed and has been quick to seize a method, machine, or a process from another operation and, with ingenuity, applied it to his problems. This, our Annual Review issue, is written by mining engineers. In gathering these separate articles under one cover for publication, we think of it as a trrbute to the tireless energy and skill of these men. They get little of the publicity accorded physicists, medical men, labor leaders, or company executives, but they supply raw materials without which industry would die.

Jan 1, 1950

By C. Edward Chamberlain

A Bureau of Mines procedure was developed for the analysis of volatile matter in airborne coal dust-rock dust mixtures prior to, and resulting from, coal mine fires and explosions. Dust in the 10-to 20-mg weight range can be analyzed. Volatile matter is determined by a greatly scaled-down version of the empirical macro-scale method used by the Bureau. The alkaline earth carbonates in the rock dust are dissolved in acid prior to the volatile matter determination of the residue, and the rock dust content is calculated from the analysis of calcium and magnesium by atomic absorption.

Jan 1, 1974

By I Canbulat, J Oh, A Mcquillan, D Payne

This paper presents a new risk assessment tool for coal mine excavated slopes. This new empirical-statistical Slope Stability Assessment Methodology (SSAM) is intended for use by geotechnical engineers at both the design review and operational stages of a mine’s life to categorise the risk of an excavated coal mine slope. A likelihood of failure is determined using a new slope stability classification system for excavated coal mine slopes developed using a database of 119 intact and failed case studies sourced from open cut coal mines in Australia. Consequence of failure is based on slope height and stand-off distance at the toe of the excavated slope. Results are presented in a new risk matrix, with slope risk being divided into low, medium and high categories. The SSAM is put forward as a new risk assessment tool to assess the potential for, and consequence of, excavated coal mine slope failure. Unlike existing classification systems, assumptions about the likely failure mode or mechanism are not required. Instead, the SSAM applies an approach which compares the conditions present within the excavated slope face, with the known past performance of slopes with similar geotechnical and geometrical conditions, to estimate the slope’s propensity for failure. The SSAM is novel in that it considers the depositional history of strata in an excavated slope and how this sequence affects slope stability. It is further novel in that it does not require explicit measurements of intact rock, rock mass and/or defect strength to rapidly calculate a slope’s likelihood of failure and overall risk. Ratings can be determined entirely from visual observations of the excavated slope face. The new SSAM is designed to be used in conjunction with existing slope stability assessment tools. CITATION:Mcquillan, A, Canbulat, I, Payne, D and Oh, J, 2018. New risk assessment method for coal mine excavated slopes, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 473–495 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By Luiz A. Teixeira

A process is described whereby worn, deffective or crystallized photoconductive Se-As layers can be stripped off from aluminium photocopier drums, using hydrogen peroxide solutions in conditions such that the aluminium substrate is preserved from chemical attack. The process allows the stripped drum to be recoated with a new photoconductive layer, and to be put again in use.

Jan 1, 1990

By J. B. Knaebel

I have been asked to discuss the "Development of the Twin Buttes Mine for Production." This property, which is a large low-grade open pit copper mine about 25 miles south of Tucson, Arizona, was recently brought into production by The Anaconda Company under a long-term lease agreement with the Banner Mining Company. Since the scope of this paper is limited to the subject broadly indicated by its title I will confine discussion of historical, environmental and other general matters to a brief summary sufficient, I hope, to establish a background of those conditions which influenced our approach to the technical and economic problems that faced us at Twin Buttes. The paper deals primarily with our studies and activities related to the solution of these problems and with the resulting engineering and business decisions that were taken - decisions which culminated last September in the initial commercial operation of another major open pit copper producer unique and interesting in several respects.

Jan 1, 1970

By John W. Frey

Although there are certain general uniform provisions in the laws ... of the several Provinces of Canada the differences are so great that it is considered advisable to present digests of separate mining laws rather than a digest of Canadian mining law as an entity . This analysis , accordingly , has been divided as follows : Nova Scotia , New Brunswick , Quebec , Ontario , British Columbia , and a group of Provinces under Dominion Law .

Sep 1, 1930

By Xuehui Li, Xinshuai Shi, Jun Wang, Jianguo Ning, Shang Yang, Zhaohui Zhang

Pressure relief is an important step in preventing and controlling rock burst disasters. Hydraulic slotting has emerged as a strategy for pressure relief and energy release in roadway surrounding rock. There is no qualitative description for the response relationship between hydraulic slotting parameters and the degree of pressure and energy release in a roadway, which is a scientific problem. In this paper, theoretical analysis, numerical simulation, and on-site industrial practice were comprehensively used. First, a structural model for the pressure relief and energy release of coal by hydraulic slotting in a deep roadway was established, and the pressure relief and energy release principle by hydraulic slotting was revealed. The principles and methods for determining hydraulic slotting parameters in the roadway were proposed. Three evaluation indices for the pressure relief and energy release effect of coal after hydraulic slotting were proposed, namely, the stress ratio of coal, elastic energy density ratio of coal, and displacement rate of the roadway rib. According to the evaluation indices, the degree of pressure relief and energy release was divided into three levels: reverse pressurization, full pressure relief, and transitional pressure relief. Then, a FLAC3D numerical model was constructed, the levels of pressure relief and energy release under different hydraulic slotting parameters were analyzed, and the optimal slotting parameters were determined. Finally, on-site industrial practices were carried out in Panel 7312 of the Xinhe Coal Mine. An effect test showed that the effect of pressure relief and energy release was remarkable after hydraulic slotting was adopted on the roadway surrounding rock, which can effectively reduce the risk of rock bursts. These research results can further improve hydraulic slotting technology systems and provide a theoretical basis and technical reference for the stability control of deep roadway surrounding rock.

Sep 20, 2023

By A N. Kusnanto, D Sims, L Henim, S Crispin, J Hertrijana

The high sulfidation Purnama Au-Ag deposit located on the Indonesian island of Sumatra entered production in mid-2012 following a two-year program of construction and development. Discovered in 1997 following a regional stream sediment geochemical sampling program by the Normandy Anglo Asia joint venture, it is the first and largest deposit in G-Resource’s Martabe Project to enter production and is the centrepiece of a series of six deposits totalling 8.1 Moz Au and 73.8 Moz Ag in Mineral Resources (G-Resources, 2013a).In 2011 investigation into the controls of high-grade mineralisation in isolated parts of the deposit identified a potentially significant mineralisation style which had not been previously recognised or accommodated in the resource model. An extensive investigation of core and logging data followed to confirm the distribution of the somewhat unusual mineralisation style – a sedimentary-like cavity infill of very high-grade auriferous pyrite within the steep hydrothermal breccia feeders to the system. With the bulk of mineralisation located within the adjacent volcanic sequence and sandy-matrix phreatomagmatic breccia surrounding the feeders, the lack of constraint for high-grade intersections in the hydrothermal breccia zones had potential to significantly impact the mine plan in the lower sections of the planned pit through overestimation of local gold grade. Combined with new data emerging from grade control drilling and infill resource drilling in the pit, a program of reinterpretation of the deposit was initiated to update the geological and alteration framework underpinning the resource model. The result has improved the economics of the project and added metal to the Ore Reserve for Purnama.CITATION:Sims, D, Henim, L, Hertrijana, J, Kusnanto, A N and Crispin, S, 2014. Remodelling the Purnama deposit – an interpretation case study from G-Resources Martabe Project, Indonesia, in Proceedings Ninth International Mining Geology Conference 2014 , pp 229–236 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By W. Beres, R. E. Miller, B. Shiari, L. R. Zhao

A dynamic multiscale (MD/FE) method has been used to study dislocation generation and plastic deformation during a nanoindentation process which is physically associated with the generation of heat within the specimen and as a consequence with a temperature rise. Two different techniques are applied to study the temperature effect on the nanoindention process. In the first technique, a global Nose-Hoover thermostat is applied to the entire atomistic region to keep temperature constant during simulation (finite temperature approach). In the second method, the thermostat is applied only on a damping region along the MD/FE interface. Both techniques are able to effectively and efficiently absorb high frequency reflected waves from atomistic/continuum interface. The temperature profile of the atomistic region beneath the indenter is reported and discussed at four different initial substrate temperatures for both techniques. The loaddisplacement (load/unload) curves for different temperature-controlling techniques are compared and discussed. The nucleation and propagation of dislocations in the atomistic region are investigated for both techniques. Correlations between the observed features in the load-displacement curves with the motion and pile-up of dislocations are reported as a function of temperature.

Jan 1, 2006

By C. Jay Hodgson, P. J. MacGeehan

"The gold ore zones of the Campbell and Dickenson mines occur within a km-wide, 2 km-long zone of highly altered and anomalously fissile and deformed volcanic and subvolcanic intrusive rocks, cut by a series of mainly post-deformation mafic and quartz-feldspar porphyry felsic dykes.Three main periods of gold ore-forming hydrothermal activity are recognized. In the first, the mine rocks were extensively altered and gold and arsenic enriched; syn-volcanic auriferous veinlet and low-grade chemical sedimentary ores were deposited in what was a major discharge zone of a submarine hydrothermal system. The chemical sedimentary ores are closely associated spatially and temporally with domal rhyolitic extrusions. Because of its mechanical and chemical properties, this synvolcanic alteration zone became the locus of later deformation, and the site of the generation of auriferous hydrothermal solutions, perhaps by pressure solution processes at depth. These solutions deposited, synchronously with deformation and metamorphism, the second and most economically important type of ore zones in the mine: large foliation-parallel and foliation-oblique banded carbonate- 'chert' Rssure-filling veins.In the third and final mineralizing event, high-grade, pipeshaped zones of siliceous replacement-type mineralization, and quartz-arsenopyrite-gold veins, were superimposed on the previous mineralization types after most of the deformation, but before the emplacement of the late dykes. The source of heat and also possibly the fluids for the third mineralizing period may have been the dyke-forming igneous activity. The textures and mineralogy of the banded carbonate- 'chert' veins suggest a near-surface (<3 km) environment of deposition, but their relationship to the fabric of their host rocks indicates they were emplaced in an environment, presumably at considerable depth (5-10 km?), in which the rocks were undergoing intense penetrative deformation. This anomaly is unresolved."

Jan 1, 1982

By R. V. Lundquist

A method was developed by the Federal Bureau of Mines for evaluating viscosity data from slurries obtained in leaching sinters from the lime soda sinter process for extracting alumina from aluminous silicates. The logarithm of the viscosity was observed to be a linear function with time. The slope of the plotted line provides a means for evaluating viscosity behavior in a lime soda sinter blurry and also a means for comparing gelation characteristics directly with other variables in the lime soda sinter process. This report presents one aspect of a continuing study by the Bureau of Mines on methods for treating siliceous aluminum ores. It is one of the many programs of the Bureau concerned with conservation, development, and use of our domestic minerals resources. Previous investigations of lime soda processes, both by the Bureau4-7/ and industrial concerns, have demonstrated that sintered materials containing CaO, Na2O, A1203, and S102 in various combinations exhibit a tendency to gel or set when mixed with water or other extraction solutions. Gelling prevents satisfactory recovery of alumina and in extreme cases prevents operation of an extraction plant.

Jan 1, 1960

By P J. Willems, B J. Junor

Blackwater Mine is in the central-southern Bowen Basin, immediately south of the township of Blackwater on the Capricorn Highway. The current open cut operation extracts coal from three main seams, designated Top, Middle and Lower, in the Late Permian Rangal Coal Measures cropping out on the eastern flank of the Comet Ridge. Complex geological structures, dominated by E-W normal faults and N-S reverse faults, have significant detrimental effects on coal mining operations. Historical exploration before 2010 involved several types of drilling only to understand structure, coal quality and washability. Hence, although drilling data was combined with limited pit mapping and observation, unknown structures were still often encountered during excavations and led to mining surprises. In 2010 BHP completed 200-line km of closely spaced 2D seismic survey to capture gross and detailed structures followed by fit for purpose structural drilling to confirm major structures in the northern part of the mine. In 2018 a high density 9.2 km2 3D seismic survey was completed in the southern part of the mine. Subsequently, a 17.2 km2 survey was completed in 2020 to cover the northern active mining area. It allowed geoscientists to successfully map previously unknown major faults and seam splits, which could potentially impact the mineability of the area. It is important to note, that faults interpreted using modern high-density 3D data can be interpreted with dramatically higher confidence in the fault dip and azimuth orientation in comparison to the legacy 2D data. Along with targeted drilling, pit mapping and structural interpretation, the outcome adds value to mine planning and operations. This paper outlines recent successful seismic 3D data acquisition and interpretation. In detail, the paper presents case studies on how the data can be incorporated into a structural model to improve geological knowledge, enable geotechnical assessment, and support safe and efficient coal mining in a large and structurally complex mine.

Mar 22, 2022

By B. M. Fisher

A process for making electrolytic copper of high quality from copper flotation concentrates is described. The concentrates are first slurried and then subjected to a high-temperature, high-pressure, oxidation-leaching operation under controlled conditions. The resulting slurry from the oxidation-leaching operation is cooled or flashed to atmospheric pressure and then subjected to a solids-liquid separation. The separated liquor, containing the recovered copper values, is cooled and then fed to an electrolytic deposition operation where metallic copper cathodes of high purity are produced. The spent electrolyte is then subjected to a sulfide treatment to precipitate the residual amounts of copper not deposited in the electrolytic cells. The precipitated copper sulfide is recovered and recycled in the form of a slurry to the initial stages of the process.

Jan 1, 1976

By John Nauman

Liquid ferrous silicates that are related to cop- per slags have been studied as media for the transfer of heat in pyrometallurgical processes. The effective thermal diffusivities have been measured from 1025Oto 1400°C, and values in the range of 0.004 to 0.007 cm2/ sec have been obtained. The heat-transfer characteristics of these slags have been determined by measuring the rise of temperature of a cold nickel sphere immersed in the liquid slag. The sphere is spun about its vertical axis to obtain a well characterized flow of liquid about the sphere. The principal barrier to the transfer of heat from the bulk slag to the metal sphere is a solid shell of slag that forms around the sphere and subsequently melts. It appears that the detailed nature of this shell is important to theheat- transfer process. A mathematical model is used to predict the rate of heating of the sphere, and to evaluate various aspects of the system that can influence the transfer of heat.

Jan 1, 1976

By G. A. Beiswenger

The application of the law of supply and demand to the sale of crude oil is generally conceded, but the motives underlying the buyer&apos;s (refiner&apos;s) demands are not always obvious to the seller (producer). In some cases this obscurity has led to the conclusion that the refiner may be unnecessarily particular when he selects one crude and rejects another. This preference, however, is very largely the reflection of the refiner&apos;s product demands and the quality of the stocks obtainable from the selected crude. The purpose of this paper is to point out critical characteristics of the major classes of refined products and to show how crudes vary in their suitability for such products. With relatively few exceptions, available processing methods and addition agents make it theoretically possible to produce any type of refined product from any crude source, although it may not be economi-cally sound to do so. The widespread application of thermal cracking for converting higher boiling stocks into gasoline is well known. More recently cracking and refining in the presence of catalysts9 have been developed, as well as various processes for polymerizing lighter hydro-carbons into gasolines having desirable characteristics.6 For several years, selective solvents have been applied commercially to refining inferior quality kerosene, Diesel fuel and lubricating oil distillates .3 Improved methods for refining lubricating oils from crude residua,4 formerly suitable only for fuel, are now in use and a number of special solvent processes are available for dewaxing lubricating oils to low pour point.5 These improved refining methods have been developed not only to meet the demand for improved product quality but also to enable the refiner to obtain quality products from crude sources that would not yield such products by the older refining methods. In many cases, the utilization of these modern refining tools necessi-tates an appreciable expenditure for equipment as well as added manufac-turing costs, and their application therefore must be justified economically. Despite the availability of such tools, the added processing costs involved and yields obtainable may render their application entirely impractical. To illustrate this point, inspections of typical cuts from various crudes

Jan 1, 1940

By Albert H. Clough

The West Lynn Canal subarea of the Juneau Mining District (JMD) is defined by Lynn Canal on the east, Davidson Glacier to the north, Icy Strait to the south and the Glacier Bay National Park Boundary to the west (figs. C-l and C-2). This area extends along the main-land west of Juneau (across Lynn Canal) northerly, to approximately 20 miles south of the city of Haines. The only roads in the area are relatively new logging roads at the southern end constructed to support a U.S. Forest Service timber sale. There is also local road access near the community of Excursion Inlet. Access to the remainder of the region is either by boat, aircraft, or &apos;foot. Helicopters provide the only time effective access to all but the coastal parts of the West Lynn Canal subarea. Coastal areas may be reached by small boat or float aircraft. There is an unimproved dirt airstrip just north of the mouth of the Endicott River. This airstrip is suitable for use by light aircraft. The subarea lies within the Tongass National Forest and is managed by the Department of Agriculture, U.S. Forest Service. Approximately two-thirds of the forest lands are open to mineral entry under the current Tongass Land Management plan. The remaining forest lands comprise the Endicott River Wilderness area, which is closed to mineral entry. Private lands within the study area are sparse, with scattered homestead tracts along the coastal regions and in the Excursion Inlet area. Sealaska (Southeast Alaska Regional Native Corporation) also has land selections in the southern Chilkat Range. Tidal and submerged lands are owned by the State of Alaska.

Jan 1, 2012

By Claude P. Heiner

mountain region to M tht Coast points for domestic consumption and for export are shown in Table 11. There is considerable disparity in rates from both Rock Springs, Wyo., and Castle Gate, Utah, to the four coast cities where the slack coal is to be used for purposes other than export. The rate on coal to be exported is the same from either starting point to any of the four coast cities even though there is a difference of as much as 341 miles in the shipping distance. It is interesting to note that the freight rate between Sunnyside, Utah, and Fontana, Calif., on coking coal is $5.05 per ton and that coal up to 8 in. can be moved on this rate if it is suitable for coking. This rate was published late in 1942 on a contemplated annual movement of more than 500,000 tons. There have been decreases in freight rates since 1923 on movements of slack coal from Utah into Seattle and Portland due to pressure on the railroads and to greater. quantity of coal shipped. It is the author,&apos;, opinion that a movement of slack coal in excess of 3 million tons of coal per year from Utah to any point in central California would justify a freight rate equal to that puhlished for Fontana, Calif.. or $5.05 per ton. The movement of 3 1/2 million tons of coal per year on the basis of 240 mine working days per year would require that 14,600 tons be handled each mine working day. If it is assumed that shipments could be arranged for a 6-day week, the average railway movement would he 11,200 tons, or approximately 3 trains containing fifty-five 70-ton coal cars per day. Such movements of coal would require railroad equipment represented by the investment amounts stated in Table 12 and entail the services of 250 men. Table 12 ... Railroad Equipment and Investment Required To Move 11,200 Tons of Coal a Day from Utah to California Railroad Equipment Cost 2800. 70-ton coal cara at $6.000 each $16,800.000 32 locomotives at $310.000 each. 9.920.000 Miscellaneous eauiument:.......... .5;000:000 Total........................ $31,720,000 It therefore appears that, under presently known mining methods, the lowest price at which coal could be sold f.0.b. the mine in amounts of 3 1/2 million tons per year for generation of power in central California would be $4.60. It also appears that the lowest freight rate that could be expecled between intermountain points and the central California area would be $5.05 per ton, making a total cost of coal delivered at a plant site of $9.65 per ton. Conelusions The following are the author&apos;s conclusions: 1. Coal mines in Utah and in the Kemmerer and Rock Springs districts of Wyoming could increase annual production by 6 1/2 million tons per year. 2. Under present conditions coal could probably be delivered to any steam electric plant in central California at a price not to exceed $9.65 per ton. 3. The use of coal at such a price, while higher than the equivalent present price of fuel oil, is entirely feasible. 4. There are adequate railroad facilities for movements of large quantities of coal from the intermountain region to the Rest Coast. 5. In a national emergency it probably would be extremely difficult, if not impossible, to obtain sufficient oil to meet requirements of the greatly expanded West Coast steam electric generatsing capacity. 6. The intermountain region contains ample coal reserves to supply all conceivable demands for West Coast power generation for a number of generations. 7. Increasing demands of labor threaten to lessen, if not eliminate, savings in cost of coal production through the use of new mining machinery. 8. Continuation of experiments in socialism by the Federal Government through construction of hydroelectric generating plants, particularly those unrelated to land-use reclamation, defies justification. Rates under this concept of a governmental function are subsidized through greater taxation of its people. Private capital is available to construct steam plants, or hydro plants where feasible, and should be permitted to continue in order to preserve the principles of our free enterprise system. DISCUSSION (L. C. McCabe and Robert P. Koenig, presiding) C. C;. BALl*—I was asked to lead off the discussion, but it is not with the thought that I might be able to add anything to the paper. The thoroughness with which it was prepared rather forestalls the asking of many questions. Your treatment, Mr. Heiner, is a very valuable contribution. I do want to suggest—that although you have limited your study to this specific question, with certain geographic limitations, many of the things in your paper apply just as well to the eastern coals. I want to agree 100 pct with your final conclusion concerning government-subsidized construction. Id. C. McCabe*—It is certainly worthwhile to take stock occasionally to see where we are going in problems of this nature. I agree with Mr. Heiner that ultimately the only reliable source of fuel that the West Coast has is coal hut the time factor is the difficult element to evaluate. Just before I came here I discussed this subject with N. B. Hinson, Vice President and Executixe Engineer of the Southern California Edison Company, and Chairman of the West Coast Inter-Power Exchange Committee. He has given much thought to utilities&apos; fuel supply and it was very helpful to me in preparing a discussion of the paper to talk with him beforehand. Stock taking and forecasting of future development are essential to the continuing success of any enterprise. Mr. Heiner has called attention to the unprecedented growth of central and southern California and to the increased demands for fuel and power which have accompanied it. He discusses the increased fuel oil and natural gas requirements and the probable limits on the future use of these fuels and of hydroelectric power. In contrast to the calculable limits of these sources of electric energy, the author points to the availability of enormous reserves of coal in the Rocky Mountain States adjacent to the Pacific Coast which can be utilized for power generation. That there will be increased use of coal for power generation in the area under discussion is generally accepted hut it is in the timetable of such development that there is not complete agreement. In a recent report, Mr. Hinson reviewed the future power outlook for the Pacific southwest area. He pointed out that the use of steam plants in connection with water power plants in this region has made the maximum use of hydroelectric energy possible, and that the correct balance between hydro and steam generating plants produces the most economical overall system. Steam plants in the area which had been installed to protect against deficiency in hydro energy in dry years were used to carry war loads. Fortunately, no dry

Jan 1, 1950

By M F. L Gibson

The issue of flyrock is very important in the operation of all mineral extraction sites that use blasting. Unlike the other environmental effects of blasting, ground vibrations and air overpressure, flyrock is (or should be) a rare event, with severe consequences which may include damage to property, injury or fatalities. These physical consequences are often matched by a loss in public confidence in the management of the operation, mistrust and bad press. In this work a deterministic analysis of flyrock was carried out using the equations of a particle in motion with drag. The solutions to these equations were used to reproduce the curves of Lundborg et al (1975) for the relationship between flyrock boulder size and maximum ejection distance. A probabilistic approach based on Monte Carlo simulation was built up with the analytical model using published data together with local case study material. A typical quarry blast situation was modelled and estimates of safe standoff distances were determined using risk assessment techniques.

Jan 1, 2001

By M. Dadvand, G. Kipuros, A. Dadvand

"The ability to codeposit fillers within a nickel matrix has led to the production of a new generation of cermet coatings with properties useful for various applications. Hexagonal boron nitride (hBN) is a ceramic-type particulate matter with thermal conductivity, thermal stability, inertness, and lubricity properties that allow it to be codeposited. In this paper, a method was developed for modifying hBN surfaces to allow them to be uniformly dispersed in water-based solutions such as an electroless nickel plating bath. hBN surface modification improved wear performance of the electroless plated cermet due to enhanced interaction between the particulate and nickel matrix. RÉSUMÉ La capacité à effectuer un dépôt simultané de charges dans une matrice nickel a abouti à la production d’une nouvelle génération de revêtements cermet (une combinaison de céramique et de métal) dotés de propriétés très utiles pour diverses applications. Le nitrure de bore hexagonal (h-BN) est une matière particulaire de type céramique utilisée pour ses excellentes conductivité et stabilité thermiques, son inertie ainsi que son caractère lubrifiant, qui permettent son dépôt simultané. Cet article explore une méthode mise au point pour modifier les surfaces du h-BN de manière à ce qu’elles se répandent uniformément dans des solutions aqueuses telles qu’un bain de dépôt autocatalytique de nickel. La modification des surfaces du h-BN a amélioré la résistance à l’usure du placage autocatalytique du cermet en raison d’une interaction accrue entre la matière particulaire et la matrice nickel.INTRODUCTION Electroless nickel alloy coatings can be used for many applications; however, the need for improved tribological properties such as higher wear resistance and better lubricity has increased interest in incorporating particulates (fillers) into the nickel matrix by codepositing the particulates with nickel during the plating process. The selection of the particulate type depends on the desired properties (Sahoo & Das, 2011; Sudagar, Lian, & Sha, 2013). In terms of tribological applications, electroless nickel-based composites are categorized mainly into lubricating and wear-resistant composite coatings depending on the type of particles incorporated. The electroless nickel-phosphorus (Ni-P) composite coatings are composed of codeposited solid lubricants such as polytetrafluoroethylene (PTFE), graphite, WS2, MoS2, and hexagonal boron nitride (hBN) and, compared to nanocomposite electroless Ni-P coatings, they demonstrate a lower coefficient of friction. On the other hand, the nickel-phosphorus wear-resistant composite coatings are composed of hard particles such as silicon carbide (SiC), aluminum oxide (Al2O3), boron carbide (B4C), silicon nitride (Si3N4), diamond, tungsten carbide (WC), and zirconium oxide (ZrO2) and, compared to nanocomposite electroless Ni-P coatings, they have higher hardness and better wear resistance (Sahoo & Das, 2011; Sudagar et al., 2013; Parucker, Klein, Binder, Ristow, & Binder, 2014; Chakarova, Georgieva, Petrova, Dobreva, & Stoychev, 2016)."

Jan 1, 2018