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By Steven V. Crum, Willard E. Pierce

Concern has been raised about the adequacy of current regulatory guidelines designed to protect homes from unwanted blast damage due to low frequency ground vibrations; in particular those with predominant frequencies below 6 Hz. This report summarizes and updates the preliminary results of a continuing Bureau of Mines investigation which will be completed later in 1995. Four structures at four different surface coal mines have been studied by examining their response to ground vibrations created from overburden blasting. House response to ground vibrations with dominant frequencies down to about 3 Hz were recorded. Many of the blasts produced ground vibrations with peak amplitudes above expected crack-producing thresholds. Response motions were compared to those predicted by theoretical single degree of-freedom response models.

Jan 1, 1995

By Hughes A

Nchanga Division of ZCCM has installed and operated a trolley assist system on part of their truck fleet for some three years. This paper examines how the system came to be chosen and how the many features of construction and operation were dealt with. The economics and productivity of the system are presented as are the personnel aspects of acceptance and training. Zambia Consolidated Copper Mines is a state controlled copper mining company formed by the amalgamation of the former Nchanga Consolidated Copper Mines and Roan Copper Mines. The company operates seven copper mines the largest producer being the Nchanga division, which is scheduled to produce some forty-two percent of Zambia's copper production. The division operates four open pits and an underground mine which produce annually some 192 000 and 96 000 tonnes respectively of copper contained in ore.

Jan 1, 1986

By A. Boltax

H. Herman and M. E. Fine (Northzcesteriz University)—The author is to be complimented on the quality and completeness of his work. Of special interest to us was the exponent of time in the exponential rate equation, n = 0.28 ± 0.03, since it is consistent with results for the early stage of quench-aging in A1-2 at. pct Cu, n = 1/3, first determined in this laboratory."' In that work we attributed the early kinetics to attraction of vacancy - solute atom complexes to the plate-shaped zone due to the strain field about the zone and the lowering in free energy. To our knowledge, Hirano et 1.' were the first to

Jan 1, 1962

By Thomas J. Menner

Jan 1, 1983

By D. H. d Hamly

THE work of Brown and others at Pittsburgh (Brown, Baum, Yant, and Schrenk, 1938)(1) and the success of their light field microprojector (Figure 1), have shown that the microscopy of dust quantitation can be greatly improved. It has been shown that dark-field microprojection of dust spots on konimeter slides is possible (Pullen, 1940), and this paper is a discussion of the new microprojector and a new counting method which is made practical by this instrument. The microscope makes possible the ready determination of the dustiness of mine ventilation air. Reduction of the dust concentration from a dangerous to a safe level involves one or more of the following: reduction of dust production, filtration of the air stream, or dilution with non-dusty air. Each of these raises important engineering problems of time and costs, and trustworthy information on the state of dustiness of the air is required ?both before and after the employment of any method of reduction. Records of this information may be divided into two broad classes concerned with safety: (1) the level of dustiness, and (2) the quantity and kind of dust produced by a machine under a given set of conditions. Though the first requires only one determination for a given time and place, numerous routine records are required to show the continuous safety of the air in an actively producing mine. Though repeated samples are required, highly accurate counts are not needed to show safety or to indicate whether a substantial increase in the non-dusty ventilation air has produced a proportionate decrease in the dustiness of the mixed air. The Devers and Gathercole konimeters have proved satisfactory instruments for this purpose in Ontario.

Jan 1, 1942

MORE than 5000 miners and suppliers descended upon Denver to make the American Mining Congress' four-day metal mining show one of the most extravagant equipment displays ever assembled in one place at one time. The most recent developments in equipment for mining, milling, and processing ore were shown by the 146 exhibitors at Denver's new City Auditorium which covers 57,000 sq ft of floor space. Other displays were placed in the open air opposite the auditorium site. Registration desks were opened Sunday, Sept. 21. A field trip to the Colorado School of Mines at Golden was the featured activity of the day. Official opening of the show took place on Monday, and presided over by Howard I. Young, president of American Zinc, Lead & Smelting Co.; Otto Herres, vice president, Combined Metals Reduction Co.; William J. Coulter, vice president, Climax Molybdenum Co.; Charles B. Stainback, Westinghouse Electric Corp.; and Merrill E. Shoup, president, Golden Cycle Corp. Convention welcoming addresses were delivered by a representative of Mayor James Q. Newton, of Denver, and Gov. Daniel V. Thorton of Colorado. Following the formal opening ceremonies a round table discussion dealt with the "Paley Commission Report" formally called Resources for Freedom. Participating in the panel were: Arthur H. Bunker and George R. Brown, members of the Paley commission; H. I. Young, president of the American Mining Congress; Horace M. Albright, president of U. S. Potash Co.; Evan Just, vice president, Cyprus Mines Corp.; Donald H. McLaughlin, president, Homestake Mining Co.; E. H. Snyder, president Combined Metals Reduction Co.; Simon D. Strauss, vice president, American Smelting & Refining Co.; Sen. H. C. Dworshak (R.-Idaho) ; Ira B. Joralemon, consulting engineer; Jess Larson, De fense Materials Procurement Agency; and Andrew Fletcher, president of St. Joseph Lead Co. The panel discussed the report for six hours, adding a great deal of information to the already voluminous amount which has been gathered concerning it. Three objections to the report frequently mentioned were: 1-the multilateral contract; 2-international buffer stocks; 3-international buffer stocks combined with limited quota arrangements. Points on which the panel commended the report were its recommendations for acceleration of topographic and geologic mapping of the United States and Alaska; recognition of the principle of percentage depletion for metals and minerals; and advocation of removal of the present limitations on the expensing of exploration costs applicable to minerals. Technical sessions were held throughout the four days of the meeting. Included in the program were: Progress in Mechanication; Small Mines; Public Lands; Open Pit Mining; Manpower-Labor Relations; Shaft Sinking; Roof Support; Taxation, Gold, Silver and Monetary Policy; Advances in Mill Practices; Special Conference on Strategic Materials; Uranium Mining-Atomic Energy; Prospecting and Exploration; New Metallurgical Processes; and Rock Breaking. About 45 papers and several panels were presented during technical sessions. Formal and informal social functions consumed the remaining time of the convention. Three locations were needed to handle the huge throng attending the Mining Jamboree Monday evening. The only other sponsored social function took place Thursday evening. A great many informal gatherings, chiefly convivial, were held in manufacturers' courtesy rooms-called wet stopes. Field trips included Cripple Creek, Pueblo, Climax -Leadville-Gilman, Colorado Plateau-Grand

Jan 1, 1952

By Roy E. Peterson

The Bureau of Mines conducted an investigation to produce metallized pellets from domestic iron ore superconcentrates using lignite and subbituminous coal as reductants. Feed materials for the metallizing process consisted of commercially indurated iron oxide pellets and green pellets prepared from upgraded domestic concentrates with graphite or limestone as internal additives. Durability of the green pellets during metallization was investigated in tests conducted in a 7-inch-ID rotating drum furnace. Test results indicated that the major cause of pellet disintegration with the concentrates used was the tumbling action during reduction rather than forces generated within the pellets. In larger scale tests made in a 34-inch-ID by 35-foot-long kiln, the previously indurated pellets were metallized with lignite at 1,030° C with little disintegration. A 96-percent level of metallization was obtained in pellets having an average compressive strength of 420 lb. In subsequent, similar tests using green pellets containing graphite or limestone, pellet disintegration was more severe, with 10 to 40 percent of the feed being lost as dust. The surviving pellets had metallizations ranging from 88.3 to 94.4 percent and compressive strengths ranging from 60 to 68 lb.

Jan 1, 1976

By Jr. Pickering

Commercial quality kaolin deposits occur in fluvial sediments in both central-eastern Georgia and in the eastern Amazon River area of Brazil. Distinctive coarse and fine particle size kaolin deposits are present in both areas; they have many remarkable similarities for mineral deposits occurring at such wide geographic separation. Industrial, mineralogical, crystalline, and chemical resemblance of the coarse and fine kaolin deposits from the two areas will be described in detail. Knowledge of similarities of the Brazilian clays to those which have dominated world production in Georgia will help to develop superior quality kaolin products for world use in paper, paint, plastic, ceramic, and other applications.

Jan 1, 1997

By David J. Dunn

GENERAL NOTES Liner Design for Comminution Liners in crushers and mills are the mechanical link between machine and ore. The way liners transfer energy to media and ore determines to large degree the production rate, liner wear rate, maintenance cost, energy use, and availability of the comminution process. Plant capacity and mineral recovery economics, and return on investment, are thus strongly dependent upon these simple, low cost metal shapes of which so much is demanded. The complexity of dynamic relationships between liner configuration, material properties, ore characteristics, and operating parameters defy simplistic generalization. Rules-of-thumb and axioms of years past fall into disuse almost daily as new analytical methods, assisted by computers and sophisticated control systems, are applied to crushing and grinding processes. Recent literature is well supplied with references citing production benefits that improved liner designs produce. This chapter is intended to review especially promising liner designs and material developments and presents cameo case studies showing the benefits derived from their application to comminution circuits (Tables 1,2,4,5,7). Complete discussions of liner design and wear materials are beyond the scope of this chapter. Norman's comprehensive studies in references (1) and (2) and Mclvor's analyses of mill speed/configuration effects (3) are especially useful reading for designers and operators of crushing and grinding circuits. Changing trends in ore, product value, and costs of wear materials, interest, labor, and energy, make ongoing evolution of liner design equally important for existing mines and for projects still on the drafter's board. Original designs supplied as new equipment must, of necessity, be best estimates. These can usually be improved as operating experience replaces engineering forecasts. Advent of new materials or design concepts such as the Angular Spiral Liners (Korpi (4) ) or Norman's Bimetallic design (2) offer improvement potential that must be evaluated if a given circuit is to be kept competitive versus others making similar products.

Jan 1, 1982

By S. Aram

Product Lifecycle Management (PLM) solutions have been serving as the basis for collaborative product definition, manufacturing, and service management in many industries. They capture and provide access to product and process information and preserve integrity of information throughout the lifecycle of a product. Efficient growth in the role of Building Information Modeling (BIM) can benefit vastly from unifying solutions to acquire, manage and make use of information and processes from various project and enterprise level systems, selectively adapting functionality from PLM systems. However, there are important differences between PLM?s target industries and the Architecture, Engineering, and Construction (AEC) industry characteristics that require modification and tailoring of some aspects of current PLM technology. In this study we examine the fundamental PLM functionalities that create synergy with the BIM-enabled AEC industry. We propose a conceptual model for the information flow and integration between BIM and PLM systems. Finally, we explore the differences between the AEC industry and traditional scope of service for PLM solutions.

Aug 1, 2013

By Grader F. E

A linear motor properly wound can serve as a mechanism for separating paramagnetic sulphide minerals, like pyrrhotite, from other sulphides and associated gangue minerals. The effective- ness of separation depends on the energising current of the separator, the frequency of the a.c. cycle, and the particle size of the minerals. The speed of travel of the minerals over the surface of the separator is also a function of particle size, and appears to be constant. The movement of pyrrhotite, magnetite and iron filings of comparable size fraction (150um +74pm) on the linear motor surface has been observed using a cine camera. An attempt has been made to give a theoretical basis for the movement of the particles by calculating the minimum electrical energy required to move them. Further, the rate of decay of magnetic moment of the particles has been estimated for magnetite and it has been found that sufficient residual magnetism existed in the particles after they had been exposed to the first half of an a.c. cycle for them to have like polarity with the second half of the cycle. The particles are therefore repelled from the motor surface every second half of the cycle. This repulsion due to remanent magnetism is the probable cause of particle movement over the linear meter surf, e.

Jan 1, 1980

By Naj Aziz

Both bolt profile shape and spacing (rib spacing) have been found to influence the bonding capacity of the grouted rock bolt. The bolt surface profile configuration has greater importance to rock bolting in strata reinforcement in mining than the steel rebar used in civil engineering construction. This is because a rock bolt in mining usually is subjected to greater dynamic loading than the steel rebar in civil engineering construction. The increased bonding capacity of a bolt is important when supported ground is either heavily fractured, faulted or the supported ground is of soft formation, typically that of coal measure rocks. Past laboratory studies have identified the bolt profile spacing as of significant relevance to bolt resin rock bonding increase, however, no attempt has been made to determine the optimum spacing between the bolt profiles spacing. Accordingly, a series of laboratory tests were carried out on 22 mm core diameter bolts, commonly used in Australian mines, installed in cylindrical steel sleeve. The study was carried out using both push and pull testing methods. The push test was carried out in 150 mm long sleeves while the pull testing was conducted in 115 mm long sleeves. Profile spacing tested include, 12.5, 25.0, 37.5, and 50 mm lengths. Additional studies undertaken include modelling the profile of the load-displacement data of pull testing. Bolts with a profile spacing of 37.5 mm were found to provide optimum load bearing capacity as compared to other tested profile spacings.

Jan 1, 2009

By Peter O. Wilkinson

Ascot Racecourse in the UK is a major international venue for horseracing. The racecourse is being redeveloped to provide entirely new public facilities. The development includes the construction of a new grandstand. A site investigation was earned out comprising mainly cone penetration testing. The site is underlain by the Bagshot Formation, comprising predominately cohesionless deposits of medium dense becoming dense, silty fine to medium sand, containing occasional layers of clay. Shallow foundations would present uncertainty regarding total and differential movement; hence a piled foundation solution was chosen using a continuous flight auger (CFA) piling system. The possibility that piles may found either directly on or within the influence of cohesive material suggested uncertainty regarding toe resistance. In order to measure shaft friction, an instrumented preliminary test pile was undertaken. The results were compared to published correlations of cone and shaft resistance. This approach resulted in a net saving in terms of pile length which resulted in optimum value engineering and hence a cost saving to the client.

Jan 1, 2006

By J. W. Spretnak, V. Kandarpa, G. W. Powell, R. A. Erickson

Neutron-diffraction pattens were obtained at room temperature from two austenitic manganese steels, oxc wth n carbon content of 1.23 zct PC/ and the olher 0.63 wt pct. Analysis of the data showed that the curOan atols (ions) occupy tile octaheadral site. any of the cavbon is in the tetahedral site, tile concentration is too strzall lo be detecled by tzeulr-on d$facton. AS part of a long-range investigation of eutectoid decomposition, a study of the structure of austenite has been undertaken in order to characterize as best as possible the parent phase in the Fe-C system. Austenite is a solid solution of carbon atoms in fcc iron, the carbon atoms being located in interstitial positions. Of the two kinds of interstitial sites, octahedral (0, +, +) and tetrahedral (4, a, $), in this lattice, the larger octahedral sites are usually considered as the probable position of carbon. The strain energy involved in pytting a neutral carbon atom (covalent di; ameter 1.54)' into a tetrahedral site (diameter 0.56A) is considerably greater than that associated with p2tting carbon into the octahedral site (diameter 1.08A). Dayal and arkeen' observed the migration of carbon in iron under the influence of an electric field indicating tha tye carbon is ionized. pe ionic radius of C'4 is 0.15A and that of C" is 0.29. Consequently, it is conceivable that carbon ions could occupy the tetrahedral sites if one considers only the strain energy. Size considerations alone do not provide a complete explanation for the formation of the interstitial solid solutions, however. because metals such as copper, zinc, and cadmium do not appear to form interstitial solid solutions in spite of their large interstitial sites. Evidence which suggests partial ioni-zation of the carbon in austenite has also been obtained by Speiser, Spretnak, and alor who derived formu- lae relating the observed change in lattice parameter to the effective diameter of the solute atom. Assuming the carbon occupies the octahedral site. they computed the effective diameter of carbon to be 1.33A whereas the covalent diameter is 1.54A. petch5 concluded from powder X-ray diffraction experiments that carbon atoms occupy the octahedral sites. His conclusion was based on the general trend observed in the intensity of the diffraction lines as the carbon content of the austenite was increased. However, the major difficulty associated with application of X-ray diffraction to this particular problem is the relatively poor scattering power of carbon. Williamson and smallman' utilized X-ray diffraction to study the line broadening caused by the strain field about carbon atoms inferrite: these investigators concluded that at least 85 pct of the carbon in ferrite occupies the octahedral (0: 3, B) site rather than the larger

Jan 1, 1967

Draftsman and transitman for coal mine work in Middle West. Salary $125 per month. No. 277. Technical graduate wanted for metallurgical work in experimental laboratory of large New England manufacturing concern. A knowledge of metallography of steel is essential. Practical experience is desirable but not required. No. 305. High-class man to install and take charge of a coal mining property. Must be experienced in handling labor and of good sound judgment. Work will require a man to be on the grounds practically all the time. The work is drift mining and is not gaseous. No. 306. Engineer familiar with the acid treatment and melting of cyanide precipitates; also a competent assayer. Applicant must be able to furnish good references. No. 307. Wanted-practical mining man, foreman, or superintendent for work in middle or southern Atlantic States. Salary $200 per month. No. 308.

Jan 5, 1918

By George Gardner

THE application of wet cleaning processes for the beneficiation of bituminous coal has created in some localities a problem in the recovery and disposal of fine solids in the washery water. The maximum allowable concentration of these solids in the washery circuit that is consistent with satisfactory operation of the cleaning units remains a controversial point. It has, however, been generally recognized for a number of years that some degree of control should be exerted over the concentration of such material. Early methods of control involved intermittent or continuous dis-charge of a portion of the plant slurry into near-by streams or settling ponds, and this persisted even after the adoption of settling tanks or cones. The practice is not always economical, for two reasons: first, because of the waste of coal, and, second, because it is sometimes difficult and expensive to obtain an adequate supply of water. The latter condi-tion often is aggravated by chemical treatment of the make-up water that is necessary to prevent excessive corrosion of plant equipment. The modern approach to this problem has been the adoption of continuous thickening devices. However, because such equipment occupies consid-erable plant space and is somewhat expensive to construct, the practice of loading these thickeners beyond their rated capacity is widespread, there-fore often the performance of such units is not altogether satisfactory. In recent years, European washeries have increased the rate of settling of the fine coal from the slurry by the addition of specially pre-pared starch solutions. These reagents cause flocculation of the solid particles and thereby increase the rate of sedimentation.

Jan 1, 1939

By W. R. Bacon

"The Canam property is in southern British Columbia, 24 miles southeast of Hope. It is reached by 5 miles of road from Mile 26 on the Hope-Princeton Highway.Between the years 1930, when the property was discovered, and I 938 development work by The Consolidated Mining and Smelting Company of Canada, Limited included some open-cuts and six adits totalling 2,700 feet in length. Canam Copper Company Ltd. explored the property intermittently from 1947 to 1955 by diamond drilling and underground work, including driving No. 10 adit. From surface down to the level of No. 10 adit, about 1,250,000 tons of ore has been outlined with an approximate grade of 1.25 per cent copper, 0.8 ounce silver per ton, and 0.01 ounce gold per ton. The ore in the upper part of the deposit also contains a little molybdenum and a little uranium.In June, 1955 Canam Copper Company Ltd. made arrangements to have the property brought into production under the direction of Mogul Mining Corporation Ltd. of Toronto, and a new low level adit has been started.GENERAL GEOLOGYThe principal rocks on the Canam property are chert, cherty argillite, and argillite. They are considered to be Jurassic or Lower Cretaceous in age. Although massive bands to 150 feet in thickness occur, these rocks are in general thinly bedded. Conformable bands of pyrrhotite, a fraction of an inch in thickness, are not uncommon in the well-bedded rocks, and fine tourmaline can be observed in various places.The sediments strike slightly west of north and dip quite steeply, generally eastward; however, sharp divergences from this general attitude are fairly common.Dark grey dioritic sills, in which slender prismatic crystals are conspicuous, are fairly common in the sediments. In general the sills are less than 25 feet in thickness, but a few are as much as 100 feet thick. Under the microscope the sills are seen to consist largely of amphibole (pargasite) and plagioclase (near An50)."

Jan 1, 1949

By Thomas J. Ferree

A Reichert cone concentrator was installed in an aggregate plant circuit to recover the extremely fine "flour gold" known to exist in the deposit. The gold content of the bank-run gravels averages about 0.1 grams per ton (about $1.45 per ton), based upon $14.47/g (345O/ounce) gold. Tine Reichert cone, in conjunction with a conventional shaking table, re- covers in excess of 85% of the gold. A screen analysis of the gold particles shows 44.1% is -i4 microns (-200 mesh) in size. The plant operates with a two-man crew.

Jan 1, 1981

By F. A. Crossley

The key to disagreements between Blackburn's findings and mine is the word equilibrium". My work attempted to define the equilibrium diagram of the titanium-rich end of the Ti-A1 system. It can readily be shown that Blackburn's conclusions are based primarily on the examination of structures substantially removed from equilibrium. The diagram presented in Fig. 16 is properly labeled a "phase diagram". However, it appears that Blackburn either does not understand or does not accept the difference between "phase diagram" and "equilibrium diagram" as defined in the Metals Handbook.17 The conflict lies not in Blackburn's data but in his interpretation of it, and his use of "transformation", "phase diagram", and "equilibrium diagram" as synonymous terms. I share his view that the light microscope is much inferior to the transmission electron microscope for the study of transformations; but this fact does not render the light microscope useless or untrustworthy. The difficulties experienced with the Ti-A1 system have not been due to the limitations of the light microscope, but rather to the extreme sluggishness in achieving equilibrium at temperatures below 1000° C. Were it not for the light microscope employed with polarized light, the twin phase syndrome' might still be unrecognized and, as a consequence, still adding to the confusion of Ti-A1 investigations. (Ref. 1 should read ... Contract No. N161-25952 ... vol. 236.) Other, more sophisticated techniques, including electron transmission, simply confirm the erroneous tentative conclusions drawn from observations of structures due to the twin-phase syndrome. By the standards of most of the investigations of the Ti-A1 systems, seven of the fifteen compositions investigated by Blackburn were seriously contaminated with oxygen. The writer has found that 0.1 wt pct 0 shifts the a + Ti3A1 boundary to 1 at. pct lower A1 content at 700°C. At constant aluminum content, this corresponds to a temperature shift of the boundary of +25°c.18 Blackburn advises that the first group of alloys contained 0.1 to 0.15 wt pct 0, bur he does say whether the analyses were performed on as-received material or on specimens in their final state of heat treatment. This is especially important considering the 20-mil-thick starting materials. If specimens had been annealed in the two-phase a + 6 region it would have provided an indication of the final degree of oxygen contamination since up to about 12 at. pct A1 the boundaries of this region are well-defined for low-oxygen alloys. Blackburn questions the capability of light microscopy in determining phase boundaries in the Ti-A1 system. I submit that the a/a + Ti3A1 boundary in Fig. 1 of Ref. 1 over the composition range from 10 to 18 at. pct A1 was determined by dilatometry and supported by electron diffraction. Specimens of alloys containing 8, 10, 12, and 14 at. pct A1 were aged at 550°C for 1000 hr (under stress of 5000 psi to accelerate the tendency to equilibrium) and then fractured in tension at room temperature. Collodion was applied to the as-fractured (unetched) surface and, when stripped, carried away particles identified by electron diffraction as Ti3A1. Perhaps Blackburn will explain why these electron diffraction data were ignored. At this time, a technique for revealing or indicating

Jan 1, 1969

By Yongping Wu

Roadway deformation and stress migration occur with uncertainty and randomness because of geology, tunneling and mining influence. In order to study the surrounding rock deformation and failure mechanisms in three-dimensional stress state, an air return roadway of Yuanyang Lake mine of Shenhua Ningxia Coal Industry Group Co., Ltd. was chosen as a research object. The three-dimensional model was a designed and completed experiment with a dynamic-static coupling load. The model was loaded by hydraulic cylinder, simulating the in-situ rock stress field and the induced stress field of surrounding rock. The deformation monitoring system of the roadway model was constituted by optical total stations, borehole observation instruments, acoustic emission monitoring, and stress sensors. A wealth of data was obtained through an omni observation of surface displacement, characteristics of stress distribution, and deformation and failure of surrounding model material. By acoustic-optic-electric methods, a real-time testing on physical, mechanical, and damage parameters was realized through the experimental process. The results showed that the data of deformation and failure obtained from the deformation monitoring system of the roadway were authentic, which has great significance for warning and forecasting safety hazards of surrounding rock in coal mines.

Jan 1, 2013