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By GEORGE ROBERT DE BEQUE

WHAT is wrong with oil shale? The answer is of interest to the public, to the oil refiner, and to the engineer. Many people have invested in shale land or shale securities, and others would invest if early development of the industry were certain. In the face of increasing demands for oil products, oil refiners are threatened with inability to maintain present output unless the supply of domestic petroleum is supplemented. Development of the oil shale industry would open a new field for engineering services. The object of this paper is to suggest reasons why there is but one shale plant in operation in the United States, and to discuss the probable time when the business will be firmly established in Colorado. As the Colorado deposits are the richest and largest in the world, ample supply of material is assured, consequently, this discussion will be confined principally to technical problems and economic problems affecting shale development.

Jan 1, 1924

By R. F. Mehl, C. S. Barrett, A. G. Guy

INTRODUCTION IN the last few years this laboratory has published a series of papers on the mecha¬nism of age -hardening.14,1,6,11,20 Briefly stated it has been proposed that hardening is caused by lattice strains created by lat¬tice coherency between matrix and precipi¬tate; much experimental evidence has been advanced to support this thesis. The system Cu-Be is an attractive one to study. It is a system that exhibits marked age hardening; it ought to be subject to the type of analysis of structural changes hitherto explored and it is a prominent example of "discontinuous precipitation," which, though studied in other cases, 6,20 remains largely unexplained. This research shows that hardening in the Cu-Be system proceeds essentially as proposed earlier.14 Guinier-Preston zones have been observed to form on the {100) planes of the matrix; no transition lattice was found. Aging and overaging were ob¬served to occur most rapidly in the region of discontinuous precipitation-the grain boundary-apparently accelerated there by strain. The Constitution of the Cu-Be System The Cu-Be constitution diagram is shown in Fig I. The structure of the ? phase was determined by Misch16 as of the caesium-chloride type with a lattice con¬stant of 2.598 Å High temperature X ray photograms of 7.2 pct Be alloy made by Kossolapow and Trapesnikow13 led them to conclude that the structure of the P phase is simply disordered body-centered cubic with [ao] = 2.79 Å at 750°C. Previous Work The initial work on the age-hardening of Cu-Be alloys was that of Masing, Dahl, Holm, and Haase. Their numerous papers were published in book form in 1929, sub¬sequently translated.18 The effects of Be content, solution temperature, aging tem¬perature, and cold work on the hardness developed in these alloys were studied. An initial decrease in the electrical conduc¬tivity was observed when strips of a 2.5 pct Be alloy were aged at temperatures from 200 to 350°C; a wire of the same analysis failed to exhibit this decrease when aged at 350°C. A volume decrease of 0.6 pct oc¬curred during aging at 250°C. Microscopic investigations of quenched and aged alloys disclosed a regularly ori¬ented "striping" (ripples) on the a and on the ß grains. In the case of the ß the cause of the striping was held to be decomposition

Jan 1, 1948

By Gerald Verbeek, Erick Baziw

Downhole Seismic Testing (DST) is an extensively utilized geotechnical tool for site characterization. DST provides low strain (<10-5) in-situ interval shear and compression wave velocity estimates. These velocities are determined by obtaining relative arrival times of source waves as they travel through the stratigraphy and are recorded by one or more vertically offset seismic sensors. The DST arrival times have associated measurements errors and resolution limitations, which become more pronounced as the depth interval of analysis is reduced. Baziw Consulting Engineers (BCE) has developed a new DST analysis technique, the so-called DSTPolyKF algorithm, whereby the arrival times of DST data set are used to define a high order polynomial. The main advantages of this new technique are four-fold: 1) the ability to utilize all arrival time estimates irrespective of measurement errors. 2) the ability to analyze the data with user specified and even small (≤ 0.5m) depth intervals. 3) the ability to apply sophisticated data fusion for significantly more accurate DST interval velocity estimation. 4) the use of polynomial regression accuracy parameters to quantify how well the “best fit” polynomial fits the acquired arrival time data sets. This paper outlines the mathematical details of the best fit polynomial where a Kalman filter formulation is implemented. The performance of the DSTPolyKF algorithm is demonstrated by processing real DST data sets.

Oct 1, 2022

CONTENTS [The Nature of Strain Markings in Alpha Brass (paper by J. E. BURKE and C. S. BARRETT, Met. Tech. Feb. 1948. TP 2327). ......................... 2 X Ray Studies of Twinning and Untwinning in Magnesium Alloys (paper by J. B. HESS and R. L. DIETRICH, Met. Tech. Feb. 1948. TP 2328) ................ 11 ]

Jan 1, 1948

By C. H. Green

. RECENTLY two papers on the structure of eutectics were read before the British Institute of Metals, one by F. L. Brady1 and the other by A. Portevin.2 In the preparation of photomicrographs of laboratory specimens as illustrations for student work, and in connection with various researches; the writer has been working along the same line for some, time and, therefore, was much interested in the results given, especially those of Portevin. He has correlated the information on the subject and has outlined a broad scientific basis for future work along this line. It is largely with the idea-of adding something by way of illustration to the work already done that this paper is written. The eutectic is generally understood to mean the alloy having the lowest melting point of any alloy of the system, and in which the melt becomes supersaturated with reference to the two or more phases which, separate out simultaneously (or alternately). From the surface pattern, the eutectic means; a structure with no primary crystals. It is not always easy to get the exact eutectic composition in making any alloy; in fact, a slight range in composition may be expected and some of the coarser particles may be richer in either of the composing metals. Even when chemical analysis shows the right composition, differences in density of the pure metals may cause segregation, or. supercooling resulting from different crystallizing properties may give a surface pattern the appearance of being on one side of the eutectic point. However, the alloys on either side of the eutectic composition, showing primary crystals of one of the phases and the effect of the pro-eutectic form on the surface pattern of the eutectic make a very interesting study, which is slightly touched upon in this paper. The phases, or microconstituents, of a eutectic may be pure metals (Pb-Sb, Tl-Au), solid solutions (Cd-Zn), a pure metal and a solid solution; (Ag-Sn), or a pure metal or solid solution with an intermetallic compound (Sb-Mg, Sb-Cu, As-Cu, Bi-Te, etc.).

Jan 2, 1925

By A S. Fogliata, L Bengochea, G Mas, J E. Lazarte

The Culampajß auriferous district is located in the northern sector of the eastern edge of the homonymous hill, Catamarca Province, Argentina. Tajo Largo mine is situated in the southern flank of Las Minas gulch at an approximate height of 3.600 m above sea level. In the studied area main outcrops are orthogneiss rocks of Chango Real Formation. The ore mineral is native gold with a lesser amount of pyrite, chalcopyrite, haematite, limonite, malachite, azurite and covellite. These ore mineral assemblages are disseminated in quartz veins filling tension fractures in the host orthogneiss.Several types of inclusions have been recognised, including three phase H2O-CO2liq-CO2vap inclusions, polyphase inclusions with H2O-CO2 and one or more solid phases, and two phase aqueous inclusions. In the three phase H2O-CO2liq-CO2vap inclusions the Tmclath is about 1¦C and the CO2 liquid-vapour homogenisation occurs at 26 - 28¦C, to liquid phase. The homogenisation temperature of H2O-CO2 occurs at 365 - 380¦C in the aqueous phase. This set of data defined a solution with a salinity of 14, 4 wt per cent NaCl equivalent and a density of 0.84 g/cm3. In the two phase aqueous inclusions the melting temperature (Tm) of -5.4¦C and the eutectic point (Te) in -38¦C indicates a salinity of about 7.5 wt per cent NaCl equivalent, with the probable presence of Ca2+. Density of fluid is about 0.83 g/cm3. Homogenisation temperature ranges between 260¦ and 280¦C. The pressure, temperature and salinity of fluids in the polyphase inclusions suggest an early fluid of high density and high salinity. The three-phase fluid inclusions may be the result of an unmixing-phase separation of post magmatic hydrothermal fluid due to pressure decrease along fractures. It is suggested that the deposit was formed during the late magmatic hydrothermal stage genetically linked to granitic rocks and can be comparable with the intrusion-related gold system of Baker (2003).

Jan 1, 2008

By John Kostuik

AT the Sladen-Malartic mine, a number of orebodies have been mined, some by shrinkage and others by open sub-level scopes, from which the ore is handled either through a grizzly system or by mechanical loaders. This paper deals with the comparative costs and relative merits of the two handling arrangements. The facts brought out in this comparison have a bearing on the selection of a proper handling method. The mine is in Fourniere township, northwestern Quebec, about forty miles east of the town of Rouyn. It is served by the Rouyn-Senneterre branch of the Canadian National railways. Two vertical three-compartment shafts give access to the present workings. No. 1 shaft, at which the plant is centralized, is the main hoisting shaft, with five levels to 950 feet. No. 2 shaft, 2,400 feet east of No. 1, is under development, with four levels to 725 feet. At the main shaft, the ore is hand-trammed in 1 1/2 tons cars from the scopes to the stations o:i each level and hoisted in cages to surface at a rope speed of 900 feet per minute. Air-operated tipples are used to dump the ore through grizzlies of 14-inch openings into a surface bin of 150 tons capacity. The ore hoisted at No. 2 shaft is trucked from the headframe bin to the mill. Milling commenced in January, 1938, ar a daily rate of 250 tons. Within two months this rate was increased to the unit&apos;s maximum capacity of 325 tons. A second unit to treat a further 325 tons daily was installed in April, 1939. The orebodies mined at No. 1 shaft are parts of a silicified zone at the contact between syenite porphyry and greywacke. The zone is ten co sixty feet wide, strikes easterly, and dips to the south at 55 to 85 degrees. The hanging-wall of the zone is marked, though not precisely, by a strong gouge fault. Locally, the boundary of silicification may be as much as twenty feet either above or below the fault, but for practical mining purposes the fault is the hanging-wall of the ore-zone. The footwall roughly parallels the fault, but as an assay wall it is usually irregular in detail. The ore is dense and hard, a siliceous replacement of both porphyry and greywacke, mineralized with fine disseminated pyrite.

Jan 1, 1941

By P. Kim Carroll, D. Nick Tiffany, Doyl M. Fritz

Thunder Basin Coal Company received the 1987 Wyoming Excellence in Surface Mining Award for construction of the State&apos;s first major sediment control reservoir to be designed using the new settleable sol ids standard. Use of this standard resulted in construction cost savings of more than $250,000; reduced water quality monitoring; enhanced downstream channel stability because of more natural sediment loading; allowed simultaneous establishment of permanent waterfowl and fisheries habitat; and provided a quality recreational site. This article will address factors associated with the design and construction of that sediment reservoir and the benefits that were realized. (Note: This paper was originally published in the proceedings for the 1988 National Symposium on Mining, Hydro1ogy, Sedimentology and Reclamation held in Reno, Nevada, December 5-9, 1988.)

Jan 1, 1989

By Y. Okahara

The chlorination behaviors of pure iron and manganese oxides were investigated by combining a thermogravimetric analysis (TGA) technique with batch-boat roasting followed by leaching. Ferrous and manganeus oxides could be chlorinated readily, but, in the absence of a reductant, the higher oxides of both iron and manganese were difficult to chlorinate. Thermogravimetric analysis curves were drawn to illustrate the complexitites of the reactions, and the possible mechanisms were discussed. Then three manganiferous materials from the Cuyuna Range of Minnesota were treated by a process involving the selective chlorination of manganese followed by leaching. The results were interpreted in the light of the chlorination mechanisms observed on the pure iron and manganese oxides.

Jan 1, 1969

By H. L. Retcofsky

Carbon-13 nuclear magnetic resonance (18CNMR) spectra of nine 2-substituted pyridines, seven 3 -substituted pyridines, and nine 4-substituted pyridines have been obtained and analyzed. Substituents included both electron-releasing groups and electron-with hawing groups. Substituent effects on the magnetic shieldings of the ring carbons, except for those in the 2-positions of 2-substituted pyridines, were found to be quite similar to the effects reported for the monosubstituted benzenes, Thus, at least to a first approximation, the two classes of compounds have similar shielding mechanisms. Shieldings of the carbon atoms in the 5-positions of 2-substituted pyridines and those in the 6-positions of 3-substituted pyridines were found to reflect electron release or withdrawal by substituent groups, The pyridinium cation and the compounds 2,2&apos;-dipyridyl and benzonitrile were also investigated.

Jan 1, 1969

By H. G. Wickes

Virtually all fluorine consumed by the aluminum industry is as the electrolyte of the Hall-Heroult process for producing primary aluminum. A small amount of fluorspar is used but most fluorine is consumed as either aluminum fluoride or cryolite. Some fluorine- containing materials are used in secondary aluminum production, but the amount is negligible compared with primary production requirements. Any analysis of the future of the primary aluminum industry must take into account two powerful and closely related driving forces which are shaping that future. These factors are increasingly stringent restrictions on the emission of pollutants and the continuing cost-price squeeze. Nowhere do these factors combine more forcefully than in the area of fluorine consumption. We can safely assume that industry efforts to reduce fluorine consumption will be intensified and that these efforts will be fruitful. This paper will attempt to identify and quantify the factors and trends of fluorine consumption during the next decade. We will be concerned primarily with the demand for new fluorine. Sources of new fluorine will not be treated.

Jan 1, 1973

By Margaret N. Maxey

For the past quarter century, it is fair to say that the political agenda of Western industrialized societies has been driven by those opposed to forms of economic growth providing sustenance to a growing population. They regard growth as the major threat to their social philosophy which champions a wholly "new ethic of biocentric equality" or "living as if Nature mattered." This ethic demands that "a violent, plundering humankind" must abandon its alleged rape of Planet Earth and derive its ethical norms from pre-existing harmonies and fragile, precarious balance present in Nature. A Green political agenda appeals strongly to deep longings shared among many people whose temperament seeks tranquillity in a world of wild natural beauty uncluttered by dependency on tools and experts and specialists. According to proponents of the Green philosophy, our world is pregnant with enormous problems. Armed with expanded political powers, regulatory guardians at state and local levels have mustered their forces with shotguns cocked, poised to prod an ignorant and lazy citizenry to the altar for an exchange of vows with Environmental Ethics. Social engineers have skillfully discredited the traditional role of professionals in scientific engineering who are summarily dismissed as the failed architects of an industrial system pillaging the earth. They stand accused of producing unmanageable offspring - from mining minerals and energy resources to disposing of toxic wastes - whose disputed parentage and expectant crimes against humanity must be prevented by removing them from normal custody. Green critics claim that markets cannot be given custody of industrial offspring - pollutants, wastes, land-use abuses. Markets appear to have failed to provide equity to present and future generations. The only custodian with sufficient coercive power seems to be the regulatory bureaucracy. The upshot is a stark Hobson&apos;s choice - Shotgun Wedding vs. Custody Dispute. It derives its fateful predestination from an uncritical acceptance of several preconceptions which currently undergird the altar of Sustainability characterized by its acolytes as "a new and exciting doctrine." It is significant that Limits to Growth slogans of the 1970s have been displaced in the 1990s by the more palatable language of Sustainability. As a policy recommended to forestall an impending doom, Sustainability derives its credibility from dire predictions of global warming, ozone depletion, acid rain and the like. The Rio Declaration announced to the world in June 1992 that, although energy is essential to human well-being, its production and consumption in wealthy industrialized nations is unsustainable. It called for a complete overhaul of energy systems with nothing short of a total replacement of fossil fuels, uranium fission reactors, and large hydroelectric projects by means of so-called renewable energy sources, augmented by coercive regulations to force conservation and limit consumption demands. The social and political consequences of such a sweeping

Jan 1, 1995

By A T. Spathis, M G. Wheatly

Some preliminary dynamic pressure data were obtained from several charges detonated in a tunnel situated in massive granite rock. The context of the work is the potential for desensitisation of explosives, failure of detonators, and sympathetic detonation due to the close proximity of inter-hole and inter-deck explosive charges to each other. Dynamic pressures were measured using piezoelectric gauges in water-filled 45 mm diameter holes adjacent to the charges. Some of the first arrival peak pressures were noisy, and although not fully resolved, may be due to reflections and the physical arrangement of the transducers and their size with respect to the monitoring holes. The estimated peak pressures were between 0.1 to 8.7 MPa at approximate distances of 2.8 to 0.8 m, respectively. Further work is planned with gauges that are disposable, have a higher pressure range, and can be used within a few borehole diameters rather than the piezoelectric gauges used in the present work.

Jan 1, 2016

By Thomas P. Battle

Titanium is the ninth most common element in the Earth&apos;s crust, yet only in this century has titanium come into use as an engineering material, particularly in aircraft structures, as the metal, and in pigments, as the dioxide. In this presentation, the metallurgical aspects of processing titanium-containing raw materials will be reviewed. Particular emphasis will be given to the ores and beneficiation techniques which lead to the production of titanium dioxide pigment, which accounts for over 90% of world titanium production.

Jan 1, 1993

By B. J. Moore

This Bureau of Mines publication contains analyses and related source data for 276 natural gas samples from 23 States. All samples except four were collected during calendar year 1984. Those four samples were collected earlier, but releases granting permission to publish were not received until 1984. All samples were obtained and analyzed as part of Bureau of Mines investigations of the occurrences of helium in natural gases of countries with free market economies. This survey has been conducted since 1917. The analyses published herein were made by the mass spectrometer and chromatograph. The results of these investigations are published annually to make the information available to the petroleum industry and the general public. Twenty-eight publications have presented the results of 13,957 gas analyses made prior to 1984. The first three bulletins (1-3)2 contain analyses and related source data on 5,218 gas samples collected from 1917 through 1960; these bulletins have been supplemented annually by information circulars (4-17, 19-24, 26-28) containing 8,453 analyses of samples collected since 1960.

Jan 1, 1985

By David R. Peterson

This user&apos;s manual covers a set of 5 computer codes which were generated during development of a simulation of deep ocean mining operational economics. Table 1.1 provides a summary of these codes, and a more thorough description of each follows, In addition to the descriptions in this user&apos;s manual, internal documentation is provided throughout each code, except for the very simple ones, for ease of understanding or possible modification. The two major codes are MINER, which performs the deep ocean mining system operational simulation, and MSWEEP, which calculates the sweep and feed efficiencies for a set of collector paths generated by MINER. The standard operating procedure is to input the system and operating parameters to MINER, which computes a set of collector paths automatically and stores the information in the fife PATH.DAT. MSWEEP subsequently retrieves the collector path data in PATH.DAT, and uses it to calculate sweep and feed efficiency. Separating MINER and MSWEEP allows parmetric execution of MSWEEP without recomputing the collector paths with MINER. PIPEST, RESP, and OBSTCL are special-purpose codes described in more detail in the following documentation.

Jan 1, 1979

Adams, John H., Pres. & Mgr., Alabama Lime & Stone Corpn., 1302-4-8 First Ave., Birmingham, Ala. &apos;14 Adams, L. W., Otis Steel Co., Riverside Plant Cleveland, Ohio. &apos;15 Adams, Leland D., Min. Engr., Mgr., Signal Mines Co., Goldbanks Quicksilver Co., 485 California St., San Francisco, Cal. &apos;14 Adams, R. L., Min. Engr., Old Ben Coal Corpn., Mine 12 Christopher, III. `19 Adams, Robert M., Robert M. Adams Co 1201 Fidelity Bldg., Duluth, Minn. &apos;20

Jan 1, 1925

The Annual Business Meeting of the members of The Rocky Mountain Coal Mining Institute held during the 83rd Regular Meeting of the Institute was called to order by the president, Bernard Bernstrom at 2:50 p.m. Tuesday, June 30, 1987 in the Janss Auditorium of the Snowmass Conference Center in Snowmass Village, Colorado. Thirty-one were present and a quorum was established. The president outlined the purpose of the meeting was to inform the members of the status of the affairs and activities of the corporation during the preceding year. It was moved by Leon Jeannot, seconded and carried to approve the minutes as published in the 1986 Proceedings. The chair called for reports of the various committees and these reports will by placed on file in the RMCMI Office. Bylaws and Resolutions. Chairman Loren V. Linville reported there were no bylaws revisions. He further reported that the Board had adopted three resolutions: (1) Noting the passing of members since the last convention-Benton Boyd, E. A. Hare, E. S. Moran, Jr. and Edward Prostel. (2) Of appreciation to the Executive Secretary, officers, chairman, Diamond Jubilee chairman and committees and convention committees for an outstanding job in preparing for the 83rd Regular Meeting of the Institute. (3) To recommend to all RMCMI members that, on an individual basis, they each oppose replacing coal fired generation with natural gas generation. Membership. Chairman Leon Jeannot reported that at the beginning of the 1986 fiscal year, there were 881 active or dues-paying members. During the year, 219 members were dropped for a variety of reasons such as non-payment of dues, transfer, employed elsewhere, change of address. Ninety-six new members have been recruited for an active total of 758. In addition there are 55 Life Members, 20 senior members, six scholarship winners and seven supporters for a net total of 846. The budget of RMCMI calls for 1,000 active members and we must address and plan for those short-term prospects as they will certainly impact our membership. A full report is on file in the RMCMI office. Patrons of the Institute. Chairman Ira McKeever reported that only 59 Patrons renewed their support during 1986-87. Program. Chairman Bill Balaz announced that the convention program theme "This is OUR Life", as presented in "Past", "Present" and "Future" segments was very well received. He called for additional helpers another year and suggested that next year&apos;s program format be changed to a hard hitting one. Publicity. Chairman Tom Egan reported that of the three newsletters sent members during the year, that the most effective one was the newspaper format one and recommended its use next year. RMCMI hired Bob Jacob who heads his own public relations firm to solicit advertising for the Proceedings on a contract/ commission basis. He attended the convention for this purpose and to solicit business card ads. A full report is on file in the RMCMI office. Scholarship. Chairman Keith McGinnis reported that five of the six scholarship recipients were present at the convention. Each was introduced to the membership at the Tuesday morning Scholarship Breakfast, presented a plaque and responded. The input from each winner was most favorable to the program. Each was appreciative of the many contacts made and the educational seminars and programs. The selection process started in March and was completed in May, except for one university which had difficulty in providing a candidate. It is suggested that the initial contact with the institutions be made in December and completed by April 1. This year, for the first time, three of the six universities were visited for the purpose of interviewing the candidates. They were Colorado, Utah and Wyoming. A very positive feedback was received from these schools and it is recommended that the practice continue. CONVENTION COMMITTEES Convention Arrangements. Doris Finnie presented the following report: As a professional meeting planner, this Diamond Jubilee convention was indeed a great challenge. One meal was added to the package and thus increased the individual cost. Snowmass Resort Association is unique in that they utilize a conference coordinator who acts as the middle man between myself and the usual persons we deal with, like AV personnel, the chef, the banquet director, the steak fry personnel, the Sunday tour etc. so the office had to become creative. For instance, we learned early on we could not deal with the local florists. It cost us lots less to buy our flowers wholesale in Denver, have my husband drive them up and our West Virginia daughter to arrange them! But, finally her floral arrangement class at CSU paid off! This was truly a Finnie family orchestrated convention. Our Lakewood daughter acted as Scholar-

Jan 1, 1987

By W. R. Crane

Recent papers on support of roof and top rock in mines representing present practice in so far as it hits been described by engineers in all of the principal mining countries, cover a relatively aide range of topics. The papers abstracted herein include such subjects as the testing of materials of support, failure and movement of rock above workings, effect of excessive pressures on rock masses, axed the application in mines of timber, metal, concrete, packing, and filling support. It is not within the scope of this paper to present a logical and orderly discussion of the elements of support and their application to conditions influenced by the material worked or the method of mining. Only the essential facts of a paper appear in the abstracts, the idea being to give a fairly clear picture of the behavior of various types of support under brows conditions and to put into concise form important information concerning present practice, modifications of practice, and the trend toward new practice. With such valuable facts from others experience made readily available, it Is hoped that the engineer with particular and often trying problems may obtain suggestions that will be immediately helpful.

Jan 1, 1932

Prospectors were digging silver in the Ray mine area in 1873, and by 1880 high-grade copper ore was feeding a 30-ton copper furnace. In 1910, D. C. Jackling and his associates organized the Ray Consolidated Copper Company, known in mining circles as Ray Con, to exploit the Ray orebody. For 50 years, all mining was underground and the Ray mine was known the world over for innovations in mining methods. It was the first to mine important tonnage (8,000 tpd) by block caving methods. The mill at Hayden, 26 miles (41.6 km) from the mine, kept pace with the new mining methods developed at Ray and in the early 1920&apos;s flotation replaced gravity concentration by the vanner machines. First mining by open pit methods began in 1950 and in January 1955 all underground mining was discontinued. The new primary crushing plant, installed in early 1967, featured design simplicity with a low capital cost. The 54 in. gyratory crusher was installed within a total height of 6 1 ft (18.65 m) from the truck dump road bed to the floor beneath the feeder-conveyor under the surge pocket. The crusher is fed by 120-ton trucks dumping from one side only into a 200-ton hopper equipped with a horizontal splitter bar to protect the crusher spider. The crushed ore pocket, of 120 -ton live capacity underneath the crusher, discharges to a 0 to 200 fpm (61.2 mpm), variable-speed, 72 in. by 80 ft long (1.83 m by 24.4 m) sloped belt feeder, probably a first in the industry. Wood-picking stations are provided on either side of the belt so that old mine timbers and tramp iron can be removed from the crushed ore and the wood can be dropped into Dempster containers located below the belt. Counter-weighted finger gates control the bed depth on the belt at 14 in. (356 mm) and a low- level radiation unit automatically maintains a minimum of a 3 ft bed (900 mm) of material on the belt directly under the surge pocket. The conveyor is skirted for its full length and is approximately 60 in. (1.52 m) wide inside its metal skirt liners. Ten impact idlers at 12 in. (305 mm) spacing are provided under the loading pocket and remaining idlers are spaced at 18 in. (457 mm). The belt is 1 ¼ in. (31. 8 mm) thick; and, while it has occasionally been damaged by tramp material, belt life averages 11 million tons. When the belt is changed, the coiled new belt is lowered into position onto one of two belt stands mounted over the feeder, the old belt is cut, and one end is attached temporarily to the new belt. The other end of

Jan 1, 1978