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By L. J. Lorig, B. H. G. Brady

The Discrete Element Method is a numerical technique suitable for use in modeling the discontinuum behavior of jointed rock. The disadvantage of this method, in its application to analysis of underground excavations, is the necessity to discretize the complete problem domain. Since the far-field rock responds to the excavation as an elastic continuum, it may be appropriately represented by the Boundary Element Method. This exploits the inherent advantage of the Boundary Element Method in representing a quasi-infinite domain in terms of its internal surface geometry and associated boundary conditions. The procedures employed in developing a first-generation coupled Discrete Element-Boundary Element algorithm are described and the solution to a simple problem verifying the performance of the coupled code is presented. A procedure for numerical treatment of installed support systems is also presented.

Jan 1, 1982

Scraper With over 40 pet more struck capacity than previous models, the new Caterpillar No. 90 scraper is designed to increase earthmoving production when used with D8 tractor power. This scraper moves dirt with the aid of a hard surfaced, reversible cutting edge. Material is carried in a flat, doublebottom bowl of high tensile steel. Operation is by means [ ] of a cable-control unit, which can be mounted on the rear of the tractor to provide for positive loading and ejection. Tapered roller bearings are installed at each axle. The scraper uses two 24.00 to 29 front tires and two 27.00 to 33 rear tires, all four of 24-ply rating. When loaded, the scraper distributes 60 pet of the weight on the rear tires. Circle No. 1

Jan 1, 1952

By D. C. Livingston

The Pilares de Nacozari mine is located ill Sonora, 75 miles south of Douglas, Ariz. The town of Douglas is on the International Boundary and is the place at which the ores from the Bisbee mines are smelted. The Moctezuma Copper Co. owns the mines at Nacozari, and the copper-concentrates shipped to the Copper Queen smelter, at Douglas, make a good smelting-mixture with the Bisbee ores. The Moctezuma Copper Co. and the Copper Queen smelter at Douglas, as well as the railroad from Douglas to Nacozari, are owned by the Phelps, Dodge & Co. The ore-deposit occurs in the form of a large ellipse with a major axis of approximately 2,000 ft. and a minor axis of about 600 ft., the major axis bearing about 9" W. of N. The

Jan 1, 1913

By Daniel C. McLean

Copper concentrates produced by many operations in the United States and South America contain chalcocite (79.9% Cu) as a major component, yet the grades of these concentrates rarely exceed 25 to 28% Cu. Mineralogical studies made by E.P. Cadwell indicated that the low grades were caused by dilution by pyrite rimmed with secondary chalcocite. Laboratory and plant tests proved that concentrates could be significantly upgraded by using a simple, low cost cyanide leaching technique to dissolve the rims and reject the pyrite. The many advantages of this new procedure are cited and the process steps and a typical flowsheet are described.

Jan 1, 1984

By L. P. Teas

ALTHOUGH 1927 in the Arkansas-Louisiana territory will probably pass into history as a year of small profits and little new production, nevertheless during this period two large gas fields were developed; two new oil fields were discovered, and two new oil horizons, hitherto of minor Annual Production in Millions of Barrels FIG. 1.-PRODUCTION OF NORTH LOUISIANA AND ARKANSAS BY FIELDS FOR 1926 AND 1927. importance, were developed; In spite of the "hard times" some of the leading, supply houses did more business this year in this. district than in any year since 1920.

Jan 1, 1928

By N. B. Aughenbaugh, W. C. Patrick

The availability of a thorough, simple-to-use roof fall classification system is desirable for several reasons. First, such a system would expedite the reporting of falls for the purposes of estimating material removal costs, analyzing damage levels, and complying with federal regulations to report falls in certain areas of the mine. Second, the classification system would allow the mining engineer to record falls routinely with little time and effort expended. This would encourage him to make observations concerning what type of roof support would work best in a given situation. Third, and probably most important, an

Jan 1, 1980

By M. J. Langley

Zinc ores were first discovered in Tennessee in 1856 at Jefferson City where a deposit became the Mossy Creek mine. From that time until 1913, small- scale attempts at prospecting and mining were made in various parts of the district. The actual systematic development of the zinc deposit dates from 1913 when the American Zinc Co. started operations at Mascot. Mining in the Mascot-Jefferson City area today is devoted exclusively to the zinc sulfide, sphalerite. Various grades of zinc mineralization have been found intermittently through a 600-ft vertical thickness. However, the commercial ore is confined to a total thickness of about 250 ft, from which it usually is mined irregularly from four or five separate levels known locally as "ore runs." In a few places vertical thicknesses up to 150 ft have been mined where commercial material extended from one run to another.

Jan 10, 1962

Detailed Geology of Certain Areas in the Mineral Hill and Warm Springs Mining District. By A. L. Anderson. T. H. Kilsgaard and V. C. Fryklund. Jr. Idaho Bureau of Mines and Geology. University of Idaho. 73 P. Maps, Illus.-Divided into three parts, this pamphlet covers the geology and ore deposits of the Hailey-Bellevue Mineral Belt, the Triumph-Parker mine mineral belt, and the ore deposits of the Mayflower Area. Numerous maps and illustrations are included for each area. Government Administration of the Copper Industry, World War 11. By John W. Douglas. 1950.51 P. $1.-This pamphlet covers in detail all the steps relating to control and operation of copper and copper products, and is of particular interest to primary producers, brass mills, wire mills, and foundries. Of particular current interest is the booklet's coverage of the steps leading to the Controlled Material Plan, into which industry is now once again heading. Copies can be obtained for $1 from John W. Douglas, Republic Foil & Metal Mills Inc., 55 Triangle St., Danbury, Conn.

Jan 12, 1951

By N. Rowlands, J. A. Finch, R. Espinosa-Gomez

The sulphation roast-leach process for complex sulphides results in phase changes due to roasting and leaching. The phases in the calcine, and in the neutral and hot acid leach residues were identified and their degree of liberation determined in order to design and Interpret separation tests on the residues. The hot acid leach residue was composed of hematite, silica, and lead sulphate with some associated silver. Magnetic separation was selected as the process for producing a lead concentrate, as the non-magnetic product. Separation was limited by -1 pm hematite reporting to the product, and hematite/lead sulphate agglomerates reporting to the magnetics.

Jan 1, 1984

By Dermot Macaragh Ross-Brown, Brian Stimpson

Borehole information is often the only source of information on rock conditions at depth during the stage of feasibility studies of a project, and from this data the rock mechanics engineer would like to make some quantitative estimates of rock mass cohesive strength. While judgement and experience will usually play a paramount role at this stage, simple tools for estimating rock mass cohesive strength would be an asset. In this paper, an approximate technique is suggested for assessing the cohesive strength of a randomly jointed rock mass from borehole data on fracture intensity and intact rock strength.

Jan 1, 1980

By T. Prof. Egleston

DURING the last winter we have been actively engaged in the School of Mines in search for boracic acid. This has been owing to the fact that Mr. M. W. Iles, assistant in the qualitative laboratory, has discovered a test for that substance which makes its discovery exceedingly simple instead of being, as previously, very difficult. It consists in powdering the mineral, calcining it, then moistening it with sulphuric acid, and heating on a platinum wire until the sulphuric acid is expelled. It is then moistened with glycerin and made to take fire. If boracic acid is present it infallibly gives a green flame. It is not at all surprising, under such circumstances, the test being so easy, that boracic acid has been found by the students in a great many cases where its presence was not previously suspected, and in some where its detection was previously too difficult to warrant looking for it. We were not prepared, however, for its discovery in Lake Superior iron ores, and were disposed at first to think that a mistake had been made. After, however, it had been frequently reported in these ores it was considered worth while

Jan 1, 1877

By E. S. Moffat

Members of the Institute who have visited the works of the Lackawanna Iron and Coal Company at Scranton, will remember the exposure of a large vein of anthracite coal in the rocky bank on the south side of Roaring Brook, near the blast-furnace. The vein is quite flat, and is exposed to view for several hundred yards along the banks of the brook, a few feet above the surface of the water. It is some ten feet in thickness, and is known as the Big Vein. At a point just opposite the blast-furnace, much of the coal from this vein was mined out many years since, the usual pillars being left to support the overlying rock and drift, which are here some twentyfive to thirty feet in thickness. Over thirty pears ago fire was communicated from an ore-roasting pile on the surface of the ground at this point, through an old shaft, down to the refuse and pillars which had been left in the mine

Jan 1, 1887

By Vassiliki G. Stavropoulou

Although plane-strain is the preferred method of analysing many rock mecahnics problems, little is known about the behaviour of rock under this loading condition. A simple and inexpensive apparatus has been built for laboratory testing of rocks in plane-strain conditions. A thorough .investigation of the specimen geometry and the friction end effects showed that the results can be considered as reliable. The behaviour of a brittle sandstone in the simplest plane-strain condition [(03 = 0)] is significantly different than that of the uniaxial compression [(02 = U3 = 0)]. The plane-strain values of the Young's Modulus and the Poisson's Ratio are decreased in comparison to the corresponding uniaxial values. Dilatancy is also reduced in plane-strain, whereas the pre-failure brittleness of the rock increases. The most dramatic effect of the plane-strain condition is that on the strength of the sandstone, which increases by 49 per cent in comparison to its uniaxial compression value.

Jan 1, 1982

By W. L. Fourney

This paper describes a number of model tests conducted in Plexiglas models to investigate the phenomenon of fracture pressurization. The models were examined with high speed photography while being subjected to explosive loading. At the same time pressure transducers were used to record the pressure in the borehole as a function of time and also along the path of the propagating fracture to measure the pressure at various locations along the fracture as a function of time. Both propellants and explosives were used to charge the borehole. Air as well as fluid filled boreholes were needed to provide a variety of pressure rise rates. On some tests eddy current displacement gauges measured crack opening displacements as a function of time. As a final check high speed photographs taken during the event were used to visually ascertain the location of the fracture at any given time.

Jan 1, 1984

By Dale C. Matthews, Donald L. Simpson

Hecla Mining Company's Lakeshore Mine and Metallurgical complex near Casa Grande, Arizona, is the first plant in North America to utilize the roast/leach/electrowinning process for production of cathode copper from sulfide concentrates. Oxide copper ores are also mined at Lakeshore. Using sulfuric acid and sponge iron by-products of the roast/leach operation, the oxide ore is leached in vats, the copper is precipitated with iron and recovered as cement copper. This paper will describe the roast/leach facilities and discuss the operating conditions at which more than 95 percent of the copper in concentrate is made soluble in acid solutions while less than 5 percent of the iron is rendered soluble. More than 97 percent of the sulfur contained in concentrate is captured either as strong sulfuric acid or as soluble sulfates in leach liquors. The iron rich residue after leaching is pelletized and reduced to sponge iron in an SLRN reduction kiln.

Jan 1, 1981

By Alan E. Bland, Jerry G. Rose, Thomas L. Robl

This paper describes the observed variability of the chemical composition of coal preparation plant refuse for the major producing seams of Kentucky. Both the Appalachian Coal Field of eastern Kentucky and the Eastern Interior Coal Field of western Kentucky are represented. Also reported is the variability observed in the chemistry of the coal refuse due to cleaning, and the observed chemical variations between past and present production samples. This represents part of a larger study directed toward characterization and utilization of Kentucky coal refuse.

Jan 1, 1978

By T. M. Anderson

From the start of production in 1915 until 1948, underground block caving operations accounted for all of the ore production of Inspiration Consolidated Copper Co. Open pit development work began in 1947, and ore production from the open pit commenced in March 1948. Thus began the transition from underground to open pit mining which continued until August 1954. Since then, open pit mining has accounted for all ore production which presently averages 105,000 tons of ore and 75,000 tons of waste rock each week. Open pit mining operations at Inspiration is carried on in two separate pits-the Live Oak Pit and the Thornton Pit. The Live Oak Pit covers an area of approximately 1500x3000 ft and the Thornton Pit, 2500x2000 ft. The geographic centers of the two pits are 4000 ft apart and, at their nearest point, the surface slopes are 500 ft apart.

Jan 1, 1961

By Lawrence Dykers

The paper presents a generalized history of the growth and utilization of electronic data processing in a medium- size, mining-oriented company. A brief narrative outlines a corporate wide data gathering system, its hardware and application. Responsibility areas for corporate accounting, operations control, engineering, and research program development are defined. A Synopsis of programs within responsibility areas is presented along with a review of program language requirements for each of these areas. Anticipated additional uses of computers and the programs being developed for these uses are outlined. The scope and growth of an Information Systems Department within Duval Corporation is briefly discussed. Suggestions are presented which should help minimize the problems and avoid some of the pitfalls of program development for those contemplating the initiation or revision of an electronic data processing system. The importance of lucid and comprehensive program documentation is stressed.

Jan 1, 1969

By Leon Hart

THE nickel-chromium alloys of importance are those containing iron and those free from iron. The most important alloys containing iron, with regard to high tonnage, are the nickel-chromium steels. Straight nickel steel was introduced about the year 1889, but it was not until 1895, when it was found that the addition of chromium greatly increased the FIG. 1.-RESISTIVITY OF NICKEL-CHROMIUM-IRON ALLOYS. strength and resistance to shock, that nickel-chromium steels came into use. The three types of nickel-chromium steels developed at this time were: Type 1, containing 3.50 per -cent. nickel and 1.50 per cent. chromium; type 2, containing 2.00 per cent. nickel and 1.00 per cent. chromium; and type 3, containing 1.50 per cent. nickel and 0.50 per cent. chromium.

Jan 1, 1921

By T. H. Chin, R. W. Bartlett

A simple on-stream particle-size analysis method is presented that leads to a bulk-property single-channel device; although the concept can be extended to multi-channel sizing information. The method is based on continuously measuring and comparing the percent solids in the sample stream and in an internal-reference stream containing only undersize particles. A semipermeable hydraulic system is used such that the particle mass concentration in the internal stream can vary, and is always proportional to the undersize particle mass concentration in the sample stream.

Jan 1, 1975