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By W. A. Hustrulid, N. A. Ross

An analysis of the design of medium to hard rock tunneling machines is presented. The developed equations are used to compare performances and machine requirements using kerf and fixed pick cutters to bore a given rock. With the use of pick cutters, required thrusts can be greatly reduced and still achieve the same boring rate as with present day tooth or kerf cutters. It appears that the cutting coefficient, which for most boring machines is of the order of 0.1, should be increased to one or larger to facilitate rock removal by cutting rather than grinding. The depth of cut and the indexing distance should be greatly increased to make use of inherent rock weakness.

Jan 1, 1971

By S. Acar, P. Somasundaran

The results obtained for the selective flocculation of natural ores do not usually agree with the corresponding properties of the constituent minerals when present alone. This is mainly due to the presence of dissolved mineral species which can interact in many ways with other components in the system and alter their behavior. In this paper, the effect of dissolved species on the flocculation and electrokinetic properties of sulfide minerals is discussed. Dissolved iron, copper, and nickel (Fe, Cu, and Ni) species are found to affect the properties of natural chalcopyrite and pentlandite in certain pH range. These effects are interpreted in terms of species adsorption leading to activation or depression of reagents, surface precipitation, and complexation of species

Jan 1, 1986

By F. R. Jones

T Tahawus, N. Y., National Lead Co. operates the MacIntyre development. Here the world's largest titanium mine produces 5200 long tons of ore per day and pours 8000 long tons of waste rock over its dumps. Concentrated ilmenite is sent by rail to National Lead Co. pigment plants, and a second product, magnetite, is sold to steel producers in raw form or is agglomerated and shipped as sinter. Several earlier attempts had been made to produce iron from the deposits, which have been known since 1826. These attempts failed, chiefly because of titanium impurity. In 1941 the present owners re-established the operation for production of war-scarce ilmenite, and the impurity became the main product.

May 1, 1956

By Christer Danielsson, Sven Ivarsson

In 1951 the first ton of iron was shipped from West Africa; ten years later the total export exceeded 4 million tons, and an optimistic forecast for 1970 indicates a production capacity of something around 40 to 50 million tons. The quality of the ore varies from normal hematitic concentrates, through naturally enriched hematitic direct shipping ores with comparatively high content of ore fines, to dense, hard, rich lump ores of magmatic character. West Africa is largely composed of folded Pre-cambrian rocks trending generally northeast to southwest. They are exposed over about one third of West Africa and are part of the vast continental plateau which has an average elevation of about 1300 ft in this area.

Jan 3, 1963

By H. R. Hardy

The study of the mechanical properties of geologic materials was initiated in the Mining Research Section of the Fuels and Mining Practice Division in 1951 as part of a fundamental study of ground stress in Canadian coal mines.1 Early in the investigation of the mechanical properties of geologic materials, however, it was realized that the test results are influenced by the rate and the duration of loading. For this reason, laboratory investigations2,3 were undertaken to study the effect of long-period uniaxial stress on the deformation and failure properties of these materials. A literature survey indicated that work on the time-dependent properties of geologic materials had been very limited in the past.

Jan 1, 1965

By Theodor Knutzen, Charles H. Fulton

The plant of the National Smelting Co., a corporation controlled by the Horseshoe Mining Co., was built during 1901 to smelt the dry siliceous ores of the northern Black Hills, extracting the gold- and silver-values in a matte of low copper-percentage which is shipped to Omaha and Denver for refining. Originally, the plant was designed to collect the values of the siliceous ores in an iron-matte, which mas to be resmelted with lead-ores, in a lead-furnace, the lead-bullion produced to be refined into Doré bullion in English cupelling-furnaces. However, the scarcity of lead-silver ores in the Black Hills, owing to the present non-productiveness of the Galena district, led to

Jan 1, 1905

By John J. Sense

The Mission unit of the American Smelting and Refining Co., located 20 miles south of Tucson, Ariz., is a high-volume, 15,000 tpd operation which utilizes a relatively light equipment fleet. As such, management is very conscious of the mechanical and operational availability of the equipment in use. One of the key items in attaining this efficiency is a complete and reliable record of mechanical and operational machine availability which is an invaluable guide for: 1) Estimating future equipment and personnel requirements of an operating property. 2) Planning an expansion program of an operating property. 3) Estimating equipment and personnel requirements of a new property. 4) Selection of replacement equipment. 5) Comparison of separate operating properties.

Jan 3, 1964

By Adrian C. Dorenfeld

Concentradora "Doña Aida" (100 t /d capacity) was built in 1971-72 to treat dumps and ores containing mixed oxide-sulfide copper-gold-silver minerals derived from two veins. The veins, Don Felipe and Maria, are about 150 m apart, but are distinctly different mineralogically. The deposits are near Sun Juan de Guadalupe, Durango, Mexico. All new process equipment was manufactured locally, in or near Torreon, Coahuilu. Sampling, ore testing, flowsheet design, plant design, drawings, purchasing, financing, and construction, etc., were planned and directed by two engineers. Construction was executed by local miners and common labor (largely agricultural). The paper presents detailed costs for equipment and construction. The subsequent breaking-in operation is discussed.

Jan 1, 1982

By Gordon B. French

Occidental's in situ retorting process for oil shale has many advantages over the conventional, underground mine and surface retort. Only a portion of the oil shale is mined and transported outside where it blends with the oil-shale talus found in the area. Spent shale is retained underground without surface disposal problems. The process consumes no water from outside sources. Noise and dust levels are kept at a minimum. As many of the facilities as possible are located underground. More oil is produced from a given area than conventional surface processing. Additional energy can be recovered by using conventional turbines to generate electrical power of magnitude of three to four times required by the operation.

Jan 1, 1977

By John J. Reed

The mines of southeast Missouri's Lead Belt have been in operation since 1864, almost 100 years. During this period about 10 pct of the total ore available has been left in place as pillars, and this now represents the best ore reserve left to the older mines. St. Joseph Lead Co. has been investigating various plans of pillar recovery for several years. The example to be described is only one possible approach under a specific set of conditions. Conditions vary greatly in the different areas within the Lead Belt, and the same approach would be entirely in- adequate in certain other areas, but there are important sections where this system is clearly applicable.

Jan 7, 1959

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 B. H. Sage

ATTEMPTS have been made to predict the volumetric and phase behavior of naturally occurring hydrocarbon mix-tures1-5 but these methods have not been extended to the higher pressures and tem-peratures that are currently encountered in some producing formations. Furthermore, the methods of prediction at present avail-able have not been tested in a sufficient number of cases to ensure their applica-bility to all naturally occurring hydrocar-bon mixtures, even at the lower pressures and temperatures. For these reasons the behavior of a number of hydrocarbon mix-tures from a field in which the subsurface pressures are above 4500 lb. per sq. in.? and the temperatures are in the neighbor-hood of 250°F. was investigated.

Jan 1, 1940

By Colin C. Harris, Nathaniel Arbiter

Current scale-up procedures are discussed critically, including: constant specific energy criterion; determination of mill size and power for a given ore, throughput and mesh of grind; specification of operating speed and loading. A major dynamic and kinetic factor now recognized is that the ratio of media rotational flow to ore axial flow, and the number of mill revolutions that ore is subjected to during residence, both diminish as mill diameter increases. These factors can lead to capacity limitations when mill diameters reach a critical range, especially regarding coarse sizes. Experience at the Bougainville and Pinto Valley operations is contrasted. Corrective measures suggested are to reduce loading and increase speed towards the Davis best operating speed.

Jan 1, 1982

By Phillip A. Stoll, Young Ku Yoon

ThE deterioration of the magnetic properties of silicon-steel core materials during service (magnetic aging) is quite undesirable. Although some information about the effects of impurity elements on magnetic properties is available, 1,2 magnetic aging that occurs at low temperatures has not been extensively studied. Moreover, the microscopic techniques used by earlier workers were not suitable for study of fine metastable phases that are precipitated at relatively low temperatures. Recently, several investigators3,4 successfully used transmission electron microscopy in the study of low-temperature precipitation in Fe-C, Fe-N, and Fe-Mn-C alloys. To investigate metallurgical factors that affect magnetic properties after aging, the microstruc-tures of steels having different magnetic-aging

Jan 1, 1964

By Richard T. Newcomb

Federal and utility industry research has largely ignored coal beneficiation techniques in the implementation of SOx control. This paper accepts the hypothesis that beneficiation cum scrubbing is the cheapest way for the vast majority of seams in the eastern coal provinces to comply with standards. Comparisons are based on point estimates of average beneficiation costs from a model of coal preparation (COBET) designed to simulate four levels of cleaning. The paper describes how economic theory can be applied to derive econometric supply functions from actual data on the geology of minable seams, washability and technical constraints. West Virginia is taken as an example of a producing region. Spatial supply functions are derived empirically from the engineering model simulations.

Jan 1, 1977

By William P. Blake

Eureka has for several years past been known as one of the most important centres of production of argentiferous lead in the country. The average daily yield is now one hundred tons of lead bars, in which the silver and gold of the ore is concentrated. The value of this lead, called " bullion," is about $300 per ton. To produce this quantity of metal, about four times the weight of ore, or say four hundred tons, is required. Most of this ore is supplied by the two leading mines of the district, the " Eureka" and the " Richmond," adjoining claims on Ruby Hill, about two miles from Eureka. There are, however, many other mines from which considerable quan-

Jan 1, 1879

By Thomas Fraser

BECAUSE of the present interest in the subject of sulfur in coal and its removal, such information as is available in the coal-washing literature on the various factors that determine the adaptability of a coal for wash- FIG. I.-COAL-WASHING TABLES OF ONE-FOURTH COMMERCIAL SIZE. ing have been collected and are presented here together with some observations based on results of experimental work carried out in the coal-washing laboratory of the mining department of the University of Illinois, and investigative work at Illinois washeries in connection with the work on reduction of the sulfur content of coal, being carried on at the Urbana Station of the.U. S. Bureau of mines. This investigative

Jan 9, 1919

By A. C. Noble, D. E. Ranta

Orebodies with intricate three- dimensional shapes (such as porphyry molybdenum deposits) are difficult to model using geostatistics or other computer- assisted methods. 'The strong trends in their spatial grade distributions occur as mathematically complex shapes and prevent the customary assumption of local stationarity that is required for accurate ore reserve estimation. "Zoned Kriging", a new method developed by AMAX, solves this problem directly by using the geologist's interpretation of the ore zones as a parameter in the kriging equations. The geological basis and methods used in the Climax ore zoning technique are reviewed and discussed relative to their application in zoned geostatistical modeling. The Zoned Kriging technique is described and demonstrated using data typical of mineral de- posits.

Jan 1, 1984

By Clarence O. Babcock

A simple robust rock bolt load gage was tested in the laboratory to define its characteristic behavior and to obtain a measure of its performance. The gage uses three vibrating wire sensors crimped 120 (2.09 rad) apart into the outer surface of a hollow cylindrical steel, tube. The resonant frequencies of the wires change as the gage is loaded. This change is read with a Creare meter developed for the Bureau of Mines on a previous contract to read borehole stress gage results. A statistical analysis of data obtained defines the variables influencing results. A U.S. patent (3,914,992) assigned by the author to the Dept. of the Interior was granted Oct. 28, 1975.

Jan 1, 1978

By F. Lynwood Garrison

The enormous growth of the manufacture of Bessemer steel in this country within the last few years, due to the almost constant large demand for steel rails, renders it very desirable that our knowledge of the physical and chemical properties of a material upon which we place so much dependence should be increaqed by every possible means. It was with this end in view, and also in hopes of learning something of the causes affecting the regularity of the Bessemer product, that I took up the subject of this paper a short time ago. The lise of the microscope as an instrument of research in the metallurgy of iron and steel is now fairly well established;

Jan 1, 1887