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By Jack L. Henry

The Bureau of Mines conducted seven pioneering experiments in a 12-inch-diameter Kroll reduction reactor to examine the feasibility of coreducing the chlorides of Ti, AI, and V to produce a homogeneous titanium alloy sponge. The coreduction studies proceeded in a normal manner, and the yields of sponge were comparable with those of pure titanium sponge made in the same reactor. Vanadium concentration was very uniform throughout the sponge cake when VC14 in solution in TiCl4 was fed into the molten magnesium. More difficulty was encountered in feeding solid VCl2 and AIC13. Vanadium and aluminum concentration in the sponge was not uniform, and mechanical difficulties were experienced with the small-scale screw feeder. Although the sponge varied in composition from region to region, the ingots prepared from it were uniform in composition.

Jan 1, 1974

By E. C. Foster

The project objective of this contract is to design, develop, and demonstrate a dust collecting system for auger head miners, used in coal seams 40 inches or less in height, which will reduce respirable dust below the limits established by the Federal Coal Mine Health and Safety Act of 1969. This system was to be incorporated into 3 Wilcox Mark 20 continuous miner. In order to accomplish this, the objective was divided in three main areas. First: To develop a dust control system which would remove by isolation, respirable dust from the face area and areas where miners work. Second: To develop a dust scrubbing system to remove and collect float dust before the air reaches the return airway. Third: To reduce the overall noise levels to which the miners are exposed.

Jan 1, 1974

By A. C. Lyons, A. J. Reed

INTRODUCTION A trend which is obvious in the United Kingdom and is thought to be evident in other parts of the Western world is the disproportionate rise in the cost of tunnel mining labour compared with other tunnel cost increases. This disproportionate increase in labour costs has been accompanied by, and may be the result of, a shortage of skilled working labour. To combat this problem there has been a steady increase in the use of machines for excavation and for the erection of tunnel linings to keep the amount of skilled labour working below ground to a minimum. The typical tunnelling cycle, where the ground needs continuous support can be excavation, temporary support, temporary lining, grouting and permanent lining. It is obviously an advantage to combine as many of these operations as possible and carry out as much as possible by machine. Machines have been developed which will, either alone or used in combination with a shield, excavate and, when necessary, temporarily support the excavation. If a segmental lining is used, it can be so designed that it will form the permanent lining and reduce the cycle time and skilled labour requirement to a minimum. In cases in which the ground can be cut accurately to a smooth profile and will stand without support for a sufficient time, the lining can be expanded against the ground and the necessity of grouting eliminated. In cases in which ground will not stand without support, the usual method is to use a bolted lining and to grout behind it preferably as the shield is shoved forward. Whichever technique is used (this is largely determined by the ground) it is an advantage to make the segments as large

Jan 1, 1974

By Gomi S

A new watersoluble binder for mineral ore pellets has been developed by the sulfonation of bituminous materials. A highly effective binder for iron ore pellet making is obtainable from bituminous materials produced in the high temperature cracking of crude oils. This paper deals with production process and basic properties of this binder as well as new applic- ations in the field of iron ore pelletizing.

Jan 1, 1974

By Fun-Den Wang

Finite-element structural analyses were performed to determine the stress distribution and displacements around a single rectangular coal mine opening in a multilayered rock system. The effects of changes in mechanical properties of roof and coal layers, roof layer and mine opening geometry, horizontal-to-vertical load ratio, and structural geologic features on the stress distribution about the opening were studied. Variability in the stiffness and relative thickness of the immediate roof layers can produce a considerable difference in the stress distribution about the opening as compared with that of a homogeneous material. Changes in opening width and horizontal-to-vertical load ratio have different effects on the stress distribution about the opening depending on the composition of the roof layers. In general, where a stiff layer exists in the roof at the surface of the opening, the stresses are higher in the roof and ribs around the opening. Horizontal changes in facies in the roof layers produced by structural geologic features can also greatly alter the stress distribution about the opening compared with the simple layered cases.

Jan 1, 1974

By Robert D. Talvensaari

It is indeed an honor for White Pine, as a member of the copper mining industry, to participate in this Rapid Excavation Conference. Although our presentation, as the title indicates, is not a success story, we foresee, through our experience, future application of boring machines and rapid excavation equipment in the hard rock mining industry. One might ask what a copper mining company would be doing with boring machines and why the gamble on a high-cost, capital investment for a relatively untried application. Perhaps a little background on the White Pine mine and its geology will explain our daring and speculative motives. THE WHITE PINE MINE The White Pine Copper Company, a wholly-owned subsidiary of Copper Range Company, operates a mine, mill and smelter at White Pine, Michigan in the western Upper Peninsula approximately 6 miles due south of Lake Superior. We employ approximately 3,000 people from the surrounding area and mine approximately 25,500 tons of low grade (1%) copper ore per day. The orebody is contained within several distinct sedimentary horizons that comprise the lower 20 feet of a Precambrian formation known as the Nonesuch Shale. Numerous articles and reports have described many aspects of the White Pine operation and the geology. I will brief you only on that criteria which precipitated our interest in rapid excavation equipment and techniques, specifically, boring machines. Mineralogical and optical studies have demonstrated that the siltstones, sandstone and shale beds all contain relatively barren and discrete particles of quartz (25%), feldspar and mica, bonded with

Jan 1, 1974

By Parks T. C

A low-grade disseminated nickel sulphide serpentinite ore from W.A. had a relatively high permeability after drying. Various techniques indicated that the permeability resided within a fine network of fibrous vein- lets and especially within coarse cracks along which the sulphides lay. The ore minerals were therefore open to selective extraction by chemical leaching. A IM ammonia-7.8 wt.o "ammonium carbonate" solution, oxygenated at 1 bar oxygen pressure and about 23¦C, released nickel, copper and cobalt from the sulphides, leaving a permeable residue of goethite, while calcium, magnesium and iron concentrations remained negligible in the leachant. The nickel and copper was electrodeposited directly from the pregnant liquor in a deposit which included 16.5 wt.% sulphur. Enhanced copper/ nickel ratios early in the extraction suggested that valleriite (not amenable to flotation) was leached preferentially. Th$ controlling influence of the pore structure was demonstrated by the dependence of leaching rates on the size of the ore particles used, and on the measured porosity of different ore samples. A 2mm size was probably the optimum for exposing sulphides to the leachant. Leaching was accelerated by increasing the temperature and oxygen pressure.

Jan 1, 1974

Operations at two open cut mines have so far commenced on two out of the five potentially mineable seams in the Fair Hill - German Creek Coal Measures. Due to seam splitting, up to seven mining units are present in the Dysart Seam interval at Peak Downs giving a total of 12 mining units in the section. The coal is low to medium volatile type and produces strong coke. Rank increases and fluidity decreases in the southern part of the area.

Jan 1, 1974

By John T. Kuo

The miner's seismic source strength can be approximately estimated on the basis of a single force acting in an infinite medium. Because of the uncertain- ty involved in estimating the amount of conversion from mechanical energy to seismic energy, the source strength thus estimated may be in error by as much as a half-order of magnitude. Calculations of wave transmission must take into account geometrical spreading, dissipation of energy by internal friction, and energy partition due to reflection and refraction of waves impinging on inter- faces in the layered earth. Theoretically derived peak-to-peak particle velocities in microinches per second (PIPS) are given for two models ; viz: (i) 50-feet thick and (ii) 100- feet thick 4000 ft/sec layers with Q = 20, overlying a half-space of 10,000 ft/sec material with Q = 5O;for the cases .of a hammer blow and a timber impact, at the frequencies of 50 Hz and 100 Hz. Comparison of the theoretically derived peak-to-peak particle velocity with experimental data taken at the Copper Queen Mine indicates that the theoretical particle velocity may be overestimated. A discussion of the distortion of seismic wavefronts by mine tunnels indicates that it is unfavorable to use a seismic source impact on the floor of the tunnel, since deceptive delays in arrival time are liable to occur at the surface. A program of parallel theoretical and experimental work is required to clarify uncertainties still associated with the nature and strength of the miner's seismic source signal which cannot be resolved within the approximations of this work. Its major components include theoretical investigations of the (1) Wave diffraction and scattering of an impact source on a face of a cylindrical cavity. (2) Impact of an elastic object on an elastic medium.

Jan 1, 1974

By Manuel Gomez

A computerized moving average technique was developed to interpolate coal seam characteristics between sample points. The interpolative method coupled with multivariate regression analysis and simulation procedures was used to forecast coal properties not readily obtained from an analysis of drill core samples. Coal property forecasts were of two kinds: (1) specific mine property forecasts that are suitable for mine product control and yield a good approximation of the local variation along both the vertical and horizontal axes of the seam, and (2) regional estimates where much of the local seam variation is smoothed out, but the general trends are maintained. Forecasts of the volatile matter, ash, total sulfur, and the heating value for part of the Pittsburgh seam located in Ohio, Pennsylvania, and West Virginia were in good agreement with independent evaluation data. Spatial configuration for preparation characteristics, particularly, the effect of crushing on sulfur release, low-and high-temperature carbonization properties, the Hardgrove grindability index, the coal hardness index, gasification variables, and hydrogenation factors were constructed for the same area of the Pittsburgh seam. These forecasts may be developed from drill core data collected in the exploration phase of mining. The results, which may take the form of a series of maps, are useful to mining, chemical, and combustion engineers, to economists and mine managers, as well as to coal users for mine design, economic analyses, energy forecasts, utilization studies, mine product control, and environmental control and programming.

Jan 1, 1974

By F. G. Pickard

"The Strathcona Concentrator is one of three concentrators presently operated in the Sudbury District by the Nickel Division of Falconbridge Nickel Mines Limited. Production commenced in 1968 at a milling rate of 6,300 tons per operating day. Milling capacity was increased in 1970 to 7,200 tons per operating day. 7he ore contains iron, nickel and copper primarily in the form of pyrrhotite, pentlandite and chalcopyrite, while the common gangue minerals are feldspar, quartz, mica, talc and chlorite. The primary function of the concentrators is not only to liberate sulphides from silicate gangue minerals but also to separate pyrrhotite from the more valuable minerals pentlandite and chalcopyrite.SummaryExcessive wear on steel liners and blinding of grates in a regrind pebble mill of the Hardy Concentrator was corrected by the use of rubber liners and grates. The success of these resulted in their installation as original linings In all grinding units except the rod mills at the Strathcona Concentrator. The operation of rubber liners and grates when sized mine ore was used as the grinding medium was satisfactory confirming the Hardy Concentrator experience. Problems developed when the grinding medium was changed from sized mine ore to steel balls in that blinding of the grates occurred. This resulted in conversion of the units to overflow type mills through removal of the grates. The lifter bar life was significantly increased by using higher lifter bars.Grinding PracticeOperation of a regrind pebble mill commenced in 1961 in the Hardy Concentrator. This operation demonstrated the economic feasibility of using sized mine ore as grinding medium. Problems caused by excessive wear of metal liners and grates combined with blinding of the grates were corrected in 1964 through installation of rubber liners and grates."

Jan 1, 1974

By Pedro Lilienfeld

This Final Report describes a program whose objective was to design, develop, fabricate, and test an airborne mass monitor for unattended and recording measurements of the concentration of dust in mining environments. Sensing collection are performed by beta-radiation attenuation and inertial implementation respectively. The instrument is portable, battery or line operated provides a digital printout of the mass concentration during each selection sampling period, as well as the accumulated mass of dust, and the elapsed sampling time.

Jan 1, 1974

By W. L. Hunter

Eleven steelmaking heats are described in this Bureau of Mines report in which acid practice was used to produce carbon steel from pre reduced iron ore pellets. Furnace slags obtained with no flux addition to the charge became quite viscous as they cooled, which precluded pressure casting from a ladle. Lime was added to the furnace charge at two levels to eight of the heats to modify slag characteristics in the furnace, and to the ladle in two heats to further modify the ladle slag cover. Selected ingots from nine heats were successfully rolled on a commercial mill to produce No. 10 reinforcing bar.

Jan 1, 1974

By L. John Minnick

Current developments in using lime and limestone slurries to remove sulfur oxide gases from the stacks of coal- and oil-burning furnaces have established an important need for treatment systems which include adequate disposal of resulting waste materials. The paper briefly outlines the classes of scrubbers which are using lime and limestone and describes the characteristics of the by-product material being produced. Some discussion is also included relating to methods of disposal of the scrubber underflow. Since coal-burning plants also produce fly ash as a waste material, one system developed by the author's company combines this material with the sulfur oxide by-products. The mixture is processed in a manner which converts the waste products into usable materials with acceptable structural and environmental properties. Recent interest in protection of ground waters from heavy-metal leachates has made the fly ash-sulfur oxide system an acceptable means of disposal, because the conversion products have very low permeability and adequately encapsulate soluble salts within the hardened mass. Although only limited information is available on the types and chemical requirements of limestone used in these processes, a few guidelines are presented to indicate the range of materials that can be used with good results.

Jan 1, 1974

By G. W. Reimers, S. E. Khalafalla

A colloidal solution of a ferrimagnetic material, such as magnetite, in a liquid that is immiscible with and lighter than water is projected for use in selective separation of particles according to their density spectrum. Magnetic levitation forces can be created as an antigravity field when the fluid is properly placed in an inhomogeneous magnetic field. When the gradient of the magnetic field is directed downwards, the levitation force in the fluid will be in an upward direction to float sinking nonmagnetic bodies by counterbalancing their density mismatch with the magnetic fluid. Several nonmagnetic objects with densities ranging from 2.50 to 11.35-g cm' were made to float or submerge at will in a 0.96-g cm' density fluid placed in vertical magnetic field gradients ranging from 0.1 to 1 kilo-oersted cm-'. The magnetic levitation force in dyne cm' was found to vary linearly as a function of the object-fluid density mismatch with a slope equal to one g, the acceleration due to gravity.

Jan 1, 1974

By J. Donovan Jacobs

Many improvements in the art of underground excavation have appeared during the past two decades. These improvements have been both in methods and in machinery and have resulted in more economical construction of today's tunnels. In the realm of machines, the developments of continuous boring heads for either soft ground or rock, random arm excavators and the sliding tunnel floor (Magic Carpet) have each made contributions toward more rapid tunneling. CONTINUITY OF ADVANCE Tunnel boring machines are often referred to as "continuous excavators". Continuous advance (without cyclical interruptions) has not been achieved, however, in any of the machines now in use. In most rotary-head tunnelers the thrust needed to make the cutters bite into the face is obtained from hydraulic cylinders reacting against anchoring devices held stationary by pads which grip against the sides of the tunnel. With this system the forward motion of the cutting head is continuous only until the propelling cylinders have reached their limit of extension. At this point the grippers must be released, moved forward and reset before a new cycle of advance can be begun. Some machines are built to obtain their propelling thrust from hydraulic cylinders pushing backward against newly-installed rings of tunnel support. This is the customary method for propulsion of shields. With it, each cyclical advance or "shove" must await the erection of a new ring of supports. Faster tunnel driving

Jan 1, 1974

By Charles H. Jacoby

The economic importance of salt domes has been recognized throughout the world primarily because of oil and gas accumulations on their flanks and, to a lesser degree, for the value of their salt and potash. Recently they have become of value as hosts for cavities used to store hydrocarbons. In the near future we believe that their main value will be as a source of geothermal energy. Although tremendous effort has been expended on the understanding of the geology and physical characteristics of the strata intruded by salt domes, relatively little energy has been exerted in the comprehension of the salt dome itself. Salt domes have long been recognized as a geological heat anomaly. With respect to other sedimentary rocks, salt is a good conductor of heat. Expressing values in 10-3 cgs units, sedimentary rocks vary from 1.0 to 8.0; metamorphic rocks from 5.2 to 8.4 and igneous rocks from 3.1 to 9.8. Rock salt in its pure form has a thermal conductivity of 17. (Gussow, 1970). Thus a salt dome (Fig. Ml) can be expected to act as a conduit bringing heat vertically from deep within the Earth's crust. This was, in part, substantiated when in 1958 a horizontal core hole was drilled from within the Avery Island Mine at the 500 foot level. The horizontal hole was started where the ambient temperature of the salt was 74° F. and drilled toward the center of the dome. At the end of this 2,000 foot hole the temperature was 90° F. thus depicting a horizontal temperature gradient of 7° F./1,000 feet. Because this core hole penetrated a shear zone connate water that appeared as a "cold spot" on the temperature gradient, the foregoing data can only be regarded as indicative.

Jan 1, 1974

By Ann G. Kim

Methane in coal constitutes a serious hazard during mining. Draining the methane from large blocks of coal in advance of mining is an effective method of improving the safety and efficiency of coal mining. Because of the similarity of the two gases, drained methane can be recovered and added to pipeline supplies of natural gas. To effectively apply advance drainage techniques and recover drained gas, a gross estimate of the methane content of coal is necessary. Using data from previous investigations, the virgin reserves of the Pittsburgh coal in the central and southwestern parts of Washington County, Pa., are estimated at over 1.5 billion tons, with a methane content of 50 to 100 fts/ton. The Pittsburgh bed in this area of approximately 265 mi2 contains over 130 billion ft3 of methane.

Jan 1, 1974

By H. O. Poppleton

This Bureau of Mines study was made to investigate a possible method for selectively removing the Si02 component of silicate minerals and ores. Of specific interest were aluminum ores and zircon. Methods are described for removing Si02 from these ores as volatile silicon sulfides by treating the ore with sulfur and carbon; with sulfur, carbon, and a reducing gas; or with sulfur compounds and carbon. Comparative results are also given for the desilication of some of the ores with carbon alone to form volatile silicon monoxide. The silica component can be removed partially from bauxites at temperatures above the sublimation temperature of SiS (940° C) by treatment with carbon, sulfur, and methane; however, it is more difficult to remove the silicon from kyanite, manganese silicate, red muds from aluminum processing, kaolinite, lateritic nickel ores, and zircon. Complete desilication requires temperatures ranging from 1,100° C for bauxite to 1,450° C for zircon. Although the high temperatures required and the undesirable metal sulfides produced eliminate practical application of this method using present technology, the Bureau is reporting this data so that they will be available to future investigators.

Jan 1, 1974

By J. J. Cummins

The Bureau of Mines heated at 150° to 350° C for 0.5 to 360. days Green River oil shale that had been previously extracted by benzene to provide information on in situ processing conditions, to determine the effect of low-temperature heating on the unconverted kerogen, and to determine the composition of benzene-soluble thermal products. The methods used in determining the composition of the soluble thermal products consisted of fractionation of the soluble material, elemental analysis of the soluble products, fractionation of the polar resins by ion-exchange chromatography, gas chromatographic analysis of [n]-alkanes3 and mass spectral analysis of the branched plus cyclic alkanes and aromatic oils. The methods used to determine the effect of low-temperature heating on the unconverted kerogen remaining in the oil shale heated residues consisted of carbon-hydrogen analysis, volatile material determination, carbon residue determination, and oxidation rate determination. In general, it was concluded that significant increases in the degradation of kerogen to oil occurred between the temperature range of 250° to 350° C; that the composition of the soluble products depends upon the temperature at which they are formed; and that the [n]-alkanes are pyrolytically degraded from the kerogen structure. In particular, the 250° C heating temperature is beneficial to the formation of branched plus cyclic alkanes. Also, the heated and unconverted oil shale kerogen and the soluble thermal products become more aromatic as the temperature increases from 150° to 350° C.

Jan 1, 1974