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By P. Henning

Rock fall accidents continue to be the main cause of fatal and serious injuries in the mining industry. Although there has been an improvement in the FOG (falls of ground) related fatal and serious injuries over the past few years, the rate is still too high. New technology has made it possible to reduce this rate significantly. FOG accidents imply failure of the support system or the design of the support system in use. In this paper we deal with the latest technology available to assist the mines to reduce the rates of FOG related injuries and fatalities.

Jan 1, 2010

By D. Turnbull, J. E. May

THE (110) [001] texture in silicon iron is of considerable interest both from the technological and scientific points of view. Its occurrence was reported more than 20 years ago.1-4 The texture develops by means of secondary re crystallizatjon5 and can be very strong, that is, greater than 90 pct alignment even thouh the primary re crystallization texture is weak or complex. This behavior is in contradistinction to the face-centered metals which develop their strong secondary recrystalliza-tion texture from a strong primary recrystalliza-tion texture.', The microstructural changes accompanying the (110) [001] texture formation in silicon iron are as follows: When properly prepared cold-rolled sheet (i.e., 0.015 in. thick) is annealed at about 800°C, primary recrystallization occurs and a fairly stable fine-grained primary recrystallized matrix of about 0.02-mm-diam grain size is produced. The material at this stage does not have the strong (110) [110] texture. As the temperature is raised to about 900°C, relatively large grains appear in the finegrained matrix and they grow at the expense of the smaller grains to many times the sheet thickness. In time the complete sample is consumed by these large grains. This process of the growth of relatively few grains (about one in 105 primary grains) at the expense of many grains is called secondary recrystallization. Since all the secondary grains are of essentially (110) [001.] orientation, the strong texture is developed by this secondary recrystallization process. Theories of the (110) [001] texture in polycrystal-line silicon iron have been proposed by Decker and Harker and by Dunn.Decker and Harker have shown that grains initially in the (110) [001] orientation will upon annealing after cold-rolling, re-crystallize back to the initial orientation. To account for the sharp texture in silicon iron they propose that (110) [001] grains become more highly strained than grains in other orientations and therefore recrystallize first. They are then the lowest energy grains and can consume their higher energy neighbors. Grains in orientations other than (110)

Jan 1, 1959

By W. H. MacLean, S. Liaghat

The Key Tuffite is a thick (0.3 m to 6 m) and laterally extensive (-10 km) cherty, sulfide-bearing tuff unit in Archean greenstones in the Matagami mining district in northwestern Quebec. It lies at the contact of the Watson Lake Group and overlying Wabassee Group volcanic rocks, and is host to major Zn-Cu volcanogenic massive sulfide deposits. The tuff component is highly altered and its volcanic precursors are not identifiable by petrographic means. The tuff is mixed with a volcanic exhalative component comprising chert, carbonate and sulfides (pyrite, pyrrhotite, and minor sphalerite and chalcopyrite). The normative mineral composition of the Key Tuffite is 33% quartz, 28% sulfides, 16% sericite, 8070 carbonate, 6% chlorite and 9% other minerals. In the vicinity of the Bell Allard and Orchan mines, the precursor tuff components are identified using immobile major and trace elements, as Watson Lake tholeiitic rhyolite (Zr/Y = 1.5 to 3.5, LaN/ybN = 1.7 to 2.8, SiO2 = 72.5 ± 1.2 wt %, and Wabassee calc-alkaline andesite (Zr/Y = 9, LaN/YbN= 4 to 8, SiO2 = 56% to 65%). Immobile element computation techniques were used to calculate mass additions and losses in the conversion of the tuff to the Key Tuffite. Average net amounts of FeP3 (27% total iron), Si02 (14%), Cao (8%), S and K2 (+ 2%), were added, Nap was removed (-2.8%), and MgO was over-all unchanged. Total net mass change was +63%, which comprises mainly exhalative additions, but also includes changes owing to hydrothermal alteration of the tuff component.

Jan 1, 1992

By Charles W. Dickson

CONTENTS. [ ] I.THE RELATION OF NICKEL TO PYRRHOTITE. Introduction. The Sudbury district is to-day one of the two great sources of nickel in the world. The peculiar geological relations of

Jan 1, 1913

One of the most unusual assignments in the his¬tory of Loffland Bros. Co. is now in progress with the drilling of a 72-in. diam. shaft in Nevada for the United States Atomic Energy Commission. Projected depth being 3200 ft, by volume, this is the same as a 216,672-ft hole 83/4 in. in diam. Every aspect of the operation is king-sized. The 15,000-lb bit moves into position over the well on a specially-made railroad car riding on rails 14 ft apart. The single drill collar weighs 300,000 lb, is 60 in. in diam., and 43 ft long. The drill pipe is 133/s-in. 72-in. N-80 casing fabricated with special tool joints. The bit chews up 1.05 cu yd of rock for every ft of penetration (This is equal to the volume of 67.71 ft of 83/4-in. hole.

Jan 9, 1964

By Guojun Ma

The entrainment of charge materials, evaporation or volatilization of elements and ejection of slag and metal by spitting or the bursting of gas bubbles are mechanisms whereby stainless steel plant dust are generated from the electric arc furnace and refining converter. TCLP and ASTM D 3987-85 tests on dust that was collected from the baghouse filter system of a South African Stainless Steel plant showed that this dust can be considered hazardous according to South African legislation, due to the high degree of Cr (VI) leachability (~13mg/l for TCLP and ~8mg/l for ASTM vs. regulation threshold of 0.05mg/l in drinking water). The dust is therefore considered to be harmful to both the environment and human health, due to its high solubility in water and carcinogenic properties. It should therefore be treated before being stockpiled or land filled. This paper consequently describes an investigation into the formation of Cr(VI)-containing stainless steel plant dust and the stabilisation thereof in a sintering process, whereby the dust was mixed with a silica-rich clay. It is postulated that Cr(VI) form when the (Mg,Fe,Mn,Cr)3O4spinel phase, CaO, Ca(OH)2 and CaF2 (all of which are present in the dust) react. This reaction was found to take place both at ambient and at high temperatures (1100°C). Stabilization of Cr(VI) in the dust could be achieved at an optimum sintering temperature of 1100°C for a 50mass% dust : 50mass% clay mixture. Chromium emission during the sintering process was found to be low, and within environmental limits.

Jan 1, 2006

By Sijing Cai, Chengpu Zhou

The requirement of mineral resources is increasing as the economy is continually increasing in China. The mining practices of various complex sulphide deposits and precious metal deposits, and the treatment of mine tailings and other industrial solid wastes, have greatly improved fill quality in the metal mines. From early-1980s, high density slurry fill, paste fill of total tailings, low density slurry fill with addition of silicate gelling agent, etc has been studied and applied, and some progress has been achieved. Today, mine tailings, slag and power plant ash are widely used as fill materials in mining. A number of cemented fill mines equipped with large capacity trackless mining machines are in production. Recently, The 3rd Chinese National Symposium on Mining with Backfill, 1995 has been held, the progress of fill technology in mines has been exchanged and summarised. In the paper, some aspects of fill technology used in the metal mines of China are briefly introduced and some applications of fill research work are presented.

Jan 1, 1998

By S. H. Penn

Preliminary experimental evidence seems to preclude the use of unlubricated mechanical force drills on the moon. Measured values of the coefficients of friction and adhesion between metallic and nonmetal-lic solids have been shown to increase in an ultra-high vacuum environment. The paucity of real knowledge of the influence of a hard lunar vacuum upon interacting solid surfaces, relegates current proposals to sample the moon with a mechanical force drill, to the equivalent of wildcatting on earth. Within a few years, drilling will be attempted on the lunar surface with tools that have been designed with parameters that are normally considered for most conventional terrestrial drills. Lunar drills must be light in weight, portable, have reasonable penetration rates, low manpower requirements, etc. Although the initial equipment cost is expected to be high, this will probably not be a critical factor. Early lunar drilling will be limited to shallow holes with depths of 10 ft or less. The primary function of these holes will be to furnish samples of lunar surface materials but they may also be utilized for other purposes, such as geophysical experiments. Instruments may be installed in them capable of measuring thermal diffusivity, gamma radiation, etc. As sampling will be the primary objective of the earliest holes, sample contamination is a parameter that effectively excludes such otherwise promising techniques as explosive or plasma jet drilling. The most desirable method is probably some form of mechanical force drilling that has the capability of operating in the extreme lunar thermal environment (125° to 37S°K), high vacuum (10- l3 torr range), and low gravity.

Jan 1, 1968

By D. W. Frommer

Processing nonmagnetic taconites by selective flocculation-desliming and flotation requires large volumes of water. If impounded without treatment, these off-process waters require excessively large areas for containment. To discharge the waste water into natural waterways would contribute to stream pollution and likely would not be permitted. In U.S. Bureau of Mines experiments conducted in the Twin Cities Metallurgy Research Center's 900-lb per hr pilot plant, approximately 85% of water requirements for the flotation-based treatment of a Michigan nonmagnetic taconite were met by reclaimed water. Water reclamation of the off-process streams from flotation was accomplished by controlled additions of lime, sodium carbonate, and a synthetic flocculant to reduce turbidities to 51000 ppm equivalent SiO*, while maintaining a Ca(II) content of =16 ppm in the finished effluent. Flotation concentrates of good quality were obtained using the reclaimed water. The cost of chemicals used in water reclamation was approximately equal to the savings in flotation reagents attributed to recycling of the water. Water quality is perhaps as important to flotation as are the reagents used. The character of water is extremely variable, depending on whether the source is a well, lake, or stream, upon the season and temperature, upon prior use, and upon the character of the watershed. All of these factors influence the water hardness and the quantity of other dissolved inorganic salts, turbidity, dissolved and suspended organic matter, dissolved gases, and pH. Frequently, the differences in water quality can measurably influence flotation selectivity, often to the point of spelling success or failure. Water hardness is particularly troublesome in flotation systems employing fatty acids, but other unrecognized constituents may also contribute to peculiarities in flotation behavior. Furthermore, a given water source may be entirely satisfactory in one flotation system, but entirely inappropriate in another. In recent years, society has given more attention than formerly to water use, even in areas where water is plentiful. However, both the demands of a growing population, with increased per capita needs, and also those of industry must be met. As a result, riparian rights must be negotiated with the appropriate government agency or agencies so that consumption of water is often allocated or otherwise controlled. Furthermore, the disposal of off-process industrial and domestic water is coming under the increasing scrutiny of these same governmental units. In these respects, the mineral industry is no exception, so that conservation, water reclamation, and reuse may be expected to assume increasing importance. In 1932, it was stated that, "water reclamation is generally more expensive than the economy in water and reagents resulting from its use. It is employed only if it is urgent to save water."' The economic aspects of this statement may still be true, but the unrestricted use of water is becoming less and less an option of the user. The purpose of this paper is to discuss an investigation conducted by the U.S. Bureau of Mines (USBM), in which water reclamation and treatment were undertaken to develop procedures for, and to assess the effects of, water reuse on the flotation treatment of nonmagnetic taconites. This investigation is a logical extension of previous work described by the author and associates at the Twin Cities Metallurgy Research Center employing selective flocculation-desliming and anionic flotation of silica from low-grade, nonmagnetic iron ores2,8 The requirements for the selective flocculation-de-sliming and the anionic flotation of silica processes determined the direction of the investigation. Previous studies had indicated that pH levels of about 11.0 and 11.8 were required for selective flocculation and flota-tlon, respectively. The calcium content of the water was believed to be of importance in both of these operations, and since Minneapolis tap water with a Ca(I1) content of about 16 ppm had been successfully used, an attempt was made to reclaim the process water at an equal level of dissolved calcium. Additionally, the objective was to nullify or effectively limit the effects of dispersants and fatty acid residuals from prior stages of processing. Last but not least, the system of water treatment had to have the capability of reducing turbidities to workable levels. With about half of the effluent being derived from the selective flocculation-desliming step and carrying about 25,000 ppm of highly dispersed, suspended fines, this last objective appeared formidable at the outset. Procedures for water reclamation were derived, in part, from well-known mineral dressing practices, from past observations and investigations, and from concepts contained in various pertinent publications on water treatment."c These procedures involved: 1) flocculation with lime and poly electrolyte-type flocculants, 2) lime-soda-ash softening, 3) chemical precipitation, and 4) mineral surface adsorption. Control was exercised at various stages of water reclamation by frequent measurements of Ca(11), pH, and turbidity.

Jan 1, 1971

By F. Hosseini

Shaping of metals by thixoforming relies on the unusual flow behavior of semisolid slurries containing nondendritic solid phase. The Flow behavior of metallic alloys containing both solid and liquid phases is investigated in the low solid fraction range (, 55%). This behavior depends on both the solid fraction and the shear rate. Four different shear rates is applied using back extrusion technique and flow stress versus true strain in different solid fraction is compared. It is well accepted that the flow stress s of alloys in their semi-solid state obeys to a thixotropic behavior, due to agglomeration and dissagglomeration phenomena during forming. The load-displacement curves produced from the tests may show an initial peak, believed to originate from a skeletal structure which rapidly breaks down under shear. Apparent viscosity obtained from this method is compared with other works and the proper power law of pseudo plastic state is introduced.

Oct 1, 2011

By Carlos E. Del Río

"El presente estudio señala las normas que resolverían el problema entre las variaciones de ley y tonelaje del mineral explotado, a partir del establecimiento de la relación matemática económica entre las condiciones de producción actuales y la variante asumida. Como segundo punto, estudia las variaciones posibles de efectuarse en tonelaje y ley a base de una cubicación detallada, mientras que el tercer punto, señala el cálculo de los costos de minado según las condiciones particulares de cada exploración. Este cálculo y su distribución varía gradualmente según los diversos sistemas y quienes los empleen."

Jul 20, 1955

By M. H. Forester, John D. Cooner

ALTHOUGH the unmined anthracite will last for approximately 150 years, most of the thicker and cleaner coal beds have been almost entirely first-mined and pretty well robbed, leaving much of the present and future production to come from thin and dirtier beds. Herewith is a section of one of the dirty beds being mined in the Wyoming region [ ] This section shows that 45.8 per cent of the bed is made up of impurities and that the 45 in. of coal in the bed is in five benches, the thickest of which is 19 in. In some localities of the anthracite region there are 14 beds of minable coal. Orderly and proper mining of the coal makes it necessary to rob or second-mine--almost all beds have already been first-mined-in sequence from the top downward. Therefore the robbing of the few remaining portions of the thicker and cleaner beds is in many instances being held up by the mining of the overlying thin and dirtier coal beds. Impurities Impurities consist of fire clay, slate, rock, and bone. The latter, which is black, contains 40 to 60 per cent carbon and often resembles good coal. In some beds there are also bands of "blue" coal, which, as the name implies,

Jan 1, 1950

By T. K. Perkins, O. C. Johnston

Because of the influence of dispersion on miscible-displacement processes, diffusion and dispersion phenomena in parous rocks are of current interest in the oil industry. This paper reviews and summarizes a great deal of pertinent information from the literature. Porous media (both unconsolidated packs and consolidated rocks) can be visualized as a network of flow chambers, having random size and flow conductivity, connected together by openings of smaller size. In such a porous medium, the apparent diffusion coefficient D is less than the molecular diffusion coefficient Do, as measured in the absence of a porous medium. For packs of unconsolidated granular material the ratio D/D, is about 0.6 to 0.7. For all porous rocks, both cemented and unconsolidated, the ratio of diffusion coefficients can also be represented as D/Do = 1/FF where F is the for- mation electrical resistivity' factor and 4 is the porosity. If fluids are flowing through the porous medium, dispersion may be greater than that due to diffusion alone. At moderate flow rates the porous medium will create a slightly asymmetrical mix zone (trailing edge stretched out), with the longitudinal dispersion coefficient approximately proportional to the first power of average fluid velocity (if composition is nearly equalized in pore spaces by diffusion). If the velocity in interstices is large enough, there will be insufficient time for diffusion to equalize concentration within pore spaces. In this region, longitudinal dispersion increases more rapidly than fluid velocity. At low velocities in interstices, transverse dispersion is characterized by a region in which transverse diffusion dominates. If the fluid velocity gets high enough, there will be a transition into a region where there is stream splitting with mass transfer but with insufficient residence time to completely damp-out concentration variations within pore spaces. There are several variables that must be con- trolled to get consistent longitudinal and transverse dispersion results, viz., (1) edge effect in packed tubes, (2) particle size distribution, (3) particle shape, (4) packing or permeability heterogeneities, (5) viscosity ratios, (6) gravity forces, (7) amount of turbulence, and (8) effect of an immobile phase. INTRODUCTION Diffusion and dispersion in porous rocks are of current interest to the oil industry. This interest arises because of the influence of dispersion on miscible-displacement processes. In a recovery process utilizing a zone of miscible fluid, there is the possibility of losing miscibility by dissipating the miscible fluid or by channeling or "fingering" through the miscible zone. Diffusion and dispersion are two of the mechanisms that may lead to mixing and dissipation of the slug. On the other hand, dispersion may tend to damp-out viscous fingers which may be channeling through the miscible slug. 58 Hence, dispersion may be detrimental or beneficial (if it prevents fingering through the miscible zone). Therefore, it is doubly important that we understand these processes. In this paper we review, summarize and interpret a great deal of information from the literature. In particular, we will briefly discuss molecular diffusion in miscible fluids. Then we will discuss what differences to expect for diffusion in a porous rock. If there is movement of the fluid through the rock, then there may be an additional mixing or "dispersion". Furthermore, the dispersion longitudinally (in the direction of gross fluid movement) and transverse to the direction of fluid movement will not be equal. We will discuss both types of dispersion as well as several variables which can affect dispersion (viscosity differences, density differences, turbulence, heterogeneity of media, etc.). This group of variables has sometimes led to difficulty when comparing literature data. DIFFUSION OF MISCIBLE FLUIDS If two miscible fluids are in contact, with an initially sharp interface, they will slowly diffuse into one another. As time passes, the sharp interface between the two fluids will become a diffuse

By Szymanski J, Planeta S

For many hard rock mines with near surface deposits, the surface crown pillars form the first line of protection for the immediate underground workings. Underground stopes are typically contained by crown pillar, which protects the level above, rib pillars, and a sill pillar through which the ore collection system is cut. This paper discusses the mining of these pillars, with particular emphasis on the overall stability of the mined out upper part of the mine areas. An area of interest is located in the Canadian Shield, where the mining has progressed below four thousand foot level in the ultramafic high grade sulphide type of orebody.

Jan 1, 1995

By Peter K. Mathison

The U. S. Department of Interior, Bureau of Mines (Bureau) is developing a hydrologic monitoring system for in situ leaching operations. A working prototype of this system was installed and tested at the Cyprus Casa Grande copper mine. Requirements specific to in situ leaching operations were identified by researchers. The system has been a useful tool for researchers and for mine personnel. Observations of the hydrologic monitoring system, including details of the development process, the design of the system, and the software developed at the Bureau have resulted in new ideas for an enhanced design of the system.

Jan 1, 1992

By G. G. Marino

Little comprehensive information has been reported on the behavior of room-and-pillar mines. The objective of this paper is to present case data on mine failures in the Illinois basin for use in practice. Presented are results of an ongoing study and details on the site characteristics of cases where sags have developed on the surface. Site data are reported to show the geologic, mining, and sag conditions that existed. Sags mainly develop from pillar, floor, or pillar-floor failure. The character of the sags depends upon the type of mine failure as well as the overburden response.

Jan 1, 1989

In any earth-moving operation, more profit may be earned or lost by equipment scheduling than by any other single facet of the project. Many now-defunct earth movers would have survived the cost-profit squeeze had they followed an efficient, cost saving, equipment scheduling program. The ideal program would have every item of the equipment fleet working all of the time. In practice this ideal situation is not possible. Several basic methods of equipment scheduling, with an infinite number of minor variations, are used. The first approach is the use of a "minimum equipment fleet," of which all items or equipment are scheduled each working shift.

Jan 10, 1967

Opencast blasting is notoriously subject to variable blasting conditions, some of which are related to changes in ground conditions and some to human and equipment factors. As drilling and blasting constitute a high proportion of working costs, control in this area is crucial for good management. During a recent exercise, wireline logging of blastholes was shown to have the potential to provide invaluable data for optimising blasting control and design. The paper reports on the exercise undertaken, showing that serious misconceptions as to the borehole diameters, explosive densities and posi- tions of decking were quickly corrected using the method. Potential use in blast design is discussed, as are the cost implications.

Jan 1, 1988

By McKenzie C. K

During a programme of explosive performance evaluation at Hamersley Iron, Mount Tom Price Mining Operations, the relative performances of a range of heavy ANFO explosives were compared during normal production blasting operations. In addition, a number of heavily instrumented single hole blasting trials were conducted with each product type. The blasts were monitored in terms of blasthole velocity of detonation (VOD), measured using multi-point plasma conductivity probes with up to 16 measurements per blasthole. Up to 16 blastholes were monitored in each production blast. The results of measurements show a marked difference in performance of all heavy ANFO products between single blastholes and full production blasts, indicating a significant degree of interaction between blastholes in production blasting. The interaction is shown to result in a loss of detonation pressure of explosive, and considered to lead to a loss of fragmentation. The degree of interaction is seen to increase with increasing emulsion content in the products, and is more pronounced in some explosive types than others. The paper presents the methods of measurement and analysis, and the results of monitoring, together with implications on blast design and application of heavy ANFO products.

Jan 1, 1990

This paper describes a mine truck hauling process called "Truck Jigging" which is currently the subject of a process patent application.The investigation explores the production and cost advantages of using the potential energy available in a descending haul truck to assist in elevating an ascending vehicle. Applications are studied for both strip cut mines and open pit operations. Various mechanical connections between the two vehicles are considered, based on a pulley mounted rope system. Fifteen year operating cost estimates show savings of up to 26.5 percent over conventional mine truck operations.

Jan 1, 1989