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By Arnold O. Tanner

The domestic mining industry continued to be strengthened and revitalized in 1989. The healthy conditions and the industry comeback that began in 1987 continued to spread and became more established for many commodities. Relatively comfortable and stable commodity prices, still found predominantly in the metals sector, reinforced other operational factors in bringing vitality to the mining and mineral processing industries. New streamlined business practices, mine and plant modernizations, and the progressive use of new technologies successfully helped lower operating costs and increase efficiency during the past 5 to 7 years. An element common to these three factors of industry renewal and growth was the ever-increasing infusion of and growing dependence on constantly advancing computer technology applications. This trend of increasing computerization was occurring throughout the mining and mineral processing business while it similarly was in most facets of modern business and culture. Some commodities and companies still struggled to outlive sluggish prices and other unstable market conditions or to modernize their businesses, but increases in productivity and profits were more common. A trend toward increased mechanical excavation in nonsoil materials was beginning to surface as a substitute for standard cyclic mine development techniques, such as drill-and-blast and surface shovel-and-truck routines. More continuous mechanical excavation offered the potential for increased production, fewer people at the working face, better ground control, and generally improved safety. The main limitation was rock hardness. The construction industry had already recognized the benefits of tunnel-boring machines for long underground drives and mechanical planers for pavement removal. The Colorado School of Mines held a short course during the year entitled, "Mechanical Excavation Techniques in Mine Development and Production,'" which was at-tended by nearly 100 engineers from 12 countries. The consensus of attendees was that for the most efficient use of these machines and techniques, new mining plans needed to be developed beyond the simple adaptation of those excavators to existing mine plans.1

Jan 1, 1991

By Hara Y, Arino S, Nakamura M, Tachimori M

The theoretical and experimental studies have been done to clarify the hearth flow of iron and slag. The results of dissections show that the hearth can be treated as a packed bed of coke hav- ing good permeability with a coke-free layer at the bottom of the hearth. 3-dimensional numerical calculations of hearth flow with and without a coke-free layer are carried out, and the results are assured by a water model simulation. The influences of a coke-free layer on the iron flow and the discharge route of iron and slag are examined. The 3-dimensional flow pattern can be represented simply by the travelling time, which depends on characteristically the profile of coke-free layer and the quantity of iron in the hearth. Those flow parameters could be obtained by the results of radioisotope tracer test ( Co for iron flow, and Sc for slag flow) at several furnaces. As a result, it is found that the coke-free layer repeats the cycle of appearance and disappearance at several-month intervals. This cycle corres- ponds to large temperature fluctuation at the bottom of hearth. The relation between iron flow and skull (solidified iron, coke and deposited graphite mixed layer) on the hearth brick was studied by the model experiment and the thermal analysis based on the indications of thermocouples installed in the bottom of the hearth. If a thin coke-free layer is formed on the skull, a fast iron flow is generated in the layer, and melts away the skull. The growth and melting of skull produces the fluctuation of thermal load on a bottom brick, causing brick Damage.

Jan 1, 1981

By Gilbert L. Eggert

The effects of reactor irradiation on age hardening in a Cu-2 wt pct Be alloy have been investigated in two neutron-energy ranges. During some of the irradiations, specimens were exposed to high-energy fission neutrons which passed through a boron-10 shield; during other bombardments, the boron-10 was omitted and specimens were irradiated in a reactor thermal column, or the fuel configuration was modified to increase the thermal-neutron flux at a location in the core. Differences in length, X-ray diffraction angle, and hardness indicated that low-energy neutron irradiation made a small contribution to changes in the measured properties. The influence of defects generated by knock-om with less than the Brinkman critical energy or by prompt (n,y) recoil is suggested as the cause of this effect. EXPERIMENTS designed to test the effects of reactor irradiation on the properties of age-hardening alloys have to the present time employed fluxes un-differentiated according to neutron energy. Billing-ton and Siegell in 1950 were the first to perform such an experiment and to compare the results with those obtained by thermal aging. These authors concluded that precipitation in a Cu-2 wt pct Be alloy was not enhanced by the radiation. However, 4 years later, Murray and Taylor,2 working with specimens of the same Cu-2 wt pct Be alloy, reported that an increase in density, hardness, and resistivity which followed reactor irradiation resembled changes associated with thermal aging at about 100°C. (It should be noted that these authors reported that higher aging temperatures caused a decrease in resistivity.) cupp3 reported hardness results similar to those of Murray and Taylor. Koppenaal4 showed that irradiation-enhanced precipitation and irradiation defect hardening were not simply additive but that they acted separately in an irradiated alloy. Kernohan et a1.,5 working with Ni-Be, offered evidence that beryllium was removed from solid solution by reactor irradiation and suggested that the mechanism was one of increased diffusion through the use of vacancies in the structure. piercy6 also found that more precipitate particles were formed by fission-neutron irradiation of a Cu-Co alloy which contained a small amount of particles before irradiation. He proposed that the additional particles were caused by an appreciable amount of diffusion during the final cooling of displacement spikes. The retrogression of extant precipitate particles found by Murray and Taylor2 and Boltax7 as well as piercy6 indicated that nuclei were dissolved within a high-energy spike region and, upon resolidification of the perturbed volume, new nuclei precipitate and grow by enhanced diffusion. Bleiberg et al.' and Konobeevski et al.' explained phase changes obtained by irradiating fissionable alloys in terms of retrogression and re-precipitation in regions of high-energy spikes. Parsons and Balluffi10 used electron microscopy to verify that crystallization did indeed occur in displacement spikes which were formed in amorphous germanium by fast-neutron irradiation. The concept that low-energy neutron irradiation might cause structure-sensitive property changes in semiconductors by atomic recoil associated with the (n, y) reaction was first proposed by Schweinler" and walker." This thesis was tested by Cleland and crawford" and found to be valid. Coltman et al.14 exposed a variety of pure metals to thermal-neutron irradiation at cryogenic temperatures and attributed the resulting resistivity changes to the action of defects created by (n, y) recoil. The present work was undertaken to extend the concepts of Schweinler," walker," and Coltman et al.I4 to the case of an age-hardening alloy and to determine whether or not the action of defects produced by thermal-neutron irradiation would en-hance age hardening. EXPERIMENTAL PROCEDURE Omeea West Reactor Irradiations.* Thermal-

Jan 1, 1965

Coal cleat and faulting influence failure, gas release, and choice of preferred mining directions, locations, and sequences. Unfortunately soil and younger rock cover restrict direct mapping of these structures ahead of mining operations. Aerial photographs of cover contain indirect indications of concealed structures in arrays of linear photostructures. These arrays are commonly too complex for interpretation by simple visual inspection.Analytical techniques applicable to complex arrays are illustrated for a covered part of the Galilee Coal Basin, Queensland. These techniques are: optical determination of sets in arrays of photostructures; correlation of these sets with sub-surface structures; filtering of m-rays for particular sets; detection of anomalies associated with concealed structures in the density distributions of particular sets; fitting filtered arrays to trajectories; correlation of trajectories with the regional directional variations of concealed structures; contouring of ratios of sets to discriminate anomalies associated with concealed fractures and variations in the total and bed thicknesses of cover; kinematic and dynamic inference on the basis of fracture-trace angular and spatial relationships.

Jan 1, 1979

By Frederick C. Tompkins

A complete service system was established for the monitoring of personnel exposure to N02 based upon the use of passive dosimetry. This system is structured such that minimum effort is required of the user: manufacturing, analysis, reporting, and record keeping functions are provided by the service organization. A field evaluation program was carried out in a dieselized mine to assess the performance of two passive dosimeters, the Walden GASBADGE TM dosimeter, and a tubular dosimeter developed at New York University. Side-by-side comparisons were carried out to evaluate dosimeter suitability for monitoring in the field, and to assess relative accuracy characteristics.

Jan 1, 1976

By Rüdiger Wunsch

The new high speed Vienna - St.Pölten line and the Lainzer tunnel are to be connected to the existing Western railway line in Vienna. This involves building an underground cut and cover branching tunnel which will be connected to the Western railway line by ramps. A key structure is the Herzmansky Street tunnel, which has a length of some 820m. It is to be constructed as a cut and cover tunnel using the top down method. The walls of the tunnel are designed as a water resistant structure consisting of double walls, an outer wall of bored piles and an inner reinforced concrete wall. The bored pile wall will be used as a temporary retaining wall during the construction phase and will also be a structural part of the per­manent tunnel wall. The retaining walls of the open pit, which will have a depth of up to 14m and a width of 12m, were investigated as a non-contiguous bored pile wall and overlapped bored pile wall. Preventing ground water from penetrating into the pit is of paramount importance. The high ground wa­ter level is the determining factor for the dimensioning of the bored pile wall and results in the require­ment for a water resistant concrete structure. It has been necessary to adopt adequate measures, therefore, in order to reduce the hydrostatic water pressure during the construction phase, assuming economical pile dimensions.

Jan 1, 2000

By Fazel G. Jahromi, Ahmad Ghahreman

"Atmospheric leaching of arsenical sulfide concentrates, and especially enargite leaching, is one of the major challenges within the current hydrometallurgy research area. One of the recent processes developed for sulfide ore treatment is atmospheric leaching in the presence of AF 5, a novel carbon based catalyst, in chloride media. The quantification of different ion concentrations during enargite and chalcopyrite leaching in the presence of AF 5 were measured and the copper recovery rates of 97% and 96% were achieved. The objective of this study is to shed light on the leaching mechanism of the sulfide minerals. Based on the speciation of iron and copper by different titration methods, the AF 5 catalyst first reduced ferric and cupric ions and then oxidized ferrous, cuprous and arsenite ions. The oxidation behavior of the catalyst enhanced the leaching results. The AF 5 catalyst also caused in situ precipitation of scorodite in leaching experiment. The speciation of ions in the chloride media were simulated by Phreeqc software and the dominant species in the leaching solution were determined.INTRODUCTION The hydrometallurgy of copper has been used for several decades and is still under development for more complex copper sulfide minerals due to their refractory nature. Most of the world copper reserves are in the form of chalcopyrite; and enargite is known as a major contaminant. Pyrometallurgical processing of enargite is problematic due to arsenic release and tight environmental regulations (Peacey, Gupta, and Ford n.d.). On the other hand, lower recoveries in the hydrometallurgical processes make most of these processes impractical. Several leaching processes have been developed for the leaching of copper sulfide minerals. Some of the common treatment methods for copper sulfide minerals are pressure oxidation leaching (POX), CESL, Activox, Albion process, atmospheric ferric sulfate leaching, Dynatec, Galvanox, and Hydro copper process (Barr, Defreyne, and Mayhew 2005; Conner and Anderson 2013; D.G. Dixon, Mayne, and Baxter 2008; Hyvärinen and Hämäläinen 2005; Palmer and Johnson 2005; Rohner, Bartsch, and Ngoviky 2012). Generally it is not viable to dissolve copper sulfide minerals at ambient pressure in mild acidic media and dissolution of these refractory minerals requires harsh conditions in the presence of oxidant materials (Biswas and Davenport 2002). Ferric ions have been used as an oxidant in different media in copper sulfide leaching processes. U. S. Bureau of Mines’ Reno Metallurgy Research Center in 1969 (Haver and Wong 1971) investigated ferric chloride leaching of chalcopyrite. Dutrizac and Macdonald (1972) studied ferric sulfate leaching of enargite. Based on this study, 50% of the copper was recovered at 80-85 ºC after 7 days of leaching. Cupric ions can also be used as an oxidant. Parker, Paul, and Power (1981) stated that cupric/cuprous couples are more effective than ferric/ferrous couples in chloride media because they are rapid and reversible. The Hydro Copper process leaches copper sulfide minerals in chloride solution catalyzed by cupric ions. In this process, copper dissolves as cuprous ions in presence of cupric ions (about 10 g/L) (Hyvärinen and Hämäläinen 2005)."

Jan 1, 2017

By S. Gallagher, A. Mayton

Introduction The mining industry has long been associated with a high incidence of low back disorders and pain (Klein et al. 1984, Leigh and Sheetz 1989, Brinckmann et al. 1998). It is believed that the higher incidence of these injuries among miners is the result of high exposures to postural demands, heavy manual work, and exposure to whole-body vibration (WBV). Recent work has indicated that miners involved with heavy lifting (especially in restricted spaces or on uneven ground) or who have been exposed to whole-body vibration in undamped seats experience noticeable changes in their spines that are consistent with degeneration of the intervetebral discs of the spine (Brinckmann et al. 1998). As will be described shortly, there is mounting evidence that disc degeneration plays a large role in the development of low back pain, particularly chronic back pain. Until fairly recently, medical doctors generally assumed that back pain was the result of muscle strain, ligament pain, or so-called “trigger points” (Bogduk, 1997). However, research supporting these mechanisms of pain has been very scant. When subjected to scientific scrutiny, none of these mechanisms has been shown to relate to back pain in a convincing manner. On the other hand, there are three mechanisms that have been shown to be highly associated with back pain in controlled scientific studies: sacroiliac pain (present in 13% of back pain sufferers) (Maigne et al. 1996), facet joint pain (present in 15 % of back pain sufferers) (Schwarzer et al 1994), and disc disruption and degeneration (present in 39% of chronic back pain sufferers) (Moneta et al. 1994). The latter mechanism, which bears the highest relationship to back pain that has been objectively demonstrated, will be the focus of this section. Scientists now believe they have a good idea how back pain may develop in cases involving disc disruption and degeneration (Bogduk 1997). As the spine experiences loading during lifting tasks or whole body vibration, the first structure to fail is called the vertebral endplate, which is a structure that attaches the disc of the spine to the vertebral body (Figure 1). The endplate typically experiences a fracture, which the body will attempt to heal by means of scar tissue. Unfortunately, this scar tissue impedes the flow of nutrition to the disc itself (discs are dependent on nutrition from the vertebral bones), and if the supply is reduced sufficiently, the disc will start to degenerate. As this degeneration process proceeds, fissures or tears in the fibers of the disc start to develop. If any of these tears is a grade 3 fissure (Figure 2), an inflammatory response occurs in the disc, which will lead to the well-known sensation of low back pain (Peng 2006).

Jan 1, 2007

By Thomas M. Barczak

State-of-the-art longwall roof supports provide effective strata control, but failures of these support systems still occur. To identify failure mechanisms and the impact these failures have on the safety of the support system, the U.S. Bureau of Mines has been conducting research on shield mechanics in the Bureau's unique mine roof simulator, as well as field studies of in situ support loading and investigations of longwall failures, Three types of failures are discussed: (1) inadequate support capacity, (2) structural failure, and (3) instability. Hypothetical situations with proposed courses of action and case studies of actual longwall failures are described. This information is intended to assist the Mine Safety and Health Administration (MSEIA) and industry mining personnel in safety evaluations of longwall roof support systems.

Jan 1, 1989

By Chi-Mun Song, Seok-Hyun Choi, Seok-In Hong, Han-Kee Jang

Accurate measurement and evaluation of hand-transmitted vibration from a power tool is an important issue for tool manufacturers, because they are obliged to develop low-hazard power tools for workers. The International Standard ISO 5349(1) dictates a systematic procedure for the measurement and evaluation of hand-transmitted vibration. However, the uncertainty in this measurement is too large for manufacturers to apply such data to the design and modification of power tools. There can be several sources of this uncertainty in such measurements; e.g., operator-dependent, power tool-dependent, and operational conditions (see Table 1). For a manufacturer to characterize the exposure of a power tool’s use to a given level of vibration, the relationship between these uncertainty factors and the measured vibration must be elucidated. In this study, we investigated the effect of several factors on the uncertainty in measurements. [ ] Methods In this study, some of the factors in Table 1 were selected for examination, and their effect on the measured variation was quantitatively investigated. Three tools from the same manufacturer were sampled at random in our experiments, and each of five of the same type of insert (disks or tips) was installed into each tool. Although each of the tools and inserts were of the same design and were made by the same production process, they differed from one to another, which can be a source of the variation in the measured vibration. Three human subjects participated in our experiments, which were carried out as stated in ISO 5349. The subjects were asked to maintain their posture, and the applied force was kept as constant as possible. The applied force was monitored using an indirect method, where vibration energy was displayed in real time during the experiment using a three-axis accelerometer attached to the work piece at a specified point. The appropriate range of the applied force was predetermined to cover the range of real work operations. The engineering tolerance between the inner diameter of a grit disk and the outer diameter of the tool shaft leads to an eccentricity of the mass at the center of the disk. The degree of eccentricity varies with installation, and this is another source of uncertainty. In our study, the effect of this eccentricity was investigated by carrying out repeated assembly and disassembly of an insert.

Jan 6, 2006

By Langtry E. Lynd

The titanium industry is based on the unique properties of titanium dioxide and titanium metal. Because of its whiteness, high refractive index and resulting light scattering ability, titanium dioxide in its two main allotropic forms, rutile and anatase, is the predominant white pigment for paints, paper, plastics, rubber, and various other materials. Titanium metal, because of its high strength/weight ratio and resistance to corrosion, is widely used for aircraft, both in airframes and engines, for powerplant surface condensers, and a wide variety of chemical processing and handling equipment. U.S. production of titanium dioxide pigment in 1979 was about 658,000 tons - 2/, valued at about $770 million. Net shipments of titanium mill products were around 19,000 tons, worth about $380 million. These two major uses account for over 96% of domestic titanium consumption. The third largest application, the use of rutile for coating welding rods, required about 9,500 tons of rutile concentrate, worth about $4 million. Other applications of titanium-bearing raw materials include the manufacture of titanium carbides, ceramics, and chemicals, and the recently developed use of ilmenite as a substitute for barite in well-drilling muds.

Jan 1, 1980

By Veena Sahajwalla

The cupola furnace is a coke-fueled shaft furnace used as a primary melting unit in iron foundries. Control of chemical composition of the iron tapped from the cupola is a key factor in productivity and quality control. In an effort to develop a control model for the cupola, a fundamental approach based on physical and chemical principles has been taken to describe the melting process. The behavior of oxidation of the solid charge in the stack of the cupola has been studied. Sulfidation of the charge materials by sulfur-bearing components released to the furnace gases from the coke has been described. Carburization of metal droplets of iron and of steel in separate molten streams has been characterized. Finally, reactions with alloying elements in the hearth (well) of the furnace have been defined. These reactions have been described in a computer-implemented model developed to predict the composition of the iron tapped from the cupola. The model has utilized the thermodynamics and kinetics of the oxidation, sulfidation, and carburization reactions, including temperature and physical aspects, in the various zones of the melting unit. The model predictions have been compared favorably with operating results.

Jan 1, 1992

By Jennings S. Cox

(Glen Summit Meeting, June, 1911.) THE following notes, prepared in 1908, as the result of a personal examination and extensive explorations under my direction in 1906, have been revised and greatly augmented after two subsequent visits and further explorations in 191.0. The hard iron-ores of the south coast of Oriente Province, in the island of Cuba, have been known for many years, in fact one mine has been in operation for more than 20 years ; but it is only within the past four years that the large mantle-deposits of brown ores of the north coast have attracted serious attention. A. C. Spencer 1 has described these ores in a paper, entitled Three Deposits of Iron Ore in Cuba, which refers to the Mayari, Moa, and Cubitas deposits. C. M. Weld,2 in a scholarly paper on The Residual Brown Iron-Ores of Cuba, has discussed the character and possible genesis of these deposits with particular reference to the Moa field, calling attention also to the Taco and Navas fields in addition to those described by Spencer. Descriptive articles with reference to the Mayari field, and a few words about the Moa deposit, have also appeared.3 It is the purpose of the present paper to give some account of the exploration of the Moa deposit and to call attention to its commercial importance. LOCATION. The Moa district is situated on the north coast of the . Province of Oriente, which is the most easterly province of the island of Cuba. It lies on the northern or seaward slope of 1 Bulletin No. 340, U. S. Geological Survey, pp. 318 to 329 (1908). 2 Trans., xl., 299 to 312 (1910). 3 Iron Age, vol. lxxx., No. 7, pp. 421 to 426 (Aug. 15, 1907), and vol. lxxxi., No. 15, pp. 1149 to 1157 (April 9, 1908).

Mar 1, 1911

By J Karlovšek

Civil engineering infrastructures are often subjected to different types of natural and mechanical activities. These influences may result in serviceability or even in stability of structures due to material deformations, increased water content within the materials used or the formation of internal or adjacent cavities that may threaten the infrastructure. Construction practices can lead to development of such defects in the form of cavities. In civil engineering it is crucial to detect these variations in material properties and to detect the presence of defects. However, as they are often hidden from view, these attributes may be difficult or impossible to target with traditional testing methods. For these reasons rapid geophysical methods, such as ground penetrating radar (GPR), are increasingly being used. At the University of Queensland (UQ) GPR is used for detection of voids and cavities which have been caused by an over excavation of the earth pressure balance machine (EPB) operating in a closed mode.A variety of numerical simulations using the finite-difference time-domain (FDTD) methods and preliminary experiments have been carried out in order to specify information about the nature, type, size, location and other characteristics of targets to be detected by GPR. In doing this the difficulty of interpreting GPR data, which is mainly due to the complexity of the factors involved in multiple possible solutions of the observed features, can be overcome.

Mar 8, 2011

By Irving Hartman

The results of the first experimental study by the Bureau of Mines on the explosive properties of metal powders were published in 1945. Since that time the explosibility of numerous other industrial dusts and powders has been investigated. Part of this information has been published, but most of the data has not been released to date. This paper summarizes the results of experiments on 22 samples of titanium, zirconium, thorium, uranium, and hydrides of these metals. The major part of the investigation was made under cooperative agreement with the Atomic Energy Commission.

Jan 1, 1951

By R. Ressel

Keywords: ferrovanadium, thermodynamics, phosphorus Recyclable material is rapidly gaining in importance as a source of raw materials in industrialized countries. This is also the case in the production of ferrovanadium, where, increasingly, materials such as discarded capacitors, spent catalysts, slag, dust and sludge are used. As the V-content in the raw material varies greatly, the demands on process technology are very high. The share of perturbing elements depends very much on the source of the raw materials, which, in turn, makes a corresponding optimization of the various refining steps necessary. The raw materials are mostly available as oxides, which means that carbon, silicon or aluminium are used as reducing agents. Thermodynamic calculations were used to show especially the behavior of vanadium and phosphorus at different process conditions.

Jan 1, 2005

By M. Tangstad, D. Lu, G. Tranell, S. Gaal, J. Safarian

The kinetics of MnO reduction from high carbon ferromanganese slag was investigated using a sessile drop technique at 1600 ºC. The effects of reductant type, ambient atmosphere and slag composition on the MnO reduction were illuminated. Two different types of industrial reductants (ground to a particle size of 44 to 106micron and pressed to pellets) were used as substrates for small slag droplets of varying composition, which were reacted in a CO or Ar atmosphere with the reaction studied in-situ. The cross sections of the reacted slag-carbon samples were subsequently studied by EPMA to find the extent of MnO reduction as a function of reaction time. It was found that the rate of MnO reduction is affected by both the type of reductant, the ambient atmosphere and the presence of metallic components in the slag. Higher reduction rates were obtained for charcoal than for coke as reductant while a CO atmosphere unexpectedly yielded faster MnO reduction than an Ar atmosphere. It was also found that metal prills in the initial slag will increase the rate ofMnO reduction.

Jan 1, 2007

Future metal prices play a direct role in both the economic evaluation and short to medium planning of a mine scheduling sequence. It is difficult to predict with accuracy the future price of volatile metal commodities, however, it is possible to fix some future metal price, outside of long term contracts by the selling of futures contracts through a commodities exchange. The futures contract represents a fixed amount of a specified quality of a commodity for future delivery at a predetermined price. Several different types of hedging are possible, one in particular which is best suited for mining companies. There are relative advantages and disadvantages when trading in futures contracts and particular reference is made to gold contracts on the Sydney Futures Exchange.

Jan 1, 1980

By L. E. Lynd

Ilmenite concentrates prepared from beach and dune sands of Florida, India, Australia, and other localities deviate to varying degrees from the theoretical composition of pure ilmenite, and generally contain more TiO2 than the formula FeTi03 would indicate, and some Fe2O3. This variation in composition is due to different amounts of altered ilmenite in the concentrates. (') The alteration has been shown to take place by oxidation and leaching of the iron in ilmenite, to yield residual products consisting of amaphous or very finely crystalline titanium dioxide and ferric oxide. Other studies(2) have stressed that ilmenite may alter first to an amorphous titanium-iron oxide, or to an amorphous mixture of titanium and iron oxides, with later alteration to crystalline titanium dioxide. There has been some speculation as to whether alteration of ilmenite is usually caused by weathering or by hydrothermal pr0cesses.(3,4,5 Three main methods of approach were used to study the mechanism and rate of ilmenite weathering. (1) Etch tests were used to learn the relationship between crystallographic orientation and the rate of chemical attack on ilmenite. (2) Altered ilmenites in New Jersey sands were compared with ilmenite in rocks of the area from which the sands were probably derived. (3) Experiments were carried out to determine at what rate, and by what agents, originally fresh ilmenite could be altered in the laboratory under simulated weathering conditions. ETCH FIGURES ON ILMENITE CRYSTAL PLANES A rather large ilmenite crystal from Sannidal, Norway, about 11/2 x 11/2 x 2 inches, bearing a few natural faces with imperfect surfaces, was prepared for etching by grinding and polishing crystal planes whose Bravais-Miller indices (referred to hexagonal axes) had been determined by X-ray methods to be 00.1, 10.0, and 10.2. Metallographic examination showed that the crystal was homogeneous, and uniform in orientation, except for the presence of twin lamellae which were oriented with their broadest surfaces parallel to the 00.1 planes of the large crystal. Since ilmenite is rather inert to standard etch reagents, strong solutions of hot sulfuric acid and cold hydrofluoric acid were used. Preliminary tests established that better etch figures were obtained using HF than with H2So4 solutions. The etch figures produced on 00.1 and 01.0 planes of ilmenite by etching 3 to 5 minutes in cold concentrated HF solution are shown in Figures 1, 2, and 3. The figures on 00.1 are "etch hillocks", rather than pits, and according to Honess(6), this phenomenon

Jan 1, 1961

By Yve Potvin, Fabien Miller, Deni Jacob

"The potential benefits of measuring the volume of excavated open stope are enormous. By comparing the actual excavation of the orebody contour, it is possible to determine the “real"" amount of mining dilution, as well as the ore left in place. Noranda Technology Centre (NTC) has developed a stope survey system that allows for rapid and efficency measurement of underground excavation volumes. The system comprises a commercial laser (EDM), a set of lightweight rigid rods, an automated scanning device, a hand-held data logger and Autocad-based software for volume calculation and drawing manipulations. This system is an invaluable tool for the optimization of mining practices and could also be used for the delineation of caving areas. IntroductionDilution is the most common and devastating mine disease. In some instance s it could systematically cripple the profitability of an operation, and in more extreme cases, it could become a terminal disease. The Northern Miner Journal (1988) reported that many operations have closed because of uncontrolled dilution, before they even completed their first year of production. Other studies (Pakalnis, 1986) have shown that approximately 40% of all underground operations have more than 20% dilution. Considering that every ton of dilution costs in the neighbourhood of $25, the total direct cost of dilution to the Canadian mining industry may easily exceed one hundred million dollars per year.The dilution problem has been a major concern to Noranda Minerals for some time and in 1984 a comprehensive geomechanics research program was created at the Noranda Technology Centre (NTC) in Pointe-Claire, Quebec. New empirical stope dimensioning techniques, improved cable bolting techniques and sophisticated ground control instrumentation projects (among others) contributed to improve the situation at Noranda.A new tool which can have a very significant impact on the ""war"" against dilution is being developed by the Noranda Technology Centre. The laser stope survey system allows for a rapid, precise and efficient measurement of underground excavation volumes. By comparing the excavation planned with the volume excavated, it becomes possible to determine the ""real"" amount of mining dilution as well as the amount of ore left in place. This system may also allow for early detection of a dilution problem. As with other diseases, early detection provides the best chance for a fast and total recovery."

Jan 1, 1992