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By Conny Postupack

To make money in mining coal you have to sell it for a lot more than it cost you to get it out of the ground. And yet, every year it cost us more and more to stay inbusiness, while the price we get for coal does not increase at the same rate.

Jan 1, 1990

By J. Esson, R. A. D. Pattrick, M. K. Nimfopoulos, D. A. Polya, K. M. Michailidis

"Economic Mn-oxide ore deposits of commercial grade occur in the Rhodope massif near Kato Nevrokopi in the Drama region, Northern Greece. The Mn-oxide mineralization has developed by weathering of continental hypogene rhodochrosite-sulphide veins. The vein mineralization is con-?ned by tectonic shear zones between marble and metapelites, extending laterally into the marble astabular, pod or lenticular oreshoots (up to 50 m x 20 m x 5-10 m). Supergene oxidation of the hypogene mineralization led to the formation of in-situ residual Mn-oxide ore deposits, and secondary infills of Mn-oxide ore in embryonic and well developed karst cavities.Whole rock geochemical pro?les across mineralized zones con?rm the role of thrusts and faults as solution passageways and stress the importance of these structures in the development of hydrothermal and supergene mineralization at Kato Nevrokopi. Three zones are recognized in the in-situ supergene veins: (A) a stable zone of oxidation, where immobile elements form (or substitute in) stable oxide mineral phases, and mobile elements are leached; (B) a transitional (active) zone in which element behavior is strongly in?uenced by seasonal ?uctuations of the groundwater table and variations in pH-Eh conditions; and (C) a zone of permanent ?ooding, where variations in pH-Eh conditions are minimal. Zone (B) is considered as the source zone for the karst cavity mineralization. During weathering, meteoric waters, which were CO2-rich (PCO2~10-3.8 to 10-1.4) and oxygenated (fO2~10-17 for malachite), percolated downward within the veins, causing breakdown and dissolution of sul?des and marble, and oxidation of rhodochrosite to Mn-oxides. Karst cavity formation was favored by the high permeability along thrust zones. Dissolved Mn2+was transportedinto karst cavities in reduced meteoric waters at the beginning of weathering (pH~4-5), and as Mn(HCO3)2in slightly alkaline groundwaters during advanced weathering (pH~6-8). Mn4+-oxide precipitation took place by fO2increase in ground waters, or pH increase by continuous hydrolysis and carbonate dissolution. In the well developed karst setting, some mobility of elements occurred during and after karst ore formation in the order Na>K>Mg>Sr>Mn>As>Zn>Ba>Al>Fe>Cu>Cd>Pb."

Jan 1, 1997

By Hendrick A. D. Kirsten, A. Clayr Alexander

Stillwater Mining Company is currently developing a second underground palladium and platinum mine approximately 21 km (13 miles) west of their existing Nye operation in the Bear tooth Mountains of southern Montana. Portals for the two access tunnels required at the new site were excavated in limestone talus to accommodate4.6 m (15 feet) diameter tunnel boring machines. A review of the technical design, field conditions and construction of the portals is presented.

Jan 1, 2001

By Árpád B. Palotás, Adel F. Sarofim, John B. Vander Sande, Lenore Rainey Christian, J. Feldermann

"Interest in the fine structure of soots and carbon blacks is motivated by a variety of possible applications. The structure provides information on the origins of the particles and on their adsorptive and reactive properties. This paper describes a method for quantification of the structure of soots and carbon blacks based on direct electron microscopic observation followed by image analysis of these materials. High-resolution transmission electron microscopy (HRTEM) provides a very detailed observation of particle structure. The differences in soot structure, because of its complexity, may not be easily quantifiable with the human eye; therefore, high-level computer software has been used to manipulate HRTEM images. This technique involves the application of fast Fourier transforms (FFT) to single particles and the measurement of characteristic parameters such as interplanar spacings and crystallite sizes from these particles. The methodology and application of this characterization technique are presented here. Results are shown for dif¬ferent samples obtained from soot and carbon black particles selected to illustrate the capabilities of the methodology. Quantitative information can be obtained on structural characteristics, e.g., interplanar spacing, circularity, orientation, elongation, and length distribution of lattice fringes, as well as on the fractional coverage of the extracted pattern. c 1996 Wiley-Liss, Inc.This paper presents a combination of techniques for recognizing and classifying different carbonaceous materials, using their structural morphology. A new method to assess and quantify the parameters which define such structures is proposed and discussed. The technique is based on the use of HRTEM (high-resolution transmission electron microscopy) and computational image analysis.It is well-known that carbonaceous materials like graphite, soots, coals, cokes, chars, etc. possess characteristic structural appearances which can vary from mostly random or amorphous to a perfectly ordered graphitic crystalline structure (Buseck and Bo-Jun, 1985; Buseck et al., 1987). The carbon structure has been variously described as turbostratic (Oberlin, 1989) or as crumpled sheets (Rouzaud et al., 1991) to indicate that parallel layering, reminiscent of graphite, is observed over dimensions of nanometers, but that these planes or crystallites show disorder over larger scales. The degree of order of such structures is strongly dependent on the thermal treatment of the material as well as on the composition of the source of the carbonaceous material. The value of the electron microscope in studying the morphology of such materials has been well-established, and abundant information is available (Ishiguro et al., 1991; Lahaye and Prado, 1978; Buseck, 1992).The use of HRTEM has brought further insight into this matter. Qualitative assessment of the structural order of such materials has been attempted over a long period of time in order to differentiate between various sources or treatments. There is, to date, no successful method available for quantifying the structural characteristics of various carbonaceous materials. This paper presents a technique which is able to recognize dif-ferent materials and to quantify the structural parameters of those materials using HRTEM and computational image analysis, including pattern recognition techniques.In the case of perfectly ordered graphitic crystals, electron diffraction is widely used for obtaining details on structure. Analysis of diffraction patterns can reveal parameters such as interplanar spacing, d002, crystallite size along the c-axis, Lc, crystal size in the plane of the layers, L., mean number of crystallites, Nc, etc.Complicated electron microscopy methods such as defocusing, tilted illumination, axial illumination, etc., often have to be used in order to characterize complex materials such as randomly oriented crystals in soots and carbons. Obtaining the right fo"

Jan 1, 1998

By B. W. Smee

Glacial lake sediments or glaciolacustrine deposits form a significant portion of the Canadian, Scandinavian and Russian landscapes. Furthermore, 50 per cent of the Archean volcanic belts within the Canadian Shield area are covered wholly or in part by these deposits. Because of the high electrical conductivity and low hydraulic conductivity of these compact sediments, the application of geophysical (electrical) and geochemical techniques in such areas becomes a difficult task. The presence of these sediments has therefore hampered exploration for metallic sulphide deposits in some of the most important metallogenic environments of Canada. Similar problems exist in some tropical countries, such as Australia, where the overburden may be very conductive. In this paper, the extent and provenance of the glaciolacustrine deposits within the Canadian Shield are described. The geochemical and geophysical factors that hinder exploration in the clay belts are reviewed, with case histories of successful and unsuccessful applications of some of these techniques. The most successful geochemical technique used within glacial clay belts is the sampling of lodgement till beneath the clay cover, and the analysis of the heavy mineral fraction of that till. Surficial sampling has not been successfully applied. Some geophysical techniques, more specifically electromagnetic and magnetic induced-polarization techniques, have detected mineralization beneath substantially deep clay or saline overburden layers. Some suggestions have been made, such as the use of anions in hydrogeochemical surveys and the use of wide-band multi-frequency EM systems. When implemented, they will hopefully make the current geochemical and geophysical methods more effective in exploration for base metal sulphides within clay-covered terrains.

Jan 1, 1979

By R. F. Favreau, L. C. Lang

"In modern blasting technology blasts are designed and analysed on an energy-mass-time relationship. The energy of the explosive is derived by computer analysis and the work potential of the available energy is expressed in numerical values. The mass involved in the blast is determined by the geometry of the blast and by the rock density. Time is also a relevant parameter, because time is required to complete the three basic stages of the breakage process.For successful application of the blasting parameters the basic mechanism of the breakage process must be understood.The physical-mechanical properties of the rock, local structural geology and the thermodynamic properties of the explosives can be brought together to create a computer model of a blast with which it is possible to predict separately the results of each parameter and to express the predicted degree of change in any parameter by actual numbers.A long-range project has started to create a ""bank"" of rock properties for as many Canadian and foreign mines as possible. A computer model has been successfully applied to predicting the effect of varying the ratio of spacing to burden at constant rock volume and significantly improved results are achieved, as the S/B ratio is increased up to about 2 to 2.5.High-speed photography has been applied to determine the time that has elapsed between zero time and the beginning of movement of the mass. The results assist in determining minimum and optimum delay time required for multiple-row blasting.The approach as described in the paper is now well proven and is clearly superior to previous methods based on powder factors and human assessment."

Jan 1, 1972

By Oliver C. Ralston

[The NOJ'l..metals Division deals wi tt mi:leral n t inte .ded to be used a ra\o,f materials for extraction of metals. ~ _ ereas, a. materinl containing a chromite, if used' for production of c~1r()rrti1..1r.'l ::tetE' .. l or fcrrochromiu"1, 1,oJould be a chromi te ore, if used as 8. rcfrn.cto~J or for prod .1.ction of chromium chemicals, it is a chromi te-beari [. ~?oCl... Li;{eHise, a r:1a&neti te used for production of iron is a metallifero"'..ls ~in8re..i; if used 8.S a water-filtration granule in .:l magne.tically cleaned filter bed, it 'ould be a nonmetallic in-dustrial mineral.]

Jan 1, 1940

By E. W. Parsons

Permanent support of the back is an important economic factor in maintaining a tunnel or other underground opening in condition to render the service for which it was driven. Timber has been most commonly used for support in tunneling and drifting because of its strength and ease of installation. Even when treated for decay, however, timber is subject to deterioration and, over a long period of time, should not be considered a permanent support. Concrete support or lining is permanent and has been used in tunnels of every size for many years but has been almost exclusively cast in place, a difficult, costly process. This report deals with the design and installation of precast concrete supports to combine the best features of both methods.

Jan 1, 1958

By R. B. Ellestad

Introduction Lithium has been known since 1817, when it was discovered by the Swedish chemist, Arfvedson, while working in the laboratory of Berzelius on the chemical analysis of the mineral petalite, LiAl(Si205)2. Development of the chemistry of lithium proceeded slowly, following the early work of Davy, Gmelin, Bunsen, and Matthiessen. Approximately seventy years elapsed before lithium products assumed any commercial importance, and for a considerable period it was a' very minor industry. Their chief early use seems to have been in medicine, and in the production of lithiated water. Other more important uses were gradually discovered, and the industry has had a slow but steady growth. Chemistry Lithium is classified as an alkali metal, along with sodium, potassium, rubidium, and cæsium. Like these, it is a silvery-white metal, which can be cut with a knife; it is harder than sodium, but softer than lead" It is remarkable in having a density of only 0.53 gram per cubic centimeter, which makes it the lightest metal. On ignition in air, it burns intensely to form chiefly lithium monoxide, Li2O. Like the other alkali metals, lithium reacts vigorously with water to form hydrogen and lithium hydroxide. The later is a strong base, and reacts with acids to form salts. The salts of lithium are in general analogous to those of the -other alkalies, but many of them have unique properties. For example, lithium chloride and bromide are extremely hygroscopic, and have a very high water solubility. Lithium fluoride, phosphate, and carbonate, on the other hand, are all relatively insoluble, unlike the corresponding sodium and potassium compounds. In this instance, lithium exhibits its frequent tendency to resemble the alkaline-earth group of elements (calcium, strontium, and barium). Many of the special and valuable properties of lithium are related to the extremely small size of the lithium ion.

Jan 1, 1948

By D. K. Deardorff

The hafnium-vanadium phase diagram was constructed within an estimated accuracy of ± 10° C and ± 2 wt pct composition. Alloys for investigation were melted under an atmosphere of purified helium by nonconsumable tungsten-electrode arc melting on a water-cooled copper hearth. Melting points were determined by optical pyrometer, and the remaining phase relationships were investigated by metallography, thermal analysis, and X-ray diffraction. The existence of a face-centered cubic intermetallic compound HfV2 (a = 7.38 A) was confirmed. A eutectic reaction occurred at 20 wt pct vanadium and 1,395° C to yield HfV2 and 8 solid solution. HfV2 melted incongruently by a peritectic reaction at 1,480° C, and the 3 solid solution decomposed eutectoidally at 1,165° C and 6 wt pct vanadium to yield HfV2 and a solid solution. The eutectoid, the eutectic, and the peritectic isotherms extended from 1 to 36.3 wt pct vanadium, from 8 to 36.3 wt pct vanadium, and from 26 to 89.5 wt pct vanadium, respectively. Terminal solid solubilities of hafnium in vanadium at 1,300° C and of vanadium in hafnium at 1,100° C determined to be about 3 and 1 wt pct, respectively.

Jan 1, 1965

By Zihe Ren, Edouard Asselin, Marcus Tomlinson, Tianbi Zhang, Jing Liu

"Raman spectroscopy is used to quantify the extent of disorder in the carbonaceous matter associated with preg-robbing ores. Previous studies of Goldstrike ores showed that the height and width of the peaks for the “D” (disordered) and “G” (graphite) bands, the so-called “Raman ratio” had a strong correlation to the preg-robbing value (PRV) measured for various ore samples. A brief literature review on Raman spectroscopy as it applies to preg-robbing ores is presented. Further, recent studies, presented here, have shown no correlation between the Raman ratio and the PRV for a wide variety of ores. This suggests that the extent of organic carbon crystal disorder is not the main factor in determining preg-robbing characteristics.INTRODUCTION Valuable base metals, such as nickel, cobalt, molybdenum, vanadium and tungsten, are used in a wide range of important technological applications. The demand for many of these metals has increased significantly over the last few decades, driven especially by economic expansion in Asia generally and China in particular. This has led in turn to a large growth in the output of mines in order to satisfy this increasing demand, as shown by the data in Table 1 (USGS, 1994, 2014). These data reflect an even longer trend of growth of these metals, with nickel, for example, showing an average rate of 5.3% per year from 1980 until 2015 (International Nickel Study Group, 2017). This rapid and sustained rate of growth means that annual mine outputs for nickel, tungsten, molybdenum and vanadium have had to double roughly every 11 to 14 years, whilst cobalt mine output has had to double roughly every 7 years, over the period from 1994 until 2014. With the average working life of a nickel mine being between 17 and 22 years (Statista, 2017), this means that from the time a nickel mine opens until it closes, the industry needs to find the equivalent of another three or four mines of a similar output to satisfy this relentless growth in demand for the metal."

Jan 1, 2017

By Christopher C. Jobes

Computer-aided control of a mining machine requires a guidance system to aid remote positioning of the machine by determining its position and heading. The mechanical position and heading system (MPHS) developed by the U.S. Bureau of Mines provides such navigation information during face maneuvers. This report describes the required theory, which yielded a reliable algorithm for calculating machine position and heading, and implementation of this theory in hardware and software design, which made surface testing of the MPHS possible. Analysis of the errors and test results showed that the MPHS provides reliable results and can, therefore, provide useful guidance information for face navigation.

Jan 1, 2010

By M. Hopf

The use of water-cooled copper components as sidewall elements of submerged arc furnaces and other pyrometallurgical applications has become increasingly common. The high cooling efficiency of copper has made it possible to increase the service life of furnace refractories when compared to conventional refractory linings. However, even the self-healing effect of ?freezing? worn areas of the lining does not necessarily protect the copper coolers against wear or corrosion completely. In order to avoid furnace explosions, various methods have been used to monitor the wear of coolers. Unfortunately, these have not been able consistently to identify localized wear. Thos Begbie (South African) and SAVEWAY (German) jointly developed technology to embed a line sensor into the copper cooler during the casting process. This system allows an exhaustive monitoring of the copper cooler. A SAVELINE sensor is placed inside the copper-cooling panel between the water-cooling passage and the hot face of the panel. The sensor follows the meandering shape of the cooling water channels. In the first instance, the sensor provides analogue information as the thickness of the copper reduces. Secondly, this wear signal will be confirmed by a signal of interruption if the sensor is washed away. Because of the structure of the sensor, a self-diagnosis is possible and indications can be confirmed (double proofed).Subsequent to the manufacture of some test pieces, coolers for a large submerged arc furnace were manufactured. The sensorized coolers have been installed at the intermittent surface (slag line) where the largest amount of corrosion has been encountered. The system has been operating since December 2005 in what is considered one of the largest submerged arc furnaces in South Africa. Keywords: Pyrometallurgy, furnace, copper coolers, freeze lining, monitoring, Saveway

Jan 1, 2006

By H. Russell, N. DePriest, J. D. Quaranta

Valley-fill structures built of blasted rock overburden from Appalachian mountaintop surface mines pose many reclamation challenges. The steep mountainous terrain, short valley lengths, and straight stream channel profiles create significant challenges to implementing fluvial geomorphic landform design in terms of both form and function, and from a safety and constructability perspective. The fluvial geomorphic landform design approach balances erosive and resistive forces by considering long-term climatic conditions, soil types, slope profiles and vegetation types. Commercial geomorphic landform design software tools do not specifically analyze the stability and factor of safety for the computer-designed landform slopes. This research investigated slope stability parameters and factors of safety between a traditional valley-fill design with a geomorphic landform alternative. Slope stability assessments were performed on two profile geometries. Finite-element modeling of a permitted valley-fill and a geomorphic design alternative indicated that slope angle and internal angles of friction associated with the gradation of the overburden greatly affected the designed factor of safety for both designs. The geomorphic designed slopes yielded the highest factors of safety out of 14 models analyzed with all cases having factors of safety over 2.0. The high factors of safety are attributed to shallow slopes and beneficial surface and internal drainage.

Jan 1, 2014

By John M. Dale

Sulfur is a plentiful, low cost, unique material whose physical properties can be altered and employed in structural applications. This program was undertaken to develop an optimum sulfur based formulation for use as a coating to both seal and support mine walls. The initial effort in the program was devoted to a laboratory study of the physical and mechanical properties of a variety of sulfur base coatings that were specifically formulated for this application. Concurrent with formulation development, laboratory equipment and techniques were developed for spray applying the sulfur based coatings to the ceiling and walls of a structure that simulated the interior of a mine. Much of the formulation work was guided by the experiences encountered when attempting to spray the formulations overhead. One hundred parts of sulfur modified with 10 parts of talc, 3 parts of milled glass fiber, and 2 parts of dicyclopentadiene was found to be a fire retarded, low odor, low eye irritation, sprayable formulation for sealing and strengthening mini, walls. An invention disclosure on this formulation was submitted to the Bureau of Mines and a patent application was filed. Various mineral samples were obtained and adhesive strengths of the formulation to these samples in both the wet and dry state were measured. With the development of an attractive sulfur based coating material, attention was directed to the design, fabrication, and testing of a portable spray application unit so that coatings might be applied in the field to various rock surfaces and earth formations for further evaluation. The unit was fabricated in the Southwest Research Institute shop. Once operational, the unit's capabilities were field tested and demonstrated at three separate locations. Upon completion of the field testing, the unit was shipped to the Spokane Mining Research Center where Bureau personnel were instructed in the use of the unit.

Jan 1, 1972

By Laurance L. Oden

The Bureau of Mines is developing melting data for binary combinations of the alkaline earth fluorides and yttria to facilitate the formulation of slag compositions. The present report deals with the SrF2-Y2O3 system for which liquidus and solidus temperatures and solid solubilities were determined. The information is presented as the phase diagram. The phase diagram was constructed from information obtained by ceramogra¬phy, X-ray diffraction, thermal analysis, and electron probe microanalysis of small specimens encapsulated in platinum-20 percent rhodium or molybdenum ampoules. The data indicate a simple eutectic system with limited terminal solid solubilities. The eutectic temperature is 1,457°±5° C, and the eutectic composition is 4±1 mole-pct Y203. Strontium fluoride containing up to 2 wt-pct 0 2 was studied to determine the effects of oxygen contamination. Oxygen levels in excess of 0.2 wt-pct resulted in eutectic formation between SrF2 and SrO. The eutectic composition is between 0.2 and 0.7 wt-pct 02, and the eutectic temperature is 1,447°±5° C. No intermediate oxyfluoride phases were detected.

Jan 1, 1974

By S. Banisi

Thickening is the most widely applied dewatering technique in mineral processing. Thickeners are used to increase the concentration of suspension by sedimentation, accompanied by the formation of a clear liquid. As the particles get finer the thickening process encounters difficulty due to a significant change in the settling behaviour of particles. The batch settling tests of coal refuse of a coal washing plant which contained 91% particles smaller than 38µm and 0.6% coarser than 75 µm showed that the optimum feed percent solids that provided highest flux (solids handling capacity) was 4%. The flux of the pulp with the plant solids concentration (i.e., 10%) was 60% lower than that of the pulp with 4% solids. A thickener with a diameter of 22m based on the dilution of feed from solids concentration of 10% to 4% was designed. Monitoring of the thickener performance for a period of one month in the plant indicated that on average the feedrate of 25t/h (dry solids) with solids concentration of 10% could be thickened to the underflow concentration of 26.5% with a clear water overflow. It was found that the key component of the successful operation of the thickener is the dilution of the feed without which the overflow loses its clarity and the system ceases to operate under predetermined conditions. Specially designed feeding system which efficiently dissipated the energy of the incoming flow and staged flocculant addition regime are among the main contributing factors in making the design and operation of such thickener possible.

Jan 1, 2014

By S. Sarac

In this study, graphical and mathematical methods used to determine operating points in single or multiple fan ventilation systems are summarized. The problem is mathematically formulized for parallel connected fans in which analytical solutions are not possible. For n number of parallel connected fans, a non-linear equation system that consists of n number of non-linear equation sis derived. The Newton-Raphson method, which is a numerical analysis method, is adapted to solve this non-linear equation system and the solution steps are given as an algorithm. A computer program based on this algorithm is written and its applicability is proved.

Jan 1, 2000

By R. Pothina

The objective of this research was to develop a mathematical model for gyratory crushers to help in the prediction of energy consumption and to analyze dominant parameters that affect this energy consumption. The development of a gyratory crusher model was achieved in the following three main stages: mathematical representation and coding of the crushing process; building an amperage constant model to derive an energy-scaling formula; and modifying the amperage constant model to represent a full-scale model. Due to their significant influence on feed-size distributions, two blasting parameters, i.e., burden and spacing, were considered. The crusher parameters that affect energy consumption were also identified. A case study of an operating dolomite mine was performed. The results indicated that by changing the burden, spacing and crusher closed-side setting, the overall (blasting and crushing) costs could be reduced by 4.7% to 7.9% annually. It can also be concluded that burden and spacing values have a linear positive relationship with the crusher energy consumption, while closed-side setting values have an inverse linear relationship with the energy consumption.

Jan 1, 2007

By David A. Monaghan

This report describes instrumentation which is part of a system for extinguishing mine fires by pumping material through surface boreholes in order to seal off all underground passageways leading to the fire area. Major instrumentation systems include a closed circuit television probing system and an acoustic seal checking system. The latter consists of a speaker probe, a receiver probe and related signal processing equipment. All probes can be winch-deployed down a 6-inch diameter borehole. The CCTV unit can be rotated 360 degrees in the horizontal plane, and contains sufficient lighting to reliably assay conditions for sealing or rescue within a 200 foot radius. The acoustic seal checker monitors the completion of a seal as it progresses by use of probes lowered through boreholes on either side of the seal.

Jan 1, 1977