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By Lu Yang

In the last two decades, acid iron ore pellets have established their predominant position as the iron-bearing burden material for blast furnace ironmaking in North America. It is a general practice that pelletization plants are asked to produce pellets of certain chemical composition and in a narrow range of sizes. A minimum amount of fines created during handling and transportation is desirable. Such a requirement is often expressed indirectly by the minimum compression load causing a pellet to break. The behavior of pellets inside a blast furnace, of course, is very important for a smooth and efficient operation. Before its melting in the lower part of a blast furnace during this period of several hours the behavior of pellets depends on their properties after induration as well as conditions inside each furnace. Among properties of indurated pellets, the ability to maintain their physical integrity in the burden and to be reducible are most important. To maintain the integrity of pellets (i.e., minimal low temperature breakdown, swelling and softening) so that there will be adequate overall permeability for certain wind rate and local permeability for gas/solid contact for reduction. A higher reducibility will moderate the adverse effects of swelling and softening and contribute to a smooth operation and efficient use of heat and reductants in a blast furnace. An article devoted to the relationships between the quality of iron ore pellets and blast furnace practice has been published elsewhere(1); therefore, no further discussion is needed here. The mechanism of strengthening of iron ore pellets during firing has been the subject of investigation of many authors(2). There is no doubt that the bridging of the growing hematite grains, particularly starting with magnetite concentrates, is very significant in the production of strong pellets. Recently, there are many reports from blast furnace operators that they have noticed the adverse effect of LTB in their plants. It is obvious that the strength derived from bridged hematite grains may disappear when hematite is converted to magnetite with thorough breakdown of grain structures. It is suggested that some other strengthening mechanism may be required in order to improve the LTB index of acid pellets. The influence of porosity on both compression strength and reducibility follows regular patterns. It has been suggested(1) that the amount of liquid slag in pellets during firing determines to a large extent the porosity, hence, indirectly, strength and reducibility.

Jan 1, 1983

By Henrique Silva Furtado

Concerning production of low phosphorus steel critical grades at ArcelorMittal Tubarão site, bottom blowing system plays a very important role. For those systems with independently controlled tuyeres, some non-uniform bottom blowing patterns seem to be promising in improving metal-slag mixing; however, based on computational fluid dynamics (CFD) results of ArcelorMittal Tubarão’s post oxygen bottom blowing, this may not be generalized. Also, from industrial trials it became clear that higher the bottom blowing flow rate, the closer were the end point P to the equilibrium. Despite this result an analysis of the apparent mass transfer coefficient has shown a week correlation with the classical power stir correlation suggesting a more complex kinetic limiting step for phosphorus removal.

Jul 30, 2018

By J. E. Urosek

The Mine safety and Health Administration (MSHA) formed the Mine Ventilation Bleeder and Gob Training Committee in 1993. This committee was charged with developing a training course designed to enhance the knowledge and understanding of practical bleeder ventilation systems. The course will probably include a discussion on the theory behind bleeder system design, an in-depth look at the strengths and weaknesses of the basic bleeder system types, case studies, and a review of the systems currently in use. A database on active underground bituminous coal mines, gob areas, and the bleeder systems presently used was developed from questionnaires distributed to nine Coal Mine Safety and Health (CMS&H) districts. Representative systems were selected for thorough investigation to develop case studies. This paper introduces some of the material to be included in the course, including a description of basic bleeder system designs, a review of a portion of the database, and facts about the gob areas and bleeder systems investigated for the development of case studies.

Jan 1, 1995

By Edward Judd

THE old Cerro de Pasco smelter at La Fundicion, near Tinahuarea, 9 miles. from the Cerro de Pasco. mines and at an elevation of 14,300 ft., has now been replaced by a thoroughly modern smelting plant at Oroya, the junction point of the company's private railroad with the Central Railway, of Peru. This site has the advantages of being closer to the Morochoca mines, as well as nearer to the port of Callao, and at the same time is 2000 ft. lower in elevation, which benefits not only the cost of transportation but also the tech-nical operation of blast furnaces , and converters. The Oroya smelter was designed with the idea of .smelting about 2500 tons of. ore per day, but having in mind the possibility of increasing its capacity, all departments of the plant can be extended within reasonable -limits; for instance, if it is found that reverber-atory smelting is cheapest, taking into consideration the cost of fine crushing and fuel, it is possible to extend the roaster and reverberatory plants accordingly. The ore handling system is modern, consisting of belt conveyors, reclaiming machines, and electrically driven calcine cars, all requiring the minimum of labor. Waste heat from the reverberatory furnaces is utilized in boilers for the production of power to operate the plant, and the power house is equipped with condensing units to obtain the highest economy. Shop installations for the making of all repairs required for the smelter are unusually complete, includ-ing iron foundry, steel foundry, forging and machine shops, carpenter and pattern shops, and an electrical shop. There is also a plant for the production of all clay and silica refractory brick used in the furnaces; this is situated on the smelter site and is conveniently arranged for receiving raw materials and delivering finished brick to the several departments of the smelter. The laboratory is in a wing. of the general office, which is a two-story brick structure, situated on the smel-ter site.

Jan 10, 1923

By L. Dudley Stamp

On April 1, 1937, Burma, formerly a province of the Indian Empire, was formally separated from India and became an independent unit of the British Commonwealth. In future, therefore, statistics of oil production in India will exclude Burma and those for Burma will be separately published. The last few years have been marked by noteworthy, almost spectacular, developments in the oil fields of Burma and the Punjab. In Burma these developments have been the proving of unexpected extensions of the existing fields and not the discovery of entirely new fields. The new extensions are important not only to Burma in giving a new lease of life to her fields, but also in general as stressing some interesting geological aspects hitherto neglected. Production The production of crude oil in Imperial gallons has been: Burma India 1934 254,760,070 67,265,210 1935 251,338,974 . 71,323,362 1936 265,656,393 69,241,504 1937 (eat.) 270,000,000 70,000,000 The Chindwin Fields.—The small field at Indaw continues to produce steadily about 3,000,000 gal. a year, but no really deep test has yet been successfully carried out and resources are thus not yet fully known. The remote location of the field, inaccessible except by river and situated 22 miles from the Chindwin 270 miles up that river from its junction with the Irrawaddy, has not encouraged active exploitation. The field is worked exclusively by the Indo-Burma Petroleum Co., Ltd. (I.B.P.), using now an automatic gas-lift system, and the company formerly refined the oil at a small refinery at Pantha on the river near by. The chief market was for kerosene in upper Burma. The refinery has now been closed. The oil is stored on the field during the low-water season

Jan 1, 1938

By R. S. Shoemaker, D. L. Harris

PST investigations into the possibility of concentrating the low-grade iron ores of the Gogebic Range in Wisconsin have been hampered by the complex association of the constituent minerals. In part the problem arises from the fact that the iron occurs essentially as two minerals, hematite and goethite, having nearly the same chemical composition but exhibiting different physical properties. Individual grains of these minerals are usually so small that the ore must be ground to a size finer than 325 mesh if substantial liberation of the minerals is to be secured. Appraisal of beneficiation tests on this iron ore requires, therefore, some method of determining quantitatively the contents of constituent minerals in the various products of the beneficiation. Because of the chemical similarity of the two iron minerals, chemical analyses do not provide a means of differentiation. Although the minerals are different physically, they are both opaque and friable, and as the ore must be ground to a very fine size for liberation to be secured, quantitative microscopic methods of analysis are extremely difficult at best. In an effort to overcome these analytical problems, a quantitative X-ray diffraction analysis method has been developed at the University of Wisconsin for the research program on iron ore beneficiation. The X-ray diffraction analysis of chemical compounds of crystalline form has proved of inestimable value for structure studies and rapid qualitative analytical purposes in a number of fields.' In some cases X-ray diffraction analysis has been found suitable for quantitative determinations. H. P. Klug2 found that quantitative procedures for quartz powders when mixed with calcium fluoride were reproducible within ±1.0 pct. Talvenheimo and White3 reported quantitative analyses of clay minerals to be accurate within 10 pct and also detected 1 pct of bentonite in 99 pct illite. In other investigations,'" powders of quartz and mica have been analyzed quantitatively with accuracies from 1 to 5 pct. A powder of tungsten carbide was analyzed similarly by Redmond7 and Rooksby8 reported the determination of small amounts (0.11 pct) of calcium oxide in magnesium oxide. In the most generally practiced use of X-ray diffraction, traces of the diffracted beam are recorded as lines on a film much as lines of elements are recorded on an optical spectrograph film. As with the spectrograph, the darkness of the lines denotes the amount of the constituent in the sample. If the film is replaced by a Geiger tube assembly and a graphic recorder or a scaling unit, the intensity of the diffracted beam can be registered as a peak on a chart or energy impulses per unit of time on the scaler. Several methods of quantitative measurement have been investigated and reported in literature. Klug2 used manual operation of the goniometer and a counting technique to determine the difference in counting rates at the diffracted angle and for the background. In another case3 the area under the recorded diffracted peak was the basis for the determination. In other instances the height of the recorded diffraction peak above background, measured while the goniometer was moving, has been the basis for the measurement. The sizes of particles most suitable for diffraction techniques are reported in the literature as follows: for tungsten carbide a maximum of 40 microns7 and for quartz a maximum of 5 microns.' Very fine sizes of crystals are known to cause a broadening of the diffused beams; hence some workers have set a lower limit of 0.1 micron for quantitative results. Guinier10 has indicated that broadening of the diffracted X-ray beam is not appreciable for crystallites larger than 0.02 to 0.03

Jan 1, 1956

By W Blair, J Bosman

The measurement of ferrosilicon rheology and characterisation of the parameters that have a direct influence on medium rheology provide the basis for evaluating, comparing and selecting an appropriate size and shape of medium to maximise separation efficiency in a dense medium application. The role of medium viscosity on particle separation in both static and dynamic separators is illustrated using relevant theory. The primary measurements of rheology are medium viscosity and stability. These in turn are determined by particle size, particle density and particle shape which in turn can be quantified. Additional characterisation parameters are also discussed. Different areas of application where ferrosilicon characterisation can be used are also discussed.CITATION:Bosman, J and Blair, W, 2017. The practical characterisation of ferrosilicon for dense medium applications, in Proceedings Iron Ore 2017, pp 135–140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Craig Byington

The stress-field orientation mapping and analysis (SOMA) technique for determining the operative stress field near mine workings and its relationship to various fracture sets is described using Dickenson-Russell Coal Company's Laurel Mountain mine as an example. Carried to its practical application, this technique ultimately defines the optimal orientation for the mine workings wherein pillars, rather than rock bolts or other roof support methods, dominantly shoulder support of the highest-probability, potential, roof-fall blocks. It also provides a predictive tool describing local variability in rock deformation and in secondary roof support methods. Fracture discontinuities within a rock mass, either as pre¬existing natural fractures or as mining-induced fractures, are uniquely necessary for every brittle-deformation ground failure including roof falls. Prediction and mitigation of roof falls requires quantifying the interaction between the fracture sets and the operative principal-compressive¬ stress-axis orientation (olo). The SOMA technique utilizes the interaction between fractures and 61o, specifically their dilation or closure, to calculate the orientation of 610, and to estimate the orientations of 62o and o3o. A stereonet program is used to organize and statistically analyze the fracture data, and then to determine the optimal orientation for the mine workings. The final step in the SOMA technique involves modeling the Laurel Mountain mine using a 2-D, finite-element, modeling program. This assures that the interpretations regarding the optimal working orientation closely match the deformation features observed in the mine. It also provides a predictive tool describing highly variable stress and strain partitioning, seemingly erratic rock-bolt failures and the interactions between different sets of mine workings within different coal seams. The critical importance of including the fracture sets is well illustrated in the Laurel Mountain mine where the effects of earlier mining of an underlying seam is contrasted in both a fractured and otherwise identical non-fractured model to illustrate the consequences of ignoring fractures in a predictive roof-fall model.

Jan 1, 2004

By Donald F. Reed

In its investigation of old, abandoned, lead-zinc mines at which records of operations are not available, in 1914 the Bureau of Mines dug surface trenches anti', in 1947 It diamond-drilled three holes at the Albright Farm deposit in Sinking Valley. Some good lead-zinc ore had been extracted from veins in dolomitic limestone during the time of the American Revolution and as late as 1870. Since that time the only activity was sporadic prospecting and developing. Thu Bureau of Mines disclosed two additional veins by surface trenching, but diamond drilling failed to find significant lead-zinc mineralization.

Jan 1, 1949

By D. M. Maijer, S. L. Cockcroft, A. B. Phillion, P. Fan, C. Reilly

"A numerical model has been developed to study macrosegregation associated with liquid feeding in the Low Pressure Die Casting of A356 aluminum alloy wheels. The model of the wheel casting process has been implemented within the commercial CFD software package, FLUENT, using a User Defined Function (subroutine) to account for Si rejection based on the Scheil approximation. The model has been validated against temperature and microstructural data taken from a commercially cast wheel. The amount of segregation in the wheel has been shown to be significant in a couple of key areas. The implications of accounting for segregation include an improved ability to predict shrinkage porosity, fatigue performance and potentially also hydrogen porosity.INTRODUCTION The aluminum alloy A356 is widely used in the automotive and aerospace industries for various components. Examples include automotive wheels, automotive suspension components and airframe castings. Focusing on automotive wheels, Low-Pressure Die Cast (LPDC) A356 wheels offer significant design freedom and are far more aesthetically appealing to consumers than conventional stamped steel wheels. A356 wheels now dominate the market, appearing in all but the entry level offerings of the OEM manufacturers. However, they are typically over-designed to allow for the various casting related defects that degrade their mechanical performance. Thus, their potential to save weight has not been fully realized. Wheel manufacturers are under constant pressure to ensure their products meet strict mechanical requirements (ductility, fatigue, vibration), tight geometric tolerances and high aesthetic quality. The mechanical properties of the final product are determined by the microstructure – e.g. SDAS – and the defect population (porosity and oxides). Depending on their size and location, both porosity and oxides, can act as crack initiation sites reducing fatigue life (Caton, 2001; Jordan, 2010; Wu, 2015). There are a number of examples appearing in the literature (Atwood, 2000; Carlson, 2007; Lee, 2001; Yao, 2011) of numerical models that have focused on hydrogen-based pore formation that have demonstrated an ability to predict porosity formation and pore size distributions in geometrically simple castings. These models assume that the local gas species diffusion through the liquid metal to the pores is the rate-controlling factor of pore growth. Another common source of porosity is liquid encapsulation (Dantzig, 2009). As the pressure within the isolated liquid drops, pores form first due to the pressure dropping below the equilibrium partial pressure of hydrogen in solution and then second grow substantially as the pressure continues to drop falling below the vapour pressure of Al. One factor that can affect both mechanisms of pore formation is species macrosegregation, which has received comparatively little attention in die-casting."

Jan 1, 2017

By C. E. Saxon, F. E. Cash

"Adequate lighting for all mining operations would unquestionably tend to promote both safety and efficiency; this would be true not only for men but also for the animals that man impresses into service in mines. The Markeeta Coal Co. and the Alabama Fuel & Iron Co. both operating mines in Alabama, have found that equipping mine mules with portable electric lights is more efficient, much more humane, and far more safe for both men and animals then the more or less usual method of forcing the animal to do its work essentially in darkness.This report is intended to give the mining industry data, that will aid in trying to bring about safe and efficient operation of mines.The authors desire to thank Charles F. DeBardeleben, president, Fred R. Bell, general manager, Hewett Smith, C. H. Shepherd, and R. A. Sensing, superintendents for the Alabama Fuel & Iron Co.; and Charles F. DeBardeleben, Jr., president, and H. M. House, superintendent for the Markeeta Coal Co., for their cooperation in furnishing the data for this paper.The eight mines operated by the Alabama Fuel & Iron Co. and one operated by the Markeeta Coal Co. in Jefferson and St. Clair Counties, Ala., are the only mines in Alabama where mules are provided with portable electric lights, and there are few if any mines in other States in which this system is in use.These two companies are convinced that equipping all mine mules with good lights decreases underground haulage cost by animals by prolonging the useful life of the animals, increasing their efficiency, lessening haulage wrecks and delays on haulage, and increasing production. Last but not least of the advantages would be the more humane treatment of the animals.The nine mines are developed by slopes along the dip of the coal bed, with double-room entries on 200- to 300-foot centers turned right and left off the slopes and with approximately 1 per cent grade in favor of the loads. Rooms are driven up or diagonally up the pitch from these entries.A surface hoist delivers the empties from the surface to the entry sidetracks at the slope and pulls the loads to the surface. From these sidetracks, mules pull one to four wooden cars, each of which holds 1-1/2 to 2-1/2 tons of coal, deliver the empties to the rooms and entry faces, and pull the loads to the slope sidetracks. The mule haul varies from 100 to 3,000 feet; there are no locomotives or trolley wires in any of these nine mines, seven of which are rated as gassy and two as nongassy by the Alabama state Mining Department."

May 1, 1933

By József L. Margitfalvi

Different Au/MgO catalysts modified with Mn, and Fe were prepared by precipitation-deposition. The catalysts were characterized by XRD, FTIR, Temperature Programmed Reduction (TPR) and CO chemisorption and were tested in CO oxidation in the temperature range of 243-523 K. The catalytic tests using both Temperature Programmed Oxidation (TPO) technique and time on stream (TOS) experiments revealed the high activity of catalysts prepared. In TPO experiments the modification by Mn significantly increased the activity above 300 K, however in the subambient temperature range the activity decreased considerably. Catalysts modified by iron did not show any decrease in the activity below 300 K, while the activity at high temperature increased significantly. Catalysts modified by Mn, Fe showed higher activity, selectivity and stability in preferential CO oxidation, carried out in the presence of hydrogen than the unmodified Au/MgO catalysts. Results of in situ FTIR spectroscopy on both the base Au/MgO and the iron modified catalyst unambiguously revealed the formation of ionic gold in the presence of CO/O2 mixture. The formation of this species was strongly hindered in catalyst modified by manganese. Results obtained strongly support the need for the formation of "metal ion - metal nanocluster" ensemble sites. These sites are involved in the activation of the CO molecule prior to its reaction with atomic oxygen. It is suggested that at subambient temperature these ensemble sites contain mainly ionic forms of gold, while at higher temperature iron or manganese ions are involved in CO activation.

Oct 1, 2003

By P. King

In considering the available reserves of coal, the author points to the importance of improved recovery, and defines three extraction ratios: the geological extraction ratio (or exploitation factor), the economic extraction ratio (or mining factor), and the geometrical extraction ratio (or volumetric extraction factor). He discusses the factors affecting each of these ratios, and concludes that, although geological factors cannot be considered in isolation from technical and economic factors, the geological extraction factor is the most significant criterion of whether the best use is being made of coal resources.

Jan 1, 1980

By R. Drummond

The fourth Teetered Bed Separator (TBS) has just been installed in Australia, and trials have been run in many sites. There is a growing recognition of the potential advantages of using TBS technology to treat coal in the ?3+0.25 mm size range, at cut points below 1.60. From these activities, there has been a substantial growth in knowledge with respect to application engineering and operational functions. The paper briefly describes the installations, including flowsheets, and so provides a background to the potential deployment of TBS technology. There are a large number of potential applications for TBS technology, including treatment of fine ROM coal in new plants, or in upgrade situations for re-processing of spiral product, or scavenging coal from coarse tailings. As well, cost effective capacity upgrades are possible by using TBS units for treating the sands size fraction. Issues arising from Australian TBS installations and application engineering are also discussed.

Jan 1, 2002

Several glacial episodes have been distinguished in the Shotover Valley. These produced fluvioglacial aggradational deposits downvalley from the terminii, commonly with well-preserved terrace treads, as exemplified near Skippers. Chronological links can be determined between the Shotover tills and sediments and assessed equivalent deposits in the Wakatipu Basin/Kawarau Valley region through axial valley profiling. Constructed relationships suggest older Shotover events were probably large and left little detrital deposits within the valley. In contrast, the younger advances were smaller and valley-constrained. They are modelled as being wholly of Waimea or Otira Glaciation age, advances from the latter period producing the visually distinctive flights of terraceremnants. Both the terraces and the inner gorge, now occupied by the Shotover River, have been extensively worked for alluvial gold. Enrichments in the former environment have predominantly been as bottom or intermediate lags produced during degradation phases of catchment erosion. Surface lags have been locally targeted. Placer mining in terrace areas involved both tunnelling and sluicing techniques. In the modem river the greatest concentrations were on the schist or false bottoms, although flood gold has always contributed to the returns. Placer mining techniques here were highly variable.

Jan 1, 1998

By Danielle Nhanqulumanga, Pranith Bhatt, Snehal Patel, Khadeeja Priyan

The Bi-Directional Static Load Test (BDSLT) is a test that determines the capacity of piles when loaded under bi-axial static compression. In recent years the BDSLT has seen an increase in demand due to its safety, speed, and affordability. This innovative foundation testing method has been universally used over the last 50 years, however respective codes and standards have only been published within the recent years. Detailed test procedures and methodology are expatiated in the ASTM D8169 M-18 [1], and the IRC 78 2014 Clause 709.2.5. [2] These standards provide the minimum requirements for the execution of the BDSLT. In this paper we did a comparative study of both standards envisaging to bring attention to the similarities and discrepancies found therein, with an aim to highlight the impacts and challenges that differing provisions of each standard could pose on the conduct of the BDSLT. Discrepancies found have been explained on the basis of geotechnical engineering theories and relevant field occurrences observed by superior engineers. Additionally, we emphasize on the relevance of experienced engineer’s judgement when utilizing the standards.

Sep 1, 2022

The emerging discipline of ægeometallurgyÆ is not new but is becoming increasingly recognised as a discrete and high-value activity that reflects an ongoing commercial and cultural trend towards more effective mine site integration and optimisation. Geometallurgy involves a quantified and spatially constrained approach to ore characterisation in terms of relationships to critical processing performance. Industry recognition of the need for large-scale, integrated geometallurgical research is currently supporting a major new research initiative. The AMIRA International P843 æGeMIIIÆ project (geometallurgical mapping and mine modelling) is a cross discipline collaboration involving four major Australian research groups; CODES the ARC Centre of Excellence in Ore Deposits at the University of Tasmania, a world leader in economic geology-related research; the Julius Kruttschnitt Mineral Research Centre (JKMRC) at the University of Queensland, a world leader in mining and mineral processing research; the WH Bryan Mining Geology Research Centre (BRC) at the University of Queensland, which aims to be a world leader in mining geostatistics, operations research and optimisation in mine design and planning; and CSIRO Exploration and Mining in the area of automated core logging. The project is currently supported by 19 global mineral companies. The project aims to deliver fundamental knowledge, tools and methods for more effective approaches to geometallurgical definition of mineralogy, element deportment and texture that can be linked to mineral processing performance and efficiency at a range of scales. Outcomes are improved predictive indices of processing performance that can be embedded in resource block models to define processing domains, which can be exploited in mine planning and optimisation. To achieve these aims the project is involved in a range of technology developments that include more automated core logging technologies, new applications of automated microscopy and development of software-based texture analysis and categorisation techniques. Attributes derived from these measurement technologies are used to develop predictive processing models linked to new small-scale physical testing regimes.

Jan 1, 2009

By J. L. Bruce, G. W. Nicolson

ThE country rock of the Mavrovouni mine of the Cyprus Mines Corp. is hydro-thern~ally altered, disintegrated pillow lava, with very little tensile strength ("short" ground). In places, especially when wet, it is heavy ground, though not extremely heavy except where movement has been caused by underlying or nearby stoping operations. Damage by caving from roof or sides of galleries is not sudden but progressively faster when the size of the cave increases as a result of the fall of small pieces. CeMent and Concrete Linings During early operations, galleries in the country rock were supported by customary mine-timbering methods. Available timber, howcver, was of poor quality and of relatively high price, and replacements were frequent and expensive. Furthermore, the massive sulphide ore bodies required large volumes of fresh air for ventilation and cooling, and it was therefore desirable to provide smooth-lined galleries with low resistance for the introduction of air to the ore bodies. It was also desirable to eliminate hazards of fire in shafts and underground workings insofar as this would be practical. Cement and concrete were relatively cheap, and plans for using these in support of shafts, underground galleries, raises, and chutes, were developed steadily. Circular shafts with diameters ranging from 10 to 15 ft were adopted for all permanent shafts and airways. In places these were lined with concrete poured behind sectional pressed-steel forms especially constructed for this purpose. In other places, they were lined with precast-concrete blocks. It was found that such precast concrete of good quality could be produced on mass production scale and delivered at the mine from most favorable point of manufacture, at a cost of about 25 cents per cubic foot of concrete. This refers to prewar costs. As the use of concrete blocks in circular lined galleries was developed, it was found that there were very great advantages in the reduction of air resistance as compared with customary timber supports. After best methods had been developed, it was found that breakage and replacements were extraordinarily low, averaging only about 11\2 pct per year during a period of about 15 years. Furthermore, it has been possible to reclaim for re-use a very large percentage of the concrete blocks from abandoned galleries. During the history of the operations precast-concrete blocks have been used for lining shafts, raises, ore chutes, galleries, and shaft stations, ranging from 3 to 16 ft id. The thickness of lining has varied from 5 to 10 in.; with 12 in. thickness in a few cases. Junctions of two galleries at angles ranging from about 30 to 60° are usually made of poured concrete behind sectional forms, or of a combination of poured concretc and precast blocks. In nearly all cases it has been found advisable to make the point of the wedge at the junction, of

Jan 1, 1949

"The National Mining Hall of Fame and Museum (NMHFM) announced the 2018 National Mining Hall of Fame inductees. This year’s inductees, selected by the National Mining Hall of Fame’s Board of Governors, represent exploration, extraction, management, education and research and development in the U.S. mining industry. Their contributions have had significant and lasting impacts on the mineral and mining industry; these individuals were selected for being mavericks, thought leaders, researchers, educators, mentors, wealth builders and philanthropists.Professor John M. Guilbert, Dr. Leo J. Miller, Robert E. (Bob) Murray and Douglas (Doug) B. Silver will join 240 other mining industry luminaries when formally inducted into the National Mining Hall of Fame on Sept. 29, 2018. Additionally, the Prazen Living Legend of Mining Award will be presented to the Freeport- McMoRan Foundation. The 31st Annual Induction Banquet and Ceremony will be held at the Ritz-Carlton in Denver, CO.2018 National Mining Hall of Fame inducteesProfessor John M. Guilbert was a renowned geologist and professor of economic geology at the University of Arizona; he had a distinguished 50-plus year career in academia and business. Guilbert, together with J. David Lowell, worked on the most important breakthrough in mineral exploration in the last 100 years, the Porphyry Copper Model. This work, known as the Lowell and Guilbert Model, was utilized by exploration geologists worldwide over the next four decades to discover hundreds of millions of tons of copper metal and numerous profitable mines including the prosperous Bajo de la Alumbrera copper mine in Argentina. Guilbert was a founder of The World Museum of Mining in Butte, MT. He was the recipient of countless awards including the Society of Economic Geologists (SEG) R.A.F. Penrose Medal as well as the D.C. Jackling Award from the SME.Dr. Leo J. Miller was a maverick in the mining industry and no armchair geologist. He believed that active fieldwork, on foot with a rock pick, was indispensable for exploration. His basic tenet was to absorb as much information about an exploration target up front, formulate ideas – sometimes novel ones — and then get out into the field to prove those ideas. Miller was known to diverge from the standard interpretation of the geological processes, which formed the mineral deposits, and to apply innovative applications of high-tech tools to more usual exploration programs. This approach resulted in a 50-plus year career that included the discovery of the Kidd Creek massive sulfide deposit and the development of the Lee Creek phosphate deposit; which other explorers had previously given up on, believing whatever phosphate might be present would be too difficult and expensive to mine. The recipient of many honors and awards, Miller received the SME Robert M. Dreyer award in recognition of outstanding achievement in ore discoveries."

Jan 8, 2018

By W. S. Sanner

Seven samples were analyzed from the major reserves of the Bottom Red Ash bed, Northern anthracite field. The data show variations in thickness and geo-logic structure and in the amount of coal that can be recovered. Recovery of market-grade (less than 17 percent ash) coal is high for all samples, ranging from 76 tp 95 percent in the 3-1/4-by 9/16-inch sizes. The occurrence of coal containing less than 5 percent ash varies from 19.5 to as much as 57.5 percent. Crushing the coarse sizes to minus 9/16 inch increased recovery of market-grade coal in six of seven bed samples. Crushing released sufficient impurities to cause substantial increases in yield of coal containing less than 5 percent ash for all samples. Analyses of the float coal indicate that the quality of coal is comparable for all samples.

Jan 1, 1967