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By R. C. Canby

JUDGE GRANT, in a delightful satire of his, says: "Boston is a state of mind." I think that this same statement might well be made of the metallurgy of lead. I was particularly impressed with this when about thirteen or fourteen years ago I prepared a paper on "Development of the American Water- jacket Lead Blast Furnace." Dividing the time, as I did into ten-year periods, from the commencement of lead smelting at Eureka, Nev. (1870), and showing the tendency for each of the five decades it was evident that the progress had been through a succession of states of mind from the rule of thumb through the ultra scientific, or from what I might call the slag type period up to the present highly developed art. Conservatism has been characteristic of the metallurgist. This may have been most natural, especially with the lead metallurgist, the development of whose art was so entirely in the custom smelting plant, where the metal contents of his ores were paid for in cash and therefore excessive metallurgical losses could mean nothing short of financial bankruptcy. The metallurgist himself was held to a personal account, in these smelting plants. It was the metallurgist who was accountable. In the concentrating plants, if undue losses occurred remodelling of the plant was discussed, but if there were excessive metallurgical losses in the custom smelting plant, a new metallurgist was considered as the remedy. For this reason the tendency was to adhere to recognized practice and to be wary of unusual methods, using the word unusual in the sense in which it is used in Article VIII of the Constitution of the United States, as to punishments and modes of death. This conservatism of the metallurgist was reflected as other branches of metallurgy were developed. We have heard of the wonderful development of flotation, but it had to be introduced over the dead metallurgical bodies of its opponents.

Jan 1, 1926

By Marion Dattilo

The search for an improved anode for the electrowinning of lead from fluosi1icic acid medium has led the U.S. Bureau of Mines to investigate composites. Polymer bonded metal oxide powders which may contain catalyst additions were prepared by pressing. These composites display an improved activity toward the oxygen evolution reaction over electrodeposited lead dioxide on titanium, carbon, and nickel substrates. These composite electrodes contain 5 to 10 wt. " binding polymer, with the balance being metal oxides. Lowered anodic potentials achieved using the compnsite anodes resulted in lower levels of lead dioxide deposition during electrowinning.

Jan 1, 1995

By R Salmimies

Choosing a ceramic capillary action filter is often favoured in processes where low energy consumption is important, such as the dewatering of iron ore. In addition, the performance of the filter medium is essential, and the possibility to regenerate the medium is an advantage compared to other types of filter media. Although low, roughly 8 - 9 w-per cent for iron ore concentrate, and even cake moisture is the primary goal of dewatering, the introduction of better filtration processes can result in significant improvements of water economy and material efficiency.As industrial beneficiation processes are often complicated in their chemistry due to impurities originating from the ore itself, from the up-stream processing equipment and from the process water used, the characterisation of the filter media after usage might provide relevant information on what actually takes place during long operating periods. The aim of this study was to obtain new information on the fouling of fi lter media in an iron ore process to enhance and develop the regeneration process of the media in the future.X-ray diffraction and scanning electron microscopy were used to characterise ceramic filter media used in the dewatering of magnetite. Principal component analysis and discriminant analysis were introduced to identify trends in the data. Two types of media blockages were found to play an important role in an acidic iron ore dewatering process: fouling by slurry particles and by in situ crystallisation of a calcium compound, of which the latter originated from the combination of process water and process chemistry.

Jul 11, 2011

By Essie Esterhuizen, Michael M. Murphy, Chris Mark

"The design of underground coal mines requires a clear understanding of the overburden response, the loading of pillars, the loading of the gob, the pillar failure process, and the ultimate load carried by partly or fully yielding pillars. Very few highquality stress measurements of yielding pillars and gob loading have been made in full extraction mining. Well-calibrated numerical models can assist in providing a better understanding of the load and failure processes, provided the coal, the overburden, and the gob are all modeled with sufficient realism. A program of numerical model calibration and validation was carried out using FLAC3D.1 The models were calibrated against observed and measured performance of coal pillars and the overburden in operating mines to provide a basic set of input parameters that can be used to provide a realistic first estimate of expected ground response and pillar loading. Input parameters for modeling coal pillar response were based on data from triaxial testing on coal samples, combined with both matching the depth of failure in the coal ribs to observations as well as matching the peak pillar resistance to an empirical equation. The models were calibrated against strong roof and floor case histories in which the pillar strength is governed by failure and yielding of the coal within the pillar and the surrounding strata only had a limited impact on pillar strength. Input parameters for the overburden were determined from a large database of laboratory tests and model calibration against maximum subsidence and subsidence curvature. Further overburden calibration was carried out by matching stresses in the mining horizon to field measurements. Three examples of the application of the calibrated dataset and modeling methodology to field measurements are presented. The results show that a reasopable estimate of the in-seam stress distribution and overburden response can be obtained for both strong and weak overburden scenarios at various depths of cover.INTRODUCTIONThe planning and design of coal mine excavations requires reliable estimates of the expected strength and loading of the mine structures to achieve global stability. Empirical methods are widely used to estimate the strength and loading of coal pillars and have been incorporated into pillar design procedures, such as Analysis of Longwall Pillar Stability (ALPS) (Mark, 1987) and Analysis of Retreat Mining Pillar Stability (ARMPS) (Mark and Chase, 1997), that are widely used in the United States. ~umerical models are finding increasing application as a tool for underground mine design because of their. versatility and the ever increasing computational power available to mine designers. A prerequisite for the application of numerical models is the calibration of the models against observed rock mass response (Hoek et al., 1990; Skiles and Stricklin, 2009). The calibration process may include comparison of model results to measured stress and deformation and modifying the input parameters in a systematic manner to achieve a satisfactory agreement between the model results and measurements. Once models have been calibrated, they can be applied to evaluating similar mining layouts in similar geological conditions."

Jan 1, 2010

By E. C. Harder, E. W. Greig

Bauxite is known mainly as the ore from which aluminum is smelted but it has large use also in the manufacture of artificial abrasives and in the production of a number of useful chemicals as well as of aluminous cement "ciment fondu." An important and growing use is in the manufacture of refractory products. Composition Dana and earlier mineralogists gave the mineral formula of bauxite as A1203.21120 and the composition as A1202, 73.9 pct; H2O, 26.1 pct. A specific mineral of this composition has, however, never been identified by either microscopic, chemical or X ray examination, and therefore it is concluded that bauxite is a rock consisting of one or more aluminum minerals together with impurities. The term is now used synonymously with aluminum ore and it embraces gibbsite (hydrargillite or alpha trihydrate), A1203. 3H20 (A1203, 65.4 pct; H2O, 34.6 pct); boehmite (alpha monohydrate), A1203•H20 (A1202, 85 pct; H2O, 15 pct) ; diaspore (beta monohydrate), A1203•H20 (A1203, 85 pct; H2O, 15 pct), and mixtures in various proportions of any two of them. Bauxite of the Mediterranean region in Europe is predominantly boehmite, as in France and Istria, subordinately a mixture of gibbsite and boehmite, as in Dalmatia, or of boehmite (or gibbsite) and diaspore, as in Greece. The bauxite of North and South America, tropical Africa, Asia, and Australasia consists largely of gibbsite, but boehmite in appreciable amount occurs in many places. Corundum (A1202) is not included un¬der bauxite, although gradations from bauxite to emery or corundum exist. All bauxite, irrespective of the aluminum minerals composing it, contains certain impurities in variable amount, including silica in the form of clay minerals (kaolinite, halloy site, and others) or quartz, iron oxide (as hematite or goethite), titania (as leucoxene or rutile), iron sulfide (as pyrite or marcasite), iron carbonate (siderite), and calcium carbonate (as calcite); the last three mentioned in minor amount and of local occurrence only. Bauxite belongs to a group of partly consolidated materials called laterites, formed by surface weathering. This group includes also impure siliceous, ferruginous, and phosphatic bauxite and siliceous and aluminous iron ores and manganese ores and nickel and chrome laterites. Phosphorus and manganese minerals locally form important impurities in bauxite deposits. Properties Gibbsite is white or light shades of gray, cream or pink. Its hardness is 2.5 to 3.5; specific gravity, 2.3 to 2.4; crystal system, monoclinic, crystals tabular parallel to 001, often fibrous, concretionary, stalactitic; luster, vitreous to pearly; generally translucent; cleavage, parallel to 001; disassociation temperature, approximately 300°C. Boehmite, a relatively new and important mineral described by J. Boehm15 in 1925, confirmed and named by J. de Lapparen64 in 1930, has some properties not yet definitely determined. It occurs in grayish, brownish, and reddish shades. Its hardness is between that of gibbsite and diaspore; specific gravity, 3.01 to

Jan 1, 1960

Provide an improved, rugged, reliable, cost-effective automatic fire protection for mine haulage trucks. Approach Systems that automatically sense and extinguish fires on haulage trucks were designed, built, and in-mine tested. How It Works Temperature sensors mounted above the engine of the truck detect the heat from a fire while it is still small and controllable. A cab-mounted control panel warns the operator of the fire emergency and then automatically triggers the discharge of 60 pounds of multipurpose dry chemical extinguishing agent (from storage tanks through hoses and nozzles) into the engine compartment. If desired, the control panel can be field-adjusted by changing one resistor to delay the discharge for up to 60 seconds to allow time for the operator to stop the truck and shut down the engine. The system can be assembled with either pressurized storage tanks, or a combination of non-pressurized storage tanks plus separate pressure cartridges. This pressure source option is one of the improvements of this system over the earlier systems described in Technology News No. 11. Other improvements are a simplified control circuit and an improved sensor.

Jan 1, 1980

By V. Sheikhzadeh, M. Saghaeian, R. Hejazi, A. Abazarpoor

Green pellet strength including drop number and green compression is highly depended on particles size and shape. The used grinding method, ball mill or high pressure grinding roll (HPGR), directly vary the particle size and shape. Considering mode of pellet crack, green pellet is composed of particle-binder-moisture system. Different type of forces existed in such a system to create a stable green pellet: solid particle interaction, magnetic, binding and cohesive forces in the interface of particle-moisture. The pellet failure can occur at solid-liquid interface and/or through liquid phase. Pellet crack occurs when crack passed through entirely the plane failure. In this research, the effect of particle size and shape of pellet feed on green pellet strength has been investigated. It was deduced that green pellet strength highly improved by increase of specific surface area. The drop number and green compression strength of pellets prepared by HPGR was higher than ball mill. It was found that the main reason responsible for this difference was the particle shape. Capillary force is responsible for part of pellet force and improves by decrease of particle size. Also more elongated shape of HPGR particles resulted in higher capillary force due to thinner interface layer between particles. The less circular shape of particles lead to improvement of capillary force as can be occurred for HPGR particles. The rougher shape of HPGR particles resulted in higher wettability of particles and better diffusion of water among particles. In fact the rougher particles means lower connection angle. Aspect ratio of particles was of great importance of crack growth because the required energy of pellet failure increases directly. The required energy for pellet failure increases by increment of particle aspect ratio. The relationship among crack failure force, roughness and aspect ratio has been modeled considering 3 shape descriptors.

Jan 1, 2018

By Jorge Vargas Fernández

El presente texto describe el diseño de una política minera como parte de una estrategia de difusión. Para tal efecto, esta se divide en dos parámetros: internacionales y parámetros nacionales. En ese sentido, el marco y referencia internacional es analizado con ayudas de gráficos estadísticos y cuadros que comprende: las fuerzas que actúan en la industria minera, crecimiento de producción minera mundial, relación del crecimiento industrial con el consumo, la comparación entre la producción y consumo de las principales sustancias por zonas, etc. Asimismo, con la finalidad de promover las inversiones en minería, es importante revisar la legislación laboral, de modo que la ley de estabiidad no rija para las empresas mineras que tienen alto riesgo

May 1, 1987

By E. H. Smith

St. Joe Minerals Corp., a subsidiary of Fluor Corp., treats high-grade gold, silver, and copper ore at its El Indio plant at an altitude of 4 km in the Chilean Andes. The ore is complex, being a mixture of massive pyrite-enargite and quartz, both containing very fine gold and silver. Treatment produces a copper flotation concentrate containing high levels of gold, silver, and arsenic, and also dore bullion. Part of the flotation concentrate is roasted to remove the arsenic content, and arsenic trioxide is collected as a by-product.

Jan 1, 1987

By Meifeng Zhi

Separation of uranium and molybdenum in the alkaline leach solution of a U–Mo ore was studied. A process of acidification-solvent extraction-precipitation uranium and molybdenum was determined. The influences of solution acidity and phase ratio of acidic scrubbing on separation of uranium and molybdenum were examined. The molybdenum extraction equilibrium isotherm was drawn. The results show that the separation of molybdenum and uranium can be achieved by acidifying the alkaline leach solution, solvent extracting molybdenum using trialkylamine at equilibrium pH 2.5, and scrubbing the loaded organic phase using sulfuric acid solution. The strip solution can directly precipitate ammonium molybdate. Uranium can be directly precipitated from the raffinat

By Amanda Powers, Brian Glynn, Robert Sauceda, Daniel Huffines, Mike Garbeth

This paper will review the evaluation performed for the Cottonwood & Hackberry Creek Wastewater Interceptor Improvements Project to replace two separate aging and undersized interceptor sewers by either open cut construction or trenchless construction methods. A case study will be discussed for the utilization of microtunneling to avoid a deep open cut excavation within a landscaped roadway median to construct nearly a mile of new 60-inch interceptor sewer in an urban area adjacent to an environmentally sensitive riverine area, while minimizing the permitting and environmental impacts of construction, and minimizing the impacts to residents and vehicular trafc and restoration reuirements.

Jun 23, 2024

By George Bain

SOME problems concomitant with commercial exploitation of marble are presented as examples of interesting, useful and profitable fields for application of scientific knowledge. The marble industry is only one such field and is selected because its varying new aspects are familiar to the author. However, what is true for marble is equally so in principle for many industrial minerals. The problems of any stone industry are to maintain markets, create new outlets for stone already in demand, and develop varied uses for varieties that are not so popular. Here the geologist has a different role from most of his colleagues in metal mining. The producing branch may ask about the expectable variation in thickness or size of a deposit as development proceeds. The stock department may call for the available amount of a given type of stone before accepting a large order. The sales force requires data on the use for stone from certain parts of deposits in order to divert grades to the most suitable use. The service depart-ment wants defects rectified and the cause determined to avoid recurrence. The mills want data on durability and cutting quality of abrasives. The geologist occupies no special department; he is on general call, as may be illustrated by a few types of problems that may be classified as: (1) dominantly geological in character, (2) dominantly chemical in character, (3) dominantly physical in character.

Jan 1, 1940

By Jean Wehbe, Daniel C. Brahana

"The new Mercedes-Benz Stadium (MBS), home of the Atlanta Falcons, is part of a new era of stadium construction in the U.S. These new-age stadiums are larger and have more amenities than their predecessors. Many of the MBS’s features, including its innovative retractable roof, result in extraordinary structural loads. The roof structure is supported by a series of mega columns that bear on eight large caps, six of which are supported by drilled piers. Each of the pier caps contains between 8 and 16 drilled piers that bear in the underlying bedrock. The design pier diameters are 6 and 6.5 ft (1.8 m and 1.9 m). Augercast piles were used to support two of the mega column caps. Drilled piers, augercast piles, aggregate piers and spread footings were used to support the more lightly loaded portions of the structure.The focus of this article is the construction aspects of the drilled pier foundations. Initially, a fairly extensive drilled pier load test program was performed. Load testing included a Statnamic compression test, two Osterberg Cell tests and two lateral tests. Production pier installation included over 3,800 linear ft (1,158.2 m) of earth excavation and over 1,350 linear ft (411.4 m) of hard rock excavation. The piers contain more than 6,600 cu yd (4,587.3 cu m) of concrete and 1,100 tons (998 tonnes) of reinforcing steel. Drilled pier installation took about 4.5 months. ABE Enterprises was the specialty foundation subcontractor and Bauer-Pileco was the equipment provider.Site and Subsurface ConditionsThe project site is in downtown Atlanta and was originally occupied by residential buildings. A portion of the site was later developed as a rail yard, and other areas contained light manufacturing, warehouses and other relatively light structures. For the past 15 to 20 years the site had been used for surface parking.Beneath a surficial layer of manmade fill, soil test borings at the site generally encountered residual soil, partially weathered rock and the parent bedrock. The bedrock at the site is highly variable, both in elevation and in hardness/quality. The depth to rock is reasonably uniform within the western two-thirds of the site at about 20 to 50 ft (6 to 15.2 m), with a few exceptions. In the eastern third of the site, the rock drops off dramatically to the north and east. In one mega column cap, there was almost 80 ft (24.3 m) in elevation difference. In two borings in the cap that were 20 ft (6.1 m) apart, the top of rock varied in elevation by 34 ft (10.3 m)"

Jan 1, 2016

By Henry E. Colton

NeaR the town of Christiansburg, Va., occurs a singular feature in topographical as well as geological structure, which may be said to have an important bearing on a large area to the southwest. The great water-shed ridge, which divides the waters flowing into the St. Lawrence from those flowing into the Atlantic ocean, coming southwestward, forms all of what was the boundary of Maine as agreed upon by the treaty of 1783, and a part of the present boundary, all of the northern New Hampshire boundary, and entering Vermont, continues south of Lake George. Passing irregularly through New York, it enters Pennsylvania, and there bifurcating, sends one prong to the west as a divide between the waters of the lakes and the Ohio, while the other becomes the steady, regular ridge which gave it the name of Alleghany, and thus passes on southwestward through Virginia. At no point has it ever been the geological divide. Its course, commencing in the Archean rocks, has passed through nearly every series of formation, and comes into Virginia in the Carboniferous strata. The geological divide—the line between the fossiliferous and the non-fossiliferous rocks—lies, in Canada, to the west of it, but from New York south into Virginia is far to the east. Reference to Dr. Hitchcock'k map will show this. But at the locality noted these positions are changed; the water-divide becomes the eastern chain, and the geological divide is the western, returning, it may be said, to the positions occupied in the region where they originated. These relations are shown on the large map accompanying the present paper. For several miles, the track of the Norfolk and Western Railroad

Jan 1, 1888

By W. E. Oching, M. M. Ghomshei

Attracting and retaining workers in mining industry has become an uphill battle to many mining companies. As workers with significant experience retire, it is getting more difficult to attract not only new workers but also top talent to the mining industry to replace professionals exiting the workforce. To make matters worse, students’ enrolment in the post-secondary mining programs in Canada and USA is continuously declining year after year for reasons not directly linked to job market. This raises a question of how can the future needs of mining be met? This paper focuses on avenues for collaboration of industry and educational institutions to meet the current and future needs of mining. It provides effective approaches that mining institutes can engage with program advisory committees, role of the mining industry in supporting both faculty and students, how to harness the benefits of diverse workforce in the country and use of innovative technologies to attract young workers in mining. This work presents Human Resources (HR) professionals with tools that they can use to hire and retain skilled workers with strong interest to work in the mining industry. It also provides HR professionals with an opportunity to re-evaluate their restructuring practices during economic downturns as they reduce number of employees on temporary or permanent basis. The paper stresses the need of working together of the mining stakeholders including mining industry, academic institutions, First Nations’ communities and provincial(state) and federal governments to meet the current and future demands of mining as the industry experiences shortage of labour and low students’ enrolment in post-secondary mining programs. It is shown that mining educational institutes can enhance their programs and recruitments through establishing a better communication with all stakeholders. This communication can be facilitated by creating a national advisory board, to work with all mining programs at the national level for sustainable mining.

Jan 1, 2023

By Z. Q. He

This paper introduces the structure and working principle of SLon magnetic separator that has excellent performance in iron removal, and summarizes a part of the examples of applications, which applies this machine to remove iron from non-metallic ores, and shows widespread prospect of application of this machine in the purification of non-metallic ores.

Jan 1, 2014

By H. R. Shell

Of three known compounds in the ternary system K20 - PbO - SiO2, one having the composition K2Pb4Si8021 crystallizes into a structure with asbestiform properties. This compound, whose silicon-oxygen ratio is between that of the layer silicates (for example, mica) and the double-chain amphiboles, crystallizes in the tetragonal system. It malts, apparently congruently, at 779° C. The fiberized product prepared from crystals is fluffy and closely resembles natural asbestos in appearance, but is more brittle and has less strength. However, potassium-lead silicate may be separated into fibers with a uniform diameter of 200-300 A.U., and the fibers show with the electron microscope the s criteria that have been interpreted as indicating a hollow tube structure in chrysotile asbestos. Since very few inorganic crystalline compounds have such a structure, the material has unusual scientific interest. Microcrystalline potassium-lead silicate was rapidly and completely formed when powdered glass of the same composition was heated to 650° - 700° C, but macrocrystals grew only slowly from the viscous massive glass. Maximum growth rate was 0.12mm. per hour at 700° C.

Jan 1, 1957

By Cory McElprang, Enamul Hoque, Aaron Thomas, Scott A. Jacobs

Crosshole Sonic Logging (CSL) only evaluates concrete on the inside of reinforcing cages leaving the outside unevaluated unless other types of testing are performed such as Perimeter Sonic Logging (PSL). While there have been some reports of PSL testing having accurately identified anomalies (e.g. Samtani et al 2005), experience by Case Foundation Company has indicated otherwise where false positives were determined with subsequent coring. Numerous cases of PSL false positives are presented as well as a study where a shaft was installed with both inside and outside tubes, and CSL and PSL data were compared. To date, there is very limited data published on perimeter sonic logging, or Gamma-Gamma Logging (GGL) with tubes on the exterior of drilled shafts. Several cases will be presented where false positives were experienced where PSL testing was performed. In addition, a direct comparison will also be presented where a shaft was installed with both tubes on the inside and outside where CSL and PSL data is compared. BRIEF HISTORY – CSL TESTING AND TUBES ON INSIDE The general procedure of Crosshole Sonic Logging (CSL) testing includes attaching tubes to the reinforcing cage to be able to send a transmitter in one tube and a receiver in another tube with which a sonic pulse is emitted from the transmitter and received in another tube. The time taken for the sonic pulse to travel between the tubes is measured and compared to expected values for the known distance between the tubes. Any increase in time from expected values indicates the sonic pulse traveled through a media other than homogeneous concrete such as objects in the path (spacer wheels, steel bracing, etc.), tube spacing, or soil inclusions. However, variations in arrival time can also result from differences in concrete density. The tubes have traditionally been placed on the interior of the reinforcing cage which protects them during hoisting and placement of the cage and reduces wave refraction caused by modulus of elasticity differences between steel and concrete. This allows the concrete within the interior of the reinforcing cage to be evaluated, but the concrete outside of the cage is excluded from traditional CSL testing. As a result, alternative integrity testing has been developed to not only provide different ways to evaluate the integrity of drilled shafts but to also address the issue of evaluating the concrete outside of the reinforcing cage. These alternative testing methods include Gamma-Gamma Logging (GGL), Thermal Integrity Profiling (TIP testing) and Perimeter Sonic Logging (PSL) which is similar to CSL testing but instead of the tubes placed inside the reinforcing cage, the tubes are placed on the outside of the reinforcing cage as shown in Fig. 1.

Jan 1, 2019

By Eugie Kabwe

The effective employment of a pretensioned bolt within support structures requires an appropriate installation tension as a result of sufficient bolt head/nut preload. In this paper, a load indicator washer (LIW) able to withstand an assigned static loading as well as provide an appropriate pretension is presented. The different LIW breadths are numerically analyzed with ABAQUS finite-element code to estimate deformation when a designated 60 kN preload is applied. The numerical simulation employs the bilinear isotropic hardening constitutive law governed by the von Mises yield criterion. The simulation also considers the nominal temperature of the nut-LIW-rock bolt connection. Therefore, long-term relaxation effect on bolt pretension as a result of stress relaxation is neglected. The compressive force required to achieve the LIW predetermined deformation is the bolt pretension. It is drawn from the simulation results that LIWs with thicknesses of 1.5, 2.0, 3.0, 3.5 and 4.0 mm are completely flattened when subjected to 28, 42.5, 65, 76 and 88 kN preloads, respectively.

By A. G. Mattes

This paper presents an overview of passive, engineered, biologically-based anaerobic bioreactor (ABR) treatment systems of the sort that can be used to remove dissolved copper from mine wastewaters. The paper begins with a brief history of the origins of this treatment technology and continues with a discussion of principles of engineered wetlands (EWs, advanced kinds of constructed wetlands, CWs) and the use of vertical sub-surface flow (VSSF) varieties that contain pulp & paper biosolids as the reactive medium for EW cells. A brief outline of a procedural methodology used in evaluating the potential for biological treatment on a site-specific basis is also included. An introduction to the microbiology of passive biologically-based treatment systems is followed by some recent research results in the general area of wetlands and ABR research. The paper concludes with a brief discussion of several sites known by the authors to have successfully (or not) demonstrated the potential of this treatment option.

Jan 1, 2007