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By S. Kobayashi, N. Ohara, T. Aoki, S. Sakurai, M. Iwano, M. Shimo, I. Otsuka

"This project is the upgrading of a commuter line of approximately 76 km to improve the railway system in Istanbul metropolitan area. Railway tracks have been connected between Asia and Europe through a tunnel under the Bosphorus Strait. The length of these underground structures sums up 13.6 km. In this paper, the observational construction management based on field measurement performed at large scale underground railway station (Sirkeci station) constructed by means of New Austrian Tunneling Method (NATM) is described and the mechanism for generation of ground surface settlement above this station is discussed.Buildings above Sirkeci station are overcrowded. About 60% of the buildings are made of reinforced-concrete (RC) and others are of brick. Based on the investigation into the predicted settlement and inclination, necessary actions such as structural reinforcement and soil improvement have been conducted for dilapidated buildings.Rock mass around Sirkeci station consists of alternative strata of sandstone and mudstone. It is overall soft rock with an elastic modulus of 150 MPa, partly including fractured zones. Overburden is about 30 to 40 m. The thickness of unconsolidated sand layer distributed on the bedrock is about 10 m. As a result of in-situ permeability tests, the coefficient of permeability of the sand layer is about 1.0x10-3 cm/s. Fill layer of about 10 to 25 m in thickness covers the sand layer at the ground surface. The fill layer contains a lot of artificial waste like splinters of wood, brick chips and mortar chips, etc. in addition to gravel, sand, silt and shells. The coefficient of permeability of fill layer is estimated to be 1.0 x10-2 cm/s, which is one-order greater than that of the sand layer. Fill layer consists of ancient city ruins of ages respectively from the Eastern Roman Empire, the Byzantine Empire and the Ottoman Empire and has a lot of gaps.The underground part of the Sirkeci station was excavated through a ventilation shaft. Ground surface settlement occurred more than predicted. Therefore, back analyses were performed in order to precisely predict the next-step settlement. However, back analyses with elasto-plastic models could not simulate the actual phenomena and hence, an anisotropic-damage-parameter model developed by Sakurai (1999) was adopted for the back analysis. Furthermore, as the excavation of tunnel proceeded, the ground surface settlement exceeded the predicted value again. Based on the monitoring results, it seemed that pore water pressure decreased by the tunnel excavation resulted in the soft rock and soil to be contracted due to the increase in the effective confining pressure. A coupled hydraulic-mechanical analysis was applied to explain the relationship between decreased pore water pressure and ground surface settlement. The settlement due to drainage from tunnel wall was well-estimated in the coupled hydraulic-mechanical analysis.However, further settlement occurred more than predicted again and again. Though it was very difficult to clarify the reason of the large settlement, it was recognized that the unexpected ground surface settlement resulted from the existence of the large gaps in the fill layer that was greatly compressed. The final settlement reached up to 327 mm."

Jan 1, 2015

By C. van Buuren, R. F. Sandenbergh, P. J. Pieterse

Gold extraction from double refractory ores using conventional cyanidation has proved challenging due to the presence of carbon within the ore. Carbon particles may adsorb leached gold resulting in gold losses to tailings, i.e. preg-robbing the gold. Some of the preg-robbed gold may be recovered by the application of the HiTeCC process on CIL tailings. The process developed by Metso Outotec involves caustic conditioning of the tailings followed by high temperature desorption and simultaneous adsorption onto virgin activated carbon of the aurodicyanide. The aim of this paper was to develop a model for the HiTeCC process which could be used to support design and optimisation of the process, based on the adsorption characteristics of the preg-robbing and activated carbons. It was found that accurate experimental isotherms can be used to predict the behaviour of preg-robbing adsorbents. Comparing the sorption isotherms for preg-robbing ores and activated carbon indicated similar dependencies on temperature and ionic composition. Applying boundary layer diffusion models coupled with experimentally determined isotherms for preg-robbing ore and activated carbon, the HiTeCC process was successfully simulated at experimental and plant scale. Gold recovery of the HiTeCC process is most sensitive to the temperature of desorption and gold loading of the activated carbon, with increased temperature improving recovery. The gold loading of the activated carbon in the process should always be maintained lower than that of the normalised pregrobbing carbon gold loading to ensure favourable conditions for adsorption onto the activated carbon. Caustic conditioning stabilises adsorption and is therefore not necessary during the desorption stages of the process, but potentially improves recovery during adsorption. Keywords: Preg-robbing, refractory gold ores, HiTeCC, aurodicyanide

Jan 1, 2020

By S. A. Willis

For over 150 years gypsum from Nova Scotia has been shipped via water to the United States east coast. The history of the movement has been one of continual improvements in quarrying, loading, and shipping. At the start, man-size rock quarried by hand auger and black powder was loaded into horse-drawn carts, hauled to the waterfront, and dumped into 100-ton sailing schooners. Last year the Canadian Gypsum Company completed the latest and most modern of these successive installations for the movement of this Nova Scotia product. The new system loads crushed gypsum into 11,600-ton vessels at Hantsport in two hours' time at high tide. At the head of the bay of Fundy are located vast deposits of gypsum. The tidal rise and fall of 45 feet twice a day, with its attendant swift currents, has always presented major navigation and shipping problems. When the tide is low, the Hantsport ship-loading pier is high and dry, with no water within 400 feet. Three hours later a large river has flooded in (running up hill) and large steamers can dock at the wharf. Before high water, the ship has been loaded and -there is a depth of 30 feet or more of water around the wharf. At high water, the ship sails away on the ebbing tide as the river runs in the other direction. Tides are caused by the gravitational attraction of the moon and sun on the ocean. When both celestial bodies are pulling together the 'spring tide' results, which means a 50-foot variation from high to low. This occurs at new and full moon. A week later, when the sun and moon work in opposition, the difference is only 32 feet between high and low water. The bay of Fundy, having a funnel shape (150 miles wide at mouth from Yarmouth to Portland, while the upper estuary at Hantsport is only one mile wide), builds up a tidal influence from 10 feet at the mouth to an average of 45 feet at Hantsport.

Jan 1, 1948

By Claude Hubert, Robert Sansfaçon

"The Malartic gold camp includes the Malartic Gold Fields, Barnat, East-Malartic, Canadian Malartic and Sladen mines. From 1935 to 1984, these mines have yielded 212 403 kg of gold. They occur within a 900 m wide belt of highly sheared, dislocated and faulted volcanic and sedimentary rocks (Piché and part of the Pontiac groups) herein named the Malartic Tectonic Znne (MTZ). The zone trends WNW-ESE and separates two lithotectonic sedimentary domains, the Cadillac to the north and the Pontiac to the south. The sedimentary domains are characterized by their coherent fold generations consisting of open to tight reclined and recumbent F1 folds that have been refolded into series of asymmetric upright F2 folds. A flat-lying schistosity (S1 ) and a vertical pressure-solution cleavage (S2) are ubiquitous throughout. Discrete sets of brittle and brittleductile faults are synchronous and parallel to each of these two fabrics.The MTZ trends N320° in the northwestern sector of the town of Malartie, changing to N2800 at its easternmost extremity. The Malartie and Sladen faults constitute its northern and southern boundaries respectively. These two faults also bound another set of faults oriented N305°. Throughout the MTZ, the faults at N280° and N320° and those at N305° outline a series of anastomosed motifs that constitute the principal structural feature of the Malartic district. Locally, a fourth set of minor faults at N065° combines with the other three prominent sets. All these faults have disrupted the gold-bearing volcanic, sedimentary and intrusive rocks encountered throughout the MTZ.The MTZ comprises numerous lozenge-shaped blocks of komatiites and basalts or greywackes and black shales which are cut by disjointed dikes, sills and small intrusions of felsic and mafic rocks. The latter includes gabbro, diorite, lamprophyre, monzonite and pegmatite. They frequently fill conjugate sets of fractures. In some areas, they are clustered into coalescent intrusions. The present morphology of these intrusive bodies( cube, chocolate-tablet boudin, parallel epiped and cigar) is not representative of their primary forms but the result of late shearing and faulting indicative of a major tectonic event subsequent to their emplacement. The intrusions were injected during a brittle stage of deformation related to the F1 folding but prior to the development of the F2 folds and subsequent tearing and shearing by late brittle and brittle-ductile faults . The ultramafic and mafic rocks are intensely altered to serpentine, tremolite, actinolite, carbonate, biotite, hematite and pyrite according to the nature of their proto/it h. In the vicinity of the MTZ, all lithologies exhibit mineral assemblages indicative of the upper greenschist or lower amphibolite facies of metamorphism.The structural evolution of the MTZ involved superimposed folding, shearing, transposition, mylonitization, brittle and brittle-ductile faulting. Each lenticular motif results from the combined effect of conjugate sets of shear zones that outline lozenge-shaped blocks where strain markers indicate different strain states from cores to margins. Bedding in ultramafic flows and/or sedimentary rocks is either NW-SE or NE-SW within the blocks but, in the vicinity of the Malartie and S laden faults, it has been rotated to become subparallel to the faults.Ore shoots are most commonly associated with altered and deformed bodies of diorite and monzonite, or some mafic and ultramafic schists and, at the Canadian Malartic, Sladen and East Malartic mines, with metasedimentary rocks. The shoots occur in close proximity to the various faults of the MTZ but the gold itself is intimately associated with pyrite, biotite and carbonate in halos bordering fractures crisscrossing the different host rocks. The density of fractures and the width of their altered zones have been significant parameters in the production of economic ore shoots. Grains of gold are visible in some veins of quartz a"

Jan 1, 1990

By Mokka Rao, Arturo Valles, Jose Rodríguez

"This paper shows a mathematical model based on finite elements, applied to bottom poured shell ingots of C.V.G. Sidor Plant. The model was used as a strategy to determine the thermal effects that are produced when solidification conditions are modified without interfering with the production process. The modification consisted of placing a thermal insulator on top of mould.The results obtained by the model indicated that the solidification time increases with insulator on base of the mould. With these results a significant number of casts were run with and without insulator. Latter by means of a metallurgical analysis it was determinated that the ingots cast with insulator reduce the level of non-metallic inclusions and the presence of internal blistering in seamless pipes.IntroductionThe process of fabrication of seamless pipes in SIDOR involves various steps of processing, such as heating the ingots, fabrication of the prelaminated, fabrication of the bored pipe, lamination of the pipe by passing through the pellegrine mill, heating the pipe in a walking bean furnace and final calibration through a calibrator mill. The material utilized for producing these pipes is provided entirely from a electrical arc furnace and casted ingots, especifically, from the superintendence of bottom pouring.The process of bottom pouring consists of positioning twelve moulds of diameters 415, 480 or 505 mm over a plate of grey cast iron in which exists a system of communicating vessels. The ingots are distributed around a central duct from which the steel flows down and filling gradually, each one of the moulds (Fig. 1)."

Jan 1, 1997

By J. B. Gwiazda

In regard to the paper by J.B. Gwiazda, it makes a highly technical approach to show that the .u factor used by designers of lemniscate-guided roof supports has never really been confirmed as a maximum and assumes that convergence is vertical. Also, the paper does not appear to take into account deflection of structures, which occurs when the lemniscate and base members are fully loaded to their maximum stress level, nor the front to back line of the support in relation to differential roof to floor movements caused by strata movements under pressure. It is not unusual for differential movements to be slightly diagonal to the line of the support, particularly in faulted areas and on gradient faces. The paper also does not take into account consolidation of fines immediately above and below the support. Generally speaking, any differential movement is from face to waste and under these conditions the .u of 0.3, which appears to be an international standard, has worked in practice. However, if the face end of the support is lower than the waste end, then the µ of 0.3 can be considerably increased, giving rise to the damage mentioned in the paper. The ideal design should aim for a slightly forward bias in the lemniscate guide so that the last increment of setting is toward the face, tending to close any fissures that may have developed during the support advance cycle. The support should also be fitted with positive set valves to ensure that a high setting load density is attained to minimize bed separation. As far as powered supports are concerned, convergence is irresistible and all powered supports converge at their rated yield load. A similar principle can be applied to the differential roof to floor movements to drastically reduce the very high forces that would otherwise be applied to the lemniscate structures and pins and that, in turn, are transferred to the base arrangement and floor loading. Any differential movements are usually catered for by the 0.3 µ factor or deflection of structures in the lemniscate guide arrangement and consolidation of the floor. The floor loading, due to differential movement, is in addition to the support convergence load and requires additional bearing area to avoid possible floor penetration. Some seven years ago, Fletcher Sutcliffe Wild Ltd. (FSW) introduced a lemniscate-guided shield support where the lemniscate linkage is connected to the roof bar through two horizontally converging rams to allow differential movement to take place above a given rated figure. This is a known force and can be guarded against, whereas with rigid connections the forces, as yet, are unconfirmed. By careful design, a horizontal force in excess of 6 MN (60 tons) opposes differential movements for a total ram loading of only 2.5 MN (25 tons), or 1.25 MN (12% tons) each. This principle can considerably reduce the length and weight of the support in comparison with a rigid pin-type structure; also, the yield load rating can be increased without affecting the lemniscate forces. The graph shows the tensile and compressive forces in a lemniscate linkage of a support with and without hydrostore. These forces react into both the roof beam and base members and, as can be seen from the support height to linkage load graph, a considerable reduction in these reactions is gained by the use of the FSW patented hydrostore system. Floor loading is considerably reduced under maximum µ conditions, and by allowing the roof bar to move with the strata, some degree of improvement to strata control is achieved in line with the assumptions in the paper. In practice, these movements have only been in the region of a few millimeters, which, in turn, reflects on the improvements to strata control by the addition of positive set valves.

Jan 1, 1987

By S. Surapunt, C. M. Nyamai, K. Itagaki

"The use of liquid copper as a medium for zinc extraction has been used in the Warner Process as a method of processing zinc-lead sulphide ore. The recovery of zinc metal is based on the reaction:ZnS(s) + 2Cu(l) = Zn(g) + Cu2S(l)In this method, thermodynamic and phase equilibria investigations of the Cu2S-FeS-ZnS and Cu2S-PbS-ZnS systems are of importance and form the basis for the liquid sulphide phase which appears as a product and is used as a solvent in the Warner Process. Phase relations in the Cu2S-FeS-ZnS and Cu2S-PbS-ZnS ternary systems were determined experimentally at 1473°K to provide a fundamental basis for the new zinc smelting process. The results show that the solid solubility of ZnS in the two systems is very small (2 wt% to 3 wt% ZnS in FeS, 4 wt% ZnS in Cu2S for the Cu2S-FeS-ZnS system; less than 0.5 wt% ZnS in both PbS and Cu2S for the Cu2S-PbS-ZnS system). The Raoultian Activity Coefficient of ZnS in the liquid mixtures and the vapour pressure of zinc over the matte in both systems is relatively large (?° = 7.7 – 15.8, Pzn(atm) = 0.088 – 1.026 for the Cu2S-FeS-ZnS system; ?° = 8.9 – 12.9, PZn(atm) = 0.075 – 0.214 for the Cu2S-PbS-ZnS system). On the FeS-ZnS join, the only phases detected are FeS and iron-rich sphalerite (Zn, Fe)S. The binary join mixture occurs at about 92 wt% FeS-8 wt% ZnS at 1473°K. Electron microprobe examination of the quenched samples indicate about 47 wt% to 48 wt% FeS in sphalerite and about 2 wt% to 3 wt% ZnS in the iron sulphide phase. On the Cu2S-ZnS join, microprobe analysis reveals that the maximum solubility is 4 wt% Zn in liquid Cu2S and 3.6 wt% Cu in solid ZnS. In the Cu2S-PbS-ZnS ternary system, microprobe analysis of the quenched samples indicate on average, 5 wt% ZnS in the liquid phase region. The only phases detected on the PbS- ZnS join are ZnS and PbS. The eutectic phase contains, on average, 13 wt% ZnS. The phase relationships, very low solid solubilities of zinc sulphide in the liquid mixtures of both Cu2S-FeS-ZnS and Cu2S-PbS-ZnS systems, coupled with the high Raoultian Activity Coefficient of ZnS as well as the high vapour pressure of zinc over matte all favour the partitioning of zinc metal into the vapour phase. This new process is cost effective and bypassesthe expensive and tedious conventionaltechnique of zinc production involving oxidationof the sulphide ore by roasting followed bya reduction process to extract the zinc. Theresults indicate that a new zinc smelting technologyusing the Warner Process would bemore efficient and preferable over the traditionalmethods of zinc extraction."

Jan 1, 2002

By D Matthews

With the increasing demand for quality-specific ores, coupled to the reality of even more complex minable iron ore reserves, there is a growing need for real-time online material analysis of plant feed and product. For a full system mass balance, the combination of conveyor weight scales, flow and density transmitters are required. This alone does not guarantee product grade. For optimal process control and material blending, real-time online elemental scans in combination with the mass weighting is becoming more than a ‘nice to have’. These elemental scans located at key positions, enable the mining and plant operators to make informed decisions timeously, therefore ensuring product outcomes and optimising operations where material grade and the control thereof are important. Typically, these units follow the mining and primary crushing circuit as well as on the product conveyors, low-grade conveyors and tailings lines. Deployed after the primary crushing circuit, an analyser acts twofold:1. guaranteeing mining production, and2. processing facility feed blends.The analysers on the product conveyors guarantee saleable product. The analysers on the low-grade conveyor and tailings line complete the elemental balance and identify the potential of the low-grade and tailings for future processing. The system losses (accumulation) are calculated to determine the amount of material ‘lost’ during the processing stage which does not report to any of the aforementioned and can be used as a measure of the efficiency of the plant. A further advantage of the real-time online analysis of material is that immediate intervention can be taken in the event that the product is not of saleable product grade requirements. In the Khumani Iron Ore mine, Northern Cape, South Africa, run-of-mine (ROM), product and control analysers were included. Run-of-mine and product stockpiles are certifi ed, low-grade material is not currently directly measured, but calculated from the internal control loops. Iron units are reconciled between product and feed material.

Jul 11, 2011

By and M. V Roper, H. N. Engelbrecht

Quality control interventions emanate from process upsets and trends that move product quality beyond the natural variation expected in a stable process. The ability to detect upset conditions and react in an effective manner protects both resource utilisation and compliance to specifications. Product quality control on coal processing plants traditionally relies on the reference (combined sampler and laboratory) system to measure product qualities. The introduction of online analyser (OA) technology, applied in different configurations, creates a second source of measurement information for control decision making. The case study was done on the primary sample stream of the final product stream at Exxaro’s GG7 and 8 plants, part of the Grootegeluk complex. It explores the OLA system’s ability to meet the OEM performance guarantee, perform equally to the reference system without analytical delay time, and assesses the effort to achieve this performance in a by-line analyser (BLA) configuration. In the paper, a conceptual comparison of the two measurement systems is done and the theoretical and practical comparison of measurement performance is discussed. Results demonstrate that the OA outperformed the OEM’s performance guarantee and achieved similar levels of performance to the reference system without the response delay. Keywords: Online analyser (OLA), by-line analyser (BLA), coal quality measurement, measurement performance

Jan 1, 2020

By Katsuyoshi Tatenuma

"In order to mitigate the effect of global warming by preventing the accumulation of atmospheric CO2, a permanent fixation method of surplus CO2 as an insoluble mineral onto the sea bottom is proposed. As the proposed reduction method of atmospheric CO2, the concrete concept of this method is to form an insoluble carbonate mineral (CaCO3) by direct electrolysis of the seawater; Ca2++2HCO3 -+OH- ? ?CaCO3(insoluble)+CO3 2- (soluble)+H++H2O <not as coral reef reaction>, are directly disposed of itself onto the sea bottom. By this treatment, a concentration of carbonate is reduced in the section of superficial seawater, and therefore the absorption capacity of atmospheric CO2 increases depending upon the shift of chemical carbon equilibrium between the mass of superficial seawater and the atmosphere. As no additives are required, or no secondary waste are produced, the proposed method assuming as green-orientated, has possibility to resolve fundamentally the problem of global warming in a green orientate manner.IntroductionRecently, the amount of atmospheric CO2 has been exponentially increasing and it is a main greenhouse effect gas causing the global warming [1, 2]. The concentration of atmospheric CO2 has increased more than 30% (370ppm in 2001) during only last two centuries, therefore approximately 750 Gton-C of CO2 currently exist in the atmosphere, in which 180 Gton-C of CO2 are accounted for the increment during two centuries [1, 3, 4]. In order to avoid the progressive increase of CO2 global abundance, 3 Gton-C of the incrementing amount per year [4], have to be removed annually from the atmosphere."

Jan 1, 2008

By D. G. Krige

I read the paper “The jackknife approach” with interest. There appears to be a widespread misunderstanding of the kriging variance as a measure of the error variance of the kriged grade estimate of an ore block. Virtually all mineral deposits display skew frequency distributions and are subject to the well-known proportional effect. Thus, it is usual to find in an ore body, when subdivided a really into subpopulations, that the variances of the grades (or the total sills of the variograms) for the subpopulations will be correlated with the corresponding mean grades (usually linearly with the squares of the mean grades). Thus, the variogram will be stationary.

Jan 1, 1996

By John C. Machisak

Statistical data on injuries in the metal and nonmetal industry of the United States first became available to the Bureau of Mines by collecting reports from the operators for the calendar year 1911. Since then reports have been collected annually. The present bulletin, covering the calendar year 1954, is the 31st publication (1933-34 was published as Bulletin 398) containing statistical data on injuries at metal and nonmetal mines and related plants, and it 1s the first such bulletin to be published since 1942. The last publication was Bulletin 461, Metal and Nonmetal-Mine Accidents in the United States, 1942. The unpublished statistics for 1943-53 may be found in the Appendix of this bulletin. The Bureau of Mines is authorized to collect data on injuries and related employment at metal and nonmetal mines, but there is no Federal law that compels operators to submit such information. Therefore, all materials submitted are voluntary responses to the Bureau&apos;s requests for information. The figures presented herein may not be complete for the entire industry, nevertheless, every effort has been made to make them so, and the data given are believed to be representative of the hazards to which metal and nonmetal workers are exposed. Moreover, the figures are comparable as between States-which is significant in view of the lack of uniformity among the States as regards classes of plants covered by State laws, classes of injuries covered by State reports, and other factors that tend to make it impracticable or impossible to compare the injury experience of one State with that of another or comprehend the relative importance of the various causes of injuries in the industry as a whole.

Jan 1, 1957

By Horace F. Silliman, Curtis L. Wilson, Eugene C. Little

The change in electrical resistance and Rockwell hardness (16-100-B) of copper alloys containing Ni2Si and Co2Si was determined by annealing the quenched solid solutions at various temperatures for various lengths of time. The rate of precipitation of Nisi, as measured by the rate of decrease of electrical resistance and increase of hardness, increased with annealing temperature up to a certain point, depending on the percentage of Ni2Si present. At these temperatures discontinuities in the rate: change occurred. Similar discontinuities in the Co2Si alloys were no The solubility of Co2Si in copper was found to be 5 per cent at 970" DISCUSSION (Robert F. Mehl presiding) R. I?. Mehl, Pittsburgh, Pa. (written discussion).—The electrical conductivity and hardness curves reported in this paper are interesting, particularly because many of the anomalies of the precipitation processes are evident from such curves. The title of the paper, however, is deceptive, for it implies that measurements of electrical conductivity and hardness are suitable to determine the rate of precipitation. Neither of these methods is suitable for a quantitative measurement of rates of reaction or of precipitation in the solid state. Electrical conductivity in some alloys shows an anomalous increase during the first stages of aging at low temperatures; it is notably sensitive to strain and to state of subdivision. I have plotted the conductivity curve representing the decomposition of the phase at 555" C. in the copper-aluminum system, given in the paper by Smith and Lindlief (Fig. 47, p. 93) as a rate of reaction curve, and compared it with the curve determined by area evaluation (Fig. 7); these two curves are not coincident. Hardness is likewise very uncertain, for it is so much dependent upon particle size. Of the various methods proposed for the study of rates of reaction and precipitation, the evaluation of volume of reaction product from the respective area of matrix and reaction product on the photomicrograph is the most trustworthy; suffering, perhaps, only from low sensitivity during the early stages. This method, used originally by Davenport and Bain and now by Smith and Lindlief, is suitable for

Jan 1, 1933

By Walid M. Abdellah, Soliman Abu Elatta A. Mahmoud, Hanaa A. Abu Khoziem

The high-grade Th-U-Y zone is one of the numerous mineralized zones found in the El Garra El Hamra hydrothermally altered syenites in southwestern Egypt. It is characterized by the thorium minerals thorite and thorogummite, which are closely associated with xenotime-(Y). This zone of mineralization is localized in the eastern part of the El Garra El Hamra hydrothermally altered syenites. This zone does not relate to the first phase of syenites that appeared on the surface but is linked to the other, hidden phase of the syenitic body. Additionally, the fluids responsible for the mineralization of this zone belong to the late-stage hydrothermal event as well as the fault action due to the fact that it had continued reactivations for a long period of time. The studied mineralized zone also contains ceriopyrochlore-(Ce),(Ce,Ca,)2 (Nb,Ta)2O6 (OH), fluorite (CaF2) and barite (BaSO4), which are found in considerable amounts, whereas apatite (Ca5(PO4)3F) and chromite (FeCr2O4) are rarely found together with Fe-oxi-hydroxides (hematite and goethite) with a minor amount of jarosite (KFe33+(OH)6(SO4)2). Finally, the main constituent mineral in the zone is the pseudomorph perthite in addition to quartz, which is found as deformed crystals. A technological sample was collected from this zone and was found to assay 4.62 weight percent thorium (Th), 0.37 weight percent uranium (U) and 3.12 weight percent rare earth elements (REEs). From the chemical and mineralogical composition of the studied technological sample, the leachabilities of Th, U and REEs were investigated using sulfuric acid (H2SO4) agitation leaching and pug leaching methods. The latter was found to be preferred under the conditions of 0.54 ton H2SO4 per ton of altered syenite at 110 °C for two hours.

By Sadegh Elyasi

TBMand roadheader are two dominating excavation machines in underground tunnelling projects. The performance of these two tunnelling machines has been reviewed and analysed individually by many researchers from multiple points of view. However, there are almost no studies that have made an extensive comparison between these two machines, mostly from financial points of view. The current study is intended to characterize both financial and technical status of these two mechanical tunnelling machines in one of the biggest coal mines in Iran. The main objective of this study is to define the best method and equipment that meets a predefined economic goal, which is mainly to maximize the net present value. To this end, a technical and financial model based on the geomechanical and financial parameters involved in the project has been prepared and the financial part of the project has been carried out by applying COMFAR III financial analysis software. Subsequently, a sensitivity analysis of the model was conducted in order to evaluate the effect of involved parameters on the project. According to the results, a roadheader has better economic justification than a TBM, while the TBM has a better advance rate than the roadheader.

Feb 12, 2021

By Frank C. Canney

The word "other" in paragraph 4, line 11, column 1, page 205, should read "over;" the correct version of reason 2, this paragraph, is: &apos;L. . . 2) to evaluate the usefulness of certain geo-chemical techniques, V. C. Kennedy and S. W. Hobbs of the USGS had already studied the distribution of copper, lead, and zinc in the soils (both in background areas and over veins) and in the water and plants, providing a criterion for measuring the magnitude and effect of soil contamination; ...9 On page 206, in the top left hand corner of Fig. 1 (in the area bounded by 47°35&apos; and 116°10), the reference to Fig. 3 is incorrect. The area of Pine Creek, South Fork Coeur d&apos;Alene River, and portion of Big Creek (the area which includes, from left to right, Kingston, Pinehurst, Smelterville, and Kellogg) should be identified as that of Fig. 2A. The headings for columns 1, 3, and 4, Tables I and 11, page 209, column 2, were reversed when the paper was printed. The corrected tables are:

Jan 1, 1961

By M. Ziegler

The article deals with the use of a digital twin in the assessment and optimization of a conveyor system in the Chilean copper mine. This example shows that a digital twin is initially just a new (albeit powerful) tool with which the system behavior can be examined. The benefits for the customer arise through the system identification and automatic detection of critical deviations from the target state. This knowledge allows mine management to react and coordinate operational and/or maintenance counter measures to insure optimal performance of their conveyor system. The information derived from the BeltGenius digital twin also allows mine management to gain a clear perspective of the overall efficiency of their conveyors, which will be invaluable for future conveyor component selections.

Mar 2, 2022

By Ned H. Snyder

In recent years the Government and other large consumers of coal have appreciated more and more the desirability of definitely determining by chemical analysis and test the character and quality of the coal they purchase. Higher prices for coal point forcibly to the need of giving more study to engine room and boiler room efficiencies and economies; this implies an intimate knowledge of the character and quality of the fuel used. Analyses and tests of delivered coal furnish data whereby power plant results can be comprehensively studied and a continuous check maintained on the coal and on the conditions of plant operation. Under authority of acts of Congress making appropriations for technologic investigation of fuels and the analyzing and testing of fuels belonging to or for the use of the United States Government, a laboratory is maintained at the Pittsburgh station of the Bureau of Mines, where samples representing deliveries of coal purchased for Government use are analyzed and tested.

Jan 1, 1923

By Bever M. B., Floe Carl F., Hung Liang

Data on the solubility of hydrogen in iron-silicon alloys are of practical interest, as hydrogen causes gas unsoundness and embrittlement in iron and steel and is also a factor in the metallurgy of cast iron. Zapffe and Simsl have recently demonstrated that in deoxidized iron and steel castings gassiness and bleeding are primarily functions of the hydrogen content of the liquid metal. These authors also suggested convincingly that ordinary melting and casting practice provides several sources of hydrogen for absorption by the metal. Norbury and Morgan2 and Boyles3 have shown that dissolved hydrogen affects the graphitization of cast iron. Schneble and Chipman4 included in a study of the effects of superheating on the properties of cast iron an investigation of the part played by hydrogen. Schwartz, Guiler and Barnett5 investigated the significance of hydrogen in the metallurgy of malleable cast iron. A complete interpretation of investigations of this kind calls for equilibrium values of the solubility of hydrogen in the liquid and solid phases. From the theoretical standpoint, the solubility of gases, especially hydrogen, may reveal some aspects of the nature of liquid metallic solutions. This was implied in the early work of Sieverts6 on the effect of alloying additions on the solubility of hydrogen in copper. Recent work by Bever and Floe7 has shown that in liquid copper-tin alloys the solubility of hydrogen changes abruptly at the composition of the intermetallic compound Cu3Sn. It is of considerable interest to determine whether liquid alloys of iron also have compositions at which the solubility of hydrogen exhibits a discontinuous or otherwise unique behavior. Among the various alloys of iron the iron-silicon system is important because of the presence of silicon in various structural alloy steels, transformer sheets, cast irons and special acid-resisting castings. The various grades of ferrosilicon, finally, cover almost the entire remainder of the composition range. Published information on the solubility of hydrogen in iron-silicon alloys is meager. The first values for pure liquid iron were reported in 1910-191 1 sieverts and Krumbhaar8 and by sieverts.9 They found that 100 grams of iron absorbs 28 c.c. of hydrogen at 1550°C and One atmosphere pressure, and 31 C.C. at 1650°C. In 1938 Sieverts, Zapf and Moritz10 published a value of 26.3 C.C. at 1550°C. Data on the solubility of hydrogen in liquid iron-silicon alloys and in liquid silicon are not available. Martin1&apos; investigated

Jan 1, 1947

By Bever M. B., Floe Carl F., Hung Liang

Data on the solubility of hydrogen in iron-silicon alloys are of practical interest, as hydrogen causes gas unsoundness and embrittlement in iron and steel and is also a factor in the metallurgy of cast iron. Zapffe and Simsl have recently demonstrated that in deoxidized iron and steel castings gassiness and bleeding are primarily functions of the hydrogen content of the liquid metal. These authors also suggested convincingly that ordinary melting and casting practice provides several sources of hydrogen for absorption by the metal. Norbury and Morgan2 and Boyles3 have shown that dissolved hydrogen affects the graphitization of cast iron. Schneble and Chipman4 included in a study of the effects of superheating on the properties of cast iron an investigation of the part played by hydrogen. Schwartz, Guiler and Barnett5 investigated the significance of hydrogen in the metallurgy of malleable cast iron. A complete interpretation of investigations of this kind calls for equilibrium values of the solubility of hydrogen in the liquid and solid phases. From the theoretical standpoint, the solubility of gases, especially hydrogen, may reveal some aspects of the nature of liquid metallic solutions. This was implied in the early work of Sieverts6 on the effect of alloying additions on the solubility of hydrogen in copper. Recent work by Bever and Floe7 has shown that in liquid copper-tin alloys the solubility of hydrogen changes abruptly at the composition of the intermetallic compound Cu3Sn. It is of considerable interest to determine whether liquid alloys of iron also have compositions at which the solubility of hydrogen exhibits a discontinuous or otherwise unique behavior. Among the various alloys of iron the iron-silicon system is important because of the presence of silicon in various structural alloy steels, transformer sheets, cast irons and special acid-resisting castings. The various grades of ferrosilicon, finally, cover almost the entire remainder of the composition range. Published information on the solubility of hydrogen in iron-silicon alloys is meager. The first values for pure liquid iron were reported in 1910-191 1 sieverts and Krumbhaar8 and by sieverts.9 They found that 100 grams of iron absorbs 28 c.c. of hydrogen at 1550°C and One atmosphere pressure, and 31 C.C. at 1650°C. In 1938 Sieverts, Zapf and Moritz10 published a value of 26.3 C.C. at 1550°C. Data on the solubility of hydrogen in liquid iron-silicon alloys and in liquid silicon are not available. Martin1&apos; investigated

Jan 1, 1947