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By D. D. Smith, D. P. Squier, E. L. Dougherty

A system of differential equations describing the temperature behavior of fluid injected at constant surface temperature in a well is derived and .solved analytically. A formula for the fluid temperature at any time and depth is given, as well us a special formula valid for very large times. These formulas are used to calculate temperatures for several typical cases. The results indicate that, initially, the temperature of the water entering the formation is considerably lower than the injection temperature. This condition lasts for only a short period— less than three days for most cases of practical interest. Following this highly transient period, during which the temperature of the fluid entering the formation builds up to about 50 to 75 per cent of the injection temperature. the system enters a quasi-steady state in which the temperature changes are very slow. After severl years, the bottom-hole temperature will still be 50" to 100°F lower than the injection temperature, hilt the heat losses may he tolerable. INTRODUCTION Predicting the behavior of a hot-water flood requires that the temperature of the water entering the injection interval be estimated. This report describes the development and solution of a system of equations which describes the temperature behavior of the injected water in the wellbore with certain simplifying assumptions. The only previous means known to the authors for describing such a process is that of Moss and White.' Their results appear to be close to those obtained by our method in the practical cases which were compared; this agreement is largely due to the fact that in our method temperature soon approaches a quasi-steady state, as was assumed in their method throughout. However, our model covers all times, is continuous (whereas the Moss-White model depends on breaking the depth into discrete intervals) and. we feel. more closely describes the physical problem. FORMULATION OF THE PROBLEM PHYSICAL SYSTEM AND ASSUMPTIONS The injection procedure consists of pumping water at a fixed surface temperature T., down an infinitely long cylindrical well or tubing of inner radius Any material exterior to the water column such as mud, casing, or cement is regarded as part of the formation. The general behavior of the system may be described qualitatively as follows. When the hot water is first introduced into the system, the temperature difference between the formation and the water is large, resulting in a high rate of heat transfer. As a result, the temperature adjacent to the wellbore rises very quickly. Because the segment of the formation adjacent to the wellbore largely controls the heat transfer rate, the heat transfer rate will become relatively constant when this portion has reached a temperature close to that of the water opposite it. The temperature of the water and formation then increase very slowly with time. The length of the initial highly transient period and the temperature of the water at its conclusion will be functions of depth, injection rate, injection-string radius, surface injection temperature and the physical properties associated with the water-formation system. The following additional assumptions were made. 1. There is no heat transfer by radiation in the system. 2. There is no heat transfer by conduction in the vertical direction in either the injection stream or the formation. 3. The linear volumetric and mass flow rate of the water is constant throughout the injection stream. 4. No horizontal temperature gradient exists in the injection stream. 5. The product of density and heat capacity is constant for both the water and the formation, and the formation thermal conductivity is constant. 6. Initially, both the water in the wellbore and the reservoir are at a temperature given by the (constant) ambient surface temperature plus the product of depth and geothermal gradient (assumed constant). At large distances for the wellbore (r m), the formation will remain at this temperature. 7. The water temperature and the formation temperature at r — r,, are equal for all depths D. DERIVATION OF EQUATIONS The differential equation satisfied by the fluid temperature T,(D, t), which is obtained by writing a heat balance on a cylindrical differential of volume dV of the injection string between the depths D and D i dD, is

By G. Barbery

In Mineral Processing, the objective of most processes is the separation of mixtures of minerals, which are originally associated in composite particles. Feed preparation processes grinding for instance, which take place before beneficiation or separation processes do not usually break particles at the boundary between mineral phases. They produce composite ("middlings") as well as liberated particle. It is therefore necessary, in a particulate system, to determine the proportion of particles which are liberated as well as, ideally, the size distribution of minerals which remain associated in composite particles. Up to now, there has been a lack of experimental techniques to characterize completely composite particulate systems. Heavy liquid separation which is commonly used to obtain information of this type can only be applied to simple binary cases for which one mineral has a low density (lower than e.g 2.8 ). The technique which is proposed in this paper involves the measurement of parameters on polished sections of particles mounted in a matrix, and the use of mathematical transformations to reconstruct in three-dimensions the information obtained from these measurements .

Jan 1, 1977

By A F. Kravic

Carbonyl nickel powders of irregular particle shape and low a11parent density are used extensively in the production of porous nickel electrodes for nickel-cadmium storage batteries and hydrogen-oxygen fuel cells employing alkaline electrolytes. Such porous nickel matrices are at-tractive for these intended applications as they are relatively inexpensive, are corrosion resistant, have good electrical conductivity, can be welded to form electrical contacts, have a long life (as demonstrated in alkaline storage batteries), and are rugged and vibration and shock resistant. This paper describes a feasibility study concerning the production of porous multi-layer nickel electrodes by the pressing and sintering of stacked layers of green-powder rolled nickel sheet. Background H AUSNER (1) conveniently listed nine different powder compaction processes used for forming metal powders into useful shapes. These are shown in Table I. There are additional powder metallurgy processes; however, most of these are combinations of two or more processes listed in the Table. A study of the literature revealed that every powder compacting process, with the exception of isostatic pressing and explosive forming, has been evaluated or is being used for the manufacture of porous metal electrodes.

Jan 1, 1965

By Leandro Miranda Nascimento

A maior parte da produção mundial de aço passa pela conversão de minério de ferro em grandes altos-fornos, tendo o coque como uma das matérias-primas. Por um lado, boas propriedades mecânicas a quente do coque, como o CSR e CRI, são necessárias para que o consumo de coque seja o mínimo, pois é também, junto com os óxidos de ferro, um dos maiores componentes dos custos variáveis do ferro gusa. As misturas dos vários tipos de carvões minerais utilizados exigem a participação de uma fração Hard, a mais cara e com maior poder de coqueificação, e de uma fração Soft, mais barata e inerte. Logo, quanto maior for a participação do Hard mais caro será a mistura a ser coqueificada. Uma maneira de aumentar a fração de Soft na mistura de carvões, reduzindo o custo da mistura, e ainda assim obter um coque com boa qualidade é aumentar a densidade a granel da mistura. Para isso alguns métodos já são empregados com sucesso, como o Stamp Charging e a Briquetagem Parcial. Este artigo apresenta um novo método, que consiste na densificação da mistura de carvões dentro do forno via dispositivos de vibração. Foram realizadas simulações físicas a frio e em escala reduzida para avaliar o potencial de aumento de densidade a granel da técnica. Os resultados mostram um ganho de aumento de 30% da densidade a granel da mistura.

Aug 17, 2017

By M. H. Thomas

El presente trabajo describe tres ejemplos de empresas en Australia que utilizaron carbones provenientes de fuentes locales para el encendido de sus hornos. Así también se muestra los principios generales de la operación de los hornos rotatorios, la quema de combustible pulverizado, el encendido directo e indirecto, la contaminación de cenizas y los problemas derivados de la eliminación de azufre.

Nov 1, 1984

By J. M. Uys, T. B. King

The solubility of water in silicate melts of various compositions was measured. The basicity of the silicate did not appreciably affect the water solu-bulity at low-base content (acid compositions). Near the orthosilicate composition the solubility increased with basicity for silicates in which the cation displayed a weak ion-oxygen attraction and apparently decreased for those in which the cation showed a strong ion-oxygen attraction; metasilicates of the former class dissolved more water than those of the latter. Temperature had little effect on water solubility. The experimental results are interpreted on the basis of two modes of solution, the contribution of one decreasing, and that of the other increas -ing, with increased melt basicity. In the former, solution occurs through interaction with doubly-bonded oxygen atoms and in the latter, through interaction with singly-bonded oxygen atoms, or, in very basic melts, through reaction with free oxygen ions. THE hydrogen content of a steel melt is in a large measure determined by water dissolved in the slag. In some glasses water may be a major cause of "seeds". Water vapor in the furnace atmosphere is the primary source in both instances. A knowledge of the mechanism of water solution in silicate melts should help in assessment of practical methods for its control in steelmaking and glass refining. Walsh et a1.l measured the water content, expressed as hydrogen, of 40 pct lime-20 pct alumina-40 pct silica and 62 pct manganese oxide-38 pct silica melts as a function of the steam partial pressure, in equilibrium with the melt. Tomlinson 2 and, also, Russell3 investigated this relationship for a molten 30 pct soda-70 pct silica glass. In all three investigations, the solubility of water was found to be proportional to the square root of the partial pressure of steam. Moulson and Roberts 4 confirmed this relationship for a silica glass. On the basis of the square root relationship, Tomlinson2 and Russell3 interpreted the solution reaction as "network-breaking", similar to that expected on the addition of metal oxides to silica. Walsh et al.' postulated two possible modes of solution, one the mechanism suggested by Tomlinson and Russell and the other the reaction of the water molecule with an oxygen ion to form hydroxyl ions. These two modes of solution suggest opposite effects of melt basicity on water solubility. However, little appears to be known about the effect of melt basicity on water solubility. Walsh et a1.l found, in the lime-silica system, that the water content increased slightly with increased basicity. As these authors pointed out, this does not appear to be in accord with their further observation that slags containing little or no silica dissolve very little water. Kurkjian and Russell5 measured the effect of basicity on water solubility in alkali silicates in the composition range 15 to 45 mole pct alkali oxide. They found a minimum in the water content at about 25 mole pct alkali. This was interpreted on the basis of two concurrent solution reacZions; one in which solubility was proportional to the activity of doubly-bonded oxygen and, in the other, proportional to the activity of singly-bonded oxygen. The present work was aimed at establishing the effect of basicity on water solubility in silicate melts over as wide a range of compositions as practical. APPARATUS AND EXPERIMENTAL PROCEDURE The silicate melt was equilibrated with a "carrier-gas" of accurately known water content, quenched, and analyzed for water by a vacuum fusion technique. Some pertinent details of the equilibration procedure, analysis technique, preparation, and handling of the silicates are given below. Gas-Silicate Equilibration. The apparatus used to equilibrate the melt with the gas mixture was similar to that used by Walsh et al.' but with some important modifications.6 Purification trains were provided for nitrogen and hydrogen; whenever air or oxygen was used as carrier gas the nitrogen purifiCation train was used with the copper furnace at room temperature. Gas flow rates were measured with capillary flow meters; bleeders filled with a mixture of dibromo and tribromo ethyl benzene (density about 2 g per cc) were used for convenience in controlling flow rates.

Jan 1, 1963

By Monica R. Garcia, Antonio Alberto S. Correia, Paulo J. Venda Oliveira

"The aim of this paper is to analyze the creep behavior of a Portuguese soft soil stabilized with binders in one-dimensional conditions, based on oedometer creep tests. The study focuses on the analysis of the effect of the binder content and binder type on the creep behavior of a stabilized soil. The results show that the best binder type for this soil, in terms of creep behavior, is composed of Portland cement and fly ash with a dry weight proportion of 75/25, as this promotes the development of secondary pozzolanic reactions. The results also show the decrease in the secondary compression index with the increment of the binder content, since it promotes an increase in the cementation bonds between soil particles. The general analysis of the results shows a clear dependence on C??and qu, until values of qu of 1500 kPa; after that this relationship is negligible.INTRODUCTIONThe geotechnical structures (such as embankments, dams and buildings) built on organic soils exhibit notable creep deformations, which increase the maintenance and exploitation costs and can even compromise their functioning. To attenuate the creep effects of the soft ground, some improvement techniques are frequently used, such as preloading or reinforcing the soil foundations with vertical rigid inclusions, like concrete piles, stone columns or deep mixing columns (DMCs). However, the installation of DMCs in the soft ground induces (via the arching effect) a transfer of stresses from the soft soil to the DMCs, which causes an increase in the creep settlement on the DMCs (Venda Oliveira et al. 2011).Notwithstanding the fact that the creep behavior of clays has been the object of several studies (Leroueil et al. 1985; Mesri and Castro 1987; among others), the study of the creep behavior of soil-binder admixtures has been practically ignored by the scientific community. The few studies on this theme have revealed that a stabilized soil’s creep behavior is dependent on: the type of binder (Venda Oliveira et al. 2013), the binder content (Correia 2011; Bobet et al. 2011; and Venda Oliveira et al. 2013), the stress level applied during the creep phase (Venda Oliveira et al. 2013), the organic matter content of the natural soil (Venda Oliveira et al. 2012; 2014), and the curing conditions (humidity, vertical stress applied during curing, and curing time) (Correia 2011; Venda Oliveira et al. 2012).The aim of this paper is to contribute to a better understanding of the creep behavior of a soil-binder admixture, by examining the results of oedometer creep tests. The study focuses on the analysis of the effect of the binder content and binder type on the creep behavior of a stabilized soil. Additionally, the creep behavior is correlated with the effective vertical yield stress and the unconfined compressive strength (UCS)."

Jan 1, 2015

By Ivano Andreis, Georgios Kalamaras, Mario Liti, Sebastiano Pelizza, Filippo Avesani

"THE SS640 AGRIGENTO-CALTANISSETTA PROJECT The Caltanissetta tunnel is part of the works for the construction of the second 28km-long maxi section of the SS 640 motorway of Porto Empedocle, from km 44 to the junction of Imera in Sicilian hinterland. Amongst other major infrastructure works, the €740 million ANAS (Italian national roads and highway administration agency) project consists of four twin tube tunnels three of which are being excavated by conventional means. The longest tunnel, underpasses the Caltanissetta city and has a length of 3.9km under a maximum overburden of 120m. The JV consisting of CMC of Ravenna and TECNIS SpA won the design & built tender in 2010. Construction started in early spring 2012 following the approval of detailed design and later on the approval of design for construction. THE CALTANISSETTA TUNNEL The Design Phase Tender design and detailed design foresaw the construction of 13.4m excavation diameter tunnels that were to be enlarged in a second phase to create, every 600m, 50m-long tunnel sections for emergency parking. During the design for construction project phase the JV proposed to replace the 13.4m tunnel with a 15.08 excavation diameter that incorporated apart from the two 3.75m wide lanes a 3.25m wide continuous emergency lane. This significant tunnel section modification was associated with better road safety conditions, simpler and safer construction procedures, better statics for the tunnel section while in terms of overall cost the solutions were equivalent.Geologic context The tunnel is located in the middle of the geologically known Caltanissetta basin that is intersected by various tectonic structures. The geologic context for the tunnel scale, was defined in collaboration with the University of Catania in early project phases. For almost its entire length the tunnel is excavated in the Terravecchia formation that represents the lower part of the stratigraphic sequence that was formed in the Tortoniano period of Miocene. The quite complex geological model is also characterized by the presence of the so-called Trubi formation that consists of clay and marl clay. Almost 90% of the tunnel traverses formations that are quite similar in terms of excavation behavior. Exception to this are thrust zones and a calcareous stretch of the alignment. This last segment has a length of 200m and was identified since the very beginning as a tunneling challenge due to the combination of very poor geotechnical properties and an important water load."

Jan 1, 2016

By T. F. Dumm, O. Trass, V. R. Koka, L. G. Austin

"The size distributions of carefully screened 2 size fractions of ground materials were determined using a Microtrac laser dif-fractometer. The size distributions were fitted to the empirical function P(x) = 1/[1 + (x50/x)1] where P(x) is cumulative mass fraction less than Microtrac size, x. The standard deviation of A for a 50 second test time was approximately 0.5, so that seventeen test times give a mean with an estimated error within t 0.25 (95% confidence level). Values of were 5.44, 4.82, 4.40 for a coal ground under different conditions, indicating statistically different shape distributions; the average value for mica was 2.91 owing to the high aspect ratio of the particles. The ratio of x50 to the geometric mean sieve size was 1.2 for the coal and 0.70 for mica.1 IntroductionKoka and Trass have presented evidence [1,2] that materials ground in the Szego mill [3] give different shapes depending on the milling conditions. The variations in shape were deduced qualitatively by viewing SEM photomicrographs of selected 1/2 screen fractions. This paper quantifies their observed differences in shape by using measurements of the size distributions of screen fractions examined in a laser diffractometer [4] (Microtrac, Model 7991). The basic concept is that particles of 'a given ""screen"" size will give a wider distribution of ""Microtrac"" size when the particles are flaky with high aspect ratios, and a narrower distribution when the particles approach the cubical and spherical geometries.2 TheoryAustin and Shah [5] have shown that coal screened within a 1. 1/2 upper-to-lower sieve size range will give rise to a much wider distribution of Microtrac size. They found that the screen interval of irregular fragments of comminuted coals or quartz gave Microtrac size distributions which could be described by the simple function"

Jan 1, 1988

By Thiago Félix dos Santos

A maioria dos materiais poliméricos sintéticos apresentam superfícies quimicamente inertes, isentas de porosidade e baixa energia de superfície. Este trabalho tem como objetivo realizar a modificação superficial do substrato têxtil de forma a aumentar a sua molhabilidade. Os tecidos de poliéster são hidrofóbicos e, por isso são desconfortáveis aos usuários, pois a fibra não absorve o suor do corpo, outro fator que é prejudicado pela hidrofobicidade da fibra de poliéster é o tingimento das mesmas. Portanto, tratamentos superficiais vêm sendo utilizados para minimizar esse problema e o plasma é uma técnica que se mostra bastante eficaz. O plasma ao interagir com a superfície do substrato provoca alterações químicas e físicas melhorando suas propriedades. Portanto, através do plasma é possível alterar as propriedades físico-químicas das superfícies de tecidos de poliéster, tendo como resultado o aumento da hidrofilidade dos mesmos com o incremento de grupos funcionais polares e o aumento da rugosidade em sua superfície. As amostras foram tratadas em um reator de plasma de barreira dielétrica a pressão atmosférica, em diferentes tempos de tratamento e voltagem. Após as funcionalizações as amostras foram submetidas ao teste de capilaridade, a fim de observar a melhora na hidrofilidade. Todas as amostras tratadas tiveram aumento na molhabilidade, com exceção, as amostras tratadas com 10 kV, onde não houve alteração.

Aug 7, 2018

By H. E. Peterson

A study was undertaken by the Bureau of Mines to develop a simple, reliable test for field detection of selenium in rocks and soils. Two methods are described for qualitative detection of selenium, dependent upon its form of occurrence and the presence of interfering constituents in the sample. Both methods involve fusion of the sample in a test tube to form elemental selenium that will volatilize and condense as a red deposit on the cooler upper portion of the test tube. The methods are sensitive to 10 parts per million, (p.p.m.) equivalent to 0.001 percent, and can be made semiquantitative by using suitable standard samples. INTRODUCTION Although selenium is widely distributed in the United States, the known deposits are either so small or so low grade that they cannot be processed economically for selenium alone-4/ At present, commercial production is a byproduct of the smelting and refining of base-metal ores, particularly copper.5/ About 0.75 pound of selenium is recovered per ton of electrolytic copper, and small amounts are recovered by special treatment of assorted smelter dusts and fume products. Since selenium is a strategic metal in short supply, new sources are being sought by both Government and private interests.

Jan 1, 1957

By J. S. Moretzsohn, D. F. Graham

"Airborne Synthetic Aperture Radar (SAR)was acquired over the Carajás Mineral Province, within the rainforests of the Amazon, which hosts the world’s largest Fe-ore deposit(Santos, 1986). Significant chemical weathering exists in this humid environment. PrevalentAu mineralization is thought to be generally associated with deformation zones in Archean schists.Radar data have proven to be very useful as an aid to geological mapping in the tropical rainforests of the Amazon Basin in Brazil. In these densely vegetated areas, a sense of regional structural trends is obtained as a con-sequence of the sensor/terrain geometry. The top forest canopy is the main terrain reflector of X-band radar energy, and consequently is the main terrain surface feature expressed in processed radar imagery. Radar is important for extending t,he continuity of mapped structural lineaments. Differential weathering is related to variations in radar image texture which is used to infer gross lithologic variations and relative age relationships of major rock units. Specifically, quartzites and banded iron formation are highlighted in the radar imagery due to their unique tonal and textural appearance, in contrast to schists, gneisses and metavolcanic rocks. As tropical areas are typically enveloped in cloud or mist, radar data are invaluable in providing information for logistical planning of field mapping activities."

Jan 1, 1997

By C. Sunderman, R. Jacksha

"Mine monitoring through various sensors is a vital component of successful miner safety and health programs. Data from environmental, geotechnical, infrastructure and other types of sensors are increasingly used to discover and mitigate health and safety concerns in underground mines. In many smaller underground mines, as well as in the new development headings of larger underground mines, leaky feeder communication systems may be the only available means to transport crucial monitoring data. In addition, data transport is increasingly being delivered using Internet Protocol (IP), while older forms of serial communication are being retired. This paper presents the selection, configuration and testing methodologies employed by researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH) to integrate commercially available land mobile data radios into an existing leaky feeder communication system to provide IP data transport.IntroductionTo enhance the health and safety of their mining workforce, mine owners and operators are increasingly installing environmental monitoring and control systems in underground mines. Real-time, mine-wide monitoring is becoming a reality with the implementation of the Industrial Internet of Things (IIoT) into the underground mining industry (Zhou et al., 2017). However, not all underground mines, especially smaller mines and new development headings in larger mines, have the information technology infrastructure in place to handle the data transport requirements for the newer Internet Protocol (IP)-based technologies that are part of IIoT.This was the case with a mine in the Western United States. It lacked the infrastructure to perform critical monitoring in remote headings. Therefore, the mine partnered with the U.S. National Institute for Occupational Safety and Health’s (NIOSH) Spokane Mining Research Division (SMRD) to develop and evaluate a cost-effective solution for the real-time monitoring of geotechnical conditions in relatively remote sections of the mine. This paper describes SMRD’s solution to leverage the mine’s existing leaky feeder communications system to achieve IP data transport using commercially available land mobile data radios (NIOSH, 2013; Forooshani et al., 2013; Novak, Snyder and Kohler, 2010; Yarkan et al., 2009). The solution, fully evaluated in laboratory and mine environments, requires no modifications to the existing system, is economical, simple to implement, and reliable. It also allows for transition to higher-bandwidth IT networks, such as fiber optic or WiFi, should they become available."

Dec 1, 2018

By Irving Hartmann

Following the severe starch-dust explosion in the casting department of a large candy factory nearly 2 years ago, great interest has been shown in the explosive properties and the safe manufacture and handling of powdered starches. Under the auspices of the National Fire Protection Association, a committee has been formed to prepare a code aimed at preventing dust explosions in the confectionery industry. One objective of this code will be to reduce the explosion hazards of starches that are widely used for molding, dusting, and other candy-manufacturing processes. The explosibilities of starches and starch mixtures have been studied in the laboratories of the Bureau of Mines and elsewhere. The results of the initial experiments made by the Bureau on 10 samples of cornstarch and mixtures of cornstarch with other materials have been published. In response to numerous requests for additional information, further laboratory studies have been conducted. Data have been obtained on the effects of dust concentration, particle size, moisture content, admixture of .calcium carbonate, and on the effect of oil treatment on the explosibility of cornstarch. The results of this investigation are summarized in this report.

Jan 1, 1950

By Rusty Winn

"R.E. Janes Gravel Co. is an aggregates producer is located along a paleo-channel of the Ogallala formation (locally known as the Slaton Channel) approximately 48.3 km (30 miles) southeast of Lubbock, TX. In an attempt to beneficiate the 25.4-mm (1-in.) concrete aggregate product, a log washer was installed in the processing line to liberate and remove fines (clay) from the finished product. The introduction of this extra cleaning step increased fines in the finished product, exacerbating the original problem. Several other processing options were investigated before a geological analysis was undertaken to try and define the lithology of the formation and formation characteristics in an attempt to alleviate this problem.Initial assessmentsThe mined resources are mid-Miocene to early Pliocene (16-4 mya) in age and is the eastern exposure of the Ogallala formation of the Southern High Plains escarpment. The Ogallala formation consists of coarse-grained alluvial sediments in paleovalley channel ways from the Rocky Mountains with fine Aeolian and paleosol deposition on the uplands across the High Plains region of the United States. Locally, these Rocky Mountain sediments from New Mexico were transported and deposited in a paleochannel that is approximately 0.805 km (0.5 miles) wide and 15.25 to 18.3 m (50 to 60 ft) in depth. As this channel cut across the Southern High Plains it eroded local rock sources of Late Cretaceous limestones and Triassic sandstones and mudstones incorporating them into the younger Ogallala depositional sequence.Depositional historyThe channel currently being mined is a nontypical Ogallala deposit. The Ogallala in the panhandle of Texas is divided into two units, the Couch and the Bridwell. The Couch is the older of the two and exhibits alluvial sedimentation of thicker and larger gravel (up to 76.2 mm or 3 in.) deposits fining upward to Aeolian sedimentation and thick friable caliche deposits. The Bridwell overlies the Couch and is characterized by alluvial sedimentation, a distinctive red tint and smaller gravel components (typically no larger than 25.4 mm or 1 in.) fining upward to Aeolian sedimentation and thick, well-indurated caliche cap. The Slaton Channel divides these two units and shares lithologic components of both, yet is lithologically distinct due to its Cretaceous Age limestone gravels that can be < 3.66 m (12 ft) in size. Caliche/calcrete is a calcareous (CaCO3) deposit that forms in the B horizon of soils as a rain water leachate of CaCO3 from the upper A horizon."

Jan 1, 2014

By Wojciech Masny, Andrzej Walentek

"The most common extraction method in Polish coal mines utilize pillars between adjacent longwall panels. This is mainly due to the significant depth and difficulties in maintaining stability of the gateroads. This paper presents measurements of entry convergence and range of the fracture zone around a gateroad measured with a borehole camera. The entry where the measurements were taken was located in a parallel entry separated from the gateroad by a 5-m- (16-ft-) wide pillar. The gateroad was located in a hard coal seam 900 m (2,952 ft) deep with a dip of 5°. The extraction method was longwall mining with caving and the mining height was about 3 m (10 ft).Furthermore, the ""in situ"" measurements were compared to the convergence forecast for the gateroad and fracture zone by means of numerical modeling conducted using the Phase2 Version X.X finite element program from Rocscience. The determination of the fractured zone around the openings is of great importance to successful mining practice, especially in support planning and design for longwall gateroads. Moreover, proper determination of the fractured rock zone is one of the basic elements in the process of planning the roof bolting for mine workings.INTRODUCTIONIn the Polish. hard coal mining sector, retreat longwall extraction is most commonly used (Prusek and Masny, 2007). This method is connected with the necessity to carry out a number of development operations during the first stage, including among others, driving of gateroads and a setup room.Currently, most Polish mines eliminate gateroads behind the extraction front, using the ""U"" ventilation system (Szlitzak et al., 2008). In such cases, one of the roads for the next longwall panel is driven along the caving goafs, leaving a protective pillar of some chosen width (Figure 1). The question regarding the width of the coal pillar is especially important to the stability of the gateroads that define the panel for the subsequent longwall. When analyzing the previous experience relating to this type of pillar (Junker, 2006; Rajwa, 2008; Stranzet et al., 1973; Betriebsempfehlung, 1982), one can state that there exist two solutions for the determination of its width."

Jan 1, 2010

By Camilo Uribe, Williams Calderón, Gonzalo Montes-Atenas

In industrial hydrometallurgical operations, the leaching process is often implemented via heap or dump leaching operations. During the pile up of these massive amounts particles a porous material is then formed. The manner it is constructed is crucial since it will define the permeability and other parameters determining the flowrate of leaching solution across the material. This study aims to estimate how the unsaturated permeability of the staked porous structure confined in a column-like geometry varies with and without particle size segregation. The piling up will be modeled using the Rocky® software. Different disposals of particle size distributions across the column will be simulated and their effect onto the overall column unsaturated permeability will be estimated. It was found that when the belt speed increased, the particle segregation in the column also increased. This condition is expected to improve the permeability of the porous structure in the column, probably due to the smaller compaction of larger particles when they are located at the base of the column and maintain a suitable porosity to permit leaching flowrates relatively high, suggesting better extraction results. The opposite was observed when small particles were preferentially located at the bottom of the column. These results are expected to provide an insight towards what is the best way to construct heaps and dumps.

Jan 1, 2014

By A. H. Underwood, M. –Ls. Trépanier

INTRODUCTION The King and Beaver mines of Asbestos Corporation Limited (ACL) were joined in 1957 to form the King-Beaver mine. In 1964, ACL purchased the Johnson&apos;s Asbestos Company. The combined underground workings are a part of the King- Beaver mine. Asbestos ore is mined at the rate of 4080 metric tons per day (mtpd) to provide 15% of the company&apos;s daily requirement in the Thetford Mines area. Figure 1 shows the location of Thetford Mines. Two shafts service the underground. No. 3 shaft, 457 m deep, is used for personnel and material transportation, downcast ventilation, and ore hoisting. No. 4 shaft, 820 m to the south, is 389 m deep. It is used for material transportation and upcast ventilation. Figure 2 shows the relative locations of the shafts and the underground workings. The ore is mined by block caving. HISTORY The orebody outcropped at surface and was first mined as an open pit. Underground mining commenced when open pit mining became impractical. Shrinkage stoping, used initially, was unsatisfactory in the highly fractured ore. Sublevel stoping improved ore recovery and safety, but did not overcome the adverse effects of the un- stable rock. Observations of the rock failures indicated that block caving would be satisfactory. This was confirmed by careful investigation and testing. A method of block caving similar to that used at the Miami Copper Company was adopted. The first block commenced production in June 1933. BLOCK CAVING General A large block of ore is undercut above pre- pared drawpoints. The ore above the undercut caves by its own weight. Caving progresses up- ward as the caved ore is drawn. A large proportion of the rock breaks up in the caving action so that it will pass through the drawpoints. Oversize blocks are broken by drilling and blasting or mudcapping. Figure 3 shows the progressive stages of block caving. In the central part of the ore zone, the vertical dimension of a block is determined by the 132 metres between production levels. When isolated ore pockets are developed, the vertical dimensions of a block depend on the extension of the ore zone above the undercut. The minimum horizontal dimension of an under- cut determines the cavability of the overlying block. When necessary, caving is assisted by drilling long horizontal holes into the block above the undercut and blasting them. This procedure speeds up or restarts caving. It will not ensure complete caving of blocks having undercuts less than 30 m wide. Orebodies suitable for block caving are highly fractured and wide enough to cave freely without excessive dilution. Undercutting must

Jan 1, 1981

By Oren C. Baptist

Umiat field contains the largest accumulation of oil discovered so far in Naval Petroleum Reserve No. 4 in Arctic Alaska. The Umiat anticline was tested with 11 wells; 6 produced oil in varying quantities. Behavior of the wells during testing was unpredictable. For example, one well was abandoned as a dry hole after all tests failed to recover any oil, yet an offset well, only 200 feet from the dry hole, produced 400 barrels of oil a day. The main oil reservoirs are less than 1,000 feet deep and are in the permanently frozen zone (permafrost). Reservoir pressures are low, and most primary production will be by expansion of gas-in-solution in the oil. Because of the unusual reservoir conditions and the difficulties encountered in drilling and completing the wells, the Department of the Navy asked the Federal Bureau of Mines to make laboratory studies of the reservoir sand to determine the cause of well plugging and to provide laboratory information, to be used as an aid in estimating oil recovery from frozen reservoir rocks under solution-gas expansion from low-saturation pressure conditions.

Jan 1, 1960

By David Miller

"The biggest concern about using soil mixing is the inability to observe physically the final product, which has led to a lack of confidence about what is in the ground. After all, you can’t see it and you can’t taste it and you can’t smell it, so are you sure it’s soil mixing? In addition, there are variations in techniques, tools and monitoring that have led to additional skepticism and the desire to “elevate” the product. This skepticism is why the industry is so scrutinized even when there are other technologies being used that do not experience nearly the same level of scrutiny. With other techniques, even with a slurry wall, you can see the backfill before it goes into the ground, and drilled piers have careful evaluation of the concrete mix even before placement into and verification of the open hole. Essentially, you get control over the final material. There is less control in soil mixing, and it’s very dependent on in-situ conditions. These factors make it difficult to rely solely upon installation parameters, quality control (QC) and verification tests. At some point, you may need to apply some engineering judgment.Start at the BeginningThe availability of sufficient and accurate geotechnical data (soil type, heterogeneity, shear strength parameters, variability, etc.) is important in establishing the material that will be drilled. This data will also help in determining the proper mix design to achieve the desired soil cement properties. Many factors must be considered when designing the mix and the mixing program, including any debris in the ground, different soil properties and varying moisture contents.Each of the various factors affect the final properties of the soil cement, so it really takes careful planning and evaluation of the mix design through iterations by looking at the soil types and adjusting the mixes. Clay is going to behave very differently than sand in both mixing efficiency and final properties. That is, the presence of clays results in more difficulty in achieving higher strengths and to physically mix the soil and the binder, whereas the presence of sands results in more difficulty controlling the final permeability."

Jan 1, 2017