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By T. L. Loucks, E. T. Guerrero

Pressure drop characteristics in a system composed of two adjacent concentric regions of different permeability were studied. The differential equations for continuity of mass flow in the two regions were solved using the Laplace transformation and the necessary boundary conditions to give the pressure distribution in the composite reservoir, the resulting equation for pressure drop at the inner boundary was evaluated for a variety of composite reservoirs and compared with the results for a uniform reservoir. From this study it was found that under certain conditions the permeability in both zones, as well as the size of the inner zone, can be determined from the pressure drop curve. INTRODUCTION The theory for the pressure distribution and pressure build-up behavior of a well producing a single, slightly compressible fluid from infinite and finite homogeneous reservoirs was presented by Hornerl and Miller, Dyes and Hutchinson.2 Extensions on this original work to provide improved and extended interpretations and better agreement between theory and observed results have been made by Matthews, et a1,3 van Everdingen,4 Gladfelter, et al5 Stegemeierand Matthews,6 Hurst and Guerrero,7 and Perrine.8 More recently Lefkovits, et al,9 studied pressure build-up behavior in bounded reservoirs composed of stratified layers. Houpeurtl0 has suggested various approaches to the general problem of variable permeability and porosity but presented no analytic solutions for particular permeability variations. Albert, Jaisson and Marionll studied the finite composite reservoir and presented numerical solutions to the unsteady-state case and an analytical solution valid only for large times. They also studied the so-called pseudo-steady state for several examples of radial permeability variations. Very similar examples have been treated in the unsteady state with application to pressure build-up by Loucks in an unpublished manuscript. More recently Hurst12 has presented the complete point-sink solution (valid for all times) for the infinite composite reservoir. He applied these solutions to interference between oil fields along with an even more elegant application of his explicit solution to the material-balance equation including water influx. Mortada 13 approaches the same application by avoiding the point-source limitation but gives the solution for the aquifer region which is valid only for large times. Hopkinson, Natanson and Temple14 have treated both the finite and infinite composite reservoir obtaining the pressure distribution for the inner zone valid for large times. This paper presents a theoretical study of the pressure distribution in an infinite composite reservoir composed of two adjacent concentric regions of different permeability. The object was to determine the manner in which pressure drop at the inner boundary of a composite reservoir depends upon time, the permeability of each zone and the size of the inner zone. Expressions for the pressure distribution in both zones are developed which take into account the radius of the sink and are valid for small times as well as large times. It was felt that an understanding of the pressure drop behavior in various composite reservoirs would be of assistance in the interpretation of some pressure build-up curves which do not behave according to the theory derived for uniform systems. Often the region surrounding the wellbore is either more permeable or less permeable than the reservoir because of the various drilling and completion practices. The effects of reduced permeability due to drilling-fluid invasion and of increased permeability due to fracturing or acidizing need to be more carefully defined. Therefore, an equation for the pressure drop in a composite reservoir was developed, and the effects of both the permeability in each zone and the size of the inner zone were studied. STATEMENT AND SOLUTION OF PROBLEM BOUNDARY CONDITIONS AND ASSUMPTIONS The physical system studied was a composite

By Gabino Preciado, Louis Sandbak

Corrosion has long been identified as a potential risk to the long-term ground support stability due to degradation of internal ground support elements such as rock bolts but also to surface support from mesh, straps, bolt plates, and ancillary support of utilities such as hangers. The emphasis is to understand the corrosion mechanisms on the primary ground support elements and any supplemental steel or arch sets. The water and chemical processes from oxidation(rust), stress corrosion cracking, and even the electrical charge created during these reactions contribute to the corrosion of the steel support elements. The main goals are to mitigate the effects of corrosion and to be able to predict those areas of high water or high sulphide for potential rehab maps. It is also essential to identify and classify the visible corrosion as part of damage mapping and provide bolt testing to those areas of suspected internal damage from corrosion. This is important to get an estimate of the support longevity or expected life before rehab to minimize the overall cost of the operation.

Feb 1, 2024

By B. A. Hillman

Silicon is the second most abundant element on earth, exceeded only by oxygen. Silicon dioxide forms a crystalline structure of repeating SiO2 molecules which form characteristically hard, durable crystals. As a result, crystalline silica is Ubiquitous in the crustal rocks, sediments and the mineral products derived from mining. An examination of the history of studies that identify silica as a human and animal carcinogen is presented in the context of the development of a public health policy in California. The implications for the cost of conducting aggregate and other mining operations in the state are discussed.

Jan 1, 1992

By T. S. Montgomery

The performance of carbon-magnesia brick in electric arc furnaces (EAF) is interpreted in light of their observed optical microstructures. Features at the bricks' hot faces were protruding periclase grains, metal globules, graphite-metal contacts and linear void patterns. These features were com-pared to similar features previously seen from microstructures of basic oxygen furnace (BOF) refractories. Modes of formation were sought; an attempt was made to interpret their influence related to wear mechanisms.

Jan 1, 1982

By Zhongxue Li, Cuiping Li, Xiaoyun Hu, Yiqing Zhao, Huaying Wang

"Under the auspices of World Federation of Engineering Organizations’ Committee on Engineering and the Environment (WFEO-CEE) and Society for Mining, Metallurgy and Exploration (SME) Task Force on Sustainability and Mining (TFSM), and aimed at helping raise global understanding on and promote capacity building of risk management, this paper presents a framework and prototype of toolbox or knowledge warehouse for facilitating the application of risk analysis, mitigation and management techniques (RAMT) in the mining and minerals sector. The conception, design and implementation of the intended system of knowledge warehouse of risk analysis, mitigation and management techniques (KWoRAMT) are outlined. The system architecture of KWoRAMT is based on a browser/server (B/S) structured platform with web oriented interfaces and composed of data base, knowledge warehouse, searching mechanisms, and risk assessment methodologies. The knowledge sources for KWoRAMT will come from the TFSM expertise and Internet, including laws and regulations, codes of practice, standards, guidelines and best practices. The functions and outcomes of KWoRAMT consist of guided navigations with web links, categorized risk tools, annotated best practices with cases, and integrated risk approaches and solutions based on typical risk methods. Risk categories include those impacting on mine safety, mine occupational health, and mine community environment throughout the whole of mine life cycle from exploration, construction, and exploitation and processing to post-mining closure. Mining associated hazards will be identified and linked by vulnerability onto risk receptors through pathways. Risk management techniques for assessing impacts and consequences of mining induced hazards will be categorized with their pros and cons or strengths and weaknesses. Best practices and significant cases including experiences and lessons with problems, solutions, and recommendations on how solutions would be derived will be illustrated. Integrated risk approaches based upon typical methods will be developed for alternatives and actions."

Jan 1, 2014

The BHP Billiton Cannington mine uses sequential flotation to treat a silver, lead and zinc ore supplied from an underground mine. The final products from the process plant are a silver rich lead concentrate and a zinc concentrate. Operational history of plant performance highlighted that the majority of valuable metal losses to final tailing occurred in the -5 ¦m fraction. Research completed on the flotation characteristics of this size fraction in plant feed resulted in the development of a split flotation process to improve the silver and lead mineral recoveries. Construction of a $A 9.5 million brownfield project to install the new split flotation circuit at Cannington was completed in July 2002. The circuit consists of three stages of cyclone classification to recover the ultra fine material to a final cyclone overflow stream, conditioning of this pulp to achieve optimal process conditions, and conventional rougher and three stage cleaner flotation to produce a silver rich lead concentrate. The rougher tail from the new circuit is recombined with the cyclone underflow streams and processed through the original lead-zinc flotation circuit. This paper discusses the circuit design, material properties, material selection for components of the circuit, operational practices and requirements to ensure the circuit succeeded in meeting production targets. The technology is subject of a number of patent applications including international application No PCT/AU02/00400.

Jan 1, 2003

By M. W. Wadsley

"Physical and chemical property models are widely used in process engineering. There exist, in the published literature, completely empirical models of ''thermodynamic properties"", that is, property models that are not consistent with the laws of thermodynamics. There also exist property models that purport to be thermodynamically consistent but are flawed in their implementation. There are also published property models that are consistent with the laws of thermodynamics but that do not reproduce property values with an acceptable accuracy. A practicing engineer might be asked to assess very different property models for which there are a variety of claims. This paper discusses features of thermodynamic and empirical property models that may assist in their practical evaluation and implementation."

Jan 1, 2005

By Maria I. De Rosa

The U.S. Bureau of Mines conducted a study to determine if correlations exist between the chlorine or nitrogen contents of materials and the hydrogen chloride (HCI) or hydrogen cyanide (HCN) concentrations evolved during the thermal decomposition of these materials. Hydrogen chloride, hydrogen cyanide, and carbon monoxide (CO) were found to be the primary toxic gases evolved during the combustion process. The experiments were carried out in a 20-L furnace with 1-g samples. The furnace temperature, rising from ambient, was set at 1,000 °C with an airflow of 10 L/min. The variables measured were the gas loads (milligrams per gram) of HCI, HCN, CO, and CO2 (carbon dioxide); CO and CO2 concentrations as a function of time were also measured. Other variables included the average concentrations of submicrometer smoke particles and particles' average diameter, mass of particulates, sample and furnace temperatures, and sample weight loss. The data indicate that there are significant correlations between the percentage of chlorine or nitrogen contained in the original samples and the HC1 or HCN concentrations evolved during the combustion of the materials. These correlations may be used to predict and evaluate a material's toxic hazard during combustion.

Jan 1, 2010

By D. J. Hawk

The mechanical properties of coal are often represented by the orthotropicmaterial model, which consists of nine elastic constants. The material symmetries involved are found in coal primarily because of the natural process by which it was formed. In this thesis the material properties of five U.S. coals, as obtained from cubical testing, are examined, using as a basis for comparison the assumption of the orthotropic material model. An analysis is performed on each set of coal material data in order to examine its conformability to other, less complex material models, these being the transversely isotropic model consisting of five elastic constants and the 'isotropic model consisting of two elastic constants. In addition, the material properties of two American shales are analyzed, based on the assumption that they comply with the transversely isotropic model. An analysis similar to that performed on the coal material is applied to the shale in order to determine the conformity of its material properties to the isotropic model.

Jan 1, 1980

By John P. Gooch

The solubility of 1,1,2,2-tetrabromoethane (TBE) in water was determined from 1.0° to 97.0° C. The solubility (S) of TBE in grams of solute per 100 grams water was correlated with [S = 1,920.55 [exp (40292L7 11, T2 10 T 737.577 + 9.923962 ] where T is in degrees Kelvin. A thermodynamic analysis conducted on a system consisting of a TBE phase and a water phase in equilibrium with a vapor phase led to the calculation of the activity coefficient, vapor-liquid equilibrium distribution coefficient, relative volatility, and heat of mixing for saturated solutions of TBE in water. Data required for these calculations were the solubility of TBE in water and the vapor pressures of TBE and water as a function of temperature.

Jan 1, 1972

By LUIS ALBERTO TORRES-CRUZ

The Plewes method is relatively well known among geotechnical engineers interested in assessing the liquefaction potential of soil deposits. Furthermore, it was one of the four methods considered in the post-failure investigation report of the Feijao Dam I, also known as the Brumadinho Dam, in Brazil. The inclusion of the method in that report is likely to increase its visibility among geotechnical practitioners tasked with assessing the liquefaction potential of tailings. While the authors of the method duly presented it as a screening method, more recent technical literature contains conflicting views on its reliability. Considering the popularity of the method and that the safety record of tailings dams is a cause of great concern, this study assessed the uncertainty of results from the Plewes method. The study concludes that, even under optimistic assumptions, the results of the method are too uncertain for detailed characterization of tailings deposits.

Pyrite is one of the principal Au-bearing minerals in refractory gold ores. Significantly high Au concentrations of up to 5200 ppm are present in pyrite. Pyrite hosting high levels of Au is also enriched in As. Pyrite as an unwanted mineral ends up in wastes and constitutes one of the primary sources of As in the mining and metallurgical wastes. Arsenic can be readily released to the environment due to rapid oxidative dissolution of the host pyrite under atmospheric conditions. In order to determine the form and occurrence of arsenic in pyrite, micro-X-ray absorption fine-structure spectroscopy (XAFS) spectra were collected from a range of arsenical pyrite grains having different morphologies and a range of arsenic and gold concentrations. All the pyrite grains are characterised by the dominant edge aligned with As-1 valence state. In pyrite, arsenic atoms substitute for S atoms that are in six-fold coordination about each Fe atom. XAFS data suggest that As atoms occur in clusters within the pyrite structure. In addition to As-1, fine-grained, inclusion-rich and framboidal-type pyrite grains have a second As species at ~11 875 eV corresponding to As5+. This As5+ species in pyrite is highly variable and attributed to the oxidation of arsenic exposed on the surfaces of pyrite.

Jan 1, 2008

By H. C. Carpenter

This literature study of methods for desulfurizing residual fuel oil was conducted by the Bureau of Mines at the request of the Department of Health, Education, and Welfare. The sulfur compounds in residual fuels are believed to consist chiefly of condensed thiophenes and other polycyclic sulfur compounds. Hydrodesulfurization appears to be the most promising method for desulfurizing these oils and is the only method applicable to all types of sulfur compounds. There are indications in the literature that hydrodesulfurization without hydrocracking of residual oils may require higher pressures than used in present desulfurization processes, but no cost data and little experimental data are available on the higher pressure operation. Literature proposals for hydrogenating residual oils and heavy crude oils are exclusively for hydrocracking the oils to lower boiling products with accompanying partial desulfurization of the residual fuel fraction. Costs of the hydrocracking operations appear the closest available to probable costs of hydrodesulfurizing the oils, and have been reported (in 1955 to 1957) as $500 to $840 investment cost per daily barrel of capacity, with total operating costs of 70 cents to $1.10 per barrel.

Jan 1, 1963

By H. C. Carpenter

This literature study of methods for desulfurizing residual fuel oil was conducted by the Bureau of Mines at the request of the Department of Health, Education, and Welfare. The sulfur compounds in residual fuels are believed to consist chiefly of condensed thiophenes and other polycyclic sulfur compounds. Hydrodesulfurization appears to be the most promising method for desulfurizing these oils and is the only method applicable to all types of sulfur compounds. There are indications in the literature that hydrodesulfurization without hydrocracking of residual oils may require higher pressures than used in present desulfurization processes, but no cost data and little experimental data are available on the higher pressure operation. Literature proposals for hydrogenating residual oils and heavy crude oils are exclusively for hydrocracking the oils to lower boiling products with accompanying partial desulfurization of the residual fuel fraction. Costs of the hydrocracking operations appear the closest available to probable costs of hydrodesulfurizing the oils, and have been reported (in 1955 to 1957) as $500 to $840 investment cost per daily barrel of capacity, with total operating costs of 70 cents to $1.10 per barrel.

Jan 1, 1963

By William J. Miles

The inhalation of dust has been a problem in the mining industry since antiquity. Crystalline silica is now known to be the cause of silicosis, a form of pneumoconiosis that is associated with excessive exposure to respirable particles in some mining and industrial environments. Crystalline silica was reviewed by the International Agency for Research on Cancer (IARC) in 1986 and classified as a Group 2A, Probably Carcinogenic to Humans in Volume 42 and Supplement 7 of the IARC Monographs (1987). In 1996, IARC reviewed additional literature and studies published in the intervening decade and recommended that quartz and cristobalite, two polymorphs of crystalline silica, be listed as Group 1, Carcinogenic to Humans. Their recommendations and reclassification were published in 1997 in IARC Monographs 68.[2] In both Monographs, IARC classified amorphous silicas as Group 3, Inadequate Evidence for Carcinogenicity to Humans.

Jan 1, 1998

By Donald W. Gentry

This section deals with one of the most fascinating aspects of mining the evaluation of mine investment opportunities. Be-fore proceeding further, it is important to clarify the meaning of some fundamental terms used frequently in the text. 6.0.1.1 Mine Valuation vs. Evaluation The words "valuation" and "evaluation" in a mining context are often used interchangeably. However, for the purposes of this section, a distinction is made between the two terms in accordance with commonly accepted practice. The word valuation in a mining project context has the rather narrow meaning of placing a dollar or other currency value on the worth of the project as a whole. In other words, the value of a mining project refers to a measure of the desirability of ownership of that property. As such, the major item of interest is, "what is the mine worth?," or `what is the value of the mine?" The value of a mining project may actually be determined in the marketplace at any specific point in time, or it may be estimated by one of several methods. The topic of mine valuation is discussed in more detail in Chapter 6.1. The word evaluation in a mining project context connotes the broader meaning of determining the numerical values of all

Jan 1, 2008

ARTHUR PHILLIPS, Chairman C. S. SMITH, Past-Chairman L. W. KEMPF. Vice-Chairman. E. E. SCHUMACHER, Vice-Chairman H. A. MALONEY, Treasurer FRANK T. SISCO, Secretary °9 West 39th Street, New York 1S, N. Y. Executive Committee 1945 1946 S. BARRETT H. L. BURGHOFF T. A. WRIGHT GERALD EDMUNDS L. L. W MAN A. A. SMITH, JR.

Jan 1, 1944

By John C. Edwards

Standard smoldering and flaming combustion tests using smaIl coal samples have been developed by the U.S. Bureau of Mines as a method to evaluate the response of a smoke detector. The tests are con-ducted using a standard smoke box designed and constructed according to Underwriters Laboratories. The tests provide a standard, easily reproducible smoke characteristic for smoldering and flaming coal combustion, based upon a comparison of the smoke optical density and the response of a standard ionization chamber to the smoke. With these standard tests, the range of threshold limits for the response of a smoke detector and the detector's reliability can be evaluated for nearly identical smoke visibility and smoke physical characteristics. The detector's threshold response limits and reliability need to be well defined prior to the instrument's use as part of a mine fire warning system for improved mine safety.

Jan 1, 2010

By John Freer

As an innovation on the annual programme, the Excursions Sub-Committee organized a social get together of the Institute's Councillors and their families on Sunday, 27th February, 1983. Asian Mining - change of date The Second Asian Mining Conference, previously announced as being held in Manila, The Philippines, from 5th to 8th November, 1984, will now be held in Manila from 11th to 14th February, 1985.

Jan 1, 1983

By O. Jantti, Erkki Laurila, R. T. Hukki

INVESTIGATION of the methods of analyses for magnetite and ilmenite in the Otanmaki iron-titanium ore and respective mill products has resulted in certain improvements in the methods conventionally employed. The outcome of the investigations is summarized as follows: 1—Development of a diamond-drill core analyser for the determination of magnetic susceptibility of drill cores containing magnetic minerals. 2—Development of a magnetite-ilmenite analyser for pulverized products. 3—Development of a potentiometric method of chemical analysis for the determination of iron, vanadium, and titanium in succeeding steps from one test sample. 4—Proposal for a continuous and automatic magnetite assay method. Diamond-Drill Core Analyser The conventional method of assaying diamond-drill cores consists of splitting the cores, pulverizing them and running chemical analyses on representative samples. The physical properties of magnetic minerals, however, offer an entirely different approach to obtain similar final result by the measurement of respective magnetic susceptibilities in a properly designed instrument. This instrument is shown in Fig. 1. Essentially it consists of a magnetic unit, A, and of a meter unit, B. On top of A is a slot where a piece of diamond-drill core C is visible. The magnitude of disturbance in the original magnetic field caused by the magnetic minerals in the drill core can be observed from the microammeter. This reading is a function of the combined susceptibilities of all magnetic grains in the magnetic field. The magnetic unit is built of E-sheets of a shell transformer, as shown in Fig. 2. The primary coil and two identical secondary coils are wound around the central leg and end legs, respectively. The drill core under examination is placed into one of the air gaps as shown in Fig. 2. The number of ampere-turns of primary coil excited by 50 or 60-cycle ac give a maximum induction of about 600 gauss in the air gaps. The secondary coils are connected in series in the opposite direction. Thus their voltages compensate each other if no drill core exists in the air gap or if the susceptibility of the drill core is equal to zero. As soon as the susceptibility becomes greater than zero, the balance of the magnetic circuit is disturbed, resulting in increased voltage in the terminals of coil 1 and in a respective decrease of voltage in the terminals of coil 2. The voltage difference thus produced is a function of the effective susceptibility of the drill core. If the magnetic grains in the drill core are unevenly distributed, the voltage difference varies as the core is rotated around its own axis. The voltage difference is measured with a Bren-tan0 tube voltmeter. If extreme sensitiveness is desired, the established symmetry of the magnetic circuit does not allow reduction of the 0-voltage difference far enough. Therefore a compensatory voltage of a correct phase taken from the terminals

Jan 1, 1952