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By R. S. Celmer

The distributions of cobalt, molybdenum, copper, and selenium between nickel matte and silica-saturated iron silicate slag have been determined in the region of the metallic saturation boundary, at 1523 K. Results are given as a function of the composition of the coexisting Fe-Ni alloy and the activity of iron in the system. Under strongly reducing conditions, these minor elements display a marked preferential accumulation in the sulphide phase. It is shown that the dissolution of cobalt and molybdenum in slag follows an oxidative mechanism, and distribution equilibria are correlated with the oxygen potential. From these data, the thermodynamic properties of cobalt in nickel matte are computed. Further, comparisons of minor element partitions are made between the nickel and copper matte smelting cases under metal saturation conditions.

Jan 1, 1988

By Liang Zhen, Jian-Tang Jiang, Guo-Ai Li, Xiao-Ya Wang

"Deformation behavior of 2A97 aluminum alloy containing coarse secondary phases was studied using uniaxial hot compression (HC, 340–490°C, 0.4001–1 s-1). The flow stress could be described by a Zener-Hollomon parameter in hyperbolic sine function with the hot deformation activation energy of 237 kJ/mol. Based on the experimental data and dynamic materials model, processing maps were generated to demonstrate the hot workability of the alloy. The coarse secondary phases experienced dissolution by varying degree under different deformation temperature, which producing different effects on the microstructure evolution. When deformed at relatively low temperatures, a mass of fine grains shaped up in the original grains and grain boundaries, and the dominating deformation mechanism was believed to be dynamic recrystallization. As the deformation temperature rising to 490°C, most secondary phases disappeared and few recrystallized grains were observed, indicating that the secondary phases dissolved sufficiently along with dynamic recovery occurred during the hot deformation. Particle stimulated nucleation related to the coarse secondary phases was believed to promote the recrystallization and the recrystallization behavior was sensitive to deformation temperature.INTRODUCTION Al-Li alloys has received much attention as new promising structural materials in the aircraft and aerospace industries, due to their lower density, higher elastic modulus and improved fatigue crack growth resistance in comparison with the conventional commercial aluminum alloys (Ou Ling, 2015). 2A97 alloy is one of the 3rd generation Al-Li alloys targeting at comprehensive improvement of aviation aluminum alloy and applications for wing spars and ribs to other internal structures for transport aircraft. Al-Li alloys are usually formed by hot deformation, either by rolling or extruding. The deformation behavior and resulted microstructure evolution during the forming process mainly dominates the formability of the alloy and the serving performances as well. Therefore, the deformation behavior and microstructure evolution at elevated temperature need be made clear for optimizing the hot processing parameters and controlling microstructure evolution."

Jan 1, 2018

"3.1. IntroductionAmong the six platinum-group elements (POE), four have identical cubic symmetry, two identical hexagonal symmetry (Table 3.1). Despite crystallographic differences, there is a clear relationship expressed in the chemistries of the POE: they tend to be mutually soluble in one another and can frequently substitute for one another in compounds with other elements. This chapter consolidates the data on phase relations of the POE and the compounds they form with elements selected for their known or potentially important mineralogical significance- As, Bi, Cu, Fe, Hg, In, Ni, Pb, S, Sb, Se, Sn and Te-together with selected data for the occurrence of POE in certain elements such as Au and Ag, and compounds such as FeS. Resources used to compile the data are those available from the chemical, mineralogical and metallurgical literature. First each element is discussed, with composition limits of solid solutions drawn from binary phase diagrams. Single element data are followed by a discussion of the relevant binary systems and a tabulation of data for binary compounds found in those systems (Table 3.2). Tables and diagrams for the ternary and quaternary systems for which information is available follow, and finally the very limited information on the solubility of POE in mineralogically important elements and compounds is presented.The chemical, mineralogical and metallurgical literature on the unary and binary systems is extensive and widely scattered in many languages and publications; fortunately, most of the data needed to compile this chapter can be found in reliable compendia. The most useful and most recent of these works is by Moffatt (1979), because it provides a ready index to all material relating to binary systems listed in previous compendia; furthermore, the Moffatt compendium will reportably be kept up to date by annual supplements."

Jan 1, 1979

By Murad Y. Abu-Farsakh

This paper presents the analyses of load-transfer (t-z) behavior of twelve prestressed concrete (PSC) instrumented test piles that were driven in different locations of Louisiana. The load transfer method is an efficient and practical tool for the analysis of single driven pile to predict the ultimate load. The test piles were instrumented with vibrating wire strain gauges in order to calculate the shear transfer for different soil layers during the static load test. The static load test was performed on all the test piles after 10 to 14 days of end of driving. Empirical load-transfer models were proposed previously by different researchers (Fleming 1992, Hirayama 1990, Krasinski 2012, Bohn et al. 2017) after analyzing the instrumented test pile results. For this study, load transfer of each soil layer was measured and compared with the previously developed existing model. The stiffness parameter (M) for the hyperbolic equation was calibrated in order to best match the measurements. The good agreement of the proposed curves was then confirmed by applying them to assess the overall load-settlement curve of other pile load test results available in the literature. INTRODUCTION The load transfer mechanism (stress-strain relationship) for an axially loaded pile usually comprises of three loading mechanisms: axial deformation in the pile (z), soil skin friction along the shaft (qs), and soil end-bearing (qb). The development of soil skin friction with axial deformation is referred as the t-z curve, and the development of soil end-bearing with axial deformation is referred as the q-z curve. Figure 1 presents the load transfer mechanisms in an axially loaded pile and the corresponding spring mass models for t-z and q-z curves (API, 2002). In order to construct the load transfer curve in clay under vertical load, the axial load transfer (t-z) curve and end-bearing load transfer (q-z) for that particular soil should be assessed separately. The axial load transfer (t-z) method is probably the most widely used technique to study the problem of single axially loaded piles. Therefore, the load transfer through the shaft of the pile and are getting more and more important compared to the only the pile capacity analyses. The load transferred from shaft to the surrounding clay soil is a function of the width of the pile and the surface roughness of the pile and clay properties. The development of a representative procedure allows the assessment of the t-z curve in soil (sand and/or clay) that leads to the prediction of a nonlinear vertical load-settlement response at the pile head.

Jan 1, 2018

By Robert F. Chaiken

A quasi-steady-burning channel model is used in this Bureau of Mines study to describe the conductive heat loss from an in situ coal combustor to the surrounding rock strata. The calculated heat losses are significantly greater than those previously estimated, but are still very acceptable from the viewpoint of energy recovery. Approximately 80% to 90% of the heat of combustion of the coal should appear as sensible heat of the gaseous exhaust, with exhaust temperatures in the range of 1,000° to 1,200° C. The effects of burning stoichiometry and channel size on the heat loss are also discussed in terms of the model. Such effects are shown to be compatible with an in situ combustion process even in thin seams. However, these results depend on gas leakage and adverse roof falls not being important factors in deter-mining the heat loss mechanism.

Jan 1, 1977

By Thomas J. Martin, James W. Martin, Paul F. Martin

The conveyor belt is the basic building block of a broad range of material handling applications in modern mining systems. The mining plans and site conditions dictate basic system requirements but this is only a part of total design evaluation. The total system in the typical mining situation can encompass all the activities from the excavators at the mining face to the processing plant, site loadout facilities and/or a power plant. The number of alternative configurations which must be evaluated including subsystems and components is limited only by analytical time and creativity. The constraints and issues which must be addressed continue to expand, driven by reliability, environmental impact and cost competitiveness. All of the system requirements must be translated into specifications for costing, final design and construction.

Jan 1, 1993

By Edward L. Clark

The year 1954 witnessed great activity in the field of geology as applied to mining. The search for in nearly all districts is becoming more and more intensified as established reserves are being depleted. Much geologic work has been directed to finding extensions of known orebodies, but prospecting in new areas has constituted a large part of the program of many operators. The acute need for additional reserves has brought into the search all the tools known to the geologic profession. This is reflected directly by frequent references to geophysical and geochemical methods in the regional reviews that follow. The lone prospector of the early days of metal mining has been eliminated almost completely by modern scientific methods involving surface and subsurface geology, exploratory drilling, geophysics, and geochemistry. Nearly all new exploration is based on long-range programs coupled with studies of regional geology to determine the structural environment of areas of mineralization. The success of this approach has encouraged new operators in the field of exploration to adopt similar policies. Only in the search for uranium ores is the individual prospector still active, but the familiar picture of the burro heavily loaded with grubstake, gold pan, and pick and shovel has been replaced by the Geiger counter and the scintillometer carried by hand, by truck, or by airplane.

Jan 3, 1955

By P G Simpson

The Sundance gold mine, located 2.5 km east of the town of Batchelor in the Northern Territiory, has produced over 5300 oz of gold since it was discovered in 1978. Sundance is unique in the Pine Creek Inlier in that the ore is hosted in palaeo-karst detritus and crystalline magnesite of the Early Proterozoic Coomalie Dolomite. This paper presents a summary of the geology of the mine, and describes the methods used during the two periods of mining.

Jan 1, 1994

Introduction The NIOSH Office of Mining and Construction Safety and Health Research has redesigned its Mining Safety and Health Web topic page. The updated page incorporates a significant amount of new safety and health information, plus an improved layout to better serve stakeholder needs. It also provides back-ground information about the NIOSH Mining Research Program, including research awards, core competencies, unique labs, community and educational outreach, and a brief discussion of how the research program is structured. The new Web topic page can be found at www.cdc.gov/niosh/mining. "Search" Feature The redesigned Web topic page features improved search capabilities. The "Search Mining" feature on each page lets you search only the NIOSH Mining Safety and Health Web topic page. The user can still search the entire NIOSH Web page by using the "Search NIOSH" option. New Safety and Health Topics Developers expanded the "Safety and Health Topics" and reorganized the site to make it easier to find information. Each topic link now has a significant amount of new and updated information, as well as links to related topics of interest. Safety and health topics include dusts, diesel exhaust, hearing loss, contact with electric current, fires, explosives, ventilation, emergency management, new and older workers, and education and training. All topics can be accessed from the home page (Figure 1). Publications Although the Web topic page highlights many of the most requested publications on the safety and health topic links, you can find a complete list of downloadable publications as well. More than 600 mine safety and health publications are now downloadable from the page. Short summaries let the user quickly identify publications of interest. Products The updated Web topic page offers more than 120 NIOSH mine safety and health products, including training exercises, toolbox talks, videos, computer software, guides, and checklists, many of which are downloadable. If not, instructions are given on how to obtain copies. Some of our products include: • Software to analyze horizontal stress, design pillars for longwall mines, and select roof bolts for ground control. • Educational software including the Hearing Loss Simulator, which simulates the effects of noise and aging; and Coal Country, which teaches children about coal formation, mining techniques, and everyday uses of coal. • Utility software including the HazCom Helper software to assist individuals in writing a HazCOM plan, as required by the Mine Safety and Health Administration (MSHA), to track hazardous chemicals at their mine sites. • Guides for troubleshooting roof support systems, under-ground workstation design, and seating design. • Training exercises and videos that can be used for safety training. Data and Statistics General mining statistics are used by a wide variety of stakeholders. The NIOSH Mining Web topic page offers statistical graphs, tables, maps, fact sheets, and other publications that document the mining population, injuries, fatalities, diseases, and occupational exposures for all mining commodities. If users prefer to analyze data themselves, downloadable files of MSHA data are available. These cover employment, production, injuries, fatalities, and accident data from 1983 to the present and are available in both SPSS® and dBASE® formats.

Jan 11, 2005

By STUART R. BRINKLEY, Ruth F. Brinkley

This same phonomonon of diffraction may be transposed into the X-ray domain. All that is necessary is to reduco, in the samo proportion, the wavo length of the light and the diameter of the particlo; thus, with radi- ations whose wave length is of the ordog of angstroms, the dimensions of the active particles go from 10 to 100 A that 18, the dimensions of col- loidal particlos. The evidence of this fact is shown by the following experimental schomo (fig. 1a): A narrow beam of X-rays passes through a thin layer of a modium containing micelles; the photographic film is placed a few centimeters behind the sample, and a small absorbing screen stops the direct beam in order to prevent its fogging the film. The intersect of the direct beam is surrounded by a narrow spot whose blackness decreases with the distance from the center. We will call this the spot of central diffusion (fig. 1b). The phenomenon, in spite of its relatively reat intensity, has been observed only by a few authors, who have simply given a qualitative description without attempting any quantitative de- ductions. This is due to the fact that observation of this phenonenon is not possible with the apparatus generally used to obtain X-ray diagrams, because the parasite foggings in the vicinity of the incident beam are sufficiently important to hide those produced by the sample. With the monochromator, however, used by us to obtain Debye-Sherer diagrams, this parasitic diffusion can be totally suppressed. In this way our attention was again directed to the spot of central diffraction, and we were led to make a detailed quaititative study of it.. then several papers have been published on this subject. Hosemann, using methods of calculation outlined by us, has extended them to the special case of fibrous substances, Kratky, on the other hand, starts from an entirely different theoretical point of view; ho examines the case, not of scattered particles, but of closely packed particles. 6ince We will now describe the experimental methods, summarize the calcu- lations needed in the elaboration of diagrams, and finally review the first results obtained in the vast domain of these new physical-chomical studies.

Dec 1, 1946

By Yuting Xue, Gamal Rashed, Zoheir Khademian, Morgan Sears

Mining has been recognized among the most hazardous industries in the United States, despite the significant reduction in injury and fatality rates over the past century. This study focuses on the ground-fall incidents classified in the Mine Safety and Health Administration (MSHA) database as “fall of roof, back, or brow from in-place” and “fall of face, rib, pillar, side, or highwall.” The main objective of this study is to conduct a comprehensive statistical analysis of the reported ground-fall incidents from 2010 through 2019 including both coal and metal/non-metal mines. Since most of the ground-fall injuries and fatalities occurred in underground coal mines and were attributed to falls of roof and rib, an additional analysis was directed to evaluate roof- and rib-fall incident trends in underground coal mines associated with the mining method, coal-seam thickness, mine size, and the seasonal effects.

By Xuewei Lv, Guibao Qiu, Jiaqing Yin, Chenguang Bai

"The iron ore sinter is one of the main raw materials for the blast furnace (BF) process. In the production of iron ore sinter, the cooling speed of the sinter determines its quality. In addition, the heat recovery devices are installed in the cooling machine for energy saving. The cooling parameters like gas flow rate and the size of sinter should be optimized for getting the gas with a higher temperature and a good quality of sinter simultaneously. In this study, the commercial simulation software COMSOL was used to establish a model for simulating the cooling process of the iron ore sinter. Moreover, three different gas flow rate (1.5, 3, 5m/s) and three different diameter of sintered particles (50, 70, 100mm) were investigated with the model. As a result, in certain porosity, a higher cooling speed was achieved when smaller size or larger gas flow rate was used. And lower gas flow rate was beneficial for the heat recovery. The model could intuitively present the exchange of heat between the sinters and air, as well as the flow and temperature fields during the cooling process.IntroductionIron ore sinter plays a great role in iron and steel industry for many Asian countries such as China, Japan and India. As a part of the sintering procedure, the impact of cooling process on the quality of iron ore sinter couldn't be neglected. On the other hand, the massive iron ore sinters which were at high temperature contain extremely large amount of heat. However, it was reported that there's very few of them recovered in China with an average recovery rate of nearly 10.5% at 2004 [1]. Thus, more reasonable cooling procedure should be developed to get high quality product and heat recovery rate simultaneously."

Jan 1, 2011

For years traditional optical microscopic techniques have been used successfully to carry out mineralogical studies on processing products. Essential information could be obtained by supplementing microscopic data with X-ray powder diffraction data, chemical analyses, etc. However, most of the time the mineralogists working on plant related issues, would supply qualitative information to the metallurgists, due to quantification not being possible in the available time. Since the late-80s, the use of semi-automated to automated techniques for mineral quantification has impacted positively on the use of mineralogy for optimising processing plants. Rustenburg Platinum Mines (now Anglo Platinum) were the first mining company to purchase a Qem*Sem in 1987. With the success achieved in quantifying the minerals in the concentrator streams of the Rustenburg Platinum operations, a second instrument was purchased soon after. These instruments have proven invaluable tools in understanding the flotation behaviour of the sulfide and gangue minerals in the various reefs of the Bushveld. Restrictions in the resolution of these earlier instruments, as well as the time involved in searching for and correctly identifying the fine-grained platinum-group minerals (PGM), meant that these investigations focused on the deportment of the more abundant base metal sulfides, rather than on the actual PGM. The Mineral Liberation Analyser (MLA), which became available in the late 1990s, was well suited to detect and analyse minerals occurring in trace amounts such as the PGM. Anglo Platinum was the first mining company to purchase such an instrument and now has fourteen systems operating at the AR Crown Mines site. One of the applications of these systems involves the study of feeds, concentrates and tailings from the various concentrators on a monthly basis. These routine investigations provide information on a variety of mineralogical parameters, including liberation, association, and grain size. Results are used to emphasise areas for improvement, and specifically underline those areas where improvements will have the most impact on recovery. After new or different technologies have been implemented, mineralogical characterisation of the different process streams is an essential component in the assessment of the impact of these changes on flotation performance. In addition, the knowledge is databased for future reference to draw trends across the various concentrators around the Bushveld complex, and is also used for comparative studies when plants experience high losses to tailings. Due to the success of these investigations the question was posed whether it was possible to obtain data on a daily basis, as compositing samples could hide the impact of daily events. Although the instruments currently used are suitable for a research environment, these are not ideal for mine-site implementation. For that reason Anglo Platinum, together with FEI embarked on a development program to develop a system that can be implemented on-site to measure the important mineralogical characteristics on a daily basis. Important requirements for such a system include time-to-data, ease of use and regular quality control. Highlighting some results from concentrator studies, the presentation will review the progress on the development of automated mineralogical techniques for fast, automated mineral measurements. This is an abstract only. No full paper was prepared for this abstract.

Sep 13, 2010

By Jieliang Wang, Shiwen Yi, Zhao Cao, Peng Zu

Bayan Obo ore contains mainly bastnaesite, monazite and associated iron, fluorite, calcite, dolomite, barite, and trace amount of columbite. Due to its complex mineral compositions and similar mineral properties, it is difficult to separate and obtain rare earth and fluorite concentrates with high purity by conventional magnetic separation and flotation. In this paper, a stepwise magnetic separation process comprised of wet permanent magnetic separation (PMS), wet electromagnetic separation (EMS), and superconducting magnetic separation (SCMS) was proposed to pre-concentrate iron, rare earth, and fluorite minerals from Bayan Obo ore. The results showed that iron, rare earth, and fluorite preconcentrates with high purity and low impurity content could be achieved, which might be helpful to shorten the technological process and improve the separation efficiency for the subsequent flotation of iron, rare earth, and fluorite minerals.

Sep 15, 2020

By Aurel Goodwin

MSHA is the regulatory Agency which administers the Federal Mine Safety and Health Act. Although MSHA's principles largely derive from this Act, they do not exculsively derive from it. One might expect that our principles are contained in the regulations we have published to implement the Act. To a degree, this is true; but the regulations we have now were developed and published before the current Act became effective. For this reason, as well as others, there are some principles that we support which are not evident in our regulations, or in the Act. One of these is the ALARA principle. This principle requires that all unnecessary exposure be avoided; that is, all exposures should be kept "As Low As Reasonably Achievable." Almost all professionals in radiation control can agree with this broad principle; but it would be difficult to get agreement on a regulation which would translate the principle into industry practice. Rather, our regulations specify a limit to exposure for any individual. For radon daughters the current limit is four working level months per year. By having an explicit limit such as this, the ALARA principle often becomes lost and the limit becomes the goal. The principles contained in the Act are equally broad in scope. The principles apply not only for radiation protection, but also for toxic substances and harmful physical agents. The Act states that standards for such substances or agents shall most adequately assure on the basis of the best available evidence that no miner will suffer material impairment of health or functional capacity, even if such miner has regular exposure to the hazards dealt with for the period of his working life. The Act also provides that, although protection of health must be our foremost concern, other considerations shall be the latest scientific data in the field and the feasibility of the standards. Our regulations reflected similar principles when they were developed and promulgated. From experience with other health and safety laws, Congress realized that setting and meeting an exposure limit may not be sufficient to prevent disease. The Act, therefore, contains a detailed description of additional provisions to be included, where appropriate, in mandatory safety and health standards. One of these additional provisions requires that miners be informed about the nature of the hazards associated with their job and about the means for their own protection. Another provision requires the use of labels and other forms of warning to inform miners about the hazards, about proper precautions for safe use or exposure, about relevant symptoms of overexposure, and about emergency treatment. We have partially implemented these provisions through regulation. The Act requires also that standards shall prescribe protective equipment and control of technological procedures and that they shall provide for the monitoring of miners' exposures. We have implemented this provision to a degree also through regulation. Finally, the Act specifies that, where appropriate, a mandatory standard must prescribe the type and frequency of medical examinations in order to most effectively determine whether the health of miners is adversely affected by exposure. Additionally, when a determination is made that a miner may suffer material impairment of health or functional capacity by reason of exposure, that miner must be removed from such exposure and reassigned. In order to encourage miners to take the medical examination, the Act also provides that the miner shall not suffer loss of pay as a result of being reassigned. This additional provision on medical examinations has not been implemented by regulation for radiation hazards, nor for most other toxic substances or hazardous physical agents. We believe that this conference will provide us with valuable information on medical examinations for radiation exposure, as well as on other considerations to be used in future regulations. We still question whether our basic exposure standard of four working level months per year is adequate to protect a miner's health. This conference is indeed timely because both MSHA and NIOSH have been reviewing this issue for some time. I would like to reemphasize MSHA's commitment to education and training. MSHA strongly believes that miners should be informed fully about the real and potential hazards associated with their work. They should know the nature of the hazard and the means for protecting themselves from the hazard. The Act also emphasizes the need for training miners by requiring that new miners receive 40 hours of training before working underground and 24 hours of training before working on the surface. The Act also requires eight hours of refresher training annually. This training must include information on the relevant health hazards and the potential consequences of overexposure. Before I close, I would like to mention briefly another source of principles that MSHA often consults to obtain guidance for both the development and enforcement of regulations. These are the various court decisions that are handed down from time to time. Two in particular that I want to stress are the recent Supreme Court Decisions on benzene and cotton dust. Although neither of the decisions has a direct impact on mining or radiation, they do clarify some general principles and directions for regulatory agencies, such as the role of cost-benefit analysis and the need for risk assessment. In closing, I wish us all an open exchange of information for a productive and useful conference.

Jan 1, 1981

The promotion of good standards of reporting of the valuation of mineral assets in- public documents has been of concern to professional mining industry bodies, the securities industry, and. Government regulatory bodies for some time. This concern led to the National Companies and Securities Commission Release 149 (1990b) which laid down standards for Expert Reports on mining and petroleum securities, and other assets. The formation of the Australian Securities Commission provided an opportunity for a timely revision of Release 149 and the Mineral Valuation Committee was established by The Australasian Institute of Mining and Metallurgy in 1991 to review the existing code, and to develop an appropriate new Code and Guidelines.

Jan 1, 1994

By Phillip N. Yasnowsky

This Bureau of Mines report summarizes State severance taxes imposed on minerals and mineral fuels, provides a hypothetical example of how a State severance tax affects selected components of a firm's income statement, and uses the Bureau's Minerals Availability System (MAS) to estimate the effect of assumed changes in State severance tax rates on copper recovery cost at given levels of potential copper availability. A reduction of the rates to zero or a doubling of them results in changes in costs that are of the same order of magnitude as the cost of transporting copper to the United States from major foreign producing countries.

Jan 1, 1982

By J. Partyka

Respirable dust produced during blasting operations in underground mines exhibits both diffusion and convection properties of the airflow. However, the application of the mathematical model presently used to calculate the change in time in the concentration of blasting pollutants is mostly limited to a single drift and cannot be easily utilized for blasts taking place in stopes. This paper discusses an analytical solution based on considerations that enable us to reliably identify the initial condition. Such an approach may be used for any blasting area regardless of its position, its size, or the ventilation system in use during blasting. In addition, a test procedure using field data is established to determined those parameters not measured directly. As well, equations are derived to find the diffusion coefficient, and the position and size of a dust source from the field data. Mathematical considerations The convection-diffusion problem, for a one-dimensional case, is described by the following partial differential equation (PDE): ct. = Dcxx - Vcx + source - sink(1) where C = the concentration of a pollutant T = time V = the mean air velocity in x-direction D = the diffusion coefficient X = distance away from the pollutant source source = any additional pollutant source specified by an initial value problem sink = decay of a pollutant inside the region specified by the boundary conditions. Respirable dust produced during blasting is best considered as an initial value problem (IVP). To derive a mathematical model, the following assumptions are made: •At time zero (t = 0), the dust source is at point x = 0 of an infinite drift. •The problem is considered a one-dimensional case. •The mean velocity of air and the diffusion coefficient are constant. •There is no source or sink of dust other than specified at point x = 0 and time t = 0. We have to solve the following problem [PDE ct=Dcxx-Vcx-m<x...m;0<t<m(2)] ICc(x,0)=f(x)t=0, the initial condition Where c = dust concentration in mg/m3 V= the average mean velocity in a drift in m/s t= time in s D= the diffusion coefficient in m2 /S x = distance coordinate in m. We observe that in problem (2), we have moved the boundaries to[ -m and +m] in order to have an initial-value problem. We introduce new coordinates, s = t and z =x - Vt. To rewrite the PDE in terms of (z, s), we use the chain rule ct = czzt + csst = -Vcz + cs cx = czzx = cz cxx = (cz)x = czz. We now substitute our computed ct, cx. and cxx into the PDE to get new IVP in terms of z and s :

Jan 1, 1991

By J. O. Lewis

The operation of gas-condensate fields is comparatively new and involves physical principles with which the industry was not prcviously familiar. It has been necessary to devise methods for testing gas-condensate wells and to correlate laboratory and field data. In this paper new methods are advanced for interpreting well G.P.M.† tests whereby dilution by dry gas can be estimated and information supplied on revaporization of condensates by dry gas. Inaccuracies in well test data are discussed. Changes in flow rates can cause changes in the G.P.M. of the effluent and it may take some time for a well to become stabilized after an important change in flow rate. Retrograde tests as usually conducted cannot be directly compared with field G.P.M. data, because the retrograde tests usually include solution gas in the condensates, which are reported On the cumulative basis whereas field data (G.P.M.) usually report pentaneS PlUS on a rate or instantaneous basis. Introduction Though long known to physicists, the phenomena Of retrograde condensation became known to the oil and gas industry Only in recent years, when deeper drilling disclosed that the behavior of vapors under changing pressures was different in high-pressure reservoirs than under the low-pressure operations with which the industry was familiar. These deep, high-pressure reservoirs in which condensation and vaporization behaved inversely to the accustomed manner became known as "gas-distillate," or preferably "gas-condensate" fields. Partly to prevent precipitation and retention of liquids in the reservoir, but still more to prevent the waste of residue gas, the operation known as "recycling," or preferably "cycling," was instituted, in which the residue gas is reinjected into the reservoir, thus maintaining pressure and driving the wet gas to the producing wells. For lack of field experience to serve as a guide, the industry had to assume that theory and laboratory experiments could accurately forecast retrograde behaviors in operating these gas-condensate fields, but it is obvious that these assumptions should be checked at the first opportunities against actual field experience. To make such checks, it is necessary to accumulate a large quantity of reliable field data, but experience has shown that it is difficult to obtain reliable field data and that the laboratory data as usually presented are not in directly comparable form. The problems of correlation involve the complex phase behavior on the one hand, and a knowledge of field data and a visualization of underground conditions on the other hand. This paper is an approach from field experience, The purposes of this article are to discuss the sources of uncertainty in the data and to present methods of analyzing, interpreting and correlating laboratory and field data. Data mostly from lower Gulf Coast fields are presented, from which some conclusions can be derived, but better data from more sources than those available to the writer will be required before satisfactory answers to many questions can be obtained. This paper is presented to stimulate the analysis and publication of data from other fields, the reexamination of field and laboratory methods, and the taking of more complete and reliable field tests. For these purposes, the writer presents some speculations that otherwise would not be appropriate.

Jan 1, 1947

By J. O. Lewis

The operation of gas-condensate fields is comparatively new and involves physical principles with which the industry was not prcviously familiar. It has been necessary to devise methods for testing gas-condensate wells and to correlate laboratory and field data. In this paper new methods are advanced for interpreting well G.P.M.† tests whereby dilution by dry gas can be estimated and information supplied on revaporization of condensates by dry gas. Inaccuracies in well test data are discussed. Changes in flow rates can cause changes in the G.P.M. of the effluent and it may take some time for a well to become stabilized after an important change in flow rate. Retrograde tests as usually conducted cannot be directly compared with field G.P.M. data, because the retrograde tests usually include solution gas in the condensates, which are reported On the cumulative basis whereas field data (G.P.M.) usually report pentaneS PlUS on a rate or instantaneous basis. Introduction Though long known to physicists, the phenomena Of retrograde condensation became known to the oil and gas industry Only in recent years, when deeper drilling disclosed that the behavior of vapors under changing pressures was different in high-pressure reservoirs than under the low-pressure operations with which the industry was familiar. These deep, high-pressure reservoirs in which condensation and vaporization behaved inversely to the accustomed manner became known as "gas-distillate," or preferably "gas-condensate" fields. Partly to prevent precipitation and retention of liquids in the reservoir, but still more to prevent the waste of residue gas, the operation known as "recycling," or preferably "cycling," was instituted, in which the residue gas is reinjected into the reservoir, thus maintaining pressure and driving the wet gas to the producing wells. For lack of field experience to serve as a guide, the industry had to assume that theory and laboratory experiments could accurately forecast retrograde behaviors in operating these gas-condensate fields, but it is obvious that these assumptions should be checked at the first opportunities against actual field experience. To make such checks, it is necessary to accumulate a large quantity of reliable field data, but experience has shown that it is difficult to obtain reliable field data and that the laboratory data as usually presented are not in directly comparable form. The problems of correlation involve the complex phase behavior on the one hand, and a knowledge of field data and a visualization of underground conditions on the other hand. This paper is an approach from field experience, The purposes of this article are to discuss the sources of uncertainty in the data and to present methods of analyzing, interpreting and correlating laboratory and field data. Data mostly from lower Gulf Coast fields are presented, from which some conclusions can be derived, but better data from more sources than those available to the writer will be required before satisfactory answers to many questions can be obtained. This paper is presented to stimulate the analysis and publication of data from other fields, the reexamination of field and laboratory methods, and the taking of more complete and reliable field tests. For these purposes, the writer presents some speculations that otherwise would not be appropriate.

Jan 1, 1947