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By Fred P. Dewey

Although coke is the acknowledged metallurgical fuel, and has been extensively used in this country for more than thirty years, yet the facts on record in regard to its physical properties are exceedingly meagre; and this is also true, but in a less degree, of its chemical composition. An investigation is being carried on in the National Museum which is intended to supply, so far as may be, this deficiency, and through the kindness of Professor Baird, Director of the Museum, I am permitted to present to the Institute a summary of a portion of the results already obtained. So far as I am aware, the credit for the first systematic investigation of the physical properties of coke belongs to Mr. John Fulton, Mining Engineer of Cambria Iron Co. The results of this investigation have been published in Report L, Second Geological Survey, Pennsylvania, 1875, and in a pamphlet setting forth the advantages of the Connellsville coke, the latter published also by the " Virginias"* His results are not altogether free from experimental errors, and the assumption that "the specific gravities of coke and water are very nearly alike "- is scarcely warranted. It has seemed to me, therefore, desirable to make an independent investigation of the physical properties of coke on a plan somewhat different from that adopted by Mr. Fulton. This is the investigation now being carried on at the National Museum.

Jan 1, 1884

By Henry D. Hibbard

The finishing and casting temperature of steel is a subject concerning which there is so much to learn that some temerity is required to write about it. This paper is, therefore, suggestive rather than dogmatic, though the views expressed seem now to the writer to be correct; nevertheless, they may be modified by future developments or discoveries but until then may be of some utility, particularly to beginners in the making of steel. Consideration is limited to the temperatures of simple steels, also called carbon steels, which are those in which carbon is the only element introduced for the purpose of conferring desired physical properties. Alloy steels will receive attention later. Three things largely determine what a batch of steel really will be; via., composition, casting temperature, and rate of teeming. Each has its advocates as being the most important; but they are so interrelated that each must conform to or be right for the other two. When one is claimed to be the most essential to have right, that, probably, was the one that it was found had to be of a certain description, within narrow limits, to suit the already adopted variations of the other two; that is, it was the last of the three to be brought into line. The term "casting temperature" is rather indefinite as there ale several temperatures to which the term may be applied. Most writers who have mentioned casting temperature of steel have alluded to it in relative terms. The few who have given actual temperatures, including Langmuir, Burgess, Styri, and Bash, do not give full information about them. Their results demonstrate the efficiency of pyrometers used rather than aid the steelmaker. In order to understand and use the temperatures, one should know in each case what the steel was, the stage at which the temperature was taken, whether it was usual or not, and whether or not it was right for that steel at that stage. When these

Jan 1, 1925

In order to test the applicability of elastodynamic codes in the modeling of mining related problems, comparisons are made between seismic data and numerical analyses. The dynamic finite difference program WA VE is used for the modeling of a horizontal stope in a deep mine. The slip along a vertical fault situated within the positive excess shear stress lobe of the stope initiates seismic waves. The stope-fault geometry is modeled in both two and three dimensions. The three dimensional non-slip weakening WAVE analyses correlate well with Brune's analytical model. For accurate modeling of the peak particle velocities predicted by McGarr's empirical relationship, it is recommended that a three-dimensional stope -fault model is used, with the amount of slip weakening dependent on the magnitude of the event.

Jan 1, 1995

By Greg Adel, Darren Thornton, Julius Krutschnitt, Toni Kojovic, J. Mark Richardson, Bryan Smith

Mine-to-Mill® optimization is a total systems approach to the reduction of energy and cost in mining and mineral processing operations. Developed at the Julius Krutschnitt Mineral Research Centre in Queensland, Australia, it attempts to minimize energy consumption through the optimization of all steps in the size reduction process. The approach involves sampling and modeling of blasting and processing, followed by computer simulation to optimize the operation and develop alternatives. The most promising alternatives are implemented, and sampling is conducted to quantify energy savings. In the current DOE-sponsored research project, the primary objective is to adapt the Mine-to-Mill® technology to the aggregates industry. The project is being carried out at two quarries operated by Luck Stone of Richmond, Virginia. This paper presents work conducted at the Bealeton quarry.

Jan 1, 2005

By J. U. Messenger

A technique is described whereby the resistance of an emudian to breaking can be quantitatively determined. Produced ailfield emulsions are usually the water-in-oil type and, accordingly, do not conduct an electrical current. However, there is a threshold of A-C voltage pressure above which an emulsion will break and current will flow. The more stable an emulsion, the higher the required voltage. A Fann Emulsion Tester, modified so that low voltages (0 to 10 v) can be accurately measured, is suitable. This technique has application in evaluating the effect of a demuksifier on the stability of an emulsion. Emulsions can, in essence, be titrated with demulsifiers by adding a quuntity of demulsifier, stirring, and measuring the voltage required to cause current to flow. Any synergistic effect of two or more materials added simultaneously can be followed accurately. A demulsifier that significantly lowers the threshold voltage (from 100 to 400 v to 0 to 10 v for the emulsions in this study) is effective and can cause the enlulsion to break. A demulsifier that will bring about this drop in the threshold voltage at low concentration ir very desirable. The technique is also well adapted for rapidly screening demulsifiers. INTRODUCTION Stable emulsions in produced reservoir fluids resulting from certain well stimulation and completion procedures are common problems. The use of suitable demulsifiers can often mitigate these difficulties. At the present time, a rapid and efficient method for selecting satisfactory demulsifiers is not available. It is badly needed. Reliance is now placed primarily on trial-and-error procedures. A new test method has been developed which permits a more rapid and precise selection of demulsifiers. It involves measuring the electrical stability potential of an emulsion before and after a demulsifier has been added. This paper describes this method and shows where it should have application in field emulsion problems. NATURE OF OILFIELD EMULSIONS Two immiscible components must be present for an emuhion to form; we are concerned here with crude oil and water. An emulsifier must be present for tin emulsion to be stable. J Emulsifiers can be substances which are soluble in oil and /or mter and which lower interfacial tension. They can be colloidal solids such as bentonite, carbon, graphite, or asphalt which collect at the interface and are preferentially wet by one of these phases. Unrefined crude oils can contain both types of emulsifiers, A popular theory is that, of the two phases in an emulsion, the dispersed phase will be the one contributing most to the interfacial tension.' Usually this phase contains the least amount of emulsifier. The stability of a water-in-oil emulsion is affected by the fol1owing: l) viscosity; (2) particle or droplet size; (3) interfacial tension between the phases; (4) phase-volume ratios; and (5) the difference in density between the phases. A stable emulsion is usually characterized by high-viscosity, small droplets, low interfacial tensions, small differences in density between its phases, and slow separatian of the phases. It also has low conductivity (high electrical stability potential). Water-in-oil and oil-in-water emulsions"' are both common; however, oil field emulsions are predominantly water-in-oil emulsions. The emulsions which commonly occur during oompletion and stimulation operations contain a combination of several of the following: acids, fracturing fluids (oil, water, acid), and formation water and oil. Produced emulsions usually contain formation water and oil. Emulsions form in oil wells because oil and water are mixed together at a high rate of shear in the presence of a naturally occurring or unavoidably produced emulsifier. During the completion and stimulation of productive zones, and while formation fluids are being produced, oil and water are very often commingled. These mixtures are formed into emulsions by agitation which occurs when the fluids are pumped from the surface into the matrix of the formation or produced through the formation to the surface. Restrictions to flow (such as perforations, pumps, and chokes)".'" increase the level of agitation; tight emulsions are more likely to form under these conditions. Often an emulsified droplet is an emulsion itself.'" Therefore, emulsion-breaking problems can be quite complex. The complexity can be even greater if a third phase (gas) is included. Demulsifiers operate by tending to reverse the form of the emulsion. During this process, droplets of water become bigger, viscosity is lowered, color becomes darker, separation of the phases faster and electrical stability potential approaches zero. Any of these effects could be followed as a means of determining emulsion stability. However, electrical stability potential is the most reproducible and most easily measured parameter for following the stability of a water-in-oil emulsion.

Jan 1, 1966

By Gerald L. Finfinger, Syd S. Peng

Geology is an integral part of roof control, mine design, and production operations. Yet, the importance of geology, coal/rock as an engineering construction material and its properties and behavior within the planned mine areas, in overall mine production operations has not been hilly appreciated. Of all of the engineering disciplines, mining engineers work with the most challenging construction materials. They must deal with rock materials as they exist in their natural states and design mine structures without well-known and defined properties. Further complicating the design process is the variability of the in-situ rock materials with rock types and rock properties varying widely from place-to-place. Predicting properties in advance of mining is difficult and oftentimes impossible. This is why some types of roof-control failures may suddenly occur in some areas when a single roof-control technique is consistently applied to an entire panel, section, or mine. Many roof-control techniques are primarily applicable to the geological conditions that were assumed in the development of those techniques and variations of the rocker rock properties may require modification or significant redesign of the support technology.

By Thomas A. Boyce

Introduction Although innovative coal extraction technology can be approached from many angles, this paper focuses on three: innovation in response to rising costs, to changing mining conditions, and to regulatory issues. Before exploring these three subjects, however, a basic question needs to be raised. Why Innovation? Coal is widely heralded, and quite correctly so, as the United States' "ace in the hole." It has been said that the U.S. is to coal what the Arabs are to oil. The implication is that we have nearly inexhaustible reserves - that coal is cheap, plentiful, and easy to extract. Indeed, because our current productive capacity is estimated to be 15-20% greater than demand, we have been given a false sense of security about the ease of future coal extraction. Therefore, innovative measures are being concentrated on developing technologies for the demand side of coal, including power generation, synthetic fuels, and industrial applications. What is often forgotten is that the unit cost of producing energy from these new technologies depends critically on the cost of the coal feedstock -in some cases the coal consumed accounts for more than one-third the total cost. Thus, while the developers of the end-use technologies struggle to improve the overall thermal efficiency of their process by one or two per¬centage points to make the energy produced competitive in the marketplace, they often are unaware of the risk of a 3 to 6% increase in coal costs wiping out the expensive, hard-earned results of their research. Energy planners are just beginning to realize that coal is not a uniform commodity available at low cost in infinite quantities. Coal is a heterogeneous material whose cost and quality vary widely with local conditions. To produce the massive amounts of projected coal-based energy at reasonable costs, we urgently need devel¬opments in extraction technology, as well as in end-use technology. Thus, coal extraction, coal conversion and utilization, and end -use energy consumption must be viewed as highly interdependent parts of an energy supply network (Fig. 1). And current emphasis on conversion and utilization must be balanced by more emphasis on upstream technologies, including coal extraction. Even more important, the impacts of innovation (or the lack thereof) in any one technology area in the energy supply network need to be discussed and understood by those working in each of the other areas. Why innovation in coal ex¬traction technology? Figuratively, we are all in the "coal boat" together - geologists, miners, transporters, processors, power producers, distributors, and consumers. Innovation is required from each of these sectors to overcome the obstacles that prevent greater use of our most abundant national energy resource. All other links in the coal energy supply network depend on large volumes of coal produced at reasonable costs. Declines in productivity, therefore, must be reversed; the more difficult mining conditions that will be encountered call for new methods and equipment, and regulatory issues must be resolved if the coal ex¬traction link is to be a strength rather than a weakness in the planned U.S. transition to an economy based more on coal and less on imported petroleum. Innovation Tailored to Regional Conditions Once the importance and urgency of innovative coal extraction technology has been grasped, the next step - implementing a research program - becomes quite

Jan 1, 1980

The history of the down draught Dwight- Lloyd system of iron ore sintering in Australia is developed. Characterisation of the broad process is given for one plant, and regional divergences from the reference practice are noted and briefly analysed. The subject of the development of high basicity sinters is introduced, and regional differences in approach and results are Examined.

Jan 1, 1972

By J. A. King, D. A. Knight

"The Porgera orebody is located in mountainous terrain in Enga Province, Papua New Guinea. An underground mine has been developed which produces up to 2000 t/d of ore grading over 2 ozs Au/t. Some 79% of the gold in the ore is free, with the balance in a highly refractory form as sub-microscopic gold evenly disseminated within a pyrite matrix.This paper describes the metallurgical plant that uses flotation and cyanidation circuits to effectively recover the free gold in the ore feed, allowing for wide variation in the gold head grade. The refractory gold component in the ore is stored as leached pyrite flotation concentrate and this concentrate will be later treated by autoclaving techniques to recover the contained gold.The ProiectThe property is located in the Porgera Valley 600 Km North West of Port Moresby. The remote location is 2500 m above sea level. The mine area has 3600 mm of annual rainfall and a temperate climate with temperatures ranging from 10° c to 22° c throughout the year.Alluvial gold was reported in the Porgera area in 1938 and has been an important source of revenue for the area for many years. Intermittent exploration was carried out until the 1960 1 s when Placer (PNG) Pty. Ltd. with Mt. Isa Mines commenced an extensive exploration program. The property was brought to production in 1990 by the Porgera Joint Venture group consisting of Mount Isa Mines Ltd, Rennison Goldfield Consolidated Ltd. and Placer Dome Inc, each with a 30% ownership and the Government of Papua New Guinea with a 10% share. Placer Dome Inc. is the manager of the property with construction under the direction of the Placer Dome Technical Services group."

Jan 1, 1992

By J. A. Herbst

Grinding circuits employed in mineral processing operations are designed to produce feed materials for beneficiation steps such as flotation and magnetic separation, which are sufficiently fine to achieve good liberation of valuable minerals from gangue without over- grinding. In many respects, grinding is the most important unit operation in a mineral processing plant. If adequate liberation is not achieved during grinding, subsequent separation steps will yield low metallurgical recoveries and/or product grades. Grinding energy requirements and operating costs typically exceed 50% of the total expenditures of the entire plant. Because grinding is an inherently energy intensive process and grinding circuit capital and operating costs are high, it is essential that such circuits be run as efficiently as possible. In- creased efficiency in grinding usually translates to a decrease in the energy required to produce a metric ton (short ton) of product size material. It is generally accepted in the mineral industry that efficient grinding circuit performance can not be achieved without the use of some form of automatic control. This is true because all circuits are subject to random disturbances which, if left unchecked, will upset circuit performance and rob a plant of productivity. Such disturbances arise from a variety of sources including natural variations in ore characteristics (particularly hardness changes), uncontrolled water additions, feed-rate upsets, changes in crusher performance, and mechanical upsets such as blockages in pumps and classifiers. Many of these disturbances occur with a frequency which is too high for an operator to detect and react to efficiently. Disturbances which occur on a time scale of several minutes up to several hours can be effectively dealt with using automatic control.

Jan 1, 1979

By A. G. H. Anderson, Eric R. Jette

A few years ago, while the writers worked on the constitution of ternary and quaternary alloys consisting mainly of iron, chromium and siliconl,2 some information on microstructures and hardness, not incorporated in the published work, alas obtained. It has not been possible to do any further work on the properties of the alloys. The information possessed is hereby presented for the interest it may have in connection with the constitution of the alloys. Microstructures Referring to the iron-chromium-silicon diagram,' the regions that received most attention were those in which the sigma phase appears. It was found that the mode of occurrence of this phase varied much with the condition under which it mas formed, and the mode influenced considerably the hardness of the alloys. In some slowly cooled alloys, well within the alpha + sigma-phase boundary, sigma occurs in pabterns suggesting a eutectic. The structure of such an alloy is shorn in Fig. 1, showing it to be partly coarsely laminated and partly globular mottled. In other annealed and slowly cooled alloys, the lanlinated structure is entirely absent, and sigma appears in an irregular distribution of sharply cornered elongated areas (Figs. 2 and 3). These areas all possess a more or less mottled structure. A carbide phase is also visible in these two photomicrographs; it is represented by bright white arras of various shapes, sometimes apparently enveloping the sigma. Quenched and aged specimens, whose compositions arc: located near the phase boundary between alpha and sigma + alpha regions, have structures not unlike martensite (Figs. 5 and 6). Fig. 4 shows the structurc of alloy No. 35 as quenched from 1100" C.; it is a typical solid solu-

Jan 1, 1938

By Eric R. Jette, A. G. H. Anderson

A few years ago, while the writers worked on the constitution of ternary and quaternary alloys consisting mainly of iron, chromium and siliconl,2 some information on microstructures and hardness, not incorporated in the published work, alas obtained. It has not been possible to do any further work on the properties of the alloys. The information possessed is hereby presented for the interest it may have in connection with the constitution of the alloys. Microstructures Referring to the iron-chromium-silicon diagram,' the regions that received most attention were those in which the sigma phase appears. It was found that the mode of occurrence of this phase varied much with the condition under which it mas formed, and the mode influenced considerably the hardness of the alloys. In some slowly cooled alloys, well within the alpha + sigma-phase boundary, sigma occurs in pabterns suggesting a eutectic. The structure of such an alloy is shorn in Fig. 1, showing it to be partly coarsely laminated and partly globular mottled. In other annealed and slowly cooled alloys, the lanlinated structure is entirely absent, and sigma appears in an irregular distribution of sharply cornered elongated areas (Figs. 2 and 3). These areas all possess a more or less mottled structure. A carbide phase is also visible in these two photomicrographs; it is represented by bright white arras of various shapes, sometimes apparently enveloping the sigma. Quenched and aged specimens, whose compositions arc: located near the phase boundary between alpha and sigma + alpha regions, have structures not unlike martensite (Figs. 5 and 6). Fig. 4 shows the structurc of alloy No. 35 as quenched from 1100" C.; it is a typical solid solu-

Jan 1, 1938

DURING the past year the Committee on Coal and Coke has been collecting data concerning various points in the bituminous industry about which a large amount of misinformation circulates through the press and, in some cases, through the coal trade papers. The data presented have been compiled by various members, from the most authentic sources available, and where possible cover the period 1913-1924. They will enable comparisons to be made within the industry, and of this and other industries, and will explain some of the differences between conditions existing now and in the prewar period. CAPACITY AND OVER-DEVELOPMENT The capacity of bituminous mines is frequently stated at figures ranging between 800,000,000 to 1,400,000,000 tons per year. Table 1 shows statistics for the industry, mainly from U. S. Geological Survey sources but partly from U. S. Coal Commission reports. Column 3 gives the mine capacity with equipment and labor as of given date, as estimated from the data published by the U. S. Geological Survey. This is calculated for each State by obtaining the total man days worked as. reported by the operators (multiplying average men employed by total days worked at each mine) and dividing this figure into the total production, getting the production per man day; this figure times number of men employed times 308 (a theoretical full working year) equals estimated- full-time capacity. Two major objections are made to this method-one that the total number of men employed is used, instead of the number actually working, and the other that the number of days used only deducts Sundays and five holidays. The first objection is answered by the fact that the same number of men is used in estimating capacity as is used in actual production, and while this number is always from 12 to 20 per cent. more than are actually working, this condition exists at all times, although it is worse at times of maximum output. Few coal men will agree with the conclusion that the use of 308 days is correct, as it is practically impossible to keep any mine working full time at the same

Jan 2, 1926

By Frank Field, Elsa Olivetti, Randolph Kirchain, Elisa Alonso, Gabrielle Gaustad

"The primary technological challenge to increased use of secondary raw materials is the presence of undesirable elemental species in scrap streams. Recent literature indicates that this may become exacerbated by accumulation of impurities over time. Devising strategies to mitigate this problem depends upon understanding the mechanisms of accumulation. This paper takes a first step at characterizing the extent of this issue by presenting a simple analytical model of recycling rate for materials experiencing exponential growth. Low potential recycling rates limit accumulation due to dilution. Empirical analysis of several major materials indicates that, even for current recovery rates, theoretical recycling rates can reach above 60%, making accumulation issues a possibility.IntroductionIt is well known that recycling of secondary materials can provide significant environmental and economic benefits. Energy savings, in particular, can be quite large when substituting secondary materials for primary. Nevertheless, over the past decade, the recycling rates within the U.S. of many materials appear to not be increasing as rapidly as one would predict or even at all (Figure 1). While many barriers exist to increasing materials recycling, one that is cited consistently by the literature and producers[1-3] is compositional limitations; that is the mismatch between the characteristics of secondary materials and those desired for the finished goods into which they would be transformed..One particular aspect of compositional limitations that is receiving increasing attention is the potential for progressive deterioration of the quality of secondary raw materials streams. For some materials, for example paper or polymers, this phenomenon is inherent and relatively rapid[4, 5]. As such, it is well documented and plays a significant role in recycling decision-making even for prompt or in-house material recycling. Conceptually, this issue can manifest in other secondary materials as well, albeit through a different mechanism.As materials are mixed, used, and reprocessed during recycling, they come into contact with and often pick up other elements. The presence of these, so-called, tramp elements alters the original known composition, possibly requiring additional measurement and processing and may even preclude economic, productive reuse; ultimately, this unintentional pick up is unwanted. A growing number of studies and literature would suggest that accumulation of unwanted elements is an emerging problem, in most recycled material streams. Table I provides a brief literature review of various recycled material streams and the accumulated elements noted as problematic by various authors"

Jan 1, 2008

By Jean Paul Duterque, Morris J. V. Beattie

In many parts of the world, pyrite and arsenopyrite occur together in sulphide ores either as the only sulphide minerals or in conjunction with other valuable sulphides. It is desirable to produce separate concentrates of the various sulphide minerals, including pyrite and arsenopyrite, so that the contained desirable metals can be recovered economically. It is common, for instance, for gold in an ore containing both pyrite and arsenopyrite to be associated almost exclusively with the arsenopyrite. It is desirable in this instance to produce an arsenopyrite concentrate for gold recovery while rejecting the barren pyrite.

Jan 1, 1992

By T. S. West

Completion and production data presented for three wells in the Oakville area of Live Oak County, Texas, which were completed near the gas-oil or water-oil contact, indicate that coning may not be as prevalent a cause of failure in such cases as is commonly assumed. Failure in the cases discussed is indicated to be due instead to: (I) erosion of the formation, (2) flowing out of mud filter cake, or (3) failure of the cement. An open-hole gravel-pack type of completion procedure is proposed for preventing failures of this kind by preventing movement of all solid material in the space in which completion is made. Various combinations of layers of gravel, sand, and cement are utilized for this purpose. Experimental results and theoretical discussion as to the applicability of gravel pack completion are included. Introduction This paper is primarily a study of the reasons for failure of oil-well completions near the gas-oil or oil-water contact, and suggests a procedure for increasing the efficiency of this type of completion. The value of improvement in completion effectiveness near the gas or water zone is not confined, however, to wells of relatively thin oil columns. Thick oil columns become thin as depletion progresses. It would seem to follow that the minimum distance from the gas or water zone at which completion can be made in a new well indicates the limit to which depletion may be carried in a well having an oil column of any initial magnitude. Only four ways can be postulated in which high gas-oil or water-oil ratio can initially occur if the zone exposed for production is within the oil column: 1. Failure of the cementing material. 2. Vertical coning. 3. Failure along the boundary between the cement and the wall of the well. 4. Failure of the formation comprising the wall of the well. Cementing materials such as portland cement and plastics have reached a high stage of development. Failures of this type are probably due almost always to extraneous causes such as mud contamination rather than to faulty cementing material. Vertical coning can and obviously does occur. However, the usual occurrence of thin impermeable streaks in sand sections and the success with which open-hole drill-stem tests can be made near the gas-oil contact suggest that over-all effective vertical permeability, and in turn vertical coning, is less prevalent than frequently is assumed. Much has been written on failure by flowing out of the mud filter cake between cementing material and the formation. A filter cake is always present if, prior to cementing, mud has come in contact with a permeable formation at pressures exceeding the pressure head of the fluid it contains. Mechanical methods are in use for removing filter cake during the cementing operation? which undoubtedly are of

Jan 1, 1947

By T. S. West

Completion and production data presented for three wells in the Oakville area of Live Oak County, Texas, which were completed near the gas-oil or water-oil contact, indicate that coning may not be as prevalent a cause of failure in such cases as is commonly assumed. Failure in the cases discussed is indicated to be due instead to: (I) erosion of the formation, (2) flowing out of mud filter cake, or (3) failure of the cement. An open-hole gravel-pack type of completion procedure is proposed for preventing failures of this kind by preventing movement of all solid material in the space in which completion is made. Various combinations of layers of gravel, sand, and cement are utilized for this purpose. Experimental results and theoretical discussion as to the applicability of gravel pack completion are included. Introduction This paper is primarily a study of the reasons for failure of oil-well completions near the gas-oil or oil-water contact, and suggests a procedure for increasing the efficiency of this type of completion. The value of improvement in completion effectiveness near the gas or water zone is not confined, however, to wells of relatively thin oil columns. Thick oil columns become thin as depletion progresses. It would seem to follow that the minimum distance from the gas or water zone at which completion can be made in a new well indicates the limit to which depletion may be carried in a well having an oil column of any initial magnitude. Only four ways can be postulated in which high gas-oil or water-oil ratio can initially occur if the zone exposed for production is within the oil column: 1. Failure of the cementing material. 2. Vertical coning. 3. Failure along the boundary between the cement and the wall of the well. 4. Failure of the formation comprising the wall of the well. Cementing materials such as portland cement and plastics have reached a high stage of development. Failures of this type are probably due almost always to extraneous causes such as mud contamination rather than to faulty cementing material. Vertical coning can and obviously does occur. However, the usual occurrence of thin impermeable streaks in sand sections and the success with which open-hole drill-stem tests can be made near the gas-oil contact suggest that over-all effective vertical permeability, and in turn vertical coning, is less prevalent than frequently is assumed. Much has been written on failure by flowing out of the mud filter cake between cementing material and the formation. A filter cake is always present if, prior to cementing, mud has come in contact with a permeable formation at pressures exceeding the pressure head of the fluid it contains. Mechanical methods are in use for removing filter cake during the cementing operation? which undoubtedly are of

Jan 1, 1947

By W. B. Gogarty

The reported decreases in water mobility do not seem unusual in view of non-Newtonian fluid properties. Shear stress vs shear rate diagrams have been reported for other solutions of water-soluble polymers. Some of these polymers are similar to the type mentioned by the author. Generally, the shear stress-shear rate is a non-linear function for these solutions. Data for plotting apparent viscosity vs shear rate can be obtained from this function. Apparent viscosity is defined as the ratio of shear stress to shear rate at a given shear rate. When plotted, the apparent viscosity decreases with increasing shear rate. This behavior is typical of a pseudoplastic fluid. For some water-soluble polymer solutions, the apparent viscosity decreases more than 50 times while the shear rate increases 1,000 times. Thus, viscosity of a pseudoplastic fluid only has meaning at a specified shear rate. Results of Fig. 1 could be explained in these terms. Viscosities measured in the Ostwald viscometer represent values at a given shear rate. Some average shear rate is affecting the polymer solutions while flowing through the core. This average value fixes the apparent viscosity as long as the flow rate remains constant. Viscosities measured by the two methods will be equal if shear rates are the same. The results indicate that shear rate in the core is lower (higher apparent viscosity) than in the viscometer. In the paper by Johnson, Bossler and Naumann, the relative permeability is independent of viscosity ratio. Thus, the relative permeability with respect to water flow at residual oil should be independent of the flowing phase viscosity. Polymer solutions will appear as Newtonian fluids The discussion emphasizes the nature of the "resistance factor effect" as discussed in the paper. Repeated anomalies arising in hundreds of experiments led us to the conclusion that non-Newtonian flow is not the only factor. Several of the key anomalies are as follows: 1. Measured viscosities over a range of shear rates from <1 sec-&apos; to 1,000 sec-&apos; do not account for but a minor fraction of the R observed in cores when compared in similar shear-rate ranges. 2. The slope of R vs flow rates in cores is always different from that expected from viscometer shear-rate measurements as shown in Fig. 2. in a core, the level of viscosity being fixed at a given flow rate. With these conditions, the definition of resistance factor R by Eq. 2 is simplified to Since , is constant with rate, R becomes a measure of the apparent viscosity in a core at a given flow rate. Variation in flow rate could easily account for the changes of R shown in Fig. 5. Also, this points to the fallacy of assuming R to be a unique parameter. The constant resistance factors at different flooding velocities appear to be in disagreement with the above discussion. The author furnishes Fig. 2 to support his arguments. As shown, the resistance factors remained substantially constant in the two cores over a considerable range of flooding velocities. However, in the 73-md core, the factor increases at lower rates. This behavior agrees with known characteristics of some pseudoplastic material. These materials act both as Newtonian and as non-Newtonian fluids in different regions of shear rate. Some exhibit first Newtonian, then non-Newtonian, finally, Newtonian character. Others are first non-Newtonian and then Newtonian. This latter type would explain the results with the 73-md core. The Fann-instrument results are not significant since shear rates in the core may be much different than with the viscometer. The higher resistance factor at high rates in the 150-md core is more difficult to explain. The greater resistance at increased flow rates could be attributed to what might be termed temporary bridging. As envisioned, changes in polymer configuration occur at the higher energy associated with the increased flow rate. These changes could cause less effective passage of polymer through the core. Correspondingly, increases in pressure drop will occur. These will be interpreted as higher resistance factors. 3. Most polymer solutions are non-Newtonian and many are more shear-rate sensitive than the polymers in question, yet only a very few polymers demonstrate useful R values. Gogarty&apos;s assumption that viscosities in cores and vis-cometers will be the same if measured at the same shear rate is only valid if non-Newtonian rheology is the only parameter. The experimental evidence does not validate this assumption. The anomalies observed in the equilibrium displacement experiment shown in Fig. 5 are not explained on the basis of varying flow rates since the rates were held constant. M

Jan 1, 1965

By James M. Barker

Sulfur is a nonmetallic element of great physical and economic importance to the world. It is widely but sparingly distributed throughout the hydrosphere, lithosphere, and biosphere. Sulfur is the tenth most abundant element in the universe and eighth most abundant in the sun. In the earth&apos;s crust, which is mainly igneous, it ranks 14th, but is eighth or ninth in sediments (Kaplan, 1972; Stanton, 1972). It apparently is very abundant in the core of the earth, because it is a strong chalcophile, and it is fifth in abundance in stony and iron meteorites (Field, 1972) where it occurs as trolite (FeS). In ancient times sulfur was called brimstone, literally "burning stone." Today the term brimstone is used interchangeably with the term elemental sulfur. Shelton (1979) summarized most of the common definitions of terms, grades, and specifications for the sulfur industry as follows (with minor additions): Sources of Sulfur: Combined sulfur-Sulfur that occurs in nature combined with other elements. Cupriferous pyrites-Pyrite containing relatively minor amounts of copper sulfide minerals. Hydrogen sulfide-A toxic gas (H2S) occurring in natural gas and petroleum. Involuntary sulfur-Sulfur produced primarily as a result of legislative or process mandates. Native sulfur-Sulfur that occurs in nature in the elemental (uncombined) form. Nonferrous metal sulfides-Copper, lead, zinc, nickel, and molybdenum sulfides that are processed for their metal content. Organic sulfurs-Complex organic sulfur compounds occurring in petroleum, coal, oil shale, and tar sands. Pyrites-Iron sulfide minerals that include pyrite, marcasite, and pyrrhotite. Sulfate sulfurs-Sulfur in anhydrite and gypsum. Voluntary sulfur-Sulfur produced in response to market forces. Basic Sulfur Products Produced and Marketed: Acid sludge-Contaminated sulfuric acid usually returned to acid plants for reconstitution. Brimstone-Synonymous with crude sulfur. Bright sulfur-Crude sulfur free of discoloring impurities and bright yellow in color. Broken sulfur-Solid crude sulfur crushed to -8 in. Byproduct sulfuric acid--Sulfuric acid produced as a byproduct of a metallurgical or industrial process, generally relating to combined sulfur sources. Crude sulfur-Commercial nomenclature for elemental sulfur. Dark sulfur-Crude sulfur discolored by minor quantities of hydrocarbons ranging up to 0.3 % carbon content. Elemental sulfur-Processed sulfur in the elemental form produced from native sulfur or combined sulfur sources, generally with a minimum sulfur content of 99.5%. Formed sulfur-Elemental sulfur cast or pressed into particular shapes to enhance handling and to suppress dust generation and moisture retention. Frasch sulfur-Elemental sulfur produced from native sulfur sources by the Frasch mining process. Hydrogen sulfide-Associated with natural gas or petroleum and produced at refineries and coke oven plants; used to make sulfuric acid or recovered sulfur. Liquid sulfur-Synonymous with molten sulfur. Liquid sulfur dioxide-Purified sulfur dioxide compressed to the liquid phase. Molten sulfur-Crude sulfur in the molten phase.

Jan 1, 1983

A. MALINOVSZKY,* Belleville, Ill. (written discussion?).-I have been very much interested in Mr. Dolman&apos;s paper. We all realize, I think, that this question of developing our home industries and support-ing the new industries which have developed during the great war is very important at present. Mr. Dolman has well shown the quantity and quality of the raw magnesite in the United States, and the commercial and industrial possibility of our home magnesite and I believe, with him, that our home industries should receive adequate protection. There are two reasons, however, for believing that this may be difficult. One reason is that much American capital is invested in the Austro-Hungarian magnesite industry. The raw magnesite can be quarried and prepared for the market in Austria with much cheaper labor expense than in the United States; large deposits which are very easy to quarry and good transportation facilities also contribute to the cheapness of production. The second reason is the old saying that the magnesite found in the United States is not of the same quality as the Austro-Hungarian mag-nesite; this I doubt. Even if the magnesite found here does not in a raw state equal the Austro-Hungarian, it can be synthetized so that the finished article will have the same properties as the Austro-Hun-garian finished magnesite refractory possesses. Thaw magnesite from Greece is not the same as the. Austro-Hungarian, but it has linen demon-strated that a good refractory can be made from the Greek product.

Jan 10, 1919