Search Documents

By J. H. East, D. Harrington

"INTRODUCTION Burning refuse dumps are a common and by no means pleasant sight in most coal-mining distracts; they have been and largely continue to be accepted as a necessary, if undesirable, adjunct to coal-mining operations. The odor, smoke, and fumes emanating from the burning dumps have caused much property damage, as well as aroused unfavorable public sentiment in the areas thus affected; and there is reason to believe that, in at least some cases, they have had an adverse effect on the health of certain communities, adjacent to mines. In some instances such communities have been owned or controlled by the mining companies and in others they are incorporated towns.After the start of World War II, it was necessary for Great Britain to take prompt and effective measures to extinguish or at least blanket the burning refuse dumps at collieries, since the fires served as beacons for the enemy planes; the problem thus became a matter of national security rather than one of local inconvenience. If the United States should become involved in a bombing war, these dumps might became a source of national danger, hence now is a propitious time to at least make a start on available methods of solving this problem. Much progress was made in Great Britain in extinguishing the dump fires that had burned for years and in preventing newly made dumps from taking fire.Burning refuse dumps have not been a national problem in the United States, but they are a nuisance and frequently a danger and often a fruitful cause of poor public relations on account of the odor and fumes. Many progressive coal-mining companies are taking effective and positive action in trying to extinguish old dump fires and to build new dumps so they are less likely to fire.The purpose of this paper is to provide information about the problem as well as on ways to extinguish refuse dump fires, to describe methods of constructing dumps that probably will prevent them from firing, and to point out some of the danger that exists when dumps are improperly built and when they are on fire."

Mar 1, 1948

By Simon C. Dominy, Alwyn E. Annels, Paul Wheeler, Suzanne P. Barr, G. Simon Camm

Abstract-Narrow veins are an important world-wide source of silver, tin, uranium and particularly gold. To potential financiers, this style of mineralization is viewed as high risk because of the often relatively small resource involved and high cost of estimation. In many cases diamond core drilling will not enable resource estimation beyond the inferred and indicated categories. Exploratory underground development is required to define measured resources. The definition of geological and grade continuity are major factors in narrow vein assessment. A measured resource must be based on strong geological and grade continuities. Narrow veins, generally less than 3 m wide, are complex geological phenomena, which commonly display unpredictable geometry and grade distribution. Variations in structural continuity, dip, strike, width, mineralogy and specific gravity are common. Veins may be composite, with ore-grade mineralization restricted to a specific structural domain. Branches, intersections and braided zones are common features. Potentially high-grade zones are often localized within ore shoots, which are surrounded by barren/low-grade regions. Resources must be determined as closely as possible to reality and reflect the distribution of the commodity in the rock. Estimation has three main requirements: (1) geological study to determine orebody nature; (2) estimation of tonnage and grade, and (3) the presentation of this information using a classification that is clear, unambiguous and bankable. Estimation methods employed are either classical or geostatistical; however, classical methods are often used because of the difficulties in applying geostatistics. Grades generally show a strong positively skewed distribution testifying the presence of high-grade values. Problems exist in the applicability of cutting outlier values risking over- or underestimation of grade. It is generally believed that where resource estimates are in error, poor geological control is usually the cause. Overestimation can lead to the closure of a mine through lost revenue and capital. An understated estimate can result in an opportunity missed for profit and/or greater economies of scale. Definition of reserves involves the consideration of economic and engineering data, to decide which part of the resource is economically mineable. Geology plays a similarly important role at this stage in the assessment of likely mining method, dilution, recovery etc. Throughout resource/reserve estimation, it is crucial that the amount and quality of the data and the geologist’s experience are relevant. The impact of geological understanding on estimation is often undervalued or assumed to be of lesser importance than finding grades and tonnages. This paper discusses the geology of narrow vein deposits and the importance of geology in their evaluation.

Jan 1, 1997

By J. S. Kennedy, M. M. Fine

"INTRODUCTION Barite is one of the major industrial minerals whose production has increased considerably in the last 10 years. In 1935 domestic production of barite was 218,075 tons and. had increased by 1944 to 515,136 tons. 3/ Most of the primary uses for barite and barite products were developed before 1935, so the increase in barite production reflects the growth of industry in general rather than any recent developments in barite technology.The principal uses for ground and crushed barrite are as a weighting agent in heavy drilling fluids, as a filler in rubber and other materials, as a pigment and extender in paints, and as a flux in glass melt. In addition, a considerable' quantity of barite serves as the raw material for the manufacture of lithopone and barium chemicals.Specifications for barrite vary widely and depend primarily on the use to which the material is put. The primary requisites for barite used in heavy drilling muds -are that it have a minimum specific gravity of 4.2 and be very,low in soluble salts. A minimun barium sulfate content of 92 percent may be specified; but this is less important than the gravity. 4/ In addition before consumption the material must be ground to '92 percent minus 325-mesh. 5/ Lithopone and chemical manufacturers require a minimum of 94 Percent barium sulfate, a maximum of 1.0 percent iron oxide, and not more than a trace of fluorine. 6/ Barite used as fillers in light-colored products should be of fairly high grade, but the filler used in dark products may be considerably lower grade.Glass barite should contain a minimum of 96 percent barium sulfate, not more than 3 percent moisture, a maxium of 0.2 to 0.4 percent iron oxide, and not more than a trace of titanium oxide. Particle size is a matter of some importance in glass barite, also. 7/"

May 1, 1948

By F. D. Stevenson

Thermodynamic properties of metal halides and, in particular, vapor pressures have become of great importance in recent years owing to increased application of chemical processing to extraction of metals from their ores. Vapor pressure data serve not only as a valuable source of latent heat of vaporization and fusion values but also differences in metal-halide vapor pressures often provide the basis for their separation by conventional mass transfer operations. This literature search was made to provide a ready reference to experimental vapor-pressure data of metal halides and oxyhalides. Results are reported in two main sections: (1) A tabulation of vapor- pressure references for each of the metal halides (listed by metal) for which actual experimental data are reported (table 1), and (2) a bibliography of the citations. Metal halides and oxyhalides are listed by chemical formula and chemical name, based on the stock4 system. To facilitate location of the references, a listing of the journal titles and their abbreviations follows the bibliography.

Jan 1, 1963

By H. L. Retcofsky

Carbon-13 nuclear magnetic resonance (18CNMR) spectra of nine 2-substituted pyridines, seven 3 -substituted pyridines, and nine 4-substituted pyridines have been obtained and analyzed. Substituents included both electron-releasing groups and electron-with hawing groups. Substituent effects on the magnetic shieldings of the ring carbons, except for those in the 2-positions of 2-substituted pyridines, were found to be quite similar to the effects reported for the monosubstituted benzenes, Thus, at least to a first approximation, the two classes of compounds have similar shielding mechanisms. Shieldings of the carbon atoms in the 5-positions of 2-substituted pyridines and those in the 6-positions of 3-substituted pyridines were found to reflect electron release or withdrawal by substituent groups, The pyridinium cation and the compounds 2,2'-dipyridyl and benzonitrile were also investigated.

Jan 1, 1969

By T. Lane Carter

(Canal Zone Meeting , October , 1910.) INTRODUCTION. IT is a curious fact that while in our Transactions there are papers dealing with mining-districts in all parts of the world, in Europe, Asia, Africa, and Australia, there is not one which describes the mining possibilities of Nicaragua; our near neighbor. To be most interested in distant objects, like the moon, .and to neglect what lies at our feet, appears to be a trait of human nature. The neglect of Nicaragua is not confined to the American Institute of Mining Engineers. In no other transactions am I :able to find papers dealing with mining in Nicaragua, some parts of which are as much in need of discovery and research as the North Pole.. I hope this paper will be the precursor of many others to be printed in our Transactions, dealing not only with the mining possibilities of Nicaragua, but with the whole of Central America, where there are vast areas awaiting skill and capital for their development. Much of this capital and skill should come from the United States in the future, although it is probable that European capitalists, when they appreciate fully the possibilities, will investigate more and more the mining-resources of Nicaragua and other Central American republics. Fig. 1 is a sketch-map of Nicaragua showing the principal mining-districts. II. HISTORY. Mining in Nicaragua did not begin yesterday. It was commenced by civilized man when the Spanish conquerors penetrated into the interior and forced the natives to procure the precious metal for them. It is strange that the Spaniards did not find more gold, and work on a scale as extensive as in Colombia and other parts of South America. Probably in Nicaragua the Indians covered up most of the rich prospects

Dec 1, 1910

By Walter L. Fisher

The public interest in the Alaskan situation is such that, with the consent of the President, I have concluded, at the request of the American Mining Congress, to make at this time a candid, if somewhat informal, expression of the views I have formed as Secretary of the Interior, under whose official supervision much of the administration of the Territory is now placed. Pressure of other matters imperatively requiring attention has prevented their presentation in as precise and comprehensive a form as I had hoped. The absence of the President from Washington has also prevented the submission to him of what I have prepared. I wish to say, however, that no one is more earnest than he in the desire to see a policy of prompt and wise development inaugurated in Alaska, and that the general policy contained in this address has been discussed with him, meets his approval, and will have his support. I have recently returned from an altogether too brief but nevertheless a most interesting and profitable visit to those portions of Alaska that are more immediately involved in the questions now under public consideration. Favored by extraordinary weather and the cooperation of steamship and railroad lines and the assistance of all of the governmental agencies, including the Revenue-Cutter Service, I visited every port in Alaska that seems likely in the near future to become an important entrance to the country. I examined all of the harbor and town sites which for this purpose have attracted any considerable public attention. I traversed the entire length of each of the three railroads that have been constructed in the Terri.tory and made a short trip from White Horse down the upper Yukon. Both before and during the journey I examined a mass of books, records,' and papers relating to the country and its resources. I had conferences with official committees representing the principal communities I visited and with numerous individuals, residents both of the coast and of the interi.or, and conferred with engineers, miners, prospectors, railroad officials, business and professional men.

Jan 1, 1911

The words ""Uncertainty"" and ""Risk"" pervade every discussion about mining exploration and investment. Perhaps these terms are subjectively understood by industry professionals, but objective portrayal of these concepts outside the industry is a woefully undeveloped science. This paper addresses current industry understanding and practice regarding quantitative risk assessment techniques, and provides examples of the application of three of these techniques. Probabilistic techniques for financial risk assessment are valuable adjuncts to conventional financial analysis, and address a range of issues not assessable by any other means. The value of whole-of-project probabilistic risk assessment is currently debatable for decision-making purposes, but is seen as important as a mechanism to focus attention to the critical issues that ultimately impact on project success. The dissection of project capital into risk and non-risk components provides valuable insights into risk characteristics not readily quantifiable in any other way. This technique also provides a framework for more objective ""what if?"" scenario evaluation and for the capital structure of resource projects. Finally, mechanisms for the valuation of undeveloped reserves are examined, and guidelines suggested. The importance of reliability in production cost estimates is highlighted and the impact of early development on reserve valuations is discussed. The importance of economics throughout all stages of the evaluation process is fundamental.

Jan 1, 1994

By Michael Sokaski, M. R. Geer, H. F. Yancey

This report is one of a series describing investigations by the Federal Bureau of Mines of the performance of various types of coal - cleaning equipment ; other reports in the series are listed in the bibliography . The information in these reports is useful to the coal industry and the manufacturers of coal - cleaning equipment in several ways : First , it assists the coalpreparation engineer who is planning a new plant to select the type of process best suited to the requirements by enabling him to forecast the yield and quality of clean coal obtainable with each type of equipment . Second , the information serves as a yardstick by which the performance of a plant can be judged and thus helps determine whether it is operating at satisfactory efficiency . Both these functions promote better coal - preparation practice ; that is , they help provide coal of more suitable quality for the market and likewise minimize the waste of good coal . This serves the interest of conservation with which the Bureau is vitally concerned . The present report deals with three plants using the Tromp dense - medium process , named after its inventor , K. F. Tromp , who developed the process in the Netherlands in 1936.5/ Selection of this particular dense -medium process for investigation was entirely a matter of convenience , and reports dealing with other dense -medium systems are planned for the future . Two baths are employed in one of the plants investigated . The first of these , handling 6- to 3 - inch coal , exhibited an exceptionally sharp separation between coal and impurity . This was characterized by an error area of 12 and a probable error of 0.023 . In the second bath , treating refuse from the

Jul 1, 1960

By Lewis A. Smith

This circular presents a summary of the domestic chromium industry, and discusses the salient features of the world situation , reflecting the literature of the subject . The United States Bureau of Mines has in its files additional detailed information on many subjects briefly discussed in this paper and desires to assist the industries and the public by giving further data in response to individual inquiries . It will welcome comment and criticism and any contributions that would assist in making future editions of this circular more accurate . Unlike most common metals , chromium is rarely marketed as a pure metal . The chromium industry deals mainly with chromite , the principal ore of chromium , and with ferrochromium , the basic alloy in which chromium enters the metallurgical industry.

Apr 1, 1932

By Ken Goering

"Bridgestone Americas opened the company’s first U.S.-based giant off-road radial (ORR) tire plant in November. The 139,000-m2 (1.5 -million-sq ft) plant, located on a 222-ha (550- acre) site in Aiken County, SC, will produce radial tire products, including 157-cm (63-in.) tires, used on mining and aggregate haul trucks.The plant, announced in 2011 as a $970-million investment, represents the largest investment that Bridgestone has made in the United States, and is also the single largest investment ever made in South Carolina. Although it had already been producing tires for a few months, the plant officially opened with a ceremony in November 2014, attended by South Carolina federal, state and local elected officials, as well as Bridgestone personnel from the United States and Japan. Prior to the Aiken County plant’s construction, all of Bridgestone’s giant ORR tires were manufactured at its Shimonoseki and Kitakyushu facilities in Japan.Kurt Danielson, president of Bridgestone’s U.S. & Canada Commercial Group, said the facility was built to primarily serve the North American mining and aggregate industries in a more efficient manner. "It’s a real change for us," he said of the U.S.-based plant at its opening ceremony. "This allows us to have a true global presence."The Aiken County plant is intended to allow Bridgestone to meet customer demand for ORR tires, Danielson said. "It really frees up our other plants in Japan to service the rest of the world, allowing us to serve our customers faster," Danielson said. "As soon as we build (a tire), we can have it to our customers."Tires manufactured at Bridgestone’s Japanese plants could spend up to a month in transit to the American continents; from initial mixing of the rubber and other compounds to being warehoused, tires manufactured at the Aiken County plant can be ready to ship in four to five days.Danielson said most of the tires built in Aiken County will be used by customers on the American continents. "We will export," he said, "but our desire is to use as much capacity as we can for the Americas."Ground was broken for the facility inSeptember 2011, when commodity prices were much different than today and global demand for tires had skyrocketed."

Jan 1, 2014

By R. C. Gould, A. M. Skov, L. F. Elkins

Comparison of long term decline in oil production during cyclic waterflooding or pressure pulsing of part of the Driver Unit with steady injection-imbibition flooding in the Tex Harvey area led to large expansion of flood in the Driver Unit on the steady injection basis. While the flood has been successful, the major problem has been attainment of satisfactory oil production rates in most of the wells. Large volume fracture treatments of low capacity wells were unsuccessful in achieving sustained increases in production. A two-section area in the Driver Unit has already recovered 620 bbl of oil per acre by waterflood but other areas have not performed so well. Sun Andres water containing 300 to 500 ppm H,S is sweetened to 0.5 to 1 ppm H,S by extraction with oxygen-free flue gas. This prevents contamination of gas produced in the area and apparently it has reduced corrosion in minimum investment, thin-wall, cement-lined water dktribution systems. Cement-lined tubing in injection wells has mitigated corrosion as effectively as thick polyvinyl chloride films have, and at less cost. Introduction As reported in the literature the Spraberry field of West Texas has presented unusual problems for both primary production and waterflood ing. Earlier information from the Spraberry Driver Unit included conception and evaluation of cyclic waterflooding or pressure pulsing in a nine-section pilot test as an aid to extraction of oil from the tight matrix rock and as a boost to normal capillary imbibition forces An additional 5 years' operation in that area, and performance of expanded steady injection water-flood, now covering a total of 68 sq miles, are reported herein. In addition, since the Driver Unit is one of the largest waterfloods in areal extent in the U. S., many operating experiences are presented for the benefit of engineers concerned with operation of other Spraberry floods or with other waterfloods where this reservoir technology and/or water handling technology may be adaptable in part. These include: (1) attempts to improve producing well capacity through large volume fracture treatments, (2) long-term performance of water treating plants utilizing oxygen-free flue gas to extract H,S from sour San Andres water, (3) performance of thin-wall cement-lined pipe in water distribution systems including comparison between those sections carrying raw San Andres water and those carrying treated water, and (4) comparison of performance of various lining materials and subsurface equipment in water supply and water injection wells. These experiences are reported without regard to whether results are good, bad or indifferent. Since the operations reported are limited to the techniques, materials, and equipment actually used in the Driver Unit, no comparison is possible with results of other approaches used in other Spraberry floods or in waterfloods generally under different conditions. However, an attempt is made to quantify these experiences as much as possible in the space available to permit other engineers to select those parts applicable to eheir problems. Background The Spraberry, discovered in Feb., 1949, is a 1,000-ft section of sandstones, shales and limestones with two main oil productive members—a 10- to 15-ft sand near the top and a 10- to 15-ft sand near the base, having permeabilities of 1 md or less and porosities of 8 to 15 percent. Extensive interconnected vertical fractures permitted recovery of oil on 160-acre spacing from this fractional-millidarcy sandstone, but they made capillary end effects dominant. Primary recovery by solution gas drive is less than 10 percent of oil in place, with most wells declining to oil production of a few barrels per day when reservoir pressures are still in the range of 400 to 1,000 psi. Partial closing of the fractures with declining reservoir pressure is believed to be the cause of such low production rates at these relatively high reservoir pressures. In 1952 Brownscombe and Dyes proposed that displacement of oil by capillary imbibition of water from the fractures into the matrix rock might significantly increase oil recovery from the Spraberry, overcoming otherwise serious channelling of water through the fractures." A pilot test conducted by the Atlantic Refining Co. during 1952 through 1955 indicated technical feasibility of the process; but low oil production rates averaging I5 to 20 bbl/well/D failed to create significant interest in large-scale waterflooding at that time." Humble Oil & Refining Co. conducted a highly successful 80-acre pilot test during 1955 through 1958 with

Jan 1, 1969

By Eugene S. Meieran

The effects of methods of crystal growing, wafer sawing, polishing, routine handling, diffusion, and epitaxial growth on the defects in GaAs are reviewed and studied using reflection and transmission X-ray topographic techniques. In general, it was found that boat-grown crystals exhibited fewer defects than Czochralski crystals, although all crystals showed large numbers of precipitates visible when examined in the electron microscope. Mechanical surface treatments such as sawing and mechanical polishing introduce damage to a depth of about 5 µ, most of which can be removed by suitable chemical or chem-mechanical polishing. In addition, defects can be introduced through routine handling of wafers, for example with metallic tweezers. These defects can be quite severe, and have been observed 20 µ below the wafer surface. Defects can also be introduced through diffusion and epitaxial growth. These defects, which include precipitates, growth pyramids, stacking faults, dislocations, and so forth, can be detrimental to device fabrication. It is shown that wafers or films which appear defect-free optically can contain defects visible in the X-ray topographs. WHILE the use of GaAs in the semiconductor industry has increased very rapidly in the last few years, due mainly to the recent development of many important GaAs devices,1,2 the major limit to the production of commercial quantities of many GaAs devices remains a severe lack of suitable materials technology. This lack is apparent in two critical areas. First, production quantities of high-quality GaAs crystals, reproducibly doped and precipitate-free, simply are not available commercially, although some reasonable quality material is available on a limited first-come, first-serve basis. Second, in comparison to silicon technology, little is known about the effects of processing variables on the defects either present in as-grown GaAs or introduced through processing and handling of wafers. These areas are now receiving some attention from semiconductor device manufacturers, who are studying defects in GaAs in order to better understand how either to prevent their occurrence or to cope with their existence. Most investigations of the defects in GaAs have been made by optical microscopy3-5 or transmission electron microscopy techniques.'-' Recently, however, the imaging techniques of X-ray topography, electron mi-croprobe analysis, and scanning electron microscopy are being applied to the study of GaAs.9-14 In the case of X-ray topography, a one-to-one image is obtained that must be photographically enlarged. In compensa- tion, the defects within entire wafers may be imaged by simple scanning (Lang technique15) if the wafer is reasonably perfect, or by using the scan oscillation technique developed by Schwuttke16 if the wafer is warped or distorted. The purpose of this paper is to both review and extend the general application of X-ray topographic techniques to GaAs. Emphasis will be placed on the effects of growth and process variables on the quality and perfection of both bulk and epitaxial GaAs. Reference to optical or electron microscopy results will be made when useful. Since the effects on defects of a wide variety of processing variables such as crystal growing, sawing, polishing, diffusion, and epitaxial growth will be somewhat superficially reviewed, a fairly extensive bibliography of the most important recent results in these areas is included. However, for completeness, important defects will be illustrated here, although such defects have been previously shown by others. While this paper is concerned with defects rather than with the physics of X-ray scattering, the mechanisms of contrast formation in the topographs will of necessity be briefly mentioned. EXPERIMENTAL GaAs crystals, both boat-grown18 and Czochralski-grown,'8 containing a variety of dopants of various concentrations, were purchased from outside vendors. Wafers were sliced from the crystals using a Hamco ID saw and were mechanically polished using 1 µ diamond paste. Chem-mechanical polishing was done in bromine-methanol as described by Sullivan and Kolb.18 Chemical polishing was done using a modified sulfuric-peroxide solution, 11 parts H2SO4, 1 part 30 pct H2O2, 1 part DI water.5 Zinc diffusion was carried out in a closed tube, using a 10 pct Zn-In source at 825°C for 1 hr. Oxide masking techniques were used to select the area to be diffused. Epitaxial wafers were either purchased or prepared here. All epitaxial runs prepared here were carried out using a Ga-GaAs-AsC13 source in a closed tube at a substrate temperature of 750°C. Wafers were chem-mechanically polished and gas-etched prior to deposition. The X-ray topographs were taken on a Krystallos Lang camera, operating in the transmission scanning geometry (Lang technique15) or in the reflection scanning geometry (modified Berg-Barrett technique20,21). MoKa, radiation was used for all transmission topographs using a Jarrell-Ash 100-µ spot focus. CuKal radiation was used for all reflection topographs using a General Electric CA-7 1-mm spot focus X- ray tube. Topographs were printed from an intermediate contrast inversion film, so the contrast shown in all figures here is the same as that of the original 50-µ-thick emulsion L4 Iiford nuclear plate used to record the topograph.

Jan 1, 1969

By A. J. Conelius, D. P. Sobocinski

This paper presents a correlation for predicting the behavior of a water cone as it builds from the static water-oil contact to breakthrough conditions. The correlation is partly empirical and involves dimensionless groups of reservoir and fluid properties and of production and well characteristics. The groups were deduced from the scaling criteria for the immiscible displacement of oil by water. The correlation is based on a limited amount of experimenfal data from a laboratory sand-packed model and on results from a computer program for a two-dimensional, incompressible system. Because the correlating groups are dimensionless, they can be used to estimate the performance of water coning cases not specifically considered in the correlation. However, despite its dimensionless nature, the correlation is not completely general and will not provide meaningful estimates of cone behavior in many situations. INTRODUCTION AND BACKGROUND The production of water from oil wells is a common occurrence which increases the cost of producing operations and may reduce the efficiency of the depletion mechanism and the recovery of reserves. We will deal with one cause of this water production, namely, coning. The coning of water into a producing well is caused by pressure gradients established around the wellbore by the production of fluids from the well. These pressure gradients can raise the water-oil contact near the well where gradients are most severe. Gravity forces that arise from fluid density differences counterbalance the flowing pressure gradients and tend to keep the water out of the oil zone. Therefore, at any given time, there is a balance between gravitational and viscous forces at points on and away from the completion interval. When the dynamic forces at the wellbore exceed gravitational forces, a cone of water will ultimately break into the well to produce water along with the oil. We can expand on this basic visualization of coning by introducing the concepts of stable cone, unstable cone and critical production rate. For instance, if a well is produced at a constant rate and the pressure gradients in the drainage system have become constant, a steady-state condition is reached. If, at this condition, the dynamic forces at the well are less than the gravity forces, then the water or gas cone that has formed will not extend to the well. Moreover, the cone will neither advance nor recede, thus establishing what is known as a stable cone. Conversely, if the pressure in the system is in an unsteady-state condition, then an unstable cone will continue to advance until steady-state conditions prevail. If the flowing pressure drop at the well is suffcient to overcome the gravity forces, the unstable cone will grow and ultimately break into the well. It is important to note that in a realistic sense, stable cones may only be "pseudostable" because the drainage system and pressure distribution generally change. For example, with reservoir depletion, the water-oil contact may advance toward the completion interval, thereby increasing chances for coning. As another example, reduced productivity due to well damage requires a corresponding increase in the flowing pressure drop LO maintain a given production rate. This increase in pressure drop may force an otherwise stable cone into a well. The critical production rate, well known in the literature, is the rate above which the flowing pressure gradient at the well causes water (or gas) to cone into the well. It is, therefore, the maximum rate of oil production without concurrent production of the displacing phase by coning. At the critical rate, a built-up cone is stable but is at a position of incipient breakthrough. Numerous papers have been published on critical rates. Some of the better known of these include the work of (1) Muskat and Wyckoff,' who first dealt with the coning problem; (2) Chaney, et al,' who developed expressions similar to those of Muskat but who presented results in a conven ient-to-use graphical form (the "Sun" method); and (3) Meyer and Garder,b hose analysis is based on radial-flow formulas. One assumption in critical production rate analyses is that the cone has built-up to just before its breakthrough into the well. But, these analyses reveal nothing directly about the time it takes for the cone to build up to this incipient breakthrough position. Thus, water-free oil can be produced from a well for prolonged periods at rates above the critical rate before the well reaches the condition to which the critical rate applies. The published literature contains little on the rate of growth of a cone. Experimentally, Meyer and Searcy studied the rate of rise of a cone in a Hele-Shaw model.' Additional related work on water breakthrough and produced water-oil ratios in water driven reservoirs was reported by Muskat," Hutchinson and Kemp," Henley, et al,' and Stevens, et a1.B Theoretically, the basic coning equations for a water-oil system can be developed by applying the conservation of mass to each of the phases, relating flow velocities with pressure by Darcy's law, and relating pressures across water-oil interfaces by capillary pressure. With the usual boundaries at the well and reservoir limits, the solution of the resulting equations for the time behavior of a water-oil interface constitutes a free-surface, boundary-value problem. The shape of the boundary depends on the internal potential distribution, while this

Jan 1, 1966

By K. A. Slagle, D. K. Smith

weight obtained. Additives used in conjunction with salt in these slurries have included silica flour, calcium ligno-sulfonate and cellulose retarders, granular lost-circulation materials, bentonite and selected low-water-loss additives that are not significantly deteriorated by the presence of the chloride ion. In some other areas of South Texas, the salt-saturated slurries have been used quite extensively for improvement of the flow properties of slurries and attainment of better circulation characteristics at lower displacement rates. Concurrently with this property, the protection of shales and shaly sands is also realized, as well as useful retardation of the slurry. Resultant superior cementing jobs have been indicated by both communication tests and acoustic logs for bonding to pipe and formation.' In one section of Louisiana, a major oil company has been using salt-saturated API Class A cement with calcium lignosulfonate retarder for cementing through the Miocene at 9,000 to 10,000 ft. This is another of the situations where interbedding of sands and shales exists, creating difficulty in maintaining formation competency when a fresh-water slurry contacts the clay minerals of the formation. Further work has also been done in the shaly Miocene formation at 13,000 to 15,000 ft where fairly close water or gas contacts are encountered. Indications thus far are that better segregation of these various fluids is obtained by use of the saturated salt slurries because of their improved formation bonding characteristics. In addition to the properties of salt in this situation, attainment of turbulent flow at minimum displacement rates has also been accomplished by use of an additive to help provide exceptional dispersion and viscosity reduction of the slurry. Another oil company was encountering considerable expense in completing wells in Southwestern Louisiana due to extensive block squeeze requirements for effective separation of zones. A very effective mud program was being used to minimize washout in the shale sections and, apparently, a nearly gauge-size hole was being obtained. However, primary cementing results with fresh-water slurries were generally poor. On a few occasions when slurry was actually circulated to the surface, large pieces of shale formation were brought out of the hole with the slurry, indicating a severely water-sensitive, sloughing formation. Inhibition of shale heaving was being accomvlished in the drilling program, and immediately indone ipon circulation of the fresh-water slurry even though it contained a low-fluid-loss additive to reduce filtrate damage in the sands. The subsequent change to salt-saturated slurry yielded 11 successful primary cement jobs out of 12, compared to the previous success ratio of practically zero. Since these were deep, high-temperature wells in the range of 13,000 ft with high-pressure zones necessitating 17.5-lb/gal fluid densities, the slurry used was API Class E cement, silica flour, weight material, retarder, salt saturation (which also reduced the amount of weight material) and maintenance of low fluid loss by use of a salt-compatible additive. Other salt slurries have been used to a limited extent in this same general area for similar problems at depths ranging from 5,000 to 17,000 ft. In the shallower wells, the cement has usually been API Class A where the salt functions as a retarder, and in the deeper wells API Class E cement is used with the additional salt advantage being its increased slurry weight and inability to dissolve salt stringers. A considerable number of squeeze jobs have also been done on older wells using the salt-saturated slurries with very good results. MID-CONTINENT In North Texas, salt-water slurries have been used for cementing the Woodbine sand, Strawn sand, KMA sand and Pettit lime. Shales surrounding these formations have created the same difficulty in obtaining separation of producing zones that has been the problem in other areas. Depths in this area range from 3,400 ft for the Strawn to 7,400 ft for the Woodbine, and concentration of salt has varied accordingly. In the deeper wells, where retardation is desired, saturated salt-water cement is used; for the shallower wells, in order to provide shorter waiting-on-cement times, the amount of salt has been 18 per cent by weight of the mixing water. Results have been excellent with no reported failures on any of the salt cement jobs; where acoustic bond logs have indicated indifferent bonds previously, they are indicating very good bonding for the salt slurries. In Oklahoma various shales of Pennsylvanian age exhibit a high degree of sloughing in the presence of fresh water, causing severe washouts above and below sand formations which it is desired to isolate. This situation exists to some degree in practically all parts of Oklahoma and includes formations of other ages such as the Wood-ford shale. For the past few years, salt-saturated cements and displacement rates as high as practical have been used as a remedy for this problem, with very good results. The Layton and Bartlesville formations are two examples of shaly sands where saturated slurries have been helpful. In one area where five wells were drilled through this type of problem shale without obtaining a satisfactory primary cement job, a change was made to salt-saturated cement preceded by a suitable chemical wash for the drilling mud involved. Acoustic bond logging indicated excellent bonding, and final completion bore out this result by being trouble-free. This type of slurry has also been used extensively on squeeze jobs where shales have been heaving around the producing formations. Predominantly, the basic slurry has been either API Class A cement or a pozzolan cement—although, as deeper wells are being drilled, the use of salt in Class E cement is also increasing. Salt cement in West Texas has been used primarily to help prevent channeling through the shales around the Delaware sand, Queens dolomite and Hope lime. Many of the shaly and dirty sands of this area are sensitive to the filtrate from a fresh-water cement. Salt at 16 to 18 per cent by weight of mixing water has been added to centent, and has been effective in controlling formation damage and communication between zones in these formations. Use of these lower salt concentrations is dictated in this area by the relatively low formation temperatures where retardation of the slurry would create unduly long waiting-on-cement times. Also, quite a bit of cementing has been done in this area using salt concentrations in the accelerating range— that is, 2 to 5 per cent by weight of water. Specifically, these concentrations have been used in coiljunction with high percentages of gel to overcome the retarding effect of the calcium lignosulfonate dispersant, although there are probably several shales where these concentrations could provide some degree of formation stability. On several occasions, the salt has also been used to lower the critical velocity or rate for turbulence with the slurry, particularly in the pozzolan cements. On wells in the Hope lime, it has usually been necessary to squeeze the shale above and below the lime to get a water-free completion. Use of salt-saturated slurries has largely eliminated this

By P. J. Deveaux, M. J. Kreczmer

The Tartan Lake deposit 12 km northeast of Flin Flon, Manitoba, was discovered in March of 1984 during the investigation of a VLF anomaly. The discovery hole intersected 16.83 metres averaging 21 gm Au/tonne. Since then, 99 holes, over 21,000 metres, have been drilled outlining 419,491 tonnes grading 11.79 gm Au/tonne in a di stinct group of mineralized lenses referred to as the Main Zone. Three other mineralized zones are known on the property but no reserves have been allowed for these, the South , East and Base Line zones. The Main Zone consists of seven parallel, east-west striking, quartz lenses. The lenses dip steeply to the north and plunge steeply west to northwest. Lens number l strikes for 160m and extends vertically to the 90m level. Within th is lens there is a 60m interval of low grade materi al. Lens number 2 is located about 5-l0m within the foo twall of Lens number I. Near surface this lens stri kes for 40m, at 200m level the strike length increases to 200 m. To date the deepest mineralization on Lens 2 has been intersected at a vert ical depth of 527m. Five smaller lenses are located in the foo twall of Lens 2 , containing gold va lues similar to the two main lenses but erratically distributed. The South Zone, located 100m south of the Main Zone, strikes east-west fo r l00m above the 100m level. The East Zone, found 230m east of the Main Zone, strikes fo r 80m and may possibly be an ex tension of the South Zone. The Base Line Zone is located 275m south of the Main Zone. Sporadic, but very significant gold intersections have been obta ined1n all three zones. Gold-bearing quartz-ca rbonate tourmaline veins are generally confined to a silicous crystal tu ff hori zon. The crystal tuff exhi bits fi ve distinct types of alteration: silicification, sericitization, ca rbonati zation, chlorit ization and pyritization. Silicification has resulted in a perasive addition of silica and the generation of multiple quartz veins. Sericiti zation is restricted to the crystal tuff. All rock units are pervasively carbonatized . Ankerite is abundant in the quartz veins and within the shear zones, particul arly those located along the chilled margin of a nearby gabbro-diorite intrusion. Chloritization is widely spread th roughout the rock units, while pyritization fo rms a broad alteration halo associated with the orebody. Sulphide accesso ry minerals associated with the gold , whi ch fo r the most part appears to be free, are chalcopyrite and pyrite. Generally, the higher grade gold values are related to an increased content of sulphides in the qua rtz veins. The average sulphide content in the deposit is less than 5 %.

Jan 1, 1986

By E. H. Henderson

MR. R. V. NEILY stated that he had at one time operated at Goldenville. The practice and results are much the same now as in the olden days. Inside plates were then found to be a source of trouble and had been removed. At the Libbey mine, Queen's county, the sulphides carried considerable gold, and $45.00 to $60.00 per ton had been recovered from the concentrates by roasting and chlorinating. Later, concentrates were treated with bromocyanide. Following that practice, a cyanide leaching plant was installed, which did not require concentration of the tailings. Cyanidation brought a recovery of around 95 per cent, with but $300 worth of plant. In Nova Scotia, the ore of each locality presents an individual problem of its own as to treatment required. Ma. W. B. Timm stated that, in the majority of Nova Scotia gold ores, more than 75 per cent of the gold content is free-milling and, naturally, stamps are most efficient for collecting and amalgamating this gold. In Ontario and the West, they had got away from stamps, and perhaps the main reason was that the supply of battery-men, who came from Nova Scotia, had died off. Ball-mills had been installed, which required smaller space and handled large tonnage, even though, as far as amalgamation goes, the stamps were probably more efficient. If concentration is to be done, ore from stamps is usually in better shape for recovery in passing over the tables, as there is no slime. With the ball-mill, flotation is necessary. The better practice, undoubtedly, is to take out what gold is possible before it is all smashed up, as in the ball-mill, though recent developments in the ball-mill make it possible to trap and take coarse gold directly from the mill. In this way, cyanidation is speeded-up, due to saving of the time the coarse gold would take before going into solution. PROFESSOR A. E. FLYNN found it unusual in these days to read anything in favour of the stamp mill, and thanked Mr. Henderson for the excellent paper in which he upholds the stamps and backs his opinion with facts from actual operations. For the typical Nova Scotia ore, containing coarse gold, stamps are un¬excelled. It used to be said that the virtue of stamps is that they brighten the gold for amalgamation. Although this saying is almost classical, it is not true, for gold is never brighter than in the native, untouched state. Any hammering that gold gets makes it more difficult to amalgamate.

Jan 1, 1935

By W. A. Hutchins

Water laws important to the mining industry are those which govern or affect the right to use water, to dispose of water after using it in mining or milling, and to discharge waste material into watercourses. They include statutes and court decisions having general applicability, as well as others that pertain specifically to mining. THE INDUSTRY'S CONTRIBUTION TO WESTERN WATER LAW Despite sharp differences of opinion, the water law the Spaniards brought to the Southwest appears to have included some form of appropriation of water. The Mormons, who settled in Utah in the mid-nineteenth century, also developed a system of appro-priative water titles. But by far the most profound impact on western water law was made by the gold-seekers who flocked to the Sierra Nevada foothills of California after the discovery of gold in 1848. Much of the gold was extracted from the ground by hydraulic or placer mining, and so the miners' rights to the use of water became fundamentally important. Since there was no organized government in the foothills and no laws other than those made by the miners, they helped themselves to the land, the gold, and the water needed to work their claims.1 They established and enforced regulations governing the acquirement and holding of mining claims and their rights to the water they needed.' In 1879 Justice Field, former Chief Justice of the California Supreme Court, spoke for the U. S. Supreme Court in saying that the miners were "emphatically the law-makers, as respects mining, upon the public lands in the State."" Rules of the California mining camps were based on two essential principles: 1) priority in discovering claims and appropriating water by diverting it from streams and putting it to use, and 2) diligence in working claims and applying water in mining. The customs so developed, which were copied in mining areas of other states and territories, were enacted into law in one western jurisdiction after another. They form the basis of what is called the arid-region doctrine of prior appropriation of water, which received the attention of Congress in legislation recognizing and protecting appropriations of water for mining, agriculture, and other purposes on the public domain.' In several western states a great number of water cases decided in the early years involved relative rights to the use of water for mining purposes or for milling connected with mining." The miner's inch, the customary unit for measuring water in the mining camps, is still used in various western communities, although its relation to the cubic foot per second varies from one area to another. Undoubtedly, the miners of a century ago made the major contribution to the appropriation doctrine as it is now recognized and applied throughout the West. What inspired the California gold-seekers to develop these principles? Thoughtful writers have pointed out that their regulations and customs were strikingly characteristic of much earlier mining enterprises in the Old World.D It is said that the right of free mining and free use of flowing water therefor —so similar to the California conditions and practices—-was a part of the customs of Germanic miners in the Middle Ages, that it spread from middle Europe to other countries and colonies, and that the doctrine of prior appropriation was widespread in the important mining regions of the world. Certainly the Forty-niners came to California from many countries. It does not tax the imagination to consider that they may have brought with them some knowledge of the old Germanic customs and applied this knowledge in their new environment. RIGHTS TO USE OF WATER IN GENERAL In the West, rights to the use of water of watercourses fall into two categories—appropriative and riparian. The doctrine of prior appropriation is recognized in each of the 17 western states. The riparian doctrine is recognized concurrently with the appropriation doctrine in some of these states but has been abrogated in the others. The riparian doctrine prevails generally throughout the East, although there is now considerable interest in developing something else. Generally speaking, the appropriation doctrine has been highly developed in the West, whereas the principles of riparian doctrine have been comprehensively established in only a few states throughout the country. The subject of water rights is a big one. Space permits no more than a brief discussion of aspects that bear upon the title of this article. RIGHTS OF PRIOR APPROPRIATION Fundamental to the doctrine of prior appropriation is the principle first in time, first in right. Although in some states there are statutory exceptions. the original and still generally prevailing rule is that the first one who initiates a right to divert and use water of a stream, and who completes his undertaking with reasonable diligence, acquires thereby the first right of appropriation of the specific quantity of water involved. Each succeeding right in point of time is junior to all earlier rights but senior to all later ones. The practical effect of this priority system is that when the water supply is not enough for all, the earliest rights must be fully satisfied before any water may be taken by those later in time. Acquirement of Appropriative Rights: Each of the 17 western states has a statute under which water may be appropriated pursuant to a prescribed procedure. Generally, the first step to be taken by the intending appropriator is to file application in the office of the State Engineer for a permit to make the appropriation. In most but not a11 states, valid ap-

Jan 1, 1961

By L. W. Saperstein, Y. J. Wang

The development of computer programs to solve complex ventilation networks has reached a point of refinement where these programs become a necessary tool of the ventilating engineer. Such a program is presented. This program has an increased efficiency over its predecessors; it also includes the important facility of fixed quantity branches. This is in addition to the earlier capabilities of free-splitting, internal or external fans, and natural ventilation pressures. The program is written in Fortran IV with double-precision arithmetic and is listed here. Sample problems with input and output are also given. The recent, and presumably continuing, official interest in mine safety is bound to result in more stringent control requirements for ventilation. Anticipating this requirement, the Dept. of Mining, The Pennsylvania State University, has developed a computer program for the solution of complex mine ventilation networks. It is the opinion of this department that the program has sufficient merit to warrant its use in normal industrial operating conditions. Although the undergraduate mining engineering students of this department are routinely trained to use the program, it was felt that this training did not present a fast enough means of dissemination; consequently, this paper was written. The conception of the program is not new;1; however, the present version incorporates features that changes it from a scientific endeavor to a useful operating tool. These features include those of earlier programs, such as free-splitting, external or internal fans, and natural ventilation processes plus the important ability of handling fixed quantity branches, and of increased efficiency giving reduced cost. The facility for fixed quantities will be discussed in more detail. The solution of any network depends upon satisfying Kirchchoff's laws. These state that the sum of flow at any junction is zero, and that the sum of the pressure drop in branches totals the pressure drop in the mesh constituted by those branches, that is that the pressure drop around any mesh is zero. The terminology is derived from Synge," and is, in fact, that used by Topologists. A branch is any airway of uniform characteristics; a junction is where two or more airways meet (the minimum number of two airways is useful for describing the point where a low resistance airway changes into a high resistance one due to some physical constriction); a mesh is a path, along some branches, that returns on to itself, but does not need to traverse the same branch twice in order to do so; and a tree describes all those branches in a network which, while connected through all the junctions, do not form any meshes. Obviously the branches-in-tree are open-ended and can be shown to be one less than the number of junction (J-1). The branches-out-of-tree, also called basic branches, are equal to the number of basic meshes and are M = N — J + 1, where M is the number of meshes and N is the number of branches. The major difference between this network and an electrical one is that the law attributed to Atkinson for pressure drop is utilized rather than Ohm's law. Atkinson stated that the pressure drop (potential) is equal to a resistance factor multiplied by the quantity squared. This is written H = RlQlQ where H is the head loss. Q? is written in this factored fashion so that H will always have the same sign as Q. A negative sign is used to indicate that flow in a branch is opposite to that of its containing mesh. A mesh takes the direction of its basic branch. Utilizing Atkinson's law in Kirchchoff's second law and bearing in mind that the first law must remain satisfied, the program will determine all quantities, or head losses as they are related, for the branches of the network. The program uses a Geuss-Seidel form of in-teration, starting from an arbitrary Q and using a correction factor of the type first suggested by Professor Hardy Cross' that will handle the nonlinear equation of Atkinson's law. A fuller description of the interative process is included in Wang and Hartman.' Iteration continues until the correction factor is less than or equal to a preset error (E) or until a maximum number of iterations (MAXIT) have been reached. Utilizing an E of 50 cfm, sample problems have had rapid solutions. Rapidity of solution is also ensured by the method of selecting meshes and basic branches. This is done by the computer, which chooses the highest resistance branches, fixed quantity branches, and those containing fans, as basic branches. Natural ventilation pressures are handled as fans of constant pressure and may be assigned to any branch. The computer will generate a fan characteristic by polynominal fitting if a few operating points from the desired fan are input. A fan may be placed in any branch of the network, except those with fixed quantities. The strength of the present program over its earlier versions is its ability to handle fixed quantity branches. This means that certain branches can have their quantity determined, or preset, by the ventilating engineer. Operating under this constraint, the program will analyze the network and output the pressure change necessary to achieve this desired quantity. A call for positive head loss would require an auxiliary fan; negative head loss would require a regulator. This represents a powerful tool for the ventilating engineer who must insure that certain quantities of air pass across the operating faces or through working stopes. McPherson6 suggested that a ventilation program would be useful for determining in advance which branches were receiving inadequate air, and that subsequent calculations would then indicate the necessary corrections. The present program makes these corrections. Thus the mine manager can know immediately the consequences of changes to his system;

Jan 1, 1971

By Mohamed Ahmed, A. Kawy

"Smelting of scrap copper and residual anodes and cathodes carried out in a reverberatory type furnace. In this, deoxidation process is carried out by wood, which acts as a resource of reduction gases such carbon monoxide, hydrogen and methane. Use of wood causes the formation of soot pollutants and efficiency of oxygen removal from copper is low leading to added costs in removing contaminants. This expensive problem was solved by using of reformed natural gas as a source of reduction gases (CO+ H2).IntroductionThree reverberatory furnaces were used for smelting of scrap copper and residual anodes and cathodes. Each furnace had a 7tpd capacity and was operated at 1183 °C.In this furnace, Step1-compressed air supplied by tubes from the side of the furnace to remove sulfur from copper matte by oxidation .The copper is also oxidized to copper oxide .[1]Step 2- copper from matte is deoxidized by a reductant. Typically deoxidation process is carried out using wood as a resource of carbon monoxide, hydrogen and methane which are the reduction gases. Use of wood causes the following:1- Forms soot pollutants2- Oxygen removal efficiency from copper is low; more contamination in copper matte increased energy in deoxidation3-the process is highly expensive.In the recent trends, this problem has been solved by using reformed natural gas as a source of reduction gases (CO+ H) .This results in 1-Reduced pollution during smelting.2- High efficiency in the removal of oxygen from copper to produce oxygen free copper. The surface of copper produced from this method is smooth which helps in forming and machining.3- Low cost and natural gas is more readily available in Egypt than wood."

Jan 1, 2010