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Discussion of the paper of BENJAMIN F. TILLSON, presented at the NEW York meeting, February, 1915, and printed in Bulletin No. 9S, February, 1915, pp. 505 to 528. T. E. STURTEVANT, * New York, N. Y.-Mr. Tillson's paper on hammer drills is of much interest to me. Early in 1909 I was invited to make tests of our drills at the Franklin mine of the New Jersey Zinc Co. The first drill that we tested gave very poor results. This was a drill having a hammer piston 1¾ in. in diameter and 3 ¼ -in. stroke, the hammer piston weighing about 6 1b., the 1 ¾ in. diameter being exposed to pressure at either end. Although this drill has given excellent results as a sinking drill, its performance as a stoping drill was poor. This was one of the surprises of the limestone as spoken of by Mr. Tillson. This led me to further investigation, and a second drill was developed, with a much lighter piston and a somewhat longer stroke, that gave better results. In the design of this drill, no attention was paid to the cost of construction, our whole attention being given to the increase in drilling speed and reduction of the quantity of air used. The first drill of this type had a piston weighing about 2 ½ lb. and a stroke of 3 ¼ in. The piston was made with a hammer-bar extension, and the cylinder was made with two diameters of the bore, one in which the hammer-bar extension moved and the larger one in which the piston head moved. The air was taken in at either end of the larger bore, thus giving a greater area to the

Jan 5, 1915

By A. Gillis, J. Keyes

"This is a prelirr1inary report on automatic control at East Malartic Gold Mines.After installation of the cyclones in the East Malartic grinding circuit, the interest was aroused in the automatic control system for the circuit. Investigations were made as to the possibilities of such an installation. This resulted in a preliminary survey of the circuit by Milltronics Ltd and an analysis of the circuit by Mines Branch personnel. A study of the investigation and analysis indicated that a cost reduction and improved efficiency could be expected by the installation of an automatic control system in the grinding circuit. It was also indicated tl1at such installation should pay for itself within a year. This was the point that sold management on such installation. The need of three operators was expected to be eliminated .The installation was to consist of a central control panel, microphoncs on each mill, regulation of feed rate, pneumatic valves for addition of solt1tions, density control of the cyclone overflow, which is a grinding circuit product, rod mill feed box plugging detector and a conveyer weightometer for tonnage indication and control.As well as the elimination of one man per sl1ift, other benefits which were to be received but unable to estimate were: 1) More tonnage per clay by operation of the mills at the proper capacities. 2) Lower grinding costs. Less under-loading should result in less steel wear and lower pumping cost. In the condition of overloading, a coarser grind is obtained resulting in greater impeller and liner wear. The overloading and underloading showed up on the n1icropl1oncs. 3) An improvement in the recovery as a result of less over-load. The tailings loss from a coarser grind are not as frequent."

Jan 1, 1965

By F. L. Grammer

The analyses given in Table I. were made several years ago at my request at a plant using Lake ores. They are of two furnaces, one making basic, the other Bessemer pig— they gave 6 casts each in 24 hr., also two flushes of cinder between each cast. They are offered simply for the sake of reference as, so far as I know, it is unusual to find so frequent full analyses made and none are on record. The variations in manganese-content in the first and second flushes on the basic furnace are interesting, if no more than a freak—the first flush being invariably higher in manganese. The iron-content of the two slags from an average of 12 flushes shows: Basic. Bessemer. Per Cent. Per Cent. Total iron...................................... 2.85 1.70 Combined iron................................ 0.72 0.52 Free iron....................................... 2.13 1.18 The greater iron-loss in the basic slag, while known, has never heretofore been so clearly set forth. This may modify the arrangement for handling slag; heretofore usually determined by proximity of the dumping-heap. If a nearby heap is used on contiguous territory, in the past, tilting molten-slag pots were used. If the Pittsburg flood-records for 30 years are a fair criterion the government regulations were inadequate, and molten slag was dumped in such a manner as to throttle the Monongahela at the time of the spring thaws. At Pittsburg the slag, where it is carried to a distance, is frequently granulated in pits and then removed in cars to which it is conveyed by clam-shell buckets. This practice is also quite customary where the slag is intended for the manufacture of slag cement. The production of 500 tons of cast-iron daily means about 300 tons of- slag and at 2.113 per cent. equals 6.4 tons

Jan 1, 1914

By B. H. Sage, W. N. Lacey, W. M. Morris

The volumetric behavior of isobutane at temperatures below its critical temperature has been studied by several investigators. Seibert and Burrelll measured the vapor pressure of isobutane from the ice point to the critical temperature. Dana and co-workers2 determined among other thermodynamic quantities the density of the saturated liquid and the saturated gas and the vapor pressure from approximately 0 to 130 F. Sage and Lacey3 studied a number of the thermodynamic properties of this hydrocarbon from 70" to 250" F. The specific volume in the gas and liquid region was determined at pressures up to 3000 Ib. per sq. in.? throughout this temperature interval. In addition, the vapor pressures were measured at 30" intervals. These data taken together serve to establish the thermodynamic behavior of isobutane at temperatures between 0" and 250" F. with reasonable accuracy. However, apparently there are no data available at the higher temperatures. For this reason an investigation of the volumetric behavior of isobutane at temperatures between 100" and 460" F. was carried out with apparatus that has been described in another paper (p. 136, this volume). Materials The isobutane used in this investigation was obtained from the Philgas Division of the Phillips Petroleum Co. That company's special analysis upon this sample indicated it to contain less than 0.03 mol per cent of impurities. In order to avoid traces of noncondensable gases, this hydrocarbon material was subjected to two successive fractionations at a high reflux ratio in a column approximately 4 ft. long and % in. in diameter, which was packed with small glass rings. The middle portion of distillate from the first fractionation was used in the second fraction-ation and a portion of the overhead from this second distillation process was repeatedly condensed at liquid-air temperatures at a pressure only slightly above the sublimation pressure of isobutane at this temperature.

Jan 1, 1940

By D Newton

The Mt Morgan Minesite in Central Queensland has been subject to both underground and surface gold mining operations since the late-1800s. The site is largely unrehabilitated and poor quality surface run-off and subsurface leachate is contaminating the nearby Dee River. The site is dominated by a large open cut, which now stores contaminated surface and subsurface run-off. Three models were used to simulate the complex hydrologic processes occurring at the Mt Morgan Mine: a rainfall-run-off model, a groundwater model and a storage behavioural model. Study results showed that the open cut is filling with water and will soon spill large volumes of highly polluted water to the Dee River on a regular basis if no remedial action is taken. This will result in a three-fold increase in pollutant load to the Dee River. Based on a consideration of water quality and quantity it was concluded that the first priority for future minesite water management should be the prevention of spills from the open cut. Potential management options to achieve this objective included surface rehabilitation, catchment diversions, modification of the pump-back system and controlled releases to the Dee River during floods. However, assessing the relative effectiveness of these measures required a thorough understanding of the complex surface and subsurface hydrology of the site. The results of a 100 year simulation of hydrologic processes revealed that previously favoured management options would be ineffective in preventing spills to the river. On this basis, a continuous treat and release strategy was proposed as the only reliable method of preventing future spills. The results of this study demonstrate that good environmental management decisions must be based on an understanding of the relevant physical processes and consideration of cumulative effects over an appropriate time scale.

Jan 1, 2003

By Vittorio Basilico, Marco Quattrone, Mario Bassan

"In Italian building market one of the reasons that often stop building contractors from not taking into consideration the possibility to recycle rubble from building is represented by the increase of costs for rubble separation. However the recycling of C&DW can also allow a decrease in disposal costs and a reduction in raw materials requirement.In this paper the results of a testing conducted on a case study through economic and technical analyses are presented.Results highlight that a wise management of demolition and disposal processes can generate a remarkable saving and that it is possible, on the other side, to achieve environmental benefits such as reduction of raw material consumption and dump life lengthening.IntroductionTwo major factors have been found to have considerably influenced the market of recycled aggregates in Europe and Italy: the EU and national regulations and environmental awareness. The market of recycled aggregate has grown in countries with limited natural resources.Waste disposal has also been one of the top EU political and environmental priorities. In the complex interaction between human activities and the environment, waste is proved to be one of the most environment-degrading products.In 1972 the European Commission introduced measures on waste reduction, reuse and recycling. In 2006, directive 2006/12/EC (European Commission) on waste was issued. It covers the scope of minimizing the waste, prevent hazardous waste, maximize reclamation, reuse, recycling and energy-recovery.No specific directive refers to management and recycling of construction and demolition wastes. However, in 1992 the European Commission listed debris among waste management priorities because of its growing amount.Only recently, effective environmental policies have been implemented in Italy, even though relevant environmental issues started rising as early as the beginning of the 1970s. In the 1980s the Government undertook the first significant measures to handle the waste management."

Jan 1, 2008

By Charles M. Rolker

It is now three years ago that I wrote a paper on the fire which broke out in October, 1880, at the Chrysolite mine, Leadville, Col orado, of which I was at that time manager. The paper was read by title at the Harrisburg meeting in 1881, and was accompanied by plans and sections fully illustrating it. It was written to invite a general discussion of the course pursued in the management of that fire, since the various fragmentary and sometimes prejudiced or inaccurate newspaper accounts were not suitable to base judg ment on. The paper I offered, gave the facts as they appeared in the contemporaneous record which I had kept. At that time, a dif ference of opinion had arisen with an adjoining mine, as to possible damages entailed through the fire; and a law suit was talked of. In view of these circumstances, the President of the Chrysolite Company advised a temporary withdrawal of my paper. Somewhat later, I withdrew it entirely, because of the unlooked-for delay in * arranging the controversy referred to. It. has now, indeed, been amicably settled; but the lapse of time has deprived the matter of much of its immediate professional interest. To the urgent request of some of the members, that I should, at least, give a description of the fire- and gas-proof bulkheads employed, I yield with some hesitation, since I lay no claim whatsoever to orig inality in these devices, and therefore question the value of such a paper. The fire originated by accident, in the Chrysolite, a mine comprising extensive and more or less irregular workings, containing immense quantities of timbering, but partially packed with waste rock or earth. This class of mines is numerously represented at

Jan 1, 1885

Such are the rigors of climate and topography of western Tasmania, that much of the area has remained uninhabited. The mountains, rising to peaks above 5000 ft high, receive the winds out of the west and precipitate 110 in. of rainfall a year on this coast. The drenched forests have a primordial look with such unfamiliar trees as the tru-sassafras, blackwood, cheesewood, ti tree, and man tree ferns. Prospectors speak of the "horizontals," trees which, in the dense foliage, grow out flat. When the explorer climbs over them he does not come back to the ground but continues forward on dense vegetation with the ground many feet below. Gold was discovered by the intrepid prospectors of the late nineteenth century and stamp mills were erected in the vicinity of Zeehan and Queenstown. At Mount Lyell, mining began for gold in the ironstone capping. The familiar story, of course, is that copper was found beneath the gossan and it was this mineralization that lead to permanent mining operations. Two companies began mining at Mount Lyell and their history from 1893 to 1902 was marked by an unreasonable competitiveness, human perversity and technical difficulties. The North Lyell and Mount Lyell companies were mining copper ores within one mile of each other separated only by a ridge. Each company built its own railroad and harbor. For six years of struggle both companies tried to work out the metallurgical problem which was the key to profit. Although they didn't know it, the two ores were complimentary and could have been smelted together. North Lyell ore was strong in silica and weak in iron, whereas Mount Lyell was fortunate in having a first-class metallurgist in Robert Sticht, from Brooklyn, N. Y., who in 1902 successfully achieved pyritic smelting without the use of carbon fuel.

Jan 10, 1964

By Richard R. Radel, Jack Barry

Contract required excavating 2,000 If of 14' horseshoe tunnel in rock, a 95' deep work shaft on shore, and a 50' deep intake shaft located in the middle of the Niagara River just above Niagara Falls. Large quantities of H2S were encountered in the range of 20 PPM with ventilation. Peak levels of 40 PPM were recorded. The original designed ventilation system required only a volume of 10,000 CFM to meet OSHA requirements. The volume of air was increased to 50,000 CFM to dilute the H2S to al- low workmen to work and comply with OSHA H2S action levels. The second phase of the tunnel consisted of placing 72" ID X 20 foot long concrete reinforced pipe in the tunnel. When the tunnel was holed through and both shafts were open, a substantial amount of work was required to take place in the shafts which eliminated the possibility of placing a bulkhead to secure proper ventilation. The ventilation team designed a jet system airlock. The design of this system was to bring fresh air down the work shaft in two duct systems; one 30" diameter and one 24" diameter. Following the excellent work of Jan Wolski (7th Mine Ventilation Symposium chapter 58) our design incorporated nozzles located approximately 100' in by the work shaft. The velocity of the 24" diameter duct was 6,365 FPMD2.2 MPH. The velocity of the 30" diameter duct was 6,117 FPMl69.5 MPH. Both systems were on blow and being that air expands at 3112 degrees per side this high velocity of air expanded and created an air bulk head through which men and the large sections of concrete pipe could be passed without any delay or additional cost to the project.

Jan 1, 1997

By Joseph Pogue

PRORATION in the petroleum industry has come to mean a method for curtailing the production of crude petroleum by artificial effort, and it is in this sense that the term is employed throughout this paper. Although a contrived curb on supply has been invoked at various times in the past in particular fields and to meet specific situations, it is not until the past few years that this procedure has become general and assumed a dominant role in the oil business. In the sense that we now understand it, proration had its inception in the Seminole area of Okla-homa in 1927, from which time and place the practice spread to include practically all the flush oil fields of the country, especially those of California, Kansas, Oklahoma and Texas. At present there is perhaps no phase of the oil business that commands more attention than proration, nor one that engages more time and effort on the part of executives in the business. The practice of proration, indeed, has not only become an integral part of the policy of most companies and operators, but it has also taken on the aspects of a "movement" involving two schools of thought with considerable feeling, and at times some bitterness, on both sides. In this atmosphere it is difficult to find calm, dispassionate consideration of proration, for most discussions are either vigorous exhortations by its proponents, or else sharp condemnations by its opponents; although it appears that the majority of the industry is clearly "in favor of" proration. It is hoped that this analysis will be taken as an attempt to appraise the movement as an economic force, without bias and without regard to the incidence of the conclusions upon any preconceptions that the industry may entertain.

Jan 1, 1932

By Robert Kinzie

WHEN Mr. Cameron, the President of the Santa Cruz Portland Cement Co., returned from Europe in 1929, he brought first-hand infor-mation about a very versatile type of hydraulic cement. It was not a new cement, many articles having been written about it in foreign journals, but in this country the record of this type of cement had been either neglected or minimized. Using local materials, and applying the information brought back by Mr. Cameron together with many data in numerous publications, the Santa Cruz Portland Cement Co. developed the Santa Cruz high-silica cement. This cement is manufactured by grinding with portland cement clinker a properly calcined mixture of siliceous material and lime. It has all the utility of portland cement, together with an increased resistance to the destructive action of many aggressive solutions. To explain the necessity for the development of a cement having these characteristics, the history of hydraulic binding materials may be reviewed briefly. The materials used as binding media by primitive people were mud, lime, gypsum and bitumin. Due to its utility, ease of preparation, and its common occurrence, lime was the most widely used. Fat lime, when used by itself or with an inert sand, hardened only on the outside surface, where the carbonate was formed by absorption of carbon dioxide from the air, while, the interior of the mortar remained soft. It was quite early discovered that the incorporation of proper siliceous material with the lime increased its ability to harden, and for this purpose various natural siliceous powders were used, such as puzzo-lana in Italy, trass in what is now Germany, and santorin in Greece. These powders reacted with the lime forming a permanent cement and rendered unnecessary the access of carbon dioxide to the mortar.

Jan 1, 1934

IN THE early evening of October 15, 1954, a large specially designed truck, convoyed by a second smaller one, arrived at Silver Bell, Arizona, completing a ten-hour 110-mile journey from Phoenix. The big truck was driven through gaps left in a previously prepared concrete foundation, the load was jacked up, the large girders that constituted the bed of the truck were pulled away, and the load was then lowered into place on the foundation. A crew of two men, the two truck drivers, finished the job in a little more than an hour. When they were through, a complete and attractive three-bedroom house, prefabricated in Phoenix, was almost ready for occupancy. About all that remained to do was to connect the utilities-water, electricity, plumbing, and gas. The kitchen and bathroom equipment and appointments were superior in every respect, and there was a built-in car port for the automobile of the prospective residents. This family domicile was one of more than one hundred, each averaging about $8,000 in cost, that the American Smelting and Refining Company has provided for its employees engaged in mining and milling 7,500 tons per day of low-grade Porphyry copper ore. Aside from the fact that it is more economical-partly because of the variety of union craftsmen needed to build and equip a house-to do the work in a city 110 miles away, the significant point is the high quality of housing that is provided for what may be called in nostalgic vein the "mining camp" of 1955. Silver Bell is typical of all the Porphyries in this respect though the community is relatively small. At San Manuel

Jan 1, 1957

By G. Bassi

RECENTLY Wallbaum¹ found that copper wires with different degrees of deformation up to 98.7 pct area reduction recrystallize giving a [112] texture, while deformation over 98.7 pct gives either a [l00] texture at low temperatures or a [1ll] texture at high temperatures. Furthermore it was found that the recrystallization temperature as a function of deformation up to 98.7 pct decreases as expected, but increases over that deformation. Wallbaum concluded that the different textures have different recrystallization temperatures. The [112] texture has the lowest and [Ill] the highest. At the same time Bassi² found that for high deformation (over 99 pct area reduction) and for an annealing temperature of 400°C, the [l00] texture first forms and with prolonged annealing time the [12] texture appears through grain growth. This secondary texture does not appear if the wire is annealed at 1000°C before the deformation. From these two papers it might be concluded that the [I12] texture can appear either as a primary or as a secondary texture after annealing. The texture formed in a special case depends on the previous history of the wire. Probably the texture of the wire prior to the last deformation is important. To investigate this, wires were produced by adequate deformation and annealing to give a [l00], a [112], and a [lll] texture. The wires then were given a series of different deformations and were annealed at various temperatures, after which the textures were studied. Experimental Work The copper used was electrolytic tough-pitch (Cu 99.90 pct and 0, 0.04 pct). Three wires with the different initial textures were made in the following way: The [l00] and [112] by drawing a 16 mm rod to 1 mm and annealing it 16 hr at 200°C and 2 hr

Jan 1, 1953

By R. G. Ward

The temperature gradient in the subhearth metal or "salamandern of the iron bhst furnace results in the establishment of gradients in the concentrations of silicon, manganese, carbon, and sulfur. The temperature and compositional variations observed in three blast furnaces are analyzed according to irreversible thermodynamics and the systems appear to be close to the steady state condition. Apparent heats of transport, Q, for silicon, manganese, carbon, and sulfur are found to be respectively -17.5, -5, -2.1, and+22k cal per g mol. In conclusion the significance of thermal diffusion in extraction metallurgy is briefly discussed. INCREASING interest has been shown in recent years in the application of irreversible thermodynamics to metallurgical problems. In particular studies have been made of the transport of matter in thermal gradients1-' and under chemical gradients imposed by a binary solvent However, no detailed example in extraction metallurgy has been reported although gradients are the essence of many extractive processes. The case of the distribution of elements in molten blast furnace iron under a thermal gradient is discussed here. DATA In blast furnace operation the hearth bottom is often extensively destroyed by molten metal, and the metal may penetrate perhaps 10 ft into the furnace foundations forming a "bear" or "salamander". Several hundred tons of molten metal may thus exist beneath the level of the conventional tap hole and remain relatively undisturbed for several years under a thermal gradient. This system is subject to little convective stirring because the temperature decreases from top to bottom, and mechanical stirring due to movements in the stack and to tapping operations is unlikely to penetrate far into the metal. The system may thus be regarded as static

Jan 1, 1963

By M. A. Mallinger

A series of laboratory tests was conducted to determine the limits of practicability in regulating the weights of various cement slurries. It was found that slurry weights of 12 to 19 lb per gallon could be obtained by adding bentonite to decrease the weight and barytes ore to increase the weight. It was also found that barytes ore was not usable in all cements. LIGHTWEIGHT CEMENT SLURRIES INTRODUCTION During the drilling and completion of oil wells the magnitude of the hydraulic pressures exerted on certain formations is critical. In many cases considerable care must be exercised to prevent drilling mud weights from becoming too high, and in those wells where loss of circulation is a problem, the use of normal weight cement slurries will generally result in lost returns during casing cementing operations. While mud weights can easily be controlled, it is necessary to exercise care in the selection of weight reducing additives for cement slurries in order that slurry weights may be reduced sufficiently to prevent the loss of a large portion of the cement to the thief formations without seriously affecting the setting properties of the cement. EXPERIMENTAL RESULTS An extensive search revealed that a large number of materials .that might have been otherwise practicable as a weight reducing additive were not acceptable for use with oil we cements because the imposition of pressure on the slurries caused the additive being tested to be compressed or to absorb water from the slurries, resulting in negligible decrease in the slurry weight. This search for lightweight additives disclosed that bentonite, a material very commonly used for reducing the weight of drilling muds and cements, produced the best results without undue harmful effects on the properties of oil well cements. It was found that there was a limit to the amount of benton-

Jan 1, 1950

By Brigitta Hassler

INTRODUCTION In the early 1960's research was begun in Sweden to improve the agglomeration of our domestic iron ore concentrates (5). Different agglomeration methods that were used in the building material industry were studied under the economic support from the Swedish Technical Council, the Swedish Board of Technical Development and by the Swedish industry. The research work was performed at the Division of Mineral Processing at the Royal Institute of Technology in Stockholm. All known agglomeration methods were reviewed and the methods were developed to produce superior quality agglomerates (6). The term cold bonding (in contrast to sintering) was introduced to describe the induration operation in these processes and this has been accepted internationally. Even though we used it mostly for steam autoclaving methods, it has come to describe a class of processes that use binding methods by pore filling. Schumacher in Germany discovered around 1907 that a strong material can be produced by mixing slaked lime with fine ground quartz and subjecting to a steam atmosphere under pressure at about 185ºC. This started development of lime-sandstone building materials and later on, in Sweden, the light-weight concrete. Schumacher also used the same reaction for briquetting iron ore concentrates by adding silica and lime, and autoclaving. The product seems to have been accepted for blast furnace burden and the process was used on an industrial scale until the 1920's. The sintering method has a small melting phase as diffusion medium and in the steam-autoclaving method a small quantity of water condensate at about 200°C serves the same purpose. Thus the induration process by the hydrothermal hardening methods is similar to that of sintering or heat treatment.

Jan 1, 1977

INTRODUCTION Engineering studies of many near surface coal deposits that are amenable to strip mining can be enhanced and expedited by the application of computer techniques for defining coal reserves and overburden and intraburden yardage and their stripping ratios. The case study discussed herein could be from the western coalfields of Colorado, Wyoming, or Montana; the lignite deposits of the Dakotas or Texas, or from the strippable coal seams of the midwest. Because the techniques can be applied so universally, the actual map locations are not identified. The same computing principles apply to one seam or multiseam deposits, and the capability of the computing programs and plotting routines to display the coal seams in plan and sections provide excellent base maps for further engineering planning and mine layout studies. MANAGEMENT OF DRILL HOLE DATA Drilling for coalfield information is usually done at much wider centers than for other mineral deposits. The geologic logs of the holes are generally quite simple, and frequently record only major lithologies and depths to the top and bottom of the coal seams, together with hole collar survey information. A header card is prepared for each drill hole showing: Hole ID Northing Fasting Elevation Azimuth Dip The header card can be followed by any number of downhole lithologic intercept records: [Hole Depth Lithology Hole ID From-To Coal] Less data errors occur if the computer cards are punched directly from drill hole logs, thus eliminating opportunities for mistakes in transcribing data. All arithmetic manipulations should be left to the computer to avoid as much human error as possible. The SURVEY program is run over the raw data file and all lithologic intercepts are computed and defined in XYZ space. BOUNDARY SURFACES-COAL SEAMS AND LITHOLOGIC UNITS The most useful computer program for defining coal seams in 3D space is a linear inter-

Jan 1, 1980

The object of this paper is not to describe any particular type of engine in close technical detail but rather to give a general picture of past and present practice in this important section of the industry. The subject involves the study of almost 600 years of coal mining history which has fluctuated from stagnation to extremely rapid progress.Up to the year 1300, coal was obtained from outcrops and exposed beds, but this easily worked source soon gave out, so by that time shafts had to be sunk to the coal seams, and coal mining proper commenced its career.These early shafts were very shallow, and winding equipment was not a matter for much concern. Raising coal was generally achieved by human labour, which was called "coal bearing." Coal was loaded into baskets. strapped to a man's back, and carried from the underground workings to the pit bottom. The unfortunate individual then climbed ladders to the top of the shaft, unloaded the basket, and descended the shaft for the next load. Men, women and even children, were employed as the mine expanded, and were generally bound to the colliery for life, performing daily work which would now be regarded as slavery. This primitive method of raising coal to the surface was slow, inefficient and highly dangerous, yet for want of a better method it continued until in 1602 it isrecorded as having been abolished in Wales, one of England's great coal districts. It was not until 100 years later, however, that it was abolished in the northern coalfields, and the colliers were freed forever from their dreadful life.WINDLASSThe first step towards winding coal was the introduction of the windlass. This was similar to the common windlass used over a well, and was operated by man power. The...

Jan 1, 1945

By A. E. H. Bergmann

INTRODUCTION The Sachtleben Chemie GmbH in Duisburg, a subsidiary of the Metallgesellschaft AG, operates a new sulfuric acid plant that employs fluid bed roasting of pyrite concentrates. The plant produces about 300,000 tons per year of pyrite cinders from the fluid bed roasting unit. The cinder product consists of 58 percent iron and is about 80 percent by weight smaller than 50 microns. This cinder product was found to be a competitive source material for the cement industry as the iron-containing additive. However, the extreme fineness of the cinder and its dusting tendency were undesirable and an agglomerating technique became necessary. In order to keep the price of agglomerated pyrite-cinders at a competitive level, the agglomerating method must be chosen such a way the capital and operating costs are low. Initial experiments were carried out on a laboratory scale to make an appropriate choice of the agglomerating method. Major goals of agglomerating the cinders were to improve the transportation, storage, and proportioning and metering properties. Minimum specifications are put on the size, size distribution and shape of the product. Criterion for handling is that a minimum of minus one mm. fines are produced after several handlings, while for storage, it is also desirable for the agglomerated product to survive several months in open air. Thermal agglomeration processes such as sintering one known to produce excellent products, but are by far too expensive for our application. For the same reason, granulation, balling, and pelletizing tests with addition of organic binding agents, such as tylose, starch, sulfite wash, molasses, etc. were not continued. The costs for the binding agent was considerable, which is probably due to the high pore volume of our cinders (35 %). Furthermore, the pellets or granules

Jan 1, 1977

By W. N. Lacey, B. H. Sage, W. M. Morris

The volumetric behavior of isobutane at temperatures below its critical temperature has been studied by several investigators. Seibert and Burrelll measured the vapor pressure of isobutane from the ice point to the critical temperature. Dana and co-workers2 determined among other thermodynamic quantities the density of the saturated liquid and the saturated gas and the vapor pressure from approximately 0 to 130 F. Sage and Lacey3 studied a number of the thermodynamic properties of this hydrocarbon from 70" to 250" F. The specific volume in the gas and liquid region was determined at pressures up to 3000 Ib. per sq. in.? throughout this temperature interval. In addition, the vapor pressures were measured at 30" intervals. These data taken together serve to establish the thermodynamic behavior of isobutane at temperatures between 0" and 250" F. with reasonable accuracy. However, apparently there are no data available at the higher temperatures. For this reason an investigation of the volumetric behavior of isobutane at temperatures between 100" and 460" F. was carried out with apparatus that has been described in another paper (p. 136, this volume). Materials The isobutane used in this investigation was obtained from the Philgas Division of the Phillips Petroleum Co. That company's special analysis upon this sample indicated it to contain less than 0.03 mol per cent of impurities. In order to avoid traces of noncondensable gases, this hydrocarbon material was subjected to two successive fractionations at a high reflux ratio in a column approximately 4 ft. long and % in. in diameter, which was packed with small glass rings. The middle portion of distillate from the first fractionation was used in the second fraction-ation and a portion of the overhead from this second distillation process was repeatedly condensed at liquid-air temperatures at a pressure only slightly above the sublimation pressure of isobutane at this temperature.

Jan 1, 1940