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Not many accounts of mining methods or labor conditions in the mines in early days can be found; all that have seemed to be authentic have been included in the preceding chapters. In practically every field opened before 18.10 the first coal was recovered by quarrying, or strip mining, the operations, of course, being by hand and on a very small scale; new places were opened as soon as mining became difficult or expensive. Where it became necessary to drift into the hillsides, the first coal was taken out by sleds, and later by small wagons, the power being supplied by the miner, often assisted by dogs. Wooden rails then came into use with small cars running on them. These cars were very small, usually holding only a few bushels; in the Belleville, Illinois field as late as 1863 cars having capacities of 10, 12, 14 and some as large as 30 bushels were in use. It was not until late in the 1830's that horses or mules came into use for haulage purposes in the Pittsburgh region, although some had been used in the Richmond, Virginia field at an earlier date. Coal was usually undercut by hand and wedged down, until explosives came into general use, and in nearly every field the coal was forked into the cars, the fine coal, or slack, being left in the mine. Hours worked were very long, but few records remain to show what they were at different places and times; there was undoubtedly a great variation between districts and mines. Roy stated a miner could often produce 5 or 6 tons in a day of 8 or 9 hours in a 5 or 6 foot seam, but in another seam possibly could mine only 3 1/2 to 4 tons. He estimated an average day's work in a four foot seam at about 3 1/2 tons.1 In a strike in the Belleville field in 1863 it was found that an average skilled miner in the field could probably produce 4 to 5 tons a day.2 This was only the coarse coal loaded and did not include slack. In 1873, a coal undercutting machine was tried at a mine about two miles from Brazil, Indiana, said to be the first coal machine ever invented in the United States. It was run by a 5 H.P. steam engine (later to be changed to compressed air), and consisted of an iron rim, four feet in diameter with movable steel teeth placed about one foot apart. The rim

Jan 1, 1942

By Y Potvin

Risk assessment in the mining industry is currently a topic of great interest with risk methodologies being increasingly applied beyond the traditional areas of finance and feasibility to analyses of risks due to various physical hazards including chemical, electrical, mechanical and geotechnical sources. The application of risk analysis and evaluation techniques to the management of personnel safety is being promoted by both industry and regulators but, particularly for geotechnical hazards, often there are inadequate databases for a meaningful quantitative calculation of risk. In Western Australia over the decade 1987 - 1997, the annual fatality rate for underground mining has averaged at approximately 1.3 in 1000 employees with rockfalls/rockbursts accounting for over half of these deaths (Prevention of Mining Fatalities Taskforce, 1997). Recent improvements have been made since this time, perhaps halving the annual fatality rate, mainly due to industry improving ground control measures and implementing various recommendations from the Prevention of Mining Fatalities Taskforce (1997). However there still remain a large number of unknowns when trying to address the complex area of geotechnical risk in mining. Risk calculations require information about the source of the hazard, the people or assets exposed to the hazard (the æelements at riskÆ) and the effects on these vulnerable elements if the hazard actually occurs (the potential consequences). To date, little information has been available on the exposure of mining personnel and equipment to underground hazards other than occupational safety studies on chemicals, heat, dust, etc. This paper concentrates on underground geotechnical risks and presents a data collection and rating system for the exposure of both the underground workforce and equipment to rockfalls and rockbursts. The methodology considers exposure times, personnel protection levels and hazard proximities to give exposure ratings for the major underground mining activities and hence rate different locations within a mine. This exposure methodology is then applied to the workforce and production/ development cycles in an actual WA underground mine, creating a snapshot map of differing levels of personnel exposure across the mine.

Jan 1, 2003

By Hee Dong Jang, Hong Yong Sohn, Miguel Olivas-Martinez

"Tetramethylorthosilicate (TMOS), a precursor of silica nanoparticles, is prepared from the waste silicon sludge, followed by the synthesis of silica nanoparticles from the TMOS by flame spray pyrolysis. A two-dimensional multiphase computational fluid dynamics (CFD) model for the flame spray pyrolysis process (FSP) for the synthesis of silica nanoparticles has been developed. The model incorporates the governing turbulent equations of overall continuity, momentum, energy and species mass transport to represent the gas phase and the population balance model (PBM) to account for the silica nanoparticles. The model has been validated with experimental data in terms of gas temperature and average particle size. Introduction Silica (SiO2) nanoparticles are used in various industrial applications, such as catalyst, pigments, thin film substrates, electronic and thermal insulators, and humidity sensors [1]. They are also used as additives in plastics and rubbers to improve the mechanical properties of elastomers, and in liquid systems to improve their suspension behavior. These applications rely on the particle morphology, average particle size, particle size distribution, and phase composition [2]. Silica nanoparticles can be synthesized by wet chemical processes such as sol-gel methods and high-temperature processes such as flame spray pyrolysis (FSP). The FSP process provides a unique control of particle size and crystalline structure and it can also produce high-purity, thermally stable particles continuously with minimal further treatments. The sizes of the flame- made particles range from a few to several hundred nanometers, depending on the operating conditions [1]. The synthesis of silica nanoparticles from organic compounds that contain silicon by the FSP process is of interest because it generates no harmful by-products [1, 3]. Several compounds such as tetraethylorthosilicate (TEOS) and tetramethylorthosilicate (TMOS) can be used to synthesize silica nanoparticles, but most such compounds are expensive. Thus, it is desirable to prepare the precursor compounds from waste materials. In the present study, TEOS and TMOS synthesized from silicon sludge were used as precursors of silica nanoparticles [4]."

Jan 1, 2008

By J. H. Field

Results of studies by the Federal Bureau of Mines on a pilot-plant scale for removing hydrogen sulfide and carbonyl sulfide from gas mixtures by the hot carbonate system are given in this publication. Gases containing up to 10 pet. hydrogen sulfide and 48 grains carbonyl sulfide per 100 cu.ft. were treated. In most tests carbon dioxide also was present and was removed simultaneously with the sulfur compounds. Because the rate of absorption of hydrogen sulfide is much more rapid than that of carbon dioxide over a wide temperature range, selective removal of hydrogen sulfide occurred in the bottom section of the absorber near the point of gas entry. Hydrogen sulfide was removed to pipeline specifications with carbonate solutions by using split-stream flows in the absorber and regenerator.

Jan 1, 1960

By R. E. Ogilvie, H. C. Gatos, R. E. Hanneman

The ejj-ect of high pressures on chemical inter-diffusion in the Fe-V system was determined by analyses of concentration vs distance profiles of atmospheric and high-pressure diffusion couples. Diffusion data were obtained as a function of tern -perature and composition. Activation energies, activation volumes, and frequency factors were determined at 1 atm, 20 kbars, and 40 kbars as a function concentration in the a and y phases. The A great deal of research has been carried out in the measurement and understanding of binary chemical inter diffusion in solids. Studies of the effects of high pressure on interdiffusion in binary systems, however, have been virtually nonexistent until the present work. This paper gives a detailed account of the effect of high pressure on interdiffusion and the Kirkendall effect in the Fe-V system. The present data are compared to existing theo- Kirkendall effects were measured at 1 atm and 40 kbars. At 1 atm Dy > DFe at the marker concentration; however, Dv approaches DFe under pressure, and at 40 kbars the values are approximately equal. The high-pressure and atmospheric diffusion data are evaluated on the basis of theoretical models. Chemical analyses of the diffusion -couple profiles were made using an electron microbeam probe. retical treatments of pressure dependence of diffusion which are based upon self-diffusion studies. THEORY The rates of atomic migration in metals and alloys are regulated by the repulsive forces exerted on an atom during its motion from one equilibrium lattice site to another and by the availability of a jump site. Application of high pressure is expected to decrease diffusion rates because it decreases interatomic distances as well as defect concentrations. A number of theoretical treatments have been focused on the problem of calculating self-diffusion coefficients in solids under atmospheric pressure. In general, the vacancy mechanism of diffusion appears to be dominant at high temperatures in most metallic systems. The migration of an atom by this

Jan 1, 1965

By P. R. ZETTWOOG

HISTORICAL BACKGROUND A program in France to develop personal [a] dosimeters has been initiated 1974. The patent on which is based the present device was obtained in 1972 * . From 1972 to 1974, the possibilities of applying certain ionograph track detectors to the spectrodosimetry of radon daughters was explored. The first prototype were produced in 1974. It took four years (from 1974 to 1978) to produce an autonomous dosimeter whose components has a sufficient life span, especially for the turbine motor unit. Qualification in the laboratory was obtained in 1977. In 1978 it was obtained in the mine for technology (autonomy of 12 hours and a life span of more than one year) and in 1980 for monitoring. 300 dosimeters have been tested in underground mines all together. Indispensable peripheral equipment were also developed from 1976 to 1980 : calibration devices, equipment to prepare and develop the films, read out systems. The concept of an "Integrated System of Individual Dosimetry" (ISID) based on a personal [a] dosimeter measuring exposure to radon daughters, thoron daughters, ore dust and external irradiation doses was proposed at the end of 1980. Since January 1st 1981, ISID is used on a routine basis in some french mines, situated in remote area, and appears to be very competitive with the ambiant dosimetry. The latest version of the dosimeter is produced in mass series since June 1981 and should equip all french mines in 1982. DESCRIPTION OF THE INSTRUMENTATION DEVELOPMENT OF THE DOSIMETER MEASURING HEAD The measuring head is based on the use of ionographic film to detect a tracks. In fact, the measuring head is a spectrodosimeter which measures separately over the period of exposure: - the potential [a] energy inhaled due to the decay of Po 218, Po 214, and Po 212 ; - the number of Rn 222 atoms inhaled ; - the inhaled total [a] activity of the five long-lived emitters present in the ore dust. The contribution to the total inhalable potential [a] energy of these various radionuclidesin a typical underground mine is studied in Appendix I. The measuring head described in detail in Appendix II, is able to satisfy all the implications made in the ICRP recommendations. Appendix III deals with the use of this measuring head in the cases where the equilibrium factor is lower than 0.1. This situation occur in open-pit mines where account must be taken of the Rn 222 contribution, which is no longer negligible in relation to that of its daughters. CURRENT DOSIMETER PERFORMANCES Table I shows the characteristics of the latest dosimeter. Appendix IV should be consulted concerning qualification of the dosimeter in the laboratory and in mines, technological development which finally produced the [a] dosimeter and its peripheral equipment, and technical presentation of the ISID (Integrated System of Individual Dosimetry) based on the concept of a multirisk personal dosimeter. Data on the installation and operating costs of such a dosimeter, which would seem to be competitive, are also given in this Appendix. ADVANTAGES OF PERSONAL DOSIMETRY AS COMPARED TO AREA MONITORING The results of the first eight months of experiments carried out under real conditions in an underground mine site are given in detail in reference 8. Area monitoring : The monthly exposure per worker to inhaled Rn 222 was determined from the knowledge of time spent in various areas of the mine and for the different mining operations, as well as from numerous and systematic sampling of the Rn 222 concentration in all work places. Personal dosimetry : The exposure to potential energy from radon daughters was measured by an [a] dosimeter developed by the CEA and worn by each of the 160 miners during eight months. In this way 160 x 8 pairs of monthly individual exposure values have been obtained which can be statistically studied. This test was decisive for us because it proved that the [a] dosimeter was technically sound (very few defects over one year for 160 dosimeters) and especially that personal monitoring devices were superior to area monitoring devices. The following conclusions can be drawn 1. The exposure distribution obtained by personal dosimetry is log-normal. This is true for the results on the whole as well as for groups of results relating to certain explanatory variables. See fig. la, 1b, 1c. 2. The exposure distribution obtained by area monitoring does not correspond to any type of distribution. If the results of personal monitoring are taken as a reference, area monitoring tends to underestimate the high exposures and overestimate the low exposures.See fig. 2. 3. [a]-energy exposures are underestimated when calculated from radon exposures and the equilibrium factor found in the considered mines. This is due to episodes or to zones of high radon concentrations not registered

Jan 1, 1981

By Richard McCaffery

THIS paper considers certain aspects of the acid Bessemer process, particularly in its relations to the duplex process-that combination in which the pig iron is first desiliconized and decarburized in acid Bessemer converters and then dephosphorized in basic open-hearth furnaces. The acid Bessemer process employs an acid-lined converter and produces an acid slag. The blow is usually thought to eliminate the silicon and manganese as oxides and then to burn off the carbon as carbon monoxide. On account, however, of the relatively large amount of metallic iron present in the converter, compared with the relatively small amount of the impurities it is desired to oxidize, the first reaction in the converter probably is the formation of iron oxide, which dissolves in the bath and acts as an oxygen carrier for the silicon and carbon. As soon as iron oxide is dissolved throughout the bath, the oxidation of silicon commences; but in the early stages of the blow the mass law would indicate that iron oxide must form first, and this oxide probably increases up to some saturation point. The molten metal in the converter from the early stages of the blow right through to its completion remains basic, while the slag produced is siliceous. This fact is shown by the corrosion of the acid bottom and the tuyeres, which is greatest at the tuyere orifice where oxidation is most active and where there is the most iron oxide. Why does this acid bottom corrode? Because it is attacked by a base. The thought, therefore, suggests itself, why not make the bottoms of basic or neutral material?1 As the converter slag is acid, those parts of the converter coming in contact with the slag should be acid; but those parts of the converter that are in contact with the molten metal saturated with metallic oxides should be basic or neutral. Bessemer operators have for some time tacitly admitted this condition, for the blast pressures have steadily increased with the object of keeping the metal in suspension, and so preventing bottom corrosion; if the molten metal were not basic, it would not attack an acid bottom. In addition, the tuyeres are bunched together at the middle of the bottom and a clear space is left around the outside of the bottom; if tuyeres are placed too near the side walls the

Jan 8, 1920

By Rossiter W. Raymond

The lead-mining industry of Missouri, as of other parts of the Mississippi basin, appears to have been paralyzed by the shock of competition with the mines of the States and Territories further west. It is difficult for establishments working galena ores, too poor in silver to pay for extracting it, to compete with the producers of the argentiferous carbonates of Utah and Colorado, who look upon their lead as a by-product of little value, and are satisfied if it pays the charges of transportation, or the loss in smelting for silver. But simultaneously with this depression in the lead-mining of the Mississippi States, the development of new zinc deposits has caused a notable revival in the mining of zinc ores. There has recently been a sndden and strong rise in the price of' spelter, which, though probably to a large extent temporary in character, has given important encouragement to prospectors and miners. Apart from the general recovery of business in the United States from the prostration of the past six years, the cause of the advance in spelter has been the falling off in production, resulting from the shutting clown of several leading Western works,—the Martindale and Carondelet works, at St. Louis, and the Consolidated Company in Kansas. At the same time, the principal works at La Salle, Ill., were undergoing repairs, and produced less than usual, while the sheet-mill of Matthieson & Hegeler, at that place, was running as usual; so that this concern, ordinarily a large producer, entered the already depleted market as a buyer. These causes are in their nature transitory, and it is quite likely that spelter will be superabundant in a few months. Having lately received from a well-informed Missouri correspondent some samples of the zinc ores and a general account of the ore deposits of Southwest Missouri, I have thought that it might interest the Institute to examine these specimens, and to hear such brief statements concerning the region as I am able, upon good authority, though without the aid of any personal investigation 011 the spot, to give. The zinc-bearing territory in Southwest Missouri appears to be very extensive; that is to sap, zinc ores have been mined during the last year at various points throughout a district extending from the eastern edge of Kansas, west of Joplin, to a line some 50 miles east

Jan 1, 1880

By J. Jones-Parra

In previous Technical Notes, W. R. Rose' and W. Purcell have discussed the capillary pressure data presented by Welge.' Welge obtained capillary pressure curves of the imbibition type in which it was necessary to apply to the apparent wetting phase a greater pressure than that of the non-wetting phase to complete the cycle and reduce the non-wetting phase saturation to low values. Rose suggests in his Note that conditions of equilibrium could not have prevailed, since the. non-wetting phase pressure must always be the greater. Pur-cell in his Note, proceeds to postulate a pore system consisting. of a series of "holes in a doughnut," in which he contends that under equilibrium conditions it is necessary to resort to negative capillary pressures before significant wetting phase displacement can take place. There is a remarkable similarity between the shape of the capillary pressure curve calculated by Purcell and those measured by Welge. It is the purpose of this Note to show that, because Purcell neglected to account for the behavior of the residual wetting phase saturation, his system was not in equilibrium during imbibition; and, furthermore, that if his system had been in equilibrium, negative capillary pressures would not have been possible. In Purcell's pore system, the residual wetting phase will form pendular rings at the interstitial spaces existing somewhere within the system, for example, such as those spaces between "doughnuts" as shown in Fig. 1. The true capillary pressure is that across the pendular ring interface, and for the system to be in equilibrium the pressure drop across all interfaces must be the same, including that across the interface in the tight pores A of diaphragm B (Fig. 1). As the pressure across the cell is reduced, the advancing interface will move into the pore from the diaphragm, but at each pressure, the curvature of the pendular rings must be the same as that of the advancing interface if equilibrium is to prevail. Since equilibrium conditions are the basis for the entire argument, it follows that pendular rings must grow as wetting phase enters the pore, that is, as the pressure across the cell is lowered. In Purcell's calculated curve, the residual wetting phase saturation remains constant as the capillary pressure decreases. Thus, his curve does not represent an equilibrium process.

Jan 1, 1953

By George H. Ashley

At the beginning of the war, about 13 years ago, a conference was called in Washington to lay plans for pooling the coals of the United States. A careful review of the various systems of classification then extant showed none well adapted to the needs of coal pooling. The system of Tidewater pools then adopted, using numbers to distinguish one pool from another, was based on typical coals of different localities. At that time, the writer undertook the preparation of such a practical classification. Aside from drawing on his experience of over 20 years in the coal fields of the United States, reaching from the Pacific Coast and the Rio Grande to Rhode Island, he first examined and carded all of the large collection of coals in glass jars made by and for M. R. Campbell. Next, he carded all of the descriptions of coals he could find in the U. S. Geological Survey bulletins and elsewhere, as well as practical tests of coals by the Navy and other organizations and then took account of every published coal analysis of the U. S. Geological Survey and U. S. Bureau of Mines. A study of this information, involving thousands of recomputations, led to the presentation of a paper on "A Use Classification of Coal" before this Institute at the Chicago meeting, September, 1919. That classification was unique (1) in a classification based on "standard coal" which included moisture, but used standardized ash, sulfur and nitrogen, (2) in using physical properties to distinguish the major classes or orders, (3) in recognizing British thermal unit values in the minor subdivision, (4) in the large number of classes recognized (thirty-six), (5) in proposing mineral names for all classes, (6) in proposing a letter code for the several classes for practical use, (7) in proposing a code for expressing what has commonly been called "grade" of the coal, the grade code to be combined with the rank code to designate and describe a coal. The writer still thinks that the principles then offered, though not necessarily the exact proposals, are valid and desirable in any practical classification. The actual classification of coal by rank was based on the ratio of fixed carbon to volatile matter for the high-rank coals—the well-known

Jan 1, 1930

By Rossiter W. Raymond

THE lead-mining industry of Missouri, as of other parts of the Mississippi basin, appears to have been paralyzed by the shock of competition with the mines of the States and Territories further west. It is difficult for establishments working galena ores, too poor in silver to pay for extracting it, to compete with the producers of the argentiferous carbonates of Utah and Colorado, who look upon their lead as a byproduct of little value, and are satisfied if it pays the charges of transportation, or the loss in smelting for silver. But simultaneously with this depression in the lead-mining of the Mississippi States, the development of new zinc deposits has caused a notable revival in the mining of zinc ores. There has recently been a sudden and strong rise in the price of spelter, which, though probably to a large extent temporary in character, has given important encouragement to prospectors and miners. Apart from the general recovery of business in the United States from the prostration of the past six years, the cause of the advance in spelter has been the falling off in production, resulting from the shutting down of several leading Western works,-the Martindale and Carondelet works, at St. Louis, and the Consolidated Company in Kansas. At the same time, the principal works at La Salle, Ill., were undergoing repairs, and produced less than usual, while the sheet-mill of Matthieson & Hegeler, at that place, was running as usual; so that this concern, ordinarily a large producer, entered the already depleted market as a buyer. These causes are in their nature transitory, and it is quite likely that spelter will be superabundant in a few months. Having lately received from a well-informed Missouri corres¬pondent some samples of the zinc ores and a general account of the ore deposits of Southwest Missouri, I have thought that it might interest the Institute to examine these specimens, and to hear such brief statements concerning the region as I am able, upon good authority, though without the aid of any personal investigation on the spot, to give. The zinc-bearing territory in Southwest Missouri appears to be very extensive; that is to say, zinc ores have been mined during the last year at various points throughout a district extending from the eastern edge of Kansas, west of Joplin, to a line some 50 miles east

Jan 1, 1880

By E. T. Dumble

In continuation of the geological work begun in Sonora, Mexico, a partial account of which has already been given in the Transactions of the Institute,* a similar reconnaissance was made of Cochise county, Arizona, and a part of the Whetstone mountains. The investigation resulted in the identification of beds of similar age and character to those of the Sonora region, and in the discovery of interesting deposits, which, so far as I call ascertain from the literature at my command, have not been described heretofore. Route.—Starting from Nogales, we followed the railroad to Crittenden, and then drove to the southeastern slope of the Whetstones. After a brief examination of some reported coalbeds we continued our route, following the wagon-road between the Whetstones and the Mustang mountains to Huachuca, and eastward to Tombstone. Crossing the Dragoon mountains at South Pass, we traveled south and west by way of Turquoise and Antelope Spring into the road from Tombstone to Bisbee. Our route over the Mule mountains lay through Mule Pass and Bisbee, where we stopped a day or two. Thence, crossing Sulphur Spring valley, we drove around the southern end of the Swisshelms, and N. through the valley between these mountains and the Chiricahuas, to White river. From that point our way led through Rucker canon into the San Simon valley, then northward along the eastern face of the Chiricahuas, and by way of Fort Bowie to Willcox, Arizona, from which place we returned to Nogales. It was greatly regretted that the extremely wet weather prevented us from including in our examination the Huachuca

Jan 1, 1902

By Milo Krejci

(Butte Meeting, August, 1913.) THE plant and quarries of the Inland Portland Cement Co. are located at Metaline Falls, Wash., about 128 miles north of Spokane, on the Pend Oreille river, and within 10 miles of the Canadian border. The plant is one of a chain of cement plants controlled by the Lehigh Portland Cement Co., of Allentown, Pa. Work on this plant was commenced in June, 1910, and was completed in April, 1911, but on account of some delays in 'the construction of the power plant, the works were not put into operation until August, 1911. Since then it has been in continuous operation and has furnished the Inland Empire with a high grade of cement. Fig. I is a view and Fig. 2 is a plan of the works. Water Power Development.-The source of the water supply for the hydro-electric plant of the Inland Portland Cement Co. is Sullivan lake, a body of water approximately 5.5 miles long and 0.5 mile wide, situated in the Kaniksu Forest Reserve. A wooden crib dam was installed so as to raise the elevation of the lake 25 ft., and the additional storage capacity was taken up by the diversion of Sullivan creek into the lake by means of a wooden flume, 0.25 mile long, 6 by S ft. in cross-section, and a ditch 1,200 ft. long. The water from the lake follows the natural water course to an intermediate storage reservoir, which was created by the construction of an earthen dam. This pond wits used in connection with the saw mill which was installed at this point. Besides the earth dam, there was also built a crib, at the point shown in the sketch map, Fig. 3. This crib dam is 35 ft. high. From this point the excess water follows the natural course of Sullivan creek to the Pend Oreille river.

Jan 7, 1913

By Sydney H. Loram

TEIS paper, which is merely an arrangement of data collected during several hurried journeys, is offered to serve as a record, until such time as a better substitute be compiled. My observations were confined, as far as possible, over the entire distance, to the actual river valley; because near the Central Cordillera the country is so mountainous as to be im; passable in any direction but that of the dominant valleys. The river is not navigable anywhere, and for the first part of its course is a mountain torrent that runs down the bottom of narrow, almost vertical-sided valleys, through which the only road requires repeated fording, and often following up the bed of the stream ; but the rock-walls, standing clean and free from debris on either side, present the different formations with remarkable distinctness. A topographical map and a cross-seetion of the Rio Huasco is given in Fig. 1. The Rio Huasco practically rises from Laguna Grande, a lake about 17 km. from the Argentine boundary, and 3,135 m. above se-level, which is fed by direct snow-water, and by a few streams varying from a considerable volume, when supplied by the melting snow, in late spring, to little or nothing during the rest of the year. It is a somewhat pear-shaped body of water, about 1.5 miles in length and half a mile in average width, with a reported maximum depth of 45 meters. It was formed by the choking up of a narrow continuation of the same valley with blocks of an agglomerate mentioned later. The present level is some 5 m. below high-water mark (to which point, according to local accounts, it has not been filled for 35 years). In the intervening margin is a calcareous deposit about 4 m. thick, formed by the rapid evaporation of the water in the exceedingly dry air, and aided by the capillary action of an aquatic plant, growing in thick masses around the edge of the lake. These masses, dying and banking up, form

Jan 1, 1905

By Oswald J. Heinrich

IN this paper I shall attempt a description of the successful extraction of coal from this property after it had been on fire for probably fifty years, or more, and after attempts, made at various times, which had still left considerable coal behind. The Richmond coal-field has a well-founded bad reputation, arising from the circumstance that many of its collieries have had to be abandoned, from time to time, if not entirely, on account of fires, caused by spontaneous combustion, to which the character of the coal in this field renders them peculiarly liable. While I fully assent to the opinion that this trouble lies in the nature of the coal, which is highly bituminous, and the seams of which are, moreover, divided by slaty bands, through which, as also in the coal, iron pyrites is more or less disseminated, often in microscopically small particles, I must, nevertheless, declare that many lamentable disasters, causing great loss of life and property, could have been avoided if a suitable system of mining had been pursued in all the collieries. If this could not have been done from the beginning of mining in this section of country (the history of which can be traced back to over one hundred years), at least experience enough existed upon this subject thirty and forty years ago to dictate the avoidance of the dangers to a considerable extent. It is therefore necessary here to refer first, in a few remarks, to the character of the coal deposits, particularly in this immediate neighborhood, the Midlothian being one of the oldest and most extensive mines, and some of its coal being much subjected to spontaneous combustion. I must also refer to the history of former managements to explain more clearly the results which were arrived at. The Midlothian coal-mine property, situated upon the eastern outcrop of the basin, about four miles south from James River, exhibits

Jan 1, 1873

By Clinton M. Ball

Magnetic iron-ore is found in many localities throughout this and other countries, in large bodies and in convenient proximity to other materials required for its conversion into iron and steel; and these bodies of ore would have great commercial value on account of their nearness to consuming markets if they were generally suitable in their natural state for use in the larger operations of steel-making. In the manufacture of iron and steel it has been found, however, that not all ores are equally valuable as sources of raw material for the finished products of furnace, forge and foundry; and, as is now well understood, this is because of the intrusion, in the process of formation of the ore-bodies, of substances which can enter into deleterious combinations with the iron itself, or form compounds associated with the iron oxide which will hinder, if they do not altogether prevent, the production therefrom of the higher grades of finished metal. It is only since the development of the modern method of steel-making by the Bessemer process that the art of the chemist has been called to a critical study of the nature and effect produced by the presence of these pernicious substances in the furnace while the iron is undergoing reduction to the metallic state. Phosphorus and sulphur are the most common and obnoxious elements, and the admixture of one or the other, or both of these, in small percentages and varying proportions, will greatly modify the final results of manufacture. It so happens that generally, although not always, these hurtful elements are found in compounds in the ore which are not magnetic, and this circumstance has led to the expenditure of much ingenuity and money over a long period of time, in attempts to utilize the attractive power of magnets to separate the magnetic oxide of iron out of its crushed ores and from sands, in

Jan 1, 1896

By D Thornton

Geologists use large data sets and spend many hours and much computing time modelling the distribution of minerals throughout a rock mass. Significant investments in drilling, assaying and quality assurance and quality control (QA/QC) are made before sophisticated geostatistical techniques are applied to the collected data. A large amount of research has been done in this field such that the ore control model is a reasonably accurate reflection of the mineral that is actually in the ground. However, after all this effort, the mining engineers then work just as diligently to blast the in situ rock mass to a particle size that can be efficiently handled and further reduced by downstream comminution processes. In open cut mines, this invariably requires large amounts of explosive energy that displaces the ore boundaries from where the geologists originally defined them. Failure to accurately account for blast movement will result in misclassification, whether that is ore to waste; low grade to high grade; sulfide to oxide; or other contaminates û collectively referred to as ore loss and dilution. The financial consequence of getting this wrong is substantial and not well quantified. This diminishes all of the good geological QA/QC done in defining the ore. This paper discusses various technologies used to physically measure blast-induced orebody movement and the difficulties in modelling this with a purely theoretical approach. Rock mass structure, blast energy, design and timing contours all have significant and interrelated effects on blast movement vectors. Measured blast movement has a large variance due to the uncertainly of many of the controlling parameters û arguably dominated by the heterogeneous nature of the rock mass. Although there have been significant advances in blast movement modelling capability in recent years, this unpredictable blast movement limits their use in the context of production ore control. Certainly, without physical field measurements, accurate predictions of movement are near impossible.Limitations of traditional surface markers in determining three-dimensional (3D) blast movement within the orebody are also reviewed, and advancements in accurately measuring these vectors within blasted ore discussed

Sep 26, 2011

By George A. Laird

THIs old and once famous district played, through its enormous production of silver and gold, an important part in the history of the State of San Luis Potosi. According to a pamphlet prepared under the direction of the Governor of the State, Sr. Don Blas Escontria, and presented to the visiting members of the Institute during the Mexican meeting of 1901, this district is situated 20 km. east of the city of San Luis Potosi, in a range of mountains of moderate height, extending 135 km. N. and S., and 16 km. E. and W.; and the mineralized area hitherto developed is about 600,000 sq. m. The history of the district, as given by the record dated 1778, and formerly kept in the Sail Francisco convent, says that it was discovered in 1575 by Sr. Don Pedro Irarte, and adds that the city of San Luis Rey de Francisco de1 Potosi received its name (in allusion to the famous Potosi mines in Bolivia) by reason of the remarkable productiveness of its gold- and silver-mines in the first period of their exploration, during which they paid to the Crown, as quintos (the fifth part of the product), $97,000,000, as appears from the accounts of the royal treasury. The amount of the quintos paid during the " bonanza period " of 80 years was $72,000,000. The larger sum first mentioned probably represents a longer series of years. But either will suffice to indicate the great wealth of the mines. In 1663, the decadence of the industry began with the caving-in of several mines, concerning which the record of 1778, already cited, says, in substance, that on Good Friday one of the owners in the enterprise, in view of the unfavorable prospect of a lawsuit in which he was engaged, set fire to the timbers supporting the underground galleries and workings of the Sail

Jan 1, 1905

By A. Lane

The socio economic risks of mining in South Africa have been emerging for some time now, and have been brought into sharp relief by recent events in the platinum sector. The slow pace of social upliftment in the country has lead to widespread social unrest with consequent calls for different forms of resource nationalism. Fundamentally, the key stakeholders are not fully aligned, and are not engaging productively. This poses significant above-the-ground risk to mining companies. Measuring social impact, deploying inclusive solutions and engaging effectively with stakeholders are three ways in which mining companies can mitigate this risk.

Jan 1, 2013

By Mark R. Lamb

The treatment of slime is of special interest to those engaged in cyaniding gold- and silver-ores. The usual practice is to make as small a percentage of slime as possible. In many instances the slime is given no treatment, but is impounded in dams in the hope that the future will develop some method of economically treating this product. The filter-press was the first step upward from ordinary decantation, but, on account of heavy labor-charge and high cost, its use has been limited to high-grade material. The slime at the Combination mill at Goldfield averages perhaps $20 per ton, and although the values are quickly dis solved the filter-press installation was not entirely satisfactory, resulting in the erection of the canvas-cell filter, developed by Chas. Butters and his staff. This filter is a great improvement over the filter-press, and the following description of it will be of interest to those engaged in treating slime produced in crushing ores, especially in view of the fact that, by the use of this filter, slime can be treated at a lesser cost and with a higher percentage of gold- or silver-extraction than in the ordinary treatment of sand; and, moreover, the initial outlay for an all-sliming plant is less than that for the ordinary sand- and slime-plant. The economy of construction of the Butters filter-plant is clearly shown in Figs. 1 and 2, which illustrate the 20-frame filter of 40 tons capacity, now being installed by the Nevada Goldfield Reduction Co. In this construction the slime-pump is so connected that it call pump to or from either tank or the filter by changing the valve-settinga—a combination which is necessary in this particular installation, since sufficient fall is not available for filling and discharging the filter by gravity. Ordinarily, a slime-plant comprises: a filter-box with frames

Jan 1, 1908