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By David A. Summers

In May 1975 the U. S. Bureau of Mines contracted with the University of Missouri-Rolla, Rock Mechanics and Explosives Research Center to develop a Hydrominer modification to a long-wall shearer unit, wherein the rotating pick-laced drums and connecting gear drives are replaced by a water jet cutting head.1 The concept of the water jet cutting head is based on using the high localized energy of the water jets to isolate a slice of coal by cutting a slot under, at the back of, and at the top of the web. The plow blade of the head then advances into the cut and wedges the pillar over onto the conveyor (Figure 1). There were several potential advantages foreseen for the system of which perhaps the most significant were the elimination of coal dust from the working area2 and the ability, with a variation in nozzle geometry, to cut webs of greater depth with a small increase in equipment horsepower. The University initially designed the head, based on experiments carried out in the laboratory, under an earlier Bureau of mines contract. The experiments showed that it was more advantageous to work at a pressure of 10,000 psi with an estimated flow rate of 50 gpm than go to the higher pressures and lower flow rates which have been advocated elsewhere.

Jan 1, 1977

"En 1953, se habilita la nueva planta de flotación de cobre en Paragsha, donde el funcionamiento de las soleras tipo Lorain y la producción del mineral pirita lograron buenos resultados. Empero las nuevas condiciones de proceso, limitaron su funcionamiento y costo. Por tal motivo, el objetivo del trabajo se basa en la construcción de una solera de mayor rendimiento y menor costo, modificando su diseño al de una honda contínua. El primer juego de este diseño fue instalado en el molino de cobre Nº 1, sin aún obtener el dato final sobre su rendimiento. Posteriormente se consideró la solera AMSCO, dado que el diseño fue más eficiente y el costo final por tonelada fue menor. Sin embargo, se encontró que el contorno del valle era muy cerrado y las bolas N°4 se alojaban de modo ajustado, formando una solera muy gruesa. En consecuencia, se construyó otro diseño denominada ""Solera de onda abierta contínua"", el cual fue instalado en el molino de cobre N°7, donde la capacidad de molienda es igual de óptima y los costos son menores. Así, se pensó que la solera de una sola honda, es mejor que la de onda contínua puesto que este diseño tiene una sola honda en el centro de cada plancha de la solera. Luego, se diseño un tercer diseño, donde el promedio de vida era mejor. Por ello, de los tres diseños a seleccionar -la solera Lorain con 10 hondas, la solera de una honda con 20 hondas y la solera de honda continua de 30 hondas -, la última demostró ser la más eficiente. De otro lado, se probaron otros diseños de honda contínua con distintas aleaciones como el ""Nihard"", cuyo promedio de vida es entre 14 y15 meses aproximadamente, con el tonelaje actual de aproximadamente 270 000. Concluyendo que la experiencia anterior con solerasNihard en molinos a rodillos de 4 pies de diámetro, el impacto es mayor, obteniéndose en quebrantamiento de soleras a 3/4 grosor, pero que pese a esto, resulta ser superior a cualquier otra solera usada actualmente y en eñ que Paragsha esté 100% con soleras de molinos Nihard, a excepción de las rejillas dada su fragilidad. "

Jul 20, 1957

La influencia de los estudios de adsorción para el beneficio de los minerales, se relaciona con la flotabilidad de las especies minerales, y la perspectiva que se ofrece para el progreso de la metalurgia de concentración. Por ello, el objeto de la investigación se basa en la realización de tales experimentos como búsqueda del dominio de la clase de fenómenos fisico-químicos. Dentro de los métodos usuales de determinación de xantatos por yodo, se buscó hallar la concentración por medio del descenso de la adsorción, para determinar la máxima cantidad de reactivo y encontrar el más adecuado para el mineral. Empero, se reparó que a mayor concentración de colector, se genera mayor adsorción. Asímismo cuando se añade el xantato sobre el mineral con poca agua, la cantidad de reactivo adsorbida es superior, justificándose la ventaja que en procesos industriales significaría acondicionar después del espesamiento. En cuanto a la adsorción de galena oxidada, se observa que mezclando este mineral con un sulfuro de zinc, disminuye la adsorción. Posteriormente se ve cómo la superficie oxidada de la galena, puede alterarse por medio de reactivos, variando el grado de adsorción para los diferentes reactivos colectores de flotación. Finalmente se infiere que la realización de las pruebas pretenden determinar principalmente cuál es el reactivo más adecuado más adecuado para una galena determinada.

Jul 20, 1957

By E. C. Pechin

THE Lucy furnace, owned by Messrs. Carnegie, Kloman & Co., and located on the Alleghany River, on the outskirts of Pittsburgh, is a splendid modern furnace, 75 feet high, and 20 feet bosh. She had been working well on low grade ores of about 50 per cent., producing daily 68 to 75 tons. There was on stock 500 tons of Republic ore, one of the purest and best of the Lake Superior ores, averaging over 68 per cent. of iron, which had been procured for the purpose of making a trial for Bessemer iron. This was charged by itself, and Mr. Skelding, the founder, reports that he did not succeed in getting a single cast when it came down, before the furnace chilled from the hearth to the top of the boshes, some 25 feet. Every effort was made to save her, without avail, and the disagree-

Jan 1, 1874

By S. Radacina Rusu

The satellite-based global positioning system (GPS) has significantly changed the way site operations are carried out in surface mining. The GPS has impacted safety, productivity, fleet efficiency, and maintenance practices. However, no comparable global localization system exists for underground mines. This paper discusses recent work in the application of ideas from the mobile robotics research community to the problem of real-time vehicle positioning in underground drift networks. Related previous work recently focused on the creation of globally consistent 2D maps of underground environments that possess sufficient detail to be used for underground localization. Our current work entails the development of a GPS-like system for mobile mining equipment, with results given from both laboratory and field experiments.

May 1, 2011

By D. A. Stout

Mr. Chairman and Members of the Rocky Mountain Coal Mining Institute: Your Secretary has asked me to write upon a subject' which is a most interesting one, and which has a very wide scope. In view of the great need for further decreasing costs at its coal mines, the Colorado Fuel and Iron Company began early in 1924 to experiment with methods of mining which had not previously been. tried out at its mines, and which were selected because of the greater possibilities for the concentration of the work, better grouping of workmen, and increased tonnage per workman, with a resultant increased efficiency, better supervision, and lowered costs. Because of the great competition of the day, means and methods must be provided by which fewer mines can be made to produce larger tonnages and at a lower cost. Western physical conditions are such as to make our problems far more complicated and not so easy of solution as compared to many of the eastern fields where conditions are more favorable for the operation of the mines. The dry condition of our Western mines on account of a relatively low humidity, and with additional gaseous conditions, makes the problem still more difficult to solve. A study of new methods was necessary before adoption, and this was particularly true of the method of extracting the coal. Where mechanical means are used, particularly in the coking coal mines of this state, due consideration must be given to the type, and machines or conveyors should not be installed solely on the basis of their performance elsewhere, without the knowledge of local influencing factors. In trying out the newer methods of extraction at our mines, very careful consideration has been given to the question of safety and the adoption of any new methods must provide adequate means of protection to employes, and be approved by' the State Coal Mine Inspector. In any large industry there are a few outstanding operating costs, and usually the leading ones in their order are labor cost, material cost, and power cost. The things which we, hope to accomplish: 1. Reduce labor costs. 2. Reduce material costs. 3. Reduce power costs by the con 4. Reduce the amount of powder used per ton of coal produced. 5. Increase the lump percentage (particularly at the domestic mines). 6. Reduce accidents and annual compensation payment. 7. Reduce haulage costs. 8. Reduce cost for track work. 9. Reduce cost for timber and timbering, and increase the recovery of timber at a considerable additional saving. 10. Reduce the brushing costs. 11. Reduce the amount of rock hauled to the outside. 12. Reduce the cost for drainage. 13. Reduce the cost for ventilating. 14. Reduce cost of inspection and supervision. 15. Reduce the cost for shot firing. 16. Reduction of number of working places. 17. Grouping of men with increased sociability. 18. Increased tonnage per man. 19. Reduction in total number men employed. In the consideration of the methods used and now working successfully, there were three points which were considered outstanding, to make them wholly successful: ventilation, roof control, and transportation. For making the experiments, those mines were selected where conditions

Jan 1, 1925

By A. C. Watts

FOR several years, a mine in Colorado experienced considerable trouble from small fires caused by the blasting of coal. Although a well-known make of permissible powder was used, it was first thought that the powder ignited gas that might be present and that this, in turn, set fire to line brattices or to the coal. Experiments were, therefore, conducted with another make of powder, but the results convinced the superintendent of the mine, Robt. Williams, Jr., that the fires were not caused by the powder but by the high-voltage electric current used for detonating the shots. The mine "makes" gas very freely, giving off from three-fourths to a million cubic feet of methane per 24 hours. The coal is a good grade bituminous of a very free burning quality. Electric shot-firing from the outside after all men and animals were outside had been practiced for a number of years. The shooting circuit was connected with the main power circuit at the mouth of each entry. Shooting circuit switches were mounted in boxes, which were kept locked with the handle of the switch, in open position, showing through the bottom of the box. The door of the box could not be shut and locked when the shooting switch was closed. At the entrance to each room, or working place, a small switch, called the miner's switch, was placed on the shooting line. It was the duty of the miner, when entering his place at the beginning of the shift, to see that this switch was open and that it was kept open until he left the place at the end of the shift to go out of the mine. Grounded return was used for main power lines. The current was 500 volts, direct current, with 100 to 300 amp. The nearest working face was 9600 ft. from the shot-firers' switch outside the mine and the most remote working face was 2 ½ miles. The various working faces were scattered over a wide area between these two points.

Jan 9, 1925

Experiments on High Efficiency Separation of Mixed Plastic Wastes by Vortex-Tube Separator

Sep 13, 2010

By L R. Sousa, M He

Rock burst is common in deep underground excavations and is characterised by a violent ejection of block rocks from excavation walls. It is critical to understand the phenomenon of rock burst and particularly the failure mechanism. Laboratory experiments are one of the ways. For that purpose, a rock burst laboratory test system was developed at the State Key Laboratory for Geomechanics and Deep Underground Engineering at the China University of Mining and Technology, Beijing. A true triaxial test system, designated the Deep Underground Rock Burst Analogue Test Machine, was developed, which can transfer a stress state from three-direction-compression on six surfaces to the compression on five surfaces with one set free. The rock burst experimental system comprises an acquisition of acoustic emission signals, a high-speed recording in order to accurately record the kinetic characteristics of rock fragments ejected during a rock burst event and the possibility of infrared thermography showing the surface temperature of the samples. In this paper, analyses of typical results from rock burst tests are presented with a description of the obtained results. The mechanisms of rock burst are illustrated, and a rock burst classification is proposed based on these laboratory tests. For the control of rock burst, the constant resistance, large deformation (CRLD) bolt or anchor is presented for accommodating the large displacement of surrounding rock masses and absorbing the impact of the sudden release of rock burst while outputting a constant resistant force in response to the external load. The CRLD bolt or anchor has had practical applications in underground mines. Finally, in situ tests performed in a tunnel at Qingshui coalmine, China, are analysed in detail.CITATION:He, M and Sousa, L R, 2014. Experiments on rock burst and its control, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 19–32 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By D. F. Malan, M. Grave, J. A. L. Napier

Previous fundamental research projects have indicated the value of continuous closure measurements in deep tabular excavations for improved support design, hazard assessment and for quantifying the effect of seismicity on stope closure. This paper describes further measurements in a VCR stope to validate some of the earlier findings. Calculation of the closure ratio showed that it is a good measure to identify different ground conditions and possible hazards. This work was supported by numerical modelling results, which showed that the closure ratio is very useful in discriminating the response of different geotechnical environments. Des projets précédents de recherche fondamentale ont démontré la valeur de mesures continues de fermeture dans le cas de profondes excavations tabulaires pour une conception améliorée du soutien, de l’évaluation du danger et pour quantifier l’effet de la séismicité sur l'affaissement du toit d’un chantier d’abattage. Le présent document décrit d’autres mesures dans un chantier d’abattage VCR afin de valider certaines des conclusions précédemment formulées. Le calcul du degré d'affaissement montre qu’il y va de soi d’identifier différentes conditions de sol ainsi que les dangers possibles. Les présents travaux ont été confirmés par des résultats de modélisation numérique, lesquels ont démontré que le taux d'affaissement est très utile quant à discerner la réponse dans des environnements géotechniques différents. Vorherige Forschungsprojekte haben den Wert von kontinuierlichen Setzungsmessungen im tiefen Sudafrikanischen Strebabbau angedeutet, vor allem fur Ausbaudesign und Risikobewertung, als auch fur die quantitative Bestimmungen der seismizitatsabhangigen Setzung. Dieses Referat beschreibt weitere Messungen in einer VCR Grube um fruhere Bestimmungen zu bewerten. Dass errechnete Konvergenzverhaltniss erweiste sich als eine gute Massnahme zur bestimmung von geotechnischen Zonen und moglichen Risiken. Numerische Analyse unterstutzte die vorliegende Arbeit und deutete darauf, dass das Konvergenzverhaltniss sehr brauchbar ist um Verhaltensunterschiede der geotechnischen Zonen zu erproben

Jan 1, 2003

By O. W. Ellis

CERTAIN alloys1 that, as a result of quenching, are retained in the form of homogeneous solid solution are known to increase in hardness and strength on standing at room temperature or on heating at slightly elevated temperatures. Other alloys" that, on rapid cooling, are held in the form of homogeneous solid solution (as, for example, certain steels) behave in like manner on heating to somewhat higher temperatures. The observed increase in the hardness and strength of these alloys, referred to as "aging" or as "secondary hardness," is widely accepted as being occasioned, either in whole or in part, by the precipitation in submicroscopic form of such constituents as were held in supersaturated solid solution as a result of cooling in excess of a certain critical rate. In earlier discussions of the cause of age hardening or secondary hardness, the question of the hardness of the precipitated particles does not appear to have been raised. At present, however, the general opinion appears to be that age hardening and secondary hardness are occasioned by the precipitation of hard particles within the supersaturated solid substance.3 The authors may be wrong in their belief that the last is a prevailing opinion. Nevertheless, it is thought that the following experiments,

Jan 7, 1924

By Restarick C, Jowett A

A cylinder-cyclone system, fitted with a flow control valve between the cylinder and cyclone plus in some tests a variable cyclone spigot, has been used to achieve classifier separations at unusually coarse sizes relative to the diameter of the units used. The method has proved to be useful for low tonnage flows at low pulp density and variable feed rate. The system relies on use of a cylinder unit to reject excess water and fine particles, the amount rejected being adjusted by the flow control valve. The valve also adjusts flow rate and pulp density of feed to the cyclone unit, and can be adjusted to give a separation at a coarse particle size. The system has been used in connection with experiments on the pilot plant at Mount Isa, where a 76 mm system was used to classify feed to the lead secondary rougher circuit at sizes as coarse as 52 micrametres galena equivalent for split conditioning tests. Further tests have been carried out with quartz to assess the range of size separations Possible.

Jan 1, 1978

By Krzystanek Z, Wasilewski S

The problem of automatic control of a coal mine ventilation network is discussed. It is found that the structure of the control sys-tem should have two levels, i.e. local regulation of ventilation para-meters (air flows) in faces to eliminate the effect of quick disturba-noes, and supervisory control of the whole ventilation process by pe-riodical modifications to the working characteristics of the main fans. Practical and theoretical problems connected with implementation of the system in Polish mining are listed and discussed. To solve these prob-lems a series of experiments with air flow control in three different coal faces were carried-out with the aim of checking the measuring and control equipment in a real mine conditions as well as investigatingthe gasodynamics of the ventilation process. The results of the experi-ments are analysdd, and used to verify the mathematical model of the gasodynamics of a longwall face.

Jan 1, 1985

By John Birkinbine

IN the spring of 1878 the Pine Grove Furnace, located in Cumberland County, Pa., was blown in after lying idle for several years. The furnace was constructed in 1770, and for over a century it has been in almost continual operation. The plant consisted in 1877, when the writer was first called there, of a stone stack 32 feet in height, inclosing a shaft and boshes, the latter being 8 feet in diameter. The blast was supplied by two wooden blowing-tubs discharging into a third, having a floating piston sustaining a box weighted to give the desired pressure, the power being furnished by a waterwheel. A small 18-pipe hot-blast stove heated the blast. The furnace was remodelled during the winter of '77-78, and a Weimer blowing-engine with a blowing-tub 5 feet in diameter and 2 feet stroke, and the necessary boilers, were substituted for the wooden tubs and water-wheel. The stack was raised and enlarged, and provided with a bell and hopper having a central drop. Water dam and tymp were added, and general repairs were made. The hot oven, however, was riot increased. The furnace had always been operated with charcoal as fuel, and its reconstruction was made with a view to continue the use of charcoal, but provision was made for ample blowing capacity should other fuels at any time be employed. Although liberal arrangements had been made in cutting wood, the stock of charcoal supplied in 1878 was insufficient for the increased requirements of the remodelled plant, and notwithstanding the purchase of some 80,000 bushels from an adjacent idle furnace, there was riot enough to keep the furnace in constant blast until a new supply could be obtained, particularly as the season was unusually backward. Instead of following the established precedent of many charcoal furnace managers, i. e., blow out every February, it was determined to continue in blast, using coke as fuel. Accordingly, when the charcoal stock was exhausted, on March 22d, 1879, Connellsville coke was substituted, the change of fuel being made at once; that is, the coke charges followed immediately upon the last charcoal charges. After working a few days,-the strike in the Connellsville coke region cut off the supply, and anthracite coal was obtained, a mixture of the two fuels being employed. The strike continuing,

Jan 1, 1880

By P. W. George

THE rapid increase in cost of discovering new orebodies by churn drilling in the Tri-State district has led to some attempts to lessen the expense by using geophysical methods. Electrical prospecting was tried three or four years ago, but no successful results were recorded. In 1926, the Federal Mining and Smelting Co. engaged the North American Exploration Co., of Houston, Texas, to make some tests with the torsion, balance. At first, it was thought that the most favorable conditions for discovery of ore deposits with the torsion balance would be in locations where the ore was known to occur at rather shallow depths, FIG. 1.-CROSS-SECTION OF DUENWEG LEASE. therefore the first trial was made at Duenweg, east of Joplin, where some zinc ore had been developed at a depth of 130 ft. The gravity gradients at 61 stations on a tract of about seventeen acres indicated plainly one large zone of maximum gravity and a smaller narrow zone of minimum gravity. Fourteen churn-drill holes, half of which struck .ore, show that all the ore found was located outside the zones of maximum and minimum gravity. In the zone of maximum, gravity the limestone beds were closest to the surface, and the first chert beds encountered were at the greatest depth. The results (shown in Table 1) indicated that the gravity of the limestone was greater than the gravity of the fractured chert together with its orebodies, and probably also greater than the bouldery soil and clay on top of the limestone. A cross-section of the Duenweg lease is shown in Fig. 1.

Jan 1, 1928

By A. F. Taggart

THE following notes represent significant excerpts from a mass of records of experimental work done in the ore-dressing laboratory at the Columbia School of Mines during the years 1926 to 1928-inclusive. CLASSIFICATION OF EXPERIMENTAL WORK The experiments performed may be grouped for purposes of description under the following general -headings: I. Collecting agents. a. A method for quantifying collecting effect. b. Coating with undissolved collecting agents (oils) c. Action of dissolved collecting agents. II. Frothing agents. a. A method for quantifying frothing effect. b. Relation between frothing effect and chemical composition. III. Inorganic reagents. a. Methods of studying the effects of these reagents. b. Effect on slime dispersion. c. Effect on sulfides. SUMMARY OF THE ORIGINS OF PRESENT-DAY FLOTATION PRACTICE The first practicable, foolproof method of froth flotation was described in U. S. patent 835120, issued in 1906 to Sulman, Picard and Ballot, and in the equivalent patents in other countries. A number of less simple methods of producing the same result had been described previously in patent publications and otherwise.1 The reagents specified in all of these early patents were "oils" and, in addition, some inorganic substance, usually an acid. The quantities of reagents recommended and added were enormous when' compared with those used today.

Jan 1, 1929

By B. E. Davis, D. A. Stanley, C. E. Jordan

A prototype expert advisor was developed by the U.S. Bureau of Mines to systematically offer advice on the control of a Florida phosphate operation. The PC based system receives input from remote sensors for circuit parameters such as feed rate, reagent addition, and pH and from operator entered information such as the quality of the concentrate and tailings in each of the coarse, fine, and amine flotation circuits. The computer evaluates the information using rules obtained from industry representatives and Bureau flotation experts. Recommended actions and questions are displayed to quickly guide the operator to a problem within the flotation circuit and suggest a solution. This process control system could provide more uniformity among the flotation operators and also serve as a trainer for new operators. In addition, it represents a step toward fully automated systems for phosphate flotation.

Jan 1, 1990

By Green S, McKernan, Skrypniuk

In November 1996, Boddington Gold Mine (BGM) began the implementation of an expert system. The objective of the expert system was to improve plant efficiency by developing an `operator best practice' control philosophy for the grinding circuit

Jan 1, 1997

By M. Valdebenito, J. Rajala

An OCS Expert control system was implemented by Svedala Cisa at the Minera Maricunga Refugio Crush-Leach Operation near Copiapo, Chile. The purpose of the Expert system was to maximize production through the primary and secondary crushing circuits and help balance crusher usage between each stage to maximize total plant production. Interesting aspects of the control strategies are discussed. Benefits of the control were verified through a randomized On/Off test program. Tonnage increases ranged from 5% to approximately 20% at good confidence intervals. Benefits analysis results are discussed. The crushing plant at Refugio is very remote and is located at approximately 15,500 ft. This poses many challenges. The effect of altitude and remote location on plant operation are discussed.

Jan 1, 2002

By W. I. van Drunick

AngloGold Ashanti Metallurgy has recently been involved in the successful installation of intelligent, expert control systems on the milling circuits. The benefits of expert systems in these highly interactive circuits are obvious. Existing comminution tools, which have been developed and can now be incorporated into online control, include improved modelling techniques and understanding, robust and competent simulation methods, sampling techniques, and optimization methods. The minerals processing industry has seen the benefits of predominantly research-based centres turning their focus to commercial applications of comminution circuit modelling packages, which in turn can be utilized within expert control systems. Expert mill control has been successfully installed at AngloGold Ashanti South Africa?s Mponeng and Kopanang Gold Plants. Expert control has also been installed at AngloGold Ashanti?s West African Sadiola Mine operation. The implementation of the systems has produced a number of positive outcomes. Plant surveys usually result in the identification of sub-optimal areas, and the control philosophy is then configured to ensure that these areas (along with the entire circuit) are optimized and maintained. Outdated PID loops have generally resulted in oscillatory control with large amplitude deviations from set-point. Significant improvements in SAR Metallurgy operations have been realized, firstly through achieving stability in the load and cyclone control, and secondly through online identification and implementation of optimized set-point conditions for mill mass, discharge density, etc. Soft sensors are configured to accurately estimate parameters that were historically not measurable, viz. breakage rate, mill load condition, onlinekWh/t-75 microns, mill discharge density and cyclone overflow grading. The Mponeng Plant system achieved circuit stability and improved overall grind. The Plant was able to pay back the control installation after 3 months, based on the additional recovery obtained from the finer grind. The system at Kopanang Plant has also resulted in enhanced plant recovery as a result of a finer grind and a lower residue gold content. The payback for this system was calculated at approximately 6 months. AngloGold Ashanti Metallurgy is currently expanding the installation of expert control to its other operations. It is also evaluating the performance of various suppliers of advanced control systems.

Jan 1, 2005