Search Documents

The Golden Cross Mine will be the first underground gold mine in New Zealand to operate since 1952. The development plans, along with the conditions and circumstances presently found in the now ongoing mine development, will be discussed as well as a brief review of planned stoping activity and stoping results to date.

Jan 1, 1991

By Catherine T. Aimone

A computerized cost model has been developed to simulate the technical and economic effects of strip mine blasting in the vicinity of structures. Current surface mining regulations restrict the allowable level of production blasting as a function of this distance. Blast design modifications,' therefore must be employed when blasting in the vicinity of homes to ensure compliance with federal and state regulations specifying limits to the seismic effects generated from a blast. The blasting level allowed. is computed by the charge weight of explosives per delay from the following scaled distance formula: [ ] where W is the charge weight per delay, in kilograms (pounds), D is the distance factor corresponding to the regulatory limit of peak particle velocity to which a structure may be subjected to. Current regulations specify 2.54 cm (1.0 in.) per second corresponding to a SD factor of 27 (60) (Federal Register, 1977).

Jan 1, 1982

By Will H. Coghill, P. H. Delano, G. D. Coe

Data concerning the actual net energy required for pulverizing coal are lacking from the literature on coal pulverization. Power data given in the literature concern gross power and frequently include the power expended on the air blast or product-conveyor system, as well as power lost through friction in the pulverizer itself. Consequently, such data supply no information regarding the net energy consumed in pulverizing or the relative grinding resistance of various coals. In the study of coal pulverizing much work has been done on what is known as " grindability-index numbers," but grind-ability tests have seldom considered the energy input (that is, the "cause" part of the system "cause and effect"). There are many records of the effect, but even these have questionable value because the "grindability" tests did not make a pull'erized product by a method comparabLe with- commercial pulverizers. In many of the tests, only a selected part of the coal was ground, and the remainder continued to be an unknown factor. Furthermore, none of the grindability tests provide the balanced circulating load common to all modern commercial pulverizing. In order to obtain better understanding of the fundamental principles of coal pulvcrizing, the Bureau of Mines is investigating the "cause" phase; that is, the net energy input or net power excluding friction between the moving parts of the machine. As a first step in the investigation,it was necessary to design and construct a laboratory machine in which no friction-loss corrections are involved, which could grind and finish a minus-¾-inch feed, which could be emptied rapidly and completely, which could operate with a continuous feed and finish in an air separator; and, most essential of all, which would be equipped with a measuring device for recording only that portion of the total power consumed in actual pulverizing, hereafter referred to as "net energy input" or "net horsepower-hours." The channel-roller pulverizer hereinafter described is believed to meet these requirements. History oF the Machine The, work started when Ralph W. smith, engineer, St. Genevieve Lime Co., St. Cenevieve, Mo., was appointed one of the consultants of the Bureau of Mines, United States Department of the Interior, in cooperation with the University of Alabama, to develop a machine for testing the abrasiveness of coal. Smith had already developed a machine for testing the abrasive-ness of dentifrices,1 and it was thought the same principles might be applied to coal, Smith's machine had a revolving disk with an annular channel in which the sample was placed. Riding in the channel was a small block or runner of selected soft metal held

Jan 1, 1942

By S T. Jarvis

Colliery spoil is the major constituent of colliery spoil ærockpasteÆ which has been used to infill abandoned limestone mines in the West Midlands of England since the early-1980s. The other constituents of rockpaste are pulverised fuel ash, lime and water. A key property of the rockpaste is its ability to flow within the mine workings over considerable distances before setting. This paper describes the work carried out to identify suitable sites as sources of colliery spoil for making rockpaste and goes onto consider the flow properties of the material and the monitoring methods used on-site. A full-scale trial comprising infilling a 6600 m3 section of an abandoned mine was conducted prior to the infilling of the Littleton Street Mine which had a volume of about 500 000 m3. As well as describing the methods used for monitoring the movement of rockpaste material, a description is also given of a dip-meter developed specifically for the purpose of measuring the level of paste in the mine. This paper shows how a colliery spoil based paste has been successfully used for infilling abandoned mine workings. The monitoring systems developed for use in the two case studies presented in this paper are now being used extensively for infilling other abandoned mine workings. To-date over 11 mines with a total volume exceeding two million cubic metres have been backfilled.

Jan 1, 1998

By D. A. Garland, A. D. Jackson

"Alanx ceramic/metal composites are proprietary products developed by Lanxide Corporation who joined with Alcan to form Alanx Products L.P. in 1988. Alanx ceramic/metal composites are composed of silicon carbide in a combined alumina and metallic aluminum matrix. In laboratory slurry wear tests conducted by Alanx ceramic/metal composites have shown to perform well against other wear resistant materials. At the Kidd Creek Concentrator Alanx CG896 ceramic/metal composite was tested in two pumping applications, the primary cyclone feed pumps and the filter feed pumps. In both instances the wear rates of the parts made of Alanx CG896 were far less than the gum rubber parts traditionally used. As of year to date September 1992 the unit cost to repair primary cyclone pump parts has dropped 58% from 1991 figures. For the filter feed pumps the unit cost to maintain the pumps has dropped by 33% as compared to 1990 figures. The total savings represented by implementation of Alanx wear parts, based on projected year end unit costs for 1992, as compared to 1991 costs for primary cyclone feed pumps and 1990 figures for filter feed pumps, is $166,753. INTRODUCTIONAt the Kidd Creek Concentrator the cost to maintain the primary cyclone feed pumps and the filter feed pumps was a constant concern. Rubber wear part consumption was quite high and the manpower required was considerable. For 1991 the total cost to maintain five primary cyclone pumps was $244,062. The cost to maintain the filter feed pumps in 1990 was $72,076. A wear material was needed that would increase the time between repairs and that would increase the reliability of these pumps between scheduled shut downs."

Jan 1, 1993

By C. D. Wittreich

The results of an engineering study of fiber-reinforced cemented tailings are presented. These tests were conducted to evaluate the potential for using fibers to increase the strength of cemented tailings used as backfill for ground support in the undercut -and - fill mining method in a mine subject to high horizontal stresses and rock bursts. Stress-strain measurements indicate that fibers not only increase the peak compressive tensile and flexural strengths of cemented tailings, but limit reductions in residual strength following failure. Results also show the effect of water content, fiber type, fiber density, and curing time on strength.

Jan 1, 1987

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 Jorgen Elbrond

Before and in the early stages of industrialization, mining was the undisputed leader in technology. It represented the high-tech of the time. Early mechanization bears witness to that. Hoisting and rock breaking driven by waterpower are such examples. The mines' use of the steam engine was a major incentive to its development. By these means new mines could be opened and more metal supplied. Understanding of systems was essential for miners when shaping the infrastructure of the mines for the transportation of ore, material and men and for the evacuation of water and for ventilation. The irrigation systems of ancient mines are such examples. However, with the industrial revolution other more specialized branches of industry advanced further, and the mines became users of other industrial branches technologies. The mining industry had, however, always been quick to recognize a good thing and use it, when time was right. But, compared with other branches of industry, the mining industry has the disadvantage of working in a rugged environment with (and actually inside) a raw material which is abrasive and highly variable with respect to mechanical properties. This determines the rather high unpredictability of mining machines' performances and their low availabilities and explains a part of the delays in introducing technological advances.

Jan 1, 1989

By T. R. Young, S. A. Scott

9.5-1. Introduction. The use of pipelines to transport solids has been successfully accomplished with many different materials. One of the oldest applications is the dredging and placing of hydraulic fill. Many installations have been made and operated for long periods of time with excellent dependability, low operating cost, and low maintenance. It is not the aim of this chapter to give the engineer the answers from which to design a pipeline, but rather to supply helpful information from which to start the project. There are several phases of solids pipelining which as yet have not lent themselves to quick engineering answers. Investigations have been carried on by many, with several theories advanced by the various investigators. In recent years certain notable theoretical advances in hydraulic transportation have been achieved. Vertical transport, using balanced "leg" operation, now appears competitive with other forms of vertical transportation. In addition, horizontal transport utilizing capsules has been proven experimentally to be attractive because of lower pressure drop than the conventional methods of solid transport in fluid media. With the aid of the computer, the laborious calculations associated with pumping calculations have been greatly simplified; and with this tool the pipeline engineers of the future will undoubtedly be able to develop a more comprehensive understanding of solids-fluid transport. 9.5-2. Theory. There have been many excellent studies made and information is available in the literature, but a general comprehensive theory of pipeline transportation of solids has not been advanced. The existing flow theories will give approximations for minimum and optimum flow velocities, friction head losses, energy requirements, and pump and pipe size The principles of dynamic similarity and scaling laws are well understood for the flow of pure liquids. There are no firm methods of scaling slurry pipelines of small diameter to larger diameters except for a few empirical.

Jan 1, 1968

By N. Brown, M. Herman

IT has been pointed out by Cottrell' and Fisher that long-range order would produce superdis-locations, consisting of two partial dislocations separated by an out-of-phase region. The mutual repulsion of the partial dislocations is balanced by the surface tension of the out-of-phase domain boundary joining the dislocations (Fig. 1). The calculation of the equilibrium spacing of the dislocations has yet to be made. The argument uses the Bragg and Williams theory of long-range order." The metal under consideration is the A-B, body-centered type, such as ß brass. The slip system is taken to be [Ill], (110). Since nearest-neighbor interactions are considered, only the atoms position in the two (110) planes adjoining the slip plane have to be labeled. Corner sites are called a and a' in the top and bottom (110) planes, respectively. Similarly ß and ß are the body-centered sites. Thus, a and ß and 0 and a sites are nearest neighbors. Assume that the bottom plane moves and the top plane is fixed during slip; the atoms in a and ß sites exchange sites but atoms in a and ß sites remain fixed. Fraction of A atoms in a sites, for example, is given by fa and fa. for the un-slipped and slipped condition, respectively. Similarly number of A atoms in the a sites is given by n, and n'a for the unslipped and slipped condition, respectively. As the dislocation moves into the ordered region the change in number of A-A bonds is given by

Jan 1, 1957

By Irving Hartmann

The record of safety in the use of permissible explosives in United States coal mines has been excellent, due in great measure to the persistence with which research has been carried on in the Bureau of Mines, to the development of permissible explosives, and to the cooperation of mine operators and workers in using permissibles in a recommended manner and in the effective though gradual replacement of black powder and other nonpermissibles. The demand for increased rate of coal production, changes in mining conditions and minim methods, and introduction of new mining machinery have resulted in modified or new blasting practices. To keep abreast of these developments the Bureau of Mines conducts investigations under actual mining conditions at the Experimental coal mine near Pittsburgh, Pa. Several years ago an extensive study was complete to determine conditions under which the allowable charge limit for permissible explosives per shot hole might be raised from 1.5 to 3 pounds without undue risk of gas or coal-dust ignitions. As a result of the study, this increase in the charge limit was authorized under certain specified conditions in 1948,5/ greatly facilitating production schedules.

Jan 1, 1954

In 1936 the Institute established the Anthony F. Lucas Gold Medal, which will be awarded from time to time "for distinguished achievement in improving the technique and practice of finding and producing petroleum." These awards will be sponsored by the Petroleum Division. Captain Lucas was a pioneer in the oil industry, one of the early wildcatters and a leading mining and petroleum engineer. He was famous as the discoverer of Spindletop. He became a member of the Institute in 1895 and in 1913 was the first Chairman of the Petroleum and Gas Committee of the Institute, the forerunner of the present Petroleum Division. He also headed the Committee in 1914, 1917 and 1918. The first medal was presented at the annual dinner in 1937, Feb. 17, to J. Edgar Pew. The personnel of the Committee on award as appointed in February, 1937, is as follows: John R. Suman, Chairman Until Feb., 1938 Until Feb., 1939 Hallan N. Marsh R. OgaRRio Russell 6. McFarland H. H. Power John R. Suman CaRl A. Young Until Feb., 1940 Until Feb., 1941 W. B. Heroy Joseph Jensen C. V. Millikan John M. Lovejoy J. Edgar Pew Carroll H. WEgemanN Members ex-officio R. C. Allen John W. Finch Axtell J. Byles H. B. FUQUA

Jan 1, 1937

Jan 1, 1962

By E. L. Vickers

Over the years, the pure theorist in economic analysis has accumulated a formidable array of facts in bringing his subject matter under control. Business managers and mining engineers are aware of the theorist's weapons, but the question of applying them to the mastery of practical problems seems hardly feasible, especially in view of the almost innumerable variables plaguing the everyday scene in the mining enterprise. One such sophisticated tool of long-standing in the theorist's arsenal is marginal analysis. Equally long-standing for the operating company and valuation engineer is the problem of defining the cut-off grade the point below which a mineral re- source ceases to be economically amenable to extraction. In other words, what part of a mineralized body of rock is ore and what is waste?

Jan 6, 1961

By J. I. Paige

The Bureau of Mines, U.S. Department of the Interior, conducts research on methods to minimize the requirements for mineral raw materials through conservation, substitution, and increased minerals and metals recovery from primary and secondary domestic resources. To further this goal, prior Bureau research had devised a pyrometallurgical technique (RI 8211) to recover metallic iron and copper from molten copper smelting furnace slags by carbothermic reduction. As a continuation of this Bureau research on the carbon injection technique, reverberatory and electric furnace slags were treated in an 800-kva electric arc furnace by simultaneously top feeding the slag and injecting coke breeze into the bottom of the molten bath. Results of the tests show that 76 to 89 pct of the copper and up to 48 pct of the iron contained in the smelting furnace slag were recovered in a metallic phase, while 56 to 82 pct of the carbon injected into the sys-tem was utilized as the reductant. Laboratory evaluation has shown that the metal product, which contains 86.9 to 95.0 wt-pct iron and 1.3 to 4.1 wt-pct copper, will be a satisfactory medium for recovering copper by cementation. The expected energy consumption for the process is 110 kwhr per ton of molten slag treated and 520 kwhr per ton of solid material charged.

Jan 1, 1982

By Nobuyuki Masuda

In Japan, the municipal solid waste, which amounts to 50 million tons, is generated every year and most of it is incinerated. The fly ash from the municipal waste incineration (the primary fly ash) contains heavy metals, such as lead and zinc, etc., and dioxins. In case of melting, the fly ash from the process (the secondary fly ash) contains high concentration of heavy metals (e.g., Zn; 1-20%, Pb, 1-10%). Metal Mining Agency of Japan launched a four-year project in 1999 to establish the integrated technologies to recover the valuable metals from, and to decontaminate, the primary and secondary fly-ashes in the practical scale by utilizing the existing metallurgical processes and facilities, along with the energy saving. The segregation, flotation and chemical treatment are applied to the treatment of the primary fly ash. The secondary fly ash is treated with MY (Mitsui-type blast furnace) Process after the chlorine removal to recover the heavy metals in the ash, In this paper, the segregation and flotation process for primary fly ash and MF process for secondary fly ash are explained. The main results of experiments done from 1999 to the mid of 2001 to design the pilot plants and to optimize the operating conditions are described. The main results of the experiments are as follows: - The segregation reaction of Cu was confirmed by the experiment on the treatment condition of 800 and 900`C with adding oil cokes and water to the primary fly ash, and 99.98% (toxicity equivalent) of the dioxins were decomposed by the treatment. - Washing tests of secondary fly ash to feed MF resulted that more than 70% of chloride were removed, but still lower than expected, and agglomeration tests were successful by the results of the sufficient strength of briquettes produced though a little more binder for the agglomeration is required than usual operation. - Smelting experiment by downsized MF showed that valuable metals, such as zinc and lead, are recoverable in the furnace dust. Recovery ratios, Zn: 58% and 67%, Pb: 74% and 83%, are accomplished.

Jan 1, 2002

Jan 1, 1942

By Ian S. Leslie

Seismic monitoring systems for mining operations are being utilized more than ever before in the characterization of rock mass response to underground and open pit mining. This paper provides a review of the use of microseismic monitoring for rock mechanics applications at mines throughout the world. Some practical considerations for the installation of these systems are presented along with techniques for optimizing seismic array coverage. Case studies and installation examples are also provided. Recent applications of advanced seismic analysis techniques are discussed including the determination of event mechanisms, mapping of maximum peak particle velocity (PPV) and seismic hazard fields, and the use of source parameter data for large event re-entry protocol.

Jun 1, 2012

By S. Dinescu

The paper deals with the modeling of longwall shearer cutterhead interaction with the coal, in order to study the influence of different limiting factors of the haulage speed, and the cutting regime ensuring optimal energy consumption A computer simulation model is used to draw-up the torque vs haulage speed and the haulage force vs haulage speed dependence diagrams, for different strength of coal and different degrees of bit wear.

Jan 1, 2008

Jan 1, 1887