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By Yoginder P. Chugh, M. Silverman

Premining investigations involve the determination of roof, floor, and coal seam characteristics to delineate areas of troublesome ground control prior to development of a mine. Data obtained can be useful in mine design, equipment selection, estimation of face productivity, development of ground control plans and assessing ground control costs, and in conducting feasibility studies and financial analyses. This paper discusses 1) the causative factors associated with ground instability, 2) how useful data can be obtained for these factors during premining investigations, and 3) analysis techniques to delineate probable areas of ground instability.

Jan 1, 1982

By A. M. Marabini

Flotation of rutile with N-benzoyl-N-phenyl-hydroxylamine (N-BPHA) has been investigated. Initially, floatability tests were performed in a Hallimond tube. The results indicated that rutile was floatable in the pH range from 2 to 4 at N-BPHA concentration between 2x10-3 M and 2x10-2 M. Selectivity against hematite was recognized when operating at pH values below 2. Following the hypothesis of the formation of a surface chelate between N-BPHA and titanium ion, this compound was precipitated from a solution of Ti(SO4) to which N-BPHA was added. I.R. spectrometry oft the rutile before and after treatment with N-BPHA solution confirmed the presence on the rutile surface of the same compound. The absorption isotherm and kinetics were determined by analyzing N-BPHA in solution with an U.V. technique. A hypothesis for the mechanism of adsorption of N-BPHA on rutile is suggested.

Jan 1, 1982

By W. Pariseau, J. Goris, S. R. Dismuke

Ore at the Magmont mine in southeast Missouri is extracted by the room-and-pillar method on two and sometimes three horizons. In 1991, a plan was formulated to recover high-grade ore in pillars using cable halts to accommodate spans of more than 27 m (90 ft ). A test area was selected and a recovery plan developed. A cooperative rock mechanics study was established by Cominco Metals, the US Bureau of Mines and the University of Utah. When initially opened in 1968, the planned production rate was about 910 kt/a (1 million stpy). Due to declining reserves, the production rate was decreased in November 1992 to 570 kt/a (630.000 stpy). Pillar recovery now accounts for about 40% to 50% of the mined tonnage. This method plays a vital role in allowing Magmont to continue to operate.

Jan 1, 1996

By R. J. Sterrett

To the average mine operator, the implementation of environmental regulations are viewed as a drain on the profitability of the mine. Since the birth of environmental awareness in the late 1960's, which led to the passage of the National Environmental Policy Act (NEPA) in 1969, and through the publicity brought about by the discovery of Love Canal in 1978, the public are clamoring for increased environmental protection. It should be emphasized that the concern regarding the issues of the handling and disposal of nuclear and toxic wastes is not limited to a few overzealous environmental advocates. Toxic waste issues have "grass roots" interest and support. A reflection of this support has been the passage of key pieces of federal legislation. . Of particular interest are the following acts: Clean Water, Toxic Substances Control, Surface Mine Land Reclamation, the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). The last act is often referred to as "Superfund". Both RCRA and CERCLA have been re-authorized and amended, and in their re-authorization they have been substantially strengthened. Of the last two pieces of legislation, RCRA is the most powerful in that it governs the handling of hazardous wastes from "birth to grave". CERCLA was established to cleanup abandoned waste sites which are threatening human health or the environment. These cleanups can be undertaken by the government and then billed back to the previous owners or to the disposers at the sites.

Jan 1, 1988

By Keith Bowers, Frank Mimnagh, Eddie Woods

The CTRL London Tunnels The Channel Tunnel Rail Link (CTRL) London Tunnels comprise 36km of internal diameter bores that were driven by Earth Pressure Balance (EPB) Tunnel Boring Machines (TBMs). The tunnels were constructed between the autumn of 2002 and the spring of 2004. The permanent works also included the 1.1 km long station box at Stratford, five ventilation shafts of depths between 30 and 54 m, 29 cross passages and various large diameter sprayed concrete lined connecting tunnels. The tunnels were driven under densely populated areas of north and east London, as depicted in Figures 1 to 4. Under the parliamentary CTRL Act the project had obligations to make

Jan 1, 2005

By J. Mark Richardson, Mary S. Sredanovic

The use of computerized steady-state process design balance systems has reduced engineering man-hours by as much as 80 to 1 over conventional manual balance calculations. The popularity and widespread use of such systems by the minerals industry increased dramatically in recent years, but these systems were mainly available for use on large main frame computers and lacked graphic capability. A considerable amount of engineering manpower was required to "conceptualize" a process flowsheet. After sketching the flowsheet layout, the engineer was still faced in most cases with a time-consuming reduction of his graphic concept of the problem to numerical data required by the balance program. Furthermore, output from these early systems was usually in tabular numeric form. The computer results then were transferred manually to a pictorial representation of the process. A new process design balance system has been developed which runs on a popular and inexpensive personal computer. This system combines modern Computer Aided Design (CAD) principles and the graphics capabilities of the personal computer to allow the process engineer to define a flowsheet problem while creating a process flow diagram. The system provides balance results in both pictorial and tabular form. Past, present, and potential applications of the system are discussed, and an analysis of the cost benefits derived from its use are provided.

Jan 1, 1985

By Alexander Sutulov

It is calculated that since the beginning of last century, which practically coincides with the beginning of the Industrial Revolution, our civilization has consumed around 239.5 million tons of copper (see: Table 1). According to the most pessimistic projections of today, with only a 2.5% annual growth rate in demand, we are bound until the end of this century to consume another 200 million tons of copper in remaining 17 years. A recent study made by US Bureau of Mines (1) indicates that the proven ore reserves of 150 major operating mines and about 120 deposits sufficiently explored for development and feasibility studies accumulate a total mass of 49.3 billion tons of ore, assaying an average of 0.82% Cu and containing around 324 million tons of recoverable copper. Consequently, there is a high grade of probability that the bulk of our future ore supplies, for our demand of, say, next 25 years will cane precisely from these mines. The interesting point in USBM study is that it indicates the recoverable byproduct content of these ores and which is: 118.2 million troy ounces of gold 2277.4 million troy ounces of silver 7.1 million tons of lead 24.7 million tons of zinc 1.3 million tons of nickel 3.1 million tons of molybdenum 765 thousand tons of cobalt, and 720 thousand troy ounces of platinum. This information gives us a relatively reliable profile of our future ores for next 25 years, and thus makes possible evaluation of byproduct credits in our future copper mining and producing activities.

Jan 1, 1983

By N. P. Titkov

This paper presents the results of laboratory and pilot plant investigations for the development of efficient methods of beneficiating hematite ores from the Krivoi Rog, Kursk Magnetic Anomoly, Olenogorsk, and other localities. The tests included gravity, magnetic (in a high intensity field), flota¬tion, and magnetizing roasting methods. It was possible to develop efficient beneficiation methods depending on the mineral composition of the ore and degree of dissemination of ore and gangue minerals. The paper shows the relationship between the iron silicate and quartz content of the ore and the technologic indices of the various beneficiation methods. Some of the conclusions based on these investigations and the technical and economic computations related to the cost of one ton of pig iron produced from concentrates obtained by the various beneficiation methods are: 1. If the hematite ore is not disseminated uniformly, it is expedient to use a combined gravity and flotation process. Ore particles up to 50 am. in size are beneficiated by gravity (heavy suspension, jigging, and others) and yield a lump concentrate. The middlings from this process are recrushed and floated; 2. Finely disseminated hematite ores, containing small quantities (less than 5 percent) of iron silicates, are most effectively beneficiated by flotation. Anionic (sulphate soap, tall oil emulsion with various foam depressors) as well as cationic collectors may be used. Depending on the mineral and chemical composition of the ore, it is possible to obtain concentrates containing up to 65 percent iron with an extraction up to 94 percent; 3. Finely disseminated, mixed hematite-magnetite ores may be beneficiated by flotation or a magnetic separation-flotation process; 4. Finely disseminated hematite ores, containing large quantities of iron silicates and earthy hematite ores are most efficiently beneficiated by the magnetizing roasting method. This method will yield concentrates containing up to 68 percent iron with extractions up to 90 percent. Although beneficiation by the magnetizing roasting process is costly, it will nonetheless, when employed on this type of ore, yield the least expensive pig iron.

Jan 1, 1960

By S. D. Thompson

An AIME transaction by P.L. Allsman (1960), "Analysis of Explosive Action in Breaking Rock," contains many useful concepts applicable to blast design. Of special interest was the derivation of a heave blasting burden formula, which is important in establishing the maximum burden. Unfortunately, its derivation contains a fundamental error and then a compensating one. This formula was: [ ] The derivation used the impulse-momentum principle, with a 0.3 m thick (1 ft thick) radius of rock mass being acted on by an explosive impulse. However, the rock weight was not converted to mass by dividing by the gravitational constant. This mistake can be verified by checking the units in the formula, which resolve into m%-sec instead of meters. Adding the gravitational constant corrects this: [ ] If the minimum velocity is now taken as 0.3 m/sec (1 ft per sec), as was recommended, excessively large burdens result. Any appropriate rock velocity should be capable of throwing the rock mass a minimum distance so that the swell needed for breakage can occur. Unless the burden is extremely small and the bench height is very high, it is unlikely that a velocity of only 0.3 m/sec (1 ft per sec) will be sufficient. A review of the literature indicates that average rock velocities observed by camera studies typically range from 15 to 30 m/sec (50 to 100 ft per sec) (duPont deNemours and Co., 1977; Tansey, 1979). On this basis, a minimum rock velocity of about 15 m/sec (49 ft per sec) would be expected and not 0.3 m/sec (1 ft per sec). When a velocity of 15 m/sec (49 ft per sec) is inserted into the corrected formula, the results approximate those of the original formula with a velocity of 0.3 m/sec (1 ft per sec). The errors were approximately self-compensating [ ] References Allsman, P.L., 1960, "Analysis of Explosive Action in Breaking Rock," Transactions, AIME, Vol. 217, pp. 475-476. E. I. duPont deNemours and Co., 1977, Blasters' Handbook, 175th Anniversary Edition, Dupont, Wilmington, DE, pp. 233. Tansey, D.O., 1979, "The DuPont Sequential Blasting System," CIM Bulletin, Vol. 72, July, p. 80. Thompson, S.D., 1981, "Critical Review and Revision of Surface Blasting Practice," MS thesis, West Virginia University, pp. 308-316.

Jan 3, 1985

By James F. Kvitkovich, George V. Weisdack

Longwall mining techniques were introduced into U.S. bituminous coal mining operations in the early 1960s. These techniques were gradually adopted by many mines during the 1970s. By 1983, considered to be the peak of the longwall mine census, there were 118 active longwall faces in 79 coal mines throughout the United States. Beginning in 1984, longwall faces began a decline in numbers that has continued to the present day (Fig. 1). The geographic distribution of longwall faces today is shown in Fig.2 according to region. A breakdown of recent longwall mine production by region is shown in Table 1. An approximate breakdown of present longwall face installations by product (metallurgical and steam) is shown in Table 2.

Jan 1, 2005

By W. Edwin Dill

For the mining industry, the Internal Revenue Code and regulations offer a range of choices in arriving at the allowable depletion. Each case is essentially unique. Two prerequisites can optimize these opportunities: communications between the mining company's tax specialists and its technical staff; and an understanding of IRS definitions. For the latter, a logical starting point is consideration of exploration and development, since they precede production and depletion is unallowable prior to production. Criteria for selecting engineering and accounting options for exploration and development indicate the necessity of interaction between these company functions to achieve the most favorable tax position.

Jan 1, 1982

By T. C. Page

The Yarnell gold depoSit, located in the Weaver mining district of Yavapai County, Arizona is found within a structurally controlled, hydrothermally altered zone that occurs within a 1700 Ma granodioritic intrusive. Both potassic and sericitically altered rock that occur around and above the low-angle northeast striking Yarnell fault are known to host economic gold mineralization; a wider envelope of weakly-propylitic alterred rock also occurs in this area. During mineralization, strong sericitization accompanied several stages of quartz ± adularia veining, stockwork formation, and localized silicification and potassic replacement, in association with deposition of specularite, pyrite (now oxidized), and gold. The footwall of the fault is also sericitically altered but poorly mineralized. Mineralization along the Yarnell fault continues both northeast and southwest from the main deposit although the thickness of the zone and associated alteration envelope diminish away from the orebody. A sample of undeformed illite taken from the Yarnell fault zone was K/Ar dated at 69 ± 1.6 Ma; this date reflects a minimum age for both mineralization and latest movement on the fault. Gold mineralization is accompanied by modest increases in Ag, As, Cu, and Mo content. Both CO2-and H20-rich fluid inclusions were studied and suggest mesothermal pressures and temperatures of formation for the deposit.

Jan 1, 1992

By Louis J. Czel

Although lithium was first discovered by Arfwedson in Sweden in 1817, it did not reach any significant status in commercial application until 1908 when Thomas A. Edison received a patent covering the use of lithium hydroxide in alkaline' storage batteries. Edison's achievement can be regarded as a major breakthrough in the development of the lithium industry. In the years prior to 1908 lithium salts had found only modest applications in the pharmaceutical and pyrotechnic fields. The next important milestone in the growth of this net industry occurred in Germany in 1918 when Metallgesellschaft at its metallurgical laboratory at Frankfort-on-Main discovered that the addition of a few hundredths percent of lithium metal to aluminum and its alloys increased-the hardness. This brought into being a new commercial use of lithium in the manufacture of bearing metals. The new material, called "Bahnmetall" (railroad, metal), was widely used for, many years in the manufacture of bearings for railroad and automotive purposes. Its use continued until the early 1930's and there was a short-lived renewal of its production during World War II. Subsequent use of-the alloy was soon outmoded.

Jan 1, 1961

By John C. Brower

Bolivia is nor a major gold producer but has produced continuously since pre Inca times. Production reached a peak in 1964 of about 4,000,000 grams and is currently about 1,000,000 grams. Production is mainly from the Tipuani River valley north of La Paz and is derived from Pleistocene basin fill: the Cangalli conglomerate and overlying terraces. Abandoned Pleistocene lake terraces south of La Paz in the Oruro area are another source of gold whose potential have not been realized. In both the Tipuani and Oruro areas, primitive hand methods are the principal means of production, with the exception of a single modern dredge. In spite of a long history of production, probably very little of the gold potential has been mined.

Jan 1, 1979

By William G. Freeman

As with most industrial minerals, barite is freight sensitive. This paper is given so that others might gain from the experience of barite companies in reducing their transportation costs. Some of the approaches used were unusual and others standard, but by perseverance considerable savings were realized.

Jan 1, 1973

By Fabio Amaya, Andrés Marulanda, Ramiro Gutiérrez, Alberto Marulanda

The behavior of a salt rock mass is strongly related to a creep phenomenon. The amount of creep depends on the level of stress generated in the underground excavation. Additionally, security conditions and the lifespan of an underground cavern excavated under this geological conditions depend on the evolution of creep. Based on the experience of the failure of the Old Underground Salt Cathedral of Zipaquirá(Colombia) and the construction of the new one, the theoretical framework to predict the creep behavior of a salt rock mass is explained. The theoretical formulations are calibrated based on actual observations of the material behavior to predict the lifespan of this striking structure.

Jan 1, 2003

By L. L. Gagné

The Churchill Falls Development will eventually be the largest source of hydroelectric power in North America. Churchill Falls was discovered in 1839, but until recent years it was not practical to begin development of this site to tap the 7 million horsepower available. This $1 billion project is located in Labrador, 700 miles northeast of Montreal and 650 miles northwest of St. Johns, Nfld. The construction will divert the Churchill River 5 miles upstream from the 245 foot Churchill Falls. Rapids above and below the Falls, together with the Falls proper, give a natural head of 1,040 feet. In contrast to the basic simplicity of the surface installations, the powerhouse labyrinth is astounding in size and complexity. The largest in the world, it consists of three major chambers - the powerhouse, 972 feet long by 81 feet wide and 154 feet high; the surge chamber, 763 feet long, 40 feet to 64 feet wide and 148 feet high; and the transformer gallery, 856 feet long by 50 feet wide and 39 feet high. Other major features include eleven inclined penstocks, each 1200 feet long and 20 feet in finished diameter; eleven draft tubes averaging 37 feet in finished diameter and 162 feet long; six vertical cable shafts each an average of 865 feet in length; a series of eleven short bus tunnels linking the powerhouse and the transformer gallery; a vertical power-

Jan 1, 1997

By Q. X. Yun, S. H. Liu

This paper provides a new approach to determine the opening layout in underground mining methods by means of genetic programming. Based on a set of random combination of openings, the layout of openings will gradually improve with the help of genetic operations, including reproduction, crossover, mutation and fitness calculation. The optimal solution will finally emerge according to Darwinian principle: "the survival of the fittest ".

Jan 1, 2002

By Alfred G. Hoyl

The small miner and small mine have an important role to play in the finding, developing and production of our mineral resources. "Help, not hinder" must be our byword. We must push in every way we can devise to change the adversary position of government and environmental movements. We need the small mines and they must be encouraged, not hindered. Technically excellent and adequate equipment is available, and needed information is also available to the small operation. Environmental questions and problems must be fully considered regardless of the size of a mining operation.

Jan 1, 1987

By J. Davitt McAteer

Improvements in the control of coal mine dust have occurred over the past 25 years. Simultaneously, dramatic improvements in coal mine production technology have occurred, particularly at mines where longwall systems are in use. Production rates of longwall systems have quadrupled since 1978, and dust generation on these systems has significantly increased. However, technology to address control of the resulting increased levels of respirable dust has not kept pace, and many high-production longwall sections continue to experience problems with respirable dust control. This paper seeks to enlist the entire mining community in the effort to resolve the health problems presented by excessive levels of respirable coal mine dust, particularly on longwall systems. These systems are expected to increase in number and length, and to generate increasingly higher levels of dust as production rates of these systems continue to rise.

Jan 1, 1995