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By J. Drelich, M. Pawlik

An improved experimental procedure to measure contact angle has been consolidated with coal surface preparation involving polishing with abrasive paper, alumina powder, and a cloth, followed by ultrasonic and mechanical cleaning. Specifically, the captive-bubble measuring technique has been compared with the sessile-drop technique and the former has been recommended for the examination of the hydrophobic properties of coal surfaces. Results of the research program, which is currently under way, on the examination of the effect of the nature, amount, size, and distribution of mineral inclusions in coal, on its wettability are briefly reviewed.

Jan 1, 1999

By Robert J. F. Goodfellow, William A. T. Meakin, Kevin Clarke, Eric Cole

INTRODUCTION New York City Water Supply—Background and History Since the 1840s New York City has been developing the largest, and perhaps, the best urban water supply and distribution system in the world in terms of quality and reliability. One of the engineering marvels of the modern world, the New York City water supply and distribution system serves a population of almost nine million, including residents in nearby Westchester, Putnam, Ulster, and Orange Counties of New York State. The average daily supplies presently are running at almost 60 m3/sec(about 1,350 million gallons per day). The watershed for the New York City water supply system, under the jurisdiction of the New York City Department of Environmental Protection (NYCDEP), consists of19 reservoirs and three controlled lakes, and covers an area of approximately5,000 square kilometers (about 2,000 square miles) north of New York City. The watershed total available storage capacity is about two billion cubic meters (560 billion gallons) and is divided into three reservoir systems: the Catskill and Delaware watersheds located West of the Hudson River; and the Croton watershed, located east of the Hudson River, see Figure 1. The first element of the system, the Croton Aqueduct, started operations in 1842.Through several updates and expansions, the present-day Croton system was in place by 1911, providing a potential maximum supply of about 15 m3/s (about 340 mgd). The system includes ten reservoirs and three controlled lakes. In the late 1800s, with the tremendous growth of the City, New York City water engineers began to look for additional sources. Between 1907 and 1929, the City acquired water rights and constructed a new 148 km (92 miles) Catskill aqueduct to convey water from the Ashokan Reservoir to the City. The Catskill system also included the construction of the Kensico and Hillview Reservoirs just north of the City,

Jan 1, 2005

By P. C. Kapur

The hierarchical relationship between three broad kinds of grinding models for a spatially homogeneous, linear, time-invariant batch grinding system are first established. Limiting and asymptotic arguments for arriving at approximate but simpler models are employed in all three cases. These parsimonious models -provide alternate and, in some respects, more incisive and convenient tools for the analyses of grinding processes and simulation of comminution circuits. In the discrete-size, discrete- time class of models, a reduced mill matrix is derived, which is seemingly adequate for those grinding circuits whose identification otherwise is difficult because of limitations on the quantity of data and its quality. In discrete-size, continuous-time types of models, parameter lumping has been employed for obtaining a G-H solution which is quite accurate and exceptionally useful for graphical display of data, model verification, and parameter estimation and simulation. In continuous-size, continuous-time models, a similarity transformation is used for solving the integrodifferential equation of grinding. This solution provides a unified framework for a number of apparently diverse empirical grinding phenomena such as self-preserving behavior of ground particle size distributions and energy laws.

Jan 1, 1987

By R. M. Owens, J. F. Lupo

The Shirley Basin Uranium mine, located in southeastern Wyoming, USA, was an open pit mining operation consisting of a series of several open pit mines excavated into poorly consolidated sandstones, siltstones, and claystones. Since the initial open pits were developed in 1969, slope failures have plagued the mine and mining operations. These slope failures have persisted into the current mine reclamation period. When the mine was first developed, the open pit slopes were designed to range between 45 to 55 degrees. Numerous slope failures during mine development required the pit slopes to be redesigned with slopes as shallow as 26 degrees. At present, movements are occurring within the open pits on reclaimed slopes that are shallow as 12 degrees. Several detailed slope studies were conducted at the mine in the early 1970s. These studies, combined with more recent geotechnical investigations, provide a unique detailed history of pit slope failures on shallow slopes. This paper presents an evaluation of the slope failures at the Shirley Basin mine, highlighting important mechanisms causing slope failures on very shallow slopes. The evaluation demonstrates important key parameters for shallow slope design.

Jan 1, 2001

By D. S. Bird

Kennecott Utah Copper began a modernization program in 1986 that was aimed at expanding and updating mining and ore process facilities at the company’s Bingham Canyon copper mine and concentrator near Salt Lake City, UT. Major components of the project included installation of an in-pit crusher, a transfer conveying system and a new ore concentrator with a design capacity of 70 kt/d (77,000 stpd). The Copperton concentrator was commissioned in February 1988. The grinding circuit is one of its principal features. It consists of three identical lines, each with a 10.4-m- (34-ft-) diam x 4.6-m- (15-ft-) long semiautogenous grinding (SAG) mill and two 5.5-m- (18-ft-) diam x 8.6- (28-ft-) long ball mills. The SAG mills are driven by two 4.5-MW (each) (6000-hp) variable- speed dc motors through a clutch-pinion gear-ring gear assembly. The ball mills are driven by 4.1-MW (5500-hp) synchronous motors coupled through a typical clutch-pinion gear-ring gear system.

Jan 1, 1995

By S. C. Suboleski

Underground long-range planning and mine design is an iterative process beginning with a specified production level, quality criteria, and geology of the deposit. Given these factors, face equipment is selected, the number of units needed and production per unit are calculated, and the mine infrastructure needs are developed. The scheduling of units then follows, with the design of the various support systems coming next. The support systems needed to maintain production can be grouped as follows: (1) outby haulage of mined material, (2) supply and manpower haulage, (3) ventilation and associated environmental considerations, (4) drainage, fresh water, and related considerations, (5) rock mechanics, and (6) power, supply. Thus, long-range planning may be viewed as a three-tiered structure, with the data on required production, product quality, and geology at the upper level; the development of face production capacity and the scheduling of units sufficient to meet the needs of the first two at the second level; and the development of support operations for the production units at the third level. Changes at any level may affect not only the items on that tier but may also cause a change to the items on the tier above and below. For example, if the rock mechanics data indicate that desired opening sizes will not be stable, then this situation will affect not only the ventilation design but also the production rate and possibly the selection of equipment itself. These, in turn, may affect the scheduling of units and the number of units, ultimately influencing the entire third tier of systems.

Jan 1, 1979

By John S. Summer

The induced polarization (IP) method of geophysical exploration is capable of detecting even small amounts of metallic luster minerals in a rock mass. Consequently, in the years since discovery, IP surveying has become the most popular ground geophysical survey method. It is not too difficult to understand many applications of IP surveying as used in the search for mineral deposits. However, the basic theory of the IP phenomenon is not well developed or understood, and there has been some disagreement on fundamental concepts. In order to most effectively apply the IP method in the field it is necessary to know the physical characteristics of the sought-for deposit including its size, shape, depth, and electrical properties. With this information an optimum IP search arrangement can be devised and one could use the best possible electrode interval, type of array, and line spacing. With uncertain target characteristics as encountered in the real world, geological guidance must be used to help direct an optimized IP survey.

Jan 1, 1972

By M. M. Botz, F. W. DeVries

Discussion by F.W. DeVries Comments on natural cyanide attenuation. The paper by Botz and Mudder in the November 2000 issue of Minerals and Metallurgical Processing had one disappointing aspect. Table 1 (p. 229) failed to include a significant species - neutral copper cyanide (CuCN). This compound has been most trouble-some in many plant-scale cyanide cleanup processes, includ- ing acidification-volatilization- reneutralization (AVR), hy- drogen peroxide cleanup and air/SO2 cleanup. It has also plagued many pilot efforts to use ion-exchange (IX) resin technology. This author elucidated the concept that, under some conditions, copper cyanide failed to precipitate out of treated effluents and appeared to exist as a filterable colloid that reported as copper and cyanide, with the latter measured as WAD (weak-acid-dissociable) cyanide in that analytical method. The concentrations measured were very near the levels of 0.2 ppm, often the regulatory limit for WAD cyanide. The copper concentration, using the 1 : 1 ratio for this com- pound, would then be more than 0.4 ppm, which could also be unacceptable. We discovered that it was unsafe to assume that the Cu(CN),- would surrender both cyanide ions simultaneously and allow cupric copper to be removed subsequently as, say, cupric ferrocyanide (Hatchett's Brown). This compound could be ignored as safely as the "iron blues," as essentially an inert solid, stable in geologic time if not exposed to sunlight. Under poorly controlled oxidation of the cyanocuprite ions (copper with four, three or two cyanides complexed to the copper), CuCN could well be formed and could not be assumed to precipitate out as a solid. The authors of the paper, by failing to include the CuCN species in their model, may have left users of the model prone to ignore the possible occurrence of the colloidal(?) form in the discharge, thus finding an effluent that failed to meet regulatory limits. (See addendum below.) This somewhat ephemeral material may well have been responsible for some large-scale failures of cyanide destruction technology to succeed at sites in North America and elsewhere. Two specific references alluding to this occurrence may be found: Griffiths et al., 1987, "The detoxification of gold-mill tailings with hydrogen peroxide," Journal of the South African Institute of Mining and Metallurgy, September, p. 282. DeVries, 1989, "Improved understanding in detoxification of cyanide leach liquors using peroxide" Rand01 Gold Conference, Sacramento CA, p. 15 1. It is advisable for workers in this area of cyanide removal or recycle to avoid assuming that CuCN will, with certainty, precipitate out of solution, or that the dicyanocuprite ion will part simultaneously with both cyanide ions and allow cupric copper to be dealt with by other reactions. One further piece of work may be incomplete. That is, a definitive study of the long-term behavior of CuCN that does precipitate when exposed to other compounds present in neutralized tailings. Addendum. The extremely complex reaction of cupric ion on cyanide- which, of course, results in oxidation of cyanide to cyanate, probably through the intermediate stage of forming cyanogen [(CN)2] from oxidation of HCN with its hydrolysis to cyanate and cyanide ion - involves two cyanide moieties and the reduction of the cupric ion back again to the cuprous state. This, then, can form the CuCN potential "solid" that was already the undesirable species. In cyanide cleanup, with either air/SO2 or hydrogen peroxide, copper is generally employed as the catalyst, so it is unclear what happens when the CU(CN)2-1 is ultimately exhausted. Certainly, the field evidence is quite clear that all

Jan 1, 2002

By Anthony Peach, Lok Home

Introduction Raise boring is the most accepted form of mechanized hard rock boring in the mining industry. It appeared logical to take this mechanization one step further by introducing computers. Atlas Copco Jarva has produced a series of raise boring models that use an integrated computer. The company decided to use electronics and computerization, not for marketing purposes, but to make its equipment more cost-effective. Basis of Cost-Effective Design From the manufacturer's standpoint, it is possible for the equipment owner to reduce the cost of putting in raises by: • Replacing existing components with less expensive components that produce the same results; • Replacing existing components with more expensive components that make the equipment more productive; • Mechanizing equipment to reduce associated labor costs; and • Combining the above. Analysis of a standard raise boring machine (RBM) system showed that little could be done with less expensive components. It appeared, however, that the RBM could be more productive by transmitting more horsepower through the expensive drill string, while being precisely controlled by computers. An RBM system includes a basic machine, drill pipe, accessories, reamer, and cutters. The approximate percentage cost of various components on a standard system capable of boring 300 m (985 ft) long and 3-m-diam (10-ft-diam) aises in medium to hard rock is shown in Table 1. Also shown is the increased cost above standard of the Jarva computerized machine, and the productivity of both. Increased Productivity Penetration is important during the reaming cycle for more productive raise boring. This is possible by increasing the cutter load with constant rpm or increasing the rpm with constant cutter load. To increase thrust and maintain rpm requires increased capacity in the cylinders, drive train, main thrust bearings, drill string, electrical motors, and power units. To increase rpm and maintain cutter load requires only increased capacity in the electrical motors and power units. This is possible because the torque requirement remains constant for a constant thrust load. Only the horsepower increases, proportional to rpm. Since cutter costs are a big factor in raise boring, changes in machine performance must be analyzed to assess the effect on cutter performance. With a standard or typical carbide cutter, as used on raise boring machines, the effects of increased thrust or rpm are shown in Table 2. The assumption is made that the base data is the current rpm and thrust range where the cutters are now operated. It is also assumed one variable is held constant while the other increases. The result of this comparison, approximately, is that a 50% penetration increase can be achieved with little or no increase in cutter cost if rpm is increased 50% and cutter load is maintained constant. A similar 50% penetration increase can be achieved with a 45% increase in cutter cost, if the cutter load is increased by 20% and maintained constant. From an equipment standpoint, it is significantly less expensive to increase rpm 50% than it is to in-

Jan 7, 1984

By L. Michael Kaas

Any increasing number of restrictions are being placed on mining management's ability to pursue profit. Raw materials pricing, the cost of capital equipment, labor cost, and overhead costs, are becoming more difficult to control. Cost reduction is one of the few remaining areas in which management may still exercise its profit making ability. Equipment maintenance is an area where mine and mill management can readily reduce costs and increase profits. Why is this possible? First, maintenance costs comprise a large portion of total operating cost. Thirty to sixty percent of the operating cost dollar is not unusual. Even a relatively small percentage reduction in this cost represents a very sizeable increase to mining profitability.

Jan 1, 1967

S.L. Barua and Y.C. Kim M. Armstrong's paper is very interesting and can be regarded as a pioneering work of applying geostatistics on washed coal. The density levels used in her study are uniformly spaced, which facilitated curve fitting through a proper experimental design. Most of the existing coal washing plants in the US, however, gather washability data at non-uniform intervals which, in turn, affects the goodness of curve fitting. We would like to emphasize the importance of having a proper experimental design, if a similar geostatistical application is to be conducted on washed coal. We, at the University of Arizona, tried the variogram on recovery (Kim, Barua, and Baafi, 1982, SME preprint 82-143) which showed a similar pattern as Fig. 4 of Armstrong's paper. In both cases, the first experimental variogram value is invariably and inexplicably higher than the second variogram value. Although Armstrong ignores the first point because of "small number of sample points," we did not do so because there were 17 sample pairs. As a consequence, we concluded that the obtained experimental variogram was unsatisfactory and that further research is warranted. In other words, this disagreement in variogram interpretation between M. Armstrong and the University of Arizona begs the question whether the experimental variogram of Fig. 4 truly reflects the spatial correlation in washed coal, assuming there is such a correlation. Finally, we wish that Armstrong could have done a similar study on clean sulfur, which is a vital interest to the coal mines in the US. Her implied remark on sulfur in the concluding section of the paper may turn out to be incorrect because our experimental variograms on clean sulfur at different density levels were even less satisfactory than those on recovery.

Jan 1, 1985

By J. Paraszczak

With regards to the cost and profitability of a mining operation, the performance of the equipment employed is one of the key issues. Cost and profitability depend on, among other factors, the reliability and availability of the equipment. In an attempt to reduce equipment downtime, it is indispensable to collect and analyze reliable data and information on failures and maintenance actions. This paper reviews common problems encountered in this respect, with particular emphasis on the lack of uniform terminology and methodology. Recommendations concerning the standardiztion of reliability and maintainability concepts and measures are given. Regarding the benefits that the latter may bring, the paper concludes with a proposal for an industry-wide initiative in this respect.

Jan 1, 2002

By Ernest F. Giovannitti

A couple of years ago, one of the major television networks produced a series on the environment. One episode in the series dealt with the nation's solid waste problem and some of the research being done to solve it. It was interesting to listen to one researcher who was attempting to develop a glass that when broken would dissolve in water. It was said that using this glass would eliminate over 100 million tons of solid wastes each year. At first glance, it would appear that this research-effort would make a significant contribution to environmental pollution control; however, if one pauses to consider the water, he can see that this solution to the solid waste problem may well contribute to a water pollution problem. The dissolved material must either end up in our surface streams or be removed in waste treatment systems. Either alternative may have a more adverse effect on the environment than the original problem. With today's emphasis on the environment, it is important that the effects of our activities be studied in depth. Then, by properly planning the activity, the adverse effects can be minimized. The coal mining industry 100 years ago was in the same boat, as our glass maker, is today. Unfortunately, it too failed to consider all the effects of its activities and as a result, in Pennsylvania, there are over 5000 miles of streams adversely affected by coal mine drainage. The situation is improving, however, because mine operators are beginning to recognize and accept the methods for controlling coal mine drainage. The purpose of this paper is to discuss the measures for the control of coal mine drainage and to set forth the factors that affect these controls.

Jan 1, 1972

By Harold L. Lovell

The current interest in sulfur recovery from coal measures is indicated by a recent report prepared for the Public Health Service (1) It was noted that the concentration of pyrites to a product containing 42-48 percent sulfur should be relatively easy with present equipment. It was also pointed out that a utility potential exists for the high-grade iron concentrate which results as a by-product of the consumption of pyrites in the acid-making process. However, economics, marketing characteristics, location, transportation, pyrite levels and coal characteristics all strongly influence the feasibility of fostering industrial development of such processes. The extent of pyrite recovery and product quality is intimately related to pyrite particle size and its degree of liberation, a consideration usually given greater emphasis in metal ore preparation than in processing coals. Consequently, fine crushing to nearly 20 mesh probably will be essential for maximum practical processing. It appears that any process separating pyrites from a coal must involve a reprocessing of the normal preparation plant refuse, although some yields can be attained from certain existing operations as products from, a shaking table or a jig. Further, the existence of millions of tons of coal refuse cannot be ignored as a mined source of raw materials. The recovery of saleable products from such wastes, although untried on a large scale under current conditions, not only offers a realistic source of sulfur but also would achieve a secondary refuse with the minimal contents of substances which incite and propagate the burning of organic and inorganic combustibles. These silicate materials, thus beneficiated, also offer some potential for economic utilization. Some significant tonnages of pyrites have been produced from coal measures in the past, but the experience was, in general, not consistent with current coal preparation practice. The processes involved did not include cyclones and heavy media; nor were they carries out under the sociological environment concerned with pollution as exists today.

Jan 1, 1967

By M. H. Pettibone

During the past decade, the size of grin- ding mills has steadily increased. Mills 11 m in diameter with 9 mW motors have been installed with even larger units on the drawing board. The rising costs of energy and labor have spurred interest in improving efficiency while reducing capital investment and operating labor. Autogenous and semiautogenous grinding have experienced renewed interest as efforts to reduce operating and capital costs have increased.

Jan 1, 1981

By Lee W. Abramson, James E. Crawley

Caltrans is studying alignments for a 160-kilometer-long high speed ground transportation system from Los Angeles to Bakersfield across the Tehachapi Mountains. This link is needed to connect southern California with San Francisco by a short passenger rail service. None presently exists. The system will require tunnels and viaducts along the route with sections crossing two major active fault zones. High speed ground transportation technologies are being evaluated for achieving rail speeds of between 200 and 480 kilometers per hour. This paper presents the technical requirements for tunnels along the alternative routes being considered for the project.

Jan 1, 1995

By J. P. H. Steele, T. Vincent, C. Debrunner, M. Whitehorn

For a variety of reasons, the need for automation of underground mining equipment is growing dramatically, e.g., improved safety and health, availability of labor, deeper mines, and desire for more focused excavation. While there has been tremendous progress made in this direction, much needs to be done to reach the holy grail of an autonomous mining machine. This paper reviews a number of technological developments and presents research and development needs for future development. A report on our current project for the Western Mining Resource Center at CSM is included.

Jan 1, 2000

By Behrouz Tehrani

The size, complex issues, and requirements to construct large number of tunnels, for a single project, expeditiously, and without exceeding the overall project budget, a program Construction Management (CM) team is highly recommended to be selected early during design process to provide guidance/direction relative to contract packaging and scheduling. This paper is not focused on the project itself, however, the emphasis is on experiences gained from the project. Wishing that some of the strategies described in this paper will be of value to owners of underground project.

Jan 1, 2008

By S. Chunhui, W. Anbin, R. B. Cook

The Xicheng is one of China's largest lead-zinc (Pb-Zn) districts with known minable reserves in excess of 10 Mt (11 million st). The centrally located Changba-Lijiagou and nearby deposits are representative of the district. They consist of stratiform and stratabound zones of pyrite-sphalerite-galena mineralization within deformed, moderately metamorphosed Middle Devonian clastic and carbonate units. When considered with other similar districts that extend for several hundred kilometers to the east, a major episode of Devonian sedimentary exhalative mineralization is indicated.

Jan 1, 1992

By J. R. Hindman

The vermiculite review arrived too late for the June issue. In 1992, production of commercial vermiculite in the United States increased 1 % to 170 kt (187,000 st), according to the US Bureau of Mines. The estimated value of vermiculite concentrate was $13.6 million, yielding an average value of $80/t ($72.50/st). Vermiculite is used in several physical forms. Use of the thermally exfoliated product include light weight aggregates, horticultural growth media, thermal insulation applications and absorbents for spill control and liquid waste containment. The untreated commercial concentrates are used as intumescent fillers in plaster board, gaskets and paints. Several chemically modified vermiculite products include clay-sized dispersions and granules for treating flue gas. South Africa was the only major foreign source of vermiculite used in the United States. It exported about 40 kt (44,000 st) to the United States last year. In 1992, Palabora Mining Co. began processing vermiculite in a new beneficiation mill at Phalabowra. It produced about 164 kt (181,000 st). Minor sources of foreign vermiculite concentrates consumed in the United States included about 140 kt (154,000 st) from China. Brazil also exports some concentrate to the United States.

Jan 1, 1993