Search Documents

By B. M. Davis

The Colosseum Mine is within the Clark Mountain mining district located approximately 72 km (42 miles) southwest of Las Vegas. Nevada in San Bernardino County, California. Gold mineralization at the Colosseum Mine is hosted in two 150 m by 210 m (500 ft X 700 ft) interconnected. rhyolitic intrusive breccia pipes that intruded Precambrian crystalline basement rocks and over-lying Paleozoic marine sedimentary rocks. Sub-sequent erosion (de-roofing) of all of the Paleozoic section and a portion of the Precambrian section has exposed the pipes to the present level (probably a significant depth in the original breccia pipe system).

Jan 1, 1989

By A. H. Summers

The La Choya mine is located 55 km south of Sonoyta in northwestern Sonora, Mexico. Mineralization is controlled by a 40 meter thick thrust fault zone which created a permeable host for the metal-bearing hydrothermal solutions. The ore body is mined by open pit using wheel loaders and truck haulage. Gold and silver are recovered from low grade ore by heap leaching followed by carbon adsorption.

Jan 1, 1997

By David M. Parkes, Mike Fisher

In 1947, coal production in Western Canada was 10 Mt (11 million st) which predominantly came from 120 underground mines. By 1968 production was down to 1 Mt (1.1 million st). Production in 1981 was back up to 29 Mt (32 million st), but only 1.5 Mt (1.7 million st) of the total was from underground mines. In fact, because of competition from open-pit mines, only two underground mines were operating in 1981-the McIntyre and B.C. Coal mines. While several other underground mines are being planned, this article will deal with only the two in production. Geology The geology in Western Canada is frequently complicated; hence only more regular deposits are mined. Coal is generally thick, often steeply pitched and usually soft or well cleated. The 5000-km (3,100-mile) coal belt that runs from the Yukon to Mexico is well developed in Western Canada. It is divided into two distinct regions-the Rocky Mountain Lower Cretaceous coals and the mostly uniform level Upper Cretaceous coals of the plains area to the east. Isolated pockets of coal occur at Vancouver Island and Hat Creek. Hat Creek's massive 300-m (984-ft) thick geologically recent lignite deposit is 250 km (155 miles) inland. Geography The infrastructure of Western Canada is shown in Fig. 1 along with the locations of the two mines. Both rely on exports of premium low volatile metallurgical coal mostly to the Pacific Rim. The rail distance from both mines to port is 1100 km (684 miles)-accounting for a significant portion of the sales cost of the coal. Mining Methods Two main mining methods are used-room and pillar and hydraulic. Longwall has been attempted and is being considered again. In the past, a simple hand method used gravity to help mine most of the coal on steep pitches. Levels were driven in the seam, rising slightly to assist in draining. On the advance, mining would start at the upper level, usually from adits driven in the side of the mountain. Rooms or angles were driven up 100 m (328 ft) at a suitable angle for the coal to flow down. On retreating out of the level, the pillars would be taken, starting from the highest point, using batteries to stop coal or rock flushing down the room. Batteries consisted of three to six stout wooden posts set at an angle to resist material flow. Coal loading was directly from chutes at the bottom of raises into 1- to 2-t mine cars hauled by diesel or battery locomotives. Often output was restricted by the supply of empty cars. Mechanization began in the 1960s but was difficult in these conditions. Mines such as Canmore and Coleman continued operation into the 1970s but closed because steep seams, high methane emissions, and faulting made mining difficult. McIntyre Mines The McIntyre mines are located 360 km (224 miles) west of Edmonton, Alberta, in the foothills of the

Jan 4, 1983

By D. D. Lauriski

The Mining Division of Utah Power and Light Company is located in the coal fields of southeastern Utah -main office in Huntington, Utah. The Division will produce 6.5 million tons of low sulfur steam coal in 1988, making UP&L the largest underground mining operation west of the Mississippi. Coal is mined from three underground mines utilizing continuous miner and longwall mining methods. All coal produced by the Mining Division is utilized at UP&L's two largest steam-electric power plants, the Hunter and Huntington plants with a combined capability of 1,995,000 Kw. At UP&L we believe that to achieve success a company must have clearly defined goals which are understood, communicated and shared at each level of operation. We have also found from experience that a safe operation is generally an efficient and productive operation. As a Division, we have established a goal to achieve the safest, most efficient operation in the country. This is an ambitious goal. To achieve such a goal requires real commitment and a safety/training program capable of achieving needed results. The following is an overview of the program we have established at UP&L which has enabled us to reduce our accident frequency rate from over 40 in 1980 to 8.00 at present, as illustrated in Figure 1.

Jan 1, 1989

By L. D. Savage

Several experiments were conducted using a large crib fire adjacent to a Kennedy Metal Products steel stopping in a simulated cross cut to evaluate the proposed mechanisms by which a mine fire would breach the stopping. Temperatures in the convective air paths on both sides of the stopping, at the surface of the roof and 16mm within the roof were measured to evaluate the effects of heat transfer. The results indicate that roof failure is the prime method of breaching this design of stopping.

Jan 1, 1996

By Charles C. Mosher

An in-mine seismic technique for detecting faults has been tested in a Western U.S. coal mine. This technique has been used extensively in the U. K. to help guide longwall mining operations. Explosives detonated on the face of a seam generate sound waves which propagate into the seam. Reflections from faults are picked up by sensors on the same face. Computer processing is then used to determine the fault locations. A known fault was successfully located in this test. Modifications to the U. K. procedures were required for the relatively thicker roan and pillar mines common in the Western U. S.

Jan 1, 1983

By R. Herrera-Urbina, D. W. Fuerstenau

A large number and a wide variety of chemical reagents are used in flotation processes for wettability and Eh control, particle agglomeration/dispersion and bubble stability. A historical account of the use of flotation reagents through the years since flotation was introduced as a viable and economic process for the concentration of sulfide minerals is given and a review of old and modern postulates of their interaction with minerals is presented. Although the results of surface and colloid chemistry studies with well characterized mineral/flotation reagent systems have advanced our understanding of the role played by these chemicals in the flotation process, many questions remain unanswered. Moreover, new flotation reagents are needed to solve the challenge posed by the treatment of problematic-type ores and fuel deposits that have increasingly become the source of our raw and energy materials. Because of the depletion of high-grade and relatively easy-to-process ores, flotation scientists and engineers are confronted with finding more specific and selective flotation chemicals to effectively and economically concentrate minerals. The development of new flotation reagents is vital for cleaning fine coal and processing polysulfide, polymetallic ores, and mixed oxide/sulfide ores.

Jan 1, 1989

By T. D. Murphy

In the fall of 1988 it became evident that the accuracy of sulfur forecasts for Monterey Coal's No.1 Mine needed to be improved. In addition, it became necessary to predict if any individual train shipments during a month would exceed a contract sulfur limit. The challenge was to develop a forecasting process that would take into account the variability of the coal in the ground as well as the difference between laboratory and preparation plant sulfur reduction efficiency, and the effects of mining coal with multiple units. This paper describes how geostatistics and simulation techniques were used to meet this challenge.

Jan 1, 1992

By G. J. Schneider

The higher stress zone adjacent to an underground opening causes a velocity anomaly that can be mapped in favorable conditions with an acoustic cross-borehole logging system. Bureau personnel used a specialized system at the Colorado School of Mines test site near Idaho Springs, Colorado, to locate the Edgar Mine tunnel and its associated stress anomaly. Data from the logging system' were processed with a tomographic image reconstruction algorithm to map the opening and the location of the high velocity zone around the opening. The velocity imagery from tomographic analysis compared favorably with predictions from numerical modelling of the location of the stress anomaly.

Jan 1, 1988

By H. Cetin

The availability of coal resources of selected 7.5-minute quadrangles of southwest Indiana was examined in this study. Resources were defined as original coal in place, remaining after mining, and currently available considering land-use and technological restrictions. The amount of coal mined from each study area varies depending on the mining practices of the companies operating within the area. Of the three quadrangle investigations, the available resources range from 50 percent to 79 percent of the original resources. Most of the coal resources under deep-minable category were not available because of technologic restrictions, such as insufficient coal thickness.

Jan 1, 1996

By J. A. Folinsbee

Placer Dome Canada owns and operates the Campbell Mine at Balmertown, in the Northwestern corner of the Province of Ontario, Canada. The mine operates at 1500 stpd and produces in excess of 300,000 oz of gold annually. Recent changes to the gravity concentration circuit have resulted in a 10-15 % increase in gravity recovery. The circuit changes responsible for these improvements will be the focus of this paper.

Jan 1, 1997

By D. Baker

Alternative material handling methods are allowing material handling operations to be performed with increased cost savings. This allows for higher production levels with better returns. RAHCO International Inc.'s Continuous Mining Excavator (CME) has recently received a lot of attention due in part to its operating efficiency, flexibility, and associated low operating costs. The CME is designed to perform three primary functions. These include material excavation, sizing and loading operations. In many applications, a drilling and blasting process can be eliminated. The CME was developed originally in 1985 for open pit coal mining. See figure I. Since this time, it has been proven an effective system for excavating many other types of materials including friable and sticky materials. It has also been shown to suitably handle hard rock in certain site conditions.

Jan 1, 1998

By R. C. Bunge

The selective flotation of semi-soluble salts with fatty acids is often negatively affected by the interaction of the potential determining cation with the ionic surfactant in bulk solution. This problem can be avoided by floating at low pH which involves the emulsification of the collector. The research presented here focuses on the influence of the Ca2+ ion on the flotation of fluorite with palmitic acid at low pH. Our results show that the surfaces of collector emulsions are dominated by precipitation phenomena similar to those encountered in bulk. In turn, fluorite in palmitic solution at intermediate pH displays surface properties similar to those of the collector by itself. This may be due to two alternative mechanisms (i) adsorption of bulk precipitate on the fluorite surface or (ii) the formation of a bilayer of surfactant ions on fluorite. Possibly, both mechanisms occur simultaneously.

Jan 1, 1993

By J. D. Lowell

The gold content of prophyry copper deposits ranges from less than .05 gmt (ppm) to more than 1.0 got, and most deposits contain on the order of 0.05 gmt Au. Perhaps the highest grade mineralization which has been found in close proximity to a porphyry copper is the Ok Tedi Gold Cap orebody whose grade falls in the 2-3 gmt Au range.

Jan 1, 1988

By W. A. McKinney

In conventional dump leaching of porphyry mine strip wastes, many years are required to extract up to 20 percent of the copper from the contained sulfide minerals. Furthermore, none of the molybdenum, gold, or silver in the strip wastes is recovered by current leaching practices. Because mineralization occurs predominately along fracture planes, breaking of the rock during mining operations liberates and concentrates some of the metal values in the fines. Research shows that upgraded fines can be screened from mine wastes and froth floated for early recovery of copper, molybdenum, gold, and silver. For example, screening a dump sample assaying 0.35 percent copper as chalcopyrite removed about 20 percent of the copper as minus 1/4-inch material that analyzed 0.6 percent copper. About 35 percent of the molybdenum and 20 percent of the gold and silver also reported in the fines. Crushing the mine dump sample to minus 3 inch before screening increased the distribution of copper and molybdenum in the minus 1/4-inch screen fraction to 28 and 50 percent, respectively. Similar results were obtained by screening fines from two other large samples of mine waste dump materials. Flotation studies established that the enriched minus 1/4-inch fines from the three dump samples could be effectively concentrated. Comparative testing revealed that the combination of froth flotation of fines and acid-ferric sulfate leaching of the coarser fraction enabled doubling the recovery of copper over direct leaching of the samples. In addition, significant amounts of molybdenum, gold, arid silver were recovered by flotation.

Jan 1, 1970

By Roland Froidevaux

The potential use of geostatistics for quantitative ore reserve reporting is shown using a simple gold case study as an example. The need of defining quantitative class limits is stressed, and a possible approach to this problem is suggested.

Jan 1, 1983

By G. Jalkanen

Dealing with a trend in inverse distance estimation, IWD, is presented. A measurement is proposed to be consisted of a portion due to a mean and a portion due to a residual. The procedure consists of de-trending the measurement via a linear or nonlinear regression. Residuals are computed, and IWD parameter estimation is conducted on the residuals. Estimation at un-sampled points is then computed by estimating the mean and adding on the estimate of the IWD on the residual. A possible BOXCOX transform is also proposed.

Jan 1, 2010

By J. D. Shenk

The White Cliffs diatomite deposit occurs in a lacustrine facies of the Quiburis Formation, an Upper Miocene to Pliocene basin-fill sediment of the lower San Pedro Valley. On-going geo-logic mapping has defined an 2.5-3.0 m (8-10 ft) thick ore zone near the mill site, several marker beds, a NNW-trending high-angle normal fault, and a NW-trending syncline. The diatomite has an average loose-weight dry bulk density of 130 kg/m3 (8 lbs/ft3) and is presently marketed outside Arizona for asphalt filler. Current development is projected to yield 3500 mt (4000 st) of finished product, with an estimated 91,000 mt (100,000 st) of finished product obtain-able from several other nearby sites.

Jan 1, 1988

By S. W. Swerson

25.1-THE PURCHASING FUNCTION The word "purchase" means "to obtain by paying money or its equivalent; to buy for a price." This definition is all too simple to properly describe the word "purchase." One should consider the basic objectives of purchasing-to procure the right material, of the right quality, in the right quantity, at the right time, from the right source at the right price. Here it should be noted that in purchasing it is recognized that the best quality or grade of materials may be the only grade to purchase for a specific job. However. there are other jobs where the medium, standard or poor grade of materials is the right quality, as the lesser grade will perform adequately. In some companies the purchasing department makes the decision as to the right quality, while in others this function is shared with other departments. Years ago in business the owners controlled the purchase of required materials and services by performing the task themselves. The owners obtained the type materials and services they needed and paid the price demanded. This function was performed along with all the other duties requisite to the owner of a business, namely, clerical, hiring and firing of personnel, financial management, etc. As companies grew in size, clerical duties were assigned to other personnel and the owner usually retained the purchasing authority. This same division exists today in many small companies. However, in the larger companies, the purchasing function has been assigned to a separate department. Importance of the Purchasing Function-The larger the company the greater the need for a separate department to perform the purchasing function. Today the purchasing agent for most larger progressive companies has policy-making authority. Therefore, it is reasonable for him to report to the president or vice president of his company. Studies of several hundred companies show the purchasing department head reporting to top management 87.5% of the time. This fact in itself is indicative of the importance of recognizing that effective purchasing requires a department staffed with specialists in the field of procurement with knowledge and experience sufficient to perform in today's complicated business atmosphere. In the manufacturing field it is a common axiom that usually half of the company's dollar expenditures are for materials. If a purchasing department functions properly and the right product or service is purchased and a savings accomplished, the contribution to the net profit of the company is much greater, as opposed to sale dollars, where only a small portion is carried forward to net profit. Thus, the importance of the purchasing department and the contribution it can make to the success of the company are obvious. 25.1.1-THE PURCHASING FUNCTION 1. Responsibilities of the Purchasing Function-The purchasing agent in performing his function is acting as an agent for the company and others in the company requiring materials and services. Accordingly, he is committing the company for materials and services subject to certain limitations which the board of directors may stipulate. In view of this, the purchasing agent,'^ position must of necessity he

Jan 1, 1973

By R. J. Morrell

The Bureau of Mines, U.S. Department of the Interior, has developed a hardrock cutting concept and incorporated it into an extraction system called the ripper miner. This concept uses a single, wide bit that attacks the rock at a shallow angle and slow speed. Research has demonstrated that the system is capable of excavation rates exceeding those possible with conventional drill-blast and can effectively cut rock too hard for conventional roadheaders or continuous mining machines. It has the additional advantages of low bit wear and dust generation. This highly flexible concept is applicable to both mining and driving development openings and can cut any material from coal to hard rock. A single rip-per miner can perform the functions of a continuous mining machine, a roadheader excavator, and a tunnel boring machine. This paper presents the history of the development of the ripper miner from the initial laboratory tests through the construction and testing of the full-scale, lab prototype. It includes a comparison of the ripper miner to systems currently used from the standpoint of energy efficiencies and operating costs.

Jan 1, 1989