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By C. Özgen Karacan

The formation of the gas emission zone in longwall mining and the potential amount of gas in this zone are factors of local geology and spatial variability within this geology. Therefore, geostatistical methods can be used for modeling and prediction of gas amounts and for assessing its uncertainty in the gas emission zone of longwall mines. This study used core data obtained from 64 exploration boreholes drilled from the surface to the bottom of the Pittsburgh coal seam in a mining district in the Northern Appalachian basin. After identifying important coal layers for the gas emission zone, semivariogram modeling was conducted for different coal seams to define the distribution and continuity of various attributes. Sequential simulations were performed for stochastic assessment of these attributes to calculate gas-in-place (GIP) in each coal seam. GIP calculations for coals of various gas emissions zones were combined and ranked for their cumulative distribution function to find GIP in the caved zone and in the fractured zone at the 5%, 50%, and 95% quantiles. Fifty percent quantile results were later used to isolate a panel from the whole area and create a mosaic representation corresponding to the daily advance rate of the longwall face. This approach helped to estimate the daily emissions of this panel from the caved zone and from the fractured zone. Results showed that gas-in-place in the Pittsburgh coal seam, in the caved zone, and in the fractured zone showed spatial correlations that could be modeled and estimated using geostatistical methods. This study showed that gas-in- place volumes in the study area may be as high as 12.3 Bscf and as much as 3.5 MMscf per acre of mining.

Jan 1, 2012

Introduction The art of ripping has been around since the Romans built the Appian Way, but only in the last decade has ripping emerged as a close competitor with drilling and blasting in breaking up heavy rock formations. That is not to say ripping is as effective in every case, or even applicable in all cases, but it does provide a cost efficient option in many situations-if the optimum ripping techniques are used. Originally designed only to loosen hard pan, the ripper has evolved into a powerful tool, its capability increasing as the weight and horsepower of tractors increased. The tractor-mounted ripper extended the range of ripping because of the additional weight it brought to bear on the ripper tooth. Tandem ripping added the weight and power of a second tractor, extending the rippability range even further. Of course, the use of ripping depends on the type of material to be ripped. Not all rock can be ripped. Determination of rippability-an art in itself-is often inconclusive but there are certain universal principles that can be considered in the first step toward optimizing ripping techniques. Each of the three basic rock types, igneous, sedimentary, and metamorphic, exhibits characteristics that bear on rippability. Igneous rocks are the most difficult to rip because they lack the stratification and cleavage planes essential to ripping hard rock. Sedimentary rocks are generally the most easily ripped since they are built of layers differing in material, texture, color, and thickness. Metamorphic rocks vary in rippability with degree of lamination or cleavage caused by transformation from pre-existing rock. The condition of rock also affects its rippability. Although sedimentary rocks offer the best opportunity to rip and igneous and metamorphic the least, decomposed granite and other weathered igneous and metamorphic rock often can be ripped economically. Little or no trouble is encountered with hardpan, clays, shales, or cemented gravel. Likewise, highly stratified or laminated rocks offer good possibilities for ripping. However, thicklybedded rock formations generally must be drilled and blasted. The physical characteristics that favor ripping may be summarized as follows: • Fractures, faults, and planes of weakness of any kind; • Weathering, resulting from temperature and moisture changes; • Brittleness and crystalline nature; • High degree of stratification or lamination; • Large grain size; • Moisture permeated clay, shale, and rock formations; and • Low compressive strength. Ripper Types A second fundamental to optimal ripping is choosing the right equipment for a particular job. There are three types of rippers-the hinge, the parallelogram, and the adjustable parallelogram. In the hinge ripper the linkage carrying the beam and shank pivots on a fixed point at the rear of the tractor. The resulting arc from up and down movement causes up to 30° differential in the tip-ground angle. Thus, the tooth angle changes as it enters and proceeds to ripping depth. The parallelogram ripper's linkage maintains the same tip-ground angle regardless of tooth depth. This type of ripper has advantages over the hinge-type when ripping above maximum depth, but does not provide the aggressive tooth angle necessary for hard-to-penetrate materials. The adjustable parallelogram combines the benefits of both the hinge and the parallelogram rippers. It has the additional benefit of being able to vary the tip angle to the optimum angle of penetration. It can also be adjusted while moving, for the optimum ripping angle in any material. Several other factors that are important in selecting the right ripping equipment are down pressure available at the tip of the ripper, tractor flywheel horsepower, and the tractor's gross weight. Down pressure at the tip determines whether ripper penetration can be obtained and maintained. Flywheel horsepower rating determines whether the tractor has the power to advance the tip. The tractor's gross weight determines whether the tractor will have sufficient- to use the horsepower. The best ripping procedure depends on the job's actual conditions. While conditions, vary, it is still possible to apply certain proven techniques to a typical ripping situation. Caterpillar Tractor Co.'s Handbook on Ripping says optimum ripping efficiency can be realized if-before actual ripping begins-these questions and answers are considered.

Jan 1, 1983

By R. L. Stone

By means of laboratory balling tests and a procedure for determining bentonite concentration in a green ball the present study revealed that the bentonite savings by mulling concentrate and bentonite prior to balling was sufficient to warrant installation of a full-size unit in a pellet plant. On the basis of this work, a muller was put on stream at Bethlehem Steel Corporation's Cornwall pellet plant in June 1969, and has operated continuously since then. Plant tests showed that the use of the muller resulted in bentonite savings of about -502 without any loss of green, dry, and fired ball quality. Virtually no maintenance problems have been encountered. This information is important to future pelletizing operations both from the standpoint of product quality and economics.

Jan 1, 1971

By Fred W. Stuart

Microprocessor technology has revolutionized the business community by placing tremendous computing power in the hands of the end-user for a very inexpensive price tag. The range of applications covers process control, to office automation, to personal computing capabilities. With the influx of this new technology, which these systems have to offer, also comes some unique operational and control considerations. But before we address these items, let us lay a foundation of common terms to be used throughout this presentation. Due to the rapid advances in microprocessor technology, where a new generation of computers is announced every two or three years, it becomes difficult to define a microprocessor system and have it valid for an extended period of time! Therefore, for this presentation, we will be dealing with a subset of microprocessors called Personal Computers or PC's. At the heart of a PC is a Central Processing Unit or CPU. The CPU performs the actual program and command execution. The programs dealing with driving the various peripheral equipment is referred to as the Operating System (for example: DOS : Disk Operating System, CP/M - Control Program/Microcomputers, etc.). The CPU is normally housed in an enclosure which contains power regulators, peripheral equipment interfacing 'cards', and expansion 'slots' to enlarge the capabilities of the PC system.

Jan 1, 1989

By Ronald R. H. Cohen, Margaret W. Staub

Two pilot scale bioreactors designed to treat acid mine drainage primarily using sulfate reducing bacteria were constructed underground at the Eagle Mine Superfund site in Minturn Colorado. The project was designed to test th applicability of microbiological treatment on water with high metals concentration and to test the process in an underground environment. Objectives were, 1) to compare metal removal, pH increase, and sulfate reduction in a single stage reactor with a double stage reactor of equal volume at varying flow rates; 2) to determine where within the substrate treatment occurs· and 3) to examine volume versus surface ara as a design parameter for optimizing metal removal processes. Results from the reactors showed that the single stage reactor and double stage reactor performed equally well for the removal of Cd, Cu, Pb, Fe, Mn, and Zn. pH increased above 6.5 in both reactors. Greater than 97% of metals were removed within the first ten inches of substrate. Volume proved to be a more useful parameter for determining removal rates than area. Using volume as a design parameter rather than surface area enables PMDT systems to be constructed as packed columns rather than broad wetlands, Thus, space requirements are significantly reduced.

Jan 1, 1993

By D. C. Moore

The decision to proceed on a "fast track" construction project is not" without risks as well as rewards. An understanding of some of the risks prior to start of the project will maximize the rewards. This paper describes the research, development, procurement, engineering and construction of the Asamera Minerals cannon Mine concentrator. This fast track project was accomplished in 20 months. Special attention is paid to the risks encountered and the steps taken to ameliorate them.

Jan 1, 1988

By S. Corrent, F. A. V. Guimarães, M. G. Barbosa

"INTRODUCTION Moisture can be a villain, so new technologies have been explored to make more viable the production of high moisture iron ores. The current work presents the attempt of the utilization of a superabsorbent polymer (SAP) to aid in the screening process and in the ore handling process, such as stockpiles reclaiming and vessels/trains discharge in sub-zero temperature conditions. The results have shown that the polymer can be used in certain cases to improve productivity and increase safety in the process of handling the material (by increasing the TML). However, for size separation no advantages were found upon the use of the polymers. WATER ADSORPTION MECHANISMS The use of water in mineral processing is constant as its utilization brings an increase in the efficiency of separation. Although we have better results in the processing with water, materials with a high content of “natural” moisture can be very difficult to be treated by the conventional methods of separation. Nowadays many studies have been conducted in order to understand the effect of adsorption of water in the particles of complex minerals. Those studies have being divided in many different lines of research such as contact angle of a drop of water and the surface of the mineral to determine hydrophobicity, the particle size distribution and the porosity of particles. Mainly two forms of adsorption of water by the particles are possible: one the water is retained inside porosity of the particles. Laboratory tests developed in China have showed that capillary adsorption is faster in coarser particles that achieve the saturation degree earlier than finer particles (Xuewei Lv et al., 2011). The so called non-porous model considers the effect of water in the bulk sample of iron ores, in a physical connection when all the water works as a binder between particles as shown in the figure 1.If we take into account the compressibility of the system and compaction due to the weight of the bed over the particles, the thickness of the water film between particles is the same but the volume inside different particle size systems is much higher than in a system with particles of same size."

Jan 1, 2018

By R. Q. Honaker

Dense medium processes are used to clean over 50% of the coal that is fed into preparation plant facilities worldwide. The dense medium is formed using ultrafine magnetite which is recovered after the cleaning step using drain-and-rinse screens and magnetic separators. Despite the high efficiency of the recovery system, magnetite losses of around 0.5 to 1.0 kg/ton are common. Considering the recent escalation of magnetite to around $300/ton, an alternative source of magnetic material from coal combustion bottom ash has been investigated. A relatively low cost recovery system has been developed. Dense-medium tests using the bottom ash magnetics revealed a high level of efficiency as indicated by probable error values around 0.03 over the range of medium densities investigated. The results from both the recovery and coal cleaning efforts will be discussed in detail.

Jan 1, 2009

By S. E. Valji

Clay slurries are normally dewatered using flocculents like sulfuric acid or aluminum sulfate. This type of flocculation is based on the electrolytic mechanism. For certain clay dewatering applications, this method of flocculation is unsatisfactory. Flocculation, based on the bridging mechanism, using organic polymers has been utilized to overcome such problem situations. This method of flocculation offers solutions not possible by previous methods. Normally these flocculents are used to assist dewatering. In this case, not only is dewatering promoted, but also further processing is assisted by a change in the dilatant character of the filter cake that is formed. Discharge of filter cake is easier, extrusion of filter cake on to conveyor dryer is possible or improved, and heat transfer and drying rates of the extruded filter cake are substantially higher. Both natural and synthetic organic polymers have been utilized for this purpose. Selection, application techniques, and economics are described.

Jan 1, 1965

By K. F. Unrug

Fractures of sedimentary rocks in the vicinity of the outcrop are commonly encountered around the world. Mine highwalls and numerous highway cuts give excellent views for detailed study of surface fractures. This paper gives an explanation of the origin of fractures as well as characterization of the distribution and extent of joint system with reference to lithologic composition of the rocks. Practical implications of the joint system affecting mine operations are described. Among the subjects discussed are: discontinuous deformation as an effect of surface subsidence, stability of mine portals and near outcrop underground operations, and stability of highwalls, when using highwall miners and strip operations. Some design procedures are recommended that can minimize the problems encountered in mining areas with intense joint systems.

Jan 1, 1994

Residential and commercial plumbers in the United States were introduced to Viega?s copper press technology in 1999. In short, the technology allows plumbers and installers to join copper pipe securely in four to seven seconds on pipe sizes of 1.2 to 10 cm (0.5 to 4 in.) by pressing the connections with specialized tools and fittings rather than through sodering or welding. The water- and air-tight technology, first introduced in Germany in 1989, includes three different sealing elements, a variety of materials and a selection of configurations. By eliminating the need to thread or solder pipe, connections and repairs can be made quickly and securely. Installations are also much quicker and as secure as traditional methods.

Jan 1, 2012

By Steve Kral

More than 124,000 people involved in the mining and construction industries throughout the world poured into Las Vegas, NV in March for ConExpo-Con/Agg ’99. Show organizers said this triennial exhibition is the largest equipment show in the Western Hemisphere and one of the largest exhibition of any industry. “Clearly, Con-Expo-Con/Agg ’99 was one of the largest trade shows of any industry ever held in the Western Hemisphere,” said Bruno Benna, co-chair of the event. Attendees included mining industry representatives, including aggregates, and sand and gravel producers. In addition, many of the attendees work in the construction, reclamation, forestry, asphalt paving, landscaping and concrete industries. According to show records, about 52% of those attending were company presidents, vice presidents, chief financial officers or managers.

Jan 1, 1999

By Martin Herrenknecht

The world?s growing population and rapidly proceeding urbanization are boosting an enormous demand for new and high-capacity infrastructures to secure the mobility of goods and people. Densely populated areas face the challenge to provide efficient traffic infrastructure, such as a modern public transportation system. At the same time, the maintenance and modernization of supply and disposal structures for water, sewage, energy and communication are also essential. Additionally, supra-regional transportation routes such as long distance water diversion schemes are the challenges for the future. All these projects are as demanding as they are characterized by a tight time schedule.

Jan 1, 2010

By J. R. Piper

“Old Borate,” located in the Calico Mountains east of Barstow, California, lead domestic colemanite production from 1884 through 1907. Mineral exploration at “Old Borate” in the early 1980's, examined borate mineralization in Tertiary lacustrine strata. Surface sample and drill hole locations, geology and structure, were hand-drafted on paper maps. To re-evaluate this data, the information was digitized using Geographic Information Systems software. Digital Elevation Model based terrain modeling integrated surficial samples with drill hole data to locate favorable drilling targets. Structural relationships were used to identify hypothetical resources formed by the leaching of boron from surface exposures, redeposited at depth.

Jan 1, 2001

Electrostatically charged water droplets efficiently suppress breathable dust produced during open air rock crushing operations, according to recently completed independent tests conducted for the Environmental Protection Agency. Since a primary rock crusher produces very heavy clouds of dust, this application was selected as an appropriate test site to measure the efficiencies of new "charged fogging" equipment in mining and mineral processing operations. EPA's Industrial Environmental Research Laboratory, Research Triangle Park, NC, contracted TRC-Environmental Consultants Inc. of Wethersfield, CT, to conduct a full-scale demonstration of a recently developed electrostatic fogger, designed to project a charged fog spray at distances up to 15.2 m. Test results indicated overall fogger efficiencies of approximately 70%. The Fogger IV* employed in these tests is reportedly the largest charged logger ever made, with an extremely long operating range. The original fogger was designed for indoor dust control; this fourth generation version is designed for fugitive dusts, indoor and outdoor, and has an operating range up to 15.2 in.

Jan 6, 1981

By L. Sandbak

"CURRENT BASIS OF GROUND SUPPORT DESIGN ANALYSIS The current strategy used in determining what kinds of support are needed is based on empirical design charts (Grimstad and Barton, 1993). Figure 1 is an example of the topcut analysis used for a 14 foot wide (4.3 meter) drift, which is the current design width used for topcuts at TRJV mine. The majority of our topcuts are situated in ore of the Type IV and Type III weak rock class categories that necessitate the use of bolts, mesh and 2”-4” of shotcrete. This type of empirical chart gives excellent guidelines for the kinds of support, and it is based on case histories of civil tunneling and mining properties. It is a good starting point for determining the kinds of support needed, but not to the detail needed to optimize the number of bolts, type of mesh, or combination of types or strengths of shotcrete. This report is an attempt to help quantify the safety factor and optimum design parameters to include mesh and shotcrete as part of the design criteria and subsequent safety factor.SAFETY FACTOR ANALYSIS: BOLTS ONLY One type of safety factor analysis used at TRJV for the past 7 years is described as the “dead weight” method, developed by Pakalnis (2008). It involves the support of a conservative “dead weight” of rock held in place by bolts in which the depth of failure is approximated as a wedge whose height is one-half of the span. The failure or dead weight wedge resembles a triangular wedge that must be supported by the remainder of the bolts going through the wedge (see Figure 2).The support capacity of the system is determined by the bond strength of the bolts holding up the wedge, which is in turn based on the RMR. The method assumes the total support capacity is the sum of the individual bolt values defined by either the breaking strength or the bond strength of the bolts (whichever is lower) passing through the failure surface."

Jan 1, 2017

By F. Kennedy

Consolidation Coal Company (Consol) supports an active R&D effort to improve the safe, productive mining of coal and to utilize coal in an environmentally acceptable manner. Attention will be focused on degasification of coal seams, continuous coal transport systems, earth sciences activities, and coal combustion. Brief mention will be made regarding the SO2 emissions control programs. The research program constitutes about 1.0% of Consol coal sales which positions Consol as the preeminent coal company supporting broad-based research addressing the full spectrum of the various problems associated with utilizing the nation's abundant reserves of economical, readily available fuel.

Jan 1, 1989

By M. J. McPherson

The legislation that prohibits the recirculation of air in coal mines was formulated because of the fear that concentrations of airborne pollutants would rise to dangerous levels. This paper undertakes a simple analysis of the effects of a controlled recirculation system on the gas concentrations in headings. It is shown, through an algebraic formulation and a numerical example, that a properly planned system of controlled recirculation leads to a reduction in the maximum general body gas concentration that occurs in a heading.

Jan 1, 1988

By T. P. Meloy

Understanding the illusive nature of the catastrophic failure of brittle solids is difficult. Proposed is a hypothesis of crack cessation. If, during catastrophic failure, cracks in a brittle solid stop before terminating on a preexisting crack, this hypothesis suggests that the slope of the size distribution curve will be lower. Moreover, this hypothesis suggests that when cracks stop, negative valleys and negative comers appear. Furthermore, particle shapes also change with particle size. While the hypothesis is unverified, it suggests that crack cessation could play a role in the comminution process.

Jan 1, 1996

By Xie Longshui

INTRODUCTION The gold production is from the state-owned gold mines, the local gold mines and the by-product of metal mines. Since 1975, the small gold mines have developed in rapid strides. Currently, there are about 3000 small gold mines in China. Most of them are operated by the local, and the production is about 50% of China's gold output. In the small gold mines, the normalized mining equipments are employed at most of mines, but some mines still use such backward tunnelling and mining tools as pick, shovel and hand hammer etc.. The mining techniques have developed from the primitive to the advanced, especially the methods of open stope, shrinkage and filling have been widely used. Such new mining techniques as bolting, vibrating draw, non-electric ignition and diamond drilling etc. are also introduced in the wall gold mines. In recent years, the development of small gold mines is very fast under the guidance of new mining policy which is ' rapid and great development of large-sized mines, helping small mines to develop, and quick mining for the existing mines; and encouraging the collective and the individual to operate a mine.' GEOLOGICAL FEATURES The gold veins are dominant, which are divided into two types, ie. the mesothermal deposit with altered rock in a crushed zone and the hypothermal deposit with quartz veins. The orebody distribution is not centralized, and the size of deposit and single minable orebody is small respectively. Most of deposit dip at 30° to 50°, characterized by expansion and shrinkage, ramification and compound, thinning out and reappearance, separation and composite at the parallel veins etc.. The ore grade is variable, and the factor of grade change is above 100%. The waste zones with lean or submarginal ore usually exist in deposits. As for the gold deposits with altered rock, the ore boundary is indistinct. Most of gold deposits, particularly the gold deposits with altered rock, are intruded by the late structural rock, thus the faults and joints are developed, and the rock and ore are crushed, especially the host rock of roof wall is very crushed. It ie obvious that the conditions of both formation of deposit and mining are considerably complicated. HISTORY With a long mining history and rich experiences, the local gold sectors are small, but they play an important role in China's gold mining industry. Dated from Xia and Shang Dynasty, the gold goods was made. In the Tang Dynasty, the development of gold mining industry was very fast. A Chinese poem , written by Liu Yuxi -- one of famous poets in the Tang Dynasty, says: As sun is shining over Dengzhou land, The fog on river slowly goes away, The panning girls together meet at bay, The beauty's jewels and stamps of king are gold from river sand. This poem shows the local gold mining was flourishing at that time. In 1888, the local gold mining sectors were all the rage at the moment, and the annual output of gold was as high as 21.5 tons. Since the founding of New China, the development of local gold mining was subjected to several back- sets, but certain advances are made on the whole, especially since 1970. Round about 1970,the simple, backward and indigenous mining was dominant in the small gold mines; for instance, the hand-hammer drilling, the hand-operated winch hoisting and the hand haulage etc.were main methods of gold mining . Up until the late 1970s,great changes took place in stoping, haulage and so on. Currently, some advanced technology and large-sized equipments are adopted in the local gold mines. Generally, the local small gold mining sectors play an important role in development of China's gold mining industry, and are important and attractive sectors. PRESENT DEVELOPMENT

Jan 1, 1987