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By Donald E. Hendrickson

A new prinicple of side dumping front end loading for underground mucking machines has completely changed the concept of underground loading and haulage equipment arrangement both in production and development work loading. Versatility and adaptability of this type of machine permits combinations with a broad range of haulage means not possible with -conventional overhead loaders. Steel "armored" conveyors serving this type of loader are replacing conventional rail mounted car haulage to give a continuous loading operation and effect important economics of reduced manpower, faster loading rates and fewer working areas for a required production. First used in Germany this easy to control and highly efficient means of placing rock from the muck pile on or into haulage means has advanced the art of underground rock loading more in the past three years than any other advancement since the first successful small crawler mounted air powered loader was introduced in 1954. Bucket type loaders with a relative new side dump principle are gaining in popularity for underground loading. They are replacing conventional overhead loaders in present applications and becoming first choice in new ones. Primarily for hard rock development and production loading they are also widely used in production loading of coal and other soft materials. This discussion briefly traces the historical development of hard rock underground loaders to the new side dump type and its present population. In more detail various applications, loading techniques and the advantages of operation, production and economy with the side dumper in hard rock loading will be dealt with.

Jan 1, 1966

By Guillermo V. Borquez

The economics of open pit mine design are dictated by three basic elements: cut-off grade, stripping ratio and slope angle. Although these elements are functions of a number of independent parameters, they are interrelated through their influence on the overall economics. The optimum slope angle is the most uncertain element to determine, because rock mass properties are difficult to obtain. However, for preliminary estimation, the slope angle can be determined from the relationship between the probability of failure and the safety factor. The economics of the slope selected will depend on a profit versus risk judgment. In this paper, the author will present an actual case of application of this postulate.

Jan 1, 1977

By Joel K. Waterland

The Homes take Mining Company at Lead, South Dakota has a yearly production of 1,868,741 tons of ore produced from horizontal cut-and-fill stopes and timber cut-and-fill stopes. This production, in addition to the necessary development (drifts and raises), requires 5,168,271 feet of drilling annually. The rock for the most part consists of quartz; mica schist; and cummingtonite schist; and must be considered as relatively hard. Penetration rates average about 15 inches per minute using an operating air pressure of 100 psi. The rock is tough, rather than brittle, and dulling occurs quite rapidly. The average regrind period is approximately 19 feet per regrind using a 1-7/16 inch carbide bit. At the present time, all drilling is accomplished with 2-5/8 inch bore airleg mounted drills, and 2-3/4 inch and 3-inch diameter bore -stopers (raising only). These machines are all direct striking, with 4-1/4 inch chucks. 7/8-inch hexagonal carbon drill steel with forged collars are used in conjunction with 1-7/16 inch multi-use, threaded, carbide bits. 62,793 rods, and 16,234 bits are used to maintain the yearly production. The number of rods noted are the rods that were sent: underground, both new and reconditioned.

Jan 1, 1963

By G. E. Wasson

Consolidation Coal Co. tested the agglomeration of fine coal using a laboratory pellet mill. The principal operating variables examined were feed coal moisture, coal size distribution, and additives to the feed coal. The moisture of the feed coal was found to be critical to both the pellet mill operability and the product strength. Coals, with feed moistures too high to pelletize, could be pelletized if mixed with lime or a water absorbent material. The addition of dry starch binder improved the product strength.

Jan 1, 1991

By William G. Doepken

GENERAL DESCRIPTION The Henderson mine utilizes a highly mechanized, continuous panel-caving system to extract ore from a deep, massive, molybdenum deposit. The mine site, lo¬cated 80.5 km (50 miles) west of Denver, is situated at 3170 m (10,400 ft) above sea level in a steep valley on the eastern side of the Continental Divide. The mill site, located on the western side of the divide, is linked to the mine via a 15.5-km (9.6-mile) railroad tunnel. Mine production is scheduled to reach 27 215 t/ d (30,000 stpd) from the uppermost production level. This pro¬duction rate will have been reached within the four years following an intensive ten-year preproduction development program. A second production level, due to come on stream in later years, will expand production capabilities to 31 751 t/d (35,000 stpd). The mine, which employs approximately 2000, has blocked-out ore reserves of 220 Mt (242 million st) at an average grade of 0.42% MoS2. Geology The Henderson deposit is composed of two partially overlapping ore bodies that lie 1080 m (3600 ft) beneath the peak of Red Mountain. The ore bodies are entirely within a Tertiary rhyolite porphyry intrusive complex that has intruded Precambrian granite. The de¬posit is elliptical in plan with overall dimensions of 670 x 910 m (2200 x 3000 ft). In section it is arcuate with an average thickness of 185 m (600 ft). The top of the deposit is at an elevation of 2610 m (8700 ft) while the lower limits range from 2340 m (7800 ft) on the west to below 2100 m (7000 ft) on the east. The mineralization is relatively continuous in the ore bodies and consists of molybdenite and quartz in random to subrandom, intersecting, closely spaced veinlets. Cavability RQD (rock quality designation) * values measured from Henderson drill core and compared with the RQD values from the Climax and Urad block-cave mines in¬dicated that the Henderson ore would cave but with difficulty and that a high percentage of the cave ma¬terial would be blocky. Initial caving experience shows the Henderson ore caves easier and with greater frag¬mentation than was indicated by the RQD values. Pos¬sible reasons for this are: 1) The greater lithostatic load at the Henderson has a greater effect on caving and fragmentation than anticipated. 2) The relief of confining pressure due to caving action and brittleness of the rock is enhancing breakage. Mine Layout The Henderson mine layout was designed from its inception for a large-scale, rubber-tired, continuous panel-caving mining system. The ore body is vertically divided into three major mine levels (Fig. 1). The top¬most level (8100 level), which is 2469 m (8100 ft) above sea level, is the current mine production level. The intermediate or 7700 level, which is in the initial

Jan 1, 1982

By C. J. Weiss

"A commercially available Through-the-Earth (TTE) communications system was evaluated at an underground coal mine in eastern Kentucky. This field study was conducted as part of a larger multi-site evaluation of available TTE systems to determine their operational sensitivity. Field testing is being performed along with simulation techniques developed for geophysical surveys. The results of the field test will additionally be used to determine the applicability of these simulation techniques to TTE communications. The mine detailed in this paper was idled at the time of the study, which provided the nearest practical representation of a post-event mine shutdown. For this study, the three following communication modes were tested: surface-to-underground, underground-to-surface and surface-to-surface. Standard deployments of the TTE system using the manufacturer’s recommended procedures were able to achieve clear communications between underground and surface locations. Other arrangements of the units yielded intriguing results, some of which were predicted by computer simulations, others were unexpected. Future experimentation is planned to further evaluate the observed phenomena. INTRODUCTION The ability to establish effective communication between surface and underground personnel after a mine event is essential for both mine evacuation and mine rescue efforts. Current communication technology is reliant on physical infrastructure, such as antennas, cables, and repeaters, located throughout the mine. Such systems are easily disabled during a mine event because of their vulnerability to physical damage. A true emergency communications system would have the ability to function regardless of a mine’s physical state. Through-the-Earth (TTE) wireless communications technology has the potential to provide such a tool. Wireless TTE communications are exceptionally challenging because electromagnetic (EM), or radio, signals are subject to drastic attenuation as they travel through solid strata. In addition to attenuation, EM wave propagation is directly affected by the physical and petrographic characteristics, mineral compositions, metamorphic properties, and the degree of water infiltrations in the strata [1-5]. These strata characteristics are unique to each mine thus making the design of an effective, universally deployable, and reliable TTE communications system very difficult. At present, TTE technology is in the preliminary stages of practical deployment with only a few permissible TTE systems commercially available."

Jan 1, 2015

By Cuthbert Musingwini, Adeodatus S. Nhleko, Mahlomola I. Mabala

Optimization of a three-dimensional (3D) underground stope layout is complex given the number of variables and constraints to consider, such as the stope size. Determination of the appropriate stope size in stope layout optimization problems is a complex process that must consider several factors including placement of infrastructure and development, production scheduling, and equipment selection. An inappropriate stope layout can result in unrealistic expectations for a production schedule, consequently negatively affecting the derived economic value. Therefore, this paper used a dual interchange algorithm (DIA) to evaluate the effect of stope size on the stope layout economic value (SLEV) for a synthetic Platreef mineral deposit planned for extraction using sublevel open-stoping. The results showed that generally as the stope size increases, the SLEV decreases. This aligns with practical mining because larger stope sizes have a higher chance of incurring more dilution which reduces economic value, while smaller stope sizes enable more flexible extraction where unprofitable blocks can be left unmined as waste, thus increasing the derived SLEV.

Jun 25, 2023

By V. T. McLemore

The Wind Mountain (WM) nepheline syenite deposit is part of the alkalic complex in the Cornudas Mountains, which ranges in age from 34.6 ± 1.5 Ma to 36.8 ± 0.6 Ma. The WM deposit consists of a complex, zoned pluton that ranges from syenite porphyry to nepheline syenite porphyry. The WM deposit has potential use for ceramics and dark-colored beverage containers and consists of nepheline, k-feldspar, albite, and varying amounts of other minerals. Analcime also is present locally but must be avoided because it is unsuitable for ceramic and glass. Chemically the deposit consists of 56-63 % SiO2 17-21 % Al2O3 and 4.0-5 % Fe2O3. Although initially iron is high, when the crushed rock is passed through a specialized magnetic separator, the iron content drops to below commercial maximum standards of less than 0.5% Fe2O3. The WM deposit is currently under exploration and testing to determine marketability.

Jan 1, 1994

By J. B. Gwiazda

Maintenance of a constant load setting throughout longwall support units and selection of the proper initial bearing capacity depending on the type of roof strata are the basic factors that ensure good performance of roof support in a longwall. These requirements can only be met by hydraulic support. The greatest advantage of hydraulic support is achieved when uniform pressure is imposed on the roof throughout the length of the longwall. Such support, however, is provided only if each of the support units acts with the same force against the roof, i.e., has the same setting load. In such cases, the roof behaves like a uniform plate without bending and shearing stresses, thereby ensuring an undisturbed structure. Without a positive set value system, achieving an equal setting load for all units of the longwall support is impossible. Due to alterations of the feed line pressure of support units as well as some reasons related to man's psychology, operators extend the height at different setting loads. This produces nonuniform roof stress, and disturbs the structure. Consequently, the roof usually cracks. The author has developed a positive set value system, which is described in this Technical Note. Selection of the setting load Two pressure values in the feed lines are usually applied in longwall hydraulic systems. Lightweight support is fed by 25 MPa (250 bar) liquid, while heavy duty units receive a nominal pressure of 31.5 MPa (315 bar). Such pressure is required not only for the props but also to power the adjust¬ment jacks and the advancing ram. If the feed pressure is too low, there will be difficulty in shifting the unit despite the inversion system of the advancing rams. On the other hand, for many roof types, the feed pressure often appears to be too high when applied as the setting load pressure. An excessive setting load acts too strongly against the roof, crushing weak strata close to the roof. The author has recognized a case where an excessive setting load destroyed not only the nearby roof strata but also the strata above a 2-m (6.6-ft) sandstone layer. In addition, an excessive setting load relieves the side¬walls, increasing the resistance when using cutting machines. As a result, the yield of coarse coal is diminished, and increased fines dominate in the final product, lowering its economic value. As indicated, selection of the proper setting load, depend¬ing on the mining and geological conditions of the extracted seam, is extremely important. In some mines, measures applied to prevent disturbances include reduction of the feed line pressure by adjusting the feed pump valve. The disadvantage accompanying reduced feed line pressure is more difficult operation in advancing the ram. Due to the reduced feed line pressure, the force of the advancing ram is much lower than the designed value. Other designs suggest using a third feed line. However, installation of supplementary valves on the support units is required, a time-consuming and expensive procedure. The disadvantages of the powered supports are eliminated by a system designed by the author. So far, such a method of setting load control has not been used in any type of support. Setting load control unit The designed positive valve set for prop loading and the setting load control correspond to existing control systems for hydraulic powered support. The layout of the unit connected to the hydraulic prop control is presented in Fig. 1. The unit is marked LIDS. It incorporates three valves that may operate separately or connected. Valve A automatically opens and closes with liquid flow in the prop feed circuit. The valve is opened when the canopy touches the roof and closed when the support unit is withdrawn. Valve B serves as the setting load control. Valve C automatically opens and closes the flow in the line connecting the under-piston space of E to the prop F with the separator G. The valve block of each support prop is marked BZ. The UDS unit is connected by the hydraulic lines to the F prop control circuit. A valve is connected by H to pressure line J and by K to the G separator. In the UDS-3 version, line L is connected to M, linking the over-piston space of F prop with the G separator. Valve B is linked with valve A by a connector; it is also connected to the under-piston space E of prop F by line P. Valve C is fixed between lines K and P, connecting space E of prop F with the separator G. When setting the support, the liquid flows from line J through separator G, the BZ valve, and valve C to the space E of prop F. When reaching the roof with the canopy, valve A is opened and C closes. In this way it is impossible for the operator to cause the liquid pressure in space E of prop F to reach the level of line J. The prop pressure is set by valve B of the UDS unit. When withdrawing the support, valve C is automatically opened and A closed. Three UDS units have been fabricated and are designated

Jan 1, 1990

By James G. Tilton

Subsidence resulting from mining operations, has been the object of sporadic study for many years. Reports have shown that subsidence has ranged from minor settlement detected only by precise measurements to great slips where buildings are destroyed, roads disrupted, and large fissures opened at the surface. For years, a controversy has raged over the question of whether there is a positive or negative angle-of-draw. None of these questions can be given a flat answer for the variables controlling, subsidence are infinite. Generalizations can be made for various situations and areas but some means of control must be executed.

Jan 1, 1966

By Keith G. Wallace

Coal mine ventilation systems are often subject to high leakage rates. As a result, changes in airflow resistance will strongly affect the efficiency with which air is delivered to the working place. One major source of airflow resistance is the line brattice used to direct air from the last open crosscut to the working face. Because it is a great distance from the fan, the resistance of the line brattice can result in more overall leakage than an equivalent resistance closer to the fan. Substituting auxiliary fans for brattice eliminates this source of resistance, with improvements in system efficiency and cost. Also, in some mines, the leakage that leads to spontaneous combustion can be reduced. The benefits obtained by several different brattice and fan substitutions have been studied by Mine Ventilation Services, Inc., under contract to the Bureau of Mines. Changes in main fan duty were compared with additional costs associated with auxiliary fans. Results indicate that in some circumstances, considerable leakage reductions and cost savings are possible.

Jan 1, 1986

By Peter F. Mataich

The phosphate mining industry is a highly competitive one, one in which survival depends on the plant's ability to produce at costs equal to, or below, the competition. The solution toward getting costs down is usually one of scaling up the plants to get the most tons through at the lowest possible cost. Control of these plants has been an art. Few of them are well instrumented because until a few years ago reliable instrumentation was non-existent. International Minerals and Chemical Corporation was a pioneer in applying computer techniques to ore reserves analysis and mine planning and the success in these areas led to the question of whether we could not extend the advantages of computer processing into the plant itself. There was a great deal of doubt on the operator's end that this could be done successfully because of the lack of instrumentation and the fact that plant control was largely an art that was learned only after many years of experience. However, in 1965 the instrumentation picture began to look up and the new generation of process computers just coming on the market were considerably lower in cost than the previous ones. A preliminary study of the installation costs and the probable benefits that could be realized from computer control convinced us that a process control computer should be seriously considered for a new phosphate mining plant which was being designed.

Jan 1, 1969

By C. Van Landingham, A. Bailey, R. A. Schoof

A residential metals abatement program has been underway in Butte for more than 20 years. More than 1,350 yard and attic cleanups were completed by the end of 2018; most triggered by lead. While the focus is on remediation of residential soil and house dust, the program also includes a blood lead monitoring program with identification and abatement of additional sources of exposure for children with elevated blood lead levels (BLLs). As specified in the remediation program, studies are being conducted every 5 years to assess BLL data collected from Butte children. The first two studies have evaluated over 6,000 BLLs from 2003 through 2017 and evaluated trends over this time period, by Butte neighborhood, and as compared to areas outside of Butte. These studies showed that rates of elevated BLLs (i.e., those above 5 µg/dL) in Butte children have declined dramatically since 2002 but have been declining much more slowly since 2011. Improved rates of confirmation testing are needed to verify the rates of elevated BLLs. While the RMAP likely has contributed to these declines in BLLs the magnitude of impact cannot be quantified.

Mar 2, 2022

By A. V. Castelli

The provinces of Guangxi, Guizhou, Hubei (and most recently Fujian) were the prime exporters of barite during this period. Guangdong and Shandong were exporters too but not major participants. These are all primarily agricultural areas so there existed a sufficient labor force willing to work in the mines to supplement their income from farming. During the early years, barite export pushed the existing transportation systems in these provinces to operational capacity. The mines from which this barite is extracted are located about 250 to 1,400 kilometers from the sea ports. Transportation of the ore from the mines to the ports follows a net-work that includes trucking to various rail-heads where it is then shipped via freight trains to ports for loading into seagoing vessels. in some instances, the barite travels by truck or train to the Yangtze River where it is then barged to an ocean port.

Jan 1, 1990

By K. Getsos

Western Greece is a favorable site for exploration and discovery of oil fields. The most important potential source rocks seem to be all the rocks deposited before middle Jurassic under special circumstances, such as reducing conditions, which allowed preservation and maturation of the organic material. In general all the rocks of middle Jurassic to Paleogene are not favorite source rocks. The porosity type was studied on fifty samples using scanning electron microscopy (SEM). Potential reservoir rocks are the porous Paleogene wackestones-packstones with boring, channel and vuggy porosity type. Finally seal rocks are the impermeable mud-stones and wackestones of Jurassic, Cretaceous and Paleogene age. These rocks consist of micrite and whole sells of foraminiferas and the porosity type is mainly intercrystal/interparticle. A Total Organic Carbon (TOC) analysis, conducted on seventy samples using a wet oxidation method, has revealed an extremely low TOC content (less than 0.05 %). This amount is by far less than the minimum organic content amount, required for source rock characterization and characterizes all the rocks of middle Jurassic to Paleogene age. Additionally, 18O and 13C stable isotope analysis was contacted and the results are given in d values. All the rocks within the studied time interval have much lower d values than petroleum source rocks. Clay mineral content was studied in almost seventy samples. As is indicated by the clay mineral content the studied rocks have reached up to the Middle Diagenesis and the temperature during diagenesis was rather low.

Jan 1, 2006

By R. Fedel-Moen, R. W. L. Kimber, B. D. Williams, S. R. Ragusa

The use o f cyanide to extract gold from ores is widespread. In the process of extracting gold, cyanide may form metal cyanide complexes with a variety of other metals present in the ore. This study was carried out to investigate the biodegradation of the Cu(I)-cyanide complex and tetracyanonickelate under varying pH and nutrient additions. Detailed studies using shake flask cultures and bioreactors showed that naturally occurring bacteria residing on gold-leach-pad ore uti¬lized the Cu(I)-cyanide complex (CuCN) and tetracyano-nickelate, Na2(NiCN4), as carbon and/or nitrogen sources. Ammonium-nitrogen (NH4+-N) and/or cyanate (CNO-) accumulated in solution as the metal cyanide complexes were degraded. The accumulation of cyanate as a product is a concern due to its toxicity. Degradation rates were increased if a growth substrate (peptone, 0.1%) was added to the medium or if bioreactors were primed with peptone before addition of the metal-cyanide complex. Tetracyanonickelate was degraded at pH 8 without added peptone, but it was not degraded at pH 10. The addition of peptone was required for degradation of the Cu(I)-cyanide complex at pH 8 and pH 10. At pH 8, the addition of peptone resulted in the accumulation of cyanate, whereas, at pH 10, cyanate was not detected in the cultures. Biodegradation of metal-cyanide complexes was faster (approximately 1.5 to ten times faster) in bioreactors than in shake flask cultures. The addition of peptone was not required for degradation of metal-cyanide complexes in bioreactors. However, priming the bioreaetor with peptone resulted in higher metal-cyanide degradation rates over multiple cycles.

Jan 1, 2000

By Gösta W. Diehl

During the past five years the use of all-hydraulic drilling equipment has increased rapidly, and we have now reached a point where the hydraulic drill has become an alternative to be seriously considered for every drilling operation. The hydraulic drills have many advantages over pneumatic drills, but they also have certain characteristics, which makes a potential user hesitate before making the switch. And when the decision to use hydraulic drills has been made, the user then faces another choice of equal difficulty: the choice between different hydraulic systems. This paper discusses some of the factors to be taken into account when considering hydraulic drilling equipment for rapid tunneling in hard to medium hard rock. THE CHOICE BETWEEN HYDRAULIC AND PNEUMATIC EQUIPMENT The choice between a hydraulic and a pneumatic drill is much more than just that: It is a choice between two different systems. The choice is usually based on the productivity, economy or ergonomy of the system. However, also other factors should be considered, such as service capabilities and training requirements. And finally the choice will be influenced by the need to acquire know-how in the new technology. Productivity If the prime consideration is to achieve the highest possible tunneling speed, then the high penetration rates of the hydraulic

Jan 1, 1979

By Raphael G. Kazmann

The predicted warming of the earth's surface, presently the subject of much debate, controversy and legislation, is based on what is termed "the greenhouse effect." This is the result of the property of certain atmospheric gases. These gases allow the passage of radiant energy to the earth's surface and reflect back, to the earth, the infrared radiation given out by the heated surface. Physicists have computed that if there were no greenhouse effect the average temperature of the earth, now about 15° C (60T), would be close to -18° C (OT). Just what gases have produced this salubrious effect? Water vapor is the most important. Then come carbon dioxide, methane and a number of minor constituents of the atmosphere, both natural and man-made. Climate change, its cause and its impact on human activities have been the subject of scientific and historical study for more than a century. Recently, some scientists have concluded that if the man-made increase in the carbon dioxide and other greenhouse gases continues, by the late 21st century the earth's global average temperature will rise between 2° to 8° F. This temperature rise would cause the water in the oceans to expand and the massive polar glaciers to melt. In 1980, it was predicted that the sea level would rise 7.6 m (25 ft) by the late 21st century. By 1985, the predicted rise was 1 m (3 ft); and by 1989, it was 0.3 m (1 ft) (Jastrow, Nierenberg and Seitz, 1990). Agricultural scientists have pointed out that an increase in atmospheric carbon dioxide would enhance biological growth including the production of foodstuffs.

Jan 1, 1992

By Karin Bäppler

A new polyhalite fertilizer mine is currently being developed in the UK by Anglo American Crop Nutrients. The project includes the construction of a Mineral Transport Tunnel almost 37 kms long to house a conveyor belt that will move polyhalite from the production shaft at the mine to a materials handling facility at the port. The project sets a new standard in terms of an ultra-long tunnel drive and sustainable, environmentally friendly and efcient material transport. The paper highlights in particular the . m diameter TBM in use for the construction of the ultra-long tunnelling section.

Jun 23, 2024

By Thomas Gleason

Wet scrubbing of fine coal from Thermal dryers poses a number of problems in adapting the gas cleaning equipment for required clean-up of the fine particulate matter. Among then are: 1. The dust In the gases leaving the Thermal dryer cyclone-s is often extremely fine with high percentages of the total dust loading less than one (1) micron in size. 2, The flue gas entering the scrubber is corrosive since the coal fired in the thermal dryer furnace is in the range of 0.7% by weight sulphur or higher. Therefore comparatively high cost stainless steel alloys or corrosion resistant linings are required for a satisfactory service life. 3. Requirements for residual coal loadings leaving the gas e scrubber are continually being lowered while modern coal preparation operation is imposing heavier burdens on the collection system through introduction into the Thermal dryer system of very fine coal previously not recovered. The advent of flotation systems in increasing numbers is typical of this trend 4. The installation of a scrubbing system on Thermal dryers is made primarily to reduce air pollution and product recovery value is of little or no value. Therefore the operating costs, that is, of gas pressure drop and water requirements must be held to a minimum.

Jan 1, 1962