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By R. S. Sandhu, S. H. Advani, J. K. Lee, B. L. Aboustit

A comprehensive finite element formulation for thermo-elastic consolidation based on a general variational principle is presented Sample one dimensional problems associated with isothermal consolidation, heat conduct ion, and thermo-elastic consolidation are presented. In addition, evaluations of thermo-elastic consolidation for an underground coal conversion field site are conducted.

Jan 1, 1982

By A. B. Holland-Batt

The application of Reichert spirals and cone concentrators within the South African mineral industry is discussed, and the procedures used in the acquisition of design data are outlined. Computing techniques developed by Mineral Deposits Limited for the processing of test data for use in the design of production circuits are described.

Jan 1, 1982

By Dennis Dobson, Keith M. Henderson

Lone Star Industries, Inc. in Cape Girardeau, Missouri operates an open pit mine to produce limestone for its portland cement manufacturing plant. The present mining method, for safety and legal reasons, requires a set back from the property line, a berm, sloped overburden, and vertical rock walls with catch benches.

Jan 1, 1997

By J. B. Hiskey

Heap leaching has in recent years been established as an important processing alternative for gold and silver. Currently, heap leaching accounts for about 25% of primary mine produced gold and 10% of primary silver. This paper reviews gold and silver heap leaching practice and surveys major operations in the United States.

Jan 1, 1984

By Mark W. Cadwallader

Heap leach mining requires liners in order to contain leaching solutions for both economic and environmental incentives. The use of HDPE geomembrane liners for heap leaching is discussed in this paper. Comparison is made to clay liners, with inclusion of economic considerations. Several heap leach projects incorporating geomembranes are discussed.

Jan 1, 1987

By Lawrence A. Roe

The magnetic reflux classifier, which utilizes the combined effects of magnetic fields and a hindered settling classifier, is a new tool for determining the quantity and quality of middlings in fine-sized magnetite concentrates. Results are given for processing a typical taconite ore, and a sketch of the apparatus is included.

Jan 3, 1953

By Emmanuel Detournay, Charles Fairhurst

A method is proposed for computing (a possible solution of) the ground reaction curve, for use in tunnel support analysis, in cases where the initial stress field is not hydrostatic. Rock around a circular tunnel is assumed to behave as an elasto-plastic material with a Mohr-Coulomb yield envelope.

Jan 1, 1982

By J. M. Keane, C. K. Chase

Critical to successful dump and heap leaching of copper is an adequate evaluation of applicable parameters. This paper deals with methods to establish optimum conditions for dump and heap leaching copper so that commercial operations can proceed. Discussion is also offered of ore occurrences and preparations for dump or heap leaching.

Jan 1, 1988

By Joseph P. Lyden

In the Picher field, structure made openings for the circulation of the mineralizing solutions by flexing, shearing, and fracturing the sedimentary beds. This structure is used with the spatial and genetic relationship of the ore minerals, sphalerite and galena, and the gangue minerals, dolomite and jasperoid, in prospecting for ore bodies.

Jan 12, 1950

By Bill Paysse, Lyle Ruffle

My intention is to produce a video, pictorial, and oral presentation on utility blasting, primarily power pole holes and ditches. Included will be blasting for a take-off structure inside of Wanapum substation, jointly owned by BPA, PSE, and Seattle City Light, and blasting for 230kV steel tower foundations.

Jan 1, 2007

By Michael J. Bertoldi

The purpose of this Bureau of Mines report is to describe the methods and establish the basic economics for dragline, shovel-truck, and scraper mining systems. An overall view of the techniques of preliminary design and the cost involved is presented. Considerations of equipment selection, emphasizing short-range evaluation of required equipment, and a long-range evaluation are considered at a constant production rate over the life of a hypothetical mine. Separate cost analyses for each system were based on 1977 equipment prices, prevailing wage rates, and associated mining costs. Specific engineering and cost breakdown for such items as access roads, transmission line installation, rail spurs, etc., are beyond the scope of this report.

Jan 1, 1977

By R. H. Oitto

To determine whether reflectors could substitute for the trip lights referred to in the Federal Mine Safety Code, the Bureau of Mines studied trip safety devices under simulated haulageway conditions. The noticeability of reflectors compared with trip lights and fluorescent panels was evaluated from distances of up to 850 feet with light source intensities of up to 1-6 foot-candles (ft c). Reflectors tested consisted of a reflective lens in a holder secured to a frame that can be attached to a trip. Reflectors were found to be suitable for use as a trip safety device. In fact, for the conditions in many underground haulageways some reflectors would be more effective than a permissible trip light.

Jan 1, 1968

By Z. G. Tao, Y. Y. Peng, W. L. Gong, M. C. He

"This paper presents an overview of the major landslide hazards in open pit mines in China, the currently used landslide control and monitoring techniques, and development of a new slope control technique incorporating the reinforcement, sliding force monitoring, remote sensing and forecasting in one system in order to constrain the displacement of the sliding blocks in the landslide to minimized the influenced area and provide precise warnings timely for the imminent landslides. For implementation of the new technique, a novel rock cable with large deformation and high resistance (also known as HE cable) was developed, which can elongate as long as 2m. At the same time, the necessary and sufficient condition for initiating a landslide and energy balance equations are formulated. Based on the proposed mathematical models and Beidou satellite system, the software and data transmission hardware for remote sensing and forecasting were developed the new landslide control technique has been applied successfully in 245 landslide sites in 12 provinces across China. In this article, two practical application cases in the open pit mines are reported.INTRODUCTIONChina is one of the countries in the world with the most widely distributed landslides and suffering the heaviest damage. According to the incomplete statistics, landslide hazards have caused death of hundreds of people and direct economic losses of several hundred million RMB each year. The landslide hazards have a great impact on the life and property safety of the people, safety of the infrastructure, as well as the social stability. Thus development of new techniques for forecasting and prediction of the landslides is imperative and of great importance. In general, the forecasting and prediction of the landslides consists of three major aspects, i.e. sliding time forecasting, landslide activity intensity forecasting and landslide hazard degree forecasting. Since a considerable part of the landslide-suspected area are adjacent to the residential areas or important infrastructures, development of the advanced landslide control and monitoring techniques to cope with the sliding time forecasting problem is more important.Over the past one hundred years, the most widely used slope monitoring techniques are based on displacement monitoring (Xu, et al. 2007; Toshitaka, 1998). In the early days owing to the limitation of the technology and equipment, the ground surface displacement and underground water level change were inspected mainly by man power for inferring the possibility of a landslide. In recent several decades, more and more ground surface displacement monitoring devices were brought to the market, such as the automatic total station, theodolite, digital level, borehole inclinometer and GPS based instruments, etc. Based on these modern techniques, some advanced instruments have been developed and applied to the landslide monitoring, for example, the “landslides early warning monitoring system” (Leonardo, et al. 2002), the “In-SAR” technique (Reevea, et al. 2000), the GPS and satellite geodetic survey based technique (Reevea, et al. 2000), and real-time telemetry technology (Xu, et al. 2007). These monitoring approaches have made significant contributions to the landslide disaster monitoring and forecasting. The major limitations for the ground surface displacement monitoring techniques are lie in the inconsistence between the displacement in ground surface and that in the sliding surface for the sliding mass, resulting in low degree of forecasting accuracy."

Jan 1, 2015

By A. Chieregati

"A heterogeneity study was conducted at Erdenet Copper Mine in Erdenet, Mongolia, to determine the fundamental sampling error associated with blasthole sampling. Using a custom designed sector sampler, six large blasthole samples were collected to perform the test that was developed by Pierre Gy, to estimate the constitutional heterogeneity factor for several types of ore. The study investigated the entire sampling protocol, from mine site to analytical laboratory, and quantified the contributions to fundamental sampling error (FSE) of the various stages of sampling and sample preparation. The total relative standard deviation (RSD) of sampling error was determined to be ±32% and ±49.4% for copper and molybdenum respectively. A classical statistics analysis conducted on the data confirmed the level of RSD. About 95% of the sampling error was produced from only one step in the sampling protocol: when the 1 kg sample was reduced to 50 g sample for chemical analysis. Therefore, it is recommended that the 1 kg sample be reduced to 50g using a slightly different protocol to minimize the FSE. The 1 kg sample should be first crushed to 0.2cm size. A 250g split should then be taken and fine ground. A 50g split should then be taken from the 250g fine ground split. These two simple steps will reduce the FSE to ±7.9% and ±17% for copper and molybdenum respectively. The modified sampling protocol effectively reduces the probability of misclassification of low grade ore to zero. INTRODUCTION The Erdenet copper-molybdenum open pit mine is located in Erdenet, in Orkhon province, Mongolia. The Erdenetiin-Ovoo copper-molybdenum deposit is between 1.5 and 3 km wide, and about 25 km in length (Erdenet Mining Corporation, 2016). Chalcopyrite, bornite covellite and chalcocite are among the major minerals found in the deposit. The mine processes approximately 26 million tons of ore annually. A study was conducted to evaluate the fundamental error associated with the blasthole cuttings and sampling protocol at the mine. The open pit mine uses 215mm diameter Russian drills to drill 17.5m holes for 15m benches. The total weight of blasthole cuttings for a 215mm diameter hole and 15m bench height is between 1.5 and 2 tonnes. This amount of sample is difficult and time consuming to collect and analyze. Therefore, a sector sampler was designed for the Russian drills to collect large samples that were representative of the blasthole cuttings (Ganguli et al., 2016). In order to eliminate the delimitation and the extraction errors, researchers consider sector samplers to be ideal for sampling blastholes (Pitard, 2008; Chieregati and Pitard, 2009). This method was intentionally more rigorous than the blasthole sampling protocol at the mine to ensure that the blasthole cuttings were properly sampled. This study was part of a broader study that also looked at the relationship between particle size and grade. The samples collected by the custom designed sector sampler were very large (195 kg on average), and therefore, sufficient for both studies. The relationship between particle size and grade has been reported in Ganguli et al. (2016)."

Jan 1, 2017

By Edward H. Robie

SUBJECT to formal Board approval in September, AIME dues will continue indefinitely at the present scale of $20 for Members and Associate Members; and $12 for Junior Members for the first six years of such membership, thereafter $17. That is the wish of the Board of Directors and the will of the membership, as expressed in the recent referendum. Though the official returns, as reported by the tellers, are not available as this is written, the data are sufficiently complete to give the results to the nearest percent. The total vote was approximately 93 pct for continuance of the present scale. Metals Branch members voted about 94 pet for continuance; Mining Branch members slightly less than that; and Petroleum Branch members about 91 pct. As in the referendum of 1949, there was no particular difference of opinion on the question of dues as between the three Branches. The percentage of ballots returned was about 61 pct, only slightly more than in the 1949 referendum. But the affirmative vote was much greater, 93 pct against 78 pet in the earlier referendum. Looked at another way, a majority of those to whom ballots were sent, 56 pct, voted to continue the present scale of dues, whereas only 46 1/2 pct of those canvassed voted to raise the dues in the previous referendum. But approximately 600 , members expressed their opinion that the dues should go back to $15 for Members and Associate Members and to $10 and $15 for Junior Members. This is a substantial group of members who either do not think they are getting their money's worth from AIME membership, or believe that a more businesslike conduct of Institute affairs should provide current services at less cost, or believe that more service is being provided for their dues than they need. As to the first point, it is probable that some members are not getting their money's worth. They perhaps have only a fringe interest in. AIME activities, or they do not or cannot participate in such activities at the Local Section, divisional, or national level, so that all they get out of the Institute is the monthly journal, which they do not have time to read. If they did read it intelligently, and acted upon the professional information thus gained, it is difficult to understand how one or more ideas cannot be gained that would be worth $20 to them professionally. But the 600 members who want lower dues offer a challenge to the Directors and to the staff to do a better job; to make Institute membership so rewarding that every. member will be thoroughly satisfied. Twenty 1935 to 1939 dollars are worth only $11.60 now, according to the latest government data, but that makes it all the more necessary for us all to appraise the value of what we buy. To the 93 pct of Institute members who expressed a vote of confidence, so to speak, the staff, and we feel sure the Directors as well, are most appreciative and thankful.

Jan 1, 1952

By R. H. Cox, A. S. Allen, James Paone

The southwestern Illinois communities of Belleville and Maryville lie within the greater metropolitan area surrounding St. Louis. Missouri. They also lie within that part of the Illinois coal basin where the Number 6 coalbed has been mined for more than a century. About half the coal was left as pillars to support the ground surface. Years later, however, damaging movements are affecting buildings, streets, and public utilities in some areas. They are generally believed to be related to abandoned mine workings. The threat of continued or increasing incidence of damage raises the need to explore other subsidence-control measures for protecting affected areas with high population density. Because of experience gained in a subsidence-control program of backfilling abandoned coal mines in the Applachian region and in Rock Springs, Wyoming, the Bureau of Mines was called upon to investigate the subsidence occurrences at Belleville and Maryville, and recommend protective measures. Funds ware appropriated for the Bureau to initiate subsidence-control projects at two residential sites in Belleville and one in Maryville. Subsurface investigation of the sites by diamond core drilling revealed two conditions that differ from those encountered at most sites of previous subsidence-control projects. The mine workings were found to be dry and the mine floor consisted of soft underclay which characteristically loses strength with increase of moisture. It had been anticipated that water would have percolated into the mine workings at one .or more of the sites through cracks resulting from subsidence. Under such conditions Bureau engineers believed that injection of mine waste by the pumped; slurry technique3 would provide support and stabilize any movements initiated by the softening of the clay. With discovery that the underclay deposits at the three sites have apparently not been exposed to water since the mines were operating, hydraulic backfilling of any type was considered inadvisable on the basis of present knowledge. To avoid introducing water, a portable pneumatic system is being devised for injecting minus 0.01 27 m (1/2 in.) mine waste into the mine workings. Machines for pneumatic backfilling have been used in Europe not only for subsidence protection but also for strata control, for reducing spontaneous combustion and methane accumulation, and as a means of waste disposal. The Bureau experimented with a pneumatic machine in the Northern anthracite field of Pennsylvania in the 1950's. Previously pneumatic machines have been installed in active mine workings discharging from horizontal pipelines which conveyed air- borne material into rooms to be filled. In the present adaptation to abandoned mines, the machine and air compressor will be operating at the surface, to impel material vertically down injection boreholes with sufficient air pressure to disperse fill material laterally in mine workings at the base of injection holes. Large diameter access and ventilation boreholes will be provided at one site for entry into mine workings to observe backfilling progress. The Belleville and Maryville projects are part of the Mined Land Demonstration Program of the Bureau of Mines. The Illinois State Geological Survey and Department of Mines and Minerals are furnishing technical support.

Jan 1, 1979

By D. C. Jones

The term "coal-mine mechanization" is definable in several ways. In its general application it can mean the use of machines instead of manpower in each of the various mining activities necessary for the production of coal—so that under this definition a mine that uses mechanical coal cutters could be classed as a mechanized mine. Common usage, however, insists that a mechanized mine is one in which machines are used for the entire process of mining or extraction and transportation of the coal. For the purpose of this paper, then, the second definition of "coal-mine mechanization" will be used, and practices employed in mines where the greater part of the production is obtained through the use of mechanical loaders and conveyors will form the basis for this discussion. Physical Contact Hazards If we were to group all the hazards that accompany the use of mechanized equipment in a mine, the predominant class would be that which, for want of a better name, might be termed the "physical contact" hazards; that is, all the sources of danger that lead to accidents through physical contact of workmen with machines. A survey of accidents in a group of mechanized mines indicated that this class of hazards may be responsible for more than half the number of accidents in mechanized mining. For example, of 21 mining-machine accidents at one mine, 14 were of the physical contact type; of 14 loading-machine accidents at the same mine, 8 were the result of physical contact. Certain of these hazards are controllable through the use of guards— a guard over the cutting-machine bits when the machine is being trammed from place to place, or a chain or some similar locking device around the cutter chain, so that an accidental blow or push against the bit control will not cause the cutter chain to move. Other hazards, such as the possibility of a loader operator having his foot crushed by a crawler tread, or a brakeman being hit by a loader boom swung too far to one side while a car is being loaded, might be subject to control through the use of guard devices, but the reduction or elimination of all physical contact hazards by such methods does not appear feasible. Every accident of the physical contact type should he investigated to discover whether guards could have prevented it, but often the only way in which to combat these hazards will be through the awakened consciousness of each workman as to the danger that exists if he indulges in unsafe practices. A good approach to control of accidents in any mine is the establishment of a set of safety rules or operating rules. The intent of such rules is to provide guides far the workmen to follow in the operation of equipment. Frequently the workmen have no regard for such rules, and observance is obtained only through compulsion on the part of management. An interesting development in connection with-the formation of safety rules occurred during a training program for employees in the

Jan 1, 1947

By G. R. Love

i\ program has been written which allows fully automatic conversion of data for X-ray intensity, as a function of time, to finished conventional pole figures. The program accepts input data in the serial order in which they are taken and is therefore immediately compatible with automatic data-acquisition devices. From these data taped instructions are prepared for the Calcomp plotter to construct ink-on-paper drawings. Because both Siemens and Norelco pole figure goniometers are used in this laboratory, the program was written for pole figure data obtained from one or more interpenetrating spiral scans during which both the polar angle, @, and the equatorial angle, a, are varied simultaneously and continuously. The reference direction for a scan, that is the point @ = 0 deg, may be chosen coincident with either the normal direction (N.D. figures) or the rolling direction (R.D. figures). In either case the plotted figures are drawn with the transverse direction (a = 0 deg) at the right and the rolling direction at the top. The full, circular, pole figure is drawn as two semicircular figures labeled "front side" and "back side". As presently constituted, the program will also accept data from circular scans taken at constant values of @. In every case the angular coordinates of each intensity entry are generated in the computer from a relatively small number of auxiliary data. The X-ray intensity data are corrected for background scattering by direct subtraction of the intensity measured with 28 set appropriately "off" the Bragg angle. It is possible to enter this correction as an additional spiral scan through the a, @ space; because the background correction does not normally vary rapidly enough to warrant this detailed a determination, the background corrections are entered as one or more auxiliary data. All data are normalized to a multiple of random intensity. The data taken in this laboratory for N.D. figures are normally taken in a reflection geometry from from sheet samples and do not extend beyond <p = 75 deg; for these data random intensity must be determined from separate experiments and entered as auxiliary information. When the auxiliary information is not available, a number is chosen to give intensity values normalized to a scale of 1 to 10. In this laboratory, R.D. figures are based upon hemispherical samples for which data are taken out to @ = 90 deg; for these data random intensity is calculated by direct numerical integration of . sin @ d@ using the trapezoidal rule and the background-corrected values of the input data. Points necessary to the construction of the pole figure are identified by simple linear interpolation between adjacent data points to determine the loci of contour lines. Points lying on a given contour are connected to one another with straight-line segments and the search-calculation-drawing sequence is patterned to assure that different contour lines do not cross, that a single line does not branch, and that lines do not end in space. However, so that there be no ambiguity in the data presentation, all contour lines end at the limits of the input data. Since the curves are constructed of straight-line segments, they are not continuous in their derivatives. However,

Jan 1, 1969

By D. C. Jones

The term "coal-mine mechanization" is definable in several ways. In its general application it can mean the use of machines instead of manpower in each of the various mining activities necessary for the production of coal—so that under this definition a mine that uses mechanical coal cutters could be classed as a mechanized mine. Common usage, however, insists that a mechanized mine is one in which machines are used for the entire process of mining or extraction and transportation of the coal. For the purpose of this paper, then, the second definition of "coal-mine mechanization" will be used, and practices employed in mines where the greater part of the production is obtained through the use of mechanical loaders and conveyors will form the basis for this discussion. Physical Contact Hazards If we were to group all the hazards that accompany the use of mechanized equipment in a mine, the predominant class would be that which, for want of a better name, might be termed the "physical contact" hazards; that is, all the sources of danger that lead to accidents through physical contact of workmen with machines. A survey of accidents in a group of mechanized mines indicated that this class of hazards may be responsible for more than half the number of accidents in mechanized mining. For example, of 21 mining-machine accidents at one mine, 14 were of the physical contact type; of 14 loading-machine accidents at the same mine, 8 were the result of physical contact. Certain of these hazards are controllable through the use of guards— a guard over the cutting-machine bits when the machine is being trammed from place to place, or a chain or some similar locking device around the cutter chain, so that an accidental blow or push against the bit control will not cause the cutter chain to move. Other hazards, such as the possibility of a loader operator having his foot crushed by a crawler tread, or a brakeman being hit by a loader boom swung too far to one side while a car is being loaded, might be subject to control through the use of guard devices, but the reduction or elimination of all physical contact hazards by such methods does not appear feasible. Every accident of the physical contact type should he investigated to discover whether guards could have prevented it, but often the only way in which to combat these hazards will be through the awakened consciousness of each workman as to the danger that exists if he indulges in unsafe practices. A good approach to control of accidents in any mine is the establishment of a set of safety rules or operating rules. The intent of such rules is to provide guides far the workmen to follow in the operation of equipment. Frequently the workmen have no regard for such rules, and observance is obtained only through compulsion on the part of management. An interesting development in connection with-the formation of safety rules occurred during a training program for employees in the

Jan 1, 1947

By William J. Miles, Raymond E. Blair

The oil and gas drilling industry is the largest user of "functional" industrial minerals for well drilling and completion. (Functional industrial minerals can be defined as those used for performance characteristics rather than composition.) This industry&apos;s use of industrial minerals involves complex mining, processing, and distribution of products. The cost of these products at the well site reflects the complexity of distribution to typically remote locations and the cost of service. Table 1 illustrates the use of functional industrial minerals by the drilling industry. The total tonnage shown is almost 2 1/2 times larger than the 3.3 Mt (3.6 million st) of kaolin used by the paper industry for filling and coating, another major use for functional industrial minerals. Drilling fluids are an indispensible part of a drilling operation. These fluids perform several functions simultaneously. They cool and lubricate the drill bit, remove formation cuttings, increase the specific gravity of the fluid to counteract formation fluid pressures, provide a filter cake on the wall of the drill hole to prevent drilling fluid loss to the formation, protect the porosity of producing zones, and prevent reaction of the formation or formation fluids with the drilling mud. When porosity of a formation exceeds the ability of the drilling fluid to form a wall cake, it is referred to as lost circulation. Because these fluids are being constantly formulated for changing formation conditions, they require a skilled technician or drilling mud engineer on the site at all times. Drilling fluids are composed of oil or water as the liquid phase, and industrial mineral products and chemicals to control chemical and physical properties. The basic function of viscosity and suspension result from the use of gelling clays and chemical and mineral dispersants; specific gravity of the mud is adjusted with mineral weighting agents; filtration control is maintained by clays and various natural and synthetic polymers; platey minerals and scrap products are used for controlling lost circulation in porous or fractured zones; salts are added to the mud to inhibit shale and clay swelling; chemicals are added for pH adjustment, prevention of corrosion, and as scavengers for formation fluid components. Because of the clay component, drilling muds have rheological properties different from conventional fluids, behaving as Bingham plastic fluids as opposed to the Newtonian behavior of water and oil. Newtonian fluids will begin to flow with the application of any force, however small. Bingham plastic fluids require a finite force or shear stress (yield value) before flow begins. Thixotropy is another property of clay-based drilling fluids. At rest they form a gel structure that suspends the weighting agents and rock cuttings. These gels break down when a finite force is applied and circulation is restored. At the bit where shear rates are the greatest, the viscosity or resistance to flow decreases, so hydraulic pressures and pumping costs are minimized. A drilling rig provides a means of rotating a hollow pipe attached to a cutting bit. A mud pit or tank is used for mixing the drilling mud and its components. A centrifugal pump delivers this fluid to the drill ripe and down to the bit

Jan 10, 1983