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By G. V. Sullivan

As part of its program to conserve domestic mineral resources through advancing mineral resources technology, the U.S. Department of the Interior, Bureau of Mines, conducted investigations to determine the feasibility of recovering high-grade barite concentrates, suitable for use as well-drilling mud, from current and old waste pond materials and materials bypassed in present mining operations. Flotation studies of waste pond samples from Missouri and Nevada yielded barite concentrates containing over 95 percent BaSO4 with recoveries of 86 percent and 96 percent, respectively, of the barite in the flotation feed. Flotation studies of a hard-rock sample from Georgia, currently bypassed in mining, yielded a barite concentrate containing 97 percent BaSO4 with an attendant recovery of 97 percent of the barite.

Jan 1, 1980

By W. G. Pariseau

Regression analysis of calculated on measured displacements were used to assess the influence of fill and fold plunge on shaft pillar mining at the Homestake Mine. These effects were neglected in the original three-dimensional finite element analysis undertaken in 1991. An average fold plunge of 15? and a 24K fill (Young’ modulus of 24,000 psi or 165 Mpa) were used in the reanalysis. Measured displacements were obtained from an array of 36 m (120 ft) multiple-position borehole extensometers installed in June 1994 and read to March 2003. Results indicate the effects of both on calculated displacements and thus on regression parameters are noticeable. However, these neglected effects would not have changed the original inference of Ross Shaft stability during pillar mining.

Jan 1, 2004

By K. Soucek

Extraction of hard coal reserves, but also of mineral resources in general in the underground coal mines includes in itself many anthropogenic interventions in the earth crust. These interventions are closely associated with the solution of stability problems in the mine and with occupational safety. One of potential applications of such geo-technical interventions in rock mass is the chemical grouting technology. The chemical grouts are very suitable to affect the physical and chemical properties of rock mass. With the present development of chemical grouts, primarily based on polymers, there come into existence new composite materials during the grouting process (the so called geo-composites), which properties significantly differ from the original rock. An important factor, which affects a choice of chemical grouts and at the same time the effectiveness of grouting technology is the resulting properties of geo-composites. The properties of a coal geo-composite differ from the ones of the unmodified coal seam. On the basis of the laboratory geo-mechanical tests, the differences of properties of both material types were found. While the pure coal samples were destroyed very brittle and explosive, the geo-composite samples were making higher level of tenacity and load bearing ability after overstep of material strength. The presented paper discusses the different behaviour of these original and modified coal samples. The X-ray CT scans were used for observation and demonstration of failure evolution in these samples of pure coal and coal geo-composites after compressive loading.

Jan 1, 2006

By Barton J. Suchomel

Introduction Despite perennial economic turbulence, Argentina continues to push ahead with efforts to develop its fledgling hardrock mining industry. The country lacks the infrastructure and mining history of neighboring Chile, but contains vast areas of great resource potential. The eastern slope of the Andean Cordillera in west-northwest Argentina is a relatively little-explored region offering geology highly conducive to the occurrence of base and precious metals deposits. Past exploration has concentrated on locating and evaluating porphyry copper-molybdenum (Cu-Mo) type occurrences. Comparatively little attention has been given to precious metals potential. An interesting and important group of base and precious metals prospects in northwestern Argentina occurs within and adjacent to the Upper Miocene Farallon Negro volcanic complex in Catamarca province. The volcanic complex contains numerous base and precious metals vein occurrences, high gold porphyry copper prospects, and possible disseminated gold targets that have attracted relatively minor attention in the past. Various geologic aspects of the region have been reported by several workers (Llambias, 1970, 1972; Caelles et al, 1971; and Sillitoe, 1973). Regional geology The Farallon Negro volcanic complex is located within the Sierras Pampeanas morphostructural province about 200 km (125 miles) east of the main Andean Cordillera (Fig. 1). The Sierras Pampeanas is characterized by north-south-trending basin and range topography that developed during the Miocene and Pliocene. Uplifted blocks are composed mainly of lower Paleozoic metasediments and granitoid plutonic rocks unconformably overlain by Tertiary redbeds and minor carbonates. A consistent landward migration of volcanic and intrusive ac¬tivity occurred in this region of the Andes from the early Mesozoic through the mid-Tertiary. An eastward extension of magmatism during the Miocene and Pliocene resulted in the formation of the Farallon Negro volcanic center. Volcanism at Farallon Negro ini-

Jan 8, 1988

By Y. J. Wang

Along with the inexpensive availability of computing hardware, a proliferation of powerful personal computers is being realized throughout the mining industry. People from every arena within the industry are designing, developing, and/or applying mining specific software, which is increasing at a rapid rate. In this section applications (or potential applications) that are being made in the analysis and design of mine systems are discussed, including the design of compressed air networks, the simulation of hoisting operations, analysis of longwall face maintenance, and a summary of computer and software applications for analysis and design of coal operations. In "Computer Aided Design of Mine Compressed Air Networks" the authors describe software, called CompAir, and the underlying theoretical and mathematical foundations of it that can be used to make accurate, cost-effective designs of compressed air systems for mines. It includes algorithms for network analysis and the optimization of pipe diameters. The techniques embodied in the software replace traditional rule-of-thumb approximations which have been used in the past and avoid the operating problems that often result from using average, steady-state parameter values, estimated for ideal operating conditions. CompAir, coded in Turbo Pascal for personal computer use, bases calculations on compressible fluid theory, which gives more accurate results than incompressible fluid theory whenever high flow rates or long line distances are involved. The net- work and pipe diameter analysis is formulated as a nonlinear programming problem. The solution technique requires a trial and error approach that iteratively applies the unconstrained optimal pipe diameter algorithm to successive solutions of the constrained network problem until the diameters become "fixed." The authors conclude by recommending the use of a mine-wide monitoring system to improve cost control and provide a better understanding of flow regimes in compressed air networks.

Jan 1, 1989

By Wallace Jarman

Introduction As with many gravity concentration processes, pneumatic concen¬tration traces its origin in antiquity. The use of winnowing to separate chaff from grain has long been known, and such procedures were undoubtedly practiced in ancient civilizations for the concentration of ores and the separation of slag from metal whenever specific gravity, size, and shape differences were favorable. Taggart142 has reported on the use of dry rockers and dry panning techniques for use with gold ores in arid regions such as Western Australia. The present day air table was developed in the last century for this purpose. Devices and Processes Classification. All classifiers make a separation on the basis of size, shape, and specific gravity. In addition to specific gravity and size, particle shape factor is often particularly important to pneumatic processes, and advantage is taken of the fact that both flat and fibrous particles settle at velocities substantially lower than that of their equiv¬alent spheres. Another factor of importance in this process is the bulk density of the material since substances such as exfoliated ver¬miculite or partially opened fibrils of asbestos have bulk densities significantly lower than those of the pure in situ mineral. Winnowing takes advantage of all of these physical factors to affect a separation starting with a closely sized feed, and vermiculite has been separated from rock by this process.142 When air classifiers are used to size minerals, the separation will often not be perfect because heavy particles will respond similarly to somewhat coarser light particles while flat, elongated, and low bulk density particles will act as would particles finer than the cut size. An example of a classification process that also results in concentration is the zig-zag classifier"' used to separate paper from glass, metal bottles, and cans during the recycle of municipal solid waste. Application of this process to minerals showing the proper specific gravity, size, and shape differ¬ences is obvious. An important device of this type is an air-aspirated screen used to remove asbestos from its associated rock during the dry processing of that mineral.144 The raw ore is crushed and screened and the asbes¬tos removed by aspiration from the surface of the screen by virtue of its shape and low bulk density. Hindered Settling. Based on the discussion in the section on "Hindered Settling Concentration and Jigging," the use of air devices could be anticipated in desert areas or where moisture may be deleteri¬ous to the product to be separated. Such processes have three major defects: (1) dust may be difficult to contain, (2) fines are difficult to process, and (3) the process is inherently less efficient than are wet processes as may be seen from Eqs. 3 and 4 in the section on "Hindered Settling Concentration and Jigging p. 4-47." Taggart142 has reported on the use of both dry panning and a dry rocker for gold separation in and regions. The dry panning makes use of winnowing, defection on the basis of specific gravity and shape during fall, and hindered settling. Prescreened placer material is poured from one pan to another as air blows across the falling stream. The process is repeated many times with hand picking to produce a rough concentrate. Magnetic minerals are then removed, and the residue, one grain deep in the pan, is air blown. In dry rocking the gravel is sized on a steeply inclined screen with the undersize fed to a riffle box with a porous bottom which is blown from underneath."' This device was the forerunner of the present-day air table. Air Tables and Jigs.145. 146 At least nine types of these devices have been developed, all but two of them for coal. While the devices used for coal may be characterized as pneumatic jigs, pneumatic tables, and pneumatic landers,145 only pneumatic jigs survive today. The same is true for ores.'" In these devices presized particles are fed to the separator which consists of an inclined vibrating conveyor with a porous surface through which air is carefully introduced to form a fluid bed. The lighter particles are lifted by the air out of uphill conveyance and float downhill, while the heavier particles in contact with the surface are conveyed uphill by the vibrator. Typically both transverse and longitudinal slopes are used. A plan view of a Triple S air table and the type of separation made is shown in Fig. 44.147 Because of its external appearance, the device has been called an air table, although it functions essentially as a jig. However, some of the asymetrical acceleration conveying function of a standard shak¬ing table is also performed by the eccentric vibrator incorporated into this device. Low pressure air is admitted below the vibrating table surface consisting of cloth (e.g., canvas), porous plastic, woven wire, or punched metal supported on a wire mesh or grid. As with a shaking table, the device produces a concentrate, middlings, and tailings. The middlings are recycled or are subsequently treated on another concentrating device. As with many wet separations, presizing by screening is necessary. The oft-repeated admonition of Professor Richards, "Separation without classification is damnation," is cer¬tainly true here. In this way a small heavy particle which might weigh the same as a large light particle and thus report to the same place on the air table has already been removed in the sizing step. Air tables are almost universally encased with a canopy to remove dust by aspiration. Some concentration may also be achieved in this step when favorable specific gravity, size, and shape differences are present. Applications Ore Separations. Air tables were originally developed for ore separations, and they find application in and regions or where water is deleterious or inconvenient to use or remove (e.g., small tonnage materials already dried). They have been used for asbestos, bauxite, calcite, cassiterite, columbite-tentalite, diatomaceous earth, fluorite, gilsonite, graphite, kyanite, manganese minerals, mica, managite, perlite, pyrite, pyrrhotite, vermiculite, and uraninite ores. More recently, air tables have found favor in separating a wide variety of secondary materials such as abrasive grains, bone char, catalysts, fiberglass, scrap glass, scrap wire from its insulation, prills from slag, dross and coke from metal or from each other, metal from crushed crucibles, lead from plastic in old batteries, and cubic particles from flat ones. The devices also finds considerable application in the preparation of food¬stuffs. As stated before close sizing before separation is desirable, and if the specific gravity difference is slight, very tight

Jan 1, 1985

By L. H. E. Weyher

Minerals beneficiation commonly requires initial crushing and grinding so that the mineral phase we seek to concentrate is adequately liberated to obtain a product of specified grade at optimum recovery. To some degree this also is true for coal preparation. In the comminution process we liberate not only the product but also the tailings phase. The true objective is, therefor, to eliminate from the comminution circuit whatever particulate matter has reached specified liberation, regardless of whether the particle is product or tailings material. Overgrinding either of the two phases ties up mill capacity and usually also burdens the downstream processing steps by increasing costs or decreasing recovery, or both. In view of this situation, one would expect concentration steps to be commonly incorporated into the cominution circuit. The reasons this is not done may vary, but probably include the desire to utilize large scale unit operations, e.g., large mills, in conjunction with very simple processes. Hydrocyclones have satisfied this desire but may not always be employed for the right reasons. Hydrocyclones are indeed simple. They also are rugged and forgiving. Unfortunately, these virtues are frequently misused. The direct results are inefficient classification and overgrinding. The indirect results are added costs through recovery losses, unnecessary recirculation, and so on,

Jan 1, 1985

Twenty field-scale tests were conducted in a 28 MW pulverized coal power plant in Healy, Alaska, to examine mill power consumption in relation to coal grind size. The intent in this field-scale study was to verify if grind size truly impacted power consumption by a detectable amount. The regression model developed from the data indicates that grind size does impact mill power consumption, with finer grinds consuming significantly more power than coarser grinds. However, other factors such as coal hardness (i.e., the lower the Hardgrove Grindability Index, or the harder the coal, the higher the power consumption) and mill throughput (i.e., the higher the throughput, the higher the power consumption) had to be included before the impact of grind size could be isolated. It was also observed that combining amperage and flow rate into a single parameter, i.e., specific amperage, hurt modeling. Cost analysis based on the regression model indicate a power savings of $19,972 per year if the coal were ground to 50% passing 76 mm rather than the industry standard of 70% passing 76 mm. The study also demonstrated that size reduction constituted a significant portion of the power consumption.

Jan 1, 2008

By P. Jacquin

Many a deposit estimation has been carried out since geostatistical methods were first implemented. To date however few mining programs have totally been completed and even fewer comparisons can be drawn between estimated reserves and extracted ore tonnages. Aluminium Pechiney work a number of bauxite mines in Southern France. As from 1969 they modified their deposit estimation methods, giving up traditional approaches and opting for geostatistics. At that time, the authors of this paper were entrusted with the first geostatistical estimations and in particular, those concerning the deposits mentioned herein. Over the past decade a number of deposits have been worked out and we thought it interesting to report about comparative results. French bauxite deposits are of the karstic, as opposed to the lateritic, type. The bauxite, formed at some distance of the present-day deposit, was brought to and trapped in limestone karst pits. Subsequent physical and chemical alterations may have taken place : silica and carbonate drifts, recent karst slips. The morphology of these deposits is often rather complicated. The deposits are small from a few hundred thousand to a few million tons at the most. The overburden thickness usually precludes open mining. Mining investments and financial risks are often high, making it necessary to obtain optimal information on the deposit considered for mining. For the three cases brought up in this paper, deposit sizes, exploration methods and conclusions differ. They are brought up mainly to show the advantages inherent to a quality geostatistical study and the lessons drawn by Aluminium Pechiney.

Jan 1, 1982

By M. Leslar

Slope monitoring has been an important issue in static terrestrial lidar for some time. Several solutions for monitoring the progress of a slide have been devised over the years. All of these solutions have required users to be in the field operating the lidar equipment. This paper presents a new system developed using the Optech ILRIS-HD or ILRIS-LR lidar and the scripting language of PolyWorks to produce an autonomous slope monitoring system. This system has proven invaluable in detecting and alerting mine workers to potential danger within their mine sites. It has already been deployed in two mine sites and is scheduled to be installed at a third.

Feb 27, 2013

By Frederik P. Agterberg

During the past 20 years, methods of multivariate statistical analysis have been developed on mainframe computers for the integration of geological, geophysical, geochemical and LANDSAT data in mineral resource appraisal. At present, it is becoming increasingly feasible to perform mathematical image analysis of digitized patterns on microcomputers. This has led us to develop a new method of statistical pattern integration for mineral exploration. In this paper, the new method is used to outline, by means of posterior probabilities, exploration targets within small areas of which the prior probabilities for occurrence of new mineral deposits had been estimated by multivariate analysis.

Jan 1, 1989

By J. W. Lowry

After years of processing copper porphry ores, the Ray concentrator of Kennecott Minerals Company installed a concentrate regrind mill in its flotation circuit. The first cleaner concentrate is reground rather than the usual rougher concentrate. An additional cleaning of the reground product yields an increase in copper content of the final concentrate and a significantly lower insol content. The desired goal of decreasing the energy requirements for smelting the concentrate has been achieved.

Jan 1, 1980

By Thomas G. Johnston, Garston H. Blackwell

The development of a block model for a copper molybdenum ore deposit is described. The early use of the inverse distance power estimator, and later transition to geostatistics and kr iging, produced block models suitable for global reserve estimates. Because the global reserve was inadequate for routine mine planning, the production blast hole assays were incorporated into the block model, resulting in excellent local grade prediction. The on site use of small mini, and more powerful personal computers for estimating grades is described. The development of a computer aided, interactive graphic, mine planning system utilizing the grade block model is detailed.

Jan 1, 1987

By Kambhampati C. Rao, Cecil Lue-Hing, Nabih P. Kelada, William B. Willborn

improvements in the analytical techniques for cyanide speciation can furnish useful information about the behavior of the different cyanide species in the receiving environment. This could be of help to the environmentally concerned public and the regulatory agencies in the assessment of cyanide limits for effluents, stream quality, and land disposal of cyanide bearing wastes. In addition the ability to distinguish the free cyanide and the weakly bound cyanide from the strong ULTRAVIOLET IRRADIATION UNIT (LAMP, COIU3' HOUSING) FIGURE 1 complexes, as well as transformation to thiocyanate is also needed by different industries, such as mining and metal finishing, etc., to evaluate the efficiency of several processes. Cyanide has been used for the recovery of gold since the late 19th century. Although cyanide leach solutions are mostly recovered and used again, a large quantity of cyanide bearing wastewater becomes unfit for use and has to be treated before it can be released into natural waterways.

Jan 1, 1992

By C. Anderson, K. Nikkhah

This paper outlines the role of simulation software in design and operation of a typical metallurgical plant with mineral processing and hydrometallurgical units, to produce concentrate and pure metal. It addresses the role of simulation and mass balance software in the conceptual, feasibility and detailed design stages. It discusses the use of JKSimMet for sizing of mineral processing units, and METSIM and IDEAS for development of energy and mass balances. In detailed design of a plant, the complex interaction and variation in performance of various units makes it difficult to predict overall system performance and availability. Simulation is used to: assess operating strategies that affect surge capacities at various stages compare different ore types and mining strategies that affect concentrate product quality. optimize transportation logistics for raw materials, concentrate and metal products

Jan 1, 2001

By Jonathan G. Price

Silver-copper-lead deposlts in Precambrian, Permian, and Cretaceous red-bed sequences near Van Horn, Texas, have the following features In common: (1) mineralization controlled by steeply dipping fractures in sandstones, (2) lack of ore In overlying and interbedded limestones, (3) absence of igneous intrusions, (4) sulfide ores without typical hydrothermal gangue minerals, and (5) associated arsenic, molybdenum, zinc, and cadmium but not gold. Ore was probably deposited along fractures by reaction between low-temperature, oxidizing, metal-rich ground waters and sulfide-bearing waters or rocks. Detailed mapping and studies of fracture patterns indicate that mineralization occurred during Basin and Range extensional deformation, thereby postdating major Trans-Pecos igneous activity.

Jan 1, 1983

By Barbara C. Williams

U.S. Bureau of Mines researchers conducted field studies at an abandoned copper-gold mine tailings impoundment. Pore water quality was analyzed in the vadose and saturated zones. Three statistical procedures were employed to summarize the variability within and between the two zones. The results indicated that linear combinations of those variables reflecting sulfide oxidation and aluminum-silicate weathering best summarized the variability in each zone, and that the zones were most different on the basis of sulfide oxidation variables. The geochemical computer code WATEQ4F was used to assess the solubility status (saturation index) of minerals. Saturation indices of sulfide oxidation and aluminum-silicate weathering minerals were different in the two zones. It was demonstrated that the statistical analyses produced similar and complementary results to the geochemical code.

Jan 1, 1992

By Y. Paul Chugh

NIOSH and the Illinois Clean Coal Institute are funding studies on characterization of coal and quartz dust in Interior Basin mines since 2009. Coal dust characteristics vary significantly and, are vital for the development of the engineering controls. This paper presents wettability characteristics of coal dust with respect to its chemical and physical properties, since wettability is considered to be a primary dust control technique. Particle size distribution, inter-particle interactions during wetting and quartz associations with organic and inorganic matter in coal seams is critical for understanding wetting phenomena. Silica content in the un-wetted fractions was found to be very high during wetting tests. Wetting of quartz may be limited by its association to hydrophobic materials as well as buoyancy forces resulting from particle size characteristics and particle-particle interaction in the wetting agent. Temperature of the wetting solution and effective contact time between dust particles and water droplets are found to be two important variables affecting the wettability. The characterization data obtained from this study can be utilized to develop engineering controls.

Jan 1, 2011

By Takeshi Shinohara

It is a great honor and pleasure for me as President of the Japanese Tunnel Association to send greetings to the 1974 Rapid Excavation and Tunneling Conference. Recently in Japan, the Japanese Tunnel Association was established as recommended by the OECD Advisory Conference on Tunneling. This is a central organization concerned with tunnel construction consisting of government authorities, universities' research institutes and construction firms as well as manufacturers of relevant materials and equipment. As I was chosen the first president of the newly-established Japanese Tunnel Association, I would like to avail myself of this opportunity to announce to you its establishment and its earnest wish to contribute to the development of tunneling technique not only in our country but also all over the world. At the same time, I cordially request your friendship and cooperation for the benefit of further development of tunneling techniques on both sides of the Pacific. At present, many tunnels are under construction in Japan. The total length of tunnels under construction for railways and highways is about 600km including the 54km Seikan Undersea Tunnel which connects the Main Island and Hokkaido. Naturally, for construction of such tunnels in Japan, we have introduced much equipment and technique from the United States and other foreign countries. Now with accumulated experience, we are confident to be able to furnish various useful information concerning tunnel construction.

Jan 1, 1974

By P. Todd, K. Dever, P. S. Mills, A. A. Campoli

Resin bolt performance is dependent on the size of the resin annulus, the difference between the hole and bolt radii. The vast majority of the millions of resin roof bolts installed each year in the United States employ an annulus of 0.125 or 0.188 inches. Short encapsulation pull tests with resin annuluses of 0.125 and 0.095 inch resisted an average of 2.25tons per grouted inch, with no significant variation. Resin loses to simulated fractures increased as annulus size decreased, with a minimum loss of35% and a maximum loss of 60% associated with0.188 and 0.095 inch annuluses, respectively.

Jan 1, 2000