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By W. de Moura, R. Fueyo, M. M. Botz, J. C. Scola

The Cerro Vanguardia mine is an AngloGold Limited operation in southern Argentina that includes multiple open pits and a hybrid Merrill-Crowe and CIL circuit to recover gold and silver from oxide ore. Operations were commissioned at the site in 1998, which included a plant in the metallurgical circuit to recover cyanide from mill tailings. The cyanide recovery plant was initially configured to process tailings slurry and achieved greater than 90% cyanide recovery from tailings containing about 600 to 800 mg/L WAD cyanide (as CN). The cyanide recovery circuit was operated in this manner for approximately eight months, during which time the consumption of sulphuric acid and sodium hydroxide was relatively high, leading to high rates of scale formation in the acidification tank and stripping towers. In July 1999, several piping changes were made in the cyanide recovery system to permit its operation with clear solution, which reduced the sulphuric acid consumption and eliminated scale formation in process equipment. The cyanide recovery system currently operates with a two-stage counter-current decantation (CCD) circuit which provides clear solution for processing in the cyanide recovery plant. The cyanide recovery efficiency now averages about 90% to 92% from solution containing about 350 mg/L WAD cyanide (as CN). Recovered sodium cyanide now accounts for about two-thirds of the total cyanide added to the leaching circuit. This paper presents a description of the cyanide recovery plant and details regarding its current operating efficiency.

Jan 1, 2004

By G. Bräuner

The methods of burst control treated in the authors' very informative paper have been applied in the Ruhr Coalfield, Germany, for more than 20 years and have proved to be highly effective. It might be interesting here to mention a few experiences: • The symptoms of critical stresses when drilling with small diameters ("test drilling") are essentially the same as described. However, we consider the situation safe if these symptoms occur beyond a certain distance ahead of the face. • That safety distance equals three times the seam thickness plus the daily advance. It is the total seam thickness that counts, not merely the mined portion. • Critical stresses within the safety distance are dissolved by so-called destressing measures: drilling with heavier equip¬ment, blasting, or water infusion. • To avoid bump initiation, the destressing operations should begin at the sides of the stressed zone rather than in the middle. • As to water injection, there are two different principles. If the situation is critical already, high pressures are applied for hydraulic fracturing. If the stresses still allow to drill deep holes, the fluid pressure is kept low and acts for a longer time. This is to make the coal break successively instead of violently - a long-term precaution. • When the stresses are very high, destressing is the most appropriate means. We mostly drill with 95 mm-diam (3.7 in. - diam). The techniques in detail are somewhat complex and sub¬ject to modifications. But the general idea is to accomplish burst prevention by controlling the potential burst situations.

Jan 1, 1989

By Frank H. Blair

A study of paleogeography and paleo-environment, coupled with modern geochemical techniques and geologic inference, points to the presence of unconventional platinum group metal deposits in domestic and foreign ultrabasic terranes. During the laterisation of the tectonized and serpentinized mafic and ultramafic rock units, onshore winds provided abundant low temperature chloride to the laterite-saprolite profile. Here, an environment formed where gold, silver and platinum was dissolved, transported and redeposited. Changes in climatic conditions have helped preserve the redeposited metals in fossil laterites. The definition of "unconventional mineral resources" used here is taken from the Cameron Volume of Unconventional Mineral Deposits published by SME-AIME in 1983: "Unconventional mineral resources represent materials of possible economic importance that occur in geological or physical environments that have not been successfully exploited for the particular mineral." (van Rensburg, 1983). Chromite-rich rocks worldwide contain high platinum group metal concentrations. This feature is found in ophiolitic sequences, Alaskan-type ultrabasic complexes or statiform intrusions. Association of platinum group metals with chromite has received much attention. The reason for that associa¬tion, however, is not clear. Much has been written about how and where the platinum group metals occur. It is known that they are present in the spinel lattice, as solid solution elements in sulfides and as discrete platinum group minerals. This article outlines the reasons geologists should be looking at lateritic terranes to determine the feasibility of searching for undiscovered, low-grade platinum group metals amenable to openpit, bulk mining. Laterite-saprolite horizons could contain significant platinum group metals and location of anomalous values on the surface and in the weathered profile can lead to discovery.

Jan 1, 1993

By Steve Kral

The Fourth International Symposium on Hydrometallurgy was organized to give those in the minerals processing field an opportunity to discuss current topics of interest in the broad field of hydrometallurgy. Held in Salt Lake City, UT Aug. 1-5, 1993, this fourth symposium also paid tribute to Milton E. Wadsworth for his many contributions in this area over the past 40 years. The science of hydrometallurgy has made great strides since the last symposium was held 10 years ago. The use of electrochemical principles and techniques has produced encouraging results. For example, the application of in situ electrode spectroscopy has helped to understand the mechanisms operating in hydrometallurgical processes. Sophisticated computer models have been developed to handle the thermodynamic properties of concentrated electrolytes. However, it is up to the hydrometallurgist to continuing working on bridging the gap between theory and practice. The successful application of solvent extraction-electrowinning (SXEW) is one illustration of the successful transfer of technology. Its widespread use in the United States during the 1980s played a significant role in the revival of the domestic copper industry. Currently, electrowon copper accounts for about 30% of total US production. Impressive developments in precious metals recovery have also occurred. Since the last symposium, carbon-in-pulp (CIP) and heap leaching have become widely used in gold recovery. And recovery of refractory precious metals ores and concentrates by pres¬sure oxidation and bio-oxidation have made significant advances. In all these examples, hydrometallurgy has played a significant role in the recovery of minerals and metals from primary sources. In addition, considerable attention has been focused on the treatment and recovery of values from secondary sources.

Jan 1, 1994

By Jim Peregoy

INTRODUCTION Frontier-Kemper Constructors, Inc. is an Evansville, Indiana based heavy construction contractor engaged in projects for both the public and private sectors of the underground construction industry. Construction activities range from conventional shaft, slope, tunnel and chamber excavation through state-of-the-art mechanical excavation, ground freezing, standard support and structural concrete operations. Conventional excavation and concreting equipment, as well as raise boring machines, road headers, tunnel boring machines, and freeze plants are owned, operated, maintained and modified "in-house" to suit the needs of individual projects. The balance of this paper wilt present a general overview of the Frontier-Kemper planning and construction operations on the recently completed Phase II of the U.S. Army Corps of Engineers, John Day Dam, Juvenile Fish Bypass Project. General Project History The U.S. Army Corps of Engineers is responsible for designing, constructing and maintaining various navigation and impoundment structures on the nation's inland waterways. Maintenance involves both the work required to maintain the structure in fully-operable condition and the ongoing work required to maintain a positive impact on the environment. John Day Dam is located on the Columbia River approximately 95 km (60 miles) upstream of The Dalles, Oregon. It was constructed to: provide electric power to the Pacific Northwest; provide Locking for up-and-downstream bound commercial and private watercraft; act as a water impoundment structure to control flooding conditions; and to provide a source of irrigation water

Jan 1, 1987

By Peter J. Tarkoy, Terence G. McCusker

INTRODUCTION The discovery of oil and gas reserves in the North American Arctic has led to substantial thought being given to their development. Systems adequate for exploration are not always, or even often, suitable for permanent installations. Combinations of offshore pipeline, drilling ships, platforms, sub-sea systems, sand islands and -ice island bases have been proposed. However, conditions in the Arctic are such that these methods may be difficult or impossible to implement. Problems exist with (1) the freezing of the Arctic Ocean surface for 9 - 10 months per year, (2) the movement of sea ice, (3) scouring of bottom sediments by ice islands and icebergs to great depths below the ocean bottom and (4) deep water channels. Any method which can avoid the problems associated with surface construction in these very adverse conditions merits detailed examination. One of the proposed solutions is to tunnel from a convenient or available access point to a point within the field, construct a chamber large enough to accommodate the drilling equipment and drill the development wells in a protected environment. Service and delivery lines would use the access tunnel and further tunnels and chambers would be constructed in a radiating pattern to develop the whole field. In order to determine the feasibility of underground construction in the North American Arctic, it is first necessary to understand the geologic and environmental factors which would affect such construction, to be knowledgeable concerning the problems and then to consider the techniques appropriate to the conditions which will be encountered, bearing in mind the need to minimize both con-

Jan 1, 1976

By C. P. Siess, S. L. Paul, E. H. Gaylord

Several types of tunnel supports are being investigated experimentally and analytically at the University of Illinois at Urbana-Champaign under the sponsorship of the Federal Railroad Administration, Department of Transportation. The results of work on two types will be discussed here. These are steel sets and continuous, monolithic steel-fiber-reinforced concrete liners. The latter is a model of a short length of liner that might result from a continuous slip-forming operation in a tunnel excavated with a boring machine. Tests have been performed on both types of support and analyses are being developed which will greatly broaden the scope of the test program. The objective of these studies is to improve the understanding of basic behavior of these supports, and to develop techniques for their analysis. The analyses will then be used to perform parameter studies that will lead to more rational procedures for structural design. The tests provide a check on the accuracy of the analysis and demonstrate the overall behavior and modes of failure. Another part of the project is concerned with the interaction of support and medium, and thus prediction of loads for the supports. These studies are presented in greater detail in a recent report (1). A brief outline of results obtained to date are presented in this paper. STUDIES OF STEEL SETS Description of Set Tests The sets tested were of the horseshoe type with a 5-ft radius arch section and 7-ft straight legs. They had bolted joints at the crown

Jan 1, 1974

By Mark L. Mott

The Pittsburgh Safety and Health Technology Center of the Mine Safety and Health Administration (MSHA) has developed the Mine Emergency Responsiveness Development (MERD) program to improve the reaction and re¬sponse of mine personnel in mine emergency situations. The MERD program simulates problems that may occur in underground mine fires and explosions or surface mine accidents. Since its inception in 1982, the MERD program has been presented to MSHA, industry, labor and state government personnel. This versatile program is easily adapted to suit various training requirements. In 1992, a Mine Simulation Laboratory was built at the Natinal Mine Health and Safety Academy, Beckley, WV, to improve training for mine emergencies and prevention and fighting of mine fires. This facility is capability of simulating a coal mine and metal-non-metal mine for training purposes. It has been included in the MERD program to provide realistic and practical training for mine rescue teams and MERD partici¬pants in advanced mine emergency operations. The objectives of the MERD program are to improve the organizational and management skills of the participants in a rescue and recovery operation and provide a better understanding of the importance that various roles have on the overall organization and the importance of their interaction. The MERD program is not intended to provide the participants with all of the abilities and knowledge required to respond effectively to a mine emergency. Rather, it is intended to give the participant an opportunity to experience the emotions, frustrations and successes of a mine emergency without having to actually be involved in one. The participants are expected to return to their regular jobs with a greater appreciation of the environment in which emergency operations take place. Experience in mine emergencies is extremely limited in the industry today. The participants are encouraged to use the knowledge gained during a MERD program to develop or enhance a mine emergency plan suitable to their needs.

Jan 1, 1993

By Charlie Sons

Pit and underground mine operators typically use a lot of big equipment tires. Just as typically, they spend a lot of money they shouldn't on these tires. That's because tire use and maintenance are not given enough attention. That often occurs because mine management and personnel do not know the basic facts of tire use and care. If a piece of large equipment is damaged or ruined, a good explanation better he forthcoming. A ruined tire is often just a shoulder shrug. But that sort of fatalistic acceptance can cost tens or hundreds of thousands of dollars a year extra for big equipment tires. That does not have to be. There are some basic tire considerations that, if followed, will extend tire life and lower tire costs. Most companies have the inevitable conflict between the production department, which resists any restrictions that may reduce productivity, and the maintenance department. Production success is based on meeting a schedule of yards moved, while maintenance success is based on availability and equipment cost. When production falls behind schedule and equipment speeds are increased, maintenance may soon find its tire costs rapidly increasing, unless everyone understands the tires' vulnerability to damage. Unless the production department understands the problem, or restraint is applied by top management, costs may become exorbitant. At one job site, tire costs alone exceeded $250,000, to move 55 dam3 (72 000 yd3) of dirt on an 11-km cycle. The operation temporarily caught up with its schedule, but tire costs and attendant downtime soon made this a not-for-profit exercise. Because an operator must always attempt to move payload at the lowest cost, there are cases when higher than normal tire costs must be accepted. For example, in pioneering work with tandem engine scrapers, steep grades shorten tire life to less than normal. But the steep grades make shorter haul cycles possible, yielding more trips per hour than alternative earth-moving methods.

Jan 1, 1982

By J. E. Spencer

Mesozoic and Tertiary mineral deposits in west-central Arizona are commonly associated with Mesozoic thrust faults and Tertiary detachment faults, respectively. Quartz-kyanite rocks and pyritic quartz-sericite schists with local anomalous gold are the product of probable Jurassic argillic alteration of Jurassic volcanic, sedimentary, and plutonic rocks followed by Cretaceous thrust burial and associated metamorphism. Slivers and sheets of Paleozoic carbonates along Mesozoic thrust faults were locally sites of syn-and post-thrust mineralization. Widespread brecciation along Tertiary detachment faults resulted in increased permeability along fault zones. Elevated thermal gradients also resulted from detachment faulting and apparently caused convective aqueous-fluid circulation along detachment faults and associated Fe+Cu±Au mineralization.

Jan 1, 1988

By Ernest A. Draeger, James W. Collins

Water only cyclones, sometimes referred to as hydrocyclones, are one of the newest types of coal processing equipment. These devices have achieved wide acceptance as fine coal cleaners in the past decade. Many metallurgical coal plants employ water only cyclones to process 0.5 mm x 0 size coal. Some of these plants have as many as 40 to 50 305-mm-diam units with each unit receiving as much as 9 t/h of raw feed. The growth in the utilization of hydrocyclones is due partly to the energy shortage, partly to the general increase in over-all coal preparation, and also because of a need for a simplified fine coal (0.5 mm x 0 size) gravimetric separator. Large diameter water only cyclones are also available and in use to process feed sizes up to 32 mm in size. However, the size normally employed for cleaning 0.5 mm x 0 coal are 356 mm or 305-mm-diam for single-stage circuits. In two-stage circuits, the secondary units are normally the same diameter as the primary units or smaller, such as 203-mm-diam. By using the small diameter cyclones and treating a closely sized feed, 0.5 mm x 0 only, it has been found that the probable error or imperfection of the water only cyclones is comparable to that obtained on the same size fraction treated in a large 610-mm-diam heavy media cyclone washing 38 mm x 0. The water only cyclone can approach the efficiency of a heavy media cyclone when cleaning fine solids because it creates its own dense media by accumulating high specific gravity particles in the wide angle conical section of the cyclone. A cut-away cross sectional view of a water only cyclone is shown in Fig. 1. It is also true that when treating a wide range of sizes (38 mm x 0) in heavy media cyclones, the smaller size particles (0.5 mm x 0) separate in proportion to the split of the media through the cyclone rather than by particle density.

Jan 8, 1980

By Z. Kowalski

In the defunct Gorka quarry, there are situated both a waste disposal site of an area of 6.7 ha and containing approximately 1 million ton of high aluminium wastes and a pond of an area of roughly 3 ha, up to 15 m deep, with about 400000 m3 of polluted water. The reservoir is fed with the filtrates arriving from the disposal site mentioned, at a rate ~130 m3/day. An alarming phenomenon is the subsidence of the pond bottom and the infiltration of solutions into the Triassic and Jurassic water resources, assessed at ~40 m3/ day. The basic problem related to the effluents in the Gorka pond is their high alkalinity (pH 12-13.4) and variable pollutants whose level increases appreciably with the pond?s depth. The solution offered provides pumping out and treatment of about 500000m3 of effluents retained in the Gorka reservoir in an about yearly time. Effluents would be treated in a reverse osmosis plant, according to a process so far verified on a quarter-commercial scale. The treatment process by-product would be discharged into the Ropa stream. The brine solution (containing about 25% NaCl), whose amount may reach up to100000m3, might be supplied to the Debiensko Mine which produces technological salt from salt-bearing mine waters. Similarly, there would be provided an intake of underflows of infiltrates (by means of deep wells, and possibly girdling ditches) arriving from the high aluminum site, and such effluents would be subject to ongoing dilution in water courses. It would be possible to test the system of underflows reaching the Gorka reservoir by means of geochemical identification, previously performed. The next stage following the pumping, would be the utilization of approx. 50 000m3 of bottom slurry. Highly alkaline slurries would be utilized in the production of self-solidifying mixtures. Slurries would be pumped out and temporarily dumped on drying beds, located nearby the Gorka reservoir, and later on used successively for making self-solidifying mixtures in a plant similar to a concrete making seat. Those mixtures would be applied for sealing the bottom of the Gorka reservoir and the necessary part of the edges of the defunct quarry. An alternative solution is the utilization of slurries in the facilities of the Trzebionka Mining Works and the application of self-solidifying mixtures, made in the Trzebionka Works, for sealing the reservoir bottom.

Jan 1, 2006

The Mine Safety and Health Administration (MSHA) academy in Beckley, WV, received enquiries from various segments of the mining industry concerning alcohol and substance abuse in the mining industry. The MSHA Director formed a committee, the Mining Industry Committee on Substance Abuse (MICSA), to deal with these enquiries. The committee met in April 1985 at the mining academy in Beckley. The MICSA committee expanded its membership to represent labor, management, and government agencies affiliated with the mining industry as well as government agencies dealing with alcohol and drug abuse. This expanded 18-member committee met for the first time in July 1985. At that time, two cochairmen were elected, one from labor and one from management. MICSA has spent time on education by sharing information on the issues and by calling in outside experts for advice and consultation. The committee also initiated several projects. These include a resource manual on substance abuse and employee assistance programs. Mine operators and labor unions can use these programs as guides. MICSA is also assembling statistics on substance abuse, particularly as applied to mining. And the committee commissioned an Education film, Substance Abuse, Is It Our Problem? (The results of a survey on drug use, given in Table 1, suggest that substance abuse may indeed be a problem.) The educational film, produced by MSHA, is an introduction to the problem of substance abuse in the mining environment. The film encourages mine operators, labor unions, and miners to analyze their individual circumstances to determine whether a problem exists. The film also offers ways to deal with the problem. And the film invites the mining industry to request additional information from MICSA. There is no single approach to substance abuse that will fit the need of every mining operation. As with any health, safety, or production problem, remedies must be site specific. MICSA's aim is to channel ideas to those who seek to help employees in a mining environment who seek to rid themselves of alcohol and substance abuse. As stated more formally: The Mining Industry Committee on Substance Abuse represents the efforts of labor, management, and government. The mission of the committee is to make the mining industry aware of the problems resulting from alcohol and other drug abuse and to recommend possible methods to remedy the problem. The function of the committee is to assist the industry in developing programs and resources to recognize and provide help for troubled employees, and thus reduce the risk of accidents, while lower absenteeism and increasing productivity.

Jan 11, 1987

By H. W. Peirce

Arizona is a sun-belt growth-region where 13 tons of industrial (nonmetallic) minerals is being produced annually per capita. In 19B5, non-fuel mineral production reached $1.532 billion and consisted of metallic ($1.277 billion-84%) and nonmetallic ($253.5 million-16%) earth materials. Sand-and-gravel value was second only to copper. over 90% of the value of nonmetallics is represented by combined sand, gravel, cement, and lime. The remaining less than 10% ($25 million) was attributed mainly to stone, specific volcanic products (cinder, perlite, pumice), gypsum, clays, salt, zeolite, and others. Current interest in industrial-mineral development in Arizona is high, especially in the geologically complex Basin and Range region.

Jan 1, 1988

By Charles D. Litton

Introduction The successful performance of a mine-wide fire detection system depends upon its ability to detect the presence of a fire rapidly and reliably. It should be sufficiently rapid so that there remains enough time to either safely evacuate a mine or successfully extinguish and control the fire or both. It should be reliable so that false alarms are minimized without sacrificing sensitivity or time response. Systems should also be durable enough to withstand the mine environment over long periods of time while maintaining a high degree of re1iability. Maintenance and calibration of the system should be simp1 e and not require the expenditure of excessive time and manpower to keep it operational. Sensitivity, reliability, and durability of mine fire sensors and their electronic support systems have been the subject of significant Bureau research within recent years. The bulk of this type of information, along with the reports from which the remainder of this paper is derived, can be found in the Bibliography. It suffices to say that there exist commercially available systems for use in mines. This paper addresses a strategy for the use of such sensors and systems. Many factors influence the design of a mine-wide fire detection system, such as the potential sources and modes of ignition, the types of combustibles involved and the quantities avai1able for fire growth and flame spread. Mine air ventilation influences the growth and spread of a fire and also serves to transport the products-of-combustion to other areas of a mine remote from the fire. Fire sensor alarm thresholds place limits on the sizes of fires that can be detected. The time to respond to a detected fire, either in terms of evacuation or control and extinguishment, place additional time constraints on the design of fire detection systems. These factors interact with each other, often in complex ways, and it is the definition and understanding of these factors and their interactions that hold the key to the design of adequate and re1iable fire detection systems. Our level of understanding of the problem has increased dramatically within recent years and it is the intent of this paper to discuss the progress that has been made and how the information can best be used to improve the level of fire detection in underground mines.

Jan 1, 1986

By C. B. Cecil

The sulfur content of United States coal can be assessed by using a variety of approaches. The sulfur content may be expressed in terms of total sulfur in the coal, pounds of sulfur per million Btu, or sulfur remaining after reduction by coal preparation. In addition, the sulfur content may be applied to the demonstrated reserve base or to coal resource estimates. Unfortunately current data bases do not allow for an integrated assessment at the National level. Although classification of coal resources and reserves according to sulfur content is arbitrary, preferential production of low-sulfur reserves will positively skew the total sulfur of the remaining coal resource.

Jan 1, 1986

By A. H. Hassan

Stibiotantalite is a relatively rare mineral not commonly found in the major tin districts of the world, and its separation characteristics have not been documented adequately in the literature.

Aug 1, 1979

By R. J. Pruett, J. Yuan

Kaolin clays from five different commercial deposits in Georgia were studied to understand the variations of zeta potential and related fundamental properties. The results suggest that higher negative zeta potential is related to exchangeable or soluble calcium ions in the clays.

Jan 1, 1999

By Dominigue Francois-Bongarcon

This paper presents a step by step vulgarized review of the applications of geostatistics to the estimation of the mineable, recoverable reserves of the Cinola gold deposit in British Columbia.

Jan 1, 1988

By Zhengbin Cheng, Wenguang Lu, Baoqi Sun, Jiaying Tang

This paper studied the flotation separation of feldspar, zircon and kyanite from quartz with a mixture of cationic and anionic collectors. Tests show that collector mixture has specially good effect, using it, the separation of these three silicate minerals from quartz can be successfully achieved at the natural pH value of tap water in the absence of any acid, fluoride and other inorganic reagents. The properties and characteristics of collector mixture were analysed. By means of IR-spectra, ESCA and AES, the action mechanism between collector mixture and minerals was throughoutly studied.

Jan 1, 1995