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By J. K. Whyatt

A microcomputer controlled data acquisition system has been developed for automatic monitoring of underground instrumentation from a remote location. The system has been used extensively by Spokane Research Center personnel for monitoring rock instrumentation in shafts, drifts, and stopes in hardrock and coal mines, especially where instrument access is limited. Ruggedness was a major consideration in designing the underground portion of the system and it has performed satisfactorily under extreme environmental conditions, including temperatures to 1100 F, 100% humidity, and falling water. The major advantage of the system is that it multiplexes the data from 16 channels through a single twisted pair cable to the receiver, significantly reducing cabling requirements. This receiving station can be as far as 8,000 ft from the instruments without the addition of line drivers. The receiver maintains a data buffer with the latest scans, which is periodical 1 y accessed by a micro- computer, either locally or through a modem, that automatically records and reduces the data. Utilities allow on-site plotting of data and uploading of data to mainframe computers.

Jan 1, 1986

By A. M. Galperin

Back analysis is a very important procedure for proper understanding of physical processes. Back analysis can be used to establish the role of different factors, define parameters to be calculated and formulate the behavior of natural or physical processes based on field experimental results. It is evident that, in order to obtain the necessary data for back analysis, field observations are required. For the Michailovsky region (Kursk Magnetic Anomaly, KMA) the long-term strength characteristics of the clay covering the quarry slopes were established with the help of back landslide calculations. The obtained data allowed quantification of the shearing resistance parameters at the presence or absence of intermittent dips of discharge in the pit bank massif structures. Based on the results of investigation for material composition, strength and deformation of finely dispersed (clay-chalk) deposits in the Kursk Magnetic Anomaly including measuring of the settlements of filled structures, complex probing and laboratory determination of water-physical and mechanical properties of "man-made" soils, engineering-geological zoning of filled structures was carried out.

Jan 1, 2005

By James W. Mahar

The following paper summarizes our observations on building response to mine subsidence and techniques for mitigation of building damage. The subsidence cases are located in Illinois. The general description of the geologic and mine conditions are primarily for those sites. Data on building response and mitigation measures were collected under grants supported by the Abandoned Mined Lands Reclamation Council (AMLRC) of Illinois and the U. S. Bureau of Mines, in Twin Cities, Minnesota. Case histories include pit and sag subsidence primarily beneath abandoned room and pillar mines. The majority of the paper deals with structures affected by sag subsidence. Most of the structures are one and two story homes. The first section of the paper summarizes the typical geologic and mining conditions at the sites. Building response to pit and sag subsidence follows the first section. Emphasis is placed on the behavior of concrete and masonry foundations, and wood frame and masonry superstructures. The third section describes mitigation techniques used to prevent or minimize building damage. A summary of the observations and critical parameters is given at the end of the paper.

Jan 1, 1982

By Jon P. Thorson, James W. Babcock

The second Belt Symposium in Missoula, MT, Oct. 9-16, 1983, was designed by its conveners as a field conference on progress in the Proterozoic Belt Supergroup rocks. The symposium was sponsored by the University of Montana with corporate support by Anaconda Minerals. Asarco Inc., Exxon Minerals Co.. Hecla Mining Co., Molycorp Inc., Noranda Exploration Co., and Utah International Inc. Introduction The Belt Supergroup is a thick middle Proterozoic sedimentary sequence deposited in a basin along the edge of the North American craton. Subsequent geological events have modified the basin so its remaining rocks outcrop in Montana, Idaho, northeast Washington, southeast British Columbia, and southwest Alberta. The Canadian equivalent of the Belt is called the Purcell Supergroup. Several similar age basins occurred along the western edge of the Proterozoic North American craton. The sedimentary sequence in the Belt basin aggregates is more than 18 km (60,000 ft) in the thickest section, where the bottom is still unexposed and the top removed by erosion. The limits of the Belt basin are poorly known because of later sedimentation and tectonic disruption. Knowledge about the Belt terrane has been difficult and tedious to obtain because the rocks are generally monotonous and fine-grained. During the last decade, new 1:250,000 scale reconnaissance maps of most of the Proterozoic Belt terrane were published, open-filed or otherwise brought close to completion. These maps provided the opportunity and challenge to consider the stratigraphy and tectonics of the Belt Supergroup as a complete basin. This broader view has contributed greatly to the solution of numerous geological problems created by previous, more focused work. Along with the availability of better geological base, there have been new exploration developments. The 1973-1983 decade saw proof of the commercial viability of the Cu-Ag mineralization at the Troy mine. The conclusion was also accepted that the Sullivan mine was a sedimentary massive sulfide. So was the conclusion that the Cu-Co mineralization at the Blackbird mine at Cobalt, ID, was the result of similar submarine exhalative processes. And there were discoveries of another Cu-Ag deposit "larger and higher grade" than the Troy mine and of two new massive sulfide districts. The Belt-Purcell terrane has long intrigued exploration and mining geologists as the host of Pb-Zn-Ag veins of Idaho's Coeur d'Alene district and of the Sullivan mine at Kimberley, British Columbia, one of the largest Pb-Zn-Ag deposits in North America. In the mid-1960s, Bear Creek Mining Co.'s discoveries of the stratabound copper-silver occurrences in the Revett Formation brought new interest in the basin's geology. The recognition of the Sullivan ore body as a sediment-hosted massive sulfide has also generated minerals exploration activity in the US portion of the Belt basin. This activity increased again after the Australian discovery of the world class Olympic Dam deposit at Roxby Downs, South Australia. This occurred because of some suggested similarities in the regional geologic setting of the Belt basin with the Adelaide geosyncline, the host for the Olympic Dam deposit. Technical Sessions Technical sessions topics included Lower Belt and Ravalli Group stratigraphy, Middle Belt carbonate and Missoula Group stratigraphy, Belt-Purcell stratigraphy, structure and tectonics, strata-related mineral resources, geochronology and geophysics, geochemistry and isotope geology, and a summary of significant problems. Evening poster sessions dealt with the topics and papers presented each day. Since the first Belt Symposium, mapping of the stratigraphic units and their tectonic setting has enabled geologists to progress in conducting a basin analysis. Belt Symposium II revealed no concensus on many aspects of belt geology. However, basic stratigraphic studies have reached the point that models can be constructed. The Prichard Formation is equivalent to the Aldridge Formation, but detailed correlations were not previously available. Studies were made by Finch and Baldwin (Cominco American) and by Cressman (US Geological Survey). These studies established important correlations of key markers within the Aldridge Formation to units in the Prichard Formation. This will help eliminate geologic interpretation problems at the US-Canada frontier and make Belt basin reconstruction more accurate. Also, the Sullivan ore deposit was shown to be formed in the deeper distal part of the basin. This contrasts to the more proximal depositional position of the Prichard Formation. Hamilton

Jan 6, 1984

By Calvert D. Iles

Open-pit mines in the US and throughout the world are typically characterized by increasing operating costs and decreasing ore grades. Thus, companies must continue to improve their use of human and technological resources to remain competitive in the marketplace. Duval Corp. has historically been very sensitive to mining costs, in part because of relatively low grade copper-molybdenum ore bodies. These concerns have resulted in three haulage system generations at the 218 kt/d (240,000 stpd) Sierrita-Esperanza open-pit mine south of Tucson, AZ. Each generation has exceeded the performance of the one replaced. The latest system of portable crushers and conveyors reduces hauling costs by combining both hardware and technique. Savings are achieved not only bysubstituting conveyors for haul trucks, but also by permitting the crusher-convey or system to closely follow mining as the pit deepens and/or mining areas change location. The Duval system is capable of easy and inexpensive relocation in varying site configurations in relatively short time periods. Its implementation in active mining areas results in minimum disruption to both the mine operation and mine design. This haulage concept allows the mining engineer maximum freedom to design an open pit for profit rather than for equipment. Maximum savings with a portable system are achieved by minimizing truck haulage costs. At Sierrita, for example, the yearly estimated operating cost savings for each thousand feet of +10% truck ramp replaced by conveyors is about $1 million per portable crusher. A savings of $30 million could be achieved fora three-portable system overa 10 year period simply by reducing the average truck Iiftto the crusher by 30 m (100 ft), There is also the added capital expense of buying trucks to cover the additional 30 m (100 ft) of lift. Relocation costs are an important consideration in a portable system. Direct costs can become a significant operating expense if frequent relocations are necessary to take full advantage of potential haulage cost savings. A site preparation cost of $375,000, for example, would add an additional operating cost of 2.8¢/t(2.5¢/st) for a system handling 13.6 Mt/a (15 million stpy), assuming one move a year, In addition to the direct cost of site preparation, such as installation of retaining walls, apron feeder slots, and equipment pads, there is the cost of site renovation after abandonment. Indirect relocation costs, while less tangible and more dependent on specific mine design and scheduling, can be of significance. A slowdown in the mining rate or a less efficient mining plan can result from a site not being immediately available for mining after abandonment. Conversely, mining in narrow areas can be adversely affected if two or three month lead times are required for site preparation.

Jan 4, 1983

By A. L. Muler

Since 1956, when Broadbent and Callcott 1 proposed to analyze breakage processes by matrix methods, several authors and their co-workers have proposed various models of grinding that, in principle, could lead to fully automated grinding circuits. In particular, Meloy and Gaudin2, Gardner and Austin3, Kelsall and Reid4, Neloy and Bergstrom5, Callcott and Lynch 6, and Draper and Lynch have, by either computer simulation or by experimental data, or by a combination of the two, verified that comminution is reasonably well described by at least two functions: a selection function and a breakage function. The stage concept proposed by Callcott and Lynch6 requires that a classification matrix be included to completely describe breakage in an open circuit rod mill. The purpose of this work, portions of which are herein described, is to accumulate sufficient information on the breakage characteristics of quartz and magnetite in an open circuit rod mill, so that several of the theoretical and experimental approaches proposed in the literature can be compared with each other. Data is being gathered to compare the experimental method used by Kelsall and paid against the stage approach of Callcott and Lynch.

Jan 1, 1968

By K. A. Natarajan, M. K. Yelloji Rao

The electrochemistry of sphalerite and chalcopyrite was investigated under both open-circuit and applied potential conditions. Emphasis was placed on the selective dissolution of sphalerite from a mixture of sphalerite-chalcopyrite flotation concentrates as a function of applied potential, acid concentration, pulp density, and time. Morphological studies using a scanning electron microscope (SEM) were also carried out with chemically leached, galvanically leached, and unleached surfaces of sphalerite and chalcopyrite. Selective dissoulution of sphalerite could be achieved if the mixed chalcopyrite-sphalerite concentrate slurry was maintained at a negative applied potential of -0.4V (SCE). Probable mechanisms involved in the selective dissolution of zinc are disscussed.

Jan 1, 1990

By Darryl J. Butcher

The Akjoujt Project is operated by MORAK SA, a company incorporated in the Islamic Republic of Mauritania. MORAK is jointly owned by General Gold International SA (A wholly owned subsidiary of General Gold Resources NL.), SAMIN, and the International Finance Corporation. The project was devel­oped to treat approximately 2.1 million tonnes of TORCO (Treatment of Refractory Copper Ores) tailings containing an average 3.2gAu/t, and 0.75%Cu/t. The process involves the use of ammoniacal cyanidation for gold extraction, and conventional carbon adsorption, and eventual desorption, of gold values. This is believed to be only the second commercial application of this leach chemistry in the world. The other being a small vat leach operation on the Paris Mine Dumps. (This operation was described by Mr M Ruane in a paper to a previous Randol Forum.) Initial work on the process, and the Akjoujt process design assumed that the reaction involved was anaerobic. This paper describes the operating experience, plant trial, and eventual installation which has lead MORAK to the conclusion that the process is not anaerobic, but requires oxygen, or an oxidant to proceed.

Jan 1, 1995

By C. Cassios

EIA is a procedure aiming the elimination of adverse impacts to the environment from undertaken projects. Historically, it starts in 1969 when NEPA (Nat.Env.Prot.Agency) in the US initiated the EIA ? EIStatement. The EIA procedure was adapted by the European Union with the directive 337/85 and in Greece the Common Ministerial Decision 69269/90 enforced it to the Greek legislation. However, mining enterprises in Greece long before the implementation of the European Directive and in accordance to the legislation of the Public Law 998/79 for the protection of the forested lands were obliged to submit EIA?s and get an approval in order to operate in forested areas. The submitted and approved EIA?s and their implementation by the mining companies were among the positive aspects of the EIA procedures. This paper is examining the impacts of EIA?s in the Greek mining industry its positive aspects as well as their difficulties and their role for the reclamation procedure. The technical and procedural aspects which EIA presents for the mining industry are commented, while proposals, for a more flexible EIA implementation for the Greek Environment are also presented.

Jan 1, 2002

By H. Bernatowicz

The Nucoalyzer (On-Line Nuclear Analyzer) is a new method recently made comercially available for monitoring the elemental composition of a process stream. Applications for the Nucoalyzer include grading ore on a conveyor belt before or after it has gone through primary crushing, monitoring the slurry being transported in a pipe to the concentrator, and monitoring the stream of concentrate or the tailings from the concentrator. The Nucoalyzer may also be used at the smelter to monitor elements in the feed that include copper, sulfur, iron and silicon where a uniform feed is desired. The advantage of the Nucoalyzer over most other techniques are (a) it performs the measurement directly on the process with no sampling necessary, (b) the analysis can be performed on streams of particulate and slurries, and (c) the system does not have to make contact with the material it measures. These Nucoalyzers are operating at coal fired power plants and several more are about to be placed in service. This paper discusses the principles of operation of the Nucoalyzer, our experience in the field, application of minicomputers to data reduction, and potential applications in the ferrous and non-ferrous industries.

Jan 1, 1982

By E. A. Rychkun

It is essential for a. mining company to determine an optimal mining strategy which will maximize the return on investment. In the case of Placer Development Ltd., the Lerch-Grossman three-dimensional optimization technique has been implemented on a digital computer to assist in the determination of such a strategy. It is the purpose of this chapter to explain and illustrate the methodology of the Placer Development Ltd. computer system with emphasis on the feasibility phase of a mine's development. In the Placer Development Ltd. strategy determination process, it is essential that certain objectives be considered: 1) There must be some means of constructing a realistic computer model of an ore body which gives a significant weight to geological constraints. 2) Data must be accurate and quantifiable. 3) Computer solutions must be unique, i.e., approximation or iteration methods of determining optimal solutions are undesirable. A method must be used which, when given fixed parameters and data, yields a mathematically sound unique solution. The following material is a presentation of how these objectives have been implemented. The flow of this outline will be from the general to the specific, with an example application.

Jan 1, 1979

By Timothy F. Markey, Brian C. Strohm

This paper presents a case study which applies risk assessment techniques in evaluating potential environmental problems associated with past waste disposal practices at a 65 acre non-ferrous metals and metal alloys manufacturing facility. Waste management activities at the site involved a number of surface impoundments for gangue material, neutralized acid rinse waters, acid rinse sludges, demolition debris, storm water runoff, stockpiled ores, and a permitted residual waste landfill. As a result of these activities, the She contained 9 identifiable waste management areas impacted by over 35 potentially hazardous chemicals and metals. Extensive environmental data obtained from investigations at the Site revealed heavy metal and volatile organic chemical contamination in various environmental media. These data were utilized to evaluate potential risks to human health and the environment. The human health risk assessment estimated potential health risks to workers, residents, and Site trespassers under current and expected future uses of the Site. Areas of the Site were identified which were considered to present potential health concerns under the various exposure scenarios. Results from the human health risk assessment were utilized to develop cost effective risk based soil remediation goals protective of the public health and environment.

Jan 1, 1992

By Robert C. Cifelli

INTRODUCTION Background and Objectives Underground coal mining is a vital component of West Virginia's economy. However adverse environmental effects including ground subsidence and aquifer dewatering are often associated with such mining activities. Many families in northern West Virginia still rely on private water wells and springs for domestic water needs. In such areas where underground coal extraction and land subsidence have occurred, a disruption of the ground water flow system commonly exists with subsequent drainage of water to lower levels that may extent as deep as the mine workings; this causes loss of water supplies to landowners and represents a nuisance to mining companies 2 This report represents a summary of an M. S. thesis project in geology at West Virginia University by the senior author (3). The intent for this study was to document the effects of underground coal removal on ground water levels at selected mine sites in northern West Virginia, as observed from water wells, springs, and streams. This research should be useful to coal companies and regulatory agencies and aid in recommendations of future water well locations and specifications in areas of existing or proposed underground coal mines.

Jan 1, 1986

By A. C. Noble, D. E. Ranta, J. W. Mustard

Skarn deposits present many unique problems in estimating ore reserves, including difficulties arising from the complex character of the mineralization and intricate ore body shapes resulting from structural complexity. Mineralization within skarns occurs in metasomatically altered carbonate horizons produced by magmatic hydrothermal fluids emanating from intrusive stocks. Deposit formation is controlled by both the presence of favorable host rocks and by proximity of these host rocks to a mineralizing intrusion. Ore controls must be defined to account for abrupt changes in grade that occur between miner- alized and unmineralized horizons. Gradational grade changes within the mineralized zones must also be defined in terms of skarn type and included barren rock to assist in reserve estimation. Defining mineralized limits can be further complicated by faulted, rotated, or folded strata affecting the morphology of an ore body. The MacTung copper-tungsten exoskarn deposit, located along the Yukon-Northwest Territories border in Northwestern Canada exhibits a number of unique properties that preclude a simple mathematical approach to ore re- serve estimation. This deposit is used to demonstrate methods for modeling geologic controls and geostatistical properties for a skarn deposit.

Jan 1, 1992

By M. Phillip Jameson, Paul Sennett

The beneficiation of kaolin by flotation has been practiced on an industrial level since 1961. A brief history of industrial kaolin flotation is given, with a description of the various processing schemes used by the companies that practice kaolin flotation. Some of the areas where improvements could be made in the beneficiation of kaolin are given.

Jan 1, 1989

By G. H. Khoe

addressed in a number of studies in the past. In this paper, the stability of a ferrous arsenate compound is evaluated using a solution model and the thermodynamic data which were determined for the system. The environmental stability of the ferrous arsenate precipitate is compared with the literature data for ferric arsenate and arsenate-bearing ferric hydrous oxide.

Jan 1, 1991

By Pramod C. Thakur

Floor gas emissions on wide longwall faces are common occurrences in the Northern and Central Appalachian basins. It creates unsafe working conditions on the face and results in very costly production delays. This paper discusses various methods of mitigating the floor gas emissions including hydrofracing of underlying strata, use of cross-measure boreholes and specifically completed gob wells.

Jan 1, 2005

By S. El-Mofty, P. Zhang, N. A. Khalek

This article reviews different technologies used for beneficiation of siliceous and calcareous phosphate ores of different origin. The review sheds light on recent trends suggested for solving problems associated with separation of different impurities from phosphates. Applications of recently modified flowsheets as well as new reagents in the flotation of phosphate ores of sedimentary origin are highlighted.

Jan 1, 2003

By S. J. Ripke

To pelletize fine moist magnetite concentrate, a 40% water slurry must be dewatered to about 10% by filtration, before it can be agglomerated into pellets. Slurry pH, typically ranging from 8 to 11, gives the magnetite particle surface a strong negative charge and thus causes two adverse effects. First, this negative charge attracts calcium and magnesium cations, which strongly retard the effectiveness of the bentonite clay binder added during agglomeration. Second, a repulsive force created by the negative charge functions as a dispersant that reduces filtering production rates. Tests were conducted to remove these cations during filtration, by rinsing the moisture remaining in the filter cake with a small amount of water adjusted to pH 6 with HCl. Laboratory work was also conducted at Michigan Technological University (MTU) and at Cliff’s Mining Services Company (CMSC) to corroborate the plant tests. In some cases HCl caused filter bag blinding, therefore CO2was investigated to reduce pH. The CMSC lab tests showed that using carbon dioxide to reduce slurry pH from 7.6 to 7.0 improved filtering production rates by 11%. Plant-scale filtering rates were improved by 23.7% when carbon dioxide addition reduced the slurry pH from 8.6 to 6.7.

Jan 1, 2004

By Jeanne A. Zimmer, Andrew B. Cecala, Edward D. Thimons

The Bureau of Mines performed a study to determine optimal locations for longwall face methane monitoring equipment. Longwall face ignitions continue to be a concern to the U. S. coal mining industry. Gains in ignition control technology have been somewhat negated by advances in longwall productivity. More reliable, heavy-duty longwall face systems generate higher production rates and increase methane liberation rates. These rates will likely continue to rise in the future as further coal production increases occur. Efforts will continue in the areas of methane drainage, methane containment, and methane dilution. In addition, more effective face methane monitoring is needed. As technology continues toward automated longwall panels, the importance of monitoring for methane at the shearer becomes even more significant. Since the primary face ignition source is the shearer mining machine, the Bureau ran tests to determine the best location to take methane readings on the shearer. This information, in conjunction with data obtained from field studies, provides a knowledge base for selecting optimum face methane monitoring locations. INTRODUCTION Face ignitions are a concern for many U. S. longwalls and will continue to be until better control technology can be developed or until reliable and accurate knowledge can be provided as to when an explosive concentration is present. Figure 1 shows the number of reported U. S. underground longwall ignitions from 1980 to 1990. The number of longwall panels have remained relatively constant over this time period with 89 reported in 1980, compared to 96 in 1990. In spite of technological improvements in mining over the past decade, no significant reduction in the number of longwall face ignitions has occurred. One factor contributing to this is that the U. S. coal industry is mining gassier seams causing methane liberation rates on the average to be higher (Trevits, 1991; Grau, 1987). Another factor is the development and implementation of more reliable, heavy-duty longwall face systems that are generating higher production rates and higher methane liberation rates. Additionally, the average panel width in 1991 was 714 ft; a 44 pct increase from 1980 when faces averaged a width of 495 ft (Merritt, 1992). Increases in panel width also impact total face methane emissions. [ ] There have been substantial advances in control technology in the areas of methane drainage, methane containment, and methane dilution. In some mines, efforts to drain methane in advance of mining have proven effective, but geological conditions often preclude this approach (McCall, 1984; Ely, 1989). In other cases, ventilation air quantities of over 100,000 ft3/min and face velocities of over 1,000 ft/min have been implemented on longwall panels. Other operations have implemented anti-ignition spray systems which use water sprays behind each cutting bit to quench the hot streaks created from cutting noncoal materials (Courtney, 1990). Other control techniques, such as the modified shearer clearer system and ventilated drum, have been used to increase the amount of turbulence and ventilation around the cutting drums, thus reducing methane levels (Cecala, 1986; Divers, 1987).

Jan 1, 1993