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By K. C. Watts

The Silver City mining region is located in Grant County, southwestern New Mexico (Fig. 1). This area is well known, having produced large tonnages of base and lesser amounts of precious metals over the past several years. Mining within the region continues today, as well as exploration activity, which seems to have been on the increase since the recent discovery of a large skarn-associated Zn-Pb-Cu replacement deposit near Pinos Altos, a mineral district within the region (McKnight and Fellows, 1978). Because the Silver City area contains a number of mineral districts and retains promise for additional deposits, as suggested by widespread hydrothermal alteration and favorable igneous rocks, it was selected as the focus of two independent geochemical studies, both seeking to enhance anomaly-to- background contrast in order to improve our abilities to detect blind metal deposits or subtle manifestations of near-surface occurrences. The first of these independent studies involved the systematic sampling of those secondary Fe-Mn oxides that occur within coatings, selvages, and fault fillings, and then the selective extraction of these oxides from the host-rock matrix by chemical methods. The second study sought to isolate clastic Fe-Mn-rich materials from the heavy fraction of stream alluvium. The ultimate source of the clastic Fe-Mn oxides is presumed to be the same coatings, selvages, and fault fillings sought by the direct sampling of joints, but has been transported as a result of lateral erosional processes.

Jan 1, 1981

By Yoshiak Mizuta, Hi Keu Lee

The manuscript of this paper was not available for publication when the Proceedings went to press. Should the authors elect, they may distribute copies at the time of the Symposium

Jan 1, 1986

By Myles E. Robinson

During the last decade there were pronounced changes in the competitive pattern of the fossill fuels It is proposed to trace these trends and describe inter-fuel competition, first as it relates to the economy as a whole and then more specifically to examine competition of the fossil fuels as these share the electric utility market. Table 1, Competitive Fuels and Water Power Used in the United States, 1950-1959, shows the growth in the consumption of coal, oil, gas and water power 'during the past decade. Uses which are not directly competitive among the fuels, such as tractor fuel, carbon black, and consumption of petroleum products in the making of synthetic rubber, have been excluded from these statistics. The experience of the three fossil fuels in competition since 1950 shows natural gas expanding more rapidly, than oil by roughly twice as much, 219.0 percent' compared to 124.1 percent growth in B.t.u.s of oil consumed in the ten-year period. Percentagewise, water power little more than held its own, and coal, including anthracite, actually decreased more than one-fifth.

Jan 1, 1961

By Richard L. Stein

INTRODUCTION Increasing a miner's chance of surviving a disaster requires advance planning for emergencies, adequate training of personnel, and the provision of proper survival equipment. It is extremely important that fires and toxic gases be detected early, and that warning systems such as stench, audible and visual alarms, and communications systems be provided to allow timely escape. However, situations do occur where timely warning is not provided and immediate escape is not possible, regardless of the precautions that are taken. Under such circumstances, a combination of new per¬sonal protective devices and old techniques can provide protection that is adequate to save a miner's life. SELF-RESCUE EQUIPMENT Self-rescuers are devices which provide a short-term supply of respirable air under the potentially lethal con¬ditions following a mine disaster. Functioning either as filtration devices for the elimination of carbon monoxide (CO) or as oxygen supplies, self-rescuers allow an endangered miner a limited amount of time in which to effect an escape or reach a place of temporary safety. Carbon-Monoxide Self-Rescuers For almost 50 years, filtration self-rescuers have protected miners' lives following explosions or fires. Designed to eliminate carbon monoxide from inhaled air, the first of these devices was approved in the 1920s and has evolved into the two units that are approved today-the Mine Safety Appliance (MSA) W-65 and the Draeger 810. Both of these units rely on the cata¬lytic conversion of very toxic carbon monoxide to rela¬tively safe levels of carbon dioxide (CO,). As shown in Figs. 1 and 2, both of these filtration self-rescuers operate in the same manner. On inhalation, the mine air passes through both coarse and fine filters that remove the dust, preventing the dust from coating the chemical beds or entering the miner's mouth. The air then passes over a drying agent that removes water vapor; this is required to prevent the water vapor from poisoning the catalyst. Subsequently, the dried air passes over the Hopcalite catalyst, where carbon monoxide is converted to carbon dioxide. Then, the air passes through a heat exchanger that reduces the temperature of the inhaled air. Finally, the air is inhaled by the user. Air exhaled by the user passes through the heat ex¬changer and exits the device through an expiratory valve. Both units of this type are subject to certain limita¬tions: 1) The units do not protect the user against oxygen¬deficient air; when air is inhaled through this type of self-rescuer, the device only removes the carbon mon¬oxide. If the mine air contains less than 15% oxygen, anoxia is inevitable. Symptoms of anoxia include dizzi¬ness, shortness of breath, quickened pulse, and deeper and more rapid respiration while the victim is at rest. During heavy exertion such as would be expected dur¬ ing escape efforts, a 15% oxygen level can cause loss of consciousness. 2) The units do not protect against excessive levels of carbon dioxide. Available data on carbon monoxide and carbon dioxide concentrations following explosions or fires are limited, but there are indications that the carbon monoxide concentration can rise to 2% and the carbon dioxide concentration can reach 5 or 6% of the mine air (by volume). In some situations, the in¬haled air could contain up to 6 or 7% carbon dioxide. At a carbon dioxide concentration higher than 2%, breathing patterns can be affected adversely. At a con¬centration of 6 or 7%, the effects include severe respira¬tory distress, with unconsciousness resulting from exer¬tion such as that needed for escape activities. 3) The units do not protect against high inhalation temperatures. The catalytic oxidation of carbon mon¬oxide to carbon dioxide is an exothermic reaction that evolves a large amount of heat. As the carbon monoxide concentration increases, the temperature of the inhaled air also increases. Available data show that above 1.5% carbon monoxide, the air inhaled through some self¬rescuers can be as high as 90°C (194°F). At those

Jan 1, 1982

By V. F. Hollister

Epithermal gold deposits occur in and near the marginal fault that circumscribes the Goldfield, Nevada, Tertiary caldera. The gold occurs disseminated in alunite, pyrite, and kaolin- bearing silicified zones that are controlled by the circular faults. Other Tertiary calderas (i.e., Summitville and Red Mountain No. 3) have epithermal disseminated gold deposits located in and near their marginal circular faults in settings that resemble the Goldfield example. These additional caldera- controlled epithermal gold deposits are also characterized by alunite, pyrite, and kaolin-bearing silicified rock that act as hosts for the gold disseminations. The Goldfield District is therefore an exploration model for those seeking disseminated epithermal gold deposits in a caldera setting.

Jan 1, 1986

By Jonas Svensson

The Grangcold Pellet Process - for which patents have been applied or already granted in a number of countries - uses a hydraulic adhesive such as Portland cement, slag cements, pozzolanic cements, etc., for the production of cold bonded pellets. The idea of using a hydraulic binder for the agglomeration of iron ore fines is not new. Portland cement was proposed as an adhesive for cold bonded iron ore briquettes in patents granted more than 50 years ago (1). In a report on the briquetting of iron ore fines, published in Stahl and Eisen 1959 (2), it is stated that briquettes bonded with Portland cement are used on a small scale at on ironwork in Germany. According to the report, the briquettes showed excellent strength in the blast furnace although their general use was made impossible because they required a long hardening time, during which they are sticky, soft and difficult to store and handle. The Grangcold Pellet "recess has overcome this particular disadvantage by mixing the balls with a suitable amount of the balling concentrate before storing them. The pellets are embedded in the concentrate during storing in such a way that they are isolated from each other and thus prevented from sticking together to form clusters. Thanks to the embedding concentrate, the pellets are subjected to a more or less uniform pressure from all sides which does not deform them. Thus the mixture can he stored in a stockpile or in a silo until the pellets have hardened sufficiently. The concentrate is separated from the pellets by means of screening. The concentrate is returned to the balling operation and the pellets are either shipped to the blast furnace or stored for final hardening.

Jan 1, 1969

By Cheng Xie, Zhihu Li, Xiaoming Sun, Linsen He, Jiaxu Ding, Jinkun Yang, Yong Zhang, Zhenmin Qi

To solve the problem of large deformation of deep soft rock roadway, taking the soft rock roadway of no. 1 coal mine in New Shanghai as an engineering example, the deformation mechanism of surrounding rock of deep soft rock roadway is analyzed by combining theoretical analysis, numerical simulation and field test, and the control countermeasures centering on deep and shallow dense drilling are put forward. Through theoretical derivation, based on the masonry beam theory, surrounding rock structure S-R stability principle and composite beam principle, the length, angle, and spacing of deep and shallow dense drilling are determined. Through numerical simulation, the deformation evolution process of soft rock roadway surrounding rock after dense drilling pressure relief is reproduced, and the influence of drilling parameters (drilling spacing, dip angle) on pressure relief effect is analyzed and compared. The field application test and monitoring verify that the deformation control measures of deep and shallow dense drilling broken roof surrounding rock have a good effect of large deformation control of soft rock roadway, and provide a new support means for the safety and stability control of soft rock roadway.

Mar 2, 2024

By David B. Brooks

I gratefully acknowledge the help of a number of American and Canadian geologists, in both federal surveys and in private firms, who took the time to discuss this problem with me. Hans Landsberg and Bruce Netschert also followed the study with interest and encouragement. In their 1961 monograph, THE FUTURE SUPPLY OF THE MAJOR METALS, Bruce Netschert and Hans Landsberg noted that identified potential resources (that is, known but submarginal resources) of lead and zinc were much lower relative to reserves (that is, known and supermarginal resources) than was the same ratio for other metals.1/ Put another way, it seemed that for such metals as iron, manganese, copper, and aluminum, slightly more favorable economic conditions or modest advances in technology would greatly increase reserves by permitting the exploitation of vest quantities of leaner or deeper or otherwise less valuable mineral deposits. But for lead and zinc, Netschert and Landsberg concluded that either: "(1) there is relatively little material below present cutoff grades; [or] (2) such material exists, but for some reason there are no data.? 2/ This situation, which they called "the lead-zinc anomaly" has been subsequently discussed by other authors. The purpose of this paper is to carry the discussion further by examining the evidence in favor of (1) and (2) and by advancing a third alternative.

Jan 1, 1967

By B. Ladanyi

An adequate knowledge of the overall behavior of a rock mass at a given site is fundamental to the satisfactory design of a rock slope. The be- havior is controlled by a variety of factors, in- cluding rock type, geological structure, stress and ground water conditions. There are essentially three lines of approach that may be used to obtain information on the in-situ rock mass behavior for the purpose of the design of a rock slope: (1) Direct measurements of rock mass properties by means ol laboratory and field tests. (2) Evaluation of rock mass properties from a study of slope failure case histories and sta- tistical information on stable and unstable natural rock slopes. (3) Evaluation of in-situ behavior of rock mass by using a physical or mathematical model technique.

Jan 1, 1980

By Yun-tao Xin, Yu Yi, Kang Yan, Gang Li, Xiao-dong Lv

This study investigated the selective removal of arsenic from high-arsenic dust in alkaline systems and the effects of different leaching conditions. The results indicated that the liquid–solid ratio, NaOH concentration, and sulfur dosage had a significant influence on the process. The leaching efficiency of arsenic reached 99.57%, while that of lead was as low as 0.03% under appropriate conditions. In particular, the addition of sulfur can effectively promote the leaching of arsenic and reduce the dissolution of lead in the solutions. An artificial neural network was used to model the leaching process. It consisted of a back-propagation artificial neural network model with a “6–10–2” structure that could effectively simulate and predict the value with more than 99% accuracy. Based on the difference in weights of the different parameters in the neural network model, the relative importance of the parameters related to arsenic and lead leaching efficiency was obtained, which followed the order of NaOH concentration, liquid–solid ratio, sulfur dosage, temperature, time, and stirring speed.

Jul 29, 2021

By J. A. Organiscak

Two types of airflow splitting methods for improving longwall dust control were investigated by NIOSH's Pittsburgh Research Laboratory. These methods included a translucent mesh barrier and a staged spray barrier system to confine the shearer-generated dust to the coal extraction side of the long wall face while maintaining a cleaner split of airflow on the opposing worker walkway side of the longwall face. The translucent mesh barrier was shown to provide notable dust control effectiveness up to 60 m downstream of the shearer in both the laboratory experiments and a long wall field evaluation, provided the mesh barrier remains relatively parallel to the airflow. The staged spray barrier system showed marginal dust control effectiveness in the laboratory and subsequently was not field tested.

Jan 1, 1999

By G. A. Rosario, G. Peach

Twin 8.5 m diameter, 10 km long headrace tunnels under overburdens of up to 1870 m were excavated for the neelum jhelum hydroelectric project in north-eastern pakistan using two main beam gripper tunnel boring machines (tbms). Rock bursts were encountered and presented a significant danger to personnel and equipment. Micro seismic monitoring was installed to analyze rock burst characteristics and to create a database for future reference. Correlation of rock burst characteristics improved the ability to predict the likelihood, location, severity, and number of rock burst events. This paper presents the analysis of the micro seismic data

Dec 1, 2022

By Jeffrey J. Daniels

Advances in borehole geophysical research for mineral assaying, and remote detection of mineralization away from the borehole. Nuclear activation measurement research has provided accurate in situ assays of economic metals with neutron-gamma activation, using a high resolution intrinsic-germanium detector. Although nuclear activation analysis is the present "best-hope" for obtaining in situ assays for some elements, gamma-gamma and magnetic susceptibility measurements can provide accurate assays for lead-zinc and magnetite, respectively. Borehole optical spectroscopy and x-ray fluorescence are being investigated as possible in situ assaying techniques for some minerals. More laboratory and field calibration research is needed before nonlinear complex resistivity (NLCR) can be routinely used as a quantitative assaying tool. Field tests have shown that variations in the local geologic environment can affect the quantitative accuracy of assay values from downhole NLCR measurements. Deeply penetrating borehole geophysical methods are increasingly being used for mineral exploration as drilling costs and exploration have increased. Borehole electrical measurements have been shown to be useful for detecting conductive orebodies that are not interesected by a drillhole. Hole-to-surface resistivity, and surface-to-hole time-domain electromagnetics are demonstrated to be particularly effective for defining mineralized zones in a massive sulfide environment. Borehole gravity meters and three-component magnetometers have been developed and should prove useful for defining geologic anomalies away from the drillhole.

Jan 1, 1985

By M. T. Atwood

For more than sixty years the rich oil shale formations of Colorado, Utah and Wyoming have been evaluated as a future source of petroleum. After many false starts the commercial production of shale oil is near. Union Oil and Colony (Exxon and Tosco) have begun construction of commercial plants. Occidental and Rio Blanco (Gulf and Standard of Indiana) are well along in the development of modified in situ (underground) processes. A number of other companies and groups are in advanced stages of development. This paper will review some of the major elements involved in the production of shale oil with emphasis on means available to express the efficiency of production of pyrolysis liquids and gases from oil shale rock.

Jan 1, 1982

By P. Schilizzi

The increased impact of mining subsidence in the U.S. coalfields and the recent regulatory constraints legislated by government and state agencies have provoked an intense research effort on this topic by government agencies, coal companies and academic institutions. Subsidence and horizontal strain predictions are a basic requirement if subsidence and its associated effects are to be controlled and contained within acceptable environmental levels. As a result, several such prediction techniques have been proposed or are currently under development to assist coal operators in minimizing the detrimental effects of these surface deformations. VPI&SU has been actively involved in this research effort in the past few years, with particular emphasis on the Appalachian coalfield. During the initial stages of this research a large number of subsidence case studies were collected from the literature, the coal industry and government agencies. In total, data from 32 longwall panels and 60 room and pillar panels were collected. This data bank was used to determine relationships between the basic mining and subsidence parameters, in order to allow the evaluation of the various prediction methods for the Appalachian coal region. Based on this data two subsidence prediction techniques, one based on profile functions and the other on influence functions have been developed. Profile function methods provide a tool for a fast calculation of subsidence on a line across a mine panel. Influence function methods, on the other hand, allow for a more detailed calculation of ground movements, in any mode and at any depth, on a grid or at any specific point. The limitations of the data of the collected case studies, i.e. accuracy of surveys, frequency of monitoring, lack of horizontal movement measurements, etc, led VPI&SU to the initiation of a detailed subsidence and strain monitoring program above a number of active mines, located in three major coal producing counties of Virginia. The aim of this program was to enhance the data base with accurate and complete measurements of surface movements and to allow, therefore, the refinement of the prediction techniques. This paper presents this monitoring program, discusses in detail the results obtained from three specific case studies and provides recommendations for the implementation of the field data in the general prediction methods.

Jan 1, 1986

By Hugh R. Wilson

Echo Bay's Waste Management Program for its Lupin Mine was developed in response to the terms and conditions of the water license issued to the mine in 1981 by the Northwest Territories Water Board. The gold mine, located about 80 km (50 miles) south of the Arctic Circle, commenced production in 1982. The Waste Management Program was based originally on the total containment concept, contingent on future treatability testwork results indicating the best treatment method to ensure pond discharges would be in compliance with stated Northwest Territories Water Board discharge criteria. To assess the various treatment technologies, an investigative program was established to determine the most effective means for treating the tailings pond water. In the course of milling, about 850,000 m3 (11 million cu yd) of tailings are produced annually that require appropriate management to protect the environment. This annual tailings stream consists of about 175,000 m3 (229,000 cu yd) of solids and 675,000 m3 (883,500 cu yd) of water. Following the completion of the required waste management studies, a two-ponds-in-series concept of tailings impoundment was developed. To attain this concept, the tailings impoundment area would require modification and construction to enable the use of such a system.

Jan 1, 1991

By Manuel Gomez

This report presents prediction equations for eleven factors indicative of metallurgical coal quality which have been developed from data obtainable during exploration. Five coke strength parameters and six carbonization product yields have been predicted for coking coals having volatile matter contents in the range 16.3 to 42.1 percent, dry basis. The prediction models developed contain information from the proximate and ultimate analyses, the size consist, and the petrographic composition of coking coals carbonized in BM-AGA retorts at 800°, 900°, and 1,000°C. The equations reported have been evaluated with independent data derived from the 900°C carbonization of 33 binary blends. Present results show that metallurgical coal quality can be predicted ahead of mining. Capability to forecast coal quality is useful in mine planning and should provide basic information for optimization of blending and crushing techniques, leading to the production of uniform coke.

Jan 1, 1968

By James Charles McHardy

During 1980-2000, the Florida Phosphate industry will deplete its Central Florida Polk County reserves. As a result, new mines will be built in the ?so-called? Southern Florida Reserve areas. These new mines will require new mining, beneficiation and tailings disposal technologies in that the southern reserves have different characteristics than have been encountered in the Central Florida deposits furthermore, government regulations will necessitate the development of new tailings and clay disposal methods. This paper reviews these challenges for the phosphate industry and how these opportunities can be expected to effect plant design and plant operating practices.

Jan 1, 1981

By Martin B. Zimmerman

It is becoming evident that traditional methods of econometric analysis are inadequate in estimating-the long-run supply of minerals. Econometrics is limited to extracting estimates from observations of the theory predicts that the least cost deposits will be exploited first.1 The estimation of parameters from past data then must lead to biased projections of the future. Mining conditions in the future will be worse than in the past and it is the impact of the future conditions on cost that we need to know. In this paper we present a methodology for dealing with this problem. We estimate a "cumulative cost" function that yields the long-run marginal cost of mining as a function of cumulative output produced over time.2 This is relatively easy to do for coal mining in the United States where exploration for new deposits is not a major factor in supply. The first step of the procedure relates cost to the rate of output and to the geological conditions of the mine. The second step combines geological information on remaining deposits with the cost function to yield the cumulative cost function. A central theme of both these steps is the interaction of economics with geology. The best deposits are selected first and in each step of the estimation allowance must be made for this fact. The problem of depletion is part of the general problem of structural change. The change through depletion in the nature of the exploitable mineral stock is only one factor that calls for an analysis sensitive to the changing circumstances of the industry. The factors impinging most heavily on the coal industry today are the strict environmental regulations legislated

Jan 1, 1977

By R. Y. Wan

Recent research efforts have shown have shown selective solvation extraction of a gold cyanide ion-pair complex from alkaline cyanide solution is possible with organic phosphorus esters. These alkyl phosphorus esters such as tributyl phosphate (TBP) and di-n-butyl n-butyl phosphonate (DBBP) can selectively load gold to rather high levels, even in excess of 30 gpl. However, traditional stripping techniques are not particularly effective. In this regard, gold recovery by direct electrolysis of the organic phase has been found to be an interesting possibility. Further, the rate of direct electrodeposition from the organic phase can be improved significantly by using an aqueous/organic mixture. Direct electrodeposition of sheet gold from loaded DBBP was successfully accomplished at a current density of 8x10 4 amp/cm2 and 55°C from such a two-phase mixture with the aqueous phase as the continuous phase. No appreciable degradation the DBBP was found after 5 cycles of extraction and, electrodeposition. Finally, the applicability of the process strategy for an industrial situation was demonstrated by the successful treatment of waste gold cyanide electroplating solutions.

Jan 1, 1986