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By G. G. Marino

Little comprehensive information has been reported on the behavior of room-and-pillar mines. The objective of this paper is to present case data on mine failures in the Illinois basin for use in practice. Presented are results of an ongoing study and details on the site characteristics of cases where sags have developed on the surface. Site data are reported to show the geologic, mining, and sag conditions that existed. Sags mainly develop from pillar, floor, or pillar-floor failure. The character of the sags depends upon the type of mine failure as well as the overburden response.

Jan 1, 1989

By Agus Sasmito, SRIVATSAN JAYARAMAN SRIDHARAN, Akash Adhikari, Purushotham Tukkaraja

The amount of toxic fumes produced during blasting operation depends on the types of explosives used, product formulation, degree of confinement, conditions of use, and reactivity of the explosives with the host rock. Ammonium nitrate and fuel oil (ANFO) is still the explosive of choice due to its lower price and ease of use/loading. If not properly monitored and controlled, toxic fumes produced from blasting operations can have serious health hazards [1]. This paper presents a novel technique developed to track trapped fumes during a development blasting.

Aug 1, 2022

By R. H. Clarke

"INTRODUCTION Characterization of waste rock is frequently an oversight in mine planning which can contribute to significant delay in permitting and ultimately development. Thorough waste rock characterization is now a prerequisite to developing operating and closure plans acceptable to regulators and the public. BACKGROUND A long history of mine development has placed virtually all focus on the economic extraction and beneficiation of ore materials, while waste rock characterization and management received substantially less attention and consideration. Inadequate waste rock characterization has contributed to planning and management practices that are having unintended and unforeseen impacts to surface and groundwater, and in some cases lead to significant long term closure liability. In response, the regulatory community has developed guidelines for performing waste rock characterization during the pre- mine permitting process that in some cases seem onerous (BLM, 2013). Additionally, where a project proponent has not met these guidelines or results have been deemed “inadequate”, the Nevada Division of Environmental Protection and Bureau of Land Management (regulatory agencies) will only issue operating permits with rigid management practices to address the uncertainty, including requirements for lining waste rock facilities. WASTE ROCK CHARACTERIZATION FOR NEVADA PROJECTS Newmont Mining Corporation (Newmont) operations in Nevada approaches waste rock characterization like ore characterization, as it requires a similar investment of time, funding and attention to detail in order to pass public and regulatory scrutiny. Newmont follows a tiered approach to characterization that creates three over-lapping data sets representing an “escalation” in analysis at each tier, an approach that has thus far gained regulatory approval. “Tier 1” waste rock characterization for most Newmont projects begins with exploration drilling which follows internal standards and procedures. 20-foot composite samples are prepared from all drilling and analyzed for multiple trace elements using inductively coupled plasma mass spectrometry (ICP-MS) methods and for acid-base characterization using method ASTM-E1915. If the exploration program is successful and further resource or reserve development is recommended, the Tier 1 data are used to prepare a Waste Rock Characterization Plan (Plan) that will be presented to regulatory agencies as a part of baseline project characterization."

Jan 1, 2015

By Harrison R. Cooper

Approximately 40 concentrators throughout the world have successfully adopted computer control for flotation circuit operation since 1969. Successful use of flotation control, gaining up to 2% efficiencies, has largely derived from effective employment of on-stream slurry analyzers and integration of key measurement data through digital processors. Requirements for reliable measurement have also led to improved functional reliability in magnetic flow meters, pH, reagent feed, and other key elements. Methods used in computer control of flotation will be reviewed and variations in operating philosophies will be described with reference to the approaches taken to flotation automation.

Jan 1, 1979

By Dolf Vos

The balling section of the pelletizing plant at Hoogovens IJmuiden consists of 7 balling drums. Each with an average capacity of 100 tons of green pellets per hour. The balling drums are equipped with rotating scrapers and water-spraying systems. The scrapers are installed in order to restrict the growth of the race to a certain thickness. The spraying system is used to adjust the desired value of the moisture-content of the rewetted ground ore, the pellets and the race. The desired value is the value by which the balling- process is stable, good pellets are formed and surge occurs within certain limits. In October 1980 the construction of one of the balling drums has been modified. The rotating scraper was removed and the inner wall of the drum was supplied with a rubber-lining. In 1982 a second balling drum has been rubber- lined. At the same time the Tyler vibrating screen of this balling circuit has been replaced by a roller(bed)screen. By the end of 1983 all 7 balling circuits will be equipped with rubber-lined drums in combination with roller(bed)screens. The combination of these two modifications will improve the quality and the screen analysis of the green pellets, moreover resulting in savings on energy- and maintenance costs. This paper describes the influence of a rubber- lining on the balling process and the green pellet quality by carrying out in-plant testruns in November/December 1980. The testrun results have been compared with the results of a not modified balling drum.

Jan 1, 1983

By P. Songfack

In this work, the slurry flow in the ball mill is solved with Navier-Stokes' equations and the marker and cell technique (MAC), which tracks the fluid-free surface. Considering different planes in the radial and axial directions, this numerical approach leads to the direct calculation of the slurry velocity profile, mill holdup, and volumetric flow in the ball charge and pool. The MAC technique takes as input, the results of a direct three-dimensional simulation of the motion of grinding media, and in turn, provides a detailed knowledge of the hydrodynamics of slurry flow through the porous structure of ball load. This technique is a new approach to the mass transport problem that overcomes the limitations of indirect studies such as residence time analysis and holdup measurements.

Jan 1, 1994

By Gunter Fauth

The setting of tasks for the process control of coal cleaning, and in this connection the requirements for instrumentation can be classified into the following three fields: - Monitoring the operation of individual units, or process steps, - Control of units or process steps, - Control of the entire coal cleaning process with the intention of optimizing the operation and the profitability of the process. Instrumentation is affected by the type of cleaning processes. For introduction Figure 1 shows the simplified flow sheet of coal preparation which is usual in the German Ruhr District and in which desirable places for the measurement of ash, moisture and sulfur content are marked. The preparation plant is supplied with run-of-mine coal from the shaft via a homogenization facility. In a first step of primary classifying the raw feed coal is screened at about 10 mm. The raw coarse coal ( = 10 mm) is sorted by jig washers or heavy-medium separators. the raw fine coal (< 10 mm) at first is pneumatically sized at about 0.5 to 0.75 mm. The fines, the aspirated dust, are a finished partial product which will be added to the final metallurgical or steam coal. The material 10 to 0.75 mm subsequently is sorted in fine coal jigs and dewatered in centrifuges. The sludge obtained with the wet cleaning processes is dewatered in thickeners and fed to the flotation. Concentrate and tailings are dewatered by filters or bowl centrifuges and by chamber filter presses or belt filter presses, respectively. The partial products coarse coal, fine coal, flotation concentrate, aspirated dust, and middlings are blended to result in the sellable products metallurgical and steam coal.

Jan 1, 1984

By William P. Blacutt

This paper examines Bolivia&apos;s General Environmental Bill recently passed by Congress: a multi-purpose law with two primary objectives: a) the protection and conservation of the environment, and b) the promotion of sustainable development. In this law, environmental benefits are emphasized by stating general principles, not by attempting to define the means. Regulations are left to the writing of subsequent complementary codes. This paper shows that much of the controversy surrounding the legislation disappears when it is seen as guide rather than an operational part of Bolivia&apos;s industrial policy. In essence, the law addresses recent environmental awareness in a region more anxious than ever to speed economic growth.

Jan 1, 1992

By C. K. C. K. Gupta

The rare earths in elemental form are required for a variety of scientific and technological purposes. They are not easily obtained in this form, due to the great chemical stability of the rare-earth compounds and the strong tendency of elemental metals to react with everything they come in to contact with, especially at high temperatures. Beginning in the 1950s, when sufficient quantities of separated rare earths became available, as the result of intense research and development, three processing routes were developed to accomplish the preparation of all 16 naturally occurring rare-earth elements. They are chemical reduction of the halide intermediates, the oxides and electrochemical reduction of chlorides and oxide-fluoride mixtures. Not all the processes are effective with all the rare earths. In spite of the celebrated similarity of trivalent rare earths, the physical properties of individual rare-earth elements are sufficiently different that a variety of techniques are required for their preparation. The development of reduction processes for the rare-earth metals are covered in this paper, with focus on the oxide reduction routes. The strong reliance of effective reduction processes on the fundamental science of reduction reactions is highlighted.

By Richard H. Follis

Activated carbons used for precious metal recovery from carbon-in­pulp (CIP), carbon-In-leach (CIL) and carbon-in-column (CIC) circuits often become fouled with Inorganic precipitates (i.e., CaCOa, CaS04, SI02), and adsorbed organics (I.e., petroleum distillates from lubricants, dissolution products from wood) (1,2). These contaminants occlude carbon pore structure, such that diffusion controlled adsorption and desorption (elution) of Au(CN)2-and Ag(CN)2· are lmpeded(3,4l. Thus, after only short exposure to the hydrometallurgical environment, the characteristic carbon activity is reduced(5l. By frequently regenerating circuit carbons, activity losses associated with fouling can usually be minimized. Regeneration typically Involves (not necessarily Is this order): 1) elution to remove adsorbed ionic species (e.g., until they are removed from the carbon pore structure, Au(CN)2" and Ag(CN)2-are contaminants )(6l; 2) acid washing with 3-15% (wt/wt) hydro­chloric acid, to dissolve soluble Inorganic precipitates such as CaC03; 3) neutralization and/or water rinsing to remove residual acid; 4) thermal regeneration at 350-650 °C to remove adsorbed and/or pyrolyzed organ­ics; and 5) screening to remove fine carbon particles produced by Impaction and abrasion in the various stages of the hydrometallurgical circuit (i.e., adsorption, elution, and regeneration). The overall process Is purposed to reopen the circuit carbon pore structure, and to maintain the activity and qualities of virgin (new) carbon(7,8l. While most CIP, CIL and CIC operators regenerate circuit carbons, few evaluate the effect of the process on carbon quality in a systematic way. Process control usually Involves Iterating critical regeneration parameters such as: acid concentration; time frames for acid washing and water rinsing; and temperature and residence time for thermal regeneration. Carbon quality control frequently comprises only sporadic activity tests performed on non-representative grab samples dipped from conve­niently accessed carbon storage bins. So, regenerated carbon quality may vary and (at times) be unacceptable for effective hydrometallurglcal circuit operation. To verify the efficacy of the regeneration process and assure accept­able adsorption and elution rates for Au(CN)2· and Ag(CN)2·, operators should systematically assess regenerated circuit carbon quality. This paper, then, suggests methods for effectively assessing circuit carbon quality, Including: carbon sampling procedures; standardized physical and chemical test methods; and criteria and general procedures for comparative adsorption rate (activity) testing. Also, a two tier quality control testing scheme is proposed, and techniques for presenting and interpreting test data are demonstrated.

Jan 1, 1992

By F. F. Peng, Y. Xia

In modeling of hindered-settling bed separators, the published separation mechanisms are based on differences of particle density and size distributions, without the details of complexity of particles-liquid interactions. A fluid dynamic model for the separator is developed using Euler-Lagrange approach of Computational Fluid Dynamics (CFD). Fluid motion is obtained from solving the movement of liquid governing equations. The damping effect on flow pat-terns caused by the movement of particles resulted in liquid-particle coupling is included in the model. Effects of particle size, and particle density compositions, feed rate, feed water flow rate, upward fluidizing water flow rate, etc., are simulated in the 2-D separation model. Flow pattern effects on the separation of fine particles in the separators with center downward-flow and side cross-flow feed systems are investigated.

Jan 1, 2004

By Harry H. Posey, John Woodling, Miriam L. Renkin

Natural acid drainage is generated from pyritic rock underlying 17 percent of the upper Alamosa River basin. About one-third of these acid producing rocks have nil carbonate buffering capacity; there the streams carry significant acid plus dissolved Al, Cu, Fe, and Zn. In part of the basin, aquatic life is limited by the natural acid drainage. In the four miles where the Alamosa flows through pyritic rock the river grows toxic to trout. Inhospitable conditions continue downstream for at least another four miles. The waters become refreshed, naturally, through metal dilution, metal oxide and hydroxide precipitation, and acid neutralization. Water quality fluctuates in seasonal cycles. Dissolved metals and acid, which are generated year-round by weathering, are stored over winter in the unsaturated zone in the retained water and in soluble metal- sulfate minerals that form by evaporation of acid-metal waters. Seasonal discharge variations cause metal concentrations and pH to shift in the trunk stream; the acid drainage source streams, however, shift only slightly by season. In early spring, metal concentrations and metal loads increase as metals and acid are flushed from the unsaturated zones by melting snow. Peak metal loads occur at this time, and precede peak flow by up to two months. Other metal load peaks occur during peak flow and monsoon flow, even though metal concentrations are diluted at that time by precipitation. In late spring and thereafter, discharge of neutral pH water wanes, so trunk stream pH falls and metal concentrations return to previous high levels. Metal concentrations appear to be low from November through January when dilution from precipitation is lowest, but rise in February to near peak yearly concentrations. In years with high monsoonal flows, metal-laden waters apparently flush from the unsaturated zone and metal concentrations remain low from about October through January. In years with low monsoonal flows, however, metal concentrations in October and November at least are higher.

Jan 1, 2000

By M. Ribeiro, P. So, P. Wong

Electrowinning is a process by which metals, such as copper or nickel, are recovered from aqueous electrolyte solutions resulting from the extraction of the metal ion from an acidic or basic leach solution. The electrolyte or “pregnant” solution is customarily forwarded to an electrowinning "tankhouse." In the tankhouse, the metal ions are deposited on cathode plates by electrodeposition and then recovered from the cathode plates. Other processes may be employed with other metals, such as nickel, zinc, among others, to produce an electrolyte from which their respective metals are obtained. During the electrowinning (electrodeposition) stage, elemental metal is plated out at the electrowinning cathode and oxygen evolves at an insoluble anode. The evolution of oxygen gas forms bubbles which entrain strong acid electrolyte, carrying it into the air above the electrowinning tank in the form of a fine mist or spray when the bubbles break. An acidic mist is generated above the electrolyte. This mist or spray then spreads throughout the electrowinning tankhouse. The acidic mist is corrosive and a health hazard and can cause extreme discomfort to the skin, eyes, and respiratory systems of tankhouse workers, especially during hot weather conditions. Polyfluoroalkyl based products (PFAS) have been widely applied as anti-misting agents in the electrowinning of metals in an acidic electrolyte. Functionalized PFAS compounds, however, have come under increased scrutiny by the EPA due to their impact on human health and the environment. There remains need for improved acid mist suppression agents for electrolysis and electrodeposition, particularly for products free of fluoroalkyl components.

Feb 1, 2023

By Shosei Serata

In the past, salt cavities for storage of liquid and gaseous fuels have been developed and operated using practical experience as a guide rather than rock mechanics principles and practices. Although many salt cavities are still operating satisfactorily. some of them are beginning to show various problems associated with long-term deterioration of the cavities. This paper describes a major breakthrough in the rock mechanics design of solution cavities which is the development and application of the REM computer simulation system. From the computer simulation analysis, the long-term deterioration process of cavities can be related to the basic parameters of rock mechanics design and the storage operations. The computer simulation system is also used for optimizing cavity design and operational specifications. This optimization technique is explained by its application to the three basic storage systems: 1) open dry storage system for liquids and solids 2) open wet storage system for liquids 3) pressurized storage system for gases, liquids and solids The effectiveness of the optimization technique is illustrated with some field examples by showing the direct interaction between the computer simulation system and field data of a test well including tectonic stress conditions, material property coefficients and geological anomalies.

Jan 1, 1974

Dynamic permeability is a significant hydrologic condition associated with in-situ leaching at the Cyprus Casa Grande operations. Several factors contribute to changes in the permeability conditions. They are: 1) hydraulically induced fracture development, 2) geochemical changes during leaching in the rock matrix, and 3) changes in the relative degree of saturation of the deposit. Dynamic permeability conditions were evaluated using available pressure and flow rates from the 58 injection and recovery wells obtained over one year period. A finite element, 2-D hydrologic model called INVERT which is designed to estimate aquifer parameters under transient and steady state flow conditions was used for the investigation. The permeability conditions during 7 different steady state intervals throughout the one year time frame were determined. The results confirm that big changes in permeability occur as a function of time as well as a function of injection pressure condition.

Jan 1, 1991

By Mahmoud Sepehrmanesh, Verya Nasri, Maziar Partovi

"This paper presents an assessment of the impact of tunneling and its associated risks on pile foundations located in the influence zone of tunneling operation. Tunneling in proximity of pile foundations introduces deformations in piles and in turn induces additional axial and bending forces. In modern mechanized tunneling, ground convergence is controlled through balancing the earth pressure at the tunnel face as well as applying pressurized bentonite through the shield. Reducing ground deformation can consequently lower the additional deformations and forces developed in the pile foundation and lessen the associated construction risk. In this paper, comprehensive detailed finite element modeling was performed to quantify the effect of the different parameters on induced forces in piles. Finite element models took into account the nonlinear behavior of soil and pile-soil interface. The modeling results are of practical importance in risk evaluation of tunneling in vicinity of pile foundations. INTRODUCTION Tunneling operation in congested urban areas becomes more frequent as demand for further utilizing underground spaces grows. In urban settings, it is not uncommon for tunnel designers to plan a tunnel route in close proximity to other structures to satisfy other competing objectives like raising the alignment to reduce excavation volume. Setting the alignment close to existing structures increases the risk involved in the project. It is the responsibility of the designer to thoroughly identify, assess, and mitigate all design risks involved. In this paper, we focus on the aspects involved in tunnel construction in proximity to existing pile foundations. Tunnel operations introduce deformation in the soil mass. Consequently, a pile located within deformation zone experiences extra forces as a result of the imposed deformation. The developed forces and bending moments can be in orders comparable with the pile capacity depending on the relative horizontal proximity of the tunnel and the relative depth of tunnel with respect to the pile length."

Jan 1, 2016

By Friedrich Steinhäusler

RADON SOURCES AND CONTROL MEASURES IN THE MINING ENVIRONMENT Most of the contamination of the mine atmosphere by radon 222 is due to radon emanating from solid or fractured ore surfaces of walls, roof and floor. Also radon gas emanates from broken ore either from storage in backfilled mined-out areas as applied in e.g. shrinkage stopping methods or from ore spillage along intake airways mainly due to the use of trackless haulage. To a lesser extent water itself can represent an additional source of radon, which emanates into air from open drainage ditches or seepages along intake airways. The contribution from water can be controlled effectively by isolating the water from the primary intake air system, e.g. by diverting the water through pipes and/or sealing of seepages by grouting. However, control of radon emanating from rock surfaces creates a major technical problem with significant impact on the economic aspects of mining operations, if adequate radiological conditions must be maintained. Basically this can be achieved by suppressing the emanation process itself, confining already emanated radon or by removal of radon from the mine atmosphere. Extensive research has been carried out on the rate of radon emanation as a function of barometric pressure changes (Pohl-Rüling and Pohl, 1969). It could be shown that the radon supply consists of a permanent and variable component. The former results from the surface of the rock and depends mainly on the emanating fraction of its radium 226 content; the latter originates from within the rocks and is a function of the suction effect of decreasing barometric pressure, rock porosity and fissures. The practical application of this barometric pump effect for depressing the rate of radon emanation, e.g. by pressurizing the mine atmosphere, is limited due to high costs for providing a sink for absorption of radon and air as well as lack of permeability in most uranium ore bodies (Schroeder et al., 1966). Mine air cleaning by removal of radon can be achieved with the use of cryogenic methods, chemical removal, adsorption into charcoal beds, use of a gas centrifuge or general ventilation techniques. Technical problems have so far prevented the application of any of these methods other than ventilation. It is common practice to use the age-of-air concept, i.e. fresh air is delivered to the worker as directly as possible and removed quickly afterwards thereby maintaining the air "young". Engineering principles for quantity distribution of air through underground working areas are straightforward for general mining situations where radon constitutes an environmental contamination problem. However, in cases of high uranium ore content this concept may result in high costs with regard to installation and energy requirements for effecting both frequent air changes as well as sufficient heating of the air in cold seasons. Taking into account that the investment in ventilation systems is a major cofactor for the overall ore production costs this can be a limiting and decisive component in the assessment of the economic feasibility of specific mining operations and mineral reserves in general. Effective control of the radon flux from the rock surface prevents the initial contamination of the mine air with radon directly at the source. A radon diffusion barrier for practical application in mining requirements should fulfill the following requirements: - reduction of radon emanation rate by at least an order of magnitude - high mechanical strength - ease of sealant application onto surface to be coated - water resistant - low fire hazard - resistant to temperature changes encountered in mines - high cost efficiency in relation to exposure reduction achieved (direct and indirect costs) - low degree of maintenance. In the past several materials have been tested as sealants for controlling the emanation of radon from surfaces of rock and building materials. Epoxy paints reduce radon emanation rate only by a factor of 2 to 6 (Auxier et al., 1974; Eichholz et al., 1980; Keith Consulting Engineers, 1980). Although it is possible to prevent the escape of more than 99 % of the radon to the environment with gel seals over 80 mm thick (Bedrosian et al., 1974), practical applicability is very limited. Multilayer coatings of epoxy resins with various additives require meticulous preparation and flawless application of seamless four-layer coatings in four days to impede radon diffusion (Culot et al., 1976), otherwise results from this method have not been totally satisfactory (Leung, 1978). Aluminium foil laminated with polyethylene and paper on each side is under test as radon barrier but results are not available yet (Ericson, 1980). However, this method has the inherent disadvantage that possible malfunctioning electrical installations can cause fire or electrical shock through the sealant. Polyurethane foam coatings have been used on stoppings as very effective sealants. It does, however, represent a potential danger of spontaneous ignition and it is expensive (Rock, 1975). Thus, there is still need for a material which has similar properties as outlined above. In the following results are reported from investigations on the suitability of various materials as radon diffusion barriers.

Jan 1, 1981

By J. Brad Dalton, Sam Vance, Trude V. V. King, Roger N. Clark, Raymond F. Kokaly, Gregg A. Swayze, Dana J. Bove

Visible-wavelength and near-infrared multispectral image cubes for the Animas River Watershed from Hermosa, Colorado to the headwaters at Animas Forks, Colorado were acquired on June 18, 1996 using the Jet Propulsion Laboratory&apos;s AVIRIS (Airborne Visible and InfraRed Imaging Spectrometer) instrument (Green et al., 1998). These image cubes have been analyzed using the USGS Tetracorder V3.4 implementation (Clark et al., 1995), an expert system which utilizes a database of more than 300 laboratory spectra of endmember minerals and mineral mixtures to generate maps of mineralogy, vegetation coverage, and other material distributions. Major iron-bearing, clay, carbonate, and other minerals were identified along with several minerals associated with acid-generating hydrothermal systems including pyrite, jarosite, alunite and goethite. Additionally, distributions of alkaline minerals such as calcite and chlorite indicate a relation between acid- buffering assemblages and stream geochemistry within the watershed.

Jan 1, 2000

By Xu Xiaohe, Zhou Jiandong, Luo Shihui, Zhang Liqun

Recently, the research and applications of ES (Expert Systern) have been put forward actively in many mining fields in China. After various ES applications or instances are introduced, the paper has especially focused on the exclusive properties of a mining system different from any other system and the problems of the existing mining ES applications. And a synthesis methodology has been introduced in order to develop a applicable ES application

Jan 1, 1996

By R. Tanaskovic

Unfavourable climatic conditions in stopes are of significant economic and social importance due to the following reasons: - Working effect is much lower leading to decreased output and work productivity disregarding implementation of mechanization. - Manpower operating capability decreases much faster under unsatisfactory climatic conditions. Under normal climatic conditions a workman would expend much less effort in line with a shorter effective time for the achievement of identical production effects since the work would be more efficacious. The objective of study of problems and climatic conditions is to make the working environment in mines suitable for normal development of operations. Lowering of mining works to increasing depths and winning of a growing number of small orebodies over a broad area makes the problem of creating suitable climatic circumstances more complex. Mining costs are growing due to bench conditions in line with decreasing metal content in the ore, so frequently the investments required for creating favourable climatic conditions represent, in addition to the selection of mining technology, a very important parameter when making decisions regarding exploitation. As known, the basic factors affecting climatic operating conditions in mines-are: temperature, humidity and speed of air flow, implying that the climatic operating conditions are closely related to mine ventilation. Usually, the concept of unfavourable climatic operating conditions includes increased mine air temperature and humidity and low air flow velocity so that heat exchange between human organism and the working environment is impeded or reduced to minimum. Metal mines in Yugoslavia are characterized by the existence of a large number of active faces - stopes and horizons and lowering of mining operations to increasing depths, so that face ventilation solutions are more and more complex. Since its foundation (1961), our Institute is engaged in investigation of factors influencing climatic circumstances improvement of calculations for air distribution and distribution control in complex ventilation networks and study of problems related to ventilation of large volume and irregular configuration faces, as well as application of gained knowledge in our mines. The paper presents the knowledge and experience gained in the case of Lead and Zinc Mine "Trepca" - Stari Trg.

Jan 1, 1980