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By Noel N. Moebs, John L. Ellenberger

Geologic structures in mine roof rock contribute to many roof falls in Appalachian coal mines. These structures include paleochannels, scours, pinch-outs, slickensides, clay veins, and cravasse splays consisting of thinly interlaminated sandstone and shale. These structures often can be identified during, and sometimes before, development and mine projections can be revised to reduce the adverse effects of discontinuities in roof structure. Large areas of roof consisting of laminated sandstones or incompetent strata generally can be delineated from exploratory drill-hole data and the need for supplementary support can be anticipated. Because an accurate description of roof geology also provides some indication of optimum length and type of roof bolts that should be installed, this Bureau of Mines paper describes the hazardous roof structures most commonly encountered in the Appalachian coal region.

Jan 1, 1982

By S. K. Kawatra

Various types of mathematical descriptions of the flotation process are used in the design of a full scale flotation circuit. Mechanistic descriptions developed under controlled laboratory conditions establish theoretical residence time requirements. Empirical models, describing flotation performance as a function of full scale operating variables, are established from one flotation system and applied to another hypothetical system. Problems of design by mechanistic modeling, such as scale up factors, can be alleviated if the model is developed from a full scale flotation circuit. However, the numerous uncontrollable variables encountered in a full scale operation would preclude the practical application of such a model. Incorporating empirical relations into the full scale mechanistic model will facilitate its effective use as a guide for flotation circuit design. A semi-empirical model has been developed that promises to offer a more effective means of flotation circuit design.

Jan 1, 1982

By Allan M. Johnson

Since 1974 researchers at Michigan Technological University have been studying mine subsidence in the Iron River District of Northern Michigan. The district, which was active from 1881-1978, has had numerous cases of subsidence. Much of the subsidence resulted from rock mass failure but some appeared to have developed primarily in the thick glacial overburden which is a typical feature of this area. This latter observation led to the recognition that some of the surface subsidence was due to piping; i .e., loss of overburden material to the mine voids by groundwater flow (Johnson and Frantti, 1978). The Sherwood Mine was the last mine to operate in the district. With its closedown scheduled for late summer of 1978, a unique opportunity to monitor the mine as it flooded was presented. It was reasoned that with the cessation of pumping, groundwater would rise in the overburden and the mine would flood. The physical characteristics of the mine were favorable for piping to occur as the mine flooded. With the permission of Inland Steel Mining Company and the support of the U. S. Bureau of Mines, a project to monitor the Sherwood Mine for piping subsidence began in June of 1978. This paper present aspects of this study pertinent to the piping-induced subsidence events which occurred at the Sherwood Mine in 1980 and 1981, including acoustic emission monitoring of the subsidence activity, hydrologic monitoring of the groundwater regime and the flooding mine, laboratory modeling of the piping mechanism, and analytic procedures which are under development.

Jan 1, 1982

By F. L. Wilke

In the german hard-coal mining industry the mechanization of longwall faces and the machinery used for the extraction process have reached such an extent, that an extensive increase in productivity and face performance is not likely to be expected. At present, the greatest amount of man-shifts is needed for operations such as tunneling, transportation and haulage (fig. 1.). The most restrictive parameter, especially considering the possible ad- [ ] vance rate of faces, is the comparatively low advance rate achieved in drifting operations. Therefore improvements in productivity and advance rates of drifting operations will have considerable influence onto the extraction rate of the faces. The importance of drifting operations - and especially the so-called "conventional drifting by drilling and blasting" within the scope of long- term planning strategy of the german hard-coal mining industry is reflected by the development factor. This factor is given by the ratio: cubic meters of rock excavated in drifting per 1.000 tons saleable coal produced. In 1973, which is considered to be the beginning of the oil-crisis, this factor was determined to be 17.7 m3/ 1.000 tons sale- able coal.

Jan 1, 1982

By Antonio Jorge de Sousa

In order to compare several mining variants, on the point of view of the variability of the ore quality parameters, a conditional simulation technique is applied to a complex pyrite deposit (FEITAIS orebody, Portugal). Exploitation methods such as cut and fill and sublevel stoping are studied by the a.m. methodology. For each mining variant, it is assessed the influence of several mining operators on the variability of grades.

Jan 1, 1982

By Peter J. Huck, Yoginder P. Chugh, M. Jennings

INTRODUCTION Large areas of the United States coal reserves have been undermined by room-and-pillar mining over the past century. These abandoned mines generally cause subsidence of the ground surface many decades after mining. Reports from England (1) where there is a longer history of room-and-pillar mining indicate that mines abandoned two centuries ago may still be causing subsidence, and causing surface destruction to urban areas or farm lands that have been developed in the interim. The devastation wrought by subsidence, both in terms of property loss and societal disruption is enormous. The authors discuss here the methods by which subsidence in abandoned mines may be controlled. Two distinctly different subsidence control technologies have been developed in the U.S. for abandoned coal mines. These are referred to as (1) Point Sup- port methods, and (2) Areal Backfilling. As the names imply, point support methods are used to protect individual structures, or even individual foundation elements of structures, whereas areas backfilling techniques may be applied to protect entire neighborhoods or urban districts hundreds of acres in extent. Both point support methods and areal backfilling have specific sub-categories of techniques that may be applied under different conditions as appropriate. POINT SUPPORT METHODS Point support methods are characteristically employed by civil engineers chartered with the design of a new structure or the protection of an existing structure. The subsidence control measures are only a part of a larger project, the safety of which must be assured to a degree of near certainty. The costs of point support methods involve a large number of bore-holes and the use of expensive materials in relatively small quantities. There exist several dozen point support methods, which operate either to support the underground cavities, controlling subsidence, or to isolate the structure from the effects of subsidence if it should occur. The latter methods usually involve deep foundations through the mine opening supporting the structure on the underlying strata. Our concern will be with the former method to support underground cavities to prevent subsidence. Gravel Columns and Associated Methods Gravel columns may be placed in the mine opening using the methods shown in [Figure 1]. Boreholes are drilled through the mine strata, and gravel poured down the borehole to form a pile on the mine floor. When the tip of the pile contacts the mine roof, it is rodded down to spread the pile, and permit additional gravel to be placed. The objective is to place as much gravel as possible in the mine opening, and to achieve firm contact with the mine roof. The gravel pile acts to reduce subsidence by three mechanisms. The filling of a significant fraction of the open mine volume reduces the amount of potential subsidence simply by killing open volume within the mine. In effect, the extraction ratio has been reduced by introducing the volume of gravel. The toe of the gravel pile abuts against nearby pillars, providing lateral support and protection against pillar deterioration. In effect, the height of the pillars has been slightly reduced by burying their lower portions. Finally, some direct support is provided to the roof strata, reducing the roof span and enhancing stability. The gravel column method may be used in a variety of applications, and with materials other than gravel. For example, gravel columns may be placed in a close line around the perimeter of the building to form a continuous gravel wall. The interior of the site may then be completely filled with sand, slurry or other material. Alternatively, a lean concrete may be used in place of gravel, so that the piles achieve significant structural capacity. The grout column, shown in [Figure 2], begins with the installation of a conventional gravel column which is placed around a grout pipe that extends through the borehole into the mine opening. When the gravel column is in place, portland cement grout is injected in stages. At each stage, sufficient grout is injected to fill the interstices in the gravel to build a column perhaps two meters in diameter and a meter tall. The group pipe is then raised one meter, and after the previously injected grout has set, the next stage of grout is injected. The process builds a column of grouted gravel to the

Jan 1, 1982

By Clayton J. Parr

Introduction This chapter contains brief discussions of various environmental protection requirements that relate to underground mining operations. Environmental disturbances at an underground mining operation can result from subsidence; water discharges; waste dumps; construction and operation of access roads and utility lines; construction and operation of surface facilities such as maintenance shops, bathhouses, and storage yards; and emanation of dust and noise from surface crushers. Construction and operation of a concentrator or washing plant may result in the emission of air pollutants, the discharge of water pollutants, the creation of noise, and disturbance of the surface. Tailings ponds can be the source of fugitive dust.1 This chapter is not intended to provide a detailed discussion and analysis of laws and regulations dealing with environmental protection. Rather, its purpose is to provide the engineer with a basic awareness of the existence and nature of such laws and regulations, as well as the procedural requirements that must be followed in complying with them. The body of law relating to environmental protection has grow" very rapidly and should continue to do to for some time. Because many of the laws have been enacted recently, numerous court decisions are being rendered to resolve disputes over their interpretation. Hence, the reader is cautioned to be alert for subsequent modifications of statutes and regulations, and new case law. Rules and regulations pertaining to environmental protection are implemented at all governmental levels. The most widely known laws are those enacted by the federal government that have nationwide applicability. However, separate requirements exist in each state, county, and municipality. Because of their general applicability, federal laws are discussed most extensively in this chapter. Ownership of the property is the most significant factor considered in ascertaining what rules govern the conduct of an operation thereon. If the land is held under lease, reference to the lease terms must be made in the first instance to determine what obligations must be met in order to prevent default and possible loss of the property. If the land is held under a lease from the federal government, the operator is subject not only to compliance with the lease terms, but also to a large body of laws and administrative regulations that pertain generally to the conduct of mining operations on land held under federal leases. Although operations on unpatented mining claims, the legal title to which remains in the federal government, are not subject to the same rules and regulations that are applicable to operations conducted pursuant to federal leases or permits, they soon will be governed by a special set of regulations that provide for protection of surface resource.2 Operations conducted on lands leased from a state usually are subject to numerous environmental protection requirements specified in the lease terms, in addition to rules and regulations promulgated by the state agency having jurisdiction over mining on state lands. Operations conducted on privately held lands are subject to fewer such requirements. Leases from private parties sometimes have environmental protection and reclamation requirements written into them, but generally to a far lesser extent than governmental leases. Operations conducted on properties owned by the operator are subject only to those laws and regulations that have general applicability without regard to land ownership. COAL SURFACE MINING CONTROL AND RECLAMATION ACT OF 1977 Introduction On Aug. 3, 1977, the Federal Surface Mining Control and Reclamation Act of 1977 was signed into law.3 It governs coal-mine operations on private lands, as well as on public lands. The Act is pervasive in its scope and is extremely long and complex. The basic purpose of the Act is to control and minimize the environmental effects of surface coal mining. Surface coal-mining operations are defined as activities conducted on the surface of lands in connection with a surface coal mine and surface impacts incident to an underground coal mine.4 The Act is administered by the Secretary of the Interior through a new agency named the Office of Surface Mining Reclamation and Enforcement.5 The Act contains detailed environmental protection standards and reclamation requirements, and it establishes a permit system for all surface coal-mining operations. Mining in certain areas and under ceri-in conditions is restricted or prohibited, and a mechanism for enforcement by the states is provided. Stiff penalties are provided in the event of noncompliance. Implementation Schedule Nonfederal Lands: As required by Section 501 of the Act, interim regulations setting mining and reclamation performance standards based on and incorporating standards set out in Section 502(c) were adopted effective Dec. 13, 1977.6 They will. be incorporated as amendments to Chapter VII of Title 30, Code of Federal Regulations. Permanent regulatory procedures for surface coal-mining and reclamation operations performance standards, which were directed to be promulgated by Aug. 3, 1978, were published in proposed form on Sept. 10, 1978. 7 They govern surface coal-mining operations in any state until a permanent state or federal program is adopted. As of Feb. 3, 1978, all new operations, and as of May 3, 1978, all existing surface coal-mining operations, on lands on which such operations are regulated by a

Jan 1, 1982

By Richard E. Gray

The Office of Surface Mining Reclamation and Enforcement (OSM) is preparing an Abandoned Mined Lands Reclamation Control Technology Hand- book. (l) GAI Consultants, Inc. , recently prepared Chapter 2 on Mine Subsidence Control which contains a summary of subsidence abatement measures plus two new decision matrices for evaluating the subsidence abatement options that might be considered for a particular problem. These decision matrices are presented for information. Review of the subsidence abatement methods resulted in identification of items where research may impact the current state of technology in mine subsidence control. These research needs are presented to stimulate discussion of their importance in subsidence abatement and to encourage funding agencies, researchers, and practitioners to work on them.

Jan 1, 1982

By Fred D. Wright

In this paper the principal theories used to design roof bolting systems are presented and discussed. Then the characteristics of various types of roof bolts are presented and finally the interaction between rock and roof bolt characteristics on choice of roof bolts is discussed. Theories can be considered design tools which may or may not be appropriate for a specific situation. It is good for a design engineer to have a number of such tools available and also important that he understand their good features as well as their limitations. Hence, some of the principal theories and classification systems used for design of roof bolting systems are discussed first.

Jan 1, 1982

By A. D. S. Gillies

Loss of visibility due to the occurrence of atmospheric fogging in underground mine airways can lead to a reduction in travel times and loss of production efficiency, an increase in the frequency of vehicular and foot traffic accidents and difficulty in checking rock surfaces for instability and loose material. Where hot and humid surface air meets colder underground air, conditions for fog formation nay be present. Further, suspended particulate matter from diesel exhausts or stoping operations together with slow movement of air along passageways nay contribute to formation. The study describes an investigation being undertaken with the cooperation of Kennecott's Ozark Lead Company to identify causes of the problem.

Jan 1, 1982

By John McMorran

An open pit mine design system should have the characteristics of being flexible, versatile, and simple. All of these characteristics are necessary for producing a dynamic mine design. In other words, a design that can be improved, updated, and implemented. Flexibility is an important characteristic due to changing times. For example, the effects of a changing economy, increased knowledge of the mineral deposit, or improvements in mining technology can result in a considerable, if not a complete change in the long range mining plans. Since the short range mining plans are based on the long range mining plans, they will-also be effected. Also, it is very important to validate the information used in the design or the design itself. This means the system should have the flexibility of being able, not only to detect, but to correct errors. Versatility is another important characteristic of a mine design system due to the wide range of situations that may appear. First, a design system must be able to handle both long and short term planning. This is necessary because of the variability in the definition of a time range. Second, a design system must be able to handle different types of deposits. Special emphasis must be placed on this issue, because many deposits, if not the majority, do not fit predefined categories such as bedded, massive, or roll-front, etc . . . Furthermore, the true test of the versatility of a design system is not only the ability to create an ultimate design but also to schedule sequences for this design. Thus, the versatility of being capable to design with a variety of time ranges, variety of deposit types, and scheduling are all important characteristics of the design system.

Jan 1, 1982

By Bernard L. Merlo

INTRODUCTION Modern mine management is constantly striving to develop improved mining methods which will not only increase productivity, but will also provide a safer work environment and make the most efficient use of our natural resources. Progress can be seen in this area by tracing mining methods through history. Work that was originally done with hand tools progressed with the age of mechanization to conventional mining, matured to continuous and longwall mining, and the advent of short¬wall mining, a combination of continuous and longwall, has recently been seen. This new method of shortwall mining provides a promising method for safe and ex¬pedient coal extraction. This study focuses upon the planning, design de¬velopment, and operation of the first producing short¬wall unit in the US which was operated in the Pittsburgh coal seam in northern West Virginia. MINE DESCRIPTION The mine is located in northern West Virginia at Grant Town in the heart of the high volatile Pittsburgh coal seam. Originally opened in 1901, the mine has be¬come one of the largest in the US, encompassing an area of approximately 103.6 sq km (40 sq miles). The seam being mined was the high volatile Pittsburgh seam which ranged in thickness from 1.8 to 2.96 m (6 to 91/2 ft). Three types of mining methods were employed: con¬tinuous mining, longwalling, and shortwalling, with each type accounting for 50%, 30%, and 20% of total pro¬duction, respectively. A total of 630 contract and super¬visory personnel were employed to produce the mine's designed annual tonnage of 1.8 Mt (2 million st). There were ten producing sections, eight continuous miners, one longwall, and one shortwall, operating a total of 22 unit shifts per day. Eight shafts, varying in depth from 80.2 to 194.2 m (263 to 637 ft) provided entrance to the Pittsburgh coal seam. These shafts were used for ventilation, portaling, coal hoisting, supply, and emergency escape hoisting. Ventilation was achieved by means of three exhaust fans which provided 707.9 m3/s (1.5 million cfm) of air to the mine and removed approximately 141 584 m3 (5 mil¬lion cu ft) of methane per 24 hr period. The room-and-pillar method was used for secondary recovery with designed barrier blocks between panels of 61 m (200 ft) in width. A double row of blocks was left around each gob area to provide efficient bleeder action

Jan 1, 1982

By Patzen Wu

Taiwan is located in the orogenic belt of island arcs on the western rim of the Pacific Ocean. The structure of the Taiwan coal fields is much complicated as a result of active Cenozoic orogenic disturbance in Plio-Pleistocene time. The abundant faults and folds have created poor structural conditions of the coal seams and some peculiar safety problems in mining however, the domestic coal still played an important role in the economic development of Taiwan for the years before 1968. Because of increasing mining depth and a decreasing number of miners, the coal production dropped from nearly 5.1 million metric tons in 1968 to 2.45 million metric tons in 1981. There were 173 small active coal mines and about 22 thousand miners in 1981. The coal mining in Taiwan has a history of more than one century. Specific efforts have been undertaken in solving major coal mine safety problems such as gas outbursts, bad roofs and weak floors, difficulty in ventilation due to deep underground mining, spontaneous combustion etc. We have thus acquired much helpful experience which, we deem, is worth reporting at this meaningful meeting.

Jan 1, 1982

By Kiran B. Chaudhuri

The Kivcet process is technologically the most advanced of the new lead smelting processes which have been developed over the past decade construction of the first commercial scale Kivcet lead smelter which has been designed by KHD Humboldt Wedag for Sociedad Complejo Metalurgico de Karachipampa is at present nearing completion in Bolivia. Some of the measures taken to minimise emission of harmful elements as well as methods employed to minimise energy consumption in the design of the smelter, are presented. Results of recent testwork which have added to the flexibility of the process are summarised.

Jan 1, 1982

By A. Maréchal

It has been shown since a few years that the problem of estimating recoverable reserves should be solved by using specialized statistical techniques : whenever the selected blocks are chosen without any other constraint than a cut-off grade criterion, the problem of estimating the corresponding tonnage-grade curve is resolved by estimating the local histogram of block grades. Two major statistical techniques are currently used by geostatisticians to estimate local histograms : the "average conditional distribution" technique (Parker, Journel, Dixon 1979) and the disjunctive kriging technique. (Matheron, 1976, Jackson, Maréchal, 1979). Both have proved to be applicable in practice, with their pros and conconcerning their practibility and versatility.

Jan 1, 1982

By K. H. Nimerick

Froth flotation of coal is growing in importance and complexity. Some of the reasons for these changes follow. 1) A need exists for energy resource conservation. 2) Preparation plants are processing widely varying coal -- deep seam, strip and stockpiled either separately or as blends. 3) More fines are being generated because more mines are using automatic mining equipment. 4) It is more practical and economical to remove ash and sulfur at the preparation plant than during utilization.

Jan 1, 1982

By Mark Gershon

This paper describes a linear programming (LP) application that schedules mining operations in an optimal manner. The model is developed such that it can be applied to a broad spectrum of mining activities. While linear programming has been applied to mine scheduling in the past, the models have been either site-specific or they have only optimized one aspect of mine operations without regard to others. The Mine Scheduling Optimization (MSO) concept makes use of a mathematical model to: (1) Determine the optimal operation of a mine, from mine to plant to market. (2) Account for mine-plant-market interfaces. (3) Optimize operations over the life of the mine. (4) Accomplish long, intermediate, and short range planning.

Jan 1, 1982

By Karl A. Olsson

The Glenharold Mine is a surface mine operated by Consolidation Coal Company. The mine is located approximately 90 kilometers (55 miles) northwest of Bismarck, and 3 kilometers (2 miles) southeast of Stanton in west central North Dakota. Glenharold has a nominal design capacity of 3.0 million metric tons per year (3.3 million short tons per year). With the exception of local coal sales, this production supplies fuel for Basin Electric's Leland Olds generating station, a mine mouth power plant. The mine has 175 hourly and 50 salary employees. The Glenharold reserve extends over 210 square kilometers (80 square miles). The mining area is on a dissected plateau between the broad flat Missouri River flood plain to the north and the gently rolling uplands to the south. Erosion by intermittently flowing streams has produced many narrow, steep-walled, drainage ways. Mining begins at the 6 meter (20 foot) cover line and continues to the economic recovery line.

Jan 1, 1982

By C. B. Henderson

The development of slurries of coal and water as a boiler fuel replacing No. 6 fuel oil has been actively pursued at the Atlantic Research Corporation since 1976. Funding for this effort has been provided by the U.S. Department of Energy, the Electric Power Research Institute, and by corporate funds. The name ARC-COALTM has been selected for these slurries. Stable coal-water slurries with bone-dry coal loadings between 62% and 77% have been prepared, evaluated rheologically, and successfully burned in an experimental furnace without the assistance of other fuels. The advantages and properties of these slurries, including combustion results, are reviewed. Also discussed is the pilot line used for processing barrel quantities of fuel and a pilot plant capable of processing 600 bbl/day, currently being designed.

Jan 1, 1982

By Bruce Kennedy, Charles Bruce

MINERAL EXPLORATION 'The Function of Exploration Mineral exploration aims at locating the presence of economic deposits and establishing their nature, shape, and grade. As all ore bodies are finite, exploration is essentially the lifeblood of the mining industry. It is divided into two phases, reconnaissance and target investigation. It involves geological mapping, geophysical prospecting (aerial and ground or both), geochemical surveys, prospect drilling, and/or exploratory under-ground workings. Successful exploration is followed by development drilling, mine development, and eventually operation. In underground mining, the term "ore" is applied rather loosely to metalliferous rock that can be profit- ably mined, but nonmetallic industrial minerals and energy related materials constitute a large and growing portion of the tonnage extracted by underground methods each year. It is appropriate, therefore, to consider exploration as the search for any useful substance occurring in the earth or in the oceans that is of sufficient value as to volume, grade, chemical and physical com- position, and location as to make extraction by mining commercially profitable for the investment required. The Selection Process The search for ore includes hundreds of mineral commodities. The more successful exploration organizations tend to restrict the search to the mineral commodities for which they have strong exploration expertise and which have a high probability of being concentrated in areas open to exploration and development in sufficient volume, grade, and proximity to the surface to warrant the large expenditures of risk capital in finding an ore body. Special expertise is needed to engage in mineral exploration and development for the extended periods required for success. Individual prospectors continue to discover mineral occurrences, but it generally takes an organization with strong financial resources to carry the exploration process forward to the point of developing "ore." Still greater corporate resources in the form of management, engineering, and sales capability are needed to develop an ore body into an operating mine. In the past, companies other than those engaged in mining rarely conducted exploration, since they lacked the technical skills and know-how to bring a mine to fruition. A notable trend in recent years has been the success of other resource-oriented firms, such as petroleum companies, that have not only acquired the necessary skills to engage in exploration for hard minerals, but are doing so on a far more intensive scale than known in the industry heretofore. The desire to diversify from increasingly regulated oil and gas, the potential for the discovery of a bonanza, and the large scale of mining projects for these capital-intensive firms are the attractions. US government and certain international organizations, such as the United Nations, have fielded sizable exploration programs in the past decade on behalf of Third World countries wherein many of the world's higher grade deposits and scarce mineral resources are located. The level of overall mineral exploration in the industry is, regrettably, closely geared to the business cycle. Accelerated search during the periods of strong demand, shortages, and high prices, together with the long lead times necessary to develop mineral finds, often creates surges in supply which invariably are followed by a collapse in prices. The trend is, therefore, to exploration funding by larger better-endowed firms having the staying power to weather the cyclical nature of mining. Tax incentives, tariff policies, and other incentives have a decided impact on the level and nature of exploration. Surface mining regulations and environmental forces have fostered a renewed interest in under- ground development despite the lower average costs of surface mining. Spiraling inflation has caused mining costs to outpace prices for many mineral substances. Organizations increasingly are directing their search away from high- grade but limited tonnage occurrences toward low-grade disseminated bulk tonnages amenable to mining on a vast scale. Mining continues, therefore, to grow even more capital-intensive with half-billion-dollar mine-mill- smelter complexes now commonplace, compared with the hundred-million-dollar projects of a decade ago. Reconnaissance Exploration Having elected to search for specific mineral commodities, the exploration company narrows its focus to a reconnaissance of those regions offering the best potential. A working hypothesis which is constantly up- dated concerning the geologic controls for ore occurrence guides the search. The possibilities for discovery are best in areas of existing mines and known ore bodies, where the probabilities are high for additional ore occurrences. In such areas, published data on the trends and geologic controls of known mineral occurrences aid the search. Even in some remote territories, a variety of geologic data is available to the explorationist. The major sources of basic geologic data are the libraries of the US Geological Survey (USGS), the state geological surveys, the American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME), the US Bureau of Mines, and various institutions such as Colorado School of Mines. Overseas, virtually all of the countries have their own geologic survey groups which are associated directly, or indirectly, with their respective ministries of mines. The objective of reconnaissance exploration is to narrow the search by pinpointing target areas having interesting mineralization. These favorable areas are then investigated in detail to delineate potential ore bodies.

Jan 1, 1982