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By Allan D. Fernie

Growing interest in pit crushing and conveying is evident from the many articles, technical papers, and new equipment development recently presented. Application of a pit crushing and conveying system is complex, as many factors such as mine design, production scheduling as well as initial and ongoing capital and operating costs must be thoroughly and realistically examined. This paper will address the fundamentals to be considered and review several approaches to developing a total system for a new and existing mine situation. The planning function will be outlined and operating and design criteria defined to interface the mining operation and the pit crushing conveying system.

Jan 1, 1983

By O. D. Christensen

The Carlin Trend is a 60 km (38 mi) long northwest alignment of epithermal, sediment-hosted, disseminated gold deposits. Collectively, these orebodies contained more than 620 t (20 million troy ounces) of gold. The Carlin deposit, located near the center of the Trend, has become the "type" deposit of this class. There are, however, significant differences between the individual deposits. Six subdistricts can be distinguished, based upon geographic, structural, lithologic, alteration, mineralization style, and geochemical characteristics. They are, from northwest to southeast, the Bootstrap, Bluestar-Goldstrike, Lynn, Maggie Creek, Rain and Bullion (Railroad) subdistricts. Regional Geologic Setting The Carlin District is located centrally within the Great Basin Geologic Province. Host rocks for the deposits include sedimentary units that range in age from Ordovician to Mississippian, as well as a Jurassic-Cretaceous granodiorite stock. During the Early Paleozoic, the area that is now Nevada lay along the western margin of the North American continent. A westward-thickening wedge of sedimentary units was deposited offshore in a eugeoclinal basin; these vary from continental shelf carbonates toward the east to fine-grained siliceous clastic and cherty units to the west. Tectonic activity associated with the Antler Orogeny in Late Devonian to Early Mississippian time resulted in the eugeoclinal Western Assemblage rocks being thrust as much as 140 km (90 mi) eastward over time-equivalent transitional to miogeoclinal Eastern Assemblage rocks along the Roberts Mountains Thrust fault system. The leading edge of the Roberts Mountains Thrust plate formed the emergent Antler highland from which siliceous clastic sediment, eroded from the overriding eugeoclinal rocks, was shed eastward into the adjacent foreland basin. Erosional products derived from the overthrust plate are termed the Overlap Assemblage.

Jan 1, 1987

By J. M. Avasthi

Gulf Research & Development Company conducted the nation's first underground coal gasification test in steeply dipping beds near Rawlins, Wyoming. The geotechnical considerations played a major role in the initial site selection. The test plan included a detailed geotechnical program for site evaluation, test design, permitting, and environmental studies before the burn. During burn, the geotechnical activity continued in the form of monitoring surface subsidence and acoustic emission. The postburn evaluation included studies of the drill cores obtained from the burn zone and effects on the surrounding rock mass.

Jan 1, 1981

By G. R. O?Neil

The justification for a "ligand- selective' approach to fine mineral beneficiation via flocculation is established initially. Special emphasis is placed upon the need to identify non-selective, interfering and complicating adsorption effects. Specific strategies directed towards the design and synthesis of complementary selective flocculants are detailed using a number of different polymers and chelating agents as examples. In this regard, the affinity of polymer-bound ligands for metallic cations, ligand concentration, possible modes of attachment, the application of spaced-out ligands and other considerations in the preparation of selective flocculants are highlighted.

Jan 1, 1983

By Charles S. Robinson

The Henderson ore body is east of the Continental Divide in the Front Range of the Colorado Rocky Mountains about 50 miles west of Denver. The ore body is being developed for mining by workings that extend more than 3500 feet below the topographic surface. During construction of the mine workings, ground water in fractures in crystalline rocks has been encountered. From 1969 to 1973, Charles S. Robinson & Associates, Inc., in cooperation with the engineering and geologic staffs of the Climax Molybdenum Company, a division of Amax Inc., studied the ground water geology of the Henderson mine development area. Detailed geologic records of the Henderson mine were available as a result of the exploration, evaluation and development of the mine. Records of the flow, chemical composition and temperature of the ground water at and near the surface, from the entire mine, from portions of the mine, and from exploration holes drilled in the mine, were kept as the mine was developed. Where possible, ground water pressures in drill holes and changes in pressure with time, were recorded. The geologic, hydrologic and chemical data were correlated. The following conclusions were drawn from the correlations: The ground water in the Henderson mine occurs in fractures in Precambrian igneous and metasedimentary rocks and in a series of Tertiary intrusive rocks. Two zones of ground water were recognized; an active zone, in which the fracture systems are recharged and discharged annually into the surface water system, and a passive zone, in which the fractures were filled with water in the geologic past. Discharge from the passive zone is through mine workings that intersect the fracture systems. Discharge from a fracture or fracture system is initially high but decreased with tire!. The rate of decrease in flow (or pressure) is exponential. By measuring the change in flow with time, it is possible to calculate the amount of flow at some given period of time in the future. Based on changes in rate of flow and pressure, and the geology, and assuming rates of mining of the ore, it will be possible to predict the volumes of water that will have to be handled during the life of the mine and the area around the mine that will be drained by the mining operation.

Jan 1, 1976

By Argenis Gamboa

The Arab community is formed by around twenty countries in Africa and Asia, linked basically by a common language-Arabic - and the same religion, the muslim. They jointly occupy around 12 million square kilometers with a total population of around 140 million people. Nevertheless, these nations differ widely in their geographic area and population. Thus, while Egypt has a territory of over a million square kilometers and a population of nearly 40 million people, Kuwait, Qatar and Bahrain have, among the three of them, less than 30, 000 square kilometers and a million inhabitants. The per capita income also vary greatly, depending on whether they are oil producing countries or not. Generally speaking, it can be said that these countries economies have been based on oil or agriculture and that in these last years, they have been making serious efforts to increase their degree of industrialization and have greatly improved their infrastructure. This trend has resulted in the development of the iron and steel industry, which is still in a stage of primary development.

Jan 1, 1979

By A. Wallace Mitchell

Barite deposits in Nevada occur as bedded and vein-types along a north-northeastern -trending zone which parallels the Antler orogenic belt The bedded deposits of Nevada are the most significant economically. They are presently supplying eighty-five percent of the domestic barite production which is used primarily as a weighting agent in the petroleum drilling industry. The ore bodies are controlled both structurally and stratigraphically, occurring along regional and local structural breaks in siliceous eugeosynclinal rocks of mid-Paleozoic age. Evidence for origin of the barite includes sedimentary and hydrothermal features indicating that localization probably took place along fractures in the seafloor.

Jan 1, 1980

By J. D. Miller

Pilot-scale tests indicate that effec¬tive concentration of fine gold from Colorado River sands can be achieved by flotation with the air-sparged hydrocyclone. The fine sands (55% minus 400 mesh and 0.01 opt*) from gravity concen¬tration were processed with a 5-cm air-sparged hydrocyclone (capacity -1.0 tph dry solids). Concentrate grades as high as 5.0 opt were produced in a single stage at a recovery of 75.0%. The separation efficiency was significantly better than that achieved in conventional batch flotation experiments.

Jan 1, 1985

By Allister McLeod

Coal is expected to play a major role in energy supply in the next 20 years. Oil is a convenient and still reasonably abundant fuel. However, its major sources of supply are regions where there is nervousness about political stability. Uranium is a more efficient fuel - but there is a continuing community apprehension regarding its use. What coal may lack in efficiency, it makes up in long term availability and competitive overall cost. Moreover, diversity of source ensures stable long-term supply. In this way, a major role for coal in the world energy scene is assured. Cyclical considerations aside, demand for coal will increase significantly and it will meet a substantial share of new energy demand, replacing oil and gas in major industrial and electric utility markets. By around the year 2000, coal's share of world energy could reach 30% and rival oil as the largest single source of energy.

Jan 1, 1982

By Merih Celasun

The literature in operations research centered on mineral exploration has been comparatively limited in view of the significant implications of mineral discoveries upon the national economies in general and mineral industries in particular. Much of what has been published is of somewhat unsure academic nature, indicating to a certain extent the scarcity of industrial applications. Mineral exploration activities present quite difficult operational and conceptual problems. The purpose of this paper is to discuss the principal characteristics of decision problems encountered in planning an exploration program, to indicate an optimization approach to a certain class of allocation problems, and to suggest directions for future research effort.

Jan 1, 1962

By J. D. Carson

A 0.60 km2 (150 acre) wetland was reclaimed by Agrico Mining Company as part of a 1.48 km2 (366 acre) reclamation program in southwest Polk County, Florida approved by the Florida Department of Natural Resources. The upland portion of the area provides watershed for the wetland site which overflows into the flood plain of Payne Creek. Construction of the wetland was designed to provide conditions favorable for a diversity of habitats, as well as retention time for surface runoff waters. A variety of revegetation methods, including innoculation with muck from unmined wetland depressions, have produced encouraging results with both woody and herbaceous species.

Jan 1, 1983

By Charles Bruce

Although much has been said about the high cost of exploration, both at home and overseas, little of a specific nature has been published on actual finding costs, if indeed such data has been developed. This contrasts sharply with our sister industry, petroleum, where finding costs for oil and gas are available for virtually any country In the world. The reason is largely attributable to the genetic complexity of the hard minerals, as opposed to petroleum, and the increasing difficulties we are facing in the search for new orebodies. We have available to us data on the annual exploration budgets of most of the major mining companies which show them to run into the tens of millions of dollars. My co-panelist, Dr. Walthier, Director - Corporation Exploration, St. Joe Minerals Corporation, New York, NY, summed up the feelings of many explorationists in a recent keynote address when he stated, "I would not recommend a mineral exploration program of a general nature in North America budgeted at less than three to four million dollars annually, spread over four to five years -- or smaller amounts for more years". We have the fact that many of the major companies now prefer to "buy into" a new mineral discovery, particularly overseas, because of the high-risk and high-cost of exploration. Is there, then, a place for the small investor, let us say with a budget of under $200,000 per year and, if so, where and how? This paper is directed toward the above question and is based on experience gained while managing a limited international exploration program, on a shoestring, over the past three years.

Jan 1, 1976

By Bryson D. Trexler

Man's activity in developing, operating, and abandoning a mine often affects the quality of the ground water and surface water. Acid water drainage from mines is an example of an impact from mining that results in degradation of ground and surface water. New flow systems are created by the mining activity. The mining made possible complex chemical reactions that, with water movement, create a discharge of low pH, poor quality water. Remedies for these problems fall into two general solutions: 1) treatment of the end product and 2) reversal of some aspect of man's disturbance of the natural system. The relative reversibility of various aspects of man's impact from mining activities ranges from relatively easy to very difficult, from economically feasible to economically infeasible, and from technically possible to essentially impossible with present knowledge. The relative reversibility of a mine-related problem cannot be assessed without first understanding the detailed physical interactions that combine to form the problem. Acid water drainage is a combination of the availability of several chemical factors with the availability of water for a transport mechanism.

Jan 1, 1982

By James H. Vignos

An optical instrument designed for the on-line measurement of the size distribution of coarse particles (3-500 mm) being transported on a conveyor belt is described. Included is a discussion of the measurement technique, as well as test data verifying the legitimacy of the basic sensing approach. Field data indicating the instrument's ability to make useful measurements in an industrial environment are also presented. Applications in the mining and mineral industry, for which this instrument was orginally developed, are outlined, with particular emphasis given to the areas of crushing and grinding control.

Jan 1, 1979

By W. Irwin

As a consequence of the oil crisis of the 70?s, the commercial value of coal increased very sharply and an upward trend in coal prices although now less pronounced, continues today. The graph shown in figure 1 illustrates the trend in the F.O.B. price of U.S. metallurgical coal. This trend occurs during a time when mechanized mining is firmly established as a means of production throughout the coal mining world. With modem methods of mining, mechanical cleaning is a necessity and quality control is no longer entirely dependant upon coal face practice. The efficiency of fine coal recovery is of vital economic importance to present day operations and good practice in this field contributes significantly to improving profitability. Numerous processes are available for the duty and this paper discusses one such system, namely the practice of froth flotation.

Jan 1, 1980

By K. K. Wu

In some cases, coal barrier pillars must be relied on to withstand high hydrostatic pressures in order to prevent inundation of active mine workings. Such barriers are particularly important in areas, such as parts of West Virginia, where much of the future mining is down dip of mines which have been abandoned, or are currently being worked. Also, where multiple seam mining is conducted, a barrier pillar in one mine may be critical to safety in a mine in a lower seam. MSHA's Coal Mine Safety and Health district offices and the Mine Waste and Geotechnical Engineering Branch of the Pittsburgh Technical Support Center, have recently been involved in the study of barrier pillars in Kentucky, Virginia, West Virginia, Ohio and Oklahoma. In this paper, the factors involved in determining the required width of pillar are discussed, past practices for sizing barriers are reviewed, and related current Federal regulations are examined. In addition, the results of laboratory testing of bottom rock are presented.

Jan 1, 1980

By James A. Martin

Evaluation and subsequent development of a quarry in east-central Missouri was based on a general but brief examination of outcrops and core from five (5) test holes. Neither core, outcrops, nor existing quarries in the general area gave any indication of potential major problems. In the third year of operation large areas of collapse rubble, consisting of green shale and large blocks of limestone and sandstone, were encountered. Their size and random distribution resulted in both blasting and quality control problems. By the fourth year of operation, production costs became prohibitive and the site was abandoned. Prior to dismantling the plant a geologic investigation, which included shallow seismic and resistivity surveys, was made of the unmined portion of the lease. The collapse dolines appear to be related to structure and predate development of the modern topography. Surface indications of these features are few. The seismic profiles were especially helpful in plotting their distribution. Geologic relationships and seismic data developed at this site are being related to similar suspect areas in Missouri and have been useful in their evaluation.

Jan 1, 1970

By Lawrence D. Ramspott

A test of retrievable geologic storage of spent fuel assemblies from an operating commercial nuclear reactor is underway at the Nevada Test Site (NTS) of the U.S. Department of Energy his generic test is located 420 m below the surface in the Climax granitic stock. Eleven canisters of spent fuel approximately 2.5 years out of reactor core (about 1.6 kW/canister thermal output) were emplaced in a storage drift along with 6 electrical simulator canisters. Two adjacent drifts contain electrical heaters, which are operated to simulate within the test array the thermal field of a large repository. Fuel was loaded during April-May 1980 and initial results of the test will be presented.

Jan 1, 1981

By L. A. Bellows

The "Athabasca oil sands" of the McMurray formation in northeastern Alberta cover an area of about 21,000 square miles and contain the world's largest reserve of oil. Fort McMurray, a small town in the heart of the oil sands area, is about 235 air miles north- east of Edmonton. A railway serves the town but no year-round roads connect the town with the rest of Alberta. (Figure 1). The McMurray formation is of early Cretaceous age, deposited unconformably on a limestone surface of Devonian age. The sediments appear to have originated from the Canadian Shield to the east and were deposited in bays and deltas of large fresh water lakes. The lakes were later replaced by marine seas in which t the overlying Clearwater shale was deposited. (Figure 2).

Jan 1, 1963

By A. A. Davis

The decade of the 70?s saw a series of landmark environmental resource programs enacted by the Congress. Many states followed suit, so that by the end of the decade air quality, water pollution, and the conservation of other natural resources, including minerals, were the subject of a wide-ranging body of laws, policies, regulations, and procedures. Many of the actions required or permitted by this rule-making involved areas for which adequate information and substantial experience were not available. Moreover, goals and objectives were sometimes established which were enormously difficult to achieve technically, or of such formidable expense as to cause concern about their consequences in the marketplace. It is therefore hardly surprising that one product of all this activity has been a mass of litigation. Court dockets are crowded with suits and counter-suits involving both substantive and procedural aspects of environmental protection. Indeed, it is probably fair to say that the volume and range of environmentally-related disputes brought before the courts parallels that generated by the civil rights movement a decade ago. There were also some new dimensions to the environmental movement. For the first time, the national environmental policy act required agencies to prepare environmental impact statements when proposed projects or activities would have substantial impacts on environmental resources. Another requirement of many of the new programs mandated meaningful citizen participation in public decision-making. Here, as elsewhere, the purpose was admirable, but guidelines were vague, and the result often was inaction, polarization, and litigation.

Jan 1, 1986