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By Charles F. Herbert

Placer mining in Alaska had a desultory inception at Sumdum in 1869 and, during the years 1880 to 1896, received thin nourishment from the readily exhausted gold placers at Juneau and the longer- lived deposits in the Circle, Fortymile, and Rampart Districts. Finally, in 1897, the great Klondike discovery in Canada's Yukon Territory brought thousands of gold seekers to the Far North. These men, in successive, far-reaching gold rushes, found the large, rich gold deposits at Nome, Fairbanks, and Iditarod, as well as many smaller placers. The hectic rushes during the years from 1898 to 19 10 were comprised of hundreds, sometimes thousands, of "stampeders," as they were called. Since very many Alaskan creeks, from the crest of the Brooks Range in the north to the Pacific Ocean in the south, carry at least a few flakes of gold, there was ample seed to start a new stampede. Of the 100s of reported "strikes," nearly 50 became more or less important placer mining districts; by 1910 they had produced about 184.2 fine Mg (6.5 million fine oz) of gold; the all- time peak production year was 1906. A few of the miners and prospectors prospered, but the total value of all gold produced failed, by a wide margin, to cover the aggregate costs incurred by them in the undeveloped Territory of Alaska. On the other hand, the traders with their readily salable supplies of food, tools, and hardware and the freighters with their teams of dogs or horses and boats of all kinds profited throughout the era of stampede.

Jan 1, 1991

By Jean-François Bougard

It has already been said and written many times that the construction of tunnels in urban areas has proved more and more indispensable, if not vital. The subsequent development of tunnelling for 15 or 20 years has brought large and sometimes spectacular improvements in the fiel of execution methods. But, particularly in urban areas, the difficulties to be overcome have been and still remain very important. As a matter of fact, most of big cities, have been settled near rivers or lakes; therefore the geological nature of the subsoil is soft ground and the level of ground water is high. As a consequence, tunnelling is often faced with many well-known difficulties and dangers issued from decompression or loosening of the ground, sometimes accompanied by a lowering of the water table. This may compromise the safety of the excavation itself and of the workers, and also cause settlements which many severely damage nearby buildings or structures. This is the reason why it is always necessary to work out specially adapted methods and even to develop new ones. In most cases, each work is a particular one and has to be specifically studied since numerous data are to be taken into account, related not only to geology, cohesion and behaviour of the different layers concerned, ground water, the activity of it, but also to

Jan 1, 1979

By Hal McVey

Introduction The role of marketing in the minerals and mining industry takes on different degrees of importance depending on the commodity, but nowhere are sales and marketing more important than in industrial minerals. This article compares industrial minerals marketing with the marketing of other mining and mineral products. Marketing in Mining Some broad generalizations on the marketing of industrial minerals in relation to other mineral products can be made without getting bogged down with exceptions to generalizations. Two totally different areas of mineral production are crude oil and natural gas, and metals, including ores and concentrates. Although these commodities are the basis for two completely different industries, they share two things in common from a marketing standpoint: • Their value per unit volume is usually high enough so that they can be transported great distances. • Their specifications are readily definable and, therefore, the quality of a standard product from a production run can be communicated by stating certain chemical and physical features. This permits sales to be consummated by telephone, telex, and letter, without the need to pretest the products under use conditions. In regard to the first item, industrial minerals, as opposed to oil, gas, and metals, are in most instances site specific. Location of the point of production in relation to the point of use is of paramount importance based on a generally lower unit to volume value. This means that transportation is a major factor, with the cost of getting the mineral to market commonly exceeding its f.o.b. value. Coal marketing has many characteristics in common with industrial minerals. Coal sales can es-

Jan 11, 1983

By P. Schiavi

A trend towards the independent verification of sustainable development reporting and assessment using third party certification can be discerned in the global minerals industry. Various codes that provide for the third party assessment and certification of performance against a range of externally developed sustainability indicators are being adopted by minerals companies, and there is also considerable activity in the broader area of third party assurance. Using a sociological approach, this paper examines the reasons why third party certification schemes are appearing in the minerals industry to address sustainable development imperatives in preference to other forms of regulation, and considers the broader implications of this trend. Data are drawn from a series of qualitative, in-depth interviews conducted with some of the key players in the development and adoption of certification schemes in the minerals industry, with executive managers of a range of large mining corporations, with representatives of global non-governmental organizations that are active in mining issues, and with government officers responsible for the regulation of mining corporations in Australia. Factors responsible for the emergence of the new certification schemes include: increasing demands from stakeholders for greater credibility in reporting against sustainable development indicators; broader contextual factors including globalization and neoliberal policies; and issues relating to trust and risk. Using insights from our research, and the work of others in this field, we identify some of the critical features of a credible third party certification scheme, and note some of the challenges for the design and implementation of such schemes. We conclude by discussing some of the broader implications of third party certification as an emerging form of regulation in the minerals industry.

Jan 1, 2007

By I. Edgar Odom

Hectorite is a rare magnesium-lithium clay mineral that occurs at many places in the McDermitt caldera of Nevada-Oregon. Commercial development of several high purity deposits began in 1986. The hectorite that was precipitated in a lake environment formed after the collapse of the McDermitt caldera. Hectorite beds and lenses are associated with volcanic sediments, limestones, dolomites, zeolites and locally sandy bentonites. The high purity deposits appear to be associated with hydrothermal areas. The hectorite consists of extremely small, flake-shaped crystals. Calcium (Ca) is the predominant exchangeable ion. Its color ranges from white to light green. Commercial uses include high-brightness, magnesium-aluminum-silicate (MAS) products, organophilic clays, pulp retention and ceramics. The MAS is used as a suspending agent, binder, stabilizer and thixotrope in aqueous solutions for cosmetics, household cleaners, pharmaceuticals and miscellaneous industrial applications. Hectorite-based organophilic clays are used in printing inks and paints. The McDermitt caldera complex is located astride the Nevada-Oregon boundary west of the town of McDermitt, NV (Fig. 1). The structural complex is elliptical in shape, extending about 43 km (27 miles) north-south and 34 km (21 miles) east-west. This area was the site of extensive volcanism during the Miocene (24 to 18 million years). The complex consists of five overlapping calderas with the oldest at the south end of the complex (Rytuba et al., 1979). Each of the vent areas collapsed and is marked by a ring fracture zone. The ring fractures around the outer boundary of the caldera complex are shown in [Fig.1].

Jan 1, 1992

By Levent Ozdemir

The advantages offered by mechanical mining have been demonstrated in the underground mining of coal, evaporites and other soft minerals. Mechanical mining and the advancements in automation technoloogies have been the principal drivers towards the realization of enhanced productivity in soft rock mining. For past two decades, emphasis has been placed on developing mechanical mining technology for hard rock applications, to achieve similar productivity improvements and cost reductions. The benefits of mechanical mining are numerous, particularly in an industry where market conditions continue to dictate higher production and lower costs while maintaining high safety standards. Other benefits of mechanical mining include reduced ground support and labor requirements and the elimination of blast and diesel fumes. These benefits further make this technology an attractive alternative to drill and blast for hard rock mining. Mechanical mining is conducive to full implementation of remote control and automation technologies that are under development to achieve further productivity and safety improvements in underground mining. Mine development has been the main focus area for mechanical miners by manufacturers and mining companies. Potential applications include ore body access, haulage and ventilation drifts, undercut and exploration drifts. The economic use of this technology in mine production is still considered many years away. It would need a major technological breakthrough that would make mechanical rock fragmentation competitive with the large-scale, low-cost production blasting operations.

Jan 1, 1998

By Richard V. Good, John B. Harvey, Lloyd S. Jones

INTRODUCTION The term "Rapid Underground Excavation" is generally associated with high speed tunnel advance with large volumes of excavation, and indeed this is the type of work for which most of the recent innovations in methods and new machinery have been developed. However, the term applies as well to any underground excavation process that results in an earlier project completion than would be expected with conventional methods, and hopefully with a decrease in total unit excavation cost. Often significant progress has been made during the primary stages of an underground construction project and then an inordinate amount of time and effort has been expended on small units of "miscellaneous" excavation which has delayed the overall project completion and escallated overall unit costs. Construction at the Nevada Test Site of the Atomic Energy Commission for underground testing frequently requires significant amounts of so called "miscellaneous mining" such as short access drifts, cross cuts, alcoves, niches and concrete keyways. Many of the keyways must be excavated without disturbing the rock beyond the excavation lines and construction scheduling often dictates that much of the work must be accomplished without disturbing sensitive electronic equipment already installed. In order to cut down on lengthy and costly delays required for the tedious manual excavation of much of this miscellaneous mining, a market search was made for suitable mechanical excavation equip-

Jan 1, 1997

By Patricio A. Espinoza, Aldo Casali, Cristian Ardiles, Guillermo González

Cluster analysis is used to design grade soft-sensors in a rougher flotation plant and a ball mill overload soft-sensor. Soft-sensors are virtual sensors which either replace unavailable actual sensors or infer measurements for non existing sensors. In the case of the grade soft-sensors clustering serves to determine clusters of related operating points. To each cluster there corresponds an ARMAX model structure whose parameters are estimated using only the points in the corresponding cluster. Thus a much better correlation is found than if all the data points were used for a global model. The problem of identifying clusters when the measurement of the real sensor is not available is addressed. In the case of the overload soft-sensor, variables were selected which are related to overload, either from a phenomenological point of view or according to operator experience. Different clusters are formed, some of which are identified as determining an overload condition or a possibility of such condition. Each of these clusters has a set of operating conditions which suggests the corrective action to be taken when necessary. Both kinds of soft-sensors are tested with industrial plant data and promising preliminary results are obtained.

Jan 1, 1995

By Frank H. Blair

A study of paleogeography and paleo-environment, coupled with modern geochemical techniques and geologic inference, points to the presence of unconventional platinum group metal deposits in domestic and foreign ultrabasic terranes. During the laterisation of the tectonized and serpentinized mafic and ultramafic rock units, onshore winds provided abundant low temperature chloride to the laterite-saprolite profile. Here, an environment formed where gold, silver and platinum was dissolved, transported and redeposited. Changes in climatic conditions have helped preserve the redeposited metals in fossil laterites. The definition of "unconventional mineral resources" used here is taken from the Cameron Volume of Unconventional Mineral Deposits published by SME-AIME in 1983: "Unconventional mineral resources represent materials of possible economic importance that occur in geological or physical environments that have not been successfully exploited for the particular mineral." (van Rensburg, 1983). Chromite-rich rocks worldwide contain high platinum group metal concentrations. This feature is found in ophiolitic sequences, Alaskan-type ultrabasic complexes or statiform intrusions. Association of platinum group metals with chromite has received much attention. The reason for that associa¬tion, however, is not clear. Much has been written about how and where the platinum group metals occur. It is known that they are present in the spinel lattice, as solid solution elements in sulfides and as discrete platinum group minerals. This article outlines the reasons geologists should be looking at lateritic terranes to determine the feasibility of searching for undiscovered, low-grade platinum group metals amenable to openpit, bulk mining. Laterite-saprolite horizons could contain significant platinum group metals and location of anomalous values on the surface and in the weathered profile can lead to discovery.

Jan 1, 1993

By J. D. Megeath

In the October 1988 issue of MINING ENGINEERING, J.G. Wargo's paper discusses the problem of measuring and analyzing permeability, porosity, and fracturing in its relation to in situ leaching of disseminated gold deposits. This paper made me suspect that a good deal of information and analysis may have been done on this in reverse in the petroleum industry. Some years ago, I was involved with the US Geological Survey in a project studying the Devonian shale of the eastern United States. The Devonian shale contains gas deposits that have the characteristic of slowly seeping gas over a very long time period. To understand the rate of seepage, considerable study and analysis was done on the interrelationship of porosity, permeability, and fracturing. The purpose was to find out how and why the gas could escape in the varying rates found in wells throughout the formation. It strikes me that this is the mirror image of the problem faced in attempting to understand how a cyanide solution will travel into a deposit. To possibly invent our own personal wheel a little faster, I would suggest a look at the work done on the Devonian shale. Some of it is contained in "Estimates of Unconventional Natural-Gas Resources of the Devonian Shale," US Geological Survey Open-file Report 82-474, 1982, and "Additional Data for the Estimates of Unconventional Natural-Gas Resources of the Devonian Shale," Open-file Report 83-676, 1983. It is entirely possible that some of this previous work could shorten the time required to make in situ leaching of disseminated gold deposits a profitable technique.

Jan 1, 1990

By Robert K. Towner, Francis S. Kendorski

Shotcrete drift linings at the Climax Mine of the Climax Molybdenum Company have undergone four years of extensive evaluations as a replacement for thick poured-in-place concrete linings. Any drift lining at Climax must be able to withstand the rigors of undercut and secondary blasting, weight problems induced by panel caving, and the abrasion of slusher mining. Examined here are the conclusions reached so far on shotcrete drift linings which have not yet completed the approximately six-year cycle from development to ore exhaustion. Properly applied shotcrete is an adequate drift lining for all phases of the Climax panel caving system of mining. Undercut blasting will damage shotcrete unless blasts are correctly timed. Weight problems will destroy shotcrete drift linings as efficiently as it will destroy concrete or steel support systems. Abrasion and secondary blasting results are inconclusive as the shotcrete lined slusher drifts have not entered the ore production stage of the mining cycle. In addition to drift linings, Climax has found shotcrete to be invaluable for lining large underground shops, for temporary support systems, for permanent ventilation bulkheads and for the repair of abraded or weight damage concrete lined slusher and haulage drifts.

Jan 1, 1974

By C. Abbruzzese, L. Piga, P. Fornari, S. Ubaldini, R. Massidda

The effects of certain variables on the extraction of gold by thioureation have been investigated on a quartzose gold-bearing ore using a statistical multifactorial strategy. The factors taken into consideration were milling time (which corresponds to a given grain size), oxidant concentration, thiourea concentration and liquid/solid ratio. The influence of these four variables was ascertained first by a full factorial design at two levels for each variable (16 runs). This permitted the estimation of first-order effects of the factors affecting the process. Then 9 runs were added whose levels were both in the centre of and outside the axes of the previous plan thus originating a central composite design. This permitted estimation both of second-order effects of the factors involved and of parameters of a second-order polynomial model. The results show that extraction of gold depends only on milling time and oxidant concentration, at least in the experimental range considered. The equation fitting experimental data, as calculated by the least squares method, allows a response surface to be drawn. Due to the low gold grade of the ore (6 ppm) statistical analysis could lead to contradictory results, hence strict observance of Gy's rules for sampling and very accurate and precise chemical analyses were required.

Jan 1, 1995

By Paul G. Schmidt

Exxon Minerals Co. was exploring for mineral deposits in Precambrian terranes of the US portion of the Lake Superior region in the late 1960s. Exploration drilling and other activities had been concentrated on massive sulfide prospects in northeastern Minnesota, but general exploration studies and competitor scouting were conducted in other areas of the region. These activities drew attention to Wisconsin in 1969 when it became apparent that Bear Creek Mining Co. had made a discovery near Ladysmith in the northwestern part of the state. Observation of their drill hole pattern suggested that a massive sulfide deposit, since named the Flambeau deposit (Schwenk, 1977), had been found. With this background, Exxon initiated an exploration program for Precambrian massive sulfide deposits in northern Wisconsin in 1970 (Figs. 1 and 2). Northern Wisconsin is extensively mantled by Pleistocene glacial drift and bedrock outcrop is sparse. Other than iron mines in the extensive iron formations along the Wisconsin-Michigan border and Jackson County, no significant mineral deposits were known in the Wisconsin portion of the Precambrian Shield until the discovery of the Flambeau deposit. Until the mid-1970s, the only specific published literature on the Wisconsin Precambrian consisted of old outcrop locations and descriptions in journals of the Wisconsin Geological and Natural History Survey (Chamberlain, 1882; [ ] Weidman, 1907; Hotchkiss, 1915) and the summary maps of Dutton and Bradley (1970).

Jan 1, 1991

By Donald D. Gullickson

The entire system is built around pre-designed and pre-engineered modules which are assembled to meet the metallurgical and production parameters of the project. The carbon vessels are the key to the flexibility of the system. The vessels are made of a coated mild steel, which allows the carbon vessels to be used in the adsorption, desorption and acid wash cycles. In the adsorption mode, the solution is pumped up-flow through four (4) vessels in series at 250 gpm fluidizing the carbon bed. When the carbon in the lead vessel is loaded, it is disconnected from the adsorption circuit via rubber hoses with quick-disconnect fittings. The second vessel is then made the lead vessel and a stripped carbon vessel is added to the end of the adsorption circuit.

Jan 1, 1998

By Frank E. Dalton, Forrest C. Neil

INTRODUCTION The Tunnel and Reservoir Plan (TARP) (Figure 1) was adopted in 1972 as the most cost-effective way to bring Chicago area waterways up to Federal and State water quality standards. TARP will significantly reduce pollution of these waterways and provide flood relief for Chicago and 53 adjacent suburban communities. These communities, covering an area of 971 sq km (375 sq miles), are at present served by combined sewers, which carry both raw sewage and stormwater. Because porous ground surfaces have been covered over in recent years by buildings, streets, and parking lots, stormwater runoff into sewers frequently exceeds the capacity of the sewers. When this happens, sewers back-up into hundreds of thousands of basements, and the overflows on the combined sewers discharge rainwater mixed with raw sewage directly into the area's waterways at 645 overflow points. The result is severe pollution of the waterways and flooding in 53 communities. During particularly heavy rains, overloaded rivers have to be relieved by opening the locks and allowing the polluted waterways to flow into Lake Michigan, the region's water source. Goals of TARP 1. PREVENT BACKFLOWS INTO LAKE MICHIGAN. 2. ELIMINATE WATERWAY POLLUTION CAUSED BY COMBINED SEWER OVERFLOWS. 3. PROVIDE AN OUTLET FOR FLOOD WATERS.

Jan 1, 1981

By Pramod C. Thakur

Tunnels are defined as underground passages made without removing the overlying materials. From time immemorial men have driven tunnels for mining purposes. Even today tunnels are the building blocks for underground mines. The total length of such a network of tunnels in a mine may add up to 10-100 miles! In addition to this, rapid development of vehicular traffic, needs for air raid protection and metropolitan traffic problems have given a great impetus to underground tunnel construction. But for the successful drivage of any tunnel an adequate air environment has always been and remains an essential prerequisite. This is particularly true for tunnels in mines which are driven in gas bearing strata often at a substantial depth from the surface. An adequate air environment is designed to promote the health, safety and comfort of workers which results in greater productivity and efficiency. Its legal definition varies from country to country but, in general, it means the provision of sufficient circulating air, often at specified velocities, to maintain: (i) at least 19% oxygen in the working areas (ii) Concentration of pollutants, e.g., methane, carbon monoxide, respirable dust, etc. below specified limits. Table 1 shows the maximum allowable concentrations for some of these pollutants.1 (iii) Temperature and relative humidity below specified limits. Ventilation of tunnels in mines assumes ever. greater importance today because of increased mechanization and concentration of output which leads to higher rate of production of inflammable gases and respirable dust. Efficient management of the tunnel air environment, however, depends heavily on a thorough knowledge of how

Jan 1, 1974

By Alberto S. Nieto

The general role of geology in the location of different types of large underground chambers is discussed. Aspects of structure, rock type and state of stress are discussed at some length. Some practical implications on stability of observations about the attitude, spacing and persistence of structural features are made. Characteristics and likely problems inherent to rock types (igneous, metamorphic, and sedimentary) are discussed. Observations regarding the uniformity of stress conditions within a physiographic province are presented. The influence of stresses parallel to the chamber axis on wedge movements is briefly discussed.

Jan 1, 1983

By Dalva L. Moellenberg

Introduction Hard rock mine closure (often referred to as decommissioning), mined land reclamation and financial assurance requirements are receiving considerable attention by governments and organizations around the world. In the United States, federal agencies and the states continue to consider and make changes to laws governing mine closure and mined land reclamation, most of which were originally enacted in the mid-1970’s through the mid-1990’s. Internationally, a number of prominent groups and various countries currently are considering new laws, regulations and policies for mined land reclamation. For example, the European Union has conducted a review of existing European laws concerning mining wastes and mine water and is considering new directives concerning mine waste and mine water management and liability schemes that are likely to significantly impact mine closure and mined land reclamation. Many countries, particularly those outside of North America, Europe, and Australia, have recently adopted or are considering new mine closure and reclamation legislation and regulations. These include significant hard-rock mining countries such as Chile, Peru and South Africa. This paper identifies recent developments in hard-rock mine closure and mined land reclamation laws in the United States, focusing on several of the more significant and controversial developments. It also discusses some of the more significant international efforts to consider mine closure and mined land reclamation laws and policies and some of the notable conclusions and trends from those efforts. The focal issues discussed in this paper include requirements for the reclamation of open pit mines, including backfilling; consideration of and measures to address the mining of sulfide ores and potential for acid mine drainage; and new requirements for the estimation of closure and reclamation costs and for financial assurance for closure and reclamation.

Jan 1, 2005

By Richard L. Daley

Today's subject of discussion, "OSHA AND ITS PROBLEMS", must be covered in the time allotted with a slight tongue in cheek approach, for if one is to believe that the "problems of OSHA" can be covered in a twenty minute review, he, himself, has one of three problems: 1. He has residual combat fatigue left over from World War II. 2. He is an egomaniac. 3. He is afflicted with both of the above. Clearly, the difference between divinity and humanity lies in their work. All human endeavor is plagued by errors and omissions, and unless one would be so facetious as to equate bureaucracy with godliness, our government-sponsored ventures seem to receive more than their share of missive missles with which to combat the ills of our society. Coming from an industry known for its undertaking of gargantuan projects, I feel capable of looking at things from the big picture perspective. No one would deny that the massive influx of government, both in the monetary and supportive personnel roles, has accomplished much. But only we, as tunnel constructors, have moved countless mountains of muck, placed endless yards of concrete and engaged the public on numerous fronts and in spite of all, at times have even made a profit! Profit! What a dirty word in our society today. It makes one shrink back from the filthy overtones dripping with the cloying scent of decay. Never shall we judge the success of our government programs with such a slimy yardstick as profit. No, for that which has been conceived in the bowers of Camelot, the measure must be more elevating and inspiring. Something to bring a proud bearing to our efforts! Nothing has helped to alleviate the suffering of man as much as medicine. The eradication of typhoid, polio, and

Jan 1, 1979

By Philip A. Mattson

INTRODUCTION Engineers involved with rock mechanics know the importance of discontinuities within a rock mass and their effect on its behavior when subjected to loads from structures or construction excavation activities. Various geophysical tools have been developed to provide comparative information on subsurface conditions, such as electrical resistivity, assorted seismic test methods, acoustic tests, etc. While these investigative means have proved invaluable in numerous situations, especially those where site alternatives are being evaluated, they shed little light on the difficult problem of quantifying the rock strength. For that purpose, a laboratory test program of samples obtained in the field is usually undertaken, often in conjunction with a variety of in-situ tests. While standard samples provide sufficient information on the rock properties, questions on the macro-structure of joints, faults, fissures, and their infillings often go unanswered. Presently, attempts are being made to incorporate into rock sampling technology new techniques which are directed towards providing better information on the incidense and orientation of discontinuities. One such device incorporates a scribe knife within the core barrel which scores the sample lengthwise as it is cored. The orientation of the scribe is known, thereby relating the bedding, planes, fractures, etc. to a spatial framework. A second approach, called the Integral Sampling Method, is the subject of this paper. Stated briefly, this method utilizes a grout injection to bond fractured rock to a steel reinforcing bar at the center of the coring. The bar is intended to act as a

Jan 1, 1979