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By Thorvald Wetlesen

Computer controlled drilling is now proven technology. It was first introduced by the development of the Furuholmen system for a prototype three boom tunneling jumbo in Norway in 1978. Now, 13 rigs with this concept are in operation in Europe, 3. in mining in England and. 10 in tunneling elsewhere in Europe. The system is also adapted to roadheader guidance. Practical experience has shown that the computer control system makes it possible to drive tunnels with a more accurate contour thus reducing the total amount of rock excavated, and where a full concrete lining is required a reduction in concrete volume is achieved. The total tunneling economy is improved. In the future we expect to see a wider range of instrumentation on jumbos, from the simple direction instruments to computer guidance systems for monitoring only, as well as fully automatic drilling to a programmed drilling pattern. More compact and reliable electronics will be available. Systems with low power consumption will fit easily into flameproof applications. Cabling complexity will be reduced by connection of sensors to serial signal lines.

Jan 1, 1989

By Robert D. Brown

The purpose of this paper is to tell a story - and it is a story with a moral. My topic is Present Trends in the Tax Environment Affecting Mineral Development in Canada, and the first thing to recognize is that, with depressed metal prices and weakening western economies, taxes, in and of themselves, are not really the cause of the Canadian mining industry's present doldrums. But the character and level of mining taxes in Canada has had a profound influence on the development of the industry over the past decade, and the expectations of what taxes the industry will face in future years will influence the industry's further growth. My theme today is that, in Canada, our tax system has, in the past, served as a negative and destabilizing influence in the mining industry: it has contributed to a major short-fall in investment commitments and hence in the contribution which the mining industry can make to the Canadian economy, and the adverse effect on the industry of previous high tax rates was made far worse by the confusing, contradictory and perverse nature of the tax system itself. This is a story with some happy parts in it, and, in fact, governments in Canada did learn, haltingly and grudgingly, that there are limits on the amounts that governments could safely extract from the industry, and that some assurances of long term fiscal stability were necessary if investors were to be induced to make massive commitments which could only be recovered over very lengthy periods.

Jan 1, 1982

By Michael M. Donahue

"The public interest -- as opposed to the narrow interests of particular shippers -- will also benefit from the establishment of adequate revenue levels and the revitalization of the railroads. And this is particularly true with respect to the transportation of coal. "

Jan 1, 1981

By D. G. Ball

Other than being used to convey fill material for the gob stowage or building of ribside packs on advancing longwell faces, pneumatic conveying has not been used for the transport of materials on a large scale in mining operations. The technique is extensively used in the wood products industry for conveying wood chips, limestone and other ingredients for the manufacture of paper, for the transfer from railcars, barges or ships to silos or stockpiles and further transfer into the pulp mills. This method of material transfer has the distinct advantage of transporting suitable material over horizontal and vertical distances within the same system. In considering material associated with mining, this includes, ore, coal and rock up to 4 inch cubed size, throughputs of 200 tons per hour over horizontal distances of 3000 feet or vertical lifts of 2000 feet. In recent years tests have been carried out to determine the physical and economic limitations of pneumatic hoisting, the results of which have led to the installation of two fully productive coal hoisting systems at mines of the National Coal Board in Great Britain. The equipment used for the pneumatic hoisting of coal or waste rock is described in this paper, together with a brief history of the tests which led up to the installation of the two hoisting systems in Great Britain.

Jan 1, 1977

By M. Scherzinger, M. Dr. Mazurkiewicz

Additional progress in comminution can be achieved if the compressive crushing principle commonly used at present is changed to one where particles are fragmented by the tensile growth of preexisting internal flaws or cracks, under internal waterjet pressure. This idea was studied in a number of tests and generated results and conclusions are the subject of this paper. It covers tests with different jets imposed on rock samples during compressive load as well as without any loading.

Jan 1, 1992

By N. Dahotre, C. Blue, C. Zhao, B. Parekh, D. Tao, G. Engleman, R. Honaker

Equipment wear is one of the major concerns in screening of coal and minerals. Not only does it decrease the screen service life, it also results in inconsistent aperture sizes and deteriorates the efficiencies of downstream operations. In this research, a coating technique based on laser surface engineering (LSE) was successfully developed to increase the life span of raw coal screens. The microstructure and wear properties of the coating were investigated in this study. Enhanced wear resistance performance (up to 11-fold increase) of coated screens has been achieved in laboratory wear tests.

Jan 1, 2006

By William H. Langer

Nearly every community in the United States is dependent on aggregate (sand, gravel, and crushed stone) resources to build and maintain its infrastructure. Unfortunately, developing aggregate resources to meet societal needs causes environmental impacts. Most environmental impacts associated with aggregate mining are benign. Extracting aggregate seldom produces acid mine drainage or other toxic effects commonly associated with mining of metallic or energy resources. The most obvious environmental impact of aggregate mining is the conversion of land use, most likely from undeveloped or agricultural land use, to a hole in the ground. This major impact is accompanied by loss of habitat, noise, dust, blasting effects, erosion, sedimentation, and changes to the visual scene. Some of the impacts are short-lived, and most are easy to predict and easy to observe. Most impacts can be controlled, mitigated, or kept at tolerable levels and can be restricted to the immediate vicinity of the aggregate operation by employing responsible operating practices and available technology. The intensity of environmental impacts generated as a result of mining are determined in large part by the geologic characteristics of aggregate deposits (geomorphology, geometry, and physical and chemical properties). Mining deposits that are too thin, or contain too much unsuitable material, results in the generation of excessively large mined areas and large amounts of waste material. Mining aggregate can lead to serious environmental impacts in some situations. Some geologic environments such as active stream channels, slide-prone areas, and karst terrain are dynamic and respond rapidly to outside stimuli including aggregate mining. Some geomorphic areas and (or) ecosystems underlain with aggregate serve as habitat for rare or endangered species. Similarly, some geomorphic features are themselves rare examples of geologic phenomena or processes. Mining aggregate might be acceptable in some of these areas, but should be conducted only after careful consideration, and then only with extreme prudence. Failure to do so can lead to serious, long-lasting, and irreversible environmental consequences, either in the vicinity of the site or at locations distant from the site. Environmental impacts caused by irresponsible aggregate mining can compromise mining in an entire region.

Jan 1, 2001

By F. Kitzinger

The possibility of increasing the efficiency of mineral processing plants by means of computer control has prompted metallurgists to examine their flowsheets more critically in order to develop practical control strategies. Control schemes in use to date generally rely on the automation of traditional and previously manually regulated control loops, for instance the addition of reagents to maintain a constant assay or a constant pH. This approach is predicated on the availability of well-established primary sensors such as pH electrodes or on-stream analyzers. Noranda Research Centre, in cooperation with Noranda Group concentrators, has developed a froth level monitor and a pulp density meter susceptible of application in this type of control. Although some of the basic principles on which they are based have been known for some time, their incorporation into the design of reliable, direct-reading instruments which can be interfaced with a computer, is be-lieved to be novel*.

Jan 1, 1977

By N. Langsford

The Archaean Yilgam craton has been a major gold province since 1888 with production and reserves of about 4700 tonnes. Production in 1994 was about 135 tonnes. The largest deposit, the famous Kalgoorlie Golden Mile, contains about 2000 tonnes of gold. About 40 deposits containing more than 35 tonnes (1Moz) of gold has been discovered so far in the Yilgarn. Most of the craton has deep weathering profiles inherited from previous tropical climatic conditions, modified by subsequent arid conditions. A mantle of transported material covers much of the variably stripped weathering profiles. Resolving the geology of the volcanic-sedimentary units (greenstones) and the structures that host the gold mineralization relies heavily on aeromagnetics and shallow drilling.

Jan 1, 1995

By Ralph Loyd

One of the principal responsibilities of the California State Geologist is to provide local governments with maps and information regarding mineral resource occurrences within their jurisdiction. The primary objective of this effort is to furnish basic data that is essential in planning for and accommodating wise development of mineral deposits that are important to the economic well-being of the region, state, and nation. Local government agencies are required by law to incorporate the information provided by the State Geologist into their general plans and formulate mineral resource management policies that emphasize conservation and development of mineral deposits. The Mineral Land Classification program was initiated by the State Geologist in 1977 under authority of the California Surface Mining and Reclamation Act (SMARA). To date, about 33,000 square miles of land have been classified for mineral resource potential. Most of the mineral land mapping has been conducted in three principal areas: (1) metropolitan areas of the state where urban encroachment has greatly diminished available supplies of construction aggregate; (2) Sierra Nevada foothills, a region that is undergoing dramatic population increases; and (3) the Mojave Desert and Great Basin regions, where large Federal land withdrawals are pending that could preclude mining. Mineral land classification studies address the overall mineral potential of a region through the identification of local and regional geologic factors that control or influence the formation of mineral deposits. These studies are field-intensive surveys that enable project geologists to gain first-hand knowledge about the nature and distribution of mineral deposits in a given area and portray that information accurately in map form. This paper summarizes the progress made in the Mineral Land Classification program in the metropolitan, Sierra Nevada foothills, and the Mojave Desert/Great Basin regions of California. Selected projects from each area are discussed in detail.

Jan 1, 1995

By Siyu Song, Yanhong Wang, Guohua Gu, Linbo Huang

In this study, the effect of cations, Na+ and Mg2+, in saline water on copper flotation in the presence of calcium bentonite was investigated. It was found that as the concentration of NaCl was increased, the copper recovery initially decreased and then increased to above 99%, while the copper grade initially increased and then decreased. In contrast, as the concentration ofMgCl2 was increased, the copper recovery continuously increased, while the copper grade continuously decreased. The variation of copper recovery and grade was mainly attributed to the synergistic effect of pulp rheology and flotation solution chemistry. The underpinning mechanisms are the compressing electrical double layer and ion-exchange interaction between saline water and bentonite, which occur at the same time. Using salinewater slightly affected the pulp rheologywith a decrease in copper recovery at low NaCl concentration. Increasing the concentration of cations in saline water might even facilitate the flowing out of exchangeable cations, especially divalent cations, from the interlayer space of bentonite to the solution, resulting in the decrease of copper grade at high salt concentration.

Sep 10, 2020

By Ian H. Clark

A series of numerical experiments were performed in order to elucidate the stress distribution, fracture strength and mineral liberation potential in single specimens of rock during crushing. Fracture strength was shown to reduce under eccentric loading conditions. Similarly, the presence of inclusions, both hard and soft, reduced the fracture strength. The predicted crack paths indicate that mineral liberation is unlikely to be preferential.

Jan 1, 1992

By Herbert S. Richey

Two hundred years ago next April, our forebears embarked upon the difficult path to national independence. They succeeded, and shook off the yoke of foreign domination. In the ensuing two centuries, the country was mobilized several times to protect that political and economic independence from foreign domination. These efforts were also successful. Thus, as we stand here on the threshold of our third century of political independence, we can thank previous generations and congratulate ourselves for establishing and maintaining the world's oldest republic. Now -- once again -- the United States faces the challenge of foreign intervention into our economy. This time the battleground is resource avail- ability. America has been blessed with enormous resources. Whether we speak of minerals or timber or water or "amber waves of grain," this nation has benefitted from a resource base that is the envy of the world. This asset, coupled with a political system that permitted us to develop it, has been the physical backbone of our independence. Without the economic independence that this resource base has given us, the political independence we fought for would have been tenuous, at best.

Jan 1, 1975

By A. B. Holland-Batt

Following a relatively static period in the 1960s and 1970s when incremental development rather than innovation was the norm for gravity separation, the last 15 years has seen a number of new developments in this area. The paper briefly reviews the traditional gravity separation techniques and then examines the newer developments such as centrifugal separators. Particular emphasis has been placed on novel devices or improvements that offer either better control or improved performance.

Jan 1, 1998

By E. M. Cukrowska

The evaporative pan complex consists of two adjacent seasonal pans. These pans carry an exceptionally high salt (TDS) load due to over 50 years of effluent discharge via the pipeline from mines. The nutrient, heavy metal, radionuclide load in the water and sediments of the pans are very high affecting groundwater around the pans. The groundwater in the region contains TDS > 40 000 mgl-1 and sulphates > 7000 mgl-1, whereas groundwater in areas assumed to be unpolluted by mining activities have TDS < 500 mgl-1 and sulphates < 200 mgl-1. The extent of continuity between the pans and the groundwater is unknown, although there appears to be seepage of contaminated groundwater into the river system.

Jan 1, 2006

By R. D. Beard

Puerto Rico lies within the remnants of a deformed Cretaceous island arc system in the northeastern Caribbean. The Island can be divided into three broad geologic provinces: the Central Volcanic-Plutonic Province (Lower Cretaceous to middle Eocene), and the Northern and Southern Limestone Provinces (early Oligocene to middle Miocene). Known precious metal deposits are generally small and occur in veins and shear zones within Lower and Upper Cretaceous volcanic and plutonic rocks. Some Tertiary igneous rocks are also mineralized. Selected indications of disseminated lithology-controlled mineralization could represent larger deposits. Associated metals in some deposits include copper, zinc, and lead. At present, tax policies, population density, political outlook, and lack of proven significant precious metal deposits discourage the establishment of a metal mining industry.

Jan 1, 1993

By C. L. Sainsbury

For 10 years, the author has been engaged in a program of geologic mapping of the Seward Peninsula, Alaska, for the U.S. Geological Survey. Initially, two 1:63,360-scale quadrangles were napped by traditional methods of traverses by foot and by tracked vehicle, supplemented by reconnaissance from a light aircraft owned and piloted by the author. Five summers were required to map those two quadrangles, which lie north of the tree lice in typical Arctic climate. In 1967, the project was reoriented toward the reconnaissance capping of four 1:250,000-scale quadrangles, with helicopter support to be used for cart of each of four summers amounting to about 45 hours time per support year. The light aircraft was use-,&apos; to support the field operations. Over the year,, the aircraft was used in progressively more geologic tasks, culminating in 1970 with a successful field test of rudimentary devices made to collect soil, rock, and sediment samples while the aircraft remained airborne. Additionally, an attempt was made j- 1970 to prepare reconnaissance geologic maps entirely by the use of the light aircraft combined with foot traverses [fr??], the landed aircraft. Several such maps, prepared at the rate of about one 1:63,360-scale quadrangle per day, were checked from a helicopter by an impartial observer end were found to be sufficiently accurate for reconnaissance mapping when reduced to 1:250.000 scale.

Jan 1, 1971

By E. A. Rychkun

Mining and environmental objectives have traditionally been in conflict. This conflict reflects a delicate balance between the need to spend money to protect the environment, and the need to save money by extracting minerals efficiently. In an increasing number of cases, profit margins diminish rapidly with new environmental regulations and reactionary measures. Forced cleanups and increasing restrictions are unwelcome expensive processes. A practical solution lies in planning rather than reacting. This requires the ability to precisely quantify and qualify environmentally sensitive problems by providing effective engineering tools to model, visualize and analyze subsurface conditions. Prevention of environmental conflicts, and effective cost control are both rooted in the mining company&apos;s ability to construct accurate models, monitor changes, assess contamination risks and to design effective remediation plan. This paper presents a case study where these issues are addresses through the application of a new and innovative technology.

Jan 1, 1993

By S. A. Jeric

In-pit crushing and conveying of waste has been utilized in the mining industry for over 30 years. In recent years, innovations in crushing, conveying, and particularly waste and leach stacking technology have sparked a renewed interest in continuous haulage systems for large-scale open pit applications. A review of the advantages/disadvantages and operating techniques of crushers, feeders, conveyors, and stacking systems currently available is made. The paper examines some operations that are currently using large scale continuous haulage systems. Finally, a case study is presented that evaluates the application of a continuous waste haulage system in a large open pit mine in the Western United States, The case study includes a economic comparison with the existing truck haulage system.

Jan 1, 1997

By J. P. A. Hortley

In conventional electrolytic copper production, looped copper starter sheets, on which the copper is deposited, are supported by hard-drawn copper bars. These bars have cross-sectional areas of between 1 and 1.4 in2. The suspension bars serve two purposes: firstly to support the cathode, which can weigh up to 150 kg, and secondly to introduce the electric current. IYI examined these two requirements in detail to see whether a better design could be achieved. Considering firstly the current carrying requirement, it wee noted that under normal refinery conditions, each cathode carries between 400 and soak. If one applies the generally accepted rule that 1 in of copper can carry 1000A4 a suspension bar need theoretically contain only 1/2 in2 of copper. This contention is supported by the fact that the 500A current passed through the cathode also appears to pass quite satisfactorily through the two support loops, which have a cross-sectional area of approximately 0.35 in 2. Turning now to the strength requirements, the cross-section of hard-drawn copper bar required to support a 150 kg cathode is relatively small, and easily met by the present designs. It is not, however, the static load applied by the 150 kg cathode immersed in the electrolyte which causes the damage to the hard-drawn copper, or even the increased static load of a 100 kg man standing on one foot in the centre of the bar; the damage is actually caused by the dynamic loads applied to the bare when they are dropped, thrown into containers, lowered too rapidly into the cell, or otherwise mistreated. The important requirement is therefore that the bar does not permanently bend. Its proof stress of limit of proportionality, rather than the amount that it deflects under static loading, should be the strength criterion. With the hard-drawn copper normally used for the manufacture of suspension bars, it has been observed that the copper becomes annealed during use, particularly at the end of the bar where the current is introduced. Thus, after a relatively short time, the cathodes are in effect being supported by annealed copper bars.

Jan 1, 1978