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By A. Pavlides

The purpose of this work is to conduct a preliminary analysis of the spatial variations of the thickness of lignite layers in the area of the Amyndeo mine, and to estimate the lignite reserves of the mine. The reserves are estimated by the method of the Voronoi diagrams, using a group of mirror points to close the polygons around the boundaries of the mine. Two data sets are investigated. The first one corresponds to an exhausted part of the mine. The derived reserves estimates are compared with the actual data obtained by the Public Power Corporation (PPC) to validate the analysis. The second data set extends over the entire mine, and it is used to derive an approximate estimate of the total lignite reserves. A geostatistical analysis of the total layer thickness is performed. The experimental semivariograms are evaluated for both data sets in different spatial directions. Two possible theoretical models for the experimental semivariogram (the exponential and a novel Spartan model) are compared and discussed. An interpolated kriging map of the total thickness variation is produced accompanied by a map of the kriging precision. The performance of kriging interpolation is discussed in terms of cross validation measures.

Jan 1, 2007

By Fernando H. Muge

The first application of dynamic pro¬gramming to the problem of grade control and scheduling was by Muge et al (1979) and Ribeiro (1982) who applied it to the simple, two-dimensional case of longitudinal open stoping using two sublevels. In this paper the formulation of the problem is extended to cover the general case applied to a cut-and-fill mining method. The criterion for optimization is the total deviation of the average, grades of mining blocks from the overall average panel grade (or the average grade of a set of mining panels or the mine processing working point). This means to schedule the operation by removing a certain number of mining blocks at a time, subject to the geometric (mining) constraints, and such that the total deviation of average block grades from overall average grade is minimum. The method can be applied to complex orebodies with several ore characteristics and the deviation of each one of these characteristics can be further constrained by specifying maximum values. The method can also be generalised in order to take into account any necessary geometric constraints used to define the mining method. In this paper a case study is presented concerning the mine planning of a complex sulphide orebody located in the South of Portugal. As input for the definition of the mining sequence, a geostatistical numerical model of the orebody was built based on a previous ore typology. The short term planning is used to assess specific mining sequences and the production scheduling is performed on the basis of an objective function (e.g. minimization of grade fluctuation).

Jan 1, 1989

By Kenneth Ronald Miller

Thunder Basin Coal Company's Black Thunder Mine is located 80 km (50 miles) southeast of Gillette, Wyoming in the Powder River Basin. Surface coal mining operations began in 1977. The Black Thunder Mine has been North America's largest producing coal mine for over 5 years. Production in 1988 totaled 22.6 million mt (24.9 million st) of sub-bituminous coal. Thunder Basin Coal Company is a subsidiary of Atlantic Richfield Company. The mine began as a truck-shovel stripping and mining operation. Haul trucks of 154 mt (170 st) capacity were part of the original fleet. In 1985, 218 mt (240 st) capacity trucks were introduced to the fleet. In 1988 a dragline was added for stripping. A single, primary/ secondary crushing stream feeds either a slot storage facility or dual silos. Three loading points are situated over two rail loops serviced by the Burlington Northern and Chicago North-western Railways. A Near Pit Crushing and Conveying system is currently under construction. It is expected to be completed during the fourth quarter of 1989. During the past 10 years, the conceptual crushing/conveying design has changed several times as technology and commodity markets have changed. The system under construction will have a capacity of 4700 mtph (5200 stph). The overland belt will be 3570 m (11,700 ft) long and 1800 mm (72 in.) wide. The belt speed will be 300 meters per minute (1000 fpm). Two separate crushing streams will feed the overland belt. Each stream will be comprised of a dump hopper at reclaim surface elevation, a drag feeder, a two-stage triple-roll crusher, and an incline conveyor of 2700 mtph (3000 stph) capacity. This article will describe the different concepts and factors that have resulted in the system design now under construction.

Jan 1, 1989

By K. G. Tsakalakis

The Greek Cement Industry is a vital sector of our economy. With an annual production of cement over 15.5 million tonnes, it contributes significantly to the national gross domestic product (G.D.P.). The cement industry, as other mineralogical transformation process industries (lime, glass, ceramics, extractive metallurgy etc.), is high energy intensive. Each tonne of cement produced requires not only large amounts of fuels (coal, fuel oil), but additionally a significant quantity of electrical power as well. All fuels consumed by the Greek Cement Industry are imported and energy accounts for one third of the cement production cost. Therefore, it is of interest of the community and the industry to increase energy efficiency, to reduce the quantities of fuels consumed in the cement manufacturing process. It is also known that like almost all manufacturing processes, the cement industry produces large amounts of CO2 (combustion of fuels, de-carbonization of limestone and use to electricity). The utilization of wastes (principally as alternative fuels, scrap tires, spent solvents etc.) is compatible with the general principles of waste management and it is also a common practice in other European and developed countries. In the present paper the economic, social and environmental benefits provided by the recycle process of the various wastes in the Greek cement plants are extensively analyzed. From the whole work, it was concluded that such a practice: - replaces a significant percentage of imported fossil fuels in the cement manufacturing process, - maximizes the recovery of energy and also ensures their safe disposal, - produces overall environmental benefits by reducing releases to air, water and land, - prevents resource depletion of valuable non-renewable fossil fuels, - overcomes the need for the construction of dedicated incineration facilities, - contributes positively to the principles of the sustainable development.

Jan 1, 2003

By K. Konialis

In the last twenty years, the mining industry has made marked efforts to improve its reputation in regard to its social performance. These efforts have been expressed in the 9th ICMM (International Council on Mining and Metals) principle as a commitment to contribute to the social, economic and institutional development of the local communities. Towards this goal, which has been increasingly highlighted because of its importance for sustainable development, a number of practices and methods have been developed. The international development literature describing these practices is full of so-called development buzzwords, such as stake-holder participation, empowerment, capacity building. This paper argues that none of these development catchwords are neutral, but contain assumptions based on a specific view of development. Since capacity building is a central task in development, the paper focuses on this concept and takes a critical look at the assumptions that underlie this concept and influence strategies employed by the mineral sector. It suggests that the notion of capacity building in some earlier approaches implies a set of asymmetric power relationships between developed and developing countries where capacity is transferred from the developed countries to the developing ones. The developing countries are seen as passive recipients while the experts, i.e. the developed countries through their mining companies ultimately control the capacity-building process. The paper also points out that the mainstream capacity development approach has been based on the assumption that local or indigenous communities are mainly made up of needs and capacity gaps. The goal of development projects should then be to address these needs, which are perceived and prioritized by the ?experts?. Critiques of this development model suggest that in order for the mining industry to embrace more successful and sustainable practices, it should rethink the notion of capacity building. It should move towards alternative approaches that see it as a two-way learning process which will serve to enhance not only the capacities of the communities, but also of the development practitioners and which will build on the strengths of the community, and move away from attitudes of superiority and practices of dependence.

Jan 1, 2007

By V. D. Ayurov, N. O. Kaledina

The coal mines monitoring should be based on the usage of simple and evident models, letting in the total unity to reflect a structure of organization of mine, system ability of its construction and specific character of its functioning. Such models are offered to create on the basis of extracted hierarchies of objects of mine. All objects of mine are broken on levels of technological hierarchy. For objects of each level of hierarchy there are made balanced models of entering and leaving material flows. Then these balanced models are coordinated among themselves by the help of the inter hierarchical relations. So the structured-qualitative characteristic of the object of monitoring, reflecting in a kind of the table structure of formation of material flows on mine, their intensity and measure of transformation is formed under transition from one level of hierarchy of mine to another. An example of real us- age of hierarchical balanced models on mine is given. The mathematical models of coal mine monitoring should reflect objective laws of their structural organization and functioning. Therefore under the constructing of mathematical models it is important such a way to reflect a structure of the mine organization, that in totality the models has been reproduction of system ability of its construction. The knowledge of the separate parties of functioning of mine, reflected in particular mathematical models, should "to be packed" in combined unity. Or else, they should be connected in system, convenient for recognition by the person. Considering the mine, the expert allocates multi-dimensionality of the objects of making its elements. He always has the knowledge of laws of development of mining work that is connected with pithy stratification of researched object. In dependence of sparial-temporary level of abstracting there are allocated the horizon, wing of a mine field, layer, panel, extracting face, longwall in coal mine. The human thinking on each of these levels operates with a set of concepts peculiar to him, characteristics, definitions.

Jan 1, 1996

By Zeynep Aktuna

In this study, the formation of zeolites around Kizkapan and Karlikoy villages (Sothwest Kesan) were investigated. In this region, stratigrafically, Upper Eocene Kesan Formation, i.e. sandstone and rarely shale are observed at the bottom. Early Middle-Oligocene Yenimuhacir Formation is composed of sandstone, marl and tuffs. The zeolitisation is determined in the dasitic tuffs of the Yenimuhacir Formation. In this tuffs' zone, alteration had primarily resulted in zeolites, mainly mordenite, heulandite-clinoptiIolite. Silicification and alteration to clay minerals are also common. The Miocene-Pliocene Ergene Formation and alluvium deposits are the top units in the area. In the studied area, zeolite occurences have economic importance. The results show that successively rapid and short term periods are responsible for the clinoptilolite-heuylandite formations. The homogene chemistry of the solutions may be evaluated for a possible successive zeolitisation period. Multi-periodic vocanic activity and also circulation of thermal water had resulted in a continous dissolution of volcanic glass; moreover, resulted in the formation of suitable conditions of zeolite formation. The mineral crystallization sequences and alteration products as zeolites within the wall-rock, circulated solution reaction depends on a serie of parameters such as chemical composition of both initial materials and volcanic solutions during rock¬solution interaction period. The previous researches and the chemical studies support our results and observations in the studied area. The aim of this study is to investigate the presence of zeolitisation and to explain the formation steps of zeolitisation in Kesan Area by considering the content and distribution of major and minor elements determined in zeolite bearing tuffs. The chemical structures of both zeolite bearing volcanics and zeolite minerals are compared to the results of previous studies. Two dimentional behaviours of major and minor elements were discussed in order to caracterize zeolitisation development and to postulate a probable formation type of zeolitic alteration.

Jan 1, 2005

By K. Anderson

There is a credible, cogent, and responsible argument that mining can be part of a sustainable future in countries with freely elected governments, transparent and enforceable laws, a closure plan with an adequate bond, and a small handful of other measures. This perspective, built largely upon the understanding of mining as a temporary use of the land, is coupled with a growing understanding of economic diversification as a tool to level out the ‘bust’ side of the boom and bust cycle. There are verifiable signs of progress that the sector has, at least in some venues, begun to embrace this view of ‘sustainability’ both in philosophy and practice. While laudable, there remains a conundrum not yet fully explored. It is conceivable that companies can fulfill all legal requirements, practice corporate responsibility in its broadest and most liberal interpretation, and yet leave behind, after the gates are closed and the lights turned off, a situation which is not only unsustainable, but far worse off than before mining started. Having observed this outcome, repeatedly, some critics have concluded that all mining should be stopped. Others recommend that it be vastly curtailed until regulatory regimes are re-vamped, communities fully empowered, and companies brought to heel. Yet others, including many within the industry, are looking to hold back this dark prospect with peer pressure, branding and competition for good will. In this paper, I propose to focus on this discontinuity, that gap wherein the chain of logic breaks and reasonable policies, reason-able choices, reasonable actions, may fail to deliver expected results. I suggest that any meaningful definition of post-closure sustainability must include the concept of human welfare, and increasingly, human security, over and above meeting the requirements of law, beyond retaining shareholder value and reputation, beyond discussions of subsequent land use and diversified employment. I suggest that self-determination, that ability of a people to hold for themselves the vision of their own future, and to have a sense of their power to implement it, may be both the most difficult and the single most important determinant of long-term sustainability in a community. The particulars will vary; a Canadian junior or an Australian multinational, a highly regulated state in the American west or a ‘failing state’ in Africa’s west, gold or sand and gravel. But the recommendation is the same: this must be a collective endeavor, a shared responsibility involving some combination of government, companies, communities, local and international NGOs (non-governmental organizations), each contributing in the ways most able.

Jan 1, 2004

By William H. Sutherland

INTRODUCTION Coal workers' pneumoconiosis and sili- cosis are only two of several diseases which are rlassed as pneumoconiosis. These are respiratory diseases caused by dusts which are inhaled and accumulated in the lungs. The individual particles of dust cannot be seen by the human eye. They are so small that they escape the natural cleansing mechanism of the nose and air passages and make their way down to the terminal air sacs of the lung where they injure the cells and cause the formation of scar tissue. Consequently, if there is exposure to high concentrations of dust over a period of time - usually, a number of years - the amount of scar tissue increases and begins to impair breathing. As a result, the miner develops shortness of breath, coughing and wheezing ad-if exposure continues - this progresses to permanent disability and frequently to death. Death is often due to pulmonary heart disease, the effect of stress on the heart 2s it tries to compensate for the weakened lungs. Specifically, silicosis is an occupational lung disease caused by the accumulation of free silica (quartz) in the lungs. Silicosis is considered the most important form of pneumoconiosis, not only because of its seriousness as a respiratory crippler, but also because of the large number of workers who risk contracting it in a variety of occupations. Quartz is one of the most common substances of the earth's crust, estimated at about 60 percent. Silicosis has been found in coal, metal and granite miners, as well as in other workers, such as sandblasters and pottery makers. Silicosis is also known to predispose the lung to tuberculosis and to increase the chances that a worker will contract chronic bronchitis and emphysema. The seriousness of silicosis was tragically brought to public attention about 50 years ago. During 1932-34, workers were involved in digging a tunnel through rock at Gauley Bridge, West Virginia. While their exposure time was relatively short, they developed silicosis because of the high concentrations of quartz. By 1936, 476 workers had died of silicosis and about 1500 were believed to have the disease (Washington Post, 1982). It is difficult to tell how many coal miners have silicosis. Because x-rays and breathing function tests do not show the difference the type of pneumoconiosis is generally diagnosed by the miner's work history. For example, if a worker

Jan 1, 1986

By R. P. Killmeyer, R. E. Hucko, P. S. Jacobsen

Cleaning of three coals from the eastern US was tested by five selective agglomeration processes and one selective flocculation process. The coals and processes are described, and the results are reported and compared. Two of the processes, which ground the coal to the finest volume mean diameter, met the stringent test program quality specifications.

Jan 1, 1991

By E. G. Kelly, D. E. Walsh

The behavior of gold particles on a spiral was studied using radioactive gold tracers. The method allowed the effects of particle size, particle shape, pulp density, feed rate and splitter settings to be studied. Although the method has been successfully applied to other gravity concentrators, it was found that reliable results were more difficult to obtain on the spiral. However, these preliminary results show that, with suitable precautions, the technique is capable of providing valuable information, unobtainable from conventional studies, that could be used to better optimize spiral performance.

Jan 1, 1993

By H. T. Miller, L. M. Scott

Radiation exposures in Uranium operations may result from external beta-gamma radiation emitted by Uranium and its progeny, internal exposure to alpha and beta radiation due to the inhalation and ingestion of Uranium ores, Radon gas, and Radon progeny in mine, mill, and laboratory atmospheres and from the contamination of environmental working surfaces and clothing by Uranium-bearing compounds and ore. This paper summarizes occupational experience with reference to the exploration, surface mining, underground mining, milling and transport of Uranium by one company in the U.S. and Canada.

Jan 1, 1981

By Kenneth N. Han, Yichang Guan

The dissolution behavior of metals from Au/Ag/Cu-alloys has been studied using rotating disc electrodes in solutions containing acids, cyanide, and ammonia. Electrochemical methods as well as leaching tests were adopted in this study. The results showed that there was no galvanic effect on the dissolution of metals from homogeneous alloys. In aerated cyanide solutions, the dissolution of gold, silver, and copper from their alloys was partly controlled by surface chemical reaction, but largely by mass transfer. On the other hand, the galvanic coupling effect played a very important role in heterogeneous alloy systems.

Jan 1, 1995

By R. A. Metz, Ted H. Eyde, Dan T. Eyde

Industrial minerals deposits present sampling and grade control problems not normally encountered in metal mining operations. No longer are industrial minerals simply crude ground mineral products but are in fact high purity chemical raw materials. Operators of industrial minerals mines and processing plants now must meet increasingly stringent specifications established by the consumer of the final products. Meeting these stringent specifications requires not only sophisticated processing techniques but equally important careful sampling and grade or quality control at the mine. A well-trained geological staff can assure an adequate supply of uniformily high quality feed to the processing plant. In the final analysis this results in significantly higher operating profits.

Jan 1, 1992

By R. L. Lewis

The White Pine Mine is a large underground copper mine located in the Upper Peninsula of Michigan. A numerical ground water flow model of the White Pine Mine was constructed to evaluate potential engineering controls that would reduce the rate of mine-water discharge after closure. Of the passive controls evaluated, the placement of bulkheads within the mine workings was predicted to offer the greatest benefit, reducing the rate of discharge by as much as 35%.

Jan 1, 1997

By Daniel Hodouin, Antoine Berton

Mineral processing plants are monitored and controlled using measurements that are usually processed by on-line material balance calculation techniques. However, gross errors, due to sensor biases or failures, may corrupt all the process variable estimates. On-line gross error detection methods are required to ensure efficient mass balance evaluation. In the proposed approach, material imbalances and raw measurement corrections are tested by statistical techniques designed to detect and isolate sensor problems.

Jan 1, 2000

By W. J. Cieslewicz

Geologically, northeastern Siberia is a region occupied by a folded belt of Triassic and Jurassic sediments and volcanics. Gold mineralization is of Upper Jurassic age. Most of the stream placers formed during the Quaternary. Placer gold was first discovered in 1916. Between 1930 and 1957, mining was carried out by the "Dal 'stroi," a Russian concentration camp organization. Since 1966, the mines have been worked mechanically. About 10 mining districts are now active, producing, altogether, 110 to 135 t (120 to 150 st) of gold annually.

Jan 1, 1987

By E. F. Loros, T. J. Smolik, V. G. Lofftus

Since plant start-up in January 1983, Golden Sunlight Mines Inc. has implemented several process changes and improvements. Among these are a pulp preaeration circuit and a sand tailing retreatment circuit. The preaeration circuit reduces reagent consumption during gold dissolution. The sand tailing retreatment circuit was added to recover and process separately pyrite concentrate to maintain acceptable overall gold recoveries with the more refractory sulfide ores. Research and plant operating data along with process and improvement descriptions are presented.

Jan 1, 1987

By Fred N. Kissell, Jeffery L. Kohler, Edward D. Thimons

Aerodynamic stall of vane-axial fans is both an operational problem and a safety concern. While deep stall is relatively easy to detect, the diagnosis of a partial stall is often more difficult. Its transient nature and the fact that its symptoms can mimic electromechanical problems of the fan and fan drive assembly, or vice-versa, compound the difficulty of making a timely and accurate diagnosis. A knowledge-based expert system known as FANPRO has been developed to aid in the diagnosis of these problems. FANPRO and its application are the subject of this paper.

Jan 1, 1991

By K. V. S. Sastry

Pelletization, sintering, and pressure compaction are the most common methods used to agglomerate ore concentrates. Over the last 20 years agglomeration has grown enormously in popularity and has become a standard unit operation in the nonferrous, cement, fertilizer, and ceramic industries. However, it is in the processing of iron ores and the preparation of blast furnace feed that agglomeration is used most and its application has grown fastest (Ball, et al., 1973; and Sastry, 1977). This chapter deals with an account of the current practices and future trends in the application of computers relative to an overview of the process design and engineering considerations of the unit operation of agglomeration.

Jan 1, 1979