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What is your assessment of the mining industry as we near the end of the 20th century? As it always has, the industry is continually changing. The recent rate of change has been hectic. Many mining-related commodities are selling at low prices. These include gold, silver, copper, coal and soda ash, to name a few. Lower prices place pres- sure on mining companies to increase efficiency through productivity, down- sizing or mergers. The short- term effect of this situation may adversely affect the individual SME member. But the long- term benefit is to build a stronger, more productive and internationally competitive mining industry. In addition, most of these metals and minerals have been historically cyclical in nature, and prices will rebound.

Jan 1, 1999

By Vanessa M. Torres, Lafayette C. L. Freitas, Evandeo C. Silva

This paper shows two applications of artificial intelligence models in process development. In the first application, a heuristic fuzzy correlation can predict flotation behavior in bench scale based on feed characteristics for a high variability copper ore, as well as to predict plant performance for a feasibility project evaluation, minimizing its risk. The second case study shows the use of neural networks to model the iron ore sintering, correlating ore characteristics and operational parameters with sinter properties. With this application, CVRD aims to establish a new step on iron ore product evaluation and customer support.

Jan 1, 1998

By J. E. deMasi

Over the past 12 years, Exxon Coal U.S.A., Inc. has shipped over 150 million tons of coal from two mines, Rawhide and Caballo, located in the Gillette, Wyoming, area. These mines are operated by The Carter Mining Company, a division of Exxon Coal. Shipments have moved to more than 25 electric utility plants in the west, midwest, southwest, and south. The customer plants have represented a wide variety of configurations, sizes. design criteria, emission standards, and operations in different parts of the country. We have learned a great deal about the performance of Gillette area coals in utility power plants during this period. This paper covers some of the highlights of Exxon's experience with these coals in customer plants. I will focus specifically on things mining engineers may be able to do to make the product better for the customer's use.

Jan 1, 1989

By J. K. Phiri

Copper mining is the main activity in Zambia and is confined to the large scale operations, mainly on the Copperbelt. The Copperbelt covers an area of size l00km by 50 km with a total of 10 underground and 5 open-pit mines operated by Zambia Consolidated Copper Mines (ZCCM) Limited. Most of the operations in these mines involves drilling and blasting. The loading of broken materials is by both manual and mechanical operations. Among the many risk factors associated with mining on the Copperbelt, is the occurrence of Pneumoconiosis which in the recent past has become quite prevalent and thus an important occupational health hazard for the industry. This study was carried out with the aim of establishing trends of pneumoconiosis incidence through the annual data collected by Pneumoconiosis Medical and Research Bureau of the Ministry of Health in Zambia, so that a basis could be formed for future research work. The study covers over 1,000 certified cases of Pneumoconiosis between 1960 and 1990

Jan 1, 1993

By Michael F. Jeglic

Dust control methods are practiced throughout the mining industry in order to protect the health and safety of its workers, the integrity of the environment, and to guard against the loss of valuable product. The use of water is often the best and most economical method of controlling dust. Increasingly, chemical agents are being chosen over more traditional mechanical means of controlling dust. Some chemicals are used alone, and many are used to enhance the dust controlling properties of water. This paper describes the various types of chemicals available and their applicability to specific problems encountered by industry.

Jan 1, 1986

By Donald L. Bott

A computer model called the Quality Compliance Model was developed to optimize the mine planning and sequencing in area coal mining with respect to the limit on pounds of sulfur dioxide per million BTU imposed by regulations. The objective of the model is to maximize the amount of high sulfur coal mined from various benches while meeting the specified compl'ance standards. Given multiple seams and multiple benching operations, the mining sequence from each pit is simulated. The rate of mining is controlled such that the in-pit blending will maximize the usage of high sulfur coal and meet compliance standards. The compliant coal can be stockpiled for usage at a later date, or it can be disassociated. This calculation can be based on any given rate of production, i.e., from as small a unit as a unit train to as large as monthly or yearly production.

Jan 1, 1982

By E. Topuz, C. Patrick

Longwall face-to-face equipment transfers or moves are the largest source of nonproductive time in a long wall-mining system. Detailed planning and resourceful thinking are paramount for economical, safe and timely longwall moves. New equipment and innovative techniques are frequently tested to reduce overall more time. Determining the cost-effectiveness of these ideas is difficult since the decision is influenced by many subjective factors. A project scheduling simulation model of the longwall move process was developed to analyze and assess the economic viability of innovative transfer methods and equipment. The model provides a project-duration frequency distribution and lists of critically indexed activities and paths. It compares the monetary savings from reduced transfer time and capital costs for several ideas.

Jan 1, 1996

By Andrew H. Stearn, Robert O. Agbede, Edward F. Divers

The ability to compete profitably in a competitive, demanding and specialized market, requires all components of productivity to be optimized toward the same manufacturing goal. This ever present requisite is seldom more apparent than with the quality control (PC) considerations that confront the super-refined metallurgical production necessary for today's exacting technical applications. In a work-place that already exceeds all environmental standards for cleanliness, this paper describes the development of specific environmental mechanisms and controls implemented at a titanium processing facility to impact both the minimal air-borne particulate contaminants and excessive process heat generation which are believed to degrade product purity. Based on the analysis of a carefully structured and instrumented field survey, two alternative solutions were proposed to modify the present facility utilizing a forced air (blowing) system. The first scenario requires ambient air to be drawn from a louvered rooftop installation and ducted to specific zones within the plant with appropriate weighted louvers and wall and roof exhausters designed into the system for air control. The second scenario incorporates a properly sized baghouse to be used in conjunction with the first system.

Jan 1, 1991

By K. Biswas

A finite-element algorithm was developed for an axisymmetric heat-transfer problem involving phase change. The finite-element treatment of the phase-change problem was dealt with by using the enthalpy method. The finite-element algorithm was subsequently applied to model the heat exchange between mine ventilation air and frozen ground in the presence of roof bolts in an underground mine with permafrost. This paper analyzes a single bolt in the problem domain with the convection boundaries at the roof level of the mine airway. A short-term study, comprising the evaluation of roof bolting (friction-anchored type), was conducted, and recommendations were made regarding the applicability of roof bolts as a support system for a given thermal condition.

Jan 1, 1996

By D. Tao

The presence of insoluble slimes in potash ore poses a serious processing problem to the potash industry. These insolubles must be removed prior to potash flotation because of their high adsorptive capacity for amines which are generally used as collectors in the subsequent sylvite flotation. This is usually accomplished by scrubbing of the ore in brine followed by hydrocyclone classification to separate slimes from the salt particles. Insoluble slimes that remain in the ore after the desliming procedure are depressed by reagents such as guar gum or starch during sylvite flotation. In this research, the feasibility of using GP clay binders to replace guar gum for potash flotation was investigated. Batch mechanical flotation tests were conducted with the potash samples provided by a leading potash company. It has been found that GP clay binders increased potash concentrate yield and recovery at the same product grade. Effects on potash flotation efficiency of flotation process parameters such as impeller rotation speed, slurry temperature, binder type, dosage and conditioning time have been investigated to establish the optimum conditions for flotation. Binder GP374G33 has been identified as the optimum substitute for guar gum as slime depressant in potash flotation.

Jan 1, 2008

By Huaiyu Liu, Shan Liu, Dashang Chang, Maixi Lu, Yaqun He, Yali Kuang

The expert system for coal preparation plant design mainly solves the crux--separation flowsheet design and optimization of product structure. There are twelve basic flowsheets available in the system which are representative of financial plants. The system can select better flowsheets automatically according to the property of feed and scale of plant. Then, it can choose the best flowsheet and product model from the better flowsheets through analysis and optimum calculation. The expert system is made up in Turbo Pascal 6.0 and consists of three sub-systems: Lump and grain coal system, coal slimes processing system, and raw coal system. Several representation methods, such as production rule, procedure, and object-oriented programming, are used to express the expert's knowledge in the system. To decide the optimum product structure, Zangwill's method is used to make an advance product model. The expert system has the performance of interpretation strategy, by 'tracer" technology and pre-arrangement text, and of learning new expert's knowledge.

Jan 1, 1996

By A. D. Unsted

The Premier mine has been in existence for over 75 years and is closely woven into the glamour of the history of South Africa. A note on the geological formation of the diamond pipe and the gabbro gives a clearer overall picture of the mine. Mining methods for operations above and below the gabbro sill are briefly discussed. Ventilation arrangements for mining above the sill are briefly described and possible ventilation arrangements for mining below the sill are discussed in more detail. Note: conversions to S.I. units are not exact as rounding has been done.

Jan 1, 1980

By Todd R. Taubert, Kenneth L. Bickel

The U.S. Bureau of Mines (USBM) pioneered the development of disposable filters for reducing diesel particulate emissions from permissible mining machines. The USBM is now evaluating filter media that can withstand the high exhaust temperatures on nonpermissible machines. The goal of the evaluation is to find an inexpensive medium that can be cleaned or disposed of after use, and will reduce particulate emissions by 50 % or more. This report summarizes the results from screening tests of a lava rock and woven fiberglass filter media. The lava rock media exhibited low collection efficiencies, but with very low increases in exhaust back pressure. Preliminary results indicate a collection efficiency exceeding 80 % for the woven fiber media. Testing of both media is continuing.

Jan 1, 1995

By Abdullah Arik

An ore reserve block model is the basis for various decisions in mine development and production. The block model is initially built using the information from the drillhole data only. Once the mine is put in operation, the information from the blasthole data becomes available. Since the spacing of the blastholes are much closer than the exploration drillholes, the blasthole data gathered from the mine over the years become quite extensive containing valuable information about the deposit. In practice, the information from the blastholes is the basis of determining the ore and waste boundaries between and within mining blocks. In an ore reserve model, the valuation of blocks on and close to the pit face can obviously be improved by using blasthole data from neat by drilled and mined-out blocks in addition to using the widely spaced drillhole data. The ideal basis on which to integrate blasthole and drillhole data is to use cokriging.

Jan 1, 1996

By Michael G. Nelson, Hanguang Wu, V. Izaxon, Sukumar Bandopadhyay

The method of mine ventilation involving heated air, which is frequently used in mines in cold regions, does not correspond to the natural conditions prevailing in permafrost regions; it is not economical and leads to a series of complications which can be prevented or greatly reduced by lowering the temperature of the air stream entering the mine until it is equal to or very close to the temperature of the frozen ground This paper presents ventilation design approaches which can be engineered to provide the required micro-climate and thus en- sure the stability bf the ground for placer mines in permafrost. Specifically three ventilation design approaches are presented: 1) design based on minimum thermal impact; 2) design based on positive/negative heat accumulation in the existing mine airways; and 3) design based on heat exchanging devices such as thermosyphons placed above ground.

Jan 1, 1997

By D. Sotiropoulos

In the recent years, the mining sector is looking for specific indices, taking into account economic, environmental and social criteria, in order to meet the sustainable development requirements. In the present study traditional and environmental sustainable indices used in the Agios Dimitrios Power Plant, Northern Greece, are compared to those of ESKOM Company, South Africa, taken as reference. These indices are referred to, a) the solid fuels consumption, such as lignite, and, b) the emissions to the atmosphere, such as SO2, NO2 and dust. Last five years data show a remarkable improvement of all indices in the Agios Dimitrios Power Plant. Although the lignite used in this Power Plant is by far of poorer quality than that used by ESKOM - net calorific value 1272 and 4638 kcal/kg, respectively - dust emissions in both Power Plants are similar (52 and 31 g/kWh, respectively). The SO2 and NO2 emissions are very low in Agios Dimitrios compared to those of South Africa, respectively 1.92 and 7.91, and 1.74 and 3.61 g/kWh. This is mainly due to natural desulfurization (by the lignite?s calcium content) and the low NOx burners.

Jan 1, 2003

By A. Pavlides

The purpose of this study is to compare estimation methods for lignite reserves at the Amyndeo mine and to provide a map of the estimated thickness of the coal seams. The reserves are first estimated with the method of Voronoi diagrams, using a group of mirror points to close the polygons around the boundaries of the mine. The second estimation method is based on Ordinary Kriging using the Spartan variogram model. Finally, the reserves are estimated by the mean lignite thickness value of the drill-hole data 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. An interpolated kriging map of the total thickness variation is produced accompanied by a map of the kriging uncertainty.

Jan 1, 2008

By J. Andersen

The very large quantities of energy used for size reduction in the minerals processing industry necessitate the accurate prediction of comminution machine power draw for optimum plant design. The JKMRC has developed effective models for predicting ball mill, autogenous mill, semi- autogenous mill and crusher power draw. When combined with comminution models they provide a powerful tool for evaluating not only the size reduction performance of a plant design, but its power utilization efficiency as well. This paper describes the structure of the mill and crusher power models. Data from a wide range of equipment types are presented which illustrate the accuracy of these models.

Jan 1, 1992

By E. Topuz, M. J. McPherson, I. M. Konduri

This paper describes experiments conducted to evaluate the effectiveness of jet fans for ventilating blind headings in under- ground mines. A laboratory model of a mine heading was built by using dynamic similarity criteria, and water as the fluid medium. In order to verify laboratory test results, field experiments were designed and carried out in a full scale mine model and in a coal mine in West Virginia. Using CO, as the tracer gas and in combination with a computerized gas monitoring system, tests were conducted to evaluate jet fan performance. The results highlight the flexibility and versatility of jet fans for ventilating blind headings. Numerical modeling of a jet fan in a typical coal mine heading was carried out to evaluate the potential of computational fluid dynamics.

Jan 1, 1997

By William A. Kneller

A considerable range of composition exists in rocks that have been described as chert, jasper, or flint. Their composition may be opaline, chalcedonic, quartzose, or mixed. Certain cherts, when incorporated in concrete, are known to possess nondesirable thermal and chemical properties. The inability of chert to withstand thermal shock above the freezing temperature of water is an example of such a property. Cryothermal reactions may cause disintegration of concrete, due to repeated cycles of freeze and thaw. Thermal properties are significant because small temperature changes may cause inordinate expansion and resultant fissuring of concrete. Freezing of entrained water in chert may cause excessive physical failure in concrete. Some cherts react chemically with alkalies liberated during the hydration of the cement, with resultant cracking and deterioration. Sources of concrete aggregate in Ohio have been viewed with suspicion because they contain considerable chert derived from Middle Devonian and Pennsylvanian carbonate rocks. Light-colored porous cherts from the Middle-Devonian Colum- bus Limestone exhibit the least freeze-thaw durability of the samples studied. Denser cherts may also yield to freeze-thaw stresses, but tend to be more susceptible to thermal shock. Cherts rich in opaline and chalcedonic silica usually exhibit alkali-aggregate reactivity.

Jan 1, 1966