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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 Mahesh C. Jha, Frank J. Smit

Column flotation and selective agglomeration are promising advanced physical cleaning processes that can be developed for preparing premium quality coal-water slurry fuel from coal fines. Such a fuel could either replace oil or natural gas in certain industrial and utility boilers or else could be burned in advanced combustors currently under development. These applications require coal cleaned to sulfur and ash contents below 258 g/GJ and 430 - 860 g/GJ (0.6 lb/million Btu and 1 - 2 lb/million Btu), respectively, to meet clean air emission requirements. A highly loaded slurry must be produced in order to avoid derating the boilers, and the total cost of the fuel must be below $2.37/GJ ($2.50/million Btu) in order to penetrate the market by the turn of the century. Achieving these technical and economic goals depend critically on the selection of suitable feed coals. This paper describes the identification and evaluation of 18 coals and final selection of six coals from different regions of the United States as potential feedstock for preparation of premium fuel. The work is being performed under a cost-shared DOE project.

Jan 1, 1995

By Munson R. McKinney, Bryan A. Slim

To date some 1,000 exploration targets (by way of adits, mine dumps, shafts, outcrops and unstoped mine areas) have so far been identified using an interactive data base system to query a digital data base comprising topographic, cadastral geological and mine components developed as a compilation of old plans, records, surveys and recently flown aerial photography. The exploration targets are intended for early follow-up as part of a 1987 exploration programme to investigate the reserve potential of the former producing property located in southern Utah. Of further interest is the unscrambling of old mine plans to provide drill targets for investigation of unstoped reserves with one target being a possible 800,000 tons in part of the lower workings. The project site encompasses about 3,200 acres of mainly patented lode claims covering most of the claims and mines of the Gold Mountain mining district formed in 1889. Turn of the century mining saw several mines operating whose total production was at least 143,000 oz. gold and 460,000 oz. silver from steeply dipping veins up to 20 ft. or more in thickness.

Jan 1, 1987

By Ronald C. Bethard, Kenneth W. Ely

The liberation of methane during underground coal mining causes serious safety concerns. During a mining cycle, with mechanized mining equipment, thousands of cubic feet of methane are released from coal seams, discharged to return air courses, and vented to the atmosphere through mine fans. This has been the traditional way of removing the explosive hazards of methane gas from the mine. Through horizontal and vertical degasification techniques, this hazard can often be handled in an equally safe and much more profitable manner. Basically, degasification allows for the controlled reduction of inseam methane content of coal prior to its mining. It is the responsibility of mine management to evaluate these degasification programs and ensure that the program itself does not introduce some new risk to the mining process. The removal of methane gas from underground coal mines using horizontal and vertical degasification is a relatively new concept. Products and systems used in degasification continue to evolve. Site conditions vary also, so no one system or equipment can be said to be the safe answer for degasification in all situations. A constant process of cooperation and evaluation by mining and degasification management should result in a safer and more profitable mine.

Jan 1, 1989

By Gerald G. Griswold, James O. Greenslade, Cherie Tilley, Richard Reseigh

INTRODUCTION The Harrison Western Corporation, a leading Denver based mine contracting and engineering concern, is presently engaged in sinking two 1,006 m (3,300 ft) shafts for the Phillips Uranium Corporation at their Nose Rock Project, approximately 13 miles northeast of the small community of Crownpoint in McKinley County, New Mexico. The Nose Rock Project is the first attempt by the Phillips Uranium Corporation to tap the deep uranium reserves in what has become known as the Grants Mineral Belt. (See Figure 1) Project Description Phillips Uranium Corporation's plan for the large 2700 metric ton per day (2950 tons/day) mining facility calls for a series of deep access and ventilation shafts ranging from 4.27 m (14 ft) to 5.49 m (18 ft) in diameter to approximate depths of 1,006 m (3,300 ft). The initial pair of shafts consists of one production shaft and one ventilation shaft separated by a distance of 91 m (300 ft). The interbedded layers of sedimentary sandstones and shales to be penetrated by the shafts contain several major water producing aquifers, the deepest being the mineralized zone called the Westwater Canyon Member of the Morrison Formation.

Jan 1, 1981

By L. M. Chan, D. H. Carlson, J. H. Johnson

This paper discusses laboratory evaluation of a tailpipe emissions measurement apparatus (EMA) developed by Michigan Technological University (MTU) under contract to the Bureau of Mines. The apparatus dilutes diesel exhaust and measures the concentrations of diesel particulate matter (DPM), CO, C02, NO and NO2 at known dilution ratios. The EMA was evaluated by side-by-side comparison of its measurements with those by laboratory grade instruments. During the preliminary laboratory evaluation concentrations of DPM, CO and CO2 were measured. The concentrations of CO and CO2 measured by the EMA were usually within ±14 pct of laboratory-measured values for CO and ±20 pct for CO2. EMA DPM concentrations correlated well (r = 0.96) with the laboratory values, but were 29 pct lower on average. The CO and C02 differences were observed to be related to the method of calculating the EMAs' dilution ratio and the difference in DPM concentrations is attributed to thermophoretic and/or condensation losses related to the EMA's unheated sample probe. Preliminery analysis of data obtained with a heated sampling probe and modifications in the sampling procedures have indicated reduced variability in DPM and in the calculated dilution ratios.

Jan 1, 1991

By J. T. Sitarski, R. C. Emmett, L. W. Luinstra, R. P. Klepper

A mining operation in Zimbabwe produces a pyritic gold concentrate that requires oxidative pretreatment prior to cyanidation in order to liberate 80 percent of the gold values. Bio- oxidation offered the potential of increased gold recovery and was considered to be an economically advantageous alternative to the existing practice of roasting the concentrate. Based on bench- scale test work, a small bio-oxidation plant, capable of processing approximately 50 percent of the concentrator production, was installed at the mine to evaluate this approach. The plant included two 57 m3 bioreactors in series and the ancillary equipment needed to prepare the feed concentrate, to wash the leached residue prior to cyanidation, and to neutralize the waste liquor. The plant was operated for a year-and-a-half, and the conditions needed to achieve a 90 percent liberation of gold values were determined. A number of critical technical problems were encountered, and many were resolved on-site. Others have been addressed since the pilot plant was moth-balled in June 1988. Valuable insight was gained from the operation of the pilot plant, which has provided useful guidance for continued process and equipment improvement.

Jan 1, 1990

By Mostafa Benzaazoua, Bruno Bussière, Mukendi Kongolo

The desulphurization process has been proposed over the last few years for acid mine drainage control at certain mines, which generate low to medium grade sulphidic tailings (-3 to +25 wt% S). The environmental sulphur recovery, which means the sulphur to be floated to produce a non-acid generating final tailings, depends mainly on the intrinsic neutralizing potential of the tailings. However, in some cases the sulphur cleaning is complicated by other parameters which affect the flotation probability of the sulphide particles. In this study, a number of tests were conducted with a Hallimond tube and Denver Cell on both pure mineral and mine tailings. To develop a better understanding of the mechanisms of non-selective sulphide flotation, three types of approach were investigated in this work: (i) pure pyrite at progressive milling degrees, (ii) artificial mix of pyrite and quartz at different calibrated granulometry and (iii) same composition tailings with 26 % wt sulphur at progressive milling degrees. The effect of the granulometry on the sulphide flotation was demonstrated both. The results allow us to define a granulometry model, which can then be considered in the whole desulphurization modeling.

Jan 1, 2000

By T. M. Barton

This paper presents several case studies in which a mechanics-based boundary-element program is used to back-calculate the surface subsidence associated with various panels at several northern Appalachian coal mines. The program used in this case study is called LAMODEL, which incorporates a frictionless, laminated overburden into a general-purpose displacement-discontinuity code primarily designed for calculating the stresses and displacements in coal mines or other thin-seam or vein-type deposits. In this paper, the program is used to calculate both the underground convergence and the resulting surface subsidence at five longwall panels and a room-and-pillar section. The fitted subsidence from the model is compared with the field measurements and analyzed. The results from this work show that the LAMODEL program is not as accurate as available empirical subsidence-predictive methods; the expected correlation between the geology and the optimum input parameters is not evident. However, for a mechanics-based program, LAMODEL does provide moderately accurate subsidence calculations, and it is one of a few programs that can even attempt to practically calculate both underground stress and convergence and the resulting surface subsidence.

Jan 1, 2000

By John A. Ferguson

John Ferguson of Phelps Dodge provides us with a case study of how his company approaches its computing and hardware decisions. Senior management is the target audience for this contribution which discusses computer employment strategy at Phelps Dodge and how it may differ from the practices followed by other companies. The computer professional is well advised to read this subsection also to gain insight into the way in which management looks at computers in support of company operations. The following pages take us through a progression of developments and expectations brought about by the computer: the tremendous versatility of this new tool and its swift development; the widespread changes and problems it introduced; the new and revolutionary management theories it prompted and the widely supported centralized service concept it introduced to information processing. It continues with a discussion of Phelps Dodge's early experience, its ,operating environment, and its strategy development-attention to operating units and later headquarters with stress on service needs of users. It concludes that for computing to be effective it must fit in with the bay in which the company operates and must be sensitive to the needs of the people it serves.

Jan 1, 1979

By Kadri Dagdelen

Production scheduling of an open pit mine is one of the most important steps in open pit mine planning. The production schedule of a mine defines the distribution of cash flows and as a result directly influences the net present value and overall economic feasibility of a project. It is becoming more and more critical to obtain an exploitation schedule of a deposit such that highest possible returns are achieved from a project. As the mining industry mines lower and lower grade ores, production scheduling is becoming a key item which can make or break a project. Although the need to plan and operate a mine with an optimum production schedule has been obvious for some time, the methods used to obtain such a schedule have not been. There is not a single, mathematically proven, optimum mine production scheduling algorithm which is widely accepted and used today. In an attempt to determine a production schedule which is optimum, a new algorithm was developed. This algorithm, in theory, is based on the lagrangian concepts of mathematics and in practice is based on the parameterization concept of mining. This paper describes the fundamentals of this newly developed algorithm.

Jan 1, 1986

By A. C. Beaulieu

CITY OF EDMONTON Rate of Growth The City of Edmonton has been classed by some economists as being the most progressive City in Canada since the early 50's. The high rise buildings that are changing Edmonton's skyline, the rapidly expanding sewer and water network, and the proposed rapid transit system all indicate the requirements of an ever expanding City. Edmonton, the core of Canada's Energy Empire is the country's seventh largest metropolitan area. Bisected by the 22 mile long park of its magnificent river valley, it sits in the midst of the 50,000 sq miles of riches that have created it. Underneath the City, however, extending down for thousands of feet and encircling it for a radius of scores of miles, lies a fabulous store of petroleum wealth. By the early 1940's, based upon the needs of the farming areas, accompanied by some small exploitation of coal and timber, Edmonton grew to 100,000 people. Then in a short space of 20 years Edmonton shot up to be a city of 450,000. Figure 1 (Slide No. 1) indicates the population growth in the City of Edmonton and the Census Metropolitan Area from 1906 to 1971.

Jan 1, 1997

By B. A. Firth

Australia is the largest exporter of coking and thermal coal to the international market. This market has required that the coal being presented to the customer has a particular level and consistency of quality. In this context, the Australian industry has developed coal preparation practices that allow this criteria to be met while maximising the recovery of coal from the resource. This has required on- going developments in both coarse and fine coal cleaning technology over the past 30 years. Coal flotation has undergone a number of developments with regard to maximising recovery from the overall plant circuit. This includes innovative flotation circuits (split feed), methods of enhancing the use of reagents and control of pH. During the 1990s, there have been major changes in flotation as practised in Australian coal preparation plants. Columns have become the preferred technology for both greenfield developments and plant upgrades. This paper will outline the above developments with a number of plant examples and the reasoning that has driven the change. The ongoing research that is being carried out on new cells to optimise the overall fine coal circuit will also be discussed.

Jan 1, 1999

Along with kyanite and sillimanite, andalusite forms part of the sillimanite industrial minerals trimorphous alumina-silicate group. Theoretically, andalusite contains about 60% A1203 and 40% Si02, with a Mohs hardness of 7 to 7.5 and a specific gravity of 3.0-3.2. Andalusite generally occurs in the contact metamorphic zones of schists and shales, constituting about 10% of the ground mass ore body. The 5- to 20mm- (0.2- to 0.8-in.-) long crystals are usually liberated through crushing and magnetic/heavy-media separation. Relatively minor occurrences of andalusite are found in Andalusia, Spain (where it was first identified), Portugal, the former Soviet Union, Ghana, South Korea, California and North Carolina. It also occurs in China, France and South Africa. The latter two represent nearly all the andalusite that is exported. Andalusite is an inert refractory raw material that does not require calcining before use. It involves an internal conversion to mullite after heating to 1400° to 1600° C (2552° to 2912° F). At higher temperatures of about 1800° C (3272° F), the mullite converts to corundum and liquid silica.

Jan 1, 1995

By Donald W. Gentry

Mine valuation is a multifaceted, interdisciplinary process by which the economic viability of an old, existing, or new mining property or venture is determined. The problems associated with arriving at a representative and accurate value for a mining property are complex and numerous, and the procedures utilized in determining these values vary from simple, back-of-envelope calculations to sophisticated mathematical manipulations requiring computer modeling and analysis. Regardless of the complexity or the degree of sophistication associated with any particular project, the evaluation process must ultimately provide management with two basic types of information. First, the evaluation process should indicate whether or not the mining project is economically viable after careful consideration of all engineering, environmental, geologic, and other variables pertaining to the project. Second, the evaluation process should provide management in- formation on the relative attractiveness of the project when compared to other alternatives. In some cases, it may be extremely difficult to supply this information for a project directly. Nonetheless, the evaluation process should and must present all information necessary in a format which can be incorporated into the decision-making process as expeditiously as possible.

Jan 1, 1979

By H. Lind

Mining in Estonian oil shale deposit mainly takes place in the Ordovician, Keila-Kukruse aquifer. The aquifer is affected by mining and is fully dried out around the working mine areas (Perens and Savitski, 2008). The groundwater level is decreased down to 30 m, to the mine floor elevation using about 30 pumping stations (Lind, 2005). The pumping rate is very high - depending on the season, ranging from 10 up to 40 m3 per ton of produced oil shale (Reinsalu et al., 2006). The Estonian oil Shale Company mined 15.5 million tons of oil shale in 2007 (Source: Estonian Oil Shale Company). In order to predict the effects, and avoid the social and environmental impacts, there is a need to continuously monitor the situation and run software simulations aiming at decreasing the pumping rate. This becomes even more important since the environmental taxes on usage of groundwater resources increase every year. Therefore, it is necessary to monitor groundwater level and quality, and develop a groundwater model for the overview of the situation during mine operations and also for a number of years after mine closure.

Jan 1, 2008

By E. A. Metz

It has been approximately four years since the International Agency for Research on Cancer (IARC) reclassified crystalline silica as a "group one" substance. Since then, crystalline silica has been considered a human carcinogen. Silicosis is a preventable disease, and several aggressive campaigns have been developed to increase awareness of silica-dust-related problems in the industrial environment. New analytical techniques are now being developed to determine quantitatively the amount of crystalline silica in materials. Yet, still much is to be learned about the surface properties of silica and the way in which the disease progresses into full-blown silicosis. This paper discusses the interaction of free radicals generated by the mineral particles and lung tissue. It is the cell injury and DNA damage that progresses to fibrogenesis. Freshly fractured surfaces of silica contain free radicals. These free radicals play an important role in the stimulation of the alveolar macrophage and the development of the inflammatory reactions leading to the fibrotic response caused by silica. Engineers, scientists and physicians need to discuss the mineralogy of silica and the technical issues concerning the development of silicosis.

Jan 1, 2000

By Donald A. Brobst

The minerals barite (BaSO, -barium sulfate) and witherite (BaCO, -barium carbonate) are the chief commercial sources of the element barium and its compounds, whose many uses are nearly hidden among the technical complexities of modem industrial processes and products. Barite, the major ore mineral, is extremely vital to the petroleum industry, which in 1990 consumed about 90% of the world's production of 4.9 Mt as a major ingredient of the heavy fluid called mud that is circulated in rotary drilling of oil and gas wells. The remaining 10% of the barite production was consumed chiefly in the manufacture of barium chemicals and glass and as a pigment, filler, and extender. Barite is found throughout much of the world and is available from three major geologic types of deposits-vein and cavity-filling, residual, and bedded-in sufficient quantity at competitive prices to meet current demands. The world's demand for barite is expected to increase because of the world's need for oil and gas. Geologic circumstances are favorable for the discovery of new deposits of commercial value. Witherite, desirable as a raw material for the production of barium chemicals, is much less common and abundant than barite.

Jan 1, 1994

By I. Kapageridis

The mining industry worldwide has recognized in the past the need to apply specific rules and guidelines in the reporting of mineral resources and reserves. The high financial investment and risk associated with any mining project and the ever stricter environmental and social controls were the forces behind this recognition. For years the industry experienced the development and enforcement of several codes for reporting accepted by different countries. The implementation of any code can be a confusing task as the guidelines are sometimes general and open to different interpretation. The use of computers in the estimation and reporting of mineral resources and reserves is necessary, particularly when trying to implement particular code guidelines. This paper discusses ways to implement a reporting code in a computerised resource/re-serve estimation study. The implementation is demonstrated using a gold deposit project as an example. The effects of mining, metallurgical, economic, marketing, legal, environmental, social and governmental factors are taken into consideration. This paper also discusses well established reporting codes and the possibility of reaching a single, universally applied code that could be used by Greek mining companies.

Jan 1, 2007

By Gealy W. Wallwork

The administrative processes of coal mines are becoming increasingly complex. As society evolves into a more complicated structure with greater emphasis on individuality, government regulations reach deeply into every activity in an effort to force individuals into a standardized mold. These contradictory pressures add an extra burden to the administration of a mining operation. Recent years have brought a substantial change in the skills needed by mine supervisors and managers. As a result, a better understanding of the administrative functions is necessary. The mine superintendent has the overall responsibility for the mine; for effective operation he must be sufficiently knowledgeable to oversee all the complex functions that make up the mine. This chapter does not cover all the administrative requirements because of the variation in mine operation and in company policies and organizational structure. It does attempt to identify the administrative functions that would be required at a large mine with a preparation plant. It is assumed that the mine operation is decentralized with very little duplication of functions at the organizational levels above the mine. Thus each function is assumed to be relatively complete at the mine and under the general supervision of the mine superintendent.

Jan 1, 1981