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By Ralph J. Holmes

INTRODUCTION Although sampling techniques used by the mineral industry continue to improve, sampling is still an area which is often neglected. Frequently, sampling and sample preparation requirements are left to personnel who do not fully appreciate the significance and importance of sampling. Consequently, plant evaluations are often based on seriously biased samples, leading to mass balance problems and incorrect assessments of plant performance. The basic rule for correct sampling is that each particle of ore or concentrate must have an equal probability of being collected and becoming part of the final sample for analysis. If this is not the case, bias is easily introduced and the sample is not representative. For example, when ore is travelling on a conveyor belt, the lumps may come to the surface. Consequently, a grab sample taken from the top layers only will contain a greater proportion of lumps, i.e., the sample is biased. There seems little point in making major investments in precise analytical equipment, if the sample provided to the analytical laboratory is not representative in the first place. This paper describes the sources of plant sampling errors, reviews the methods of estimating their variance, presents some worked examples, and provides some practical advice for reducing sampling errors and their variance. SAMPLING BASICS It is generally accepted that the discharge point of an ore or concentrate stream is the most suitable sampling location. The stream can be intersected at regular intervals, and representative samples, referred to as increments, can be obtained by taking a complete cross-section of the ore stream. On the other hand, sampling devices that take part of the stream on an intermittent or continuous basis, e.g., a bleed from a pipe, may introduce serious bias, and should be avoided at all cost. Increments may be taken at completely random times or tonnages during the sampling operation, in which case it is called "random sampling". However, as shown below, random sampling results in the largest sampling variance, so it is preferable to divide the ore or concentrate stream up into strata of equal time or mass and take one increment from each stratum. This operation is called stratified sampling and may be either systematic sampling, in which increments are taken at the same point in each stratum, or stratified random sampling in which the increments are taken at random within each stratum. Systematic sampling results in the smallest sampling variance, provided periodic variations in quality or quantity are not present which may coincide with, or approximate to, any multiples of the proposed sampling interval. In such cases, it is strongly recommended that stratified random sampling within fixed time or mass intervals be carried out.

Jan 1, 1991

By P. K. Mululi, T. M. Yegulalp

The number and type of trucks and shovels used are two important factors in determining the optimal design parameters of an open-pit mining system. The characteristics of the arrival and service-time distributions of the trucks determine the performance measures of a truck-shovel system when it is modeled as a closed queuing network. In all of the previous analytical queuing studies of truck-shovel systems, trucks are assumed to be identical with respect to their arrival and service-time distributions. This assumption, although desirable for reducing computational difficulties, causes either underestimation or overestimation of the performance measures, depending on the number and types of equipment used in the model. The relative error in performance measures could be significant when the number of different types of trucks and shovels is large. In this paper, an analytical method is proposed to model the truck-shovel system as a multiple-class closed queuing network. This approach provides the capability of estimating system performance measures for planning purposes when the truck fleet is not necessarily composed of identical trucks. An example of truck-shovel systems is presented to show how the incorporation of different types of trucks affects performance measures.

Jan 1, 1998

By Robert C. Freas

Over the past twenty years people throughout the world, but particularly in the United States, have been taking an increasing interest in the environment, sources and causes of pollution, and pollution abatement. Air quality in the United States has been and continues to be an area of primary emphasis. In 1970, the US Congress passed the Clean Air Act and subsequently revised and strengthened it in 1977 with the issuance of the New Source Performance Standards. The Act has been further strengthened with the passage of the 1990 Amendments. By far the largest single source of sulfur dioxide (SO,) pollutants are coal fued electric generating power stations. Hence, a substantial portion of the flue gas desulfurization (FGD) research and equipment installation has been geared to the utility industry. Several competing FGD technologies were touted during the period 1970 to 1990 with varying degrees of success. Subsequently, the more successful technologies have been accepted, revised, and improved to the point that by 1991 third and fourth generation technology is available. A second area of emphasis for FGD has been coal fired industrial boilers. While individually they are much smaller than any electric utility generating station, they do represent a significant source of sulfur pollution. However, due to the size of industrial boilers and their location within industrial and educational complexes, the wet scrubber technology being employed by the utilities is not appropriate for these applications. Hence, fluidized bed combustion (FBC) technology has been developed for the industrial boilers. Since the installation of the first full scale test unit at Georgetown University, several equipment vendors have come forward with an increasing array of more sophisticated FBC units. Currently, FBC technology has matured to the point that the Tennessee Valley Authority (TVA), in cooperation with the Electric Power Research Institute (EPRI), has installed an FBC system on a 250 MW test unit at the Shawnee Power Station in Kentucky.

Jan 1, 1994

By Anna Marabini

This paper provides a summary of the studies performed over a period of more than fifteen years by the Italian National Research Council's Mineral Processing Institute in Rome to develop applications for the use of chelating reagents in the flotation of metallic minerals. A description is given of the various phases through which the studied progressed, starting with the combined use of commercial chelating reagents and a neutral oil and then moving on to the synthesis of new long-chain chelate collectors for the flotation of sulphide and oxidized Pb, Zn and Cu minerals. After a series of preliminary tests which confirmed the possibility of floating various metallic minerals with commercial reagents containing chelating groups exerting specific action on given cations, the studies were addressed to the development of a theoretical method of choosing chelating groups that exert selective action on one metallic mineral rather than others. The theoretical approach was based on thermodynamic data concerning the chemical equilibria in solution. The validity of the method has been proved in numerous cases by flotation tests on pure minerals. Subsequently the research was directed towards the design and synthesis of reagents with a mixed aliphatic-aromatic structure containing chelating groups for Pb and Zn and an alcoxyl chain of various length, position and configuration. The flotation results obtained on oxidized and mixed Zn-Pb ores provided interesting pointers for designing the nonpolar portion. The structural criteria identified via these studies were interpreted on the basis of chemical and steric considerations. A description is given of a new synthetic chelate collector which is effective in the selective flotation of Cu minerals from complex sulphides. The fact that this reagents is more selective than xanthate is demonstrated by comparative flotation tests on actual ores.

Jan 1, 1994

By D. W. Niosi

In this chapter, a review is made of the various stages of an exploration program, mineral rights acquisition methods and the partners involved in an agreement, the after- tax cash flow approach using present value discounting principles, the establishment of computerized financial models for assistance during the negotiating stages for a mineral property, and the various evaluation techniques and their specific applications during different phases of an exploration program. A set of examples is shown encompassing the initial target-seeking stages to the ultimate feasibility study stage.

Jan 1, 1979

By B. Farshadi, B. Asi, M. J. Habibian

"In this paper, the most significant environmental aspects that are identified in the Taft Copper Project (TCP) are the quality and quantity of water, pollution of the existing watercourses and post-mining land use, matters such as air and noise pollution are deemed to be of less significance. Analysis has been performed for Do Nothing Alternative, Pre-stripping Phase, Mining Phase, Closure and After-use Phases. Analysis of the environmental assessment of TCP was carried out in three stages. In the first stage, the general negative and positive aspects of the project were identified. In the second stage the intensity, magnitude and significance of the environmental impacts of the project were identified. The third stage is related to the final conclusions of the assessment team and the relevant reasoning. A modified Leopold Matrix was adopted for evaluating the significance and magnitude of the environmental impacts. For this project, the matrix was modified to allow the assessor to take account of negative and positive numbers."

Jan 1, 2011

By P. A. Anderson

Innovative solution management is being used at Coeur-Rochester, Inc. to increase bullion production and decrease overall costs. New operating programs call for reduced solution application rates to the heap to increase pregnant stream values at a lower and less costly plant flowrate because silver and gold extractions are equal regardless of leach solution application rate. Solar heating is used in the summer months to increase the core temperature of the heap for use in the winter months thus increasing silver extraction rate. This paper outlines the programs now in effect and the savings incurred because of them.

Jan 1, 1989

By K. E. Doud

An unusually pure grade of rutile and several grades of aplite rock are produced in a unique mining and mineral dressing operation in Hanover County, Virginia. The ore body is an aplite rock of gnessic structure, having a sari ace exposure extending over several hundred acres, heavily leathered and containing rutile, ilmenite, and other titanium and iron minerals. The physical nature and mineral composition of the ore body has permitted the use of a relatively economical and unusual processing circuit. The flowsheet was designed to take full advantage of the remarkable liberation of the minerals at relatively coarse rinds. It permits flexibility in changing the product mix, and maintains high levels of purity in both rutile and aplite rack. The mineral processing is discussed in some detail below.

Jan 1, 1962

By H. P. van Ormer

The objective of this paper and the developed personal computer program is not to identify or try to identify the actual total drilling cost in any Rotary Drilled Blast Bole Program. The ideas put forth here and in the computer program developed are a very accurate way to measure what is often very hard to identify and interpret -The actual direct operating cost of various drilling package combinations including comparing with available blast hole sizes and patterns

Jan 1, 1988

By T. P. Meloy

The packed column flotation cell is an awesome separation device. Virtually unknown and untested, the packed column flotation cell is one of the ten most important developments in mineral processing of the 21st century. Though experimental and industrial data is limited, it is clear that the packed column flotation cell is two to three orders of magnitude better than the conventional flotation cell and one to one and a half orders of magnitude better than the open column flotation cell. With the modern packing taking up less than one percent of the packed column, column blocking does not occur. For a packed column operating 24 hours a day, 365 days a year, the estimated mean time between failures (MTBF) is one hundred thousand hours or roughly twelve years. With no moving parts, lower maintenance costs, lower power consumption and inherent operating stability, the packed column is a powerful separating machine. Because there is little meaningful data for comparing the packed column to the conventional flotation cell and the open column flotation cell, much of the material presented in this paper are guesstimates. They are disinterested guesstimate made by the authors after extensive theoretical work and reviewing the known facts. In the authors' opinion, no available data contradicts the guesstimate. The authors expect that there may be errors as large as three hundred percent. Even three hundred percent errors will not change the conclusions of this paper. The packed column flotation cell is a formidable separating device. To understand the problems of comparing the three types of flotation cells, consider the fact that the three cells may have different modes of separation. One of the authors, Meloy, believes that in the conventional cell, the primary particle separation takes place in the liquor with secondary separation taking place in the froth, while for open column flotation, all the separation takes place in the froth. However, he believes that in the packed column a large part of the separation may take place on the walls of the packing. If this is true, not only is the method of modeling each type of cell different, but the method of particle selection in the cell is different. This means that one type of cell may be better at differentiating between two different types of particles. There is a growing body of literature on open and packed column flotation. Suggested reading: (Clarke et al; Hucko et al; Li; Smith & Warren; and Yang).

Jan 1, 1994

By J. Wes Blakely

In the mid-1950s the importation of foreign oil began to encroach on traditional coal markets such as railroad steam engine fuel, home heating, electrical generating plants, and others. Many of the smaller coal companies with substantial coal reserves subsequently found that they could no longer continue to mine economically and merged in various ways with larger established coal mining concerns. As the seats of top management and authority were removed from the mines to large metro centers such as New York, Pittsburgh, and Chicago, the more personal relationship between mine workers and management that had existed prior to these mergers began to be eroded and replaced by " remote control " mine management. The disappearance of this face-to-face contact of upper management with mine employees tended to create barriers blocking simple effective communications between coal mine management and labor. In examining the human relations aspects of the coal mining industry, many elements, some concerned with work and others not, have depicted the industry as almost devoid of good applied human relations and communications practices, and, in truth, little has been done to alleviate this situation. In past years many coal producing companies, with the exception of one of the largest, failed to adequately define the term "communications" as it applied to their companies, whether internally or externally. Internally many still place heavy reliance on written communications such as company-wide newspapers to do the job of communicating with their employees which they feel ought to be done. One company puts an inordinate belief in its company "newspaper" as the primary instrument to stimulate its work force into increasing productivity. Primarily aimed at the workers, who greatly outnumber the salaried administrative people, this publication mainly documents the fortunes of individual mine workers who are felt to have achieved something with their lives, e.g., a mine worker who had managed to put four children through universities, the philosophy behind this being to inspire other workers to achieve worth- while goals.

Jan 1, 1981

By P. Worley

With Utah Power & Light Mining Division's commitment to operate the safest and most productive mines possible, a decision was made to purchase and install mine-wide monitoring systems for use in the mines. After review of several different systems the Conspec Senturion 200 system was chosen. Three separate systems were ordered to fulfill the monitoring requirements of the six mines in operation: one system for the Deer Creek Mine one for the Wilberg/Cottonwood complex, and one for the Deseret, Beehive and Little Dove complex.

Jan 1, 1989

By Doug Brown

The recent expansion of our cities into hilly areas, particularly on the Pacific Coast, has resulted in damage or destruction of many homes due to geological problems such as landslides, soil creep, erosion, subsidence, or groundwater seepage. In southern California, landslides are the principal cause of damage and attention is focused on them. Landslides have occurred due to the reactivation of old slide masses, or have been caused by grading and increased water, infiltration resulting from development.. Reactivation of a portion of the ancient Portuguese Bend landslide in Palos Verdes, Los Angeles County, affected approximately 150 homes. A common type of new failure' occurs when grading has undercut bedding or other essentially planar surfaces so that they dip unsupported out of slope. Other slides have occurred due to the inherent weakness of the material involved. Preventive measures undertaken to eliminate damage in the southern California area have. included areal geologic mapping programs-in-advance of development, enacting or strengthening grading codes, and requiring extensive studies by consulting geologists and soils engineers both during the design stage and during construction. In the design stage, proposed cuts are frequently flattened, lowered or reorientated. Frequently, due to the high cost of land, they are supported by compacted fill buttresses. As a result of these measures, the geologic environment has a major effect on the feasibility, design, and development of, a very substantial percentage of tracts or individual homes.

Jan 1, 1967

By Dwight R. Coles

The solving of complex metallurgical flowsheet calculations by hand is, at best, a tedious job which often proves that engineers, too, make mistakes. The high cost and long lead time associated with manual flowsheet solutions have led several organizations involved in research, development and construction of extractive metallurgical processes to search for computerized systems which will solve flowsheet calculations. Although design flowsheet programs have been developed by the chemical industry, the ability to solve flowsheets involving particulate solids is usually overlooked. A new computer applications system has been developed at Fluor Mining and Metals which has been designed to accommodate the type of design flowsheets required by the minerals industry. By employing the sequential modular computation technique, a library of metallurgical pro- cessing routines may' be accumulated which are used by a universal executive system. This technique enables rapid solution of new process) .flow- sheets with only a minimum of additional programming effort. The implementation of the FLEXMET flowsheet solution system is the subject of this paper. Some of the major features of the system which are examined include interactive input data handling, automated flowsheet calculation order arrangement, flexible accomodation of unit operations models and advanced management of recycle and specification control calculations.

Jan 1, 1982

By R. L. Grayson

The Office for Mine Safety and Health Research, National Institute for Occupational Safety and Health is responsible for providing research leadership in the prevention of mining work-related illness, injury and death. Planning of the NIOSH FY99 research program focused on the comprehensive collection and risk analysis of fatality, injury and illness data according to commodity and mine type. This data, coupled with the mapping of information obtained from stakeholder meetings over several years, provided the basis for prioritizing research needs. Results of the combined analysis were compared to the FY98 program to identify surveillance and research gap areas. The FY98 research program was then assessed according to commodity and mine type and compared with exposure assessments, traumatic fatality rates, injury rates and employment trends in each commodity-mine type combination to gain insight into the potential balance of the future research program. This paper presents the methods, data and results of this planning process.

Jan 1, 2002

By S. Polegeg

The basic principle of this separation method was already defined in the middle of the nineteenth century. However, a change over for the treatment of minerals has followed from the construction of proper machines i.e. airjigs and airtables as late as in the twenties and thirties of this century. The main application of this technology was subsequently found in coal processing and reached quite a great dimension in the two following decades. The number of applications of this method in mineral dressing plants decreased rapidly and has almost vanished in the fifties in favour of wet concentration procedures. It has been for a long period as long as up to the eighties that no more consideration was taken for applying dry gravity separation in the field of mineral processing also due to the successful introduction of flotation. Due to the fact that labour cost was increasing remarkably within the past period after the end of World War II also the economic conditions in the agricultural sector became more though. As a result there came up a great demand for harvesting machines. Since agricultural products can only be processed by dry methods in a prevailing number, highly developed machines were introduced for the dry processing of food and feed stuff.

Jan 1, 1992

By E. D. Thompson, Y. J. Zhang, K. F. Unrug

This paper presents the results of a recent study on the development of an in situ testing method for determining coal strength in mine pillars. The strength testing is performed in the horizontal holes drilled into the coal rib using a penetrometer, which is an hydraulically powered device that uses an indenter to press on the surface of the borehole until the load reaches the failure point of the coal. The pressure and the penetration of the loading pin are recorded by a data-acquisition unit. The results collected from several coal mines indicate that this testing method is ideally suited for the realistic coal strength measurements. The new testing system not only improves the accuracy of the pillar-strength determination, but it is more cost efficient than the conventional method.

Jan 1, 1997

By F. C. Turin, T. L. Friend, A. G. Mayton, J. S. Jaspal, W. J. Wiehagen

This paper describes the serious injuries that have occurred to bulldozer operators working at domestic coal, metal and nonmetal mines in the United States. A serious injury is defined as one that results in either a fatality or in lost work time. Examined were 873 injury records compiled by the Mine Safety and Health Administration (MSHA). The time period covered was 1988 through 1997. These injuries resulted in 18 fatalities and 31,866 lost work days. All of these injuries occurred to dozer operators while they were performing common production tasks. An injury classification system was developed to code the narrative information that describes the circumstances surrounding the injuries. Jolts and jars accounted, for 604 or 70% of the serious injuries to bulldozer operators, and jolts and jars accounted for 75% of the workdays lost. Vertical jars comprised the largest set (354 incidents) of jolting and jarring injuries. In more than half of these incidents, the operator was backing up the dozer. Working near an edge carries significant risk for fatal injuries. Of 116 incidents where the dozer fell over an edge, rolled over or fell into a hidden void, 14 (12%) resulted in fatal injuries. In cases where the dozer operator either jumped or was thrown out of the cab in a fallover or rollover, seven out of 17 of the operators were killed. This study finds that further reductions in injury risk would require more widespread use of seat belts; consideration (and maintenance) of the seat and seat suspension systems that might reduce injury risk from jolts and jars; research interventions to assess the effect of alternative engineering designs to dampen or isolate the effects of shock and vibration; and continued attention to skilled performance, i.e., the integration of hazard awareness, recognition and response with dozer operational skills.

Jan 1, 2003

By Russell W. Hunt

The cave man of ages past took his wife-and family from the cave pointing to a fire he had built and beating on his breast said, "Look what I have done". Today man is taking his family back to a cave saying, "Come enter in because of what I have done". At the close of World War II Germany said if they had gone underground one year earlier with more of their operations, the war could have lasted four years longer with perhaps much of Britain devastated. The protection of the home front no longer rests with the soldier in actual combat. The battle will be won at home with the most careful kind of protection against missiles. After Nagasaki-Hiroshima Sir Winston Churchill said in substance "Up to now the Almighty has mercifully withheld from man the knowledge of these terrible weapons of destruction."

Jan 1, 1959

By Andrew Burton, Damian Schofield, Jeremy Noond

This paper will introduce and discuss a range of techniques that utilise new developments in Computer Graphics (CG) and Virtual Reality (VR) for the investigation of incidents and accidents in mining environments. The future of mining safety may not be totally led by the demands of the mine operators, but sometimes by the academics, commercial software developers and legal pioneers who generate new ideas and products and set admissibility precedents which may change the way certain traditional investigative operations are performed. In any accident investigation the outcome from the investigating team is often a complex affair and the results of the investigation are often reported in large, convoluted documents. Computer-generated forensic reconstructions allow investigators to present accident scenarios in an accessible and easily understood, visual manner. Surveys in the US have also shown that people have increased recall of computer-generated images over many other forms of evidence. The AIMS Research Unit in the UK have been pioneering the use of Computer Graphics (CG) and Virtual Reality (VR) technology for both industrial and road traffic accident reconstruction. This paper and accompanying presentation will contain examples of forensic reconstructions developed by the authors that explain some of the methodologies used to ensure admissibility of this type of digital evidence. The paper will contain a number of case studies based on UK and International industrial accidents. The paper will focus on how AIMS Research is extending the capabilities of the accident reconstructions created to take advantage of the latest developments in VR technology. As digital technology makes its impact within professional and commercial fields, computer generated forensic reconstructions will form important admissible evidence in the courtrooms of the future. The technology will also make a great impact in the way we train our workforces, with highly visual three-dimensional (3D) interactive training tools becoming the norm. Acceptance by the public, courts and workforce is an important issue, and implementation strategies must be considered carefully.

Jan 1, 2002