Search Documents

Machine breakdowns and maintenance delays are large contributors to lost production and increased operating costs in the mining industry. The US Bureau of Mines is investigating the applications of expert system technology to diagnostic and predictive maintenance for mining equipment. This will help increase mining productivity and decrease operating costs by reducing the frequency of equipment failures and repair times. The Bureau has begun this effort by applying expert system techniques to the diagnosis of hydraulic system problems on a continuous mining machine. This paper discusses the development of the hydraulic diagnostic expert system.

Jan 1, 1992

By W. P. Stroud, R. S. Dennen

A ground penetrating synthetic pulse radar system has been used by the US Bureau of Mines to probe into a coal pillar to locate hidden structures or anomalies. Direct matrix inversion was used to obtain a velocity image of the interior of the pillar. The reconstructed image showed the existence and location of a relatively low velocity material within the pillar. Core samples were taken from the pillar in a region surrounding the low velocity material. Analysis of the cores showed the presence of a clay vein coinciding with the low velocity material imaged in the tomogram.

Jan 1, 1992

By M. Ghiani, R. Ciccu

After a short review of the basic concepts underlying the application of selective flotation and electrostatic separation to the beneficiation of phosphate ores, the paper deals with the results obtained with these two technologies for a number of run-of-mine ores of different origin and distinct mineropetrographic features. Problems are discussed in the light of the minero-petrographic characteristics of the ores.

Jan 1, 1993

By S. B. Bhagwat

Equipment capacities of a sample of Illinois surface coal mines representing about 60% of surface production in the state were studied. Available equipment capacity was compared with the required capacity, as indicated by coal production and stripping ratios reported. Most mines sampled showed surplus equipment capacity, which if avoided, would result in substantial cost savings. The surplus capacity results mostly from market fluctuations that result in underutilization of equipment. Study findings underline the importance of market assessment at the time of mine planning and of communication between marketing and engineering arms of a coal firm.

Jan 1, 1987

By Richard K. Thorpe, Francois E. Heuze

The concept of a reusable underground nuclear test facility, named HEDEF, has been under study for some time. This rock chamber would have to be engineered to sustain the repeated mechanical and thermal shocks of internal explosions. In this paper, we summarize preconceptual studies performed in support of HEDEF, including -simple dynamic calculations for internally loaded tunnels, -outline of proof-of-concept tests of proposed reinforcement, - and initial dynamic testing of reinforcement components in an underground high explosive (HE) test.

Jan 1, 1986

By P. Bevilacqua, M. C. Williams, T. P. Meloy

We will bet you that, without prior programming within 10 minutes, we can design and simulate a 10,000 unit operation separation circuit. We will even do it at your place. We do it all the time. [ ] There are no tricks; we do it in a spreadsheet. We do it in those user friendly spreadsheet such as Quattro Pro. Spreadsheets must be user friendly. Accountants use them as do managers, business men, lawyers, doctors and salesmen. What these users seldom realize, is how powerful a mathematical tool a spreadsheet is. Among their other capabilities, spreadsheets can do a finite element analysis. That is why they are useful for accounting. That is also why they are more useful to engineers in the mineral industry. Spreadsheets are ideally suited for the engineering problems in the mineral industry. We have used then for solving problems in: a) mine ventilation; b) circuit design and optimization of dense media, flotation and sizing; c) comminution circuit design; d) shaking tables; e) Humphrey spirals; f) sluice ways and channel flow; g) lock particle and liberation problems; h) tunnel and shaft stress problems; i) cascadograph simulation; j) complex heat transfer problems; k) flow in porous media; and sheet flotation (Figure 1). Mineral industry problems presented on or with a spreadsheet are an excellent teaching instrument, problem statement and solution tools and sales devices. Spreadsheets answer easily, quickly and reliably many mineral industry engineering problems. What makes spreadsheets so useful to the mineral industry. The short answer is: they are easy to use; mineral industry problems fit the spreadsheet format. Those reasons are part of the answer. The real answer lies with the structure of the spreadsheet itself. Essentially, a spreadsheet is a "finite element analysis" form of computer software. Many mineral industry problems are readily solved by finite element analysis techniques. While some in the mineral industry may think they have never heard of finite element analysis, most use it weekly if not daily. Any profit and loss statement is essentially a finite element instrument. In fact, any array of numbers where one number is related to another may be construed as a finite element analysis product. Finite element analysis is a common daily activity. To get an appreciation of a finite element analysis, think of a monthly sales forecast for the next year. For each product and for each month, there exists a dollar figure for the forecasted amount of sales. In the forecast statement, for a given product in a given month, there is a "box" where the forecasted figure is presented. The forecast figure in that box was arrived at through some type of formula. The formula probably required some information from other neighboring boxes in the master forecast statement. Voila, one has a finite element analysis. Today the analysis would be done in a spreadsheet. A typical mineral industry problem is ventilation in an underground mine. Think of a rectangular room and pillar mining operation. Each room has air entering at a given pressure and velocity and air leaving at another pressure and velocity. During steady state, the air entering and leaving the room is determined by conditions in the adjacent rooms. One can readily model the room and pillar mine layout in a spreadsheet, and then find the flow in and out of each room at steady state. Change the flow by moving a brattice cloth or blocking off a path way and one gets a new air flow profile. Change the numbers on the spreadsheet that reflect

Jan 1, 1993

By R. R. Klimpel

The efficiencies of plant-scale comminution processes are often evaluated by various indices calculated and/or measured somewhat independently of the performance of any associated downstream froth flotation processes. To compare specific comminution factors, such as energy utilization, media consumption and equipment utilization time, comparisons of comminution efficiency independent of flotation behavior are appropriate. However, as increasingly detailed plant-level information is gathered on the joint and highly interactive nature of comminution and froth flotation, it is becoming even more obvious that knowing and using simple efficiency indices are not enough. What is needed are more performance-related measures of the efficiencies of the combined size reduction froth flotation system for effective plant-level economic optimization to occur. The purpose of this paper is to present examples of some of the important interactions that influence the joint efficiencies of size reduction and froth flotation processes.

Jan 1, 1999

By R. H. Moore, B. D. Breitenstein

INTRODUCTION The United States Uranium Registry (USUR) tissue program was funded in 1978 by the United States Department of Energy (DOE) through its Human Health and Assessments Division, and registrant enrollment began in 1980. It is operated by Hanford Environmental Health Foundation (HERF), Richland, Washington, with support provided by Pacific Northwest Laboratory (PNL).** The USUR tissue program is the first systematic effort to contact and gain assistance of workers occupationally exposed to uranium and to seek and study uranium deposition in human tissue. This paper describes the program objectives, populations selected for study, procedures for enrolling workers in the program, types of tissue to be studied, and analytical procedures to be used. PROGRAM OBJECTIVES The objectives of the USUR tissue program are to: 1) Determine the distribution and concentration of uranium, if any, in the tissues of occupationally exposed workers. 2) Compare bioassay measurements of exposed individuals with the results of analyses of tissues obtained at autopsy. 3) Seek evidence of histopathologic changes related to any uranium deposition that may be present. 4) Conduct analyses of whole bodies, when available, to obtain more precise data on the uranium burdens, if any, in the body and organs, and especially the distribution in parts of the body, such as the skeleton, that are not usually accessible for sampling. 5) Develop data that will assist in evaluating a) the accuracy of current in-vivo measurement techniques, b) the propriety of existing regulations, and c) the adequacy of current protection programs. SELECTION OF POPULATIONS FOR STUDY Selection of the populations for the USUR tissue program was based on studies of the United States Uranium Registry described elsewhere (0c81). Potential populations for study were quite varied because of occupational exposure to different chemical forms of uranium, different levels and eras of exposure, varying ability to identify populations exposed in the past, and the general interest and cooperativeness of the populations. Nevertheless, certain identifiable populations emerged that were both willing to participate in the study and likely to provide useful information. Among the targeted populations are individuals who were exposed to uranium prior to the existence of modern exposure standards. These individuals are presently being enrolled by the USUR. The reliability of concentration and distribution data and the demonstration of effects are more likely in such individuals than in those who have received less exposure. However, the targeted groups also include individuals who Have been exposed to permissible levels of uranium, and reference employees in uranium plants who have not worked with uranium. The lesser exposures are of immediate interest because of the rarity of heavy exposures under current standards. The sampling of potentially exposed individuals with negative in-vivo measurement results may serve to check the adequacy of in-vivo measurements in the detection of deposition. [ENROLLMENT PROCEDURE] The enrollment of participants follows three patterns. 1) Presently employed workers are enrolled by the cooperative efforts of USUR staff with the medical, industrial relations, and/or health physics personnel of the uranium facility. Volunteers may be enrolled by medical personnel at the time of their physical examination or by health physics personnel at the time of a bioassay or lung counting procedure. Follow-up after initial contacts with currently employed uranium workers is carried out by on-site personnel, but subsequent follow-up is the responsibility of the Registry. 2) Retired workers are contacted by mail, with a covering letter from their former employer supporting the principles of the study but leaving participation in the program on an entirely voluntary basis. 3) An alternate method of enrollment is to obtain a USUR autopsy consent after death from the next of kin. As part of enrollment in the program, permission is requested for access to the individual's medical and exposure data, and a short occupational history is filled out. The autopsy permission agreement signed by the individual is for an initial period of 5 years; the USUR ordinarily seeks renewal of the agreement upon its expiration. While this agreement provides

Jan 1, 1981

By J. Cheung, H. Rabia

The traditional methods for predicting mine air temperatures are based on steady state heat transfer models as developed by Voss (1969) and Starfield (1983). These models are useful in providing approximate predictions of air temperatures in trunk and gate roadways. More complex models are required to provide predictions along faces. In practice, the heat flow in underground mines is of transient nature and recent observations in some British Coal mines show temperature variations of up to 5°C during a working week at any one point. In addition, the recent introduction of district recirculation of mine air in British mines requires a more precise prediction of air temperatures during start up of the system or during breakdown. A transient heat transfer theory based on the work of Jordon is presented. The method lends itself easily to computers due to the large number of calculations involved. The proposed transient model is validated using actual temperature data collected in roadways in Wearmouth Colliery in the North East of England. The transient results are compared with the steady state predictions of Voss (1969). Finally, predictions of air temperature in roadways for a recirculation system will be made using both the transient and steady state models. Temperature predictions along faces will be made using a separate model.

Jan 1, 1989

By Karl W. Mote, R. K. "Ivan" Urnovitz

One of the Northwest Mining Association's guide-lines is: "If you always do what you've always done, you'll always get what you've always gotten." Another way of saying this is, simply, "when the road curves, don't refuse to turn." Our industry has been roundly criticized for living in the old political world, and, I believe, justifiably so. Until about 20 years ago, members of both houses of Congress deferred to specialists among their members for mining legislation. This was true for all public lands and natural resource issues, and were referred to as the mining bloc, or the timber bloc, or the ranching bloc. We felt safe, and to a large degree, were safe in the sense that western members of the US House of Representatives and of the US Senate understood the need for multiple use of public lands, and the need for the natural resources they supply. They also knew what it takes to stay in business and how to create the economic atmosphere that encourages private industry to find and provide the natural resources. Almost daily, members of our industry bemoan the destructive effects that current regulations, let alone new proposals, are having on American industry. And, there are some intriguing aspects for us to ponder. First, the specific complaint about the government is not regulation per se, but rather that the rules or policies don't make sense. We recognize that few understand our industry, but we have assumed that the government will rely on people experienced and knowledgeable in the area being brought under government controls. There was a time that this assumption was valid, but it is no longer true since we have entered the era of the professional regulator. Much like the MBA who believes that a professional manager can manage anywhere, the new breed of regulator sincerely believes that process is the key to developing effective regulations or programs. They reason the process virtually assures that all the pertinent facts will inevitably come to light and, after receiving appropriate considerations, will result in the proper decision being reached and implemented. Unfortunately, following the process also allows politics to play a new and greater role than ever before, since information based on what can only be called weird-science can now be presented to the professional regulator and accepted as fact. Regulators do not have the background to question the basic tenets of the conclusion being presented to them. To add insult to injury, testimony from people in the industry involved, intended to set the record straight, is too easily discounted as being merely self-serving. A second aspect is that the question of why the associations aren't doing more to stop poorly conceived legislative and regulatory proposals, or to counter the ever-increasing influence of the selfappointed public interest groups is being increasingly discussed. This is occurring despite the fact that there is a higher level of involvement and closer cooperation between the various associations than ever before. This raises a most important question: where are we going wrong? In the last 20 years or so, major changes have taken place. A new philosophy, taking advantage of the public's recognition of need to protect our environment, has swept through the nation, resulting in a whole new body of law enacted to assure environmental protection. We all acknowledge the need to prevent undue degradation during the course of mineral development, and we all consider ourselves to be responsible stewards of the land, because we live and work in the outdoors and know the importance of environmental protection. The changes in the federal statutes apply now to every aspect of mineral discovery, development, and production, and assure adequate reclamation of lands when we are done. Along with the positive changes, are a constant barrage of attempts to stop public land use, or stop mining, or stop any new economic development, ostensibly to "protect the environment," but often reflecting a hidden agenda of social reform. These types of extreme, irrational, and just plain impossible proposals are everyday occurrences, but we have not geared up to challenge all the proposals which could end mining. Instead, we did what we always had done. The road turned, but we didn't. And we wondered why those who had always protected mining weren't doing their job, and why we were having such limited success in reining in the regulators. The Congress had changed, the public demands had changed, the recognition of importance of natural resources had

Jan 1, 1991

By Harold Stocker

INTRODUCTION This presentation is concerned with the administrative and technical capability of the Atomic Energy Control Board (AECB) to assure compliance with the individual exposure limit for radon daughters (currently 4 WLM per year). It is not concerned with the epidemiological bases for setting the exposure limit. Moreover, the intent is to show how sophisticated methodologies and advanced technologies, applied to radon daughter concentration measurements in uranium mines, convey the spirit of compliance by providing better estimates than do the historical methods. These better estimates mean that more accurate and more precise estimates of each worker's exposure are determined using these more modern methods and devices. The estimates so derived should provide more convincing evidence to an individual worker that his assigned exposure is a valid indicator of his true exposure. In addition, a perspective on the exposure estimate in relation to the exposure limit is given as further evidence that an exposure limit is not the dividing line between "safe" and "unsafe" exposures. A brief description is given of the compliance aspects of the Atomic Energy Control Regulations and of the limitations of purely statistical non-compliance procedures. Most of the emphasis of the paper will be placed on the uncertainties associated with conventional radon daughter exposure determination and the means being employed (and anticipated) to reduce these uncertainties. NON-COMPLIANCE Under current Atomic Energy Control Regulations (1978), the annual individual exposure limit for radon daughters is given without reference to the possible methods of sampling and calculation of radon daughter exposure and without any reference to possible uncertainties or their magnitudes. This is common in such statutes, the details of sampling, calculation, error analysis, and so on, being left for licence conditions or provided as a specific guideline to the licensee on the matter of compliance with the Regulation. Since the exposure limit is contained in the Regulations, compliance with it is absolute, as with any other law. In Canada, a state of non-compliance with the radon daughter exposure limit exists when an exposure (attributed to an employee) is reported by the licensee to exceed the limit. No uncertainty in the measurements or in the overall determination of exposure is reported nor is any requested. Removal of the worker and the loss of his services are the immediate and direct penalty suffered by the licensee for failure to maintain the exposure at, or below, the limit. A worker may be re-instated to employment for the balance of the reporting period only if the licensee can assure the AECB that further significant exposure to the worker will not ensue. In other jurisdictions, such as the United States, non-compliance is defined on a statistical basis. For example, NIOSH, the National Institute for Occupational Safety and Health presents procedures for calculating the 95% Lower Confidence Limit (LCL) in order to "compare the results of occupational environmental sampling to an occupational health standard and make a decision with a known chance of making an incorrect decision that a state of non-compliance exists" (Leidel and Busch, 1975). (In the nomenclature of this presentation, exposure limit would be used in place of "standard", in the NIOSH sense). Furthermore, it is emphasized in the NIOSH document that such numerical comparisons "are necessary only if the sample mean is greater than the standard". The NIOSH document points out, quite correctly, that the "statistical procedures presented below will not detect and do not allow for analysis of highly inaccurate results, i.e., systematic (non-random) errors or mistakes ... If a systematic error is known to exist in an instrument or analytical procedure then correct the sample mean of the data before analyzing for non-compliance". It is certainly not the purpose of this paper to criticize the sophisticated statistical approach to non-compliance as given in the NIOSH document or in similar approaches used in other jurisdictions. Rather, the purpose is to approach, with some introspection, the question of the determination of exposure by the employer for his employee and especially the employee's understanding of, and confidence in, the accuracy of the exposure determination and its relation to the exposure limit. DETERMINATION OF EXPOSURE Historically, in uranium mines, exposure to radon daughters for an individual miner

Jan 1, 1981

By P. K. Berger, G. T. Lineberry, H. P. Cole, J. V. Haley

Sixty-five simulation exercises were developed for teaching and testing problem solving and decision making skills to miners and mining engineers. The exercises focused on judgment and decision making for preventing and controlling mine emergencies. The structure and field testing of the exercises are described, and sample frames of individual exercises are presented. Empirical data are summarized about the effectiveness of these simulations based on the performance scores of a national sample of miners and mining engineers.

Jan 1, 1994

By Z. T. Bieniawski

Ground support requirements for safe and economical design of room and pillar coal mining layouts are reviewed. The design methods for mine roofs and mine pillars are discussed and the role of the geotechnical aspects is considered. It is shown that current support design procedures in the United States do not utilize fully the latest research findings and the need for more effective technology transfer in coal mine ground control is emphasized. Promising new developments in ground support are identified and possible research areas are suggested.

Jan 1, 1982

By Terence H. Fisher

The use of more productive mining equipment, the tendency to longer development and the advent of new mining methods have introduced new challenges to the ventilation practitioner in Western Australia. These new and more productive mining methods have presented specific ventilation problems, that if not properly addressed, present additional hazards to miners. Factors influencing the increased hazards are larger diesel units, the use of series ventilation systems and an increasing incidences of long (single entry) development and production headings where miners could be trapped in a fire emergency. This paper discusses these new ventilation safety challenges, how they have been and are being addressed, and the legislation changes that take cognisance of technological developments.

Jan 1, 1995

By Y. David

In 1990, the United States became only the second country (after China) to produce more than 900 Mt (1 billion st) of coal in a single year. US production of bituminous and subbituminous coal, lignite and anthracite totaled 933.5 Mt (1.029 billion st) in 1990, 5% more than in 1989. The production gains were largely due to the rebuilding of depleted coal stockpiles by electric utilities and a surge in US coal exports. Domestic coal consumption essentially remained at its 1989 level. A slight increase in electric utility coal consumption was partly offset by a decline in metallurgical coal use. The use of coal in other industries and in the residential-commercial sector remained virtually flat.

Jan 1, 1991

By B. K. Parekh, R. H. Mehta

The handling of fine coal is an important issue for both the coal and utility industries. Reconstitution of fine coal in the form of pellets or briquettes would be desirable if it could be done economically. This paper evaluates the effectiveness of three binders, asphalt-emulsion, corn starch and Brewex, informing pellets of ultrafine clean coal. It was found that asphalt-emulsion and corn starch were not effective binders. However, the use of Brewex resulted in pellets that exceeded all of the minimum quality requirements for coal pellets.

Jan 1, 1997

By Fang-tu Wei

The purpose of developing this system is to monitor the operating status of the fully mechanized mining system in order to raise it's reliability. The completely mechanized coal mining system is a complex dynamic system, involving many sub-systems. It is the key of the mining process as well as a connected system composed of each working procedure. Any hitch in breaking, loading or transporting will interrupt the mining process. The analyses of the operating data has proved that the reasons causing the interruption of the extracting processes mainly come from the inner of coal face. Hence, after the installation of the MINOS system in England, the delays of belt conveyor sub-system were reduced. But the production increment was not as much as expected.

Jan 1, 1986

By G. Atesok, M. Hancer, M. S. Celik, O. F. Emrullahoglu

Multivalent ions are shown to activate the flotation of colemanite in the presence of sodium dodecylsulfate (NaDDS). Floatation recoveries versus barium ion concentrations exhibit three distinct regions of floatability. Adsorption, zeta potential and solubility mesurements under comparable conditions reveal that Region I is characterized by the uptake of Me2+ ions followed by electrostatic attraction of sulfate ions onto the oppositely charged surface. The improvement observed in flotation recoveries in Regions II and III is ascribed to surface and bulk precipitation of metal dodecyl sulfate onto colemanite, respectively. While the most soluble BaDDS ions yield the highest activation, the least soluble MgDDS achieve the lowest activation. It is postulated that metal ions depending on their solubility products with DDS are capable of activating the boron minerals.

Jan 1, 1993

By R. L. Unger

Restricted fields of vision are a common problem with underground mining equipment. Also, when lighting systems are provided, they may be positioned where they cause glare. This restricts the visibility around the machines even further. To help address these problems, the US Bureau of Mines has developed a PC-based software package to aid in the analysis of certain human engineering aspects of mining equipment design. The software is available for use by equipment manufacturers and mining companies for design work on new machines, as well as for evaluating proposed modifications to existing machines.

Jan 1, 1995

By R. K. Rajamani, R. Verma

In ball milling the rates of breakage vary primarily with the size distribution of powder in the mill. Using an approximate solution to the batch-grinding equation, the acceleration and deceleration of breakage rates of all individual size classes are determined when the grinding environment is varied. Experimental results with limestone and copper ore show time-dependent breakage rates under both dry and wet grinding conditions. The effect of grinding additives on breakage rates is also studied. In general, breakage rates increase for coarse sizes and decrease for fine sizes with an increase in the fines present in the mill. Such variations have strong implications in closed-circuit grinding.

Jan 1, 1992