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By Brian P. Stapleton, Bill M. Stewart, Joel R. Warneke, Curtis C. Clark

Of the 28 accident/injury classifications listed by the Mine Safety and Health Administration, handling materials is second only to roof falls in terms of generating the highest number of reportable accidents in active underground coal mines. Two materials-handling activities that cause numerous injuries each year are the categories of ‘handling supplies or material, load and unload’ and ‘moving power cables.’ Mechanization and mine worker activity training are two methods that can aid in preventing these injuries. This paper describes three mechanical methods – the mobile manipulator, the in-mine hoist, and a cable-handling system - being developed and tested at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health. Two of the devices are specifically designed for loading, unloading, and moving supplies and materials, and the third device is for handling trailing cables in the confined spaces of coal mines. Also described are safety solutions developed for underground coal mines geared to showing miners safe and unsafe ways of performing various materials-handling tasks.

Jan 1, 2005

By J. W. Choung, J. A. Finch

Acid rock drainage (ARD) is a recognized environmental challenge facing mining industries. An ambient temperature ferrite (ATF) process has been investigated for treating ARD. Most nonferrous metal and calcium ions present in typical ARDs were found to be detrimental to the ATF process. Three approaches were examined, including C02 aeration, addition of complex agents and use of magnetic seeds. By introducing magnetic seeds in the ATF process, the interferences were minimized and all the precipitates formed with lime neutralization were magnetically recovered from a simulated ARD. The residual concentrations of major metal ions in the treated water were environmentally acceptable. The XRD pattern confirmed the spinel ferrite crystal structure of the products

Jan 1, 2000

By John W. Kelse

What happens when the skull and crossbones goes on a product? In the case of cancer warnings, the consequences can be severe. If the label contains the term "lung carcinogen", you might expect to compensate a lot of smokers, meet a lot of expensive lawyers, be counseled by equally expensive consultants and pay sharply elevated insurance premiums, if you are able to obtain coverage at all. At the extreme, you may face plant shutdowns, job losses or even Chapter 11 bankruptcy. Regardless of how you fare, you are likely to learn some very disconcerting things about the risk evaluation and regulatory system which required you to label in the first place. If a particular material or product does pose a health risk, you are obliged both legally and morally to warn those potentially exposed. Once that warning appears on the label, however, the consequences are often beyond your control. You and your embattled product become part of a legal/regulatory system which has a life of its own. Therefore, the issue of health labeling is not so much whether one warns but rather whether the warning itself is justified and the reasonableness of what happens afterwards. It is this matter of justification and reasonableness, particularly of cancer warnings, which this paper addresses. Until, as they say, your ox has been gored, we tend to believe that risk is determined by the best available technology and expertise We expect that risk evaluators appreciate the ramifications of their work and place things in proper perspective; that risk has been appropriately demonstrated before it is publicized and regulated; that the time-honored concept of prudence, to err on the side of safety, has not been excessively stretched. Unfortunately, the risk evaluation process is rarely, if ever, this

Jan 1, 1991

By J. A. Hrabik

The feasibility of mining deep phosphate deposits by a borehole mining system was compared with mining by proven conventional techniques. An economic comparison of the borehole mining system with conventional dragline and bucket wheel excavator mining systems was completed at various mining depths and production rates. Hypothetical phosphate deposits, with various overburden thicknesses and reserve tonnages, were defined. Geologic conditions necessary for the application of the borehole system were identified. Discounted cash flow analyses based on derived capital and operating costs were used to generate rates of return and product prices. Borehole mining was found to be more economical where overburden thickness was 46 m (150 ft) or greater. However, at 15- and 30-m (50- and 100-ft) thicknesses, conventional surface mining was more economical. Overburden thickness has a great effect on the economic feasibility of the conventional mining systems but less effect on the economics of borehole mining. Economies of scale are only realized in conventional mining, since larger equipment is used to achieve greater production, whereas increased production from borehole mining is achieved using additional equipment units. A comparison of the environmental effects of borehole and conventional surface mining systems showed that borehole mining is environmentally more desirable.

Jan 1, 1987

By R. V. Ramani, R. Bhaskar

The results of an experimental and theoretical research study into the spatial and temporal behavior of dust in mine airways is summarized. Experiments were performed in mine airways under both controlled and normal operating conditions. The controlled experiments included the documentation of the concentration and deposition patterns for two types of dust under three different velocities. Real-time dust concentration data were obtained using real-time aero- sol monitors (RAM-I) to determine the dispersion coefficient in a mine airway. On the theoretical font, a convection diffusion model of the dust flow phenomenon in mine airways was developed considering dominant mechanisms affecting dust transport and deposition in mine airways. Mechanisms modeled include turbulent and gravitational deposition, coagulation, and dispersion. In this paper, comparative analyses of results (8 the controlled experiments with the predictions of the mathematical model are presented. In addition to the overall validity, the adequacy of the individual components of the model, such as deposition in the total and respirable range, and dispersion are examined in light of the experimental observations. The experimental data from controlled experiments compared more favorably with model predicted results for similar conditions as opposed to the comparative analysis results for in-mine experiments. Specifically, the model predictions for an 800-m stretch of a mine airway reveal some significant differences from the behavior noticed in the mine. The deposition was lower than that predicted by the model. Consequently, concentrations were higher than those predicted by the model. The implications of these and other findings for further investigations are discussed in the paper.

Jan 1, 1987

By Carl-Eric Dr. Nilsson

Energy cost for mine ventilation in Sweden is high, especially during winter time when air must be heated. This paper presents the result from a project entitled ventilation-as-required. The term ventilation-as-required means that the required volume of fresh air should be distributed only to such areas, where mining work is going on and to be reduced to a minimum in the rest of the mine. Ventilation-as-required is a monitoring system that controls the operation and capacity of the fans and measure the air pollutant gases, i.e. carbon monoxide, nitrogen and sulphur dioxide at strategic points. It is an active system that responds when equipment is under operation. MITU proposed in 1991 a project to develop a ventiation-as¬required system and such components as transmitters and receivers for the communication between the equipment and the fans. The mining companies, Boliden Mineral AB, LKAB, Outokumpu and Ammeberg Mining Corporation joined the project and have financed a joint research and development programme supported with a grant from the Swedish Government through NUTEK. MITU proposed a second project in 1992 to the mining companies to develop an improved "intelligent" fan for scope ventilation. Boliden Mineral and LKAB joined the project and have financed a joint research and development project supported by the Swedish Government through NUTEK. The Government even made a commitment to support the investment of the first 50 fans ordered with a grant of 25% of the investment cost. The result from projects show that the target set up in the plans is more than achieved, with an energy reduction that exceeds 30% compared to previous consumption. No environmental influence due to reduced ventilation is observed in the stope when work is under progress. Dilution of exhaust gases from diesel fuel decreased from 6.000 m3/L consumed diesel fuels to 3,600 m3/L. The automatic data processing and sensor system is even increasing the security of the work so that it can be done under safer environmental conditions.

Jan 1, 1995

By Jeong-Heum Kim, Jan M. Mutmansky, Y. J. Wang

The simulation of randomness in a system of components is important in certain types of systems analyses. This paper presents procedures for generating ventilation networks that are random in many of their characteristics and which can be used to study the performance characteristics of various mine ventilation network analysis procedures without introducing undue bias as a result of the nature of the network. Among the parameters of a network that affect the efficiency of a network analysis procedure are: (1) the interconnection pattern of airways, (2) the distribution of resistances in the network, (3) the number and location of fans, (4) the fan characteristic curve, (5) the size of the network (number of branches), and (6) the density of the network (number of nodes compared with the number of branches). In the procedures proposed here, a single fan with a fixed characteristic is used to simplify the problem and eliminate the fan as a source of variation. The resistances of the airways, the pattern of interconnection of the airways, and the fan location are randomly chosen in an attempt to eliminate the bias in the performance characteristics of the network analysis methods caused by these parameters. A method of generating biconnected networks while keeping the "randomness" of these other parameters is suggested. At the same time, the size and the density of networks are controlled to investigate their impacts on the performances of the network analysis procedures. The combination of these two variables has been termed the "level of complexity" of the network in this paper. Finally, a summary and conclusions section outlines some characteristics of the networks generated, using the random generation procedures outlined in the paper.

Jan 1, 1991

By Faruk Oksuz, Cary Hirner, Ray Brainard

"Key project participants, including owners, engineers, and contractors continually seek for sound and structured decision analysis on how to select the best contracting method for successful project delivery. In addition to being burdened with technical challenges, lack of resources, budget shortcomings, regulatory requirements, and bureaucratic and politically mandated obstacles, the project participants need a reliable decision analysis model on the best project delivery method. The pendulum of choice for contracting continually swings back and forth between traditional design-bid-build and alternative delivery options such as design-build, progressive design-build, construction manager at risk, and public-private-partnership. For large tunnel projects, the decision process is further complicated due to contract packaging options as well as risks in underground construction. Contracting strategies for large tunnels require thorough consideration of performance, risk, quality, operability, cost and schedule. This paper compiles an array of decision making criteria and tools for an unbiased and balanced evaluation and ranking system in the procurement of large tunneling projects. INTRODUCTION Successful project delivery hinges upon meeting the owners’ expectations and key performance indicators. Large tunneling programs benefit from a thorough understanding and successful implementation of project delivery options by key project participants including the owners, engineers and contractors. The key to success is a collaborative advancement of project as the key project participants knowledgably address the applicable management, performance, risk, quality, cost, operability and schedule considerations throughout a project realization cycle. PROJECT REALIZATION CYCLE All projects have customary planning, design, construction, commissioning and operation phases that may seem to be sequential but in reality that are well integrated and dependent on one another. A glitch in any phase of a project realization cycle could hinder a successful outcome and none of the project partners are immune to consequences whenever and wherever they may surface."

Jan 1, 2016

By Thierry Coléou

In this paper, we consider open pit optimization. At present, most methods specify the economic parameters and then find the corresponding optimal pit. But as the economic environment varies (which it does regularly these days), the "optimal" pit changes and quite often changes markedly. The questions are: by how much does it change and which parameters are most influential? The functional approach of Technical Parameterization of Reserves, devised by Matheron in 1975, gives the set of all the different optimal pits, under any economic condition. It separates technical design and economic assumptions and thus permits the use of several optimality criteria when choosing the final pit, and not just the maximization of an additive profit formula. Very efficient specific algorithms are presented to obtain all the potentially optimal pits. Fluctuations in the parameters induce changes in the optimum design. Inclusion relations that exist generate very tight bounds and hence very quickly detect optima, even when using a classical adaptation of maximization techniques (graph theory, moving cone, dynamic programming ...). The advantage of Technical Parameterization of Reserves over other methods is that it provides a nested sequence of optimal pits which can then be used for mine scheduling. Many possible mining schedules can be obtained by using the family of technically optimal projects to split up the orebody. The "optimal" schedule, which is in fact a compromise between the different requirements of the economists, the mine planner and the metallurgist, can be chosen from within the wide scope of possibilities. A practical example of mine scheduling for a chromite mine is presented in detail.

Jan 1, 1989

By Henry R. Tiedemann, Eugene H. Skinner, George E. Wickham

The need for ground support research in underground excavation has been well identified in recent years by many studies in the subject area (1, 2, 3, 4, 5). A typical conclusion from these reports (1, 2) is that the drill-and-blast (D & B) mining or the mechanical tunnel boring machine (TBM) methods are expected to be continued in use for the needs of tunneling in the immediate future. The Organization for Economic Co-operation and Development (OECD) sponsored in June, 1970 advisory conferences on Hardrock and Soft Ground Tunneling (3,4). These two reports were based on the combined response received from approximately six hundred inquiries from 17 nations in the summer of 1969 and which concerned all aspects of present-day inadequacies of, and the needed improvements in the technology of tunneling. Some specific problem areas in ground support and tunnel linings were: 1) the ability to successfully predict rock loads that must be carried by the support system; and 2) inadequate methods for determining the load-carrying capacity of the various support systems. Therefore, the problem area is clearly defined by these two objectives: 1) To find means of predicting rock loads; and 2) To develop methodology for determining safe, efficient, and economical ground support design practices. Noting these research needs from a great number of sources, the United States Bureau of Mines, Spokane Mining Research Center (SMRC), acting as agent for the Advanced Research Projects Agency (ARPA), undertook contract research effort in these problem areas. Work by Jacobs Associates has studied a methodology for specification of temporary artificial support based on the dependent sequence of mining operations and prediction of various rock conditions in the pre-excavation stage. The major thesis is that rock behavior is the

Jan 1, 1997

By Dirk van Zyl, Lysa Morishita

Mining companies are increasingly approaching the social aspect of sustainable development within the rural communities that neighbour their projects and operations. Rural community engagement requires significant effort and resources, and it can be extremely challenging for mining companies to earn and sustain social capital. The focus on rural, proximal community engagement is not to be understated and has led to significant benefits in many communities. However, opposition to mining projects is often exhibited in urban environments, where there may be potential for mining companies to gain social capital with relative ease. Cities tend to have existing frameworks for community engagement and public activation, such as annual parades and festivals, that make it easy for a mining company to provide financial support or value-in-kind. Local organizations and community groups can achieve the same amount of engagement in an urban environment with significantly less effort required from the mining company. By applying simple marketing principles to community engagement strategies, corporations can increase awareness for their business and encourage city residents to think critically about the origin of resources. Unlike many corporations, mining companies are not marketing or selling products to individual consumers. From this arises the opportunity for a company to use marketing to promote other positive initiatives and, as such, connect their brand with positive messaging thus earning social capital. This may lead to a wide variety of secondary impacts including benefits to recruitment efforts, increased political support, and positive media coverage. This paper explores these matters with special reference to Vancouver, BC, Canada and the mining companies Teck and Goldcorp.

Jan 1, 2017

By Stephen P. Harrison

The ventilation of coal mines has long been a major challenge for the mining industry. Prior to the 1969 Health and Safety Act, mine ventilation planning was almost entirely handled by individuals in mine operations and engineering who had extensive practical experience. Their background and expertise was sufficient to deal with existing ventilation problems and planning. A recent decline in the number of qualified individuals combined with more stringent state and federal regulations have necessitated a thorough engineering oriented approach to ventilation in mine planning design. To plan for an existing mine, a thorough ventilation survey must be conducted to determine the capabilities of the existing ventilation network. A ventilation survey also provides considerable useful data for long range planning. Essential information such as friction factors, entry resistance, and potential ventilation problem areas is gained from the survey data. With this information a comprehensive computer analysis can be conducted to evaluate alternative mine plans. This evaluation of mine plans is essential to minimize the number of shafts required while still maintaining the quality of mine ventilation. Using an existing mine as an example, this paper outlines a detailed procedure for organizing, con-ducting, and evaluating a ventilation survey. In addition, specific ventilation problem areas are isolated and alternative methods for their solution are considered. Furthermore, a long range mine plan is evaluated and the most feasible variation of the plan is selected.

Jan 1, 1980

By J. Linhart

In vertical airways, falling material - solids-or water - may cause undesirable disturbances in the ventilation in the airway itself and also in neig¬bouring airways unless precautions are taken to stabilize the air flow. Such cases can occur, for example, - in shaft sinking by drilling from a pilot hole, - during the filling up of shafts, and - during the introduction of water into shafts in the case of mine fires. In an airway with upward ventilation the falling material will reduce the air flow and may even re¬verse its direction. In an airway with downward ventilation the air flow can only increase, but a reversal of the direction of ventilation may result in a parallel airway. These disturbances in the normal ventilation are undesirable as it must be the aim to have ventilation that is stable in quantity and direction throughout a mine. In order to be able to prepare suitable stabilization measures one must know the pressure generated by the falling material; this pressure will henceforth be called "aeromotive" pressure. The main factors determining the influence of falling material on the ventilation are - the amount of falling material and its height of fall, - the cross sectional area of the airway, - the pressure. difference prevailing in it, - the-position of the. airway in the ventilation. network, - the air velocity, and - other parameters, e. g. the density and grain size of the falling material. To determine the aeromotive pressure-measurements have been made underground during the sinking and filling of shafts and systematic studies have been carried out during the supply of water into a staple shaft. The present paper deals first with some fundamental theoretical considerations and then describes the measuring arrangements and the results of the series of experiments that have been carried out.

Jan 1, 1980

By Wayne F. Crockett, Martin H. Col

Gold, as a precious metal, has been sought for several thousand years. During this time economics have generally determined whether or not a deposit is minable. Today, few would spend $500.00 or $1,000.00 to produce one ounce of gold, yet most gold deposits currently being mined would have such costs if they were mined using the methods of the 18th century. Innovation has been the key to success in the world of mining. We are constantly having to look for new ways to mine deposits of lower grade, at greater depths, or with higher stripping ratios. The mining of placer gold deposits has always been subject to the volatile swings of the world price and the constant rise in production costs. The rise in costs is compounded by the drop in overall ore grades. Occasionally, a major technological innovation will dramatically reduce the costs of placer mining to allow previously marginal or unminable deposits to be mined at a profit. The continuous bucketline dredge was the last such major innovation in the gold placer mining. The continuous bucketline dredge has allowed large volumes of placer deposits to be picked up and processed on a continuous basis. Unfortunately, as the overall grade of the deposit declines, it becomes impossible to process enough ore to pay for the operating costs. There are many gold deposits around the world waiting for the next technological innovation that will allow them to be mined. One such deposit has been the Grey River deposit near Greymouth in New Zealand. The deposit contains gold reserves of 8992 kg, yet the deposit has been sitting idle for many years because the average value

Jan 1, 1988

By Van E. Housman, Stephan Hoffman

Introduction Based upon the 1980 Bevill Amendment to the Resource Conservation and Recovery Act (RCRA), a 1986 Regulatory Determination decision, and subsequent rulemakings, the Environmental Protection Agency (EPA) exempted all extraction and beneficiation wastes and twenty mineral processing wastes from regulation under RCRA Subtitle C (hazardous waste) regulations. These twenty mineral processing waste streams were studied in a 1990 Mineral Processing Report to Congress. For purposes of regulatory classification, EPA made special distinctions between extraction/beneficiation and mineral processing. Wastes determined by EPA to be from the extraction/beneficiation of ores and minerals retain the exemption, while wastes found to be mineral processing, except for the “special" twenty mineral processing wastes, fall within RCRA Subtitle C jurisdiction. For those wastes that are subject to RCRA Subtitle C, § 3004(m) of RCRA requires EPA to set levels or methods of treatment, of any, which would substantially diminish the toxicity of the waste or substantially reduce the likelihood of migration of hazardous constituents from the waste so that short- term and long-term threats to human health and the environment are minimized. These treatment standards are developed by EPA under the Land Disposal Restrictions (LDR) program. Under § 3004(g) (4) of RCRA, EPA is required to promulgate treatment standards for any waste that is newly identified or listed as hazardous. As part of the settlement agreement in Environmental Defense Fund (EDF) v. Reilly and Chemical Waste Management, Inc. v. EPA (1992), EPA has agreed to propose a rule by June 30, 1995 and promulgate a final rule by June 30, 1996. This rule is commonly referred to as the "Phase IV" LDR rule and will address newly identified mineral processing wastes. Other wastes that will be addressed in this rule include newly listed dyes and pigments and wood preserving wastes. Therefore, in the Phase IV rule EPA will develop treatment standards for all mineral processing wastes that have lost their Bevill exclusion. EPA is currently collecting information on the waste characterization, treatment alternatives, and disposal capacity data currently available on these wastes. EPA is also soliciting data and information on opportunities for

Jan 1, 1995

By Matthew Spedding

The complex nature of the carboniferous measures prevailing in the U.K. has dictated the types of mining required to exploit the coal seams. Most mines in Britain are referred to as deep mines in the sense that they operate at depths of 1800 - 3000 feet. The main system of coal transport to the surface is by vertical shafts which intersect the workable seams which at times number between 4 and 5. As mining has been practiced in most of the major coalfields in the U.K. for well over 100 years, with the initial extraction of the shallower and more profitable seams, the present management have been left a legacy of indiscriminate extraction which severely hampers their efforts to maximise the mine layouts. There is no single standard design of mining layout capable of meeting the wide variety of conditions which exist in the British coalfields. Mining layouts are subject to fixed and variable parameters. In discussing multi-seam working, the main parameter must be the effect of old workings above and below the seam to be extracted. There is a distinct lack of reliable information which would enable layouts to be designed to completely avoid or control these destructive forces. The guidelines are, therefore, mostly empirical.

Jan 1, 1977

By Albert W. Evans

Introduction Engineering Health and Safety is concerned with the understanding of the complex interplay between the risk of injury with technological ,environmental, individual, organisational and legal factors. With this understanding, the design and decision making processes can be balanced with the other objectives of industry and employment to arrive at solutions which place appropriate controls on technology and other aspects of human activities to prevent disease and injury to personnel in the coal mining industry and the design of safe production machinery and ancillary equipment. Advances in the detection and diagnosis of causes of diseases and the need for engineering health and safety in the coal mining industry has increased the need for appropriate education and training. Hazards arise in many forms; exposure to toxic chemicals, escape of radio - active materials, explosion of pressure vessels, contact with moving machinery, exposure to dust, environmental dangers such as excessive noise, high temperatures and manual handling etc. As technology advances, these dangers become more complex and less clearly defined and less easily perceived. Consequently, the ways of controlling the dangers also become more complex and wide ranging. The need to educate and train people in coal mining applications of engineering health and safety has been enhanced over the last five years and courses should be established to fulfil the need for competent people to deal with the problems which modern coal mining technology creates together with the legislation that governs engineering health and safety and to carry out research and development work in the coal mining industry. Industrial Involvement The engineering health and safety experts must be prepared to take a more active part in monitoring conditions that exist in the mining industry, and not design from information obtained from the mechanical, electrical and hydraulic expertise and off-the-shelf components from other industries. Surveying and control of the operating environment must be essentially the concern of the engineering health and safety experts and, whilst it is not possible to create a perfect environment for each machine, every effort must be made to minimise failures and hence plan for designs which will maximise

Jan 1, 1986

By James R. Norris, Thomas A. Conto, Gary R. Walter

For at least five decades, a plume containing acidic metal-bearing water has been moving through the shallow alluvial aquifer along Pinal Creek in the Globe-Miami area. Two chemical facies of water are distinguished in the alluvial aquifer: (1) a metal-rich acidic plume with gram per liter concentrations of metals (primarily iron) and pH values between 3 and 5 and (2) neutralized water with a pH greater than 5, low concentrations of metals, and high concentrations of sulfate and manganese. Historically, the acid plume has moved through the aquifer at an average velocity of 0.6 m/day, ten times slower than the average pore velocity of groundwater in the aquifer calculated using the Darcy equation. The rate of migration of the metal-rich plume is retarded by pH-dependent chemical reactions between acid water and the aquifer matrix. As acid water is neutralized by reaction with calcite, rising pH conditions in- crease the oxidation rate of iron and decrease its solubility resulting in the precipitation of ferric hydroxides. The formation of ferric hydroxides is a proton releasing reaction which main- tains acidic conditions. The acidit of the plume and the neutralization capacity of tKe aquifer are best assessed in terms of the iron content of the water and not the hydrogen ion activity computed from pH measurements. The parameters controlling plume migration are: (1) the calcite content of the aquifer (2) the iron acidity of plume water, and (3) the rates of acid neutralization and ferrous iron oxidation. A numerical solute transport and reaction model based on the concept of iron acidity effectively simulates the historical development of acidic conditions, predicts the behavior of the plume, and was used as a management tool to identify the most efficient and cost effective remedial strategy.

Jan 1, 1991

By Kenneth V. Luza

Underclays are associated with coals found in eastern Oklahoma. These coals are of bituminous rank and are in beds of Middle and Late Pennsylvanian age. They occur in an area of about 8,000 mi2, within the southern part of the Western Interior Coal Region. The rocks of the area consist of a thick series of sandstones, shales, underclays, coals, and limestones. There are more than 40 beds of bituminous coal in the state, but only 12 of these have been mined over large areas. The 12 are, from oldest to youngest: the lower Hartshorne, upper Hartshorne, McAlester (Stigler), upper McAlester, Cavanal, Rowe, Secor, Weir-Pittsburg, Mineral, Croweburg, Iron Post, and Dawson coals. None of the underclay associated with these coal beds is known to have been exploited commercially. Nine samples of underclay from beneath the Croweburg coal were collected over a wide area in the eastern Oklahoma coal field for evaluation. The underclays are usually shades of gray with brown or orange iron-oxide staining. Although soft and plastic in some places, they are generally hard and slickensided, and contain abundant carbonized plant fragments. Bulk chemical analyses, clay mineral identification, and ceramic tests were performed on each underclay sample. The dominant clay minerals are illite and kaolinite with some mixed-layer clays. Silica (Si02) ranges from 45.96% to 59.03% and alumina (Al2O3) varies from 14.98% to 23.60%. The U.S. Bureau of Mines Tuscaloosa Re- search Center conducted the ceramic evaluations. Samples were slow fired from 1,000°C to 1,250°C in 50°C intervals. Bulk density, color, percent linear shrinkage, and percent absorption were determined for each slow fire test. All Croweburg underclay samples are best suited for building brick.

Jan 1, 1999

By Laurence M. Demers, Douglas C. Kuhn

It has been suggested that radicals on the surface of dust particles are key chemical factors in the pathophysiology which results from the occupational inhalation of coal and silica dust. In addition, oxygenated derivatives of arachidonic acid (eicosanoids) have been implicated as important biochemical mediators of mineral dust-induced lung disease through their role in bronchial and vascular smooth muscle reactivity, inflammation, and fibrosis. Therefore, we assessed eicosanoid production by the rat alveolar macrophage (AM) exposed in vitro to mineral dusts with varying surface chemical characteristics in order to determine if radicals associated with the mineral dub1 could influence the production of pro-inflammatory mediators in the lung environment. Rat AM were exposed to freshly fractured or "stale" bituminous coal dust, as well as untreated silica or silica calcined to 500°C and 1100°C. Prostaglandin E2 (PGE2) and thromboxane B2 (TxB2) levels in incubation medium were determined by specific radioimmunoassay. When AM were exposed to freshly fractured coal dust, PGE2 and TxB2 production were markedly increased. In contrast, exposure of AM to "stale" dust significantly reduced PGE2 and TxB2 production. In vitro exposure of AM to untreated silica resulted in a significant increase in PGE2 and TxB2 production compared to control. However, exposure of AM to silica calcined to 1100°C resulted in eicosanoid levels which were not significantly different from control. These findings suggest that radicals associated with respirable coal and silica particles may play a key role in the ability of mineral dust to activate AM eicosanoid production.

Jan 1, 1991