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By L. J. E. Hofer, L. F. Zeiler, D. A. Giardino

The Jones Trickett Ratio (JTR) is generally used in investigations of fires and explosions for the determination of the composition of the fuel. This paper takes a close look at the JTR and finds it unreliable and ambiguous for the determination of fuel composition. A new index is presented, termed the (H/C) Index which uniquely determines the fuel composition. The (H/C) Index is simple to use requiring only the results of a single gas analysis of the combustion products. Experimental data testing the (H/C) Index for methane, propane, ethylene and coal dust are given, showing that the Index unambiguously determines the composition of the fuel. The (H/C) Index is also applied to the gas analysis data of several mine fires, illustrating how the Index changes with the progression of the mine fire.

Jan 1, 1993

By G. Johnston, P. K. Chatterjee, S. Holguin

Underground mine planning is largely manual and can demand considerable resources to generate a working plan and to perform limited tests of sensitivity to variations in geological and mining conditions. It is possible to use computer aided mine planning to automate many of the manual procedures to allow the planner to evaluate a number of layouts, extraction strategies, and schedules. his paper examines the simulation and scheduling of an under- ground coal mine operation through the-use of on- screen graphics. The simulation will provide a basis for predicting productivity and other relevant information over a specified number of shifts. The software developed is extremely user friendly and reduces the tedium of repetitive manual calculations inherent to mine planning and drafting to a minimum, thus offering considerable savings in an area that is widely recognized as extremely labor intensive.

Jan 1, 1988

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 Robert Mermelstein, Robert W. Kilpper

In a long term toxicology study SPF, F-344 rats were exposed 6 hours/day, 5 days/week for up to 24-months to a special test toner at 0, 1 (low), 4 (medium), and 16 (high) mg/m3, or Ti02 at 5 mg/m3, or Si02 at 1 mg/m3 by the inhalation route. The test toner was composed of about 90% random, high molecular weight acrylic copolymer and 10% high purity, medium color, furnace type, carbon black. It was enriched in fine particles such that the respirable aerosol concentrations (ACGIH) were to 0, 0.35, 1.4 and 5.6 mg/m3. There were no effects of exposure on survival, causes of death, body weight, food consumption or clinical chemistry and hematology parameters. There was no evidence for systemic or upper respiratory system toxicity as all of the changes were restricted to the lungs and associated lymph nodes. The lung tumor frequencies in the control (air and Ti02) and toner exposed groups were comparable. There were no changes at the low exposure level, which is the most relevant in regard to potential human exposures. The lung changes at the high exposure level consisted of decreased alveolar clearance, increased toner retention, increased lung weight, chronic inflammation, decreased pulmonary function and a moderate degree of focal fibrosis in all animals. The changes in the middle exposure level were smaller in magnitude than at the high level, and a very slight degree of fibrosis was found in 20% of the animals. In a follow-up investigation, female F-344 rats were exposed to one of three toner concentrations; control, low (10 mg/m3) or high (40 mg/m3) for 13 weeks followed by five, 13 week observation intervals. At the low exposure level, slight clearance retardation and modest inflammatory changes were observed at the end of exposure. They returned to normal values within six months post-exposure. In contrast, at the high exposure level, increased lung weight, decreased alveolar clearance and a disproportionate increase in toner retention, as well as an inflammatory response, were noted, which persisted throughout the post-exposure interval. While no significant histopathological changes were noted at the end of exposure, a very slight degree of fibrosis was observed in all of the animals in the high exposure group, after 65 weeks of observation. All of the above alterations are ascribable to "lung overloading", a generic response to excessive amounts of any dust retained in the lungs for a prolonged time interval. Published accounts in the toxicology literature document that long-term inhalation of large quantities of even innocuous particles such as Ti02, carbon black, petroleum coke, toner, and other polymeric and insoluble materials has resulted in a spectrum of generically similar pulmonary changes. Scaling of the rat-data, using 1 mg dust/g of lung as a threshold for "lung overloading", normal ventilatory parameters and 300-500 day human retention halftimes project "lung overloading" upon long-term exposure to insoluble respirable dust above 0.2-0.33 mg/m3. Other types of information are consistent with an exposure limit in the range of 0.4-1.0 mg/m3 for respirable dust. The absence of definitive toxicology data in support of the current OSHA respirable nuisance dust limit, coupled with the lack of sound epidemiology data, indicate the need to reexamine the validity of the current nuisance dust health standard.

Jan 1, 1991

In the early days of minimal environmental protection awareness and unreasoning economy development pressures, little attention was paid to growing environmental concerns in Fuxin colliery, especially the air pollution problem due to the long term mining activities. In order to determine air quality concentration levels, a new technique for synthetic assessment of ambient air quality by using the extension of matter-element method is proposed in this paper. The air pollutants data such as Sulphur Dioxide (SO2), Carbon Monoxide (CO), Nitrogen Oxides (NOx), Total Suspended Particulates (TSP), Particulate Matter (PM10), and dustfall collected at four different air quality monitoring stations located in four districts of Fuxin colliery is used. The results obtained indicate that TSP, PM10, dustfall and SO2 are the predominant pollutants. Other pollutants such as CO and NOx are also detected in Fuxin colliery. The air pollution comes mainly from industrial emissions, mining activities and the abandoned gangue stockpiles. Compared to those applied to other mathematical assessment methods, it is demonstrated that the extension of matter-element model is quite appropriate for air quality assessment.

Jan 1, 2006

By O. A. Bascur

In recent years, metal-producing companies have increased their investment in automation and technological innovation, embracing new opportunities to enable transformational change. Transformation to a digital plant can fundamentally revolutionize how industrial complexes operate. The abundant and growing quantity of real-time data and events collected in the grinding and flotation circuits in a mineral processing plant can be used to solve operational issues and optimize plant performance. A grade recovery model is used to identify the best operating conditions in real time. A strategy for increasing the value of instrumentation in current plants is reviewed. An optimal Gaudin size distribution model provides augmented information from traditional sensors to find the optimal grind cut size to reduce metal losses in the flotation circuits. Sensors in flotation circuits enable an estimate of the recovery and determination of the optimal froth depth and aeration using an air hold up flotation model. A strategy of classifying data for online generation of insights to using operational intelligence tools is described. The implementation of a recovery/grind strategy with industrial examples in nonferrous mineral processing is presented.

By Roger J. Hornberger, Paul F. Ziemkiewicz, Dirk J. A. vanZyl, Gene E. Krueger, Harry H. Posey, Kim A. Lapakko, Charles H. Buckmam

The Acid Drainage Technology Initiative (ADTI) was initiated in 1995 by federal agencies, the National Mining Association and the Interstate Mining Compact Commission to identify, evaluate and develop cost- effective and practical acid drainage technologies. In 1999 ADTI was expanded through the addition of the metal mining sector group, which began organization efforts in 1998. ADTI addresses drainage quality issues involving metal mining and related metallurgical operations and acid drainage from coal mines, for abandoned, active, and future mines. ADTI is a technology development program. It is not a regulatory or policy development program. The guiding principle of ADTI is to build a consensus among industry, federal and state regulatory agencies. ADTI is focusing these efforts on technology development and technology transfer in the areas of mine drainage sampling/monitoring, prediction, avoidance/remediation and modeling.

Jan 1, 2000

By Patricio A. Espinoza, Aldo Casali, Cristian Ardiles, Guillermo González

Cluster analysis is used to design grade soft-sensors in a rougher flotation plant and a ball mill overload soft-sensor. Soft-sensors are virtual sensors which either replace unavailable actual sensors or infer measurements for non existing sensors. In the case of the grade soft-sensors clustering serves to determine clusters of related operating points. To each cluster there corresponds an ARMAX model structure whose parameters are estimated using only the points in the corresponding cluster. Thus a much better correlation is found than if all the data points were used for a global model. The problem of identifying clusters when the measurement of the real sensor is not available is addressed. In the case of the overload soft-sensor, variables were selected which are related to overload, either from a phenomenological point of view or according to operator experience. Different clusters are formed, some of which are identified as determining an overload condition or a possibility of such condition. Each of these clusters has a set of operating conditions which suggests the corrective action to be taken when necessary. Both kinds of soft-sensors are tested with industrial plant data and promising preliminary results are obtained.

Jan 1, 1995

By D. K. Jorgensen

The Bullfrog and Montgomery-Shoshone deposits, near Beatty, NV, have a combined drill-indicated reserve of 15.8 Mt (17.4 million st) of ore. Average grade is 3.5 g/t (0.103 oz per st) gold and 8.2 g/t (0.24 oz per st) silver. The deposits occur in Miocene volcanic rocks that underwent large-scale movement within a detachment-faulted terrane. The principal host to gold mineralization is a strongly welded rhyolitic tuff that experienced brittle deformation during plate movement. Open space fractures and breccia were filled with quartz, calcite, and adularia accompanied by lesser pyrite, gold, and acanthite. Gold occurs as micrometer-sized particles within and adjacent to the low-angle fault and along associated listric-normal and tear faults. The Bullfrog and Montgomery-Shoshone are volcanic-hosted, detachment fault-related, epithermal quartz calcite stockwork gold deposits. Bullfrog's minable reserve is 13 Mt (14.3 million st) of ore grading 3.8 g/t (0.11 oz per st) of gold. At Montgomery-Shoshone, 2.7 Mt (3 million st) minable tons at 2.5 g/t (0.072 oz per st) are present. Preproduction stripping has begun at the Bullfrog ore body. A 7.7-kt/d (8500-stpd) carbon-in-pulp (CIP) mill is under construction. In 1990, Bond Gold expects to be producing about 6.2 t/a (200,000 oz per year) of gold.

Jan 1, 1990

By J. E. Hoffman, Massimo Maccagni, T. J. Keefe, Marco Olper, O&apos

The research laboratory of B.U.S Engitec has identified and patented a new process for electrolytic production of lead from lead sulphide concentrates with simultaneous production of elementary sulphur. The process occurs in an aqueous solution, at atmospheric pressure, utilizing a solution of ferric fluoroborate in fluoroboric acid as the oxidizing and solubilizing medium for lead sulphide. After the filtration and separation of a residue composed of elementary sulphur and the gangue which accompanied the concentrate, the solution containing lead as fluoroborate and iron reduced to a ferrous state is sent to a diaphragm electrolytic cell where, in the cathode compartment, the lead is deposited in a compact form on the stainless steel permanent blank. The exhaust solution stripped of lead is sent to the anode compartment where the oxidation of ferrous fluoroborate into ferric fluoroboratetakes place, reproducing the oxidizing solution for new leaching. Depending on operating conditions, it is possible to selectively solubilize the lead from the other metal values present in the concentrate. The sulphur produced from the reaction may be separated from the gangue by extraction with solvent or by flotation.

Jan 1, 1993

By Gunter Zimmermeyer, Hartmut Eicker

Radon in the Environment Radon, as a natural nobel gas, can be detected nearly everywhere in the environment as a decay product of ubiquitous uranium. As it is emanated from soil and rocks measurable concentrations have been found at the surface of soils and in even higher concentrations in enclosed spaces like, for example, mines and buildings. While above soil surface activities caused by radon have been found in an order of magnitude of up to 1 pCi/l (Weigel, F. 1978), concentrations in enclosed spaces and mines are higher because of the lack of atmospheric circulation. Beside air circulation the relevant figure depends on the Ra226-concentration in the surrounding rocks or building material, as well as on emanation coefficient and the diffusion coefficient. While representative Rn222concentrations in well ventilated buildings are reported to be in an order of magnitude of 1 pCi/l maximum values up to one order of magnitude higher have been found in badly ventilated brick buildings (Ettenhuber, E., Lehmann, R., Clajus, P., 1978) (Aitken, J.H., et al., 1977). Just now it was stated that the reduced air circulation due to German legal regulations on energy conservation will increase radon exposure of the public considerably (Jacobi, W., 1979). Radon in Mines Radon exposure of workers is, of course, a matter of concern in uranium ore mines where relatively high concentrations of the uranium to be mined are present. Measures to protect workers' health have been implemented, based on experience on dose-effect relationship. They serve to meet exposure standards by limiting inhalation of radioactive particles, in reducing radon concentrations or in limiting working hours. Both improved measuring devices and capacity as well as the lower discrimination threshold enable to measure radon concentrations in other mines, e.g. in coal mines. It is known that radioactivity in coal is small compared with that in other minerals and even soil, rocks. Nevertheless, radioactive elements were identified in coal and so the question was whether the concentrations of radon in coal mines might be a subject of concern. The problems encountered when measuring radon in coal mines are described below, as the measuring device has to be flame proofed which is an important additional requirement. Measured radon concentrations in British coal mines have already been published (Duggan, M.J., Howell, D.M., Soilleux, P.J., 1968 (Dungey, C.J., Hore, J., Walter, M.D., 1978). The authors found concentrations of up to 14 pCi/l in Cornish mines. In most cases the values were in the order of 2 pCi/l. These results were consistent with measurements reported from U.S.-coal mines (Lucas, H.F., Gabrush, A.F., 1966). Such concentrations of radon were not considered to represent a hazard for British miners (Ogden, T.L., 1974). In Germany, too, first measurements have been carried out in five coal mines in the Saarland in the 60's. Air samples were taken at different places in the coal mines, dried, fed to an ionisation cell and measured by a device including reference cells. Samples taken at ventilated places showed radon concentrations consistent with the lower British results. They all kept within the standards of the first German regulation on protection against radiation. Measuring the radon daughters was renounced because of the relatively low radon concentrations and the requirements for flame proofness in coal mines. Moreover, it can be ascertained that because of the effective ventilation the disequilibrium factor between the decay products and the radon concentration remains far below the value of one (Muth, H., 1978) (Keller, G.). In 1979 the committee on mine safety and health protection in coal and other mines of the EEC proposed to have measured and evaluated radon concentrations in European coal mines to find out whether they complied with international standards. Great Britain and Germany agreed to this proposal and by commissioning such measurements to scientific institutes complied with the request to harmonize the methods used. In the Federal Republic of Germany, e.g. Westfälische Berggewerkschaftskasse (WBK) and Staatliches Materialprüfungsamt; Dortmund (MPA) were requested to carry out the measurements in coal mines of the Ruhr coalfield whereas Saarberg Interplan was responsible for the Saar coalfield. The WBK measurements are reported in later paragraphs.

Jan 1, 1981

By K. H. Al-Rawahy

Mineral resources comprise of metallic, non-metallic, and fossil fuels. Our civilization, and the associated economic and industrial developments are inherently dependent on the availability and use of minerals. This is evident from historical development and identification of civilization eras throughout human history: the stone age, the iron age, the bronze age, and the current computer age. This paper deals with the depletable fossil fuel sector of minerals; this is represented by crude oil, natural gas, and coal. Fossil fuels provide approximately 80% of total global primary energy supply; the rest being provided by renewables (wind, hydrothermal, solar), nuclear, and biomass. Economic, industrial, and population growth will, inevitably, lead to an increase in demand for energy. In general, per capita energy consumption is correlated with per capita income, with the US showing the highest energy use per capita, and South Asia having the lowest. This paper examines the underlying interrelated issues (factors) of energy reserves, production, scarcity, depletion, economic, and technological factors and impact on long term availability and thus sustainability. Is it possible to extend the time to economic depletion of these resources? This will have an impact, direct or otherwise on total energy availability, and the inter-temporal allocation of the resource. Specific economic and physical parameters relevant to mineral supply and their respective impact on depletion, and inter-temporal welfare are investigated. These variables include own price, substitute price, population, income, technical innovation-both on supply as well demand, and resource substitution.

Jan 1, 2007

By J. Fox, C. Allen, A. Greth, K. Kocsis

"It is the duty of the mine operator to ensure the mine environment is healthy and safe for the mine workers. For deep and hot underground mines, this requires maintaining adequate working temperatures by means of mitigating the heat load generated by strata, auto-compression, mining equipment, explosives, ground water, and human metabolism. The heat load is best reduced by minimizing the amount of heat transferred to the mine air from these sources and through the use of efficient ventilation with effective cooling systems. The heat emitted by mining equipment and vehicles contribute a significant proportion to the combined heat load of an underground mine. This is especially a problem for diesel equipment due to the fact that besides heat, a large amount of water vapor is produced, which increases the humidity in the production workings. Diesel engines have proven advantageous in recent history due to their high power output and reliability. However, as mines continue to become more mechanized and deeper the climatic problems introduced by elevated heat generation will continue to rise. With that, the issue of heat generated by diesel equipment must be addressed. The economic alternative for diesel engine equipment fleets in underground mines is the electric engine. Technological advances in battery technology, increased mechanical output and improved reliability have made the electric engine significantly more competitive in comparison to diesel engines. Because electric engines do not utilize internal combustion, the heat produced by them is significantly less than of the diesel engines. Battery powered mining equipment likewise eliminate diesel particulate matter (DPM) produced by diesel engines. Utilizing battery electric equipment in underground mines provides many advantages, such as: (a) reduced heat load, (b) healthier and safer environment for the mine workers, and (c) reduced mine operating costs due to lower ventilation requirements. This paper will highlight the health and cost benefits of using battery/electric fleets versus diesel fleets in deep and hot underground mines. The study analyzes simulations produced from thermodynamic ventilation models. Early simulations show significant cost reductions in terms of net present value (NPV) when comparing the air volume requirements for battery/electric equipment versus diesel powered equipment for the same production rate. INTRODUCTION The competitiveness of the world mineral market demands that mine operators continue to increase production and decrease costs as commodity prices fluctuate in often unplanned directions. This has forced underground mines to operate at deeper depths and to become more mechanized to remain competitive. Because of these changes, ventilation challenges have continued to increase as the mines combat an enlarged influx of contaminants such as heat and diesel particulate matter (DPM)."

Jan 1, 2018

By H. T. Kang

Various geological anomalies are encountered in underground longwall mines, and they cause stability problems. In this study, a number of detailed two-dimensional finite-element models were made, consisting of mine floor, roof, coal seam, shield structure, gob, etc. to analyze the influence of geological anomalies on longwall shields. Two different categories of anomalies were simulated. The first ones are shear zone and sandstone channels, with variable sizes and locations in the roof. The second category is fault or fracture plane, with variable friction factors, locations, and orientation of the fracture plane. The results of the analyses are' integrated with an artificial intelligence system for developing a forecasting guideline for prevention of underground hazards due to the existence of geological anomalies.

Jan 1, 1996

By Michael DiMatteo, Michael D. Gardner, Eric F. Perry, John K. Felbinger, Robert S. Evans

A hydrologically isolated surface coal mine was reclaimed using acid material handling, alkaline addition and ground-water management techniques. Eight pit floor drains were installed during reclamation to intercept ground-water flow in the mine backfill and minimize water table buildup. All drains began flowing within six months of installation. Water quality and ground-water discharge have been monitored for four years after mine closure. A thin water table aquifer about five to seven feet thick has developed in minespoil about 20 to 40 feet thick. Ground-water flow direction is largely controlled by geologic structure and the drains. Median ground- water discharge is about 0.43 gallons per acre per minute, and varies an order of magnitude between wet and dry seasons. About 19 % of precipitation enters the aquifer as recharge. Seven of the eight drains typically discharge net alkaline water. Alkalinity is produced continuously and concentrations are highest during dry periods. Conversely, sulfate and acidity concentrations increase during wet periods as slugs of accumulated acid products are leached. Overall water quality is controlled principally by minespoil geochemistry and added alkaline material. The drains have successfully directed ground-water to a planned discharge area. Without the drains, a ground-water mound was expected to form against a buried highwall and discharge over a large area.

Jan 1, 2000

Last year in the US alone, about 425 Mt (468 million st) of minerals and coal were beneficiated by froth flotation. This number indicates that from 1983 there was a 10% increase in tonnage of min¬erals and coal beneficiated by the indus¬try. A significant improvement was seen in the tonnage processed by the nonferrous minerals and coal industries. BP Minerals America installed 85 m; (3000 cu ft) flotation cells at the Bing¬ham Canyon mine and concentrator. The new flotation circuit has fewer than 100 cells compared to 2000 flotation cells used in the old plant (Mining Engi¬neering, November 1988). Column flotation use on a commer¬cial scale continues to expand as seen from the interest expressed at the Col¬umn Flotation Symposium (Column Flotation '88). The Magma Copper Co., San Manuel Division replaced all con¬ventional cells with 1.8 x 12 m (6 x 40 ft) column flotation cells for copper con¬centrate cleaning. Also, 1220 mm and 760 mm-diam (48 in. and 30 in.-diam) column cells are operating at the plant in the molybdenum circuit. A commercial Diester Flotaire col¬umn cell for fine coal recovery was installed at the United Coal Wellmore No. 20 plant. The 36.8 m3 (1300 cu ft) cell recovers 13.6 to 18 t/h (15 to 20 stph) of -590 gm (-28 mesh) coal. A similar unit has been installed at Tanoma Mining Co. in Pennsylvania. Various modifications of the column cells are being designed around the world. Jameson (Mining and Metal¬lurgy, 1988) described a new concept whereby the feed and air stream mixture is discharged into a cylindrical column of about 1.2 m (4 ft) height. Recovery and grade of nonferrous minerals have been reported to be better than that in a four-stage conventional flotation clean¬ing circuit. Flotation reagents American Cyanamid and Dow Chemical continued development of a new generation of sulfide collectors. A general feeling is development of new sulfide collectors has not kept up with flotation technology. Additionally, joint efforts between industry and chemical suppliers will likely be necessary to realize the economic benefits of the new technologies, since new chemistries respond differently compared to the conventional collectors. Flocculant development in recent years has been evolutionary rather than revolutionary. Rothenborg reported on development of a new flocculant family (a hydroxymated polyacrylamide desig¬nated S-6703) that has shown consider¬able promise in red mud clarification. Plant testing showed that this new floc¬culant could replace starch and poly¬acrylate and provide significantly higher overflow clarity. Barol Kami (Siirak) and Cleveland¬Cliffs (Hancock) reported development of an amphoteric apatite collector (ATRAC 873) that was used in Tilden's silica flotation process to increase apatite rejection. The collector was engineered for the particular flotation conditions in the complex Tilden process. Significant plant testing with ATRAC 873 showed that this reagent gave significantly in¬creased apatite rejection without any effect on silica flotation effectiveness or selectivity. Electrostatic separation Electrostatic separation is now em¬ployed in the precious metals mining industry to recover gold and silver grills from crushed slag. The installation at Paradise Peak has prompted other op¬erators to consider this application. In another development, attractive potentials for treating very fine minerals (-45 µm or -325 mesh) are being devel¬oped by Advanced Energy Dynamics and by the Department of Energy. Demonstration tests using triboelectric charging/electrostatic separation have been successful on a variety of minerals as well as coal. Magnetic separation Developments in magnetic separa¬tion have transpired on a production scale. Superconducting, high gradient magnetic separation has gained accep¬tance with the successful startup of a second unit treating kaolin at J.M. Huber Corp. This liquid-helium-cooled mag¬net generates 2.0 tesla in a 3-m-diam (120-in.-diam) bore with no power con¬sumption. Wet, high-intensity magnetic separation has been applied to sulfide mineral separations both domestically and abroad. These continuous type of separators are effective in removing residual chalcopyrite and sphalerite from other base metal sulfide concentrates. Separators using high energy rare earth permanent magnets are continu¬ally increasing. Now offered as both drum and roll type, these units are be¬coming a staple in the processing of industrial minerals. Tests using rare earth magnets strategically placed on a spiral concentrator have demonstrated the enhanced recovery of heavy miner¬als such as ilmenite. Classification Although no major technology break¬throughs in classification appear immi¬nent, there is an increasing need for more efficient and cost-effective meth¬ods to make size separations. It is be¬coming more apparent that mineral concentration methods will be more common at very fine sizes, say below 50

Jan 1, 1989

By C. L. McKenzie, R. A. Heig

The design and operation of metallurgical laboratories is discussed. Laboratory size, general laboratory equipment and metallurgical staffing are discussed from a standpoint of desired laboratory results.

Jan 1, 1986

By T. B. Whitmoyer, J. E. Sneckenberger, M. A. Jerabek, C. F. Stanley

The measurement of acoustic impedance at frequencies up to 6,400 Hz has been proposed as a diagnostic tool to yield more detailed information about lung condition. A three generation branching system of plastic Y-tubes has been constructed. The impedance of the branched system is measured by an impedance tube using the two-microphone technique. The impedance spectrum is used to calculate the reflection coefficient spectrum, which is converted to an impulse response by an inverse FFT. The area function is extracted from the impulse response by the Ware-Aki algorithm. Measurements of acoustic impedance of the branched system were made for several different end conditions of the eight terminal outlets. The outlets were either blocked with modeling clay, plastic packing material, or aluminum blocks or were unblocked. Six measurements were made of each configuration. In general, the more outlets blocked, the larger the shift to the right of the impedance magnitude peaks for frequencies above 3000 Hz. The impedance magnitude peaks for the plastic packing material were shifted in frequency to the right relative to the peaks of the other system terminations. The impedance magnitude peaks for the clay and aluminum system terminations were significantly different in magnitude but not shifted in frequency. The area functions at the end of the branched system were significantly different (a > 99%) for most of the end conditions. Area functions for the modeled branched lung systems between the end of the impedance tube and the termination outlets of the branched system were similar but distinctively different for the various end conditions. These results indicate that the two-microphone technique can sense small changes in the terminating end conditions of a rigid system of branched tubes and thus may sense impedance changes due to lung disease in the conducting airways. Keywords: acoustic impedance, lung model, area function.

Jan 1, 1991

By Ron Jackson

The report gives a general method for the geological evaluation of a gold deposit. Recognizable parameters associated with gold mineralization are used to develop a model of an orebody. The California Mother Lode is used as an example.

Jan 1, 1987

By B. M. Sadashiva Murthy

Increasing quantities of nutrients and pesticides in agricultural runoff in recent years has caused the more developed western nations to become concerned about diffuse agricultural pollution. Thus, the problem of diffuse pollution is of greater importance and concern for any integrated water quality management programme. The above mentioned sources and activities causing pollution to groundwater cannot be completely avoided. The best solution is to entail a firm understanding of the principles of solute transport through porous media. The complex factors that control the movement of contaminants in porous media and the resulting behavior of contaminant plume are usually intricate to assess because of interaction of many factors such as dispersion, advection, sorption, degradation, volatilization, etc. As accurate quantification of solute under field conditions is inherently difficult, the fate of nitrate and phosphate have been analyzed in laboratory column and channel studies. From the analysis of the breakthrough curves, the dispersion co-efficient for nitrates and phosphates through sandy soil was found to be 0.262 m2/d and 0.114 m2/d for column studies, 0.321 m2/d and 0.231 m2/d for channel studies respectively. The column studies revealed that the concentration of nitrates and phosphates increased steadily in the first few days (around 5 days) and then it increased rapidly after 8 to 10 days. However, it attained equilibrium after 20 days. Similarly, the channel studies revealed a steady increase in concentration of nitrates and phosphates in the first few days (1 to 2 days) and rapid increase up to 15 days and there after it attained equilibrium. In the study, one-dimensional analytical model has been developed which include the advection, dispersion, and a characteristic term called ?total elimination rate?. The comparative study of column and channel studies, and model output (in which the term total elimination rate ?K? is considered as zero) exhibited a variation of 30 to 50 % in leaching characteristics of pollutants (nitrates and phosphates).

Jan 1, 2008