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By Flaviani Marculano Marchesi, Silas Gambarine Soares, Elton Volkers do Espírito Santo, Felipe Fardin Grillo, Heitor Cristo Clem de Oliveira

O objetivo deste trabalho é utilizar a termodinâmica computacional para estudar as propriedades de escórias iniciais dessulfurantes utilizando misturas com diferentes fluxantes: fluorita, sodalita, borra de alumínio, B2O3 e ilmenita. A princípio, as misturas foram definidas e em seguida foram realizadas simulações para o aquecimento dessas misturas a 1350 ºC por meio do software FactSage 7.2. Assim, foi calculado o fator de dessulfuração (FDeS) para cada mistura com base nas condições de equilíbrio. As misturas contendo 5 e 10% de fluorita e 5% de sodalita foram as que apresentaram maior FDeS. Em contrapartida, as misturas com 10,15 e 20% de B2O3 tiveram os piores resultados nessa análise. Misturas da literatura também foram simuladas a fim de se obter o FDeS e relacioná-lo com a eficiência.

Oct 1, 2019

By M. F. Lopez, A. J. Mattus, S. B. Magid, D. B. Mobbs

"The use of Caro's acid as a replacement for hydrogen peroxide for the oxidation of vanadium prior to solvent extraction resulted in a 56% reduction in oxidant usage when compared on an equivalent hydrogen peroxide basis. Comparative oxidation tests, using two actual uranium mill raffinates, resulted in premature precipitation of an amorphous ferric vanadate when hydrogen peroxide was used to oxidize one of the raffinates containing a high iron to vanadium ratio. The use of Caro's acid eliminated the precipitation problem, thereby permitting the adjustment of the raffinate pH to a higher, more favourable level prior to solvent extraction.Potentiometric characterization of the raffinates revealed that vanadium is responsible for the inefficiency of hydrogen peroxide compared with Caro's acid, with the oxidation efficiency of iron being the same for both oxidants. A limiting potential between 720 and 740 mV was observed when using hydrogen peroxide, while, when using Care's acid, potentials approaching 1200 mV were achievable.A four-stage, countercurrent extraction performed on the oxidized raffinates did not reveal any operational problems. The extraction efficiency and the extraction coefficient were found to be higher when Caro's acid was used as the oxidant, as opposed to hydrogen peroxide.IntroductionMost vanadium is recovered as a by-product of some other process: leaching of Carnotite uranium ores, oil fly ash, phosphate rock or chromite processing. The major source of vanadium has been from uranium mills incorporating acid leaching of Carnotite ore s at elevated temperatures and pressures. The by-product recovery of vanadium from uranium ores of the Uravan Mineral Belt, located in the Colorado Plateau , is a common occurrence when vanadium recovery is economically viable."

Jan 1, 1983

Jan 1, 2005

By S. Castro

The aim of the present paper is to review the current technologies for arsenic removal in the copper metallurgical industry, and to show the progress made with some promising emerging strategies, involving the pre-treatment of copper-arsenic concentrates by selective flotation or by alkaline leaching with Na2S-NaOH solutions. The advantages of alkaline leaching are the selective dissolution of arsenic and antimony, the high extraction yield, and the practically nil loss of copper, which remains in the clean copper concentrate as a CuS residue. Alkaline ?cured? ? a procedure similar to ?acid-cured? in conventional leaching ? improves arsenic extraction and reagent consumption, making this an interesting technology for the treatment of high As-Sb concentrates. In light of recent advances on the selective flotation of enargite and tennantite, the importance of redox conditions to control the flotation/depression of enargite-tennantite from copper sulfides has been well established. However, problems of selectivity must still be solved. Additionally, the limitation imposed in some cases by the need to recover the molybdenum by-product must be considered. The application of selective flotation to obtain a high-arsenic or ?dirty? concentrate and its sub-sequent treatment by the alkaline leaching process is suggested.

Jan 1, 2014

By E. V. Cilento, R. C. Laotz, K. A. DiGregorio

"PULMONARY ALVEOLAR macrophages (PAM) protect the lungs by providing a first line of defense against inhaled foreign debris and bacteria. In this role PAM phagocytize foreign matter, secrete enzymes that augment microbial killing and digestion, and produce reactive oxygen me-tabolites (2, 3, 18, 19, 22, 26). However, in addition to this antibacterial function, PAM participate in a diversity of functions, such as tissue repair, lipoprotein metabolism, and immunoregulatory activities (11, 22).Studies have suggested the existence of a heterogeneous population of PAM with respect to immunologic function, enzyme release, phagocytosis, morphological characteristics, expression of membrane receptors, ad-herence, and superoxide (O2•) release (4-7, 10, 16, 21, 23, 28). This heterogeneity has been observed by analyz¬ing subfractions of PAM separated by cell density frac-tionation. For example, using guinea pig PAM, Dauber et al. (7) showed heterogeneity in cell density and size, morphological characteristics, and cytochemical properties, whereas Holian and co-workers (16) reported variations in migration, chemotaxis, O2• release, and pinocytosis among subfractions collected. Similarly, O'Neill et al. (21) observed functional heterogeneity in rat PAM with regard to phagocytosis, O2 • release, and lysosomal enzyme activity.Several investigations have reported a correlation between PAM activity and cell volume. Most studies have shown that O2 release from PAM increased with decreasing cell size (15, 21, 25), although Bielefeldt Ohmann and Babiuk (4) reported a decreasing trend. However, Gallin (13) has suggested that significant variability may even exist within density-defined or cell-volume subfractions that could lead to misinterpretation of results concerning PAM heterogeneity.A better understanding of the heterogeneity in O2 production may be obtained by using single cell meas-urements to evaluate whether functionally distinct sub-populations actually do exist. As such, the present study was designed to examine heterogeneity in O2 • release from single PAM using a recently developed electrooptical technique (8). The initial oxygen metabolite, O2•, produced by NADPH oxidase at the surface of the plasma membrane, was measured by quantifying the reduction of nitro blue tetrazolium (NBT I to a diformazan precipitate. Measurements were made from video recordings of individual cells stimulated by their adherence to the bottom of a culture dish. The cell volume and degree of spreading also were determined directly from the same video recordings, and the data were correlated with the initial rate and maximum amount of diformazan produced by the same cell."

Mar 1, 1992

By Walter R. Storms

"INTRODUCTION Geological examination of the Iron Mountain beryllium deposits was begun by a field part 3/ of the Federal Geological Survey in May 1942. Later in that month the occurrence was examined by the author and C. H. Johnson, of the Bureau of Mines, and a preliminary exploratory program was outlined. Trenching and sampling began about June 15 and were completed in July 1942. A large tonnage of beryllium-bearing material was indicate by this preliminary survey, so that additional funds wore allotted for further trenching and sampling, underground exploratory work, and diamond drilling. This later program was initiated in July 1942 and was completed in May 1943. 4/ACKNOWLEDGEMENTSIn its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilisation of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R.G, Knickerbocker, chief, analyzes samples and performs beneficiation tests."

Mar 1, 1947

By William X. Chavez

The Mantos Blancos copper-silver district, a major copper-producing area since 1961, is located on the Tropic of Capricorn about 45 kilometers northeast of the northern Chile port city of Antofagasta, as shown in Figure 1. Copper oxide minerals occurring as atacamite (Cu C1(OH)3) and chrysocolla (copper silicate-hydrate) were discovered in the district in the early 1900's (Knobler and Joseph, 1962). The mine is situated in the northern Atacama Desert, one of the most arid regions on earth, and presently receives less than 1 cm per year of precipitation. The extreme aridity of the Atacama Desert is thought to have prevailed since at least Middle Miocene time (Mortimer et al., 1978) when development of important supervene copper enrichment was slowed in many areas of northern Chile (e.g., Chuquicamata, Exotica). Despite the paucity of precipitation, landform development is mature, with large alluvial fans and alluvial-filled valleys covering much of the region. In addition, the aridity and presence of salts have led to the formation of a sub-surface cementing of alluvium and colluvium by halite-rich caliche ranging from a few centimeters to over 3 meters in thickness. These factors, resulting in poor outcrop exposure, make even reconnaissance mapping difficult.

Jan 1, 1983

By Irving Hartmann, John Nagy

"The pressures produced by dust explosions are frequently so great and are developed so rapidly that widespread destruction of manufacturing equipment and buildings results. Experimental data on maximum pressures and rates of pressure rise produced in a closed vessel by numerous metal powders and by dusts used in the plastics industry were published in two previous Bureau of Mines papers.4/5/One means for reducing structural damage is provision in the enclosing walls and/or roof of rapidly opening explosion-relieving devices or relief vents through which the pressure of an incipient dust explosion can be quickly dissipated. The vents can be simply unrestricted or free openings: hinged or pivoted sash which swing outward at a predetermined internal pressure; fixed sash, with light wall anchorages; scored glass panes; light wall panels; monitors or skylights; poppet-type vent closures; paper, metal foil, or other diaphragms that burst at low pressures; pull-out diaphragms, or other similar arrangements.The use of pressure-relief vents is recommended in the dust-explosion codes of the rational Fire Protection Association,6/ and recently a special committee on explosion venting has been organized. However, technical data on which the design and distribution of relief vents can be based are meager. An experimental study on venting grain-dust and cornstarch explosions was made by the Bureau of Chemistry and Soils, United States Department of Agriculture.7/ Tests on cork fines, cinnamon, starch, barley dust, and a phenolic plastic were made in a laboratory-scale (0.1-cubic-foot) apparatus by the engineering department of the Factory Insurance Association.8/ A study on the venting of explosions of acetone-air mixtures was made by the Bureau of Mines.9/The object of the present investigation is to extend the limited knowledge on the effectiveness of pressure-relief vents of different types, shapes, and sizes. The aim is to determine the venting requirements in equipment and structures of various dimensions and shapes for dusts of widely different explosive properties. On the basis of such accumulated information, together with theoretical considerations, it is hoped that ultimately it will be possible to recommend correct venting for most operations in which a dust-explosion hazard exists."

May 1, 1946

By L. R. Burdick

This paper presents a review of published investigation dealing with the importance of sulfur compounds in the deterioration of materials or providing some basis for estimating the extent of loss shareable to such air pollution. Materials included are cement, stone, metals, paint, leather, paper, sand cloth. The investigations may be divided into two classes, one of the laboratory type in which the sulfur content and the humidity of the air were controlled and the other dealing with the exposure of materials to atmospheres not under control. The first type of work has shown that cement is subject to deterioration by the action of sulfur dioxide gas. The experiments with stone indicate that although limestone takes up sulfur dioxide, from the air, moist sulfur dioxide-air mixtures alone cannot be used for establishing- the comparative weathering- qualities of the different types of stone by accelerated test methods. Laboratory tests indicate that sulfur compounds in the air accelerate the corrosion of iron, steel, zinc, copper, and nickel at normal air temperatures and at certain relative humidities. It has also been indicated that certain types of paint are, affected by high sulfur dioxide concentrations, and that paper is attacked by sulfur dioxide in the atmosphere. The investigations of the second type show the amount or variation of corrosion in different localities and under different types of exposure. The investigations (10) (18)4/ during which sulfur determinations were made indicate that sulfur dioxide is a main controlling factor in the corrosion of iron and steel but according to Quick (18) may not be for some nonferrous metals. In general, the laboratory tests do not Jive definite data on the loss due to sulfur compounds at the concentrations normally found in the air. The data from atmospheric exposures are not complete from the standpoint of the exact effect of the sulfur compounds. Damage to materials so exposed is affected by factors such as other chemical contaminants, humidity, rainfall, solid deposits, and sunlight. A simple scheme has been devised in Great Britain which is considered to provide a measure of the attack of sulfur compound, on building materials (1). Small cylinders coated

Jan 1, 1939

By GJ Hundman

The Multiple Unit Continuous Haulage (MUCH) System was designed to provide the capacity to continuously convey coal from the mining machine to the main haulage belt. The MUCH System has an operator who steers the lead vehicle, ever following the mining machine. All the remaining vehicles follow the path of the lead vehicle, with their conveyors automatically lining up between the lead vehicle and mine section panel belt. This is accomplished by mechanical linkages on the vehicles which are interconnected by steering bars between vehicles (patent pending). The MUCH System has an operator who steers the discharge vehicle when outby travel is required. Outby travel is just like inby, with each vehicle following the path of the preceding vehicle. Surface tests overwhelmingly indicate the "UCH System should track/retrack successfully in square pillar underground room and pillar coal mines with 18 ft. wide entries and slopes up to 10 percent. For 60 degree pillar plans the minimum entry width required is 15 ft. Surface tests also indicate the MUCH System will convey over 8 TPM of coal around 90 degree corners without excessive spillage.

Jan 1, 1983

By K. A. Johnson, H. F. Yancey

"INTRODUCTION Coals vary so widely in their burning characteristics that all coals prepared for domestic stoker use cannot be burned efficiently on every type of stoker. The overfeed stoker, a large number of which are in use in the Pacific Northwest, operates satisfactorily when burning low- to high-ash, noncaking bituminous or subbituminous coals, whereas on the clinkering-type, underfeed, bituminous stoker both caking and noncaking bituminous and subbituminous coals are burned, generally with ash contents below 12 percent and ash-softening temperatures between 1,800º and about 2,600º F. Because fly ash continues to be one of the most troublesome factors in domestic underfeed stokers, noncaking coals especially must be chosen carefully with respect to size composition, particularly as regards the exclusion of excessive fines. Their formation as a result of degradation in storage handling or because of crushing in .the stoker worm will increase the fly-ash nuisence.Bituminous and subbituminous coals with higher ash-softening temperatures and, often, higher ash contents have not been able to enter the domestic stoker-coal market in the Pacific northwest because clinkers are not formed readily during clinker-type underfeed-stoker burning, especially in mild weather, and because of the labor and attendant inconvenience required in handling larger volumes of ash. The work described in this report was undertaken to enable mines producing coals of the kind described to enter the stoker-coal markets. The anthracite stoker selected was one that conveys the refuse from the ash pit of the furnace and deposits it into one of two covered, dust-tight disposal cans."

Dec 1, 1945

By T. S. Washburn

THE grades of commercial steel produced in large quantities can be divided into two general types from the standpoint of ingot structure-killed and rimmed. Killed steel covers a wide variety with carbon contents throughout the range of the steel portion of the iron-carbon diagram, and is the kind usually used in the production of alloy steels. Rimmed steel is normally associated with carbon ranges under 0.30 per cent, and is not yet used to a large extent in alloy practice, except for copper-bearing steels. The fundamental differences in the ingots made from these two types of steel can be seen most easily in Figs. 1 to 7. In the rimmed ingot shown in Figs. 5 to 7 there are two lines of blowholes approximately parallel to the sides and coming together at the top and at the bottom of the ingot. In the killed ingots shown in Figs. 1 to 4 these blowholes are not present. Also, the rimmed ingot has no well defined pipe, as com-pared to the deep pipe on the killed ingots, and there are numerous pri-mary blowholes in the lower portion of the rimmed ingot perpendicular to the surface and close to it, while on the killed ingot there are no blowholes of this type in the ingot shown in Fig. 1 and very small ones close to the surface in the lower part of the ingot shown in Figs. 2 to 4. With respect to the presence of pipe and the primary blowholes, the structure may vary considerably in both rimmed and killed ingots, therefore these cannot be considered as fundamental structural characteristics differ-entiating the two types of steel. The primary blowholes in rimmed ingots may be much less pronounced than those in the ingot shown in Figs. 5 to 7-as, for example, in "ingot iron," which is entirely free from them. An example of a cross section of an ingot-iron ingot is shown on page 16 of "Research and Methods of Analysis of Iron and Steel," published by the American Rolling Mill Co. (1920). A certain amount of pipe may also occur in rimmed ingots, though it is normally porous and not as well defined or deep as in the killed ingot of Fig. 1. In killed ingots, pri-mary blowholes may occur near the surface, as in Figs. 2 to 4, and

Jan 1, 1937

By S. M. Shelton, M. M. Fine, T. L. Johnston

"INTRODUCTION The Bynum property is about 15 miles west of Gadsden and 1 mile north of Walnut Grove, Etowah County, Ala. The ore lies in layers and as irregular masses and pockets in the clay residue from decomposed quartzite and limestone formations to the district.The property has been developed by means of numerous shallow shafts sunk to water level - about 25 foot. Operations are confined to small-scale, selective mining of pockets of high-grade ore. The ore is marketed directly, without beneficiation. The property does not yield a large amount of manganese ores. No estimates of reserve ore tonnages are available.A 206-pound sample was furnished for test. It was taken at random from a stock rile estimated to contain 130 tons of ore. The sample con¬sisted of a mixture of manganese oxides, iron oxides, and siliceous fragments in clay. The manganese occurred largely as soft, unconsolidated pyrolusite and wad. Some hard, crystalline pieces of psilomelane were distributed through the soft material. Small amounts of iron oxides were associated with the manganese oxides. Chert, quartzite, and clay comprised the gangue minerals.Dry analysis of the sample was as follows: 36.0 percent manganese, 6.1 percent iron, 2: .0 percent silica, 1.5 percent calcium carbonate, 0.36 percent phosphorus, 3.0 percent alumina, 2.2 percent barium, and 0.31 percent zinc."

May 1, 1942

By Ahmad Rahbar-Kelishami, Zahra Karimi

When alumina is extracted from bauxite ore, one of the environmental pollutants created is known as red mud (RM). This study clarifies that the RM obtained from the Iran Alumina Company has a significant proportion of iron oxides (24%), alumina (19%), silica (17%), and calcium (21%), as well as trace amounts of other minerals. The elements in the RM can be removed and utilized again to reduce environmental pollution. Acid leaching is one of the best ways to selectively exclude some minerals from the RM. In this research, the RM is exposed to different inorganic acids, including HCl, HNO3, H2SO4, and H3PO4, and their binary mixtures. By comparing the results obtained from XRD, EDX, and SEM, it was discovered that CaSO4 crystals are formed by exposing the RM to sulfuric acid. Besides, phosphoric acid was only able to destroy the surface of RM particles. The XRD analyses of acid-washed residues demonstrated that except for the residue of HCl 5 N, all residues contain hematite, showing that inorganic acids cannot easily extract hematite from the complex phases of red mud. While the dissolution of RM with HCl or HNO3 will remove most of the calcium content of RM texture, increasing its iron oxide percentage, which may subsequently be utilized to make colors and pigments.

Mar 29, 2024

Mine pit slopes in the Pacific Rim are a geotechnical challenge because of the complex geology in which they are developed. Mines are currently being fast-tracked to meet the increase in commodity prices, often resulting in some reduction in ground studies and short-cutting of design procedures. In addition, the resources boom means that skilled personnel are in relatively short supply. At a time when mine pits are getting bigger and deeper, and the engineering is getting more demanding, there is an increased demand on managers to effectively implement the work.   Experience both in New Zealand and the Philippines, display the complex range of geological environments in which pits are being excavated. Working in these conditions has shown that successful geotechnical design requires a strong geotechnical model based on sound geology. An appropriate level of investigation and analyses results in a certain level of understanding for the mine design. There is a point where additional expenditure (on investigation and analyses) is not warranted based on the expected minimal impact on decreasing the level of perceived risk on the project. For most projects in our experience the analytical methods and complexity of geotechnical assessment changes increases as the level of knowledge grows.

Jan 1, 2006

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in Saline and Pulaski Counties, Ark., has been given in Report of Investigations 4251. The factual data obtained during the project are reported in a series of Reports of Investigation beginning with No. 4251, of which this is the thirteenth. The data are accompanied by maps showing the location of holes drilled and the deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township map. The description of each half township is followed by a description of each deposit developed in that half township. The 14 half-township maps and 77 detail maps of the bauxite deposits in this series of reports give the locations and numbers of all the holes drilled on the project, except the deep holes drilled to test the geophysical anomalies. The locations of those holes show on figure 13 in volume 1. The description of the deposits developed is followed by complete detailed logs of the drill holes. Many of the widely spaced exploratory holes did not discover bauxite of minable thickness and grade. The pertinent information obtained from the widely spaced exploratory drill holes has been summarized and tabulated and a table for each half township is given with the discussion covering that area.

Jan 1, 1948

By Michael J. Beus

This Bureau of Mines report describes a field experiment involving the sinking of two test shafts to directly compare the deformational behavior of circular and rectangular shapes. Results show that the circular shape is less sensitive to geologic discontinuities and applied stress field. Also, the rectangular shape is subject to a variety of behavioral modes, including beam bending and buckling. Geologic discontinuities around circular and rectangular shapes influence displacement significantly. Simple, two-dimensional elastic finite-element modeling, simulating circular and rectangular shapes in a biaxial stress field, shows that the structural response of a shaft is largely controlled by geologic structure. Consideration of anisotropy may be required for realistic analysis of a deep shaft.

Jan 1, 1985

By Roger Evangelista Sánchez

El presente texto analiza la problemática del oro en Madre de Dios a través del informe presentado por el Ministerio de Energía y minas en 1979 donde se debe brindar oportunidad a todo aquel que desee explotar los recursos naturales, sin que afecte el desarrollo normal de sus actividades. El problema se origina como consecuencia de la "Ley de Promoción aurífera" que vive ajena a la realidad del Departamento de Madre de Dios y desaprovecha la tecnología disponible. Para ello, se requiere de una política aurífera donde se busca crear nuevos recursos, considerando el canon al oro, madera, castaña, pago de peaje, aportación económica de los peajes y escala de concesiones de recursos naturales. Asimismo, se debe crear más de 50 mil puestos de trabajo en minería aurífera, la empresa minera del oro, la construcción de un central hidroeléctrica y de una nueva ley aurífera.

May 1, 1980

By L. A. Cornish

Pt-based alloys for high-temperature applications in aggressive environments have been under development for over 10 years, and are targeted to be used as either as bulk, or as coatings. The alloys comprise Pt, Al, Cr, and Ru, and the microstructure has been improved by composition to a best possible analogue of the nickel-based superalloys, which these alloys could partially replace. This was necessary because the previous best alloy had a strengthening precipitate volume proportion of only approximately 40 vol.%, whereas the nickel-based superalloys have around 70 per cent, and a lower volume would mean that the strength would not be the best that could be obtained. The microstructures were assessed using electron microscopy, and have been related to the alloys? hardness values. The current microstructures are much more like those of NBSAs, with a high proportion of the strengthening ~Pt3Al precipitates. Since the samples have to be small (platinum is expensive), hardness has been used as an indication of strength. Nano-indentation studies showed that the hardness and Young?s modulus were higher for ~Pt3Al than the (Pt) matrix. More extensive oxidation studies have been undertaken on the previous optimum sample, and the effect of cooling rate after heat treatment has also been ascertained. In addition, the samples were studied after different heat treatment times, and cross-sections were made in order to characterize the alumina scale that formed. The oxide scales of Pt-11Al-3Cr-2Ru (at.%) up to 100 h exposure did not spall, and were at least as good as those of the ternary alloys. There was no discernable Al depletion zone in the substrate, although it could have been at a greater depth than thickness of the samples studied. Further additions to the Pt-Al-Cr-Ru alloys have been studied, to increase the melting temperature as well as to reduce the platinum content without compromising the properties. Reduced platinum content would have the benefits of reduced density and cost. The target elements include vanadium and niobium, of which vanadium is of special interest, since it is a South African product. Before these additions could be made, phase equilibria studies were undertaken so that the maximum addition could be ascertained, and also to check any possible ternary phases, which could be deleterious. Work on the Pt-Al-V system revealed a ternary phase, ~V27Pt54Al19 (at.%), which has a eutectic reaction with (Pt). The maximum V addition is likely to be around 15 at.%, otherwise ~Pt3V or the ternary phase will form, and not the required (Pt)/~Pt3Al phases.

Jan 1, 2012

By Harold J. Schock

This paper describes an experimental method for the monitoring of diesel-generated exhaust gas pollutants in a dead-ended drift for the purpose of assessing the effect of control approaches. Experiments were conducted to determine the relative merits of these ventilation configurations: no auxiliary ventilation, induction ventilation at the entrance to the drift, and ventilation of the dead-ended drift with positive displacement tubing. The drift used in this experimental work was approximately 105 ft. (32.0 mf long and slightly downsloping, with an average height and width of 8 ft. (2.4 m) and 28 ft. (8.5 m1 , respectively. The data were gathered for assessing these ventilation methods and for gathering data to support a computer model of the dispersion and mixing processes. For this drift, it was found that ventilation with positive displacement tubing provided the best removal of diesel-generated pollutants. Induction ventilation appeared to be the least effective of the three methods examined. A comparison was also made between personal monitoring and area monitoring. Results of this analysis showed that in regions of high concentration gradients, it was not possible to get good agreement between point sampling and personal monitoring. In well-mixed areas, good agreement between the two methods of monitoring was obtained.

Jan 1, 1980