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By Bao K. Le, Khang T. Truong, Masaki Kitazume, Toru Kobayshi, Long P. Le, Tanaka Hitoshi, Makoto Kamimura, Hoang-Hung Tran-Nguyen

"Earth levees constructed using dredged materials taken from a river along an earth levee have annually damaged in the Mekong Delta due to high void spacing in earth levees and floodwater. Sliding and internal erosion due to floodwater or piping are two key factors causing earth levees’ failures. This study proposed to apply Deep Mixing Method (DMM) to reinforce earth levees in the Mekong Delta, Vietnam. The DMM creates a soil cement wall or soilcrete wall having better engineering properties such as higher strength and low hydraulic conductivity than those of the in-situ soils. The DMM can be applied to reinforce earth levees with limit additional materials that provinces in the Mekong Delta are difficult to supply. The study investigates capacity of the DMM to reinforce earth levees in the Mekong Delta, Vietnam against annual floods. Seepage and slope stability analyses under various conditions were performed with various scenarios of earth levee’s body. The analysis results indicate that the DMM can create a wall that cuts off piping across earth levee significantly and can improve stability against deep sliding due to rapid drawdown of the floodwater.INTRODUCTIONThe Mekong Delta produces agriculture products of 50% of the whole country even though the Mekong Delta has an agriculture area of 30% of the country (Wikipedia 2014). Rice is the main product for the domestic demand and export. This is the main reason why the local people want to cultivate rice 3 times per year to increase the total rice product for export. To do that, the local provinces have constructed earth levees surrounding each area of 100-200-hectare against annual floods to protect rice fields, and farmers can grow rice in the whole year. There are thousands of kilometers long earth levees in the Mekong Delta, and the local governments have spent millions of US dollars to repair and to maintain their earth levees yearly (reports of Dong Thap province 2012; 2014).Earth levees in the Mekong Delta have often failed in flood seasons (e.g., from August to December), especially in Dong Thap and An Giang provinces – the two provinces confronting directly the annual floods from the Mekong River when the floods reach the Vietnam land. The main failure of earth levees is piping, and then causing collapse of some section of an earth levee. An earth levee was usually constructed by piling up dredged materials along a river with minimum compaction. Subsequently, floodwater flows through connected void spacing and washes out soil particles in the body of an earth levee slowly to create piping. Annual wet-dry cycles make the top clay layer swelling and shrinking to form cracks that can store rainwater to trigger sliding (whitlow 2001; Ton That Vinh 2003)."

Jan 1, 2015

By X. Gumede

A model is being developed to quantify the benefits for mining houses resulting from the reduction in greenhouse gas and energy consumption by the application of innovative blast designs in addition to direct financial benefits throughout the mine to mill value chain. The conversion from shock tube initiation systems to electronics and some changes to powder factor measured on an open pit mine had previously been used to show significant improvement on blast outputs. Benefits were realised on drilling, blasting, loading, hauling and beneficiation. Quantification of the relationship between powder factor and reduced greenhouse gasses is investigated in this study. The study has highlighted new data that must be recorded and hence some assumptions were made as to fuel consumption and the energy in crushing was obtained from the Bond work equation. The mine to mill projects in an open pit platinum mine and a quarry produced energy savings and reduced greenhouse gas emissions associated with the careful application of explosives and blast innovations. The less fines project showed an increased carbon footprint. The model provides a new insight into how project feasibility should be decided based on economic and environmental viability.

Jan 1, 2012

By Sigmund Black

Ingersoll-Rand Research, T n c and the Lee-Norse Co. built a Bureau of Mines sponsored, special deep cutting continuous miner under this contract to study the effects of rotational speed and depth of cut on airborne respirable dust. After preliminary tests indicated and later verified that deep cutting - low rotational speed reduces airborne respirable dust, a series of underground tests were performed (9 combinations of rotational speed and depth of cut at 45° bit angle and 4" bit spacing). Additional data was obtained on specific energy, coal sizing and noise. The conclusions reached from the tests results were; a) deep cutting reduces airborne respirable dust generated and specific energy needed to cut coal., b) the greater majority of the decrease occurs in going from 1" to 2" depth of cut, c) lowering rotational speed has a particularly sizable effect of reducing the amount of dust at the operator's location, d) no significant relationship was found for either noise level or coal sizing to rotational speed or depth of cut. Recommendations include. a)) use of specific energy as an indicator of the change in dust level correlating to changes in cutting parameters, b) mine operators should acquire new deep cutting machines., since retrofitting would be selective.

Jan 1, 1977

By F. McGravie, S. T. Solinski, W. W. Robertson

During this, the Centennial year of the discovery of the Hall-Heroult process, it seems appropriate to review some of the developments which have taken place in Canada and to explain why it has become an important world centre for the production of primary aluminum. For many years after it was recognized that the element aluminum existed, scientists were frustrated in their efforts to isolate it. In the early 1800s H. C. Oersted and Frederick Woehler prepared small quantities sufficient to measure some of the physical properties. A quasi-commercial process involving reduction with metallic sodium was developed by the French scientist H. St. Claire Deville in 1855 but the cost was very high ($30. 00 per kg). It was not until 1886 that Charles Martin Hall in the United States and P.L.T. Heroult in France, more or less simultaneously but completely independently, discovered the process which is essentially that in use today. Some of the early pioneers in the industry quickly recognized the potential of the hydro-electric resources in Canada as economic energy suppliers for aluminum production. The first commercial production in Canada was in Shawinigan, Quebec in 1901, only 15 years after the process was discovered. Subsequently operating plants were established at nine different locations in Canada (Quebec and British Columbia) (Table 1). Operations continue today in all locations except one (La Tuque). The table shows present plant capacity which for the older plants was reached in an evolutionary manner including replacement of obsolete capacity or upgrading and modernization of existing designs.

Jan 1, 1999

By J Tiihonen, J OÆCallaghan, T Haakana

Outotec is today capable of providing technologies, process equipment and engineering for the construction of pressure oxidation leaching (POX) plants in any location in the world. Outotec works with customers from mine to pure metal, participating in plant design from the process development phase (including test work execution/supervision) to plant commissioning and operations. Either key equipment technology packages with basic engineering or entire POX plants can be supplied.The addition of pressure oxidation equipment to OutotecÆs product portfolio adds to and complements already existing significant experience in general hydrometallurgical process and proprietary equipment design and supply.In addition to providing key pressure vessels, piping and valves to a POX plant, Outotec can offer an enhanced and proven autoclave agitation system that maximises oxygen mass transfer and utilisation. Novel energy and water recovery technology can also be tailored to a customerÆs specific needs. Importantly Outotec owns and operates extensive test work facilities and can provide test work to ensure the optimum POX flow sheet and materials of construction. Outotec ensures that best available technology (BAT) concepts are used in POX design to improve the availability of the process and minimise unpredicted shutdowns.CITATION:Tiihonen, J, Haakana, T and OÆCallaghan, J, 2013. Outotec pressure oxidation - more out of sulfide ore, in Proceedings World Gold 2013 , pp 197-206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By B. J. Moore

This publication contains routine analyses and related source data for 374 natural gas samples from 24 States and 5 foreign countries. These samples were collected during calendar year 1966 as a part of a continuous survey of the free world for occurrences of helium in natural gas. This survey has been conducted in the United States by the Bureau of Mines since 1917. In late 1965, the survey was expanded to include foreign gasfields. The analyses of foreign samples contained in this publication represent the first samples received as a result of this expanded program. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus, which are described in Bureau of Mines Bulletins 4863 and 576.4 Eight previous publications have been made to present the results of 7,244 gas analyses made? by the Bureau of Mines Helium Activity prior to 1966. The first three, Bulletins 486,5 576,6 and 617,7 contain analyses and related

Jan 1, 1967

By Michael J. Friedel

The integrity of mine structures, such as the roofs, ribs, face and supporting pillars, is difficult to assess beyond the exposed surface. To mitigate potential rockfall hazards, the U.S. Bureau of Mines is assessing the usefulness of Rayleigh wave dispersion analysis to detect damage and stress-relieved zones in mine structures. Classical surface wave dispersion modeling is utilized at both laboratory and field scales in damaged and undamaged material to assess the integrity of a mine pillar and roof. To more fully exploit Rayleigh wave propagation characteristics, derivation of a novel dispersion parameter was conducted using a convolutional model. The development of a suitable Rayleigh wave dispersion system based on insight derived from forward modeling is presented. The application of inverse modeling for damage and stress assessment in the mine environment is also discussed.

Jan 1, 2010

By Toby Mayo, Tassos Grammatikopoulos, Massoud Aghamirian, MARK FEDIKOW

The Zoro pegmatite project in east-central Manitoba occurs 20 km east of the historic mining town of Snow Lake. A composite sample (Master Comp) was prepared fromthree pegmatite zones within Zoro Dyke “D1” including the North, Central, and South Zones for mineralogical analysis and heavy liquid separation (HLS). The mineralogical examination was conducted on a subsample crushed to ca. P80 of 600 μm to determine the overall mineral assemblage, liberation of spodumene, and assess the potential recovery of spodumene by flotation. XRD and QEMSCAN results show that the sample consists of spodumene (10.5%), quartz (29.3%), plagioclase (29.0%), K-feldspars (21.3%), micas (5.1%), tourmaline (2.9%), and Fe-Mn-phosphates (0.1%). Spodumene is well liberated (88%), but also forms complex particles (7%), and middlings with quartz (4%). Liberation of spodumene increases from 81 in the + 600 μm to 95%in the − 106 μm size fraction. Liberation of quartz, feldspars, and micas account for 89%, 94%, and 83%, respectively. Electron probe micro-analyses and LA-ICP-MS showed that the average Li concentration is 3.7% in spodumene, 2196 ppm in micas, 1001 ppm in tourmaline, and 115 ppm in K-feldspars. Thus, spodumene accounts for 96%, micas 2%, Fe-Mn phosphates 1%, and both K-feldspars and tourmaline for < 1% of the total Li in the sample. The mineralogical data indicate the potential to recover spodumene by flotation with minimal Li losses due to other than spodumene carriers. Heavy liquid separation was conducted on the Master Comp which was crushed to − 6.4 mm, while the − 600 μmfractionwas removed fromthis test. The coarse fraction − 6.4mm/+ 600 μmwas subjected to HLS tests with eight heavy liquid-specific gravity cut-points (2.65 to 3.10 g/cm3). HLS indicates that it is possible to produce a high-grade lithium concentrate (close to 6% Li2O) after the rejection of iron silicates with magnetic separation.

Sep 16, 2020

By D Bertoldi, C Haines

"The Waihi Gold Mine (WGM) operated by OceanaGold New Zealand Limited is a wholly owned subsidiary of the OceanaGold Corporation of Australia. Traditionally WGM has stockpiled and processed separate campaigns of open pit and underground ore. The ore is processed via a conventional semi-autonomous grinding (SAG) / ball circuit (SABC). The low aspect SAG mill operates in a closed circuit with two 20&quot; cyclones, whilst the ball mill is also a closed circuit with a 10&quot; cyclone cluster. A major wall movement in April 2015 ceased open pit operations indefinitely, 18 months ahead of the mining plan. This immediately reduced the forecast mill tonnage leaving two options: begin campaign milling or change the operating strategy and target lower throughput. Additional cost pressures necessitated improved milling cost efficiency. The immediate ore restriction limited processing alternatives to within the existing major infrastructure. Available comminution circuit survey data laid the foundation for developing a comminution model using the JKSimMet&trade; software package (version 6, created by KJTech). A number of flow sheet variants were then evaluated based on predicted throughput and efficiency. The comminution models suggested opportunities for improved efficiency lay in reducing throughput and increasing utilisation rather than on/off campaign milling under the existing operating philosophy. A series of process alterations followed, delivering new cost efficiencies that maintained the current $/t processing cost. This paper aims to review the change in circuit performance and examine the decisions and challenges faced following the transition from a high tonnage SABC circuit to lower tonnage SABC circuit.Citation:Haines, C and Bertoldi, D, 2016. The Transition from Semi-autogenous to Autogenous Milling at Waihi Gold, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 303&ndash;312 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By D K. Weatherley, G R. Ballantyne, S Ali, M Yahyaei, M S. Powell

This paper explores development of a novel ore characterisation method for the precise measurement of practical minimum comminution energy. A monolayer of particles with a narrow size distribution is broken using a precision rolls crusher (PRC); an ore characterisation device developed to overcome the shortcomings of conventional tests. For energy measurement, PRC uses two shaftmounted rotary torque transducers. These transducers acquire precise torque and angular speed data in response to the load applied to the rotating shafts during breakage events, which is converted into energy. The test progressively crushes feed particles down to final product size in many controlled breakage stages. The generation of fines in each breakage stage is then plotted as a function of input energy. The inverse of the gradient of this plot provides the size specific energy (SSE) in kWh/t of material generated below a predefined marker size; -75 μm in this case. The PRC has potential to evolve as a geometallurgical ore characterisation test—it is simple, fast, requires small sample mass (200–300 g), covers a wide feed particle size range (10 mm to 115 µm), and provides ideal SSE measurements that can be used for the calibration of on-site production equipment.

Aug 24, 2022

By A. E. Foscolos

British Petroleum (BP, 2005), indicates that world reserves for oil to be 1198 billion barrels, for natural gas the equivalent of 1156 billion barrels of oil and for coal the equivalent of 3219 billion barrels of oil. If we take into consideration the mean aver-age annual increase in demand of the last three years for oil, 2.6%, for natural gas, 3.9%, and for coal, 6.6%, then their respective reserves? lifespan are calculated to be 27, 34 and 38 years. Without taking into account their annual increase in demand, lifespan increases to 38, 67 and 161 years respectively. Since zero increase or perpetual increase in energy demands on finite resources is unrealistic the selection of the most suitable energy commodity for power generation rests upon the law of supply and demand of each commodity. This defines its price hence its selection for the production of cheap electricity. When the ratio of supply to demand is less than one, peak production is achieved. Any further increase in demand results in price increase to quench its demand. The Association for Oil and Gas Peak (ASPO) has calculated that when oil demand exceeds 84 million barrels/day, Peak Oil Production will be attained thus prices will start to increase in order to even demand with supply. Correspondingly, Gas Peak Production is expected to take place when demand exceeds 9.1 or 10.2 billion cubic meters/day. Peak Oil production has been calculated to take place in the current year, 2006, while Gas Peak production is estimated to take place between 2020 and 2025 provided that gas will not cover the energy deficit created from the lack of oil otherwise Gas Peak production could arrive as early as 2010. The use of coal for power generation is considered a better alternative than oil and gas if new combustion technologies with an energy efficiency of 43%, Germany, and 47%, Denmark, are adopted. These not only extend the lifespan of coal reserves but reduce also CO2 emissions by 25% and 31%, respectively. In the very near future CO2 sequestration and fixation in deep geological strata will eliminate its emissions thus rendering the use of coal the cheapest feedstock for power generation.

Jan 1, 2006

By Sherwin Kelly

IN presenting this brief historical perspective, it is not my purpose to address myself to the geophysicists, to most of whom the story is already well known. My objective is to draw the attention of those who hold the belief that geophysics is something new, typically twentieth century, to the fact that fundamentally, whether it was known by the name of geo-physics or not, the science is an ancient and an honorable one. It began many centuries ago, and our modern civilization and its commerce owe a great debt to its founders, who today are likely to he overlooked and their names forgotten. The word "geophysics" means the physics of the earth, and is descriptive of a science that in many ways bears the same relationship to geology that astrophysics does to astronomy. When dealing with dis-tant stars or deeply buried rocks, the experimenter cannot reach them to obtain samples, which can be taken to his laboratory for study. He therefore exhibits the resourcefulness of Mahomet in the mountain episode, and makes the terrestrial globe or the cosmic universe his labora-tory, studying the effects of distant bodies on certain "fields of force"" which come to him across interstellar space, or through the rocks that make our earth. The application of these techniques of the physics laboratory to the study of the stars is the science of astrophysics, and to the investigation of the earth is geophysics. Yet the origin of the most valuable contribution to the world&apos;s trade and commerce ever made by geophysics remains lost in deep obscurity. Unknown even is the country wherein lived the unsung genius who invented the first geophysical instrument, the mariner&apos;s compass! Worse yet, it is not certain whether this invaluable guide of man had its begin-nings in Europe or in Asia. A Chinese legend tells of the Emperor Hwang-ti, who attacked his enemy Tchi-yeou on the plains of Tchou-lou in the year 2634 B.C., whereupon the latter magically raised such a fog that the Emperor could not pursue the retreating troops. Not to be outdone, the mighty ruler constructed a chariot that indicated the cardi-

Jan 1, 1938

By Henry M. Howe

This paper may be regarded as a report of progress of an investigation into the influence of prior exposure to different high temperatures, under different conditions, on the properties of steel after it has been cooled completely. The following are the chief divisions: II.—Experiments on toughening manganese-steel by sudden cooling. III.—A study of the critical points of common or carbon-steel, chiefly by examining the spontaneous retardations which occur in heating and cooling it, and by examining the ductility of pieces of steel which have been cooled suddenly from different temperatures by quenching them in water or brine. IV.—A brief note on Osmond&apos;s theory. V.—A study of the critical points by examining the ductility of pieces of steel which have been cooled slowly from different temperatures at, above, and below them. VI.—A description of the furnace used, with notes on thermoelectric pyrometry. It remains to throw further light on the questions studied by ascertaining the condition of the carbon and the hardness proper, and by studying the microstructure and the fracture of the many pieces treated. I hope to present later the results of experiments in some of these directions. With few exceptions, the experiments have been performed in my private laboratory. I tender sincere thanks to my assistant, Mr. William Haskins, S.B., on whom most of the labor has fallen, for his zealous and intelligent co-operation; to the Sterling Steel Co. for their extra hard steel, Series 17; and to Mr. Joseph Hartshorne and the Pottstown Iron Co. for their soft basic steel. Series 8, 9,10, and 18 were supplied by Messrs. Spaulding, Jennings & Co., of the West Bergen Steel Works; to them also my thanks are due. The temperature of the pieces treated has been very carefully

Jan 1, 1894

By C. Clark, J. Seymour, D. Benton

"National Institute for Occupational Safety and Health NIOSH is conducting research on jackleg use and related accidents in underground metal mines. This paper provides an analysis and overview of jackleg drill usage, accidents, operational characteristics, and alternatives, based on information from injury reports, legacy research, stakeholder input, and published literature. Jackleg drills are involved in more ground fall accidents in underground metal mines than any other drill. Jackleg-related injuries are most prevalent at the face in the course of installing initial ground support. Alternatives to jacklegs for drilling and bolting under incomplete support in narrow underground openings are not yet available. Small mechanized bolting equipment needs to be developed to address jackleg-related accidents and improve safety at mines where jacklegs are being used. JACKLEG DRILL Description The term “jackleg drill” is a generic name for a class of handheld, rotary, percussion rock drills that are equipped with an attached reaction leg to provide stability and thrust for the drill (Figure 1). All of the drill and leg controls are located near the operator’s handle at the rear of the head portion of the drill. Jacklegs are classified according to the bore size of their pneumatic pistons which normally range from 6.03 to 8.26 cm (2.375 to 3.25 in) [Kurt, 1982; Clark, 2012]. Jacklegs typically weigh 460 N (103 lbs), but their weight can approach 535 N (120 lbs) after they are fitted for operation with drill steel and air and water hoses [McKibbin and Clark, 2001]. In underground mines, jackleg drills are commonly used to drill 3.8-cm (1.5-in) diameter holes 1.83 m (6 ft) deep in rock. Application The jackleg drill is primarily used in underground mines when the size of the ore body, the ground conditions, or the mining method do not permit large openings to be mined using mechanized equipment (e.g., narrow vein mining). Jacklegs are used to drill blast-holes for explosives and also holes for installing ground support. These versatile drills are used in nearly all phases of mining including exploration, development, production, and maintenance [Kurt, 1982; Williams et al., 2007; Chen and McKinnon, 2012]. The jackleg is used to drill holes in rock using drill bits attached to hollow steel bars called drill steels (rotary percussion drilling). After the hole is drilled, the jackleg can be used to install different types of ground support components, depending on the ground conditions and the specific ground support measures that are needed. For example, the jackleg can be used to install expansion-anchor rockbolts or resin-grouted rockbolts using the drill’s rotary-motion feature. On the other hand, the jackleg can also be used to install friction-type Split-Set™ rockbolts using the drill’s percussion (hammer-motion) feature. As shown in Figure 1, various washer-like bearing plates can be installed along with these bolts to provide additional ground support and to help secure surface control products, such as wire mesh and shotcrete that are in turn used to retain small, loose material between the bolts [Clark, 2012]."

Jan 1, 2016

A new branch of the Institute-the Zululand Branch- was formed at the end of last year. After many months of preparation and perusal of address lists, it was realized that branch serving our members north of the Tugela was long overdue. A small steering committee consisting of Messrs John Selby, Dawid de Wet Smith, and Bill Kluckow got the branch of to a roaring start. They organized the inaugural meeting, which was held at the Richards Hotel in Richards Bay on 28th October,1993. Out of a possible 70 members residing in a 100 km radius, over half attended that first meeting!

Jan 1, 1994

By F. J. Perzak

The Bureau of Mines conducted a study to develop a standard fire test for 5-gal containers used for storing combustible fluids in underground coal mines. A standard test method was developed which evaluates the performance of the container in a 4-min tray fire. Bureau investigators used the standard test method to evaluate several types of closed 5-gal plastic and metal cans in outdoor tests. Each can tested contained 1 gal of nonfire-resistant (NFR) hydraulic oil. A container failed the test if it lost its contents in any of seven trials. Contents spilled either as a result of thermal rupture or melting. Fewer than 10 pct of the metal containers failed this criterion, but all the plastic containers failed. The metal container failures were usual-ly due to tipping over during pressure relief, which spilled the NFR oil. Replacing the NFR oil in the container with kerosene resulted in failure of more than 30 pct of the metal containers. The standard tests and preliminary tests showed that plastic containers are not equivalent to metal containers in their ability to contain combustibles such as lubricants and greases in a fire. For solvents and lubricants more volatile than NFR hydraulic oil, approved metal safety containers are recommended.

Jan 1, 1985

By Barry D. Simmons

The Millenbach copper-zinc orebody is an ideal Canadian example of a stratabound base metal deposit in volcanic rocks. The mine, operated by Lake Dufault Divison, Falconbridge Copper Ltd. is located five miles north of the city of Noranda in northwestern Quebec. The deposit occurs within an Archean volcanic sequence which forms part of regional acidic volcanic center within the Abitibi greenstone belt. Preproduction ore reserves totalled 2,075,000 tons grading 3.5% copper, 3.6% zinc, 1.1 ounces per ton silver, and 0.02 ounces per ton gold. Stratabound lenses of massive sulphides together with underlying stringer sulphides are closely associated with a dome of quartz-feldspar porphyritic rhyolite approximately 3000 feet below surface. The paper describes the presently known geology of the deposit and includes documentation of sulphide mineralogy and textures as well as sulphide/ host rock relationships. The stratigraphy, petrography and chemistry of the volcanic host rocks are described with emphasis on the alteration intimately associated with the sulphide bodies. Although the volcanic stratigraphy is complex within the mine area, the presence of only low-grade metamorphism and the relative lack of structural deformation allow detailed interpretation of geological history. Presently recognized evidence strongly suggests that the sulphides were deposited at and near sea-floor, by hydrothermal solutions. The dome of porphyritic rhyolite appears to have been the most significant factor controlling sulphide localization.

Jan 1, 1975

By F. W. Horton

This paper covers the salient features of the occurrence and mining of sheet mica in the United States and the preparation of mica for market; presents the results of a study of the physical properties of domestic and foreign micas, which the author hopes may he of interest to every mica user, as it definitely answers many questions as to the suitability of various minas for particular purposes; and discusses mica-trade conditions and the future outlook for the domestic mica industry. ACKNOWLEDGMENTS The author takes pleasure in acknowledging his indebtedness to J. R. Thoenen, of the United Stator Bureau of Mines, under whose guidance the work reported herein was performed, and to Frank L. Hess, also of the Bureau, for information on the geological and mineralogical characteristics of mica-bearing pegmatites.

Jan 1, 1935

By K. V. Raj, M. McNinch, A. L. Miller, J. Wilson, D. A. Parks

Diesel particulate matter (DPM) has been shown to contribute to various adverse health effects on underground miners. In order to reduce worker exposures, it is critical to measure the levels of DPM in the active work settings and in real time. However, the 5040 method, developed by the National Institute for Occupational Safety and Health (NIOSH), which quantifies the mass of elemental carbon (EC) and organic carbon (OC) in the samples, is based on full-shift samples, and can take days or even weeks for results. Use of real-time monitors could significantly reduce the risk of DPM exposure to miners, and available monitors have been shown to quantify DPM, mainly using the EC and other surrogates. The NIOSH Spokane Mining Research Division is conducting research aimed at developing a field-portable DPM monitor that is able to quantify both EC and OC. One part of this work is to understand the effect of OC on currently available real-time DPM monitors. This paper will present the results from experiments that were designed to observe the effect of OC on real time monitors and compare the results with the NIOSH 5040 method. BACKGROUND Diesel engines remain ubiquitous in mining environments and, as such, are one of the primary sources of ultrafine- and nano-aerosols in the mining environment in the form of diesel particulate matter (DPM). As a result of their small size, DPM has longer residence times in a mine atmosphere than the typically larger mechanically generated dust [1]. In addition, the small size enables DPM to penetrate deeply into the respiratory system [1], and exposure to DPM has been shown to contribute to various adverse health outcomes of the pulmonary system [2] and cardiovascular system [3]. Diesel exhaust has been classified as a carcinogen to humans (Group 1) by the International Agency for Research on Cancer [4]. Due to mounting concern about adverse health outcomes, extensive efforts are being made to reduce workers’ exposure to DPM, with the high exposures that often occur in underground mines being of particular concern [5]. New technologies are being developed to reduce engine emissions and thereby airborne DPM levels, including advanced engine technologies, a host of aftertreatment systems [6], and a variety of alternative fuels. The latter have been shown to markedly decrease respirable DPM and other hazardous components of diesel emissions from mining vehicles [7], yet high exposures persist, especially in underground mines [8]. In order to reduce worker exposures, it is critical to measure the levels of DPM in active work settings. In mine settings, exposures to DPM are measured by collecting air samples on filters (usually full-shift samples) and sending them to a lab for analysis using the Mine Safety and Health Administration (MSHA) P13 method, a variant of the National Institute for Occupational Safety and Health (NIOSH) 5040 method. The 5040 method is designed to quantify the mass of elemental carbon (EC) and organic carbon (OC) on the samples [9], which is then used to determine the concentration in the sampled air. MSHA has set a limit for exposure, which is based on the concentration of total carbon (TC), or the sum of both EC and OC. The allowable TC in the air (time-weighted average over the shift) is 160 μg/m3 of TC [10].

Jan 1, 2019

By Heinz W. Sternberg

A method for the electrochemical reduction of the benzene ring was developed and applied to the electrochemical reduction of coal. Successive electrochemical reductions of a vitrain from low-volatile bituminous coal in ethylenediamine saturated with lithium chloride resulted in the addition of 53 hydrogens per 100 carbon atoms. Ultimate analyses and pyridine solubility of the vitrain recovered after each reduction showed that hydrogen added at the beginning has a much greater effect on solubility than hydrogen added at a later stage. Surprisingly, the removal of sulfur from the vitrain takes place only after the more reactive aromatic rings are reduced. Nuclear magnetic resonance analysis and average molecular weight determination of the extracts of the reduced vitrain samples, representing about 18 percent of the vitrain, showed that these fractions had 95 percent of their hydrogen content on saturated carbon atoms and an average molecular weight of 800 to 900. A study of the effect of operating variables on current efficiency showed that current efficiency is highest with aluminum as cathode material and with lithium chloride as electrolyte. A substantial increase in current efficiency of difficulty reducible olefinic double bonds was achieved by adding a proton donor. This result is significant in connection with the electrochemical reduction of coal which proceeds from readily reducible aromatic double bonds to difficultly reducible isolated double bonds. It is proposed that reduction is achieved by electrolytically generated and subsequently solvated electrons and hence does not require prior adsorption of the substrate at the electrode surface. This offers a distinct advantage for electrolytic reduction of sparingly or insoluble substrates such as coal.

Jan 1, 1967