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By K. Sasaki

Ventilation measurements were carried out in a shallow underground-quarry space with relatively large internal volume of 14,600 m3 in order to evaluate its effective ventilation characteristics. Based on air velocity measurements with an ultrasonic anemometer in the exhaust airway connected to the space, it was found that the space was ventilated by natural ventilation airflow with intermittent changes in direction. It was difficult to measure the ventilation flow with typical methods of flow measurement provided from the intake portal and throughout the mine, because the cross-sectional area and volume of the openings were too large and the flow was variable. In the present study, a tracer gas method was applied to evaluate the effective ventilation airflow rate in the space. A photo-acoustic infra-red gas monitor, highly sensitive to SF6 gas used as a tracer gas, was set in the space to determine air exchange rates from gas concentration-time decay curves. The seasonal variations of airflow and thermal environment in the space were investigated through 13 sets of measurements taken over 15 months. Airborne rock dust concentrations were also measured at same time in the opening. The correlations between the effective ventilation airflow rate, thermal environment and dust concentrations in the opening space were analyzed and are discussed based on the presented measurements taken during year. It is concluded that seasonal variations in effective ventilation flow and the dust concentration are mainly due to differences in air temperature in the space, as affected by the rock?s surface temperature and atmospheric temperature. In summertime, the air temperature and associated air density difference generated lower natural ventilation flows resulting in higher dust concentrations.

Aug 1, 2013

By S. J. Schatzel, J. D. Addis, V. Gangrade, L. L. Chasko, C. A. Hollerich

"A ventilation study using tracer gas was conducted at a western US coal mine. The objective of the study was to evaluate the movement of longwall face air exchanges between the face and worked-out area and to document the presence or absence of face airflow pathways between these locations. The mine operator uses a bleederless longwall ventilation system with a back return and a blowing mine ventilation system. The study was conducted on an active panel and included both underground and surface monitoring sites. The study used sulfur hexafluoride (SF6) released as a slug on the longwall face and in the front of the gob inby the face. The velocity of the tracer gas movement in the gob was 0.019 m/s (3.7 fpm). The rate of movement for the overall tracer gas slug averaged about 0.0091 m/s (1.8 fpm). A separate tracer gas test initiated with the release of SF6 into the legs of the first shield showed the existence of more than one pathway of face air in the general direction from the headgate towards the tailgate corner. Maintaining adequate ventilation air on longwall faces is important for worker safety and for the dilution of methane emitted from the face and caved gob. A more detailed characterization of longwall system air and gas movement allows a mine to better assess its ventilation design for controlling gas on the face and in the gob. INTRODUCTION During a series of stakeholder meetings, a near unanimous concern was expressed related to maintenance of effective ventilation airflow on longwall faces. There was a strong interest expressed regarding the impacts of face length and caving characteristics on the ability to maintain adequate face airflow levels. This study seeks to understand and improve a mine operator’s ability to monitor and control ventilation and methane concentrations across the longwall face by assessing airflow variations in terms of roof caving characteristics and face length. National Institute for Occupational Safety and Health (NIOSH) researchers seek to identify flow paths of ventilation airflow on longwall panels with variations in roof caving characteristics and longwall face lengths. The project research aims to develop an understanding of the role of gas dynamics in variable broken rock, interactions with ventilation airflow and methane concentrations across the longwall face area. The research also addresses continuous ventilation monitoring along the shield line to provide early detection of gas exchanges between face and gob, and thus improve a mine operator’s ability to monitor and control ventilation and methane concentrations around the face. In the context of this paper, the longwall gob refers to the pillared area behind the shields. This work reports on results from one project task to conduct field based research using a tracer gas to describe face air and gob area gas movement in a bleederless longwall ventilation system that incorporated a back return."

Jan 1, 2017

By G. W. Bonnell, D. A. Young, D. G. Genter

Through 1996 and 1997, CANMET and the Cape Breton Development Corporation (CBDC) conducted a project to study the Phalen Mine’s 7 East longwall ventilation network to help determine methane emission patterns that were having a negative impact on coal production. Increased methane emissions were primarily related to mining depth and were also affected by the influence of a large sandstone body located above the worked seam. The research included the installation of tube bundle systems to monitor waste (gob) methane and pressure differentials. The focus of this paper is on the novel use of tracer gas techniques that helped shed light on the performance of the ventilation system and in determining the methane migration paths in the waste.

Jan 1, 2001

By D. J. Kennedy, W. G. Klinowski

Over the past few years the Cape Breton Coal Research Laboratory's staff designed, built, tested and proved the necessary hardware, software and methodology of tracer gas based surveying techniques applied in the field of mine ventilation. These methods are now used routinely in a variety of applications where traditional anemometric methods do not provide the required accuracies or cannot be effectively employed. Irregular or highly turbulent flows, leakages, geometrically complicated or highly obstructed airways are just a few examples where traditional anemometry can produce unacceptable errors in calculated ventilation parameters. Tracer gas based ventilation techniques have been used in many problematic situations where the standard ventilation methods are inadequate. One such problem, faced by many mine operators, is the emergency imposed by the ever present threat of a mine fire. An understanding of the propagation of smoke contaminants and the demonstrated integrity of appointed escape routes can save lives and property during a fire. That knowledge can be gained quickly and inexpensively by the application of tracer gas smoke simulation methods. The concept of controlled air recirculation has recently gained considerable attention in the mining industry. While mathematical models can be used to predict performance, the ultimate proof of a ventilation system's performance can best be provided by a tracer gas based simulation of contaminant levels. Fan performance tests and assessment of auxiliary ventilation systems are highly dependent on accurate definition of airflows; precise data can be easily obtained by tracer gas based volumetric surveys. This paper contains a brief description of the equipment and the methodology of tracer gas based ventilation techniques and presents typical examples of their use

Jan 1, 1991

By R. W. Hyde, B. S. Old, S. E. Eaton

INTRODUCTION ONE of the most important problems facing the steel industry at the present time is that of maintaining at a minimum the sulphur content of many grades of steel where sulphur is known to have harmful effects on both quality and yield. The present outlook in this struggle to reduce the amount of sulphur in steel is rather gloomy since the sulphur content of the raw materials available in the United States is gradually rising, with little relief in sight. A flow sheet of sulphur in the steel process is shown in Fig I. The values used here were obtained by averaging coke oven and blast furnace data at No. 5 furnace in Cleveland and are considered typical for high top pressure practice. The sulphur evolved in the blast furnace top gas was obtained by difference and since the amount is relatively small, little significance should be attached to this particular value. From Fig I it is apparent, however, that coals used in the production of metallurgical coke represent by far the largest single source of sulphur in steelmaking. As an indication of the decrease in quality of these coals as regards sulphur content the weighed average annual sulphur analysis of the coals supplied to two different steel plants, since 1925, is plotted in Fig 2.1 The sharp rise since 1940 is strikingly apparent. Another indication of this trend is found in estimates of coking coal reserves. Thus in the case of Pittsburgh seam coals available in Allegheny, Fayette, Greene, Washington, and Westmoreland Counties in Pa. as of Jan. 1937 only 25 pct of the coal reserves would contain less than 1.50 pct sulphur after washing.2,3 Many of these lower sulphur reserves have been seriously depleted in recent years because of accelerated war demands. Still another demonstration of the increasing sulphur content of coals on a country-wide basis is found in a report by the Bureau of Mines4 which shows a steady increase in the sulphur content of coke made in the United States, It should be noted that this increase continues in spite of the wider use of coal washing in recent years. Sulphur occurs in coal in three forms, pyritic (FeS2), organic sulphur, and a small amount of sulphate sulphur (CaSO4), The sulphur is subsequently found in the coke in combination with carbonaceous material of unknown composition and as calcium and iron sulphides: In considering the general problem of sulphur elimination, the Republic Steel Corp. was interested in determining which, if either, of the two major forms of sulphur in coal contributes the greater portion of sulphur to the coke, Since the ratio of pyritic to organic sulphur varies widely in different coals, it was thought that if it could be shown definitely that the major part of the sulphur occurring in coke originates from one of the two major forms of sulphur in the coal, it would then be possible to select with confidence coal which, although high in total sulphur, would yield coke of fairly low sulphur content, Using the new

Jan 1, 1948

By M Wortley, R Morrison, T Rivett

The tracking of ore through process hold-ups such as stockpiles has been traditionally been difficult to achieve. The inability to pinpoint the exact source in the mine of material that is feeding a processing plant has led to inefficient mine-mill reconciliation processes. In addition, a lack of understanding of the behaviour of ore in process hold-ups such as bins and stockpiles often leads to poor predictions of plant performance and to poor reconciliation of this to the orebody.This paper reports on two short case studies. One case study addresses tracking ore from various parts of two mines to the concentrator. The other follows synthetic particles through the coarse ore stockpile. Both studies use radio-frequency identification (RFID) tracer technology. The paper concludes by discussing general strategies for implementation of such concepts into mine-mill metal accounting and reconciliation systems. As shown in this paper, reliable ore tracking systems will allow much more effective mine-mill reconciliations as well as the ability to model process hold-ups with regard to size by residence time distributions. This should, in turn, allow metallurgists to have a better understanding of the size and grade of material that will report to the plant at different process hold-up (eg stockpile) conditions.

Jan 1, 2009

By Carlos Collado, Oscar Jimenez, Francisco Diaz, Rodrigo Bernal, Carmen Salinas

Water is a strategic resource for the mining industry. The rising cost has forced the industry to become more efficient in their use, reduce and recycle waste as much as possible. The importance of having a reliable water balance is increasingly urgent, because the resource is scarce and vital to the sustainability of human life, animal and ecosystem. Conventional flowmeters can suffer disruptions or failures by corrosion, fouling, presence of elements in the water as acids, salts and suspended solids. Use of radiotracers is advantageous to determine fluid velocities that are transported through pipes, as they are detectable by means of the radiation emitted, the same way for surface flows, such as natural watercourses and drainage from tailings dams, fluorescent tracers are those with the best advantages. For velocity measurements in pipelines a Iodine-131 tracer solution, around 5 mCi was injected into the suction of the pumps. The technique used is the transit time between detectors at known distances and determining the time of passage of the radiotracer. For measurements of surface fluxes using the fluorescent tracer Rhodamine WT by tracer dilution technique, injecting the tracer at a constant rate and measuring it known concentration diluted downstream. This work has been performed in Minera Los Pelambres, located in the IV Region of Chile, measuring the flow rate pumped from 12 pools with 1-7 pumps operating, obtaining speeds of 0.56 to 2.62 m/s. In pumping wells three facilities have been measured at speeds of 0.111-0.223 m/s, plus six surface flows with flow rates of 8.45 to 357.2 L/s.

Jan 1, 2014

By W. R. Johnson

In the spring of 1935 the writers undertook to compare the geomagnetic and direct-current earth-resistivity methods of tracing a concealed dike along its strike. As far as they are aware no such direct test has been attempted.# The area surveyed lies along United States Highway number 15 about one and one-half miles east of Chapel Hill, North Carolina, and northeast of Bolin Creek (Fig, 1). To the south of the highway is the flood plain of Bolin Crook, and to the north is a hill that rises almost to the elevation of Chapel Hill. A diabase dike, which strikes slightly west of north, out-crops in a. gully just south of the highway. Southward it has been covered by alluvium but northward outcrops again on the southeastern slope of the hill north of the highway. South of the highway the country rock is Triassic shale and sandstone, the northern limit of which is slightly north of the road. On the Geological Map of the United States I the pre-Triassic formations are shown as lower Glenarm and assigned a pre-Cambrian age. Since the ago of the Glenarm has been called into question in Pennsylvania 2, the writers prefer not to commit themselves as to the ago of these rocks further than to say that they are definitely pre-Triassic.

Jan 1, 1937

By Roy J. Greenfield

A highly undesirable side effect of the mining of coal is the release of acid forming chemicals into the ground water system. The disturbance of the ground during mining allows water to flow through the coal bearing strata and mine refuge where it absorbs iron and sulfide ions and thus becomes highly acidic. The highly acid mine water can then contaminate water supplies and can destroy many of the recreational uses of Pennsylvania's waterways. A great deal of effort has been expended to develop methods of controlling groundwater pollution from mine drainage. At the Pennsylvania State University there has been an ongoing effort to under- stand the chemistry of acid mine water formation and the hydrologic environment in which the acidic water migrates from the mine source into the ground water system. As a support to the hydrologic studies, geophysical studies have been used to help determine the geologic structure of the areas under study which are contaminated by acid water. In addition, the geophysical work has been used to define the type of information geophysical methods can give to determine which geophysical methods are most useful and to develop geophysical field procedures.

Jan 1, 1973

By A. Dreimans

Tracing of 'float' against the latest ice-flow directions ha!' led to or assisted in discoveries of several mineral deposits in Canada at lP.ast since 1891, e.g., fluorite and corundum in eastern ?Ontario, Steeprock and Josephine iron ore in western Ontario, Malartic, Fisher-Quebec, and Lamaque gold ore, and Vendome zinc ore, in western Quebec, Sullivan zinc and lead sulphides in British Columbia, Orvan Brook or New Calumet sulphide deposit in New Brunswick, Lynn Lake nickel sulphide de-posit in Manitoba, etc. Pebbles or ore boulders whose source has not yet been found include diamonds in the Great Lakes region and ?sulphides in several localities in Ontario and Quebec. Complexity of transport of ore boulders, including non-glacial transport, may be the explanation. Tracing of ore boulders requires knowledge of the Pleistocene history of each particular area (ice flow directions, their ?changes during glacial oscillations, existence of pre-glacial lakes with ice-rafted boulders, later interference by streams, lakes, mass movements). Important also is distinction of till from similar non-glacial deposits and knowledge of the bed-rock geology. Quantitative methods, e.g., pebble counts, maybe applied while tracing magnetite, hematite, or goethite. Fragments of sulphide ores are less abundant in indicator trains, and quantitative methods are less suit-able for tracing them. Heavy-miner-al investigations may give good results for minerals resistant to weathering. Geochemical methods are of value only in the vicinity of ore deposits.

Jan 1, 1958

By L. M. English, K. A. El-Nagdy

The mine characteristic curve represents the relation between the airflow in a system and the pressure drop across the system. In a single fan system, this relation can be easily drawn by assuming different values of the airflow and calculating the corresponding pressure drop according to Atkinson’s law. In a multiple-fan system this cannot be done for each fan simultaneously. However, an alternative mathematical method for plotting subsystem characteristic curves on subsystem quantity coordinates is outlined here that achieves this objective. The Hardy Cross algorithm has been combined with a switching-parameters technique and has been used to trace subsystem characteristic curves. An example using four fans in a complex network is presented here. This example illustrates the nature of the problem and the difficulty of detecting unstable conditions in this type of network.

Jan 1, 2001

By Paulo Cesar Pavan

T&T or Traceability, is a concept of generating, storing and on demand providing information about all traceable items in the supply chain

Jan 1, 2019

By Frank Hirthammer

Since the introduction of the Explosives Track & Trace in Europe in 2014 for manufacturers and 2015 for end-users, a lot has changed in all areas of the supply chain and the use of explosives. The regional associations, manufacturers' organizations, and trade associations have proven that it is possible to overcome a hurdle, that looks almost impossible in the beginning, through consistent cooperation. The paper gives an insight into the problems involved in introducing such a requirement, identifies ways and solutions, and concludes them. When looking at the current situation, the paper describes the process by which a prescribed change in business processes are transforming into a solution that increases productivity, security, and handling. It shows examples from daily work, in which possibilities for optimization, improved quality assurance, and work facilitation are explained. It presents the resulting potential by comparing process flows, before and after the introduction of Track & Trace solutions. What challenges will we face in the future concerning the use of T&T solutions? Will the tracking of explosives become the norm worldwide? What are future hardware and software developments to be expected? What impact will this have on the global supply chain?

By Frank Hirthammer

Since the introduction of the Explosives Track & Trace in Europe in 2014 for manufacturers and 2015 for end-users, a lot has changed in all areas of the supply chain and the use of explosives. The regional associations, manufacturers' organizations, and trade associations have proven that it is possible to overcome a hurdle, that looks almost impossible in the beginning, through consistent cooperation. The paper gives an insight into the problems involved in introducing such a requirement, identifies ways and solutions, and concludes them. When looking at the current situation, the paper describes the process by which a prescribed change in business processes are transforming into a solution that increases productivity, security, and handling.

Feb 1, 2020

By D. C. McKeehan

The importance of properly bonded rail joints has received the attention of The National Research Council, whose committee will investigate several methods now used and determine the merits of each as applied to street railways. The results of this investigation should be appreciated no less by the mining industry. Literature on the subject of bonding mine tracks agrees, as a rule, "that the work is poorly done." With present day facilities there is little excuse for inadequate track conductivity, and a job well done must be maintained in order to realize results. Many years ago The Union Pacific Coal Company installed their first haulage locomotive, and at that time used the channel pin bond for joining the rails. The system utilized 500 volts and the, relatively small current for a large amount of power, undoubtedly, contributed to the success of the system. The bonding of both rails was considered imperative in those days, while now the bonding of one, rail is considered sufficient in most instances. The recent installations utilizing 250 volts and correspondingly heavier currents required a more effective method of joining the rails for use as an electrical conductor. The company has used the arc-weld bond since its introduction in 1919. The art of electric welding found great favor for various methods of doing the work. The first arc-weld bonds were placed on the outside of they ball of the rail, but the bonds were ill-adapted to rails lighter than sixty pounds per yard, and the results were that grooved locomotive wheels or derailed cars removed the bonds. Familiarity with the process of electric welding brought forth numerous schemes for joining the rails. In one, instance the rails and splice-plates were welded together and with excellent results for a short time. Track movement and vibration finally broke the welds and the method was dis¬carded. Another scheme consisted of placing a channel pin over each end of an annealed copper wire about twenty inches long. The idea was to develop some way of using short lengths of scrap wire. The pin and wire were then welded to the base of the rail. Numerous joints made in this way are still intact, but successful welds were so exceptional that the practice was abandoned. Some of these bonds were welded to the web of the rail, with the result that practically all rails broke at the weld; however, this is our only record of broken rails with arc-welded bonds. At one time a quantity of No. 2 bare iron wire wasp available and was tried as a bond and proved very satisfactory. Two or three strands twenty inches long were used and were welded to the base of the rail. The method was cheap and effective and of some merit for light rails on temporary track. The use of iron wire was criticized because it did not give a balanced circuit; that is, one having equal carrying capacity for trolley and track circuits; and I am of the opinion that this is not always necessary. The total length of bond that is in circuit is so small that it contributes very little additional resistance to the complete circuit consisting of trolley wire, rails and bonds.

Jan 1, 1923

By Wenbing Xie

At Renlou Coal Mine, Huaibei Mine Area, the track entry deformed significantly after longwall mining in an overlying multiple seams. The supporting characteristics of primary roof bolts and shotcrete with wire mesh are closely related to the movement of the mine?s surrounding strata. A case study of a track entry deformation was monitored during the longwall mining of a selected overlying panel. The measured data showed the unique entry deformation pattern during the longwall mining in the overlying seam. Underground extensometer measurement showed that entry stability was mainly affected by the periodic roof weighting of longwall mining in the overlying seam. The displacement of the deeper strata occurred a head of the immediate vicinity of the entry. Thereafter, deformation of the roof and floor strata was in the form of shearing of the shallower strata. Due to the use of heavy-duty roof bolting with wire-mesh, the roof-tofloor and rib-to-rib convergences were small, but the floor heave was large, greater than 80% of the roof-to-floor convergence. The measured displacement from extensometers varied with the position of the monitored cross-sections and depth into the roof. There were several deformation patterns, such as shearing movement, compression, and expansion, and the variations between compression and expansion. Strata compression at the entry surface was always accompanied with shearing movement at the deeper strata. During the longwall mining, the whole surrounding strata of the entry moved toward the opening. Underground practical experience indicated that prior to mining, the entry was supported very well in excellent conditions. After mining, however, it deformed greatly. The current entry support technology was not effectively control the severe deformation incurred in entries driven in soft strata due to the following reasons: (1) little is known about the entry deformation behavior of the strata surrounding the opening and (2) the degree of interactions between entry deformation and roof bolting with wire mesh is not well understood. Consequently, effective supporting systems cannot be properly selected to control its deformation and maintain a stable supported surrounding structure.

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