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By P. K. Kaiser

The purpose of deformation monitoring for the evaluation of the stability of underground openings is reviewed briefly and some results from laboratory tests of small tunnels are presented. The ground behaviour is described by comparison with the response of structural systems and illustrated by the data from the testing of small tunnels. It is concluded that the main objective of a deformation monitoring system for stability evaluation is to determine the actual process of deformation and instability in the area surrounding the opening. Only when this process has been established is it possible to use deformation measurements to design support systems or to improve construction or mining procedures. Present monitoring practice is not sufficiently orientated toward the aim of process description.

Jan 1, 1981

By Richard M. Tinlin

The mining industry needs to assure compliance with the Federal Water Pollution Control Act Amendments of 1972 (Public Law 92-500). Congress has enacted this legislation with the intent of preventing, reducing, and eliminating pollution of the nation' s surface and groundwaters. Recognized sources of pollution such as seepage from tailings ponds, waste dumps, and contaminated effluent from mine dewatering operations pose a serious threat to adjacent groundwaters. In addition, technological innovations being implemented by the industry such as in situ leaching of low grade ore deposits may also lead to ground- water contamination. An adequate monitoring methodology designed to meet the needs of the mining industry is needed. Monitoring and control methodology devised for other man- caused sources of ground- water pollution - e. g., landfills - offer considerable promise for adaptation to the problem. The prediction of deleterious effects on groundwater quality usually requires extensive geohydrological data in addition to a thorough analysis of the mining activity that is underway or projected. If the avail- able data are adequate, mathematical models of surface and groundwater flow can be constructed that will help to predict effects on water quality. Data are inadequate to allow a realistic interpretation of pollution potentials. These data can be supplemented by computer simulation as a method to explore a number of possible environmental effects and also to develop a minimum-cost approach to identifying and gathering the additional necessary supporting data. Incorrect assessment of the important environmental considerations may, in many instances, prove to be the weakest link in analyzing the financial feasibility of a mining operation.

Jan 1, 1973

By Richard M. Tinlin

Some of the practices of the mining industry that may place an undesirable stress on the groundwater environment are coming under increasing scrutiny from legislators and regulatory agencies. Among these practices are mine dewatering, the use of tailings ponds, land rehabilitation, and technological innovations such as in situ leaching of waste clumps and ore deposits. Pernichele, noting that 24 states have enacted legislation controlling to varying degrees the environmental effects of mining, has emphasized the importance of assessing the potential for damage to groundwater when evaluating, planning, and designing mining projects. 1 Illinois has enacted legislation requiring anyone opening, operating or abandoning a mine site to obtain a permit from the Illinois EPA. The law is one of the first to require regular monitoring and reporting to a control agency. Legislation has also been recently enacted at the national level that will have a significant impact on the mining industry; e. g., the Federal Water Pollution Control Act Amendments of 1972 (Public Law 92-500). The stated objective of this Act is to restore and maintain the chemical, physical and biological integrity of the nation's waters. Specifically, according to Sec. 102(a), the Administrator of the U.S. Environmental Protection Agency (EPA) is required to prepare or develop comprehensive programs for preventing, reducing or eliminating the pollution of the navigable waters and groundwaters and improving the sanitary condition of surface and underground waters. The definition of the terms "pollution" and "pollutant" is of particular significance to those who must comply with PL 92-500. The definitions are quite broad and include most of the adverse water quality effects of man's activities. As defined in Sec. 502(19), "pollution means the man-made or man-induced alteration of the chemical, physical, biological and radiological integrity of water." Within the Act, the list of pollutants includes dredged spoil, solid waste, incineration residue, chemical wastes, radioaetive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt, and industrial waste discharged into water.

Jan 1, 1973

By L van Latum, A Koh, I Thomas

Haul truck drivers are at a high risk of developing fatigue due to the monotonous nature of the work and demanding shift rosters. In the mining industry, fatigue is identified as a major contributing factor in several fatal accidents a year. A number of fatigue detection devices are now available, that can contribute to improved fatigue risk management in the mining industry. This paper describes the technology and algorithms behind one particular product which is both predictive and un-obtrusive to the operator. The Advisory System for Tired Drivers (ASTiD), was developed by Fatigue Management International (FMI) in collaboration with the Loughborough Sleep Research Centre (LSRC), both in the United Kingdom. While this system includes a model of the human circadian rhythm as a bias for predicting expected fatigue risk by time of day, it also uses yaw data generated by a solid-state gyroscope in the horizontal plane. Algorithms analyse this data to determine the level of monotony of actual driving conditions and to detect changes in steering control caused by driver fatigue. During normal levels of attention, a haul truck driver applies continuous, small adjustments to the steering wheel. As the level of fatigue increases, steering adjustments become less frequent and more erratic. Differentiating between these modes of control in the highly variable mining environment is accomplished by chromatic processing of the gyroscope data. This paper will go into some detail explaining the principles behind chromatic processing and the specific application of these in detecting fatigue in haul truck operators.Technology in itself is not the solution to addressing operator fatigue, but it plays an important role in ongoing monitoring and maintaining awareness with mining personnel. Furthermore, the specific principles behind ASTiD technology support a risk-based approach to fatigue management, allowing optimisation of the mining operation for productivity as well as safety.

Sep 26, 2011

By He F, Zhu D

How to monitor and control the support and surrounding strata system on a longwall face effectively is one of the major research problems in ground control. Based on observations on movements of the support and surrounding strata of face No. 2703 of Dongpang colliery, the relationship between the downtime related to support and surrounding strata and other influential factors is analysed systematically in this paper. Monitoring indices and control measures are then determined by taking corresponding downtime as an objective function. When the monitoring method, developed from the above findings, was used on face No. 2703, the downtime due to support and surrounding strata was remarkably reduced, and the face advanced Normally.

Jan 1, 1992

By Ming-Gao Qian

How to monitor and control the support and surrounding strata system on a longwall face effectively is one of the major research problems in ground control. Based on observations on movements of the support and surrounding strata of face No. 2703 of Dongpang colliery, the relationship between the downtime related to support and surrounding strata and other influential factors is analysed systematically in this paper. Monitoring indices and control measures are then determined by taking corresponding downtime as an objective function. When the monitoring method, developed from the above findings, was used on face No. 2703, the downtime due to support and surrounding strata was remarkably reduced, and the face advanced normally.

Jan 1, 1992

By Stephen Hardcastle

Presentation Outline ? Introduction ? Mine Ventilation Facts ? Ventilation-on-demand (VOD) ? Sensors/Controls ? Continuing Work ? Conclusions ? Mine ventilation engineering practices were published in 1556 in Agricola?s De Re Metallica (wind sails, bellows, etc.) That was then? This is today? Large fan installations handling >1M cfm

Nov 1, 2011

By D. A. King

Monitoring devices have been installed at several mine sites to assess the potential for the development of acid rock drainage (ARD) in waste rock, spent ore, and tailings material. In addition, instrumentation has been designed for monitoring changes in water quality in pit lakes. These devices monitor temperature, oxygen, water movement, and water chemistry in the waste rock pile. This information can be used to evaluate the current and future ARD risk, the effectiveness of caps and covers, and provide information to aid in the design of other reclamation strategies that limit ARD development. The instrumentation includes nested thermistors and oxygen sensing ports, neutron access tubes, heat dissipation units (HDUs), and lysimeters. Many of the monitoring devices can be linked to a datalogger and telemetry systems, enabling monitoring data to be downloaded from the office.

Jan 1, 1997

By P. Schmidt, M. Hopf

Water-cooled parts of submerged arc furnaces are potentially dangerous, especially if molten matte or slag contacts the water. Explosion hazards and metal run-outs generate high costs for production loss and repairs - not mentioning the possible loss of human life. This paper reports about practical results of wear measurement on intensive water-cooled tap-holes and spray-cooled side walls. On the one hand an embedding technology has been developed, that is used e.g. in water-cooled copper tap blocks or copper side wall coolers. Second the application of the sensor installation on the inner side of a water-cooled steel shell will be discussed. The fibre-optic sensor is fed through a specially arranged piping system and measures numerous temperatures over its entire length. By using the thermal conductivity of the installed refractory materials the lining thickness is calculated. The practical installation of the sensors will be discussed and the results of the wear measurement will be compared to the theoretical FEM calculations. The highly sensitive and accurate temperature measurement, as well as the recalculation of the impact of differences in the cooling water temperature, allows the exact determination of the remaining lining thickness. The discussed technologies offer efficient and safe monitoring of tap-holes, side walls and other endangered parts of pyro-metallurgical smelters.

Jan 1, 2015

By Paul D. Kovscek, Charles D. Taylor, Edward D. Thimons

When blowing ventilation is used on a mining section, a machine-mounted scrubber is often required to maintain face dust levels below 2 mg/m3. Operation of the scrubber also affects airflow patterns at the face and the dilution of liberated methane. Reductions in scrubber flow can result in increased methane concentrations. During mining, loading of the scrubber filter with dust is likely to reduce airflow. Detecting changes in scrubber flow is difficult, especially with extended cutting, because the machine must be operated from a remote location. Tests were conducted to demonstrate how scrubber airflow could be continuously monitored at a remote location. Three variables, static pressure at the fan inlet, differential pressure across the scrubber filter, and scrubber fan motor current, were continuously monitored while the scrubber filter was incrementally loaded to reduce air flow. The results show that monitoring each variable provided a way for estimating scrubber flow.

Jan 1, 1995

By Matthew Wilcock, Kenichi Soga, Peter Wright

"This paper discusses how an existing grey cast iron segmental tunnel lining responds to construction of a new SCL tunnel transversely beneath with zero clearance; how the damage assessment for the existing tunnel was conducted for impact of longitudinal movement; how the tunnel is subsequently instrumented to observe both movement and stress manifestation at its longitudinal connections and how the results from the instruments compare with the prediction. An assessment of neutral axis of the tunnel in longitudinal flexure is also explored using interpolated horizontal displacement data from a conventional monitoring system. INTRODUCTION The Royal Mail Tunnel (RMT) (formely Post Office Tunnel or ‘Mailrail’) was constructed using semi-mechanised deep level construction techniques from 1914 and 1917 (Lee 1938). Commencing full commercial operation in 1926, the system was until 2003; conveying parcels the 6.5 miles between seven sorting offices in the center of London, and linking the system with main line rail stations, Paddington and Liverpool Street (The British Postal Museum & Archive 2013). A single tunnel of 2.74m internal diameter facilitated a bi-directional twin narrow-gauge (~611mm gauge) railway road system for electric driverless operation. The tunnel lining is segmental grey cast iron (grade 10) made up of six flanged segments and a smaller flanged key segment; constructed into a ring of width 508mm The external diameter of the tunnel is 2.971m. For further details of the tunnel lining and material properties are outlined by (Devriendt & Alhaddad 2014).London Underground Bond Street Station is a major station of the London Underground system in the very center of London; in its vicinity, the RMT runs west-east perpendicularly above the north south Jubilee Line tunnels. Historic survey record of the Jubilee Line’s (the then Fleet Line) construction in 1974 and its impact on the RMT case is documented in (Crossrail 1993): it is one of only a hand full of case-studies frequently cited when assessing the impact of new construction scenarios of this type; not least including the assessment of the same tunnel, at the same site some 40 years later, and the subject material for this paper: It noted significant vertical displacement of ~90mm to the RMT without noticeable serviceability or operational impediment."

Jan 1, 2016

By Akira Kaneda

Mitsubishi continuous process employs an electric furnace for settling matte from slag. Electrodes are immersed into the slag layer in the slag-cleaning furnace and the temperature of the melt is maintained at a predetermined level by Joule's heat. Electrodes are immersed to the depth where the current of each electrode is kept at a set value, and they are raised or lowered automatically to compensate for the deviation from it. Because electric resistance of the bath is varied with the matte level in the furnace and the composition and temperature of the slag, the immersion depth of the electrodes is affected by them. Therefore by monitoring the immersion depth and its change with time, abnormal situations in the furnace, such a~ rise of matte level or local abnormal state of melt, can be detected. In this paper, relations between state of the furnace and electrode behavior are discussed based on the plant data, and then a new and simple monitoring method of the condition of the furnace is proposed.

Jan 1, 2001

By K. Thuro, H. Käsling, C. Wieser, G. Nuijten

"The time-dependent behavior of brittle rocks during stress relaxation is of great interest for mining industry, nuclear waste disposal as well as tunneling and underground construction. Several studies have shown that both elastic as well as inelastic deformation occur during stress relaxation (Emery, 1964; Zang & Berckhemer, 1989). While elastic strain occurs already during the drilling process, inelastic deformation is time-dependent and can endure for hours, days or weeks. To investigate the evolution of microcracks during core relaxation, two crystalline core samples were recovered from high in situ stress conditions in Europe’s deepest mine in Pyhäsalmi (Finland). Samples were prepared for testing within one hour after coring such that a large portion of the time-dependent component of relaxation could be recorded over several days using ultrasonic velocity as well as acoustic emission (AE) measurements.Results from AE analysis show an exponential decrease in the number of events over a period of several hours. Repeated sudden increases of acoustic events can be related to the propagation or the interaction of cracks. In the first hours of recording also the signal energies reached the highest values and the increases in signal energy correlate well with increased event rates. On additional drill cores, P-wave velocities were measured parallel and in 45° distances perpendicular to the core axis. After core recovery, stress-induced microcracking caused an exponential decrease in wave velocities similar to AE rates. Lowest compressional wave velocities were measured parallel to the core axis and thus normal to the foliation and in the direction of the maximum in situ stress component. The highest measured velocities occurred parallel to the foliation plane. Within the samples, the anisotropy ratios were up to 1.37 at the beginning of the measurements and increased to values of up to 1.8 after 45 days. The wave velocity anisotropy is in agreement with the in situ stress orientations."

Jan 1, 2015

By Joseph M. Denk, John N. Baran, William J. Francart

Filling or sealing shafts of underground coal mines is required when the mine is declared inactive by the operator, permanently closed or abandoned for a period of time greater than 90 days. Although shaft filling requires the use of incombustible materials for the first fifty feet of the shaft, a sparking potential may exist which has been reported to be the cause in at least one shaft-filling explosion. This paper outlines the method used at the explosion site to monitor mine gases within the shaft to assure the safety of the workers involved in the remainder of the shaft-filling operations. Gases which were monitored include methane, oxygen, carbon monoxide and carbon dioxide. Continuous sampling was conducted twenty-four hours per day to determine the methane liberation and accumulation of gases within the shaft. Once gas concentrations were evaluated, the need for ventilation in the shaft was obvious because methane accumulations within the shaft were in the explosive range. Several methods to ventilate the shaft were explored. The most practical seemed to be the dilution of gas concentrations with compressed air to inject a quantity of fresh air into the shaft. But, when the compressed air was stopped, a buildup of an explosive mixture reoccurred. The pattern of gas accumulation was then studied to find the correct combination of ventilation and shaft-filling time periods which would a1 low for the greatest reduction of the potential for an explosion. Gas concentration sampling continued during the remainder of shaft-filling operations at this shaft and four others at the same mine. In conclusion, this paper illustrates some of the problems which are often overlooked in a shaft-filling operation. If addressed, the work can be done in a safe and feasible manner.

Jan 1, 1987

By Kenneth E. Hay

Researchers from the U.S. Bureau of Mines conducted a field study to assess the safety of remotely controlled mobile roof supports (MRS) in a retreat pillar mining operation, Data were collected to provide the Mine Health and Safety Administration with criteria needed to develop guidelines for MRS use and to determine if precursors could be identified that would alert miners to imminent roof falls. Two test sites at which two different support methods-MRS's and posts were used and were monitored to obtain information on entry stability. Pressure transducers and string pots were installed on all four MRS's to obtain loading and displacement information. and roof bolt load cells. sonic probes, extensometers, and survey targets were installed in the surrounding entries to obtain information on ground behavior. Results showed a larger increase in roof bolt loading and roof movement when MRS's were used, especially in the intersection area. Roof bolt loads in the entries showed decreases in load when the MRS's were set and increases up to 11,1 kN (2,500 lbf) when the MRS's were unloaded. Unloading of one MRS in a pair did not significantly increase load on the other. MRS's I and 2 usually had the higher loads, with these loads increasing as the pillars on each side were being mined. MRS 3 normally had lower loads than I and 2: however, it also experienced some very high loads when in the last position near the pushout. MRS 4 usually had the lowest loads, primarily because it was located near the solid pillar that was not being mined.

Jan 1, 1995

By S. Ramatsoma, D. N. C. Phillpotts, B. Whitehead

Changes in flotation performance have been correlated to changes in froth structure, velocity and stability. Literature has shown that when the aeration rate is varied for a specific float cell, the recovery of the valuable mineral reaches a peak which also coincides with a peak in the air recovery – a measure of froth stability. Peak air recovery optimisation methodology is a way to use direct readings of physical phenomena by froth cameras to optimise the metallurgical performance of a flotation plant. The aim of this paper is to show the transient nature of the peak air recovery value and the variety of conditions required to attain the peak air recovery on an industrial flotation plant with tight base-layer control of the feed and internal conditions. Industrial site tests that were conducted under controlled conditions showed different peak values at significantly different corresponding aeration rates during normal operation. The measured peak air recovery points corresponded to maximum PGM recovery during normal flotation, as expected. This dynamic nature of the peak air recovery point conditions has not previously been discussed in literature and indicates the need for online measuring equipment and informs the design of process control algorithms required to exploit the phenomenon for optimisation. Keywords: Froth flotation, flotation control, flotation optimisation, peak air recovery

Jan 1, 2020

By Stephen Buttling, Zhong Rui

"A single unit gas fired power station was being built on the edge of the Gulf of Thailand in 2001. The soil conditions consisted of very soft to soft Holocene Marine Clay, and the site was part of a coast line which had been subsiding below high water mark for some time. In order to provide access around the power station a road system in a figure-of-eight formation was required, and this also needed to be above the design flood level, allowing for future settlement. A ground improvement scheme was proposed and constructed, which consisted of two spacings of prefabricated vertical drains (PVD) over two depth ranges, vacuum consolidation and pre-loading, and rigid inclusions.During the construction phase, the vacuum consolidation was applied for 202 to 221 days in different zones, and monitoring allowed a prediction that the future settlement, including secondary consolidation over a period of 25 years, would be within the range of 175 to 355 mm, which met the contract requirement of less than 400 mm.The power plant was completed and became operational in 2003. Monitoring of the road levels continued, as did the settlement, and in early 2010 the total settlement since the end of vacuum consolidation had reached about 800 mm. The monitoring data both during the ground treatment and for the following 7 years is presented and analysed. This is supported by numerical analysis using 3D finite element methods which shows good agreement with the measured data, and allows a preliminary explanation as to why the predictions were so far out.BACKGROUNDAfter a period of bidding and negotiation, the Eastern Power and Electric Co Ltd (EPEC), an Independent Power Producer, entered into an agreement with the Electricity Generating Authority of Thailand (EGAT) in November 1997 to sell them power. In 1999 an Engineering, Procurement and Construction (EPC) contract and an Operation and Maintenance contract were signed with a supplier to provide a gas-fired (with oil as a back-up fuel) 350 MW combined cycle power plant in Bang Bo, Samut Prakarn Province, east of Bangkok. The site of the plant at Bang Bo is located immediately to the east of the Samut Prakarn Wastewater Treatment Plant, adjacent to the Gulf of Thailand (see Figure 1) in an area of very soft to soft marine clay (Bangkok clay) having low shear strength and potential for excessive settlement. The site layout comprises the main Power Plant components of generating block, cooling towers, fuel unloading area and storage tanks, switchyard and administration block, separated by access roads."

Jan 1, 1900

By Richard E. Thill

Backfilling of mine voids is used to prevent or control the effects of subsidence on surface structures. The pumped-slurry, blind-backfilling process has been particularly successful for stabilizing ground over abandoned and inaccessible underground coal mines. Using this newer technology, vast quantities of backfill material can be distributed over wide areas in underground openings from a small number of injection boreholes. The rapid and successful development of this backfilling method, however, has outstripped technology for monitoring and controlling backfill placement. Surface or borehole remote sensing methods are needed to determine where fill material is being distributed underground and how effectively the material is packed in the voids. In search for improvements in backfill monitoring and control technology, potential remote geophysical sensing, process monitoring, and tracer methods were evaluated to select candidate systems for monitoring backfill placement under the constraints imposed by the injection process and the surface and subsurface conditions. ' A multiple objective ranking matrix, based on theoretical considerations as well as pragmatic experience with systems working in related or similar conditions, was used to narrow down potential methods to several most-favored candidates. Two of the candidates were field tested under actual operating conditions at a backfilling site in the Wilkes-Barre-Scranton region of northeastern Pennsylvania. Although process and acoustic emission monitoring indicated promise for improving existing backfill monitoring technology, more extensive testing under different conditions at various sites is required to establish the validity and utility of these methods. Results indicate that no single method is adequate in itself for backfill monitoring, and that a successful system will require the Integration of several methodologies.

Jan 1, 1982

By F. Charette

The paper reviews the requirements of the instrumentation required to monitor mining excavations in a high stress environment, and the development plan to instrument the D-Bolt in such a fashion as to be able to follow the behaviour of the bolts in relationship to the ground movements and support performance. Recent field observations of D-Bolts under static and dynamic conditions are also presented. Also discussed is the assumed mechanical behaviour of the D-Bolt. D-Bolts are used in two (2) Canadian underground mines operating in high stress environments and tested in three (3) other operations.

Jun 1, 2012

By B. Papilon

Dynamic pressures during blasting can affect performances of both electronic and non-electronic detonators. Boreholes can develop tremendous amount of pressures during blasting. The effect of such elevated pressure especially during electronic delay countdown is probably more acute in electronic detonators. Measuring the pressures during blasting can aid to understand the relationship between magnitude of the pressure developed and the multitude of blasting conditions.

Jan 1, 2013