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By J. N. Van der Merwe

The principal goal of the research described in the paper was to determine, by measurement of pillar scaling on pillars that have not failed, whether the pillar life prediction method developed by van der Merwe (2003) was valid as it stood or whether adjustments were necessary to the rates indirectly derived from observation of failed pillars. To this end, measurements were taken on over 350 pillars at 13sites on 6 mines. The project was done as a collaborative effort between the University of Pretoria, the Nancy School of Mines and CSIR Miningtek. During the course of the investigation, it was found that the majority of pillars display maximum scaling at mid height, that there was no clear preferential direction of pillar scaling, and that pillar corners do not scale significantly more than the mid pillar areas. The most important conclusion was that the scaling rates found by measurement agreed with the inferred rates found in the previous work. The previously developed procedure for the prediction of pillar life spans consequently requires no adjustment, although the error span is in the region of 20%. It is recommended to do further research into the effect of sealing of panels and, possible chemical changes taking place in the pillars as they age on the scaling rate.

Jan 1, 2004

By D Craw, P Upton

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Otago Schist belt of southern New Zealand hosts widespread orogenic gold deposits. Erosion of these orogenic gold deposits has led to the formation of numerous placer deposits distributed across and beyond the host schist belt. Numerical modelling of crustal scale deformation and geomorphic evolution has defined the key tectonic features that have controlled the severance of detrital gold deposits from their sources. Tectonic activity over the past 20 million years, during development of the modern Pacific-Australian plate boundary, has severed links between some placers and their sources. Detrital gold was transported south from the Otago Schist source region in two different river systems in the Miocene. Mesozoic orogenic gold deposits shed gold into rivers that flowed to the south. These rivers were terminated by the rise of north-west-trending basement ridges at the boundary between weak schist crust and strong greywacke crust, and the ridges were controlled by pre-existing faults at that rheological boundary. In contrast, rising mountains close to the developing plate boundary in the Miocene were the locus of new orogenic gold deposits hosted in extensional faults. These gold deposits were rapidly exhumed and contributed detrital gold to orogen-parallel Miocene rivers that flowed to the south-west. Pleistocene deformation on mainly north-west and north-east orientations, and associated river capture, has severed the links between these Miocene orogenic deposits and downstream detrital gold.CITATION:Craw, D and Upton, P, 2015. Tectonic severance of links between placer gold and its sources, southern New Zealand , in Proceedings PACRIM 2015 Congress, pp 541–544 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By D. Craig Camp

conditions. The soils included 65 m of rock not exceeding an unconfined compressive strength (UCS) of 200 kgf/cm2, 130 meters of soft clay, silt, and sand not exceeding 30standard penetration test SPT blows per 300 mm, and 220 m of rock ranging between an UCS of 400-600 kgf/cm2. The river crossing, utilizing 1778 mm OD x 19 mm wall x600 mm steel casing pipe without intermediate jacking stations, was part of a seven kilometer liquefied natural gas (LNG) transmission line in South Korea. This 440-m, 1,442-ft, river crossing was microtunneled through three different ground conditions and completed in just over three months. The crossing was achieved with an average of 25 m of ground cover and 15 m of water cover. The Kwang Yang River Crossing was part of a 7 km liquefied natural gas pipeline project for POSCO, a Korean steel producer. The microtunneling machine was custom built for this project. The microtunneling machine selected for this project was tooled with 7 button bits and 2 roller bits. None of the cutter bits were replaced during the drive. Inside the machine, before the spoils laden slurry was pump back to the surface, it would pass through an independent cone crusher. The crusher is placed in the slurry flow to make sure that none of the spoils are so large as to stop the return flow of the slurry. An additional requirement was for the inclusion of a compressed air lock. The air lock was required in the event that the cutter tools required replacement. The cutters were back loaded so that the workers would have access to change the cutters in the event of cutter failure or wear out. No intermediate jacking stations were installed for the drive. The soils included 65 meters of rock not exceeding an unconfined compressive strength (UCS) of 200 kgf/cm2 with production averaging between 7 and 20 mm/minute. The second zone contained 130 meters of soft clay, silt, and sand not exceeding 30 standard penetration test (SPT) blows per 300 mm with production averaging between 80 and 180 mm/minute. The third zone contained 220 m of rock ranging between an UCS of 400-600 kgf/cm2 with production averaging between 7 and20 mm/minute. The steel casing pipe was 1778 mm OD x 19 mm wall x 6000 mm long. The project profile, see Figure 1, shows the soil conditions. The hand written numbers locate just above the pipeline are the production dates. The circled numbers are the 10 pipe joint increments. The project required 74 pieces of pipe to span the440 m drive. Figure 2 and Figure 3 are the jacking information. Figure 3 is a continuation of the information from Figure 2. The top section of the graph is the jacking force. The jacking

Jan 1, 2001

By D. F. Malott

The Michigan Dept. of State Highways makes extensive use of geophysics for subsurface surveying which would be applicable for uses in other fields. Examples of resistivity surveys are given which include a proposed large-volume excavation with suggestions for land use after excavation, subsurface evaluation for engineering design, and a subsurface survey for land appraisal. An example of a combined refraction seismic and resistivity survey is shown where the resistivity is used for outlining the unconsolidated soils, while the seismic method is used to outline bedrock and to evaluate it for rippability. A refraction seismic survey at the bottom of bridge caissons for evaluation of bedrock uniformity and a rehtive aid in assessing rock strength is reported. These past several years have been a period of unprecendented construction and commercial expansion. Vast private manufacturing complexes and government road, power, and office projects are being built or are in planning stages. Nearly everywhere, municipalities are expanding outward and upward. Many towns are developing into cities and many cities are displaying new skylines, and the building boom shows little sign of slowing down.

Jan 1, 1970

By S. Fuentes, J. Cáceres

"During the past fifteen years, mines utilizing the block caving method have improved performance and systematically reduced total mining costs.This paper describes improvements in mine design, mine planning, and mine management, including methods enabling the Chilean and international mining industry to ensure cost savings and productivity growth while using the block caving method. These improvements have encouraged the re-evaluation of underground operations at operating and closed open pits, and challenge surface mining applications as the only low-cost mining method. This paper describes a strategy to estimate the optimum open pit to underground transition time during the life of a mine. IntroductionDuring the last fifteen years, block caving mines have experienced huge changes in designs, planning and administration. These changes have permitted operators to drastically reduce costs, improve equipment productivity, and improve overall business performance. As a consequence of this situation, the block/panel caving mining system is challenging actual open pit operations to maximize the net present value (NPV)."

Jan 1, 2004

By Raymond Philippe

Background ?Hatch Water has worked with most major mining companies in Chile on water supply and optimization projects ?Many(copper) mining projects are located in Northern Chile, which hosts the driest desert on earth Water supply options in Northern Chile ?River ?Availability/Rights ?Well(Brackish) Water ?Availability/Rights ?Municipal Wastewater ?Water rights ?Volume ?(Desalinated) Seawater ?Infinite source ?Cost depends on distance and altitude ?Recycling/Reutilization ?Water losses All these options present water quality issues

May 1, 2009

By John C. Machisak

INJURY and employment figures for nonmetal mines and mills in 1959 are presented in this publication. Data for nomnetal mines are presented separately from those for nonmetal mills. The Bureau of Mines is authorized to send questionnaires to the nonmetal mining industry each year requesting their voluntary submission of injury experience and employment data. The voluntary response to these requests has contributed greatly toward the promotion of safety in the industry, and every effort has been made to make the information as complete as possible.

Jan 1, 1963

By M. R. Saharan

A brief overview of rockburst control measures is presented. The paper then elaborates on one key rockburst control measure, which is known as destress blasting. A historical background of the technique is presented in order to understand different aspects of its field application. The publication enumerates key aspects of the technique as being used in practice in South Africa and North America. The paper also presents an analysis of three case studies in order to demonstrate difficulties associated with the field application of distress blasting in hard rock mines.

Jan 1, 2006

By L. W. Saperstein

Public Law (PL) 95-87 contains explicit demands for land use planning in its reclamation and designation sections. Both sections require recognition of local land use plans; however, they are not well integrated. Accommodation to these planning requirements affords an opportunity to create better links among local land use planners, the state's permitting authority and designation office, and mine designers. Mining companies should take a more positive interest in local land use plans and in resource inventories. States should consider handing down to local government the responsibility for accepting mine permit applications and designation of unsuitability petitions.

Jan 12, 1983

By David S. Yantek

Miners in underground coal mines experience prolonged exposure to high noise levels, often with A-weighted sound levels in excess of 90 dB. Field tests have shown that the continuous miner conveyor is a dominant noise source. This paper will identify the most significant noise-radiating surfaces on the continuous miner tail section using vibration levels and surface areas to estimate the sound power levels of each surface. In addition, using five test cases, this study will examine the effects of three engineering noise controls on the surface-averaged vibration levels and average sound levels measured with four microphones located two meters from the tail section. The noise-radiating surfaces of the conveyor’s tail section include the top and bottom decks, the sideboards, and the flex plates. Emphasis is placed on the changes in the estimated sound power levels in the 500 – 2500 Hz 1/3-octave bands since this frequency range accounts for 80-85% of the sound energy near the tail section. The results show that the bottom deck is the most significant noise radiator for the untreated miner. Installing a coated bottom deck reduces the estimated sound power level radiated from the bottom deck by 11 dB and the average sound level by 2 dB. Using a coated tail roller results in reductions of the estimated sound power levels for individual components from 1 to 4 dBand reduces the average sound level by 2 dB. Coating the slide plate has little effect on both the estimated radiated sound power levels and the average sound level. The test results indicate that modifications that reduce flex plate vibration and reduce energy transfer from the tail roller into the tail section will be effective in reducing noise when combined with a coated tail roller and coated return deck.

By Frank Chase

Longwall mining has gained the reputation as being the safest extraction method in underground coal mines. However, one of the most difficult tasks associated with longwall mining is moving the face once a panel is completed. Based on Mine Safety and Health Administration (MSHA) fatality reports since 1996, longwall face recovery operations have claimed the lives of 5 U.S. miners and have resulted in numerous injuries. Recovery operations can be hazardous because they involve moving large pieces of equipment in very confined spaces. They are also conducted in highly stressed ground conditions due to front abutment loads generated by panel extraction. Shield removal is the most hazardous operation during face recovery because miners are constantly exposed to the unpredictable gob edge. To protect the miners, one or more walking shields, cribbing and/or other supplemental roof and standing supports are typically employed as breaker line supports as each shield is removed. At the Harris No. 1 Mine in southern WV, mobile roof supports (MRS?s) have been used in lieu of traditional walking shields on 17 face moves since 1997. MRS?s are shield-like support units mounted on crawler tracks and are commonly used during room-and-pillar retreat mining operations. For longwall recovery, the two biggest advantages that MRS?s have over traditional walking shields are that they are remotely controlled and are highly maneuverable. MRS?s have contributed to safer shield recovery and shorter move times at the Harris No. 1 Mine. This paper will address both the safety and the operational issues associated with MRS usage during shield recovery. It will also discuss new developments, including the use of the inherently safer battery powered MRS?s, which have been recently certified by the Mine Safety and Health Administration.

Jan 1, 2007

By Paul J. Sabatini, Yazen A. Khasawneh

"A Demag CC1800 crawler crane was partially erected on crane mats adjacent to a seawall when settlements near a corner of the crane mat area were observed to be slightly larger than previously assessed. A ground improvement program including installation of dry soil cement mix (DSM) piers was implemented to improve soil bearing capacity. Due to near-surface obstructions, only 75 percent of the DSM piers were installed to the design depth. Because of the partial installation of the DSM piers, an evaluation of the crane pad stability and the effect of the crane loading on the stability of an adjacent 10-ft high concrete seawall, which was believed to have limited (if any) reserve capacity, was required. A two-dimensional finite element model was developed to evaluate the responses of the partially improved ground and the sea wall to the loads imposed by the crane. Geotechnical site investigation and laboratory testing programs were performed to better define the subsurface conditions near the area where settlements occurred and to provide the required mechanical parameters for the soil constitutive model. Analysis results indicate that total and differential settlements of the crane pad and the increase in load on the seawall were tolerable provided limited excavation and replacement of weak dredged soils outside the DSM area would be implemented.INTRODUCTION & BACKGROUNDA Demag CC1800 was erected on 8 ft × 16 ft crane lattice mats at about 12 ft from an existing seawall. Approximately 3.5 in. of subsidence was observed at one corner of the crane mats, while the crane was partially erected and stationary. The approximate location of the crane mats with respect to the existing seawall when the subsidence occurred is shown on Fig. 1.The seawall consists of a reinforced concrete wall connected by reinforced concrete bents to a composite section of sheet pile wall; the total depth of the seawall is about 29 ft. The bents are spaced at about 20’4” and supported by five piles at each bent location. The composite sheet pile consists of concrete and a sheet pile section with a reinforced concrete wale section. The retaining wall is about 10 ft in height and is supported at three levels. The first support level comprises a 2-½” diameter steel rod near the top of the wall spaced at 40’8” the second and third level supports comprise 1-½” diameter steel rods spaced at about 5’6”. The second level support is inclined at about 10 degrees below horizontal and the third level support is oriented horizontally through the wall footing. A schematic of the seawall section is shown on Fig. 2.A geotechnical site investigation was implemented soon after the subsidence was observed. The program included advancing four borings to a depth ranging from 16 ft below ground surface (bgs) to about 30 ft bgs. In general, the investigation showed sandy material (likely fill that was used behind the retaining wall) from the ground surface in two borings located immediately behind the retaining wall. The other two borings furthest from the retaining wall showed very soft to soft clay (possibly dredged material) from the ground surface to a depth of about 10 ft bgs. Based on this information, the ultimate bearing capacity of the subsoils was estimated to range from 1,200 to 2,000 pounds per square feet (psf). From the anticipated crane loading (weight of the crane and loading lifts), a minimum allowable bearing capacity of about 1,500 psf would be required for safe operation. To achieve the required bearing capacity a ground improvement program was selected and implemented."

Jan 1, 2017

By R. Siy, O. Neiman, B. Hilscher

"A full-scale prototype of “Jameson Downcomer” technology has been installed and tested on a Tailings Oil Recovery (TOR) vessel in Syncrude’s Mildred Lake extraction plant. Jameson Downcomers are a type of mineral flotation equipment used in the coal industry that Syncrude has extended to the recovery of secondary bitumen in the oil sand extraction process. The TOR vessels are currently being operated as single-gravity separation vessels, in series with the Primary Separation Vessels (PSV’s). We have developed a model to differentiate between “floating” and “non-floating” bitumen in the PSV’s, and then applied it to verify that the current TOR performance only captures the “floating” bitumen by simple separation. The existence of “non-floating” bitumen provides an opportunity for recovery enhancement by means of the Jameson Downcomers. To achieve bitumen recovery enhancement, middlings slurry is withdrawn from the TOR vessel, and passed through a number of parallel Jameson downcomers, within which the slurry is accelerated to a high-velocity free jet, and impinged upon the slurry surface inside the downcomer, in the presence of air. The aerated slurry is returned to the middlings zone inside the TOR, resulting in an incremental recovery improvement of bitumen in the TOR. The operation of the downcomers is thought to produce suitably small air bubbles for the flotation of bitumen, either by fluid shearing during the slurry jet impingement, and/or by micro-bubble nucleation. This full-scale prototype design has met or exceeded the recovery expectations of the original Research piloting, recovering at least 40% of the non-floating bitumen. In Syncrude Extraction, this provides high business value by a separation efficiency gain achieved with modest expenditure. As well, the system has demonstrated excellent operability and maintainability.INTRODUCTION Syncrude Overview Syncrude Canada Ltd. is one of the largest producers of crude oil from oil sands. Our crude oil production facility has the capacity to produce over 15% of Canada's total oil requirements. To do this, we surface mine oil sand, extract the raw oil known as bitumen from the sand using water-based processes, and upgrade that bitumen into sweet light crude oil by fluid coking, hydro processing, hydro treating and reblending. Our final product, Syncrude Crude Oil (SCO), is sent by pipeline to three Edmonton area refineries and to pipeline terminals which ship it to other refineries in Canada and the United States. The Syncrude operation is comprised of four major technology areas: Mining, Extraction, Upgrading and Utilities. As well, Syncrude invests more than $40 million annually in science and technology, and is among the top 50 companies in Canada for Research and Development (R&D) investment. Syncrude holds 21 active Canadian and U.S. patents."

Jan 1, 2012

By J. J. Bouillon

"Located in the northwestern portion of the Abitibi greenstone belt, Les Mines Selbaie is a copper-zinc (silver and gold) producer. Felsic tuffs host three are zones. Composed of sulphide veins and breccias, they are not exhalative massive sulphide deposits, except, probably, for the massive pyrite (fragments and lenses) localized close to the top of the volcanic sequence.The total of all (mineable and mined) ore in the three zones presently outlined on the property, is of the order of 29.9 x 106 tonnes with average grade of 0.63 g/t Au, 37.02 g/t Ag, 1.21% Cu, 1.91% Zn.The ore reserve calculations and the daily production procedures are computerized to various degrees. The data handling process is highly computerized.Various geophysical methods are, and have in the past, been successfully used on the property. The ""mise-à-la-masse"" surveys were used to perform the geological interpretation of an underground deposit (A-2 zone). Presently the PULSE-EM surveys are performed in all surface and underground exploration drill holes."

Jan 1, 1990

Jan 1, 2004

Remote methane detection State and federal regulations require frequent measurements to verify that safe methane levels are maintained in underground coal mines. Ventilation control is the primary means of maintaining safe methane levels. In the immediate face area, where the highest methane levels occur, methane measurements are required every 20 minutes during active mining. To perform these measurements, temporary roof supports must be erected. This allows a miner to reach the face. There a hand-held methanometer is used to make the measurements. This procedure is time consuming and potentially hazardous. To facilitate the measuring process and reduce the miner's exposure to roof falls, the US Bureau of Mines has developed a prototype optical device. It can measure methane remotely from distances up to 12 m (40 ft). The device uses two infrared signals, reflected from the coal face, rib, or roof. One signal is absorbed by the methane, the other is not. The ratio of the two signals determines the average methane concentration in the face area. The prototype detector has also been successfully tested at the Lake Lynn, PA Laboratory. Instantaneous responses were obtained for methane in the ventilation airflow and for methane layered near the roof. Conventional methanometers required from five to 25 seconds to respond to the methane in the ventilation airflow. They did not respond to methane in the roof layer. For more information about the Bureau of Mines' remote detection research, contact Richard W. Watson, US Bureau of Mines, Pittsburgh Research Center, Box 18070, Cochrans Mill Road, Pittsburgh, PA 15236 or call (412) 892-6630. Ignition suppression system The incidence has increased of fractional spark ignition at the mine face. One reason is the advent of mechanical mining. Another is the more difficult ventilation conditions associated with deeper and more extensive underground workings. To cope with the problem of frictional ignition, the Bureau of Mines initiated research to develop a system that would provide rapid detection of incipient methane-air ignition. Then, rapid dispersion of a quenching agent would ensure that the methane flame was extinguished while it was still relatively small. This concept was successfully demonstrated by suppressing explosions in the Bureau's Bruceton, PA experimental mine. But the bulkiness of the early storage-dispersal system proved impractical to retrofit onto face equipment. In a cooperative effort by the Bureau and the Mine Safety and Health Administration, a more compact system has been developed and is being tested. A continuous mining machine has been equipped with four 1.8-m-long (6-ft-long) and two

Jan 9, 1987

By R. W. Watson

A belt-wearable self-contained self-rescuer (SCSR) manufactured by the CSE Corp. and designated the "SR-1OO" was evaluated for safety in the underground mine environment by the U.S. Bureau of Mines. The evaluation consisted of laboratory tests on the chemicals contained in the unit and field trials to simulate the mine environment. This report summarizes the test results and compares the results with those from earlier tests with chemical and compressed oxygen self-rescuers. It was concluded that the new SCSR did not pose any different or more severe hazards than the earlier units. In view of the mine-proven safety record of the SCSR's now in service, no reason could be found to disallow use of the belt-wearable unit.

Jan 1, 1991

By P. C. Schutte

There have been several high-profile accidents in the South African mining industry where fatigue was identified as either causal or contributory. The risk of fatigue is inherent in any work-time arrangement involving shift work and work that is physically or mentally demanding, repetitive, or requires high vigilance. The management of fatigue is not simply a matter of correct shift scheduling. Amore comprehensive approach is needed. In order to be successful, a fatigue management programme should address the unique needs of the operation in which it will be implemented and should be integrated into normal operations. Fatigue management is a shared responsibility between the organization and its employees, and all stakeholders should participate in order to provide the safest and healthiest working environment possible.

Jan 1, 2010

By K. Oraee

Zarshuran gold deposit, with the total reserves of some 12.5 million tons of 4.18 g/ton ore, is considered to be an important gold mining project in the area. In this paper the feasibility studies of the whole project is carried out on the basis of several economic variables. Given that mining data are often of uncertain nature, these economic variables have therefore been estimated under the conditions of uncertainty. The resultant Net Present Value is hence also obtained under the same conditions. For this purpose, a model is first devised with the help of Excel and COMFAR software. The model is then developed that considers different scenarios which would result in different expected values for the economic variables. It is concluded that the NPV of the project is most sensitive to gold and silver price and that other variables such as discount rate, operating and capital cost all affect the feasibility of the project with lower degree of severity. Finally, risk analysis is also carried out using Mont Carlo technique, in order to estimate the most probable value of NPV. The average NPV calculated in this way is US$ 49.7 Million, whilst without due consideration of risk, this would be US$ 36.6 Million. The techniques used, together with the procedures adopted in this paper, can be used in feasibility studies of all mining projects. Such decision would result in more accurate Net Present Values than expected from other frequently used methods.

Jan 1, 2011

By James M. Baugher, Donald W. Conrad, William J. Wiehagen

This report describes a process for quickly developing information that is useful for skills training. The process is called job training analysis (JTA). Its main use is to structure skills training at the jobsite. JTA supports structured skills training by identifying the job duties, tasks, and steps and the reasons why those job components are important. The outcome of the JTA process is a worksheet—a training outline based on the knowledge and expertise of experienced workers. Time invested in developing a JTA will result in significantly more time saved when it is used appropriately by skilled trainers. Like a roadmap, JTA saves time and energy. Experimental work at several mine sites helped document, refine, and validate the JTA process. JTAs for two mining jobs—roof bolting and lift truck operation—at two different mine sites are used to illustrate some of the concepts and the specific JTA process described in this report. The work at these two sites was influenced by cooperative work between the Mine Safety and Health Administration (MSHA) and the National Institute for Occupational Safety and Health (NIOSH) at several other mine sites and prior collaborative work with the U.S. Navy. The mining JTA process is grounded within the military research on the design of instructional systems. MSHA and NIOSH worked to simplify and apply the military training development model for mining industry use through collaborative work at several mine sites. The JTA process involves three activities: (1) planning, (2) a 1- to 3-day workshop where the JTA is developed using facilitated work with subject-matter experts, and (3) followup. Guidelines and considerations for each of these activities are included. Results indicate that the JTA process has been well received and valued by mining industry participants. It blends aspects of health and safety, production, maintenance, and crew coordination.

Jan 8, 2006