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By P. R. Taylor

A cyclone reactor system for the partial reduction and melting of taconite concentrate fines has been engineered, designed and operated. A non-transferred arc plasma torch was employed as a heat source. Taconite fines, carbon monoxide, and carbon dioxide were fed axially into the reactor, while the plasma gas was introduced tangentially into the cyclone. The average reactor temperature was maintained at above 1673 K (1400 C), and reduction experiments were performed under various conditions. The influence of the following parameters on the reduction of taconite was investigated: carbon monoxide to carbon dioxide inlet feed ratio, carbon monoxide inlet partial pressure, and average reactor temperature. The interactions of the graphite lining with carbon dioxide and taconite were also studied.

Jan 1, 1993

By Ray Nivens, Umit Turunc, Caroline Sui, Nick Morrison, Douglas Steiner

"In most copper mines and concentrators, mill water is continuously recovered and reused, with fresh water added to make up for losses. When mixed, these water chemistries can lead to severe scaling, especially in pipes, tanks and pumps on the mill water supply side, reducing flows and causing significant production losses.At KGHM Robinson Nevada Mining Company, increases in the fresh water addition ratios resulted in severe scaling problems and premature pump failures thereby jeopardizing plant production. What initially appeared to be a few isolated scaling events eventually unfolded into a recurring pattern of water supply-related production losses with increasing severity. Through completion of detailed root cause analysis, chemistry modeling, laboratory work, in-plant testing and system engineering, the mechanisms of scaling were identified and addressed.Advancements in fresh water addition practices and antiscalant application methods resulted in a stepwise reduction of the mill water scaling. Cost savings and production benefits were significant to the plant’s financial metrics.IntroductionThe production of mineral and metal concentrates using the flotation process requires large quantities of water. Flotation is utilized as the primary means for beneficiation with sulfide ores. Mined ores are crushed and ground into a slurry of 20-55% solids. For each ton of ore, 400-900 gallons of water1 are needed to supply the grinding mill. Additional water is needed in the flotation circuit as well. With many modern mills operating at2 11,000-165,000 tons/day, water supply volumes can be upwards of 3,000 gpm to 100,000 gpm of flow.For plants operating at or above capacity, disruptions and restrictions in water supply flow can have a direct impact on the production and recovery of the metal. Water supply flow can be limited for a wide variety of reasons but of interest are those limitations that are due to mineral scaling. Mineral scaling is the selective point precipitation of inorganic species above saturation concentrations. Precipitated species form flow-restricting deposits in the mill water system (tanks, pumps, pipe and valves), that will eventually impact water supply to the concentrator."

Jan 1, 2017

By R. L. Virta

Six companies mined fire clay in Missouri and Ohio during 2004. Production, based on a preliminary survey of the fire clay industry, was estimated to be 398 kt(438,700 st), valued at $9.81 million. This was slightly less than the production and value figures from 2003. Missouri was the leading producer state. It accounted for more than 70 percent of the U.S. production. Consumption Domestic producers sold or used fire clay primarily for refractory applications. This application accounted for 79 percent of the market. Refractory products made using fire clay include firebrick and block, grogs, high-alumina brick and specialties, refractory mortars and mixes, and saggers.

Jan 1, 2005

By A. Cole, A. Bolland

The roasting and gas handling circuits at Goldstrikes' new Roasting Facility incorporate proven technologies in a unique combination. During the design of the plant, every effort was made to utilize the best available unit operations from the perspective of capital, environment and operating costs. The roaster utilizes Freeport-McMoRan whole ore roasting technology with pure oxygen as the oxidizing gas. This process was chosen based on its proven application on Carlin-type carbonaceous ores. An extensive gas cleaning train follows the roaster and comprises direct cooling, dust scrubbing, indirect cooling, wet electrostatic precipitation, mercury scrubbing, SO2 scrubbing, CO incineration and NOX reduction.

Jan 1, 2001

By Z. T. Bieniawski, E. H. Skinner, R. A. Cummings, F. S. Kendorski

INTRODUCTION Caving Mine Drift Support Design The support of production drifts remains a high-cost item facing the developer or operator of an underground caving mine. Support costs are incurred well in advance of ore production, and there is a strong need to minimize these pre-production commitments of capital. Due to the extensive rock loads that normally develop during the caving process, the support used in caving mines is typically quite heavy and therefore costly. The process of designing this support increasingly makes use of basic tunneling principles, but is hindered by the still-incomplete state of knowledge of rock behavior in caving mines, and high variability of geological conditions in caving orebodies. Caving mines differ from tunnels in that the deformations and rock loads induced are transient and dynamic in occurrence, and are normally large in magnitude, often well in excess of rock mass strength. As opposed to tunnels, caving mine layouts are more intricate, and the methods and effects of construction ordinarily are not as closely monitored. Safety factors in mining tend to be lower and rock masses tend to he weaker. These aspects prevent strict application of tunnel design technology to caving mine drift support, with the result that mine drift supports are commonly designed chiefly on the basis of experience at other mines. Mining procedures at caving mines are evolved in response to site-specific requirements, to the extent that there are really as many caving methods as there are caving mines.

Jan 1, 1983

One of the most important parameters in mine ventilation planning is the friction factor (K). Accurate values of friction factors are critical especially when carrying out mine ventilation simulations. No computer simulation of a mine ventilation network is meaningful if the airway resistances are not accurately estimated (when planning a new mine) or measured (for an existing mine). However, in the first case not many reliable values of friction factors exist in the international literature. This paper presents the results of a research project carried out in the province of Quebec where ventilation friction factors were measured in all underground metal mines. These friction factors are statistically analyzed and tabulated. A friction factor database was created that also includes the friction factors measured in the past by other people. This database can help the mine engineer to accurately estimate ventilation friction factors according to the specific conditions. This database offers several values of friction factors typical for hard rock mine conditions typical of modern underground metal mines.

Jan 1, 2009

By S. Tuylu, D. Adiguzel, A. Bascetin, E. G. Savas, O. Ozdemir

"Paste Technology has some advantages comparing to other surface disposal methods. With this method, it is possible to pump high concentrated solid materials to very long distances without segregation problem. However, it is known from Literature that pumpability of materials is completely related to rheological properties of the materials. For this reason, in this study, the rheological parameters (e.g. yield stress and viscosity values) of the paste material prepared from Pb-Zn tailings at various solid ratios (60-85%) were obtained in order to determine the pumpability of the paste material. Additionally, slump tests, which are usually used in mining industry, was carried out. Finally, regression analysis was made between the slump values and rheological parameters of the paste material to find a correlation between two independent parameters. The results showed that there is a great correlation between the slump values and the yield stress of the material. On the other hand, there was no correlation with viscosity: ty=430.28-16.877Sv (R2= 0,94; ty: Yield Stress (Pa), Sv: Slump Value (cm)). Based on the results obtained from this study, it can be clearly concluded that the slump values obtained from a simple test can be used to predict yield stress values of paste materials. INTRODUCTION Recently, surface disposal of mining tailings has become one of the biggest problems in mining industry in terms of environmental issues. Therefore, several researches have been focused on this subject in order to find a best solution or method for this problem. These studies showed that paste technology has some advantages compared to other conventional methods. Tailings thickened to the extent show no segregation of particles during transportation, and relatively small amount of settling occur post-deposition which are often called “paste” (Cincilla et al. 1997). Paste tailing technology has two applications in the industrial area as underground paste fill and surface paste disposal. Paste tailing technology was first started to be used in Grund mine, Germany in the late 1970s (Grice, 1998). Process tailing material, water and - if needed - cement materials, which are the components of the paste, must be blended to obtain a homogenous mixture suitable for pumpability. Consistency behavior of the paste material is determined using a conventional sedimentation cone concrete test (slump). Meanwhile, the slump value of the paste must be between 200 and 250 mm for surface applications (Newman et al., 2001). Additionally, in the case of underground paste system, the optimum slump value must be between 150 and 200 mm. On the other hand, the water content and density of paste at certain slump value change depending on the amount of fine particles in the tailing sample. While moisture of the material will be high, its density will be low because of surface area of particles which increases with decrease in particle size (Meggyes and Debreczeni, 2006). For pumpability of the paste to long distances, slump value of the paste must be good enough to be accepted for use of surface paste disposal. Paste material has a yield stress because they show non-Newtonian behavior and generally is classified as a Bingham plastic fluid. (Cooke, 2008; Theriault, 2003). In addition, the appropriate viscosity value of the paste along with the yield stress must be between 100 and 250 Pa (Bascetin et al., 2013; Bascetin et al., 2014; Bascetin et al., 2015)."

Jan 1, 2016

By E. J. Haas

DISCLAIMER The findings and conclusions in this paper are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health. ABSTRACT Leadership is a critical component to an organization’s safety culture and influences the ways that health and safety is enacted on site. Therefore, it is not surprising that improving leadership will also improve safety. Worker perceptions of management practices are shaped through unique leader-employee interactions over time. However, few details are known about the communicative support (i.e., emotional, informational, and tangible) offered by supervisors and its impact on miners’ perceptions and performance. Using pre and post-interview data with 20 supervisors and 48 workers during six-week interventions, researchers identified positive and negative instances of supervisor support and its implications on worker performance. This paper highlights the common support tactics offered by supervisors and desired by workers to help practitioners identify ways to improve their safety culture and subsequently, the proactivity and compliance of their workforce. INTRODUCTION Supervisory leadership is a critical component to the effective implementation of an organization’s health and safety management system (HSMS). Specifically, supervisors serve as representatives of an organization and their actions are indicative of the organization’s safety culture (Eisenberger et al. 1986). Senior management has been shown to serve as a frame of reference for guiding safe behaviors in the workplace (Mearns et al. 1998) and, more recently, research has related supervisory enforcement to workers’ safety compliance (Petitta et al., 2017). Therefore, it is not surprising that by improving leadership, perceptions of management and subsequent safety outcomes are likely to improve as well (Zohar, 2002). Perceptions of management are shaped through unique leader-employee interactions over a period of time (Hofmann and Morgeson, 2004, 1999). How these unique interactions impact worker performance, however, remains unexamined. As a result, understanding how supervisor-employee relationships operate in high-risk environments is unclear (Mirza and Isha, 2017; Denis et al., 2010). A starting point to better recognize the idiosyncrasies of these relationships is by way of examining the communicative support offered by front-line management and received by industry workers. To this end, this paper uses pre- and post-interview data to study the communicative aspects of supervisor-employee interactions at mine sites. The analysis uses a social support framework to identify positive and negative instances of supportive communication. From interview data with 20 managers and 48 mineworkers, data emerged that shows how supervisors’ unique types of support contribute to workers’ perceptions, motivation, and follow-through of safe work behavior.

Jan 1, 2019

By A. Taghavi, I. Hassan, A. Solecki

"The Eglinton Crosstown Light Rail (LRT) Project is part of an $8.4 billion investment to expand transit in the Toronto, Canada area and is the largest transit project initiated in Province’s history. Settlement control and impact to over 1400 adjacent structures due to tunnelling was identified early as a critical project risk. The ground conditions along the 10km tunnel alignment consist of water bearing soft ground deposits (clays, sands, silts) which required careful analysis and control during design and construction. This paper will describe the process used to analyze settlements along the numerous of adjacent structures and evaluate achieved settlement results to those used during design. The paper will demonstrate that with the appropriate design specifications, selection of modernized EPB machines, and contractor performance, settlement can be maintained well below typical industry (volume loss) standards, expanding the application and suitability of soft ground tunnelling in sensitive settlement areas. INTRODUCTION The Eglinton Crosstown Light Rail Transit (LRT) Project is part of an $8.4 billion (2010$ CND) investment from the Ontario provincial government to expand transit in the Toronto, Canada area. The project is being developed by Metrolinx, an agency of the Government of Ontario to provide 19 kilometers of dedicated LRT service connecting the City of Toronto from the west to east along Eglinton Avenue. Upon completion in the year 2020, the Crosstown will be the first LRT constructed in Toronto. It will link regional and local transit, cut travel time along the route by half and provide over a thousand jobs during construction."

Jan 1, 2016

By Gabriel Böde Jimenez Leon, Michael Karmis, Christopher Newman, Zach Agioutantis

"When utilizing high recovery underground mining methods, such as longwall or high-extraction room-and-pillar mining, the movement and deformation of the overburden propagate toward the surface and may affect the integrity of overlying surface streams (Peng et al, 1996). Published studies cite three major mechanisms of subsidence as most likely to impact streams: displacement, slope and strain. While subsidence-induced vertical displacement cause little structural damage to the stream bed, it may create adverse drainage and stream flow issues as the subsidence trough allows for ponding (Dawkins, 2003). Subsidenceinduced changes to the slope, or tilt, of a stream may have adverse effects on water flow. As the stream enters the subsidence trough, the gradient increases providing potential erosion control problems. When exiting the subsidence trough, a reduction of the gradient may inhibit stream flow, causing localized ponding (Peng, 2008). While vertical displacement and tilt both may have detrimental effects to surface streams, the resulting strains have been documented as being the most damaging to surface streams and structures causing distortion, fractures, or failure (Singh, 1992). When stream beds are subjected to high tensile strain, tensile cracks may form at the surface level allowing for the direct loss of stream flow through fissures. When stream beds are located in areas of high compressive strain, rock layers forming the stream bed can fail as the stream bed ruptures, upward, blocking stream flow or having the stream diverted into the fracture zone at the base (Iannacchione, et. al., 2010).Recent investigations on the effects of underground mining on surface bodies of water suggest that to determine the degree of stream impact one must also consider the geologic structure and thicknesses, surface topography, watershed drainage areas, width of river bed and rate of mining. Due to the complex nature and number of parameters affecting surface streams, subsidence modeling tools and software packages should be implemented throughout all stages of subsidence planning, prediction and control. The Surface Deformation Prediction System (SDPS) utilizes the influence function for the calculation of final subsidence deformations with respect to the angle of influence, supercritical subsidence factor as a function of the percent hard rock, edge effect offset distance, and surface topography. Developed more than 25 years ago, SDPS has been continually updated with new analysis and prediction features, providing a reliable and versatile program for subsidence management methodologies. Most recently, the program has been updated to evaluate the effect of varying surface topography in the prediction of horizontal displacements, referred to as ground strain, allowing for the accurate three-dimensional representation of surface deformations in mountainous terrain (Agioutantis and Karmis, 2014). Ground strain has become one of the predominant deformation indices used in the evaluation of potential damage to surface structures (Karmis et al., 1995). Ongoing work with SDPS software seeks to investigate the calculation of ground strain in SDPS and its ability to accurately and realistically predict damage to surface streams due to underground mining operations."

Jan 1, 2015

By John A. Wolfe

The concepts of sea floor spreading and plate tectonics provide more logical explanations of some geologic processes than were possible a few years ago. I plan to premise my discussion of the regional features of Philippine porphyry copper deposits on this tectonic basis, recognizing that parts of the picture can be explained in other ways, but in the belief that this is the best explanation of the whole. The sequence of events which results in the formation of Porphyry deposits (Figure 1) can be summarized as the result of collision of crustal plates, subduction of the oceanic plate, emplacement of a serpentine ultrabasic diapir, formation of a dioritic magma at depths of 300 to 500 km, rise of the magma to a sub crustal or intra-crustal chamber, eruption of andesitic volcanoes, emplacement of diorite or differentiation of the magma into more acidic products, multiple intrusion of hypabyssal rocks and hydro-

Jan 1, 1973

By Rebecca Mae Summer

Large scale surface mining has a major impact on land use. Without reclamation, abandoned mining sites are usually less productive than before mining. With increasing and completetive land use demands in the United States, it becomes increasingly evident that multiple land use should be considered for all areas that will be mined, with special emphasis on coal, sand, gravel, and stone. The mining of these commodities affects the largest land areas and the latter two are commonly mined near population centers where high land-use pressures justify serious consideration of multiple use. Typically, sequential use will mean restoration of the mined land or at least transformation of the land into a useable state. Determination of land reclamation capability is a viable approach to planning reclamation of surface mined land. The natural resource base--geology, soil, and water--controls the type and intensity of land-use practices which can be sustained following mining. Evaluating physical limitations can eliminate consideration of uses which would severely impair the environment or which are impractical. This approach provides for an environmentally and economically sound land use at very little cost. In addition, it can save or make money for the mining company and landowner. Sand and gravel is an especially significant resource because it is mined throughout the entire country and commonly extracted near cities. Increasing urban growth and industrial activity require increased supplies of sand and gravel. This translates into expanded surface mining and an increase of disrupted land. Oftentimes this land is within an urban area and has potential for real estate or water-based activities. Therefore, if reclamation is planned and carried out concurrently with mining, it is definitely feasible and

Jan 1, 1977

By Charles W. Daugherty

INTRODUCTION The Washington Metropolitan Area Transit Authority's (WMATA's) rapid transit system, Metro, ultimately will comprise 162.5 km (101 miles) of line divided among 10 routes. As shown in Figure 1, about 24 km (15 miles) of the system will consist of mined rock tunnels distributed along the A, B, C and K Routes. The structural construction contracts for all of the A, C and K Route rock tunnels are complete and trains are running in about one-third of them. A contract for construction of rock tunnel section B-9, the southernmost third of the B Route, was awarded on June 27, 1980. The final design of Sections B-10 and B-lla, the remainder of the rock tunnel portions of the B Route and the Metro system, are well advanced and should be under con¬struction by 1982. Of Metro's 87 stations, 11 will have been constructed by mining in solid rock, a not inconsiderable achievement, since each structure must be over 183 m (600 feet) long, wide enough to accommodate two trains and one or two passenger platforms, and high enough to achieve a stable arching action without encumbering columns. With the passage of years, some original priorities have been reordered, and ways have been sought to streamline and simplify this most complex of Metro structures without grossly violating the architectural standards that make it unique. This paper will summarize that search, and describe the design and construction aspects of the resulting product, the dual chamber rock tunnel station.

Jan 1, 1981

By Dermot M. Ross-Brown

The more important factors controlling the design of pit slopes are related to the local geology over which the designer has little or no control. Nevertheless, there are some factors over which the designer does exert some control and these concern the say in which the rock is excavated and supported. They include blasting, face cleaning, water control, and the use of rock improvement techniques. The paper discusses these factors and relates the extra costs incurred to the steeper slope angles that can usually be obtained. It is demonstrated that even a modest increase in bench angle of 5° through improved excavation techniques can pay off in a single push-back.

Jan 1, 1975

By D. M. Avant, S. M. Pickering

A variety of grades of very white muscovite mica are now being produced from sedimentary sands and clays in Central Georgia. The mica is naturally concentrated near the base of the lens-shaped kaolin deposits and also disseminated in associated quartz sands. The same weathering and bacterial alteration processes which have transformed the kaolins from dark organic muds to white pigment-grade industrial clays have also removed discoloring iron from the micas and developed unusually white muscovite. Further, chemical alteration has removed some potassium from the muscovite atomic structure, resulting in an easily delaminated mica which can be cleaved to unusually fine, high bulking, high aspect ratio products. The peculiar alteration history of these sedimentary micas enables production of some of the whitest, finest particle size, and thinnest aspect ratio muscovite mica products on the world market today. Raw mica feed is obtained from kaolin and sand processing by-products, and also from beneath the useful base of abandoned kaolin mines. The processed ultrafine and filler grade muscovite mica products are used for paint, plastics, cosmetics, mold release, thermal and electrical insulation, epoxy, and dry wall joint cement markets.

Jan 1, 2002

By G. Biles, K. Loughran, R. Anand

The Eskay Creek Mine, a high-grade gold and silver underground mine in northwestern British Columbia started operations in late 1994. For the first three years of operation, ore was crushed to minus 2 inch; blended to satisfy smelter terms and direct shipped to smelters in Japan and Canada. Before commencing the above operations, preliminary evaluations had indicated that an extremely complex metallurgical facility, requiring a large capital investment, would be required to recover the precious and other economic metals. Subsequently markets for raw ore were identified and underground mining and ore transportation operations, at a nominal production rate of 300 tonnes per day, were commenced. Exploration diamond drilling in 1995 and 1996 discovered additional lower grade mineralised zones, which are less economic or uneconomic as direct shipping ore. Test work demonstrated that these lower grade zones could be upgraded to marketable concentrates in a simple flotation mill. The mill was built in 1997 and has been in operation since late 1997. The mining rate now has increased to 400 tonnes per day including 250 tonnes per day of the direct shipping ore and 150tonnes per day of the mill ore. Prime Resources Group Inc. wholly owns the Eskay Creek Mine. Homestake Canada Inc. owns 50.6% of Prime’s shares and manages and operates the mine on Prime’s behalf. This paper discusses the mining and milling operations as well as ore shipment and smelter contracts' administration.

Jan 1, 1999

By William Gleason

"Sometimes it’s the smallest things that make the biggest difference. In the world of mining, erosion can lead to small cracks, which can then lead to bigger problems that, over time, can eventually lead to a catastrophic event. However, when managed correctly, as in the case of the Manefey Slide at the Bingham Canyon Mine in Utah, the damage can be minimized.Numerous industry conferences, technical papers, studies and resources are dedicated to these issues each year, but what is sometimes overlooked is how the erosion of personal ethics can also have life-changing effects.At the 2019 SME Minnesota Conference, April 15-17 in Duluth, MN, two inmates serving their respective prison sentences at the U.S. Federal Prison Camp in Duluth spoke to the conference about how small cracks in their ethical foundations grew over time, eventually leading each man to his new address at the minimum-security facility.The men’s full names were not released and they were introduced as Jeff and Tony. Other than the matching green uniforms, both middle-aged men could have fit in with the rest of the crowd. They are well-educated and articulate whose career paths eroded thanks to greed and careless decisions.Tony, a licensed professional engineer, enjoyed a successful career working in contract oversight for the U.S. Department of Defense. Jeff is a former senior vice president of investments who ran a well-respected investment management team. Both spoke openly about the mistakes they made and emphasized that their crimes were not flagrant violations of the black and white rules but grew from ethical violations that live in the gray area between black and white, and right and wrong.Working in contract oversight for the U.S. Department of Defense (DOD), Tony said he was befriended by a wealthy man who was generous with his money. As Tony told it, a few meals with this man led to a few trips to casinos and eventually to gifts of money. The donor did not ask for anything in return, and at the time, Tony said he did not think that he was doing anything wrong. He admits now that the perception of a high-ranking officer in the DOD accepting gifts is not a good one, as it could be construed as the donor might have been trying to gain favor for future contracts; which is how it was presented in court by the prosecution team."

Jun 1, 2019

By G. S. Hansford, C. J. N. Dempers, G. E. Searby, A. W. Breed, M. A. Jaffer

The bioleaching of sulfide minerals involves a ferric attack of the mineral with the role of the micro-organisms being the oxidation of the ferrous-iron back to the ferric form, and the oxidation of sulfur, either via thiosulfate or polysulfides, to sulfate. The kinetics of bacterial ferrous-iron oxidation and the chemical ferric leach kinetics of sulfide minerals can both be described as functions of the ferric/ferrous-iron ratio. The independently determined bacterial ferrous-iron oxidation and chemical ferric-iron leaching kinetics have been successfully used to predict continuous bioleaching operations.

Jan 1, 2000

By R. Owen

An overwhelming amount of data can be collected around the blasting process. This information can include blasting product, pattern design, blast results, and routing. It is only when these data sources are combined in a concise and accurate form that they are of real use in determining the safety and economic implications of each parameter. Two key technological aspects of blasting are drill fleet management (DFM) and size fraction analysis (SFA). As these technologies are integrated as near-real-time measurement and QA/QC tools, the resolution and realization of blasting parameters is significantly increased. The Freeport-McMoRan Morenci Mine has integrated these technologies along with other existing database structures to create a responsive and sustainable tool for reconciliation, forecasting and parameter matching. This ability allows Morenci to customize blast patterns to meet the criteria most critical to each shot, whether the impact is influenced by routing and recovery, equipment maintenance or safety concerns. DRILL FLEET MANAGEMENT The current DFM was stabilized in its current form in mid 2009 after database and hardware maintenance met stability requirements. Currently the system is running on 12 production drills. The system receives pattern layout and is capable of semi-autonomous drilling over the entire district. The fleet is capable of drilling in highly altered intrusive units and hard granites through the range of sedimentary and volcanic units that comprise the Morenci District. The system brings a level of accuracy not achievable with earlier paint-marked patterns. Depth control is also increased along with more consistent wear and maintenance patterns due to semi-autonomous drilling.

Jan 1, 2011

By H. Burger

For mine planning in the hardcoal industry the reliable prediciton of the properties of a deposit-both ahead of the zone to be worked as well as of zones at depths not yet developed - may help improve the production results of workings. With the wide spacing of exploration drillings usual in the coal industry, it is hardly possible to establish adequately reliable plans just by simple kriging methods. During the exploration phase a decision has to be made whether the zone ahead of a face area is economically profitable and, in addition, accessible and safe in order to be included in the production planning. It is, first of all, important to gather global information on certain parts of the planning area it the form of local estimates. Moreover, cut-off problems play a critical role, e.g. if there are set cut-off thicknesses as a criterion for minability or if safety aspects have to be considered. Conditional simulation appears to be a useful geostatistic method in order to localize or predict areas of potential rock burst hazard - based on geological criteria in conjunction with the guidelines by mining authorities - in the zones ahead of a working. It is a means of providing an objective basis for the evaluation and planning of mining activities.

Jan 1, 1986