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By J. Schleifer

On short term, planning techniques require more details to ensure feasibility, giving importance to operation constraints and use of available resources. In GUEMASSA (Morocco), the ore mass is mined by cut-and- fill method. Correct organization requires to forecast a few weeks ahead the schedule of blocks to be mined, in order to respect ore quantity and grade constraints. While operating constraints are tackled, feasibility is assumed with an average production capacity suggesting that resources will be available. In ST-SALVY (France), scheduling operations is not possible if not considering account resource allocation. In any stope within the vertical vein zinc deposit, the cut-and-fill method enables to mine each horizontal slice according to various strategies, de- pending how to use manpower and equipment, and selecting among predefined scenarios known as realistic. For KOFFIEFONTEIN (South Africa), the kimberlite pipe is mined by a sub-level-stoping method. To achieve the production target, precise organization over one month is obtained, using on& resources when available and respecting all mining rules. This combined operation scheduling and resource allocation is called sequencing. While following the BONANZA concept, providing a planning- retrieval process, sequencing offers more. Very detailed, it is possible to check the impact of resource parameters and mining rules. The sequencer, like a simulation platform, enables expertise. Each sequencer must be tailor-made to fit to each specific mine. The next challenge is to produce a generic environment.

Jan 1, 1996

By R. Hogg, R. C. Klimpel, D. T. Ray

The sedimentation and dewatering characteristics of flocculated slurries are determined by the size and density of the flocs. Studies of the formation and growth of flocs reveal that floc size is limited by breakage of the agglomerates due to shear in the suspension. Floc density measurements indicate that there is an inverse relationship between size and density. This relationship appears to be determined primarily by the nature of the solid particles, especially the size distribution, but it appears that agitation of the suspension can lead to some densification of the flocs, in addition to breakage. It follows that both size and density can be controlled to a significant extent by regulating the physical conditions (agitation, method of flocculant addition, etc.) during flocculation. The use of physical floc conditioning to control the sedimentation and dewatering (filtration) behavior of flocculated, fine-particle suspensions is evaluated in terms of its effects on floc size and density.

Jan 1, 1988

By P. Coleman, J. C. Kerkering, S. Iverson

Fault tree analysis is a systematic safety analysis tool that proceeds deductively from the occurrence of an undesired event (accident) to the identification of the root causes of that event. One recurring mine safety problem-a dozer falling into a void over a drawpoint on a coal surge pile-was analyzed using available, inexpensive fault tree programs on a personal computer. The analysis identified basic and intermediate events that led to the burial of the dozer and graphically depicted the interrelationship between these various subordinate events as well as the various chain of events leading up to the primary event. A sensitivity analysis on these probabilities showed which events had the greatest influence on dozer burial in a coal surge pile.

Jan 1, 2001

By F. N. Kissell, C. D. Litton

This study ranks the factors impacting survival during a coal mine fire. It has already been established that reducing time delays is the most important factor in saving lives. Consequently, every event during afire is measured in terms of its duration, and the effectiveness of any action taken to improve survival is measured in terms of the time it saves. By ranking actions according to time saved, these authors found that a combination of actions was most effective. This combination was: •installing lifelines, •moderately decreasing air leakage and •decreasing the fire growth rate. Changing ventilation leakage alone was much less effective, as was altering the CO (carbon monoxide), sensor alarm threshold. These results confirm an earlier fault-tree study on escape from mine fires. The fault-tree study had shown that, with the exception of delays, single-factor changes have minimal impact. Significant reductions in fire fatalities only take place with multiple factor changes.

Jan 1, 1994

By O. J. R. Baena

Mining activity in the Segovia region in NE Colombia is the main source of employment in the local economy. This has created major problems of illegality and informality mining associated with a high social and environmental impact, as inefficient technologies are used and high consumption of toxic substances required in the process of gold recovery by amalgamation and cyanidation. In this work is presented mineralogical characterization of six local mills and studied beneficiation processes developed in them. With the results presented a proposed plant design that eliminates the use of mercury by replacing gravity concentration processes taking advantage of the characteristics of the treated material. Significant results were obtained regarding the recovery of precious metals and present a methodology that can be replicated in other mineral beneficiation plants that use gold amalgamation processes. This implies a significant reduction in mercury use and decreased risk of human contamination associated with this.

Feb 23, 2014

By G. A. Rowell, T. M. Barczak, J. C. Zelanko

The US Bureau of Mines conducted a multifaceted geomechanics research project at a bump-prone longwall coal mine in eastern Kentucky. This mine presented a unique opportunity to study coal mine bumps because the problem appeared to be confined to areas beneath a sandstone channel of limited areal extent. The Bureau's research plan sought to exploit the uniqueness of the site by monitoring strata behavior and longwall support reactions as the longwall face approached and passed beneath a sandstone channel. The study incorporated static pillar stress and strata deformation measurements, shield support leg pressure measurements and microseismic monitoring, as well as geologic mapping and the collection of observational data. Data collection was underway when a major coal bump occurred on the longwall face at the mine. Pillar behavior (load and deformation), shield loading and microseismic activity were monitored prior to, during and after the bump. Observations in the tailgate indicated that these pillars were failing prior to and following the face bump. Shield load data, evaluated in an effort to identify trends that could be used to forecast coal bumps, appear to provide a measure of the effectiveness of destressing operations conducted on the face (e.g. shot firing). Analyses of microseismic data revealed anomalous values associated with microseismic "energy" prior to the face bump. In addition, microseismic source-location data and underground observations provided some insight as to the sequence of pillar and face bumps.

Jan 1, 1992

By Bruce A. Brown

Construction aggregate is the most important nonmetallic-mineral commodity in quantity and value that is produced in Wisconsin. Crushed stone is produced from the Precambrian crystalline rocks and the Ordovician and Silurian carbonates, and sand and gravel is extracted from Quaternary glacial deposits. Dimension stone is quarried from both the Precambrian crystalline rocks and Paleozoic carbonate rocks. Other nonmetallic minerals include industrial sand, lime, roofing granules, terrazzo aggregate, and peat.

Jan 1, 1999

By J. Kretschmann, K. Sakamornsnguan

"Sustainable development is an influential ethical concept in modern mining management. However, the concept is not culturally neutral because it is based on Christian, Western values. These values can be very different from traditional values in emerging mining countries like Thailand, where Buddhist values are dominant. When applying the concept of sustainable development, these differences should be taken into account. Different values imply different interpretations of ‘good mining’. They have a significant impact on how mining operations are evaluated, perceived, operated and managed. This paper attempts to integrate Buddhist principles with approaches of the sustainable development concept. When local values are appreciated and maintained, mining companies and their external stakeholders can identify objectives and approaches that match with their own values and contexts. Practices based on this integrated ethic can help to promote sustainable mining and to minimize communication risks for enterprises in mining countries like Thailand. INTRODUCTION The objective of this paper is to integrate Buddhist principles to the application of sustainable development concept to mining activities. The structure of this paper is divided into four parts. An introduction provides basic information about Thailand, its mining industry and the role of Buddhism on the past development. The second part compares the differences between the sustainable mining framework and the implications of Buddhist principles on mining. In the third part, the core Buddhist teachings are integrated into the sustainable mining framework. This is followed by conclusions in the last part. THAILAND, BUDDHISM, AND MINING Thailand is a constitutional monarchy state in Southeastern Asia with a population size of around 65 million [1]. Its GDP in 2013 was 391 billion USD [2], predominantly deriving from manufacturing (38%), trade, transport and communication (24%), agriculture (8%) and mining and construction (4%). Still the largest part of the Thai workforce (39%) is working in the agricultural sector. The remaining part of the workforce is equally distributed across services, manufacturing, and mining and construction sectors. [3]"

Jan 1, 2015

By L. Zhou, D. Bahrami

Mine ventilation is one of the most important aspects of mining operations in underground mines. It is critical to maintain and deliver required fresh air to the active areas to reduce the risk of overexposure to hazardous contaminants or explosive atmospheres. An unexpected or unknown event such as roof collapse, unexpected mine door closure/opening, a fire/explosion, or fan malfunction could adversely alter the airflow distribution within the mine ventilation network that could lead to a hazardous underground environment. Knowing the occurrence and location of such an incident is of critical importance. In this study, the authors developed a novel methodology to assist mine operators in quickly identifying the location of any abnormal airflow change within the network using the airflow changes at monitored airways. The concept is based on a direct derivative method developed by the authors. This paper provides the details of the developed method as well as numerical verification examples. The application of this method can benefit mine operators and safety personnel in making better decisions during a mine emergency response operation to mitigate hazardous conditions arising from an unexpected airflow disturbance

Mar 2, 2022

By R. Perlo

"INTRODUCTION Peoples’ and operators’ safety in construction are tightly linked to the engineering choices, as much as the necessity of reducing time and costs of realization. Therefore, it is of paramount importance to address them properly from the earliest stage of the design, identifying the risks connected to the work and the variability of such during the different phases of the project. Risk is often measured as the expected value of an undesirable outcome. Regarding to occupational safety and health, the risk is the likelihood that a person may be harmed of suffers adverse health effects if exposed to a hazard. This combines the probabilities of various possible events and the assessment of the corresponding harm into a single value. However, the actual occurrences are often more complex than a single binary possibility case. In a real case scenario, with several possible accidents, the total risk is the sum of the risks for each different accident, provided that the outcomes are comparable. The semi-automatic tunnel support system along with its erector machine proved to be a solution with improved structural performance, able to reduce the time and yet to deliver an enhanced, quality-aware and safer working environment for the operators. The implementation of the system provides the engineers, the contractors and the owners with an effective alternative option shortlisted in 2015 for the ITA Award for the Safety Innovation of the Year. In a market industry driven by safety and time constrains the efficiency shall be the ultimate goal, in order to provide solutions able to negotiate with the most challenging ground conditions. In this paper, the authors describe the recent developments on regard of this whole new tunnel support system, including design approach and presenting related case histories OFFSETTING THE RISKS Considering the above factors, from the manufacturers’ point of view, an effective way to limit the construction risks is to focus on the material and technological characteristics, their application and the risks related to them including any residual risks. Finally addressing the construction needs also involves time and cost-effective solutions. The path to follow is an integrated approach where the efficient management of the risk is supported by a flexible, user-friendly, and time effective product that is able to provide a safe, reliable and viable solution to address the construction requirements. Therefore, in a market sector driven by safety and time constraints, the efficiency is a key goal, in order to avoid redundancy and yet to deliver a safe working environment able to meet the construction schedule. The safety of all the parties involved is given by stable working conditions, either for the workers, or the operators and eventually the public. Therefore, the solutions provided should ‘strengthen’ the overall condition and such “to limit or to reduce the deformations within acceptable designed limits and to prevent [the tunnel] to collapse” [1: Clause 207.1.4]."

Jan 1, 2018

By J. W. Leonard

Gravity based coal/mineral preparation plants must be operated to yield products of a quality satisfactory to existing markets; but, because of historic control problems, recovery is frequently sacrificed to achieve quality resulting in losses of valuable product. Plant control has ranged from intuitive in-plant spot quality judgments made by various operators to gross methods involving such devices as density gauges, floats, grab-sample on-the-spot sink-float tests, etc. Millions of tons of quality coal/minerals are lost to refuse each year, because of the historic lack of a continuous and dependable control system. The result is both serious economic as well as environmental losses. While the economic losses are obvious, less obvious environmental losses, in the case of coal, result from the misplacement of more ignitable quality fuel to refuse banks. A control system capable of supplying a market-grade coal/mineral product, while continuously minimizing product losses to refuse, has until recently escaped technology.

Jan 1, 1991

By Q. Lin, D. Z. Wang

Molecular design plays an important role in development of new flotation reagents. Group electronegativity calculation is a main method of molecular design. It is commonly used in calculating the hydrophilic-hydrophobic balance of reagents, particularly in designing chain length of flotation reagents for located minerals. But there is a limit to group electronegativity method. The method can only apply to those of [Ø]known straight-chain compounds ([Ø] is the hydrophobic energy of each -CH2- , determined by experiment). In this Paper, we propose another new calculation method: fragment method of flotation reagent. The method could be used as a supplement of group electronegativity method to design and calculate flotation reagents without any limitation. With the fragment method, we can calculate the hydrophilic-hydrophobic performance of any known or unknown reagents including those complicate structure compounds such as cyclic, branch, heterocyclic and so on by summing the appropriate structural elements (fragment). The principle, calculation stages and some results of designing new-type flotation reagents by fragment method are presented in this paper.

Jan 1, 1995

By Ken A. Phillips

Like the Arizona jeans commercial says: Arizona's not just a state, its a state of mines. Nearly 300 mines operate in Arizona making it the largest nonfuel mining state in the nation. Although copper is king in Arizona's mineral complex, nonmetallic minerals play important roles both regionally and nationally. Throughout Arizona's mineral resource development history industrial minerals have dominated over the metals for most, but not recent years. The State's metal mining industry which makes Arizona the number one mining state in the United States is a relatively young phenomenon. Arizona was an important industrial mineral producer long before her metal mining industry got started. Salt, phosphates, silicates, and oxides as food additives, tanning chemicals, gemstones, components of aboriginal ordnance, pigments, and construction materials are among the minerals produced long before copper, gold, silver, and the other metals became important. Around 92 % of Arizona's mineral industry is made up of nonfuel minerals, 86 % of that is accounted for by copper. Another 4 % is taken up by copper byproducts of molybdenum, silver, and gold. The remaining 10% of the production is occupied by non-fuel, non-metallic minerals. Arizona's 1994 industrial mineral production of nearly $380 million ranks us among the top 25 in the nation and higher than the total mineral production of at least 15 states.

Jan 1, 1996

By Mark S. Stagg, Michael J. Nutting, Douglas R. Barlet

Single-row bench blasts at a reduced scale in the field were used to study the effects of delay time on fragmentation. Nine shots with a spacing of 21 in. and a burden of 15 in. (S/B = 1.4) and nine shots with a spacing of 30 in. and a burden of 15 in. (S/B = 2.0) were completely screened to determine particle size distributions. Delay intervals between holes ranged from 0 to 45 msec, corresponding to effective delay intervals ranging from 0 to 36 msec per foot of burden. Each shot was instrumented with strain and pressure gages to measure in situ blast dynamics and to evaluate interactions between blastholes. Finer overall fragmentation was produced for shots with delay intervals between 1 and 17 msec per foot of burden. Only for shots within this optimum delay range was it observed that the strains induced by stress waves constructively interacted with strains induced by gas pres- sure from an earlier detonated hole. Coarsest fragmentation resulted at delay intervals less than 1 msec/ft, where stress waves from each hole were observed to interact destructively, and at delay intervals greater than 24 msec/ft, where no inter- action between holes was observed, indicating a condition that can be considered as the firing of single hole shots independently.

Jan 1, 1986

By R. W. Barbaro, J. M. Mutrnansky

This paper presents a nonlinear integer goal programming model that optimizes a mineral production schedule while considering the penalties and bonuses based on quality variations in the final product. It involves five coal quality goals plus a profit objective in its formulation and uses the weighting method of goal programming for a solution. The goals to be sought involve the sulfur, ash, heat content, moisture content, and ash softening temperature of the blended coal product. The model is linear in its handling of most of these goals but uses a piecewise linear integer formulation for the sulfur and heat content bonus and penalty schedule. The model is applicable to any mineral product blended from several different sources and subject to a varying price dependent on blended product quality or qualities. However, it seems to be most pertinent to optimizing production schedules for coal deliveries to power plants. Accordingly, the model is applied to a hypothetical coal production problem where multiple coal mines are operated to supply a final blended product to a power plant. In this example, the price paid for the coal is assumed to be a function of five of the most important coal qualities. The problem is solved as a direct function of the coal supply contract, thus removing the necessity of determining the weighting coefficients on a subjective basis.

Jan 1, 1987

By E. B. Kroeger, Y. P. Chugh

The goal of this project is to develop, demonstrate, and document the beneficial use applications of a ponded F-fly ash as a road subbase material for the 2.1-mile Meredosia Industry Access Truck Route in Meredosia, Illinois. Approximately 60,000 to 70,000 cubic yards of ponded fly ash are proposed for use on this project without negative environmental impacts to surface water or groundwater. The County Highway Truck Route will consist of a 24-foot wide road built on a 0 to 7-foot thick compacted F-fly ash subbase. Laboratory testing indicates this fly ash will serve adequately as a road subbase, conforming to IDOT standard specifications. The economic considerations of using the Meredosia F-fly ash will also be developed so that a detailed cost-benefit analysis can be prepared for this project and for future projects. This project represents a two-year cooperative development and demonstration effort among the Office of Coal Development and Marketing (OCDM) of the Illinois Department of Commerce and Community Affairs (IDCCA), Southern Illinois University (SIU), Morgan County Highway Department (MCHD), Illinois Department of Transportation (IDOT), AmerenCIPS, and the Morgan County Regional Planning Commission. It is anticipated that monitoring activities will continue for a period of three (3) years after the completion of this project. The MCHD and IDOT will oversee all construction activities and long-term performance evaluation studies. Successful demonstration of large-volume beneficial use applications of F-fly ash at this site will significantly reduce management costs for power plants burning Illinois Coal. Furthermore, it will encourage similar utilization strategies at other sites in the State of Illinois.

Jan 1, 2002

By L. J. Laughlin

The majority of non-drive conveyor pulleys use rotating shafts, and typical idler rolls use non-rotating shafts, even though both products are used to support and guide the conveyor belt and its load. This paper will explore and compare the requirements for rotating and non-rotating shaft designs and the impact of that design on the product. Additionally, it will explore how the “roller” bearing types (deep groove ball, tapered, or spherical) affect these designs.

Jan 1, 2003

By Larry J. Hughes

Ground-based electrical geophysical techniques have be valuable for three indirect exploration strategies: "tracer" sulfide mineralization, 2) mapping structure with or controlling mineralization, and 3) mapping proven to 1) mapping? associated alteration zones. When sulfide mineralization is associated with gold, it often can be mapped using induced polarization (IP). This technique can detect pyrite in amounts as small as 0.2% by volume, and in some cases can distinguish pyrite from anomalies due to graphite and clays. A case history illustrates mapping sulfides in a shear zone. Structure and alteration mapping are often the domain of controlled source audio-frequency magnetotellurics (CSAMT) due to the superior lateral resolution and depth penetration of this technique. Typical CSAMT targets include silicified sediments and volcanics, faults, brecciated zones, argillic alteration, clay and graphite horizons, and certain lithologies. Examples of mapping silicification and mapping epithermal alteration are presented in CSAMT case histories over Cannon mine in Washington and Hishikari mine in southern Japan. In our experience, four things are needed to use geophysics effectively in precious metals exploration. First, the explorationist must correctly identify the exploration stage at which the geophysics is most useful. Second, the explorationist must clearly define the types of "tracer" mineralization, host geology, or alteration which need to be defined by the geophysics. Third, the right electrical technique needs to be applied to the problem to provide the best chance of success. Fourth, the explorationist must be willing to commit adequate finances to do the geophysics properly. With careful adherence to these principles, geophysics can greatly enhance exploration success while reducing the total cost of exploration.

Jan 1, 1989

By J. W. Markham, M. Atiemo, K. Yoshida

INTRODUCTION In open-pit mining of high grade ores, operators of mining equipment in a pressurized cab are protected from inhaling radioactive aerosols by the use of filtered air through a pre-impactor and a HEPA (high efficiency particulate air) filter. At present, a limited amount of scientific information is available on the worker exposure to airborne alpha emitters in the mining of high-grade ores. (Miller, 1977, Nielson, et al, 1979). Factors affecting the worker exposure to alpha radiation are: the grade of uranium containing ores, the environmental conditions inside the mine pit, the protection factor of the cab filter system, the workers' attitude towards the hazards of radioactivity and the adopted contamination control in the cabs. Four series of field samplings were conducted during the fall of 1980 and the summer of 1981 at a mining site in northern Saskatchewan to investigate the extent of protection an equipment operator has against cab internal exposure to airborne alpha emitters with short and long half-life radionuclides. The variation in the breathing zone concentrationnof aerosols as a result of resuspension is discussed, however no attempt was made to isolate and investigate the factors and the associated parameters of the aerosol resuspension phenomenon. AEROSOL RESUSPENSION IN A CAB Mechanisms of Resuspension [Sources]: The presence of radioactive aerosols inside a cab and in the breathing zone of an operator may be due to initial concentration inside [(CO)], concentration in the filtered (HEPA) air (CC, at the flow rate [QC]), the concentration of the aerosol through resuspension ([CR]), the aerosol concentration in the air outside the cab ([CE]) and the concentration of the aerosol in the leaking air [(CL)], at the flow rate of [(QL)]. [Volumetric Equilibrium]: Assuming a uniform concentration of the aerosol in the cab, the aerosol concentration in the breathing zone[ (CBZ)] may be expressed as, [CBZ+CO+CC+CR-CL] If [QC] remains greater than [QL], there is pressurization in the cab. There is particle loss as a result of the leaking air from the tight cab, however the condition of adequate pressurization ensures that [CL ~ CC]. Also for dust particles filtered through HEPA [CC – 0] thus [CBZ + CO + CR] For the radioactive gases, [CBZ - CO + CC] Over long periods,[ CBZ – CE] but if [CBZ] exceeds the value of CE then the aerosol build-up in the cab has, occurred. [Resuspension]: Turbulent bursts are generated within the core region of a cab confinement, such that the down sweeps and the up sweeps of the air bursts cause resuspension of dust from the surfaces. Particles initiate resuspension by four major modes: namely, sliding, rocking, rolling, bouncing or sudden ejection or by combinations of these. Nevertheless the adhesion force between the particles and the surface must be overcome by ejection forces before ejection takes place (Kline et al, 1967, Corino and Bradkey 1969, Kim et al 1971). The phenomenon of particle resuspension from a surface may be expressed in a generalized form as: CR =f (Uz . R . D . H) where CR = Rate of particle resuspension UZ = Surface shear velocity R = Surface roughness parameter D = Aerodynamic diameter of particle H = Frequency of surface airburst A detailed discussion of the individual parameters was attempted for the case of farm tractor cabs by Atiemo (1981), such a treatment is out of the scope of this study. Only the effects of the properties of surface roughness will be discussed. Effect of Surface Properties The roughness of the surface from which dust particles are ejected plays a significant role in the deposition and resuspension of the dust. The roughness or the amount of protrusions greatly influence the intensity of air turbulence in the immediate vicinity of the surface (Schmel 1976). For most roughened surfaces therefore, larger particles may be dislodged in greater quantities than smaller particles. The deposition and the resuspension of dust particles from different surface materials of glass, cloth, metal and rubber have been studied in a wind tunnel (Atiemo, 1981). Field Conditions Mining equipments used are: a backhoe, a bulldozer with ripper attachment and two dumptrucks for high-grade ore operations; a payloader and two dumptrucks for waste handling; and a jumbo drill which drills dynamite holes for ore blasting. All this

Jan 1, 1981

By W. A. Niepelt, F. A. Locher

Flow in steep cascades may lead to the occurrence of a nearly periodic train of waves known as slug flow. This, in turn, may result in overtopping of the channel walls and problems with energy dissipation in receiving sumps. Experimental data from an operating facility was used to extend clear water technology for predicting the occurrence of slug flow to conditions with slurry flows. A design methodology and a design chart to determine the region of steady flows is presented that will permit the design engineer to avoid slug flow in cascade systems for conveyance of slurries.

Jan 1, 1990