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By Jr. Kirschner

An abandoned waste impoundment located within a portion of the Kellogg, Idaho Superfund site constitutes a field research area for studying the feasibility of recovering heavy metals in-situ from unsaturated mine and mill wastes. A prototype in-situ leaching cell has been evaluated using liquid-phase tracer tests and other hydro-geologic tests prior to introducing a lixiviant. The results of the tests suggest that: (1) the cell can be operated excursion-free with a low-density lixiviant at an injection/withdrawal rate of approximately 0.32 l/s; and (2) each hydro-geologic unit is highly heterogeneous at the different scales studied.

Jan 1, 1993

By Shadia J. Ikhmayies

The SnO2/CdS/CdTe thin film solar cells were fabricated on glass substrates by using the spray pyrolysis (SP) technique for the deposition of the SnO2 and CdS layers and vacuum evaporation for the CdTe layer. The transmittance curves were used to investigate the interdiffusion in the two interfacial regions SnO2/CdS and CdS/CdTe by taking the first derivative of the absorbance as a function of wavelength. The appearance of new bandgaps around the bandgaps of SnO2:F, CdS:In and CdTe layers is a strong evidence on the interdiffusion in the two interfacial regions and/or the formation of quantum dots.

Jan 1, 2010

By Claudia Ríos Figueroa, Gonzalo Montes-Atenas

"Among the many variables mentioned in the literature that may influence the froth flotation performance, particle size is perhaps one of the most renowned. Empirical knowledge has indicated that recovery of fine particles will inevitably drop below certain particle size threshold. Several processing alternatives have been suggested to improve the recovery of fine particles. Some of these initiatives have been reached the status of patents and other intellectual property related documents; however, there is still a disconnection between the scientific knowledge available and the industrial operations practicalities implemented to address this matter. In fact, in general terms, none of these ideas or processes concepts have become a final solution to this problem. At first glance, economical reasons may be argued as the main cause hindering the development of these and other ideas, but it would be an oversimplification as technical issues behind them are still themes to be discussed and sorted out. This study aims to review technical aspects behind scientific ideas and processes concepts suggested to solve the problem of low beneficiation of fine particles in froth flotation. The analysis was performed using the theory of inventive problem solving (TRIZ) which allows identifying technical gaps these initiatives have not considered or overlooked. Statistically the scientific databases indicates that reports on fine particles froth flotation only represented less than 50% of all reports involving fine particles processing. Most of the solutions derived from classic contradictions derived from bubbles and particles hydrodynamics only (reducing the bubble size or increasing the turbulence would increase the rate of bubble-particle aggregates formation but may reduce the recovery). This contradiction encompasses a small range of contradictions possible to be accounted and to be resolved. The method is expected to provide insights towards designing definitive solutions for the industry in this field."

Jan 1, 2014

By J. Chilton

The fact that methane ignitions continue to occur at the mining face indicates that monitoring with machine-mounted methanometers does not always indicate the presence of high methane concentrations. Methane concentrations at the face change quickly due to changes in airflow. By measuring these changes in airflow, it may be possible to predict changes in face methane levels more quickly. Currently there are no techniques or instruments to accurately measure airflow in by the mouth of the ventilation curtain or tubing. Tests conducted in the NIOSH ventilation test gallery compare the data provided by one-, two-, and three-axis ultrasonic anemometers. The effects of changes in airflow direction and turbulence on instrument readings are discussed, and guidelines are given for selecting the type of instruments to be used for monitoring airflow near the mining face.

By J. Chilton

The fact that methane ignitions continue to occur at the mining face indicates that monitoring with machine-mounted methanometers does not always indicate the presence of high methane concentrations. Methane concentrations at the face change quickly due to changes in airflow. By measuring these changes in airflow, it may be possible to predict changes in face methane levels more quickly. Currently there are no techniques or instruments to accurately measure airflow inby the mouth of the ventilation curtain or tubing. Tests conducted in the NIOSH ventilation test gallery compare the data provided by one-, two-, and three-axis ultrasonic anemometers. The effects of changes in airflow direction and turbulence on instrument readings are discussed, and guidelines are given for selecting the type of instruments to be used for monitoring airflow near the mining face.

Jan 1, 2007

By T. Mal

A test system was developed at the National Institute for Occupational Safety and Health's ventilation test gallery for measuring airflow using a three-axis ultrasonic anemometer. The gallery war used to simulate face airflow conditions in underground mines having a blowing curtain. Airflow data, collected at multiple sampling locations between the face and the end of the curtain, were used to draw airflow profiles for different curtain setback distances, intake flow quantities and entry widths. In addition, methane was released at the face, measured at the sampling locations and displayed as methane distributions in the area between the curtain and the face. Entry geometry had a significant effect on airflow patterns, and the flow patterns affected the distribution of methane in the entry. Flow measured at and parallel to the face was a good predictor of methane dilution and removal within 0.6 m (2ft) of the face.

By Robert J. Timko, Charles D. Taylor, Edward D. Thimons, Tom Mal

A test system was developed for measuring airflow in the National Institute for Occupational Safety and Health (NIOSH) ventilation gallery using a three-axis ultrasonic anemometer. The gallery was used to simulate face airflow conditions in underground mines having a blowing curtain. Airflow data collected at multiple sampling locations between the face and the end of the curtain were used to draw airflow profiles for different curtain setback distances, intake flow quantities and entry widths. In addition, methane was released at the face, measured at the sampling locations, and displayed as methane distribution in the area between the curtain and the face. Entry geometry had a significant effect on airflow patterns, and the flow patterns affected the distribution of methane in the entry. Flow measured at and parallel to the face was a good predictor of methane dilution and removal within two feet of the face.

Jan 1, 2005

By Robert J. Timko, Charles D. Taylor, Edward D. Thimons, Tom Mal

A test system was developed for measuring airflow in the National Institute for Occupational Safety and Health (NIOSH) ventilation gallery using a three-axis ultrasonic anemometer. The gallery was used to simulate face airflow conditions in underground mines having a blowing curtain. Airflow data collected at multiple sampling locations between the face and the end of the curtain were used to draw airflow profiles for different curtain setback distances, intake flow quantities and entry widths. In addition, methane was released at the face, measured at the sampling locations, and displayed as methane distribution in the area between the curtain and the face. Entry geometry had a significant effect on airflow patterns, and the flow patterns affected the distribution of methane in the entry. Flow measured at and parallel to the face was a good predictor of methane dilution and removal within two feet of the face.

By A B. Jr Nunn, W C. Gould

Good community relations is a major concern at this central Virginia aggregate quarry. In this paper, the authors describe the use of a new electric millisecond delay initiation system that has reduced the average level of vibration by 27% since its use began in late 1984.

Jan 1, 1986

By Bo Hyun Kim, Mark K. Larson

Researchers at the National Institute for Occupational Safety and Health have tested the finite element code, UT3PC, with LaModel to evaluate their results using know case studies. The purpose of the testing was to demonstrate the usefulness and limitations of these programs in evaluating mine layout design. Both of these software packages are simple to use and free for public download. Their use by mine engineers, along with other tools, such as empirical methods, can enhance the assessment of a mine layout design. LaModel can model mining layout on a mine scale or, at least, on a multiple-panel scale. However, this software has limitations in calibrating to conditions at many coal mines in the western United States. The UT3PC software models smaller parts of a mine and is used to evaluate the design of pillars, shafts, or drifts; but the software calculates all components of the stress tensor and provides stresses, displacements, and safety factors throughout the model volume. The two codes are used to evaluate design of one known case, and UT3PC is used to evaluate another case. The results and approaches demonstrated in the testing are intended to aid mine engineers in evaluating site-specific problems and to show that these tools can provide useful information to the mine engineer in evaluating mine layout design.

Jul 1, 2023

By W Stange

Assessing the risks in a mining project is a key aspect of project evaluation. This is an exacting and demanding task because of the complexity due to the need to deal with uncertainty over long time periods. The way risks are assessed and managed is critical to the long-term success of the projects and the business. Discounted cash flow (DCF) analysis is commonly used for project and risk evaluation. A discount rate is selected that accounts for uncertainties in the cash flows. However, it is difficult to determine an appropriate discount rate due to the large number of factors that need to be considered and the complex relationships between risk sources. Using a proven framework, ævalue at riskÆ (VaR), this paper proposes to rigorously model and quantify ærisk at sourceÆ. The approach was first employed to assess financial market risks and is now widely used in the banking sector for risk assessment. In project evaluation, all risk sources are identified and estimated separately to ensure the overall project risk is quantified accurately. A bottom-up approach has been proposed. Estimates are first carried out for risk factors at the bottom of the project structure. The assessment is then applied at increasingly higher levels until the overall project risk is estimated. Value at risk is a versatile methodology and can be used in a local or integrated manner. The final value is objective and the calculation steps can be easily justified and followed. Four case studies have been included to illustrate how the proposed approach can assist management in decision-making.

Jan 1, 2009

By A. B. Cecala

It has long been known that ventilation is a cost-effective method to lower respirable dust concentrations in all types of mining applications. The National Institute for Occupational Safety and Health has been working on a number of different research techniques that use ventilation as a critical component to lower respirable dust levels at surface and metal/nonmetal operations in the United States. This article presents five such research efforts. The first research area discusses how improving the ventilation flow patterns in an iron ore mill facility lowered respirable dust concentrations by 31 pct throughout the primary grinding area. The second research area examines how respirable dust levels were lowered at a dimensional stone shop by using air cleaning units suspended from the ceiling. A third area discusses how improvements in ventilation at underground limestone mines lowered respirable dust concentrations. The fourth area examines how improvements in dust filtration and pressurization systems significantly impacted the air quality in enclosed cabs of surface mining equipment. The last area presents a newly developed clothes cleaning technique. This technique uses an air spray manifold to blow dust from a worker?s clothing in an enclosed booth, which confines the dust for capture and removal by a baghouse dust collector. These research areas represent an array of different control technologies to lower respirable dust concentrations. Ventilation is an integral part of these control technologies.

Jan 1, 2006

By J F. Colinet, G, J A. Zimmer, R J. Timko

It has long been known that ventilation is a cost-effective method to lower respirable dust concentrations in all types of mining applications. The National Institute for Occupational Safety and Health has been working on a number of different research techniques that use ventilation as a critical component to lower respirable dust levels at surface and metal/non-metal operations in the United States. This article presents five such research efforts. The first research area discusses how improving the ventilation flow patterns in an iron ore mill facility lowered respirable dust concentrations by 31 per cent throughout the primary grinding area. The second research area examines how respirable dust levels were lowered at a dimensional stone shop by using air cleaning units suspended from the ceiling. A third area discusses how improvements in ventilation at underground limestone mines lowered respirable dust concentrations. The fourth area examines how improvements in dust filtration and pressurisation systems significantly impacted the air quality in enclosed cabs of surface mining equipment. The last area presents a newly developed clothes cleaning technique. This technique uses an air spray manifold to blow dust from a workerÆs clothing in an enclosed booth, which confines the dust for capture and removal by a baghouse dust collector. These research areas represent an array of different control technologies to lower respirable dust concentrations. Ventilation is an integral part of these control technologies.

Jan 1, 2005

By Stephen W. Lambert

One of the primary interests of the United States Department of Energy's Mine Planning Division is to fully develop avenues of technical research which potentially offer positive effects on coal mine productivity. One such area of research involves the removal of methane gas from unmined portions of coalbeds through vertical wells drilled from surface locations. As coalbed methane content is reduced, less gas is available for flow into the mine, and consequently ventilation requirements are decreased and/or coal extraction rates increase. Another attractive aspect of the vertical borehole drainage method is that it presents an opportunity to recover and utilize significant quantities of methane gas, which would otherwise be wasted to the atmosphere. The viability of removing gas from the Mary Lee coalbed using stimulated vertical boreholes was first suggested by Elder and Deul as a result of a United States Bureau of Mines' drilling project conducted from 1971 to 1974 (4). Other United States Bureau of Mines' studies forecasted that degasification would eventually be necessary in the Mary Lee coalbed because most new or expanding mine development would take place at depths exceeding 1 000 feet (305 meters), where the methane problem would be severe (3) (13). In 1975 a large-scaled drilling program was designed in order to supply industry's anticipated need for a degasification technology in the Warrior coal basin, Alabama. The results of this government/industry sponsored effort were to be specifically applicable to the Mary Lee coalbed, the most extensive and economically important deep minable coal present in the area. Major technical objectives of this program are twofold: (1) to measure the effects of various well completion designs, particularly hydraulic stimulation, on mining and (2) to determine the effects of well spacing on gas drainage rates. A cooperative agreement was established with United States Steel Corporation in late 1975 and field work began shortly thereafter in the proximity of a newly developing mine near Oak Grove, Alabama. Government responsibility for this program was transferred from the United States Bureau of Mines to the United States Department of Energy in October 1977. To date, as a result of this program, twenty-one wells have been completed into the Mary Lee coalbed at the Oak Grove site. Seventeen of these wells were drilled on an experimental grid pattern located two miles from the active mine. These grid wells are primarily being used to generate data necessary to determine the effects of well spacing on gas drainage rates and will also provide a large amount of information regarding the long-term effects of degasification on mining. The four remaining wells (designated Ton through TW4) were placed near the mine so that the full effects of completion could be studied within the short time required for underground interception. Results gathered from the first two test wells (TW1 and TW2) have been reported in detail (10) and indicated that several improvements were necessary to increase gas drainage rates. Hydraulic stimulation was one of the most important aspects of well design that required improvement. Nitrogen-charged foam stimulation treatment was used at TW3 and TW4 instead of the gelled-fluid type stimulation used at the first two near-mine test wells.

Jan 1, 1980

By Thomas Leonard, Philip R. Berger, Bryan E. Papillon

Bardon Trimount Inc., a large producer of aggregate, crushed stone, and concrete, was experiencing significant public opposition to its five quarries in the Boston area. It was believed by the authors that this opposition could be significantly lessened if the total number of blasts per week were reduced. Although the blasting company at these quarries, Austin Powder Company, contended that this could easily and safely be accomplished by increasing the size of the blasts, regulations precluded this alternative by limiting the total amount of explosives that could be used per blast.

Jan 1, 1996

By Thomas Leonard, Philip R. Berger, Bryan E. Papillon

Bardon Trimount Inc., a large producer of aggregate, crushed stone, and concrete, was experiencing significant public opposition to its five quarries in the Boston area. It was believed by the authors that this opposition could be significantly lessened if the total number of blasts per week were reduced. Although the blasting company at these quarries, Austin Powder Company, contended that this could easily and safely be accomplished by increasing the size of the blasts, regulations precluded this alternative by limiting the total amount of explosives that could be used per blast.

Jan 1, 1996

By L Soares, W T. Hennies, F Fujimur

Barra Bonita reservoir, located in the Sao Paulo State, Brazil, has been mainly used for local navigation and electricity generation to supply a prosper region in the country. Sand mining activities in that area have an important social and economic meaning for the local community. In this reservoir there are several sand mines that produce around 45 000 m3 of sand a month. These deposits were rich in material used as concrete aggregate in the civil construction. However, nowadays a significant increase in the demand of gravel can be observed, representing a serious productive problem. This material hasnÆt been well accepted by the market and, through the years, it was disposed at open sky in piles as waste deposits. This deposits have caused environmental problems like visual impact, reduction of free spaces outside and inside the mine, source of material to erosion and sedimentation processes in lower areas, flooding as a result of the filling up process in the drainage system, among others. For a lack of an appropriate technological characterisation, this material have been mainly used to pavement internal and external areas in the mine, with lower cost associated. With the purpose of evaluate the usefulness of this material in the conventional concrete, there were conducted several tests in the disposed residue including petrographical, physical, and chemical characterisation. The petrographical analysis and the preliminary results of the study showed that the material reacts with the alkalis that are present in the conventional cement (CP-II-E-32). In order to make the application technical and economically possible a research was developed seeking forms to correct this characteristic by adding special cements with high pozzolana content. The results of the technological, physical and chemical characterisation of the products indicated the technical viability of the use of that material. The study also allowed projecting environmental improvements resulting in the elimination of the waste piles.

Jan 1, 2003

By Robert Carlson, Hugh McMillan

During 1967, the Metropolitan Sanitary District of Greater Chicago adopted a policy of land application as a method of using the solids produced in the wastewater treatment process. Research by the Agronomy Department of the University of Illinois, several demonstrations on farm land, reclamation of acid strip-mine spoils, fertilizing a land fill, and reclamation of an alkaline sand waste pit showed the value of using wastewater solids to reclaim marginal and submarginal lands. To launch the Solids-On-Land Program, 10,000 acres of land in Fulton County, Ill., was purchased, part of it previously strip-mined for coal. The Sanitary District initiated a water monitoring program, constructed holding basins, leveled the land, awarded a liquid fertilizer transportation contract, installed a distribution end application system, and began application and crop production. During 1972, the Sanitary District completed the first year of application and harvested the first corn crop. The corn yielded 60 bu per acre while the previous year in a demonstration field it yielded 56 and 13 bu per acre, respectively, on treated and untreated strip-mined land.

Jan 1, 1976

By Hugh McMillan

To protect the water supply for the Metropolitan Chicago area, the Illinois legislature, in 1889, created the Metropolitan Sanitary District of Greater Chicago. To insure the quality of the water supply, the Sanitary District collected and diverted the wastes of 750,000 people away from Lake Michigan. Today, the Sanitary District collects and treats the wastes from a domestic population of 5 ¼ million people and an industrial waste load equivalent to 4 ¼ million people. The District serves Chicago and 120 other cities and suburbs in an 858 square mile area. An average of 1300 million gallons of wastewater is treated each day, producing as a by- product about 700 dry tons of solids which contains more than $10,000 worth of plant nutrients when equated to the value of commercial fertilizer purchased in the retail market. The Sanitary District considered several alternatives to past methods for disposing of these solids, and chose land application as a technique to utilize the solids produced by the wastewater treatment process in a beneficial manner.

Jan 1, 1973

By Gerrit V. R. Goodman

Supplemental water sprays were placed along the sides of a continuous mining machine to improve suppression and confinement of the dust cloud under the cutting boom to re- duce downwind dust levels. Using a full-scale mock up of a continuous mining machine, preliminary work showed that these side sprays improved suppression of the dust cloud and redistributed this cloud under the cutting head. This led to reductions in dust levels around the machine and in down- wind airways for some positions of the mining machine. This testing also showed that side spray effectiveness was influenced by the distance from the fresh air ventilation device to the cutting surface, termed the ventilation setback distance. These sprays produced larger reductions in machine and re- turn dust levels at smaller setback distances than at larger setback distances. These side sprays then were installed in similar locations on a mining machine at an underground coal mine operation to evaluate their effectiveness for im- proving suppression and capture of dust by the flooded-bed dust scrubber. Although sampling could not be conducted successfully in the return, sampling around the mining ma- chine and at the machine operator showed that dust levels decreased with use of these sprays. Further analysis showed that these sprays were most effective at the smaller setback distances, a result confirmed by full-scale laboratory testing. Keywords Occupational Health, Dust Sampling, Coal Mining. Continuous Mining, Control Technology