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By K. V. Raj, A. T. Weakley, A. L. Miller, D. A. Parks

Diesel particulate matter (DPM) is a common and well-known health hazard in the mining environment. The current approved method for monitoring both the organic and elemental carbon (OC, EC) portions of DPM is a laboratory method with a turnaround time of approximately one week. In order to evaluate exposure levels and take corrective action before overexposures occur, a portable real-time device capable of quantifying both OC and EC is needed. To that end, researchers from the National Institute for Occupational Safety and Health (NIOSH) designed and tested a device based on narrow bandpass optical filters that is capable of targeting infrared absorbance bands associated with DPM. Five optical bandpass filters were chosen based on previous work quantifying DPM using Fourier-transform infrared (FT-IR) spectrometry. The resulting device, referred to as a filtometer, is optimized to exclusively determine DPM and could serve as a cost-effective, field-portable alternative to laboratory-grade FT-IR analysis and instrumentation. The performance of the filtometer was investigated by calibrating FT-IR data from DPM (dependent variable) to the filtometer spectra (predictor variables) using a partial leastsquares (PLS) and ordinary least squares (OLS) approach. The square of the correlation coefficient and root-mean-square error of cross validation m

Mar 2, 2022

By A. D. Pernichele

Four types of slope failures in waste dumps are recognized; debris flow, foundation failure, edge slump and blowout. The first three types, although at times causing considerable damage to property and interfering with mine operations, are not usually dangerous to personnel because of their slow rate of movement. The fourth type, the blowout, is considered to be the most dangerous because of its explosive mode of failure and lack of forewarning. The December failure at Verona dump is presented as an example of a blowout. Data from piezometer holes indicate that the blowout was due to perched leach solutions near the face of the dump. The level of water in this zone is very closely related to the rate of leach water application on the dump. A detailed analysis of core samples indicated that the impounded water was due to a zonal accumulation of Jarosite which is associated with a buried dump surface. Drain holes proved successful in controlling perched leach solutions in the critical zone near the face of the dump. Monitoring of the water level in the perched zone is considered essential in preventing blowouts. The use of drain and piezometer holes has allowed an increase in the rate of water application on the dump while preventing additional failure.

Jan 1, 1971

By C. J. Johnson

As the U.S. coal industry moves into the next century, it is becoming more apparent that the effective application of new technology is the only way it can remain competitive in the energy marketplace. Examples of this emphasis are with us today in such diverse areas as face-ventilation and excavation-equipment applications. The focus of this new technology is directed toward improvements in health and safety, cost control, and productivity. Room-and-pillar mining accounts for approximately 80% of the nation's underground coal production; this percentage is not expected to decrease markedly in the near future. As such, this paper analyzes the impacts of the changing technological climate on future room-and-pillar operations by comparing a base-case section (current) to three scenarios incorporating new or emerging technology. A microcomputer-based comparative analysis will reflect the changes in section production and costs.

Jan 1, 1988

By G. Labonte

The behavior of four different redox sensing electrodes (gold spiral, black platinum, chalcopyrite, and galena) during roughing and cleaning flotation is examined and related to the flotation response. Although it is difficult to provide unequivocal interpretations of the different potentials measured, the results indicate that the solution potential (as sensed by the black platinum electrode) is different from that of the pulp potential (gold spiral) and is only weakly related to the flotation response. On the other hand, the potentials exhibited by the gold spiral and the two mineral electrodes are related to the floatation response. The gold and mineral electrodes exhibit different transcient responses during the addition of flotation modifiers (e.g. NaCN, SO2). These responses appear to be related to the reactivity of the minerals and could indicate the conditioning time required to achieve flotation or depression of selected minerals.

Jan 1, 1989

By Ronald L. Wiegel

Success has been achieved in developing mathematical models of rod mills, ball mills and recently to a limited extent autogenous grinding mills. There is also considerable activity in the development of mathematical models of various mineral concentration opera¬tions, such as flotation, magnetic separation and electrostatic concentration. However, at present there is a technological gap which hinders the integration of both size reduction and mineral concentration models into an overall process simulation model. This gap exists because size reduction models have been aimed at describing the size of the product and have not dealt with the equally important problem of identifying the product composition in each size fraction. Without this information the concentration model is ineffective. This situation is especially critical in the simulation of the magnetite-taconite beneficiation process, where a portion of the ore is rejected from the process following each stage of size reduction. Consideration has therefore been given to the merging of a size reduction model and a mineral liberation model to permit prediction of mineral composition as a function of size. The results of this integration of size reduction and mineral liberation models are discussed from both theoretical and practical viewpoints using batch grinding data for a magnetite iron formation sample as a demonstration vehicle.

Jan 1, 1975

By L. M. English

When plotted as head vs. volume, fan curves start high and decrease in head with increasing volume while mine head curves start low and rise with increasing volume. Their intersection is the system operating point But wait a minute: Isn't head loss a negative number, a debit? And isn't fan head an energy addition, a credit? This, as every ventilation instructor knows, is often a stumbling block to student or audience comprehension. It is possible to use the intuitively correct curves -pressure losses as negative values and energy additions as positive values -and still obtain the correct operating point: adding the two curves produces a third curve that intersects the x-axis at the operating point, the point at \\tIich the fan energy input exactly matches air circulation energy loss. Using this technique also makes it easier to account for outside influences on the system, such as natural ventilating pressure; with the standard approach it is quite easy to add or subtract such influences to the wrong curve. This approach can be extended to the graphical solution of any series/parallel circuit or ventilation net\wrk. The results are the same, and the approach is logically consistent and less confusing.

Jan 1, 1997

By James C. Burrows, Frances Kramer Mesher

Tungsten-containing ores are mined on all continents of the world. China is the world's largest producer and controls the world's largest reserves. The USSR, itself a sizeable producer, is estimated to be the world's largest consumer. The major use for tungsten in the noncommunist world is in production of cemented tungsten carbides for cutting, drilling, and wear parts. Other major uses include lamp wires, steels for tools, and armaments. Real tungsten prices have been in a general decline since 1977-1979 as the tungsten market undergoes basic and lasting structural changes.

Jan 1, 1986

By James P. Bowersox

Modem mineral processing plants handle large amounts of ore and produce large tailing streams. Plant performance can be optimized when the water is quickly recovered with a thickener. The caisson thickener was developed to overcome process and mechanical problems with the conventional traction and center column units. The caisson is a hollow center column that serves as a pump house. The rake arm structure is supported by a hydrostatic bearing which sits on top of the caisson. The caisson thickener with a hydrostatic bearing has operated for many years in several mineral processing applications.

Jan 1, 1981

By Richard L. Ash

Less than optimum production in mining always results when poorly blasted material is provided at loading points. More often than not the cause is due to blasting founds that fail to fully control and utilize explosive energy. In many cases the problem exists because too few blasters understand how blastholes actually break rock and recognize that blasting is a three-dimensional process in designing their blasts. To better understand how blasts can be more effectively designed the two major rock breakage processes are described. In addition, the respective contributions of the borehole and detonation pressures are defined as are the specific roles of the several important blasting design variables. The concept of stiffness as an engineering principle and its significance in blasting design is introduced for explaining the breakup of rock. Basic guidelines for affecting control over fragmentation and side effects like over-break are offered.

Jan 1, 1975

By William J. Bryson

Just picture, if you will, the hot, lonely and desolate Ochre Mountains west of Salt Lake City. There works a grizzled old miner, his boots worn down, his clothes hang on a body stooped by years of hard labor. His skin is wrinkled and leather toughened by many years in the hot desert sun. His ever faithful burro stands patiently in the shade of a large rock as the tired old miner examines ore samples just acquired that very morning. Suddenly the old man's eyes widen, his breathing becomes rapid. 'Leaping to his feet, with a gleam in his eye, he cries, "Eureka, I'm rich, I've found the mother lode. This is where I will start my digging. " Without warning, the silent wilderness is alive with wild, shouting, charging figures! Frightened the old miner glances about him wide-eyed and pan- icky. His heart sinks, dismayed he now knows all is lost, this is the end. For there leaping from behind rocks and brush papers in hand, are the men from the Department of Interior, Bureau of Land Management, State Mine Inspectors, OSHA, MESA, EPA, OEO, and the never ending list of regulatory bodies related to todays mining industry.

Jan 1, 1975

'IM existing predictive methods were chosen for evaluation; an influence function (Bals Theory) and a profile function (hyperbolic). These ere applied to several field measured subsidence profiles over United States coal mines. The effect of homogeneous versus non-homogeneous overburden on surface subsidence is demonstrated and the utilization of Bals Theory as a subsidence predictive method for both types of overburden is examined. The major factor affecting subsidence profile characteristics is the migration of the inflection point toward the centerline of the longwall panel. A computer program was written to aid in the analysis.

Jan 1, 1982

By T. Matthews

"One critical factor in mineral reserves reporting, as well as mine-reserves reconciliation, is the impact of dilution and ore loss in the mining process. This paper considers the implications of various factors on dilution and ore loss projections, by orebody geometry, mining method, and ore control systems. We also discuss the implications of resource estimation methodology on dilution for reserves. DEFINITIONS Dilution and ore loss are two critical concepts in mining, which address the differences encountered between modeled grade and tonnages and actual production. Dilution is volume increase and grade reduction caused by multiple factors, chief among which are mining of waste material along ore-waste contacts, mining of internal waste as ore, and misclassification of waste as ore in the ore control process. There are also geostatistical and estimation aspects sometimes lumped with dilution, including the volume-variance effect (the tendency for small volumes of material to include a less regular distribution of grade than large volumes of material). Ore loss is described as reductions of ore volumes in the mining process due to misclassification of ore as waste in the ore control process, exclusion of discontinuous mineralization from mining due to geometry or continuity, and mechanical losses in the mining process. Dilution is typically taken as an increase in tonnes of ore with no change in contained metal (and thus results in a reduction in grade.) (Some workers consider the likely grade of the diluting material as well, particularly in deposits with gradational grade boundaries—this will be addressed later in the text.) Ore loss is typically taken as a reduction in tonnes at average grade of the ore, and thus results in a reduction in both tonnes and contained metal. If model (resource) tonnes are Mt, grade is Mg, and contained metal is Mm, the resource with ore loss (L) and dilution (D) included (Rt, Rg, and Rm) will be:"

Jan 1, 2015

By R. W. Smith, D. L. Taylor, K. A. Altman

The importance of metallurgical information in reaching appropriate decisions during the development of mining projects is demonstrated. A financial analysis is calculated using discrete system simulation. The results are compared to the results of a traditional sensitivity analysis. The traditional analysis is shown to have the potential to overestimate the value of mining projects. The type of statistical distribution used in a random number generator affects the results significantly. The statistical method of analysis provides insight into the amount of metallurgical testing needed and provides verification of how representative the samples are.

Jan 1, 2002

By J. A. Finch

The use of pneumatic methods for measuring interface level in flotation columns is analysed. It is shown that errors can vary over a wide range (e.g. 40 cm. in one industrial application) depending on bubble size, particle size, bubble loading, liquid hold-up and bulk slurry density. Accurate measurements (+ 5 cm) can be obtained by measuring intensive properties of the froth near the interface. Methods based on the measurement of temperature and conductivity are described and analysed. Control of the interface level using these measurements subject to various disturbances is demonstrated.

Jan 1, 1988

By Y. Topkaya, R. E. Johnson, B. R. Palmer, R. B. Bhappu, J. Brent Hiskey, Gürses Öner

Currently there is considerable interest in applying in situ leaching technology to recover copper from oxide ores. In many instances, the distribution of copper mineralization in these deposits is fracture controlled. Laboratory core-leaching experiments have demonstrated that leaching response is sensitive to the dissolution of copper from and the formation of channels along main fractures. Solution short- circuiting can be a major limitation of this technology. This paper describes the application of macromolecular polymers to achieve flow-profile control during leaching. Pre- and post-leached fractures were characterized by computerized tomography (CT) analysis.

Jan 1, 1993

By D. Tao

Coal is a major source of energy in the U.S. and more than 51% of the electricity used in the country is generated from coal. Coal cleaning prior to combustion is necessary and often accomplished using wet physical processes at coal preparation plants to remove impurities such as ash, sulfur, mercury. However, the resultant clean coal product still contains a significant amount of impurity due to the fact that impurities are not well liberated from coal particles ranging from several millimeters to inches in size at which wet cleaning processes take place. A cleaner coal product can be obtained if a cost-effective dry process is developed to further clean pulverized and thus better liberated fine coal at the power plants prior to its combustion. The benefit of such a process is a significant reduction in the cost of expensive post-combustion chemical cleaning processes such as flue gas scrubbing employed to meet the stringent environmental air quality regulations. In this study, a novel rotary triboelectrostatic separator (RTS) was investigated for its application to dry cleaning of fine coal samples acquired from the power plants in the state of Illinois. The pulverized fine coal contains well liberated ash and pyrite minerals and is an ideal feed to the triboelectrostatic separator for further cleaning without the use of water or any chemical reagents. The proprietary rotary triboelectrostatic separator (RTS) is characterized by an innovative high efficiency rotary charger, charger electrification, laminar air flow, and specially designed electrodes. Compared to existing triboelectrostatic separators, the rotary triboelectrostatic separator offers significant advantages in particle charging efficiency, solids throughput, separation efficiency, applicable particle size range, etc. Testing with several fine coal samples has demonstrated that this technology can significantly reduce ash content with a process efficiency similar to or better than froth flotation. Important process parameters such as charger rotation speed, injection and co-flow rate, feed rate were investigated for their effects on separation performance.

Jan 1, 2010

By Pieter Hoekstra, Jim Hild, Mark Blohm

In the Basin and Range Province of Nevada, geophysics is used to assist exploration for bulk minable gold deposits, particularly over pediments. It is employed for mapping thickness of alluvium and Tertiary valley fill, for mapping covered structures, and for identifying alteration zones. In addition to potential field and seismic methods, three different electrical and electromagnetic methods are frequently used, resistivity-induced polarization, controlled source audiomagnetotellurics, and time domain EM. A review and comparison of the principles of these methods, illustrated by case histories, is the topic of this paper.

Jan 1, 1989

By Y. Topkaya, R. E. Johnson, B. R. Palmer, R. B. Bhappu, Ronald J. Roman

The hydrodynamics of the leaching solution in leach heaps is known to be one of the important variables in the performance of the heap. The solution hydrodynamics are also important in the decommissioning of a heap where the aim is to flush out the residual dissolved metals and the remaining reagents. Chemical engineers have studied the hydrodynamics of "trickle bed" reactors for 40 years in an attempt to relate the performance of trickle bed reactors to flow conditions. Their work is reviewed with emphases on areas of similarity to heap leaching.

Jan 1, 1993

By M. Scherbakov, W. Shi

Abrasion is an important mode of performance for any element of an engineered product that involves material contact for example, a conveyor belt cover. Abrasion resistance is considered to be one of the leading factors in belt cover design and improvement. Various types of abrasion testing are reviewed by and compared to actual belt applications. A new quantitative screening torsional abrasion test is developed by Goodyear to mimic a dynamic contact between belt cover and differently shaped stones of various weights dropped onto belt at any angle, velocity and height.

Jan 1, 2004

The purpose of this paper is to describe two systems designed to provide estimations in stratigraphic orebodies for the purposes of detailed mine planning. The first is a completely geostatistical approach and the second is a combined geostatistical/deterministic approach. The essential features of both systems are the estimation of stratigraphic ore boundaries and the subsequent use of those boundaries to provide stratigraphic (or zonal) control for block and point grade estimation (kriging). Both systems are illustrated by application to a section of, the Hilton orebodies, Queensland, Australia.

Jan 1, 1989