Search Documents

By H. H. Fields

The Bureau of Mines conducted research to determine the effectiveness of long holes drilled in solid virgin coal in degasifying an area of the Pittsburgh coalbed showing that horizontal holes drilled into a virgin coalbed from the bottom of any shaft will effectively remove methane gas in commercial quantities from the Pittsburgh coalbed. The in situ pressure at a depth of 214 feet into the coalbed and the average gas and water flows from the five degasification holes were 3 lb/in2 gage and 860,000 ft3/d and 1.7 gal/min, respectively. On June 19, 1975, after 593 days of degasification, a compressor was installed and pipeline quality gas was introduced into a commercial pipeline. As of June 1, 1976, after 1,022 days of degasification, over 753 million cubic feet of gas had been drained and 117 million cubic feet of gas had been purchased by the gas company for use in the local community of Wadestown, W. Va. The gas drained to date is six times the gas estimated to be in the area subtended by the holes. Methane emissions at the working face of 1 West mains, Federal No.2 mine has been reduced by 50 pct, proving the value of methane drainage by horizontal degasification holes drilled from shaft bottoms ahead of mining.

Jan 1, 1976

By K. I. Afewu

A modified approach to the implementation of Gy?s sampling theory is discussed and used to design a procedure for sampling crushed gold ore feed to metallurgical process plants. The approach involves calibration of certain ore-specific parameters. These parameters were calibrated for two different crushed gold ores en route to grinding mills in process plants. The model predictions were compared with the predictions from Gy?s original model. Far smaller masses of samples are required by the modified model than by Gy?s model at the same relative variance. The representativeness of the sampling procedure if normally distributed errors are assumed was also calculated. These procedures and evaluations lead to significant savings on cost of handling and preparation of the samples and to a quantifiable degree of confidence in the analytical results for the process plant.

Jan 1, 1998

By E. J. Bonet, P. B. Crawford

It is fairly common practice to reinject water into the aquifer near the oil-water interface in water-drive reservoirs. There have been many studies of aquifer behavior without reinjection,l-5 but apparently no analytical studies have been made to indicate performance when injection wells are present in the aquifer. The diffusivity equation may be used to describe the pressure behavior in an aquifer. When sources are present it can be written as A general solution of Eq. 1 may be obtained as the sum of two solutions. One is a general solution of the homogeneous equation, obtained by dropping the source term in Eq. 1 and still satisfying the required boundary conditions. Another is a general solution of Eq. 1 satisfying homogeneous boundary conditions.1° The first solution, which corresponds to the aquifer without reinjection, has been given quantitative and qualitative treatment in the literature.l-5,8,9 The latter solution will be treated here. Solutions with variable injection rates are obtained by superimposing solutions with constant rates, so we have considered only the latter. Five cases have been treated here: 1. A linear aquifer of finite width and extent. Water is injected into the aquifer at point xo, yo at constant rate. The pressure along the line x = 0 is maintained at zero pressure. (See Fig. 1.) Equations showing the pressure distribution, rates, velocity and cumulative influx have been developed. Certain numerical results are shown. 2. A linear aquifer of finite width and extent. Water is injected into the aquifer at point xo, yo at constant rate. The rate of production along the oil-water water contact is maintained constant. Equations showing the pressure distribution inside the aquifer are presented. 3. A linear aquifer of finite width and extent. Constant pressures are maintained at opposite ends of the aquifer. Water is injected at constant rates at point xo, yo. Equations showing the pressure distribution are shown. 4. A linear aquifer of finite width and infinite extent. The pressure is maintained constant at the oil-water contact. Water is injected at a constant rate at point xo, YO. 5. A linear aquifer of finite width and finite extent. The pressure at the oil-water contact is maintained constant. Water is injected at constant rate per unit length along a line x,. The Linear Aquifer The linear closed aquifer, performing at constant terminal pressure was selected as the first case to be analyzed. The development of the equations is based on uniform injection per unit of thickness, and gravity effects are neglected. In practical application this condition is probably most closely achieved when the

Jan 1, 1970

By M P. Cipold, J F. Bachmann, C C. Bachmann, J Ha

Knowledge of fuel qualities is of ultimate importance for the efficiency of chemical plants or power stations. Although most blending yards are equipped with automatic samplers and the derived samples are processed in the laboratory, the quality variation of the blended product may still be strong. This is caused by several reasons. First of all the process of sampling, crushing, dividing and analysis is time consuming. Results are available only with a delay of two to 24 hours. During this time blending is operated without knowledge of the main parameters. Conveyors with high throughput require expensive sampling systems capable of handling samples which are representative. The frequency of sampling needs also to be high in order to be representative. This results in high maintenance costs and also downtime of the sampling system.Online analysis of bulk materials has matured over time and today it can supplement but not replace laboratory analysis. As an example, J&C Bachmann has realised a coal quality monitoring system on the coal supply of a South African coal processing plant. The plant consumes ~42 Mt of coal per annum. The blending yard consists of two sets of three heaps where coal of six different mines is blended according to the factory’s requirement. From there, the blended coal is fed to the factory on two different belts.In 2010 the plant installed a TEXAS X-ray fluorescence analyser as a trial. It was tested under different conditions on several belts before the customer decided to install six TEXAS analysers on the feed belts to the stackers and two more analysers on the reclaimer belts. All analysers are installed directly on the belt and not on a substream.During the test period blending strategies were developed in close cooperation between the customer and J&C Bachmann. The use of the analysers in conjunction with the blending model has proven that the variation of the reclaimed coal quality was decreased significantly, which results in increased process performance and significant cost savings.CITATION:Bachmann, C C, Bachmann, J F, Cipold, M P and Ha, J, 2017. Online quality control of a coal blending yard, in Proceedings Eighth World Conference on Sampling and Blending , pp 125–128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By George M. Fowler

THE Tri-State district, as outlined in this paper, refers to the entire mineralized area in southwestern Missouri, southeastern Kansas and northeastern Oklahoma (Fig. 1). The part of the district in Missouri and near Galena, Kans., is still sometimes referred to as the Joplin district (Fig. 2). The Picher-Miami area is that part of the Tri-State district located contiguously in Kansas and Oklahoma in the vicinity of Baxter Springs, Picher and Miami. This paper is confined almost wholly to the ore deposits of the Tri-State district and particularly to the Picher-Miami area. Our study of the ore deposits of this district dates from late in 1925 (by Fowler) and early in 1927 (by Lyden) to the present. Our work has been confined almost entirely to the search for ore for numerous companies and individuals. It was not possible for us to undertake numerous highly interesting investigations which presented themselves but which would not immediately help in finding ore. We particularly refer to the general structural geology of the Ozark uplift, the genesis of the ore, and other problems of a similar nature. The local and general structural problems of the district are being solved gradually as the work progresses. The factors that control the loci of the several orebodies are evident. This paper is based almost exclusively upon our own observations. Most of the important mines in the Picher-Miami area were studied in detail. A map (Fig. 5) is included which shows this area and the properties we have examined to date. When it was convenient we visited, studied and compared structural relations in numerous mines in states outside the district. Some of these observations are noted in this paper.

Jan 1, 1932

By J. P. McDonald

Exposure to particulates containing metals and metal fumes (PCMMF) is a potential concern in ore refining and smelting. Some metals of primary interest are arsenic, cadmium, copper and lead, which have been linked to various adverse health effects. The current National Institute for Occupational Safety and Health (NIOSH) sampling method for metals in particulates requires the use of a filter, precision airflow pump and laboratory analysis. A major concern with this method is the one-to-two weeks? wait before laboratory results are available for use in determining if additional controls are needed to assure adequate exposure protection for workers. Particulates containing these metals were sampled during sixteen sampling events at a copper smelter using the traditional NIOSH methods. Monitoring of particulates was simultaneously conducted using a TSI 8520 Dust-Trak real-time aerosol monitor with a 10-µm-cutpoint sampling inlet. NIOSH analytical methods related to particulates and metals (methods 0500, 0600 and 7300) were used to determine particulate mass and individual mass contributions of metals on sample filters. Linear regressions with y-intercepts forced to zero were developed to determine the relationship between the PM10 measurements recorded by the DustTrak and laboratory-reported total particulate mass, PM10 and respirable arsenic, cadmium, copper and lead concentrations. These linear regressions yielded correction factors that can be applied to DustTrak readings to obtain total particulate mass, PM10 and respirable concentration estimates for each of the four metals. The R2 (coefficient of determination) values from the linear regressions ranged from 0.65 for total lead to 0.91 for total copper. These results suggest that the DustTrak may produce real-time data useful in providing estimates for airborne concentrations of arsenic, cadmium, copper and lead in copper smelter particulates.

Jan 1, 2011

Grade uncertainty can have a number of important implications for a mining operation. One of the most significant risks in not considering grade uncertainty in planning is the over or under allocation of processing or mining capacity when compared to realised grades. This could lead to wasted capital expenditure or missed opportunities to add value. This paper demonstrates a method that optimises production capacity and mining schedules in the presence of grade uncertainty. Applying this method to the case study of a nickel deposit recommended a reduction in processing capacity, an increase in mining capacity and more extensive utilisation of stockpiles than optimisations completed with traditional methods. As a result, average NPV improvements of between seven per cent and 27 per cent were gained.

Dec 6, 2010

Equilibrium calculational software programs can be effectively utilized to illustrate the importance of activity or concentration, solubility, temperature, solution pH, solution potential, and ligand complexation to students studying hydrometallurgy. The calculational program STABCAL will be demonstrated. illustrative examples for the creation of diagrams such as EH-pH, activity or concentration-pH and activity or concentration-EH will be presented to demonstrate the fundamentals of real hydrometallurgical systems. Speciation, titration and mixing will be used to simulate or predict operational processes. Applications will include treatment of Acid Mine Drainage (Berkeley Pitlake water and sediments), mass balance potential/pH diagrams, leaching and selective separation of metals from electroplating sludge, metal adsorption at femhydrite surfaces, and flowsheet development for treating mercury sulfide K106 sludge.

Jan 1, 2002

By L. A. Roe

Calcium carbonate and talc fillers both find use in a multitude of Industries. Each filler has many commendable properties, and often compete for the same market. Quality controls for various grades are exacting and complicated. A detailed comparison of the physical and chemical properties of these two fillers is tabulated and the mining and processing of the ores is described.

Jan 1, 1980

By Deno M. Pappas

The purpose of this Bureau of Mines study of U.S. roof and rib (roof- rib) accident statistics and related accident costs is to define current accident trends (1980-84) associated with fatal and nonfatal roof-rib fall accidents. Data were retrieved from a data base containing all recorded U.S. mining accidents, then sorted and normalized utilizing a computer software program. The statistics indicate that roof-rib accidents have significantly declined in the 5-yr study period. Moreover, they indicate that there have been increases and/or patterns of roof-rib accidents associated with specific mine characteristics, such as seam height, mine size, geographic location, and seasonal variations. Also, roof-rib injury characteristics produced pattern changes involving worker activity, lost workdays, types of injury, and severity of injury. A conservative estimate indicates that there has been a 30% adjusted increase in the cost of a roof-rib accident over the 5-yr study period.

Jan 1, 1987

By J. Roodt

Paper written on project work carried out in partial fulfilment of B. Eng (Metallurgical Engineering) degree This work was done to characterize the leaching of a uranium containing pulp processed by a South African producer to identify parameters that could be adjusted to increase the extraction of uranium in the existing circuit. Batch leach tests were used to characterize the leach properties and especially the influence of the oxidant concentration on the leaching achieved. It was found that relatively high extraction could be obtained even at room temperature by using a high liquid-to-solids ratio and that increasing the oxidant concentration significantly improved the leaching of the uranium minerals.

Jan 1, 2003

The Skorpion Zinc Project demonstrated the viability of the production of zinc from non-sulphide (commonly called ?zinc-oxide?) ores, using the leach/solvent extraction/electrowinning process route. The success of Skorpion raised the profile of a number of other zinc oxide deposits, considered to be similar. However, a study of three such deposits demonstrates that the application of whole-ore-leaching may be limited and that the concentration of zinc, or at least the separation from acid-consuming gangue minerals, prior to leaching is essential to the successful recovery of zinc from these deposits. The recovery of zinc is dependent on an understanding of the geology of the deposit, the mineralogical association of zinc minerals with gangue minerals (Boni, 2005) and limitations of mining practice. Flow sheet development and the associated metallurgical test work to derive an economically viable treatment route from two of these deposits are discussed. Key parameters affecting zinc recovery by gravity separation and flotation are presented, demonstrating that even minor differences in mineralogy have a profound impact on zinc recovery and reagent consumption. The study also deals with the determination of appropriate design parameters through metallurgical mapping of the dense media separation process.

Jan 1, 2008

By R. V. Ramani, C. J. Bise

INTRODUCTION Classification of coal seams as thin, medium, and thick is both subjective and relative and is more a reflection of the statistical mode of the thicknesses en- countered in a mining region. A geological factor more precisely understood as defined than thickness is the inclination of the seams to the horizontal, commonly referred to as the pitch or the dip of the seam. Thick and steeply pitching seams present far more challenges to the ingenuity of the mining men to devise methods for their extraction than the thick and less steeply inclined ones. In a marginal case, where a thick coal seam may be minable by surface or underground methods, the decision bears a close relationship to the technological developments in the mining scene. Near surface thick coal seams are a special gift of nature and are not as wide- spread as the ones that call for the application of under- ground methods. Recent advancements in surface mining equipment have made it possible to surface mine to great depths. Stripping ratios of 30: 1 (cu yd of over- burden removed per ton of coal) have been achieved. The extraction of thick seams which preclude the use of surface methods is the concern of this chapter. Specifically, the objective here is to outline the special technological factors in underground mining of thick coal seams and to illustrate through several case histories the methods that are practiced in the North American continent. For the purposes of this chapter, a thick seam is defined as one which is not readily minable with currently available equipment without modifications to the extraction method or the equipment. At the present time, a thickness of 4.8 m (16 ft) can be considered as the lower limit, although developments in equipment and methods can be expected to push this limit upwards. The data for the case histories were collected from two extended mine visits in 1975 and 1978, and from other published accounts of the mines visited. Reference is drawn particularly to reports by Bise, Ramani, and Stefanko (1976) and Rarnani and Kenzy (1979). THICK SEAM MINING METHODS The various methods of mining thick seams can generally be grouped into three major categories: full face methods, where the entire thickness of the seam is re- covered in a single pass; slicing methods, where the seam is extracted to its full thickness by horizontal or inclined slices either in an ascending or descending order; and caving methods, where the seam is undercut and the en- tire coal seam is recovered by caving the top coal into the excavated cut, or some variations of the basic sub- level caving method. As shown in Table 1, in each of these methods, the coal is removed by either room-and-pillar or longwall methods. Hydraulic mining and transport of the coal in open flumes or in pipelines are also practiced. Addition- ally, the void created by the removal of coal may be filled with a packing material (stowing) except in the caving methods. The pitch (dip) of the seam, particularly when it is greater than 0.26 rad (150), imposes severe operational limitations on mobile equipment. A more detailed general discussion of the methods can be found in Bise et al. (1976) and Vorobjev and Deshmukh (1964). Specific discussion on the many variations of the three basic methods can be found in the papers presented at the international symposia that were held in

Jan 1, 1982

By R. Tipman, T. C. Burnett

"A general computer program has been written to calculate material balances using multiple regression techniques. The program can handle metal assays or size distribution data obtained in multiple surveys of the flotation circuit. The ""best fit"" weight split is calculated between the input and product streams by minimizing the sum of squares of the residual errors using all of the available data. The program includes an assay adjustment feature in which each assay is recalculated to fit the ""best fit"" mass balance. Thus assay or sampling errors can be easily identified. Also the assays can be statistically weighted so the most precise measurements are given the most influence on the material balance. The computer output reports the mass balance, the actual and corrected assays, the percent metal recoveries and the significance and confidence levels for the weight splits.The program enables a rapid and accurate evaluation of mass balances from large masses of data obtained in multiple surveys around a flotation circuit. The effects of changing process variables can be quickly evaluated with statistical confidence."

Jan 1, 1978

By Natalie White, Joel Asp, Allyz Kramer

"Minnesota has robust reclamation standards and have proven results in the taconite mining industry. Reclamation of overburden spoils, lean ore spoils and fine tailings from taconite production has generally been successful on the Iron Range, using a low input standard reclamation practice. Success at reestablishing vegetation on these landscapes is likely due to fairly favorable chemical and physical properties (e.g., few limitations due to acidic generating materials, metal toxicities and water and nutrient holding capacities). However, coarse tailings reclamation has proven more difficult, presumably due to lower nutrients and challenges with moisture holding capacities. Research efforts conducted since 1990 have struggled to develop a reclamation strategy for coarse tailings that meets the Minnesota Mineland Reclamation Rules, Chapter 6130. However, new breakthroughs in scram mining technologies are producing fine and coarse tailings that have not been encountered nor reclaimed in northern Minnesota. Scram mining in Minnesota is defined as those mining operations that produce natural iron ore concentrates. Innovative research is underway to investigate and determine successful reclamation strategies to reclaim scram mining tailings from these scram mining operations. The research program is conducted through collaboration with SEH, Prairie Restorations, Inc. (PRI) and Mining Resources, LLC with funding support from the Iron Range Resources and Rehabilitation Laurentian Vision Partnership minescapes grant program.The research program was divided into three phases:Phase I. Bench-scale testing to identify successful treatments to reclaim and restore scram tailings through evaluating surface soils amendments, viable seed mixes and plant germination, growth and densities. Phase I was completed in early 2015.Phase II. Field-scale pilot trial to test larger scale effectiveness of the treatments deemed successful in Phase I and test various vegetative assemblages and planting techniques focused on the unique challenges with scram tailing basins. Phase II was completed in late 2016 with a summary monitoring report.Phase III. Produce a technical report of results for the research undertaken in this study, as well as compile prior reclamation results used during previous Minnesota iron mining reclamation projects on tailings basin applications. Phase III was completed in 2017 with a summary monitoring report and recommendations."

Jan 2, 2018

By F. H. Cornet, D. Ask, O. Stephansson

We have conducted a stress analysis of overcoring stress measurements undertaken at the Zedex Test Site (ZTS) in the Äspö HRL, Sweden. Two different types of overcoring cells have been used at the site: the 9-gauge Borre Probe (CSIR-type) and the 12-gauge CSIRO HI cell. Inversion programs based on the least-squares criterion were developed and calibrated. The primary and secondary stress field in the ZTS were back-calculated using strain data from individual cells as well as from combining data from both cells. We propose that the combination of strain data from the two cells significantly improves the determination of the stress field. A striking result is the good agreement between the re-analysed overcoring data and the existing hydraulic fracturing data. The deviations for the horizontal stresses between the re-analyzed overcoring data and the existing hydraulic fracturing data are approximately 3 MPa. The deviation in the orientation of maximum horizontal stress is approximately 10-20°. Nous avons analysé les résultats de mesures de contrainte par surcarottage réalisées sur le site Zedex, du laboratoire souterrain HRL d’Aspö, en suède. Deux types de cellule de mesure ont été utilisés sur ce site : la cellule à 9 jauges (du type CSIR) et la cellule à 12 jauges (du type CSIRO HI). Un programme d’inversion mettant en œuvre une norme par moindres carrés a été développé et validé. Les champs de contrainte primaires et secondaires du site Zedex ont été évalués d’une part en considérant chaque mesure isolément, d’autre part en intégrant l’ensemble des données de déformation dans une inversion unique. Nos résultats suggèrent que l‘association des diverses mesures dans une intégration unique améliore nettement la détermination du champ de contrainte. Un résultat intéressant est le bon accord entre ces nouveaux résultats et les résultats des mesures par fracturation hydraulique. Les écarts sur l’amplitude des contraintes horizontales est de l’ordre de 3 Mpa, les écarts sur les orientations de l’ordre de 10-20°. Auf dem Zedex Test Gelände im Äspö Festgesteinslabor (HRL) wurde eine Spannungsanalyse mittels Overcoring Spannungsmessungen durchgeführt. Hierzu wurden zwei verschiedene Methoden verwendet: das 9-kanal Borre Gerät (CSIR- Ausführung) und die 12-Kanal CSIRO HI Zelle. Inversionsprogramme, die auf dem “least-squares”- Kriterium basieren, wurden entwickelt und kalibriert. Das primäre und sekundäre Spannungsfeld des Zedex Test Geländes wurde sowohl aus Verformungsdaten individueller Zellen als auch aus Kombination beider Zellen ermittelt. Wir nehmen an, daß die Kombination der Messergebnisse beider Geräte die Bestimmung des Spannungsfeldes signifikant verbessert. Überzeugender Beweis hierfür ist die gute Übereinstimmung der überprüften Overcoring Daten und Ergebnisse aus existierenden Hydraulic Fracturing Versuchen. Die Abweichungen der horizontalen Spannungen aus beiden Datensätzen ist etwa 3 MPa und Abweichungen der Orientierung der größten Horizontalspannung liegen bei etwa 10-20°.

Jan 1, 2003

By W. L. Saunders

It is now generally admitted by experts that at least so far as rapid progress is concerned the Alpine system of tunnel-driving is superior to any other. This is perhaps natural in view of the record of experience in driving tunnels through the Alps. These great mountain-chains cannot be treated in the ordinary way by shaft-sinking and driving headings, thus multiplying the points of attack. The work must be done from the ends only, hence speed in driving is of the utmost importance ; and, as necessity is the mother of invention, the concentration of effort to make progress has resulted in an organization and in mechanical appliances that have produced results so much in excess of the usual practice, even in America, that a discussion of the subject in detail should be of much value to the engineer and contractor. The first Alpine tunnel mas the Mont Cenis, length 7.5 miles, driven with a progress that averaged about 7.75 ft. per day. Next came the Saint Gothard, 9.5 niiles long, 18 ft. per day; Arlberg, 6.5 miles long, 27.25 ft. per day; Simplon, 12.25 miles long, 36 ft. per day. The figures represent progress when driving from two headings, so that by dividing them in two we get the daily single-heading progress. The latest of the Alpine tunnels is the Loetschberg, now being driven. In this work the world's record has been beaten by a single day's record in one heading of 36 ft. and by an average daily record in one heading of 29.5 feet. The Alpine range forms a natural barrier between a large section of northern and southern Europe. This range extends from the southeast of Prance to the frontier of Hungary, betveen Italy and the plains of sonthern Germany. The contour

Jan 1, 1912

By A. Burger Pintér

To be meaningful the sharing of ideas about the National Environmental Management Act (NEMA) and social issues within the context of Mining and Metallurgy (M&M) requires an honest scrutiny of the M&M/social environment relationship, both past and present. It is not a secret that this relationship has been and is fraught with difficulties. Thus from all perspectives (M&M, society and environmental and social consultants) such a dissection, that highlights the realities, both good and bad, is uncomfortable. For this section of the colloquium to have any value, the honest but difficult approach needs to be taken.

Jan 1, 2000

By James D. Noll, M. Eileen Birch

A monitoring method for diesel particulate matter was published as Method 5040 by the National Institute for Occupational Safety and Health (NIOSH). Organic and elemental carbon are determined by the method, but elemental carbon (EC) is a better exposure measure. The US Mine Safety and Health Administration (MSHA) proposed use of NIOSH 5040 for compliance determinations in metal and nonmetal mines. MSHA also published a rule making for coalmines, but no exposure standard was provided. A standard based on particulate carbon is not considered practical because of coal dust interference. Interference may not be a problem if an appropriate size-selective sampler and EC exposure standard are employed. Sub micrometer dust concentrations found in previous surveys of nondieselized, underground coal mines were relatively low. If a large fraction of the sub micrometer dust is organic and mineral matter, sub micrometer EC concentrations would be much lower than sub micrometer mass concentrations. Laboratory and ?eld results reported here in indicate the amount of EC contributed by sub micrometer coal dust is minor. In a laboratory test, a sub micrometer EC concentration of 31µg m 3 was found when sampling are spirable coal dust concentration over three times the US compliance limit (2mg m3). Laboratory results are consistent with surveys of nondieselized coal mines, where EC results ranged from below the method limit of detection to 18µg m 3 when size-selective samplers were used to collect dust fraction shaving particle diameters below 1.5µm sub micrometer EC concentrations were ?7µg m3. In dieselized mines, sub micrometer EC concentrations are much higher.

By H. Saroglou

Anisotropy is a characteristic of intact foliated metamorphic rocks (slates, gneisses, phyllites, schists). Testing was used to establish the anisotropic behaviour of selected gneissic rocks. The effect of anisotropy on various mechanical properties (strength, deformation) and dynamic properties (wave velocity) was examined. The rock samples were also tested at successively higher confining pressures in order to evaluate the effect of anisotropic behaviour at high overburden pressures.

Jan 1, 2004