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By S Chaudari, T Ren, T Harvey

Management of respirable dust on longwall face remains a challenging issue for mine operators, particularly for the new generation of thick seam longwalls. A fundamental understanding of the airflow behaviour around the shearer is critical for dealing with the dust control issue on longwall faces. Computational fluid dynamics (CFD) modelling techniques have been used in this study to conduct a detailed investigation of the air and respirable dust flow patterns around the longwall shearer. Three CFD models have been developed to represent different longwall cutting heights. The results of these modelling studies tallied well with field measured airflow data from different mines. The validated thick seam longwall face model was then used for detailed parametric studies to simulate the effect of various parameters and dust control concepts. The dust control options investigated include various spray configurations, shearer clearer, modified cutting sequences and shearer scrubbers of various capacities to minimise the respirable dust migration towards the walkway area of the longwall face. This paper presents a summary of the results of these CFD modelling investigations.

Jan 1, 2005

By W. S. Gresley

The traces of fossils herein described were discovered in or upon piles or heaps of iron-ores upon the docks at Erie, Pa. The author has worked among these ore-piles since 1890, when his attention was first directed to what looked like organic remains upon certain specimens collected. All the specimens described and figured herein were found by him, and, as no ironore is used at Erie, and no other iron-ores, save those of the Lake Superior region, find their way to the stock-piles at this place, there can be no question but that the specimens in question are genuine ore transported from that region over the great lakes, and cannot have been brought in from other ironore regions. The author has reason to think that no fossil remains have been reported hitherto as occurring in the iron-ores of the Lake Superior region, and he believes that these specimens, however imperfect, rank among the oldest forms of which man has any knowledge. The illustrations are engraved from photographs of drawings. The specimens themselves have not been photographed, because their condition would have prevented bringing out, by that process of reproduction, all the markings as clearly as is necessary, and would have rendered the specimens otherwise less distinct by reason of the blotchy character of their colors, the presence of cracks, or of marks more or less in contact with those of the organisms. In drawing these remains, therefore, I left out everything upon the specimens of ore that did not seem to belong in any way or contribute to their value as illustrations of the fossils. According to information obtained from the dock superintendent at Erie, Pa., the majority of these specimens came from the Chapin mine, Iron Mountain, Menominee range, Mich. As to the rest of them, I stupidly failed

Jan 1, 1897

By J. B. Yianatos

A practical an interactive model to describe the operation of a flotation bank of mechanical cells was developed based on the hydrodynamic and metallurgical characterization of large industrial flotation cells. Thus, the mineral grade and recovery, as well as the stream properties along the flotation bank can be described in terms of the operating variables. The model was built considering the flotation bank as a distributed system, so the solution for the water and solids mass balances, per size classes, for each single cell, are sequentially solved. Also, each cell was described by two distinct zones, the collection zone characterized by the flotation rate constant and the froth zone characterized by the froth recovery. The mineral feed was described in terms of the mineral species and particle size classes, using a rectangular flotation rate constant distribution. Also, the effect of changing the actual operating variables (air flowrate, pulp level, pulp density, pulp flowrate, etc.) on the mineral collection process, in the collection (pulp) zone, was considered downstream along the bank. The froth recovery of floatable mineral has been estimated by measuring the mass flowrate of particles entering the froth by true flotation together with the concentrate mass flowrate (ton/h). The mass flowrate of collected particles at the pulp/froth interface level was calculated from direct measurement of bubble load (ton/m3) and gas flowrate (m3/h). Flotation recovery is mainly related to the froth depth and air flowrate. All parameters considered in the model have been adjusted from direct measurements in plant site. Also, the effects of other operating variables such as reagents dosage, top of froth grade, or froth discharge velocity are presently under study. This procedure has been tested using data from industrial rougher operations consisting of flotation banks with 5 cells to 9 cells in series, and different cell sizes, such as 45m3, 130m3, 160m3 and 250m3. Thus, it has been shown that the model approach is a powerful tool for flotation cells diagnosis, operation and development of new control strategies, as well as, to evaluate the effect that de-sign and operating variables have upon the collection and froth zones performance in large flotation cells.

Jan 1, 2014

By R. M. Oliver

THE Falconbridge property is almost completely covered with over-burden to a depth varying from 60 to over 200 feet. This overburden consists of grave], sand, and boulder, with bands of very fine silt, and there is usually a layer of water-bearing quicksand adjoining the r:ock surface. In previous shafts sunk at Falconbridge, this water-bearing quicksand had given considerable trouble, and further difficulties were expected in sinking No. 5 shaft, due to its greater size. The method described in this paper is the one adopted in sinking this shaft, after the matter had been carefully considered. No. 5 shaft is located 2,400 feet east of the old main No. l shaft, and is sunk in norite in the hanging-wall of the ore-body, which is, however, ? practically vertical to the deepest known intersection. The greatest depths of overburden prevail on the south side, or footwall, of the ore-body, and this, together.. with the fact that the footwall is wet and more badly fractured, swayed the final decision to sink in the hanging-wall. After the shaft site had been chosen and cleared, a diamond drill was set up a few feet away and a hole bored to a depth of 405 feet to test the over-burden and character of the norite bedrock. The depth of overbudren indicated by the hole was Ill feet, with the last 10 feet water-bearing. The norite was rusted and broken up for only a few feet below bedrock. A steel sinking shield (Figure l) was assembled at the shaft location, and consisted of 5/8-inch plate, 5 feet deep, built around a frame of 6 inch by 6 inch angle-iron, and braced at the corners with the same material. Twelve-inch I-beams held the shield as rigid as possible. In order to reduce binding against pebbles to a minimum, the shield was constructed with a 1-inch batter on all sides.

Jan 1, 1938

By D. S. Colby

Statistics on the volume of natural gas produced in the United States were first collected for 1906. A summary of those statistics covering 1906-35 was incorporated in the 1937 Minerals Yearbook. This summary, covering 1936-50 presents, by States, a number of the more important statistics that have appeared in the natural-gas chapter of the Minerals Yearbooks. The period covered has been one of rapid expansion, especially of long-distance transmission lines. Natural gas was made available to some States for the first time; in other States the degree of dependence upon supplies transported from outside their boundaries changed rapidly. Thus, an isolated series of statistics cannot be studied without considering other regional influences that reflect in the overall operations of the industry. These tables accordingly have been designed to show for each State the simultaneous changes taking place in the various sectors surveyed. The tables show production data in the upper portion and consumption data in the lower portion. They are arranged alphabetically, by States. A copy of the 1906-35 production summary from the 1937 Minerals Yearbook has been included.

Jan 1, 1952

Previous methods for the assessment of the explosive potential of gas mixtures have required the plotting of apeexplosibility diagram. These became cumbersome if a large -number of assessments of various sampling locations over a period of time wererequired. This may make the approach of a dangerous situation more difficult to predict. With the aid of a programmable calculator, a new method for the rapid assessment of the explosibility of coal mine sample gases has been developed. This method does not require that an explosibility diagram be drawn to indicate the explosive status of a gas mixture. Simple Cartesian co-ordinates representing the explosive potential of,mixtures are obtained, which may readily be plotted to show changes with time.

Jan 1, 1981

By P. Mousset-Jones, G. Danko

Rock thermophysical properties, i.e. heat conductivity and thermal diffusivity, were obtained for reference values at the Waldo Test Mine for mine fire simulation purposes. An in situ measurement method was chosen since it could include the effect of rock fractures. The REKA method (Rapid Evaluation of k and alpha) was used because it can measure conductivity (k) and diffusivity (alpha) simultaneously within an eight-hour measurement period. A total of six measurements were taken in three different holes, and at two different depths from the collar of the hole. Each measurement provided an averaged conductivity and diffusivity for a volume of rock of approximately one cubic meter. The boreholes were driven into the upper and lower limestone, two at right angles to and one parallel to, the stratification of the rock. Significant representative conductivity and diffusivity values were obtained for the whole mine by averaging the six measurement results. The thermal properties for the band of shale in between the two limestones were not measured in situ, but only in the laboratory. Problems were encountered in the evaluation because of unexpected heat conduction on one side of the symmetrically built probe. A modification was made to the previously developed evaluation method together with further testing and correction, before the final results were obtained. As expected, the in situ and lab- oratory measured values of k and alpha compared favorably, since the in situ rock was dry and relatively unstressed.

Jan 1, 1989

By Mizuta T, Sakurai M

The Pine Creek Inlier produced 12 440 kg of gold in the period from the first gold discovery in the 1860s to the early-1900s. During the 1930s renewed large-scale prospecting took place and gave a foothold for today's gold mining operations. The rise of the gold price and improved mining methods in the 1970s and 1980s made possible low cost, bulk low grade mining operations. Various gold deposits including vein, network and stratiform types occur in the Pine Creek Inlier (Nicholson and Eupene, 1990). The Tom's Gully deposit is located 100 km south-east of Darwin in the Northern Territory. It is hosted in the early Proterozoic Wildman Siltstone and lies north-east of 1800 my old Mt Bundey Pluton (Figure 1). Around the Mt Bundey Pluton, there are several prospective base and precious metal deposits such as Quest 29. The Tom's Gully gold deposit was discovered in 1986 and yielded a total of 3070 kg of gold from ore averaging 9.35 g/t gold between 1987 and 1990 when the mining operation was terminated.

Jan 1, 1994

In 1984/85 financial year Australia produced 529 thousand barrels per day (kbd) of crude oil. By far the major contribution (453 kbd) was light waxy oil from offshore Gippsland, Victoria. When these discoveries were made in the latter 1960s, imported oil was available in abundant supply and at low prices. Because of this, the Gippsland producers persuaded Government to control the marketing and pricing of their crude, and thus provide the required security of offtake. Political events in the middle East created supply shortages during the 1970s, and dragged up government selling prices for OPEC crude oil. Thus Arab Light crude that sold for less than US$2/barrel (bl) in 1970 reached $34/bl in 1981. Following the consequent decline in world oil demand, in 1982, Australian refiners sought to evade their obligation to lift Gippsland crude. Hence, in 1983, the Government was forced to introduce a floor quota of 385 kbd of Gippsland crude liftings and to allow producers to export any additional production refiners did not require. On expiry of the old arrangements, Government introduced a partial free market from January 1985, whereby the balance in excess of 350 kbd may be sold to Australian refiners at negotiated prices, or exported as before. In 1984/85 exports were some 90 kbd and will be higher in the current year. About half this total has been exported by BHP, providing valuable experience and lessons which are described in the paper.

Jan 1, 1986

By Ishijima Y, Goto T

Displacement Discontinuity Method (DDM), which was originally developed by Crouch,S.L., is a powerful tool to calculate mechanical disturbances due to tabular excavations. Three topics on DDM applications to strata control problems in Japanese deep coal mines are described. First, is numerical simulation of microseismicity induced by longwall mining in Horonai Coal Mine. Microseismicity in the mine had been monitored by a mine-wide seismic ar- ray. Location of microseismic events and in- tensity of seismicity were well simulated. In the simulation procedure based on DDM, first, zones where a failure condition is satisfied by the advance of mining are detected. Then, the seismic moments, which indicate the inten- sity of seismicity, at the failure zones are evaluated. Second, is prediction of the shaft damage due to mining in Sumitomo Akabira Colliery. In this mine, the limit angle of the shaft pillar was changed from 600 to 800 to increase the amount of minable coal volume without increas- ing mining depth. Displacement of the shaft axis has been measured to assess the damage due to mining around the shaft pillar. In the calculation based on DDM, a fault intersecting the shaft and the ground surface are con- sidered. Observed and predicted displacement of the shaft axis agreed well.

Jan 1, 1992

By W. W. Stephens

As part of the Bureau of Mines program directed toward more effective utilization of the mineral resources of the United States, a number of processes for production of sponge iron have been investigated. The use of sponge iron as a raw material for production of steels and other ferrous alloys offers several possible advantages over the conventional pig-iron and scrap process, especially for utilization of the smeller, widely distributed iron-ore deposits of the western United States. Although considerable information has been made available on various processes for production of sponge iron, little information 118.6 been published heretofore on the problems and costs involved in melting the sponge iron for production of steel. The present Paper reports the results of tests conducted at the Bureau of Nines pilot plant at Redding, Calif. in which several different types of sponge iron Were used as charge material for production of steel in a 4-ton-capacity basic arc furnace.

Jan 1, 1949

By Djona M. Gaballah I.

Selective chlorination of unroasted and roasted spent hydrorefming catalysts was studied between 300 and 600°C using the following gas mixtures : C12+CO, C12+N2 and CI2+air. Such materials contain Co, Ni and Mo compounds supported by alumina and/ or silica. They also contain variable amounts of V compounds, C, S, etc., accumulated during the life time of the catalyst. Direct oxychlorination of the C+S rich sample allows higher extraction rates than those obtained by the carbochlorination of the same roasted one. It seems that the roasting step doesn't favor the economic metals' recovery. Results of the chlorination of C+S poor spent catalysts, in the presence of CO, in the chlorinating gas mixture, or of carbon added to the sample, were comparable. Cobalt and nickel chlorides were .extracted from the chlorination residues by their dissolution with acidified water, whereas molybdenum and vanadium chlorinated compounds were recovered by selective condensation from the vapor phase. The recovery rates of valuable metals as well as the selectivity were higher for the chlorination of spent catalysts than results obtained by the hydrometallurgical processing of the same sample. Results of the scale-up of the oxychlorination of the unroasted sample confirmed those of the laboratory scale. The global recovery rates were about 88 pct of cobalt, 93 pct of molybdenum and 76 pct of vanadium. The carbochlorination was applied to the recovery of W and Ti from Denox catalyst that is a carbon and sulfur free one. Recovery rates higher than 99 pct at temperatures lower than 500 °C could be obtained. This may indicate that the chlorination process can be applied to the treatment of various industrial wastes or by-product containing transition and/or refractory metal compounds A flow - sheet for the pretreatment of these materials is proposed.

Jan 1, 1995

By Doyle A. Ellerbruch

An FM-CW microwave system was investigated for measuring coal layer thickness. Measurements were made in three different mines near Pittsburgh, Pennsylvania, near Fairview, West Virginia, and near Coffeen, Illinois. Microwave frequencies in the range 1-2 GHz were used to measure samples up to 55 cm thick. All samples were backed with a naturally occurring shale. Measurements were also made on coal and shale samples compounded in the laboratory at the Bureau of Mines Pittsburgh Mining and Safety Research Center near Bruceton, Pennsylvania. The results indicate that layer thickness can be determined in most cases, although large anomalies may, in some cases, produce misleading results. Many anomalies that were detected with the FM-CW system were verified visually by drilling into the coal layer. The dielectric constant of coal apparently varies significantly within a coal seam. The form of the output signals from the FM-CW system seem to simplify the data interpretation and analysis process as compared to the manually swept microwave system used previously. It appears that this technique has the potential of measuring changes in the dielectric constant of a coal seam and providing an output that can be used for real-time corrections in layer thickness; measurement.

Jan 1, 1976

By Tucker G, Clark A, Young M. F, Johnston M

Mount Isa Mines has made a huge commitment to process control in milling. Yet in lead zinc we still failed to achieve a steady operation. Comparisons with manufacturing plants showed the key difference was failure to control plant inputs. Lead

Jan 1, 1998

By Salley J, Gould WD

The stack-gas scubber effluent from base metal smelters often contain 20-100 ppm of oxidized selenium salts. Due to their toxicity, these must be removed from solution prior to release of the effluent to the environment. Many species of microorganisms including Corynebacterium diotheriae, Neurospora crassa, Candida albicans, Escherichia coli and various species of Salmonella are capable of assimilating oxidized selenium and reducing it intracellularly to red amorphous selenium. CANMET in cooperation with several companies has developed a biological process to recover selenium from dilute solutions. The laboratory, mini-pilot plant and the large industrial pilot- plant studies leading to the development of this process will be described.

Jan 1, 1990

By M. J. Beus

The U.S. Bureau of Mines is conducting investigations to improve design methods for mining volcano-genic massive-sulfide (VMS) type deposits in environmentally sensitive regions. This study was conducted at the Greens Creek Mine, which is typical of many VMS-type deposits throughout southeast Alaska, and served as a case history for computer modeling and structural analysis. Results indicated that the finite-element design method provided reasonable comparisons with both the anticipated regional stress regime and the measured deformational response of the underground accessways. Investigators concluded that reasonable accuracy can be expected for stability analyses of proposed mine design scenarios at this mine using the results of this preliminary study.

Jan 1, 2010

By D. Komljenovic, E. Lafontaine, J. Paraszczak

Availability of the production equipment used in underground mines has a substantial impact on production costs and, thus, on mine profitability. Appropriate collection of pertinent data and information, as well as use of adequate performance measures and their analyses, can help mine operators identify cost-effective opportunities to improve equipment availability. This paper presents study results aimed at reviewing and analyzing means and measures used to quantify equipment availability and its contributing factors (reliability, maintainability and maintenance support) in several Canadian underground mines. It overviews sources, as well as quality and quantity of relevant data and information, and examines performance measures and their definitions, as applied to surveyed mines. Problems concerning data acquisition and meaningfulness of the performance measures are discussed. The paper concludes with some suggestions and recommendations concerning several aspects of equipment availability assessment. Evidence suggests that the latter may become a more useful tool for mine operators in their efforts to reduce production cost.

Jan 1, 2008

By J. H. Moran, E. E. Finklea

The pressure build-up technique is a recognized method of determining permeability from conventional drillstem tests. In this paper an effort is made to extend such techniques to the interpretation of data obtained from the wireline formation tester. Such a study is necessary because of the differences, for this case, in the magnitude of the flow parameters (rate of flow, amount of recovered fluids) and in the flow geometry (flow through a perforation vs flow across the face of the wellbore, etc.) involved in the solution of the equations of flow for compressible fluids. The perforation is replaced by a spherical hole, and the effect of the borehole is neglected, so that the flow can be considered to be radial in a spherical co-ordinate system. Arguments are presented to justify this idealization. Assuming single-phase flow, general relations between pressure and flow rate are developed for a homogeneous medium. The study is then extended to permeable beds of finite thickness. It is shown that the early stages of pressure build-up tend towards spherical flow, while the later stages tend towards cylindrical flow. The thinner the bed, the more quickly flow approaches the cylindrical model. The prevalence of thin beds in practical work makes this analysis quite important. Cases involving permeability anisotropy are treated. INTRODUCTION From wireline formation tester operation, two types of data are obtained: (1) the nature and amount of recovered fluids, and (2) the pressure history recorded during the test. A number of papers have been written dealing with the interpretation of formation production on the basis of the recovered fluids.'.' In general, the methods described have been quite accurate for both high- and low-permeability formations. The present paper will deal with an analysis of the pressures observed. An analysis of the pressure build-up curves obtained in hard-rock country has already been attempted on the basis of the formula proposed by Hor-ner. Although this approach has met with success in many instances, some questions have been raised as to its validity. It is the aim of the present study to place the analysis of pressure build-up in the formation tester on a firmer basis, from which more detailed methods of interpretation can evolve. Because of the great differences between the operation of the wireline formation tester and the conventional drillstem test, modifications are necessary in the interpretation. The major difference relates to the flow geometry. Once the flow geometry has been established other features such as multiphase flow, skin effect, afterflow, etc., well described in the literature, can be introduced. It will be assumed that the mechanical operation of the formation tester is already known to the reader.6 t will suffice here merely to state that the tester provides the means for taking a relatively small sample of the fluid immediately adjacent to the borehole, and for recording the subsequent pressure response. In comparison with conventional drillstem tests, the time required for a satisfactory pressure build-up response is much shorter, because of the relatively small quantity of fluid withdrawn by the wireline tester. This feature is highly desirable in the case of low-permeability formations. For an analysis of the pressure response within the formation, three simple flow geometries are considered— linear, cylindrical and spherical. The spherical and cylindrical flow geometries are most pertinent to the formation tester; therefore, they will receive the major emphasis. Since the configuration of the borehole and the perforation made by the tester complicate the flow geometry, it is necessary to allow for them in the drawdown response. However, because of the volume of formations contributing to the pressure-response, the details of the perforation shape are unimportant in the build-up period. Since relatively small amounts of fluid are withdrawn from the formation, in contrast to a conventional drill-stem test, a study of the "depth of investigation" and the significance of drawdown as well as build-up data will be included. Because the "depth of investigation" will be shown to be rather large, the effect on the build-up curves of the finite thickness of the permeable bed is considered. It is this consideration that leads to the importance of cylindrical flow geometry. Also included is a discussion of permeability anisotropy and its effect on the interpretation of the tester results. The pressure curves recorded by the formation tester will follow two general patterns, depending upon whether the formation is of high or low permeability. Fig. I (a and b) schematically illustrates these two responses. In Fig. 1(a), the high pressure recorded during fill-up of the tool is essentially the pressure differential across the choke in the system. In Fig. l(b), the flow rate is

By S. Seetharaman, Du Siehen

"In the processing of molten metals, it is extremely important to monitor continuously the concentration levels of various minor elements. In the production of common metals like copper, iron and aluminium electrochemical sensors involving solid as well as liquid electrolytes are being increasingly used to measure the concentrations of minor elements. The present paper deals with the electrochemical principles underlying these measurements and the possible errors involved. One of the major difficulties in the case of the solid electrolytes is to correct for the consequences of the electronic contribution to the conduction of the electrolyte.The application of the electrochemical sensors for molten metals processing involves designing of these probes to withstand the industrial operating conditions. In this respect, significant achievements have been made with respect to the design of oxygen probes for liquid metals in general and liquid copper in particular. Some of the salient design features are discussed in the paper. The application of auxiliary electrodes for impurities in molten metals like phosphorus in copper and silicon in iron are taken up. The development of oxygen sensors for slags is given special attention. Recent developments in the field of sensor technology, as applied to metals processing are highlighted.1. IntroductionThe rapid technological advancement today require precise control of the process parameters and the impurity levels. Most of the molten metals processing in industrialized countries are often steered by suitable computer models, either phenomenological or simulations based on theoretical principles. These models often require that the process parameters are continuously monitored so that the progress is followed and modified suitably as and when required. It is common practice to measure temperatures by incorporating temperature sensors at the various strategic points of the reactor. In the case of monitoring the composition changes in the various phases, the method of sampling followed by routine chemical analysis involves a time lag as well as uncertainties in sampling and analysis. In this respect, electrochemical sensors have the advantage of generating accurate data when properly applied and increasing attention is being paid in the development of electrochemical sensors for various common species in molten metals processing. In the present paper, the developments in this area over the years are outlined and typical process applications are discussed. A greater emphasis will be laid on sensors based on oxygen conducting electrolytes and their application to the production of common metals like iron and copper."

Jan 1, 1996

By R. V. Ramani, R. A. Jankowski, R. Bhaskar

The spatial distribution of airborne dusts, deposition of dust in the airway, as well as the effect of airflow velocity and particle density on dust behavior in mine airways were studied in a set of experiments performed in a mine airway under controlled conditions. Considerable deposition of dust near the source was indicated. Pronounced effects due to velocity were observed in ambient dust concentration and deposition along the mine airway, both in the respirable and the total size ranges. Cross-sectional concentration measurements indicate an increase in concentration from the roof to the floor. The average cross-sectional concentration is about 75% of the concentration in the center of the airway.

Jan 1, 1987