Search Documents

By J. J. Barakso, S. J. Horsky, H. V. Warren

"A review of past and present biogeochemical studies is given. Early and more recent analytical procedures are described and compared. Tables 1-5 give silver concentrations in various organs of some plant species at different localities. Table 6 and conclusions provide guidelines for exploring for silver using biogeochemistry.IntroductionBiogeochemistry has been shown to be a useful tool in the search for gold deposits, especially those of the disseminated type (Warren and Barakso 1982). The purpose of this paper is to demonstrate that biogeochemistry can also be of assistance in searching for silver concentrations buried by as much as twenty feet of overburden without inflicting any damage on the environment."

Jan 1, 1984

By Dean Bray

During the past three years, a new rear-dumping dragline bucket technology has been patented, developed and tested at North Dakota coal mines. Field testing has shown that this new concept in dragline bucket technology can improve strip-mining efficiencies by reducing cycletimes and increasing dumping radius. This article details the process, participants and the results for the development of a rear-dumping dragline bucket. Participants in the process In November 1995, the board of directors of Dakota Coal authorized the execution of a field test and option agreement and a license agreement with the partnership of D.F. Schmidt, electrical/maintenance supervisor, and Bill Lengenfelder, president of Modern Industrial. The board also authorized entering into a dragline bucket field-testing agreement with the Falkirk Mining Co.

Jan 1, 1999

By Dennis R. Dolinar

Physical property tests were conducted on drill core from three exploratory holes on the Naval Oil Shale Reserve near Anvil Points, Colo. Data and regression analysis curves are presented. Data obtained above the Mahogany zone were used to estimate the potential zone of surface effects from under-ground mining. Single specimen testing was primarily used to obtain Mohr's envelope and subsequent rock properties. The technique is shown to provide satisfactory results for this rock type with a significant reduction of core preparation and testing time.

Jan 1, 1981

By P. T. Carter, A. B. Murad, H. B. Bell

The distribution of manganese and oxygen between molten iron and FeO-MnO-SiO2 slags not saturated with SiO2 has been determined and used to calculate activities of MnO and SiO2 in MnO-SiO2 slags. These were found to be intermediate between the corresponding activities in FeO-SiO2 and CaO-SiO2 slags. THE equilibrium constant for the reaction between molten iron containing manganese and slags containing FeO and MnO, namely: FeO(slag) + Mn = MnO (slag) + Fe(1iquid) is most conveniently represented by: (MnO) Kmn== (FeOHMn] [Fe] is omitted, since for dilute solutions of manganese in iron, afe is approximately constant. When activities are used for (MnO), (FeO) and [Mn], Kmn is a true equilibrium constant and will apply to all types of slags, but when weight percentages are used, the values obtained for Kmn for different slags vary considerably. The equilibrium between iron containing manganese and relatively pure FeO-MnO slags has been investigated by several workers;1-4 the most recent investigation reported is that of Chipman, Gero, and Winkler.4 Their results, corresponding to slags containing up to 4 pct SiO2, were represented by the equation: 6440 log KMn = +2.95 In this case both slag and metal may be assumed to be ideal solutions, therefore the values of Kmn so derived represent the true constant for the manganese reaction. As the molecular weights of MnO and FeO are almost equal, weight concentration of these oxides may also be used in the above expression. Acidic oxides such as SiO2 and P2O5 affect the activities of FeO and MnO differently, so that when total concentrations by weight of FeO and MnO are used in the above expression for Kmn the values obtained are no longer constant. These will be denoted by K'mn. Körber and Oelsen5 investigated the manganese reaction using silica-saturated iron-manganese-silicate slags and found: 7940 logK'mn =3.172 This corresponds to Kmn values much higher than those obtained for pure oxide slags. The results of Körber and Oelsen, and Chipman, Gero, and Winkler are summarized in Table I. In the present investigation it was decided to study the manganese reaction using iron-manganese-silicate slags not saturated with silica, and which fell mainly between the orthosilicate join 2FeO . SiO2 - 2MnO.SiO2 and the FeO-MnO side of the ternary system FeO-MnO-SiO2. It has been shown" that the phases present in solidified slags of this part of the diagram are (FeO, MnO) and (2Fe0.Si02, 2Mn0-SiO,) solid solutions. Such an investigation would be of interest in deoxidation and also gives information on activities in liquid slags. This equilibrium has not as yet been investigated successfully. Hilty and Crafts7 attempted to examine this reaction in a rotating crucible furnace, but were unable to obtain suitable slag samples. In the present investigation one series of experiments was carried out in a rotating crucible furnace, because the success of Taylor and Chipman8 with such a furnace in their study of oxygen distribution between molten iron and (CaO, MgO) — FeO-Si0, slags suggested that it would minimize contamination of the slag by the crucible material. A second series was carried out using a wire-wound resistance furnace. Rotating Crucible Furnace Experiments In all cases the metallic charge consisted of 800 to 1000 g Armco iron containing 0.02 pct C, 0.03 pct Mn, and traces of Si. Manganese and silicon additions consisted of electrolytic manganese (99.9 pct)

Jan 1, 1953

By Verne E. Hooker

Stress-relief techniques and instrumentation have been developed through many years of research in the Federal Bureau of Mines and successfully used to determine the in situ state of stress in rock. This paper describes the drilling equipment and accessories for use with the Federal Bureau of Mines three-component deformation borehole gage. Operation and calibration procedures for the deformation gage are discussed in detail. Site selection and overcoring procedures are included to provide a complete working knowledge for surface or underground applications.

Jan 1, 1974

By Eric R. Borys, Amaneh E. Kenarsari, Brett Gitskin

This case study discusses impacts of excessive Earth Retention System (ERS) lateral movement at a project in city of Chicago. The ERS (cantilevered sheeting) moved inward towards the excavation and caused lateral displacement and cracks in six drilled shafts located about 1 to 2 lateral feet (0.3 to 0.6 m) from the face of the sheet pile wall. Up to 9 inches (23 cm) of horizontal movement was observed on top of the supporting sheet-pile. Similarly, survey measurements showed the top of the drilled shafts moved laterally up to 8 inches (20.3 cm). To evaluate the cause of failure and determine a remediation solution, the soil, shaft and site conditions were investigated. Pile Integrity Tests (PIT) were conducted at the affected drilled shafts. The shafts with identified anomalies were cored and video-recorded. The cause of the failure was determined to be related to variable soil conditions across the site, deeper excavation (i.e., increased effective ERS wall height), and other differences between design and as-built conditions. Internal bracing, in the form of walers and rakers, was installed to limit further movement of the sheet pile as a short-term solution, with additional grade beams framed into the basement slab-on-grade as a long- term solution. Five of the six cracked shafts were spliced with reinforcing bars and high strength grout and one shaft was replaced. INTRODUCTION The subsoil in the Chicago Area mostly consists of glacial till clays underlain by water-bearing granular soil over bedrock. The glacial clays have very soft to medium consistencies for a typical thickness of 30 to 50 feet (9.1 to 15.2 m) below which hard clays (Hardpan, i.e., heavily over-consolidated clay soils) are encountered. The soft clays are often referred to as the “Chicago Blue Clay”. Beach Sands are also found above upper soft clays in several areas, especially within a three-mile strip near Lake Michigan (Peck and Reed 1954). Due to the existence of soft clay in Chicago area, supporting the mid to high rise buildings on drilled shafts extended to Hardpan is a common practice in modern building design. In the early 19th century it used to take about 3 weeks to excavate 1 shaft hole and about 1½ days to fill the shaft with concrete in Chicago (Manierre 1916). The early 19th century methodology of excavating a shaft consisted of hand digging the shaft, installing wood lagging as temporary shoring with spoils removed with a rope and pulley system from the surface. Today, the excavation of a typical drilled shaft in Chicago uses heavy drilling equipment and requires much less time for excavation and concrete placement. It is not uncommon for contractors to excavate shafts and place concrete at a rate of about 2 to 5 drilled shafts per day (with one drill rig).

Jan 1, 2018

During the past Two years in reef gold mining, "indicators" have received great attention at the hands at the Victorian gold seekers. Many years ago, what was caned the" indicator lode," was struck in Ballarat East, on the course of which extremely rich deposits of gold were discovered but as to its being a .qeneral experience in reefs or leaders no one ever dreamed. Now, however, we find that these "indicators" are frequently to be met with, though they differ very much in different localities, making it, therefore, a difficult matter for other than a careful minel' to follow them. The necessity of following "indicators" for the purpose of developing gold is now recognized, and the policy of following them up has been attended with much success in this field. In the case of Messrs Shaw and Sons, at Wedderburn, those gentlemen began to work on an "indicator" here five years ago, and immediately thereafter more by accident than anything else they being at that time inexperienced as regards "indicators " came upon gold bearing quartz, which continued payable so long as the" indicator" aud the stone were in conjunction with each other, but as soon as they parted company the stone ceasedto be of any value then, by following the" indicator," as the latter intersected fresh bodies of stone they proved again more or less payable, until a fortnight or so ago the Messrs. Shaw turned out 4 tons of stone, which yielded £1,825, with also profitable workingup to the present moment. Where they are now working is a mile north of their original find thus proving that "indicators" travel considerable distances and have something to do with the gold deposits found in reefs. On the direct course of Shaw's "indicator," as high as hundreds of ozs to the ton was obtained from the stone but, just a few inches from either side in the same" leader," not a colour could be got. Whatever the cause-whether by electricity or some unknown force in nature-the gold is found on the course of these" indicators" and nowhere else, and-as each of the Victorian Government Geologists admit-their value to the gold-seeker as a means of leading to' gold cannot be over-estimated.

By Y Cai, B Hebblewhite

In this paper, the Australian thick coal seam underground mining potential is highlighted and the characteristics are investigated by analysing a thick seam database. It is clear that thick coal seam resources should be mined with a high recovery, productive, efficient as well as a safe and reliable mining method. Longwall Top-Coal Caving (LTCC) is the most recent thick coal seam mining method which has been developed and extensively used in China for the last ten years. The successful applications indicate that this method has a very high recovery and productivity rate and less development cost in comparison with any other thick coal seam mining method. One of the aims of the current study is to seek potential for the application of LTCC as a thick seam mining method in Australia. In this paper, preliminary results of investigation on Australian thickseam potential are given and results of data analysis for potential LTCC seams in Australia are described. The outcome of this study shows a great promise for the application of LTCC in Australian coal industry.

Jan 1, 2002

By Douglas E. Pollock

Recent NIOSH published information has shown an increase of rapidly progressive coal workers? pneumoconiosis (CWP) in the southern Appalachian coal region (SAR) of the U.S., despite the fact that compliance data indicates that most coal miners have been exposed to coal mine dust concentrations below the statutory limit of 2 mg/m³. While the exact cause of these elevated CWP levels in the SAR has not been established, several factors may be contributing to the increase in occupational lung disease among coal miners. The mining of high rank coal is known to lead to higher CWP rates, and this type of coal is mined in a portion of this region. Also, a high percentage of the mines in the region are on reduced dust standards because of the high silica content of the airborne dust resulting in miners possibly being exposed to excessive amounts of respirable silica dust. Exposure to excessive amounts of respirable silica dust can lead to silicosis, a disabling and potentially fatal lung disease. NIOSH?s Respiratory Hazards Control Branch has been investigating the possible causes that would account for the observed higher trends in disease progression through literature review, data analysis and in-mine surveying. The investigation to date has revealed that underground mines are faced with cutting large amounts of rock in order to maintain haulage clearances. Cutting rock not only increases the potential for silica exposure, it increases the requirement for machine maintenance, which was a concern observed during dust surveys conducted by NIOSH. Over half of the mines operating in the SAR are on reduced standards due to high silica content. Adequate face ventilation of the continuous miner and roof bolter and limited down-wind operations from the miner are also issues of concern and items that require the constant attention of miners operating in these conditions.

Jan 2, 2010

By Robert Hopler

A blast caused the destruction of a bridge and loaded freight train and the death of three men, near Chattanooga, Tenn., on May 16, 1907. The blast and its disastrous effect has been described by Mr. Hunter McDonald, M. Am. Soc. C. E., in a paper read before the Engineering Association of the South and reprinted in the Proceedings of the Association for April-June, 1907. The excessive damage was so largely due to coincidence and wreckage of the bridge and train so complete that the incident is worthy of notice.

Jan 1, 2008

By Nobuaki Sato

The electrical conductivity, k, of pure and sodium doped sulfur melts was measured with and without ultrasonic waves at temperatures ranging from 140 to 340'C by the two probe method using an ultra high resistance meter. The k value of the pure sulfur melt with irradiation jumped at around 170°C by an order of 102 after which it mouutuniocally increased from 10-5 to10-4 A' 1 cm-1 with an increase of the temperature. The addition of the sodium metal to the sulfur melt was found to cause a larger jumping in the K value. The k value increased with the increase of Na proportion in the melt. For a 10mol% Na doped sulfur melt it was as high as max ~30 A 1cm -1 above 180 C under the irradiation of of ultrasconics.

Jan 1, 2003

By D. Eastick, S. Hardcastle

"Over the last few years, a multi-faceted feasibility study has been evaluating the introduction of hydrogen fuel cell-powered equipment into underground mines to replaced diesel engine-powered equipment. The analysis has shown that under normal operating conditions fuel cells could at the very least be an environmental and health benefit by eliminating combustion engines and their unwanted by-products. However, they could also generate significant reductions in the amount of ventilation a mine needs to supply when compared to dieselized operations; this would further decrease a mine’s energy consumption, its associated greenhouse gas impact, and also reduce a mine’s significant ventilation-associated costs. Fuel cell-powered equipment also has the advantage of lower noise and heat production compared to its equivalent diesel-powered counterpart.The degree to which fuel cells can generate ventilation benefits in underground mines depends upon a number of operational parameters and mine specific qualifiers such as current ventilation control or management, mine depth, inherent dust conditions, and minimum velocity requirements.However, another major consideration in the introduction of fuel cells in underground mines will be the safety requirements associated with diluting and removing the potentially explosive hydrogen in the event of a gas leak. In outside surface applications, it is possible to use dispersion, buoyancy, time, and lack of ignition sources as mitigating factors in deriving a low risk of an explosion. However, in underground operations, these factors change, and dispersion and buoyancy are limited; time may not be available and, in non-coal mines, ignition sources are not typically controlled. When a hydrogen leak occurs, the availability of sufficient ventilation to dilute and effectively remove the gas will be critical. Consequently, ventilation may be the prime risk controlling factor. In this paper, the authors evaluate the potential benefits of replacing diesel engines with fuel cells in powered production equipment, discuss the mitigating qualifiers that could limit ventilation savings, and evaluate solutions to retain and maintain an additional ventilation capacity in the event of an emergency situation, such as a hydrogen leak from the fuel cell stack or its distribution system."

Jan 1, 2007

By John B. Hastings

THE origin of the watery vapors of vulcanism has always been an object of interest and speculation to the seismologist, and as theories of the genetic origin of ore-deposits have of late years been pretty well narrowed down to the expiring forces of plutonic action, the same question has had a lively interest for mining engineers and geologists, as is well shown by the discussions of the subject in our Transactions. The important part taken by volcanic emanations in the origin of pegmatites and quartz-veins, described in my paper, Origin of Pegmatite,1 and their latent power to concentrate into useful deposits such scattered gold as occurs in the Hartsel granite, make a discussion of their derivation but a natural third and final step. It is conceded that enormous amounts of vapor accompany volcanism, though perhaps we are apt to forget that steam has 1,700 times the volume of water, besides which the column seen over Vesuvius and other volcanoes is greatly mixed with air; the immensity of such volumes compared with solids and liquids is shown by the experiment of Gautier, who, by heating dessicated granite to 100° C., evolved from it uses 20 times, and steam 90 times, its own volume. Dana appraised the average amount of water left in ordinary rocks as 2.5 per cent. T. M. Read estimated that the Mississippi river carries to the sea annually 150,000,000 tons of rock material. If these Mississippi sediments, as deposited, contained 20 per cent. of water, it would be 600,000,000 cu. ft., or 4,500,000,000 American gallons, annually. Allowing the vapor suspended over a volcanic cone to be mixed with 80 per cent. of air, this amount of water converted into steam would replenish anew, every 9 min., a column 15,000 ft. high, 2,000 ft. in diameter at the base, and 10,000 ft. at the top. Read's estimate is only half of the amount given in a more recent and probably correct one .2

Jan 5, 1908

By H. Warren Newcomen

Assessments of the stability performance of open pit highwalls have traditionally been based on consideration of surface movement rates. Although generally accepted in industry, this approach presents challenges for establishing appropriate threshold values to allow for safe mining operations and does not address the issue of total strain. Surface movement monitoring data from a limited number of open pit mining operations in North and South America has been evaluated in terms of highwall strain, rock mass quality and inferred mechanism of instability. Threshold strain levels for key stages of highwall stability proposed from previous work have been reviewed and are generally endorsed based on evaluation of additional data. An empirical highwall strain criteria for the assessment of highwall stability performance is postulated based on the observed trends in highwall strain data from the case histories presented.

May 1, 2004

By N. A. D. Parlee, I. D. Shah

The solubilities of oxygen in liquid Ag-Au, Ag-Pt, and Ag-Pd alloys have been determined in the range of 940° to 1200°C at 1 atm pressure of oxygen using an improved Sieverts technique. The additions of gold (0 to 57 pct), platinum (0 to 27 pct), and palladium (0 to 22 pct) to liquid silver continuously decrease the solubility of oxygen in liquid silver. Activity coefficients and interaction coefficients of oxygen in these alloys and have been calculated. The interaction coefficientscan be described by the following equations: Approximate second-order interaction coefficients (pM have been calculated. The contribution of the product, pMxNM, to In yo only becomes significant at high alloy concentrations. RECENTLY several investigators1"3 have redeter-mined the solubility of oxygen in liquid silver. In general the recent findings1" for Po, = 1 atm are in good agreement with the equation:4 log %O = 695.4/T + 1.086 [1] It is established1, 2 that the solubility of oxygen follows Sieverts' law reasonably well, at least up to 1 atm partial pressure of oxygen. It should be noted that a very slight deviation from Sieverts' law has been reported by Lupis and Elliott.3 Only recently has the solubility of oxygen in Ag-X binary liquid systems received much attention, and only the Ag-Cu, Ag-Au, Ag-Pt, and Ag-Pd systems have been studied. Par lee, Sacris, and zoellners reported that the solubility of oxygen in liquid silver increases progressively with the small additions of copper (0 to 0.5 pct) up to the point where the copper oxide phase appears. Lupis and ~lliott~ have reported that the solubilities of oxygen in liquid silver decrease progressively with the additions of gold, platinum, and palladium. However, their investigation was limited to 0 to 5 pct of these alloying elements, a range too limited to satisfy the requirements of the research program of this laboratory, where the solubilities of oxygen in the range of 0 to 30 pct were required for the calculation of chemical diffusion coefficients of oxygen in these alloys. The present paper deals only with the solubilities of oxygen in these alloys while another paper will deal with the diffusion of oxygen in these alloys. EXPERIMENTAL METHOD A Sieverts technique was employed which involved an improved design of the reaction tube, Fig. 1, as described briefly in a previous communication.4 Liquid melts (70 to 100 g) were held in Norton Alun-dum crucibles. The induction furnace used had a maximum output of 2.5 kw with very fine control. This induction system had excellent stability and the final equilibrium temperatures measured by calibrated Pt-Pt, 10 pct Rh thermocouples are believed to be within ±2C. These thermocouples were checked against the melting point of pure gold wire, and the results agreed with standard tables (±l°C). Each run involved a careful sequence of operations. The sample was heated to and held at about 900°C in vacuum for 3 to 4 hr with the thermocouple in a retracted position. After melting, the melts were usually exposed to a small amount of oxygen (0.5 to 2.0 cu cm) and then degassed slowly for 1 to 2 min to remove any oxidizable volatile impurities such as carbon and sulfur as CO, CO2, SO2, and SO forth. Argon gas was then allowed to enter the system. The protection tube containing the thermocouple was then

Jan 1, 1969

By Aner W. Erickson

"Preliminary examination of tungsten deposits on the Mountain View property near Hyder, Alaska, was made by Neal M. Muir, an engineer of the Bureau of Mines daring the summer of 1942. Fifteen samples were cut, rough esti¬mates of ore reserves were made, and it was proposed to extend the drift on scheelite-bearing vein 300 feet in a northwesterly direction.From May 22 to October 24, 1944, an exploratory project was conducted on the property by the Bureau. In the course of this work, the camp buildings were rehabilitated; the dam, hydraulic line, and machinery were repaired; 226 feet of drift was driven; 80 groove samples aggregating 3.9 tons in weight were cut; a 6,000-foot surface and underground traverse was run; and the area was mapped in detail.In its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to the national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. R. S. Dean, assistant director.Special acknowledgment is doe Neal W. Muir, project engineer, and Robert S. Sanford, acting chief, Alaska Division, Mining Branch, for their supervision of the field work and revision of the report.Acknowledgment is also made to Silbak Premier, Ltd., for rendering valuable assistance in the repair of equipment and for extending various courtesies to Bureau of Mines personnel during the conduct of this project.The Mountain View property is located at latitude 55° 59' north, and longitude 130° 03' west in the Salmon River mining district of southeastern Alaska, about 5 miles in a northwesterly direction from the town of Hyder, which lies at the head of Portland Canal, as shown in figures 1 and 2. Vein outcrops and surface workings are at an elevation of 950 feet and occupy the west flank of a low ridge between Skookum and Fish Creeks, as shown in figure 3. The portal of the long adit exposing the vein at depth is on Skookum Creek about 550 feet north of the confluence of Skookum and Fish Creeks.Access to the property is over a 4-foot wide trail built and maintained by the United States Forest Service. This trail is suitable for pack animals and is adequate for transportation of supplies and material for exploratory work. During the periods of camp construction and past exploratory operations a 4,000-foot, single-cable, aerial tramway, now in disrepair, served for transportation of materials and all machinery from the Salmon River Highway to the property. The cost of such hauling was high, amounting to $12 a ton. Topography is suitable for construction of a ""cat road"" 2 miles in length, connecting the property with the Salmon River Highway. It is estimated that such a road could be built for $5,000 a mile, and supplies, machinery, and concentrates could be haled over it at a cost of less than $2.50 a ton."

Sep 1, 1946

By William R. Bond, Jim V. Rouse

Introduction The pressure/vacuum (p/v) lysimeter or soil water sampler has become useful for monitoring vadose zone or unsaturated zone water conditions. The soil water sampler was first introduced around 1961. It was used as a monitoring and research device for studies in agriculture and soil contamination around landfills. Since then, it has been used for many purposes. The use of p/v lysimeters at mining facilities to monitor for solution loss is a relatively new idea. The primary purpose of the lysimeter here is to function as an early warning system. It detects leakage through liners of tailings ponds, heap leach pads, and leachate holding ponds. Their use has proven valuable for collecting baseline data and detecting loss of precious leachate fluid. Different lysimeter designs are capable of vadose moisture sampling from near the surface and down to 90 m (300 ft). They are also capable of sampling soil moisture or saturation plume contaminants from areas not accessible by conventional water well installations. The most common installations are usually simple and cost-effective. In many cases, they can be installed without the use of heavy drilling equipment. A properly placed and installed lysimeter can detect solution leaks in several days or weeks. A conventional perimeter monitor well may take months or years to detect a leak of the same magnitude. A discussion on the general design and installation of p/v lysimeters will give an understanding of its versatility. Three case studies of lysimeter installations at mining sites will be examined in detail. Design, Installation, and Sampling Design The basic design of a p/v lysimeter chamber consists of a porous material through which the soil is drawn into a collection chamber. Access tubes run from the unit to the sample station at the ground surface. Most units currently available range from 25 to 76 mm-diam (1 to 3 in.-diam). The sample collection chamber, or body, can vary from 0.6 to 1.8 m (2 to 6 ft) in length. The body can be constructed of PVC casing or Teflon, depending on the installation desired. The collection chamber functions as a holding reservoir for the collected soil moisture. The intake, or porous material, on the lysimeter is the most complex and vulnerable portion of the unit. The pore size selection varies based on the needs of the installation, type of fluid to be sampled, and type of soil material surrounding the unit. Teflon (PTFE) and porous ceramic are used in fabrication of the porous inlet portion. When using a Teflon material, which is hydrophobic, a larger pore size of 70 µm is needed to overcome surface tension and draw water into the collection chamber. It is typically used at sites involving organic contamination, because of its inert properties. Ceramic material is generally hydrophilic, having less surface tension. Therefore, it has a smaller porosity range to conduct the moisture through the porous medium while under vacuum. Pore sizes may be selected from 0.16 to 6 µm, and can be manufactured for the specific needs of the installation. The final major design component of the p/v lysimeter is the access or sampling tubes. The tubes are usually of 6.3-mm-outside-diam. (0.25-in.-outside-diam). They are made of rigid polyethylene or flexible Tygon with a wall thickness of 1.5 mm (0.06 in.). The con-

Jan 4, 1985

By T. J. Woodside

A. E. LEE*—One question of the flue leading to the tube coolers. What gas velocity is maintained to prevent settling of the finely divided fume ? T. J. WOODSIDE (author's reply)— 30 fps. Of course some fume settles out, but is immediately carried away by the screw conveyors. H. R. BIANCO —How effective are the soot blowers ? Do you have to use any hand lancing? T. J. WOODSIDE Only one point, which is right at the top of the economizer and which the soot blowers do not reach, we occasionally hand lance. But everywhere else the soot blowers have been very effective and no hand lancing has been done. L. V. DAVIDSON*—Do you have considerable variation in the lead content of the fume collected if the lead is higher, and is there greater tendency for the fume to stick on the boiler tubes ? T. J. WOODSIDE—There is very little variation in the lead content. From 5 to 7 pct is the widest range variation we have had and we have noticed no difference in the behavior of the fume. C. R. KUZELL—Mr. Woodside has been quite generous with data pertaining to metal and fuel economics. I think he stated that the coal consumption of the furnace was 21/10 21/10 for a pound of zinc recovered. I take it that that is the gross coal input to the furnace. I wonder what the net fuel consumption in terms of coal might be after crediting the fuel equivalent of the waste heat steam recovered? T. J. WOODSIDE—The fuel value of the waste heat steam is approximately 42 pct of the heat input to the furnace. A very large part of the heat, of course, goes out in jacket water—44 pct. A. D. TERRELL*—I would like to know how much lead is in the deleaded material. T. J. WOODSIDE—It is a little less than 2 pct now.

Jan 1, 1950

By D. Grgic, A. Giraud, F. Homand

RESUME : Le comportement mécanique partiellement saturé du minerai de fer a été étudié à partir d’essais de compression simple sur des éprouvettes à pression capillaire imposée par les solutions salines. Les échantillons restent peu saturés (32 %) même pour une humidité relative de 94 %, du fait de la présence de mésopores. Jusqu’à 90 % d’humidité relative la résistance diminue régulièrement. De 90 % à 94 % une forte chute est observée et pourrait être liée à la fois aux effets capillaires et à l’hydratation de certains minéraux. Le cycle hydrique subit par la roche dans la mine a été modélisé en 1D à l’aide d’un code de calcul entièrement couplé pour les milieux poreux partiellement saturés. Les calculs ont montré notamment une diminution importante en paroi des contraintes totales au cours de la phase de désaturation et une augmentation importante au cours de la phase de resaturation. Ces variations pourraient induire un endommagement du massif et être à l’origine d’instabilités, et soulignent l’intérêt d’une modélisation avec une géométrie plus adaptée. MOTS-CLEFS : mines de fer, partiellement saturé, pression capillaire, résistance, modélisation. ABSTRACT : The partially saturated mechanical behavior of iron ore has been studied from uniaxial compression tests on samples in which the suction is imposed with aqueous solutions. Samples are little saturated (32 %) even for a 94 % relative humidity because pores are too large. Up to 90 % relative humidity the strength decreases regularly. From 90 % to 94 % a great decrease is observed ; it could be explained by the capillary effects and the moisturizing of some minerals. The hydrous cycle imposed to the rocks in the mine has been modeled with an 1D fully coupled code for partially saturated porous media. The computations have shown an important decrease in the total stresses at the wall during the desaturation stage and an important increase during the re-saturation stage. These variations could induce a rock mass damage and instabilities, and highlight the necessity of a modeling with a well-adapted geometry. KEY-WORDS : iron mines, partially saturated, suction, strength, modeling. ZUSAMMENFASSUNG : Das mechanische Verhalten von teilweise gesättigten Eisenerz wird durch einachsige Druckversuche untergesucht. Die Prüfkörper haben einen durch Salzlösungen gestimmten kapillarischen Druck. Sie bleiben kaum gesättigt (32 %), sogar bei einer relativen Feuchtigkeit von 94 %, aufgrund der Anwesenheit von Mesoporen. Bis eine relative Feuchtigkeit von 90 % verringert sich gleichmässig die Druckfestigkeit und zwischen 90 % und 94 % merkt man eine starke Abnahme in Verbindung, möglicherweise, mit kapillarischen Effekten und Hydratation von bestimmten Mineralen. Die nümerische 1D Modellisierung des gezwungenen Wasserzyklus im Stein der Mine ist mit einem für porösen Medien ganz vernetzten Rechnungcode geführt. Sie zeigt besonders ein bedeutendes Sinken der Gesamtspannung während der Entwässerung und eine bedeutende Steigerung während der Sättigung. Diese Veränderungen könnten die Beschädigung des Gesteines herbeiführen und die Grundlage von Unstabilität sein. Sie unterstreichen die Wichtigkeit eine Modellisierung mit einer gut geeigneten Geometrie. STICHWÖRTER : Eisenminen, teilweise gesättigt, kapillarischer Druck, Druckfestigkeit, Modellisierung.

Jan 1, 2003

By Thomas C. Shapiro

Introduction In recent years - even months - the number of articles on computers has increased rapidly. One can hardly pick up a newspaper or magazine without seeing a computer-related article. The article usually explains how the computer will change our lives. Many of us have some concern about the nature and type of change. For most of us, though, the problem is lack of information and understanding about how computers work. In other words, how do we make cost-effective decisions about computers? This three-part series will explain, simply, what a microcomputer is, how it works, and how to decide if you need one. This first article will define terms and briefly discuss areas where computerization might be economic. The second article will discuss geology and mining applications. The third article will discuss plant, administrative, and geotechnical areas as well as the future of software development in the minerals industry. Terms and Concepts All computers have input and output devices and a central processing unit (CPU). Information - instructions and data - is communicated to the computer by means of input devices. These instructions to the computer are converted into language that the computer understands. This causes the instructions to be carried out in the CPU. The result of these operations is translated back into language that we understand. This information is then sent to output devices such as printers and video display tubes. Traditionally, peripherals were devices separate from the main-frame (the CPU and memory) and were used to input, output, and store information or instructions. Today, peripherals perform the same functions though they may be housed in the same cabinet as the CPU and memory. Historically, peripherals included all input and output devices not part of the mainframe. Input devices include keyboards, magnetic tape, and card readers. Tapes and disks are input as well as output devices. Output devices are printers, CRTs (Cathode Ray Tubes), and any mass storage device capable of storing data when directed to do so by the computer or the program. In fact, any mass storage device that can give the computer data when requested is an input device. Mass storage devices include floppy disks (thin, round sheets of plastic covered by metal particles), and hard disks. The latter are thicker and more densely coated with metal particles. This allows much more information to be stored. Another type of mass storage is magnetic tape. Its type and size varies widely. Processing and Storage Any computer understanding must include how instructions and data are processed and stored. Information is stored as a positive or a negative field known as a "bit." There are eight bits in a byte. The bits can be represented as either a one or a zero. Thus the code for a byte representing the numeral one is 00110001. The byte representing the letter A is 01000001. These codes are from the American Standard Code for Information Interchange (ASCII). ASCII defines the standard set of characters including alpha, numeric, and special characters. The computer's memory has allocated locations where instructions as well as incoming information can be stored. All information and instructions are stored as binary numbers bit by bit - zeros and ones. The amount of data that can be stored is referred to as either thousands or millions of bits or bytes. The letter "K" is used to designate one thousand units. The letter "M" is used to mean one millon units (one meg). Disks Thus, a 113-mm (5 1/4-in.) floppy disk - double sided and double density (DSDD) - contains 320,000 bytes (characters) or 320K. This is about 164 double-spaced, type-

Jan 2, 1984