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By W. R. Reed

The National Institute for Occupational Safety and Health (NIOSH) uses light-scattering dust monitors (nephelometers) in its research to develop dust controls to reduce respirable silica dust overexposures in miners. Recently, the model 1500-pDR, an active nephelometer, was introduced by Thermo Scientific. Testing was completed to ensure compatibility with the metal/nonmetal mine dust personal sampling unit (M/NMDPSU). Results of testing demonstrated that gravimetric concentrations measured from the 1500-pDR are comparable to the gravimetric concentrations measured using the M/NMDPSU, without need for correction, under commonly observed dust loading conditions.

Jan 1, 2012

By Donna lynne Anderson

This report documents the status of a laser-based underground guidance system for tracking and controlling the movements of underground mobile mining equipment. This research is part of a multiple project effort at the U.S. Bureau of Mines to increase mine safety and efficiency by developing technology for computer-assisted mining. Guidance systems, which can track and control the movements of underground mining equipment, are essential during computer-assisted mining operations. A continuous mining machine at the Bureau's surface test facility served as the test-bed for initial development and experimentation of this guidance system. Subsequently, a continuous mining machine in an underground mine served as the platform for in-mine experimentation The first section of this report includes details of the laser sensors, communication network, and computer hardware. The next section includes experimental results, which show the system capable of accurately tracking and controlling the tram maneuvers of a continuous miner underground. The final section discusses conclusions and recommendations.

Jan 1, 1992

By Fábio de Oliveira Braga

Atualmente, tecidos de fibras sintéticas como a aramida (Kevlar®) e o polietileno (Dyneema®) têm sido os preferidos para proteção balística contra munições leves, e para integrar sistemas de proteção contra calibres superiores, como o 7,62 mm. Porém, por apelos econômicos, ambientais e da disponibilidade limitada destes produtos, materiais alternativos têm sido testados. Neste cenário, destacam-se os compósitos reforçados com fibras naturais, que têm demonstrado bom desempenho balístico. Assim, o objetivo deste trabalho é avaliar o desempenho individual de compósitos reforçados com fibras naturais de curauá, quando submetidos ao impacto balístico com munição 7,62 mm. Foram executados ensaios balísticos, medindo-se a energia do projétil absorvida pelos materais, e os resultados tratados estatisticamente por Anova e teste de Tukey. Mostrou-se que estes compósitos têm potencial para substituir as fibras sintéticas em sistemas de blindagem para proteção pessoal, com a vantagem de serem materiais leves, de baixo custo, nacionais, de ampla disponibilidade e ambientalmente corretos.

Aug 17, 2017

By Byron M. Bird, Earl R. McMillan

"The method and apparatus described herein was developed at the Northwest experiment station of the Bureau of Mines, Interior Department, in cooperative research work with the University of Washington. A fuller description will appear in a bulletin entitled ""study of coal washing problems in the Pacific Northwest, to be published by the University. During the past four years this Bureau and the University have been co-operating with various coal companies in the Pacific Northwest in an extensive study of coal washing problems. Much of the valuable data resulting from this study has been obtained with the well-known float-and-sink test. This test has known for a number of years****, but its possibilities have not been thoroughly understood. A few investigations have developed apparatus and technique suitable to their needs, but these were not adopted to the conditions faced in the Northwest. Thus, the necessity arose for designing suitably equipment and working out a method of procedure or technique in carrying on the fundamental studies of coal washing by means of the float-and-sink test method."

Feb 1, 1924

By K Palmer, G J. Artmont

Alluvial gold is an ideal exploration tracer to bedrock source and indicator of bedrock mineralisation style because: (i) gold occurs in a wide range of deposit types, (ii) primary composition is sensitive to style of mineralisation, and (iii) it is a heavy resistate mineral that is readily preserved and easily sampled. In regional exploration of the Central Ranges of Irian Jaya, alluvial gold mineralogy has been applied to maximise the information return from panned concentrate sampling and to focus exploration effort. Primary gold is a solid solution of Au+Ag¦Cu¦Hg, ¦ trace Pd, Te, and Sb. In general Ag¦Hg increase and Cu decreases with inferred decreasing temperature of formation, and gold from particular mineralisation styles has signature compositions that can be used as indicators of bedrock mineralisation type. Furthermore, the abundance of alluvial gold is an indicator of the economic potential of a catchment. The convergent continental-oceanic plate geology of the Central Ranges is conducive to a wide range of mineralisation styles. Mineralogy of gold in ophiolite, skarn, porphyry, mesothermal vein and possible VHMS environments is characterised from alluvial and bedrock samples, and the use of gold mineralogy in prospecting at regional scale through prospect definition to drilling is demonstrated.

Jan 1, 1995

By W. R. Hardwick

This paper describing the mining methods of the Inspiration Consolidated Copper Co. is one of a series being prepared by the Bureau of Mines on mining methods and costs in various mining districts of the United States. The story of mining at Inspiration is of particular interest because, after 127,812,000 tons of low-grade copper ore were successfully mined, the mining method was changed from block caving to open-pit. As the open pit became deeper, many features of the former block-caving operation that were exposed elucidated concepts of the mechanics of caving that previously had been assumed but not observed. The conversion to open-pit mining was accomplished by unique combinations of equipment and the introduction of ingenious engineering and operating practices that have extended the expected life of the mine for many years.

Jan 1, 1963

By Rambabu Pothina, Rajive Ganguli

The economics of a mineral processing circuit is dependent on the numerous sensors that are critical to optimization and control systems. The sheer volume of sensors results in mines not being able to keep the sensors calibrated. When a sensor goes off calibration, it results in errors which can severely impact plant economics. Normally, these errors are not detected until the error grows and becomes a large (“gross”) error. Undetected errors are not remedied until the next calibration, which on average are a year apart Beamex (2019) [1] across all industries. Classical statistical methods that depend on linear relationships between input and response variables are typically used to find gross errors, but are not effective for highly non-linear and non-stationary operations in mining and mineral processing industries. Calibration of sensors is time-consuming and generally requires physical intervention that results in equipment downtimes causing production losses. Therefore, in situ detection methods are warranted that do not require physical removal of sensors to compare with standard measurements or well-calibrated sensors. Data-mining based techniques and algorithms have high success rate in tackling such problems. This paper presents results from a groundbreaking multi-year big data research project whose goal was to develop data-mining-based original techniques in a multi-sensor environment to identify when sensors start to stray, rather than wait for errors to grow. The carbon stripping (gold) circuit in the Pogo Mine of Alaska was selected for this project. Maintaining strip vessel temperatures at optimum levels is crucial for maximizing gold recoveries at Pogo, and hence the focus was on the temperature sensors of the two strip vessels. An automated algorithm to detect errors in strip vessel temperature sensors was developed that exploited data from multiple sensors in the strip circuit. This algorithm was able to detect with a high success rate when bias errors of magnitude as low as ± 2% were artificially induced into strip vessel temperature data streams. The detection times of about 1 month were much less than the industry average calibration frequency of 1 year. Thus, the algorithm helps detect errors early, without stopping the circuit. The algorithm alarms can serve as triggers when calibrations are done. Experimental methodology along with results, limitations of algorithms, and future research are also presented in this paper.

By Rambabu Pothina, Rajive Ganguli

The economics of a mineral processing circuit is dependent on the numerous sensors that are critical to optimization and control systems. The sheer volume of sensors results in mines not being able to keep the sensors calibrated. When a sensor goes off calibration, it results in errors which can severely impact plant economics. Normally, these errors are not detected until the error grows and becomes a large (“gross”) error. Undetected errors are not remedied until the next calibration, which on average are a year apart Beamex (2019) [1] across all industries. Classical statistical methods that depend on linear relationships between input and response variables are typically used to find gross errors, but are not effective for highly non-linear and non-stationary operations in mining and mineral processing industries. Calibration of sensors is time-consuming and generally requires physical intervention that results in equipment downtimes causing production losses. Therefore, in situ detection methods are warranted that do not require physical removal of sensors to compare with standard measurements or well-calibrated sensors. Data-mining based techniques and algorithms have high success rate in tackling such problems. This paper presents results from a groundbreaking multi-year big data research project whose goal was to develop data-mining-based original techniques in a multi-sensor environment to identify when sensors start to stray, rather than wait for errors to grow. The carbon stripping (gold) circuit in the Pogo Mine of Alaska was selected for this project. Maintaining strip vessel temperatures at optimum levels is crucial for maximizing gold recoveries at Pogo, and hence the focus was on the temperature sensors of the two strip vessels. An automated algorithm to detect errors in strip vessel temperature sensors was developed that exploited data from multiple sensors in the strip circuit. This algorithm was able to detect with a high success rate when bias errors of magnitude as low as ± 2% were artificially induced into strip vessel temperature data streams. The detection times of about 1 month were much less than the industry average calibration frequency of 1 year. Thus, the algorithm helps detect errors early, without stopping the circuit. The algorithm alarms can serve as triggers when calibrations are done. Experimental methodology along with results, limitations of algorithms, and future research are also presented in this paper.

By Ray L. Tobie, Douglas E. Julin

GENERAL DESCRIPTION Block caving is a distinct caving method applied mostly to large, massive, ore bodies because of its in¬herent low cost and high production capabilities. Areas of sufficient size are removed by undercutting so that the mass above will cave naturally. Drawing of the caved ore at the bottom of the ore column causes the caving action to continue upward until all of the ore above the undercut level is broken into sizes suitable for handling. When properly applied, block caving results in a lower mining cost per ton than any other under¬ground method. There are three distinct forms: (1) dividing the horizontal area into rectangular or preferably square or nearly square blocks, drawing evenly over the entire area to maintain an approximately horizontal plane of con¬tact between broken ore and caved capping; (2) divid¬ing the horizontal area into panels across the ore body, retreating by undercutting manageable areas from one end of the panel to the other and maintaining an in¬clined plane of contact between the broken ore and caved capping (thus the name panel caving); and (3) no division of horizontal area of the ore body into defi¬nite blocks or panels (this is termed mass caving). Undercutting may be from wall to wall, retreating from one end of the ore body to the other, maintaining an inclined plane of contact between the broken ore and caved capping. The total active caved area is deter¬mined by the size of block that will not produce undue stress on workings below the undercutting level and by total production requirements. This type of operation is also referred to as panel caving at some properties. SUITABLE ORE BODIES Block caving in its various forms is applicable to deposits of various shapes and ores of various strengths. Its success is governed by rigid requirements and limi¬tations. In unsuitable deposits or where improperly em¬ployed, the loss of ore may exceed that of any other mining method. Good planning, systematic work pro¬cedures, careful supervision, and good judgment con¬tribute to its success. Ore Characteristics Included as a necessary characteristic in an ore body suited to a successful block-caving operation is a proper fracture pattern. Ore hardness should be another gov¬erning factor, and the toughness or softness of the ore should be considered. There must be sufficient horizon¬tal area available for expansion of the undercut, if neces¬sary, to start the caving process. Large, massive, ore bodies usually meet these conditions. Veinlike deposits must be wide and dip rather steeply to conform to the block-caving limitations. The capping must be of such a nature as to cave when the underlying ore is being removed since the weight of the overburden aids in crushing the ore. The most favorable capping character¬istic is that it breaks into coarse pieces and resists attrition as the block is drawn. Soft capping, by breaking into fine pieces and sifting into the ore or channeling through the ore to the drawpoints, can seriously dilute the ore and hinder the extraction of clean ore from the blocks. Types of Ore In block caving, a fairly uniform distribution of val¬ues in the ore is necessary. Grade values may range from low grade to high grade, but most often the sys¬tem is applied to low-grade ores. Wide veins, thick beds, or massive deposits of homogeneous ore overlain by ground which will cave constitute suitable ore bodies. The ore must be such that it can be supported while blocks are being developed and undercut but breaks up readily when caved. Some applications include porphyry copper, disseminated molybdenite, hematite in the Lake Superior iron district, limonite deposits in northern Spain, the diamond mines of South Africa, asbestos and nickel in Canada, and massive magnetite in Pennsylvania. Size and Shape Outline of the ore body should be fairly regular, and the sides of the ore body should dip steeply. It may not be economical to mine small portions of ore extending into the walls of the deposit, and low-grade inclusions in the ore cannot be left unmined. Some dilution of the ore, as mining progresses, by low-grade or barren cap¬ping is inevitable and, unavoidably, some clean ore is left between drawpoints. Determining Cavability The use of rock mechanics is sometimes advantageous in helping to determine the cavability of an ore deposit. The US Bureau of Mines has information and testing ability which can assist in determining the cavability of ore types. Several competent consulting orga¬nizations knowledgeable in rock mechanics can also as¬sist in evaluating the cavability of an ore body. Some recent work has been done to better define the cavability index of various ore bodies; an example of how this was determined is discussed by McMahon and Kendrick (1969). The intensity of the fracture pattern is a critical parameter to be analyzed. The question to be answered is, "How intense must the fracture pattern be?" Table 1 is a tabulation of the size of rock fragments that appear at the drawpoint of various block-cave mines around the world. These are indicative of the fracture-pattern spac¬ing and, as can be seen, they vary substantially from the almost sandy material at the Mather mine to fairly sizable blocks at the Grace mine. Several sets of fractures are essential to promote good caving. Ideally, two vertical sets at nearly right angles to each other and a third set nearly horizontal are required to insure a good caving ore body. Since initial caving of an ore mass is almost always by the action of gravity acting on these planes of weakness, it is doubtful

Jan 1, 1982

By Otto Ruhl

The zinc-lead ore reserves of the Tri-State district of Kansas, Missouri, and Oklahoma, as of December 31, 1947, are estimated at a total of 66,100,000 tons of crude ore containing 2.18 percent metallic zinc and 0.38 percent metallic lead. The Bureau of Mines began estimating the reserves in October 1945 and completed the' work December 31, 1947. A total of 38,900 acres of land representing approximately 5 percent of the area of the district is covered in this report. The work was confined for the most part to properties developed or partly developed by drilling and underground workings, and to acreage sufficiently drilled out to indicate ore of enough tonnage to make a commercial undertaking. The acreage in which ore reserves exist is widely distributed in all three States. A map of the Tri-State area is shown in figure 1. The remaining 95 percent of the area is not necessarily nonproductive but represents, possibilities for future exploration and development of additional mineral resources when and if economic conditions or national necessity encourage such work. Of the total reserves, 41 percent are in Missouri, 38 percent in Kansas, and 21 percent in Oklahoma.

Jan 1, 1949

By David Hopkins, Steve Klein, Bradford Townsend, Ed Sum, Derek Penrice

INTRODUCTION The Transbay-Caltrain Downtown Extension (DTX) Project involves the construction of an approximately 1.5-mile rail line that will extend Caltrain commuter service and the future California High Speed Rail system into downtown San Francisco. The underground rail extension will be constructed by mined tunnel and cut-and-cover methods. Tunneling challenges include difficult ground conditions, low rock cover, the presence of historic buildings along the alignment, and the large tunnel span, ranging from approximately 50 to 65 feet. Three mined tunnel construction methods were evaluated: the Stacked Drift Method, the New Austrian Tunneling Method/Sequential Excavation Method (NATM/SEM), and Tunnel Boring Machines (TBM). This paper describes the challenges presented within the mined tunnel section, and summarizes the evaluation of tunneling methods that led to the selection of NATM/SEM. PROJECT OVERVIEW The existing Transbay Terminal opened in downtown San Francisco in 1939. This facility is antiquated, and does not meet current building seismic safety standards or the transportation needs of the Bay Area. For these reasons, San Francisco voters approved Proposition H in 1999, which proposed to construct a new or rebuilt regional transit center at the site of the existing terminal and extend Caltrain commuter rail ser-vice to the new transit center. The new transit center is the hub of the Transbay Transit Center (TTC) Program, which will greatly enhance regional transit service by providing connectivity for six Bay Area transit providers at one facility. The program will be the largest inter-modal centerwest of New York City. The TTC Program is comprised of two major projects, the Transit

Jan 1, 2007

By B. Xu

Keywords: Magnetic damping, g-jitter, Hot-film anemometry Results from an experimental study on natural convection induced by temperature gradient in molten gallium contained inside a rectangular container. The damping effect of the convective flow from an externally applied static magnetic field is investigated. Induced velocity and temperature fields are mapped using a standard constant temperature hot-film anemometry and a thermocouple with and without the applied magnetic field, respectively. Detailed experimental setup and procedure are depicted in the present paper. Obtained velocity and temperature profiles are examined against previous numerical simulations and reasonably good agreement has been achieved. Obvious damping effect can be observed in both the temperature and the velocity profiles when the external magnetic field presents.

Jan 1, 2005

YOUR Excellency, Fellow Members of the Australasian Institute of Mining Engineers and Gentlemen:-Nearly a decade has passed since our Institute first met in New Zealand. May I, at the very outset of this second gathering, congratulate the Institute on the great progress that has been made in the interval. At the first meeting in New Zealand in the year 1903, I understand that less than 20 persons were present, and now in the large concourse before me I believe there are not fewer than 140 persons, while if every member of the Institute to-day where here there would be over 500 with usagreat change from a membership of only 250 in 1903. I feel deeply appreciative of the honour you have conferred upon me by electing me your President for the year 1911. In return for the compliment, may I ask you to believe that I shall do everythingin my power to further the interests of the Institute throughout the coming year.It is a great regret to me to realise that soon my work in New Zealand will be over. However, I trust that the new...

Jan 1, 1912

By Peter Klaver

Deep tunnels have been used for decades for the temporary storage of large volumes of urban runoff, both storm water and combined sewer overflow (CSO). Tunnels are attractive because they reduce surface disruption and do double duty as storage and conveyance systems, collecting overflows from multiple locations and transporting them for treatment to various facilities. Like any hydraulic system, however, there are dynamic effects that must be fully understood during the design phase so that the final constructed product does not have unintended negative consequences. Preliminary sizing of storage tunnels is typically based on the total volume required. For example, if studies have determined that a volume of 56.8 ML (15 million gal) will provide the intended level of control, then that figure can be used, along with a preliminary idea of the desired tunnel length, to compute the required diameter. Of course, filling a long tube with water from various points along the way is not at all the same as pouring water into a bucket, and these dynamic effects require additional attention from design engineers. The rapid filling of storage tunnels can lead to the formation of bores, which are essentially moving walls of water. An open channel bore can build in height until it reaches the crown of the tunnel, at which point it becomes a pipe-filling bore. Figure 1 depicts both kinds of bores moving upwards in a rapidly filling tunnel. Bores can strike the ends of tun-nels with tremendous force, driving water and entrained air upwards into dropshafts and creating strong pressure surges in portions of the tunnel that are already filled. If the hydraulic surges are high enough to reach grade, they can cause overflows and/or damage structures at the surface. Trapped air pockets can occur through several phenomena, including the reflection of bores off dropshaft structures and the occurrence of ?premature pressurization.? The latter refers to the situation where the inflow to a tunnel is increasing more rapidly than the tunnel can convey it, such that the pipe becomes surcharged at an upstream point while points downstream are still flowing as an open channel. These air pockets are a great nuisance as they migrate toward points in the tunnel where they can rise to the surface, which are often shafts that are already filled with water (Fig. 2). The ?geyersing? that results can be hazardous and costly.

Jan 3, 2010

By Meyer Klein

Decision theory is the formal theory of the logic of decisions in view of the decision maker's objectives, preferences, I beliefs, and available information, It usually deals with weighty economic problems involving irrevocable (or costly to reverse) decisions. Capital investment planning problems constitute an instance par excellence for application of the decision theory concepts. Decision theory as it is presently conceived has evolved in recent years. At first it concentrated on decisions in the face of total lack of information and on games with intelligent adversaries. The results of these efforts proved theoretically interesting, but practically of little applicability. In the last few years, stress has shifted to the introduction of subjective probabilities and preferences, and the results have been eminently successful in applications both in government and with- in business firms in the resolution of complex problems.

Jan 1, 1970

By Karen C. Armfield, Gisele R. Passalacqua, Joanna Smith

When selecting a solution for improving resiliency at facilities, such as airports, utility and transit sites, there are many options to protect structures and equipment against potential flooding. Each case involves an evaluation of the several key factors such as: design flood parameters, the geography and geological conditions below the site, the facility, and the layout of buildings and equipment to be protected. Upon reviewing these conditions and conducting a cost analysis of various options, the most suitable approach to protecting a facility can be determined. This paper will compare the conditions at various New York City sites, and give detail to the solutions utilized at these sites to improve resiliency and protect each facility. Flood wall types varied as did the strategies for raising critical equipment, to meet the Federal Emergency Management Agency (FEMA) and American Society of Civil Engineers (ASCE) 7 guidelines. Due to granular soil conditions, some sites may experience soil seepage below the flood wall resulting in the need for underground cut off systems. The authors will also present detail regarding the solutions used to control seepage. Various cut off systems will be discussed such as grouting and sheeting, explaining the factors that may impact the choice of systems. Another consideration in flood resiliency is the potential for a buoyancy condition on basement slabs when localized flood barriers are employed on first floor doors and windows. The authors will discuss the potential impacts of this condition on facilities and methods to mitigate this issue. 1. INTRODUCTION New York City is an urban coastal Metropolis with varied geology and low land areas. This includes but is not limited to sandy soils at Coney Island and the John F. Kennedy Airport. Soft marshes are found near Flushing Queens and LaGuardia Airport. Heavy rains and coastal storms caused disruption to daily life and heavily affected the economy of this vibrant City. For instance, in lower Manhattan business was interrupted in the Financial District. Power outage was widespread; commuter trains and subways were stopped and put out of service. Additionally, numerous residential homes were damaged in Coastal Neighborhoods such as the Far Rockaways and Staten Island. 1.1. Superstorm Sandy Flood Statistics On October 29, 2012 Superstorm Sandy impacted numerous facilities in the New York City Metro area. The resulting damage cost New York City more than $42 billion in repair costs. $33 billion was allocated to repair housing and infrastructure, and $9 billion was allocated to protect transit systems1. One of the major issues that impacted the city in terms of its preparedness was the high flood surge. The surge surpassed the former base flood elevation and reached as high as 13.88 feet (above mean lower low water - MLLW) in Battery Park at 9:24pm that evening. Tottenville, Staten Island experienced more damage where the water was recorded at +16 (North America Vertical Datum of 1988 - NAVD88), which is equivalent to 18.7 feet above MLLW (see Fig. 1). Not only was the surge at record levels, the waves in New York Harbor were also at record level where some buoy stations recorded waves of up to 32.5 feet. The City released “A Stronger, More Resilient New York” in June 2013, a plan laid out to rebuild communities impacted by Sandy and improve the resiliency of the infrastructure and buildings in New York City. Figures below help to illustrate the extent of the inundation relative to the projects being discussed.

Jan 1, 2018

By G. L. Oldright

"The various districts in the United States where complex lead-zinc ores occur are too well known to require description, there being hardly a mining State with any large amount of ores of either metal that is free from this problem. This paper briefly presents developments in the volatilization process, as applied to the treatment of such ores, since the data in Bureau of Mines Bulletin 211** were published. In that bulletin, among the many types of ore treated, examples are given of the treatment of lead-zinc ores by the chloride volatilization process for the separation of lead. An outline of the general process, with views of the rotary kiln, ore feeder, firing system (these three features resemble closely those of cement-kiln practice), dust chambers, and a Cottrell precipitator to remove the fume from the gas, are also shown in that bulletin, to which the reader is referred for the results obtained, and for practical details of operation. The small initial cost of a volatilization plant, and its adaptability for use in isolated districts were emphasized.In general, it was found that when an intensely oxidizing atmosphere was maintained in the furnace, a good lead-zinc separation could be made. Therefore, a heavy sulphide ore would have to be preroasted, and enough air would have to be admitted to obtain complete combustion of whatever fuel might be used.The work done by private companies and the bureau since the data for Bulletin 211 were obtained, indicates that the ores most immediately amenable to treatment by volatilization are of two types. The first is an oxidzed lead. silrer ore whose variable lime content makes it impractical to chloridize the ore for acidulated brine leaching, and whose base metal content makes treatment by cyanidattion unfeasible, The second type is the lead-zinc ore mentioned above, and is the one on which data are available for publication at present. This article Chows what ores of this latter type are amenable to treatment by volatilization, by giving briefly some of the more important physical and chemical properties an ore should preferably possess. Several examples are given from both laboratory experimental work, and from practice in the field, showing various phases of the volatilization process."

Nov 1, 1923

By V N. Rudashevsky, F Melcher, J Lodziak, D Klosa, N S. Rudashevsky, M Sitnikova, L Gast

A combination of novel and æclassicÆ methods, namely electric pulse disaggregation (EPD), hydroseparation (HS), preparation of monolayer polished sections, and mineral liberation analysis (MLA) was employed to study ores from platinum pipes (Bushveld Complex, South Africa), pristine PGE mineralisation of the Main Sulfide Zone (Great Dyke, Zimbabwe), as well as ancient and modern gold/PGM placer deposits. It is shown here that the EPD technique liberates mineral grains of interest without any visible destruction allowing the study and analysis of individual rock-forming and ore minerals, in our case especially platinum-group minerals. The HS method is an effective tool in concentrating heavy minerals by factors up to 10 000 fold. As near-total recovery of grains >10 ¦m is achieved, the nugget effect can be overcome also in case of limited availability of samples (drill core, museum specimens). The MLA technique is a fast tool to detect and characterise mineral phases in ores and ore processing products. Many mineralogical parameters of individual grains and mineral assemblages can be deducted and documented. The results show that the techniques employed, either on their own or in combination, provide a wide range of additional information especially on platinum ores which is beneficial to both the researcher and the metallurgist.

Jan 1, 2008

By Frank G. Miller

Controlling natural-water drives to effect efficient and economic production of petroleum, through wells, from reservoir sands and rocks is a problem of major importance in the oil-producing industry. Water-drive fields are characterized by large quantities of mobile water under high pressure immediately below the oil in the flanks or extraneous parts of reservoir formations, Hence, the water, which is in fluid connection with the oil and a source of a large proportion of the energy available for moving it, advances up-structure to replace it. This phenomenon of water moving crestward into the oil-bearing parts of the reservoir and replacing oil is termed edgewater encroachment. The mechanism by which oil is flushed out and continually replaced by water as the hydocarbon content of the field is depleted must be understood if natural-water drives arc to be used successfully to, induce efficient recovery of oil from its reservoir rocks. Until recently, the function of water in the production of oil has been somewhat obscure and was not given the consideration it deserved in early petroleum production-research programs because of the greater importance associated with and the effort devoted to investigations concerning the relations of natural gas to production of oil. Thus, with virtually no fundamental information at hand, it is not surprising that at first edgewater was considered a necessary evil, and the manner in which it was dealt with depended largely on the experience of the operators. During the intervening years, however, practical information on encroachment of edgewater in oil sands has been widely disseminated as a result of studies of oil-field depletion, and many theories pertaining to petroleum-reservoir energy and performance have been advanced; these theories necessarily included consideration of edgewater as an integral -art of the reservoir fluids and a source of energy for propelling hydrocarbon fluids through the reservoir and to the surface of the ground.

Jan 1, 1941

By R. Costantini

The author discusses the promising future of the use of pipelines for transportation of ore slurries over long distances, citing existing installations. Various criteria and factors affecting the use and size of pipelines are considered. Among the factors influencing the use of pipelines are particle size, specific gravity, abrasiveness, minimum velocities, and pumping considerations. Long-distance transportation of solids by hydraulic pipelines holds the promise of great economic benefits. Today within the confines of most mineral processing plants, the moving of solids about in slurry form by pipeline is commonplace, since the method offers great advantages when conditions are suitable. Yet, this method is surprisingly slow in being adopted on a broad scale for transportation of solids over long distances (arbitrarily the term will be applied to one over five miles long). This is especially surprising in view of the successful realization in this country within the last five years of two daring ventures in long-distance solids pipelines. A 72-mile long, 6-in. diam pipeline of the American Gilsonite Co. has been satisfactorily transporting 700 tpd of gilsonite from the mine at Bonanza, Utah, to the processing plant at Grand Junction, Colo., since April 1957. The 108-mile long 10-in. diam pipeline of the Pittsburgh Consolidation Coal Co. has been transporting about 4000 tpd of finely crushed coal from the mine at Cadiz, Ohio, to the Eastlake power plant of the Cleveland Electric Illuminating Co. on Lake Erie since January 1958. However, besides two projects in the operations of The Anaconda Co. there have been hardly any other significant solids pipeline developments in the minerals industry during the last three years. The two projects are the 14-mile long, 6-in. diam copper concentrate gravity pipeline at Anaconda's El Salvador project in Chile which has been transporting about 800 tpd since January 1959. The second is a 16-in. diam tailings pipeline at the Anaconda Reduction Works, Anaconda, Mont., designed to transport about 20,000 tpd of deslimed flotation tailings for dam building. This pipeline, which is currently undergoing tryout tests and which will be about seven miles in length, will have a maximum of three 20-in. rubber-lined centrifugal pumps in series at the starting point, each developing a maximum of 100 ft of head, to supplement gravity. It is the writer's opinion that the major reason for the hesitation in considering pipeline operations is confusion due to an inadequate understanding of the basic physical principles affecting the slurry flow process by many engineers in the industry. This in turn begets an attitude of fear and trepidation instead of confidence on the part of many management executives, which leads to a minimizing of the advantages and exaggeration of difficulties when considering the possibility of a long-distance solids pipeline. The promotion of better understanding and consequently the promotion of greater confidence in the potentials of long-distance solids pipelines when conditions are suitable is thus the main purpose of this article. To this end, after considering several examples of the possibilities for solids pipelines in the minerals field, the relative significance of the major factors affecting pulp flow, and some major aspects of slurry pumping will be discussed on a general qualitative level. Then a brief outline of the semi-empirical quantitative methods developed to date for estimating slurry flow behavior will be presented. SOME POSSIBILITIES To give an idea of the magnitude of the possible economic benefits, it should be interesting to mention briefly some of the projects currently under consideration and to suggest some likely future possibilities. At Anaconda's El Salvador Project in Chile (Fig. 1) it is eventually planned to extend the existing 14-mile pipeline by another 60 miles to bring the copper concentrates down to the coast of the Pacific Ocean. Preliminary tests indicate that the projected 6-in. pipeline will be able to transport approximately 2000 tpd of concentrates at a pulp density of 40 to

Jan 1, 1961