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By T. Ito, N. Tokashiki, H. A. Bilgin, Ö. Aydan, T. Akagi

This study is concerned with the electric potential induced by deformation, fracturing and sliding of non-piezoelectric geomaterials. In experiments, the acoustic emissions together with electric potential measurements were also measured in order to see how the so-called seismic electric signals are associated with new fracture occurrence and propagation and sliding in case of existing discontinuities. The outcomes of this experimental study may explain why such electric potential variations may occur during the fracturing and sliding of non-piezoelectric geomaterials. On the basis of these outcomes, their possible implications in geo-engineering and geo-science are discussed. Ce travail concerne 1e potentiel électrique produit par la déformation, 1a fracture ou le glissement du matériel géologique non-piézoélectrique. Aux expérimentations, on a mesuré 1es émissions acoustiques avec le potentiel électrique afin de constater la relation entre les phénomènes de glissement ou de formation et de propagation de nouvelles fractures le long des discontinuités existantes. Les résultats de ce travail expérimental expliquent pourquoi de telles variations de potentiel electrique se produisent durant le glissement ou la fracture du matériel non-piézoélectrique. Sur la base de ces résultats, on a discuté de leurs éventuelles implications dans les domaines de 1a géologie et de 1a géo-ingénierie. Diese Studie befasst sich mit dem elektrischen Potential das durch die Deformation, Bruchbildung und Gleiten von nicht-piezoelektrischen Geomaterialien induziert wird. In Experimenten wurden die akustischen Emissionen zusammen mit elektrischen Potentialmessungen gemessen, um zu sehen, wie die so genannten seismischen elektrischen Signale mit neuer Bruchbildung und Ausbreitung sowie Gleiten im Falle von vorhandenen Diskontinuitäten verbunden sind. Die Ergebnisse dieser experimentellen Untersuchungen könnten erklären warum elektrische Potential Schwankungen während der Bruchbildung und dem Gleiten von nicht-piezoelektrischen Geomaterialien entstehen. Auf der Basis dieser Ergebnisse, wurden ihre möglichen Implikationen in Geoingenieurwissenschaften behandelt.

Jan 1, 2003

By David G. Borg

Emulsions explosives, like slurries or water gels, are water based explosives. Emulsions were first introduced as a packaged blasting agent in the late sixties. Since then, many new variations have been developed, from small diameter detonator sensitive products to bulk loaded anfo/emulsion blends. Explosive detonation characteristics such as velocity of detonation, density/sensitivity relationship, strength, and water resistance along with how they relate to the type of rock and type of application will be presented. Various methods of sensitizing such as glass microspheres and chemical gassing along with product limitations and safety recommendations for bulk loading emulsions will also be presented.

Jan 1, 1994

By W. R. Reed, G. J. Joy

The personal dust monitor (PDM) is a new coal mine respirable dust sampling instrument that has the ability to provide accurate end-of-shift and real-time respirable dust exposure data. A hypothetical cost comparison analysis of the PDM with the current MSHA-required coal mine dust personal sampling unit (CMDPSU) was conducted. Some simplifying assumptions were made to create hypothetical cases for analysis. This analysis was limited to respirable dust sampling of one designated operator (DO) and one designated area (DA) for one mechanized mining unit (MMU) which operated one shift per day. Only sampling intervals of the minimum sampling as required by federal regulations and continuous sampling were analyzed. This cost analysis from the company perspective is only one part of an overall cost/benefit analysis that should be conducted at a later date. In this analysis, company-associated costs were examined for both sampling systems. Results show that the PDM, while it has high initial costs of approximately $12,600, may be a cost-effective sampling system for measuring coal mine respirable dust. The estimated present worth cost of conducting the minimum required dust sampling over a five-year life ranges from $5,850 to $19,000 for the CMDPSU, with the higher present worth cost including costs of potential violations incurred. For the PDM, the comparable present worth cost is $14,900 to $19,300, with the lower present worth cost representing a lower capital cost of $8,150 per unit if more than 850 units are produced per year, while the higher present worth cost reflects the result with the higher $12,600 capital cost.

By Donald E. Redmon

This Bureau of Mines report reviews injury experience in the metallic mineral industries for 1966-67. For each of the years, 27 tables summarize disabling work injuries by department, source of injury, extent of disability, part of body injured, and nature of injury. Correlative information on employment, worktime, and operating activity is also presented.

Jan 1, 1973

By F. A. Rutledge

"The chromite deposits of Red Mountain, 10,miles southeast of Seldovia, Alaska, are in an intrusive of ultramafic rocks. The earliest reference to the deposits was made by U.S. Grant3/; J.B. Mertic, Jr. 4/ made a brief examination in 1917; and A.C. Gill5/ spent 7 weeks studying the ore bodies and geology of the region in 1918. The Federal Geological Survey had a field party in the region from July until September 1940 and the Red Mountain area was mapped and geological data were assembled by P.W. Guild.6/A preliminary investigation of the Kenai chromite deposits was made in July 1941 by R. S. Sanford,7/district engineer of the Bureau of Mines, accompanied by P. W. Guild, assistant geologist of the Geologi¬cal Survey. This was followed by surface sampling and core drilling, which were completed in September 1942 under the direction of John W. Cole,8 associate engineer of the Bureau of Mines. G. O. Gates, associate geologist, and A, B. Unkelsbay, junior geologist, of the Geological Survey, logged cores and interpreted geologic features revealed by Bureau of Mines drilling and trenching.9/J. C. Roehm, associate engineer of the Territorial Department of Mines; examined the Red Mountain area in august 1941.10/Additional exploration of other deposits in. the Red Mountain area was completed during the summer of 194. Work consisted of surface sampling, core drilling, and mapping. G. O. Gates, associate geologist of the Geological Survey, spent 4 days in August investigating results of the Bureau of Mines program.Throughout the exploratory work conducted by the Bureau of Mines the cooperation of Red Mountain Chromite, Inc., and especially of John Blodgett, Jr., and Collis 2, Druley, president and superintendent, respectively, was greatly appreciated. Use of their camp in the Windy River cirque and shops at Kasitsna Bay facilitated the Bureau of Mines program."

Apr 1, 1946

The fundamental objective of mine plans are usually to maximize the mine profit by extracting ore at the lowest possible cost over the mine life while some technical constraints are satisfied. Since the costs associated with the operation of trucks and shovels as resources are significant, determining the optimum number and allocation of these resources is an essential issue. This paper presents a Mixed Integer Linear Programming (MILP) model to determine the optimum number of shovels and trucks required to meet the short-term plan?s goals. Also, the model takes into account the allocation of trucks and shovels to mining faces. This model minimizes operational costs, while attempting to meet the production demand and to satisfy technological constraints. This paper also analyzes the operations of trucks and shovels in an open pit mine using ARENA simulation software.

Jan 1, 2012

By R J. Butcher

Many deposits have been evaluated as potential block caves over the last 20 years due to the perceived benefit of low operating costs. However, block cave projects are typically capital intensive, with mass mining providing high throughput rates that required large investments in mining, processing and utilities infrastructure. While the key economic metrics in deciding to proceed with a caving project are typically net present value (NPV) or internal rate of return, these may not represent the best decision metrics for some companies. Where a caving project is competing for scarce capital amongst other projects in a company’s portfolio or where the caving project is the only project being evaluated by a company trying to raise capital, other metrics may be more appropriate. This paper explores the use of present value ratio and the minimising of maximum negative cash flow as suitable metrics in determining alternative strategies. Trade-offs between optimising for economic value and capital efficiency measures allow for decision-makers to evaluate potentially higher-risk, higher-capital and maximum NPV projects against lower-risk, lower-capital projects.CITATION:Stewart, C A and Butcher, R J, 2016. Block cave evaluation, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 809–816 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By P. L. Swanson

Stability analyses of fractured and faulted rock masses require delineation of the position, extent, and orientation of geologic discontinuities. The size of the smallest active discontinuity that may potentially be resolved using the spatial distribution of microseismic event locations is Limited by the accuracy and precision of the location methods. At a hard-rock mine in the Coeur D'Alene mining district of northern Idaho, two data sets consisting of calibration blast signals from a known source site and origin time and microseismic event signals were recorded using a stope-wide accelerometer array. These seismic signals are used to quantify various sources of error in event location. Five factors influencing source location errors are examined in this U.S. Bureau of Mines study: (1) biases of the numerical source location techniques, (2) receiver array geometries, (3) uncertainties in receiver positions, (4) errors in picking arrival times, and (5) uncertainties in seismic velocity structure, including the effect of mine openings. In addition, synthetic data (accelerometer positions, travel-time picks and wave velocity) are used to determine the effect of known systematic and random errors on source location calculations. It is shown that the commonly accepted association of minimum travel-time residuals with the best location solution does not necessarily hold true when there is a systematic error in seismic velocity. Recommendations are made for increasing the accuracy and precision of locations of microseismic events detected under similar field conditions.

Jan 1, 2010

By D. Kunstelj, M. Stubicar, A. Tonejc, A. Bonefacic

A. Bonefafcic, D. Kunsfeli, M. Stubicar, and A. Tonejc The present communication is concerned with the variation of the texture in aluminum wires with die angle and temperature, at constant speed of extrusion. Experiments were carried out concurrently on refined samples, with a stated purity of 99.997 pct pure A1 and commercial samples of 99.5 pct Al. Ingots of refined aluminum samples were machined to 30-mm-diam by 150-mm-long billets. These billets were transformed to 5-mm-diam wires by drawing. The final form, suitable for examination, was obtained by extrusion through conical-face dies with a 1-mm hole diam and extrusion ratio 5:l in diam. The initial form of the commercial aluminum samples was drawn wire 5 mm in diam. These samples showed a poorly defined texture with (111) as a major and (001) as a minor component. A similar defined texture appeared in the refined aluminum samples after drawing to 5 mm diam. Conical-face dies with different angles (defined by the axis and the generating line of the cone) were used in our experiments. The values of the angles were 27, 35, 45, 57, 63, and 90 deg. The extrusion container was fitted with a heating element and controller permitting temperatures up to 600°C to be maintained within i5"C. Extrusion was performed at 250°, 300°, 350°, 400°, and 500°C at constant speed (approximately 1 mm per sec) and constant die reduction. The extrusion product was a wire 1 mm in diam and approximately 20 cm long. In order to remove the surface layer with the "conical" texture and to reduce the absorption by the X-ray examination of the samples, the extruded wire was etched to 0.22 mm in diam. Experiments were performed in the middle sections of the 20-cm-long wires. In addition to the die of l-mm hole diam, dies with a 1.5-, 0.7-, 0.6-, 0.5-, and 0.4-mm hole diam and 63-deg die angle were constructed. In our experiments we did not find in these ranges any important difference concerning the texture of the extruded wires and we continued our work solely on the 1.0-mm die. The diffracted X-rays (Cu K radiation) were recorded photographically. Diffracted intensities were measured on the (111) reflection with a microphotometer. The relative amounts of texture components were determined from the areas under the diffracted maxima. We found the texture of extruded aluminum wires to be strongly influenced not only by the temperature of extrusion and the purity of the sample but also by the form of the die. It is generally admitted that cold-drawn aluminum wires have mainly a (111) texture with a small amount of (001) component, Table I of Ref. 1. In our experiments with wires extruded in conditions represented by Fig. 1, in some cases a single (001) texture was obtained. If these wires were drawn repeatedly at room temperature, X-ray measurements revealed a duplex (001)-(111) fiber texture. Further drawings increased the (111) and decreased the (001) texture component. In Fig. 1 the percentage of material oriented with (001) parallel to the extrusion direction is represented as a function of the temperature and the die angle (a), for commercial and refined aluminum samples, respectively. From these diagrams we may draw the following conclusions. The slope of the die (a) influenced more strongly the texture at the lower rather than the higher temperatures. Again, a stronger influence was found in the case of the commercial in comparison with refined aluminum samples. In the case of the commercial aluminum samples the amount of material with (001) texture increases with increasing wire temperature in an approximately linear manner. This effect is less pronounced in the pure aluminum samples, with the exception of the die with a = 45 deg. In this case the (001) texture decreases with increasing temperature, as shown in Fig. 1. Component (001) is more pronounced in higher-purity aluminum samples. Our experiments led to the conclusion that both (001) and (111) components are essentially stable in extruded aluminum wires. As we obtained a single (001) texture starting with a sample of drawn wire in which the (001) component was very weak, our experiments revealed that the (001) component is not a remnant of the initial texture; this is in disagreement with the findings of Vandermeer and McHargue.1 We gratefully acknowledge discussions with Professor M. Paic. 1 R. A. Vandermeer and C. J. McHargue: Trans. 7MS-AME, 1964, vol. 230, p. 667.

Jan 1, 1969

By W. W. Adams

Coal mining in the United States, had a somewhat higher death rate per million man-hours of exposure among the employees in 1937 than in 1933 to 1936. However, the rate in 1937 was lower and therefore more favorable than that in any year since 1921 but previous to 1933. The nonfatal injury record, which began in 1930, was lower and therefore better in 1937 than in any other year since 1930. Separate figures covering bituminous-coal mines in all States showed a lower fatality rate in 1937 than in any year since 1920 but before 1933, and a lower nonfatal injury rate than that of any year since 1930 except 1933 and 1936. Reports for anthracite mines in Pennsylvania revealed a better safety record for fatal accidents in 1937 than in any year since 1930 except 1933, 1934, and 1936 and a better record for nonfatal injuries than in any year since 1930 except 1933.

Jan 1, 1940

By Kjell Winther

"Hydralift Scanmec introduced early in the eighties a new and different mill design for very large grinding mills. The design described has actually no size limitation upwards and is so far suggested with motor power up to 40 MW. The mill is furnished with gearless ring motor drive transmission. It is totally fabricated, without heavy castings. The first installation, an 8, 1 MW ball mill dia. 6,5 m x 9,65 m length, has been in continous operation in 13 years without problems. Total grinding costs has been reduced with 3 0% compared to traditional smaller mills. Reductions has been achieved in maintenance cost, power consumption, liner wear and grinding media consumption.So far 3 ball mills of the described design are delivered and in operation, one grinding Iron ore and two grinding Nickel ore.IntroductionThe design of mills for mineral ore dressing has basically been unchanged since grinding in mills started some I 00 years ago, in spite of the fact that mills have grown larger and larger. This has resulted in structural and mechanical problems, causing expensive failures and loss of production.Hydralift Scanmec engineers were designing mills for more than 20 years according to the old «rules». As they experienced interest for an increase in the mill size at the time when reports about failing mills were published, they started analyzing the different mill parts to find new solutions. One goal was to only use elements from proven technology in the new design. Two key items were ring motor (wrap around motor)(Isch et al. 1977, Meintrup and Klein 1982, Ranze 1983) and large diameter pad bearings (wrap around bearings)(Fuller 1984), both acknowledged from other industries."

Jan 1, 1995

Mr D. Twigg graduated in Metallurgy at the Sheffield Polytechnic, and later obtained a Master of Science degree at the University of Bradford. Mr I.D. Matthews matriculated at Roosevelt High School and joined the No. 1 Parachute Battalion in 1968. He worked in Zimbabwe for 31 years in geological prospecting, civil engineering, and open-pit mining.

Jan 1, 1985

By Pablo Velasco

The Belize economy recorded modest growth during 1980; the growth of the gross domestic product (GDP) in real terms was between 1% and 2%. At current prices, the 1980 GDP reached $108 million2. This output was largely attributed to the performance of a few industries, mostly nonminerals. Such performance improved significantly the balance of payments situation by reducing the deficit from $19 million in 1979 to $4 million in 1980. The rate of inflation was an estimated 18% in 1980 and would have been greater if not for a conservative monetary policy and price control on a number of essential items. Expert earnings increased $43 million, or 50%, from the 1979 level. After increasing more than 25% in 1979, imports increased only 6% in 1980 to a level of $141 million owing to the decline in investment and stabilization of petroleum prices. The balance of trade deficit was $9.8 million in 1980, a marked improvement from the 1979 level of $45.1 million. The mineral output for Belize accounted for only a fraction of 1% of the GDP. Such activity was limited to the production of limestone, marl, and sand and gravel, all of which were primarily used in construction of the Northern Highway between Orangewalk and Belize City. Mineral resources are deficient or nonexistent in Belize for the majority of metals and nonmetals, although the Government and others continue to believe that petroleum must exist in Belize. The proximity to Mexican oilfields and the growing finds in the Peters area of Guatemala support this expectation. The Government continues encouraging exploration onshore and offshore and offers terms that

Jan 1, 1982

By Robert Vidal

The performance of a laboratory-scale cell for the electrolysis of an aqueous chrome alum solution was studied. Electrode potentials, pH, and Eh were recorded. An optimum catholyte pH of about 2.5, consistent with information from the literature was observed. Values exceeding this range resulted in a precipitate formation and are detected by wavering cathode potentials. The role of anodically produced dichromate ions was investigated by chemical analysis. It was found that the steady state concentration of dichromate ions varies inversely with fluid flow from catholyte to anolyte. This concentration was also reduced with the use of precious metal coated titanium anodes.

Jan 1, 1994

By Noel A. Warner

Modern steelmaking is based on direct use of oxygen in high intensity batch reactors. A totally new approach is proposed in this paper, based on the view that pursuit of high intensity is unlikely to lead to successful coal-based continuous steelmaking. By substituting carbon dioxide and water vapor as the oxidants rather than using oxygen directly, the intensity is greatly reduced. Accordingly. subsurface formation of carbon monoxide bubbles can be avoided by careful manipulation of the three participating rate processes, gaseous diffusion, interfacial chemical kinetics and liquid phase mass transfer. Steelmaking can then be carried out without explosive ejection of molten droplets and the generation of micro-spray but rather in a controlled and fumeless fashion. The vital component is the introduction of generic melt circulation technology. Three melt circulation loops in series are envisaged. Starting with a composite feed of iron ore fines, pulverized coal and lime flux, a metallized solid raft floating on molten iron is propelled out of the ironmaking loop onto the first of two downstream steelmaking loops. In the first, a liquid slag is formed, primary decarburization is undertaken not with oxygen but rather with CO2 and H2O and the melt is desulfurized. The semi-product stream enters the third melt circulation loop, where open-channel decarburization is effected along with dephosphorization to yield a low carbon steel product. Alternatively, the melt leaves the last loop to irrigate a packed tower countercurrent to argon at around 100 mbar to continuously produce ultra-low carbon (ULC) steel.

Jan 1, 2003

By E. J. Gleim

To make a thorough survey of a coal mine in order to eliminate hazards, the competent safety engineer must be familiar with mere than one branch of engineering. It is essential that he know the properties of mine gases and the methods of detecting them, as well as hew to prevent dangerous as accumulations. It is also essential that he understand the action of overlying strata when the coal is removed, and the proper methods of protection by timbering or other suitable means of support. He must know the value of protective clothing in reducing injuries and mast be informed as to the correct handling and use of explosives to avoid premature blasts, misfires, and ether failures in blasting practice. He must understand hew to operate locomotives and cutting, loading, and various other types of machines to be able to recommend effective safeguards for protecting the men who use them in addition to being informed as 'to these and many ether activities connected with the mining of coal, he must net overlook electrical engineering if he wishes to combat the fire, shook, and ignition hazards attendant upon the use of electrical machinery and circuits in and around the mine intelligently. There are many points relating to safely in the selection, maintenance, and use of electrical circuits and equipment that are perfectly obvious to the electrical engineer but perhaps are not se evident to those not trained in this particular branch of engineering. Engineers of the U.S. Bureau of Mines who have made a special laboratory study of electricity as related to safety in minus haw e also made inspections of electrical installations at a large number of bituminous mines. These inspections have revealed practices and conditions that not only do not contribute to safety but that add nothing to efficiency and economy in the operation of the mine.

Jan 1, 1936

By Adam Turcotte

Mining operations consume a considerable amount of energy, and while reduced energy consumption is desirable, it is not always clear how to achieve this goal. Understanding the opportunities to optimize energy consumption is crucial, and the key to understanding is visualization. One option is the Sankey diagram, which has been used for over 100 years to visualize the flow of energy, materials, or cost through various processes. However, there are drawbacks to this approach that must be addressed. In a Sankey diagram, each flow is represented by an arrow possessing a width proportional to the magnitude of the flow it represents. The diagrams show input flows, how energy is converted and into what form, and also output flows. As per the first law of thermodynamics, the total energy output is equivalent to the total energy input, so any energy that is not transferred to another process is considered to be wasted. These waste flows are depicted in Sankey diagrams and make it straightforward to associate energy sources, sinks and waste flows. Unfortunately, Sankey diagrams do not convey all information required to support practical decision making for redirecting individual energy flows. Based only on a Sankey diagram, it may become evident that a significant flow of waste heat is of the appropriate grade (temperature) and volume to meet an on-site heat demand currently being met with paid-for, possibly carbon intensive fuel. However without augmenting the Sankey diagram with 3D spatial, true geometric analysis, the practicalities of the concept or idea may not be fully appreciated. Another issue with a Sankey diagram is that the magnitude of the energy flowing between processes may have temporal fluctuation or variability on different timescales (diurnal, seasonal, interannual). Currently, Sankey diagrams only provide a static picture of energy conversion and consumption, so that, for example, 4 separate diagrams could have to be prepared for each season. A new energy flow visualization technique which we have called Sankey Trees has been developed. Process locations are defined within a 3D model of the site being studied, and the magnitude of the flow between each pair of processes considered is replaced with a time series. Branches of sustained and diminishing flows are represented through variation of the geometric properties of the branches of the trees. These branches are animated to indicate the direction of flow, and branch joints are used to indicate that a process is transporting one form of energy to multiple processes.

Aug 1, 2013

By Robert H. Peters

Several significant problems associated with employee turnover among underground miners are described in this Bureau of Mines report. Although a vast amount of research has been conducted on turnover among employees in nonmining industries, there has never been an attempt to empirically investigate the causes of turnover among underground miners. This report presents the results of empirical research on employee turnover in other industries and describes and critiques the research methods that have been used to investigate turnover. Using the findings on employee turnover in other industries and known data about miners and the mining industry, a conceptual model of the factors that cause turnover among miners was generated. This model, which is expected to provide a basis for later empirical studies, is presented. Several recommendations for controlling miner turnover are also presented.

Jan 1, 1986

By R. B. Anderson

SULFUR poisoning of iron catalysts in the Fischer-Tropsch synthesis was investigated at the Bureau of Mines, because synthesis gas produced from coal contains sulfur compounds. Tests of two typical iron catalysts with synthesis gas containing known concentrations of H2S were made to determine catalyst life as a function of sulfur concentration to ascertain the type of gas purification required. Fixed beds of activated steel turnings and a fused iron oxide catalyst were investigated in sulfur poisoning tests at 21.4 atmospheres with IH2+100 gas containing 6.9, 23, or 69 mg S as H2S per cubic meter (0.3, 1.0, and 3.0 gr per 100 cu. ft.). In tests of reduced catalysts at constant temperatures, more than 80 percent of the activity was lost when 0.5 mg S/g Fe was introduced. Poisoning of nitrided or carbided fused iron oxide catalysts to a given extent required more than twice as much sulfur than for the corresponding reduced catalyst. When the synthesis temperature was increased to compensate for loss in activity, tests of the fused iron oxide catalysts at constant productivity could be continued for 19 to 98 days. The tests were terminated by clogging of the reactor, presumably caused by carbon deposition. One objective of the present work was to determine if synthesis gas, purified by the Bureau of Mines' hot-potassium carbonate process for removing H2S, OOS, and CO2, is suitable for synthesis on iron catalysts. The sulfur content of the gas purified by tills process is in the range of concentrations used in the present work. In constant-productivity tests of nitrided fused iron oxide catalysts with synthesis gas containing 6.9 mg S/m3, catalyst lives are nearly long enough for serious consideration of tills mode of operation. However, factors relating to selectivity and stability of the catalyst indicate that this type of operation is impractical for a commercial process. On this basis additional gas purification, such as iron oxide boxes following a hot potassium carbonate scrubber, is desirable.

Jan 1, 1965

By G. A. Van Wielingen

"The conditioning of natural gas to meet contract pipeline specifications involves in the majority of cases in Western Canada, the appropriation of substantial capital expenditures for treating and processing installations. It is therefore of vital importance to the owners and producers of natural gas to arrive at an appreciation of the economics pertaining to the production and surface handling of their gas reserves at the earliest possible stage of field development. The treating and processing of natural gas often results in considerable changes in composition and related physical characteristics between the wellhead and the point of delivery of the saleable gas. This paper presents a general outline of engineering calculations which can be applied in the pre-determination of the effects that surface handling of gas will have on the composition and physical characteristics of sale-able gas. Emphasis has been placed on the calculation of hydrocarbon dew-points, heating values and shrinkages prevailing at the various stages in the surface handling of natural gas. It is believed that advance information indicating the approximate ranges of these physical properties will facilitate process selection and will provide a basis for the estimation of capital and operating costs of process installations."

Jan 1, 1960