Search Documents

By Richard J. Mainiero, Marcia L. Harris, James H. Rowland

In the past several years, there have been a number of blasting-related carbon monoxide migration incidents. In each case, there have been some common factors that appear to be related to carbon monoxide migration. Geology, heavy confinement of the blast, close proximity to the affected structure, and open pathways into the affected structure are just a few. Prince William County, VA is an area undergoing a boom in suburban development. In the year 2001, more than 4,050 new homes were constructed within the county.1 In the new housing development located in Bristow, VA, trench blasting was utilized to excavate proposed sewage and utility lines. On November 8, 2002, a trench blast was conducted for the installation of utility lines. Later that evening a carbon monoxide detector alarmed in a nearby house. The gas company and fire department sampled for carbon monoxide and measured 100 ppm and more than 200 ppm on the first floor and in the basement respectively. Subsequent efforts to prevent migration of CO into the nearby homes met with mixed results. The only reliable technique for protecting neighbors from CO appears to be the placement of CO monitors in the homes. The events are presented and discussed.

Jan 1, 2004

By G. L. Fisher, R. Maddin

The rate of self-diffusion in silver single crystals during torsional strain was measured over a wide range of tenperatures and strain rates. The torsional strain was applied in a cyclic manner by reversing the divection of twist aftev a certain fraction of the total strain was reached. Surface roughening was substantially reduced in cyclically strained specimens compared with those strained entirely in one direction. Diffusion coefficients were determined using a special sectioning technique whereby slices could be removed parallel to the surface of a strained torsion specimen. The accuracy of the technique was first determined using roughened specinzens statically diffused to various penetration depths. Simultaneous strain-diffusion experiments were then performed over the temperature range 550' to 800 using strain rates of lo-' to 2.2 x 10' sec-'. The increase in silver self-diffusivity during torsional plastic strain was small. In only one case was the enhancement greater than twice the static value of the diffusion coefficzent. The enhancements increased slightly with decreasing tenzperature and increased with increasing strain rate. A dislocation pipe mechanism of enhancement was found to explain the present results satisfactorily. The magnitude of the enhancements and the tenzperatures at which they were observed suggests that a steady-state dislocation density of 10' to 109 dislocations cm-2 existed during the high-tempevature deformation. The diffusion coefficient in an fcc metal can be increased by 1) an excess concentration of point defects and 2) the rapid movement of diffusing atoms along grain boundaries and dislocations. Plastic deformation may be responsible for enhancements by both of these mechanisms. The results of simultaneous strain-diffusion experiments have caused a controversy over the magnitude of the effect of strain upon diffusion. Experiments reporting large enhancements have been criticized for the manner in which the diffusion coefficient was measured. Several of these experiments have been contradicted by other results obtained in a similar manner. No enhancement was reported by two investigators''' who performed their experiments at high temperatures where strain is expected to have little effect upon diffusion. A recent theoretical analysis3 indicates that strain enhancement by a vacancy mechanism will be small and exist only at low temperatures and rapid strain rates. It is doubtful whether any experiment has yet proven that strain enhancements can occur by an excess vacancy mechanism. In the present research, experiments were performed at extremes of temperature and strain rate in an attempt to measure enhancement of diffusion by strain. Self-diffusion of silver during torsional deformation was chosen since two separate investigations4j5 indicate that at least a small enhancement exists under these conditions. An accurate method of determining the diffusion coefficient, mechanical sectioning, was employed after a technique was devised to apply it to the roughened surface of a strained torsion specimen. First, the accuracy of the technique was determined for different penetrations (2fi). Then diffusion experiments were performed at temperatures between 550" and 800°C at strain rates of 10"" to 10"" per sec. I) EXPERIMENTAL PROCEDURE Preparation of Specimens. The experimental procedure detailing the growth of crystals, their treatment, and the annealing techniques during straining are contained in earlier publications.496 The dimensions and orientations of the torsion specimens are shown in Figs. 1 and 2. licatiin of Torsional Strain. The torsion procedure was changed from that used previously. The specimens were strained in cycles to reduce the gross distortion and surface roughening inherent in twisting to high strains in one direction. For all strains above 0.30, the total surface strain was obtained as follows: the specimen was twisted to 0.10 strain in a clockwise direction; the direction was reversed; the backlash in the torsion apparatus was taken up; and the specimen was twisted in a counterclockwise direction through the initial starting point to 0.20 surface shear strain in the opposite direction. The strain reversal took no more than 1 min to accomplish. The total accumulated surface shear strain was arbitrarily taken as the sum of the 0.10 strain in the clockwise direction plus 0.20 in the counterclockwise direction. Although cyclic torsional strain was beneficial, surface roughening and specimen distortion were not entirely eliminated. The variation in the diameter at various points on the specimen was often much greater than the depth of the diffusion zone. Since serious errors might result if specimens were sectioned in the usual manner, a technique of lathe sectioning was devised to allow sections to be taken parallel to planes of equal concentration.

Jan 1, 1967

E. B. WILSON, Scranton, Pa. (written 'discussion *).-Prof. Young's paper shows another application of electricity in solving problems in coal mining, and suggests that it may be possible to utilize the data he has collected in developing an electric firedamp detector. If electric lamps are to be adopted in gassy coal mines, the use of an electric firedamp detector becomes almost imperative, for safety lamps and electric lamps in the same mine are not always conducive to safety, and Liveings electric firedamp detector, is too cumbersome to meet with general approval. Three well understood facts are verified in a new way by Prof. Young's experiments: - 1. The temperature at which methane ignites. 2. The more inflammable gas present in an atmosphere, the hotter will be the flame, and the longer the cap in a safety lamp. 3. As the temperature at the source of ignition varies, the length of the gas-cap flame varies. Prof. H. B. Dixon collaborating with Mr. H. F. Coward, some years ago, made experiments on the ignition of various gases to find the tem-perature of their kindling points.1 From the results of their experiments, the writer has culled the ignition temperatures of some hydrocarbon gases, and has tabulated them with other data, in Table 1.

Jan 10, 1919

By O. C. Wheeler

During 1938, Colombia witnessed greater activity in oil prospecting and development than in any previous year in its history; more wells were drilled, more potential production established, more geological and geophysical work was accomplished, and more leases and concessions were acquired. Many companies, including the Texas, Socony Vacuum, Richmond (subsidiary of the Standard Oil of California), the Shell, and Tropical, contributed to this activity. Probably the most noteworthy development was in connection with the Barco Concession, which forms part of the Maracaibo Basin in eastern Colombia, adjacent to the Venezuelan frontier. There a great deal of preparatory work was accomplished in addition to camp and other construction, 20 producing wells were drilled and work was begun on the construction of a 12-in. pipe line to transport the oil to the port of Covenas, a distance of 260 miles. It is reported {hat 58,000 bbl. daily initial production was established during the year and is awaiting an outlet through this pipe line. Leasing and exploratory operations in Colombia continued active throughout the year; applications were made for concessions covering more than 1,100,000 acres of national lands and, in addition, leases were taken up on large areas of privately owned lands. Under Colombian law

Jan 1, 1939

Total extraction is a misnomer and invariably some coal losses occur in the mining of pillars. "Fulls" pillar extraction is by the pocket and fender method, the splitting method or the open end method, with extraction in the pillar, and in rows of pillars in planned sequence, using combinations of coal and timber and roof-bolts for support. Where circumstances dictate, partial extraction is used, leaving behind portions of pillars in large blocks for support. The use of such extraction plans and supports as minimum guidelines has contributed greatly to safety in United States Coal Mines.

Jan 1, 1974

By W. H. Basssett

THE amount of oxygen present in refined copper bears an important relation to the effects of various impurities on physical properties of copper, as well as the effects of reducing gases at higher temperatures. It seems fitting at this time, when the effects of reducing gases on copper are being discussed, to describe methods that have proved satisfactory for the determination of oxygen and sulfur, and to present some results obtained by investigation of these methods in the authors' laboratory. The procedure for the determination of sulfur is closely interrelated with that for oxygen and has, therefore, been included. It was first proposed by Hamper that oxides in copper could be accurately determined by the loss in weight sustained by finely divided copper when reduced at red heat in pure hydrogen, or by the weight of water produced. Hampe's method was later modified by Archbutt,2 who established the accuracy of the method and demonstrated that equally accurate results were obtained by noting the loss in weight or by weighing the water formed. The determination of oxygen by heating in carbon monoxide has been proposed by West.3 In our hands this method has given slightly lower results than obtained by heating in hydrogen.

Jan 2, 1926

By T. S. Lovering

The use of geothermal energy is expanding very rapidly. This type of energy has proven commercially profitable for generation of electricity, for space heating, process heating, auxiliary heating of water in conventional steam power plants and for recovery of chemicals contained in natural hot water and steam. Two types of geothermal energy sources are recognized: 1) hot springs in regions of nearly normal heat flow that tap a deep reservoir through which water moves slowly to a hot springs conduit and then rapidly to the surface; 2) hyperthermal areas in which the water is heated by a relatively concentrated heat source related to volcanicity. If there is a geologic trap that provides a geologic analog to a steam boiler, as at Larderello, Italy, the hyperthermal area will have a convecting system that develops superheated water at relatively shallow depth and may provide natural steam in large quantities. If a hyperthermal area is to be productive for a long time, the underflow into the reservoir should be slow enough to allow the heat source and convective system to heat the underflow to the working temperature, and the production rate must not exceed this rate of underflow. A model based on a typical aquifer suggests that the rate of movement of water through the reservoir be such that a few years are spent in transit between isotherms that are spaced about 2°F apart. The possibility of finding blind geothermal areas is illustrated by discussion of the techniques developed in evaluating the subsurface temperatures in the East Tintic district of Utah where a map of isotherms at water level (2000 to 2000 ft below the surface) shows that a hyperthermal area may exist a short distance southeast of the mining district. Very nearly all of the energy that man currently uses comes ultimately from the sun's radiation. This includes water power, fuels such as wood, peat, coal and petroleum, the wind and all our animal power. In the paper summarizing a conference on solar energyl6 the average amount of solar energy received daily on the earth is taken at about 1 cal per m2 per min or slightly less than 2 pcal per cm2 per sec; this is almost exactly the amount of energy on the average that the earth liberates in regions of normal geothermal gradient due to its own internal heating. In many places, however, the energy released is many times the average and in some of these hyperthermal areas, geothermal steam is used for generation of electricity, and hot springs are used for heating buildings and private dwellings, process heating, auxiliary heating of water in conventional steam power plants, and chemicals may be recoverable from both hot water and steam. The use of hot springs waters for heating houses goes back hundreds of years but until recently was confined to a few dwellings close to the hot springs. In Korea, some houses had hot spring water channeled through conduits in the floor centuries ago and thus the Koreans can be credited with pioneer development of radiant heating. In Iceland at present nearly a third of the population uses natural thermal water for domestic heating." The Reykjavik system pipes hot spring water at about 94°C throughout the city and has devised insulated double pipes that allow the water to be piped for some 25 km with a drop of only 1°C for every 5 km. The actual cost to the Icelandic consumer is only one-third the cost of heating by imported coal and yet the industry is one of the most profitable in Iceland. The most profitable use of geothermal energy has been its conversion into electricity which can be transmitted economically much greater distances than hot water. The largest installation at the present time is that at Larderello, Italy, where the Count of Larderello began to experiment in the production of electricity from geothermal steam 60 years ago — in 1904. He installed his first steam turbine, with a capacity of only 250 kw, in 1912 as the result of a local quarrel with the power company which furnished the current required in the Larderello chemical industry - an industry that then dated back nearly a century. As experience was gained in drilling deep holes to tap geothermal steam and in converting it to electric power, the capacity of the installation of Larderello gradually increased, but was all destroyed by the Germans during their retreat from Italy in the closing

Jan 1, 1965

By Richard J. Mainiero, Marcia L. Harris, James H. Rowland

In the past several years, there have been a number of blasting-related carbon monoxide migration incidents. In each case, there have been some common factors that appear to be related to carbon monoxide migration. Geology, heavy confinement of the blast, close proximity to the affected structure, and open pathways into the affected structure are just a few. Prince William County, VA is an area undergoing a boom in suburban development. In the year 2001, more than 4,050 new homes were constructed within the county.1 In the new housing development located in Bristow,VA, trench blasting was utilized to excavate proposed sewage and utility lines. On November 8, 2002, a trench blast was conducted for the installation of utility lines. Later that evening a carbon monoxide detector alarmed in a nearby house. The gas company and fire department sampled for carbon monoxide and measured 100 ppm and more than 200 ppm on the first floor and in the basement respectively. Subsequent efforts to prevent migration of CO into the nearby homes met with mixed results. The only reliable technique for protecting neighbors from CO appears to be the placement of CO monitors in the homes. The events are presented and discussed.

By H. S. Soto

The exact reasons that explain the low recoveries of coarse particles in conventional flotation machines are not clear. Being a concern for only a couple of mineral industries comparatively very few studies have been devoted to the problem of coarse particle flotation. Coarse particles flotation is particularly important in potash and phosphate beneficiation. Potash concentrates with particles larger than 1-2 mm do not require additional compaction or recrystallization and receive a premium price. However, recovery of this size particle in conventional flotation cells is very low, and therefore, the coarse floation tailings have to be reground and refloated to produce, at a higher cost, a less desirable concentrate. In phosphate beneficiation deslimed coarse ore (nominally l4x35 or l6x35 mesh) is normally treated separatedly from the finer (35x150 mesh) ore. Concentration by conventional froth flotation alone yields very low recoveries, and therefore, additional processes such as agglomerate flotation in tables spirals and belt conveyors have to be used ( Moudgil and Barnett 1979). Fatty acids and fuel oil used in phosphate flotation have a moderate level of selectivity but considerable amounts of sand report to the froth product, thus concentrates have to be further upgraded by a double flotation process. Concentrates from the anionic circuit are scrubbed in an acidic media to desorb the collectors and then refloated in a cationic circuit to eliminate the fine silica (Lawver et.al. 1978). In this paper the reasons that explain the low recovery of coarse particles in conventional flotation are discussed. A flotation column modified according to the main conclusions of this discussion is tested with two coarse phosphate samples.

Jan 1, 1989

By V Radmehr

Ammonia and Amonium salts have been recognized as effective leaching agents in hydrometallurgical processes due to low toxicity and cost, easy recovery and high selective recovery of metals. New research findings of considerable advantages of leaching by these agents and elimination of problems associated with acid leaching has resulted in a new approach in the world to this method. The investigations in this field indicate more frequent use of this method for extracting copper from ore and concentrate relative to other basic metals. In this paper, we have attempted to describe the basis and different ammonia leaching methods and present the major research activities in this field for copper. We have also presented the latest findings and related novel processes. Comparative assessment of advantages and disadvantages of this method relative to acid leaching method, kinetic study of copper ammonia leaching and evaluation of Eh-pH diagrams in a system containing water and ammonia are other parts of our study. Finally, by describing the studies on copper extraction from the resulting pregnant solutions, the applicable extraction agents have been reviewed.

Sep 1, 2012

By B. Tora

Coal mining activity is inextricably connected to waste production. These include coal slurries deposited in environment. Current knowledge in the field of mining and especially mineral processing allows extracting valuable fuel from deposit coal slurries. The article discusses of previous works devoted to coal slurries inventory in Jankowice Mine in Poland (Upper Silesia) and quality assessment of coal slurries. 12 samples of coal slurries deposited in waste pond of Jankowice Mine was taken for the investigation. Total amount of wastes deposited is more than 100 thousands tones. Keywords: re-flotation, coal wastes, waste storage, industrial verification

Sep 1, 2012

By Y. K. Rao

In the carbonyl process for the refining of crude nickel CO(g) reacts with nickel in the 310-370K range producing nickel tetracarbonyl, Ni(C0)4(g). Iron and cobalt impurities also form gaseous carbonyls but their partial pressures are low. The carbonyl is led to a decomposer plant wherein the gas disproportionates in the 500-600K range depositing pure metal on nickel pellets that move countercurrent to the gas-flow. This system serves to illustrate the fundamental principles involved in the vapor phase mass transport of elements, against temperature-gradient, under the influence of chemical potential gradient. Unlike in the crystal growth, the source is at a lower temperature (say 350K) whereas the seed is in the hot-zone (say 550K) of the closed ampoule-type reactor. By assuming virtual gas-solid equilibria in the end zones, with diffusion of gaseous species between them acting as a slight perturbation, the quasi-steady- state mass-transport rates are computed for a range of CO-pressures and temperatures.

Jan 1, 1993

By A. H. Taitt

During 1938, the exploratory drilling by the D'Arcy Exploration Co. Ltd., subsidiary of the Anglo-Iranian Oil Co. Ltd., was continued. The original basis of the search for oil and results to the end of 1937 have already been described.' During 1938 two further wells were drilled in the south, making a total of five wells completed in that part of England. Test wells were also commenced in the Midlands, East Yorkshire and Scotland, where one well, which proved natural gas, was completed during the year. Southern England.—The test well at Kingsclere, in Hampshire, which at the end of 1937 had reached a depth of 5032 ft. in the Lower Lias, entered the Trias at 5060 ft. and was abandoned in that formation at a depth of 5125 ft. A shallow test well was also drilled near Pevensey, in Sussex, to test the lower horizons of the Wealden series and the Purbeck and Portland beds. Traces of oil were encountered in the Wealden series but no production was obtained and the well was abandoned at a depth of 842 ft. in the Kimeridge clay, which underlies the Portland beds. A geological borehole was begun north of Lulworth in Dorset, where the outcropping Wealden series, Lower Cretaceous, is strongly impregnated with oil, to determine whether a more pronounced pre-Albian anticline underlies the very gentle arch of the unconformable Upper Cretaceous. Drilling is not yet completed. Nottinghamshire, Lincolnshire ad Yorkshire.—Geophysical investigations were continued in the eastern part of England where the structural conditions of the Carboniferous rocks are concealed by an unconformable blanket of Permian and younger sediments. Seismic methods failed to confirm the structural picture obtained by the previous gravity traverses, but confirmation of a structure near Ollerton, Nottinghamshire, which was suspected on evidence from colliery workings, was obtained. A location was made for a test well on this structure. Eskdale No. 1, begun on the Eskdale pericline near Whitby, in Yorkshire, to test the magnesian limestone of Permian age, was abandoned at a depth of 2486 ft. in the Trias after protracted fishing operations. A

Jan 1, 1939

By A. H. Taitt

During 1938, the exploratory drilling by the D'Arcy Exploration Co. Ltd., subsidiary of the Anglo-Iranian Oil Co. Ltd., was continued. The original basis of the search for oil and results to the end of 1937 have already been described.' During 1938 two further wells were drilled in the south, making a total of five wells completed in that part of England. Test wells were also commenced in the Midlands, East Yorkshire and Scotland, where one well, which proved natural gas, was completed during the year. Southern England.—The test well at Kingsclere, in Hampshire, which at the end of 1937 had reached a depth of 5032 ft. in the Lower Lias, entered the Trias at 5060 ft. and was abandoned in that formation at a depth of 5125 ft. A shallow test well was also drilled near Pevensey, in Sussex, to test the lower horizons of the Wealden series and the Purbeck and Portland beds. Traces of oil were encountered in the Wealden series but no production was obtained and the well was abandoned at a depth of 842 ft. in the Kimeridge clay, which underlies the Portland beds. A geological borehole was begun north of Lulworth in Dorset, where the outcropping Wealden series, Lower Cretaceous, is strongly impregnated with oil, to determine whether a more pronounced pre-Albian anticline underlies the very gentle arch of the unconformable Upper Cretaceous. Drilling is not yet completed. Nottinghamshire, Lincolnshire ad Yorkshire.—Geophysical investigations were continued in the eastern part of England where the structural conditions of the Carboniferous rocks are concealed by an unconformable blanket of Permian and younger sediments. Seismic methods failed to confirm the structural picture obtained by the previous gravity traverses, but confirmation of a structure near Ollerton, Nottinghamshire, which was suspected on evidence from colliery workings, was obtained. A location was made for a test well on this structure. Eskdale No. 1, begun on the Eskdale pericline near Whitby, in Yorkshire, to test the magnesian limestone of Permian age, was abandoned at a depth of 2486 ft. in the Trias after protracted fishing operations. A

Jan 1, 1939

By E. Cortese

Phosphate occurs in many places in Egypt, in two main zones: one in Upper Egypt, along the Nile Valley, principally on the right side, and one near the Red Sea coast. In the Nile zone, the principal layers of phosphate rock are to be found: in the mountains east of Mahamid (right side of the valley); in the hills near Sibaiya, also called Sebaieh (both sides); in the hills of Agula, Hagaza and Gurn (right side); and further on, along the camel road leading from Kena to Kosseir, a few miles east of Legheita's Oasis. Following that track, after having crossed the watershed, underlain by rocks like granite, serpentine, porphyry, and diabase, one comes again to the Cretaceous formation containing considerable quantities of phosphate, at Gebel Duwi, Gebel Nakheil, and Gebel Kosseir El Kadim, not far from the coast. More to the north, in the hills near Safaga Bay (Um El Uettat El Wasif) is another rich bed of the same formation. There are reports of phosphate existing near Suez and in the Sinai peninsula, and possibly some other zones can be traced or discovered in the future. The mines are well developed on the right bank of the Nile at Sharawna (near Sebaieh Station) and along the Red Sea coast, at Safaga and near Kosseir. Prospecting work has been done at Gebel Duwi, Gebel Gurn, Agula, Hagaza, and near Mahamid. The phosphatic formation in Egypt is quite variable, not only from place to place, but even within small areas. The phosphate is all of Cretaceous age, as is proved by the fossils found in it. It is considered to belong to the Campanian or, more appropriately, to the Maestrichtian series. The principal fossils are: Alectryonia Villei Coq. sp.; Roudereia Aures-sensis Coq. sp. = R. Drui Mun. Chalm.; Trigonoarca multidentata, Newton.; Cardita libyca, Zittel; Libycoceras Ismaely, Zittel; Nautilus sp.; Ancystrodon libycum Dam.; Corax pristodontus Ag.; Lamma biauriculata Zittel sp. Above the Maestrichtian beds, we have the Danian series, unconform-ably covered by Lower Eocene beds. Under the phosphate is a grayish marly clay, and beneath this, bluish-gray scaly shales resting on the Nubian sandstone (Santonian).

Jan 1, 1918

By Walter Miller

Advancement in engineering in the refining industry during 1933 might be likened to the jagged flame of a poor wick-test kerosene—a few outstanding high spots, but not broadly spectacular. Economic conditions were unsatisfactory for the first six or eight months, but the improvement in the latter part of the year had some immediate effect in stimulating new designing and building. The national legislative program involving the industry drew the attention of executives away from petroleum technology to some extent. The National Recovery Act, and its offspring, the Petroleum Code, demanded deep and continued study to put the machinery into smooth motion. From a purely technical engineering stand, therefore, the emergency measures might be considered a temporary brake on progress. The ultimate effect, if the whole industry can get back "out of the red," may well be a more than expected advance. Of course, petroleum technologists and engineers, including both those engaged within and those busy in designing and building for the industry, continued their efforts, and much of the results of their work will undoubtedly see the light of day under the improved economic conditions, which bid fair to stay with us. There was little improvement during 1933 in atmospheric distillation, sweetening processes, or furnace design, but experimentation during the year on these subjects may materialize into distinct advances. The trend toward compact distilling and fractionating equipment, especially in the Appalachian district, deserves noting. A number of refineries in that district replaced obsolete shell still units with up-to-date tube stills and efficient fractionating towers, both for the better separation of lubricating fractions from the crude and for improving the boiling range of the gasoline. A number of small skimming and topping plants in flush fields, such as East Texas, which felt the pinch of production control, were forced to shut down, but the stronger among them are consolidating their positions by installing cracking equipment and in some cases more modern crude-distillation units. Motor Fuel For the first time in many years a reviewer is able to point to at least a temporary cessation in the competitive race in the manufacturing

Jan 1, 1934

By D. D. McNaughton

IN providing 65,000 tons of broken muck per day for shovel operation in a large open pit copper mine, drilling equipment and efficient use of that equipment is of prime importance. To improve existing drilling efficiencies, a large electric rotary drill capable of drilling 12-in. holes was purchased in May 1955. At Chino 96 pct of the blasting is done with 12-in. holes because: 1) the large holes break the optimum amount of material to reduce trackshifting to a minimum, 2) better fragmentation is obtained from a relatively short column of powder, and 3) longer spacing results in greater tonnage broken per foot drilled. From 1955, when it was purchased, through October 1956, the rotary drill has drilled 95,701 ft at a rate of 167.4 per shift in various locations and types of ground encountered in the mine. (This includes moving time and all other delays while a crew is on the machine.) The machine has been worked two shifts per day, seven days per week, and has been available 68 pct of this time.

Jan 5, 1957

Average annual growth in consumption of primary energy in Australia over the past ten years has been 5.5% compared to a world average of 4.1%. Over the next ten years growth rate is expected to increase to 6% per annum due largely to the rapid development in the mineral processing industry. By the end of the 1970's natural gas is expected to supply more than 9% of Australia's, primary energy market. Coal will supply 40% and petroleum products 47%. Nuclear energy will make its appearance but-will only make a small contribution in the period. Australia has adequate reserves of natural gas and coal to supply its needs in the 1970's and beyond. However the newly developed reserves of crude, while supplying 60-70% of requirements-in the initial years; will need regular and sizable additions if they are to .keep pace with the expanding consumption. For Australia to become self sufficient in the period 1970-1990 it is estimated *that new discoveries-will need to approximate. ten times the volume of recoverable reserves found in Australia to date. .

Jan 1, 1970

By Kenny Lo

"SummaryFor more than a century, ground freezing has been a construction technique used in stabilization of ground by means of lowering the temperature of surrounding soil strata. This technique is used in circumstances where conventional grouting method is unable to achieve the degree of consolidation required to prevent settlement and water ingress during the execution of underground excavation. Whilst ground freezing is effective in imparting self-supporting characteristics to the excavation profile, it poses significant challenges when it comes to the New Austrian Tunneling Method (NATM) where sprayed concrete is used to support the freshly excavated ground. Sprayed concrete, if used in an appropriate manner, provides a fast, efficient and structurally-reliable means of supporting the structure, especially in underground construction. The evolvement in sprayed concrete technology is attributed to the development of concrete know-how, improvement of spraying technique with the use of automation spraying equipment, more in-depth understanding of sprayed concrete behavior and enhancement of materials used in production of high quality sprayed concrete Not only has this markedly escalated the prominence of sprayed concrete on wider perspective,. the positive development has also pushed sprayed concrete beyond its boundaries, enabling it to be embarked on area of application not considered possible decades ago. Nevertheless, sprayed concrete, for all its placement versatility, still depends largely on the technicality provision very similar to concrete to achieve the required quality. Parameters such as raw material grading composition, curing temperature and cement quality are some of the factors that can easily sway the quality of concrete from one extreme to another. Conducive ambient temperature is critical in ensuring optimum hydration of concrete. This is more important in sprayed concrete where temperature plays a pivotal role in influencing the early strength and long term strength development. The low temperature imposed by ground freezing is everything but ideal for competent hydration to take place. This paper outlines how the innovative use of sprayed concrete helps to overcome the adverse ambient temperature in the construction of a 110m underground pedestrian walkway utilizing ground freezing technique in Hong Kong."

Jan 1, 2016

By W. J. Millard

Owing to a moratorium in the drilling of crown-land leases in Trinidad during the year of 1931, only 40 wells were spudded in during the first eight months as compared with 110 during the same period in 1930. Nevertheless the production will show an increase of about 400,000 bbl. over that of 1930. An estimate is given in Table 1. Since the oil produced in 1930 was 9,418,907 bbl. and that in 1931 probably will be 9,853,976 bbl., the year 1931 probably will see an increase of about 4.6 per cent. The gross production of crude oil in the colony has increased steadily year by year, with the exception of 1919, when there was a slight decline. A tabulated statement was given last year.' The Petroleum Times of March 21, 1931 (p. 413) gives the total production of 1930 as 9,418,000 bbl. and the average monthly production as 784,833 bbl. The same two items for 1931 are estimated at 9,853,976 and 821,165 bbl., respectively.

Jan 1, 1932