Search Documents

By Carlton D. Hulin

The usual concurrence in time and space of intrusive igneous activity, favorable structural disturbance and mineralization, which is so manifest in the mineralized district necessarily indicates a close interrelationship between these events. Evaluation of available evidence leads to the recognition that an appreciable time interval exists between the emplacement of the igneous intrusive and the formation of associated ore deposits. During this interval known portions of the intrusive are completely solidified, highly differentiated magma facies are injected as dikes, and important faulting occurs, which may fracture and shatter the solidified intrusive body. The highly differentiated dike types could only have originated in some deep portion of an underlying plutonic body that had reached an advanced stage of magmatic differentiation. Appearing after these dikes, the mineralizing solutions may likewise be presumed to have originated at great depth. Certainly no source for these solutions can be found in near-by portions of the intrusive igneous body. The association of igneous intrusives and clustering ore deposits must be recognized as resulting from structural control. The emplacemerit and the subsequent solidification and cooling of the intrusive set in operation forces that are responsible for the favorable structural disturbances that control the mineralized district. The emplacement of the body of fluid magma weakens the crustal rocks to the extent that failure due to strains originally present in the rock body may occur. Faulting of any type and of any magnitude may be the result. Subsequently, owing to the change of state from fluid magma to crystalline granitic rock, volume decreases approximating 10 Per cent may Occur, with resultant shrinkage and collapse within the rock body. Following solidification, thermal contraction, induced by cooling of the rock body, causes a further volume reduction of 6 per cent. This thermal contraction, extending over a lengthy period of time, results in a succession of minor fault movements. These small fault movements, occurring progressively throughout the period of mineralization, are responsible for maintaining the permeability of the rock body, without which access of the mineralizing solutions and the formation of the ore deposits of the mineralized district would be impossible. Introduction A proper understanding of the causes that have localized our mineralized districts should be of considerable value to geologist and engineer alike. under current conditions the known ore reserves of productive mining camps are being rapidly depleted. Although ore of the future will be derived in part from deposits now known and from Ore bodies that are still to be discovered within the limits of productive mining districts, in part at least it must come from mineralized districts whose existence or importance yet remain to be recognized. The mining geologist is thus faced with two problems of paramount importance: (I) the location of new ore bodies within known mineralized areas and (2) the location of new mineralized districts within whose confines, previously unknown, valuable Ore deposits may occur. Any contribution to our knowledge concerning the causes for the localization of mineralized districts

Jan 1, 1949

By R. W. Nelson

The theoretical basis is presented for energy dissipation methods of measuring permeability in saturated heterogeneous media. Analysis starts with the equation for single-phase flow in heterogeneous porous media which is a first-order partial differential equation in the unknown permeability. This equation is reduced to a system of characteristic equations useful in deriving a differential expression for the permeability as a function of the known potential distribution. For steady flow systems the expression is integrable, giving the permeability integral for direct calculation of the distribution along successive streamlines. The boundary condition in permeability is presented and includes a discussion of the special requirement to assure uniqueness. Theoretical results and necessary computations are incorporated into two general computer programs capable of determining the permeability distribution in two- and three-dimensional steady flow systems. Results are then presented for an energy dissipation analysis using the methods and soltware to determine a field permeability thickness distribution. INTRODUCTION Theoretical work leading to the description of fluid flow in heterogeneous porous media has developed slowly and somewhat sporadically, although the areas of engineering applications predominantly involve flow in nonhomogeneous media. The lack of accurate and economical methods for measuring field permeability distributions has been a major limitation to realistic description of natural flow systems. The economical measurement of permeability using energy dissipation methods may overcome this limitation. Among other things, any permeability measurement method involves consideration of energy dissipation; as used here, "energy dissipation method" denotes the following general approach. The areal energy distribution is measured on an existing flow system in porous media. Then through appropriate analysis of the dissipation of energy in the flow system, the permeability distribution is determined throughout the region using the minimum boundary conditions required to assure a mathematically unique result. This paper presents the theoretical basis for such a method, as well as the techniques and computer software needed to carry out the analysis. The method and techniques are then used in a preliminary field application. EQUATIONS DESCRIBING FLOW IN HETEROGENEOUS MEDLA Heterogeneous as used here implies differing in kind, having unlike quantities or possessing different characteristics. Accordingly, a heterogeneous porous medium has unlike quantities or differing characteristics at different locations. More precisely, if a porous medium is heterogeneous with respect to some property, then that property is functionally dependent on the spatial location. (Media properties are considered here as macroscopic.) Specifically considering permeability k,** then k = G(x, y, z) ,............(1) or the permeability is a scalar function G of the location (x, y, z). Spatial variation of several other properties, of which porosity, dispersivity and medium compressibility are but a few, is implied by the broad title of heterogeneous porous media. The term will be used hereafter to imply only heterogeneity with respect to permeability. The porous medium is considered isotropic as implied by G being only a scalar function. Anisotropy

Jan 1, 1969

By J. Murray Riddell, Arthur E. Anderson, Grover J. Holt

OUT of the depths of each business cycle we emerge with a stimulus for greater efficiency and a realization of progress in industrial technique. The recent years have not been an exception to this rule, and in retrospect we sense that significant advances have been made in mining practices on the Mesabi Range, with emphasis on speed of production and economy of operation. A survey of such changes does not reveal anything that is fundamentally or basically new, but it is apparent that ideas and machines that have found wide application in industry elsewhere, with necessary modifications, are being put to productive use in mining iron ore. Innovations in transporting and conveying ore from the open pits stand out with greatest prominence, so that, in the main, it will be with these features that this paper will treat, in the review of progress made to this date. The late years have witnessed the development of small deposits for open-pit operation, the cleaning up of pits nearing exhaustion, and in two large operations the approach to the limit for haulage by steam locomotives, owing to grades, making it necessary to recover the ore in slopes, track benches and below the power-shovel limit by a milling and scram operation. For several years small standard-type dump trucks have been used in clean-up or scram operations within the pits, but during the seasor1 of 1936 the first effort was made to use heavy truck haulage in the transportation of stripping and iron ore. The new units in use today vary from 15 to 20 tons in capacity, and are equipped with powerful gasoline or Diesel engines and supplemented by trailers or wagons on rubber or crawler treads. The Diesel engine finds favor with most operators because of fuel economy. These units develop upward of 125 hp. in the 15-ton trucks. The speed of these trucks varies from 2 miles per hour in low gear to 35 in high gear. The transmission affords 12 speeds forward and 3 speeds in reverse.

Jan 1, 1938

By Noel H. Stearn

OF the many instruments devised for the measurement of magnetic anomalies, the ordinary dip needle, by virtue of its superior simplicity of construction, facility of manipulation, and definiteness of interpretation, seems to merit serious attention as the instrument most readily applicable to the detection of magnetic anomalies of the higher order of magnitude. In spite of the fact that it has been used for many years for the discovery of iron ore in Europe and in the Lake Superior region of America, its capabilities as a geological instrument have not yet been thoroughly plumbed. The Wisconsin Geological Survey, under Dr. W. 0. Hotchkiss, E. F. Bean, and H. R. Aldrich, has been most thorough in developing the technique of the instrument, and the results it has obtained have aroused a general interest in a more widespread use of geomagnetics as an exploration method and the dip needle as a geological instrument. The simplicity of the instrument is an especial advantage, as it can be used by anyone, regardless of his technical training; but to insure useful results not only is a knowledge of the background of geomagnetics necessary but also an understanding of the principles of the instrument itself. Principles of the Dip Needle The major feature of the dip needle is an elongated magnet suspended with fixed bearings in such a way that it can move in a single plane. If the point of suspension were exactly at the center of gravity of the magnet, the instrument would be identical with the "dip circle" or "dipping needle" of terrestrial magneticists, and as such could be used to determine variations in the inclination of the earth's magnetic field when observed in the plane of the magnetic meridian. The dip needle, however, differs from the "dip circle" or "dipping needle" in having an adjustable counterweight affixed to one end of the magnet. This counterweight serves to balance the magnet at an angle to the inclination of the earth's field when the instrument is oriented in the plane of magnetic

Jan 1, 1929

By Edward J. Harvey

Joplin, one of the most famous zinc mining camps of a bygone era, is today experiencing a healthy growth in manufacturing enterprises. Manufacturing requires water, and knowledge of its availability and quality often is the main factor in location of industry. For this reason in January 1964, on the suggestion of the former State Geologist, Dr. Thomas R. Beveridge, a study of the water resources of the Joplin District was undertaken as a cooperative effort of the Missouri Geological Survey and Water Resources now under the direction of Dr. William C. Hayes and the U. S. Geological Survey. The project area is in southwestern Missouri on the Springfield Plateau and is bordered on the west and north by the Osage Plains of Kansas and Western Missouri, (fig. l). Upland altitudes rise from 900 feet above sea level in the west to 1400 feet in the east. The countryside is rolling to moderately hilly and much is excellent farmland.

Jan 1, 1965

On August 22, 1966, just 20 months after writing sales agreements with Japanese steel mills, Hamersley Iron Pty Ltd made its first contractual shipment of 52,000 tons to Yawata Iron and Steel Co Ltd. As world news, the event was not spectacular. But to mining men it represented an astonishing achievement. Twenty months of feverish effort and the expenditure of more than $100 million had created a large open-pit iron ore mine, a crushing plant, storage and load-out facilities for sized ore, and a supporting township at Mt Tom Price; a 182-mile standard gauge railway; and port and loading facilities for a nominal loading capacity of 6000 tph as well as a port town, Dampier, on King Bay. The project was executed in the sparsely inhabited, arid, dissected-plateau country of the Hamersley Range in the northwest sector of Western Australia. Hamersley, 60% owned by Conzinc RioTinto of Australia Pty Ltd and 40% by Kaiser Steel Corp, holds sale contracts for ore and pellets valued at $770 million. The main contracts are with the Japanese, who are to be supplied with 65.5 million tons of ore during the 16 years from August 1966 to August 1982 and 18 million tons of pellets over a 10-yr period beginning in early 1968. Of lesser importance at this time, but presaging trends, are contracts for a total of nearly 1.5 million tons to be shipped to England and Western Europe during the years 1966-68. A pellet plant with a capacity of 2 million tpy is now under construction at Dampier and is to be on stream early next year. Another interesting project for which the plans are set, is a desalination plant for sea water to supply industrial requirements and potable water for the town of Dampier.

Jan 5, 1967

By D. W. Richardson

This Bureau of Mines publication provides the enthalpy of formation of malachite [Cua(COs)(OH)2] as determined by hydrochloric acid solution calorimetry. At 298.15 K the enthalpy of formation from the component oxides is -15.l0±0.30 kcal/mole and from the elements, -251.9±0.5 kcal/mole.

Jan 1, 1974

Previous studies on the blast furnace raceway zone have been undertaken at three levels of scale, namely: laboratory models at low temperature, hot models which simulate coke combustion in the zone, and tests performed on operating and dismantled blast furnaces. This paper reviews the results of this published work on raceways in order to illustrate the factors which affect the raceway shape, size and combustion characteristics. As a result of the work it has been established that raceways are influenced by blast parameters such as velocity, temperature and chemistry, as well

Jan 1, 1981

By Gregoire Gutzeit

THE development reported in this paper was begun by the author a number of years ago, while he was a lecturer on complex chemistry and metallurgy at the University of Geneva, Switzerland, and in charge of that institution's research laboratory. Completion of the development and reduction to practice did not occur until last year at the Westport mill, laboratories and testing plant of the Dorr Company, where this method is now in general use for identifying and localizing the mineral constituents of both metallic and nonmetallic ores. It has proved to be a practical tool of the metallurgical staff at the Westport mill, devising unusual milling flowsheets for complex and refractory ore bodies. In a number of instances the findings have been successfully used as fundamental factors in the design and specification of complete metallurgical plants. Seven examples of the use of this method in solving practical milling problems are included in this paper. GENERAL OUTLINE The microscopic study of an ore, at first only of scientific interest, has proved extremely useful both in practical geology and in ore dressing. The binocular magnifying lenses for rough observation of the products of an ore-dressing plant have been in use for a long time; but only within the last few years has a systematic microscopical examination of ore samples become a normal tool of any research laboratory dealing with ore-dressing problems. Such an investigation avoids considerable loss of time as well as empirical trials and useless experimentation. It will generally indicate the correct grinding and often will suggest the proper method of treatment. The petrographic determination of transparent minerals in thin sections, or even in grains, has been perfected, and very accurate methods have been devised to meet any requirement, such as Feodorof's rotating stage on the petrographic microscope. Almost all transparent minerals can be positively identified by their optical properties; i.e., isotropism, anisotropism, color, pleochroism, refractory index, cleavage, crystal form, birefringence, and others. The identification of opaque minerals is a much more difficult problem and can be done only by using polished specimens. Unfortunately, most of the valuable metallic ores, and even some of the nonmetallic ones, are not transparent; therefore it has been necessary to develop a special technique for the determination of these minerals. Some optical properties-for instance, isotropism, anisotropism, color, cleavage, reflecting power-are often adequate in roughly classifying the mineral. Only "reflecting power" is a measurable value, provided special photometric equipment (ocular photometer or Orcel's photoelectric cell) is available. The other optical properties mentioned are more or less relative,

Jan 1, 1942

By Batric Pesic

Reactions of metallic iron were studied in several different aqueous solution systems: water, medium salt solution used for the growth of T ferrooxidans, ferric iron solution and solution containing T ferrooxidans. Each system was studied under abiotic and biotic conditions in the presence of T ferrooxidans and as a function of pH, particle size of iron powder, temperature, ferrous and ferric iron concentrations. It was found that metallic iron reacts with water differently than does with ferric iron in water. Surprisingly, T ferrooxidans were non-functional in the dissolution of metallic iron. Also, the reactions of metallic iron with pure water were indistinguishable from the reactions with water containing medium salts for bacterial growth. The reactions with ferric iron were also independent of medium culture compounds. The mechanisms of metallic iron reactions with ferric ions are different from the mechanisms of metallic iron reactions with water.

Jan 1, 2001

By Harold B. Ewoldt

The Appalachian Ores Co., Sweetsprings, W. Va. was a small but persistent producer of manganese ore for several years prior to 1942. Most of the ore mined was hard, nodular psilomelane, with some pyrolusite and, wad, occurring in clay. The Bureau of Mines started an investigation of the area in January 1942 and completed the work in May 1942. Twenty-four churn-drill holes were bored, aggregating 2,084 feet. A total of 420 feet of test pits was sunk on selected drill holes to check the churn-drill sampling. Twelve drifts and crosscuts aggregating 139 feet were driven from the bottom of test pits to investigate concentrations of manganese nodules. Three hundred sixty-six churn-drill samples and 102 other samples were sent to Bureau laboratories for analyses. Beneficiation tests were conducted in the Burp.au of Mines laboratory in Rolla, Mo. Results of testing 10 samples indicated that approximately 80 percent of the material in crude ore could be discarded by log washing. Gravity tests indicated 'that 55 percent of the total manganese in the crude ore was recoverable as a gravity concentrate averaging 34.6 percent manganese.

Jan 1, 1949

By Ira B. Joralemon

Neighboring mines, like men who live in the same environment, often assume similar characteristics. In the Bridge River area of the Lillooet district in central British Columbia there is a remarkable exception to this rule. The Pioneer mine has a simple fissure over 3000 ft. long, with no faults of more than a few feet and with only minor variations in width; the Bralorne mine, 2½ miles away at the other end of the same intrusion, has developed one of the most intricate vein and fault systems in the West. Hinged faults displace the main vein for hundreds of feet, and sometimes become valuable veins themselves. The width of ore varies in a few yards from 2 to 60 ft. Changes in grade of ore are just as abrupt. The rocks that follow the veins or are cut by them often grade into one another or into the ore with no definite contacts. Although the complexity of the structure has left many problems unsolved, the development has indicated a fascinating geological pattern. The Bralorne is in the eastern portion of the Coast Range, 55 miles by spectacular mountain road from the Pacific Great Eastern Railway station of Bridge River. The adit tunnel runs easterly from Cadwallader Creek, a tributary of Bridge River that flows into the Fraser River. Steep mountains rise from 3300 ft. elevation above sea level at the creek to peaks and ridges at 8000 to 9000 ft. altitude. The lower slopes are heavily wooded while above 5000 ft. bare rocks, glaciers and snow-fields extend far above timber line. See Fig. 1. Story of the Bralorne The Lorne claim, staked in 1897, was one of the earliest lode locations in the Bridge River district. At that time it was 70 miles by steep and treacherous trail from the railway. For the next 15 years Arthur Noel, Will Haylmore and other local prospectors mined the small, irregular, oxidized quartz veins to a maximum depth of 200 ft., and treated the ore in arrastres and later a five-stamp mill. The total production to 1912 was only $55,000. Noel and associates later formed the Lorne Amalgamated Mines Co., which they worked in a desultory way until 1925. Increasing sulfide and arsenide content in the veins

Jan 1, 1935

By Ira B. Joralemon

Neighboring mines, like men who live in the same environment, often assume similar characteristics. In the Bridge River area of the Lillooet district in central British Columbia there is a remarkable exception to this rule. The Pioneer mine has a simple fissure over 3000 ft. long, with no faults of more than a few feet and with only minor variations in width; the Bralorne mine, 2½ miles away at the other end of the same intrusion, has developed one of the most intricate vein and fault systems in the West. Hinged faults displace the main vein for hundreds of feet, and sometimes become valuable veins themselves. The width of ore varies in a few yards from 2 to 60 ft. Changes in grade of ore are just as abrupt. The rocks that follow the veins or are cut by them often grade into one another or into the ore with no definite contacts. Although the complexity of the structure has left many problems unsolved, the development has indicated a fascinating geological pattern. The Bralorne is in the eastern portion of the Coast Range, 55 miles by spectacular mountain road from the Pacific Great Eastern Railway station of Bridge River. The adit tunnel runs easterly from Cadwallader Creek, a tributary of Bridge River that flows into the Fraser River. Steep mountains rise from 3300 ft. elevation above sea level at the creek to peaks and ridges at 8000 to 9000 ft. altitude. The lower slopes are heavily wooded while above 5000 ft. bare rocks, glaciers and snow-fields extend far above timber line. See Fig. 1. Story of the Bralorne The Lorne claim, staked in 1897, was one of the earliest lode locations in the Bridge River district. At that time it was 70 miles by steep and treacherous trail from the railway. For the next 15 years Arthur Noel, Will Haylmore and other local prospectors mined the small, irregular, oxidized quartz veins to a maximum depth of 200 ft., and treated the ore in arrastres and later a five-stamp mill. The total production to 1912 was only $55,000. Noel and associates later formed the Lorne Amalgamated Mines Co., which they worked in a desultory way until 1925. Increasing sulfide and arsenide content in the veins

Jan 1, 1935

Neighboring mines, like men who live in the same environment, often assume similar characteristics. In the Bridge River area of the Lillooet district in central British Columbia there is a remarkable exception to this rule. The Pioneer mine has a simple fissure over 3000 ft. long, with no faults of more than a few feet and with only minor variations in width; the Bralorne mine, 2½ miles away at the other end of the same intrusion, has developed one of the most intricate vein and fault systems in the West. Hinged faults displace the main vein for hundreds of feet, and sometimes become valuable veins themselves. The width of ore varies in a few yards from 2 to 60 ft. Changes in grade of ore are just as abrupt. The rocks that follow the veins or are cut by them often grade into one another or into the ore with no definite contacts. Although the complexity of the structure has left many problems unsolved, the development has indicated a fascinating geological pattern. The Bralorne is in the eastern portion of the Coast Range, 55 miles by spectacular mountain road from the Pacific Great Eastern Railway station of Bridge River. The adit tunnel runs easterly from Cadwallader Creek, a tributary of Bridge River that flows into the Fraser River. Steep mountains rise from 3300 ft. elevation above sea level at the creek to peaks and ridges at 8000 to 9000 ft. altitude. The lower slopes are heavily wooded while above 5000 ft. bare rocks, glaciers and snow-fields extend far above timber line. See Fig. 1. Story of the Bralorne The Lorne claim, staked in 1897, was one of the earliest lode locations in the Bridge River district. At that time it was 70 miles by steep and treacherous trail from the railway. For the next 15 years Arthur Noel, Will Haylmore and other local prospectors mined the small, irregular, oxidized quartz veins to a maximum depth of 200 ft., and treated the ore in arrastres and later a five-stamp mill. The total production to 1912 was only $55,000. Noel and associates later formed the Lorne Amalgamated Mines Co., which they worked in a desultory way until 1925. Increasing sulfide and arsenide content in the veins

Jan 1, 1935

By Ira B. Joralemon

Neighboring mines, like men who live in the same environment, often assume similar characteristics. In the Bridge River area of the Lillooet district in central British Columbia there is a remarkable exception to this rule. The Pioneer mine has a simple fissure over 3000 ft. long, with no faults of more than a few feet and with only minor variations in width; the Bralorne mine, 2½ miles away at the other end of the same intrusion, has developed one of the most intricate vein and fault systems in the West. Hinged faults displace the main vein for hundreds of feet, and sometimes become valuable veins themselves. The width of ore varies in a few yards from 2 to 60 ft. Changes in grade of ore are just as abrupt. The rocks that follow the veins or are cut by them often grade into one another or into the ore with no definite contacts. Although the complexity of the structure has left many problems unsolved, the development has indicated a fascinating geological pattern. The Bralorne is in the eastern portion of the Coast Range, 55 miles by spectacular mountain road from the Pacific Great Eastern Railway station of Bridge River. The adit tunnel runs easterly from Cadwallader Creek, a tributary of Bridge River that flows into the Fraser River. Steep mountains rise from 3300 ft. elevation above sea level at the creek to peaks and ridges at 8000 to 9000 ft. altitude. The lower slopes are heavily wooded while above 5000 ft. bare rocks, glaciers and snow-fields extend far above timber line. See Fig. 1. Story of the Bralorne The Lorne claim, staked in 1897, was one of the earliest lode locations in the Bridge River district. At that time it was 70 miles by steep and treacherous trail from the railway. For the next 15 years Arthur Noel, Will Haylmore and other local prospectors mined the small, irregular, oxidized quartz veins to a maximum depth of 200 ft., and treated the ore in arrastres and later a five-stamp mill. The total production to 1912 was only $55,000. Noel and associates later formed the Lorne Amalgamated Mines Co., which they worked in a desultory way until 1925. Increasing sulfide and arsenide content in the veins

Jan 1, 1935

By Kermit Allen

Storing natural gas in solution mined salt cavities appears to be one of the more promising methods being considered by some major gas transmission companies for meeting peak demands. Historically, these companies have been faced with the problem of meeting peak demands when the source of natural gas is located hundreds of miles from the marketing area. Transcontinental Gas Pipe Line Corporation's position was further complicated because some of its offshore Gulf Coast gas supply wells may have to be shut in during hurricane alerts. Transco's solution was to construct. solution mined salt storage caverns adjacent to its pipeline near Eminence, Mississippi. (See Figure 1.) In 1965, Fenix & Scisson, Inc., was engaged by Transco to evaluate the feasibility of storing natural gas in caverns dissolved from salt at selected locations along Transco's pipeline to the East Coast. In June of that year a report was submitted to Transco concluding that this proposal was feasible and recommending several potential sites for storage development. Additional engineering and geological studies followed and in March 1968 the Eminence Salt Dome site was selected and storage construction began that year.

Jan 1, 1971

By Rodolfo Nava

El presente texto señala las innovaciones tecnológicas en los sistemas de soporte de las minas Industrial minero México S.A. con el objetivo de incrementar los factores de seguridad y productividad. Dichos factores son: marcos de madera, marcos de acero, anclas de concha de expansión, anclas de varilla corrugada y cemento inyectado a presión, anclas de cable de acero y cemento inyectado a presión, tubos ranurados de fricción, anclas de varilla corrugada y cartuchos de resina, concreto lanzado; solo o en combinación con alguno de los tipos de anclaje anteriormente citados. En ese sentido, se considera las experiencias desarrolladas en la Unidad Taxco, con los tubos ranurados de fricción, que es el tipo de anclaje de más reciente aparición en el mercado de los Estados Unidos.

Mar 1, 1981

The discovery of copper and nickel sulphides in the Riwaka Complex in 1967 led to considerable exploration activity by a number of companies. Various exploration techniques used by these companies are summarised and discussed. Activity of these companies shows that mineralisation is mainly confined to the southern, ultramafic section of the Riwaka Complex where geological mapping recognised sixteen units within, or associated with the Riwaka Complex. Significant pyrrhotite, pentlandite chalcopyrite mineralisation is restricted to biotite feldspar pyroxenites and to clinopyroxenite units. Lesser and more erratically distributed pyrite chalcopyrite pyrrhotite mineralisation occurs in poikilitic pyroxene hornblendites, melanocratic gabbros, and in marginal diorite lenses. It is suggested that a linear belt of layered ultramafic and mafic rocks described in Fiordland by Williams (1974) may be a southern extension of the Riwaka Complex. The Riwaka Complex has been classified as belonging to the Picritic subtype, (Tholeiitic suite), of Naldrett and Cabri, (1976), and as such it is concluded that it exhibits substantial potential for the discovery of economic copper and nickel deposits. It is considered that the complex is a multiphase differentiated intrusion emplaced in a major tensional fracture zone that developed in a relatively stable tectonic environment, namely a succession of middle Paleozoic shallow water shelf sediments. Based on sparse available evidence it is suggested that the Riwaka Complex was intruded in the lower to middle Permian. It is further suggested that the tensional fracturing was initiated by the onset of subduction process which were responsible for the development of the Permian volcanic arcs and ophiolite belt in the north west Nelson area.

Jan 1, 1977

By William J. Harris, Morris Cohen

INTRODUCTION THE recent application of lineal analysis1,2 to the austenite-martensite reaction has made possible a quantitative study of the kinetics of this transformation during rapid cooling. Martensite range curves can thus be constructed to portray the onset of the reaction at [M.] and its subsequent progress as a function of temperature down to and below the ambient. It now seems in order to investigate other aspects of the martensite transformation, using this quantitative method of approach. One of the least understood characteristics of the austenite-martensite reaction is that of stabilization which has been defined by Troiano and Greninger3 as "a lowering of [M.], resulting from aging, without change in chemical composition of the parent solid solution." In other words, if the hardening quench is arrested at a predetermined subcritical temperature (Th) for a sufficient period of time, more austenite may be retained at a given lower or reference temperature (Tr) than if the steel had been cooled directly and rapidly to Tr in the first place. For the purposes of the work at hand, the extent of stabilization produced by the isothermal treatment at Th, is measured explicitly in terms of the excess austenite [(S)] that exists in the steel at Tr, over and above the amount that is normally present after direct quenching to Tr. Tr is conveniently taken to be room temperature, but this choice is not essential and is sometimes undesirable. The holding temperature (Th) may be above or below [M], and still cause stabilization depending upon the chemistry of the austenite. Stabilization has been found to occur in the presence of bainite4 and of martensite5,6,7,8 as well as in the absence of either.9 The phenomenon of stabilization is not concerned with (and may even be obscured by) ferrite formation or any other type of phase change occurring at Th that alters the chemistry of the remaining austenite. Such a structural change would obviously influence the martensite transformation during subsequent cooling. Stabilization, however, is more subtle; it appears to manifest itself without detectable variation of the austenite composition, whether in the presence or absence of transformation products. There are relatively few direct references to stabilization in the literature. The stabilizing effect of room temperature aging and tempering on the subzero transformation of retained austenite has been clearly shown in plain carbon,6.8 low alloy 6.7.8 and high alloy tool steels.10,5 Starting with the as-hardened steel, the degree of stabilization increases with tempering time and temperature through

Jan 1, 1948

In the U.S. coal mining industry, a large cohort of miners is at or nearing retirement age. As these miners retire, there will be a need to hire and train thousands of new and most likely younger workers. Moreover, a large portion of safety trainers will also require replacement due to retirement. In a speech before the U.S. House of Representatives (2004), Bruce Watzman, Vice President for Safety, Health and Human Resources for the National Mining Association said, “[W]e will need to replace a major portion, approximately 50%, of the underground coal mining workforce within the next 5–7 years.” The large influx of new mine workers, along with the deficit in safety trainers, creates the challenge to provide consistent and effective safety training. Given the expected high turnover of the mining workforce, it is very likely that incoming workers will have much less experience than those leaving the workforce. Unfortunately, inexperienced miners have been shown to incur the highest rate of injuries. The piece of machinery most associated with these injuries is the roof bolting machine, which accounts for 56% of machinery-related injuries in underground coal mining. The National Institute for Occupational Safety and Health (NIOSH) has released a new report entitled “Roof Bolting Machine Operators Skills Training for a Walk-Thru Roof Bolter: Trainer’s Guide” (IC 9489). It is designed to help safety trainers develop struc-tured training for new operators of walk-thru bolting machines. This resource will help trainees learn, understand, and apply knowledge and skills. Included in the trainer’s guide are the following tools: [ ] a six-part DVD video series, a skills check survey, talking points, and a complete job training analysis. Also included is an exercise to help trainees learn more about their mine’s roof control plan, as well as a list of supplemental training and reading materials. On-site trainers can modify this guide to fit their particular mine conditions, machines and equipment, and work procedures. The goal of every coal mine safety professional is to increase safety awareness and make mines a safer place to work. The Walk-Thru Bolting Machine Trainer’s Guide will help teach new miners skills to create a safer working environment that will ultimately prevent or reduce on-the-job injuries. Safety trainers can also use the ideas and concepts from this guide to develop their own training skills for the safe operation of other pieces of underground coal mining equipment.

Jan 6, 2007