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By G. L. Humphrey

Although silicon carbide has been an important manufacture refractory for many years, knowledge of its thermodynamic values has been seriously lacking. In fact, some of the very properties that make it a useful substance, particularly chemical inertness, obstruct determination of its heats of formation and reaction. This paper reports the results of new measurements of the heats of combustion and formation, low-temperature heat capacity, entropy at 298.16°K., and heat-content and entropy increments between 298° and l,800°K. Two varieties of silicon carbide were studied -the common, hexagonal (type II) and cubic. The data are combined to obtain heat and free-energy-of-formation functions, which are given in tabular form. It is shown that the cubic variety is the more stable at temperatures to at least 1,800°K but, because of the inherent difficulties and errors in the heat-of-formation determinations at 298°K, it was not found possible to specify the free-energy difference accurately. The mechanism of silicon carbide formation from silica and carbon is not known and is not ascertainable from thermodynamic data. It appears improbable, however, that it can be a single-step reaction. Some reactions involving silicon monoxide gas and metallic Silicon, as possible intermediates in silicon carbide formation, are considered and shown to be thermodynamically feasible.

Jan 1, 1952

By Gordon R. Harris, Raymond Chalk

Descriptions of typical pulp and paper manufacturing processes are presented, with particular emphasis on the use of minerals and derived products. Some consideration is given to the future demand for these minerals by the pulp and paper industry. Possible influences of techno-logical change and social legislation are suggested and their effect on saltcake demand by the pulp industry is discussed. Predictions are made regarding trends for new and existing paper products.

Jan 1, 1968

By D. B. Dreisinger

The zinc pressure leach process developed by Sherritt Gordon, Ltd. permits the direct leaching of sulphide concentrates according to the overall reaction, ZnS +H,zS04 +402.+ZnS04+H20 +S0 The kinetics of the leach are affected by three rate controlling steps; ( l) oxygen mass transfer from the gas to the leach solution, (2) homogeneous oxidation of ferric ion to ferric ion by dissolved 011.ygen and (3) ferric ion leaching of zinc sulphide in the presence of a sulphur dispersing detergent (lignin sulphonic acid). Fundamental studies have been conducted to identify the factors that influence the kinetics of each individual rate controlling step. Oxygen mass transfer studies have been directed toward optimization of the agitator configuration for solids mixing and gas pumping from the atmosphere above the leach slurry. The rate of ferrous oxidation by molecular oxygen and the rate of zinc sulphide leaching by ferric ion have been studied over a wide range of temperature and solution compositions. The study of zinc sulphide leaching by ferric ion was supplemented by a series of interfacial tension measurements in the liquid sulphur - zinc sulphate solution system. The various kinetic studies have been summarized in terms of the importance of each rate to the performance of the process.

Jan 1, 1990

By E. R. Maize

This report is the second of a series on roof movement in coal mines. The first (R. I. 3355)4/ dealt with convergence of roof and floor and movement of the surface accompanying and following extraction in a mechanized mine in which retreat of rib lines was rapid. The studies reported herein were made in a mine in which all the coal is loaded by hand, and movement of the rib lines was much slower in consequence. In choosing a site for this work, it was decided that the mine selected should have natural conditions akin to those of the first study and entirely different methods of working. To this end a cooperative agreement was made with the Crucible Fuel Co. through W. J. Whitaker, secretary, for conducting the work in the company's Crucible mine, operating in the Pittsburgh bed in Greene County, Pa. This paper gives an account of the methods used in the investigation, excerpts from the data obtained, and such generalizations as can be made.

Jan 1, 1939

By E. R. Maize

This report is t e second of s series on roof movement in coal mines. The first (R. I. 3355)4/ dealt with convergence of roof and floor and movement of the surface accompanying and following extraction in a mechanized mine in which retreat of rib lines was rapid. The studies reported herein were made in a mine in which all the coal is loaded by hand, and movement of the rib lines was much slower in consequence. In choosing a site for this work, it was decided that the mine selected should have natural conditions akin to those of the first study and entirely different methods of working. To this end a cooperative agreement was made with the Crucible Fuel Co. through W. J. Whitaker, secretary, for conducting the work in the company?s Crucible mine, operating in the Pittsburgh bed in Greene County, Pa, This paper gives an account of the methods used in the investigation, excerpts from the data obtained, and such generalizations as can be made.

Jan 1, 1939

By K. Awuah-Offei

An aggregate plant may have difficulty balancing product stockpile inventories if hot mix asphalt (HMA) design engineers do not account for aggregate inventory during mix design. Yet HMA design engineers do not, often, take this into consideration during asphalt mix design. This is due to the lack of tools that enable the lab technician or engineer to optimize the mix for good performance while helping the aggregate plant manage its stockpile inventory levels and reducing the aggregate cost. This work presents a linear programming model of the asphalt mix design problem that helps aggregate plants manage their inventory levels while meeting HMA customer demands. The algorithm is implemented in MATLAB as an Asphalt Mix Design Optimization (AMIDO) program. The program is successfully validated with real-life data. The results show that AMIDO can be used to successfully produce any mix design while reducing the cost of aggregates by using the cheapest stockpile materials. The application of AMIDO will increase aggregate plant profitability when serving HMA customers and could potentially be modified for concrete aggregate customers too.

Jan 1, 2009

By R B. Stewart

Where pasture production is the intended land use of the areas to be reclaimed, the creation of a suitable growing +medium is a major objective. To achieve this land reclaimers require a sound understanding of the proposed mining plan and a knowledge of the physical, biological and chemical properties of materials intended for resurfacing disturbed areas. Where the original soil is not being replaced in its natural state, research is usually required to determine an alternative growing medium. Results from field research conducted on waste material from the Waihi Gold mine are reported with emphasis on the significance of soil depth in relation to pasture production in this environment.  Problems in extrapolating field research to large scale operations are also considered.   Essentially the requirements for successful pasture production, on surrogate growing medium, are akin to conventional approaches used in New Zealand in the development of unimproved agricultural land. High inputs of fertiliser are initially needed, especially where volcanic soil is used, and careful management of pastures and soils is required to minimise soil erosion and create a sustainable system. In the first three to five years of pasture production, grazing use of the land requires to be dictated by pasture availability and soil conditions and not by animal feed requirements. The use of light stock (young dairy or sheep) is recommended.   Successful land restoration requires a team approach by a range of cooperative specialists including engineers, soil scientists, farm managers, agricultural contractors, landscape architects and environmental officers.

Jan 1, 1991

By M. W. Airth

ON THE 6TH JULY in the year 1953 an announcement was made to the public that touched off one of the greatest staking rushes in the history of mining in Canada and resulted, in tl1e space of a few short years, in the development of the greatest reserves of uranium-bearing ore in the world. It was ?On this date that the famous "Blind River back-door staking bee" was completed with the acquisition of some 2,000 claims by the Preston East Do me-Technical Mine Consultant teams under the direction of Mr. Franc Joubin and Mr. Robert C. Hart. That story has been told from coast to Coast and is too well known now to re-quire elaboration. Suffice to say that, in the short elapsed time of less tl1an five years from that momentous summer of 1953, three of the Algoma mines are in full production, three more are rapidly nearing full production, five more 1are approaching the production stage, a new hard-surfaced highway, 108, has been built to serve the area, and a brand new, completely planned city, Elliot Lake, is being built to provide the amenities of living to the 22,000 people already in the area.

Jan 1, 1958

By D. O. Kennedy

"INTRODUCTION During the recent war attention was directed to prevent the destruction of American industries by sabotage. By Executive order of Lay 19, 1942, the Bureau of Mines was required to conduct investigations and make recommendations that would prevent loss of production of essential war minerals. The Health and Safety Branch of the Bureau of Lines was able to extend its activities with minimum loss of time to include security surveys of the important mineral facilities in the United States.A Mineral Production Security Division was established in the Health and Safety Branch with funds appropriated for that purpose by Congress in April 1942. From July 1942 to July 1945 engineers of this division, under the direction of D. Harrington, Chief, Health and Safety Branch, and J. J. Forbes, Chief, Mineral Production and Security Division, conducted investigations of 1,560 metallic and nonmetallic mines and associated facilities in accordance with the requirements of the Executive order.PURPOSEAn analysis of losses in the production of minerals shows that failure or destruction of equipment either from deliberate or accidental causes produces essentially the same result. Maximum production is insured by the prevention of subversive activities, fires, and industrial accidents."

Sep 1, 1946

The Gippsland Basin, southeastern Australia, has an Upper Cainozoic history of episodic change of hydrology and the related environment, reflected in the geomorphology and surficial deposits of the onshore basin and the hydrodynamically controlled accumulations of petroleum of the offshore basin. Succeeding this episodic pattern, man through a number of activities, has had a sudden and major impact on the hydrology and the related environment. Activities include those directly affecting the groundwater system, such as extraction of fossil fuels with the consequent threat of land subsidence; irrigation and clearing of vegetation and the consequent effect of salinisation; change of land use and installation of septic tanks with resulting nitrate pollution; damming of streams and the consequent reduction in the frequency of floods with degradation of the biological Environment; de-snagging streams and construction of cutoffs with increased stream erosion, modifying wetlands including drainage, with the consequent degradation of their ecosystems; and increase in phosphate and nitrate inputs to the coastal lakes with the risk of their eutrophication.

Jan 1, 1992

By William A. Sloan

"In smelting operations, finely divided material called ""flue dust"" is carried by the moving gases from the roasters and furnaces; it is partly settled and recovered in the flue system. The flue dust from copper smelters contains a high percentage of copper, usually some gold and silver, and occasionally other valuable metals. It is too valuable to throw away and in present practice is returned to the smelting furnaces for re-treatment. A part of this material again passes out with the gases and forms a circulating dust load in the system. The dust that passesout of the stacks into the atmosphere is an important source of loss in copper smelting. Loss of values also occurs by dust being blown away while in transit from the flues back to the furnace, and of course the greater the amount of rehandling the greater this loss.Dust carried in the gas currents causes corrosion of the roof arches in reverberatory furnaces. Returning flue dust to the furnace increases the quantity of suspended dust. Corrosion reduces the life of the arches and shortens the length of furnace campaigns; also the corrosion of arches limits the temperature at which a furnace may be operated. Every ton of material that must be re-treated in the furnaces reduces correspondingly the amount of new ore or concentrates that could be smelted.As the present tendency is toward finer grinding in flotation plants smaller particles will need to be treated at the smelters, increasing the difficulty of preventing losses in flue dusts. Many schemes and processes for a more economical method of treating flue dust have been proposed or tried, but in the main none of them has been successful."

May 1, 1928

By O. H. Metzger

This is the second of two papers dealing with the construction and use of aerial tramways in the metal-mining industry. The first paper3/described aerial tramways in a general way and discussed the engineering principles used in tramway design. The purpose of this paper is to give a more detailed description of equipment and material rind to discuss construction and operating costs. ACKNOWLEDGMENTS The paper is based largely on data from actual operations. Metal-mine operators from many parts of the United States, Canada, Alaska, and Mexico contributed liberally.

Jan 1, 1940

The C.S.I.R.O. acid alumina process employs the essential steps of digestion, hydrolysis and calcination to produce pure alumina from ores too high in silica or too low in grade for the Bayer process. The two latter stages have been described in some detail previously but the digestion stage requires separate discussion since ores vary widely in composition and reactivity. Kaolinitic clays require roasting to 800°C to render the alumina soluble in the 11 per cent sulphuric acid used in the process while some ferruginous laterites require roasting to reduce the reactivity of iron minerals.The iron content of pregnant solutions is kept at a low figure by digesting at temperatures where the solubilities of ferric oxide or basic ferric sulphates are small. A two-stage, counter-current digestion is necessary to extract a high percentage of alumina from the ores and to produce a basic pregnant liquor with an SO3 : AI 203 ratio of 1'\1 suitable for high temperature hydrolysis. The second stage of digestion, called the modification stage, treats slightly acid liquors with excess of ore in the temperature range 1200-1400C.The first stage operates at 170°-1900C to extract further alumina from modification residues, using recycled acid obtained from later steps of the process. Both temperature ranges are critical for economic operation and for proper control of the iron content of solutions. In batch experiments, 30 min is regarded as a suitable retention time for digestion and modification; ores which require much longer than this are less suitable for the process. Impurities such as silica, and titanium and vanadium oxides are discarded in the residue along with iron oxide, and do not contaminate the final product. Bivalent metallic sulphates such as MgSO4, can build up in the circuit to a very considerable degree without affecting product purity.Comparison with other processes shows that the C.S.I.R.O. process is superior for control of contamination by iron, which is the major problem in acid processes. The pure intermediate product (3Al203.4S03.9H20) is also more convenient for calcination to alumina than the hydrated aluminium sulphate usually recovered in other processes. Detailed cost comparisons must await pilot-plant evaluation of the C.S.LR.O process.

Jan 1, 1964

By C D. Strickland

Western Australia (WA) has been a significant world producer of titanium minerals (rutile, ilmenite and leucoxene) and zircon for over 55 years. In 2010, despite global difficulties, WA accounted for 12 per cent of world production for zircon, ten per cent for ilmenite, and eight per cent for rutile. With downstream processing, titanium minerals (ilmenite, rutile, leucoxene) and zircon exports for 2010 were valued at $511 M (Department of Mines and Petroleum, 2010).Production is dominated by two areas of the Perth Basin, namely the Eneabba and the Bunbury-Capel regions, which are located 240 km north and 200 km south of Perth respectively. Mineralisation is within Cenozoic beach or near shore dune deposits at three broad altitudes related to the present coastline, and two older higher sea-level still-stands. The titanium-zircon minerals presumably were derived from the underlying Mesozoic sediments of the Perth Basin. Contrary to expectations, age dating suggests that the ultimate source of most of this mineralisation was not the adjacent Yilgarn Craton. With the cooperation of industry, the Geological Survey of Western Australia has mapped all known significant titanium-zircon mineralisation within the Perth Basin. This mapping has identified ‘strategic mineral resource protection areas’ that should be set aside for future mining, ‘sterilised’ and ‘mined’ areas that generally do not restrict land use options, and ‘possible strategic resource areas’ which have exploration potential for hosting titanium-zircon mineral deposits.The Perth Basin is currently undergoing rapid residential and industrial development. By informing all stakeholders of the locations of potential mining areas, the titanium-zircon mapping has the ability to reduce future land use conflicts, and facilitate sequential land use planning. Appropriate planning measures are being implemented to ensure that the Western Australia’s titanium-zircon minerals industry remains strong and viable in the future.

Oct 5, 2011

Roof falls in coal mines typically occur in or around intersections and this has not changed in the last two decades. This research develops an improved scientific understanding of stress distribution and associated failure behavior around 4-way and 3-way coal mine intersections. Three-dimensional numerical analyses were performed to determine factors that influence intersection stability. The analyses used Hoek-Brown failure criterion. Failure zones around 3-way and 4-way intersections were developed. Intersection span and horizontal stress have a major influence on intersection stability. For the 4-way intersection, pillar corners across the intersection fail first and lead to progressive failure of immediate roof and floor layers. The mechanism of failure is similar for the 3-way entry but the shape and extension of failed zones differ. Coal ribs mostly fail due to tensile stress, while roof and floor strata fail due to shear stresses. Rib corners fail due to a combination of shear and tensile stresses. In addition to stress distribution; safety factor contours analysis was performed to assess stability of intersections.

Feb 27, 2013

THE art of mine surveying has made very great progress in recent years, and is still advancing, perhaps faster than any other branch of surveying. The scope of the mine surveyor's duties has greatly increased, his instruments and methods have improved, the responsibility of his position is greater, and the end is not yet in sight.It might be supposed that such a steadily growing subject would have an adequate literature, but this is by no means the case and outsiders commonly judge mine surveyors by their text-books. Hardly any condemnation can be too strong for most of these books. The English books truckle to the antiquated and crude methods apparently still in use in England, and thereby largely aid in perpetuating them; they commonly in illustrative examples give the distances in fathoms, feet, and inches; they spend page after page discoursing on instruments that should have been forgotten long ago; they try to antagonize theory and practice by detailing such calculations as that a certain vein will contain 2,003.907 pounds of galena per square fathom, and then reduce this amazing quantity to hundredweights, quarters, and pounds. Nothing can be more unscientific, or, for that matter, less businesslike, than unwarranted assumptions of accuracy; it is, perhaps, the greatest curse of applied science. Here we have a calculation to thethousandth part of a pound, when there is probably an unavoidable error of two hundred pounds. What shall we say of a man who explains how to measure the depths of shafts to the hundredth part of an inch by means of short brass rods screwed together...

Jan 1, 1909

By D. M. Davidson, P. F. Kerr

The Permian Cutler Formation in Kane Creek, Utah bears uranium ore in fissure-type vertical veins. This fissure vein formation and its associated host rock bleaching, weak argillic alteration, and base-metal sulfide mineralization along with the development of hydrothermal minerals, a 60 m.y. isotopic Pb/U age, and well-crystallized uraninite's structural control, give evidence of ore deposition in a hydrothermal environment consistent with Laramide mineralization. Mica polymorph studies indicate first, that temperature during the hydrothermal alteration or subsequent ore deposition did not exceed 200°; hence Cutler deposits are classified telethermal; and secondly, that rock alteration and ore deposition are closely related both in time and space, as is seen in argillic alteration sequence. Ore deposition in an alkaline to slightly acid reducing environment is postulated. Ore textures and mineral associations and distributions also indicate that carbonate complexes may have been transported with the deposing ores. Bleached rock formations are not primary strati-graphic phenomena. Bleaching, or changes in ferric iron content, results from a chemical process involving reduction and conversion of hematite to a soluble aqueous ion. Nearby Chinle bedded deposits (Moss Rack sandstone), containing shale lenses, fossil wood, organic debris and minor fractures, overly the Cutler formation. Chinle ores have a single reported isotopic age of approximately 200 m.y. Their chemical environment is assumed similar to that of the Cutler ores, though slightly more acidic. Two genetic, paradoxically divergent interpretations of the bedded deposits are derived from available spectrographic, petrographic, X-ray and chemical analyses. Kane Springs canyon is located southwest of Moab, Utah, south of the Colorado River and northwest of the Lisbon Valley mining district (Fig. 1). Uranium deposits occur along the northeast flank of a Kane Creek salt anticline where two geologic formations bear ore, the Permian Cutler and the Triassic Chinle. The Cutler deposits' fissure vein formation is an unusual occurrence in the Colorado Plateau. The Chinle deposits appear to be of the normal sedimentary type. Associated with the vein deposits are a number of features, including argillic alteration of sedimentary strata. The minerals of these deposits and their associated features have been studied in detail in a two year program entailing both field and laboratory techniques. STRATIGRAPHY A stratigraphic section of the lithologic units in the Kane Creek area is given in Table I.

Jan 1, 1967

By R. C. Courtney, D. J. Forrester

Modern advances have led to sweep and multibeam bathymetric surveying techniques that yield three-dimensional images of the sea floor and have also produced high-powered personal computers with which to control the data and analyse the results. At Sydney, in Nova Scotia, the topography of the sea floor over the longwall workings was observed before and after mining with a precision echo-sounder in 1987-89, with sweep bathymetry in 1993 and with multibeam bathymetry in 1994-95. The results of the latter programme produced what was probably the first observation of a complete three-dimensional subsidence trough over a longwall panel 2 500 m x 168 m. The subsidence has been quantified to a sufficient degree of accuracy to allow simple trend analysis, which has shown that the pattern and shape of movements are similar to those found elsewhere but with significantly smaller maximum subsidence. A prediction model has been calibrated

Jun 19, 1905

By Kentaro Kuraji

INTRODUCTION Background Tokyo, the capital of Japan, is one of the largest cities of the world. As many as 33 million people live in Tokyo and three neighboring prefectures although the city occupies only 0.6% of the area of the country. The network of Metropolitan Expressways serves as a major artery for daily physical distribution in Tokyo. The Central Circular Route of the Metropolitan Expressway (MECCR) is located innermost among the three circular routes in Tokyo (Figure 1). Once completed, MECCR is expected to drastically mitigate traffic congestion in the central Tokyo area and provide drivers wider varieties of options in route selection. Alleviating congestion is estimated to reduce 400,000 tons of carbon dioxide emissions annually. The eastern and northern sections and part of the western section of MECCR have been completed with the total length reaching 33 km. The western section will be extended southward by approximately 4 km in the spring of 2010. An 11-km-long western section of MECCR that is currently being constructed is composed mostly of tunnels. A large number of power supply, gas supply, telephone, drinking water and sewerage pipes have been placed under the Yamatedori avenue along which MECCR is being constructed. The shield tunneling method has therefore been adopted for constructing tunnels along the route. The method involves the advancement of a shield tunnel boring machine (TBM) through the ground simultaneously assembling segmental rings within the shield. The method not only enables the building of highway tunnels more quickly and efficiently than other methods but also minimizes the effects of construction work on the surrounding area and the environment. Constructing the tunnel using the conventional cut-and-cover method might have required large amounts of time and cost because relocating the numerous objects buried under the Yamatedori avenue might have been necessary during tunnel construction. It was also considered desirable to place the tunnel at a depth of 30 m or more from surface to prevent tunnel construction from adversely affecting railways because the tunnel was expected to cross eleven railways and subways. This is one of the reasons for selecting shield tunneling as an effective method. The shield tunneling method was finally adopted for a length of 7 km in the 11-km western section of MECCR. The shield tunneling method was also employed in the Ohashi Tunnel located southernmost in the 11-km western section of MECCR. This paper describes the construction of the Ohashi Shield Tunnel.

By D. P. Lindroth

The Bureau of Mines is engaged in research on ground probing radars for detection of geologic hazards in advance of mining. Penetration distances and interpretation models depend on the dielectric properties and wave propagation characteristics for coal measure stratified media. Relative dielectric constants and dissipation factors were measured under ambient conditions for Pittsburgh Seam coal measure rock over the frequency range of 20 to 100 MHz by the susceptance-variation method. The rock types measured were representative sedimentary rock located above the Pittsburgh Coal Seam. Extreme values for the computed attenu-ation distance ranged from 1.7 m at 100 MHz for siltstone to 230 m at 20 MHz for a particular limestone.

Jan 1, 1984