Search Documents

By D. J. Bowen

"Abstract -The Great Dyke extends for 540 km along strike, to unknown depth, and varies in width from 3 km to 11 km. Rb/Sr age determinations gives values of approximately 2470 Ma.The Dyke consists of a variety of mafic and ultramafic rocks, many altered to serpentinites. These include, from top to bottom, successions of gabbro/norites, pyroxenites, peridotites/harzburgites, and dunites/picrites.The layers dip in from either margin, steepest at the edges (20°) and flattening toward the central sections. Four separate complexes are present. From north to south these are termed the Musengezi, Hartley, Selukwe and Wedza Complexes, and are described as 'boat-shaped' or 'pig-troughed'. All are similar in petrological sequences. Physiographically, the Dyke is spectacular in the north, where as a mountain range it meets the Zambezi Escarpment. Elsewhere in the central parts there is little surface expression and wide open treeless vleis. Dyke rocks cut through granite and schist belt terrain and are termed 'The Magnesia Belt'.Vast mineral resources exist. These include chrome, asbestos, platinoids, nickel, copper and gold. Up to eleven chrome seams numbered from top to bottom occur in the lower ultramafic sequences. Seams are narrow at 10 cm to 30 cm but of high grade. The platinum occurs 10 m to 40 m below the norite/pyroxenite contact.A 60 m wide zone of Light Sulfide Mineralization (LSM) of Jess than 1% sulfides extends from the lower gabbronorites into the upper pyroxenites. In this LSM, four enriched zones carry up to 5% sulfides. The most widespread is termed the Main Sulfide Zone (MSZ), below which is No. 2, No. 3 and No. 4 Sulfide Zones. The MSZ carrying pyrite, pyrrhotite and chalcopyrite is a multi­ element ore with components of PGE (Pt-Pd-Rh), nickel, copper and cobalt, and gold and silver.Extensive exploration programs have been carried out and the intention is to begin large-scale mining. However, with Russia supplying metals to the western markets, South Africa's cutback on production, and an end to the Cold War, delays have arisen."

Jan 1, 1994

By J. L. Llanca

The New Level Mine project (NLMP), the planned underground expansion of the El Teniente mine in Rancagua, Chile, is expected to reach a daily extraction rate of 137 to 180 ktpd upon achieving full capacity. Production is planned to start in the year 2017 and the current plan is to meet that target through two development phases, from the year 2012 to 2014 and from the year 2015 to 2017. To achieve the 2012 to 2014 underground development schedule, the ventilation requirements have been estimated in the range of 189 m3/s (400 kcfm), and cannot be made available without significant modifications to the current system of El Teniente. As a result, a certain number of alternatives were explored to find a solution to this shortfall, for example, adding raises to generate parallel airways and installing fans to reinforce the current ventilation system. From the alternatives studied, the installation of a second main fan (system) in parallel to an existing one was identified as the best solution, and selected for implementation, however the location was not ideal and there were concerns as to the operation of both fans once the second fan was installed. This paper presents the study used to estimate the operational points of both the current and the new fan, and to justify the parallel installation of the additional main fan. An additional computational fluid dynamics study was undertaken to validate the operational point, given the particular geometry of the fan?s location and placement, to guarantee a stable operation of the fans. Finally, the protocols arising out of this work for starting the fans, and operating them in parallel to avoid generating a stall condition and damaging the investment are discussed.

Aug 1, 2013

By M. M. Hajdasinki

A project's rates of return (RORs)1, be it the internal rates return (IRRs) or one of the many IRR surrogates, frequently needs to be approximated. The success and efficiency an ROR- approximation procedure depend on the quality the approximation-initiating parameters, such as bounds or seed values (guesses). The existing approximation procedures commonly use bounds and guesses suggested by intuition rather than supported by mathematical considerations. This paper presents three mathematically founded ROR-bounding and eleven ROR-guessing approaches and examines their suitability by using examples of typical project cash-flowpatterns (CFPs). The calculated bounds and guesses not only improve the approximation efficiency, but also allow the process of the ROR discovery to be automated, thereby making it more convenient and reliable.

Jan 1, 1999

By Archer E. Wheeler

IN the copper industry, the year 1942 was one of striving for larger tonnage and increased production. The demands of the war program placed copper high in the list of strategic metals and the Government encouraged production by offering a premium of 5c. per pound for copper output in excess of the 1941 quotas. This had the effect of increasing the tempo of existing operations and also of initiating a number of projects which will eventually result in production from sources not hitherto exploited. No radically new methods of copper reduction were reported.

Jan 1, 1943

By M. Potesser

After the primary or secondary lead production the bullion lead is remelted and charged into a vessel with following refining process. The removing of arsenic, antimony and tin takes place by salt slags or oxidizing gases like air or pure oxygen. Due to the increasing lead price, Messer Austria GmbH in cooperation with the institute of Nonferrous Metallurgy at the University of Leoben have developed a new process named OXIPOT for the refining of tin, arsenic and antimony. The OXIPOT process is in principle based on purging technology with a ceramic or steel purging device. This leads to an increased retention time of the refining products due to the deeper bath level and an optimized specific reaction volume concerning the bubble size. This paper describes the process, pilot plant, and thermodynamic calculations for the optimization concerning the selectivity of element removal.

Jan 1, 2008

By Joseph J. Wallace

The 1952 Annual Report of the West Virginia Department of Mines lists seven beds that are being mined in Mingo County, of which the Cedar Grove is the most important. The Cedar Grove, Alma, and Coalburg contain the largest remaining known reserves. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and 1,800 tons per acre-foot of coal in place, are estimated at 3,007 million short tons as of January 1, 1953. Of this total, 2,396 million short tons is in beds 28 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics are too meager for making an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.

Jan 1, 1954

By J. B. Rubenstein

This work demonstrates the feasibility of using confocal surface profilometry to measure and characterize wear of graphite anode surfaces. This method was tested using anode samples that were electrolyzed for 24 hours in a laboratory-scale magnesium cell with a high oxide molten salt electrolyte. The oxide produced accelerated wear on anodes designed for low oxide electrolytes. Contour maps, which are effective at displaying non-uniform wear, and total graphite consumption values were generated from the collected surface coordinates. Along with both qualitative and quantitative analysis capabilities, this measurement system was shown to have a fine resolution and a low detection limit.

Jan 1, 2004

By H. J. Heinen

The Bureau of Milts studied repetitive batch electrowinning of molybdenum from molybdic oxide ) to determine the effects upon the electrolyte life, purity of metal product , and overall cell performance. The electrolyte consisted of 54.0 weight-percent sodium tetraborate (Na2B407), 23.6 weight-percent sodium chloride (NaC1), 14.9 weight-percent sodium fluoride (NaF), and 7.5 weight-percent Mo03. The feed materials were pure and technical-grade Mo03. Electrolysis was conducted at l,000° C in a graphite cell in an atmosphere of air and carbon oxides. Electrolyte degradation did not occur during repetitive winning of molybdenum from pure Mo03 in an 8-day (5,400-ampere-hour) period of operation. Electrowon metal contained <0.1 percent total impurities. The electrode configuration is a key factor in the direct conversion of technical-grade Mo03 to metal by repetitive cyclic electrolysis. The best configuration found was a cathodic crucible and a central anode. Metal purity of 99.8 percent and a current efficiency of 91 percent were maintained until the combined impurity buildup the electrolyte reached 4.7 percent silicon, l.0 percent aluminum, and 0.6 percent iron. One pound of molybdenum was produced per 1.5 pounds of solvent salts employed. About 25 percent of the initial NaCl and NaF contents of the electrolyte were lost owing to volatilization and crucible penetration.

Jan 1, 1966

By E. Watkins, S. J. Schatzel, K. Ajayi, V. Gangrade

The National Institute for Occupational Safety and Health (NIOSH) has been conducting research related to unconventional gas wells positioned in abutment pillars associated with active longwall mining in Southwestern PA. The Ventilation and Explosion Prevention Team at NIOSH is working toward predicting and characterizing a hypothetical casing breach and its effect on the safety and health of mine workers, gas well workers, and the general public. An important aspect of this research is to distinguish coalbed gas from shale gas in the mine environment as an indicator of a casing breach. Another noncoal gas source exists in the region in the form of underground gas storage fields which also have the potential to migrate towards mine workings. During a potential gas breach, the addition of excess natural gas to coal mine environments will exceed the anticipated ventilation loading and can create a mine explosion hazard. A methodology has been developed to distinguish these gas sources. Gas samples from the three sources were analyzed by gas chromatography, and interpretive methods were applied to distinguish the populations graphically and statistically. Bivariate plots using the hydrocarbon index and the normalized molecular ratios showed that the sources occupy different regions of the graphs. All samples of non-coal gas contained under 2% CO2, and all coal samples included greater than this amount. A multivariate T-squared (T2) test analysis relating comparing data in pairs showed a low p-value (dimensionality parameter) and a high T2 test statistic for all comparisons, indicating that these sources are different and distinct gas populations. Ultimately, stakeholders from the mining and gas production industries can utilize this method to identify gas sources and a potential casing breach.

Mar 2, 2022

By Barry J. Morash

The over-all slope angle of between 55 and 60 degrees at the Adams Mine necessitates control blasting on the final pit walls. The control blasting techniques used are pre-shearing and buffer blasting. Pre-shearing with 2&apos;I2-inch holes on 5-foot centers is used in areas where jointing and rock type are not conducive to smooth stable walls. Buffer blasting with 12&apos;/4-inch holes is used in areas where the rock is competent. Control blasting adds to the operating costs, but can result in substantial savings in increased slope angle and reduced stripping.

Jan 1, 1978

By William L. Crentz

In a Nation-wide appraisal of coking-coal reserves and of the practicability of upgrading marginal deposits to metallurgical standards, this study of the preparation characteristics of the coals in Cambria County, Pa. , was undertaken. Over 90 percent of the coal remaining in Cambria Comity is found in the Upper Freeport, Lower Freeport, Upper Kittanning, and Lower Kittanning beds. The Middle Kittanning bed, although mined on a commercial scale in the past, is not an important bed now, as most of the remaining reserves are too thin to be mined over wide areas. For many years, Cambria County has been an important source of coal for industrial and metallurgical purposes. The) principal production comes from the Lower Kittanning bed, which accounts for almost .60 percent of the Cambria County coal output. Table 1 shows the county&apos;s coal production, by beds, during 1948.

Jan 1, 1950

By Earl T. Hayes

THIS BIBLIOGRAPHY has been assembled to aid research by the Bureau of Mines, and others on high-purity tungsten. It appears approximately 50 years after the development of ductile tungsten-one of the first metals to be produced in a high-purity form. Requirements of the missile age are ever more demanding that engines rout hotter and space vehicles fly higher and faster. Thus, it has become necessary to reexamine all conventional materials of construction as well as to investigate new combinations. At this stage of our technology we have alloys capable of operation at 1,800° F. and several possibilities of developing some. that will be satisfactory up to 2,500° F. Strength-weight comparisons, detrimental to tungsten at, lower temperatures, disappear at this point, mid tungsten or its alloys appear to be the only metal capable of operation at truly high temperatures. The aim of this bibliography has been to include only references that concern improving the purity of tungsten-from processing the ore to treating the finished metal. In this sense it is a selected and not a critical bibliography. The period front January 1911 through February 1959 has been covered. Because repent literature has the greatest, value, most of the selected items refer to publications issued within the pest 5 years.

Jan 1, 1960

By James R. Myers

A source of clean gas containing sulfur dioxide and sufficient oxygen for convers.ion to sulfur trioxide ?is essential to the production of sulfuric acid. S02 containing gases obtained from roasting sulfide ores are heavily contaminated with inorganic dust and volatile impurities. If not removed, these contaminants will reduce product acid quality, foul the catalyst beds and mist eliminators, and accelerate equipment corrosion. This paper reviews conventional gas cleaning systems for metallurgical acid plants, followed by a discussion of modern systems utilizing DynaWave Scrubber technology. This technology is based on a unique approach to? gas scrubbing that can concurrently accomplish several gas cleaning/processing tasks scrubbing liquid is injected into the gas stream to create. a "Froth Zone". This is a region of extreme turbulence, with a very high rate of liquid .surface renewal. It efficiently removes both particulate matter and gas contaminants, and is also a cost effective quenching device for gases as hot as 1250º C. Smelter

Jan 1, 1992

By Robert G. Bottge

The Bureau of Mines has engaged m a program to determine the availability of land for mineral exploration and development in Alaska. Land availability, based on ownership and Federal and State laws and policies, is compared with mineral terranes and mineral deposits. This is the fifth of six regional studies, which cover the State with a comprehensive set of maps and data compilations. This study covers an area of 112.3 million acres in western Alaska. In July 1986, 41.0 million acres, 37% of the study area, were available for mineral exploration and development; 14.6 million acres, 13%, were available with restrictions; and 56.7 million acres, 50%, were unavailable. Nearly 65% of the unavailable land is classified as national parks, preserves, wildlife refuges, and wild and scenic rivers. Of the 34.0 million acres of mineral terranes that underlie the study area, 12.9 million acres, 38%, are available for exploration and development; 3.6 million acres, 11%, are available with restrictions; and 17.5 million acres, 51%, are unavailable.

Jan 1, 1988

By Paul M. Tyler

OF THE 92 elements generally accepted by chemists as constituting the primary building blocks of matter, all but the very rarest have been investigated with a view to employing them in steel manufacture. The surprising thing is that so few have been found commercially acceptable. Despite the relatively small number of elements involved, the use of alloys in steel making is one of the most complicated and probably one of the least well understood of modern industrial enterprises. The action of individual elements in steel making has been described often and a profuse and somewhat acrimonious literature covers pretty much the whole field of ferroalloy ore supplies. In the middle ground between the miner and the -steel maker developments are less carefully watched by most observers and except for an occasional description of the technique of some conversion process or the tariff hearings in Congress, little is said about them. The present paper has been submitted in the hope that it will stimulate broader constructive economic thinking. It undertakes to describe in&apos; relatively nontechnical terms this great and growing though highly complex industry and to study its relations to national progress.

Jan 1, 1932

By E. M. J. Alenius

This paper describing the mining practices at the United Verde open-pit mine at Jerome, Ariz., is one of a series being prepared by the United States Bureau of Mines on mining practices, methods, and costs in the various mining districts in the United States. The purpose of this paper is to present the methods used in developing and operating the mine, and to discuss the problems encountered.

Jan 1, 1930

By C. E. Brechtel

This project describes the design and testing of large face ventilation systems for oil shale mining. A design data base was generated by reviewing general industry practice, oil shale industry planning, and technical literature. Conceptual designs for seven different systems were developed and evaluated for suitability. A large, free-standing, jet fan and reversible fan with rigid duct were selected for fabrication and testing. The two systems were field tested in a dead-end heading 55 ft wide by 30 ft high and 320 ft long. System performance was optimized using measurements of air flow direction and air velocity. Total system performance was then measured using SF6 tracer gas released to simulate blast fumes, hot diesel exhaust, methane layering and methane from a blasted muckpile. Field testing indicated that both systems delivered similar performance. The jet fan offered some clear advantages because of its mobility, ease of oper-ation and lower power requirement. It also offered some functional advantages in ventilating for methane because of it high average velocity.

Jan 1, 1985

By D. F. VanDine

The phases of a typical exploration program for sand and gravel resources include: (1) collection and assessment of existing information; (2) air photo interpretation and remote sensing; (3) ground investigation and mapping; (4) sampling and testing; and (5) data storage, retrieval, analysis and presentation. Depending on the purpose, time frame and funding available for the study, these phases, and the various techniques used within each phase, will vary. Once a sand and gravel deposit has been located, defined in size and quality, and found to be suitable for a given purpose, it can then be classified as a granular resource.

Jan 1, 1984

By R. R. French

Investigations were conducted by the lndiana Geological Survey for some dry methods of bene-ficiating low-grade gypsum ore. Seventy-two batch and continuous flow tests were performed with a roller mill, rod mill, pebble mill, electronic color sorter, electrostatic separator, and an air separator. Approximately 650 size analyses and 550 chemical analyses were performed during the investigation. Batch samples were tested by the Survey, and most of the continuous flow tests were handled by com-mercial laboratories. INTRODUCTION Although many companies producing gypsum have been interested in dry beneficiation, very little information has been published in the past. One of the most comprehensive investigations was reported by the Canadian Department of Mines.5 Other reports of interest have been published by the Canadian Department of Mines,&apos; the South Australian Department of Mines,2 and the U.S. Bureau of Mines.3 Some beneficiating practices, such as hand picking, selective mining, crushing and screening, milling, and air classifying, were already in use in the Canadian industry prior to MacPherson&apos;s investigations.5 MacPherson examined the effect of tabling, air separation, screening, flotation, electrostatic separation, calcining, washing, and various types of milling, in his efforts to eliminate dolomite, limestone, and small amounts of silica and clay from the gypsum ore. RAW MATERIAL Gypsum and anhydrite occur within the lower part of the St. Louis Limestone (Mississippian) in southwestern Indiana. Gypsum in single beds 10 or more ft thick occur at Shoals, Martin County; near Freedom, Owen County; near Bloomfield, Greene County; and in the Devonian strata of LaPorte County. Only the Shoals deposit has been exploited commercially. The western edge of the Shoals deposit is contaminated by a continuous bed of shale, about 1 1/2 to 2 ft thick, near the top of the evaporite and by thin continuous strata or irregular masses of carbonate rock. The low-grade material used in these investigations was obtained from the waste pile of the National Gypsum Co.&apos;s plant at Shoals. The waste ore averaged about 67.4% gypsum and was contaminated by various amounts of shale, dolomite, and limestone. All the material had been previously crushed and screened to minus 1 1/4 to plus 3/8 in. X-ray analyses of powdered, sedimentated, gly-colated, and heat-treated samples of the shale showed that it was composed of slightly structurally disordered illite, Fe-rich chlorite, and very finegrained disseminated silt. The clays and silt were partly cemented with carbonate material. Light-gray argillaceous limestone and gray or brown porous dolomite made up most of the carbonate rock contamination. Crushing Characteristics: The rate unweathered gypsum, carbonate rock, and shale reduce in size was determined by crushing handpicked samples in a rod mill and screening at minus 100 mesh (.0059 in.). Fig. 1 graphically represents the data. These data indicate that carbonate rock should be relatively easy to separate from gypsum, but that shale should be difficult to separate from gypsum by differential crushing. Controlled Samples: Eight rod mill tests of hand-picked samples of mixed gypsum and shale and mixed gypsum and carbonate rock were made. Sample weight and crushing weight were standardized, but the scalping screen size was varied from 3 to 10 mesh (.265 to .0787 in.) in order to obtain the optimum purity and recovery. The data obtained from the tests (see Table I) illustrate that the relatively hard carbonate rock allows appreciable beneficiation (13.6 to 18%), but the low strength gypsum and shale allows only minimal separation (3.1 to 7.5%).* Semi control led Samples: During the investigation considerable slaking of the shale was noted when the ore was subjected to alternate wetting and drying. As demonstrated in laboratory tests, as much as 76% shale can be removed by two cycles of wetting and drying in a 48-hour period with subsequent screening at .265 in. Five ore samples, stockpiled and weathered, were screened, rod-mill crushed and rescreened at .157 or .187 in. with excellent results (Table 11).

Jan 1, 1967

By A M. Mueller

St Helena tunnel is the centrepiece of the Pacific Highway upgrade from Tintenbar to Ewingsdale, abbreviated and commonly known as T2E. At the deepest point the twin tunnels run 45 m below the ridge line of St Helena Hill, located about 5 km west of Byron Bay. The tunnel breakthrough was achieved early in 2014 and the works for permanent lining will be completed in early 2015.Once the project will be handed over to the public in 2015, T2E will deliver a safer highway and uninterrupted traffic flow between New South Wales and Queensland. The design speed in the project area has been set to 110 km/h by the client Roads and Maritime Services (RMS), which will reduce the travel times between Brisbane and Ballina to just over two hours.The two tubes of the tunnel have been designed to accommodate three lanes in each direction with shoulders and walkways on either side of the carriageway. These requirements result in a huge cross-section of about 20 m width and an excavated area of about 210 m2.With the tunnel alignment being situated in basaltic rock, St Helena tunnel is conventionally driven. The selected excavation method was predominantly drill-and-blast with temporary support being installed immediately after the excavation. Despite the wide span of the tunnel, the geology allowed the tunnel perimeter to be supported by only rock bolts and a layer of shotcrete over the majority of its length.Due to environmental reasons one of the approval criteria of the project was that the tunnel must not have a detrimental long-term impact on the groundwater system within St Helena Hill. Consequently the tunnel has been designed as a fully tanked structure with a waterproofing sheet membrane installed on the temporary shotcrete.The permanent structure of the tunnel has to meet a 100-year design life and it is designed as a cast in situ concrete lining. Considering the water pressure on the lining the concrete is reinforced with a significant amount of bar reinforcement.The presented paper provides a more detailed explanation of the geology and the consequential temporary and permanent support measures together with the waterproofing system.CITATION:Mueller, A M, 2014. Pacific Highway upgrade from Tintenbar to Ewingsdale (T2E), St Helena Tunnel, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 419–424 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014