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By R. E. Cumings

The Bureau of Mines made electrorefining tests in inert-atmosphere, molten salt cells to develop methods for the preparation of high-purity molybdenum. Seven of the electrolytes investigated were suitable for the preparation of refined metal. The electrolytes were composed of molybdenum chloride in alkali chlorides or mixtures of alkali and alkaline-earth chlorides. An electrolyte composed of potassium chloride and potassium hexachloro-molybdate was selected for a larger scale, more detailed study on the basis of its ease of preparation, its ability to retain the molybdenum salt, and the type of deposits obtained. High-purity molybdenum in the 99.99-percent-purity range was successfully prepared as dense plate up to 80 mils thick and as dendritic crystals. The temperature of electrolysis and the current density were major factors in determining whether plate or dendritic crystals of molybdenum were obtained.

Jan 1, 1966

By Marvin E. Lane

This paper , which describes the mining methods and practices at the Hayden Creek lead mine of St. Joseph Lead Co. in southeast Missouri , is one of a series being prepared by the Bureau of Mines on mining methods , practices , and costs in various mining districts of the United States . The Hayden Creek mine is in the W 1/2 sec . 7 , T. 36 N. , R. 4 E. , St. Francois County , Mo. , about 1 mile southwest of the town of Frankclay ( fig . 1) . The mine is on the west edge of the mining district known as the Lead Belt . However , neither the ore body nor the underground workings are connected with those of any other mine in the district . In contrast with most operations in the district , underground haulage is entirely trackless , and nearly complete delineation of the large , well -defined ore body by drilling permitted comprehensive planning of development and mining in advance of shaft sinking . The ore differs in character and occurrence from that of the main ore deposits in the Lead Belt in that the lead mineral , galena , occurs in the dolomitic matrix enclosing granite boulders instead of in dolomite limestone .

Apr 1, 1957

By R. Le Houillier, M. Nagamori, A. J. Plumpton

"Asbestos tailings are a typical serpentine, hydrated magnesium silicate, consisting primarily of antigorite and a few per cent of unrecovered fibrous chrysotile. Serpentine has unique thermal properties in that dehydroxylating calcination at 600 to 700°C can yield an amorphous structure in which most of the magnesia is liberated from the original bond with silica and thereby rendered chemically active. The amount of activated magnesia can be quantified by selective leaching with a weak acid such as acetic acid. Many wet processes have been proposed to extract magnesium values from calcined or natural serpentine by means of various acids and their ammonium salts. However, the only commercial utilization of serpentine today is found in dry processes such as the production of fused magnesium phosphate fertilizer .The present paper reviews the physical chemistry of the dehydroxylation of serpentine and also various wet and dry processes in order to provide a general view regarding the chemical transformation of asbestos tailings.IntroductionAsbestos fibers occur as chrysotile, a serpentine polymorph. More than nine tenths of mined asbestos ores consist of massive non-fibrous serpentine, primarily the polymorph antigorite, which is discarded as tailings after fiber extraction. For many decades, Quebec has been a world leader in the production of asbestos fibers. As a result, colossal tonnages of serpentine have accumulated in the Eastern Townships'!'. Serpentine minerals are found in large deposit s throughout the world, and significant research efforts have been made, particularly in Japan and the USSR, mostly in attempts to extract magnesia or silica values therefrom.The chemical composition of serpentine (chrysotile and antigorite) may be ideally expressed as Mg3Si2Os(OH). which corresponds to 43.7% MgO and 43.3% SiO2. Natural serpentines often contain a few per cent of Ni-bearing magnetite and other impurities, and therefore the contents of MgO and Si02are both about 40% or lower.Serpentine (hydrated magnesium silicate) is virtually insoluble in weak acids. However, when dehydroxylated under controlled conditions, ' it decomposes to an amorphous state in which magnesia and silica are isolated and chemically active. The magnesia so activated is readily soluble in weak acids. This unique characteristic of calcined serpentine, first discovered in 1942,, has since attracted the attention of innumerable researchers, whence many processes have been proposed."

Jan 1, 1980

By Murray Hitzman

Central and southern South America contain a variety of sediment-hosted base metal deposits including shale-hosted Zn-Pb-Ag, Irish-type Zn-Pb-Ag, BrokenHill-type Pb-Zn-Ag, Mississippi Valley-type Zn-Pb, and sediment-hosted stratiform Cu deposits. In this sense, the paper point out Potential for sediment-hosted base metal deposits in Central and Southern South America.

Apr 24, 2001

By Mansoor Barati, Shaghayegh Esfahani

"The slag from extraction of ferrous and non-ferrous metals is a potential heat source which if treated properly can contribute to recovery of a significant amount of energy. The waste heat of slag may be used to generate steam, synthetic fuel gas, or electricity. Although several technologies have been investigated for this purpose, very little has been achieved in terms implementing the technology in industry. In this article, the development and application of various granulation techniques are reviewed and the methods to recover energy from granulated slag are discussed.IntroductionEvery year, more than 422 million tons of slag is being produced around the world as a by-product of the metal manufacturing at temperatures of up to 1300-1600°C [1, 2]. Currently slags are either disposed of or treated by processes such as granulation. Through the granulation process, most slags can be converted into a material which may be fully used as a cement feedstock. Conventional cement production is an energy intensive process with large emissions of CO2; therefore, the replacement can both be energy saving and environmentally friendly. However, for this purpose, the slag should have what is known as a “glassy” content (i.e. it should be amorphous) which requires rapid cooling rates that are not easily achieved due to the very low thermal conductivity. The main challenge in all these processes is to granulate the slag at a high cooling rate while the heat is also being recovered."

Jan 1, 2012

By Fuqiang Guo

Scorodite (FeAsO4, 2H2O) is suitable mineral carrier for immobilization of arsenic-rich wastes. Its stability is, however, highly pH dependent (typically at 4 ≤ pH ≤ 7) and satisfactory only under oxic disposal conditions. In thiswork an encapsulation process using mineralized gels of aluminum hydroxy-oxides is developed to enhance the stability of scorodite under wider pH and redox potential range conditions. The encapsulation involves blending and ageing of synthetic scorodite produced by McGill’s atmospheric scorodite process with aluminum hydroxyl gels derived from controlled hydrolysis of aluminum salts. The amorphous hydrolyzed Al-gel encapsulates the scorodite particles,which upon short-term aging transforms into crystalline Al (OH)3/AlOOH mineral phases providing a robust protection microscopic barrier. Long-termstability testing demonstrates the encapsulation systemto be highly effective in suppressing arsenic release under either oxic or anoxic (100 mV < Eh < 600 mV) potential and neutral-alkaline pH (7 ≤ pH ≤ 9) ranges.

By Roorda H. J, R. R. Saddington, Curlook W

THE copper-nickel sulfide ore deposits of the International Nickel Company of Canada, Limited contain the minerals pyrrhotite, pentlandite, and chalcopyrite. In the extraction of the nickel, copper, and iron, much of the processing involves oxidation of the metals as well as sulfur. Roasting plays a predominant role at several stages in the operations which prepare the constituent metals for refining. Copper, nickel and iron concentrates of various grades, ranging from low-grade nickeliferous pyrrhotite to high-grade nickel sulfide, must be partially or completely oxidized. Figure 1 shows the main points at which roasting is conducted at INCO. Roasting experience at INCO dates back to the time when lump ore was partially roasted in heaps. It has progressed through single hearth roasters, sinter machines, multiple-hearth roasters, flash roasters, and more recently has centered on the development and utilization of fluid bed roasters. The primitive, slow, and inefficient method of heap

Jan 1, 1961

By W. E. Lamont

The Federal Bureau of Mines, in cooperation with phosphate companies in the Florida land-pebble area, made a comprehensive study of the waste clays, or "phosphate slimes," produced in the mining of phosphate rock in Florida. These slimes represent a significant ecological problem and a major deterrent to effective land recovery in the phosphate-mining areas. Physical, chemical, and mineralogical studies were made of slime samples submitted by 15 of the 16 plants in Florida in an effort to identify factors that prevent successful consolidation of the slimes and subsequent recovery of the mined lands. Results of these studies indicated that the clay mineral attapulgite, a hydrated magnesium silicate, was primarily responsible for the very poor settling characteristics of the slimes, and that the quantity of attapulgite in the slimes effectively controlled the settling rate, pulp density of terminal solids, viscosity, percent solids of filter cake, and flocculant requirements.

Jan 1, 1975

By G. Bulut, Ü. Yenial

"The use of recycled water in flotation has significant effects on flotation and selectivity because the recycled water contains many dissolved compounds and ions that alter the chemistry of the system. In this study, the effects of calcium, magnesium and sulfate, which are abundant components in recycled water, were investigated on galena, sphalerite and pyrite flotation using pure minerals and a complex sulfide ore by conducting bench-scale flotation, microflotation and zeta potential measurements. The bench-scale flotation tests indicated that higher recoveries of galena and sphalerite are obtained when water is recycled, due to higher concentrations of ions in recycled water. However, there was a critical ion concentration for galena recovery. The microflotation tests showed that galena recoveries at different pHs in recycled water are lower than in tap and distilled water. Pure sphalerite recoveries improved in recycled water in the bench-scale test with ore. Pure pyrite was depressed with recycled water as well. Zeta potentials became less negative with increased calcium and magnesium ion concentrations due to their adsorptions, and the presence of sulfate ions was seen to increase the negative charges of sphalerite and pyrite, conversely for galena. IntroductionWater is among the most important elements for mining and mineral processing. The distance to water sources is one of the major factors for mine site selection. The mining and mineral processing sector needs and consumes large quantities of water. In Chile in 2014, the copper mining sector alone consumed 12.7 m3/s fresh water for 1.189 tons of ore processing, and recycled 74 percent of the consumed water (Chilean Copper Commission, 2015). A plant that does not reuse or recycle any water will require 1.9 to 3.0 m3 of water per ton of ore processed (Gunson et al., 2012). Many stages of mineral processing, such as grinding, gravity concentration, dense medium separation, wet magnetic separation, flotation and hydrometallurgical operations, use large volumes of water (Schumann, Levay and Ametov, 2009).In mineral processing plants, the process water is recycled from the tailings dams, thickener overflows, and dewatering and filtration units. Wet concentration processes can require large quantities of water. Flotation, the most common process, typically takes place at 25 to 35 percent solids by mass. Most flotation plants practice at least some water reuse and recycled. Modern mines and mineral processing operations generally aim for zero water release (Levay, Smart and Skinner, 2001). In most cases, water quality has been found to affect flotation performance, and this interaction remains under investigation."

Jan 1, 2016

By G. D. Ruttan

"LYNN LAKE, in northern Manitoba, has become Canada's second nickel-producing area. The discovery by Sherritt Gordon Mines of nickel ore in an entirely new district was the result of systematic prospecting of a belt of volcanics and sediments situated 100 to 150 miles north of the Company's former copper-zinc mine at Sherridon, Manitoba.Prospecting in this area was begun in 1937 and continued each year until 1941, when Austin McVeigh, a company prospector, found a patch of sulphides on a gabbro outcrop near a small lake named Lynn Lake. Samples from this sulphide indicated nickel and copper in significant amount. In 1943, magnetometer work disclosed a number of weak anomalies in low ground near the discovery. In 1945, staking was followed by geophysical surveys and diamond drilling, which continued through 1947. During this period the A, B, E, EL, and Corebodies were located and partly outlined. The discovery of the high-grade ""EL"" orebody in January 1947 was the turning point in the estabishment of the mine. Subsequent development, including additional exploration on surface and under-ground, evolution of a new metallurgical process, financing, erection of a mining and milling plant, hydro-electric power development, building of a rail line from Sherridon (by Canadian National Railways) and a refinery at Fort Saskatchewan, Alberta, culminated in August 1954, when the first shipment of nickel left the refinery. This paper, presented at the 1955 Annual General Meeting of the C.l.M. in Toronto, was one of a symposium covering the whole operation."

Jan 1, 1949

By B. W. Dyer

At about 8:30 o&apos;clock on the morning of March 8, 1924, an explosion occurred in the Castle Gate No. 2 Mine of the Utah Fuel Company, Castle Gate, Utah, and 171 men lost their lives. The explosion was caused by the ignition of a comparatively small body of gas and was propagated throughout the mine by fine coal dust which had accumulated on the roof and ribs of the mine and by coal dust made by the explosion itself. Castle Gate No. 2 Mine was one of the best kept mines in the state and it was believed not only by the officials of the Utah Fuel Company, but by all others connected with the coal industry of the state that this was one of the safest mines in the entire state. The state had not been visited by a catastrophe for over twenty years and it was a general belief that the mines were kept in such condition that a catastrophe was almost impossible. During the preceding twenty years new mining officials from other fields had entered the state and seeing that sprinkling as done in Utah was far more elaborate than in most other coal mining sections of the country, caused them to believe that they were keeping their mines in an absolutely safe condition. When coal -mines suffer no mishap during a period of twenty years the general attitude relative to safety may become somewhat lax, not only with the operating officials, but also with the State Inspection Department. However, there were some who were more keen to appreciate the hazards of Utah coal dust and who predicted that if Utah mines were kept only damp but not wet, some day the state would be shocked by the news of a dreadful disaster. In a paper prepared and read before the Salt Lake City Chapter of the American Institute of Mining and Metallurgical Engineers in 1924, Mr. D. Harrington stated: "The writer had his first mining work in Utah mines spending nearly ten years in Utah, starting just after the Scofield explosion in 1900. After having been absent from the state for about eight years upon returning and spending a few days in a few properties, there appeared then to be a definite relaxation as to precautionary methods especially against dust; some of the properties which in 1900 to 1910 would have stopped work if for any reason water was not available for sprinkling purposes, were in 1918 definitely dry in many places, and in some instances there was also definite relaxation as to shooting regulations, some properties with electric shooting systems were allowing firing of certain shots while the men were in the mine. The Utah coal. dusts are too inflammable and explosive to allow of taking any chances and unless up-to-date and carefully maintained, the Utah coal mining world will hear to its dismay, that the very excellent record of the past twenty-three years as to explosions has been shattered. Hence, possibly it was not altogether a complete surprise that such a disaster occurred in Utah, but it was a surprise to many that it occurred in one of the best kept mines in the state and it was that fact that led the coal mining men of Utah to believe that the state coal mining laws should be modified.

Jan 1, 1925

By J. O. Marsden, M. M. Botz

"Heap leaching is responsible for approximately 21 percent — 3.9 million metric tonnes — of copper production and 9 percent — 270 metric tonnes or 8.7 million ounces — of gold production worldwide. Given metal price assumptions of $2.25/lb for copper and $1,250/oz for gold, these portions of global production generate revenues of $19 billion and $11 billion, respectively. For heap leaching operations, small changes in metal extraction efficiency drive substantial changes in operating cash flow margins and affect project viability. Variances in actual metal production from budgetary forecast estimates can mean the difference between success (value creation) and failure (value destruction) for a heap leach project. Despite the importance of heap leaching for copper, gold and silver production worldwide, there are no clear standards or guidelines for developing heap leach metal production forecasts. There is considerable variation among copper and gold producers that apply heap leaching technology as to how such modeling and forecasting is applied at the operational level. There are a variety of different modeling approaches that can be utilized for this purpose. However, these vary in cost, complexity, time to implement, accuracy and credibility. This paper explores the options available for heap leach modeling, discusses the advantages and disadvantages of each approach, and provides guidelines/recommendations for an effective approach to modeling metal production at existing or planned heap leach operations. The paper also provides expected ranges of variation between actual and modeled production.Introduction and backgroundHeap leaching is fundamentally different from other methods used in the processing and extraction of gold, silver, and copper and other base metals. Considered globally, the technique represents a relatively modest portion of production compared with the primary technologies applied for copper and gold recovery. Approximately 21 percent of copper production is attributable to heap leaching techniques, as opposed to 79 percent by conventional crushing, milling, flotation, smelting and refining. For gold, about 9 percent of global production is obtained from heap leaching, compared with over 90 percent by various combinations of crushing, milling, gravity concentration, flotation and/or agitated cyanide leaching processes or, in the case of placer deposits, by direct gravity concentration and/or amalgamation. In cases where heap leaching is the primary source of metal production, the ability to accurately forecast metal production may be the difference between commercial success and failure for a project or operation. Heap leaching — of crushed or run-of-mine ore — is also commonly applied as a secondary process to treat lower-grade ores from a given deposit, such as at Chuquicamata in Chile, Cerro Verde in Peru and Bagdad in Arizona for copper extraction and at Twin Creeks and Carlin, both in Nevada, for gold. In such cases, heap leaching provides incremental revenue to supplement the primary process. Variances between actual and forecast metal production from heap leaching as a secondary process are typically tolerated and absorbed within the overall site metallurgical balance. In either case, accurate production modeling and forecasting creates significant value for heap leaching projects, is essential for managing production expectations — timing and volumes — and is likely to be a critical success factor for most heap leach projects."

Jan 1, 2017

By Dudley L. Davis, E. C. Peterson

INTRODUCTION THE Darwin District is 30 miles east of Olancha which is 220 miles north from Los Angeles via U. S. Highway No. 6. The ore deposits occur in the Darwin hills that have been elevated above the Darwin Plateau by typical basin and range-type faults. Some of these faults have been active quite recently as shown by the displacement of Quaternary (?) basalt flows and the rejuvenation of erosion in Darwin wash. The ore bodies occur as fissure fillings and replacement of favorable beddings in a thick series of Paleozoic limestones, dolomites, shales and quartzites. Rich oxidized lead-silver ores were discovered in the early seventies. By 1875, Darwin had a population of about 5000, and by 1880 several small mills and smelters had been built. Early exhaustion of surface ores, the isolated location of the district, and fluctuation of metal prices caused intermittent operations until World War II. The district production is estimated at about $3,000,000 prior to 1900 and perhaps $4,000,000 between 1900 and 1945 when Anaconda purchased the major producing mines. For the past two years, daily production has averaged 75 tons of direct shipping and 150 tons of milling-grade ore. At present, 300 tons of mixed oxide and sulphide ore are treated by flotation, the oxidized lead minerals being activated by addition of sodium sulphide after galena and sphalerite have been recovered from the circuit. Extraction averages 85 pct of the lead, 80 pct of the silver, and about 33 pct of the zinc in a bulk concentrate. The mill is designed so that minor changes permit selective flotation of pyritic lead-zinc ores encountered at depth. GENERAL GEOLOGY The oldest rocks in the Darwin hills are a series of Paleozoic limestones, dolomites, shales and quartzites probably Pennsylvanian in age. These rocks have been intruded on the west by the Coso granite batholith and on the east by a granodiorite stock. Numerous sills and dikes grading from orthoclase granite to gabbro are exposed in the underground workings. The sedimentary rocks have been considerably folded and faulted, the most prominent structure being a northwest pitching anticlinal fold, the crest of which lies just west of the ridge line of the Darwin hills. The east limb of this fold has been intruded by the granodiorite stock and east of the stock the sediments show several closely spaced anticlines and synclines. The minor flexures on the west flank of the major fold are structurally important in localizing the ore in the Defiance and Essex mines of the Darwin group. There are three principal systems of faulting and fissuring, most of which are post-intrusive and premineral in age, with minor amounts of postmineral movement. The Darwin tear fault is the largest, most persistent fault in the district. It strikes N 60 to 95°W, dips steeply south and is traceable for about 1o miles. It is a normal

Jan 1, 1947

By Davood Moradkhani, Maryam Rasouli

"The present study reports solvent extraction and separation of zinc from concentrated nickel sulfate solution. In our previous study, Zn and Cd in cold filter cake (CFC, 45-55% Zn, 11-16% Cd, and 2.5-4% Ni) were extracted by alkaline leaching followed by electrowinning processes respectively. The strip solution from electrowinning process, was a pregnant liquor solution (PLS) containing 16.8 g/l Ni and 4.2 g/l Zn. In this work, PLS is subjected to the solvent extraction process for separation of traces of Zn from high grade nickel. The zinc free raffinate containing 16.6 g/l Ni sulfate solution will flow to nickel electrowinning plant for cathode production. Di-(2-ethylhexyl) phosphoric acid (D2EHPA) is the organic phase used in this study. The effects of various parameters such as organic phase concentration (10- 40 % v/v), pH (1.5-3), and temperature (25 and 45°) are investigated. Zinc over nickel separation factor increases by increasing pH from1.5 to 3. The results show that 98.7% of Zn was loaded at25°C O/A ratio of 1, pH 3, and 10% vol. D2EHPA. A 10 M NaOH is used for pH control. However, replacement of pH controlling agent with ammonia solution (25%. v/v) results in interesting observations. Ammonia addition, reduces the solubility of Ni2+ cations in solution. Nickel starts to precipitate from raffinate in a crystalline bluish-green form. The obtained crystals are characterized by XRF and identified to be nickel-bearing analog of boussingaultite, a rare sulfate mineral of nickel with chemical formula of Ni (NH4)2(SO4)2.6H2O. The crystallization rate of crystals is studied. It is a slow precipitation process with 75% in 4 days.INTRODUCTION Annually, many hydrometallurgical processes such as electrowinning, solvent extraction and leaching are applied to waste filter cakes in Zanjan, Iran. These additional processes on filter cakes are critical from both environmental and economic points of view. CFC (cold filter cake) is a toxic but valuable filter cake (45-55% Zn, 11-16% Cd, 2.5-4% Ni, and 0.2-1.5% Cu) produced in many zinc production plants. Our research group at Research and Engineering Company for Non-ferrous Metals (ReCo.), developed a series of hydrometallurgical methods for extraction of zinc, cadmium and nickel from CFC (Moradkhani, & Rasouli 2012). The recovery of zinc and cadmium with alkaline leaching and electrowinning was successfully studied. The strip sulfate solution from cadmium electrowinning unit, contains high concentration of nickel with some traces of zinc impurity. This pregnant liquor solution (PLS) was analyzed and reported to contain 16.8 g/l Ni and 4.2 g/l Zn. In this work, PLS is subjected to the solvent extraction process to separate Zn from nickel (Fig. 1). The organic phase stripping solution containing 4.2 g/l zinc and 200 ppm nickel can be circulated and used in the acidic leaching step. This generates nickel solution with high purity suitable for nickel cathode production."

Jan 1, 2017

By J. D. Miller

The sedimentary western phosphate deposits of Idaho, Montana, Utah, and Wyoming tend to be calcareous and generally carry a significant amount of dolomite along with collophanite. In some cases, such as the Smokey Canyon Mine, Afton, Wyoming, the ore will also contain mudstone, and in this case the aluminosilicate minerals (clay, feldspar, etc.) together with some dolomite are floated from the collophanite in column flotation cells with an amine in order to meet product specifications (31 % P205) (Service et al.). In other cases, such as the SF Phosphates Limited Mine, Vernal, Utah, the ore is treated by traditional fatty acid flotation of the collophanite with mechanical flotation cells (Weber, 1986). Preliminary tests have now been conducted to evaluate air-sparged hydrocyclone (ASH) technology for the flotation of western phosphate ore. For this preliminary study, samples were taken from the hydrosizer overflow stream (18-21 % P205) at the SF Phosphates Limited Plant in Vernal, Utah for scavenger flotation testing with the 2-inch ASH system in laboratories at the University of Utah. Selected design and operating variables are being studied, and the initial results show that satisfactory separations can be achieved by high-capacity ASH flotation at appropriate operating conditions. For example, with single-stage ASH flotation 80% recovery can be obtained with a scavenger concentrate grade of about 26% P2O5. These results are comparable to, or better than, those obtained at SF plant operations with conventional flotation cells and suggest that ASH flotation technology can be used to good advantage in the phosphate industry. Of course, research should be continued to consider other process streams, optimize the separation efficiency, and evaluate larger diameter ASH units.

Jan 1, 1993

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Hugh Steele, Brower Dellinger

U. S. mining trends for 1956 continued steadily U+ S. uphill, technique and equipment advanced with the pull, and exploration and development of once mined districts attracted more attention than new areas. Expansion of the Ambrosia Lake district in New Mexico more than doubled known uranium ore reserves, and production began from several of the large new ore discoveries. In Canada the up trend was more spectacular, especially in exploration and development. To combat increasing problems arising from high labor costs, taxes, low grade orebodies, and dwindling discoveries, manufacturers and mining companies have continued to introduce new techniques and new products-reamer bits for enlarging small holes drilled by jacklegs, whup d&apos;whups for drift mucking, Cryderman machines and over-the-head small crawler-type machines for shaft mucking, the 20-ton TL 220 four-wheeled tractor trailer unit for underground haulage, inertia-type dust collectors, roof bolting in conjunction with chain link fencing for wall support, wooden roof bolting using compression support of ground for wall support, and new one-use carbide bits.

Jan 2, 1957

By Adnan A. Malik, Tadashi Maejima, Jiro Kuwano

"Previous studies revealed that the helix deflection reduced the end bearing capacity of screw pile in dense ground even if the installation process is completed with minimal soil disturbance. The ultimate end bearing capacity in dense ground is difficult to achieve during the full-scale pile load test due to the limitation of the loading system. Therefore, in the present study, model scale of testing is selected to investigate the effect of helix deflection on load settlement behavior of single helix screw pile under increasing stress level. It is observed from the test results that the applied surcharge pressure, which is used to simulate the effect of stress level, is decreased with increase in model ground thickness. This decrease in the stress level is due to the frictional resistance between the container wall and sand. It is also observed that the end bearing capacity of screw pile increases with the increase in stress level but at gradually decreasing rate. The test results indicated that the helix deflection during the pile load test should not be more than critical deflection (0.72 mm average) of the helix to avoid any reduction in the end bearing capacity of screw pile. The helix deflection, which is measured after the pile load tests are also compared with the equations of flat circular plate having uniformly distributed load over the plate with simply supported and fixed inner edges.INTRODUCTIONThe screw pile consists of a central steel shaft with one or more helices attached at different location on the central shaft. The installation mechanism of screw pile consists of torque and pushing force. The screw pile installation mechanism can affect the unit weight of the ground during its installation. This effect is small in cohesive soils but it is quite noticeable in loose to medium dense sands (Adams 2011; Santos et al. 2013). The pushing force should be controlled in such a manner that pile penetration should be at least 80% of the pitch of the helix, during each revolution (Perko, 2009)."

Jan 1, 2017

By Gordon W. Hines

This paper, dealing with network planning in an industrial complex, discusses the type and size of project that can be handled on a manual basis. After a review of the fundamentals of network planning, and specifically of the Critical Path Method, the author analyses several different types of projects, each with its own characteristics. Some can be handled in conjunction with a computer, but others can be dealt with equally well without one. Among the projects discussed are a blast furnace reline, the installation of a billet mill flying shear, and routine maintenance-type operations.

Jan 1, 1967