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By K. G. Davis, P. Fryzuk

A study has been made of the effect of undercooling on the grain structure and solute distribution in small ingots of pure bismuth and of a 100 ppm Ag in bismuth alloy. Autoradiographic evidence shows that in undercooled melts a network of dendrites is formed throughout the melt immediately after nu-cleation. At large undercoolings the dendrites are very thin and closely spaced. The origin of the observed grain morphology can be explained on the basis of information about the mode of solidification revealed by the impurity substructure. WHILE a great number of studies of nucleation in undercooled molten metals have been made, comparatively little attention has been given to the mode of solidification from melts with large undercool- ings. Colligan and Bayles1 and Walker2 have measured the rate of advance of the solid-liquid interface in undercooled nickel melts, but the morphology of the solidifying material remained a matter of speculation. Fehling and Scheil3 have described the grain structure in ingots formed from undercooled melts of nickel, palladium, and copper, and a series of Ni-Cu and Ni-Pd alloys. At small undercoolings, equiaxed structures are observed, the grain diameter tending to increase as the temperature of nucleation is lowered. At greater undercoolings, a columnar structure is developed, while with still further undercooling there is a smaller grain size incorporating rather coarse subgrains. All-bright and Colligan4 examined the grain structure shown by ingots solidified from melts of nickel and of Ni-Ag alloy at an undercooling of 105°C, and concluded that considerable grain growth had taken place after solidification. The object of the present work is to correlate the mode of solidification from undercooled melts with both the grain structure and impurity segregation, using tracers to examine the latter.

Jan 1, 1965

By Alexander Karim

This paper reviews the growth pattern in bauxite and alumina production, and primary aluminum smelting through 1980. Because the alumina and primary metal are intermediate products of the major integrated aluminum companies, it is not possible to determine their production costs. The costs indicated in this paper are order of magnitude costs based on published figures and the market price of these products. The conclusions in this paper indicate the general pattern of growth in the aluminum industry and are not meant to be a substitute for the feasibility and economic studies that are needed for individual bauxite mining, alumina refining and aluminum smelting projects.

Jan 1, 1968

By Glenn C. Reed

This report is one of a series based upon investigations made and being made within the Missouri River Basin in Montana by engineers of the Bureau of Mines , Albany Branch , Mining Division . These investigations are made primarily to provide preliminary information to the Department of Interior agencies and to others concerned with planning the proposed Federal power development within the Missouri River Basin . The present report has been designed to permit public distribution of factual data obtained . The field investigations were made during the late fall of 1947 and the summer of 1948. Information on mineral occurrences in several areas in Sweet Grass County also are included in this report because of their close proximity to Park County . Practically all known metallic mineral deposits within Park County were investigated ; some nonmetallic mineral deposits also were investigated. The investigations of the metallic mineral deposits in Park County cannot be considered complete ; some long inactive mines and prospects on which little or no information is of record may have been missed . Many of the underground openings , especially at the long inactive properties , no longer are accessible ; consequently , much of the information regarding history their and development necessarily has been obtained from available Federal and State publications .

Feb 1, 1950

By David A. Sterling

Approximately 50 percent of the uranium resource of the Free World is in deposits of Precambrian age, principally in lower Proterozoic conglomerates in Canada and South Africa (Uranium Resources, Joint Report, ENEA and IAEA, 1967). Most of the uranium resource of the United States is in Mesozoic and Cenozoic continental clastic sedimentary rocks that fill intracratonic basins. The Atomic Energy Commission is investigating the distribution of uranium and thorium in the Precambrian of the Western United States and the relationship of, time-space-facies patterns of uranium and thorium enrichment in the Precambrian to the major resources of uranium in the Mesozoic and Cenozoic host sedimentary rocks. This paper summarizes the results of preliminary studies of the Precambrian in the Southwestern United States including New Mexico, Arizona, southern Nevada, and southern California (Fig. 1). The host rock provenances for the major uranium resources in epigenetic deposits of Mesozoic and Cenozoic age in the Western United States were in areas of extensive Precambrian exposure along the eastern margin of the Phanerozoic geosynclinal belt (Fig. 2). Mesozoic continental clastic sediments in the Colorado Plateau contain about two-thirds of the uranium resource of the United States. These sediments formed from detritus derived from the Mogollon highland in the Southwestern United States where the Precambrian was extensively exposed (Stewart, et al., 19593 McKee, et al., 1959; McKee, et al., 1956; Craig, et al., 1955) (Fig. 2). A genetic relationship may exist between this provenance and the major uranium deposits of the Colorado Plateau. The Precambrian might be equally important in the genesis of uranium deposits whether the most important process in the formation of these deposits was the leaching of low-order intrinsic amounts of uranium from Precambrian granite or from Mesozoic pyroclastics derived from syntexis of the Precambrian basement rocks (Malan, 1968).

Jan 1, 1969

By Kenneth E. Hjelmstad

In situ leach mining operations often encounter difficulty maintaining adequate leach solution flow into the are formation. Swelling and dis-persion of clay particles in the formation are often responsible for this permeability loss. Permeability and leaching tests were done in the laboratory on clayey ores to evaluate a clay-stabilizing polymer's effectiveness in preventing these problems. Test results indicate that treating the ores with the stabilizer could maintain permeabilities two to five times greater than the long-term permeabilities present in untreated ores. Both alkaline (pH 8.5) and acidic (pH 2.0) leaches were used in the permeability-leaching tests. Since in situ leaching throughput rate is directly related to permeability, these results also indicate a potentially beneficial effect on operating parameters such as capacity and injection pressure. To determine the reasons for the success of the clay stabilizers, an investigation was conducted to cieter-mine the effect of the stabilizer on clay swelling and dispersion. Clay-swelling tests indicated that the clay stabilizer reduced clay swelling. Zeta potential measurements made on fine clay particles treated with the stabilizer were compared to measurements made on untreated particles and indicated that the stabilizer was electropositive and, therefore, could reduce the degree of negative charge on the particles and their tendency to disperse or migrate.

Jan 1, 1984

By C. RAMADINI, F. NURJAMAN, A. SHOFI, B. SUHARNO

In this work, the selective reduction of lateritic nickel ore was carried out using sodium sulfate, sodium carbonate, and sodium chloride as additives. The 5 wt% of anthracite coal, which contains 60.35% of fixed carbon and 1.9% of sulfur, was used as a reductant. All raw materials were mixed homogenously prior to the pelletization process into 10–15 mm of diameter. The reduction process was carried out to 50 g of pellets at 950 °C, 1050 °C, and 1150 °C for 60 min in a muffle furnace at atmospheric pressure. It continued with a wet magnetic separation process to separate ferronickel (concentrates) and impurities (tailings). Iron and nickel grade analysis was performed using XRF, while phase transformation and microstructure were analyzed with XRD and SEM–EDS. The results showed that the sodium sulfate was superior, resulting in the highest nickel grade in concentrate, i.e., 15.06%. The sulfidation mechanism, which could inhibit the metallization of iron, effectively increased the nickel grade in concentrate than decomposition of carbonate and chloridization process. The sulfur content in the reductant also influenced the selective reduction process. It promotes more sulfidation of iron, thus increasing the nickel grade in concentrate.

Jul 7, 2021

By Allan F. Lawrence

"I AM SURE you do not expect from me any learned dissertation on the problems and opportunities of the mining industry. Y our program committee must have recognized my limitations when issuing the invitation to speak to you, because they very thoughtfully left the subject wide open.With the leeway thus granted, I hope that you will bear with me for a few minutes while I try to clarify the impressions of the mining industry that I have gained in the very short time I have held the Mines portfolio and some of the parts that government bas or should have in furthering its development.As I see it, it is the duty of the Mines Department, as an arm of the provincial government, to balance the proprietary rights of all the people against the interests to whom the privilege of developing our resources are, in a s e n s e, leased. To strike a fair balance is not always easy, nor is it possible always to satisfy both sides. Still, under the free enterprise democratie form of government to which I think we al! subscribe, no better way of handling the problem has yet been discovered."

Jan 1, 1968

By I. Druce, C. Li, T. Qu, J. Dong, W. Y. Xinchao, V. Nkuna

CITIC Heavy Industries has a large installed base of grinding equipment throughout Africa in different configurations, including high-pressure grinding rollers with ball mill and semi-autogenous ball crusher. The total installed power of CITIC’s mills exceeds 430 MW. In this paper, we compare several typical grinding circuits of copper in Africa with about 15 kt/d throughput based on ore properties, process selection, equipment sizing, and key equipment capital and operating costs. Actual operating performance is also introduced. The comparison for the following mine sites provides a general reference for the selection of copper grinding circuits with this approximate throughput: Kamoa-Kakula Copper Mine with high-pressure grinding rollers with ball mill circuit, and Deziwa and Sicomine Copper-Cobalt Mines with semi-autogenous ball crusher circuits

Jan 1, 2023

By F. F. Aplan, J. A. Gutierrez-Rodriguez

"Contact-angle and flotation techniques were used to evaluate the influence of oxygen - both that inherent in the coal and that introduced by ambient temperature, aqueous oxidation - on a wide range of coal ranks. Oxidation was found to decrease the hydrophobicity and floatability of coal; with the effect being minor for coals of high rank but becoming increasingly important as the rank of coal is reduced. As an approximation, oxidation makes a coal behave as if it were one of lower rank. Frother only flotation' of coal· correlates with the captive-bubble contact angle whereas when oil is used as a collector, the flotation appears to follow the pattern shown by the water sessile drop on a fresh, un-reagentized coal surface. Coal recovery lost through oxidation may often be recovered by use of a variety of collectors, of which No. 2 foe! oil is among the best of those reagents tested. A simple alkali-extraction test may be used to estimate the influence of oxidation on coal preparation processes and use.INTRODUCTIONThe hydrophobicity of coal is not only a function of its rank but also of the extent of oxidation of the coal during and subsequent to its formation. Weathering and oxidation processes may proceed in-situ for coal deposits that outcrop near the earth's surface, or the oxidation of the coal particles may occur during mining, stockpiling or processing. Such oxidation, whether it affects the bulk-coal sample or on1y a thin outer layer on the coal surface, can dramatically influence the wettability of the particle and hence such processes as flotation, filtration, flocculation and dispersion.Many of the studies made on the oxidation of coals ·were designed to study its effect on flotation, coking or pyrolysis. The. present study 'is directed exclusively toward the effect of oxidation on the hydrophobicity and floatability of the coal. One of the first studies of the effect of oxidation on coal flotation was that of Sun [l] who found that as oxidation proceeds, coal becomes progressively more hydrophilic. Low-temperature oxidation (100-150°C for 250 h) generally lowered the coal floatability with an oily collector only slightly, but more extensive oxidation (200- 3500 C for 250 h) reduced coal floatability seriously. Sun also found that cationic amines were effective collectors for the oxidized coal which infers that oxidation makes the coal more negative in solution. He attributed the loss of floatability to be due to the accumulation of water-insoluble oxidation products at the coal surface. Gayle et al. [2] found that oxidation adversely affected coal flotation when an aliphatic-alcohol frother was used, though a small amount of oxidation appeared to improve the floatability of some coals using a kerosene-pine oil, collector-frother mixture in pilot-plant testing. Prolonged oxidation adversely affected the flotation recovery of the coals tested, the effect being more pronounced when an alcoholic-type frother only was used. They also noted that the reduction in floatability of lower rank bituminous coals was more affected by oxidation than was that of higher rank bituminous coals."

Jan 1, 1989

By MAURICE ALTMAYER

M Y DUTIES, as a member of the Department of Franco-American War Cooperation of the French High Commission were to study the copper and brass industries of America from the mining of the various non-ferrous metals to the semi-finished, or finished materials. In the pursuit of these studies, it was my privilege to visit a number of industries and organizations in different parts of the country. I first visited most of the Eastern copper refineries that were supplying the Allies with vast amounts of metal. These works are producing their material by the multiple or the series process, although the first method predominates. But, regardless of the process employed all the plants attain an exceptionally high standard of quality in their production. One of the points that particularly attracted attention was the manner in which improvements could be traced from the older worlds to the more recent ones. The impression was that, thanks to a spirit of broad-minded cooperation between the principals of the companies and frequent exchanges of views between members of the staffs, all persons interested benefitted by the experience thus gained, to the advantage of the community at large.

Jan 1, 1920

By R. Lindsay Mundell

In the first half of 1990, lessening of cold war tensions was welcome. But Iraq's invasion of Kuwait in August led to the Persian Gulf War in January and February 1991. The subsequent oil shock contributed to a dampening of the U.S. economy, and the U.S. gross national product rose only 0.9 % to $5,463 billion (U.S. billion = 109). The buildup of military forces in the Persian Gulf area focused greater attention not only on petroleum but also on other strategic materials. The U.S. Department of Defense continued to review stockpile goals and upgrade several mineral materials. In addition, the U.S. Bureau of Mines continued to maintain the standby Emergency Minerals Administration. After the Defense Production Act, which authorizes priorities, allocations, and supply expansion, lapsed on October 20, 1990, the Selective Service Act of 1967 became the authority to ensure that orders of the Armed Forces and defense atomic energy programs were given priority treatment.

Jan 1, 1993

By D. W. Mitchell

This Bureau of Mines report summarizes experience and past research on methods for sealing abandoned areas of a coal mine and areas from which the pillars have been wholly or partially extracted. The Federal Coal Mine Health and Safety Act of 1969 requires that such areas be ventilated or sealed with explosion-proof bulkheads, but the present study indicates that bulkheads alone cannot isolate areas in a coal mine in which methane and other dangerous gases have accumulated. Gas-air exchanges between sealed and open areas must be controlled.

Jan 1, 1971

By Thomas P. Dolley

Building stone, cassiterite, kaolin, gold, lime, and peat were the only commodities mined, The country's main economy was in agriculture, primarily in coffee exports. Tribal violence occurred again, between the Hutu and Tutsi tribes, causing an estimated 50,000 deaths, mainly in rural and mining areas. The inflation and a large deficit continued. The country continued to import cement, fertilizers, oil, and petroleum products. Burundi possessed numerous small gold deposits. The northwest and north-east were the country's two most important gold-bearing regions. A large kaolin deposit was found at Ngozi, and its mining was specified in the fifth 5-year development plan for 1988-1992. In the area of Rugombo, limestone was being explored with the intention of opening a cement plant.

Jan 1, 1990

By Phillip E. Butler

Since early 1973, the Pennsylvania Department of Transportation (PennDOT) has been actively engaged in the utilization of coal mine refuse in the design and construction of highway embankments. The Soils and Geological Engineering Division of the Bureau of Materials, Testing and Research has the task of managing the program which includes field investigations, laboratory testing, engineering evaluation, planning, coordination, implementation, construction control, and review of construction performance. The objectives of the utilization program, in removing colliery refuse banks and utilizing the material in construction, are the environmental and aesthetic rehabilitation of those areas in the Anthracite and Bituminous coal fields which have been plagued for such a long time by air and water pollution, and unsightly landscapes; and the economic rehabilitation of those areas occupied by refuse banks by providing usable land which can now be developed as residential, business, or industrial sites.

Jan 1, 1975

By Donald J. Frendzel

The post-World War II expansion of the Soviet petroleum industry has established the U.S.S.R. as a major oil-producing nation and has led to Russian reentry into the international petroleum trade. The rapid growth of Soviet petroleum production will allow the U.S.S.R. to displace Venezuela as the world's second largest oil-producer in 1960 and to narrow further the gap between Soviet and U.S. crude-oil production. U.S.S.R. crude oil output was only a tenth of U.S. production in 1946, but it will be more than a third at the end of 1960 and more than half in 1965. The Soviet Seven-Year Plan (1959-65) for oil provides for substantial increases in petroleum production, refining, storage, and distribution facilities. Crude oil production and primary distillation capacity are to double, considerable storage capacity is planned, and pipelines for crude oil and petroleum products are to increase threefold. According to the Soviets, the initial phases of this plan (1959 and 1960) have been completed successfully. However, this progress has been achieved with difficulty.

Jan 1, 1961

By M. Walawalkar, C. K. Nichol, G. Azimi

Rare earth elements (REEs) are essential to the production of technologically advanced products, including wind turbines, electric and hybrid cars, automotive catalytic convertors, hand held electronic devices, and military defense systems. Their application in environmentally beneficial technologies puts them at a high priority for ameliorating environmental concerns. Because of their increasingly high demand and limiting resources, it is highly beneficial to find new sources for them. The present study is focused on leaching REEs from a phosphate based fertilizer by-product, known as phosphogypsum (PG). Global estimated world production of PG is about 240 million tonnes that is stored in the form of wet stacks adjacent to fertilizer production facilities, occupying vast amounts of land. PG also contains trace metals, which are detrimental to the environment, and hence it is crucial to monitor these stacks. We obtained our PG sample from Agrium Inc. (a fertilizer manufacturing company in Canada). We performed a comprehensive characterization of the PG sample and found that it predominantly contains Y, La, Ce, Nd, and Sm. For leaching purposes, we used hydrometallurgical acid leaching techniques. We investigated three acids over a range of operating conditions such as acid concentration, temperature, solid-to-liquid ratio, and residence time. We achieved an average leaching of 81% with hydrochloric acid as leachant using operating conditions that can be easily replicated in industrial settings. If our process is implemented, not only will it reduce the size of the existing PG stacks (mitigating their environmental risks), but also enable the development of new innovative routes for extracting REEs, making countries like Canada less vulnerable to supply disruptions.

Jan 1, 2016

By T. R. Kostecki, A. J. S. Spearing, G. S. Esterhuizen, K. V. Jessu

Discontinuities are geologic occurrences in rock and when present within a pillar, reduce the strength of the pillar. Empirical formulas that are commonly used to determine pillar strength do not explicitly take into account the presence of discontinuities and thus can overestimate the pillar strength. The effect of discontinuities on the strength of pillars has been investigated using numerical models, but in these models, the discontinuity strike was parallel with the pillar faces. In this study, fully three-dimensional hard rock pillars were simulated using numerical modeling to understand the effect of the discontinuity dip direction on square and rectangular hard rock pillars. Based on the results, recommendations to assess a pillar’s strength in the presence of a discontinuity are discussed.

Jan 1, 2018

By Ritva Tuunila, Antti Häkkinen

"Wet stirred milling is one of the most effective grinding methods in producing very fine powders in large scale production, but it is a very energy-intensive process, especially when pigments or even nanosize particles are produced. Therefore, optimization of the process parameters is important. The specific energy consumption is a function of stress energy, which describes the effect of tip speed and media characteristics on grinding, and is related to the number of stress events during milling. In effective grinding, a large number of stress events are necessary. The stirrer configuration influences the number of stress events and their intensity, because the motion of the media and the suspension are caused by a rotating stirrer. The effect of three different stirrer types: a pin, disc and blade stirrer, on the grinding rate, i.e. product fineness and specific energy were investigated in this study with a batch laboratory stirred mill with two tip speeds. The material used in the experiments was calcium carbonate. The results obtained with the smaller tip speed showed approximately similar grinding rates and energy consumption for all stirrer types. When looking in closer detail, the blade stirrer seemed to give the finest product with all grinding times compared to the pin and disc stirrers, which both produced almost the same product fineness with the same grinding times. The specific energy consumption was the smallest with the disc stirrer, but not very big differences were obtained. With a higher tip speed, greater differences occurred both in grinding rates and specific energy consumption. The blade stirrer was the most effective in grinding, and the pin stirrer the next. The net energy consumption for the blade and pin stirrers was almost the same, but it was slightly higher for the disc stirrer."

Jan 1, 2014

By Louis D. Huntoon

(New Haven Meeting, February, 1909.) THE Hammond Mining and Metallurgical Laboratory is the gift of Prof. John Hays Hammond to the Sheffield Scientific School of Yale University. Professor Hammond was graduated from this school in the class of 1876, and has always shown great interest in its welfare and progress. In 1903, he offered to build and equip for it a mining and metallurgical laboratory. This offer was gratefully accepted by the trustees; and in October of the same year the architect, W. Gedney Beatty, and the writer were employed to draw up plans for the building, which is the largest of its kind in this country. The Treasurer's report shows the total gift of Professor Hammond, including land, building, and equipment, to have been $128,741.53. This does not include $5,000 given by Professor Hammond to defray incidental expenses. The detailed cost of the machinery and installation, included in the above sum, is as follows: Machinery, $9,846.00 Pipe and fittings, 925.05 Hangers, shafting, pulleys, belts, etc., . 357.83 Steel-work, tanks, launders, etc., . 272.19 Screens for sizing ore, 411.37 Lumber, 1,896.36 General Supplies Hardware, . $135.96 Tools, 263.66 Paints, . 04.63 Electric and incidental, . 439.57 - 1,043.82 Machine-shop material, 259.44 Labor, 722.29 - 981.73

Mar 1, 1909

Past arguments advocating reverse circulation sampling against blasthole sampling are reviewed to present the debate under a different light. The advantages and disadvantages of each drilling method are compared, and the choice is presented as an informed trade-off between them.

Mar 1, 2010