Search Documents

By S. A. Shuey

The present industrial practice used to separate aqueous cobalt from nickel is multistage solvent extraction processing. This paper describes a different but simpler treatment technology. The proposed technology has been applied to cobalt/nickel hydroxide intermediate solids produced from the treatment of Electrochemical Machining (ECM) waste sludge, The process consists of dissolving the cobalt/nickel hydroxides in basic cyanide solutions. Cobalt and nickel form aqueous .solution metal cyanide complexes. Nickel can be selectively precipitated from the solution as a nickellic hydroxide solid. Cobalt can be recovered from the leach solution by precipitation of a cobaltous/cobaltic cyanide double salt. The double salt product can then be subsequently treated to produce an appropriate cobalt product. The process chemistry, proposed fiowsheet and preliminary reagent costs are presented and discussed.

Jan 1, 1998

By Ned H. Snyder

In recent years the Government and other large consumers of coal have appreciated more and more the desirability of definitely determining by chemical analysis and test the character and quality of the coal they purchase. Higher prices for coal point forcibly to the need of giving more study to engine room and boiler room efficiencies and economies; this implies an intimate knowledge of the character and quality of the fuel used. Analyses and tests of delivered coal furnish data whereby power plant results can be comprehensively studied and a continuous check maintained on the coal and on the conditions of plant operation. Under authority of acts of Congress making appropriations for technologic investigation of fuels and the analyzing and testing of fuels belonging to or for the use of the United States Government, a laboratory is maintained at the Pittsburgh station of the Bureau of Mines, where samples representing deliveries of coal purchased for Government use are analyzed and tested. The Bureau of Mines has been active in promoting the purchase of coal by the Government under specifications/ that is, by contracts that make definite requirements regarding the heating value of the coal, expressed in British thermal units, and the composition as shown by proximate analysis. Under many of these specification contracts the bidders guarantee the quality of the coal offered, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled and analyzed to determine whether the coal is of the quality guaranteed by the contractor, and if it is not, the price to be paid is decreased in proportion; but if the coal is of higher quality, the price is proportionately increased. The known analyses of coals or the guaranteed analyses offered by the bidders may sometimes be used for determining the award of a contract, but if the coals offered differ widely in characteristics, it may be difficult to determine which would prove the cheapest fuel without data on their relative evaporative efficiencies. Hence, the making of evaporative tests under service conditions may be necessary in order to determine which coal is particularly adapted for successful and economical use in a certain plant. Once a particular coal is selected, however, regardless of the procedure of determining the award of a contract, then the greatest advantage of the specification method is realized, for it guarantees the purchaser receiving coal of uniform character and quality, thereby insuring the best results in the plant. The success of the specification method for the purchase of coal and the reliability of analysis now rests largely on sampling.3 Improper sampling leads to controversies, with resulting condemnation of the specification method in general and of the value of laboratory analyses and tests in particular.

Jan 1, 1922

By A Trench, S Ulrich, S Hagemann

A synthesis of reported All-In Sustaining Costs (AISC) for 57 Australian gold mines in the period 2014–2016 reveals for the first time the clear influence of grade upon cost performance, most evident in gold-only underground mines. Past syntheses of costs on a single quarter basis have viewed grade as potentially subordinate to other factors such as production scale, mine geometry, mineralisation style and a combination of other mining-related costs. Better understanding of the grade to cost relationship on both an individual mine and whole-of-portfolio portfolio basis is needed. Insight into the roles and trade-offs between other cost-determining factors will aid the future sustainability of the gold mining sector in Australia and assist in targeting prospects for future resource growth and development. While the overall trend is toward higher-grade mines displaying lower costs and vice versa, the grade to cost functions appear radically different between mines based on time-series data. The median cost of Australian gold production in the final quarter of 2016 was A$1081/oz. The threshold for lowest cost quartile production was A$965/oz. Underground production now dominates Australian gold output – with 71 per cent of ounces originating from operations that are either entirely underground or hybrid pit/underground mines. Scale economies are evident, with smaller mines predominately among the higher cost producers. For mines of equal grade, open pit mines are lower cost than underground operations. Reserves are modest, with a median mine life for underground operations of 4.7 years based on current production rates. Reserve additions at mines are likely constrained not only by the finite nature of mineralisation at each mine but also by the geometrical difficulty of accessing suitable drilling locations to test for reserve extensions.CITATION:Ulrich, S, Trench, A and Hagemann, S, 2017. Towards an understanding of production costs at Australia’s underground gold mines, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 241–250 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By Anderson Alves Cunha

Diante do cenário macroeconômico internacional, o setor mineral busca soluções inovadoras e sustentáveis para seus processos produtivos. Uma dessas soluções é, sem dúvida, aumentar a recuperação do mineral de interesse presente no rejeito proveniente de operações de beneficiamento de baixa recuperação metalúrgica. A substituição de matérias primas naturais por resíduos abre uma gama de oportunidades para melhorar a gestão de recursos não renováveis, contribuindo significativamente para o desenvolvimento sustentável e competitividade do negócio. O presente trabalho tem o objetivo de definir qual a faixa granulométrica, existente na lama, é mais adequada para concentrar e produzir pelotas, considerando a composição química, perda por calcinação, mineralogia e quantidade de elementos deletérios. Para isso, foram utilizadas técnicas de caracterização tecnológica, como: classificação granulométrica (peneiramento a úmido e cyclosizer), fluorescência de raios X, difração de raios X e microscopia óptica. Os resultados do trabalho permitiram identificar uma faixa granulométrica com alto teor de ferro e alto grau de liberação dos minerais de ferro, porém com teores de quartzo acima que um pellet feed comercial. Sendo assim, um determinado tratamento de concentração ou um blend será necessário para adequar quimicamente o material, para posterior obtenção de pelotas com baixo custo.

Aug 17, 2017

By D M. Verster, P L. Gillot, A Kone

Randgold ResourcesÆ MorilaÆs gold leach plant is subjected to uncommon æoxygen stressesÆ. Feed ores exhibit very high oxygen demands, primarily caused by iron sulfides. In addition, ore oxygen demand varies significantly over time, as well as between different feed ore sources. The inability of the Morila gold leach plantÆs oxygenation system to cope with these high and fluctuating oxygen stresses manifested itself in variable gold residue grades, and cyanide consumption rates.Management launched a Morila oxygen system review project during September 2009, with the objective of auditing the performance of the then current oxygenation system, against required performance parameters as calculated from oxygen demands of the various feed ore types and targeted dissolved oxygen levels in the leach train.This paper describes the systematic changes made since 2009 to the Morila oxygen system in four main areas: O2-supply plant, O2-volumes, O2-controls and oxygenation equipment. Data are provided on corresponding improvements in leach plant performance. Theoretical, as well as practical aspects of gold leach oxygenation systems are covered.CITATION:Verster, D M, Gillot, P L and Kone, A, 2013. Oxygenation system upgrades and leach plant performance improvements at Morila Gold Mine - 2009 to 2012, in Proceedings World Gold 2013 , pp 215-224 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By D. Mannino, M. Townsend, E. Daniloff, E. Petsonk

Nonspecific airway hyperresponsiveness is a central feature of chronic obstructive pulmonary disease and has been associated with atopy in the presence of environmental exposures such as smoking. Coal miners may develop emphysema and lung function decrements related to their dust exposure. To investigate the roles of airway responsiveness and atopy in these effects, we evaluated the relationships among smoking, a history of hay fever or seasonal rhinitis, and airway responsiveness (AR) in a group of underground bituminous coal miners and nonmining controls. All subjects had a normal baseline percent predicted FEV1. Increased airway responsiveness was defined as a 15% or greater decrease in FEV1 following methacholine inhalation. 85 miners (45%) and 99 controls (46%) were current smokers, 59 miners (31%) and 55 controls (26%) were lifetime nonsmokers; former smokers were excluded from further analysis. Overall, 25% of 144 miners included in this analysis had increased AR, as opposed to 29% of 155 controls. Thirty-seven percent of both miners and controls had a history of seasonal rhinitis. Significantly fewer miners (15%) had a history of hay fever compared to controls (25%, p< 0.05). Figure 1 shows the prevalence of increased airway responsiveness in miners and controls in association with hay fever. In both smoking and non smoking miners the presence of a hay fever history was significantly (p < 0.05) associated with a higher prevalence of increased AR. Little effect was seen in smoking (p = 0.827) and nonsmoking (p = 0.940) controls. Figure 2 shows a similar higher prevalence of increased AR associated with symptoms of seasonal rhinitis in the mining group. This was significant (p < 0.01) only in the smoking miners. No effect was noted in the controls. These data suggest that the association of a history of hay fever or seasonal rhinitis symptoms with increased airway responsiveness may be more common in coal mining, compared to non-dusty occupations. Although the implication of these data are unclear, further study of miners with a history of hay fever or seasonal rhinitis is warranted. (Supported in part by Grants G1135142 and G1105142, US Bureau of Mines, Generic Mineral Technology Center for Respirable Dust)

Jan 1, 1991

By H. J. Struth

The benefits of proration of oil production were perhaps more concretely realized in 1932 than at any time since the oil industry adopted nation-wide production control. Reduced output of crude petroleum, which brought the daily average of the United States down to approximately 2,000,000 bbl. from a peak in 1931 of more than 2,600,000, had a telling effect on the trend of oil prices. Mid-Continent crude was advanced in price from 776, for 36-gravity oil, to $1.04 a barrel. California crude, of 26-gravity at Signal Hill, moved forward from 736 to 976 a barrel. Pennsylvania crude, the only exception to the upward trend, rose in price from $1.82 per barrel to $2.02, only to react to $1.72. This was due to local conditions which necessitated an adjustment to overcome competition from other areas of the United States. East Texas continued to exert a far-reaching influence on the crude and gasoline market during 1932. Despite the fact that oil prices were advanced in most fields, large quantities of oil were produced in East Texas in violation of state proration orders, and sold in the market at prices considerably below official postings. This created competitive conditions in the gasoline market that were felt by all refining centers of the United States. The quantity of gasoline produced from cheap East Texas crude was not large, but the volume was sufficient to influence prices in practically all sections of the country. Thus, while the industry&apos;s&apos; economic situation showed visible improvement statistically, the unreported and unseen statistics originating in East Texas proved to be an insurmountable obstacle to the economic betterment that was otherwise apparently justified. Somewhat surprising to many was the fact that gasoline consumption was maintained within 10 per cent of the preceding year. Domestic consumption showed only a net decline under 1931 of about 8.5 per cent; exports dropped in volume to the extent of about 23 per cent. As a matter of fact, domestic gasoline consumption was only about 1.4 per cent less than it was in the predepression year of 1929. Exports, however,

Jan 1, 1933

By David Keys

THE object of this investigation was to determine with a vertical magnetic variometer the extent of the titaniferous ore deposit that occurs not far from Ivry in Terrebonne County, Quebec, about 70 miles north of Montreal. The Ivry mine, on lots 37 and 38 of range V, Beres-ford township, Quebec, is one of the largest and most accessible to transportation of the deposits of ilmenite in Quebec. The ore consists of an aggregate of ilmenite anhedra serving as host for numerous fine plaques of hematite. No magnetite is known from any occurrence near this lot, and in this way the deposit differs from many others that contain a large percentage of magnetite with the ilmenite. The deposit at Ivry thus has much lower magnetic susceptibility than those containing abun-dant magnetite, and a sensitive magnetometer was necessary for the work, although a body of magnetite with ilmenite about a mile from the Ivry mine was successfully prospected with a dip needle. The principal orebody is exposed in a quarry known as the Ivry mine, from which about 16,000 tons of ore have been shipped. Small exposures of ilmenite isolated by drift serve to show the presence at the surface of some of the bodies indicated by the magnetometer,- but most of the hill is covered with glacial till and second growth hardwood. At the lower levels the till gives place to fluvioglacial sands and gravels from which the forest has been cleared. The increasing thickness of the sand and gravel as the hill descends makes the tracing outward of the deposits from the rocky knob of anorthosite a difficult matter. Within the orebodies too, some masses of anorthosite persist, which may account for some local irregularities. Fig. 1 is a photomicrograph, taken by reflected light, of a typical specimen of the ore. The dark patches are hematite and the light parts are ilmenite. No trace of magnetite was found. Fig. 2 is a photo-micrograph of a thin section of the country rock showing the texture of the anorthosite. The mean of four analyses quoted by Robinson1 is: titanium, 19.26 per cent; iron 45:41 per cent.

Jan 1, 1936

By Mateus Sotelo Menezes

Uma ferramenta de trefilação deve suportar as altas tensões a que fica submetida durante o processo sem apresentar deformações. Para isso, o projeto da fieira deve iniciar com a escolha correta do material de fabricação e um dimensionamento adequado. Tais fatores podem minimizar a ocorrência de falhas, tanto na fieira, quanto no produto trefilado, assim como diminuir as tensões e desgaste na ferramenta. Portanto, este estudo visa analisar as regiões de uma ferramenta de trefilação industrial que estão sujeitas as maiores amplitudes de tensões ao longo de um processo de trefilação. O método de elementos finitos foi utilizado para simular a trefilação de uma barra de aço utilizando uma ferramenta de carbeto de tungstênio. O perfil da fieira foi inserido no software e então analisado em diferentes etapas ao longo do processo de trefilação e após o seu término. Observou-se a ocorrência de tensões compressivas superiores a 600 MPa na região de trabalho e as maiores tensões trativas foram visualizadas na região de saída, com valores próximos a 200 MPa. A presença de tensões residuais não foi registrada na fieira, como esperado.

Aug 17, 2017

By Seth C. Schaefer

The Federal Bureau of Mines studied the Gibbs free energies of formation of chromous fluoride (CrF2), chromic fluoride (CrF3), and chromium (II,III) fluorides (CrF2.40 and CrF2.45) with high-temperature galvanic cells employing calcium fluoride doped with 1 mole-pct yttrium fluoride as the electrolyte. Free-energy changes were obtained from open-circuit potential measurements for the following cells: Cr, CrF2 // CaF2 // NiF2, Ni (a) NiO, NiF2 // CaF2 // CrF3 , Cr203 (b) CrF2 , CrF2.40 // CaF2 // NiF2, Ni (c) and CrF2 ?45 , CrF3 // CaF2 // NiF2, Ni (d) with the following overall reactions Cr(s) + NiF2 (s) = Ni(s) + CrF2 (s) (1) 3NiO(s) + 2CrF3 (s) = 3NiF2 (s) + Cr203 (s) (2) 5CrF2 (s) + NiF2 (s) = 5CrF2.4O (s) + Ni(s) (3) and 3.64CrF2.45 + NiF2 (s) = 3.64CrF3 (s) + Ni (s) . (4) These results were combined with the best available literature values of ?Gf° of NiF2, NiO, and Cr203 to deduce Gibbs free energies of formation for the chromium fluorides expressed as follows: ?Gf°(CrF2) = -179.31 + 24.33 X 10-3T ± 0.43 kcal-mole. (5) (858.1 - 964.9 K) ?Gf° (CrF3) _ -226.16 + 1.82 X 10-3T ± 0.79 kcal/mole (6) (880.8 - 957.8 K) ?Gf°(CrF2.40) _ -213.65 + 32.14 X 10-3T ± 0.44 kcal/mole (7) (0053.9 - 936.8 K) and ?Gf°(CrF2.45) _ -176.17 - 12.67 X 10-3T ± 0.80 kcal/mole (8) (875.1 - 937.6 K). Free energies and equilibrium fluorine pressures for three univariant and one bivariant equilibria are illustrated.

Jan 1, 1976

By Márcia Maria Salgado Lopes

Este trabalho busca avaliar a utilização do resíduo de granito, como pigmento, em tintas para construção civil, que atendam aos requisitos de uma tecnologia social. Inicialmente, caracterizou-se o resíduo, para determinar a potencialidade de uso desse material em tintas. Para a produção das amostras de tintas, definiu-se um modelo experimental, baseado na variação das proporções dos componentes da mistura. Nesse modelo, as proporções de pigmento e resina foram definidas de acordo com a faixa de variação de PVC (Pigment Volume Concentration) esperada para uma tinta fosca. Já a proporção de água variou, de modo a se manter a viscosidade dentro de uma faixa que permitisse a boa aplicação da tinta. Em seguida, foram realizados ensaios de determinação do poder de cobertura e resistência à abrasão para cada uma das amostras. Verificou-se que, o resíduo de granito apresenta características que o habilitam a ser utilizado, como pigmento, em tintas. Notou-se ainda que foi possível produzir misturas com elevados teores de sólidos e que o PVC exerceu grande influência sobre o desempenho das tintas. Entretanto, os resultados dos ensaios de determinação de desempenho indicaram que em nenhuma das misturas produzidas foi possível atender simultaneamente aos requisitos estabelecidos pela ABNT NBR 15079:2011.

Oct 30, 2017

By Sofia Martins, Anna Lichtschlag, Sven Petersen, Fernando Barriga, Bramley Murton, Adeline Dutrieux

"Sediments in the vicinity of the hydrothermal seafloor massive sulphide (SMS) mounds are characterized by high concentration of metallic particles. They result from a long process of weathering of the primary mineral deposits and have been accumulated in depressions by mass wasting and hydrothermal plume fall-out. We present here the first results obtained on pore waters analyses of such sediments in distinct geological seafloor environments (in low-temperature hydrothermally active zones, on extinct hydrothermal mounds and in a remote depositional channel). Vertical concentration profiles suggest that the pore fluid composition is affected more by seawater circulation compared with hydrothermal fluid flow in all environments. The composition of pore fluids is affected by diagenesis and redox processes in the distal depositional channel where Mn2+ is released at depth with Cu2+.IntroductionMarine hydrothermal fields, hosting seafloor massive sulphides, are potential resources for future deep-sea mining and might become economic reserves for the industries. They are widespread at mid-oceanic ridges, arcs and back-arc spreading centers (Hannington et al., 2011; German et al., 2016). Sediments in the vicinity of these fields can contain unusually high concentration of Fe, Mn, Zn and Cu among other metal elements (Shearme et al., 1983). These hydrothermal, or metalliferous, sediments result from a combination of processes such as collapsing and weathering of chimney material, filling of the channels by turbidite-like mass wasting, in situ authigenic mineralization and hydrothermal plume fall-out (Goulding et al., 1998; German et al., 1990). The sediments contain important indicators reflecting the development of the hydrothermal systems. Because of their widespread distribution and metal content, they themselves can be considered potential mineral resources. Circulation of seawater through these deposits, however, often modifies the sediment composition by oxidizing the sulphides into oxyhydroxides and clays causing mobilization of the metals. To address the importance of alteration and diagenesis of these hydrothermal sediments, including the result of seawater circulation, we investigated the post-depositional processes occurring in the hydrothermal sediments at the TAG Hydrothermal Field (Mid-Atlantic Ridge, 26°N), focusing on the mobility of metallic cations in a number of different seafloor environments."

Jan 1, 2017

By J. A. Abols, P. M. Grady

Recovery via gravity is one of the oldest mineral processing methods available. Unfortunately, the use of gravity techniques for gold recovery has been in decline for the past century as more effective chemical processes such as flotation and leach/CIP have been developed. Recently, with the push towards more sustainable environmental outcomes, the benefits of gravity separation have become more apparent. While gravity as a unit process is not usually capable of achieving as high a recovery as flotation or whole ore cyanidation, a combination of gravity devices alone or in conjunction with these processes can offer significant advantages to the operator. This paper reviews the range of gravity devices available, their application and the results that can be achieved by maximizing gravity through the use of a combination of gravity recovery devices. Three case studies are provided.

Jan 1, 2005

By J. S. McEwan

This paper describes the derivation of a set of simultaneous algebraic equations that can be solved to produce a rigorous theoretical mass balance around solution mining wells. This mass balance can then be compared with a mass balance calculated from field measurements to provide the percentage of mass balance closure. Significant deviations from the closure can be an indication that the wells are either gaining or losing circulation fluids. The equations also provide calculations for the amount of water and dissolved mineral that accumulates in the well during the mining process, as well as the net mining rate. Equations for both single mineral mining and multiple mineral mining are discussed. They can easily be formatted into spread sheets for rapid calculation of field measurement data.

Jan 1, 2010

By M. Hesham El Naggar, Mehdi Heidari

"Equivalent fixed-base cantilever model is a common approach for performance base seismic design of bridge structures supported by extended pile-shaft. In this method, global displacement ductility factor is related to local curvature ductility demand by assuming a concentrated plastic hinge at location of maximum bending moment. Equivalent plastic hinge length is one of the key parameters that should be assumed accurately in kinematic expression of the cantilever model. Although, some expressions have proposed to estimate the length of the in-ground plastic hinge; however, these relations yield differing results. In this paper, a general expression is derived based on the concept of distributed plasticity to predict the plastic region of yielded piles in clay and sand. A length modification factor is defined to relate the equivalent length of plastic hinge to the real plastic zone. Then, results from nonlinear pushover analyses are used to propose an equation for the modification factor as a function of displacement ductility factor.IntroductionDuring severe earthquake events, development of the plastic hinge in pile foundation below ground level is inevitable for bridge structures supported on extended pile-shafts. A common approach for seismic design of the yielding pile-shafts is to replace the pile-soil system by an equivalent fixed-base cantilever assuming the equivalent system has the same global response as that of the pile-shaft (Budek et al. 2000; Chai 2002). In this method, plastic curvature is concentrated at the center of the equivalent plastic hinge below ground surface. Prior knowledge of plastic-hinge length is essential for proper assessment of assess plastic displacement at the top of the pile-shaft. Unfortunately, existing recommendations for estimating plastichinge length are largely incomplete and/or inadequate.During the last two decades, several relationships have proposed for evaluating the equivalent plastic hinge length, Lp, based on experimental and numerical studies. Budek et al. (2000) conducted numerical modeling to calculate the plastic-hinge length of piles embedded in cohesionless soil. They found that the plastichinge length varies linearly with both soil stiffness and aboveground height, e. Chai and Hutchinson (2002) conducted full-scale experimental tests on reinforced concrete piles in sand. They reported that Lp depends primarily on the aboveground height of the pile, neither sensitive to the soil stiffness nor to the value of displacement ductility factor. They stated that the equivalent plastic hinge length is relatively independent of the displacement ductility factor and is not very sensitive to the change in soil density. On the contrary, Goel (2014) and Liu et al. (2016) conducted nonlinear numerical analyses which revealed that Lp changes with the displacement ductility factor and even suggested that using different values of Lp for different seismic design levels is essential for a reliable estimation of the ductility capacity."

Jan 1, 2017

By L. Kilburn

"A survey of 281 mineral exploration agreements examines the ratios among three ways that may be used to purchase an interest in a mineral property, viz: pay cash, pay shares and make future expenditures on the property.The dollar value of the future expenditures exceeds that of cash or shares by about nine times in most of the 110 agreements that contain cash-expenditure or share-expenditure components. Results suggest that cash and shares are treated about the same in terms of value.Buyers and sellers have opposing priorities for the way that they prefer to purchase a mineral property. These opposing priorities should give rise to a perceived 50:50 balance between cash/share payment and future expenditures to satisfy the idealized situation described by most definitions of fair market value (FMV). This balance between cash/share payments and future expenditures appears to be rationalized in negotiations to a FMV when expenditures are nine times greater than cash and/or payments.On this basis, it is proposed that the FMV of a property may be determined by aggregating the dollar amount of the cash/share payments plus one-ninth the dollar value of future expenditures, as set forth in the respective purchase agreement, and proportionately applying such aggregate to full property value."

Jan 1, 2005

By R. D. Currie

A study of the accident statistics in the coal mining industry convinces one that an organized effort must be put forth to prevent the vast destruction of human life in this industry . The fatality rate in Pennsylvania has not improved in the past several years and during 1928 it was higher than the average for the period 1916 to 1927 , inclusive . Although the accident rate for this State is less than that of the coal mines of the United States as a whole , nevertheless the rate is unduly high ; however , there are many companies which have exceptionally good records as regards both fatal and nonfatal accidents . A study of the methods used by some of these relatively good- record companies to reduce accidents in their mines shows that they exert an organized effort to prevent accidents , and that their safety organizations usually affect every employee in and about the mine from the highest official to the check boy . The chief executive must be actively and personally interested in accident prevention if real safety results are to be obtained ; when he shows this interest it is almost invariably reflected in the officials under him and throughout the organization . Safety organizations vary in form and are readily changed or adapted to the varying conditions found in the bituminous field . The companies whose organizations were studied in preparing this report are all getting good results , and it is their opinion that the safety organizations have been a big factor in obtaining these results . At their request the identity of some of the companies whose organizations were studied has not been divulged in this paper , but this does not affect the value of the information concerning their safety organizations .

Mar 1, 1931

By Philip G. Freeman

The growth-promoting properties of coal-derived humus were tested by a variety of bioassay methods. Humate materials used included leonardite, a form of naturally oxidized lignite, and humic acids extracted from leonardite. It was found that the greatest effects were evident when water-soluble humic acid was applied to excised root tips. No significant short-term effect was noted when water-soluble humic acid was applied to stem or coleoptile sections. Root initiation was promoted in bean stems when high concentrations of coal-derived humate were applied. Gross weight of tomato plants was increased by up to 40 percent when coal-derived humates were added in concentrations of 101 to 104 ppm to the nutrient in a hydroponic growth test of 6 weeks&apos; duration. It is concluded that coal-derived humate promotes the uptake of minerals, specifically iron, by serving as a metal chelate.

Jan 1, 1968

By Paulo César Pontelo

Buscando atender seus clientes com soluções inovadoras no campo do tratamento de metais líquidos, a Sidertec efetuou a atualização tecnológica do sistema de dessulfuração primária de uma grande usina integrada brasileira trazendo o seu sistema antes obsoleto para o estado da arte em dessulfuração e ainda substituindo o dessulfurante a base de CaC2 anteriormente utilizado por PureSteel®; tendo como benefícios a otimização do processo, redução de custo de 61% e melhora na condição de segurança operacional pela retirada de produto perigoso do processo da usina. Esta implementação utilizou o Know How Sidertec e se baseou na metodologia de estudo do problema, aprofundamento de engenharia das possíveis soluções e realização do revamping proposto.

Aug 17, 2017

By G. Rong, W. Du

Stability of some potential unstable blocks in the left bank slope of Baihetan hydropower station is evaluated in this paper using the three-dimensional (3D) limit equilibrium method. The Baihetan hydropower station is in the downstream of Jinshajiang River, China. The geological condition in the river valley is complex, and many large discontinuities are detected in the slope of the two banks. As a result, much attention should be paid to the stability of the slope in the feasibility study stage. Because the left bank slope is an oblique consequent one, we mainly focus on the slope stability analysis in the left bank. Comprehensive geological exploration is conducted in the studied area and the detected discontinuities are well researched. By building a 3D geological model of the left bank slope, three potential unstable blocks which are close to the dam site are detected. An irregular wedge analysis method is then used to calculate safety factors of the three blocks under three conditions, which are natural condition, rainfall condition, and seismic condition, respectively. It is found that the safety factors of the block 1# and the block 2# are quite low when compared to the suggested values. Extra care must be exercised when excavating the slope near the block 1# and the block 2#. A preliminary reinforcement is also suggested.

Jan 1, 2015