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By Eduardo Cabral

A introdução da tecnologia intensiva de mistura nas plantas de sinterização de minério de ferro tem sido vital nos últimos 20 anos, dado o fato do progressivo afinamento do minério e a necessidade de manter ou até diminuir os custos operacionais das sinterizações. As características intrínsecas da mistura intensiva facilitam a incorporação de finos cada vez mais presentes nas formulações promovendo sua aglomeração de forma eficiente, sem perda de produtividade e com economia de coque, água e energia por tonelada produzida.

Aug 17, 2017

By Rakesh Kumar, S. Mehrotra, T. Alex

"This paper, an overview of our recent findings on mechanical activation (MA) of minerals/materials, emphasizes the importance of sample genesis, mechanically induced/altered porosity and surface area, mineral interactions, glassy inorganic materials, surface alteration and zeta potential changes and, mechanically induced reactivity of solids. Materials investigated include Al-oxyhydroxides (gibbsite and boehmite), fly ash and granulated blast furnace slag. Planetary, attrition, vibratory and conventional ball mills are used for MA. Genesis of boehmite has been found to have a bearing on its behavior during MA. For example, BET specific surface area (SSA) of boehmite prepared by thermal dehydroxylation of gibbsite has decreased from 265 to 65 m2/g during 240 min of MA; in contrast, the SSA of hydrothermal boehmite has increased from ~2 to 36 m2/g. Mechanisms of surface area changes in the two boehmite samples differing in their genesis is explored. MA of gibbsite and its mixture with hematite/quartz using attrition milling has indicated that the presence of the second phase promotes amorphisation. Amorphous materials show signs of change in nature of bonding during milling as illustrated by MA of fly ash. Physicochemical changes during MA are not restricted to the bulk phase. The genesis of zeta potential changes in MA solids can be many; for example texture induced zeta potential changes as observed for gibbsite, while zeta potential changes during the milling of granulated blast furnace slag occur due to enhanced (possibly non-congruent) dissolution. Interesting manifestations of mechanically induced reactivity and its correlation with physicochemical changes are illustrated in terms of alkali leaching of boehmite and, hydration of MA slag. New findings reported here are associated with several open questions and are highlighted in the paper."

Jan 1, 2014

By Kent R. Van Horn, W. P. Sykes

Since Honda and Murakamil in 1918 proposed their constitutional diagram of the carbon-free iron-tungsten system, considerable effort has been expended by several investigators in attempts to define more positively the structural features of the alloys. The existence of an intermediate phase corresponding to the formula Fe3W2 (68.7 per cent W) was proposed from evidence of a purely metallographic nature by one of the present authors2 in 1926. Since that time the identity of this phase has been confirmed by Arnfelt3 and by Takeda,4 both of whom employed X-ray methods as well as the microscope and the chemical analysis of isolated microconstituents. According to Arnfelt, Fe3W2, as crystallized from the iron-rich melts at a temperature above 1450° C., contains by analysis 68.7 per cent W. The lattice of this phase is characterized by trigonal symmetry. Arnfelt, moreover, proposed a second intermediate phase formed at some temperature between 1450" and 1000" C. by a peritectoid reaction involving Fe3W2 and the iron-rich solid solution. A melt containing 25 per cent W was cooled to 1000" C. and heated for 100 hr. The precipitated tungsten-rich constituent was separated and found by analysis to contain 62.6 per cent W. This composition agrees closely with that represented by the formula Fe2W (62.2 per cent W). Diffraction patterns from the concentrated precipitate showed a hexagonal unit cell. Takeda confirmed the data of Arnfelt regarding Fe3W2 but was unable to detect Arnfelt's second intermediate phase. While Takeda failed to describe in detail the treatments employed, he stated that in alloys containing 40 per cent W which were quenched after heating at various temperatures between 1200" and 1450" C. no evidence of the second phase (Fe2W) was observed 'either in the microstructure or in the diffraction patterns of isolated residues. He therefore considered the existence of this low-temperature hexagonal compound as disproved.

Jan 1, 1933

By Francis Dakubo, Courtney Young, Avimanyu Das

"Hydrometallurgy of copper ores typically involve acid leaching followed by solvent extraction and electrowinning (SX/EW). EW is the final purification stage in which a voltage is applied across two electrodes causing the copper ions to reduce and deposit on the cathode. Applied voltages are near 2 volts with current densities around 300 amps/m2. In this study, research was undertaken to decrease the energy consumed in the EW process. To do this, various cell designs were constructed and tested in which a membrane was used to separate the cathode and anode compartments with concentrated solution from SX serving as catholyte and raffinate from SX serving as anolyte. Therefore, copper in the concentrated solution would be deposited on the cathode while ferrous in the raffinate would be oxidized to ferric at the anode. Because it is assumed that ferric acid leaching is used, resulting ferric would be recycled to the leaching process. A positive side effect of the envisioned process would be the elimination of oxygen evolution at the anode and thus the prevention of acid-misting. After a cell design was selected, it was used to test a number of variables: flowrate, concentration, temperature, ion-exchange membrane, and applied voltage. Following experiments in which variable ranges were determined, statistical modeling was conducted using STATEASE software. Optimal results indicate the voltage can be decreased to 1.5-1.7 volts with current densities of 300-400 amps/m2. Significant reduction in the energy consumption was accomplished by reducing the applied voltage. Furthermore, current efficiencies and copper production rates was increased by application of the membrane.INTRODUCTIONLeaching of copper ores is achieved using mostly sulfuric acid. The copper pregnant solution is contacted with an organic solvent or resin adsorbent which picks up copper ions as in Equation 1:"

Jan 1, 2016

By José Claudio Blanco

A medição de Planicidade sem contato (contactless) para Laminadores a Frio é efetuada com o sistema conhecido como SIFLAT. Os sensores utilizam tecnologia eddy current como medição precisa de amplitude entre o sensor e a chapa na qual será medida a planicidade. Os resultados convertido para valores de planicidade são de alta qualidade e precisão na mediação que serão posteriormente enviadas ao sistema de controle de planicidade. Este sistema é aplicado em laminadores de chapas a frio e linha de processo.

Aug 16, 2017

By H. M. Kraner, R. C. Devries, K. H. Gee, E. F. Osborn

On the basis of liquidus measurements in the system COO-Mg0-Al2O3-Sio, and previously published data, diagrams have been constructed at 5 pct Al2O3, intervals from 5 to 35 pct Al2O3,. Liquidus temperatures and primary phase fields are shown. The optimum composition of a blast furnace slag for a given alumina content is indicated. At the optimum point, ordinary slags will be entirely liquid and will have maximum desulphurization potential and minimum viscosity. The relation of optimum composition of slags to the "plateau region" of the liquidus surface, and the application of these data on synthetic quaternary slags to actual slag compositions are discussed. Index of refraction of glasses is given as well as composition, temperature, and phase data for each mixture. THE usual blast furnace slag, as a first approximation, can be considered a mixture of the four oxides, CaO, MgO, Also,, and SiO,. Systematic, extensive data for the quaternary system, CaO-MgO-A1,0,-SiO, is therefore required for the understanding of the properties of such a slag as a function of composition and temperature. With sufficient data, it should be possible to fix unequivocably the relative amounts of lime, magnesia, and silica required for a given alumina content to result in a slag composition having optimum properties. Other constituents, such as FeO, MnO, Ti02, and S, have an effect on the properties of a slag, but as long as they are present in small and approximately constant amounts they produce only a second-order effect superimposed upon the major changes in properties of slags determined by the relative amounts of the four major components. Viscosity and desulphurization data have been reported for mixtures approaching blast furnace slags in composition, but systematic liquidus data have not been obtained. Inasmuch as a slag must be all liquid in order to be most effective as well as practicable, clearly the temperature above which a mixture is all liquid (liquidus temperature) is a type of data needed. Such data have been obtained through the study of 446 compositions and are pre- sented in this paper along with a discussion of their bearing on the optimum composition of blast furnace slags. For an orderly presentation of the data, the quaternary system is viewed as a tetrahedron with one component at each apex. Fig. 1 shows a tetrahedron representing the system Ca0-Mg0-A1,0,-Si0,. The base is the ternary system Ca0-Mg0-SiO,, A1,0, is the top apex, and the front face, the system CaO-

Jan 1, 1955

By Anthony Edey, Leigh A. Readdy, Bruce A. Kennedy

Introduction Very little attention normally is given by the experts, or the public at large, to the fact that the majority of the oil that has been or will be discovered within the U.S. remains in the ground. The inherent limitations of oil production through surface wells, either by primary or secondary techniques, will result in a total of over 300 billion bbl of oil left in the ground after completing production by standard petroleum techniques in currently producing or producible fields. This reserve represents some two-thirds of the original quantity of oil discovered in place. Recent work by a number of groups has shown that there is strong economic justification for extracting this remaining oil by mining and processing techniques. Table 1, taken from 1977 API reports, demonstrates the oil left in place at the end of the con¬ventional petroleum production cycle in then-known fields within the U.S. Possible targets for oil mining operations include (1) oil remaining in place in fields and pools that have reached economic depletion by current petroleum production methods and that are not amenable to economic recovery by conventional petroleum industry techniques; (2) oil-or bitumen-saturated rocks not normally considered by the industry to constitute producible reservoirs, such as shales and diatomites; and (3) asphalt- and bitumen-impregnated rocks. Economically Depleted Fields A more detailed examination of the depleted fields shows that estimates of oil remaining in place after primary, secondary, and nondestructive tertiary recovery can vary widely. There is significant evidence, however, that more than half the estimated original oil in place (OOIP) remains in the reservoir after all petroleum extraction techniques have been applied. If one compares the sum of past oil production and estimated remaining producible reserves with the API estimate of total discovered OOIP as of 1975, it becomes apparent that for the U.S. as a whole, 67% of the OOIP will remain in place at the end of the

Jan 9, 1980

By Anthony Edey, Leigh A. Readdy, Bruce A. Kennedy

Introduction Very little attention normally is given by the experts, or the public at large, to the fact that the majority of the oil that has been or will be discovered within the U.S. remains in the ground. The inherent limitations of oil production through surface wells, either by primary or secondary techniques, will result in a total of over 300 billion bbl of oil left in the ground after completing production by standard petroleum techniques in currently producing or producible fields. This reserve represents some two-thirds of the original quantity of oil discovered in place. Recent work by a number of groups has shown that there is strong economic justification for extracting this remaining oil by mining and processing techniques. Table 1, taken from 1977 API reports, demonstrates the oil left in place at the end of the conventional petroleum production cycle in then-known fields within th’e U.S. Possible targets for oil mining operations include (1) oil remaining in place in fields and pools that have reached economic depletion by current petroleum production methods and that are not amenable to economic recovery by conventional petroleum industry techniques; (2) oilor bitumen-saturated rocks not normally considered by the industry to constitute producible reservoirs, such as shales and diatomites; and (3) asphalt- and bitumen-impregnated rocks. Economically Depleted Fields A more detailed examination of the depleted fields shows that estimates of oil remaining in place after primary, secondary, and nondestructive tertiary recovery can vary widely. There is significant evidence, however, that more than half the estimated original oil in place (OOIP) remains in the reservoir after all petroleum extraction techniques have been applied. If one compares the sum of past oil production and estimated remaining producible reserves with the API estimate of total discovered OOIP as of 1975, it becomes apparent that for the U.S. as a whole, 67070of the 00IP will remain in place at the end of the

Jan 1, 1980

By B. Geelhoed

Gy's formula for the variance of the fundamental sampling error (FSE) is based on a model that assumes independent selections of particles. A generalization of this model, which can theoretically lead to more realistic representation of actual sampling processes, was, for the first time, experimentally verified by repeated sampling from a well-mixed batch consisting of particles of zirconium silicate of two different sizes. The predictions for the sampling variance made in Gy?s theory and in the more general model were compared with the experimentally observed sampling variance. During the experiment performed here, the variance prediction made in the theory of Gy ranges from 0.96 × 10?7(g2/g2) to 0.95 × 10?7(g2/g2), which is approximately a factor 60 lower than the experimentally observed variance (5.76 × 10?6(g2/g2)). The difference between the Gy prediction and the experimentally observed variance cannot be fully explained by the uncertainty in the experimentally obtained variance due to the finite number of degrees of freedom. Therefore, the difference is likely to be a significant effect. This shows that, under the experimental conditions, Gy?s formula for the variance of the FSE probably undervalues the sampling variance, unless an empirical correction factor for grouping and segregation is applied in the theory of Gy. The new theory resulted in a variance prediction of 6.00 × 10?6(g2/g2), which is much closer to the observed variance than the Gy prediction. This indicates that the generalization of Gy?s theory offers an outlook for providing a better variance prediction than the Gy predictor in the case of dependencies between particle selections. The results are discussed. Keywords: sampling, variance, parameter for the dependent selection of particles, Gy, experiment.

Jan 1, 2009

By L. V. Wade

The use of longwall/shortwall mining systems is under increasing scrutiny by the U. S, coal industry as a means to reverse the decline in productivity. The success of these mining systems depends to a great extent upon designing the system hardware to best suit local conditions. Of particular importance in this regard is designing the various elements of the total ground support system, including face, face end, and gate road supports, to accommodate local geologic conditions. This presentation centers on the problem of selecting the face support system. The existing geologic situation can influence the selection of the face support hardware in a variety' of ways. In general terms, these influences can be grouped into the following four areas: 1. The capacities required of the support unit; 2. The roof, coverage supplied by the support units; 3. The flexibility required of the support unit to meet changing geologic conditions; and 4. The required stiffness characteristics of the individual support units both vertically and horizontally. The following will center on the first area, i.e., the required d capacities of the support unit, in particular, the maximum required load density for a particular geologic situation.

Jan 1, 1976

By A. K. Snelgrove

At a time when water resource planning is proceeding on a continental scale, such as the proposed $100 billion North American Water and Power Alliance, which would redistribute water among three nations, including seven provinces of Canada, 35 of the United States, and three States of Mexico, the selection of a single river basin for study may seem to require an apologia. None is offered because of ( 1) the magnitude of the Indus , itself a part of the great Indo-Gangetic Plain drainage system, with Himalayan sources, upon which the thickly populated northern sub-continent of Indo-Pakistan depends for agriculture and hydroelectic power; (2) the extraordinary problems created by dismemberment of the world?s largest irrigation system through legal beheading of the Eastern Waters under the Indus Waters Treaty of 1960; and (3) the herculean effort to contain the twin encroachments of waterlogging and salinization in a basin which faces a shortage of fresh water. The British irrigation system of barrages and canals on the Indus was a venture admirable in conception. Unfortunately, it is now a legacy burdened with unwanted consequences, due to interference with the hydrological regimen, particularly the rise of water table occasioned by leakage.

Jan 1, 1967

By A. B. Cortes

This research work discusses the development of a two-dimensional model that represents the flow that occurs in the inlet section of hydrocyclones. The governing equations are the two-dimensional, unsteady, incompressible Navier-Stokes equations in cylindrical polar coordinates with primitive variable formulations. In this approach, no assumptions have been made other than independence in the axial direction. The full two-dimensional Navier-Stokes equation in the r-a plane is used. The commonly used simplifying assumption of axisymmetry is not used. A numerical technique based on a newly developed spectral-difference method is used to solve the equations. The spectral-difference method is a multi-domain, and multi-dimensional extension of the Jacobi polynomial collocation technique. The computational grid for the inlet section is composed of 25 sub-domains which result from five partitions in the angular direction and five partitions in the radial direction. Several test cases are used to validate the appropriateness of the numerical model.

Jan 1, 1995

By I. H. Warren, E. Devuyst

A review of the physical and chemical aspects of the direct leaching of metal oxides has been given and com- pared to recent data of the authors and co-workers. The physical aspects, including the anisotropy of the dissolution, the hydration and the zero point of charge of some metal oxides are discussed first and then the kinetics of the dissolution of metal oxides are considered. A general mechanism of the leaching of oxides which describes most of the observed results is proposed.

Jan 1, 1973

By Michel Claisse, R. P. Goel, André J. Rancourt, Kent Murphy

The Malana Hydroelectric Project is a private development located in HimachalPradesh State, India that was commissioned in June 2001. The plant was built and is owned by the Malana Power Company, a subsidiary of the Bhilwara Group of New Delhi. With a total head of 400 m and nominal capacity of 86 MW, the plant is capable of generating 360 GWh annually. The 3,1 km long, 4,0 m diameter power tunnel was designed to be excavated by conventional drill and blast methods. Contrary to traditional practice in India for pressure tunnels of providing a concrete lining, the Malana tunnel was finished mainly with shotcrete. In this way, the tunnel was completed in a period of18 months, a record for recent projects in the Himalayas, and at a cost substantially below that of conventionally lined tunnels. An interesting aspect of the project was the design of the steel tunnel liner linking the power tunnel to the penstock. The length of the liner was fixed finally on the basis of in-situ testing using both hydraulic jacking and doorstopper tests to evaluate the ability of the rock to withstand the internal pressure of4,0 MPa that exist near the downstream end of the tunnel.

Jan 1, 2003

By Millett R

In January 1989, Western Mining Corporation (WMC) acquired the Perseverance and Rocky's Reward orebodies and associated infrastructure from the Agnew Mining Company (AMC). AMC had closed the operation in August 1986 and it had been on care and maintenance since that time. To return the operation to full production as quickly as possible it was planned to mine the Rocky's Reward orebody by opencut mining and treat this ore whilst the underground Perseverance workings were rehabilitated. Removal of overburden from Rocky's Reward thus commenced immediately with a target of April 1989 for delivery of the first ore to the concentrator. Extensive rehabilitation and upgrading of the concentrator commenced in late January, and continued in stages for an 18 month period. The first stage consisted of overhauling all existing equipment and completing a crusher upgrade commenced by AMC prior to the mine closure. During this period, it was necessary to recruit a workforce and re-establish all the required support structure. In late April the plant commenced commissioning trials on mullock. The first ore was crushed on the 11th May 1989 and concentrate produced the following day. From May 1989 to June 1990 the plant was producing nickel concentrate whilst further upgrading continued. During this period, the flotation capacity was tripled by installation of a bank of eight Wemco 144L flotation cells in rougher-scavenger duties and two 12 metre by 2 metre diameter columns in cleaning duties. The existing vacuum drum filters were replaced by two Larox PF32 pressure filters, eliminating the need for solar drying and allowing the flash drier to be fed direct from the filters. These, along with a major borefield expansion and further work to the crusher increased the nominal plant capacity from 600,000 to 1,000,000 t/yr. The plant achieved the 1,000,000 t/yr rate in April 1990.

Jan 1, 1991

By John C. Nigro

Bench scale and pilot plant research was conducted using dolomites (CaO,MgO) lime as the basic additive in the preparation of self-fluxed pellets from a typical magnetic taconite concentrate (5.57 S_2). The specific objective of this investigation was to ascertain the viability of the magnesia lime pellets in high temperature oxidizing and reducing atmospheres. Pellet basicity and induration temperature were major parameters affecting fired pellet quality; temperatures ranging from 1,200° to 1,250" C appeared to be the most favorable for production of self-fluxed pellets with basesities (B) above 1.0. Comparison of the mechani¬cal and metallurgical properties of regular (acid) and self-fluxed pellets (B 1.55) produced under similar conditions in a modified grate pelletizing machine showed that the self-fluxed pellets were more resistant to abrasion and to high and low temperature reduction disintegration, an important consideration in commercial application. The Plus 3 mesh Linder index increased from 68 percent (regular pellets) to over 90 percent (self-fluxed pellets). The reducibility and swelling indices of the self-fluxed pellets were found to be comparable to the regular pellets.

Jan 1, 1972

By M. D. Hassialis

THE claim is made in a number of patents1,2,3,4 that some compounds of the class known as aryl sulphides have collector properties. One of these patents generalizes the claim to include all aryl sulphides, whose generic formula is R-S¬R[=]-R’ (where x = r,2, . . . ), with the restriction that if the aromatic radicals R, R' contain substituent groups these groups may not contain nitrogen or oxygen. Moses, Hess, and Perkins cite as evidence for their claims the results of flotation tests on Anaconda and Miami copper ores using Biphenyl sulphide, ditolyl disulphide and dinapthyl disulphide as collectors. The use of alkyl sulphides as collectors has also been reported5 with the conclusion that the alkyl sulphides are better collectors than the corresponding aryl sulphides. The experimental work cited appears to confirm this contention. In order to test these claims with respect to diphenyl sulphide, a sample, purchased from the Eastman Kodak Co., was tested against Anaconda ore. The procedure followed was that of Moses, Hess, and Perkins. A sample of ore weighing 500 grams was placed in a laboratory ball mill. To this was added 220 grams of water, 0.06 grams of commercial diphenyl sulphide (1/4 lb. per ton of ore), and 0.8 grams of lime (3 lb. per ton of ore). The material was ground until 93 per cent passed a 65mesh screen. This pulp was diluted to 16 per cent solids. A sample of the diluted pulp was placed in a Minerals Separation type of laboratory flotation cell. After a 2-min. agitation period, pine oil was added and the froth collected for a period of 15 min. This test recovered 68 per cent of the copper, with a ratio of concentration of 6.8: 1. The tailing assay was 0.3 per cent Cu. Moses, Hess and Perkins attained a recovery of 75 per cent, with a ratio concentration of 12: 1. Although these results do not compare too well with those of Moses, Hess and Perkins, subsequent tests showed an improvement, as judged by vanning of the tails. It is concluded, therefore, that the patent results are confirmed. CONTACT-ANGLE TESTS In order to study the response of the various minerals, found in Anaconda ore, to commercial diphenyl sulphide, some contact-angle tests were made. Polished particles of bornite, chalcocite, chalcopyrite, pyrite and quartz were conditioned for 15 min. in a suspension of diphenyl sulphide in water. The concentration of this suspension was 0.284 grams per liter, this being the concentration of this reagent in the ball mill. The conditioned particles were rinsed with water (not rubbed with filter paper or boiled linen) and then tested against an air bubble in the bubble machine, with the following results: born-

Jan 1, 1943

By William T. Ingram

Early in the 60's the author served as Chairman of the Engineering Foundation's Coordinating Committee on Air Pollution Research. One of our objectives was the development of a study on the measurement of stack emissions. Three publications of the Foundation resulted from these efforts to focus attention on the stack sampling problem.1,2,3 Two of these were annotated bibliographies covering 197 references. The third reported the results of a workshop meeting at which some 21 individuals from research institutes, industry and government discussed the possible and probable areas of research that would add to or increase the ease, precision and utility of sampling gaseous and particulate matter emitted from stacks. The American Society of Mechanical Engineers has had in its Power Test Codes a Standard Code for Determining the Dust Concentration in a Gas stream4 since 1941, The American Industrial Hygiene Association has published, in its Air Pollution Manual,5 a Section on Stack Sampling. Industry and regulatory agency requirements for stack sampling have utilized some modification of the alternatives in methodology. There has been ho single guide to stack sampling that met the needs of those who have the need to know.

Jan 1, 1970

By D. F. Sinclair

It is often said in business that if you don't have a customer you don't have a business. The same rule applies to project evaluation; if you don't have customers you really don't have a viable project. It is therefore essential that in the early stages of project evaluation the following fundamental questions are addressed: ? What products will this project produce? ? Who are the potential customers? ? What are the customers' requirements with respect to grade and impurities? ? Do they have adequate capacity to take the production from the proposed project? ? Will the products introduce adverse effects in the customer's process circuits? ? Will additional waste streams requiring disposal be produced? In the past the attitude has been along the lines of the customer will take whatever we produce at the mine site. Times have now changed with customers now operating under much tighter environmental regulation with waste disposal becoming increasingly difficult. It would therefore be prudent that the principles of product stewardship be used as a tool in project evaluation. This paper will provide a general discussion on customer requirements and provide detail on case studies of the impact of mine products on smelter process circuits. It will provide examples where there were synergies between the mine product and the smelter circuit and where the mine product had adverse impacts on smelter performance.

Jan 1, 2007

By Gustavo Elói de Sá Lima

A estratégia de manutenção de locomotivas da VLI sofreu significativa modificação após a implementação de propostas de consultores americanos, baseadas principalmente, na execução de atividades fora de oficina, realizadas em estruturas chamadas de “Track Service”, estruturas as quais contam basicamente com uma vala para inspeção na parte inferior das locomotivas. Dessa forma, foi possível capturar diversos ganhos em custeio e redução de investimentos, como por exemplo o aumento de periodicidade entre manutenções preventivas e redução do projeto da nova oficina de Paulínia.

Oct 30, 2017