Search Documents

By V. Damiano, M. Herman

CELLULAR substructure observed in metal crystals grown from the melt. has been studied extensively'-' and is attributed to the existence of a constitutionally supercooled zone in the liquid ahead of the solidifying interface. The mathematical description of this process has been given in terms of the concentration of solute in the liquid phase, the rate of solidification, and the temperature gradien.t in the liquid as the only variables.5 This technical note presents some evidence of 1) the effect of crystal orientation on some aspects of cellular growth, and 2:) the degeneracy of these cells into dislocation arrays. The zinc single crystals used in these studies were alloyed with cadmium sufficient to produce the constitutional supercooled cellular substructure. Crystals containing 0.05 pct Cd exhibited substructure formation for a growth rate of 10 cm per hr and a temperature gradient of 15°C per cm in accord with the theory. The growing liquid-solid interface was examined after we liquid had been decanted away in a fashion similar to that described by Rutter and Chamers.' The cellular substructure was also observed after polishing and etching the surface directly behind the decanted interface with a solution of HNO, and water. Fig. 1 is a photomicrograph of a typical polished and etched surface revealing substructure, the cleavage plane, and twins. The crystal has been grown with its basal plane parallel to the direction of growth and the plane of the micrograph is per-

Jan 1, 1960

Phase II of President Nixon's economic game plan will incorporate many top flight metals mining companies. The large corporations must receive approval from the Cost of Living Council before increasing prices and or wages. The theory here is that, with large companies complying with advance approval, smaller firms will be examined more closely by government, and thus will be forced also to comply. Rep. Paul McCloskey (R.-Calif.) called for a moratorium on strip mining for "the few years involved before we adopt a national energy policy and a national land use policy." McCloskey, who is a cosponsor of Congressional legislation that would outlaw strip mining, told a hearing that a "moratorium can scarcely hurt us until national energy and land use policies are adopted."

Jan 1, 1971

By R. J. Young, S. J. Tennant, A. D. Drummond

"Gibraltar Mines is located on the western slope of Granite Mountain, 230 air miles north of Vancouver, B.C. and 38 miles north of Williams Lake, B.C. There are four mineable zones within the copper-molybdenite deposit: Gibraltar East, Gibraltar West, Pollyanna and Granite Lake. Open-pit reserves are 358 million tons which average 0.37% Cu and 0.016% MoS2 at a 0.25% Cu cut-off. The Granite Mountain pluton is one of the several Jurassic-Cretaceous intrusions which outcrop along the east side of the Fraser River fault system between Williams Lake and Prince George, B.C. The original Granite Mountain quartz diorite has been metamorphosed by a cataclastic deformation which foliated the rock on a regional scale. Attendant to the development of the foliation, the rock was saussuritized such that the present mineralogy is compatible with that of the greenschist facies. The presence of garnet-bearing assemblages is explained by a restricted increase in water pressure. Pre-mineral intrusive phases within the saussuritized quartz diorite are: (1) leucocratic quartz diorite, (2) aplite and (3) quartz-feldspar porphyry. A late chloritized hornblende dacite dyke is post-mineral. Quartz-feldspar porphyry and leucocratic quartz diorite are locally present on the inner sides of the Gibraltar East, Pollyanna and Granite Lake pits. Their presence suggests a core around which occurs an elliptically shaped sulphide-bearing stockwork. The stockwork, which comprises four ages of vein development, is imposed on and partly controlled by the regional foliation of the samssuritized quartz diorite."

Jan 1, 1973

By Kari Moen, John Rasmus Leinum, Jarle Hjelen, Terje Malvik

"Industrial minerals may contain the same elements in approximately the same amount. In these cases backscatter electron imaging or chemical analysis are not sufficient to identify the minerals. Another problem arises when micro textures are not detectable in traditional imaging or the grain size is smaller than the X-ray spatial resolution.As a supplementary technique in these cases, application of crystallographic information by electron backscatter diffraction (EBSD) in the scanning electron microscope (SEM) may be a suitable method. The technique has been demonstrated on three Norwegian mineral raw materials and one Italian marble and shows that it has some advantages compared to traditional techniques.• quantitative measurements by ebsdCommon automatic techniques describing the mineral contents and the occurrence of minerals in free and locked particles, are based on optical-, backscattered electron (BSE)- or X-ray-signals. There are various commercial software systems on feature analysis by backscattered and X-ray signals in combination with image analysis (e.g. Oxford Inca Feature, CSIRO QemScan).Especially in silicates, the occurrence of similar elements in the different minerals is common. Sometimes the various minerals not only contain the same elements, but also approximately the same amount of each element. In these cases BSE imaging and chemical analysis are not always sufficient for identification."

Jan 1, 2003

By George A. Morgan

The 53 countries that constituted Africa in 1990 accounted for a significant portion of total world output of a number of mineral commodities. Among the most significant to be produced in Africa were andalusite, antimony, asbestos, bauxite, chromite, coal, cobalt, copper, diamond, fluorspar, gold, lithium minerals, manganese, phosphate, platinum-group metals, the titanium minerals-ilmenite and rutile, vanadium, vermiculite, uranium, and zircon. Several of these, chromite, cobalt, diamond, and manganese, were not produced in the United States. Despite the underdevelopment of much of Africa, mineral raw materials playa very important part in the national economies of many of its countries. In many cases, the production of minerals is the dominant economic activity in the country, often having the largest and most sophisticated work force. In several countries, one or two mineral commodities are dominant in a weakly diversified economy. Among these are petroleum and diamonds in Angola, petroleum in the Congo, gold in Ghana, bauxite in Guinea, uranium in Niger, phosphate in Senegal and Togo, and copper and cobalt in Zaire and Zambia.

Jan 1, 1992

By Eugene Barsky

"At present, theoretical concepts of gravitational separation processes are mainly limited by the study of the interaction between a flow and a solitary particle. Then the main conclusions of this analysis are applied to a mass process. However, this analysis is absolutely insufficient, because some elementary phenomena such as the ingress of coarse particles into the fine product output and vice versa cannot be interpreted from its standpoint. It is also impossible to predict the results of the classification of a material with a specific granulometric composition on a specific apparatus on its basis.In the present paper, an extended model of the process is suggested. The model is based on the behavior of all the particles of a specific narrow size class, and not on that of an individual particle. Similarity criteria of the process, which were empirically derived previously, are obtained from the analysis of this model.INTRODUCTIONIn case of gravitational separation, a part of solid phase moves, as a rule, vertically upwards with the flow, while another part settles against the flow. This flow is extremely complicated and chaotic due to various random factors. Among these factors are mass interactions of particles with each other and with the apparatus walls, non-uniform character of concentration and velocity fields, turbulent vortices and local fluctuations, real particles shape difference from spherical one, etc.Particles rotation results in a transverse force (Magnus' effect). At the motion of a non-rotating particle in a non-uniform velocity field, a transverse force also arises (Saffman's effect).A great number of publications have been devoted to the account for all these factors in two-phase flows in recent decades. Very complicated models have been developed, but the problem has not been completely solved as yet [1, 3].At the same time, simplified models of the behavior of a solitary particle in a flow are being developed. Despite their schematic nature, such models often prove to be useful for establishing general laws of the process and its similarity criteria [1]."

Jan 1, 2016

By M. J. Pool, R. K. Saxer, J. R. Myers, D. S. Dickson

ThE equilibrium phase diagram of the Mo-Cr system, described by anssen,' indicates that chromium and molybdenum form a continuous series of solid solutions above 1673K. The liquidus and solidus have been reported to have a minimum at about 12 at. pct Mo and 2133°K by Bloom and Grant2 and by Putnam, Potter, and Grant.3 X-ray studies by Trzebiatowski and ploszek4 and Baen and Duwez' revealed no indication of solid solution decomposition after long anneals at 1473", 1273", 923", and 873°K. However, Bloom and rant' by means of cooling and heating curve analysis of alloys containing up to 45 at. pct Mo found thermal effects at temperatures approximately 100" * 30°K below the liquidus. The only previous thermodynamic study of the Cr-Mo alloy system was made by Laffitte and Kuba-schewski6 who used the Knudsen effusion method at 1471°K. These investigators reported the possibility of a miscibility gap because they observed positive deviations from ideality in their chemical activity

Jan 1, 1970

By Heikki Jalkanen

The mineralogical composition and morphology of solidified copper smelting and converting slags are of some interest from slag cleaning (by froth flotation), impurity elimination, and environmental points of view. Properties result from both the state of molten slag before solidification and processes taking place during solidification and cooling. In solidification and cooling, copper and sulfur dissolved in molten slag are .precipitating substantially from the silicate phase. Even in water quenching of slag, dissolved copper is pushed out of the solution in the form of finely divided precipitate. Elements present in the raw materials are distributed in a distinct manner between the solidified slag and non-silicate solidification products. Arsenic, antimony, and tin are strongly accumulated in copper precipitate, but not the other metallic constituents common in copper concentrates. Smelting and converting slags differ remarkably on their mineralogical composition and morphology although resulting principally of same chemical processes. Converter slags are more inhomogenous; they often contain solid particles and copper content is .as a rule higher than in matte smelting slags. The final copper content of converter slags was observed to be in a distinct manner dependent on iron oxide - silica ratio. Slag forming, solidification, and precipitation phenomena are discussed on the basis of mineralogical and morphology analysis of smelter slags and laboratory scale experiments.

Jan 1, 2002

By William Butler

El presente texto describe las oportunidades que tienen las naciones menos desarrolladas para un progreso en el campo de los recursos naturales. Para ello, se revisan los inconvenientes ocurridos en el manejo de recursos minerales tales como: los mercados mundiales tienen un sobreabastecimiento que son pocas las probabilidades de ingresos por exportación, la inestabilidad de los precios no permite basar la economía de la nación sobre su riqueza minera, la explotación de los recursos, reduce la riqueza de la nación, los beneficios que puedan obtenerse como resultado de una mayor eficiencia en la producción minera en los países menos desarrollados, se vuelca a favor de las zonas industriales. Por lo tanto, no hay mayor esperanza para aquellos países en propender a una mejor explotación de los minerales. En ese sentido, aquellas naciones que buscan un rápido desarrollo económico, deben buscar un manejo adecuado de sus recursos y así asegurar una fuente de ingresos en divisas extranjeras que les permitirá financiar las importaciones necesarias para su crecimiento y, a la vez, acrecentar sus conocimientos técnicos, como el bienestar de un sector importante de su población.

Jan 1, 1966

By S. Hearn, S. Boskovic, A. Smethurst

"The digestion of minerals in strong acids or at elevated temperatures can result in the release of large amounts of silicic acid which can polymerize in solution to form colloidal silica and gels. Colloidal silica can cause a number of problems including interfering with flocculation, initiating crud formation in solvent extraction (SX), decreasing SX extraction kinetics and increasing SX phase disengagement times. Huntsman’s POLYSIL® polyether coagulants have a “lock and key” relationship with the surface of colloidal silica to help lower the concentration of these particles in solution, improve process efficiency and reduce reagent losses by minimizing crud formation. This paper investigates some of the issues caused by colloidal silica in hydrometallurgy processes and illustrates how the use of POLYSIL® coagulants has helped to improve process outcomes. INTRODUCTION Coagulation differs from flocculation in a number of ways. Coagulants are relatively small molecules that modify the surfaces of fine particles, weakening repulsive forces between them and allowing particles to stick together, while flocculants are generally molecules that are large enough to bridge the boundary layers between the particles. With flocculation, addition rate and mixing all make a difference to the flocs formed. Coagulation, on the other hand, is an equilibrium process. With coagulation it is only necessary to achieve good mixing, and coagulates will form as Brownian motion pushes the particles into each other. In real systems, this process is complete within seconds. Huntsman’s POLYSIL® polyether based coagulants have a strong affinity with the surface of colloidal silica formed by the polymerization of silicic acid. While silica found in minerals has a low aqueous solubility, large amounts of silica as silicic acid can be released as these minerals are digested in strong acids at elevated temperatures. The solubility of free silicic acid is about 150 ppm under pH conditions typical in acid leach environments (1), so the bulk of the silica will polymerize in solution to form colloidal silica. Colloidal silica can pass through a hydrometallurgy process without affecting any of the operations. However, it can cause a number of problems. These include gelling in a leach, interfering with flocculation or crystallization, initiating crud formation (2,3,4), decreasing extraction kinetics and increasing phase disengagement times (5,6) in solvent extraction. In these cases, coagulating the silica with POLYSIL® coagulants can reduce or eliminate the problem by enabling these particles to be flocculated and removed from the solution."

Jan 1, 2015

By Wang Ding-heng, Wang Zhi-yuan, Nolan B. Aughenbaugh

The People's Republic of China has abundant coal resources with proven reserves amounting to 582 Gt (641 billion st). Recognizing coal as a major energy source on which to build the country's industrial and economic base, there has been a rapid increase in production since the founding of the People's Republic. In 1949, only 29.4 Mt (32.4 million st) of coal was mined. Production has increased to 576.5 Mt (635.5 million st), exclusive of Taiwan, at present, making China the third largest coal producing country in the world. Plans call for a 4-5% increase in annual production for the next 20 years. Coal constitutes 70% of the primary energy consumption in China. The remaining 30% is divided between petroleum and natural gas with 26% and hydropower with 4%. Coal use and consumption is divided as follows. General industrial use comprised 48.9%, power generation uses 20.1%, and coking accounts for 10.5% (6.3% for metallurgy and 4.2% for chemical industry). Domestic use such as home heating and cooking makes up 17.8% and coal-fired steam engines for railways uses 4.7%. Coal Districts Coal underlies about 1/18 of China's land area. It occurs in 30 provinces, autonomous regions, and municipalities. In addition, the western interior region, which has not been explored, may contain sizable reserves. Based on geology, geography, and administration, the coal fields can be grouped into five districts as shown in Fig. 1. The north China district, the heart of the industrial base for the country, has the most extensive and largest deposits of the five districts. This amounts to almost 40% of the country's total reserves. The largest coal basin with proven reserves of 181.4 Gt (200 billion st) and the most exploitable seams is located some 300 km (186 miles) southwest of Beijing (Peking) in Shanxi Province. Centered around Taiyuan, the compound field extends from Datong in the north to Xian in the south. Its western extension is not known fully. The Northwest and Northeast districts contain the second and third largest deposits. The biggest coal field in South China is located in the Sichuan and Guizhou Provinces near Chongqing. At present, it is not known if sizable coal measures exist in the Tibetan district. Coal Types China's coal varies widely both in age and rank. Geologically, coal measures were deposited from the lower Carboniferous (Pennsylvanian of the US) and Permian of late Paleozoic, mainly during the Jurassic of the Mesozoic and peri¬odically throughout the Cenozoic. Collectively, coal from the lower Carboniferous, Permian, and Ju-

Jan 3, 1983

By Leonilson Toffoli Pedrini

A corrosão ocorre devido à deterioração de um material pela ação química ou eletroquímica em meio corrosivo, sujeito ou não a esforços mecânicos, causando modificações indesejáveis, tais como perda de massa, alterações estruturais e variações químicas. O aço inoxidável austenítico AISI 304L é utilizado em grande escala pelas indústrias por apresentar baixo custo e boa resistência à corrosão decorrente da camada de passivação. A passividade dos aços inoxidáveis em eletrólito com íons de cloreto é destruída em pontos ou áreas localizadas. Neste trabalho foi analisado, por meio de ensaios eletroquímicos, a resistência à corrosão do aço AISI 304L. Foi utilizada gaiola catódica em chapa de aço inoxidável 316, com dimensões de 0,8 mm de espessura, 112 mm de diâmetro, furos de diâmetro de 25 mm de altura e 8 mm uniformemente distribuída, com um distância de 9,2 mm entre furos. Os tratamentos térmicos foram realizados a 700, 800 e 900ºC, respectivamente. Os resultados indicam que a resistência à corrosão das amostras tratadas diminuiu, devido a precipitação de nitretos quando são submetidas a processos em altas temperaturas.

Aug 16, 2017

By T McConachy

New opportunities for miners are beginning to appear through new discoveries, improved knowledge and access to vast unexplored areas of the deep sea and continental shelf. Recent discoveries of undersea hydrothermal deposits show evidence of high-grade mineralisation, although in many instances the extent of the resource is still unknown. The promise and the difficulties of undersea mining have been evident since attempts were first made to mine manganese nodules in the 1960s. The physical nature of the undersea resource is a key influence on its mining potential; and environmental issues will also become increasingly important. This paper explores these issues and concludes with a description of the immediate to medium term applied research required to develop this industry and the spin off that such research can provide.

Jan 1, 2000

By M. Rahman, P. C. Kapur

The fixed-time locked-cycle grinding test is employed to simulate the industrial closed grinding circuit on the laboratory scale. A mathematical algorithm for 'cyclewise' computer simulation of the locked-cycle test has been derived and used to study an idealised laboratory-scale model of a closed ball-mill circuit. The agreement between simulated and experimental results is reasonably good, except when the grinding times are relatively long

Dec 1, 1971

By James M. Link

The design and construction of cross-country pipelines for fluids such as crude oil appears relatively simple compared to the complex problems encountered in slurry systems. Considerable effort has been expended in hydraulic research laboratories in an attempt to improve the understanding of slurry behavior. This effort has been rewarded with considerable success and is best illustrated by the large number of slurry systems now planned or under construction. However, slurry transport in pipelines is still, in many instances, more of an art than a science. In order to minimize the risk factors in the construction and operation of large scale slurry systems, studies are frequently conducted in pilot scale test loops such as the one at the Colorado School of Mines Research Institute. The pilot scale projects are designed to provide the basic engineering data necessary to design slurry transport pipeline systems. Usually three slurry solid concentrations are pumped at various line velocities and optimum slurry densities and velocities are determined. Critical velocities, friction head losses, power requirements, and so forth, are also determined from measurements and calculations. Wear tests are also strongly recommended and anticipated pipe wear rates in inches per million tons of solids reported.

Jan 11, 1972

By R Valenta, J Owen, D Kemp, E Lebre, G Corder, J Thomas

Numerous recent analyses have shown that future demand for a broad range of critical commodities is unlikely to be met by new discoveries and recycling alone. The only practical alternative source to address this shortfall comes from orebodies which are currently either uneconomic or inaccessible. A common assumption is that a simple rise in commodity price will render these deposits economic. The mining industry has a long history of innovation allowing economic production from increasingly low grade and technically challenging orebodies. Industry “roadmaps” have been produced on a regular basis, with the aim of identifying future innovations which will allow this progression to continue. At the same time, there have been relatively few systematic analyses of the actual range of challenges facing undeveloped orebodies. The aim of this study is to analyse the mix of challenges faced by a group of undeveloped orebodies in order to better understand the relative importance and necessity of innovations applicable to the deposits, with the ultimate aim of determining the relative value and impact of possible innovations to the economic viability of those deposits. CITATION: Valenta, R, Lebre, E, Kemp, D, Owen, J, Corder, G and Thomas, J, 2018. Can a simple price-rise unlock complex copper orebodies?, in Proceedings Complex Orebodies Conference 2018, pp 71–72 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By J. Arce

Recientemente algunos mineros han empleado métodos instrumentales de operación del subsuelo. Sin embargo, dado el paso del tiempo, las técnicas varían en efectividad, por lo que se hace necesario estar a la vanguardia de los nuevos instrumentos de exploración. En ese sentido, el presente trabajo analiza algunos estudios geofísicos en el pasado, así como sus posibilidades de uso en el Perú. Asimismo se anota lque os métodos de polarización inducida para exploración terrestre prfurida; los de activación neutrónica y fluorescencia de rayos para análisis químico en campo y los de análisis de gas de mercurio para campo y laboratorio, son los métodos que deberán utilizarse en el futuro cercano, así como algunas técnicas de sensores remotos serán especialmente útiles para evaluaciones regionales o continentales.

Nov 20, 1972

By G. S. Rice

IT is evident from Professor Louis' remarks that he holds a different opinion on certain phenomena connected with a specific type of surface subsidence from mining than is held by many engineers in the United States. The question which appears to be at issue is whether or not the line or plane of "draw" produced in ground movement resulting from extraction of pillars may, under certain conditions, be vertical or even inclined toward the workings rather than inclined for- ward over the unworked mineral, as it is universally agreed occurs in mining by the longwall advancing method. In discussing this case it is well to take the simplest condition, such as specified by Professor Louis, of a flat bed, whether it be coal, iron or other mineral, where the overburden is stratified rock and where there is no overlying quicksand. Professor Louis says in effect that his experience is that the ultimate angle of draw is always positive and inclined 5" to 15" from the perpendicular over the unwrought mineral. My experience under Illinois coal-mining conditions is that .'where longwall advancing is used the draw is always positive as Professor Louis describes it, but that in extracting of panels by withdrawal of pillars, the ground movement is manifested, after the first roof' beam break, by the forming of an unstable dome over the goave. Then subsequently, by the falling of individual slabs from the under side, the dome gets larger and higher until it breaks through to the surface of the rock., Up to this time, arch stresses buttress the rocks above the solid coal or mineral. When, however, after. the dome breaks through and the central hole - #enlarges so the arch is no longer sufficiently supported -the stratified rocks cantilever out .from over the solid unworked mineral and tend to break off in masses triangular in vertical cross-section, until the broken loose material, sliding down against the solid rock, .has such a thrust that it balances the tendency ,for the solid stratified rock to break away and slide toward the excavation.

Jan 1, 1929

By Oscar Damiani

El presente texto señala la distribución general de las brechas encontradas en el depósito de Toquepala, especialmente la distribución de la brecha de colapso, a través de ciertas orientaciones. Esta distribución incompatible con el origen diatrémico propuesto anteriormente, sugiere la posibilidad de establecer preliminarmente que el depósito ha sido originado por el fenómeno conocido como «magmatic stopping» emplazado en un área de debilitamiento ocasionado por la intersección de varias fallas pre - existentes, generando de este modo el «breccia pipe».

Sep 1, 1968

By Aner W. Erickson

Magnetite iron deposits on Tolstoi Mountain were examined as part of the investigations by the Bureau of Mines of iron and copper ores on Prince of Wales Island. The Tolstoi Mountain project was a part of a program for investigating mineral deposits in Alaska, under the general supervision of R. S. Sanford, acting branch chief.

Jan 1, 1948