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By W. J. Rooney, James Fisher, W. O. Hotchkiss

During the summer of 1927, the Department of Terrestrial Magnetism of the Carnegie Institution of Washington joined with the Michigan College of Mining and Technology in conducting a series of earth-resistivity measurements in the Michigan copper country. The geological structure in this section is quite varied and fairly well known. The purpose of the investigation was to discover the correlation between the variations in electrical resistivity of large masses of soil and rock in place and the geological structure below the surface. The work done may be roughly divided into two parts: (1) Measurement and study of the variations in resistivity with depth, or with volume, to establish such general relations as exist between the two; and (2) the determination of the specific resistivity of various formations in order to make available more fundamental data which may aid in the interpretation of the results of the former type of measurement. A report by Mr. Rooney, which gives in detail the measurements made and the results obtained, forms the basis for this article. Measurement and Study of Variations in Resistivity The possibility of applying data from measurements of the physical properties of earth material to the study of the geological structure has long been recognized, and a number of methods for determining the position and character of concealed rock strata by means of seismic, gravitation, magnetic and electrical measurements made on the surface are being used with varying degrees of success. One physical property which varies widely for different materials, and hence affords an opportunity for distinguishing between them, is their electrical resistance. Locations • were selected where the geological structures were well known and where the depths to the water level and bed rock had been determined by drilling. The problem was to determine the value of measurements of resistivity and its variations as indications of the geological structure below the surface.

Jan 1, 1929

By Erick F. Weiland, John W. Lindemann

Introduction Minerals exploration is one step in the mining industry's task of providing raw materials to basic industries. The industry's provision of raw materials involves identifying and evaluating resources, converting them to reserves, and intelligent, economic exploitation of these reserves. The mineral process focuses on identification and evaluation. Reserves are ore bodies and ore bodies are, by definition, wasting assets. Therefore, if an adequate provision of raw materials to basic industry is to continue, these wasting assets (ore bodies) must be replaced with new or different reserves as current reserves are depleted. Minerals exploration is a geologic problem and is fundamentally deductive, flowing from the general to the specific. Past exploration methods and philosophy have amply supplied the resources to meet the demands of an industrial society. During the past decade, however, the framework where mineral resources were identified, defined, and evaluated has changed. Mineral explorationists no longer can rely solely on the successful past methods to provide the necessary resources for our complex society. Productive explorationists must effectively and efficiently use tools and procedures that will maximize exploration efforts. Past tools need not be abandoned, but should be critically reviewed and revised in light of current scientific knowledge and technical advances. Future explorationists will view their craft not as a single discipline, but as a thoughtful integration of geophysics, geochemistry, and geostatistics for solving interrelated problems. This integration of the geosciences will lead to successful mineral exploration. Not only will the productive explorationist generate new information, he will master the use of existing data for identifying and evaluating a mineral resource. The mineral exploration process consists of incentives, ideas, finance, area, staff, time, and luck. The exploration process that stems from the interaction of these elements has three stages, each bound by a major decision point. They are selection, reconnaissance, and definition. Subsequent evaluation and exploitation phases are considered more the function of mining engineers than the exploration geologist. Mineral exploration endeavors that have been productive have three attributes fundamental to success: commitment, competence, and persistence. Commitment Commitment is believing that exploring for mineral resources is worth performing. While the mining industry is the focus of this commitment, government and society must also be committed to the concept of mineral reserve identification through exploration activity. Government demonstrates its commitment by providing access to land for exploration and, if it is successful, exploitation can take place. Realistic legislation relating to taxation, land use, reclamation, and environmental constraints is indicative of government commitment to intelligent resource use. The public must come to terms with mineral resource evaluation and extraction. Without some form of commitment from the public, availability of mineral resources vital to basic industry will be largely in the control of a foreign and potentially unstable mining industry. Commitment to a mineral resource identification-evaluation-extraction system must be shared equally by government, society, and the minerals industry. The scope and direction of this commitment varies, with the industry's commitment to explore for mineral resources being the most apparent. Industry commitment is the belief at all levels of exploration (from senior corporate executives to individual field and support staff) that exploration is worth performing, that exploration goals can be met, and that their particular organization is the best and the only group that can successfully accomplish the project. Commitment can be considered at three

Jan 11, 1983

By H. C. van Elst

Ultrahigh-speedphotographic and electronic meth-ods were applied to an investigation of details of brittle-fracture propagation in steel. The brittle fractures studied were obtained in steel plate with the aid of a Robertson apparatus. It was found that a brittle fracture proceeds by discrete steps ranging from 30 mm near the stop temperature to less than 2 mm at lower temperatures. The halting FROM prior metallographic observations of brittle fracture in steel' it could be concluded that the distribution of mechanical twins along a brittle fracture was similar to the distribution of mechanical twins induced by explosive deformation. It was therefore assumed that a running brittle fracture created stress waves, cf. Refs. 2-7. An emission of stress waves by a brittle fracture, however, seems only conceivable if the fracture propagates by discrete steps. For this reason a study of the details of times between successive steps drop in this tem-perature region from 20 usec to about 1 psec. The stepwise propagation mechanism is accompanied by an intermittent emission of stress waves of the order of 100 to 200 kg per sq mm. These stress waves seen1 to play an important role in the mechanism of brittle fracture as will be discussed. brittle-fracture propagation was undertaken to investigate the possible determination of the fracture steps and the emitted stress waves associated with the assumed mechanism. The more practical object of this work is the development of a test method for the determination of the ductile-brittle transition in small specimens. This has special advantages for the study of irradiation damage in steel. In this test method, which will be published in a following paper, the stress waves emitted by an actual brittle fracture are reproduced with explosive or electrical means and are then transmitted through small specimens at various temperatures. In the present paper only the results of the brittle-fracture study will be reported.

Jan 1, 1964

By N. Nemeth, L. L. Sirois

The role of the filter medium in continuous-vacuum filtration and the special circumstances which influence the resistance to flow through the porous cake and filter cloth are discussed. Due to negative pressure differential, gas bubbles evolve in the slurry, constrict passages in the filter cake and medium, and further restrict flow through the tortuous channels. Filtration is a liquid-solid separation process taking place at a porous medium under a pressure differential. The liquid passes through the medium; the solids are retained on the medium as a partially dewatered cake. Filtration is far from a simple process and has been described in terms ranging from "complex" to "subtle." Because of the many variables involved, no unified filtration theory has been developed, and the filtration process is still considered very much an art. In industrial filter design, basic relationships, whether derived for idealized conditions or developed empirically, are usually adapted to suit local conditions. In the mining industry where continuous-vacuum filtration is the main dewatering process, the physical state of the concentrates and the relatively low pressure differentials permit the assumption that the cakes are noncompressible, an assumption which leads to the use of theoretically sound rate equations. Notwithstanding this simplification, there are other problems, unique in the application of vacuum to dewatering, and until now completely ignored, which demand special attention. The basics of filtration involve the capture of solids on, while permitting the flow of liquid through, a porous layer of cake and cloth. Flow is determined by the structure of the solids which make up the cake and the particles permanently attached to the cloth. The problem of this structure, essentially one of solid geometry, has been considered insoluble by Hatscheckl as early as 1907 and by Freshwater as recently as 1967. Since cake structure is determined by the slurry parameters, that problem is far too large for inclusion in this study. For theoretical considerations, uniform buildup of the filter cake must be assumed; and for efficient practical operation, the resistance of the medium must be kept constant over long periods. The latter can be achieved by careful selection of the filter cloth, since the greatest part of the total filtration resistance will develop at the cake-cloth contact. This paper discusses the role of the filter medium in continuous vacuum filtration and the special circumstances which influence the resistance to flow through the porous cake and the filter cloth.

Jan 1, 1971

By Jaime Fernández Conca

"El siguiente estudio señala la ubicación, fisiografia, depósito, importancia y cubicación del fierro producido en la mina del cerro Casca, situada en el distrito de Mollendo, provincia de Islay, departamento de Arequipa. Según el estudio microscópico del mineral, los depósitos de fierro del cerro Tarpuy y del cerro Miramar se dividen en dos partes: la primera se inicia en la parte baja y mediana de cerro Tarpuy, donde la mena está constituída solamente por hematita, y la segunda, se encuentra en la parte alta del cerro, formando la magnetita y hematita. Asimismo, la cubicación aproximada del fierro, señala que la zona mineralizada tiene una forma piramidal y la base, una longitud aproximada de 120 m, con un ancho medio de 80 m.; la altura de la mineralización será aproximadamente de 60 m. Estas dimensiones darían 288,000 m3 y aproximadamente 1,000,000 de toneladas de mineral. En el aspecto económico, dado que su ley en sílice es muy alta y no permite una fundición en alto horno, el yacimiento minero no tiene por el momento valor comercial como mineral de exportación. Por ello, sería conveniente la aplicación de un tratamiento de concentración por gravedad o por el campo magnético."

Jul 20, 1956

By D. Montagna

This Bureau of Mines report describes a salt-free, fluxless method for reclaiming metallic aluminum from aluminum dross. The dross is smelted under argon, nitrogen, or carbon dioxide, instead of a salt flux, in an externally heated pot furnace. Aluminum recovery, using argon, is equal to recoveries reported from commercial smelters that process dross in rotary-type furnaces This salt-free method could offer a reduction in air pollution, lower energy requirements by elimination of salts, and the production of up to 60 percent less solid waste for disposal than the salt method.

Jan 1, 1978

By H. Jung, J. Kim, Y. Lee, Y. Seo

"Shale gas has become an increasingly important source of natural gas supply in North America and around the world. Horizontal drilling and multi-stage hydraulic fracturing are the two key enabling technologies for the economic development of these shale gas reservoirs. It is believed that gas in shale reservoirs is mainly composed of free gas within fractures and pores and adsorbed gas in organic matter (kerogen). It is generally assumed in the literature that the monolayer Langmuir isotherm describes gas adsorption behavior in shale gas reservoirs. In this work, we have analyzed several experimental measurements of methane adsorption from the Horn River Shale core samples that obey the Langmuir isotherm. INTRODUCTION In nature, gas shales are characterized by extremely small grain size, extremely low permeability on the order of nano-Darcy (10-6 md), small porosity, and high total organic carbon (TOC). Shale can serve as both source and reservoir rock. The amount of gas in place in shale is strongly affected by the TOC, clays, and the adsorption ability of methane on the internal surface of solid (Martin et al., 2010). Since a considerable amount of gas in shale reservoirs is adsorbed, investigation of gas adsorption can provide critical insights into evaluation of well performance and reservoir characterization. Generally, natural gas in shale reservoirs is stored as free gas in both larger mineral pores and natural fractures, as well as adsorbed gas within organic matter (Leahy-Dios et al., 2011). EXPERIMENT METHOD & THEORY Adsorption Experiment Several experiments were carried out on 9 shale core samples obtained in a vertical well drilled within Horn River basin (Figure 1). The CH4 adsorption isotherms were measured for the different depth. In order to measure the amount of adsorbed gas, the high pressure Belsorp-HP equipment applying volumetric method was used. The temperature was kept at 298 K and pressure was increased up to 18 MPa. Approximately 5 g of crushed sample was used for each measurement."

Jan 1, 2016

By David Schlain

"IntroductionThe purpose of this investigation was to study the characteristics of the high-acid electrolytic manganese cell with the idea of fitting it into one of the flow sheets being worked out by the Metallurgical Division of the Bureau of Mines for the recovery of manganese from low-grade domestic ores.In construction, the high-acid cell 3/ differs from the low-acid type in that the cathode and anode compartments are separated by a diaphragm of relatively low porosity, such as alundum. This is necessary because in the high-acid cell the two electrolytes are circulated separately. The anolyte is 15 to 30 percent H2SO4. The catholyte consists of a solution of ammonium sulfate and manganese sulfate with a OH of 4 to 3. The only mixing of electrolytes is that resulting from flow through the diaphragms. In the low-acid cell the two electrolytes are not circulated separately and do not differ so widely in hydrogen-ion concentration. Hence, the canvas diaphragm is sufficient.During operation of the cell, manganese is deposited on the cathode, and sulfuric acid is produced in the anode compartments. Various other reactions take place in the cell. There is considerable decomposition of water; hydrogen is evolved at the cathode, and oxygen is liberated at the anode. When lead anodes are used, some hydrated oxides of manganese are formed at the anodes. The quantity of oxides formed is not as great as it is in the low-acid cell, because fewer Mn++ reach the vicinity of the anodes."

Jul 1, 1942

By H. Alzraiee

Traditional planning methods such as CPM and PERT have been useful tools to manage construction projects. However, the underlying model of these traditional methods often seems to fail to represent real projects as they tend to assume no interrelationship between project components. In reality, project components have complex dynamic feedback process that requires modeling of inherent uncertainty in the execution of these projects. Nevertheless, this dynamic nature and uncertainty have not been explicitly addressed by traditional planning methods. Project failure can be attributed to poor representation of the inner and outer aspects of operations that are responsible for project dynamics. Uncontrollable external forces are often cited but the real cause may be internal such as the feedback process among components of the project. An alternative perspective is offered in this paper through system dynamics (SD) that accounts for the feedback process and discrete event simulation (DES) for modeling the uncertainty. The proposed method utilizes SD method for modeling project dynamics and DES method coupled with CPM network for operational details and uncertainty, respectively. A case study that involves preparing engineering drawings in a design office is used to demonstrate the use of the developed method and to highlight its capabilities. Modeling the dynamic dimension is expected to enhance planning and scheduling of construction operations and to provide a better understanding of the impact of various internal and external factors on project schedule and productivity performance.

Aug 1, 2013

By M. King Hubbert

THE theme of this paper is that one of the greatest retarding factors in progress of geologic science is the inadequate training given to students of geology in schools and universities. Students of geology are still taught as though geology were an independent, sovereign domain of science. Consequently, only in exceptional cases do geology students acquire more than the most elementary introductory college courses in mathematics, physics and chemistry, and frequently not even so much. Furthermore, students with such training receive Ph. D. degrees in geology, and often they become professors of geology in our universities. The phenomena of geology are also phenomena of physics, of astron-omy, of chemistry, and to a lesser extent, of biology; and to properly deal with them a knowledge of mathematics, physics and chemistry considerably beyond the elementary level is necessary. Already many of the physical and chemical problems of the earth, such as earthquakes, gravity, hydrology, meteorology, and the physical chemistry of rocks and minerals, are being attacked with considerable success by the employment of the methods of physics and chemistry, and being written almost exclusively in the language of advanced mathematical physics and chemistry. Geophysics is not just a "borderland field" between two sciences; on the contrary, it is the process whereby the knowledge and techniques of the more fundamental science, physics, are borrowed and employed in solving the problems of the more dependent science-geology. Geo-physics therefore embraces a large part of the two sciences taken together. The institution of work in geophysics, in its true sense, in depart-ments of geology would go far toward correcting the present inadequate training of students of geology and bringing the members of that profes-sion more uniformly abreast of the advances being made in earth science by people whose training has been primarily in the fundamental sciences of physics and chemistry rather than in geology. If something of this sort is not done, the geological profession may contemplate being left farther and farther behind as the scientific procession moves onward.

Jan 1, 1938

By J. P. Piguet, Y. Wileveau

ABSTRACT : An experimental programme for damage assessment was performed in the vicinity of the main shaft of Andra’s Underground Research Laboratory, currently under construction in the East of France, when the shaft is crossing the Kimmeridgian marls between 80 and 100 m depth. The mechanical behaviour was analysed by mean of convergence and displacement measurements. The disturbance into the wall was assessed using numerous methods such as measurement of sonic velocities, permeability measurement and VSP measurement in radial boreholes. The intensity of the damaged zone is low, and its extension does not exceed 0.5 time the radius of the shaft. It does not seem to depend on blasting patterns. ZUSAMMENFASSUNG : Ein Forschungs- und Versuchsprogramm wurde aufgestellt, um die beschädigte Zone im Bereich der Kimmeridgemergel zwischen 80 und 100 Meter Tiefe beim Zugangsschacht des im Bau befindlichen Andralabors im Osten Frankreichs zu berechnen. Das mechanische Verhalten der Formationen wird auf der Grundlage von Konvergenz- und Verschiebungsmessungen ermittelt. Verschiedene Messmethoden, wie z.B. mikroseismische Geschwindigkeite Messungen, Permeabilitäs- und Beschleunigungsbestimmungen in strahlenförmigen Bohranordnungen, erlaubten die Ermittlung des Beschädigungscharakters der Schachtwand. Die Intensität der beschädigten Zone ist niedrig, ihre Ausdehnung übersteigt nicht die Hälfte des Radius des Zugangsstollens und scheint unabhängig vom Schema der Sprengstoffanordnungen zu sein. RESUME : Un programme expérimental visant à évaluer la zone endommagée autour du puits d’accès du Laboratoire de Recherche Souterrain de l’Andra actuellement en construction dans l’Est de la France a été mis en œuvre lors de la traversée des marnes du Kimméridgien entre 80 et 100 m de profondeur. Le comportement mécanique des formations est évalué à partir de mesures de convergence et de déplacements. La mise en œuvre de nombreuses méthodes, telles que des mesures microsismiques, des mesures de perméabilité et d’accélérométrie en forages radiaux, a permis de caractériser l’endommagement en paroi du puits. L’intensité de la zone endommagée est faible et son extension ne dépasse pas 0,5 fois le rayon du puits. L’endommagement semble indépendant des schémas de tirs testés.

Jan 1, 2003

By Edward Keller

Someone some time ago remarked that some chemists still insist on telling us how to determine copper by the electrolytic method. The writer must confess that he believes that everything is not known definitely as yet as to how the exact amount of copper is determined in such material as purest commercial electrolytic copper. Some of us are not yet convinced that the pure copper atom is at all times deposited from an acid solution and that no oxygen or hydrogen will, under certain conditions, accompany it. Difficulties with impurer material are frequent, but erroneous results are not always apparent, since these do not speak so readily for themselves as those in the first case. By this is meant that if a chemist finds 100 per cent. of copper in electrolytic copper it is pretty certain that he perceives the result to be wrong, while if he finds 0.1 per cent. of copper too much in a very impure material he is far more likely to be unconscious of his error. These, in a wide experience, are frequent happenings and the writer has always looked with interest to publications on this subject. In turn, he feels justified in giving to others a few of his own observations. Up to a few years ago there were two methods of electrolytic copper assay in technical use, which had in common, that the amount of copper deposited on the cathode did not exceed 2 g., and they differed in that, for the one a large sample1 (20 to 80 g.) was taken from the general sample by a splitting device, dissolved, and from the solution a small portion (to contain 1 or 2 g. of copper) measured out for the electrolytic deposition; in the other method the copper was determined, generally in 1-g. portions of the separated coarse and fine portions of the sample, all of which passed a 16 or 20-mesh screen, being accomplished by a 40-mesh screen,

Jan 1, 1914

Coal miners, especially roof bolter and continuous miner operators, work in a hazardous underground environment where they are often exposed to poor roof conditions. Nearly 500 rock fall injuries are reported each year, and 99% of them are caused by rocks falling from between the roof bolts. These loose rocks that injure miners are usually just a few inches thick, but on average weigh 280 pounds. NIOSH has found that most rock fall injuries can be prevented by installing roof screen during the bolting cycle. Roof screen is a sheet made of steel wires in a grid pattern. When screen is bolted up against the mine roof, it provides far more coverage than any common surface control used in the mines today. Because more mine roof is covered, there is less chance that a rock will fall and injure a miner. The facts about roof screen are shown in the new NIOSH video entitled “Make It Safer With Roof Screen.” Using extensive underground footage, the 7-minute video shows how well screen keeps loose rock from falling in difficult roof conditions. Techniques for installing screen from both outside-controlled and walk-thru roof bolting machines are shown. The video also provides safe handling tips, best practices, and information about machine technology that can greatly improve material handling. Throughout the video, a coal mine safety manager and a shift foreman talk about the tremendous difference that roof screen has made at their mines. An instructional booklet supplements the video with additional information. It presents compelling data from mines that have practically eliminated rock fall injuries with a roof screening program. Other sections of the booklet discuss in greater detail roof screen installation, tips for manual screen handling, a material handling system for roof screen, and use of the personal bolter screen, which can be easily handled by one person. Screen specification and custom ordering are described, including the sizes of screen, grid sizes, reinforcing (indicator) wires, edge cut options, and screen strength. A list of additional sources of information is also provided. Nearly every mine eventually encounters poor roof. Screen is one of the most powerful control techniques available. This new video will help make mine managers aware of screen, and it can help them in developing a roof screen installation program. It also serves as an information source and teaching tool for safety managers and trainers. The video can easily be integrated into new miner training programs or annual refresher training.

Mar 1, 2005

By Michaela Böberl

State of the art sinter coolers are working based on the cross flow cooling principle. Thus, only a part of the thermal energy can be used for heat recovery application. The other part of the cooling air is brought unused to the environment. Furthermore, environmental regulation regarding dust emission and intelligent usage of exergy are getting stronger. Therefore, Primetals Technologies developed sinter coolers based on the counter flow principle. The cooling air passes the sinter bed in counter-flow direction enabling a direct heat transfer from the hot sinter to the air. The exhaust gas temperature can be maximized by using the total heat of the hot sinter. Due to the possible usage of the total exhaust gas amount, diffusive dust emission is reduced to zero. Two types of counter flow coolers are in the portfolio of Primetals Technologies. One type is based on a stationary shaft, in which the hot sinter is charged. The flow of the hot sinter is in vertical direction from top to bottom, in counter direction than the cooling air. The second type is a circular hopper cooler. The hot sinter is charged on top of a moving bed. At the bottom of the bed the sinter is discharged. The cooling air flows also from the bottom to the top, following the counter flow principle. Depending on the requirements, one of the two counter flow cooler types can be chosen for optimized and efficient cooling of hot sinter..

Oct 30, 2017

By ir. H. Eraly

The allocation of miners to teams, and of teams to production faces, is complicated by the high degree of absenteism of miners in Belgium. Therefore, the exact knowledge of who is actually present at the beginning of a shift and of the exact skills of those present, enables the foremen and mine captains to constitute their teams before all men go down into the mine in the most effective way possible. This paper describes the system of attendance recording and of displays which the foremen use to constitute their teams and/or to interrogate the personnel data base in order to do so. It shows how the foremen dialogue with the computer, to change the function of a miner within a team, to another team, or the function of a team as a whole. The implementation of the system, data bases, and data communication equipment and procedures, is described. The benefits obtained are presented for each level of the company: foremen and team supervisors, engineers, mine management.

Jan 1, 1977

To provide accurate navigation and control of continuous mining systems.

Jan 1, 1996

By S Marsters

Imerys Tableware New Zealand Limited has mining rights to four deposits of halloysite, which are located about 203 km north of Auckland, New Zealand. These primary deposits were formed by the hydrothermal alteration and weathering of rhyolite domes. Halloysite clay is currently being mined from two of these deposits and then processed for export markets. From humble beginnings in the mid 1950s, the Northland halloysite was processed initially for paper filler markets and then for higher value tableware and technical ceramic niche export markets. The paper will briefly cover the geology and processing of halloysite and then examine the history of New Zealand China Clays Limited, now Imerys Tableware New Zealand Limited and then look to its future as part of global industrial minerals company, Imerys.

Jan 1, 2002

By William B. Lee, James J. Jurmu

The Cleveland-Cliffs Iron Company operates three open pit iron mines on the Marquette Iron Range of Michigan's Upper Peninsula. Open pit iron ore mining began in the area in the 1840's. Underground mining was predominant from 1860 through 1960. Large scale low grade-open pit iron ore mining began in the early 1950's with the establishment of the Humboldt Mine, concentrator and pelletizing plant. This pit operated until 1970, when the reserves were exhausted.

Jan 1, 1986

By M. Clotilde Apua, A. F. Mulaba-Bafubiandi

"The efficiency of hydrochloric acid (HCl) leaching of gold from low grade gold-bearing material has been investigated in the presence of sodium hypochlorite (NaOCl) to produce in situ chlorine gas which is an oxidizing agent able to oxidize gold metal to its soluble forms. The effect of concentrations of HCl, NaOCl, and mixtures of HCl + NaOCl was sought. Iron and potassium present in the feed were leached and consumed all the HCl. Gold found as inclusion in pyrite was not exposed to the lixiviant. Therefore, leaching of gold from low grade gold-bearing material in aqueous chlorine solution is not an effective process for now.INTRODUCTIONHydrometallurgy of gold is commonly based on cyanide leaching solution. Due to the environmental concerns related to cyanidation and mercury processes, and inefficiency of cyanide gold leaching to dissolve refractory ores, sustainable alternative lixiviant systems, capable of generating gold (I) and gold (III) complexes must be studied. Amongst non-cyanide gold lixiviants there is the chloride/chlorine system (Hilson and Monhemius, 2006; Senanayake, 2004; Pilsniak and Trochimczuck, 2007; Wang et al., 2007; Reeves et al., 1999; Khodadad et al., 2008).In practice, the most oxidizing agents utilized for the leaching of gold as chloride, are chlorine (Cl2) or hypochlorite (HOCl) which are either generated in situ by suitable reaction or added in solution (Adamson, 1972). The dissolution of gold concentrate using hydrochloric acid, sodium chloride and sodium hypochlorite (Cl-/HOCl system) were studied (Puvada and Murthy, 2006). The effect of NaOCl and NaCl concentrations were also investigated. The leaching was performed under the following conditions; time: 4h, solid–liquid ratio = 1:4, at room temperature. It was found that the increase of the NaOCl concentration from 25 to 75 g/L did not have any meaningful effect on the recovery of gold which was about 30% (experimental conditions; S/L ratio = 1:4, NaCl concentration: 25 g/L, HCl concentration: 0.35 M). It was also found that from 25 g/L to 200 g/L NaCl, the recovery of gold rose from 30% to 40% (experimental conditions; S/L ratio: 1:4, NaOCl concentration: 25 g/L, HCl concentration: 0.35 M)."

Jan 1, 2012

By Felipe De Lucio Pezet

El presente texto analiza las hipótesis sobre los pernos de roca, así como las particularidades de las teorías de los pernos cementados y sus sistemas de sostenimiento.

Jan 1, 1978