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By Alex Del Castillo

The mineral processing industry has followed the development of database control systems, and various systems have been installed in existing and new plants. The goal is to improve product quality, raise productivity and lower production costs. Improvements in different units for mineral .processing .have been applied. This has led to increasing information for the operators. To support the operators and for an easy overview of the process, a complete concept for an integrated process-control system is required. This paper describes the plant-wide [process control system for the Collahuasi copper project located in northern Chile. The total investment for the project was $1,700,000,000 and included a port area and two copper processing plants, an oxide plant with a cathode production of 50 tons per year and a sulfide plant with a concentrate production of 330 kilotons per year. The main characteristics of the plant-wide process control system include a 200- kilometer long redundant control network and a 24-kilometer long redundant serial network providing coverage for the entire plant. The plants are located around 4,700 meters above sea level, serial communication lids allow the integration of over 2,700 SCADA data units, and the system handles over 7,500 physical signals plus the SCADA data integration. The main equipment consists of 39 different sized controllers, 16 operator stations, 5 engineering stations, 2 information management systems and 4 X- terminals. The project management, control configuration, factory acceptance test, system integration test, training, commissioning and start-up were carried out in close cooperation with the customer. The result was completely satisfactory for the customer.

Jan 1, 1999

By Martin Smirlock

A novel instrumentation system has been developed which enables simple, quick, and accurate measurement of vehicular dynamics within low speed ranges. The system, consisting of a microwave transceiver and microprocessor data acquisition and reduction system, measures the deceleration dynamics of low-speed mining and construction equipment. It makes the basic measurement, calculates key parameters such as average deceleration, initial velocity, stopping distance, and brake system delay time, and produces autoscaled graphs of velocity, acceleration, and displacement versus time.

Jan 1, 1981

By E. S. Bumps, W. F. Craig, M. Baeyertz

Metallurgists have looked at fractures macroscopically for many years and have evolved a vocabulary in which such words as "cleavage," "brittle," "shear," "ductile," "granular," "fibrous," and "silky" are used to describe the appearance of the fractured surface; but the meaning of these words in terms of metal structure is not well established. Observations of the structural meaning of "brittle" and "ductile" fractures in plate steels have been made, notably, by Kramer and coworkers1 and by Tipper.2 Grossman3 has studied the fracture of tempered martensite and combinations of ferrite and martensite. Notwithstanding these and other less concerted attacks on the problem, present understanding of fracture rests more on assumptions and logic than on experiment. It is the purpose of this paper to add a little to the growing fund of experimental observations of the nature of fractures in steel. The particular fractures to be described were obtained in conventional impact testing of an ordinary structural steel shape. In impact tests of the Charpy type, the specimens fail in a characteristic manner that depends on the steel and the temperature of testing. With ordinary structural and many other steel products, an appropriate range of testing temperature will cause a considerable change in the energy absorbed before fracture. This change is known as the energy transition and is accompanied, more or less closely, by alteration in the appearance of the fracture. At testing temperatures below the transition, the terms "brittle," "cleavage," or "granular" are used to describe the fracture; above it, "ductile" or "shear" are often used. Within the transition, the fracture changes from "brittle" to "ductile" by a progression in appearance, wherein the "brittle" portion of the fracture becomes restricted to a smaller and smaller central area of the fracture, as the testing temperature is raised and the "ductile" type of fracture is approached. All this is well known to metallurgists. The specimens under consideration are of the conventional V-notch Charpy type. They were taken from a structural steel shape of the following analysis: C Mn P S Si 0.17 0.46 0.009 0.029 0.03 Both longitudinal and transverse specimens were tested and examined. Fig 1 shows the energy values plotted against testing temperatures in the usual way. The curves for both longitudinal and transverse specimens show an energy transition, although the maximum energy absorbed at testing temperatures above the transition is greater in the case of the longitudinal specimens. Fig 2 illustrates the changes in the macroscopic appearance of the fractures that are associated with the energy transitions shown in Fig 1. Macrographs of the fractured surfaces of the specimens have been identified with the fracture ratings at intervals on each fracture curve. The numerical fracture rating on the ordinate of Fig 2 indicates the percentage of the area of each fracture that was considered to be "brittle" on macroscopic observation. Such rating of the fracture type in impact tests is now customary in many laboratories. Hereafter the specimens will be identified by reference to Fig 2 as 90 pct "brittle," 80 pct "brittle," and so on, in accordance with this macroscopic evaluation of the appearance of the fractured surface. The discussion of the fractures is divided into three parts. The first two are concerned with the mode of fracture and its relation to general structural features. As the same metal-lographic features occur in both longi-

Jan 1, 1950

By Steve Kral

For a state whose roots are in mining, most Colorado residents probably do not realize that the industry still contributes heavily to the state’s economy. In 2005, the industry contributed, directly and indirectly, about $8 billion to the state’s economy, according to the Colorado Mining Association (CMA). It employed nearly 10,000 people at mines and support businesses. And the mining industry in Colorado is one of the highest paying occupations in the state, averaging about $80,000 a year in wages and benefits. The state’s coal mining industry produced nearly 36 Mt (40 million st) of coal in 2005, valued at $800 million, the CMA said. That was seventh in the nation. And Colorado’s only major gold mine produced 10.2 t (329,000 oz) last year, valued at $124 million. That was third in the nation. And Phelps Dodge’s Henderson Mine produced about 12.7 kt (28 million lbs) of molybdenum, valued at $350 million. Colorado is the largest molybdenum producing state in the nation.

Jan 1, 2006

By William Escudero

El presente trabajo describe el planeamiento estratégico para el sostenimiento de la sociedad minera El Brocal a través de la gestión en el trabajo organizacional. Su principal objetivo es aumentar la productividad y la reducción de costos de minado y la planta concentradora. Para ello, se tomó el modelo de planeamiento estratégico desarrollado por Fred David y se realiza el análisis y diagnóstico interno de la empresa, a partir de los antecedentes, situación actual de la empresa, evaluación de la misión, objetivos actuales y cadena de valor de la empresa, luego se clasifica a la industria minera y se integra los resultados obtenidos, la matriz de evaluación del factor externo (EFE) y la matriz de evaluación del factor interno (EFI); para así elaborar la matriz (FODA) a partir de la cual se formula as estrategias por seguir. Finalmente, se redefine la misión de futura de SMEB y se ejecuta las estrategias y las acciones en las áreas funcionales.

Sep 13, 2001

By Sureshan K. Moothedath

This paper provides a mechanistic representation for floc formation, growth and degradation and presents results from an experimental study of batch flocculation in which step changes were made in the impeller speed, flocculant addition, and slurry concentration. A discussion of the experimental results is included in terms of the mechanisms of floc formation and size-change.

Jan 1, 1993

The ability to optimise a concentrator from mill feed to final products requires a simulator which integrates comminution, classification and separation modelling. In order to model this range of processes, such a simulator must handle a variety of information about the ore. The AMIRA P9 project has developed a whole-of-concentrator simulation capability which brings together a texture-based model of mineral liberation, quantitative X-ray micro-tomography analysis to measure the inputs required by this model, and a multi-component simulator software framework. In the context of this approach, the term ?multi-component? implies the ability of the simulation to handle many particle properties simultaneously; for example size, composition, density, floatability etc. The simulation software framework provides the means to manage the flow of data around a circuit flowsheet, allowing each process model to access the information relevant to that particular model. A case study based on plant data from a gold-bearing pyrite concentrator is used to demonstrate the capabilities of the multi-component approach in simulating circuits which contain comminution and separation processes.

Feb 27, 2013

By Edward Wisser

THE Pachuca silver district, situated about 100 kilometers northeast of Mexico City (Fig. 1), covers roughly the southeastern half of the Sierra de Pachuca. The latter is a mountain range with northwest trend, and forms a part of the northeastern rim of the topographic basin known FIG. 1.-LOCATION OF PACHUCA DISTRICT AND OTHER MINING CAMPS. as the Valley of Mexico. The length of the Sierra proper is about 50 km., its greatest width about 9 km., and it rises to a maximum of 600 meters above the general level of the basin floor. The Pachuca district consists of two contiguous subdistricts, the Pachuca area and the Real del Monte area. The center of the Real del

Jan 1, 1936

By Allan Gibb

The ores of copper are usually associated with minerals containing arsenic, antimony and bismuth. Whatever the means adopted for extracting the copper, these metals are usually found, to a greater or less extent, in the product. There is, however, usually some elimination in the various metallurgical operations to which the ores are subjected, and some attempt is made here to determine the degree to which this elimination is effected.

Jan 1, 1903

By Filipe Sathler

Mediante efeitos de sazonalidades do mercado Siderúrgico, períodos de crise, aliados às necessidades de reparos de equipamentos, os Altos Fornos são, eventualmente, submetidos ao desligamento. O procedimento específico mais utilizado é o Blowdown, com o abaixamento de carga até nível de ventaneiras, facilitando posterior limpeza e reparo. Para sucesso deste procedimento, é essencial um planejamento adequado das atividades. Informações técnicas e experiências operacionais permitiram o embasamento teórico e a execução do Blowdown do Alto Forno 03 da ArcelorMittal FCSA (Tubarão). Como preparação, foi efetuado o aumento do fluxo periférico (remoção de cascão) e o aumento da permeabilidade do Cadinho (maior circulação de líquidos, limpeza e drenagem). Realizou-se também a preparação de equipamentos específicos e controle dos parâmetros operacionais. O abaixamento de carga foi devidamente realizado conforme planejado, até o nível de ventaneiras e permitindo paredes internas livres de cascões.

Aug 16, 2017

By Heinz Distelmeier

Short Historical Review Tunnelling in Germany is as old as it is in other industrial countries. Until the middle of this century German contractors had no chance to work continuously in this business except if they were operating internationally. Since 1960, however, tunnelling has been a growing market domestically. The reasons for this growth have been both in the growing demand of traffic routes and also in an increasing environmental consciousness, which tries to transfer any cause of disturbance underground. Tunnelling engineers of course don't complain about this trend. As almost every German city is built upon water-bearing soft ground, shields have been used soon after they were first successfully utilized in Great Britain and the United States. Until the seventies lining systems for shield tunnels were predominantly either cast iron segments or concrete segments for primary support combined with different sealing systems and a secondary concrete lining cast-in-place. Steel ribs and timber lagging for primary support has not been utilized in Germany, since the owners don't accept timber to be left in the ground. In 1973, for the first time, permanent linings were constructed with watertight segment rings of precast concrete (Fig. 1). This lining was developed as an economical solution for use with slurry shields in noncohesive, water-bearing soils that required an immediately watertight lining. Extruded linings have a similar effect, although these still need a secondary lining

Jan 1, 1987

This paper considers two particular empi- rical models for the processes of the generati- on of hydrochemical zoning and epithermal near- surface mineralization of mercury-antimony-arse- nic formation in the discharge area of the Uzon Caldera ore generating hydrothermal system in Kamchatka. Vertical and horizontal hydrochemical zo- ning is caused by mixture of infiltration waters of the surface formation with fluid of chloride- sodium composition which are supplied up the-zo- ne of deep fault. Ore formation is caused by simultaneous existence of two geochemical barriers, namely oxidizing and reductive. The first barrier is determined by the-level of ground waters. The second one forms under the clay-opal screen un- der the influence of two factors, namely the inflow of deep reduction sulphur compounds (which are transported together with arsenic, antimony and mercury) and the generation of hyd- rogen sulphide as a result of sulphur- and sul- phate reduction. X-ray-amorphous phase of orpi- ment composition and realgar phase are formed, respectively, on the oxidizing and reductive Barriers.

Jan 1, 1987

By F. P. van der Meer

Roller Press grinding has become an accepted technology in the cement industry, and finds a growing application in iron ore processing. Its introduction to the gold industry will depend on anticipated benefits such as a reduction in power requirements, the increase in throughput, and higher gold recoveries from the ground ore. The presentation highlights some of the specific features of the KHD Humboldt Wedag Roller Press and the effects of various operating parameters on the grinding result. Based on recent experiences examples are given on the use of the Roller Press in mineral applications. The anticipated reduction of grinding energy when using the Roller Press is discussed, together with the reduction in Bond Work Index.

Jan 1, 1997

By C. R. Johnson, R. A. Greenkorn, R. E. Haring

Three confined five-spot miscible displacements at unity, favorable, and unfavorable mobility ratios were conducted in a shallow, water-saturated sandstone of Pennsylvan-ian age near Chandler, Okla. These studies, plus associated laboratory experiments, were designed to measure miscible displacement performance in a controlled natural system, using known scaling criteria to develop an approach to modeling the heterogeneous field system. We have concluded from these studies that: (I) displacement efficiency in the field is a pronounced function of mobility ratio, indicating that miscible fingering observed in simple laboratory models occurs in the field: (2) field displacements can be quantitatively predicted by scaled laboratory models if the degree and location of field permeability variations are preserved in the models: and (3) arbitrary simplifications of heterogeneity will not necessarily predict observed displacement efficiency, and the simpler the model, the more optimistic the prediction. INTRODUCTION Many processes to achieve miscible displacement of reservoir oil by injected fluids have been conceived and field tested by the oil industry. Among the better known are high-pressure gas, enriched gas, and LPG banks. The simplest form of miscible displacement—one fluid miscibly displacing another fluid of different viscosity but the same density—has been studied extensively in homogeneous laboratory models. Observations of unstable fingering have been made which explain the significant decrease in displacement efficiency as the mobility ratio (ratio of displacing fluid mobility to displaced fluid mobility) increases. General industry experience with field tests of miscible displacement projects, mostly LPG banks, has been premature solvent breakthrough and lower than predicted production rate increases. These results have been attributed to either unstable fingering, unusual or unexpected permeability stratification, or both. Miscible displacement data in a controlled natural system have never been reported, however. Also, it has not been shown that properly designed and constructed laboratory models quantitatively predict field-scale behavior. The purpose of the combined field and laboratory ex- periments reported in this paper is twofold. The first was to measure miscible displacement performance at different mobility ratios in natural rock approaching field size under precise, controlled conditions. The second purpose was to utilize known scaling criteria plus several approaches to heterogeneity to model the field. Comparison of model and actual field results should then determine whether or not the laboratory phenomena (manifested by miscible displacement efficiency) are exhibited in large, natural rock systems. We carried out our program by first locating a shallow, water-saturated reservoir whose rock properties were representative of oil-bearing reservoirs. Detailed reservoir description by core analysis and interference testing showed the field site to be heterogeneous. A sequence of controlled, aqueous-phase miscible displacements was conducted at unity, favorable and unfavorable mobility ratios. A central, confined pattern was used to obtain the displacement data. A laboratory program using sand-packed models was conducted to determine the modeling criteria necessary to simulate field behavior of miscible displacement in a heterogeneous system. SCALING THEORY The detailed derivations and descriptions of the scaling laws that apply to laboratory models of reservoirs are adequately described elsewhere, so the following discussion will be restricted to facets of importance in this study. For a displacement in which one liquid miscibly displaces another, the following dimensionless groups are required to have the same numerical value in the model as in the field: The model also must be geometrically similar to the field, be spatially oriented the same as the field (same dip angle), and have the same initial and boundary conditions as the field (same initial fluid saturations and same injection-production well arrangement). When these conditions are satisfied, the theory predicts that at dny dimensionless time (pore volumes of produced fluids) the dimen-sionless flow potential and dimensionless fluid concentrations will be identical at all dimensionless spatial locations within the model and the field. If this prediction is correct, then the local dimensionless velocities must be identical, thus the instantaneous fraction of displaced fluid produced and the cumulative recovery expressed as fraction of original fluids in place must be identical at all dimensionless times. The theory outlined above has been obtained by either dimensional analysis or inspectional analysis of differential

Jan 1, 1966

By Donald Barton

THE theory of gravitation is based on Newton's law that any two bodies exert a mutual attraction which is proportional to the product of their masses and inversely proportional to the square of the distance between them; i. e., A = K MM/R2 (1) where K is a constant, M and m are the respective masses of the two bodies, and R the distance between them. In the earth's gravitational system, the earth is one of the bodies; the other may be any body within or without the earth. In theoretical discussions and calculations in regard to gravity, that other body usually is taken as a unit of mass: in the C. G. S. system, a body of one gram in mass. GRAVITY AND LEVEL SURFACES Gravity is defined in geophysics as the force of attraction exerted by the earth, towards itself, on a body of unit mass. The intensity of gravity is usually expressed in dynes of force or in centimeters of acceleration. In geophysical work in America, most commonly it is expressed in dynes (per gram) with the "per gram" understood and not directly expressed. In geophysical work in Europe, most commonly it is expressed in centimeters per second per second (cm./sec 2) and less commonly merely as centimeter-gram-second units (C. G. S.). At sea level, the intensity of gravity amounts very nearly to 980 dynes. The vertical is the direction along which the attraction of gravity is exerted at any point. In most cases, it is very nearly, but not quite, perpendicular to the earth's surface. The path that would be taken by a body falling freely through space toward the earth is vertical at each point and may be spoken of also as "the vertical," or as the line of the vertical, or as a line of force of gravity. At the earth's surface it commonly is very nearly, but not quite, a straight line.

Jan 1, 1928

By Donald C. Barton

The theory of gravitation is based on Newton's law that any two bodies exert a mutual attraction which is proportional to the product of their masses and inversely proportional to the square of the distance between them; i. e., A = KMRm2 (1) where K is a constant, M and m are the respective masses of the two bodies, and R the distance between them. In the earth's gravitational system, the earth is one of the bodies; the other may be any body within or without the earth. In theoretical discussions and calculations,in regard to gravity, that other body usually is taken as a unit of mass: in the C:. C:. S. system, a body of one gram in mass. Gravity and Level Surfaces Gravity is defined in geophysics as the force of attraction exerted by the earth, towards itself, on a body of unit mass. The intensity of gravity is usually expressed in dynes of force or in centimeters of acceleration In geophysical work in America, most commonly it is expressed in dynes (per gram) with the "per gram" understood and not directly expressed. In geophysical work in Europe, most commonly it is expressed in centimeters per second per second (cm. /sec.2) and less commonly lrierely as centimeter-gram-second units (c. g. s). At sea level, the intensity of gravity amounts very nearly to 980 dynes. The vertical is the direction along which the attraction of gravity is exerted at any point. In most cases, it is very nearly, but not quite, perpendicular to the earth's surface. The path that would be taken by a body falling freely through space toward the earth is vertical at each point and may be spoken of also as ('the vertical," or as the line of the vertical, or as a line of force of gravity. At the earth's surface it comrrlonly is very nearly, but not quite, a straight line.

Jan 1, 1929

By R. W. Lawrence

"The management of acid rock drainage( ARD) to prevent impact when tailings are disposed of in the environment requires understanding of the phenomena giving rise to acidic drainage, a rigorous evaluation of the weathering characteristics of the tailings, and the successful implementation of control measures that will be effective in the long term. This paper provides a brief theoretical background to the complex reactions taking place in mill tailings containing residual sulfide minerals which must be appreciated to enable waste characterization program to be effective in predicting the future behavior of the tailings and in designing control methods which will work. The principals and practice of prediction and control as part of an ARD management strategy will then be discussed.Paper Not Available at Time of Publication"

Jan 1, 1997

By Kevin Phelps, Jason Baird, Philip Mulligan, Dominique Nolan

Determining the transitions from run-up to optimal cut length and optimal cut length to run down, without bias, from the penetration of a linear shaped charge (LSC) is difficult. The stresses applied to the targets during explosive testing can distort the targets in such a manner that determining the true distance of cut, penetration, or fracture can be demanding. Through the course of this research, it was observed that the researchers made many of the errors involved in the collection of data. Among these errors researchers found problems in: determining and fitting the sample to a single plane from which to read measurements, determining where along the path of cut the three phases of penetration transition, and the precision of measurement based on handheld tools and the human eye. This study looks at three methods of recording the data of a series of linear shaped charge tests. The tests resulted in samples which are not ideal for measuring with common laboratory devices like measuring tapes, calipers, or rulers. The first method utilized these common laboratory devices and the difficulties the authors experienced are described in this paper. The second and third methods involve digital photography, image manipulation, and the use of AutoCAD. Methods two and three are then compared to the simple observational method and discussion is made in regards to the precision and accuracy of each method.

Jan 1, 2013

By Robinson Irarrazabal, Edison Collinao, Rodrigo de Carvalho, Patricio Davila, Marcelo Tavares

"In recent years, DEM (discrete element method) softwares, along with 3D laser measuring equipment, have become powerful tools to describe mill charge behavior, as well as forces acting on the liners of SAG mills. With the aim of contributing to streamline this application of the advanced technologies ME Elecmetal and Universidade Federal do Rio de Janeiro, UFRJ, proposed a new approach to improve the design of mill liners using elements from mechanistic modeling of grinding. The paper presents a methodology for continuous improvement of liner design, which uses information from the DEM collision energy spectra in the mill discriminated for the different components (ore and steel balls), as well as information on the breakage properties of the ore being ground. From these it proposes the concept of "effective collisions", which corresponds to the collisions that are of sufficient magnitude to cause breakage, thus allowing to discriminate from impacts that do not cause breakage either in a first impact or after repeated loading. It also tracks the collision of steel balls against the shell in order to assess their potential damage to the liners. An industrial case study is presented of a 38’ diameter SAG mill, which was experiencing challenges associated to liner breakage and low efficiency with the old liner design. Through a modification of the liner design, simulations demonstrated the potential benefit associated to reduction in ultraprojection and improvement in mill capacity. Implementation of the new design in the SAG mill was carried out, resulting in increase in daily throughput from 6 to 12%. Further, the time spent in liner change was reduced by 47% given the reduction in the numbers of parts. This operation also benefited from having no stops due to unplanned shutdowns to replace broken tiles. These demonstrate the benefit of coupling advanced computational tools to sound engineering principles in continuous improvement of liners."

Jan 1, 2014

By John Dasher, Wilfred L. Freyberger, James H. Pannell, A. M. Gaudin

WHEN beryllium is bombarded by gamma rays under suitable conditions it evolves neutrons. This nuclear reaction, Bes + y + n + Be", [I] is utilized in the process that is described in this paper. The equation, which physicists often abbreviate to Bevy, n)Be" shows that a photon, y, is absorbed by the Be- sotope of beryllium which then emits a neutron, n, leaving Be8 as a residue." It has been determined that the threshold for this reaction is 1.63 mev; that is, gamma rays having an energy less than 1.63 million electron volts do not have enough energy to remove a neutron from the beryllium nucleus. The threshold value for the beryllium (y, n) reaction is lower than that for any other element. The next most sensitive element is heavy hydrogen (deuterium) whose gamma neutron reaction, D2 (-y, n) H1, has a threshold of 2.2 mev. Thus, gamma rays having an intensity between 1.63 and 2.2 mev will evolve neutrons from beryllium and from beryllium only. Nuclear reactions can be considered as occurring between a projectile and a target. The probability of the occurrence of any such encounter can be expressed in terms of the "cross section" of the target nucleus for the projectile and projectile energy. This cross section, then, is the area normal to the path of the projectile controlled by the target for the purpose of the reaction under consideration. Cross sections are usually expressed in barns, in which a barn is lo-" sq cm. The cross section for Eq 1 is very small, even for nuclear reactions, and of the order of 10"3 barns. It is therefore necessary that a high flux of gamma radiation at the appropriate energy be used to obtain an appreciable neutron yield. In view of the nuclear properties of beryllium it seemed that if pieces of beryllium ore on a moving belt were bombarded with an intense beam of gamma rays, those pieces which are rich in beryllium minerals would emit neutrons at a sufficiently high rate to make it possible to detect that emission, and to use it to actuate a mechanical device for removal of the active from the barren particles. The principal economic source of beryllium is the mineral, beryl. Beryl occurs mainly in pegmatites which are characteristically coarse grained. The suitability of mechanical concentration depends upon the size at which the desired mineral can be liber-

Jan 1, 1951