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By M. Z. Sukiennik

A static method for vapor pressure measurement up to 1450 K and above 1 hPa is presented. The method is designed for equilibrium and kinetic studies of metallic systems, including those with a chemical reaction. Application examples are given for determination of activities in condensed phases, and heterogeneous reaction rates and equilibrium constants.

Jan 1, 1993

By Víctor Arguelles

El presente trabajo señala el panorama geológico de las zonas auríferas Gigante, Alaska, Culebras ubicadas en el departamento de La Libertad, donde existen numerosos sistema de vetas con cuarzo y pirita auríferos emplazads s en rocas granodioríticas y tonalíticas de edad paleozoica y tonalidades paleozoicas. En esta misma geografía, se encuentran la galena y marmatita escazas en las partes altas de las estructuras que longitudinalmente presentan recorridos de hasta 400m.

Nov 8, 1982

By A. G. Kim

Increasing transportation costs, clean air regulations and the decreasing availability of landfill space are factors in the increased interest in the utilization of low cost disposal sites for coal combustion residues (CCR). Inactive surface and underground coal mines can satisfy the conditions for stable CCR disposal sites, and subsurface CCR injection can be beneficial in reducing the amount of acid mine drainage (AMD) often produced at such sites. The material is expected to add alkalinity to the subsurface environment and to decrease the permeability and porosity of the buried spoil. Both mechanisms can reduce the amount of acid normally generated at a mine site. The Bureau of Mines is cooperating with an independent coal company in a test of subsurface injection of a mixture of fly ash, from conventional power plants or from fluidized bed combustion (FBC) , with AMD sludge into a reclaimed surface mine. Changes in water quality parameters and the concentration of heavy metals in water samples from wells and seeps are being used to assess the effect of CCR injection. The preliminary results discussed here indicate that improvement in subsurface water quality was related to fly ash injection and that components of the fly ash were stable in the acid environment.

Jan 1, 1994

By G. R. Fitterer

Trends in slag composition in acid open hearth practice, particularly the variation in iron and manganese oxides during refining, are reviewed. A procedure which is currently being used to control the refining reactions is described and partially explained through slag phase diagram considerations. In addition, the ionic nature of these slags is considered and it is proposed that silica combines with the oxide ion and forms a series of complex silicate ions. The effect of basic oxides such as FeO, MnO, and CaO is apparently additive in furnishing the oxide ion for this purpose. IT is now possible to control192 the refining of steel in an acid open hearth furnace to a surprising degree. This control has been brought about through the knowledge and use of several facts and tests. These are: 1—A planned charge analysis based on a knowledge of the type of fuel, the bath depth, etc. 2—Knowledge and control of rate of fuel input as well as its method of atomization, if any. 3—Determination of the slag fluidity. 4—Bath temperatures (use of the Pt-Pt-Rh thermocouple). 5—Periodic determination of carbon content (use of the Carb-analyzer or Carbometer). Through the use of these control methods, a heat may be made to "melt-in" with or without residual manganese and silicon. The rate of refining or carbon elimination may be controlled accurately, and the desired tapping (or "go-ahead") carbon may be approached at a rapid or slow rate according to preference and type of steel being made. Thus operating time may be predetermined and greatly reduced. Further, all of the refining can be done without any ore or other oxidizing additions, and the heat may be brought to the desired tapping temperature simultaneously with the attainment of the desired carbon analysis. This control procedure is being used in most acid plants in the United States today and has been de- scribed.', ' Although the slag metal relations are sufficiently well known to control the heat as stated, yet it is possible to account for only about two-thirds' of the 0, which must have been used for the elimination of the carbon and other metalloids. Phase diagram studies' of the slags, slag weights, the metal particle theory,' ore additions, limestone additions, etc., may all be taken into consideration; yet, the mechanism of oxidation and source of all the oxygen remain to be explained. This paper reviews some of the principles upon which the control methods were based and proposes other possibilities regarding the unexplained phenomena. Old and New Acid Open Hearth Practice Some of the recent statements in the literature regarding acid open hearth operation are based on old heat data which are not typical of modern American practice. These old heat logs have been responsible for many misconceptions regarding the acid hearth practice and represent heats which do not coincide with modern methods. In recent years, American practice has been altered materially and these changes will be briefly described. Modern American Practice: A typical log of a modern American acid open hearth heat' is shown in Fig. 1 which indicates that the refining time was only two hours, during which the carbon was eliminated rapidly and the bath temperature increased at a fast rate. The manganese and silicon contents of the metal were essentially eliminated and their oxides had become constituent parts of the slag at the "melt-down" period. During the course of the heat, the MnO content of the slag remained practi-

Jan 1, 1954

By Gerardo Muñoz

All along this century CODELCO's smelters have been operating on conventional technology, which Codelco has streamlined by using oxygen, developing oxy-fuel burners for reverberatory furnaces and introducing oxygen smelting of concentrates in converters (Teniente Converters). Chuquicamata began capturing sulfur from its first Teniente Converter in 1985. Since then, it has implemented a program allowing to gradually increase such capture. In 1994 a Frame Law on the Environment was enacted in Chile. By virtue thereof and of CODELCO's corporate environmental policy, an investment program aimed at capturing more than 95% of gaseous pollutants in all its smelters in a term not exceeding twelve years was established. The above entails a substantial improvement of the operational management as regards fugitive gases capture and treatment. This paper describes the way CODELCO is to deal with this challenge with a view to fully complying with environmental regulations and obtaining the required environmental certifications of its operations.

Jan 1, 1996

By M. H. MacLeod

"IntroductionTHE ORE PASS raise system at the H.B. mine as contracted by the Patrick Harrison Company consisted of two raises 6 ft. by 10 ft. in section •at 60 degrees to the horizontal. No. 88-88 raise, the longer of the two, was a straight raise 690 feet long, with access only from the bottom. In addition, this raise had two branch knuckle-backs only one of which was driven by. the Patrick Harrison Company. The other, known as 88-89 raise, was 540 feet long with knuckle-backs at 280 feet and 410 feet. Its access, also, was from the bottom (see Figure 1)."

Jan 1, 1954

By A. G. Spencer

"The horsepower required to drive large grinding mills has increased dramatically during the past ten years. Limitations on the amount of power which may be transmitted by a single gear and pinion have resulted in the application of multimotor drives, with consequent loadsharing problems. It has also sparked the development of some entirely new drive concepts. In addition, the severe demands made upon the electrical system during the acceleration period have required that the selection of motors and electrical system design be closely coordinated. Moreover, the installation of such large process units results in downtime being very costly. The equipment selected and the plant maintenance philosophy must therefore be such as to minimize the risk of unscheduled downtime."

Jan 1, 1972

By Charles S. Ney

"ZINC-LEAD REPLACEMENT deposits straddle the steep-sided valley of Kicking Horse River at a point three miles east of Field, B.c., in Yoho National Park. The Monarch orebodies extend into Mt. Stephen on the south side of the valley, and outcrop at two points, 1,000 and 1,200 feet above the valley floor. The Kicking Horse deposits are in Mt. Field, on the north side of the valley, and they outcrop 200 feet lower.The East Monarch outcrop is said to have been discovered in 1884 during construction of the Canadian Pacific Railway. The larger West Monarch outcrop, 700 feet west of the original discovery, was not reached till 1917 because of its nearly inaccessible location on the cliff face.The Kicking Horse mine was staked in 1906. Little development was done for several decades, and mining was not commenced till 1935.At the East Monarch, mining was commenced soon after location, and several thousand tons of ore were shipped prior to 1912. At this time a gravity concentrator was installed. This was operated till 1924, and a total of 42,000 tons of ore were mined, including about 10,000 tons from the West Monarch. The period from 1928 to 1935 featured flotation milling and the mining of 265,000 tons of ore, mostly from the West Monarch orebody. Intensive exploratory development was carried out in both Monarch and Kicking Horse from 1935 to 1946. Production from both mines in this period totalled 380,000 tons. From 1947 to the time of closure in 1952, considerable new ore was found in both mines and 185,000 tons were milled. Immediate possibilities for finding ore in the Monarch were considered exhausted. Kicking Horse orebodies are known to persist with a low grade of zinc. Total production from the two mines amounts to 842,500 tons grading approximately 7 per cent lead, 10 per cent zinc, and 1.2 ounces per ton silver."

Jan 1, 1949

Jan 1, 1954

By F. E. Calkins

THE following presentation of the more important accumulated facts and probabilities involved in copper ore deposition is based on my experience in examination work and study of the extensive litera-ture of the subject; to make personal mention of all sources of information would require the naming of a small army of able geologists and other investigators who have contributed to, building up the science. I have tried to present the salient features of the subject in logical order and condensed form, and to point out the relative importance of processes involved. Doubt-less many geologists could suggest some changes and many additions. ORIGINAL SOURCE The original source of all copper was in the earth's interior; it has been brought to the outer part of the earth, within reach of man, in three ways: (1) By intrusions and flows of basic igneous rocks containing copper in minute quantities, presumably as silicate or sulfide. No orebodies have been formed by this method. (2) As segregations within intrusive igneous rocks, the copper minerals having solidified at the same time as the rock itself. The few deposits known to have been formed in this manner have been of little or no importance. The oft quoted Sudbury nickel-copper deposits are now known to belong to the class following. (3) By gaseous or liquid aqueous emanations from ,large deep-seated masses of intrusive molten rock. These emanations, or mineral solutions, ascended through zones of connected openings in the earth's crust and dropped their load at points far above their source. Deposits formed in this manner were the primary source of nearly all, if not all, of the world's copper production.

Jan 10, 1923

By Y. Kocaefe, D. Bhattacharyay, D. Kocaefe

The carbon anodes used in the electrolytic production of aluminum are made of petroleum coke, recycled anodes and butts, and coal tar pitch. Due to technological advances in the aluminum production technology, aimed at increasing production and decreasing energy consumption and greenhouse gas emissions, better quality anodes are required. Presently, the anode quality is evaluated by visual inspection and the analysis of a small core taken from 1.5-2% of the anodes produced. The visual inspection is susceptible to human error and limited to surface imperfections. The analysis of cores takes time, and therefore, it is difficult to determine the existence of a problem and intervene at the right time. In addition, the core does not represent the whole anode due to the non-homogeneity of anodes. A validated online anode quality control system can highly improve the situation. In this article, an electrical resistivity measurement method developed for this purpose is presented.

Jan 1, 2014

By Rong. G., T. Q. Lin, W. Du

Based on analysis of the evolutionary history of the valley in Baihetan, the mechanism of asymmetrical evolution, gradual migration-incision evolved from left bank to the right, is revealed in Baihetan river valleys. The process of in-situ stress evolution is carried out by using the Universal Distinct Element Code (UDEC). Consequently, the numerical results which indicate the main regulations of that stress field are as follow: (1) The phenomenon termed "high in-situ stress fold" appears in the bottom of the valley. With the maximum principal stress being 28-34 MPa, the stress increases significantly at a vertical depth of approximately 130 m. (2) The in-situ stress presents zonal distribution along the bank slope. It is apparent that the in-situ stress field consists of stress relaxation zone (SRZ), stress concentration zone (SCZ) and original stress zone (OSZ). The horizontal depth of stress relaxation zone varies from the left bank (roughly 200 m) to the right (about 120 m). Furthermore, the stress evolution of the left bank slope is studied. As a result, it is found that asymmetrical erosion contributes to the difference of the in-situ stress distribution as a critical factor, between the left bank and the right. And for an asymmetrical valley, the evolutionary process of in-situ stress field is a circular procedure, which includes the incision of valley, the accumulation of landslides and the migration of valley.

Jan 1, 2015

By R. J. Goodman, P. Lafleur

This paper presents a current interpretation and projections of recent statistics on raw materials availability based on familiarity with the Canadian steel industry and its development. Problems and opportunities are recognized and discussed.

Jan 1, 1976

By J. C. Yingling, J. Sottile

This paper addresses detailed models of the temporal pattern of material flows produced by longwall mining units and procedures for inferring the parameters of these models from field data. First, a model is established that predicts material flows referred to shearer position and cutting element. This model is comprised of trend and fluctuation components. The trend component, which is invariant between repetitions of the cut cycle, accounts for deterministic effects on the flow pattern, such as web depth variation as a function of the cutting operation, systematic tendencies for seam height and cutting speed variations along the face, changes in the relative velocity between the shearer and face conveyor, etc. The fluctuation component models random effects on material flow and employs time series approaches. Subsequently, a method is given for converting the positionally-referenced flows to temporally-referenced flows. The model serves as a basis for generating detailed, accurate computer simulations of material flows from longwall units. As such, it provides a more rigorous foundation for analysis of cutting procedures and outby materials handling systems in longwall mines.

Jan 1, 1994

By V. Ramachandran

In view of the increasing environmental regulations that have been promulgated in the last 30 years, non-ferrous smelters and refineries have learnt to handle effectively the process waste streams that need to be bled from the system for impurities' control The cations of concern are copper, lead, zinc, cadmium, mercury, thallium, nickel, silver, sodium and potassium. Anionic species of arsenic and selenium also need to be addressed, Sulfates and chlorides-not a major concern at present-have come under scrutiny in the recent past. The current paper reviews several treatment options with reference to a) types of waste streams processed b )process chemistry c)discharge options and recovery of treated water and d) sludge disposal The long term goal of any smelter and/lor refinery should be to achieve zero liquid discharge from the plant. Methods to obtain zero discharge are discussed.

Jan 1, 2003

By Frank E. Chase

Kettlebottoms are columnar masses of rock--the preserved casts of ancient tree stumps--embedded in coal mine roof strata (of which they are a part). Because unsupported kettlebottoms can detach from a mine roof without warning, they are a hazard to miners. The primary objectives of this investigation were (1) to better define and describe kettlebottoms and (2) to evaluate kettlebottom support techniques in terms of safety and effectiveness. A telephone survey of mine operators, interviews with Mine Safety and Health Administration (MSHA) personnel, and underground mine visits were conducted in Pennsylvania, West Virginia, and Kentucky. Information gathered during this investigation indicates that the size and frequency of kettlebottoms in mine roof are dependent upon past geologic events and biological processes active during the deposition of roof sediments. To ensure the safety of mine personnel, all undermined kettlebottoms should be supported. The roof should be bolted next to kettlebottoms less than 3 ft in diameter, close enough to allow a portion of a wood or steel header to be extended beneath each kettlebottom for support. Two bolts and a wood plank or steel strap should be employed to support kettlebottoms over 3 ft in diameter.

Jan 1, 1983

By G. Florez

Durante los años 1968 a 1970 al Servicio da Geología y Minería el Servicio de Geología y Minería desarrolló un programa de Prospección Geoquímica regional en el Norte del Perú, abarcando desde Cajamarca hasta la frontera con el norte en el Ecuador. El objetivo fue descubrir nuevas áreas mineralizadas con probable interés económico a través del muestreo de sedimentos de quebrada se recolectaron 1,600 muestras y se realizaron alrededor de 12,000 determinaciones por cobro, molibdeno, zinc, plomo y plata. En ese sentido, el objetivo del presente texto es revisar los últimos estudios geológicos y químicos (1970-1971) realizados en las áreas con mayor anomalía en la zona. Así también describe la ubicación, geografía, el muestreo regional, la comparación de dispersión entre Michiquillay con otros depósitos cupríferos y la orientación regional de mineralización.

Nov 20, 1972

By Aldin Ardian, Mustafa Kumral, Jagjit Singh

Risk assessment of mining projects is a requirement in the mineral industries. In this process, many risk variables are timedependent, and the only available data are historical time series. Moreover, in the case of a multivariate scenario, conventional forecasting methods fail to capture conditional dependency across the variables, which is important when there is an underlying causal relationship that needs to be modeled for accurate project evaluation. Thus, we investigated the use of copulas to capture the conditional distribution of the factors involved in a mine risk assessment study. We employed a multivariate copula-based time-series approach to model several uncertain variables. The Autoregressive Fractionally Integrated Moving Average - Generalized Autoregressive Conditional Heteroscedasticity (ARFIMA-GARCH) model was used for the conditional mean and copulas were used to model the error distribution, thus capturing the collective variation and dependence pattern across the variables. The method was implemented to model gold prices, copper prices, and the 10-year US Treasury bond yields and to determine the project’s net present value and probability of being economically feasible. The proposed approach can be used for cases where simulation of multivariate time-series is conducted.

Apr 13, 2021

By Gordon F. Revey

In construction and mining work, situations occasionally occur where hard rock or concrete must be excavated at locations near critical structures or utilities. Fearing damage from blasting, contractors and engineers often explore the viability of using mechanical methods or expansive concrete to facilitate the excavation work. However, for moderate to large excavations, the prolonged duration and high cost of using these methods is often impractical. In these situations, under the right conditions, controlled blasting and blast-management methods can be used to speed up the work and lessen costs. The process of determining whether or not blasting is practical is often complex, particularly when risks are high.

Jan 1, 2002

By Dr. -Ing. Wolfgang Pietsch

Many primary metallurgical wastes are in the sh.-ape of turnings; borings, chips, dusts, and other particuletes. While such. materials can be easily segregated and/or upgraded to yield high quality ?secondary metals with often known composition for easy recirculation into the production? process; their particulate nature results in various problems. Roller presses are used in an ever increasing number for size enlargement and densification of primary particulate metallurgical wastes for secondary metal recycling. The paper will mention the areas of application from A(luminum) to Z(ink), also including Brass; Cast Iron, lead, and Stainless Steel, as well as dusts from all types of melting and ladle furnaces or converters. Typical systems using roller presses for size enlargement. will be discussed.

Jan 1, 1995