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By R. F. Pilgrim

A digital computer program to mathematically simulate the effect of limited changes in feed rate in the range of 80 to 95 tph on a plant-scale wet grinding circuit has been developed and tested. The circuit studied included an 8-ft-diam X 12-ft rod mill operating in open circuit and feeding two parallel 12-ft-diam x 10-ft pebble mills, each one operating in closed circuit with an 8 X 32-ft rake classifier. The simulation is an empirical one based on two sets of data collected manually from the operating circuit under what was said to be steady-state feed rates of 80 and 95 tph with all other operating variables also at steady state. The procedure is a combination of several published approaches to the modeling of grinding mills and classifiers and it is applicable to a wide range of circuits. The program permits the computing of the size distributions of all feeds and discharges of all grinding units and classifiers in the circuit for a specified feed rate. The data used in this report for demonstrating the program are unsatisfactory since the circuit was not operating under steady-state conditions when it was sampled. Consequently the circuit model parameters could not be accurately estimated. The predictive power would be greatly improved if new data were obtained under true steady-state conditions.

Jan 1, 1973

By D. Goodings, W. L. Fourney, Bonenberger, R., Uli Leiste

The problem of the maximum depth at which a mine buried in the surf zone or beach zone is a threat to landing vehicles is being studied by Naval Surface Warfare Center (NSWC), Indian Head Division, Naval Research Laboratory (NRL), and The University of Maryland Dynamic Effects Laboratory. The problem was divided into two parts: The first part involves determining how deep a pressure plate mine can be and still detect a vehicle passing over it. This requires determining the distribution of stress within dry and saturated sand when a vehicle passes over a buried mine. The results obtained from that study are presented in a related paper (1). This paper will cover the second part, which entails determining the impulse delivered to the vehicle. This is equivalent to determining the impulse delivered to a plate suspended above the detonating explosive charge and includes an investigation of the distribution of the impulse over the plate. The purpose of the research is to develop a scaling law and/or computational capability which will permit predicting impulse to be expected in the field from tests conducted in the lab. The computational effort is aimed at the development of and confidence in computer codes that can be used to predict stresses and strains in plates due to the detonation of buried mines.

Jan 1, 2004

Hunkered up against the spine of the Andes in a tight valley where natural refuge from avalanche hardly exists is the daring Rio Blanco project of Cerro Corp. The deposit here was found in 1904, but nature has foiled all previous attempts to open it. To an experienced mountaineer or a highway engineer with mountain experience, the avalanche hazard in the valley of the Blanco river would be immediately apparent. The collar shaft is at the head of the valley at an elevation of 3600 m and for 12 km down the valley there is no space on the floor for building very much; the dissected rock walls are roadways for avalanches and even a highway could not be maintained sufficiently passable. This is the proposition taken on by the Cerro Corp. Chilean National Decree #1699, passed on December 9, 1966, signified "Go" to the Compania Minera Andina, a company whose shares are held 70% by the Cerro Corp. and 30% by the government of Chile. The orebody, although only partially delineated, contains proven reserves of 120 million tons of ore averaging 1.58% Cu. When the operation comes on stream in the last quarter of 1970, it will be at the rate of 11,000 tpd. Annual production will be 65,000 tpy of recoverable copper in concentrates.

Jan 11, 1969

As the Mount Morgan electrolytic chlorine plant is the first of its kind installed in Australia, and as the details of this method of producing chlorine have, up to the present time, been kept more or less secret all over the world, the author trusts that this paper may fill a gap in the technical literature of the subject.When an electric current is passed through a strong solution of sodium chloride the following reaction takes place -2 NaCl + 2 H 20 = 2 NaOH + C1 2 + H 2 Chlorine gas is liberated at the anode or entering pole of the current, while caustic soda and hydrogen are formed at the cathode or leaving pole of the current. If the two electrodes be simply immersed in a vessel containing salt and the current be turned on, there will be no result save slight smell of escaping chlorine gas. The passage of the current will have certainly split up the salt water according to the above equation, but as the products would be in juxtaposition they would immediately reunite, and the electrical energy would have been spent without any beneficial result having been obtained. Therefore, the all-important problem in designing an electrolytic chlorine cell is the finding of some effective means of isolating from each other the chlorine and caustic: soda as soon as liberated from the...

Jan 1, 1911

WHEN Georgius Agricola, in 155o, dedicated his now famous De re Metallica to the rulers of Saxony, Thuringia, Meissen, and other, smaller principalities, he included in his review of previous works on similar subjects reference to two books written in German: one, an "anonymous, rather disorganized account of assaying for metallic content and of metals," which must be the Probierbüchlein, the other, "dealing - with veins, written by Calbus of Freiberg, a well-known physician."* Calbus is mentioned a second time-and cited-at the end of the Third Book of De re Metallica. Comparison of the citation with the Bergbüchlein leaves no doubt that Agricola considered Calbus of Freiberg the author of the latter work, although all the editions of the Bergbüchlein known now were published anonymously. It is generally accepted by those who have dealt with the bibliography of the Bergbüchleint that Calbus was Ulrich Rülein von Kalbe, who served the City of Freiberg, in Meissen, as health officer in 1497, as member of the City Council in 1509, and as mayor in 1514 and 1519. He died at Leipzig in 1523. In connection with the very garbled description of the mining compass toward the end of Chapter 3 of the Bergbüchlein it is of interest that von Kalbe is supposed to have been not only a physician of repute but a mathematician, astronomer, mine sur-

Jan 1, 1949

By C. M. Weld

Attention has been turned recently to the exploration and development of certain large blanket-deposits of brown iron-ore in Cuba. The most conspicuous of these to-day, and the one upon which the most light has been shed, is the Mayari deposit, situated about 15 miles south of Nipe bag. Here the Spanish-Aniericau Co. has sole control over 18,500 acres of ore-bearing lands, reported by its engineers to contain 500,000,000 tons of ore. The necessary plant and equipment, with docks and railways, is now under construction for the early marketing of this ore. A similar deposit, and undoubtedly the next to be exploited, is the ore-field at Moa bay, where from 13,000 to 15,000 acres of ore-lands, immediately adjacent to the shores of an excellent harbor, have been generously covered by numerous mining-claims, practically all controlled by four large interests;. This deposit is now estimated to contain approximately 350,000,000 tons, on the basis of dried ore ready for shipment, a figure which may be increased when the western limits of the ore-deposit have been more accurately defined. Other deposits of the same type, but smaller and less accessible, are those at Cubitas, situated from 12 to 15 miles north of Camaguey city,

Jan 1, 1910

By Bastias J

The Ranger uranium mine has operated in the Kakadu region of the Northern Territory since 1979. The mine's water management system was designed to cater for the wet-dry monsoonal climate and to satisfy the recommendations of the Ranger Uranium Environmental Inquiry - Second Report, 1977 (The Fox Report) with respect to environment protection. The Fox Report advised that the aquatic ecosystem of the region must be protected and that the mine should collect all runoff from disturbed areas. Furthermore, the mine was to operate as a no-release system until release standards, based on the experience of several years of operation and on the results obtained from monitoring and scientific investigations, could be established. Monitoring and research data have now been collected for a decade. it is evident that lower-than-expected concentrations of chemical constituents are present in the runoff waters which are retained on site. Standards have been established for the release of these waters to the streams when in flood during the wet season. Mine water quality data and release standards are presented. It can be confidently concluded that controlled release will not cause detriment to the aquatic ecosystems of the Kakadu region. The Ranger operation has demonstrated that environmentally responsible management of mine waters is feasible for future mining ventures in the Kakadu region.

Jan 1, 1988

By J. A. Ryder

Compressed air is a relatively inefficient yet very convenient vehicle for transmitting mechanical energy. It is inefficient when compared to, say, hydraulic or electric energy systems since compressor and pneumatic machine efficiencies are quite low (in the range 20-65%) and reticulation losses can be quite high unless adequate pipe diameters are used to minimize friction drops. It is convenient in that capital and maintenance costs of pipes and machines are exceptionally low, the equipment is flexible and lightweight, the technological level is simple, the form of the energy supply is intrinsic- ally safe, and as an additional minor but psychologically important benefit, it provides a ready source of cooling and air supply for emergency use in deep hot mines. It is for these reasons that compressed air is a premier source of energy for many forms of underground equipment, in particular hand or rig-mounted rockdrills, some forms of rock- handling equipment, and a host of minor applications including agitators, small-lift pumps and temporary f am installations. In a typical S. African deep-level gold or platinum mine, compressed air generation accounts for 15% of the total mine electrical energy bill - more than is used for hoisting. In these mines it is not uncommon for over 100 km of underground compressed air piping to be installed, primarily to supply handheld rockdrills.

Jan 1, 1979

By Henry B. Fernald

THE Federal income tax treatment of expenditures for exploration and development for mines and other natural deposits (other than oil and gas) was materially changed by special provisions of the 1951 Act that are continued in the present 1954 Code." These present provisions for mines in stance they are the same as the 1951 amendments to the 1939 Code, Secs. 23 (cc) and (ff), respectively, except that for exploration the allowable annual deduction is increased to $100,000 (from $75,000) and minor changes in case of property transfers are made with respect to the four-year limitation. Before 1951 the statutes made no specific pro- visions regarding development and exploration for mines, but the rules were prescribed by Treasury regulations: 1) Before the mine entered the production stage, all development and exploration expenditures for mines, less net receipts, were to be capitalized recoverable through depletion or written off as losses when determined worthless. 2) After a mine entered the production stage, development expenditures were deductible as expenses-currently if ordinary expenses, but on a deferred basis if extraordinary in scope. This recognized the two separate periods, one before and the other after beginning of the production stage. There was no distinction between an exploration and a development period, but exploration was included as part of development.

Jan 1, 1958

By H. W. Dow

Quite early in the beginning of the present century, hoisting equipment underwent a radical change, when electric motors were applied to furnish the power in place of steam engines. Naturally, in the beginning, motors were not employed for large hoists: most of them were small single-drum hoists for which the motor ran continuously and the drum was clutched in for hoisting by various methods, and the down-going trips were made on the brake. In 1911 the Nordberg Manufacturing Co. of Milwaukee built for the first time a double-drum hoist powered with a first-motion direct-current motor (Fig. I). This hoist embodied many of the features that are used on larger hoists today. In the early development of motor-driven hoists a more or less natural mis- take was generally made, which only recently is being corrected. Because the electric motor has a higher speed than the steam engine, mining people in general accepted, without question, the use of small-diameter drums and the resultant finding of the rope in multiple layers, which was not at that time, the general practice on first-motion steam hoists. Small-diameter drums can usually be driven by a motor through a single reduction of gears even with relatively high motor speed, therefore the complete equipment could be obtained with a lower first cost.

Jan 1, 1946

By R. Jr. Schuhmann

PROBLEMS in expressing, interpreting, and using size-distribution data recur in many phases of mineral dressing; therefore it is desirable that size analyses be ex-pressed in such a form, either numerically or graphically, that comparisons can be made readily. The size distribution of comminuted material is a result of a specific physical operation on the material and therefore should be governed by some definite physical principle, or cause-effect relation. Although this principle has not been dis-covered, it has been found that the size distribution of comminuted, homogeneous solids may be expressed by relatively simple mathematical equations. Two equa-tions in particular, proposed by Gaudin1 and by Rosin and Rammler,2 respectively, have stood out, both having wide demon-strated ranges of application. The form and the method of application of the two appear almost irreconcilably different on the surface, but, as will be shown, they are asymptotic in the fine sizes when expressed in the same units. This paper gives the results of a further study of the Gaudin and Rosin-Rammler relations, made with the object of develop-ing a form of size-distribution equation that will be more usable and more signifi-cant-particularly in comminution studies, both for interpreting the nature of size distribution and for evaluating surface. The work is summarized in the following:

Jan 1, 1940

By Donald E. Crowell

In the fall of 1969, ASARCO and Newmont Mining Co. began the design of the 700tpd concentrator at their Black Cloud shaft located near Leadville, Colo. The concentractor would treat by flotation a Pb-Zn-Ag ore containing minor gold values. Flowsheet design was based on laboratory test work performed at the Minerals Research Testing Laboratory of ASARCO. Since the concentrator is located at an elevation of 11,000 ft, cold weather was a major factor in design considerations. The original capacity was designed as 700 tpd but for various reasons an ultimate capacity of 1,000 tpd was desired. This necessitated special consideration in the design of several areas, particularly the grinding circuit. The grinding circuit chosen was a single 9 X 12 ball mill operating in closed circuit with one 20-in. cyclone. The ball mill will operate at low speed and as an overflow type originally. The mill can be speeded up and converted to grate type for handling the larger tonnage when required. Thickeners and filters were oversized and space was left for additional flotation cells in order to handle the increased tonnage in these areas. Pumps were sized so that they could handle the increased tonnage by increasing their speed. Construction began in May 1970; the Black Cloud concentrator went on-stream in April 1791.

Jan 1, 1974

Improve the efficiency of stainless steel pickling (chemically cleaning) operations by providing the industry a quick and convenient method to estimate pickling solution behavior and to estimate recommended ranges of nitric and hydrofluoric acid concentrations for effective pickling of stainless steels. Background Iron, chromium, and nickel in stainless steels react with nitric and hydrofluoric acids during pickling. Ions of these dissolved metals complex or combine with the acid anions. When the total metal concentration reaches about, 50 grams per liter of pickling solution, the solution no longer serves its purpose and is considered spent. Knowledge of cation and anion species in these pickling solutions contributes an insight into pickling chemistry and allows estimates to be made of the most effective ranges of acid concentrations. The Bureau developed a computational model of the complex equilibrium chemistry occurring among iron, chromium, and nickel and the pickling solution. Total concentrations, in grams per liter, of nitrate, fluoride, iron, chromium, and nickel were used as input; output was 17 cation and anion molar concentrations. The model, in the form (if an equilibrium program on a mainframe computer, was used extensively to facilitate Bureau research by determining chemical complexes in numerous stainless steel pickling solutions. However, the program's availability to members of the stainless steel industry, its intended users, was limited because of lack of mainframe compatibility and the difficulty of program maintenance.

Jan 1, 1989

By Chi-shing Wang

The late Professor P. B. Bucky of Columbia University introduced the principles and techniques of barodynamic experimentation in early 1931 by the application of centrifugal loading to achieve dynamic similitude between models and prototypes of mine structures.1 Later, he and his associates introduced the combined experimental technique of photo- elasticity and the centrifuge to determine the stress distribution in civil engineering structures and mine workings by the use of transparent bakelite models.2,3 The photostress technique, also known as the birefringent-coating method of photoelastic stress analysis, dates back to 1930, when Mesnager published its principles.4 Since then it has been widely applied to experimental stress analyses in many industries. A practical method of observing the dynamic behavior of opaque mine models, which are made of prototype materials, by means of a combination of the centrifugal and the photostress techniques is a new experimental approach under development at the Henry Krumb School of Mines, Columbia University.5 This paper summarizes the development of the barodynamic photostress technique and presents the information obtained from a recent series of experiments in the study of the behavior of rock beams loaded by their own weight. THEORETICAL BACKGROUND Theory of Pure Bending In the general theory of strength of materials, the flexure stress at any point in a beam of any type of cross section which has a longitudinal

Jan 1, 1968

By David A. Gulley

One of the advantages of the market¬place, economists believe, is that it automatically generates information which would otherwise be hard to come by. For example, supply and demand signals imply something about private and social sacrifices and benefits. This information is seldom perfect, and can neglect some costs and benefits, but it nevertheless is crucial data. Moreover, marketplaces can also eliminate the need for some information. For example; since market participants are voluntary actors, only those transactions are culminated in which a mutual gain occurs. This eliminates the need for some cost-benefit calculations. A corollary to this standard economic doctrine is that whenever a government or other party supplants a marketplace, it must generate some of the information either lost or newly-needed. (Schultze, 1977) In 1981, following a ten-year moratorium the United States government resumed leasing of publicly-owned coal. When the government designed this program, the goal was to guide the marketplace, rather than merely to respond, as a landlord, to the market's wishes. This goal has been modified somewhat, due both to the changing political climate and to the practical difficulties of implementing so ambitious an undertaking. Nevertheless, during this period of program design and implementation, part of the challenge of creating and using the necessary information fell to the professional modelling fraternity.

Jan 1, 1982

By J. J. Scott

INTRODUCTION Rock mechanics theory needs to be applied to solve ground control problems, but in the final analysis the mining method and equipment which is used will be those which solve problems in a practical manner. Equipment and its inherent productivity and safety as supplied as "off the shelf" items by manufacturers often dictate the size of mine openings. Operators may tolerate falls of ground and associated hazards if productivity and safety problems are not too severe. In this whole process the costs of mining finally dictates just what system will be employed and what equipment will be used. True solutions to ground control problems sometimes require that the mine operator step back and totally rethink his problems. The true cost of accidents are often missed and hidden in overhead costs. Losses in production and accompanying profit are not fully considered, false economics, such as using inappropriate roof support devices, are undertaken at times when using the most expensive devices to totally eliminate accidents may be the best overall solution. Automation to remove the worker from the hazard area is often over- looked as the initial capitol expense to apply it may be high. Cooperation between mine engineers, mine operators, safety personnel, equipment suppliers, and government inspectors, both state and federal, is required to reach workable solutions that best meet the goals of all parties.

Jan 1, 1983

By David Swan

No mystery shrouds the discovery of chromium. The indefatigable French chemist Vauquelin, in reporting his discovery of this chemical element to 1'Institut National in 1798, concluded his discourse with the statement: "I place before the eyes of the Institute a small quantity of chromium and several of its most re- markable combinations." Working with the so-called "red lead of Siberia, Vauquelin not only prepared numerous chemical compounds of the new metal, but he reduced the oxide to the metallic state. These chemical compounds possessed a variety of remarkably distinctive colors; so, acceding to suggestion, Vauquelin named the new element chrome (chromium), a derivative of the Greek word chroma, meaning color. Siberian "red lead" (crocoite) was not plentiful; however, it was not long before Vauquelin's prediction was realized that the chemical compounds of chromium would become useful in the arts when sources of chromium became more readily available. Although chrome-iron ore (chromite) became obtainable in France, the United States and elsewhere during the early part of the nineteenth century, it is interesting to note that from 1828 to about 1860, Maryland, Pennsylvania, and others of the eastern United States furnished almost the entire chrome-ore requirements of the world. Several countries each in turn have since dominated for certain periods the supply of chromite. In recent years, the largest tonnages have come

Jan 1, 1953

By Paul C. Miclea, Robert E. Murphy

The behavior of fire and airflows in a confined tunnel differ significantly from more familiar fire situations outside, due to the buoyant effect which tends to create a layer of hot smoke and gases flowing away from the fire near the crown of the tunnel, while air supporting combustion moves toward the fire beneath the smoke layer. A subway emergency ventilation system is designed to force air to flow through the tunnel, shifting the balance of heated air in the direction of the forced flow and avoiding the "back-layering" of hot gases and fumes. This paper presents a computer program, called the "Subway Environment Simulation" (SES), which can be used to predict airflows created by the emergency ventilation system. It utilizes the latest state-of-the-art analytical treatment of fires in enclosed spaces, including observations from mine fires and gas explosions. The program allows designers to reduce construction cost by identifying unnecessary ventilation shafts and by verifying fan capacities. In addition, the program allows the designers and operators to determine safe evacuation routes, in case of a train fire, by predicting the occurrence of back-layering. It can be used to determine when the ventilation system can control the direction of smoke movement to provide a clear and safe path for evacuating people and facilitate fire fighting operations.

Jan 1, 1989

The first introduction of automatic control systems for flotation occurred about fifteen years ago. The early control work coincided with the introduction of on-line assaying using XRF techniques. This OSA availability, coupled with the emergence of small digital computers suitable for process control in the late 1960-s, meant that the necessary process information and control hardware existed for flotation control experiments. A period of intensive research related to flotation control. ensued. A great deal of effort was devoted to the development of mathematical models of flotation. Plant experimentation sought to understand the effects of a range of flotation variables on the process. Finally, control loops were proposed and plant tested. An evolutionary pattern emerges when the range of flotation control installations is examined. The earliest systems had as objectives process stabilisation using reagent control. There were also some early attempts at flotation optimisation procedures, again using reagent variation. Current work is still associated with the same objectives. One of the difficulties with flotation control has been to recognise and define clear and precise control objectives. More emphasis is now placed on cleaner control which has the advantage that the objectives are usually well defined. A number of flotation control systems which cover a range of control system types is discussed. Based on this accumulated experience,a list of good and bad practice in flotation control is Proposed.

Jan 1, 1983

While mining silver at Butte in 1882, Marcus Daly is reputed to have told his partners in The Anaconda Silver Mining Co., "It looks rather gloomy. The vein is running into copper." Recently, The Anaconda Co. authorized an $11 million expenditure to be made over the next five years to ensure their "running into copper" at deep levels for many more years. The new development program is designed to permit both deeper and more widespread selective mining in "the richest hill on earth" by means of additional shaft-sinking, reactivating closed mines, and establishing new haulageways and centralized hoisting facilities. Historically a deep level selective mining camp, Butte will now continue its uncommon use of three main types of mining methods at one camp-selective mining, block caving, and open pit mining. It was thought by some people that the construction of the Kelley shaft and the subsequent beginning of block caving operations in 1952-outgrowth of the Greater Butte Project-signaled the end of stope mining of high-grade ores at depth. This feeling became more pronounced when, in 1957, the Berkeley open pit commenced operations. During recent years, the tonnage of ore mined selectively underground has decreased, but the new program will maintain the position of selective underground mining in the overall picture of the Butte operations for many years to come.

Jan 7, 1960