Search Documents

By L. G. Austin

My first contact with industrial milling was during the time I worked in the electricity generating industry in the United Kingdom. In visits to power stations to investigate either deposits in the boiler furnaces or polluting deposits settling around the stacks. I had to check the performance of the vertical coal pulverizers, since poor pulverization aggravated both problems. Naturally, then, when I came to the USA in 1957 to take a PhD in fuel technology at Penn State, I was put to work to review the science of coal pulverization. After this reviewing, I was completely confused. On one hand, there was a well-developed understanding of stress-strain equations, and a rapidly developing knowledge of how stressed, brittle solids fractured, based on the Grifith crack theory. On the other hand, reading in the grinding literature gave me: -Kick's Law, which was clearly not correct in the light of modem fracture theory; -Rittinger's Law, which was also clearly not correct; -Bond's Third Law of Comminution, which was claimed to have something to do with the Grifith crack theory, but where the connection between the two was made by intuitive pseudo-scientific reasoning I could not accept; -the choice of mill motor power for the most common type of coal mill, the Raymond pulverizer, was calculated from the fan power required to move air through the mill. Although I could accept the empirical connection between the two, it made no sense from the point of view of fracture energy. Even today, most books or review chapters on size reduction start from these laws. Incorrect statements abound in the literature, such as "the Hardgrove Index is based on Rittinger's Law," which it is not, "The Bond theory states that work input is proportional to new crack tip length produced in particle breakage," which is not true, etc. My own test work showed that these "laws" did not fit the data for grinding of coal. At about this time, Epstein (1948) and Broadbent and Callcott (1956), following the original work by R.L. Brown (1941) at the British Coal Utilization Research Association, proposed describing breakage as a series of fracture stages. I took their concepts and developed the basic differential equation for a batch grinding process continuous in time, analogous to a batch chemical reactor. Robin Gardner then joined the project and did his PhD on treating batch grinding in the same way as a batch chemical reactor. He found that the basic equation had already been partially derived by Sedlatschek and Bass (1953) in Ger- many. We confirmed experimentally the validity of the equations for describing batch grinding (1962) and formulated the equation describing steady-state continuous grinding in a fully-mixed mill. At about the time this work was published, Gaudin and Meloy (1962) and Filippov (1961) independently published essentially the same equations, but without experimental proof of the validity of the concepts. I will give a brief overview of what these beginnings had led to in the design of mills for size and power, and show some of the results of this more detailed understanding of grinding processes. Concepts of Fracture Mills such as tumbling ball, rod, pebble and autogenous mills and vertical mills such as the Raymond, and E-type, apply compressive stress to lumps or particles relatively slowly. Compressive stress applied to a particle of an elastic brittle solid imparts overall strain energy to the solid and produces local regions of tensile stress, [(Fig. 1)] (Berenbaum and Brodie, 1959).

Jan 1, 1985

By E. G. De Coriolis

The development of huge production facilities and of new or improved processes for manufacturing magnesium from its raw sources has been an outstanding achievement of this war. Furthermore, at least one new method has reached a stage of pilot production that offers promise. Its potentialities seem to indicate that a reduction in cost and simplification or elimination of problems incident to the use of at least one of the present processes are quite within the realm of possibility. Although magnesium of very high purity (99.9 per cent and higher) is obtained, and the rate of recovery reasonable (60 to 70 per cent). the ferrosilicon reduction process is open to a serious objection, which at the time its use was proposed was thought to be sufficient to raise some doubts as to its success, at least on a high production basis. The temperature range at which the reaction is carried out—namely, 2100" to 2150°F.—is very close to the failure temperature of the material of which the retort is made. It is so close that for a time it was assumed it might make commercial use of the process an impossibility. However, at the time under discussion, the demand for magnesium was so great that it was felt by those who had to go ahead and produce this essential metal that the emergency warranted their taking a chance on this process. Subsequent developments have fully justified the soundness of their decision. Fortunately for the war effort, when the plants were put into operation it was discovered that although the retorts did collapse in rather short periods of time, as predicted, they could be blown back into operable shape by application of high-pressure air. This practical method of operation so relieved the situation that the problem disappeared. Nevertheless, if the process had not been successful, or the production of magnesium by the electrolytic process had not been able to keep pace with demands, our war program would have been seriously impaired. Fireless Cooker'' Process For this reason a program was set up and assigned for the development of a new method that had been suggested to the War Production Board in 1941. It is believed justifiable in terming the method "new" for several reasons: (I) while utilizing the same (ferrosilicon) process as the Pidgeon, hence involving similar reactions, the type of retort or furnace is essentially different, (2) the method of operation, reaction temperatures, etc., differ materially, and, most important of all, (3) the problems to be overcome in making the process successful were not and could not have been anticipated by anything previously known about the Pidgcon process. As will be shown later, the briquetting process, the condenser, the furnace lining

Jan 1, 1949

By William A. Hustrulid

An overall summary and the individual reports of eight workshops to determine research and development needs in western mining ore presented. Problem areas are identified, and recommendations regarding priorities, funding sources, and prime movers are made. The objective of this contract was to identify research and development needs for advancing mining technology as well as health and safety measures for western U.S. Surface and underground mining. This was accomplished by convening a series of workshops where problems could be thrashed out by producers of trona, uranium, open pit copper, underground salt (from the Midwest and New York), underground metal and nonmetal, etc. In addition to problems, future priorities, funding, and the desicion as to who should be the prime mover on R & D were discussed.

Jan 1, 1976

By E. Niehuis, J. Y. Kim, H. G. Cramer, S. L. Chryssoulis, K. G. Stowe, C. Bendel

TOF-SIMS was used to detect, identify from parent molecular ions and determine the relative concentrations of collectors sorbed on the surface of mineral particles in concentrate and tailings samples from three Canadian concentrators. In the Kidd Creek Zn circuit, sphalerite lost to tailings carried on average a quarter of the amount of isobutyl xanthate present on that recovered to Zn concentrate; amyl xanthate, which is not reported as added to the circuit, was also detected on floated sphalerite and pyrite. At Brunswick, sphalerite particles lost to the scavenger tailings had ten times less amyl xanthate and isobutyl xanthate than those recovered to the Zn final concentrate, while both xanthates were detected on sphalerite floated to the Cu-Pb cleaner circuit. At Matagami, significantly more isopropyl xanthate and isopropyl dithiophosphate were detected on sphalerite recovered to the final Zn concentrate than on that lost to the Zn rougher tailings

Dec 1, 1995

By R. V. Ramani

One area of study in the Coal Mine Injury Analysis project was to illustrate and enhance the ability of mine safety management personnel to apply analytical techniques to injury experience data and to justify requests for funds for safety enhancement actions on a cost/benefit and other quantitative basis. Four volumes of this final project report detail (1) the objectives and scope of the mine safety management research, (2) the results of literature review, and case studies, and (3) models developed for mine safety management. The four volumes are titled as Volume III: Mine Safety Management, Volume IV: Analytical Techniques for Mine Safety Management; Volume V: Mine Safety Management Case Studies and Volume IX: Training Cost Model. In this volume, the quantitative procedures that have been developed for the mine-specific analyses of accident/injury experience data are presented and their applications are demonstrated in a summary form through case study examples. The quantitative procedures will aid mine safety management personnel to develop focused accident prevention strategies including training, as well as to justify the investment in such proactive programs through cost-benefit analyses.

Jan 1, 1993

By S. Addie

In the early 1990’s the British Columbia (Canada) mineral industry frequently discussed the need to participate in, and compromise with, public environmental interests in order to ascertain long-term stability. However, as the decade progressed the mineral industry withdrew from almost all meaningful public participation. As government protected areas policy in the past year has illuminated, there is a continued need for long-term land access stability. This paper historically analyses the public engagement policies of the British Columbian mineral industry while it participated in long-term consensus-based multi-stakeholder land-use planning processes. From this analysis the paper recommends that the mineral industry reengage the public and institute a new working relationship with environmental advocacy groups so as to ensure British Columbia becomes the most sustainable mineral producing jurisdiction in the world.

Jan 1, 2011

By John Dilworth

THE word "development," as used in connection with .mining, is a rather general term and in most instances must be qualified or explained before the exact thought in the mind of the user is made clear. For instance, by the development of a mining district is often meant its entire facilities of mineral production, such as railroads, towns, mine plants, etc. In speaking of the development of a property its prospecting by test pits or diamond drill borings may be referred to; or it may be the mines, strip pits or quarries from which the coal, ore or rock is won. But, as a rule, when the development of an individual mine is spoken of the idea in mind is the system of underground workings by means of which the mineral is recovered and transported to the surface. It is this character f development that is considered in this paper. The discussion will be confined to the ordinary room-and-pillar, system of mining. practically horizontal coal seams that is used in most bituminous coal mines in this country, and to only two phases of this subject; viz., what is properly included under the head of "Development"' as it appears on the books of a coal company or the inventories of an examining engineer, and how its "value" should be determined -by the accountant or engineer. No absolute rule or definite agreement covers these points, yet these questions are far more than academic. Development is often an important part of a mining company's assets, affecting the amount of its invested capital (and hence its rate of taxation under present Federal income tax laws) as well as the value of its total assets and the amounts chargeable to cost of coal and to depreciation.

Jan 7, 1921

By E. J. Haug, K. L. Clifford, K. L. Purdy

St. Joe Minerals Corp.'s Southeast Missouri Mining and Milling Division produces lead, zinc and copper sulfide concentrates at three of its operations. The Viburnum and Fletcher mills have been described in previous papers. The new Bushy Creek mill, dedicated in May of 1973, is an updated version of the Fletcher mill incorporating 8.5 m3 (300 cu ft) lead and zinc

Jan 2, 1979

By W. W. Aljoe

The use of protective canopies can result in canopy roofing and/or serious restrictions to operator comfort and vision. To document this experience, BCR conducted a field study of cab and canopy design and application which resulted in a catalog of 164 canopy designs and an analysis of field data which showed no simple relationship between working height and canopy-related problems. The relationship also involves (1) machine frame height, (2) mine floor undulations, (3) operator compartment dimensions, (4) canopy design and location on the machine. Data analysis indicates (1) present technology does not always permit successful application of canopies in working heights below 42 inches, and (2) development of satisfactory low-coal canopies is doubtful. The basic conclusion of the study is that future R&D studies should be directed at development of alternative protection systems and remote mining methods.

Jan 1, 1981

By Henry M. Harris

The roll forming of oxide powders was studied in a Bureau of Mines investigation to find the conditions and parameters required to make satisfactory ceramic strip. High-quality porous or dense alumina, zirconia, and porcelain shapes were made by sintering strip roll-formed at room temperature from powders containing minor amounts of binder and water. Strips with thicknesses of 0.04 to 0.08 inch and bulk densities from 40 to 90 percent of theoretical densities were made. The parameters most important to formability were particle size, condition of the powders, and roll gap. Other factors affecting quality were speed and surface condition of the rolls, amount and type of binder, water content, and sintering conditions. Ceramic strip was formed at rates up to 78 feet/minute, which is 13 to 23 times faster than reported by previous investigators, and forming was done in a simple and inexpensive roll unit. Reshaping the strip was possible by cutting, grinding, shearing, and stamping. The following innovations were developed that allow roll processing not normally possible with ceramic powders: (1) Fine-sized powders were made into strip by preparing these as partially sintered granules; (2) thick strip was formed by pressure feeding powders into the rolls; (3) flexible strip was made using a rubber-base bonding agent; (4) corrugated strip was formed on shaped rolls; and (5) porcelain strip was densified and reduced in thickness by rerolling while hot.

Jan 1, 1970

By J. H. Adkins

The goal of this program was to produce a set of baseline health and safety training materials that could be used by the metal/nonmetal mining industry to reduce injuries and to comply with federal training requirements. The materials developed are arranged in a two level outline format. The first level provides the title, course goals, background and topical outline while the second level provides a detailed outline of the course content. Visuals, designed to portray miners in a positive, attractive fashion, were done in simple line drawing so they would reproduce for handouts without loss of quality. Each of the required units in the Baseline Guides have one or more self-checks. These are designed to be suggestive of evaluation techniques the users can develop for themselves. An instructors guide and a mining terms glossary are included. In a second phase the program developed performance based training guides for Annual Retraining and Experienced New Hires in the Underground Salt Industry.

Jan 1, 1983

By Peter Campi, Harry R. Asche, Ian P. Callow, Edmund G. Taylor, P. Scott Smith

The US$1,850 million EastLink project is a 39km tollway and includes twin 3-lane,1.5km long, undrained driven tunnels. The hard rock tunnels are being built to avoid passing the motorway through the Mullum Mullum Valley and so to help preserve the unique flora and fauna in the area. This paper describes several of the key issues in the tunnel design and construction, including: the integration of the temporary support design with the Contractor’s tunnel excavation and support procedures, including sharing of responsibility between the Designer and Contractor for support type selection and the production of a project specific rock mass classification system to enable more objective determination of ground conditions. detailed hydrogeological assessments during the design and construction phases to allow confirmation of design loads for the tunnel lining design and the various suite of waterproofing tools in order to meet the project inflow requirements. development of a pre-cast invert solution to the main tunnel secondary lining to enable faster lining construction and to minimize risks to the tunnel membrane associated with fixing reinforcement and construction traffic.

Jan 1, 2007

By Robert Linton

This paper deals with work that has been carried on for over three years by the management and staff of the North Butte Mining Co. in an effort to standardize mining methods, to eliminate lost motion in the operating organization, and to improve the efficiency of the individual workman. Naturally, much of this work is an adaptation of ideas suggested by other mining operations or by practice in manufacturing and other productive industries. The studies, however, have developed some features that it is believed are new. Both new and adapted features are given in detail. The normal capacity of the North Butte mines is about 2000 tons per day. Hoisting is done principally through the Granite Mountain shaft, which is 3740 ft. (1140 m.) deep and equipped with an electric hoist capable of hoisting 200 tons per hour from a depth of 4000 ft. (1219 m.). The lowest stoping level is the 3400-ft. The Granite Mountain shaft is connected with the Speculator shaft, about 850 ft. (259 m.) south, and with the Gem, about 1150 ft. (350 m.) east, which are 3000 (914.4 m.) and 2000 ft. (609.6 m.) deep, respectively. These two shafts are equipped with reversible fans for ventilation. The Speculator has a steam hoist with a capacity of 150 tons per hour from the 3000-ft. level. The Granite Mountain shaft is concrete lined from the 1600-ft. to below the 3000-ft. level and gunited with cement from the 1600-ft. level to the surface. Sections of the Speculator shaft with a total combined length of 500 ft. (152.4 m.) are also concreted. There are approximately 36 miles (58 km.) of drifts and crosscuts in the mine, in which there are 15.2 miles (24.5 km.) of track. At normal capacity, about 75 stoping faces, 20 raises, and 30 sill development faces are working. Stoping is usually by the standard square-set method. Where the size of the oreshoot and character of the walls permit, the rill (or cut-and-fill) system is employed. Scope and Limitations of Standardization Standardizing mining operations presents problems quite different from the problems of the manufacturer. Methods of a successful

Jan 1, 1922

By Oscar Delgado Venero

Dado el alto potencial económico de los metales preciosos que genera Centromin Perú, el yacimiento minero elaboró un programa de investigación para la recuperación del oro y la plata, a partir de minerales marginales, relaves y productos intermedios de fundición. Durante el desarrollo de este programa, se utilizó el proceso de lixiviación en botaderos la extracción de plata para la extracción de los minerales piríticos de Cerro de Pasco, obteniendo resultados óptimos. Por tal motivo, el presente texto señala el proceso de lixiviación en botaderos que Centromin decide implementar en una planta industrial, utilizando como lixiviante el sistema de Nac1-H2 SO4 y la chatarra de fierro como agente de cementación.

Nov 24, 1986

By Brian Gar Wingfield

Bulk explosive systems have developed from the infancy stages in the early sixties to a sophisticated process of the nineties. With ever changing bulk explosives technology, bulk delivery and loading systems needed to keep pace. Efficiency, as compared with packaged loading, was the keyword allowing faster loading of trucks and shots. Efficiency was also improved by the explosives coupling factor that bulk loading permitted.

Jan 1, 1991

By Gerrit V. R. Goodman

In This Chapter [Design and operation of machine-mounted scrubbers Dust control with scrubbers and blowing ventilation Dust control with scrubbers and exhaust ventilation Dust control with exhaust ventilation and no scrubber Dust control methods common to all continuous miner sections Dust control for roof bolters] This chapter explains how to control dust at continuous miner sections in coal mines where the main dust sources are continuous miners and roof bolters. In relation to dust, there are three categories of continuous miner faces depending on the type of ventilation and whether or not a machine-mounted dust scrubber is used. These are— 1. Mining machines with dust scrubbers used with blowing face ventilation 2. Mining machines with dust scrubbers used with exhaust face ventilation 3. Mining machines without scrubbers used with exhaust face ventilation The approach to dust control is somewhat different in all three of these. However, there are many dust control features (such as the need to provide adequate airflow) common to all continuous miner sections. For workers at roof bolter faces, there are two dust sources: 1. Dust from the continuous miner when it is upwind. 2. A malfunctioning dust collector on the bolter, which allows dust to escape DESIGN AND OPERATION OF MACHINE-MOUNTED SCRUBBERS [Almost all new continuous miners are equipped with scrubbers. When the dust is excessive, it is possible that the scrubber needs some maintenance.]

Jan 6, 2003

By E. E. Wark, J. Rogers, I. W. Wark, K. L. Sutherland

SOAPS have been used as collectors for many years, but only in the last eight years have other long-chain paraffin salts been used. It may be anticipated that these newer collectors will be used mainly with nonsulphide minerals, for which the xanthates and similar compounds are of little value. On the other hand, the xanthates are both cheap and effective for sulphide ores and seem likely to retain their present eminence in this field. During 1938 and 1939 two of us (E. E. W. and I. W. W.) commenced a comprehensive investigation of the principles underlying the use of paraffin chain salts as flotation reagents. This research was sponsored jointly by the University of Melbourne and a group of Australian mining companies.[t] A broad, semi quantitative survey was then made of the field covered in the present paper. This was followed in 1940 by further work by one of us (K. L. S.). In 1941 the investigation was taken over by the Division of Industrial Chemistry of the Commonwealth Council for Scientific and Industrial Research, Australia. Discovery of some principles upon which are based the flotation of minerals by paraffin chain salts was followed by their application in the development of processes for the recovery of certain strategic minerals from their ores. Promising results in the flotation of cassiterite from various ores will be described in a subsequent paper. THE PARAFFIN CHAIN SALTS The basic requirements for a "collector" in flotation are that it should form a film over the surface of the mineral to be floated, and that this film should be orientated so that hydrocarbon (nonpolar) groups form the effective surface. When modified in this way, the mineral surface possesses some degree of air avidity. All investigators would agree with Taggart, Taylor and Ince23 that such a film can be produced only if the collector compound contains an active (polar) group to attract it to the mineral surface as well as the nonpolar group. One section of this large class of polarnonpolar compounds is the paraffin chain salts: CH3(CH2) „X where X signifies a polar group that ionizes in aqueous solution. Though the compound can ionize, it may be a weak or a strong electrolyte, and the hydrocarbon chain may be in the cation or the anion (Table I). Many compounds of similar constitution are available, but the usual polar groups are: -CO2Na, -SO3Na, -SO4Na, - PO4Na2, or an aminonitrogen group, the

Jan 1, 1946

By M. E. Hawkins

This Bureau of Mines report provides information on all of the 329 proved salt domes in the Gulf Coastal States and offshore area of the United States. It includes specific data related to location, depth to the cap rock and to the salt, storage facilities for LPG, and production of salt, sulfur, petroleum, and rock related to or associated with the dome structure in the subject area. Also included is a brief history of the salt, sulfur, and petroleum industries as related to the salt domes. Gulf Coast salt domes were the scene of the first discovery of a large deposit of rock salt in North America, the birthplace of the Frasch sulfur industry, and the location of the first large oil gushers that ushered in the modern liquid fuel age.

Jan 1, 1966

By A. V. Tarasov

In order to improve technical, economic and environmental performance of hydrometallurgical processing of intermediate products containing copper and nickel, the Gintsvetmet Institute and the IMET Institute of the Russian Academy of Sciences have conducted studies into the efficiency of the use of alternating current of industrial frequency on processes applied for hydrochemical leaching of various copper- and nickel-containing materials. It has been found that: 1.Imposition of alternating current over the process of leaching of softly reduced nickel oxide with recycled copper sulfate solutions resulted in an increase by 20 to 30% of the rate of the copper cementation process and reduced by 20% its activation energy. At the same time, the recoveries of nickel, cobalt and iron to the leach solution increased up to 82.2%, 78.5% and 57.1%, respectively, and that of copper to the cement precipitate up to 74%. Optimal process conditions have been identified with respect to the current density, electrode material, copper concentration in solutions and the process temperature. 2.In the process of hydroelectrochemical sulfuric acid leaching of nickel and copper sulfides, the grain size, the phase form of sulfides, the solution composition (H2SO4, Cl?, Cu2+, Fe3+)and the current amperage had an effect on the nickel recovery to the solution, which reached 90%, while the degree of copper transfer to solution did not exceed 20%. The process of hydroelectrochemical sulfuric acid leaching of nickel and copper sulfides with an addition of Cl? made it possible to selectively recover nickel into the leach solution along with concentrating copper in the leach residue. 3.When subjecting samples of commercial-grade magnetic fractions of converter matte to sulfuric acid leaching, the imposition of electric current, the concentrations of sulfuric acid and chloride ion in the solution and the duration of the reaction process had an effect on the process. The nickel recovery was 85% and that of cobalt and iron was 95% and the recoveries reached 97.5%, 98.3% and 99.8% as a result of repeated treatment of the primary residue under similar process conditions. Up to 75% of copper, 75% of sulfur and 99.0-99.5% of palladium was concentrated in the solid reach residues. The experimental data obtained indicates that the use of AC for hydroelectrochemical sulfuric acid leaching for separation of copper- and nickel-containing intermediate products has favorable prospects.

Jan 1, 2003

By J. E. Norton

PRODUCTION statistics show that during the period of emergence from the depres¬sion the coal industry was becoming increasingly cognizant of the economic and competitive necessity for mechanizing. About 1935 many of its leaders were becoming aware also of the alarming scarcity of men properly trained to cope with the new problems of mechanization. In order to get a factual statement of this problem, a special AIME Coal Division Committee + was requested to survey the condition. Its investigation disclosed that graduates of mining schools going into coal mining numbered 16 in 1939 and 15 in 1938. With this as a background, Pittsburgh Coal Co. foresaw that a comprehensive program was necessary if it was to enlist the services of trained technical men, who were an indispensable part of a mechaniza¬tion program. The purpose of this paper is to review the program set up, to comment on the successes and failures and to outline the future course of action. SUMMER WORK An inescapable conclusion from the mechanization statistics was that the opportunities in coal mining were good. Not only was there a void in technical skill to fill from past years, but the ac¬celerating rate of mechanization indicated an increasing demand for technically trained men for the future. The remedy lay primarily in presenting facts con¬cerning the coal industry to the under¬graduate engineers before they made their professional occupational choice. Based on this idea, one of the key points in the program - was summer vacation work for the undergraduate, which, through the inducement of summer earnings, brought men into the mines to take a look at the prospects. This was more successful than statistics indicate because the war badly scrambled the orderly working of the program, but it could not obscure the value of a summer work program. A decided advantage was that it gave the company a preview of the graduate. An observation on this part of the program is that it is extremely hard to gauge lower classmen, and we found it wise to give them the benefit of the doubt, as the last two years in college bring about surprisingly rapid develop¬ment in some men. We could readily single out the men at the opposite ends of the scale of competence. COMPREHENSIVE TRAINING PROGRAM Having adopted summer work as a

Jan 1, 1946