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By B Huls, B E. Smith, I Brake, M Yu

A brief outline of some of the pioneering events in the development of flotation technology, which originated in Broken Hill at the start of the 1900s, is presented. The development of the original Potter-Delprat process, the introduction of oils to generate froth flotation and the achievement of selective flotation processing are described, all focussed on solving challenges with the Broken Hill Pb-Ag-Zn ores. Some recent initiatives in flotation at BHP Billiton operations are also outlined, covering coal, copper, lead-silver-zinc and diamonds. Some views are offered on the characteristics of innovation in flotation and on possible trends into the future.

Jan 1, 2005

By T. N. Singh

Board and pillar system of mining has beer, practised in India in view of abundant availability of cheap labour force, low investment and quick return. Subsequently, selective mining from thick seems and partial mining under surface features boosted the trend. As s result over 2000 million tonnes of coal is locked up in form of developed pillars inclusive of about 1000 million tonnes of high grade coking coal in Jharia field alone. The trend of pillar formation is still uninterrupted as the estimated pillar reserve in this field in 1974 was only 700 million tonnes which increased to 961 million tonnes in 1983. The trend is not much different in other coalfields end as a rough estimate 100 million tonnes of virgin coal reserve is being transferred to pillar every year. The method of board and pillar mining is likely to remain moat preferred technology for decade9 to come in view of several inherent advantage in Indian mining conditions.

Jan 1, 1984

By Mark Larson, Steve Iverson, Brian G. White

The authors hypothesize that excavation-induced extension fractures are caused by elastic shearing displacement that in turn causes tension oblique to a propagating shear zone. Such extension is manifested as tension on scales larger than that of microcracks. En echelon fracture patterns are a common result. FLAC modeling confirmed that localized tension is created near the corners of mine openings. In the model, tension was concentrated at the leading edge of a simulated fracture in a pattern that could promote the formation of an en echelon fracture. Particle Flow Code models confirm progressive formation of en echelon tensile failures with distance from an opening. The elastic displacements and the resulting fractures facilitate reduction in applied load at the expense of shear deformation and lateral dilation. Understanding the mechanics of fracture and deformation is vital for designing more effective ground support practices, a major objective of ground control research being conducted at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health.

By E. A. Sondreal, F. I. Honea

This paper summarizes coal and ash properties and pilot-plant results for 14 key lignite seams in the Gulf Province, as well as discusses operating problems encountered by the four Texas power plants burning Gulf Province lignite. Some consideration is given to the design of future power plants.

Jan 1, 1982

By Takahide Wakamatsu, Douglas W. Fuerstenau

Contact angles on alumina are related directly to the adsorption of alkyl sulfonates at the solid-water interface and thus are strongly controlled by the pH of the solution, the concentration of surfactant, and the number of carbon atoms in the alkyl chain. As the pH of the solution is increased above the point of zero charge, sulfonate adsorption ceases and alumina remains hydrophilic. However, in neutral and acidic solutions, contact angles increase markedly in magnitude when the adsorbed sulfonate ions form hemimicelles at the solid-water interface. Under a wide variety of solution conditions, a limiting value of the contact angle is attained at the point of reversal of the zeta potential. Finally, contact angle phenomena are empirically correlated with the sulfonate adsorption density through the work of adhesion.

Jan 1, 1974

By Fred C. Bond

IN crushing and grinding the larger particles are more exposed to the work input. They absorb most of the work and protect the smaller neighboring particles from destructive contact with the crushing surfaces or grinding media. The importance of this exposure differential upon the reduction efficiency and product size distribution has long been recognized. Unfortunately, there has heretofore been no direct method of evaluating it, and such indirect methods as observing the slope of the plotted product size distribution line have been used as an indication. In this presentation the Third Theory of Comminution1 has been used, together with the exponential formula for size distribution, to evaluate the exposure ratio and exposure constant and to illustrate examples of their utility in crushing and grinding applications.

Jan 12, 1957

By Milton E. Wadsworth

Cost effectiveness in gold and silver leaching has centered mainly on reducing or preventing excessive use of lixiviants. In cyanide leaching practice, the active reactants, cyanide and oxygen, present different problems. The activity of cyanide may be adjusted at cost, but oxygen from air, has a fixed, low activity with an equilibrium concentration of ~7 ppm. Consequently, the use of air in agitation and heap leaching presents distinct kinetic problems. The refractory ores are either high consumers of oxygen or tend to immobilize dissolved precious metal-cyanide complexes. Commercial treatment of refractory ores involves oxidation by pressure leaching, roasting or biooxidation prior to cyanide leaching. Chemical reactions important in preoxidation of refractory sulfide ores by pressure leaching and biooxidation are considered. Major emphasis is given to the role of oxygen in heap leaching of oxidized ores.

Jan 1, 1995

By L. J. Erck, T. E. Ban

A discussion of laboratory procedures used to determine pellet quality and to simulate handling and firing conditions. Strength- temperature relationships in pelletizing; effect of chemical additives on agglomeration; and crushing, abrasion, and impact resistance of the pelletized products are discussed with respect to five different iron ore concentrates.

Jan 8, 1953

By Toshiki Hayashi, Shoichi Asahina, Kenitsu Hosokura

Sumitomo Metal Mining Co., Ltd.'s Kunitomi Smelter has been treating in the blast furnace copper concentrate containing bismuth. The bismuth is concentrated in the electrostatic precipitator dust and the converter dust. Bismuth contained in the converter dust is leached by a mixture of salt and sulfuric acid, and is then recovered by a cementation process using scrap iron. The bismuth cake thus recovered and the electro- static precipitator dust are reduced to crude bismuth metal which is further refined to a high purity bismuth metal by the pyrometallurgical refining process. Details of this process are elaborated in this report.

Jan 1, 1976

By Oliver C. Ralston, James E. Norman

Separation of minerals by froth flotation is rightly called an art. It can truthfully be said that no two ores separate in the same way. The difference in results obtained when natural and synthetic mixtures of minerals are separated is so great that such tests frequently have been worthless in attempting to select conditions in which a natural mixture will separate. With a few rare exceptions, the natural mixture is much more difficult to treat than a synthetic mixture, and a much poorer separation is obtained. Perhaps several experimenters have wondered why 10 or 20 per cent of a mineral being floated from an ore does not float and is different from the 90 or 80 per cent that is recovered. In experimental tests on pure sphalerite, observers' have noted that varying amounts of sphalerite may be froth-floated with pine oil alone, the amount recovered in the froth depending apparently upon the source of the sulphide. The only explanation of results such as these, barring insufficiency of frother or time of flotation, is that the surface of the mineral floated is different from that of the mineral depressed. This difference often has been found to be caused by natural contamination of mineral surfaces, apparently brought about by weathering and exposure to natural solutions. There is virtually no rock that is absolutely unweathered. One of the writers had an exceedingly instructive experience in 1931 while working with United Verde copper-zinc iron sulphide ore in Arizona. Nonselective flotation of chalcopyrite and sphalerite away from some of the pyrite was all that could be accomplished. All known depressants produced only slight effect. Sodium cyanide showed some effect, but so much had to be used that only a small amount of chalcopyrite could be

Jan 1, 1939

By Reginald S. Dean

Manganous oxide is readily soluble in concentrated ammonia solutions containing ammonium salts. Lixiviants of ammonia and ammonium carbamate permit ready extraction of manganese from reduced ores and the manganese in such solutions may be precipitated by heating to transform the carbamate to carbonate. THE widespread occurrence of manganese in low grade oxide and carbonate ores not amenable to mechanical concentration has led to extensive investigations of hydrometallurgical methods for producing a pure manganese compound suitable for further treatment. Manganese carbonate is the preferable compound. This product when fully crystalline and of not too fine crystal size is easily filtrable and stable in air. It can be converted to other compounds such as the oxides by heating in air or can be reacted with acids for producing salts. A useful hydrometallurgical process must produce relatively concentrated solutions that can be purified easily, reagents must be cyclically used, and heat requirements must be small. Neither the ammonium sulphate nor sulphur dioxide leaching processes that have been tested extensively fulfill these requirements. Other heretofore proposed processes have obvious limitations and have not been tried on a large scale. The present process is based on the discovery by the writer of a new group of aqueous manganese-ammonia complex solutions highly concentrated in ammonia, which permit rapid solution of manganous oxide to concentrations of 80 to 100 g Mn per liter and from which a fully crystalline, easily filtrable manganese carbonate is precipitated by the addition of carbon dioxide and partial ammonia removal. Although the process may be carried out with many ammonium salts, commercial advantages dictate the use of ammonium carbamate, which is obtained when CO2 is passed into concentrated aqueous solutions of ammonia. If the carbamate is used, the only reagents, ammonia and CO2, are volatile and may therefore be recovered from solutions and residues by heating, thus eliminating washing and extensive evaporation. Impurities are controlled easily as most metal oxides are either insoluble in the lixiviant or fail to precipitate with the manganese carbonate. Others are controlled by sulphide addition. The process has been tested extensively on a small scale on a wide variety of ores, including Three Kids, Artillery Peak, Cuyuna, and Chamberlain, as repre-

Jan 1, 1953

By L. A. M. Castro

As Canadian mines progress to greater depths, magnitudes of induced stresses increase, becoming high enough to cause rock mass damage and failure during excavation. In addition, depending on the orientation of key geological structures in relation to the in-situ stresses, induced shear loading can be developed on these structures, creating the potential for: a) remobilization of existing geological structures, b) formation of new seismically active structural zones, created through rock mass damage and coalescence along such structural zones, and/or c) interaction between existing and newly created structures. Numerical analyses were carried out to investigate four possible factors that might cause fault slip on controlling structures, namely: (a) unclamping, (b) day-lighting, (c) stress rotation and (d) pillar shear. Application to an underground mine in the Sudbury Basin allowed verification of these factors and the proposal of two alternative mine planning methods to limit fault slip on key structures: (1) pillar clamping and (2) stope sequencing.

May 1, 2009

By F. C. Gregory

"The ""safety bonus"" in metal mining is a sum in addition to the regular wage, paid to foremen or bosses for keeping the accident rate down to a specified minimum. It has been used with success for some time by certain companies as a regular part of their safety work. It is desirable from the employer's point of view in that the desired results in accident reduction must be accomplished before the bonus is earned; and from the standpoint of the recipient, in that he receives a reward for the additional effort which he has put forth in order to earn the bonus.While this paper relates to the safety bonus as applied in the metal mining industry, the bonus system discussed herein will apply equal well to coal mining, oil-field work, and other mineral industries.Various estimates have been made as to the percentage of accidents that can be prevented through physical safeguards, adoption of safe working methods, and other safety measures which can be initiated and carried out wholly through the management or the safety department. This percentage will always be a vari¬able according to the local plant and conditions. But all who have been engaged in accident prevention agree that such work alone cannot bring the accident fre¬quency down to where it should be, and that it is very necessary to work directly with the workmen, in an effort to make each individual do his share in making the work safe. In this latter phase of the work, the boss who has immediate super¬vision of the men is the one who can do the most, since he is in daily and frequent contact with the men while they are at work. In the metal mines, the shift and stope bosses are the key men; in the oil fields, the ""tool-pushers"" or sub-foremen, and the same applies to all industries. So it becomes necessary to keep these sub-foremen constantly interested in accident prevention, both because they are in personal touch with the men and because they are responsible for production and hostile to any plan which they think will interfere with their output. In large organizations it is the shift boss who represents the company and its policies to the man on the job."

Jun 1, 1924

ABB Industrial Systems is one of the largest electrical engineering companies in the world. ABB develops, manufactures and markets electric drives. The company has more than 100 years experience in the application of medium- and high-voltage AC machines. And ABB's continuous research and development program ensures that its machines use the latest technologies and materials. Each motor is custom designed to meet specific applications. The HXR high-efficiency motors (100 to 1,900 kW or 134 to 2,250 hp at 50 Hz) are efficient and have low noise levels. Typical applications are pumps, fans, blowers, compressors and pulverizers. The enclosed units are constructed with external cooling ribs and fans. And the motors are equipped with solid, longlife stators and rigid rotor construction. The patented rotor construction provides for low vibration levels. ABB's large synchronous motors (1 to 50 MW or 1,340 to 70,000 hp up to 900 rpm) are used in the mining industry for crushing, grinding hoisting and conveying systems. These motors are designed to customer's specifications, including existing foundations. They can be equipped with fixed or adjustable speed control.

Jan 1, 1998

By W. M. Courtis

This district commences near Pigeon River, the northeastern boundary between Minnesota and Province of Ontario, and extends entirely around the north shore of Lake Superior, terminating for the present at the Bruce Mines on Lake Huron. The discoveries of mineral-bearing veins have been confined for the most part to the lake shore, or to the country opened up by the Dawson Red River road. As yet the country back from the lake has been but little explored, on account of its roughness, being intersected by steep, rocky trap bluffs, 1000 or more feet high, and alternating white cedar and tamarack swamps. The forests are exceedingly difficult for prospectors. In many places Titanic piles of rocks, protected by chevaux-de-frise of dead cedars, with their hooked, tough, sharp branches, and a covering of spongy moss, sometimes several feet thick, successively guard against the discovery of hidden treasure. The Hudson's Bay Company for nearly a century have maintained trading-posts at Fort William and other points, which probably opened the way to the first discoveries that were made at Prince's Bay, near the western limit of the district. At this point a large vein was worked by Colonel Prince, the owner, as early as 1846. The richest part of the vein seems to have been on Spar Island, but work was stopped on account of excess of water. Sir William Logan states that a mass of ore weighing several hundred pounds and carrying 3 per cent. of silver was taken out. On the mainland small quantities of native and sulphide of silver were found, together with iron and copper pyrites, zinc blende, and galena, in a large spar vein. On the main shore a drift 165 feet long and 90 feet in depth

By Howard Smith

OF late considerable experimental and, theoretical interest has been shown in the rates of transformation from a single phase, usually a supercooled solid solution, into one or more phases. Such reactions may involve both diffusion and transformation of the major constituent, as in iron alloys, or it may simply involve diffusion, as in superstructure forma-tion and in age-hardening systems. Most of the work has been confined to ferrous alloys1-9t although two investigations have been made on copper alloys10,11. That such work may be of considerable, practical importance has been demonstrated by Bain12, by the workers at the Kaiser Wilhelm Institut fur Eisen-forschung13,14, and by the everyday use of precipitation and age-harden-inn principles15. Experiments in this country have generally followed Davenport and Bain's technique of rapid supercooling followed by isothermal treatment. In Germany16,17 the work has been extended to the study of the influence of accurately controlled and measured rates of cooling. The work on steel indicates that there are two subcritical temperature ranges where reaction starts sooner after quenching and proceeds at a more rapid rate than at other temperatures. At subcritical temperatures above Ar" where reaction is dependent upon atomic migration there is a period of time of which the length depends upon the alloy content and the temperature, before which no reaction has been detected. Daven-port and Bain1 find that different sorts of atoms in solid solution in gamma iron affect the length of this "prereaction" period differently, manganese

Jan 1, 1935

By John V. Beall

Given: One large, but dated open-pit copper mine and processing plants, down about one third in production capacity in decade because of declining ore grade. Solve for: Restoration of former peak capacity without further losses during period of reconstruction. That is the problem that Kennecott's Utah Cop- per Division began solving in 1963. Most of the work went to a task force of engineers, several of whom were plucked out of line jobs and assigned to the so-called "Expansion Project" for the duration. There was no doubt from the beginning that effective cooperation between Expansion Project engineers and operators was critical to success, and personnel was chosen accordingly. This foresight paid off. The Expansion Project is all but complete, and the Utah Copper Division is returning to its rated capacity of 300,000 tons per year of copper metal.

Jan 6, 1967

By Oliver C. Ralston, James E. Norman

Separation of minerals by froth flotation is rightly called an art. It can truthfully be said that no two ores separate in the same way. The difference in results obtained when natural and synthetic mixtures of minerals are separated is so great that such tests frequently have been worthless in attempting to select conditions in which a natural mixture will separate. With a few rare exceptions, the natural mixture is much more difficult to treat than a synthetic mixture, and a much poorer separation is obtained. Perhaps several experimenters have wondered why 10 or 20 per cent of a mineral being floated from an ore does not float and is different from the 90 or 80 per cent that is recovered. In experimental tests on pure sphalerite, observers' have noted that varying amounts of sphalerite may be froth-floated with pine oil alone, the amount recovered in the froth depending apparently upon the source of the sulphide. The only explanation of results such as these, barring insufficiency of frother or time of flotation, is that the surface of the mineral floated is different from that of the mineral depressed. This difference often has been found to be caused by natural contamination of mineral surfaces, apparently brought about by weathering and exposure to natural solutions. There is virtually no rock that is absolutely unweathered. One of the writers had an exceedingly instructive experience in 1931 while working with United Verde copper-zinc iron sulphide ore in Arizona. Nonselective flotation of chalcopyrite and sphalerite away from some of the pyrite was all that could be accomplished. All known depressants produced only slight effect. Sodium cyanide showed some effect, but so much had to be used that only a small amount of chalcopyrite could be

Jan 1, 1939

By E. G. C Charlesworth, M. J. Robertson

"Gold mineralization in the Main Reef Complex at Sheba Gold Mine is hosted within shear zones in a sequence of shales and greywackes of the Fig Tree Group. Competency contrasts between these rocks and a steeply dipping chert unit provided a locus for the development of right lateral steeply dipping shear zones. A set of flatter dipping shear fractures crosscut these zones with their intersections defining a system of en échelon ore shoots. Mineralization is both of vein type and disseminated strata-controlled replacement type. The latter occurs mainly within the wall rocks to the shear zones. Arsenopyrite and pyrite are the major sulfides, with arsenopyrite being confirmed largely to greywacke beds and pyrite to the more iron-rich shale units. Gold was introduced, together with minor sphalerite, pyrrhotite, chalcopyrite and early arsenopyrite, toward the end stages of a first pyrite phase. The mineralizing fluids were introduced along dilated cleavage planes and, emanating from these, produced a series of replacement fronts. Mineralization was syntectonic to late tectonic and occurred under conditions of progressive deformation, resulting in sulfides which are concentrated in the hinges of shear-related folds and semimassive sulfides within tension fractures which are folded, attenuated and fractured. An analysis of the structures shows a sequence of events in which an initial ductile simple-shear event with a steep sense of movement was succeeded by a more brittle strike-slip event. Mineralization is temporally related to the latter. This evolution in structural style was probably related to reactivation of the Sheba Fault as a transcurrent fault during emplacement of large granitoid bodies."

Jan 1, 1994

By James Howard

ON Aug. 25, 1911, a rail failed on the Lehigh Valley Railroad, causing a disastrous wreck. The surface of the fracture was in a plane at right angles to the length of the rail. There was a dark-colored, oval spot on this surface, located on the gage side of the head, representing the part of the rail which was the first to fracture. The nucleus of this spot showed that the fracture had an interior origin. Other fractures of this kind, the peripheries of which had not reached the surface of-the rail, presented surfaces having a silvery luster. The darkened surface of the present fracture was caused, doubtless, by the air having had access to it. This fracture was recognized as a fatigue fracture, of a modified type, its interior origin having been due to a component in the rail which is not usually present in cases of fatigue fractures. The metal next the running surface of the head of the rail was in a state of internal compression, this being the component not commonly met with in other cases, and which caused the fracture to have its interior origin. For the purpose of giving this modified type of fatigue fracture a specific name, for identification, the term "transverse fissure" was applied. No mystery was thought to attach to its formation, or to its development. The explanation of its occurrence was obvious in the light of common knowledge upon the behavior of steel under repeated alternate stresses. By reason of the state of internal compression at the running surface, the maximum tensile stresses in the head, under bending loads, were along an interior element. Here the tensile strains were higher than in the fibers more remote from .the neutral axis. Under such conditions the fracture of the rail would be expected to have an' interior origin. A discussion of the subject of transverse fissures essentially becomes a discussion of fatigue fractures, since they are identical. The descriptive term employed, merely for the identification of this type of fatigue fracture, had the appearance of creating alarm. Apprehensions arose that a new phenomenon in the physical properties of steel had presented itself, the explanation of which was sought in every

Jan 11, 1917