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By V. Svalbonas

The process of grinding mill quality assurance brings with it associated truths and myths. When the mill quality assurance process took its first great steps forward in the late 1970s and early 1980s, they were in response to the conditions existing, in our industry, at those times. In the late 1990s, we are faced with different conditions, and problems, and need fresh solutions. Yet the system developed for the early 1980s has produced no new approaches for the late 1990s, becoming instead more hardened and entrenched. This lack of development and actual resistance to research is now costing the industry significant amounts of money in late start-ups and useless scrap loss.

Jan 1, 1999

By Brian Hart, Stamen Dimov, Aparup Chattopadhyay, Barun K. Gorain

"A novel gold deportment technique has been developed for complex copper-gold and double refractory gold ores using state-of-the-art technology. Characterization of these ores is a challenging task due to low copper and gold grades in ores, presence of both primary and secondary copper sulfide phases and variable proportion of visible and invisible gold in different sulfides and iron oxide phases.Double refractory ores are mainly composed of silicates and carbonates with moderate clay and mica, and minor amounts of sulfides and organic carbonaceous matter. Gold mostly occurs as ""invisible gold"" (sub-microscopic gold) as solid solution or as colloidal-sized particles in different sulfides and other phases. The dominance of invisible gold and presence of highly preg-robbing and finely disseminated carbonaceous matter adversely affects gold recovery in flotation and leach circuits. Characterization of this carbonaceous matter, commonly known as TCM and quantification of gold associated within TCM, along with different sulfide and oxide phases is highly complex and challenging.Studies were initiated on various complex ore deposits and also on samples representing various process streams. This paper presents the development of a systematic approach to diagnostic metallurgy using state-of-the-art optical and automated mineralogy techniques, namely, micro-probe, dynamic SIMS and TOF-SIMS analysis for quantification of invisible and visible precious metal content in various species. The relevance of the mineralogy characterization to metallurgy will also be discussed in this paper."

Jan 1, 2016

By William F. Jenks

The possibility that a hypothesis explains almost all observed facts may be satisfying. Yet the almost gives a distinct sense of uncertainty. Moreover, overlooking the almost, reliance on the favored hypothesis may close our eyes to the discovery of new information and, in the field of mineral exploration, to the possibilities of finding new and hidden ores. A case in point is that of mines such as the Elizabeth and Ely, along the copper belt in eastern Vermont, principally in Orange County. The geology of the Strafford Quadrangle, where the Elizabeth Mine is located, has been described by Doll (1944). Two informative papers (McKinstry and Mikkola, 1954, Howard, 1959) present much valuable information about the geology of the Elizabeth Mine. Both reach the conclusion that the ores were emplaced after the peak of metamorphism, through the agency of metal-bearing hydrothermal solutions. Both, therefore, conclude that the source of the ores was somewhere below the outcrop area, presumably in some hidden intrusive mass. Neither yields a satisfactory guide for further exploration. Howard (1959) cites geophysical observations which show that there is a mass with a density similar to that of granite under the Strafford dome, adjacent to the Elizabeth Mine on the West. Yet examination of gneissic granite in the Chester dome, 25 miles to the South gives no suggestion of a young, near-surface intrusive capable of carrying or mobilizing large quantities of sulfur and metals. The Acadian intrusives in New Hampshire and in the Barre district

Jan 1, 1968

By Roy G. Stott, John A. Johnson, Floyd G. Anderson

"This information circular discusses drilling and blasting in open-cut iron-ore mines and is one of a series of papers describing iron-ore mining practices in the Lake Superior district to aid in preventing accidents in that industry.The Lake Superior district consists of the Marquette and Menominee ranges of Michigan, the Gogebic range of Michigan and Wisconsin, and the Vermilion, Mesabi, and Cuyuna range of Minnesota. Open-cut mines produce 8o percent of the iron ore mined in the district; 98 percent of the total Lake Superior district open-cut ore is produced in Minnesota and 2 percent in Michigan. The entire Wisconsin iron-ore production is from underground nines. The Mesabi range in Minnesota produced 93 percent of the open-cut iron ore and 76 percent of the total iron ore in the district in 1947.During the 8-year period 1940-47, 619,000,000 gross tons of iron ore were shipped from mines of the district, or 85 percent of the United States output. Approximately 78,000,000 gross tons of iron ore were shipped from the mines of Minnesota, Michigan, and Wisconsin in 1947.This paper is based primarily on observations daring the period July 1947 to March 1948. Thirty-two open-cut mines were visited; 28 on the Mesabi range, 3 on the Cuyuna range, and 1 on the Marquette range. In 1947, 36,100,000 tons of iron ore was shipped from these 32 mines, or 59 percent of the open-cut ore and 46 percent of the total iron ore shipped from the district. During 1947 about 90 open-cut iron-ore mines were operating in the district, and the annual production of each ranged from 25,000 to 10,000,000 tons.Many recommendations included in this paper for improving safety and preventing injuries to employees were taken from Bureau of Mines Information Circular 7387.Data were collected under the direction of Frank E. Cash, former supervising engineer, Health and Safety Division, Bureau of Nines, Duluth, Minnesota. E. W. Felegy, mining engineer, Safety Branch, gave valuable assistance in reviewing and editing the manuscript.The authors gratefully acknowledge the information and assistance given and the numerous courtesies extended to them by officials of the following mining companies:All the Lake Superior iron ores occur in bedded formations that range from less than 100 feet to over 2,000 feet in thickness. These formations are designated by one commonly applied name, ""iron formations.""4/The Mesabi range in northern Minnesota, about 70 miles northwest of Duluth, was opened to mining in 1892; it is the largest single source of iron ore in the United States. It is 75 miles long and, because of the gentle dip of the ore formation, it ranges in width from 1-1/2 to 3 miles.5/ The ore formation, which is nearly horizontal, has a maximum thickness of about 450 feet and is covered by a glacial drift that ranges from 10 to over 100 feet in thickness. Most of the ore is near the surface and adaptable to open-cut mining."

Mar 1, 1950

By G. F. Comstock

THE subject of transverse fissures in steel rails has been discussed very thoroughly in recent years from various points of view and the final opinions expressed may be roughly classified into two groups: (1) That these fissures are the result merely of fatigue of the steel and are independent of the quality of the metal. (2) That the quality of the metal and the mill practice must have something to do with them. The first point of view was most-ably and logically presented by J. E. Howard,1 and in the discussion of this paper, as well as in several other preceding publications, Dr. P. H. Dudley, Consulting Engineer of the New York Central Lines, has strongly defended the other opinion.2 The steel makers of the country have naturally rallied under Mr. Howard's banner, hoping to place the entire blame for these. failures upon the railroads with their high wheel-loads, hard steel, heavy traffic, and sometimes inferior roach-bed; while the railroad men,, on the other hand, have been busy accumulating statistics and records in the effort to find an actual reason in the rails themselves that would account for the seemingly haphazard occurrence of transverse fissures under varying conditions and at widely separated points. The view that these fissures were due merely to normal fatigue under alternating stresses seemed most reasonable to the writer until quite recently, because from work clone in this laboratory, as well as the work of other investigators of the problem, no structural differences, in the vast majority of cases, were found between metal at the nuclei of transverse fissures and metal at similar positions in the same rails or in other rails that had not developed fissures. . Within the last year or two, however, since the method of etching polished sections for the microscope with a cupric chloride solution has been tried systematically. on lengthwise sections, passing through the nuclei of transverse fissures, evidence

Jan 11, 1918

By Lynn Long

We have seen many new developments in the explosive and blasting accessory category, but one of the most useful items is the blast control plug. Blast control plugs are cone shaped units that are placed in the stemming just above the explosive load. They are placed about 8 to 12 inches up into the stemming material.

Jan 1, 1996

By Jamie Girard Dwyer, Edward McHugh, Stanley Miller, Jeffrey Whyatt

This user's guide covers the operation of a suite of three computer programs-Bplane, Bstepp, and Bwedge. These programs can be used to evaluate the potential for plane shear, step-path, and wedge failures along the crest of a slope bench. Such failures reduce the width of a catch bench and may compromise the bench's ability to catch rolling or sliding material before it reaches miners working below. The Bplane and Bwedge programs address sliding of blocks defined by continuous planar joints. The Bstepp program examines sliding of blocks defined by more complex failure surfaces that include steeply dipping cross joints and may even include breaks across small bridges of intact rock. The programs are applicable to jointed rock masses where the joints are small relative to the overall slope and form a number of sets with uniform statistical characteristics within a slope sector. The theoretical basis, application, and operation of these programs are described.

Jan 3, 2007

By Michael D. Balen

The U.S. Bureau of Mines (Bureau) is currently conducting a four-year study to assess the mineral resources and the mineral development potential of the 5.7 million acre Valdez Creek Mining District (VCMD) located in southcentral Alaska. The VCMD study is part of the Bureau's ongoing statewide mining district evaluation program. This report is a summary of the 1988 field work. The field work involved collection of reconnaissance placer and rock samples, and also involved sampling and examination of the mines, prospects, and mineral occurrences which were identified by literature research of the geology, exploration history, and mining history of the district. During the 1988 field season, Bureau personnel spent a total of 11 weeks in the field, collected 1,006 rock and placer samples, and located, mapped, and sampled 106 of the known mineral occurrences. The Bureau has visited 243 of the 250 known mineral occurrences during the course of the VCMD project. Reconnaissance sampling for placer occurrences resulted in the identification of 4 previously unreported gold placer occurrences, and identification of 5 occurrences that contain detectable levels of platinum or palladium. Reconnaissance sampling for lode sources of base and precious metals resulted in the identification of 5 new Lode gold-silver occurrences, identification of 2 occurrences that contain elevated quantities of chromium, cobalt, nickel, palladium, and platinum, and identification of one occurrence that contains elevated quantities of copper, molybdenum, anti zinc.

Jan 1, 2011

By John Drew Ridge

For the early conservationists before the first decade of the twentieth century, conservation meant largely the planned preservation of water, forest, soil, and wildlife resources-renewable natural resources-through efficient use. Water was primarily thought of as a resource that must be kept available for humans to enjoy in a recreational sense and as a habitat for wild animals, birds, and fish. Little thought was given to conserving water for actual human or industrial needs. If industry entered the picture it was as an actual or potential polluter of water, which was the basic necessity for drinking and bathing and for outdoor recreation. Even the forests were only held worthy of conservation largely because they were areas in which wildlife could, or should, abound and in which human beings might find relief from the cares and problems of everyday life. Finally, the soil was to be preserved in its natural fertility through proper fertilization, cultivation, and crop rotation; in this the conservation program did enter the realm of the practical. For through soil conservation, the world was to be able to raise increasingly large crops of constantly improved organic foods which the steadily growing population of the earth was to need to survive and improve. Relatively little time, however, was spent on considering what profit the farmers of the world were to make from the scientific farming on which they were to embark. In short, the appeal of the early conservationist program was much the same as that of the entire era of Theodore Roosevelt of which it was a part; it was to the heart rather than to the mind; it was to emotion rather than to reason. Because of the way in which the problem was approached, conservation took on the character of a crusade rather than that of a practical plan for the betterment of man through economically sound methods of improving his environment and the uses he makes of it. Conservation had, then, all the advantages of a stirring appeal to the emotions, but it did not have the lasting results that would have been achieved by a program with a sound economic basis.

Jan 1, 1959

By A. T. Yu

Technology and economies of scale have, in the past decade, brought about the emergence of giant vessels. Meanwhile, to answer the need for rapid dispatch, as a means of combating the proportionately far greater demurrage charges, shiploading and unloading speeds have soared (Ref. 1, 2, 3). As the loading and unloading rates have dramatically increased, so has the cloud of dust grown in unbearable proportions. It not only has threatened to be a real menace to machinery and men, but in certain instances has also seriously jeopardized fish and marine life (Ref. 4). In an era when ecology is king, dust in shiploading and unloading can no longer be shrugged off as a mere public nuisance, and its control is now duly recognized as of grave concern to all. Even if public outcry were not a problem, from the operator's own parochial point of view, dust can adversely affect productivity and the well-being of the operating personnel. Without adequate control, it can also result in costly equipment maintenance, particularly when the dust is micronic in size, and abrasive. The Hierarchy of Control Techniques Given the great fortune of not yet having to deal with gas and odors, in the jargon of pollution control, our problem is confined to having to control "particulates" only. To deal with "particulates", the myriad of dust control techniques can be utterly confusing to those who are not entirely well versed in the methodology. Our analysis of what is available to date results in the following hierarchy of logical preferences: 1. Prevention 2. Removal 3. Suppression 4. Containment 5. Dilution Since it deals with the root cause, prevention always outranks the cure. Once the dust is generated, removal nips it in the bud. Only when dust removal is

Jan 1, 1972

By Arnold O. Tanner

The domestic mining industry gained more strength in 1988 as the healthy comeback that became evident in 1987 continued and grew for many commodities. The increasing and more stable commodity prices, still predominantly in the metals sector, reinforced both the new ways of conducting business and the use of technological advancements in successfully lowering operating costs during the last 4 to 6 years. Some commodities and companies still struggled to survive, but increases in productivity and profits were becoming more common.

Jan 1, 1990

By A. S. Yue

Small-angle tilt boundaries have been observed in a lamellar eutectic structure. These boundaries are morphologically similar to a theoretical till boundary originally proposed by Burgers. The production of a small-angle tilt boundary in the lamellar eutectic structure is attributed to the formation of an indentation on a planar solid-liquid interface during growth. Constitutional supercooling due to the accumulation of impurity atoms ahead of the interface is primarily responsible for the generation of an indentation. The distance between two faults of like sign, designated as lamellar fault distance, is calculated by the Burgers equation for small-angle boundaries. It was found that the lamellar fault distance decreases exponentially and the tilt angle increases exponentially with freezing rate. SMALL-ANGLE tilt boundaries have been observed in many crystals in the as-grown states by etching techniques. However, a detailed substantial proof for revealing the presence of dislocations in the form of etch-pits was recently accomplished by Vogel. These boundaries are described as an array of dislocations of like sign. The angle of tilt associated with a boundary is treated theoretically by Burgers3 and is given by 0 = b/D for small tilt-angle where b is the Burgers vector of the dislocations and D is their average spacing. During the course of experimentation on the solidi fication of the lamellar Mg-32 wt pct Al eutectic a microstructure which was strikingly similar to a dislocation tilt boundary was observed. An example of the type of microstructure is given in Fig. 1, which shows a combination of transverse and top sections of the lamellar eutectic structure. The lamellae of the top section on one side of the apparent tilt angle are not parallel with those on the other side. Consequently, some lamellae must be terminated somewhere. Fig. 1 shows that the termination of lamellae is analogous to a dislocation tilt boundary in a crystal lattice originally proposed by Burgers. This work represents a closer look at such structures. The factors governing the production of the small-angle tilt boundary are discussed in terms of the freezing condition and impurity distribution in the melt. The effect of freezing rate on the distance between two faults, designated as lamellar fault distance, and the tilt angle is also described. In addition, the lamellar fault distance is determined by means of the Burgers equation for small-angle tilt boundary. EXPERIMENTAL PROCEDURE The slightly impure Mg-32 wt pct Al eutectic rods, 5/8 in. in diam and 12 in. long, were made from 99.99 wt pct Al and 99.98 wt pct Mg and were cast in a high-purity graphite mold. Some of these rods were purified by zone-refining the eutectic using direct-radiation helical-coil furnaces5 A molten zone about 2 in. long was passed through the cast rods at a speed of 5.3 x 104 cm per sec for ten passes of the molten zone. Before the freezing experiment was begun, 2-1/2 in. of the material from the head and tail ends of the zone-refined eutectic were removed from the rod to eliminate any impurity. The freezing experiments were carried out under controlled conditions,8 using a protective atmosphere of purified argon. At the end of each run, observation of the tilt boundary was made throughout the entire length of the rod with a light microscope on the top, longitudinal, and transverse sections (three mutually perpendicular sections) of the lamellar eutectic solid. The experimental data used for the determination of interlamellar spacing and tilt angle were taken from the middle portion of

Jan 1, 1964

By T. D. Yensen

In the investigation of the magnetic properties of iron-nickel alloys,' it was found necessary in order to make the alloys forgeable, or malleable, to add small quantities of some other element. Iron-nickel alloys have been known for nearly a century, but have been made in commercial quantities only since 1885. Their remarkable mechanical properties were disclosed by Riley in 1889 and from that time on a large amount, of research work has been done both to discover new properties and to correlate the results obtained.2 Lately the Bureau of Standards has collected the published data in a special circular" giving in compact form an account of the properties of the iron-nickel alloys. It also contains a clear historical sketch of the development as well as a selected bibliography. The chief difficulty with the development of iron-nickel alloys was that the "pure" alloys do not forge readily. The addition of small amounts of manganese, however, made the alloys forgeable, and manganese has therefore come to be regarded as a necessary constituent of nickel steels. The present paper shows to what extent manganese is needed for various nickel contents and also what is the effect of other alloying elements on the forgeability. It also touches upon the cause of forgeability but refers to other sources for more exhaustive treatises on the subject. The alloys were prepared by melting electrolytic iron and electrolytic nickel with or without other alloying elements in the desired proportions in a magnesia crucible in a vacuum furnace under a pressure of 1 mm. mercury. The ingots, weighing about 2 kg., were allowed to cool in vacuo. If pipes or blowholes were present, the ingots were cut in such

Jan 1, 1922

By T. D. Yensen

In the investigation of the magnetic properties of iron-nickel alloys,' it was found necessary in order to make the alloys forgeable, or malleable, to add small quantities of some other element. Iron-nickel alloys have been known for nearly a century, but have been made in commercial quantities only since 1885. Their remarkable mechanical properties were disclosed by Riley in 1889 and from that time on a large amount, of research work has been done both to discover new properties and to correlate the results obtained.2 Lately the Bureau of Standards has collected the published data in a special circular" giving in compact form an account of the properties of the iron-nickel alloys. It also contains a clear historical sketch of the development as well as a selected bibliography. The chief difficulty with the development of iron-nickel alloys was that the "pure" alloys do not forge readily. The addition of small amounts of manganese, however, made the alloys forgeable, and manganese has therefore come to be regarded as a necessary constituent of nickel steels. The present paper shows to what extent manganese is needed for various nickel contents and also what is the effect of other alloying elements on the forgeability. It also touches upon the cause of forgeability but refers to other sources for more exhaustive treatises on the subject. The alloys were prepared by melting electrolytic iron and electrolytic nickel with or without other alloying elements in the desired proportions in a magnesia crucible in a vacuum furnace under a pressure of 1 mm. mercury. The ingots, weighing about 2 kg., were allowed to cool in vacuo. If pipes or blowholes were present, the ingots were cut in such

Jan 1, 1922

By D. G. Kuehn

Studies were conducted by the Bureau of Mines to determine the positive ions and neutral species produced in glow discharges of gas streams containing 1.0 percent NO in helium, 29 percent dry air in helium, and 1.06 percent NO in N2, Mass spectrographic measurements were conducted for gas pressures from 2.3 to 10.0 torr and dc currents from 10 to 20 mAo Ion species observed included NO+, N2 +, O2 +, N+, and 0+ with lesser amounts of He+, He2+, and N02+. Variations in various ionic and neutral species with discharge duration were interpreted to be consistent with an electrically induced dissociation of NO to produce N2 and O2. No nitrogen oxides were observed to form in glow discharges of the helium-air mixture.

Jan 1, 1975

By Edward C. Peterson

Recent studies indicate that the United States halt substantial reserves of ilmenite, one of the major titanium minerals. However, the studies showed that sources of rutile, another important source of titanium are limited. This paper summarizes and evaluates results and conclusions reached by the various investigations initiated by the Bureau of Mines and others pertaining to the titanium mineral resources of the Nation. Domestic occurrences of ilmenite that are economically exploitable by present-day beneficiation methods are found in Florida, New Jersey, New York, South Carolina, and Virginia. These deposits are estimated to contain 50.3 million tons of titanium dioxide (TiO2). Occurrences of ilmenite that cannot be processed economically under present technological conditions are found in California, Colorado, Minnesota, Montana, Oklahoma, Oregon, Rhode Island, and Wyoming. These reserves amount to 51.1 million tons of TiO2. Reserves of rutile found in the United States are estimated to be 1.8 to 2.1 million tons of TiO2. Other than occurrences in Florida and South Carolina, rutile is found either in small scattered bodies or in deposits where the mineral cannot be recovered economically by present beneficiation methods.

Jan 1, 1966

By Jiechao Liu, Lijian Luo, Yubao Ma, Bo Zhang, Yanfeng Yang, Xin Hong, Luming Liu, Jienan Liu

Reduction kinetics of stainless steel slag in iron bath smelting reduction was studied at the temperature of 1500℃ ~ 1650℃. It was concluded that the reduction process consisted of two parts. That is to say smelting reduction was controlled by stainless steel slag melting initially and by interface reaction later. In order to increase smelting reaction rate, the melting point of slag should be decreased at the first stage and adjust the liquidity of slag at later stage. Smelting reaction rate will be accelerated by means of optimize the slag content. The optimal reduction result that all most all of the chromium in slag been recovered was obtained in temperature was 1500℃, basicity of slag was 1.0~1.2, the value of Al2O3+MgO was 25%.

Jan 1, 2015

By W. P. Sykes

Seven years ago, Dr. S. L. Hoytl presented a masterful discussion of the hard metal carbides and cemented tungsten carbide. His lecture summarized most of the data then available in the field; many of the details relating to the production, properties and structure of cemented tungsten carbide had never been previously published, for, in fact, this information was only then being acquired. During the intervening years, the cemented carbides have assumed a place of real importance in the commercial field, with an ever widening variety of applications due to constant improvement in the control of production technique and the unremitting search for new compositions that might better the performance of the alloys in one or another type of service. The most recent summary of production methods, properties and guides for the successful application of the cemented carbides appears in the 1936 edition of the Metals Handbook. Of necessity, much detailed information relating to structures and physical properties is not included in such a summary, and it is with such details that the present discussion is concerned. Steps in Preparation While the past 25 years have contributed a valuable store of working knowledge in the field of powder metallurgy, many of the process controls are derived entirely from experience and are not as yet finally explained by a specific physical or chemical phenomenon. For most of the cemented carbides such difficulties are aggravated by our lack of knowledge not only of the complex alloy systems involved, but also by the possible changes in structure and even in composition which may accompany variations in temperature, heating time, and furnace atmospheres. The principal steps in the preparation of these cemented carbide alloys are fairly well known, but to supply a foundation for discussion these steps are briefly outlined as follows : 1. Formation of the metal carbide in the form of powder by heating a mixture of carbon and the metal powder or oxide for several

Jan 1, 1938

By W. P. Sykes

Seven years ago, Dr. S. L. Hoytl presented a masterful discussion of the hard metal carbides and cemented tungsten carbide. His lecture summarized most of the data then available in the field; many of the details relating to the production, properties and structure of cemented tungsten carbide had never been previously published, for, in fact, this information was only then being acquired. During the intervening years, the cemented carbides have assumed a place of real importance in the commercial field, with an ever widening variety of applications due to constant improvement in the control of production technique and the unremitting search for new compositions that might better the performance of the alloys in one or another type of service. The most recent summary of production methods, properties and guides for the successful application of the cemented carbides appears in the 1936 edition of the Metals Handbook. Of necessity, much detailed information relating to structures and physical properties is not included in such a summary, and it is with such details that the present discussion is concerned. Steps in Preparation While the past 25 years have contributed a valuable store of working knowledge in the field of powder metallurgy, many of the process controls are derived entirely from experience and are not as yet finally explained by a specific physical or chemical phenomenon. For most of the cemented carbides such difficulties are aggravated by our lack of knowledge not only of the complex alloy systems involved, but also by the possible changes in structure and even in composition which may accompany variations in temperature, heating time, and furnace atmospheres. The principal steps in the preparation of these cemented carbide alloys are fairly well known, but to supply a foundation for discussion these steps are briefly outlined as follows : 1. Formation of the metal carbide in the form of powder by heating a mixture of carbon and the metal powder or oxide for several

Jan 1, 1938

The Australian Mineral Industry's growth in the last two decades is directly related to the skill and experience of its consultants in mining, metallurgy, geology, finance, management, marketing, and engineering. The role of mining consultants needs to be re-examined, so that the quality of the service they deliver will continue to be adequate for the 1990's. One means of this evaluation is by examining Case Studies in the strategies and difficulties of developing contract and entrepreneurial research.

Jan 1, 1986