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By John W. Rushton

What role does maintenance play in the design of a new mineral processing facility? Consider the fact that most new plants never reach design capacity the first year-or the second, third, or fourth years. The fact is, according to data collected from several plants which have started up in the last ten years, mill throughput and equipment availability doesn't peak, on the average, until the fifth year.

Jan 3, 1978

By Harold Rabling

THE following notes are taken from results obtained on a standard 25-ft. Hancock jig 1 tested during regular operation in the Bonne Terre mill of the St. Joseph Lead Co. The object of the tests was to determine the conditions for most effective 'work, and the nature of products that could be made. The material treated was sized between 9mm. and 2-mm. round-hole screens, and was constant throughout the experiments, Three products were made, concentrates from the first three hutches, middlings from the fourth and fifth, and tailing from the sixth. The middlings were crushed in one pair of Allis-Chalmers Style B 30 by 14-in. rolls, and elevated with the original ore to the 2-mm. screens, oversize of which formed the jig feed. While this arrangement was very simple, it gave rise to undesirable crowding of the circuit. Table 1 shows tonnage and assay values of the jig feed and products at the beginning of the experiments, and brings out the excessively large amount of middlings, comprising 63.3 per cent. of the total material fed to the jig. The rolls, being heavily overloaded, did very little crushing, a screen analysis of the product showing that only 27 per cent., or 128 tons, was crushed fine enough to pass to the tables. The remaining 347 tons returned to the jig with 400 tons of original ore. At times, this overcrowding became much worse, and the tonnage in circuit grew to enormous proportions. It became imperative

Jan 8, 1917

By C. E. Sims

THE following presentation is more a summation of observations made and conclusions drawn over a period of three to four years than a report of experiments made with a definite objective. Tests were made, of course, to verify hypotheses, but the large mass of data was collected incidental to other work. Lack of space forbids the presentation of more than a few of those data. On the other hand, it is unfortunate that some of the most illustrative examples are not available. The work is admit¬tedly incomplete but is presented in the hope that it will stimulate further work along a similar line. The answers to many of the questions left unanswered by this paper will be found only after long and painstaking study, such as is scarcely possible in a commercial laboratory where problems of immediate importance consume most of the time. It is also hoped that this study will in some measure throw light on some of the dark spots of steelmaking, and help to clarify some of the annoyingly vague references to "good practice." Only cast steel was studied and the conclusions apply to cast steel, but it is the authors' opinion that the quality of rolled or forged steel is largely dependent on the quality of the ingot, which is a casting. Although this discussion deals almost entirely with inclusions, it is important that the reader understand that only those natural inclusions which owe their origin to the solubility of certain materials in steel and to the chemical reactions of steelmaking are considered. Accidental inclusions, such as entrapped particles of slag, nozzle, runner, or mold are outside its province and are not considered. Such accidental inclusions are always dangerous and should be carefully avoided.

Jan 1, 1932

THE 144th* meeting of the American Institute of Mining and Metallurgical Engineers was held in New York, Feb. 18 to 21, 1935. It consisted of the annual business meeting, 45 technical sessions at which 216 papers were presented (approximately the same number of sessions and papers as at the previous annual meeting), two sessions of the Board of Directors, three meetings of Section delegates, two formal lectures and two addresses, luncheon Monday, Tuesday and Wednesday for members and guests, six group dinners and eight group luncheons, ten committee meetings, the annual reception and dinner dance, an informal dance, a smoker-dinner and the annual meeting of the Woman's Auxiliary. Attendance was generally greater than for the two preceding meetings; the statistics follow (figures are in the order 1935-1934-1933); total registration, 1609-1534-1475; dinner dance, 577-543-426; dinner-smoker, 490-425-394; informal dance, 279-295-250; women's registration, 179-160-133; general luncheons, 1132-1034-734. The Coal Division held two general sessions on Monday and a symposium on coal-mine ventilation on Tuesday morning. The Committee on Bituminous Planning, Edward Steidle, chairman, presented a report at the Monday morning session. C. B. Huntress, President of Appalachian Coals, Inc., was the principal speaker at the luncheon on Monday, at which Eli T. Conner, Chairman of the Division, presided. Mr. Huntress was preceded by Howard N. Eavenson, President of the Institute, who spoke briefly. The Sectional Committee on Classification of Coal met Wednesday afternoon. A feature of the meeting concerning three Divisions-Iron and Steel, Institute of Metals, Petroleum-was the symposium on Use of Metals in the Petroleum Industry, Thursday morning and afternoon. Five of the papers presented at this symposium have been published in METALS TECHNOLOGY'. Another feature, of general interest, was the Tuesday morning session in the Auditorium, devoted to Federal Government and Mineral Industries. Dr. C. K. Leith delivered the principal address, on "A, Mineral Policy for the United. States." . The Institute of Metals Division held technical sessions Tuesday afternoon and Wednesday. morning and afternoon and on Thursday

Jan 1, 1936

By R. S. Shrode

By now most readers of this column are aware that it no longer has a regular editor. Tom Murphy, who did the job so well, has had to bow out because of his duties in Australia---duties that keep him from the luxuries of such things as typists and typewriters for rather extended periods of time. We will miss his regular contributions but hope and expect to hear from him as a guest columnist from time to time. Finding an editor to function on a regular basis turns out to be no simple task. This does not mean that there may not be candidates around who would secretly enjoy having their arm twisted into a "yes" position, but at the moment none has been found. Anyway, at the Salt Lake City business meeting it was agreed that we should try to spread the load around. To that end, the Regional Vice Chairmen were specifically singled out as one potential source of contributions. These fellows should have an opportunity for a hearing during their term in office. The existing organizational set-up of the IndMD Division may be a little unfair to this group of officers. The limited responsibility outlined in our Manual of Official Duties and Responsibilities does not offer them much chance for self-expression. Probably the by-laws were written so as to have a geographic representation of membership in case it should be needed at some time. But that is another subject. The point is that now these regional officers have an opportunity to speak out on topics of their own choosing through this column. Some have already done just that. There are also other potential contributors to the column. One is the Secretary, who twice a year uses the column for distributing the minutes of our business meeting to the members. Another is the outgoing Division Chairman. In Salt Lake City, it was decided that this officer should be challenged to contribute something each year as a means of reviewing events of the past year or explaining what should have happened but didn't. I am, therefore, trying to accept that challenge.

Jan 1, 1970

By Max Hebgen

I. Natural Features of State Affecting Power Development .. 792 II. Early Developments. 1. Big Hole Plant................. 792 2. Canyon Feny Plant............... 793 3. Madison Plant No. 1............... 593 4. Black Eagle Plant................ 795 III. Later Developments. 1. Madison River System .............. 795 2. Missouri River System.............. 797 3. Great Falls System............... 797 4. Missoula River Development............ 797 5. Big Fork Development.............. 802 $ IV. Present Capacity of Power Developments....... 802 V. Transmission System...............: . 802 VI. Character of Load. 1. Lighting and Small Power Uses........... 804 2. Street Railways ................ 804 3. Mining................... 804 4. Railroads.................... 808 5. Irrigation................... 810 VII. Operation of System................. 812 VIII. Increase in Use of Power............... 811 IX. New Power Developments............... 814 X. Undeveloped Powers................. 815 It is estimated that the total stationary power now used in the United States. steam. water and gas. is probably over 30.000.000 h. p. The total developed water power is about 6.000.000 h. p. The water power in the United States now economically capable of development probably exceeds 25.000.000 h. p. The total developed and undeveloped power is

Jan 1, 1914

By R. A. Pallanch

PROBABLY one of the most perplexing problems with which a mill operator contends is the proper evaluation of his mill results. True, he accurately determines his recoveries of metals and grades of products monthly, weekly, and often daily. These figures do not of themselves directly translate to mill economics. When one figure is unusually good there may be an offsetting circumstance. The advantage of high lead or zinc concentrate grade may be offset by poorer recovery; high lead recovery may be offset by poorer zinc recovery, or vice versa; and so on. Besides, grades or recoveries may not of themselves mean more than a reflection of the grade and character of the ore during the period under study. What the operator sorely needs is some one measuring stick that tells him when he has achieved his greatest return, regardless of grades or recoveries-for if he knows his methods and practices are yielding the optimum return he need no longer concern himself with the assays of products and tailings, or the corresponding distribution of metal values. At first blush it would appear that the obvious answer to this is the actual money return to the mill. Paradoxical as it may seem, however, money return does not make a dependable yardstick any more than do grades and recoveries, as ore conditions would vary enough to bring about greater money return during periods when the actual metallurgical work is not as good. The mill operator, of course, should always aim for the greatest return on the ore, once it is in the mill bins, with proper attention always to mill treatment cost. The need of a proper yardstick becomes more imperative with the increasing complexity of the problem. In the case of a simple, single-product operation on a fairly uniform ore, in which only one metal is of significant importance, the need is not great, as grade and recovery pretty well tell their own story. At the other extreme is the operation that makes three or four separate marketable products from a complex mixture of heterogeneous ores that vary tremendously in individual metal contents and ratios, degree of oxidation, and other characteristics, and in which gold, silver, copper, lead and zinc are all significant values. ECONOMIC RECOVERY The first attempt at obtaining a proper single yardstick for a fairly complex ore with which I am familiar is the use of the "Economic Recovery" term at the leadzinc flotation mill of the Sunnyside Mining and Milling Co., Eureka, Colorado. This method had been applied there early in Sunnyside flotation-mill history (not later than 1920) and credit for the innovation I believe belongs to Messrs. Kuryla and Marquand. The term "Economic Re-

Jan 1, 1947

By Donald H. Yardley, A. Aly Selim

Abstract-An economic simulation model was developed to predict the amount of copper recovered from copper oxide deposits, and the cost of producing it as a function of the deposit parameters. The economic simulation model includes programs for fragmentation design and cost, copper extraction, solution distribution and recovery, effluent solution cutoff grade, and financial analysis. Cost and price indices were also developed to evaluate the economic feasibility of in situ leaching operations as a function of their starting date. Application of the models to various hypothetical properties having the same area and different ore thickness shows that the effluent solution cutoff grade does not vary with the ore thickness nor with its grade. The percent of copper recovery is, however, shown to increase with the increase in the ore thickness and is independent of the ore grade. It is also shown that while the profit per unit of extracted copper increases with the increase in ore grade or ore thickness, the rate of return on total investment does not show any correlation.

Jan 1, 1978

By A. S. Adams

A GLANCE at the list of papers1 that have been published since 1920 on the general subject of flotation suggests the variety of ideas that exist regarding the underlying cause of the phenomenon. Among these ideas, we find several coherent theories, but none that adequately and completely explain the phenomenon. Ralston2 and Bains3 suggested an electrical theory which has to do with the attachment of mineral particles to a bubble by the attraction of unlike electrical charges. This theory has its root in the fact that a bubble of air in pure water is electrified in such a way that the surface is negatively charged while the body of the water is positively charged. This result, which was first discussed by Helmholtz, also obtains when the water contains anything except a high concentration of hydrogen ions, or ions which are trivalent or tetravalent. The theory also holds that the mineral particles have positive charges on their surfaces, and so there is attachment between bubble surface and mineral particles by the old law of electrostatics, which states that unlike charges attract.

Jan 1, 1928

By J. W. Axelson

CRUSHING has always been a major operation in the chemical and metallurgical industries, yet little is known about the theory of crushing, and today, the design of crushers is still based almost entirely on empirical knowledge and accumulated practical experience. In view of the increasing national need for the economic working of poorer grades of ores, the lack of a fundamental under- standing of this unit operation hardly presents a satisfactory situation. Basic investigations of crushing have been concerned mainly with three phases of the problem, 1-the mechanism of the fracture process itself, 2- the particle size distribution of the crushed product, and 3-the relationship between the energy input and the amount of new surface produced. Probably adequate information on these phases will be required for a comprehensive understanding of the process of crushing. A bibliography covering these phases will be given as well as a review of the work done in recent years at the University of Minnesota on the relationship between the energy input for crushing and the amount of new surface produced.

Jan 12, 1951

By Robert S. Nichols

Fording Coal Limited's mine in the Rocky Mountains near Elkford, B.C. has produced 21.8 million clean tonnes of metallurgical coal from 1971 to 1980, inclusive. This production has come from several pit areas and required the removal of 149.1 million bank cubic meters of waste rock and overburden by truck-shovel and dragline operations. Waste dumps from 30m to 200m in height have been successfully constructed on natural slopes, generally between 10° and 26°. Design considerations for the dumps include foundation and soil conditions, natural slope angles and containment of weak overburden or rehandle materials. Dump control is maintained by monitoring the crest and the face of an active dump area. Crest movement is measured by extensometers locally termed "Spoil Monitors". When crest movement rates progressively increase above normal, dumping operations are temporarily relocated. Some unstable conditions and mass failures have occurred as the result of natural foundation slopes being in excess of 26°, failure of weak water saturated foundation soils or weak material being placed on the dump.

Jan 1, 1983

By H. O. Hofman

With the exception of the exhaustive paper on the Father de Smet mill, by its designer, Mr. A. J. Bowie, Jr. (Bans., x. 87), nothing, so far as the writer is aware, has as yet appeared on the stamp-mills of the Black Hills of Dakota, although they have been steady producers for the last ten years. Within the small area of about 6000 by 1600 feet, $2,271,341.14 was produced in 1887† from rock averaging $4 per ton in free gold. I. The Ores. Character of the Ores.—The gold of the district is found in quartz and pyrites finely distributed through vast bodies of mica- and amphibole-schists, argillites and phyllites, and also impregnating the schists themselves. The " Belt," embracing the section of Lead City, Terraville and Central City, is the only part worked at present. The principal associated mineral is iron pyrites, with some arsenopyrite and chalcopyrite, garnet and asbestos. The ores from open cuts and upper levels are more free-milling. than those from underground workings below water-line. Hence

Jan 1, 1889

By R. D. Nelson

The purpose of this technical note is to briefly present some data on a phenomenon—recrystallization with concurrent deformation—that has been found to occur in a plutonium. This phenomenon is unusual because a plutonium is considered brittle, not easily deformed, and not easily recrystallized; the a phase is simple monoclinic having 8 atoms per unit cell and it is stable below about 115°C. The properties of the recrystallized metal were different from the as-cast metal. Even though a plutonium is difficult to deform, Ianniello successfully rolled it' and he also observed some recrystallization at 120°C.2 Pavlick and Hanson3 detected some recovery at 109°C but they observed no recrystallization. Gardner4 and Bronisz5 studied the compression properties up to 100°C but they did not report having seen recrystallization. In the present deformation studies of electrorefined plutonium pronounced recrystallization took place concurrently with plastic deformation in compression between 24" and 115°C. The metal contained less than 300 ppm total impurities with the major impurities being 100 ppm Am, 30 ppm C, 40 ppm W, and 25 ppm U; all other impurities totaled less than 100 ppm. The compression specimens were machined to dimensions of 1.2 cm long and 0.8 cm diam from as-cast rods having a density of 19.65 g per cu cm. They were heated to the test temperature in a high-temperature silicone fluid that was evacuated to 10-4 Torr. With this procedure the specimens oxidized a negligible amount, and the temperature was maintained within ±0.2°C for times up to 3 weeks. Deformation and recrystallization

Jan 1, 1969

By William J. Douglas, Jack T. Urie, Randall D. Metz

Production and financial planning for a new underground mine requires the coordination of equipment and coal reserves in a manner which assures that resources are utilized efficiently in achieving the target mine production. It is necessary to establish the productions which are attainable at the section level during different mining operations (advance, retreat, development) and under different mining conditions (roof, seam height, resource quality). It is also necessary to identify the interactions between production plans and ventilation equipment So that operations can be carried out without disruptions caused by inadequate ventilation. A set of computer models has been applied in planning a number of new coal, oil shale, and phosphate mines. A critical path production model, CPMINE, was used to determine face production levels for different cut sequences and seam heights, taking into account machine performance characteristics and operational availabilities under these varying conditions. The results formed a production data base for use in the mine sequencing model, MPLAN. This model processes each of the segments of a user-defined mine sequence network (strategy tree) taking into account the equipment available for mining operations and the previously determined production scheme devised by the mining engineer. Mine ventilation was analyzed with an expanded version of the Penn State MVS Ventilation model to determine fan and ventilation shaft requirements for supporting alternative production strategies. The MCOM mine cost analysis model has been applied to evaluate the economic performance of mining alternatives. The results of these studies were used to make decisions relating to equipment selection and acquisition schedules for both room-and-pillar and longwall mining systems. The approach and procedures which were used during these studies are described.

Jan 1, 1983

By Will B. Jamison

It is a fact that the most serious safety problems encountered in US underground coal mines are related to roof-bolting operations. It is also true that roof bolting is usually the operation which limits coal production from a mine section. There has been a recent focus on activity involving roof bolting research, development, and new ideas as people concerned about mine worker safety and productivity realize that significant progress can be made in these areas, even with equipment presently available.

Jan 7, 1977

By J. B. Stubbins, D. F. Coates, K. L. McRorie

Twenty-two pit slides that occurred in two Canadian open pit mining properties are analyzed. Information on the results of laboratory tests of the rocks and a brief description of the geological environment are also presented. One deduction from the study is that slides seem to be predictable by using established theory. This corroboration indicates that, contrary to normal mining practice, the appropriate slope angle should vary with the height of the wall. In addition, if the general ground water level around an open pit can be reduced, the appropriate slope angles of the walls could then be increased by a determinable amount. The ultimate objective of these investigations is to determine the relationship between the percentage probability of failure of any slope designed with specific strength paraheters. With this relationship it would then be possible to determine optimum slope angles. Because of changes in various economic factors, open pits are now being mined to much greater depths than previously. The need to keep stripping ratios low without endanrrerine.-- lives and equipment provides a strong incentive to determine the maximum practicable wall slopes. Applied research work is currently being conducted to establish the methods for analyzing optimum slopes.

Jan 1, 1963

By L. Adler

A relatively simple and effective technique is proposed to deal with the failure of geologic masses containing weakness planes. This technique, termed irextended" rupture envelope, provides a means to clearly distinguish rock and soil from fractured rock and, on a theoretical level, considers a matrix-inclusion system. It may also constitute the link between Mohr's and Griffith's failure theories. Included in the article are five sample problems concerning site location, structural design, strengthening the plane of weakness, changing the magnitudes of major and minor principal stresses and changing the orientations of major and minor principal stresses. Engineers trying to solve design problems in rock and soil mechanics have often assumed an iso-tropic and homogeneous medium. For naturally occurring geologic masses this assumption has always been viewed with regret. The following analysis which deals with the effects of plane anisotropy on failure presents a solution to this. The planes of weakness are joints, faults, bedding planes, fracture and cleavage (natural and induced), foliation and schistosity. The physical properties of these weakness planes include an undulating surface, frictional resistance, discontinuous extent, filling material, tightness and presence of water to cause a hydrostatic pore pressure. All of these properties relating to failure can be summarized in Mohr's rupture envelope for the plane of weakness. This, along with the geometrical orientation, strike and dip, of the plane of weakness produces what is termed an irextended" rupture envelope. MOHR'S STRESS CIRCLE AND RUPTURE ENVELOPE The significant features of these concepts are listed below.' 1) A point on the u - r coordinate plane represents the normal and tangential stress components on a reference area in the material. This area can have any orientation. (Fig. la)

Jan 1, 1963

By C. D. Woodward

ThE subject of elcctric signals for the despatching of mining cagey through shafts has received cousiderable attention recently from various mining companies. The Anaconda Copper Mining Co. has found it necessary to develop a system that is rcliable, safe and simple in operation, and easy to repair. The movement of all mine cages or skips is under the direction of a station tender, who rides on the cages when men or supplies are being lowered or raised; when ore is hoisted, he is stationed at a skip pocket for loading and despatching the skips. For the station tender's use, two signal systems are installed in cach hoisting compartment, and he is the only employee authorized to use them. One system is known as the "AC " or station bells, as it is operated from the 110-volt, 60-cycle, power service; the other system, called the "DC" or shaft bells, takes its energy from closed-circuit primary batteries. As a supplemcnt to the two main signals, a buzzer system is installed The general arrangement is similar to the main signal, except that there is a mine buzzer at each station. When a signal switch connected into the buzzer system is pulled down, all buzzers arc operated, thus notifying the station tender that he is wanted at seine particular level. Placed on the station posts, and within easy reach of the men on the cages are the signal pull switches for the main signals. The station, or "AC," pull switches are furnished with a short rope as shown in Fig. I, while the shaft, or "DC," pull switches are equipped with ropes that extend down the shaft past the next station. To avoid all confusion in the use of the three signal systems, a standard arrangement has been adopted in all mines for the location of the pull switches. Fig 2 illustrates the position of the pull switch at the various mine stations for the main signal systems, but it does not show the buzzer pull switch; this is fixed to the roof timbers about 25 ft. back from the shaft. If the skip pockets are a considerable distance below the station, a pull switch for each main shaft compartment is connected to the "AC" system and placed at this point. However, if the distance is short, a light cord is attached to the station pull switches and dropped down to the skip pocket.

Jan 1, 1923

By C. D. Woodward

ThE subject of elcctric signals for the despatching of mining cagey through shafts has received cousiderable attention recently from various mining companies. The Anaconda Copper Mining Co. has found it necessary to develop a system that is rcliable, safe and simple in operation, and easy to repair. The movement of all mine cages or skips is under the direction of a station tender, who rides on the cages when men or supplies are being lowered or raised; when ore is hoisted, he is stationed at a skip pocket for loading and despatching the skips. For the station tender's use, two signal systems are installed in cach hoisting compartment, and he is the only employee authorized to use them. One system is known as the "AC " or station bells, as it is operated from the 110-volt, 60-cycle, power service; the other system, called the "DC" or shaft bells, takes its energy from closed-circuit primary batteries. As a supplemcnt to the two main signals, a buzzer system is installed The general arrangement is similar to the main signal, except that there is a mine buzzer at each station. When a signal switch connected into the buzzer system is pulled down, all buzzers arc operated, thus notifying the station tender that he is wanted at seine particular level. Placed on the station posts, and within easy reach of the men on the cages are the signal pull switches for the main signals. The station, or "AC," pull switches are furnished with a short rope as shown in Fig. I, while the shaft, or "DC," pull switches are equipped with ropes that extend down the shaft past the next station. To avoid all confusion in the use of the three signal systems, a standard arrangement has been adopted in all mines for the location of the pull switches. Fig 2 illustrates the position of the pull switch at the various mine stations for the main signal systems, but it does not show the buzzer pull switch; this is fixed to the roof timbers about 25 ft. back from the shaft. If the skip pockets are a considerable distance below the station, a pull switch for each main shaft compartment is connected to the "AC" system and placed at this point. However, if the distance is short, a light cord is attached to the station pull switches and dropped down to the skip pocket.

Jan 1, 1923

By D. Grosse

At the beginning of the 1960's, the Hannoversche Portland-Cementfabrik A. G. needed to open a new quarry. The land on which this quarry was to be developed was completely flat and separated from the existing quarry by a navigable canal. The area had been exploration-drilled previously, so that enough reliable data on the chemical properties of the deposit were available. From the geologic point of view, the deposit under a very moist surface belongs to the Turon (Upper Chalk) formation, soft on the surface and medium to very hard farther down. Between the 15% sloping banks of chalk (with a calcium carbonate content of 75 to 90% and running from west to east), there are numerous beds, up to 3 m deep, which are rich in alumina and iron oxide but contain only 50 to 60% CaCO3. In the old quarry-worked conventionally by deep-hole drilling, a 2-cu-m shovel, and 900-mm track with 6-cu-m dump cars-an adequate and modern crushing plant was available. The plant crushed the moist material (11 to 13% H2O content) down to 0 to 50 mm. INSTALLATION OF ORIGINAL MOBILE CRUSHER It was decided to employ a mobile crushing unit in the new quarry; the moist and soft ground did not permit the use of heavy trucks for transporting the material, and a road network would have entailed a large investment. The use of a rail system was eliminated from the beginning, since the ground would be very uneven after the quarry was developed. At that time only one prototype of a crawler-mounted mobile crushing unit existed. This unit was operating in a nearby works as a primary crusher. A similar, slightly improved machine (Fig. 1) was purchased

Jan 1, 1969