Search Documents

By J. W. Fuller

DURING the last 20 years, experimenters have sought to utilize pulverized coal in boiler plants, but refractory and slag troubles have usually overbalanced any, gains in efficiency that were obtained. These troubles were caused largely by lack of knowledge of the proper methods of coal preparation and lack of a furnace design that would be adaptable to pulverized-coal firing. When this information was obtained the results were so much more satisfactory that within the last 5 years approximately, 80,000 boiler hp. have been installed in plants ranging from 1000 to 20,000 boiler hp. rated capacity, which are operating at an average of 174 per cent. of rating. The first commercial installation for burning pulverized coal under boilers was made at the Parsons shops of the M. K. & T. railroad in 1916. Of eight 250-hp. water-tube boilers thus fitted, six were operated continuously for 3 yr., when oil was obtained at such a low price as to warrant its use. Since then, this plant has been operating alternately on pulverized coal and oil, depending on prevailing prices. Recently gas has been discovered within 20 mi. of this plant, so that this fuel may also be used. No change in furnace design was made when changing from pulverized coal to oil or gas firing. One of the principal advantages of this method of firing is its ability to utilize, with maximum efficiency, all kinds of coal, irrespective of quality or physical characteristics. In fact, quite a number of the present pulverized-coal installations were made for the purpose of utilizing coal that could not be marketed or used in any other way. The Pacific, Coast Coal Co., at Black Diamond, Wash., formerly hand fired the boilers, using approximately 125 tons of prepared steam-size coal daily. The Black Diamond steam coal is the best quality of coal for steaming purposes mined in that section of the country, and there is a market for all that can be produced. By installing a pulverizing plant, it was possible to substitute coal of a size and quality that had no commercial value, so that 125 tons daily of the best steam coal formerly used at the mines is now marketed.

Jan 12, 1921

By C. P. Sandberg

C. P. Sandberg, London, Eng. 1 think we should all be grateful to the Pennsylvania Railroad Company, and to their chemist, Dr. Dudley, for spending so much time and money in order to solve an important question; nor are me less indebted to the public spirit which leads them to impart tlie experience thus gained. In Europe nothing similar has hitherto been done, either by a company or by any private individual. In England the great railway companies employ their engineers in other ways, and do not keep a chemist or specialist to study rails; bat even if they did they would probably not publish the results. The chief professional engineers are so occupied with their private practice of railroad construction generally, that they cannot be expected to devote their time and energies to so special a question. The German Railway Union has, in my opinion, missed the real object of its elaborate researches by falling into the error of specifying costly, impracticable tests for rails—tests at the same time which do not infallibly expose the impurities that may be in the rails under examination. There has, therefore, been nothing done on this side of the Atlantic in the way of exhaustive study to determine the best composition for steel rails. America should consequently have full credit for the enlightened example which she has set. I wish, however, to make a few remarks on Dr. Dudley's second paper,—& paper which follows very much upan the same lines of argument as the first red three years ago, upon which I have previously touched in my pabr on the same subject read at the meeting in August last. If Dr. Dudley had discovered a new metal he could hardly, I think, have taken wore pains to prove that he was correct in his first formula for the best chemical colnposition of steel rails. But I hare seen so much done in the way of proof by experiment that I am inclined to think that almost anything can be proved by experiments and by satnples. If Dr. Dudley would only give up his formula, which would not suit any country—not even America—

Jan 1, 1881

By B. H. Dunshee

This paper is not intended to be a technical discussion of square-set framing as used in mines, but merely a short description of the different kinds of framing that have been used in the Butte mines, and what has been decided upon, after years of practical experience, as being the best, taking into consideration the physical condition of the veins and country rock, and also the supply of timber available for mining purposes. Butte is, essentially, a square-set district. Virginia City, Nev., was the first mining camp to use this method of timbering, and to Philip Deidesheimer, who went to the Ophir mine in 1860, is given the credit of solving the problem of square-set framing, where large bodies of ore were stoped and the timbers were supposed to hold the ground from caving without any filling. That he did his work well is shown by the fact that the main features of his framing are in use to-day. In the Butte mines the conditions are such that this method of timbering is generally used. We do not, of course, depend upon the timbers any more than is necessary. The worked-out stopes are filled with waste rock as close behind the miners as possible and not interfere with mining operations. The waste rock is obtained from development work on the different levels or from the surface. In the earlier days of mining in Butte there were numerous independent companies and naturally there were different ideas as to the best way to frame the square sets, although the general features were the same. Timber was abundant for mining purposes and the common practice was to use sawed lumber, generally 10 by 10 in. or 12 by 12 in. square. Some of the mines used for girts 6 by 10 in. or 8 by 12 in. timber, depending upon whether they used 10-in. square or 12-in. square timber for posts and caps. This avoided the necessity of framiug the ends of the girts, and also required less timber for the

Jan 1, 1914

C. P. Sandberg, London, Eng. 1 think we should all be grateful to the Pennsylvania Railroad Company, and to their chemist, Dr. Dudley, for spending so much time and money in order to solve an important question; nor are me less indebted to the public spirit which leads them to impart tlie experience thus gained. In Europe nothing similar has hitherto been done, either by a company or by any private individual. In England the great railway companies employ their engineers in other ways, and do not keep a chemist or specialist to study rails; bat even if they did they would probably not publish the results. The chief professional engineers are so occupied with their private practice of railroad construction generally, that they cannot be expected to devote their time and energies to so special a question. The German Railway Union has, in my opinion, missed the real object of its elaborate researches by falling into the error of specifying costly, impracticable tests for rails—tests at the same time which do not infallibly expose the impurities that may be in the rails under examination. There has, therefore, been nothing done on this side of the Atlantic in the way of exhaustive study to determine the best composition for steel rails. America should consequently have full credit for the enlightened example which she has set. I wish, however, to make a few remarks on Dr. Dudley's second paper,—& paper which follows very much upan the same lines of argument as the first red three years ago, upon which I have previously touched in my pabr on the same subject read at the meeting in August last. If Dr. Dudley had discovered a new metal he could hardly, I think, have taken wore pains to prove that he was correct in his first formula for the best chemical colnposition of steel rails. But I hare seen so much done in the way of proof by experiment that I am inclined to think that almost anything can be proved by experiments and by satnples. If Dr. Dudley would only give up his formula, which would not suit any country—not even America—

Jan 1, 1881

One of the most frequently asked questions at the feasibility study stage of a project is, æhow big can one go?Æ This important question effects costing and efficiency of metallurgical equipment, the real estate required and the operating plant strategy.The presentation covers both engineering and process considerations and explains the limits that exist today and explores future trends.The paper is specific about large slurry application usually found in gold applications; however, it could apply to silver and uranium or other dense media leach duties.Agitator drive sizes are examined as well as process risks associated with large tank agitation. New technology has increased the maximum tank size and designers are now experienced in tank volumes in excess of 5000 m3. Tanks of 6000 m3 have been agitated and 10 000 m3 tanks are within present engineering know-how and scale-up.Fabrication techniques for shaft and impeller designs exceed the existing standards and new specifications will be needed to cover large mixer design. The paper covers certain aspects of mechanical design and proposes alternative standards that are more appropriate. Process considerations such as fluid natural frequency as well as typical superficial velocities for efficient operations are examined. Scale-up techniques based on existing and new technology are also examined to ensure a successful installation.The presentation therefore covers the majority of large mixer design questions that are frequently asked.

Jan 1, 2006

By Chengyi Ding, Xuewei Lv, Changyang Ji, Rende Zhang, Xiangwei Zheng

The fraction of liquid phase in sintered ore can be the most important factor to determine the sinter quality and yield in sintering process. The generation ability of liquid phase for mixture of iron ore powders is determined by basicity, roasting time, roasting temperature and chemical composition of iron ores. Five different iron ores were selected in this study and the dried powders of iron ore and CaO reagent (<200 mesh) were homogeneously mixed together at their required proportions, then 15g of the mixture was pressed under a pressure of 20MPa to make a cylindrical sample with a diameter of 20mm. The sintering temperature in this study was kept at 1280℃, the gas phase is air, the holding time was varied with its three levels of 5min,10min and 15min. After that, the sample was cooled under room temperature in the air, and the cooled sample was analyzed by using zeiss optical microscope. The mineral phase compositions were quantitatively determined with an open source image processing software, Image J whicn can calculate the fraction of liquid phase. Besides, the study on how to estimate the sintering behavior of the raw materials in different conditions by the theoretical calculation is of vital importance, and the development of this will greatly improve the sintering production. Factsage will be used to calculate the liquid phases formulation during the sintering. Comparing the experimental results and the theoretical calculation shows that the mass of liquid phase increases with increasing basicity during the sintering, besides, the mass of calcium ferrite increases with increasing basicity. The generation ability of liquid phase of iron ores can be predicted through the experiment verification.

Jan 1, 2015

By William J. Miles

Bentonite Corporation decided to pursue ISO-9002 Registration for our bentonite production for many reasons. We wanted to improve our current Quality System to encompass all business aspects, not just Quality Assurance. We wanted this system to build supplier/customer confidence and provide our customers with all the services that they needed for their business functions: such as Quality Assurance for their needs; appropriate shipping and delivery; appropriate billing; and appropriate sales, technical and management support of our product. These objectives of our Quality System are addressed by the ISO 9000 clauses and requirements. There were additional reasons and expectations for implementing an ISO 9000 Quality System. ISO 9000 registration would develop and aid international sales since the ISO system is a basic requirement in many parts of the world such as Europe and the Far East. It would bring acceptance of bentonite products by new customers and markets Another objective was to develop better trained employees. We hoped that the ISO Quality System would help us reduce costly non-conformances and reduce overall production and operating costs. We hoped to achieve ISO 900 registration before our major customers required it. For example, our major market is use of bentonite as a binder in foundry mold sand systems. The foundries in North America primarily service the automobile manufacturers who have individual Quality System requirements that are being merged with ISO 9000 Standards. As the foundries addressed the automobile manufacturer?s needs, Bentonite Corporation received numerous inquiries and surveys of our Quality System and its conformance with ISO 9000 Standards. Eventually, ISO 9000 Registration will become a requirement to directly or indirectly service this market.

Jan 1, 1996

By Sheldon P. Wimpfen, Ralph H. Sweefser

FOR centuries the pumping of water has been one of the chief problems to be overcome by the persistent men who win the mineral wealth of the world. Profitable operations have often been forced to suspend activities as the mine penetrated well below the water table or when sudden rushes of water were encountered. To operate below the local water level requires continuous pumping equal in volume to the amount of water flow¬ing into the mine workings. Often the water to be removed exceeds the tonnage of valuable material produced. To be above local water level is a valuable asset. Modern mining practice permits nothing short of the extraction of the last pound of profitable ore from a mineral deposit. In the days before the development of mechanical and electrical power as we know it today. water in any quantity was a major

Jan 1, 1948

By J. Lux, B. Clermont

Magotteaux, with the co-operation of Anglo Platinum, has erected a fully instrumented pilot plant at Frank concentrator, which is being used to study the influence of a variety of grinding parameters. This paper will discuss only the influence of mill speed and pulp density on secondary stage grinding. A Ø0.82 x1 m open circuit mill was used with reclaimed Merensky tailings as feed. The conclusions apply to this pilot plant but further investigation needs to be done to verify whether the same trends will be applicable to a large industrial-scale mill.

Jan 1, 2004

By Stanton L. Tainter

"INTRODUCTION Molybdenite, the only common mineral and ore of molybdenum, occurs wide¬-spread but is concentrated as the main ore mineral in commercial quantities in only a few known deposits. Consequently, the Government sought additional sources of the minerals as a precaution against the possible shortage of moylbdenm for war uses. Upon request by the War Production Board, the New Year’s Eve and Esperanza properties of the Amargosa Molybdenum & Copper Corp. were investigated by the Geological Survey 3/ and the bureau of Mines 4/. The Survey appraised the mineral potentialities of the deposit and prepared topographic and geologic maps, and the Bureau made a preliminary engineering examination. The deposits were previously examined by W. J. Vanderwilt, consulting engineer. It was largely due to his recommendations that interest was stimulated in the deposits.Development on the New Year’s Eve deposit indicated a small tonnage of sub marginal ore. There was little development at the Esperanza, but surface examination revealed a large volume of rock containing a little molybdenite and a trace of copper in the oxidized outcrops. Some molybdic oxide was noted suggesting that some molybdenite might have been leached from the oxidized outcrops and that the molybdenite content in the sulfide zone might be higher."

Feb 1, 1947

By Werner Langguth

The modern process and plant for the precipitation of gold from chlorine solutions, by sulphurous acid gas and hydrogen sulphide, differ materially from the older methods of precipitating with sulphate of iron. The chemical process and its applicability, as carried out in the Golden Reward chlorination-works at Deadwood, S. D., was described and discussed in the Engineering and Mining Journal, of New York, for February 14, and March 21, 1891. I purpose to give, in this paper, the details of construction from a general standpoint—the particular arrangement, most suitable to each case, depending, of course, upon local conditions. The accompanying sketch shows the arrangement. The plant consists of a wooden, lead-lined tank, in which the chlorine solution is precipitated; apparatus for the production of the precipitants, sulphurous acid and hydrogen sulphide; and a pressure-tank and filter-press for the collection and filtration of the precipitated gold-sulphides. These parts and arrangements are, in general, those which I employed in the Deadwood chlorinationworks, and which have proved practically successful, more than $100,000 worth of gold having been already precipitated by this method. In the construction of the generator and pressure-tank I have made, however, a few slight changes. 1. The Precipitating-Tank. The exact dimensions of this tank are not of much importance. A horizontal area of 10 x 12 feet and a height of 12 feet, holding about 7000 gallons of solution, is a good size. As the amount of attention and care required to precipitate the solution in a precipitatingtank is independent of the size of the vessel, there is economy in tanks of large capacity. Square tanks are more advantageous than round ones, because they need less floor-space, and at the same time are cheaper in construction. These tanks are made of common 2inch pine boards and 12 x 12-inch timber. They are well-bolted,

Jan 1, 1893

By Ker-Chang Hsieh

Four three-phase equilibria and one two-phase equilibrium in the FeNi- S-0 quaternary system in the vicinity of 1023 K and Pso2 = 1 atm were studied using the following emf cell 2 Pt,o2 (air)Zr02 .CaO/Pso2 = 1 atm, mixture of phases, Au The four three-phase equilibria are sp + (Fe,Ni )S + Ni 3s2, sp + Ni 3s2 + NiO, sp + NiO + N1S04 and Fe2 o3 + sp + (Fe,NOS04 -Y:he two-phase equilibrium is sp + (Fe,Ni)S. The two-.phase equilibrium was measured by using mixtures containing a major portion of one phase and a minor portion of the other. The results are presented in terms of oxygen potential as a function of YNi = nNi/(nN1+nFe) at constant temperature and pso2 = 1 atm. The stability diagram was also calculated using appropriate thermodynamic models for all the pertinent phases. The calculated diagram is in accord with the measured ones.

Jan 1, 1985

By L. C. IlsLey

"Nearly every piece of electrical equipment used in mines ""breathes."" In other words, motors, controllers, rheostats, switches, and other similar equipment, even though encased in seemingly tight compartments, breathe in the atmosphere that surrounds them.As the apparatus is used, the temperature of metallic parts is changed generally in positive direction through the heat by friction and the heat due to the electric current. When the apparatus is idle it gradually cools down to the temperature of the surrounding atmosphere.This increase of temperature during operation and return to normal temperature when operation stops alternately raises and lowers the temperature of the atmosphere within the compartments which, in strict accordance with Charles' law -will expand or contract in proportion to any given temperature change.As compartments are not gas-tight, such expansion and contraction will force the atmosphere out of the compartment =on expansion and suck the surround¬ing atmosphere into the compartment during contraction, hence the term ""breathing.""Investigators2 of explosion-proof equipment have recognized that such an interchange would take place and have designed their equipment to safeguard possible explosions within the compartments."

Jun 1, 1927

By Louis C. Brichta

The rapid depletion of known deposits of high-grade ore and the need for development of additional reserves, together with increased interest in open-pit mining of low-grade zinc-lead ores in the Tri-State District, led the Bureau of Mines to examine likely mining sites. Underground operations failed to remove all of the ore in a number of areas, and it appeared possible that some of them might be reworked successfully by low-cost open-pit methods. The South Carthage or Hull tract in Jasper County, Mo., was selected by Bureau engineers as favorable for the development of an open-pit mine.

Jan 1, 1949

By Z. C. Shen

As core part of flotation column, aerator has been always priority research. A new type of porous aerator made of stainless sintered microcellular material is designed , which diameter is between 20µm to 40µm. High bubble surface area flux is obtained at low air pressure 20kPa by this type of aerator in water. In order to extend its applied range ,experiments were carried out in alkali slurry (pH=12) , resulting with porous aerator clogged after working 20 days . Sampling the cross-section of aerator detected by microscope and X-ray diffraction ,the reason clogging was found. Then plugging aerator was reactivated after putting it in acidic liquor treated by ultrasonic for about ten minutes. On-line aerator maintenance can be done in no down time , and it can be repetitive-used after recovered ,so reduced capital costs.

Jan 1, 2014

By R. V. Ramani, C. B. Manula, A. Owili-Eger

MINE PROTOTYPE The prototype chosen for application demonstration is from Kingery (1960). The mine and the ventilation plan is presented in Figure 11. A new coal mine is projected with entrance by slope 1,500 feet long. Nine train entries will be standard for development, five as intake and four as return. One return shaft is planned near the slope bottom. The slope will have an area of 150 square feet and a perimeter of 55 feet. The return shaft will be circular with a diameter of 18 feet and will be 500 feet deep. Two hundred feet of the shaft and 500 feet of the slope will be concrete lined. Will it be possible to operate five units per shift with amount of air at each unit not less than 25,000 cfm? Additionally, a shop at the slope bottom will require 10,000 cfm. The problem is completely worked out using standard ventilation formulas and simple manual calculations in the above reference and is reproduced here in Appendix II for ready reference. APPLICATION In this manual, four different applications of the PSU/MVS are outlined. An article by Stefanko et al (1972), outlines how one can move from a mine map to a network for the generation of computer input. Attention is drawn to Figure 12, which is the network line diagram of the mine ventilation system in Figure 11. Note that every roadway junction has been numbered. The dotted lines represent leakage paths and the letter &apos;R&apos; on a branch denotes that the split is regulated for the quantity shown. For example, there is a leakage

Jan 1, 1975

The sudden. explosion of relatively inexpensive digital process control computers has accelerated interest in the possibilities of economic savings by their use. In particular the metalliferous industries have shown that they are willing and capable 6f grasping this new technology and putting it to good use. These industries have a number of problems which need special attention. In many cases the process is difficult to measure and a reaction is often controlled by measuring a secondary effect, computing its relationship to the reaction and then applying the necessary corrective action. This creates problems in building the process model, designing the computer to process interface and in the subsequent system development. Environmentally the metalliferous industries create conditions which severely test sophisticated electronic equipment. Care taken in locating and housing this equipment is a major factor in ensuring reliability in Operation.

Jan 1, 1977

By S. Shapiro, G. Krauss

The strutural and cr~stallo~aphic features of the plates of austenite produced by the martensite to aus-tenite or reverse martensitic tramformation have been determined in an Fe-33 wt pct Ni alloy. Micro-focus X-ray techniques and single-surface trace analysis 072 bulk samples yielded two distinct habit planes, (0.174, 0.309, 0.~35)~ and (0.375, 0.545, 0.749jM. The former plane uas the one predorninantly observed and its existence was verified by transn~ission electron microscopy. The orientation relation-ship between the reversed austenite and the parent martensite was approximately the same as the Nishiyamna and other relationships reported for the direct tramformation. Replica and thin-joil obser-vations show that both high densities of tangled dis-locations and occasional twins constitute the fine structure of the reversed austenite. Application of the phenomenological theory to a variant of the predominant habit plane defines an irrational plane and direction for the second shear in accordance with the comnplexity of the fine structure. The shear accompanying the reverse martensitic transformation is at least 0.51, the maximnum value of- the tangent oJ the tilt angle measured on surface replicas. A mechanism relating the fine transformation twins in martensite to the nucleation of reversed austenite of the predominant habit is proposed. The reversal of Fe-Ni martensite takes place both at the edges of martensite plates and in a piecewise fashion within them.&apos; The shear-type nature of the reverse transformation is verified by the surface relief which accompanies both edge-type reversal2 and the fragmentation of plates of martensite&apos; as a result of rapid heating above the A, (austenite start temperature). The orientation relationship between the edge-type reversal product and the parent martensite, as determined by transmission electron microscopy, is reported to be within 4 deg of either the Kurdyumov-Sachs or Nishiyama relationships,&apos; but there is no work at present in the literature relating to the crystallography of the platelike reversed austenite. The fine structure of reversed austenite after heating to 50°C above the Af is reported4 to be composed primarily of tangled and jogged dislocations in concentrations up to 10" per sq cm. A replica investigation of partially reversed Fe-Ni martensites5 corroborates the increase in dislocation density following reversal and presents indications of other possible modes of fine structure. This paper reports on an investigation performed to examine in detail the morphology and crystallography of the plates of reversed austenite and the shear which accompanies their formation in a matrix of Fe-Ni martensite. EXPERIMENTAL PROCEDURE Discs of a high-purity Fe-32.9 wt pct Ni single crystal served as the starting material. The single crystal had been produced in the course of an earlier investigation6 and the carbon content was determined at the time to be 0.006 wt pct. The M,, and the A,, were respectively -120" and 300°C. Partial transformation to martensite was performed at -125°C and reversal of some of the martensite was accomplished by heating in the temperature range 340" to 355°C. Most samples were heated to the reversal temperature by immersion&apos; in a salt bath for 2 min. For surface-relief studies some polished and etched Samples were heated in a tube furnace for ten min in a hydrogen atmosphere maintained over the samples throughout the heating and cooling cycles. Samples were prepared for metallographic examination by electropolishing and etching with an HC1-HNOs-H20 et~hant.~ On one of the surface-relief samples two sets of fiducial scratches were placed on the etched sample by drawing it over a slurry of 0.06 p alumina on a "microclothJ&apos;. The orientations of individual plates of martensite were determined by X-ray analysis. A Rigaku-Denki microbeam X-ray generator in conjunction with a Micro-Laue camera with facility for precision location of the sample in front of the beam was employed for this purpose. The collimator size was 30 p and the specimen to film distance was 5 mm. The Laue photograms were enlarged to an equivalent 3-cm specimen to film distance for analysis. The orientation of each of the plates of martensite was compared to that of the parent austenite and the relationship be -tween the two phases was, in all cases, within a few degrees of those predicted for the direct transformation. The orientation relationship between one of the larger plates of reversed austenite and its parent martensite was determined in a similar manner. The habit plane of the islands of reversed austenite in the X-rayed plates of martensite was determined by a single-surface trace analysis. Each reversal island had with the parent phase one comparatively straight boundary which was presumed to represent the habit plane trace. The pole locus technique7 was applied to traces from six different plates of martensite to determine the indices of the habit plane. A 40-cm stereographic net was employed for this analysis The morphology and fine structure of the reversed austenite were studied by electron microscopy of pre-shadowed direct carbon replicas,5 and the macroscopic shear was evaluated by a two-stage replica technique similar to that employed in electron fractog-

Jan 1, 1968

By W. I. Enderlin, P. O. Jackson, J. A. Glissmeyer, K. B. Olsen

A reliable estimate of radon emissions to the environment from underground uranium mines was obtained through measurements of radon in ventilation air at 24 mines and from estimates of radon release from other mine sources. The total production of U308 from the mines sampled represents about 63% of the total U.S. production from underground mines (1978 statistics). Wide variation in the radon emission rate per unit of production was found from mine to mine. Using the total radon emitted and U308 produced by all mines sampled, an average of 26.7 Ci of radon was emitted per ton of U309 produced. The investigation includes a brief study of the sources of variation of the emission rates. A statistically significant relationship was found between the measured radon release rate and the cumulative ore production at several mines.

Jan 1, 1981

By George E. Niewiadomski

The exposure of miners to radon gas and its airborne daughter products is a serious health problem which has long been recognized in the uranium mining industry. The association of high exposure to alpha particle emitters with incidence of lung cancer is well established. There continues to be a pressing need to reduce and eventually eliminate the high incidence of occupational lung cancer among uranium miners through the development of new and improved measurement and control technologies. This paper highlights the current efforts of the Bureau of Mines radiation hazards research program. It is aimed at obtaining a fundamental understanding of the behavior and transport of radon and radon daughters, developing more accurate and reliable instruments and measurement methods and developing cost-effective control techniques. Also discussed are the most recent accomplishments and the future research plans of the program.

Jan 1, 1981