Search Documents

By Jr. Schnakenberg

The automation (robotization) of coal mining activities at the face offers improvements in worker safety and productivity. The evolutionary introduction of autonomous, intelligent robotic machines to perform the most hazardous tasks may become a reality within the next 10 years. The U.S. Bureau of Mines Robotics and Automation research program is aggressively pursuing the development of the enabling technology necessary to achieve this goal. This program consists of both core and applications research, each focused on the fundamental issues of robotic technology. In the short term, the research is directed specifically to the robotization of present-day underground equipment and is being performed in a manner that can make incremental improvements in safety and productivity. The long-term goal is the development of intelligent autonomous mining systems.

Jan 1, 1990

By Allen D. Graham

The coal industry in South Africa is briefly outlined. Test- work carried out on bulk samples of coal in the laboratory and used in the design of the Van Dyks Drift washery are described. Factors affecting the selection of equipment and the designed capacity of the plant are discussed. A description of the crushing plant, washery and load out section is given together with performance data obtained in the final acceptance tests. New features incorporated in the Van Dyks Drift plant and in more recent plants of the Group are outlined.

Jan 1, 1982

By R. S. Dean. J. R. Long T. R. Graham, Roberson A. H., Armantrout C. E.

The general program of the Federal Bureau of Mines on the study of alloys made with electrolytic manganese has been extended to copper-manganese-aluminum alloys. The initial results of the work are presented in this report and concern a determination of the mutual solubilities of these three metals to form the alpha solid solution. The principal studies of this system, reported in the literature, have been focused on the Heusler alloys containing ro to 30 per cent Mn with 9 to 15 per cent Al. These investigations concern the ferromagnetic properties and the determination of the crystallization contours, with little emphasis on the phases present in the solid state outside of this area. Heuslerl recognized a breakdown of the beta solid solution of the magnetic alloy, which he says decomposes into the alpha, beta, and gamma phases of the copper-aluminum system, somewhat modified by the presence of manganese. Rosenhain and Lantsberry2 examined alloys ranging up to 10 per cent Mn and 10 per cent A1 but were unable to reach definite conclusions concerning the phase boundaries in that area. Krings and Ostmann3 made magnetic studies and examined the system by thermal analysis. They present contours of the liquidus surface but do not place any of the phase boundaries. Corson4 has drawn a hypothetical boundary for the alpha field with few, data to support such construction. The binary systems involved have rcceived considerable attention by numerous investigators, and their general features are well established. The copper-ahminum system (Fig. I) has been thoroughly examined by Stockdale,5 who places the limit of solubility of aluminum in copper at 7.4 per cent at the liquidus and 9.5 per cent at room temperature. Smith6 established the eutectoid temperature at 570°C. by a study of isothermal decomposition of the beta phase. The copper-manganese system (Fig' ') has been recently reviewed by Dean and CO-WorkersS.7 Using high-purity alloys,

Jan 1, 1947

By Armantrout C. E., R. S. Dean. J. R. Long T. R. Graham, Roberson A. H.

The general program of the Federal Bureau of Mines on the study of alloys made with electrolytic manganese has been extended to copper-manganese-aluminum alloys. The initial results of the work are presented in this report and concern a determination of the mutual solubilities of these three metals to form the alpha solid solution. The principal studies of this system, reported in the literature, have been focused on the Heusler alloys containing ro to 30 per cent Mn with 9 to 15 per cent Al. These investigations concern the ferromagnetic properties and the determination of the crystallization contours, with little emphasis on the phases present in the solid state outside of this area. Heuslerl recognized a breakdown of the beta solid solution of the magnetic alloy, which he says decomposes into the alpha, beta, and gamma phases of the copper-aluminum system, somewhat modified by the presence of manganese. Rosenhain and Lantsberry2 examined alloys ranging up to 10 per cent Mn and 10 per cent A1 but were unable to reach definite conclusions concerning the phase boundaries in that area. Krings and Ostmann3 made magnetic studies and examined the system by thermal analysis. They present contours of the liquidus surface but do not place any of the phase boundaries. Corson4 has drawn a hypothetical boundary for the alpha field with few, data to support such construction. The binary systems involved have rcceived considerable attention by numerous investigators, and their general features are well established. The copper-ahminum system (Fig. I) has been thoroughly examined by Stockdale,5 who places the limit of solubility of aluminum in copper at 7.4 per cent at the liquidus and 9.5 per cent at room temperature. Smith6 established the eutectoid temperature at 570°C. by a study of isothermal decomposition of the beta phase. The copper-manganese system (Fig' ') has been recently reviewed by Dean and CO-WorkersS.7 Using high-purity alloys,

Jan 1, 1947

By Sanchita Chakravarty, Sumantra Bhattacharya, Divya Jyoti, A. K. Mukherjee, Soni Jaiswal

"Release analysis is independent of collector and frother dosage and type, but it is primarily influenced by the degree of liberation or “state of release of the sample”. The shape of release curve is an indication of the degree of liberation. This paper briefs about the effect of reagent combination, particle size and surface characteristics on the release analysis of difficult-to-clean LVC coal.Release analysis of three LVC coal fines obtained from two different coalfields of India was carried out at three different size levels such as -0.5mm, (-0.5+0.1) mm, and -0.1mm. The collectors used were n-dodecane and commercial diesel oil. Incomplete liberation of coal fines even at a size of -100µm, corroborated by photomicrographs of ROM and clean coal macerals, in a great measure reduced the flotation-based cleaning potential of the fines. FESEM images of fines reveals that the adherence of ultrafine onto the surface of relatively coarser particles reduced the clean coal recovery. The results obtained also appear to be coal, reagent combination and, particle size and particle surface specific. Only one coal indicated the liberation as is usually expected for -0.1mm particles with a reasonable yield of 65% at 18% ash. INTRODUCTION Froth flotation has a long history of being used to treat coal fines. Coal flotation is considered to be difficult, if the percentage of Near Gravity Material (NGM), i.e. essentially locked particles, in flotation feed is >10% [Aplan, 1993], which is usually the case with all the coking coal fines in India. The fines are rich in vitrinite, so valuable for coking coal. Unfortunately, there appears to be no standard procedures to determine the separation efficiency of froth floatation. Release analysis proposed by C.C. Dell in 1953 [Dell, 1953], aimed to determine the ultimate floatability of coal. Several other techniques had been proposed but release analysis technique has been considered to be a vast improvement over the batch flotation process [Forrest et al. 1994]."

Jan 1, 2018

By Z. Hajnal

Three years ago a research program was initiated at the University of Saskatchewan to develop seismic surveying techniques for use in the Precambrian geological environment. The success of the reflection method in many younger geological settings suggested that this is the technique which would be the most suitable for experimentation. A successful adaptation of this technique to the Shield environment would make mapping of rock formations possible to much greater depth than is possible at the present time with any other applied geophysical technique. This presentation attempts to illustrate the advances which have been made in this program and will provide some insight into future plans. The field investigations were limited to the Flin Flon basin near to the town of Flin Flon, Manitoba (Fig. 1). This area was chosen because the surface geology has been mapped in great detail and it is a very important base metal producing region. It is an ancient sedimentary basin with some characteristics similar to areas where the reflection method has been successful.

Jan 1, 1976

By M. B. Kime, A. T. Kaniki

"Grinding tests were conducted on an oxidized copper-cobalt ore using a pear-shaped ball mill. Twelve mono-sized ore fractions were prepared and wet ground batchwise. The mill was run for 0.5 to 30 min intervals. The shortest interval provided data more closely related to the breakage function (B) because less secondary breakage was hypothesized. Some selection function (S) and B parameters were determined. Remaining parameters were estimated using a population balance model simulator. To evaluate the kinetics model, an unsized ore sample was also milled. Predicted and measured particle size distributions (PSDs) agreed well, suggesting that S and B parameters can be used for continuous operation mass balances.RÉSUMÉ Des essais de broyage ont été menés sur un minerai oxydé de cuivre-cobalt à l’aide d’un broyeur à boulets piriforme. Douze fractions de minerai de dimension unique ont été préparés et broyés en voie humide en lots. Le broyeur était mis en route à des intervalles de 0,5 à 30 minutes. L’intervalle le plus court fournissait des données plus étroitement liées à la fonction d’abattage (B) car d’après l’hypothèse avancée, le besoin d’abattage secondaire était moindre. Certains paramètres de la fonction de sélection (S) et de B ont été déterminés ; les paramètres restants ont été estimés à l’aide d’un simulateur de modèle d’équilibre de population. Pour évaluer le modèle de cinétique, un échantillon de minerai non calibré a également été broyé. Les compositions granulométriques (PSD, de l’anglais particle size distributions) prévues et mesurées correspondaient bien, ce qui laisse penser que l’on peut se servir des paramètres S et B dans le cadre d’équilibrages massiques en fonctionnement continu. INTRODUCTIONSize reduction of solids is a very energy intensive and highly inefficient process. It consumes approximately 5% of the electricity produced worldwide (Rhodes, 1998), and more than 50% of the total energy used in mineral processing plants (Walkiewicz, Lindroth, & Clark, 1996). An increase in grinding efficiency can therefore result in significant reductions in operating costs. This often amounts to determining the optimal design configurations for milling an ore sample in a laboratory mill under standard conditions. Prior to optimizing the milling stage, the requirements for downstream processing in terms of particle size distribution (PSD) need to be understood because low liberation and overgrinding will lead to future problems. Once this is done, it is also important to clearly understand the breakage properties of the ore. The kinetics of size reduction in tumbling mills are often determined using two probabilistic functions: selection and breakage (Austin & Luckie, 1972). Knowledge of the selection and breakage functions also enables the prediction of the PSD for a given ore sample."

Jan 1, 2017

By P. M. Daignault

"Fording Coal Limited is one of Canada's largest producers of metallurgical coal for the export market. Medium- to highvolatile coals are mined at its Fording River operations in southeastern British Columbia. This paper discusses some of the mine design and production related problems encountered, and how they have been resolved. Other aspects of the operation such as geography, geology and standard mining methods employed are also covered.IntroductionFording Coal Limited was formed in 1968 to mine and market metallurgical coal resources held by the company in the East Kootenay region of southeastern British Columbia<1>. The company, at its Fording River operations, holds approximately 19,635 hectares of coal lands, having an estimated resource of 3.5 billion tonnes of metallurgical coal. Total reserves are approximately 520 million tonnes.Fording Coal is owned 600Jo by Canadian Pacific Enterprises Limited and 400Jo by Cominco Limited. Cominco itself is owned approximately 540Jo by Canadian Pacific Enterprises. The company, originally staffed and managed by Cominco, has been independent since January 1978, with its own board of directors, management, staff and employees. The head office is in Calgary, Alberta. The Fording River operations are located in British Columbia, approximately 70 km north of the Crowsnest Pass, near the Alberta/ British Columbia boundary, only 150 km by air and 320 km by road from Calgary.A contract was signed in 1969 with the Japanese steel mills to provide 45. 7 million tonnes of metallurgical coal over fifteen years, commencing in 1972, at an annual rate of 3 .05 million tonnes per year. The mine is presently expanding annual production capacity from the original 3.0 million long tons (3.05 million tonnes) to in excess of 5.0 million tonnes.Concurrent with this production expansion, a vigorous marketing effort has diversified Fording's customers to include additional countries in the Pacific Rim area. Three cleaned coal products are now marketed compared to the single ""standard blend"" product originally shipped to satisfy the Japanese contract. The product specifications are listed in Table I."

Jan 1, 1985

By William (Bill) H. Walton

"I arrived in Chicago in 1993 with Dr. Ralph Peck’s University of Illinois bulletin titled Engineering Properties of Chicago Subsoils (Bulletin 429), which he published in 1954 with William Reed. Being an outsider, I wanted to learn from Chicago geotechnical practice leaders that included Clyde Baker, Jr., John Gnaedinger, Charles Pfingsten, Dr. Safdar Gill, Robert Lukas and Dr. Jorj Osterberg, who have influenced foundation designs for the structures that make up the contemporary Chicago skyline. One of my immediate goals was to get the Illinois Structural Engineering license to be on par with the likes of Eli Cohen, Mike Tylk, Stan Korista, Bob Halverson, Joe Burns, Ron Johnson, Bill Baker, Bob Sinn, Chuck Anderson and Dave Eckmann, who have led their structural firms in the design of the skeletal core and frames of many of Chicago’s iconic buildings (and for many other buildings around the world). From my time with GEI Consultants (GEI), then on with STS Consultants (STS, and now AECOM), and now back with GEI, I have had the opportunity to analyze and design foundations and, with the help of many skilled foundations and building constructors, to verify that predicted foundation performance matches actual movement data. The theme of Chicago’s foundation design practice is to assume and verify. In 1948, Peck published the History of Building Foundations in Chicago (Bulletin 373) that was updated in 1998 by Baker, Pfingsten and Gnaedinger, who meticulously documented hundreds of Chicago’s foundations, and have shown the value of advanced analyses and testing to advance the deep foundation design practice that includes a variety of high-capacity driven and drilled deep foundations. Mehmet Uyanik, Peck and Baker have made Chicago’s subsurface into a full-scale foundation test laboratory. They confirmed soil mechanics principles like Terzaghi’s 1-D consolidation theory when early foundations bearing on sand-clay crust over soft to medium silty clays (e.g., Auditorium, Masonic Temple, Monadnock Block and Old Board of Trade buildings) took 40 to 60 years to consolidate clay 1 to 2 ft (0.3 to 0.6 m). They also confirmed proven increases in bearing pressures based on measured performance of deep foundations bearing on the glacially derived hardpan clay till and in solid dolomite that underlies Chicago."

Jan 1, 2017

By K. A. Clark

SEPARATION of the oil from the bituminons sands of the Athabaska area of Alberta has been a subject of study by the Research Council of Alberta. The results of the study have been published in the Annual Reports of the Council. However, the last Annual Report in which there is mention of bituminons sand separation is that for 1934. The attention that is being directed toward the bituminons sands at the present time calls for an up-to-date summary of the work of the Research Council of Alberta on the hot-water separation process. STATEMENT OF FUNDAMENTALS OF HOT-WATER PROCESS Studies of the hot-water separation process have been largely empirical in nature. The objective sought has been a complete recovery of oil from the sand in the form of a separated oil which, itself, is free from mineral matter. Various procedures have been tried in the hope of attaining this objective and a very considerable mass of observations and background of experience have been acquired. lt is rime that a theory for hot-water separation should commence to emerge. As a start toward the formulation of such a theory, the statements which follow regarding the constitution of bituminons sand and its reactions with water and air are presented. It is not pretended that they are entirely correct, but it is believed that they lie not far from the truth. (1) Bituminons sand is an aggregate of sand, clay, oil, and water. The sand consists mainly of quartz particles of 100 ta 200 mesh size and smaller, but also of particles of other minerais including mica, rutile, ilmenite, tour-maline, zircon, spinel, garnet, pyrite, and lignite. Clay occurs interbedded with the bituminons sand, of which, also, it is a constituent. lronstone nodules of all sizes up to eight inches in diameter are likely to be present in the bituminons sand beds. The oil is viscous, naphthenic, and of a specific gravity slightly greater than that of water. The oil content ranges up to, and sometimes even exceeds, 17 per cent by weight. Rich bituminons sand from beds not invaded by water has a water content of 3 to 5 per cent by weight. The water is probably present as a film around the sand particles. The oil surrounds the moist sand grains as an envelope. (2) Water wets quartz and other siliceous minerals more readily than does mineral oil. Consequently, water tends to displace the oil film surrounding the quartz and other siliceous particles when the bituminons sand is mixed with water. Whether the oil is completely displaced depends on the properties of the water. That is to say, the materials dissolved or suspended in the water modify its wetting properties.

Jan 1, 1944

By J. D. Forrester

I have availed myself of the opportunity to prepare, and to give this talk because, as incumbent Chairman, I am directed by the Bylaws of the Council of Education to make an Annual Report of the Council activities which have transpired during the past year. In addition, and inasmuch as I have this captive audience, I am taking the liberty to express also some beliefs I hold about various other elements of Mineral Industry education. First, my report is that constructive progress has been achieved in the Council of Education during 1960-61. These advancements have been particularly notable through projects carried on by the Committee on Meetings and Programs, by the Student Chapters Committee, by the Accrediting Affairs Committee and by the Committee for Securing Better Representation of Mineral Industry Colleges. I believe each of these groups will report concerning details of their respective programs at the Business Meeting of the Council. On the other hand, not as much has been done in some areas of work as I had hoped would be the case when I took office as Chairman last February. Let me make clear that these delinquencies, for the most part, have resulted through my ineptness in handling of affairs; they are not caused by the failure to perform various assignments which I have given to council members.

Jan 1, 1961

By Roger Davieds

FACT: a company?s profitability (or loss) is directly related to the efficiency and effectiveness of its maintenance operation. Fact: in order to contribute in a positive manner, maintenance must understand what its true purpose is in the organization. It is easy to say our main purpose is to increase: ?equipment uptime ?OEE ?asset life cycle We all understand this; so does management.

May 1, 2010

By Lloyd R. Nelson

The feasibility of producing low carbon (LC) ferromanganese (FeMn) by lime-&apos;ore&apos; melt refining of high-grade ferromanganese silicon (FeMnSi) was investigated. Thermodynamic simulations demonstrated significant benefits in moving from a single-stage ladle operation to a two-stage counter-current reladling operation (to emulate the commercial Penin Process). The theoretical alloy silicon content was predicted to be refined from 1.57 to 0.005 per cent silicon, at a 6.2 per cent higher manganese yield (yield predicted to increase from 82.3 to 88.5 per cent). Extension of this counter-current refining principle, to a multistage Counter-Current Reaction Launder (CCRL) was investigated using the Slag Metal And Gas Klnetics (SMAK) software to model the mass transfer kinetics of the multicomponent coupled reaction system. Simulation results suggested that commercial production of 50 000 tonnes per annum (tpa) of refined LC FeMn, containing less than 0.5 per cent silicon, at manganese yields of up to 90 per cent, should be feasible in a compact CCRL (7 m long by 0.7 m wide).

Jan 1, 1994

By F. R. Joubin

MR. CHAIRMAN, Members of the C.I.M., and Friends -particularly friends, because I am not entirely a stranger in your city. I was last here some five years ago and it has given me a great deal of pleasure this evening to be able to say "Hello" again to those I had met at that time, when Bourlamaque and V al d&apos;Or were very busy centres of intensive and successful gold exploration. My remarks this evening have to .do with Canada&apos;s Place in the Atomic Age. They will be of a general nature but I hope to tell you ?enough to whet your appetite so that you may be provoked into per-.suing the subject further. Now, atomic developments have become quite commonplace. Words like radioactivity, reactors, nuclear fission, and so on are known to everyone, even the youngsters. I re-member two or three years ago one of my office boys came to me and said "Mr. Joubin, I would like a raise." I gave the request a few seconds of serious thought and finally said "Alright, Jimmy, we&apos;ll give you a raise." However, he made no effort to leave, so after a -couple of seconds more I said, "Is there something else ?" and he said "Yes, Mr. Joubin, could you make that raise &apos;radioactive&apos; to the first .of the year ?"

Jan 1, 1958

By W. C. Ellis, E. S. Greiner, M. E. Fine

C. H. Samans and W. R. Ham (Chicago, Ill., and Dix-field, Maine, respectively)-—For several years we have been studying transitions of this basic type in metals, alloys, glasses, etc. Usually, however, they are not so clearly marked as those which the authors have found, and hence are much more difficult to determine accurately. Since our studies indicate that most of them occur virtually unchanged (as far as temperature is concerned) regardless of the form in which the element appears, we believe that they are a characteristic of the atom. Specifically, we believe that there is an additional rotational degree of freedom possessed by the nucleus which has not been considered heretofore. This nuclear rotation is made up of several components, each related to the several quantum shells of electrons. In chromium there are four of these shells and hence four separate series of characteristic transition temperatures. The lowest temperature at which any transition occurs, based on the present state of our computations, is 125°K, 4° higher than the authors&apos; value of 121°K. A convergence of this series, we believe, shows up at the higher temperature of 2085 °K, surprisingly close to the transformation temperature of 2103°K recently announced by N. J. Grant of M.I.T. for a body-centered to face-centered transformation in chromium. Likewise, our computations indicate a temperature of 311°K for the second transition temperature, reported by the authors as 310 °K. A convergence of this series, we believe, shows up at a higher temperature as the melting point at 2163°K. Although our work on these series must, in a sense, still be regarded as empirical, since we do not understand fully as yet just what the series mean, it is based on a reasonably firm picture. The individual constants, from which the various series are computed for each element, comes directly from the X-ray K absorption limit. Furthermore, the same basic method has accounted for transformation and melting temperatures in about 50 of the chemical elements, which is all we have tried thus far. In many cases the only known transformation is the melting point, but in others the occurrence of transformations or other transitions, equally as well marked as those of the authors, has been pointed out by others. These observations have assisted us greatly. Consequently we were very pleased to see the authors&apos; excellent work in finding these two transitions in chromium. With these confirming data, our picture of this element is clarified considerably, so we expect that at least some of our work can be published in the near future. R. C. Ruder (E. I. du Pont de Nemours & Cu., Wilmington, Del.)—The authors&apos; interpretation of these transitions in terms of 3d to 4s electronic structure transitions is most interesting. It would be interesting to have additional experimental evidence of such transitions from the temperature dependence of the Hall coefficient in the neighborhood of the property changes discussed in this paper. Simple theory15 suggests the Hall coefficient as a measure of the free electron (or s electron) concentration per unit volume. It has been shown that for paramagnetic&apos;" and ferromagnetic1? metals the simple theory is in fact too simple. However, the existence of a discontinuity in the Hall coefficient would provide information which should aid both in our understanding of these transitions and the significance of the Hall coefficient in these metals. It was rather surprising that no significant paramagnetic effects were observed. In this connection the recent work of McGuire and Kriessman18 is cited. They measured the magnetic susceptibility of chromium from 20" to 1460 °C. They also observed no large change in the susceptibility although there might be a change in slope in the vicinity of the 40 °C transition. The existence of these 3d to 4s electronic transitions has been discussed in connection with the paramagnetic susceptibility behavior of nickel and nickel alloys.&apos;"-" Assuming a correspondence principle between classical and quantum mechanical paramagnetic theory and using classical theory to calculate the effective Bohr magneton number from the Curie constant for substances obeying the Curie-Weiss law," it is found that the effective magneton number is a function of temperature. The process of calculation involves the inverse of the differential of the 1/x4 vs. temperature curve so that good and numerous data are necessary to obtain significant results. The data of Fallot23 show a discontinuous increase of about 12 pct in the effective magneton number between 850" and 900 oC, followed by a continuous increase up to the melting point. The data of Sucksmith and Pearce24 show a possible 8 pct increase. The older data of Terry25 and Weiss and Foex26 show a continuous increase. It is possible that small amounts of impurity atoms change these electronic transitions significantly. Fallot&apos;s23 data on a nickel alloy with 4.5 atomic pct Fe indicate that the discontinuity occurs around 1300 °C. Systematic investigation of the transition metals for transitions of this nature should provide information which would be very valuable for our understanding of these metals. The absence of antiferromagnetic structures in chromium has been shown by Shull27 using neutron diffraction techniques. M. E. Fine, E. S. Greiner, and W. C. Ellis (authors&apos; reply)—The remarks by Drs. Samans and Ham are certainly very interesting, in particular those pertaining to the close agreement between the theoretically calculated values for transition temperatures in chromium and the experimental values reported by a number of investigators. This is a remarkable achievement and we shall look forward to a more detailed presentation of the method followed in their calculations. We do not believe that the transition in pure chromium near 40 °C remains temperature invariant with alloying, as was reported by Samans and Ham for a number of the substances that they studied. We have not done any work with alloys but base our belief on the results of earlier studies in which less pure chromium was included and considerably lower transition temperatures were observed. The transition tempera-

Jan 1, 1952

By Sydney Mantsho, Toni Streczynski, Manuel Gonzalez

"In 2013, the commissioning of the MillStar Stabilisation and FloatStar Stabilisation and Optimisation controllers were completed at the Cerro Bayo Silver (Ag) mine in Patagonia, Chile. The MillStar control system has stabilised the feed to the SAG mill as well as the density at the discharge end of the SAG mill and ball mill. The FloatStar Stabilisation and Optimisation controllers have successfully stabilised and optimised the flotation circuit to ensure consistent product quality within desired specifications.The mill feed is controlled utilising the MillStar Solids Feed controller. Additionally, the solids to liquid ratio into the SAG mill was controlled utilising the Mill Inlet Ratio controller in conjunction with the Solids Feed controller. The discharge end of the milling process is a highly interactive and complex system. The use of a Robust Nonlinear Model Predicative Controller (RNMPC) was ideally suited to control this section of the process. On the Cerro Bayo milling circuit, the RNMPC was used to control the mill discharge sump level and the primary cyclone feed density to produce a more consistent feed to the flotation circuit.Three levels of the FloatStar control system were installed, for flotation stability, concentrate flow stability as well as grade optimisation. The Level Stabiliser was used to stabilise the level control on 6 flotation banks. The Flow Optimiser was commissioned on the Rougher, Scavenger and Cleaner concentrate sumps to stabilise concentrate flow from the flotation cells. The Grade Recovery Optimiser was commissioned on the Roughers section. A number of instrumentation challenges were identified which limited the overall benefit derived from the system. Once these were addressed, the performance was optimised. The overall benefit provided by the system was observed in terms of the improvements in Ag recovery."

Jan 1, 2014

By George H. Holmes

This paper , which describes mining methods and milling and manufacturing operations at the gypsum property of the Blue Diamond Corp. , is one of a series on mining methods and practices being prepared by the Mining Division of the Bureau of Mines . The property comprises about 4,000 acres and is in secs . 30 , 31 , 32 , and 33 , T. 21 S. , R. 59 E. , and secs . 5 , 6, 7 , 8 , and 9 , T. 22 S. , R. 59 E. , M. D. B. and M. , Clark County , Nev . , approximately 23 miles by paved highway southwest of Las Vegas , Nev . ( fig . 1 ) . This circular summarizes the history of company operations , describes physical features , labor and living conditions , and the geology . The method of exploration is outlined , and the section on mining methods contains descriptions of open - pit and underground systems , including loading and transportation methods . The crushing plant and tramway are described , as well as plaster-mill and board -plant practices . The boiler plant and organization are described , and wage scales are contained in the concluding section of the circular .

Mar 1, 1950

By H. W. Gillett

MAINTENANCE of membership by the technical so¬cieties and the activity of these societies in spite of the adverse business situation have been noteworthy. This forcibly brings home the fact that industry recognizes that sound technical guidance is well worth its cost. The numerous difficulties and losses due to defects of various kinds arising from gas-metal reactions are now generally recognized and interest in these problems is widespread. The forthcoming A. I. M. E. round-table discussion of gas-metal problems will do much to clarify the situation and will permit us to assay our present knowledge and to suggest the proper direction for profitable future research. "The Age Hardening of Metal" was the title of the annual I. M. D. lecture delivered by Dr. Paul D. Merica. A critical review of the known facts relating to age-hardening phenomena was first given, followed by the presentation of a theory correlating the detailed observations which have been made regarding the mechanism of the hardening.

Jan 1, 1933

By Roger Cabos

El presente texto señala la necesidad de estudios microscópicos determinativos y cuantitativos como complemento de los análisis químicos, de forma que se explore la posiblidad de beneficiar el mineral oxidado por métodos convencionales.

Jan 1, 1987

By C. Bezemer, I. Havenaar

An investigation was carried out on the dynamic liltration behavior of drilling fluids. In a set-up consisting of a porous pipe through which the drilling mud was circulated, dynamic liltration rates and cake thicknesses were determined as a function of flow rate and filtration time. Eventually, a state of equilibrium was reached; i.e., both cake thickness and filtration rate attained constant values. Concurrently, dynamic filtration tests were carried out in a simple dynamic filter apparatus where mud flow was similar to that in a rotational vismmeter. In both arrangements the relation between equilibrium liltration data and rate of shear at the cake surlace was studied. Filter pipe and dynamic filter apparatus were lound to give identical relations. It was therelore concluded that the latter apparatus, which is suitable lor routine measurements on small amounts of mud, could be used to determine the dynamic liltration behavior of mud under borehole flow conditions. Some data are presented on the effect of filtration pressure and temperature on equilibrium filtration rate and cake thickness. INTRODUCTION In oil well drilling, the drilling fluid used generally forms a mud cake on the permeable sections of the borehole wall while filtrate is lost into the formation. As to the conditions under which this filtration process takes place, a distinction should be made between static mud filtration (mud is not circulating) and dynamic mud filtration (mud is circulating). In recent years several investigatorsl-5 have studied the process of dynamic mud filtration about which little had previously been known. This type of filtration is the subject of this paper which confirms several findings of previous investigators. It differs from already published works, however, in the following respects. 1. It contains a description of a simple laboratory apparatus developed for dynamic filtration measurements on small amounts of mud. 2. The effect of rate of shear at the cake surface on dynamic filtration has been studied. As a result of this study, dynamic filtration data pertaining to the borehole conditions of mud flow can be found from laboratory tests. 3. Some data are presented on the effect of filtration pressure and temperature on dynamic filtration. The work was limited to a small number of muds. No attempt was made to compare data on API filtrare loss with dynamic filtration rates. Previous workers have clearly shown that no correlation exists between static and dynamic filtration rates. EXPERIMENTAL ARRANGEMENT To establish whether the effect of mud flow conditions on dynamic filtrations is governed by the rate of shear at the cake surface, two different types of mud flow were used. In this connection the experiments were partially conducted by means of a porous pipe through which mud was circulated, partly in a dynamic filter apparatus which somewhat resembles a rotational viscometer. In both cases the flow conditions of the mud were well defined, thus making it possible to-calculate rates of shear at the cake surface. The filter pipe was 200 cm long with an internal diameter of 3 cm. Its perforated wall was covered on the inside with filter cloth on which the mud cake could form. Mud was pumped through the pipe at linear rates varying from 20 to 186 cm/sec. The required filtration pressure was obtained by means of a lack-pressure valve downstream of the filter pipe. In this arrangement the type of flow existing in the borehole is reasonably well simulated. The dynamic filter apparatus (Figs. I. and 2) consists mainly of two concentric cylinders with a clearance of about 0.5 cm. The outer cylinder (rotor) can be rotated at rates up to 1,000 rpm. The outer surface of the inner cylinder (radius about 2.5 cm) is covered with filter cloth or paper supported by copper gauze. The two cylinders are mounted inside a pressure

Jan 1, 1967