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By Vincent C. Smith, Agit Singh, Daniel de V. van der Spuy, Bernard Muller

"Process control in the minerals industry is made difficult by factors such as the multivariable nature of the processes, noise, many disturbances, the changing nature of the processes, nonlinearities, process constraints, slow responses and large deadtimes. A good example of such a process is a milling circuit, where all these problems are experienced. Since model predictive control (MPC) effectively handles most of these difficulties, Mintek decided to develop, customise and test an MPC controller for milling control.Conventional MPC uses a dynamic model of the plant to calculate the future (predicted) plant outputs based on the movements of the manipulated variables in the past. The future moves of the manipulated variables can then be calculated using an optimisation algorithm that will minimise the difference between the setpoints and the predicted outputs. The least squares optimisation method is the quickest, but it does not cater for process constraints. Constraints can, however, be handled explicitly by using a quadratic programming optimisation method. This method ensures that the variables stay within the constraints at all times, but the calculation procedure is much more computationally intensive.• modifying MPC for the Minerals Processing IndustryIt was found that in order to obtain good, robust control using MPC in the minerals processing industry, the conventional MPC algorithm had to be adapted. The MPC controller was first tested on an extensive milling simulator, which was specifically developed for that purpose. Problem areas were identified and the MPC controller was specially adapted to accommodate for these difficulties. Some of the adaptations to the conventional MPC algorithm and special features added were as follows:Since milling plants contain many integrating processes (e.g. sumps), and integrating errors can cause offsets and poor control, it was essential that integrators be handled explicitly. This problem was solved by adapting the algorithm and also using an integrating error portion to compensate for integrating errors.Constraints on the inputs and outputs adversely affected the control. The controller using simple least squares optimisation was tuned with the constraints in place, while the maximum expected setpoint changes were made. This ensured that the process would be able to handle most setpoint changes up to these expected values without violating the constraints. A later improvement on this method was the incorporation of a quadratic programming algorithm to perform the optimisation. This method handles limits explicitly and was shown to perform better than the least squares methods (at the expense of a much higher computational cost)"

Jan 1, 2003

By E. H. Henderson

MR. R. V. NEILY stated that he had at one time operated at Goldenville. The practice and results are much the same now as in the olden days. Inside plates were then found to be a source of trouble and had been removed. At the Libbey mine, Queen's county, the sulphides carried considerable gold, and $45.00 to $60.00 per ton had been recovered from the concentrates by roasting and chlorinating. Later, concentrates were treated with bromocyanide. Following that practice, a cyanide leaching plant was installed, which did not require concentration of the tailings. Cyanidation brought a recovery of around 95 per cent, with but $300 worth of plant. In Nova Scotia, the ore of each locality presents an individual problem of its own as to treatment required. Ma. W. B. Timm stated that, in the majority of Nova Scotia gold ores, more than 75 per cent of the gold content is free-milling and, naturally, stamps are most efficient for collecting and amalgamating this gold. In Ontario and the West, they had got away from stamps, and perhaps the main reason was that the supply of battery-men, who came from Nova Scotia, had died off. Ball-mills had been installed, which required smaller space and handled large tonnage, even though, as far as amalgamation goes, the stamps were probably more efficient. If concentration is to be done, ore from stamps is usually in better shape for recovery in passing over the tables, as there is no slime. With the ball-mill, flotation is necessary. The better practice, undoubtedly, is to take out what gold is possible before it is all smashed up, as in the ball-mill, though recent developments in the ball-mill make it possible to trap and take coarse gold directly from the mill. In this way, cyanidation is speeded-up, due to saving of the time the coarse gold would take before going into solution. PROFESSOR A. E. FLYNN found it unusual in these days to read anything in favour of the stamp mill, and thanked Mr. Henderson for the excellent paper in which he upholds the stamps and backs his opinion with facts from actual operations. For the typical Nova Scotia ore, containing coarse gold, stamps are un¬excelled. It used to be said that the virtue of stamps is that they brighten the gold for amalgamation. Although this saying is almost classical, it is not true, for gold is never brighter than in the native, untouched state. Any hammering that gold gets makes it more difficult to amalgamate.

Jan 1, 1935

By C. E. Cottrell, G. W. Preckshot, N. D. Delisle, D. L. Katz

Most crude oils contain asphaltic substances that may be naturally or artificially precipitated. In the Greeley field, California, this asphaltic bitumen is precipitated during the flow of the oil from the reservoir to the stock tank The mechanism of such precipitation is not well understood. This paper presents the progress that has been made by using the electron microscope as a new tool and by observing the effects of the streaming potential on the formation of bitumen particles. Crude oils at atmospheric pressure viewed in the electron microscope in very thin films under a vacuum showed no asphaltic particles. A technique of preparing slides of thin films by dilution of the oil with benzene and washing in petroleum ether was used at first, and these observations showed that the solvents caused the formation of the particles, varying from 0.01 to 0.2 micron in diameter. The electrical effects of fluids flowing through porous solid were studied, with emphasis on the formation of colloidal particles by the streaming potential. The streaming potential of crude oil flowing through sand was measured and was shown to be responsible for the formation of bitumen particles. These results bring out a new phenomenon, which may occur when crude oil flows through the porous oil reservoir. mechanisms. Asphalt has been the subject of widespread investigation but, owing to the complexity of the substances being considered, progress has been slow. Investigators working primarily with the asphaltic substances have treated the subject from the colloidal standpoint and have developed theories that picture the asphaltic particles as surrounded by adsorbed materia1s.14,15,17,24 The deasphaltization of lubricating oil by the use of solvents treats the subject primarily from the standpoint of liquid-liquid equilibria.'' A complete understanding of asphaltic substances would make possible the following of the material from its initial state in the crude oil through precipitation processes to the final plastic stage, the most common form of which is used in asphaltic pavements. Since these asphaltic particles are very small, it appears 'hat the electron microscope4 might be a useful tool in studying the precipitation processes. Specimens are examined by the electron microscope in a vacuum and as very thin films, requiring special techniques in preparation of samples. A brief description of the electron microscope and its operation will bring out the difficulties and advantages of its use for this problem. The first work was done with crude oils that had been diluted with solvents for the preparation of the film to be examined. Later a technique was developed by which the undiluted oil film could be made thin enough for direct examination. These two techniques show vastly different results Asphaltic particles have been precipitated from crude oils by a variety of

Jan 1, 1943

By G. W. Preckshot, C. E. Cottrell, D. L. Katz, N. D. Delisle

Most crude oils contain asphaltic substances that may be naturally or artificially precipitated. In the Greeley field, California, this asphaltic bitumen is precipitated during the flow of the oil from the reservoir to the stock tank The mechanism of such precipitation is not well understood. This paper presents the progress that has been made by using the electron microscope as a new tool and by observing the effects of the streaming potential on the formation of bitumen particles. Crude oils at atmospheric pressure viewed in the electron microscope in very thin films under a vacuum showed no asphaltic particles. A technique of preparing slides of thin films by dilution of the oil with benzene and washing in petroleum ether was used at first, and these observations showed that the solvents caused the formation of the particles, varying from 0.01 to 0.2 micron in diameter. The electrical effects of fluids flowing through porous solid were studied, with emphasis on the formation of colloidal particles by the streaming potential. The streaming potential of crude oil flowing through sand was measured and was shown to be responsible for the formation of bitumen particles. These results bring out a new phenomenon, which may occur when crude oil flows through the porous oil reservoir. mechanisms. Asphalt has been the subject of widespread investigation but, owing to the complexity of the substances being considered, progress has been slow. Investigators working primarily with the asphaltic substances have treated the subject from the colloidal standpoint and have developed theories that picture the asphaltic particles as surrounded by adsorbed materia1s.14,15,17,24 The deasphaltization of lubricating oil by the use of solvents treats the subject primarily from the standpoint of liquid-liquid equilibria.'' A complete understanding of asphaltic substances would make possible the following of the material from its initial state in the crude oil through precipitation processes to the final plastic stage, the most common form of which is used in asphaltic pavements. Since these asphaltic particles are very small, it appears 'hat the electron microscope4 might be a useful tool in studying the precipitation processes. Specimens are examined by the electron microscope in a vacuum and as very thin films, requiring special techniques in preparation of samples. A brief description of the electron microscope and its operation will bring out the difficulties and advantages of its use for this problem. The first work was done with crude oils that had been diluted with solvents for the preparation of the film to be examined. Later a technique was developed by which the undiluted oil film could be made thin enough for direct examination. These two techniques show vastly different results Asphaltic particles have been precipitated from crude oils by a variety of

Jan 1, 1943

By Junbiao Liu

Rutile is mostly produced from placer sands. Its beneficiation from primary deposits has rarely been investigated. However, there is interest in primary deposit because of the depletion of sand deposits. The Zaoyang deposit in China is the only rutile primary deposit currently mined. The plant employs a Tabling-Magnetic process which recovers only 20% Ti02 at a grade of 87%. This study shows that significant improvement on the recovery (52% at the same grade) can be achieved. This study includes a detailed mineralogical examination and the development of a processing flowsheet of the ore. The gangues are primarily amphiboles, garnets, zoisites, and chlorites. The liberation of rutile occurs at about 200 mesh. Gravitational, flotation, and magnetic separations are all employed in the process developed, depending on the mineral characteristics and experimental results. The flotations circuit utilizes benzyl arsonic acid to float rutile and sodium fluosilicate to depress the gangues. This is a new reagent scheme for rutile flotation.

Jan 1, 1989

By Fred Drury

I spent 38 years in the Industry in a variety of sales, technical and management positions. I started out with Hercules, then was one of the founders of ECONEX, a large regional Distributor, and finally served with Dyno Nobel as a global Vice President, based in Oslo, Norway. When I retired in the fall of 1998, I looked forward to spending a lot less time traveling and a lot more time around home. After 4 years, I’m still traveling and still wondering how to find a few more hours in the day.

Jan 1, 2003

By Brian W. Hester

Ore was first discovered at the Kidd Creek mine site during the first few days of December 1963 when a diamond drill hole there cut sulfide mineralization. This event marked the end of the search started 11 years earlier with the conception of a geological idea. Economic forces provided the stimulus needed for the application of this idea but other-events, and legal considerations, also played arole in delaying the ultimate discovery. The location of Kidd Creek is shown in Fig. 1. Management of the then Texas Gulf Sulphur Co. had become concerned in 1951 at the company's declining reserves of native sulfur in Texas. This problem was to be alleviated by new discoveries and development of methods to recover sulfur from sour gas. At the time, however, the solution appeared to lie in the recovery of sulfur from pyritic ores. Canada was chosen as the best country in which to find these ores. Walter Holyk was hired in 1951 to conduct the search. By 1952, he was working in the area near Sherbrooke, Quebec, known as the "Eastern Townships" where mineralization consisting of base metal sulfides in volcanic rocks has long been known. His observations here led him to the then revolutionary conclusion that such mineralization could have formed as part of the volcanic process and not, as was generally supposed at the time, by replacement. On learning of the discovery of similar mineralization near Bathurst, NB, he moved there in the spring of 1953. He was able to utilize his new concept and found the Half-Mile Lake sulfide deposit.

Jan 1, 1991

By Johne Jesus Mol Peixoto

No reator RH, a otimização do fluxo recirculatório de aço entre a câmara de vácuo e a panela é a chave para promover as reações de refino. Neste trabalho, foram utilizados água e solução de cloreto de zinco (ZnCl2) como fluido similar ao aço para investigar a taxa de circulação no modelo a frio de um reator RH em escala 1:7,5. A taxa de circulação foi determinada utilizando o método de pontes de Strain Gages. A técnica PIV foi utilizada de modo a calibrar e validar os resultados. O aumento da vazão de gás de 30l/min para 120l/min resultou na elevação da taxa de circulação para ambos os fluidos. Cálculos preliminares demonstraram que há grande diferença nas condições de arraste de escória entre os sistemas água/óleo e ZnCl2/óleo.

Aug 17, 2017

By T. S. Lundy, R. E. Pawel

Effects of short-circuiting paths on observed diffusion behavior in real crystalline systems are considered. It is concluded that experimentally measured diffusion coefficients may vary widely from values associated with true lattice diffusion to those appropriate for short-circuiting paths alone depending upon the conditions of the experiment and the sensitivity and completeness of the data. IN 1961 Harrison1 classified experimentally observed diffusion behavior in systems involving both lattice and dislocation-enhanced atomic transport into three categories. His types A and C were limiting cases where the measured diffusion coefficients using the usual serial sectioning techniques were representative of lattice diffusion (with only slight effects of dislocations) and dislocation-network diffusion (with only slight effects from lattice diffusion), respectively. In both cases A and C for a sectioning experiment in which the diffusion couple has the semi-infinite geometry and unidirectional diffusion takes place from a plane source located at the origin of the coordinate system, he pointed out that Gaussian penetration behavior should be observed. For case A the lattice coefficient should be slightly enhanced by dislocation contributions, and the model of Hart2 can be used to predict the amount of this enhancement. For case C the observed coefficient should be that for the dislocation network and have little or nothing to do with lattice diffusion. Hart's model in its general form is still applicable, but the apparent diffusion coefficient for this case is virtually independent of dislocation density. Harrison's case B is that for which non-negligible contributions exist for transport by both mechanisms and "the concentration distribution does not approximate to any simple form." With the possible exception of very low temperatures where diffusion distances approach atomic dimensions, any real diffusion specimen will in general show non-Gaussian behavior provided the data are complete enough to uncover it. Thus, a "complete" set of data for any real system cannot be expected to be totally amenable to treatment by a simple mathematical model which does not take into account the relative distribution of transport by the various modes or submodes. For a particular sensitivity of specimen analysis and at a given temperature of annealing if the concentration profile could be observed as a function of time, "the behavior will initially be type C, and will develop into type B. and ultimately type A".1 Thus, it appears that the type of diffusion behavior which is experimentally observed in a given system depends very much upon the particular experimental conditions and the particular tools available to obtain the data. Interpreted in this fashion, Harrison's classification refers not to the diffusion behavior as a whole but to the relative sensitivity of the method of examination and completeness of the data. In the present paper we will: 1) assume that the measured penetration behavior follows the same general classification as that proposed by Harrison; 2) give, for diffusion in tungsten, examples of the range of diffusion coefficients that it is possible to obtain in a single experiment; and 3) speculate that some arguments which consider the possibility of short-circuiting effects being responsible for "anomalous" diffusion in several bcc metals may have been discarded prematurely.3 Both monocrystalline and polycrystalline tungsten were used in this work. The former was obtained as triple-pass, electron-beam zone-refined 6.0-mm-diam rod from Materials Research Corp.. Orange-burg. N.Y. The latter was swaged, high-purity bar stock which was annealed for 2 hr at 2200°C and 10-9 torr to yield an average grain diameter of about 25 /i. The tracer Nb95 was received in oxalate solution from the Isotopes Division, Oak Ridge National Laboratory. Experimental procedures of specimen preparation, isothermal diffusion annealing, serial sectioning by anodizing-and-stripping, and y counting of the individual sections to determine the tracer penetration profile after a given diffusion anneal have been described elsewhere.4 However, it should be noted that the anodizing-stripping sectioning technique has the particular advantage for this research of permitting sectioning to be accomplished over a wide range of

Jan 1, 1970

By B. Sergeant

Any study of the contentious subject of nationalization can ultimately be reduced to a sombre analysis of the simultaneous, and very different, interests of capital, labour, and government. Each of these interests attempts to maximize its objectives, subject to checks and balances provided, in an ideal system, by a country's executive government, legislature, and judiciary. Where even one of the three interests goes out of control, the consequences can be disastrous. The case histories show that when this occurs, the most common culprit is government, or its proxy, such as a dictator. At the other extreme, the case studies indicate that the optimum outcome occurs when capital, labour, and government are 'ring fenced' from each other: each enjoys its rights, but is also subject to duties. 'Conflicts of interest' between the three entities are ideally avoided to the maximum possible extent. The case studies include several salient instances from both the DRC (Gécamines, La Générale des Carrières et des Mines) and Zambia, along with Ghana and Chile. Further instances are examined in South Africa (gold), India (Coal of India), Brazil (Petrobras), Venezuela (Petróleos de Venezuela), Sweden (Luossavaara-Kiirunavaara Aktiebolag), Mauritania (Société Nationale Industrielle et Minière), Norway (Norsk Hydro), Botswana (Debswana), and Namibia (Namdeb). The article concludes broadly that South Africa's minerals sector is not ready for nationalization.

Jan 1, 2013

By I. S. Thompson

"Exploration properties form a continuum from grass roots to those with favourable geology, geochemical and/or geophysical anomalies, mineralization, showings (prospects), and finally to those with defined mineral deposits. Often, properties exhibit a composite of these categories.The most problematic to value are properties or deposits that are not economically exploitable at the time of the valuation due to a lack of exploration, insufficient grade or tonnage, poor mining conditions, or the imposition of socio-economic, environmental, or legal constraints.Various acceptable methods of valuing the range of all such mineral properties or deposits are reviewed. Some less appropriate methods are also discussed."

Jan 1, 2002

By E. Suoninen, K. Laajalehto, L. Kartio

Efficient separation of pyrite from other sulfides is of great importance for the metallurgical performance of flotation processes. In this work Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) were used to study the surface chemistry of pyrite in depression, activation and xanthate adsorption under conditions of controlled potential. Modifications of pyrite surfaces after treatment with depressants (lime, sulfur dioxide, sodium cyanide) and after activation with metal ions (Cu, Pb) were studied. The principal adsorption product identified on pyrite was dixanthogen whose formation started at about +0.15 V and +0.25 V (vs, SHE) in ethyl and amyl xanthate solutions, respectively. Copper xanthate was formed on copper(II) activated pyrite. Activation mechanism of pyrite by copper(II) salts is likely to be electrochemical where copper occurs as copper(I) on the surface of pyrite. Effective depression is achieved by sulfur dioxide and sodium cyanide. Depression at high pH is due to formation of iron(III) hydroxides. Calcium ions do not affect the electrochemistry but adsorb on pyrite and reduce the surface sites for dixanthogen adsorption.

Jan 1, 1995

By D. W. Schmidt, J. W. Shuster

Use of electric-wheel-driven haulage trucks at Chino dates back to 1963, and in today's fleet of 38 units, 17 trucks are electric-wheel- type powered with 700 hp diesel engines. Output of these engines is not adequate to exploit fully the 1200 hp potential of the two electric- wheel-drive motors, and, as a result, Chino has been testing larger prime power sources. An earlier test involved the use and evaluation of 1000 hp gas turbine engine in a conventional Model M-100 Unit Rig haulage truck (see [ ], May 1967, pp. 57-60). Now Chino has tested a trolley-diesel application in the same 100-ton capacity vehicle, and has shown that trolley power on electric-wheel-drive trucks can improve productivity rates from 18-36% on adverse grades, depending, of course, upon haul road profiles.

Jan 3, 1968

By G. E. Wood

THE INSTABILITY of copper prices and their low levels since late 1974 are of great concern to both producers and, to a lesser degree, consumers of copper. The price levels portrayed by the "neutral long-term" price trend are assumed to have been enough to encourage sufficient investment to provide adequate world production capacity and yet not so high as to encourage development of excessive over capacity. The identification of the present level of this trend has taken on special importance for governments and for corporations active in the world copper industry. One approach to the possible determination of such a price is through the use of moving averages. In this way, the effects of relatively short-term price movements can be dampened, as can those related to business cycles. From such averaged price data, long-term trends can be sought over a selected time period. The choice of the past time period for which a price trend is sought may have a major effect on the result'. For example, in the period 1885-1973, the long-term price trend for copper in constant dollars showed a decline, whereas in the period 1919-1973 it was rising. For the purposes of discussion, an appropriate choice of period might be a relatively short and recent one so that the majority of the present cost factors would be present throughout. It should also be long enough to cover a number of full business cycles.

Jan 1, 1977

By George M. Potter

During the late 1960s the mining industry became interested in USBM's efforts to develop the gold-silver heap leaching process. In the last 10 years, successful commercial heap leaching applications increased. The process provides a relatively low-capital means of processing treatable ores with reasonable operating costs. Present gold and silver prices compared to capital and operating costs favor the continued growth of the heap leaching method. The heap leaching process is defined as the percolation leaching of relatively coarse gold-silver ore piled on an impervious surface. To date, dilute alkaline cyanide solution is the lixiviant of choice. Other leaching reagents such as thiourea and hypo have been suggested, although they are not currently used in heap leaching practice. Ores may he run-of-mine in size or crushed as fine as about 10 mm. Gold and silver-bearing so¬lutions draining from the heaps may be processed in activated carbon columns to recover the metals, followed by stripping and metal recovery, or treated by the Merrill-Crowe zinc dust precipitation method. All solutions are generally recycled to the leaching step, and the heap leaching system is relatively easy to control from an environmental viewpoint. One advantage of the heap leaching process is its flexibility. Plants may be very simple, comprising leaching of uncrushed ore on a locally-obtained clay-lined pad and shipment of gold and silver recovered in the form of loaded carbon or zinc precipitates; such a plant would have a relatively low capital investment. More elaborate plants for larger ore bodies may be planned to include crushing, cyclic pad use, and done gold-silver recovery. General planning is similar in each case. This article outlines some key factors in designing heap leaching operations and discusses how these factors are applied to develop a working operation. Since individual design requirements and local costs vary so much, only a few general comments on costs are included.

Jan 3, 1981

By David C. Oyler, William P. Diamond

Three long horizontal holes were drilled from a directionally drilled sur¬face hole at the Emerald Mine near Waynesburg, Pa. The purpose was to adapt the technique of directional drilling for use in draining methane from coalbeds. A 504-m (1,652-ft) long, 76-mm (3-in) diam¬eter, circular arc pilot hole was drilled, using a downhole mud motor, to enter the Pittsburgh coalbed at a verti¬cal depth of 305 m (1,000 ft). The hole was reamed to 222 mm (8-3/4 in) and was cased to a measured depth of 486 m (1,595 ft). Three 76-mm (3-in) diameter horizontal drainage holes were then drilled, totaling 2,909 m (9,544 ft) of horizontal hole. Improvements in drilling methods increased the average drilling rate from 20.4 m (67 ft) to 64.9 m (213 ft) per day. The cost of drilling the directional and horizontal holes (using a Government-owned drill rig) was $1,169,530, a figure inflated by inexperience and by delays caused by lost-circulation problems and fishing operations. An estimated total drilling cost of $960,000 (including rental of a drill rig) for an improved system, was determined by a detailed cost analysis. Initial gas and water production from November 1979 through May 1980 was low because of caving of the horizontal holes drilled in shale near the bottom of the casing.

Jan 1, 1982

By Z. Khan

Iron, in the form of steel and stainless steel, is the most commonly used metal in the world. Plain steels corrode and oxidize easily, while stainless steels exhibit improved corrosion and oxidation resistance. It has been found that rare earth metal (REM) additions, such as cerium and erbium, result in the improvement of the abovementioned properties in iron-containing compounds. Gadolinium is a REM, however, there is very little information available on the influence of gadolinium on the microstructure and mechanical properties of iron-containing compounds. Thus, the purpose of this research project was to determine the influence of gadolinium additions on the microstructure and mechanical properties of mild steel and 316 stainless steel. Ten alloys were produced for the purposes of this research. Five of the alloys had a base composition of mild steel while the remaining five had base composition of 316 stainless steel. The alloys for each of the base composition contained gadolinium additions of 0.1, 0.5, 1.2, and 5 weight per cent. The as-cast and the cold-rolled alloys were analysed. The alloys responded well to the cold-rolling with the exception of the 5 weight per cent gadolinium mild steel and stainless steel alloys. These alloys were extremely brittle and underwent a significant amount of cracking during the cold rolling process. A microstructural analysis of the alloys was conducted using a light optical microscope, while the chemical analysis of the alloys was conducted using energy dispersive x-ray spectroscopy (EDS). The resulting microstructures and EDS analyses revealed that the gadolinium displayed minimal solubility in the ferrite matrix of the mild steel alloys and minimal solubility in the austenite matrix of the stainless steel alloys. Instead the gadolinium formed as an interdendritic secondary phase in both alloys. EDS analysis revealed that the secondary phase in both alloys was gadolinium-rich. Vickers microhardness tests conducted on both alloys revealed that the alloys were composite-like, with a hard, brittle gadolinium-containing compound dispersed throughout a softer, more ductile matrix. The corrosion resistance of the alloys was determined through potentiodynamic anodic polarization tests. Two solutions were used for the corrosion rate tests: a 0.5 weight per cent NaC1 solution and a 0.5 M H2SO4 solution. The results from the mild steel alloys revealed that in both the solutions, the corrosion potentials and the corrosion resistance of the alloys increased with increasing gadolinium concentration up to 1 weight per cent. The corrosion rate test results from the stainless steel alloys revealed that the passivation current density and corrosion resistance of the alloys increased with increasing gadolinium concentration in both solutions. The oxidation resistances of the mild steel and stainless steel alloys were determined through the use of a Netzstch Simultaneous Thermal Analyser. For both the mild steel and the stainless steel alloys, it was found that the oxidation resistance of the alloys increased as the concentration of gadolinium increased when compared to the as-received mild steel and stainless steel samples. This could be due to a strongly adhering gadolinium oxide scale that formed on the surface of the alloys and resulted in the protection of the mild steel and the stainless steel.

Jan 1, 2012

By Emil Szaks

[A great number of papers have been presented at various Engineering Society meetings on the Unit Train subject. Moat are descriptions of facilities that have been constructed or are abort to be built. Many describe the facility as being the World's fastest, newest, largest, incorporating the latest technology and so forth, Many are duplications of installations that have been recently constructed, sort of carbon copies but perhaps arranged differently. The trend has been to incorporate loop tracks, rotary dumpers, indexers and, of course, the snivel coupler equipped unit train. How that the energy crisis has increased the use of coal, there has been a tremendous Increase in applications for permits to construct rail to river coal loading facilities. This paper is different. It does not describe any single existing facility, but is given to alert prospective terminal owners and engineers that there are items that require considerable study and evaluation beside merely selecting an indexer, car dumper, stacker, ship or berg loader and so on. An important item is the selection of the railway car which in turn can affect the selection of the method of loading and unloading. Let us list a few of the items that should be considered and discuss the areas that require examination:]

Jan 1, 1979

By B Cope, N Hastings, D Webb

A Feasibility Study was completed in late 2002 to ascertain the risk and reward profile from the proposed deepening of operations at Perseverance Nickel Mine in Western Australia. The system and approach adopted to this brownfields extension work is outlined and the main components of the study are overviewed. In particular, emphasis is given to the integration of mine design and scheduling tools through to financial evaluation. Detailed comment is given on the ability of the system used to provide a robust project schedule complete with 3D animation. The level of importance in eliminating scheduling errors is demonstrated in relation to the reported bottom line viability of the project. It is suggested that this is an area where brownfields Feasibility Studies have lacked clarity and authenticity, leading to the creation of an unrealistic benchmark for project implementation.

Jan 1, 2003

By E. P. Youngman

This paper presents one of a series of digests of foreign mining legis- ation and court decisions that is being prepared in advance of a generel report elative to the rights of American citizens to explore for minerals and to own nd operate mines in various foreign countries. This interpretation of the laws of Demark and her possessions, has been prepared entirely from answers made by Ernest L. Ives, American charge d'effaires, Copenhagen, to a questionnaire ini- isted by the United States Bureau of Mines and transmitted through the courtesy of the Department of State.

Jun 1, 1932