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By K. A. Hildebrant, J. R. Norgate

"Synthetic lubricants have for many years documented extended service life and provided superior performance in temperature extremes. Increasing interest in synthetics' ability to reduce energy costs has resulted in laboratory and industry application evaluations. These tests have documented savings in functions such as worm gear drives, spur gears and in compressors. Energy savings data are presented as well as payback calculations as low as thirty days.The National Research Council of Canada has estimated that the Canadian economy loses over five billion dollars per year in friction and wear. Figures quoted were for 1986 during which it was estimated that nine hundred and forty million dollars were lost in the mining industry alone"" It has been further estimated that about 115 million dollars can be immediately recovered through improved tribology practices (Table I).The purpose of this paper is to present results and savings opportunities through the use of synthetic lubricants in various but common applications. Many other areas exist with the opportunity for energy savings such as in the use of more efficient drive equipment, reduced contact seals, spray mist lubrication systems and reduced friction coatings on rotating equipment such as pump impellers"

Jan 1, 1994

By Joseph J. Yancik

An exchange of coal mine specialists was made with the USSR under an "Agreement on Exchanges and Cooperation in Scientific, Technical, Cultural, and other Fields for 1972-73," which was signed by President Nixon and Chairman Breshnev on April 11, 1972.* This exchange, in the field of coal mine safety and scientific research in hazard control technologies, was one of 16 technical exchanges covered under the above agreement. A six-man USA delegation visited the Soviet Union from September 9 to September 21, 1973. The delegation visited four deep mines, three in the Donets Basin and one in the Moscow Basin, a State Safety Research Institute, a Mine Research Station and associated Research and Design Institute, two Research and Design mining equipment institutes, and a Trade Union-sponsored health sanitarium. In Moscow, the delegation received a briefing on the Soviet coal industry from First Deputy Minister Vladimir Fedanov. A similar briefing was given to us on the Donets coal basin by the Deputy Minister S. Saratikyanz of the Ukrainian Coal Ministry. Lengthy technical discussions were held with the mines staff and research personnel at the institutes we visited. In addition, we had detailed discussions with key staff members of two combinats "Donetskugol" and "Tulaugol." In all these meetings, principal topics were matters of safety related to hazards associated with face mechanization, coal transport, methane gas control measures, gas outbursts, coal and rock outbursts, fire fighting add control, explosion suppression and control measures and other related hazard factors. There was also much discussion on miner training, miner's attitudes toward safety and accident prevention practices, and preparation and enforcement of safety rules and regulations. The delegation was very warmly received and constant attention was given to our needs. Our numerous questions were answered with candor although quite often in not as much detail as we would have liked.

Jan 1, 1974

By M. L. Bakker

Keywords: Pyrometallurgy, top submerged lance (TSL), nickel, PGM, calcium ferrite, lime ferrite The ISASMELT? top submerged lance (TSL) bath smelting process was developed in Mount Isa, Australia by Mount Isa Mines Limited (now a subsidiary of Xstrata plc) during the 1980s. By the end of 2011, the total installed capacity of the ISASMELT? technology will exceed 9 000 000 metric tons per year of feed materials in copper and lead smelters around the world. Commercial plants, operating in Belgium and Germany, are also batch converting copper materials in ISASMELT? furnaces. This TSL technology is equally effective for continuous converting processes, whereupon it is called ISACONVERT?. This paper presents the recently patented ISACONVERT? process for the continuous converting of nickel and Platinum Group Metal (PGM) containing mattes using the calcium ferrite slag system. The paper focuses on the potential application of the ISACONVERT? technology to existing nickel and PGM smelting complexes.

Jan 1, 2011

By G. R. Leverant

RECENT investigations1,2 of the low-cycle fatigue behavior of pure copper under strain cycling conditions have shown that a unique saturation stress level is eventually attained for each value of applied plastic strain amplitude. The dislocation substructure of copper at the saturation stress level is in the form of cells whose diameter decreases with increasing saturation stress level, i.e., plastic strain amplitude. In addition, both the saturation stress level and the cellular substructure are completely reversible. That is, the saturation stress level and accompanying cell size are determined solely by the present conditions of testing and are, therefore, independent of any previous cyclic history. The mechanical and substructural reversibility observed in pure copper, which has a relatively high stacking fault energy, is not observedz for Cu-7.5A1 which has a much lower stacking fault energy. This implies that easy cross slip (wavy slip) is a prerequisite for reversible fatigue behavior. A dispersion of fine, nondeformable particles of a second phase in a metal matrix tends to stabilize substruc- tures introduced by forming operations during subsequent elevated-temperature heat treatments.3 This raises the question as to whether a finely dispersed second phase can induce an element of irre-versibility into the cyclic deformation behavior of a wavy slip material at room temperature, due to partial stabilization of the initially introduced substructure. Since nickel has a higher stacking fault energy than copper,6 pure nickel should be characterized by cyclic reversibility. Therefore, TD-nickel* (Ni-2ThO.r) was

Jan 1, 1968

By P. B. Barton, P. M. Bethke, R. O. Rye

Rhyolitic welded-tuff wallrocks of the epithermal base and precious metal veins of the Creede district were pervasively altered by the addition of more than two billion metric tons of potassium some 1.5-2 million years before mineralization. Sodium, calcium and magnesium were strongly depleted, yielding a nearly binary quartz + potassium feldspar assemblage containing as much as 13 weight percent K 0. This large-scale metasomatism, originally noted by Steven and Rattle (1965), took place progressively by initial alteration of plagioclase phenocrysts to orthoclase or microcline followed by alteration of the groundmass feldspar to orthoclase and gradual change of the sanidine phenocrysts to more Or-rich compositions. Oxygen isotope and chemical studies show that the metasomatism resulted from the interaction of the tuffs with deeply circulating heated ground water and suggest that the potassium metasomatism of rhyolitic rocks is the facies equivalent of propylitization of volcanic rocks of more basic composition.

Jan 1, 1985

By Savage E. N

Two genetic types of base metal deposits occur in the Wainivesi area of central eastern Viti Levu. The Wainivesi deposit is now considered to be a stratiform volcanogenic type, and the Wailotu and Wainiviti deposits are described as contact metasomatic with some hydrothermal manifestations. The Wainivesi mineralization is correlated with the Tertiary "e" stage, i.e. uppermost Oligocene-Iowermost Miocene. Tertiary "e" stage rocks in Fiji are therefore potential ore producers of stratiform volcanogenic type. On the basis of plate tectonics with Fiji part of the New Hebrides Arc prior to rifting apart in the late Miocene, stratiform volcanogenic deposits of the Wainivesi type may also occur in rocks of comparable type and age in the New Hebrides.

Jan 1, 1976

By P Stephenson, G Mosher, M Berry, C Arnold, P Stoker

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Globally, private minerals companies considering the transition to a public company and entrepreneurs looking to create a new public company through, for example, an initial public offering or by a reverse takeover have many options. For companies with assets around the Pacific Rim, there are arguably five key stock/securities exchanges that actively promote international minerals company listings, and these are located in Australia, Canada, Hong Kong, Singapore and the United Kingdom.Listing on any of these exchanges requires a range of technical, commercial, financial and legal documentation. Each exchange has specific rules and requirements for technical documentation to support the listing process. Once listed, each exchange also has specific rules for technical information to meet ongoing compliance requirements. The nature and detail of this documentation differs for the five exchanges.This paper presents statistics on the minerals company listings on each exchange and provides an overview of the technical documentation required to prepare for an initial listing and ongoing compliance.CITATION:Berry, M, Stoker, P, Stephenson, P, Arnold, C and Mosher, G, 2015. Technical considerations of public listing and ongoing compliance for minerals companies , in Proceedings PACRIM 2015 Congress, pp 101–108 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By M. L. Requa

In the fall of 1910, the Nevada Petroleum Co., operating in the Coal-inga field in California, determined to drill a number of wells with rotary tools, in order to prove conclusively the relative value of the rotary as compared with the standard rig. At that time, the rotary was but little known in California and its proposed introduction met with considerable criticism on the part of the operators and quiet opposition among the standard drilling crews. There were few men available who were competent to handle a rotary outfit, and these few had had but little experience in California fields. Machines as then built were much inferior to those now used, being lighter in construction and of a poorer quality of material. The shells encountered at depths between 1,700 and 2,000 ft. seemed to be too hard to permit of successful drilling, and at these depths the rig was changed over to standard tools and by them completed. Because of the heavy depreciation, the time lost in converting from rotary to standard, and the comparatively small profit, it was concluded that unless in the future there was some material improvement in rotary rigs, nothing would be gained by drilling with rotary tools upon this property. Little or no drilling has been done upon the property since that time, but in the meantime a large number of men have been trained in the use of the rotary; in fact, many standard-tool men have abandoned standard drilling and, starting in as roustabouts, have become thoroughly competent rotary operators. The improvements in the machinery have been such as to remove many of the objections and the rotary drilling of to-day is in every way superior to that of 1910. In contrast, a well drilled recently by the Kern Trading & Oil Co., in the east side Coalinga field may be cited. The first 2,500 ft. was drilled in 24 days and it is confidently expected that the water string will be set with a rotary at 3,400 ft.—a record obviously far beyond that made in 1910 by the Nevada Petroleum Co. The records herewith are published with the hope that some one having more recent data will publish them so that comparison may be

Jan 1, 1915

By W. M. Ma, Daniel W. H. Su, K. Centofanti, Yi Luo, W. L. Zhong, Syd S. Peng

6.1 INTRODUCTION A surface structure will suffer damage when the additional stresses induced by ground deformations associated with surface subsidence, plus the original stress introduced by construction de¬sign, exceed the strength of the structural elements. In this con¬text, there are two methods available for preventing and control¬ling surface structural damage: one is to strengthen the structure and the other is to design the mining operations such that ground deformations at the structure site can be reduced to an acceptable level. Mining operations include panel layout and mining tech¬niques. These methods are detailed in this chapter. It must be noted that most prevention/control methods men¬tioned in this chapter are used in the countries where the reference papers are cited. In the United States, the coal operators are not required to take those measures mentioned in this chapter. Some of the methods described in this chapter cannot be implemented with¬out changes in the current mining practice as permitted by laws. In addition cost of implementing those methods are not considered here. 6.2 PANEL LAYOUT As shown in Figs. 2.9, 2.10, and 2.11, permanent ground deformations in a subsidence basin mainly concentrate near the edges of the underground opening, and can be divided into four zones. A structure located in different zones will be subjected to different types and magnitudes of ground deformations. In laying out the panels, Table 5.1 and Figs. 2.9, 2.10, and 2.11 could be taken into consideration. Attempts could be made to avoid placing the structure on a location where the ground deformation to which that structure is sensitive is at its maximum. Therefore rational design of the panel is the simplest way to reduce structural defor¬mations. Panel design involves the determination of panel dimension, panel edge location, direction of face advance, and use of yield chain pillars. A. Panel Dimension Since longwalls in the US employ a multiple-entry system, where rows of chain pillars are left unmined, subsidence over those chain pillars is usually smaller. Therefore, whenever possi¬ble, the panel dimension could be designed such that a major structure or structures are over those unmined chain pillars, be¬tween adjacent panels, or some distance beyond both ends of the panels. At the center of the supercritical final subsidence basin, a structure will not be subjected to any final or permanent ground deformations. In order to create such a condition, the panel width must be such that the structure will be located beyond the major influence zone of the final subsidence basin, the minimum dimen¬sion of which must be: [ ] where L is the width or length of the final mined out gob, t is the width or length of the structure to be protected, h is mining depth and [ ] s is the angle of full subsidence. B. Panel Edge Location Wherever there is a permanent panel edge, there are large ground deformations induced on the surface on both sides of the permanent panel edge. Therefore whenever possible the panel di¬mension should be designed such that the permanent panel edges could be located in the areas with the least impacts. In terms of permanent edge location, it is best to eliminate any permanent panel edge under a structure or groups of structures. If this cannot be done, the panel should be lengthened to reduce the number of permanent panel edges, or narrower multiple panels advancing in the same direction in a staggered manner could be employed. If the structures are located in Zones II and III, the longer dimension of the structure must be parallel to the nearest perma¬nent edge (Fig. 6.1). But in Zone IV, the longer dimension should be tangential to the corner of the permanent panel edge. If the structure is inclined to the permanent panel edge, it will be sub¬jected to twisting and shearing. C. Direction of Face Advance The direction of face advance should be parallel to the long axis of the structure. But if the structure is to be located at or close to the center of the final subsidence basin, the direction of face advance should be perpendicular to the long axis of the structure. Careful choice of the direction of multiple face advance is the most effective way to reduce structural deformation and thus dam¬age. This applies the principle of overlapping and cancellations of ground deformations, due to multiple face advance, at the right time and at the right intensity, e.g., opposing tilts, concave and convex curvatures, tensile and compressive strains are induced simultaneously on the structure to be protected by two or more faces. D. Use of Yield Chain Pillars In US longwall panels there are generally two or three rows of stiff chain pillars between the panels. The combined width of the chain pillars ranges from 100 to 350 ft(30 to 107m). depending on mining depth. In general, surface movement above the chain pil¬lars after the panels on both sides have been extracted is much smaller, as compared to that in panel center. Thus in order to create critical or supercritical width of opening and eliminate sur¬face bumps over the chain pillars, yield chain pillars may be em¬ployed (Jarosz and Karmis, 1986). However if yield pillars are to be used, it must be designed such that it yields totally right after the panels on both sides have been extracted. Unfortunately cur¬rent yield pillar design techniques cannot predict when and how much it will yield. In summary, whenever possible attempts could be made to lay out the panel in such a way that surface structures are located above chain pillars between panels or above solid coal beyond both ends of the panels. In those areas the surface structures will most likely be unaffected, or if affected, the damage is so minor that no remedial measures are necessary. 6.3 CONTROLLED MINING TECHNIQUES Several mining techniques are available for reducing the sur¬face ground deformations of specific types. Regardless of tech-

Jan 1, 1992

By Maria D. Mastalerz, Wei Wang, Maria E. Holuszko, Amit Kumar

In this study, the micro-FTIR analysis was used to investigate in-situ surface properties of coal and its components (macerals) and these were directly correlated to the coal hydrophobicity as measured by the contact angle before and after reagent addition to understand the suitability of the reagent for flotation. The micro-FTIR technique can provide a semi-quantitative analysis of the chemical functional groups on coal surface, exactly where the contact angle is being measured. Selected functional groups and their ratios that provide information about aromaticity, the contribution of oxygenated groups, and aliphaticity are used to evaluate the reactivity between reagents and various coal components. The observations made in relation to the susceptibility of some reagents towards certain coal components should lead the way to a smarter way of using process design in terms of reagents selection for coal flotation.

Jan 1, 2017

By B. Devulapalli

A mathematical model of the industrial hydrocyclone based on fluid dynamics is a better alternative to the currently existing empirical models. The swirling-flow velocities are determined by solving the Navier-Stokes equations with an appropriate turbulence model. The solution of the momentum-balance equations yields the flow field inside the hydrocyclone which determines the particle trajectories, and subsequently the classification curve. The essence of the model is that the physical dimensions of the hydrocyclone and the slurry characteristics can be incorporated, and the influence of these parameters reflects on the flow predictions. The predicted tangential and axial velocities in a 250-mm hydrocyclone are in good agreement with the laser-Doppler velocimetry measurements. Finally, the predicted classification curves show good agreement with experimental data measured on a KREBS Dl0B hydrocyclone.

Jan 1, 1993

By Lawrence Mirabelli, Wayne Lidkea, Mario Paventi

On Januarv 1, 1996, INCO Limited, Tamrock OY, Dyno Nobel and CANMET formed a consortium for the development of robotic mining equipment called the Mining Automation Program (MAP). This project was a tive- [5] year research and development program that combined the talents of the above organizations to facilitate the development of mining equipment and systems for tele-remote mining. The year 2000 brings MAP to conclusion with actual production process trial testing of the developed prototype equipment and systems during the period between May and October. MAP consisted of multiple projects all of which are based on the communication system developed by INCO Mines Research and currently sold and marketed by Automated Mining Systems Limited. The main projects include the development of a positioning and navigation module (including a software mapping system that will be inherent to each piece of equipment), robotic systems for underground development and stoping operations, as well as software systems to support the use of this equipment. Included in the program was the establishment of a Research Mine, at INCO’s 175 orebody, Copper Cliff, Ontario, Canada. This facility allowed for the on-site collaboration between the companies and research organization in the design and testing of techniques and equipment to mine with TeleminingTM. Some of the prototype equipment developed through the program are: a tele-operated drilling jumbo, a tele-operated load-haul-and-dump [LHD] tram, a tele-operated production drill, a remote initiation system for programming and detonation of electronic detonators, and the development of a vatiable energy bulk emulsion explosive system, including loading equipment, to deliver the explosives to boreholes. Use of tele-operated and automated equipment for mining mandates a dramatic change in the traditional drill/blast/muck/support cycles in the underground mining process.

Jan 1, 2001

By R. R. Hartman, W. B. Agocs

IN the course of a return flight from Olympia, Wash., to Laramie, Wyo., an airborne magnetometer profile was recorded continuously. The level of flight was controlled at barometric levels along segments of the flight. Barometric altitude was changed from 3000 ft to a maximum of 12,000 ft above mean sea level to take care of topographic variations. Terrain clearance varied from 800 to 7300 ft. Horizontal positions were obtained by recording and tying to cities, towns, airports, river crossings, and other landmarks in the course of the flight. Figs. 1-6 show the course of the flight and the general geologic and tectonic features traversed. The flight line begins south of Olympia, Wash., and proceeds south across the Puget-Willemette depression to the Columbia River. Thence it proceeds eastward along the Washington-Oregon border across the Cascade Mts. and lava flows and the Umatilla basin to Pendleton, Ore. From Pendleton it traverses the Blue Mts. uplift of Oregon in a southeasterly direction, and then to the Boise basin of southwestern Idaho. The flight line swings in an easterly direction as it passes over the Snake River downwarp to the south of the Idaho batholith. It then passes over the northern portion of the Great Basin and the heavily overthrust area at the intersection of the Utah, Idaho, and Wyoming borders. The flight then assumes an easterly course to cross the series of basins and uplifts of southern Wyoming and terminates near the western flank of the Laramie uplift. It should be clearly understood that all statements in this article pertaining to the magnetics were interpreted on the assumption of elongate anomalies transverse to a single profile. Hence any theories or ideas advanced here are in line with future paths of research rather than trying to prove or disprove existing data. Magnetic Interpretation: Depth determinations were made by the slope method of Peters: which is stated as follows: "Draw a line in the maximum slope (at the point of inflection); draw a line whose slope is one-half this maximum slope; draw two lines parallel to this line tangent to the anomaly curve. The horizontal distance between the points of tangency is approximately equal to 1.6 times the depth [or the distance times 0.6251." Certain assumptions must be made for determinations of the causes of the magnetic anomalies:' 1) The anomaly is caused by a susceptibility change rather than basement relief. 2) Polarization of the basement rocks is in the same direction as the earth's inducing field. 3) The disturbing magnetic mass has a great horizontal length in comparison to its width and its sides are vertical and of great vertical extent. 4) The anomaly is unique and not affected by the anomalies from nearby sources.

Jan 1, 1957

By H. A. Wheeler

THAT lead and zinc deposits are the result of prolonged, slow deposition is the idea of most students of ore deposits, -and in many cases, where the ore-bearing solutions have been very weak or the precipitating conditions have been very feeble, the ore accumulations have undoubtedly taken a long period of time. As these two vital, conditions have been subject to great variations in the different mining camps, the following example is highly interesting in showing that deposition can be very rapid under favorable conditions, geologically speaking, and also extremely recent. In fact, the writer is inclined to regard most, if not all, of the Mississippi Valley deposits of lead and zinc as probably being very young, at least not older than Tertiary, if not Quarternary, in age. The extensive Joplin lead and zinc district, in southwestern Missouri, which is about 60 years old and has numerous mines that were abandoned from 1 to 50 years ago, shows that the lead and zinc today are in an active condition of solution and redeposition, although these two metals occur in the predominant form of sulfides. The mine waters from the older and more or less abandoned portions of the district are frequently so acid, mainly from the oxidation of associated pyrite, as to necessitate the use of wooden pipes and pumps. The first boom in the Oklahoma zinc fields, which is the southwestern extension of the Joplin district, occurred when ore was accidentally struck in drilling a water well. Among the mines then opened up was the Mission mine, at Lincolnville, Ottawa County, Okla. This mine was opened' in 1903 in lean "sheet ground," or a flat blanket formation of chert carrying disseminated zinc blende, or "jack," and galena. The ore-body was very free from iron pyrites and the concentrates were very high grade, the "mineral," or lead concentrates, assayed 80 to 85 per cent. lead and the jack, or sphalerite, assayed 60 to 65 per cent. zinc. The orebody was very shallow, occurring at a depth of 75 to 95 ft. (22 to- 28, in.) and very wet, requiring three or four pumps to handle the water. The

Jan 2, 1920

Virginia Polytechnic Institute, Department of Mining Engineering, Blacksburg, Va Otto C Burkhart, Professor of Mining. The titles of pertinent publications have been abstracted from the Bulletins on Research and Publication This material has also appeared, in most cases, under other auspices Presumably, the Bulletins whose titles are quoted may be had for the cost of postage The coals of Virginia (1927), Ceramic resources of Virginia and their development (1929), Effect of ilhum crucibles on volatile determinations of coal (1930), Possibility of briquetting southwest Virginia coals (1930), Coking of semi-anthracite coal of Virginia (in preparation), Distribution of ash in the Merrimac coal seam (1929); Unit coal studies on some Virginia coals (1931), Sulphur forms in Virginia coals (1931); Comparison of results of fusion point of coal ash obtained by two different methods

Jan 1, 1933

Scientific drilling and blasting techniques are currently being presented to the mining industry as an aid in the overall optimisation process. The degree of success in the development of these techniques over the last ten years has prompted statements that generally relate to blasting becoming a science rather than an art. Many of the techniques are currently operated or at least analysed by scientists. As such, their use has been restricted to project type activities while the more routine activities associated with day to day mining has continued to be carried out by engineering rather than scientific staff. Some of the scientific techniques will remain legitimately as a project or an occasional use facility. Generally speaking a cost/benefit analysis at a particular mine will decide the level of use. This should logically highlight a number of techniques with potential of regular mine site use. Regular mine site use implies mine site analysis and hence the gulf between the scientist and mine operator/engineer must be addressed. There are all sorts of solutions and they are not mutually exclusive. One alternative could be to increase specialisation at the mines. With "career paths" becoming more formalised the trend would seem to be away from mine site specialists unless, for instance, this specialisation was provided by term secondment from research establishments. Another alternative could be the scientists themselves applying their developmental skills to "humanise" and "package" the projects in such a manner that they can be routinely used at mines.

Jan 1, 1990

By R. D. Lindsay

"Pamour Porcupine Mines, Limited is involved in the mining, milling and primary refining of various gold, gold - copper and refractory gold ores. Pamour operates five mines in the Porcupine Mining District of Ontario, and two 2,550 t/d milling facilities.Both metallurgical facilities use conventional cyanidation technology including zinc cementation for precipitation of gold and silver from solution. The precipitation process, as applied to clarified leach solutions (less than 1 ppm suspended solids) at Pamour is called the Merrill - Crowe process. Precipitates from both milling operations are treated at Pamour's Area Refinery. Schumacher precipitates, unlike Pamour No. 1, require an ''Acid Treatment Stage"" prior to refining to remove the high contained copper. This is accomplished by leaching the precipitates initiallv with sulphuric acid to remove zinc and then with sulphuric acid and manganese dioxide to dissolve copper. Refining procedures after ''Acid Treatment"" are essentially the same for both precipitates.The following considerations highlight the basic principals applied to refining cyanidation precipitates at Pamour, including:"

Jan 1, 1986

By A. L. Blomfield

THE Golden Cycle Mining and Reduction Co. operates its custom mill at Colorado Springs on Cripple Creek ores exclusively. These ores are straight sulpho-tellurides, with practically no base metals such as Pb, Cu, Zn, As, or Sb. Upon entering the mill, the ore all passes through the sampler to storage bins, where beds of 5000 tons each are made to insure uniformity in roasting. CLASSIFICATION OF ORES For efficiency, it has been found advisable to separate the ores into two classes according to their line content. Other constituents have their effect, such as alumina and magnesia, but, speaking generally, these are roughly proportional to the line, which, as CaO, is used as the indicator. Class A contains not more than 2 per cent. CaO and comprises about 66 per cent. of the ore treated. Class B contains over 2 per cent. CaO, and comprises 34 per cent. of the ore treated. Typical analyses of both classes are as follows: Class A Class B Insol 56.70 75.90 Al203 2.30 3.40 Fe 3.26 3.48 CaO 1.57 5.12 S 1.79 1.80 Mg0 0.21 1.08 Ignition loss 3.20 6.50 99.03 97.28 The beds of each class of ore are made as large as possible with the available ore as it comes in, to avoid changing from one bed to the other any oftener than necessary. Each roaster will handle 50 percent. more of class A ore than of class B, with practically the same results. This necessitates changing the rate of feed for each new bed and tends toward a poor roast and loss of tonnage at each change.

Jan 8, 1918

By J. P. Gu, C. Beckermann

"Melt convection and macrosegregation in casting of a large steel ingot is numerically simulated. The simulation is based on a previously developed model for multicomponent steel solidification with melt convection, and involves the solution of fully coupled conservation equations for the transport phenomena in the liquid, mush, and solid. Heat transfer in the mold and insulation materials, as well as the formation of a shrinkage cavity at the top are taken into account. The numerical results show the evolution of the temperature, melt velocity, and species concentration fields during solidification. The predicted variation of the macrosegregation of carbon and sulfur along the vertical centerline is compared with measurements from an industrial steel ingot that was sectioned and analyzed. Although generally good agreement is obtained, the neglect of sedimentation of free equiaxed grains prevents the prediction of the zone of negative macrosegregation observed in the lower part of the ingot. It is also shown that the inclusion of the shrinkage cavity at the top is important in obtaining good agreement between the predictions and measurements.IntroductionMacrosegregation in large steel ingots is one of the most well-known and now classical problems in the field of solidification and casting [1]. Commonly found macrosegregation patterns in steel ingots are a positively segregated zone at the top, negative segregation near the bottom in the equiaxed zone, inverse segregation near the ingot surface, V-segregates along the centerline, and A-segregates in the columnar zone [2, 3]. It is well established that the macroscopic transport of species leading to macrosegregation can occur by a variety of mechanisms, including thermally and solutally driven natural convection of the melt in the mushy zone, flow due to solidification contraction, and the sedimentation of free equiaxed crystals. Fredriksson and coworkers [ 4,5] provide recent overviews of the solidification transport phenomena and macrosegregation in ingot casting."

Jan 1, 1999

Cyanidation and Concentration of Gold and Silver Ores. By J. V. N. Dorr and Francis L. Bosqui. Second edition, completely revised. Mc-Graw-Hill Book Co., New York. $8.50.-First issued 13 years ago, this book has become a milestone in the literature of mining and metallurgy. Mr. Dorr, with the assistance of F. L. Bosqui, has completely revised the book. Its comprehensive picture of ore dressing and hydrometallurgical methods are of importance to mining engineers and operators throughout the entire field. Operating data and methods, flowsheets, testing procedures, and many miscellaneous methods of extracting bullion are given. The book is divided into two sections, the first discussing principal unit processes involved in gold and silver recovery, and the second describing with flow diagrams a number of typical treatment plants selected from the more important gold and silver mining areas in various parts of the world. International Conference on Coal Preparation in Paris. English Language edition of transactions.-The transactions of the recent conference in Paris will be presented in the form of 6 issues of the revue de l'Industrie Minerale, and may be purchased for 3000 francs per set. About 60 papers were presented at the meeting, covering a wide range of interesting subjects. Ad- dress subscriptions to: Secretariat de la Societe de l'Industrie Minerale, 19 rue du Grand-Moulin, Saint-Etienne (Loire) France.

Jan 1, 1951